CN101848787B

CN101848787B - Pb-free solder compositions and PCB and electronic device using same

Info

Publication number: CN101848787B
Application number: CN200780100259.1A
Authority: CN
Inventors: 高明玩; 朴商福; 宋明圭; 朴玧秀; 李光烈
Original assignee: ECOJOIN
Current assignee: ECOJOIN
Priority date: 2007-08-14
Filing date: 2007-08-14
Publication date: 2013-10-23
Anticipated expiration: 2027-08-14
Also published as: WO2009022758A1; CN101848787A

Abstract

Provided is a lead-free solder composition, including at least two of tin (Sn), silver (Ag), phosphorous (P), nickel (Ni), copper (Cu), bismuth (Bi) and germanium (Ge), and including both silicon (Si) and cobalt (Co), for preventing the deterioration of workability caused by the oxidation of the solder alloy and eliminating the need of replacing the whole lead bath caused by the increase of the copper erosion during soldering, and a printed circuit board (PCB) and an electronic device using the lead-free solder. Through the lead-free solder composition including both silicon and cobalt, and the printed circuit board (PCB) and the electronic device using the lead-free solder, it is possible to constantly prevent the formation of the oxides, prevent the discoloration and the erosion of the copper pad, improve the mechanical properties and the soldering joinability while maintaining the wettability during the soldering.

Description

Pb-free solder compositions and use its printed circuit board (PCB) and electronic device

Technical field

The printed circuit board (PCB) (PCB) and the electronic device that the present invention relates to a kind of Pb-free solder compositions and use this Pb-free solder compositions, and more particularly, relate to a kind of Pb-free solder compositions and the PCB and the electronic device that use this Pb-free solder compositions that human body is had the lead (Pb) of harm that do not contain, this solder composition comprises the tin (Sn) that is added with silicon (Si) and cobalt (Co), the ternary composition of copper (Cu) and silver (Ag), add the tin in silicon and the cobalt to, copper, three grades of compositions of silver and nickel, add the tin in silicon and the cobalt to, copper, silver, nickel, the hexa-atomic composition of germanium (Ge) and phosphorus (P), perhaps be added with the tin of silicon and cobalt, copper, the four-tuple compound of phosphorus and bismuth (Bi), so that under the help of the silicon that adds therein, improve the operating efficiency of welding by constantly anti-oxidation, under the help of a small amount of silicon that adds therein, prevented variable color, and the typical welding temperature of maintenance lead-free solder and typical wetability, and the wetability that the excessive interpolation that has prevented silicon causes is deteriorated, thereby prevented the deteriorated of combinableness, and prevented oxidation, prevented copper corrosion, and under the help of a small amount of cobalt that adds therein, showing the breaking load amount that has improved combination, help load to increase articular fracture wherein, use the Pb-free solder composition with printed circuit board (PCB) and electronic device.

The invention still further relates to a kind of high temperature lead-free solder composition in temperature use more than 400 ℃ and PCB and the electronic device that uses this Pb-free solder compositions, and be particularly related to a kind of composition of high temperature lead-free solder and PCB and the electronic device of this high temperature lead-free solder composition of use, said composition comprises the silicon that is added with and the tin of cobalt, the copper binary composition, be added with the tin of silicon and cobalt, copper, nickel, phosphorus four-tuple compound, under the help with the silicon that adds therein, improve the operating efficiency of welding by constantly anti-oxidation, under the help of a small amount of silicon that adds therein, prevented variable color, and the typical welding temperature of maintenance lead-free solder and typical wetability, and the wetability that the excessive interpolation that has prevented silicon causes is deteriorated, thereby prevented the deteriorated of combinableness, and prevented oxidation, prevented copper corrosion, and under the help of the minute quantity cobalt that adds therein, showing the breaking load amount that has improved combination.

The invention still further relates to PCB and the electronic device of a kind of Pb-free solder compositions for dilution and this Pb-free solder compositions of use; And be particularly related to PCB and the electronic device of a kind of Pb-free solder compositions for dilution and use said composition, said composition comprises the tin that is added with silicon and cobalt, nickel, the phosphorus ternary composition, be added with just tin of silicon and cobalt, silver binary composition or be added with silicon and the tin of cobalt, silver, the phosphorus ternary composition, under the help with the silicon that adds therein, improve the operating efficiency of welding by constantly anti-oxidation, under the help of a small amount of silicon that adds therein, prevented variable color, prevented under the help of the cobalt of the minute quantity of adding therein that the wetability that the excessive interpolation of silicon causes is deteriorated, thereby prevented the deteriorated of combinableness, by they have been improved the performance of control the content of copper and welding performance as diluent.

Background technology

Lead-containing alloy begins from very early the time just to be used widely.Especially, for a long time, tin-lead solder is used for parts are arranged on printed circuit board (PCB) (PCB) as bond material.Welding is a kind of technology of using the solder bonds material, and is used for Small electronic component such as semiconductor chip and semiconductor resistor are arranged on printed circuit board (PCB) always.Use the combination technology of this scolder to be widely used in Small electronic component such as semiconductor chip and semiconductor resistor are arranged on the printed circuit board (PCB).

Recently, along with electronic product becomes less, weight is lighter, and have stronger function, need more thickly installation component, thereby need the combination technology of more advanced use scolder.In addition, although tin and plumbous binary eutectic alloy have been used as the material for welding usually, lead is the factor of environmental pollution, is therefore controlling at present its use.This is because lead not only causes environmental pollution, and human body is had harmful effect.

Therefore, now, use plumbous in the solder alloy is subject to control or restriction, thereby is developing various eco-friendly lead-free solders.Yet, to compare with solder containing pb, common Pb-free solder compositions has high fusing point and poor wetability.In addition, common Pb-free solder compositions is owing to the severe oxidation that melts scolder has poor welding job efficient.In addition, of poor quality, the poor reliability of PCB assey by welding.

In addition, do not have a kind of lead-free solder, it has enough welding combinableness such as wetability, and has simultaneously i.e. 183 ℃ the fusion temperature of fusion temperature that is similar to common scolder (Sn37Pb).Therefore, lead-free solder only improves use in welding process such as baking box replacing now.This is because only have limited metal, and for example copper, silver, zinc, bismuth, indium are used as reducing the alloying element of fusion temperature.

In addition, common lead-free solder neither has enough scolder combinablenesses such as wetability and corrosion resistance, does not also have the common tin solder (Sn that contains ₃₇Pb) near the low melting glass the melt temperature (183 ℃).Therefore, in most of lead-free solders, add a small amount of metal for reducing melt temperature in lead, for example copper, silver, zinc, bismuth, indium reduce the fusion temperature of lead-free solder.Yet, do not further developing aspect the fusion temperature that reduces lead-free solder.

Therefore, mainly use now the melt temperature scope from the silver alloy of 220 ℃ to 230 ℃ SnAgCu and the non-silver alloy of SnCu.As mentioned above, with regard to melt temperature, scolder has been developed dead end, and therefore, the exploitation of scolder is just concentrating on performance, operating efficiency, quality and the reliability of improving scolder.

Compare with solder containing pb, lead-free solder has high melt temperature, needs expensive raw material, and generates a large amount of slags, has increased production cost.In addition, for lead-free solder, the oxide in the fusion welding is attached in the welding band (welding portion) of PCB assey, causes assemble welding q﹠r variation.

In order to overcome these problems, KR10-0327767, JP3622788 and JP 3296289 disclose and a kind ofly have been added with element such as phosphorus, nickel, germanium, gallium in case the SnAgCu of oxidation is solder alloy and SnCu is alloy.Yet the interpolation of element such as germanium, gallium, nickel is limited, because it can improve fusion temperature, and can owing to sclerosis causes the welding portion cracking, cause reliability deteriorated when through heat-treated and heat fatigue.

Especially, the interpolation meeting of a large amount of phosphorus increases the fragility of welding portion owing to the sclerosis of solder alloy.Phosphorus rises to the surface of fusion welding to prevent the oxidation of fusion welding.Yet under about 260 ℃ welding temperature, phosphorus only has of short duration impact owing to its high volatility to the formation that prevents slag (oxide).Particularly, for wave soldering and immersed solder, after bath was filled hundreds of kilograms of scolders, this process continued the several months usually, only adds the scolder that a small amount of scolder compensates consumption.Therefore, in this process, the interpolation of phosphorus only has of short duration impact to the formation that prevents slag, and impact is not lasted for a long time.

High temperature lead-free solder replaces plumbous as raw material with expensive tin, and compares with leaded scolder, experience significant oxidation (slag formation) during fusing (welding), and this can increase user's financial burden.In addition, the oxide that mixes in the fusion welding can be combined in the welding band (welding portion) of PCB assey, and this can cause the deteriorated of soldering group accessory.

Especially, the welding temperature of high-temperature solder causes the remarkable increase that slag forms, thereby causes operating efficiency deteriorated far above the welding temperature of the scolder that is used for general fluctuation.For head it off, it is that solder alloy is prevented oxidation that JP2004-154864A and JP2004-181458A have described the SnCu that wherein is added with element such as phosphorus, nickel, germanium and gallium.

Yet germanium, gallium, nickel are expensive materials.In addition, when addition surpassed certain level, they can cause crack and heat fatigue in standing the welding portion of thermal process, reduced reliability.Especially, when phosphorus adds in a large number, because the overvulcanization of solder alloy can increase the fragility of welding portion.

In addition, for the high-temperature solder alloy, phosphorus rises on the surface of solder bath, to prevent the oxidation of fusion welding.Yet the volatilization temperature of considering phosphorus is 380 ℃, and the common operation of high-temperature solder is to carry out in about 520 ℃ welding temperature at about 420 ℃, and phosphorus is on preventing seldom the impact of being formed with of slag (oxide).

In addition, for immersed solder, after bath was filled scolder, this process continued the several months usually, only adds the scolder that a small amount of scolder compensates consumption.Therefore, only can prevent in short time that effect from can not continue a very long time in the filling that is formed on initial bath of slag.

In addition, if nickel content be increased to 0.1% with on when increasing temperature, the overvulcanization of solder alloy can increase fragility, deteriorated welding performance.

In addition, the high-temperature solder alloy uses in 460 ℃ of-540 ℃ of temperature, and common solder alloy is 260 ± 10 ℃ of lower uses of temperature.Therefore, in the high-temperature solder alloy, produce more oxide, produce with higher speed, therefore than needing higher antioxygenic property in the common solder alloy.

In addition, because the erosion of copper packing material among the PCB, when copper concentration is increased to 1% when above, the fusion temperature of scolder increases sharply, wetability decline.This can require to change whole lead bath maybe can cause cracking.

In addition, when only adding silicon, can improve the impact on slag and variable color.Yet, if when the content of silicon surpassed a certain quantity, the key property of scolder was that combinableness can reduce.The element that therefore, other need to be arranged.

Summary of the invention

Technical problem

One embodiment of the present invention relates to provides a kind of Pb-free solder compositions of silicon and minute quantity cobalt that comprises in order to prevent oxidation, keep wetability, prevent variable color, improve mechanical performance at weld period, prevent the erosion of copper packing material and improve the combinableness of welding, and PBC and the electronic device that uses this Pb-free solder compositions is provided.

Technical scheme

According to an aspect of the present invention, a kind of Pb-free solder compositions is provided and has used printed circuit board (PCB) (PCB) and the electronic device of said composition, said composition comprises copper from 0.1wt%-2wt%, the silver from 0.1wt% to 4.0wt%, be tin from the silicon of 0.001wt%-0.05wt%, from cobalt, the surplus of 0.001wt%-0.01wt%.

According to a further aspect in the invention, a kind of Pb-free solder compositions is provided and has used printed circuit board (PCB) (PCB) and the electronic device of said composition, said composition comprises copper from 0.1wt%-2wt%, be tin from 0.1wt%-4.0wt% silver, from 0.001wt%-0.05wt% silicon, from 0.001wt%-0.01wt% cobalt, surplus.

According to a further aspect in the invention, PCB and the electronic device of a kind of Pb-free solder compositions and use said composition are provided, said composition comprises copper from 0.1wt%-2wt%, from the silver of 0.1wt%-4.0wt%, from the nickel of 0.001wt%-0.5wt%, from the germanium of 0.001wt%-0.1wt%, from 0.001wt%-0.2wt% phosphorus, from the silicon of 0.001wt%-0.05wt%, from the cobalt of 0.001wt%-0.01wt%, surplus is tin.

According to a further aspect in the invention, PCB and the electronic device of a kind of Pb-free solder compositions and use said composition are provided, said composition comprises copper from 0.1wt%-2wt%, from the nickel of 0.001wt%-1.0wt%, from the phosphorus of 0.001wt%-0.2wt%, from the silicon of 0.001wt%-0.05wt%, from the 0.001wt.%-0.01wt% cobalt, surplus is tin.

According to a further aspect in the invention, PCB and the electronic device of a kind of Pb-free solder compositions and use said composition are provided, said composition comprises copper from 0.1wt%-2wt%, from the bismuth of 0.1wt%-17wt%, from the phosphorus of 0.001wt%-0.2wt%, from the silicon of 0.001wt% to 0.05%, from the cobalt of 0.001wt%-0.01wt%, surplus is tin.

According to a further aspect in the invention, PCB and the electronic device of a kind of high temperature lead-free solder composition and use said composition are provided, said composition comprises copper from 2wt%-5wt%, from 0.001wt%-0.05wt% silicon, from 0.001wt% to 0.01wt% cobalt, surplus is tin.

According to an aspect of the present invention, PCB and the electronic device of a kind of high temperature lead-free solder composition and use said composition are provided, said composition comprises copper from 2wt%-5wt%, from the nickel of 0.001wt%-1.0wt%, from the phosphorus of 0.001wt%-0.2wt%, from the silicon of 0.001wt%-0.05wt%, from the cobalt of 0.001wt%-0.01wt%, surplus is tin.

According to an aspect of the present invention, PCB and the electronic device of a kind of Pb-free solder compositions for diluent and use said composition are provided, said composition comprises nickel from 0.001wt%-0.1wt%, from the phosphorus of 0.001wt%-0.2wt%, from the silicon of 0.001wt%-0.05wt%, from the cobalt of 0.001wt%-0.01wt%, surplus is tin.

According to a further aspect in the invention, PCB and the electronic device of a kind of Pb-free solder compositions for diluent and use said composition are provided, said composition comprises the silver of 0.1wt%-4wt%, the phosphorus of 0.001wt%-0.2wt%, the silicon of 0.001wt%-0.05wt%, the cobalt of 0.001wt%-0.01wt%, and surplus is tin.

Beneficial effect

According to an illustrative embodiment of the invention, circuit board and the electronic device of this Pb-free solder compositions and this Pb-free solder compositions of use, include simultaneously silicon and cobalt, with weld period constantly anti-oxidation, keep wettability, prevent variable color, improve mechanical performance, prevent the erosion of copper packing material, and improve the combinableness of welding.

The accompanying drawing summary

Fig. 1 illustration the lead-free solder by one embodiment of this invention prevent the principle that oxide forms.

Fig. 2 illustration according to the principle of Fig. 1, the result who under the initial state of slag test, carries out elementary analysis.

Fig. 3 illustration according to the principle of Fig. 1, in slag test 3 results that as a child carried out elementary analysis.

Fig. 4 illustration according to the principle of Fig. 1, at the silicon peak that test is measured by Auger electron spectroscopy (AES) afterwards.

Fig. 5 illustration according to the principle of Fig. 1, the SiO that after test, measures by AES ₂The peak.

Fig. 6 illustration the high temperature lead-free solder by an embodiment of the present invention prevent the principle that oxide forms.

Fig. 7 illustration in slag test 3 results that as a child carried out afterwards the high-temperature solder elementary analysis by AES.

The specific embodiment

Fig. 1 has illustrated with comprising and has been added with a small amount of P and Si prevents that the SnAgCu that oxide forms from being the fluctuation welding method of the solder alloy of alloy.The P that adds and the part consumption of Si are in the deoxidation of fusion welding matrix alloy, and another part is dissolved in the fusion welding matrix alloy.Yet because P and the solubility of Si in molten tin are very little, most of P that adds and Si are because the difference of proportion rises to the surface of fusion welding matrix alloy.Then, be formed on lip-deep phosphorous oxides and silicon oxide film and intercepted contacting of airborne oxygen and fusion welding, prevent the formation of lead-free solder oxide.

As mentioned above, the lip-deep a part of P of fusion welding matrix alloy forms oxide-film.Yet the lip-deep most of P of fusion welding matrix alloy has been evaporated in the air, thereby has reduced gradually the effect that prevents that oxide from forming on the fusion welding surface.On the contrary, lip-deep Si is not evaporated in the air, thereby can constantly form oxide-film on the fusion welding surface, thereby prevents that the interaction energy that oxide forms on the fusion welding surface from continuing the long time.

In addition, when adding the minute quantity cobalt, be dissolved in the formation that cobalt in the fusion welding also can prevent oxide.

Fig. 2 illustration the results of elemental analyses that obtains by Auger electron spectroscopy (AES).Comprising of this elementary analysis: add the cobalt of the silicon of phosphorus, 0.05 quality % of nickel, the 0.005 quality % of copper, the 0.06 quality % of 0.5 quality % and 0.05 quality % in tin, melting is also cast this solder alloy and is become ingot, cutting ingot casting, the cutting surfaces of polishing ingot casting and the cut surface that polishes by the AES analysis.Fig. 3 illustration use the ingot casting according to above-mentioned technical process manufacturing with reference to Fig. 2 to carry out slag test (oxidation test) after 3 hours at 260 ℃, carry out the result of elementary analysis by AES.As shown in Figure 2, in the initial state of slag test, P rises to the surface of ingot casting, so that most of P concentrates on upper area, accounts for 1.86% of gross mass, silicon be distributed in P below.This can find out from putting 1,2 and 3 component data, use respectively in Fig. 2

Mark is represented.

As shown in Figure 3, carry out the slag test after 3 hours at 260 ℃, locate (upper area) Si content (0.08 quality %) at 1 and be higher than P content (0.06 quality %), locate Si content (0.19 quality %) at 2 and also be higher than P content (0.13 quality %).In addition, according to the peak value that Auger electron spectroscopy detects, Si oxide (estimation is silica) is located to form at 1.Yet, 2 and 3 locate, detect the peak value of silicon, rather than the peak value of silica, as shown in the figure 4.

Therefore, can be following consideration.In initial state, because the difference of proportion, phosphorus, then be the surface that silicon rises to the fusion welding in the fusion welding.After this, evaporation in lip-deep most of phosphorus short time of fusion welding only has small part phosphorus to contact with airborne oxygen and forms oxide-film.On the contrary, most of silicon forms silicon oxide film such as SiO ₂Film has prevented the oxidation of fusion welding.

Fig. 6 illustration the high temperature lead-free solder composition by according to an embodiment of the present invention prevent the principle that oxide forms.As shown in Figure 6, when using solder alloy to carry out immersed solder on the plumbous surface of electronic component, this scolder by in the SnCu matrix alloy, adding phosphorus and silicon in case the block compound forms makes, a small amount of a part of P that adds and Si consume in the deoxidation of fusion welding matrix alloy, and then remaining P and Si are dissolved in the fusion welding matrix alloy.Yet because P and the solubility of Si in molten tin are very little, the phosphorus of most of surplus and silicon are owing to the difference of proportion rises to the surface of fusion welding matrix alloy.The phosphorous oxides that forms from the teeth outwards and the film of Si oxide have intercepted contacting of airborne oxygen and fusion welding, have prevented the formation of lead-free solder oxide.

In 260 ℃ common welding, the lip-deep a part of part P of fusion welding matrix alloy has formed oxide-film.Yet the lip-deep most of P of fusion welding matrix alloy is evaporated in the air, thereby has reduced gradually the effect that prevents that oxide from forming on the fusion welding surface.On the contrary, lip-deep Si is not evaporated in the air, thereby can constantly form oxide-film on the surface of fusion welding, thereby prevents that the interaction energy that oxide forms on the fusion welding surface from continuing the long time.

Fig. 7 illustration the result who carries out the high-temperature solder elementary analysis by AES after 3 hours in slag test.Specifically, Fig. 7 illustration in 420 ℃ of slags test, 3 results that as a child carried out the high-temperature solder elementary analysis by AES, to prove above-mentioned phenomenon.As shown in Figure 7, the upper area on the ingot casting surface does not detect phosphorus at all, and detects the Si of 1.09wt%.This tells us, although the major part of P from the surface evaporation of fusion welding, silicon even still exist at high temperature has formed silicon oxide film on the surface of fusion welding.The lip-deep silicon oxide film of fusion welding has intercepted fusion welding and has contacted in case oxidation with airborne oxygen.

When only adding silicon, variable color and slag effect are improved.Yet when the interpolation of silicon surpassed a predetermined quantity, the fusion temperature of solder alloy descended, and wetability reduces, thereby combinableness descends, and this is the fundamental characteristics of scolder.Therefore, by adding the cobalt of minute quantity, can obtain to keep wetability, the remarkable result that anti-oxidation, variable color and copper corrode.

Performance and purposes according to component in the Pb-free solder compositions of embodiment hereinafter will be described.

Tin (Sn) is the key component in the lead-free solder, and as parent metal.

Be used for common wave soldering solder alloy the copper slight reduction melting temperature of solder alloy and the bond strength of weld seam.At this moment, when the addition of copper was lower than 0.1wt%, effect was not enough, and when the addition of copper during greater than 2wt%, the solution temperature of solder alloy increases.Be used for the addition of solder alloy copper of common wave soldering preferably from 0.1wt%-2wt%.In addition, at least in the high temperature immersed solder of 400 ℃ of uses with the copper in the solder alloy, addition during less than 2wt% on improving the not impact of solder alloy fusion temperature.When addition during greater than 5wt%, high temperature immersed solder has excessively improved fusion temperature with the copper in the solder alloy and has caused the overvulcanization of solder alloy.Therefore, high temperature immersed solder is 2wt%-5wt% with preferred copper content in the solder alloy.

Silver (Ag) is nontoxic.In addition, silver has reduced the fusion temperature of solder alloy, has improved the dispersiveness of parent metal, and has improved thermal fatigue property.When the addition of silver during less than 0.1wt.%, the effect of silver is inadequate.When the addition of silver during greater than 4wt%, melt temperature raises.Therefore, the preferred silver content 0.1wt%-0.4wt% in the solder alloy.

Phosphorus (P) has prevented the formation of oxide in welding process, has improved operation.When the addition of phosphorus during less than 0.001wt%, without any effect.When the addition of phosphorus greater than 0.2wt%, melt temperature raises.Therefore, preferred silver content is 0.001wt%-0.2wt% in the solder alloy.

Germanium (Ge) has improved wetability and has prevented oxidation.When germanium addition during less than 0.001wt%, without any effect.When the addition of germanium during greater than 0.1wt%, the cost of raw material increases fast, and fusion temperature raises.Therefore, preferred Ge content is 0.001wt%-0.1wt% in the solder alloy.

Nickel (Ni) has prevented the erosion of copper packing, has improved bond strength.When the addition of nickel during less than 0.001wt%, without any effect.When the addition of nickel during greater than 0.5wt%, fusion temperature increases rapidly and occurs the overvulcanization of solder alloy.Therefore, preferred nickel content is 0.001wt%-0.5wt% in the solder.

Bismuth (Bi) has reduced fusion temperature and has improved bond strength.When the addition of bismuth is no more than 0.1wt%, do not reduce the effect of melt temperature.When the addition of bismuth during greater than 17wt%, the fusion temperature of Sn alloy is reduced to about 210 ℃, or solder alloy generation overvulcanization.Therefore, preferred bi content is 0.1wt%-17wt% in the solder.

According to embodiment, silicon (Si) is main alloy element.Silicon has the characteristics of rising and is nonvolatile.Therefore, by add a small amount of silicon in the scolder matrix alloy, can prevent that oxide from forming and interaction energy is kept the long time, this is different from phosphorus.By in the scolder matrix alloy, adding a small amount of silicon, the variable color of rear welding region can be prevented from significantly welding and the erosion that stops copper can be strengthened, keep simultaneously temperature and the wetability of common lead-free solder.

Cobalt (Co) does not have the characteristic of rising.Yet, by adding together a small amount of cobalt with silicon, can prevent that oxide from forming, variable color and erosion, thus improved welding performance and processability, and keep wettability.

Embodiment 1

This embodiment provides a kind of Pb-free solder compositions and has used PCB and the electronic device of this Pb-free solder compositions, and said composition comprises that silver, the copper of 0.1wt%-2wt%, the silicon of 0.001wt%-0.05wt%, the cobalt of 0.001wt%-0.01wt%, the surplus from 0.1wt%-4.0wt% is tin.

Hereinafter illustrate that with reference to Fig. 1 the composition of silicon and cobalt is to the effect of anti-oxidation.

Fig. 1

(Amount of oxidation: the amount of oxide; Oxidation rate: oxidation rate; Comparativeexample: comparing embodiment; Example: embodiment; After after 1hour:1 hour; After after 2hours:2 hour; After after 3hours:3 hour.)

Fig. 1 illustration the test data of amount of the oxide measured by the following method.Silicon and cobalt are added in the predetermined matrix alloy.The alloy melting that obtains is made solder composition.Solder composition is heated to 260 ℃ in heating plate in the SUS of 160mm diameter crucible.Then, the agitator of solder composition with diameter 140mm stirred respectively 1 hour, 2 hours and 3 hours with the 60rpm mixing speed, therefrom extract oxide and weighing at every turn.

As shown in fig. 1, be 479g, 540g after 2 hours, 564g after 3 hours after the amount of the oxide that forms is respectively 1 hour in the Sn3Ag0.5Cu that includes 0.5wt% copper, 3wt% silver and surplus tin, therefore, the oxide aggregate that formed in 3 hours is 1,582g.295g after the amount of the oxide that forms in the Sn3Ag0.5Cu0.005P of the phosphorus that comprises 0.5wt% copper, 3wt% silver, 0.005wt% and surplus tin is respectively 1 hour, 325g and 390g after 3 hours after 2 hours, therefore, the oxide aggregate that formed in 3 hours is 1,010g.This is because squama is used for having reduced the amount of oxide.

Yet, when adding 0.005wt% silicon among the Sn3Ag0.5Cu, the amount of oxide respectively be 270g after 1 hour, 302g after 2 hours, 345g after 3 hours, therefore, the oxide aggregate that formed in 3 hours is 917g, and this is less than the amount of the oxide that forms among the Sn3Ag0.5Cu0.005P without silicon.In a word, when the addition of P was 0.005wt%, within 2 hours to 3 hours time period, the quantity of slag significantly increased.Yet, when the addition of silicon is 0.005wt%, similar with the quantity that forms 1 hour to 2 hours time period in the quantity of the oxide that forms from time period of 2 hours to 3 hours.Therefore, can conclude that silicon is more effective than phosphorus aspect constantly anti-oxidation.

In addition, can find out that when adding 0.05% silicon, the amount of oxide further reduces.

When in Sn3Ag0.5Cu0.005Si, adding the cobalt of 0.005wt%, the amount of oxide is respectively 215g after 1 hour, 240g and 264g after 3 hours after 2 hours, therefore, the oxide aggregate that formed in 3 hours is 719g, can find out from this result, than the situation of Sn3Ag0.5Cu0.005P and Sn3Ag0.5Cu0.005Si, the amount of oxide reduces.

That is to say, the cobalt of (0.005wt%) by in Sn3Ag0.5Cu0.005Si, adding minute quantity, the oxidation of fusion welding can be reduced to the level of the quaternary composition system that is equivalent to only to be added with 0.05wt% silicon.

When in Sn0.3Ag0.7Cu0.005Si, adding the 0.005wt% cobalt, can find out, by adding a small amount of silicon and cobalt, compare with comparing embodiment, reduced the quantity of oxidation.

Therefore, can find out, be a small amount of Si of interpolation in the alloy by Sn-Ag-Cu, can constantly stop oxide to form.Also can see, by to the cobalt that wherein further adds minute quantity (0.01wt%), can reduce the requirement of silicon by the synergy of Si and Co.

Hereinafter illustrate that with reference to Fig. 2 the component of silicon and cobalt is on the impact of wetability

Fig. 2 has illustrated the result of the test of wetability.In order to test the wetting time of solder composition, use SP2 wetting test machine (by Malcam Ltd.) at 260 ℃ of fusion weldings.Copper tip is immersed in from the degree of depth on 1 millimeter on fusion welding surface, measures the wetting time that immerses after 5 seconds.

Fig. 2

(Wetting time: wetting time; Comparative example: comparing embodiment; Example: embodiment; Temp: temperature.)

As shown in Figure 2, include 0.5wt% copper, 3wt% silver, surplus is the Sn of tin ₃Ag _0.5The wetting time of Cu is 0.48 second.The Sn that includes 0.5wt% copper, 3wt% silver, 0.005wt% phosphorus, surplus tin ₃Ag _0.5Cu _0.005The wetting time of P is 0.51 second.

When at Sn ₃Ag _0.5When being added with the silicon of 0.005wt% among the Cu, wetting time shortens to 0.44 second.On the contrary, when adding the Si of 0.05wt%, wetting time increases to 0.49 second on the contrary.

This may be that oxygen is removed from melting matrix alloy scolder (SnAgCu), thereby has improved wetability because when (0.005wt%) of minute quantity silicon adds in the scolder.Yet when the addition of silicon during greater than 0.05wt%, the fusion temperature of scolder increases, and excessive silicon has reduced the wetability of fusion welding.

When the Co of 0.005wt% added among the Sn3Ag0.5Cu0.005Si, wetting time foreshortened to 0.46 second.Can find out from this result, by adding the cobalt of a small amount of (less than 0.01wt%), can improve the acid resistance of molten braze alloy, and the addition of minimizing silicon descends greater than the wetability that limiting value causes.

Hereinafter with reference to the copper corrosion rate of Fig. 3 explanation according to the composition of silicon and cobalt.

Fig. 3 illustration the result of the test of copper corrosion rate.For the rate of corrosion of copper test, with solder alloy fusing and remain on 260 ℃.The copper wire of a diameter 0.8mm is immersed in from the degree of depth of fusion welding surface 30mm, measures respectively before immersing and the weight that immerses copper wire after 60 seconds.The be compared to each other weight of copper wire is to obtain the average corrosion rate of 5 samples.

Fig. 3

(Erosion rate: rate of corrosion, comparative example: comparing embodiment; Example: embodiment, temp: temperature; Time: time.)

Shown in Fig. 3, include the Sn of 0.5wt% copper, 3wt% silver, surplus tin ₃Ag _0.5The copper corrosion rate of Cu is 58.3%.The copper corrosion rate that includes the Sn3Ag0.5Cu0.005P of 0.5wt% copper, 3wt% silver, 0.005wt% phosphorus, surplus tin is 58.1%.

Work as Sn ₃Ag _0.5When adding 0.005wt% silicon among the Cu, the copper corrosion rate drops to 54.3%, and when adding 0.05wt%Si, the copper corrosion rate drops to 41.7%.

When the cobalt of (less than the 0.01wt%) that add minute quantity among the Sn3Ag0.5Cu0.05Si, the copper corrosion rate is showing and is dropping to 21.1%.As can be seen from these results, by in the matrix alloy that contains 0.005wt% silicon, adding the cobalt of minute quantity (less than 0.01wt%), the copper corrosion rate can be greatly owing to the cooperative effect of silicon and cobalt reduces.

Hereinafter with reference to amount, fusion temperature, wetting time, copper corrosion rate and the bond strength of table 1 explanation according to the oxide of the component of silicon and cobalt.In addition, will estimate the preferred content that Sn-Ag-Cu is Silicon In Alloys and cobalt according to these results.

Table 1 has been listed Fig. 1,2 and 3 test data and the test data of fusion temperature, variable color and bond strength.

The common scolder of table 1SnAgCu

As shown in table 1, the melt temperature that comprises 3wt% silver, 0.5wt% copper, surplus and be the Sn3Ag0.5Cu of tin is 220 ℃.The fusion temperature that comprises 3wt% silver, 0.5wt% copper, 0.005wt% phosphorus, surplus and be the Sn3Ag0.5Cu0.005P of tin is 221 ℃.When being added with the silicon of 0.005wt%, the fusion temperature of Sn3Ag0.5Cu becomes 220 ℃, and when being added with the silicon of 0.1wt%, the melt temperature of Sn3Ag0.5Cu increases to 224 ℃.

When being added with the cobalt of 0.01wt%, the fusion temperature of Sn3Ag0.5Cu0.05Si increases to 223 ℃.Usually, according to the metal alloy phasor, if low-melting ashbury metal adds a small amount of high-melting-point more than 1400 ℃) silicon when being higher than predetermined quantity, the fusion temperature of ashbury metal increases sharply.Therefore, the silicone content in the ashbury metal need to be limited under the certain level.

The following acquisition of variable color data in the table 1.Prepared sample with being of a size of oxygen-free copper 25x31x0.3mm, purity 99.99% in 3 seconds 260 ℃ of immersions.This sample is heated to 250 ℃ and kept 10 minutes.Then, use the variable color amount of Minolta CM3700B colorimeter measurement yellow.

As shown in table 1, the variable color amount that comprises 3wt% silver, 0.5wt% copper, surplus and be the Sn3Ag0.5Cu of tin is 16.47, and the variable color amount that comprises the Sn3Ag0.5Cu0.005P of 0.5% bronze medal, 3wt% cobalt, 0.005wt% phosphorus and surplus tin is 19.31.

When being added with the silicon of 0.005wt% at Sn3Ag0.5Cu, the variable color quantitative change becomes 15.66, and when wherein adding the silicon of 0.05wt%, the variable color amount is showing and drops to 6.6, and this will be lower than the variable color amount of Sn3Ag0.5Cu and Sn3Ag0.5Cu0.005P.

When being added with the cobalt of 0.005wt% among the Sn3Ag0.5Cu0.005Si, the variable color amount is showing and is dropping to 3.46, and when being added with the cobalt of 0.01wt% among the Sn3Ag0.5Cu0.005Si, the variable color amount significantly drops to 3.02.

Therefore, can reach a conclusion, by wherein adding a small amount of silicon, the variable color of Sn-Ag-Cu matrix alloy can reduce, and by wherein adding a small amount of silicon and cobalt, also can reduce significantly the variable color that the Sn-Ag-Cu matrix alloy causes because of the oxidation of solder alloy.

In the table 1 in conjunction with the following acquisition of breaking load data.The silk that is coated with the 2mm diameter of Sn-Bi vertically inserts in the hole of PCB substrate, and carries out in the above wave soldering and prepare sample.Then, use cupping machine to measure it in conjunction with breaking load (kgf).

As shown in table 1, comprising wherein, 3wt% silver, 0.5wt% copper, surplus are the Sn of tin ₃Ag _0.5Cu's is 84kgf in conjunction with breaking load, comprise 3wt% silver, 0.5wt% copper, 0.005wt%P, surplus tin Sn3Ag0.5Cu0.005P be 89kgf in conjunction with breaking load.

Work as Sn ₃Ag _0.5When being added with 0.005wt% silicon among the Cu, be 95kgf in conjunction with breaking load, when wherein being added with 0.05wt%Si, showing in conjunction with breaking load and to increase to 105kgf that this is greater than Sn3Ag0.05Cu and Sn3Ag0.5Cu0.005P those.

When being added with the cobalt of 0.005wt% among the Sn3Ag0.5Cu0.005Si, be 96kgf in conjunction with breaking load, this is greater than the numerical value of Sn3Ag0.5Cu.When being added with the cobalt of 0.01wt% among the Sn3Ag0.5Cu0.005Si, significantly increase to 112kgf in conjunction with breaking load.

Therefore, can reach a conclusion, Sn-Ag-Cu be matrix alloy can be by improving to wherein adding a small amount of silicon in conjunction with breaking load, also can be by significantly improving to the silicon that wherein adds minute quantity and cobalt.As mentioned above, according to the Pb-free solder compositions of the Sn-Ag-Cu matrix alloy that is added with a small amount of silicon comprising of this embodiment, can keep welding temperature and the wetability of this typical case's Pb-free solder compositions, constantly reduce oxidation, reduce copper corrosion and variable color, and increase in conjunction with breaking load.

Yet when the addition of silicon surpasses some, when namely quantity was greater than 0.05wt%, the fusion temperature of solder alloy increased, and its wetability descends.Therefore, preferred silicone content is 0.001wt%-0.05wt% in the solder alloy.

In addition, in the Sn-Ag-Cu matrix alloy and a small amount of silicon when adding together the cobalt of minute quantity (less than 0.01wt%), the formation of oxide constantly and significantly reduces, copper corrosion and variable color reduce, compare with the solder alloy that only is added with silicon, increase in conjunction with breaking load, and have identical wetability.

In a word, the adding of silicon is enough to anti-oxidation and variable color.Yet when the addition of silicon surpassed a certain quantity, wetability and combinableness therefore reduced.Therefore, by to the cobalt that wherein adds further minute quantity (less than 0.01wt%), can show minimizing oxidation, variable color and copper corrosion, keep simultaneously wettability.

The bond strength that the copper that adds in the Sn-Ag-Cu-P matrix alloy is used for falling slightly low-alloyed fusion temperature and improves weld seam.Yet when the addition of copper during less than 0.1wt%, the effect of copper is inadequate, and when the addition of copper during greater than 2wt%, fusion temperature increases on the contrary.Therefore, preferred copper content is 0.1wt%-2wt% in the solder alloy.The silver that adds in the Sn-Ag-Cu-P matrix alloy is used for falling low-alloyed fusion temperature and improves dispersiveness and thermal fatigue property in conjunction with parent metal.In addition, silver is nontoxic.Yet when the addition of silver during less than 0.1wt%, the effect of silver is inadequate, and when the addition of silver during greater than 4wt%, fusion temperature increases on the contrary.Therefore, the preferred content of silver is 0.1wt%-4.0wt%.Tin is the key component of lead-free solder and is used as parent metal.

Lead-free composition according to this embodiment can be used with the form of cream, rod or silk.This lead-free composition can be used in the electronic device that comprises the many electronic components that are fixed thereon by this Pb-free solder alloy.This electronic device goes for various electronic installations, for example computer, DV, DTV, digital camera and mobile communication terminal.

The present embodiment also can be used the PCB that leadless welding alloy is fixed thereon electronic component or comprised in the electronic device that uses this leadless welding alloy that electronic component is fixed thereon and being implemented comprising.As mentioned above, this leadless welding alloy comprises that copper, 0.1wt%-4.0wt% silver, the silicon of 0.001wt%-0.05wt%, the cobalt of 0.001wt%-0.01wt%, the surplus of 0.1wt%-2wt% are tin.

Like this, lead-free composition and use like this electronic device of this Pb-free solder compositions can have mechanical energy and the processing characteristics that is similar to Sn-Pb alloy and Sn-Ag-Cu alloy.In addition, they can by at tin, add the oxidation that silicon and cobalt can prevent fusion welding constantly, effectively in silver and the copper triple combination objects system.In addition, by adding the only alloy element of minute quantity, they can keep welding temperature and the wetability of common lead-free solder, the corrosion of copper packing material among the variable color after having prevented from welding and the PCB, and improved solder bond.

Leadless welding alloy according to this embodiment can comprise tin (Sn), copper (Cu), silver (Ag), phosphorus (P), silicon (Si) and cobalt (Co).

Hereinafter illustrate that with reference to Fig. 4 the component of silicon and cobalt is to the effect of anti-oxidation.

Fig. 4 illustration form the data that test obtains by oxide.

Fig. 4

As shown in Figure 4, the amount that comprises 0.5wt% copper, 3wt% silver, 0.005wt% phosphorus, surplus and be the oxide that forms among the Sn3Ag0.5Cu0.005P of tin is respectively 295g after 1 hour, 325g after 2 hours, 390g after 3 hours, therefore, the oxide aggregate that formed in 3 hours is 1,010g.The amount that comprises 0.5wt% copper, 3wt% silver, surplus and be the oxide that forms among the Sn3Ag0.5Cu of tin is respectively 478g after 1 hour, 540g after 2 hours, 564g after 3 hours, and therefore, the oxide aggregate that formed in 3 hours is 1,582g.This is because P is used for having reduced the amount of oxide.

Yet, when adding the silicon of 0.005wt% among the Sn3Ag0.5Cu0.005P, the quantity of oxide is respectively 135g after 1 hour, 157g after 2 hours, 185g after 3 hours, therefore, the oxide aggregate that formed in 3 hours is 477g, and this is less than the amount of the oxide that forms among the Sn3Ag0.5Cu0.005P without silicon.In a word, when the addition of P was 0.005wt%, within 2 hours to 3 hours time period, the quantity of slag significantly increased.Yet, when the addition of silicon is 0.005wt%, be similar to the quantity that forms within 1 hour to 2 hours the time in the quantity from the oxide that forms in 2 hours to 3 hours time period.Therefore, can conclude that silicon is more effective than phosphorus aspect continuous prevention oxidation.In addition, when the addition of silicon was 0.05wt%, oxidation further reduced.

When being added with the cobalt of 0.005wt% among the Sn3Ag0.5Cu0.005P0.005Si, the quantity of oxide is respectively 105g after 1 hour, 132g after 2 hours, 155g after 3 hours, and therefore, 3 hours form oxide aggregate is 392g.Can find out according to this result, compare with the situation of Sn3Ag0.5Cu0.005P and Sn3Ag0.5Cu0.005P0.005Si that oxidation quantity reduces.

That is to say that by adding the cobalt of minute quantity (0.005wt%) in Sn3Ag0.5Cu0.005P0.005Si, the oxidation of fusion welding can drop to the quantity of the situation that is equivalent to only to add 0.05wt%Si.

When adding the cobalt of 0.05wt% among the Sn0.3Ag0.7Cu0.05Si, can find out that compare with comparing embodiment, by adding a small amount of silicon and cobalt, the amount of oxide can show and reduces.

Therefore, can find out, by in the Sn-Ag-Cu-P matrix alloy, adding a small amount of Si, can constantly prevent the formation of oxide.Also can find out, by to the cobalt that wherein adds further minute quantity (less than 0.01wt%), by the synergy of silicon and cobalt, can reduce the demand of silicon.

Hereinafter illustrate that with reference to Fig. 5 the component of silicon and cobalt is to the effect of wetability.

Fig. 5

As shown in Figure 5, including 0.5wt% copper, 3wt% silver, 0.005wt% phosphorus, surplus is that the wetting time of the Sn3Ag0.5Cu0.005P of tin is 0.51 second.The wetting time that includes the Sn3Ag0.5Cu0.005P of 0.5wt% copper, 3wt% silver, 0.005wt% phosphorus, surplus tin is 0.48 second.

When being added with the silicon of 0.005wt% in Sn3Ag0.5Cu0.005P, wetting time shortens to 0.47 second.On the contrary, when adding the Si of 0.05wt%, wetting time increases to 0.52 second on the contrary, and this will be longer than the numerical value of Sn3Ag0.5Cu.

Therefore, by the cobalt of further interpolation minute quantity (less than 0.01wt%), can improve the acid resistance of molten braze alloy, and simultaneously, the addition that reduces because of silicon descends greater than the wetability that limiting value causes.

Hereinafter with reference to the copper corrosion rate of Fig. 6 explanation according to the component of silicon and cobalt.

Fig. 6 illustration the result of the test of copper corrosion rate.

Fig. 6

As shown in Figure 6, the copper corrosion rate that includes the Sn3Ag0.5Cu0.005P of 0.5wt% copper, 3wt% silver, 0.005wt% phosphorus, surplus tin is 58.1%.The copper corrosion rate that includes the Sn3Ag0.5Cu of 0.5wt% copper, 3wt% silver, surplus tin is 58.3%.

When adding the silicon of 0.005wt% among the Sn3Ag0.5Cu0.005P0.005Si, the copper corrosion rate is showing and is dropping to 19.2%.And when adding the cobalt of minute quantity (less than 0.01wt%) in the matrix alloy that is containing 0.05wt% silicon, the copper corrosion rate is owing to the cooperative effect of silicon and cobalt can significantly reduce.

Hereinafter with reference to amount, fusion temperature, variable color, wetting time, copper corrosion rate and the bond strength of table 2 explanation according to the oxide of the component of silicon and cobalt.In addition, will estimate the preferred content that Sn-Ag-Cu-P is Silicon In Alloys and cobalt according to these results.

Table 2 has been listed Fig. 4,5 and 6 test data and the test data of fusion temperature, variable color and bond strength.

The common scolder of table 2SnAgCuP

As shown in table 2, the melt temperature that comprises 3wt% silver, 0.5wt% copper, 0.005wt% phosphorus, surplus and be the Sn3Ag0.5Cu0.005P of tin is 221 ℃.The fusion temperature that comprises 3wt% silver, 0.5wt% copper, surplus and be the Sn3Ag0.5Cu of tin is 220 ℃.When being added with the silicon of 0.005wt%, the fusion temperature of Sn3Ag0.5Cu0.005P is 221 ℃, and when being added with the silicon of 0.1wt%, the melt temperature of Sn3Ag0.5Cu0.005P increases to 225 ℃.

When being added with the cobalt of 0.01wt%, the fusion temperature of Sn3Ag0.5Cu0.05P0.05Si increases to 223 ℃.Usually, according to the metal alloy phasor, if low-melting ashbury metal adds the silicon of a small amount of high-melting-point (more than 1400 ℃) when being higher than predetermined quantity, the fusion temperature of ashbury metal increases sharply.Therefore, the silicone content in the ashbury metal need to be limited under the certain level.

The variable color amount that comprises 3wt% silver, 0.5wt% copper, 0.005wt% phosphorus, surplus and be the Sn3Ag0.5Cu0.005P of tin is 19.31, and the variable color amount that comprises the Sn3Ag0.5Cu of 0.5% bronze medal, 3wt% cobalt and surplus tin is 16.47.

When being added with the silicon of 0.005wt% at Sn3Ag0.5Cu0.005P, the variable color quantitative change becomes 17.5, and when wherein adding the silicon of 0.05wt%, the variable color amount is showing and drops to 8.12, and this will be lower than the variable color amount of Sn3Ag0.5Cu and Sn3Ag0.5Cu0.005P.

When being added with the cobalt of 0.005wt% among the Sn3Ag0.5Cu0.005P0.005Si, the variable color amount is showing and is dropping to 7.02, and when being added with the cobalt of 0.01wt% among the Sn3Ag0.5Cu0.005P0.005Si, the variable color amount significantly drops to 4.7.

Therefore, can reach a conclusion, by wherein adding a small amount of silicon, the variable color of Sn-Ag-Cu-P matrix alloy can reduce, and silicon and cobalt by wherein adding minute quantity, also can reduce significantly the variable color that the Sn-Ag-Cu-P matrix alloy causes because of the oxidation of solder alloy.

Comprise 3wt% silver, 0.5wt% copper, 0.005wt%P, surplus and be tin Sn3Ag0.5Cu0.005P be 89kgf in conjunction with breaking load, comprise 3wt% silver, 0.5wt% copper, 0.005wt%P, surplus tin Sn3Ag0.5Cu be 84kgf in conjunction with breaking load.

When being added with 0.005wt% silicon among the Sn3Ag0.5Cu0.005P, be 106kgf in conjunction with breaking load, when wherein being added with 0.05wt%Si, showing in conjunction with breaking load and to increase to 113kgf, this is greater than Sn3Ag0.05Cu and Sn3Ag0.5Cu0.005P those.

When being added with the cobalt of 0.005wt% among the Sn3Ag0.5Cu0.005Si, be 110kgf in conjunction with breaking load, this is greater than the numerical value of Sn3Ag0.5Cu.When being added with the cobalt of 0.01wt% among the Sn3Ag0.5Cu0.005Si, significantly increase to 115kgf in conjunction with breaking load.

Therefore, can find out, Sn-Ag-Cu-P be matrix alloy can be by improving to wherein adding a small amount of silicon in conjunction with breaking load, also can be by significantly improving to the silicon that wherein adds minute quantity and cobalt.

As mentioned above, according to the Pb-free solder compositions of the Sn-Ag-Cu-P matrix alloy that is added with a small amount of silicon comprising of this embodiment, can keep welding temperature and the wetability of this typical case's Pb-free solder compositions, constantly reduce oxidation, reduce copper corrosion and variable color, and increase in conjunction with breaking load.

In addition, in the Sn-Ag-Cu-P matrix alloy and a small amount of silicon when adding together the cobalt of minute quantity, the formation of oxide constantly and significantly reduces, copper corrosion and variable color reduce, compare with the solder alloy that only is added with silicon, increase in conjunction with breaking load, have simultaneously identical wetability.

In addition, even because Co also has good effect when adding less than the minute quantity of 0.01wt%, so the preferred content of Co in solder alloy is 0.001wt%-0.01wt%.

The bond strength that the copper that adds in the Sn-Ag-Cu-P matrix alloy is used for falling slightly low-alloyed fusion temperature and improves weld seam.Yet when the addition of copper during less than 0.1wt%, the effect of copper is inadequate, and when the addition of copper during greater than 2wt%, fusion temperature increases on the contrary.Therefore, preferred copper content is 0.1wt%-2wt% in the solder alloy.The silver that adds in the Sn-Ag-Cu-P matrix alloy is used for falling low-alloyed fusion temperature and improves dispersiveness and thermal fatigue property in conjunction with parent metal.In addition, silver is nontoxic.Yet when the addition of silver during less than 0.1wt%, the effect of silver is inadequate, and when the addition of silver during greater than 4wt%, fusion temperature increases on the contrary.Therefore, the preferred content of silver is 0.1wt%-4.0wt%.The phosphorus that adds in the Sn-Ag-Cu-P matrix alloy is used for reducing the formation of welding oxide, thereby improves the welding processing performance.Yet when the addition of phosphorus during less than 0.001wt%, effect of phosphorous is inadequate, and when the addition of phosphorus during greater than 0.2wt%, fusion temperature increases on the contrary.Therefore, the preferred content of phosphorus is 0.001wt%-0.2wt%.Tin is the key component of lead-free solder and is used as parent metal.

Leadless welding alloy according to embodiment can comprise tin (Sn), copper (Cu), silver (Ag), nickel (Ni), germanium (Ge), silicon (Si) and cobalt (Co).

Hereinafter illustrate that with reference to Fig. 7 the component of silicon and cobalt is to the effect of anti-oxidation.

Fig. 7 illustration form the data that test obtains by oxide.

Fig. 7

As shown in Figure 7, the amount that comprises 0.5wt% copper, 3wt% silver, 0.06wt% nickel, the germanium of 0.01wt%, surplus and be the oxide that forms among the Sn3Ag0.5Cu0.06Ni0.01Ge of tin is respectively 147g after 1 hour, 151g after 2 hours, 160g after 3 hours, therefore, the oxide aggregate that formed in 3 hours is 458g.The amount that comprises 0.5wt% copper, 3wt% silver, 0.05wt% phosphorus, surplus and be the oxide that forms among the Sn3Ag0.5Cu0.05P of tin is respectively 295g after 1 hour, 325g after 2 hours, 390g after 3 hours, and therefore, the oxide aggregate that formed in 3 hours is 1,010g.The amount that comprises 0.5wt% copper, 3wt% silver, surplus and be the oxide that forms among the Sn3Ag0.5Cu of tin is respectively 478g after 1 hour, 540g after 2 hours, 564g after 3 hours, and therefore, the oxide aggregate that formed in 3 hours is 1,582g.This is because Ni is used for having reduced the amount of oxide.

When adding the silicon of 0.005wt% among the Sn3Ag0.5Cu0.06Ni0.01Ge, the quantity of oxide is respectively 105g after 1 hour, 115g after 2 hours, 121g after 3 hours, therefore, the oxide aggregate that formed in 3 hours is 341g, and this is less than the amount of the oxide that forms among the Sn3Ag0.5Cu0.06Ni0.01Ge without silicon.

In a word, when the addition of P was 0.005wt%, within 2 hours to 3 hours time period, the quantity of slag significantly increased.Yet, when the addition of silicon is 0.005wt%, be similar to the quantity that forms within 1 hour to 2 hours the time in the quantity from the oxide that forms in 2 hours to 3 hours time period.Therefore, can conclude that silicon is more effective than phosphorus aspect continuous prevention oxidation.In addition, when the addition of silicon was 0.05wt%, oxidation further reduced.

When being added with the cobalt of 0.005wt% among the Sn3Ag0.5Cu0.06Ni0.01Ge0.005Si, the quantity of oxide relatively embodiment descends.

Therefore, can find out, by in the Sn-Ag-Cu-Ni-Ge matrix alloy, adding a small amount of Si, compare with the common solder composition that is added with P, can constantly prevent the formation of oxide.Also can find out, by to the cobalt that wherein adds further minute quantity (less than 0.01wt%), by the synergy of silicon and cobalt, can reduce the demand of silicon.

Hereinafter illustrate that with reference to Fig. 8 the component of silicon and cobalt is to the effect of wetability.

Fig. 8

As shown in Figure 8, the wetting time of the germanium of 0.5wt% copper, 3wt% silver, 0.06wt% nickel, 0.01wt%, Sn3Ag0.5Cu0.06Ni0.01Ge that surplus is tin is 0.38 second.The wetting time that includes the Sn3Ag0.5Cu of 0.5wt% copper, 3wt% silver, surplus tin is 0.48 second.The wetting time that includes the Sn3Ag0.5Cu0.005P of 0.5wt% copper, 3wt% silver, 0.005wt% phosphorus, surplus tin is 0.51 second.

When being added with the silicon of 0.005wt% in Sn3Ag0.5Cu0.06Ni0.01Ge, wetting time shortens to 0.34 second.On the contrary, when adding the Si of 0.05wt%, wetting time increases to 0.39 second on the contrary.

Hereinafter with reference to the copper corrosion rate of Fig. 9 explanation according to the component of silicon and cobalt.

Fig. 9 illustration the result of the test of copper corrosion rate.

Fig. 9

As shown in Figure 9, include the germanium of 0.5wt% copper, 3wt% silver, 0.06wt% nickel, 0.01wt%, the copper corrosion rate of Sn3Ag0.5Cu0.06Ni0.01Ge that surplus is tin is 56.5%.The copper corrosion rate that includes the Sn3Ag0.5Cu0.005P of 0.5wt% copper, 3wt% silver, 0.005wt% phosphorus, surplus tin is 58.1%.The copper corrosion rate that includes the Sn3Ag0.5Cu of 0.5wt% copper, 3wt% silver, surplus tin is 58.3%.

When adding the silicon of 0.005wt% among the Sn3Ag0.5Cu0.06Ni0.01Ge, the copper corrosion rate is showing and is dropping to 53.2%.When adding 0.05wt% silicon in Sn3Ag0.5Cu0.06Ni0.01Ge, the copper corrosion rate drops to 31%, and this is less than Sn3Ag0.5Cu0.06Ni0.01Ge, those numerical value of Sn3Ag0.5Cu and Sn3Ag0.5Cu0.005P.

When adding the cobalt of 0.01wt% among the Sn3Ag0.5Cu0.06Ni0.01Ge0.05Si, the copper corrosion rate is showing and is dropping to 17.2%, and when the cobalt of (less than the 0.01wt%) that add minute quantity in the matrix alloy that is comprising 0.01wt% silicon, because the cooperative effect copper corrosion rate of silicon and cobalt significantly reduces.

Hereinafter with reference to amount, fusion temperature, variable color, wetting time, copper corrosion rate and the bond strength of table 3 explanation according to the oxide of the component of silicon and cobalt.In addition, will estimate the preferred content that Sn-Ag-Cu-Ni-Ge is Silicon In Alloys and cobalt according to these results.

Table 3 has been listed Fig. 7,8 and 9 test data and the test data of fusion temperature, variable color and bond strength.

The common scolder of table 3SnAgCuNiGe

As shown in table 3, the melt temperature that comprises 3wt% silver, 0.5wt% copper, 0.005wt%Ni, 0.01wt% germanium, surplus and be the Sn3Ag0.5Cu0.06Ni0.01Ge of tin is 222 ℃.The fusion temperature that comprises 3wt% silver, 0.5wt% copper, 0.005wt% phosphorus, surplus and be the Sn3Ag0.5Cu0.005P of tin is 221 ℃.When being added with the silicon of 0.005wt%, the fusion temperature of Sn3Ag0.5Cu is 220 ℃.

When being added with the silicon of 0.1wt%, the melt temperature of Sn3Ag0.5Cu0.06Ni0.01Ge increases to 225 ℃.

When being added with the cobalt of 0.01wt%, the fusion temperature of Sn3Ag0.5Cu0.06Ni0.01Ge increases to 224 ℃.Usually, according to the metal alloy phasor, if low-melting ashbury metal adds the silicon of a small amount of high-melting-point (more than 1400 ℃) when being higher than predetermined quantity, the fusion temperature of ashbury metal increases sharply.Therefore, the silicone content in the ashbury metal need to be limited under the certain level.

As shown in table 3, the variable color amount of Sn3Ag0.5Cu0.06Ni0.01Ge is 15.6, and the variable color amount that comprises 0.5wt% copper, 3wt% silver, surplus and be the Sn3Ag0.5Cu of tin is that the variable color amount of 16.47, Sn3Ag0.5Cu0.005P is 19.31.

When being added with the silicon of 0.005wt% in Sn3Ag0.5Cu0.06Ni0.01Ge, the variable color quantitative change becomes 13.5, and when wherein adding the silicon of 0.05wt%, the variable color amount is showing and drops to 9.47, and this will be lower than the variable color amount of Sn3Ag0.5Cu and Sn3Ag0.5Cu0.005P.

When being added with the cobalt of 0.005wt% among the Sn3Ag0.5Cu0.06Ni0.01Ge0.005Si, the variable color amount is showing and is dropping to 6.72, and when being added with the cobalt of 0.01wt% among the Sn3Ag0.5Cu0.06Ni0.01Ge0.005Si, the variable color amount significantly drops to 3.08.

Therefore, can find out that by wherein adding a small amount of silicon, Sn-Ag-Cu-Ni-Ge is that the variable color of alloy can reduce, and silicon and cobalt by wherein adding minute quantity, also can reduce significantly Sn-Ag-Cu-Ni-Ge and be the variable color that alloy causes because of the oxidation of solder alloy.

As shown in table 3, Sn3Ag0.5Cu0.06Ni0.01Ge's is 100kgf in conjunction with breaking load, comprise 3wt% silver, 0.5wt% copper, 0.005wt%P, surplus and be tin Sn3Ag0.5Cu0.005P be 89kgf in conjunction with breaking load, and comprise 3wt% silver, 0.5wt% copper, surplus tin Sn3Ag0.5Cu0.005P be 84kgf in conjunction with breaking load.

When being added with 0.005wt% silicon among the Sn3Ag0.5Cu0.06Ni0.01Ge, be 107kgf in conjunction with breaking load, when wherein being added with 0.05wt%Si, showing in conjunction with breaking load and to increase to 115kgf, this is greater than Sn3Ag0.05Cu and Sn3Ag0.5Cu0.005P those.

When being added with the cobalt of 0.005wt% among the Sn3Ag0.5Cu0.06Ni0.01Ge0.005Si, significantly be increased to 109kgf in conjunction with breaking load, this is greater than the numerical value of Sn3Ag0.5Cu0.06Ni0.01Ge.When being added with the cobalt of 0.01wt% among the Sn3Ag0.5Cu0.06Ni0.01Ge0.005Si, significantly increase to 119kgf in conjunction with breaking load.

Therefore, can find out, Sn-Ag-Cu-Ni-Ge be alloy can be by improving to wherein adding a small amount of silicon in conjunction with breaking load, also can be by significantly improving to the silicon that wherein adds minute quantity and cobalt.

As mentioned above, be the Pb-free solder compositions of alloy according to the Sn-Ag-Cu-Ni-Ge that is added with a small amount of silicon comprising of this embodiment, can keep welding temperature and the wetability of this typical case's Pb-free solder compositions, constantly reduce oxidation, reduce copper corrosion and variable color, and increase in conjunction with breaking load.In addition, be in the alloy and a small amount of silicon when adding together the cobalt of minute quantity at Sn-Ag-Cu-Ni-Ge, the formation of oxide constantly and significantly reduces, copper corrosion and variable color reduce, compare with the solder alloy that only is added with silicon, increase in conjunction with breaking load, have simultaneously identical wetability.

In addition, even because cobalt also has good effect when adding less than the minute quantity of 0.01wt%, so the preferred content of cobalt in solder alloy is 0.001wt%-0.01wt%.

Sn-Ag-Cu-Ni-Ge is the bond strength that the copper that adds in the alloy is used for falling slightly low-alloyed fusion temperature and improves weld seam.Yet when the addition of copper during less than 0.1wt%, the effect of copper is inadequate, and when the addition of copper during greater than 2wt%, fusion temperature increases on the contrary.Therefore, preferred copper content is 0.1wt%-2wt% in the solder alloy.Sn-Ag-Cu-Ni-Ge is that the silver that adds in the alloy is used for falling low-alloyed fusion temperature and improves dispersiveness and thermal fatigue property in conjunction with parent metal.In addition, silver is nontoxic.Yet when the addition of silver during less than 0.1wt%, the effect of silver is inadequate, and when the addition of silver during greater than 4wt%, fusion temperature increases on the contrary.Therefore, the preferred content of silver is 0.1wt%-4.0wt%.Sn-Ag-Cu-Ni-Ge is that the nickel that adds in the alloy is used for preventing the corrosion of copper packing and improves bond strength.Yet when the addition of nickel during less than 0.001wt%, without any effect, when the addition of nickel during greater than 0.5wt%, fusion temperature increases fast on the contrary and overvulcanization occurs.Therefore, the preferred content of Ag is 0.001wt%-0.5wt%.In addition, the preferred content of Ge is 0.001wt%-0.1wt%.Tin is the key component of lead-free solder and is used as parent metal.

Sn-Ag-Cu-Ni-Ge is that the phosphorus of the middle interpolation added in the alloy is used for reducing the formation of welding oxide, thereby improves the welding processing performance.The preferred content of phosphorus is 0.001wt%-0.2wt%.

As mentioned above, Sn-Ag-Cu-Ni-Ge is that the Si and the Co that add in the alloy have the effect that prevents oxide formation and prevent variable color, and can significantly improve this effect by adding together them.

The present embodiment also can be used the PCB that leadless welding alloy is fixed thereon electronic component or comprised in the electronic device that uses this leadless welding alloy that a plurality of electronic components are fixed thereon and being implemented comprising.As mentioned above, this leadless welding alloy comprises that copper, 0.1wt%-4.0wt% silver, the phosphorus of 0.001wt%-0.2wt%, the nickel of 0.001wt%-0.5wt%, the germanium of 0.001wt%-0.1wt%, the silicon of 0.001wt%-0.05wt%, the cobalt of 0.001wt%-0.01wt%, the surplus of 0.1wt%-2wt% are tin.

Leadless welding alloy according to this embodiment can comprise tin (Sn), copper (Cu), phosphorus (P), nickel (Ni), silicon (Si) and cobalt (Co).

Hereinafter illustrate that with reference to Figure 10 the component of silicon and cobalt is to the effect of anti-oxidation.

Figure 10 illustration form the data that test obtains by oxide.

Figure 10

As shown in Figure 10, phosphorus, the surplus that comprises 0.5wt% copper, 0.06wt% nickel, 0.005wt% is that the amount of the oxide that forms among the Sn0.5Cu0.06Ni0.005P of tin is respectively 134g after 1 hour, 268g after 2 hours, 384g after 3 hours, therefore, the oxide aggregate that formed in 3 hours is 786g.The amount of the oxide that forms among the Sn0.5Cu is respectively 371g after 1 hour, 395g after 2 hours, 460g after 3 hours, and therefore, the oxide aggregate that formed in 3 hours is 1226g.The amount that comprises 0.5wt% copper, 0.05wt% phosphorus, surplus and be the oxide that forms among the Sn0.5Cu0.005P of tin is respectively 251g after 1 hour, 356g after 2 hours, 440g after 3 hours, and therefore, the oxide aggregate that formed in 3 hours is 1,047g.The amount of the oxide that forms among the Sn0.5Cu0.06Ni0.005P is that less than the reason of the amount of the oxide that forms among Sn0.5Cu0.005P and the Sn0.5Cu nickel and phosphorus are used for reducing oxidation.

When adding the silicon of 0.005wt% among the Sn0.5Cu0.06Ni0.005P, the quantity of oxide is respectively 110g after 1 hour, 132g after 2 hours, 155g after 3 hours, therefore, the oxide aggregate that formed in 3 hours is 397g, and this is less than the amount of the oxide that forms among Sn0.5Cu, Sn0.5Cu0.005P and the Sn0.5Cu0.06Ni0.005P.

In a word, when the addition of P was 0.005wt%, within 2 hours to 3 hours time period, the quantity of slag significantly increased.Yet, when the addition of silicon is 0.005wt%, be similar to the quantity that forms within 1 hour to 2 hours the time in the quantity from the oxide that forms in 2 hours to 3 hours time period.Therefore, can conclude that silicon is more effective than phosphorus aspect continuous prevention oxidation.

In addition, when the addition of silicon was 0.05wt%, oxidation further reduced.

When being added with the cobalt of 0.01wt% among the Sn0.5Cu0.005P0.06Ni0.05Si, the quantity of oxide is respectively 86g after 1 hour, 103g after 2 hours, 119g after 3 hours, therefore, the oxide aggregate that formed in 3 hours is 308g, and this is less than the amount of the oxide that forms among Sn0.5Cu0.005P and the Sn0.5Cu0.06Ni0.005P0.005Si.

That is to say, by in Sn0.5Cu0.005P0.06Ni0.05Si, adding the cobalt of minute quantity (0.01wt%), can reduce the amount of the oxide of fusion welding, be similar to the amount of the oxide of the solder alloy that only adds 0.05wt% silicon.

When in Sn0.75Cu0.005P0.1Ni0.005Si, adding the cobalt of 0.005wt%, to compare with comparing embodiment, the amount of oxide descends.

Therefore, can find out, by being a small amount of Si of interpolation in the alloy at Sn-Cu-P-Ni, compare with the common solder composition that is added with P, can constantly prevent the formation of oxide.Also can find out, by to the cobalt that wherein adds further minute quantity (less than 0.01wt%), by the synergy of silicon and cobalt, can reduce the demand of silicon.

Hereinafter illustrate that with reference to Figure 11 the component of silicon and cobalt is on the impact of wetability.

Figure 11

(Wetting time: wetting time; Comparative example: comparing embodiment; Example: embodiment: temp: temperature.)

As shown in Figure 11,0.5wt% copper, 0.06wt% nickel, 0.005wt% phosphorus, surplus are that the wetting time of the Sn0.5Cu0.06Ni0.005P of tin is 2.07 seconds.The wetting time that includes the Sn0.5Cu0.005P of 0.5wt% copper, 0.005wt% phosphorus, surplus tin is 1.88 seconds.The wetting time that includes the Sn0.5Cu of 0.5wt% copper, surplus tin is 1.67 seconds.

When being added with the silicon of 0.005wt% in Sn0.5Cu0.06Ni0.005P, wetting time shortens to 1.85 seconds.On the contrary, when adding the Si of 0.05wt%, wetting time increases to 2.09 seconds on the contrary.

Hereinafter with reference to the copper corrosion rate of Figure 12 explanation according to the component of silicon and cobalt.

Figure 12 illustration the result of the test of copper corrosion rate.

Figure 12

As shown in Figure 12, the copper corrosion rate of Sn0.5Cu0.06Ni0.005P is 47.1%.The rate of corrosion of Sn0.5Cu is that the rate of corrosion of 53.6%, Sn0.5Cu0.005P is 52.7%.

When adding the silicon of 0.005wt% among the Sn0.5Cu0.06Ni0.005P, the copper corrosion rate is showing and is dropping to 45%.When adding 0.05wt% silicon in Sn0.5Cu0.06Ni0.005P, the copper corrosion rate is 44.7%, and this is less than those numerical value of Sn0.5Cu, Sn0.5Cu0.005P and Sn0.5Cu0.06Ni0.005P.

When adding the cobalt of 0.01wt% among the Sn0.5Cu0.06Ni0.005P0.05Si, the copper corrosion rate is showing and is dropping to 11.8%, and when the cobalt of (less than the 0.01wt%) that add minute quantity in the matrix alloy that is comprising 0.05wt% silicon, because the cooperative effect copper corrosion rate of silicon and cobalt significantly reduces.

Hereinafter with reference to amount, fusion temperature, variable color, wetting time, copper corrosion rate and the bond strength of table 4 explanation according to the oxide of the component of silicon and cobalt.In addition, will estimate the preferred content that Sn-Cu-P-Ni is Silicon In Alloys and cobalt according to these results.

Table 4 has been listed Figure 16,17 and 18 test data and the test data of fusion temperature, variable color and bond strength.

The common scolder of table 4SnCuNiP

As shown in table 4, the melt temperature of Sn0.5Cu0.06Ni0.005P is 233 ℃.The fusion temperature that comprises 0.5wt% copper, 0.005wt% phosphorus, surplus and be the Sn0.5Cu0.005P of tin is 231 ℃.The fusion temperature that comprises 0.5wt% copper, 0.005wt% phosphorus, surplus and be the Sn0.5Cu of tin is 230 ℃.

When being added with the silicon of 0.1wt%, the melt temperature of Sn0.5Cu0.06Ni0.01P increases to 237 ℃.

When the cobalt that is added with 0.01%, the fusion temperature of Sn0.5Cu0.06Ni0.005P0.05Si is increased to 236 ℃.

In general, according to the metal alloy phasor, if add a small amount of Si that surpasses the high-melting-point (more than 1400 ℃) of predeterminated level in low melting point Sn alloy, the fusion temperature of Sn alloy can significantly increase so.Therefore, the Si content in the Sn alloy need to limit and be lower than certain level.

As shown in table 4, the variable color degree of Sn0.5Cu0.006Ni0.005P is that the variable color degree of 13.5, Sn0.5Cu0.005P is 14.71, and Sn0.5Cu variable color degree is 15.81.

The variable color degree is 12.7 when 0.005wt%Si adds Sn0.5Cu0.006Ni0.005P, and when adding 0.05wt%Si therein the time variable color degree significantly be reduced to 11.3, it is lower than the variable color degree of Sn0.5Cu and Sn0.5Cu0.005P.

When 0.005wt%Co added Sn0.5Cu0.006Ni0.005P0.005Si, the variable color degree significantly was reduced to 8.33, and when 0.01wt%Co added Sn0.5Cu0.006Ni0.005P0.05Si, the variable color degree significantly was reduced to 4.

Therefore, can find out that the variable color degree of Sn-Cu-P-Ni base alloy can reduce by adding therein a small amount of Si, and owing to the Sn-Cu-P-Ni base alloy variable color of scolder oxidation also can significantly reduce by adding therein very small amount of Si and Co quantity.

As shown in table 4, Sn0.5Cu0.006Ni0.005P's is 85kgf in conjunction with breaking load, and Sn0.5Cu0.005P's is 87kgf in conjunction with breaking load, and Sn0.5Cu's is 83kgf in conjunction with breaking load.

When 0.005wt%Si adds Sn0.5Cu0.006Ni0.005P, be 90kgf in conjunction with breaking load, and when 0.05wt%Si adds wherein, significantly increase to 96kgf in conjunction with breaking load, its be higher than Sn0.5Cu and Sn0.5Cu0.005P in conjunction with breaking load.

When 0.005wt%Co adds Sn0.5Cu0.006Ni0.005P0.005Si, be 93kgf in conjunction with breaking load, its be higher than Sn0.5Cu0.006Ni0.005P in conjunction with breaking load.When 0.01wt%Co adds Sn0.5Cu0.006Ni0.005P0.005Si, in conjunction with the breaking load phenomenal growth to 99kgf.

Therefore, can find out can improving by adding therein a small amount of Si in conjunction with breaking load of Sn-Cu-P-Ni base alloy, and can significantly improve by adding therein very small amount of Si and Co.

As mentioned above, lead-free solder compounds according to present embodiment comprises the Sn-Cu-P-Ni base alloy that has added a small amount of Si, can keep solder temperature and wetability, lasting reduction oxidation, minimizing copper corrosion and the variable color of typical lead-free solder compounds, and increase in conjunction with breaking load.

In addition, when very small amount of Co and a small amount of Si add Sn-Cu-P-Ni base alloy, compare with only adding Si, have in the situation of identical wetability, can continue the also significantly formation of reduction oxide, reduce copper corrosion and variable color, and increase in conjunction with breaking load.

Yet when the Si that adds surpasses a certain degree, namely quantity surpasses 0.05wt%, and the fusion temperature of solder alloy increases and its wetability reduces so.Therefore, preferred Si content is from 0.001wt% to 0.05wt% in the solder alloy.

In addition, because the very small amount of Co that adds less than 0.01wt% also demonstrates good effect, so preferred Co content is 0.001wt% to 0.01wt% in the solder alloy.

The Co that adds in the Sn-Cu-P-Ni base alloy can significantly fall low-alloyed fusion temperature temperature and increase the bond strength of binding site.Yet when the Cu that adds was lower than 0.1wt%, the impact of Cu was inadequate.When the Cu that adds was higher than 2wt%, fusion temperature had increased on the contrary.Therefore, preferred copper content is 0.1wt% to 2wt% in the solder alloy.The Ni that adds in the Sn-Cu-P-Ni base alloy can increase intensity and the toughness of scolder, and avoids the formation of burn into oxide and the growth of mating surface place intermetallic compound.Preferred Ni content is 0.001wt% to 1.0wt% in the solder alloy.This is because of the increase along with nickel content, and fusion temperature increases, and wetability and dispersed the reduction.The P that adds in the Sn-Cu-P-Ni base alloy reduces the formation of oxide in welding, thereby has improved the operability of welding.Preferred P content is 0.001wt% to 0.2wt%.Sn is the requisite component of lead-free solder and uses as underlying metal.

Present embodiment also can be embodied as the PCB of the use leadless welding alloy that comprises that electronic component is mounted thereon or comprise the electronic device of the use leadless welding alloy that a plurality of electronic components are mounted thereon.As mentioned above, leadless welding alloy comprises cobalt, the phosphorus of 0.001wt% to 0.2wt% and the tin of surplus of Si, 0.001wt% to 0.01wt% of nickel, the 0.001wt% to 0.05wt% of copper, the 0.001wt% to 1.0wt% of 0.1wt% to 2wt%.

Leadless welding alloy according to present embodiment can comprise tin (Sn), copper (Cu), phosphorus (P), bismuth (Bi), silicon (Si) and cobalt (Co).

Above-mentioned solder compound is without silver alloy and the low temperature lead-free solder alloy with about 210 ℃ of fusion temperatures.

Silicon and cobalt component are described in the effect aspect the anti-oxidation below with reference to Figure 13.

Figure 13 has shown the data that form acquisition the experiment from oxidation.

Figure 13

(after After 1hour:1 hour; After Afer 2hour:2 hour; After Afer 3hour:3 hour; Comparative example: comparing embodiment; Example: embodiment; Amount of oxidation: the amount of oxide.)

As shown in figure 13, the amount of the oxide that comprises 0.5wt%Cu, 17wt%Bi, 0.005wt%P and surplus Sn that forms among the Sn0.5Cu17Bi0.005P respectively after 1 hour for 330g, after 2 hours for 360g and after 3 hours for 450g, and therefore 3 hours formed oxide aggregates are 1140g.

When the Si of 0.005st% adds Sn0.5Cu17Bi0.005P, the quantity of oxide respectively be 201g after 1 hour, after 2 hours for 241g and after 3 hours for 273g, and therefore 3 hours formed oxide aggregates are 715g, and it is less than the amount that is formed on the oxide among the Sn0.5Cu17Bi0.005P.

In a word, when adding the P of 0.005wt%, scum silica frost quantity significantly increases during 2 hours to 3 hours.Yet, when adding the Si of 0.005wt%, the amount of the oxide that during the amount of the oxide that forms during 2 hours to 3 hours is similar to 1 hour to 2 hours, forms.Therefore, can judge that Si is more effective than P aspect lasting anti-oxidation.In addition, when adding the Si of 0.05wt%, oxidation further descends especially.

When the Co of 0.005wt% adds Sn0.5Cu0.005P17Bi0.005Si, the quantity of oxide respectively be 168g after 1 hour, after 2 hours for 181g and after 3 hours for 205g, and therefore 3 hours formed oxide aggregates are 554g, and it is lower than the amount that is formed on the oxide among the Sn0.5Cu0.005P17Bi0.005Si.

Therefore, can find out, with the typical solders Compound Phase ratio that has added P, by in Sn-Cu-P-Ni base alloy, adding a small amount of Si, can continue to prevent the formation of oxide.Also can find out, by further adding therein the very cobalt of a small amount of (being lower than 0.01wt%), required silicone content is minimized.

Silicon and cobalt component are described in the impact aspect the wetability below with reference to Figure 14.

Figure 14

(Temp: temperature; Comparative example: comparing embodiment; Example: embodiment; Wettingtime: wetting time.)

As shown in figure 14, the wetting time of Sn0.5Cu17Bi0.005P is 0.24 second.When wherein adding 0.005wt%Si, the wetting time of Sn0.5Cu17Bi0.005P is reduced to 0.22 second.On the contrary, when wherein adding 0.005wt%Si, the wetting time of Sn0.5Cu17Bi0.005P has increased on the contrary.

When adding the Co of 0.01wt% in Sn0.5Cu17Bi0.005P0.05Si, wetting time foreshortens to 0.28 second.On the contrary, when adding the Co of 0.005wt% in Sn0.5Cu17Bi0.005P0.05Si, wetting time is 0.23 second.

Can think that when very small amount of silicon (0.005wt%) added scolder, oxygen removed from the base alloy scolder (SnAgCu) of melting, therefore increase wetability.But when the Si content that adds surpassed 0.05st%, the fusion temperature temperature of scolder increased, and Si has reduced the wetability of fusion welding.

Therefore, by the very small amount of Co of further adding (less than 0.01wt%), might improve the acid resistance of molten braze alloy, and, simultaneously, the reduction that produces wetability owing to the silicon that adds quantity in excess of the quota is reached minimize.

The copper corrosion rate of the component that depends on silicon and cobalt is described below with reference to Figure 15.

Figure 15 has illustrated the experimental result of copper corrosion rate.

Figure 15

(Temp: temperature; Time 60sec: 60 seconds time; Comparative example: comparing embodiment; Example: embodiment; Erosion rate: rate of corrosion.)

As shown in figure 15, the copper corrosion rate of Sn0.5Cu17Bi0.005P is 51.9%.

When the Si of 0.005wt% added Sn0.5Cu17Bi0.005P, the copper corrosion rate was 44.7%.When the Si of 0.05wt% added Sn0.5Cu17Bi0.005P, the copper corrosion rate was 31.7%, and it is less than the copper corrosion rate of Sn0.5Cu17Bi0.005P.

When the Co of 0.01wt% adds Sn0.5Cu17Bi0.005P0.05Si, the copper corrosion rate significantly is reduced to 12.7%, and when very small amount of Co (less than 0.01wt%) joined in the base alloy of the Si that comprises 0.005wt%, the copper corrosion rate was because the cooperative effect of silicon and cobalt and significantly reducing.

Amount, fusion temperature, variable color degree, wetting time, copper corrosion rate and the bond strength of the oxide that depends on silicon and cobalt component are described below with reference to table 5.In addition, from these results, will estimate optimum content at Sn-Cu-Bi-P base Silicon In Alloys and cobalt.

Table 5 has been listed Figure 13,14 and 15 experimental data and fusion temperature, the experimental data of variable color degree and bond strength.

The conventional scolder of table 5 low temperature SnCuBiP

As shown in table 5, the fusion temperature of Sn0.5Cu17Bi0.005P is 211 ℃.When the Si of 0.1wt% added Sn0.5Cu17Bi0.005P, fusion temperature was increased to 214 ℃.

When the Co of 0.01wt% added Sn0.5Cu17Bi0.005P0.05Si, fusion temperature was increased to 214 ℃.In general, according to the metal alloy phasor, if add a small amount of Si that surpasses the high-melting-point (more than 1400 ℃) of predeterminated level in low melting point Sn alloy, the fusion temperature of Sn alloy can significantly increase so.Therefore, the Si content in the Sn alloy need to limit and be lower than certain level.

As shown in table 5, the variable color degree of Sn0.5Cu17Bi0.005P is 16.78.

The variable color degree is 11.87 when the Si of 0.005wt% adds Sn0.5Cu17Bi0.005P, and adds wherein as the Si of 0.05wt%, and the variable color degree significantly is reduced to 8.97, and it is lower than the variable color degree of Sn0.5Cu17Bi0.005P.

The variable color degree significantly is reduced to 6.81 when the Co of 0.005wt% adds Sn0.5Cu17Bi0.005P0.005Si, and the variable color degree significantly is reduced to 4.99 when the Co of 0.01wt% adds Sn0.5Cu17Bi0.005P0.05Si.

Therefore, can find out, Sn-Cu-Bi-P base alloy can reduce variable color by adding therein a small amount of Si, and since the variable color of the basic alloy of the Sn-Cu-Bi-P that the solder alloy oxidation produces also can reduce by adding therein very small amount of Si and Co.

As shown in table 5, Sn0.5Cu17Bi0.005P's is 95kgf in conjunction with fracture load.

When the Si of 0.005wt% adds Sn0.5Cu17Bi0.005P, be 117kgf in conjunction with breaking load, and when the Si of 0.05wt% adds wherein, significantly be increased to 127kgf in conjunction with breaking load, its greater than Sn0.5Cu17Bi0.005P in conjunction with breaking load.

When the Co of 0.005wt% adds Sn0.5Cu17Bi0.005P0.005, be 119kgf in conjunction with breaking load, its greater than Sn0.5Cu17Bi0.005P0.005Si in conjunction with breaking load.When adding Sn0.5Cu17Bi0.005P0.005, the Co of 0.01wt% significantly is increased to 131kgf in conjunction with breaking load.

Therefore, can find out, can the improving by adding therein a small amount of Si in conjunction with breaking load of Sn-Cu-Bi-P base alloy, and can significantly improve by adding therein very small amount of Si and Co.

As mentioned above, according to the lead-free solder compounds of present embodiment, comprise the Sn-Cu-Bi-P base alloy that has added a small amount of Si, welding temperature and the wetability that can keep typical lead-free solder compounds, constantly reduce oxidation, reduce copper corrosion and variable color, and increase in conjunction with breaking load.

In addition, when very small amount of Co and a small amount of Si add Sn-Cu-Bi-P base alloy, compare with the solder alloy that has only added Si, can continue and significantly reduce the formation of oxide, reduce copper corrosion and variable color, increase in conjunction with breaking load, and have identical wetability.

Yet when the Si quantity that adds surpasses to a certain degree, namely quantity surpasses 0.05wt%, and the fusion temperature of solder alloy raises and its wetability descends so.Therefore, preferred Si content is that 0.001wt% is to 0.05wt% in the solder alloy.

In addition, though since when adding the very small amount of Co be lower than 0.01wt% Co also demonstrated good effect, so preferred Co content is that 0.001wt% is to 0.01wt% in the solder alloy.

As mentioned above, silicon and cobalt have the generation that prevents oxide and the effect that prevents variable color separately, and they have further improved effect by common interpolation.

Present embodiment also may be embodied as the PCB of the use leadless welding alloy that comprises that electronic component is mounted thereon or comprises the electronic device of the use leadless welding alloy that a plurality of electronic components are mounted thereon.As mentioned above, leadless welding alloy comprises that 0.1wt% is to the copper of 2wt%, 0.001wt% to the phosphorus of 1.0wt%, the bismuth of 0.1wt% to 8wt%, the silicon of 0.001wt% to 0.05wt%, the cobalt of 0.001wt% to 0.01wt% and the tin of surplus.

Embodiment 2

High temperature lead-free solder compound according to present embodiment can comprise tin (Sn), copper (Cu), silicon (Si) and cobalt (Co).

Silicon and cobalt component are described in the impact aspect the anti-oxidation below with reference to Figure 16.

Figure 16 has illustrated the experimental data of the amount of the oxide of being measured by follow procedure.Preparation tin-copper base alloy, and with its in high-frequency melting furnace with silicon and cobalt the two or silicon and cobalt in one of common fusing, to form solder compound.After the solder compound sampling, use dsc analysis to measure its fusion temperature with 5 ℃/min.After this, in order to measure the amount of oxide, on hot plane, the scolder of 3kg in being the SUS crucible of 160mm, diameter is heated to 420 ℃.Then, use diameter to stir respectively solder compound 1 hour, 2 hours and 3 hours as the agitator of 140mm with the speed of 60rpm, and therefrom extract oxide at every turn and carry out weighing.

Figure 16

(Oxidation rate: oxidation rate; After After 1hour:1 hour; After Afer 2hour:2 hour; After Afer 3hour:3 hour; Amount of oxidation: the amount of oxide; Comparativeexample: comparing embodiment; Example: embodiment.)

As shown in figure 16, the formed oxide of 4wt%Cu and surplus Sn that comprises was respectively 687g among the Sn4Cu after 1 hour, be 743g after 2 hours, and be 805g after 3 hours, and therefore 3 hours formed oxide aggregates is 2235g.The formed oxide of 4wt%Cu, 0.1wt%Ni, 0.005%P and surplus Sn that comprises was respectively 567g among the Sn4Cu0.1Ni0.005P after 1 hour, be 641g after 2 hours, be 773g after 3 hours, and therefore 3 hours formed oxide aggregates are 1891g.The reason that the oxide that forms at Sn4Cu0.1Ni0.005P is lower than the oxide that forms in Sn4Cu is that P has played the effect of the amount of reduction oxide.

Yet, when the Si of 0.005wt% adds Sn ₄During Cu, the quantity of oxide was 461g after 1 hour respectively, was 532g after 2 hours, 596g after 3 hours, and therefore 3 hours formed oxide aggregates are 1589g, it is lower than is not having the Sn of Si ₄The amount of formed oxide among Cu and the Sn4Cu0.005P.In addition, when the Si of 0.05wt% joined wherein, the amount of oxide can further reduce.

When the Co of 0.005wt% adds Sn4Cu0.005Si, the quantity of oxide was respectively 445g after 1 hour, be 449g after 2 hours, 552g after 3 hours, and therefore 3 hours formed oxide aggregates are 1488g, and it is lower than the amount of formed oxide among Sn4Cu0.005P and the Sn4Cu0.005Si.

By add the very cobalt of a small amount of (0.005wt%) in Sn4Cu0.05Si, the oxide of fusion welding can minimize to the degree identical with the oxide of the solder alloy that has only added 0.05wt%Si.

Therefore, can find out, by in Sn-Cu base alloy, adding a small amount of Si, can continue to prevent the formation of oxide.Can find out that also by further adding therein the very cobalt of a small amount of (being lower than 0.01wt%), it is minimum that required silicone content can reach by the cooperative effect of Si and Co.

The copper corrosion rate that depends on silicon and cobalt component is described below with reference to Figure 17.

Figure 17 shows the experimental result of copper corrosion rate.

Figure 17

As shown in figure 17, the copper corrosion rate that comprises the Sn4Cu of 4wt%Cu and surplus Sn is 58.9%.The copper corrosion rate that comprises the Sn4Cu0.1Ni0.005P of 4wt%Cu, 0.1wt%Ni, 0.005wt%P and surplus Sn is 53.9%.

When the Si of 0.005wt% added Sn4Cu, the copper corrosion rate was 57.1%, and added fashionablely as the Si of 0.05wt%, and the copper corrosion rate is 52%, and it is lower than the copper corrosion rate of Sn4Cu and Sn4Cu0.1Ni0.005P.

When 0.01wt%Co added Sn4Cu0.005Si, the copper corrosion rate significantly was reduced to 10.2%.Can see, by in comprising the base alloy of 0.05wt%Si, adding a small amount of Co that is lower than 0.01wt%, significantly reduce the copper corrosion rate owing to the synergy of silicon and cobalt.

Amount, fusion temperature, variable color degree, wetting time, copper corrosion rate and the bond strength of the oxide that depends on silicon and cobalt component are described below with reference to table 6.In addition, from these results, will estimate optimum content at Sn-Cu base Silicon In Alloys and cobalt.

Table 6 has been listed experimental data and the fusion temperature of Figure 22 and 23, the experimental data of variable color degree and bond strength.

Table 6 high temperature SnCu scolder

As shown in Figure 6, the fusion temperature that comprises the Sn4Cu of 4wt%Cu and surplus Sn is 357 ℃, and the fusion temperature of Sn4Cu0.1Ni0.005P is 362 ℃.

Fusion temperature is 358 ℃ when the Si of 0.005wt% adds Sn4Cu, and fusion temperature is increased to 361 ℃ when the Si of 0.1wt% adds Sn4Cu.

When the Co of 0.01wt% added Sn4Cu0.05Si, fusion temperature was increased to 361 ℃.Usually, according to the metal alloy phasor, if add dystectic Si (more than 1400 ℃) in the scope of predeterminated level in a small amount of surpassing in low melting point Sn alloy, the fusion temperature of Sn alloy can significantly increase so.Therefore, the Si content in the Sn alloy need to limit and be lower than certain level.

As shown in table 6, the variable color degree that comprises the Sn4Cu of 4wt%Cu and surplus Sn is 19.2, and comprises that the variable color degree of the Sn4Cu0.1Ni0.005P of 4wt%Cu, 0.1wt%Ni, 0.005wt%P and surplus Sn is 16.8.

The variable color degree is 17.3 when 0.005wt%Si adds Sn4Cu, and the variable color degree significantly is reduced to 13.42 when 0.05wt%Si adds wherein, and it is lower than the variable color degree of Sn4Cu and Sn4Cu0.1Ni0.005P.

When 0.005wt%Co added Sn4Cu0.005Si, the variable color degree significantly was reduced to 9.62, and when 0.01wt%Co added Sn4Cu0.005Si, the variable color degree significantly was reduced to 5.3.

Therefore, can reach a conclusion, the variable color of Sn-Cu base alloy can reduce by adding therein a small amount of Si, and Sn-Cu base alloy since the variable color of oxidation also can significantly reduce by adding therein a small amount of Si and Co.

Shown in the chart 6, comprise 4wt%Cu and surplus Sn Sn4Cu be 90kgf in conjunction with breaking load, and comprise 4wt%Cu, 0.1wt%Ni, 0.005wt%P Sn4Cu0.1Ni0.005P be 98kgf in conjunction with breaking load.

When 0.005wt%Si adds Sn4Cu, be 100kgf in conjunction with breaking load, and when 0.05wt%Si adds wherein, significantly be increased to 130kgf in conjunction with breaking load, its be higher than Sn4Cu and Sn4Cu0.1Ni0.005P in conjunction with breaking load.

When 0.01wt%Co adds Sn4Cu0.005Si, significantly be increased to 139kgf in conjunction with breaking load.

Therefore, can reach a conclusion, can the increasing by adding therein a small amount of Si in conjunction with breaking load of Sn-Cu base alloy, and can significantly increase by adding therein a small amount of Si and Co,

As mentioned above, according to the lead-free solder compounds of present embodiment, comprise the Sn-Cu base alloy that has added a small amount of Si, can continue and reduce significantly oxidation, reduce copper corrosion and variable color, and increase and finish make and break and split load.

Yet when the Si that adds surpasses a certain degree, namely quantity surpasses 0.05wt%, and the fusion temperature of solder alloy increases so.Therefore, preferred Si content is 0.001wt% to 0.05wt% in the solder alloy.

The Co that adds in the Sn-Cu base alloy can significantly fall low-alloyed fusion temperature and increase the bond strength of binding site.Yet in the high-temperature solder alloy, when the Cu that adds was lower than 2wt%, the impact of Cu was inadequate, and when the Cu that adds was higher than 5wt%, fusion temperature had increased on the contrary.Therefore, preferred copper content is 2wt% to 5wt% in the solder alloy.Sn is the requisite component of lead-free solder and uses as underlying metal.

As mentioned above, each Si and the Co that add in the Sn-Cu base alloy have the effect that prevents that oxide from forming and preventing variable color, and can significantly increase effect by adding together them.

Present embodiment also can be embodied as the PCB of the use high temperature lead-free solder alloy that comprises that electronic component is mounted thereon or comprise the electronic device of the use high temperature lead-free solder alloy that a plurality of electronic components are mounted thereon.As mentioned above, the high temperature lead-free solder alloy comprises the cobalt of Si, 0.001wt% to 0.01wt% of copper, 0.001wt% to 0.05wt% of 2wt% to 5wt% and the tin of surplus.

Equally, the high temperature lead-free solder compound, and use PCB and the electronic device of insulation lead-free solder compounds to have and mechanical property and workability like Sn-Pb alloy and the Sn-Cu alloy type.And then, by in two metamember systems, add silicon and cobalt the two and do not add lead (Pb), can surpass the oxidation that continues and effectively prevent fusion welding under 400 ℃ the high temperature.Further, by only adding very small amount of silicon and cobalt, they just can keep welding temperature and the wetability of typical lead-free solder, the corrosion that prevents from welding copper packing among rear variable color and the PCB, and significantly increase mechanical performance.

High temperature lead-free solder compound according to present embodiment can comprise tin (Sn), copper (Cu), nickel (Ni), silicon (Si) and cobalt (Co).

The effect of component aspect anti-oxidation of silicon and cobalt described below with reference to Figure 18

Figure 18 shows the experimental data of the amount of oxide.

Figure 18

(Amount of oxidation: the amount of oxide; After After 1hour:1 hour; After Afer 2hour:2 hour; After Afer 3hour:3 hour; Oxidation rate: oxidation rate; Comparativeexample: comparing embodiment; Example: embodiment.)

As shown in figure 18, the quantity that comprises the oxide that forms among the Sn4Cu0.1Ni0.005P of 4wt%Cu, 0.1wt%Ni, 0.005wt%P and surplus Sn was respectively 567g after 1 hour, be 641g after 2 hours, be 773g after 3 hours, and therefore 3 hours formed oxide aggregates are 2235g.The quantity of formed oxide was 567g after 1 hour respectively among the Sn4Cu, was 641g after 2 hours, was 773g after 3 hours, and therefore 3 hours formed oxide aggregates are 1981g.

The reason that the amount of the oxide that forms among the Sn4Cu0.1Ni0.005P is lower than the amount of the oxide that forms among the Sn4Cu is that Ni and P have played the effect that reduces the amount of oxide.

When 0.005wt%Si adds Sn4Cu0.1Ni0.005P, the quantity of oxide was respectively 390g after 1 hour, be 441g after 2 hours, be 512g after 3 hours, and therefore 3 hours formed oxide aggregates are 1343g, and it is lower than the amount of formed oxide in the Sn4Cu that does not have Si and Sn4Cu0.1Ni0.005P.In addition, when the Si of 0.05wt% adds wherein, the quantity of oxide can further reduce.

When 0.005wt%Co adds Sn4Cu0.1Ni0.005P0.005Si, the quantity of oxide was respectively 365g after 1 hour, be 426g after 2 hours, be 478g after 3 hours, and therefore 3 hours formed oxide aggregates are 1269g, and it is lower than the amount of the oxide that forms in Sn4Cu0.1Ni0.005P0.005Si.

By adding the very cobalt of a small amount of (0.005wt%) in Sn4Cu0.1Ni0.005P0.005Si, the oxidation of fusion welding can minimize to the degree of oxidation of the solder alloy that equals only to add 0.005wt%Si.

Therefore can find out, by in Sn-Cu-Ni-P base alloy, adding a small amount of Si, can continue to prevent that oxide from forming.Also can find out, by further adding the very Co of a small amount of (being lower than 0.01wt%) to it, because the synergy of Si and Co makes required Si content minimum.

The copper corrosion rate that depends on silicon and cobalt component is described below with reference to Figure 19.

Figure 19

(Erosion rate: rate of corrosion; Temp: temperature; Time 60sec: 60 seconds time; Comparativeexample: comparing embodiment; Example: embodiment.)

As shown in figure 19, the copper corrosion rate that comprises the Sn4Cu0.1Ni0.005P of 4wt%Cu, 0.1wt%Ni, 0.005wt%P and surplus Sn is 53.4%.The copper corrosion rate of Sn4Cu is 58.9%.

When the Si of 0.005wt% added Sn4Cu0.1Ni0.005P, the copper corrosion rate was 49.5%, and added fashionablely as the Si of 0.05wt%, and the copper corrosion rate is 45.5%, and it is lower than the copper corrosion rate of Sn4Cu and Sn4Cu0.1Ni0.005P.

When the Co of 0.01wt% added Sn4Cu0.1Ni0.005Si, the copper corrosion rate significantly was reduced to 10.3%.Can see that when adding the Co of very a small amount of (being lower than 0.01wt%) in comprising the base alloy of 0.05wt%Si, the copper corrosion rate can be because the cooperative effect of silicon and cobalt and significantly reducing.

Amount, fusion temperature, variable color degree, wetting time, copper corrosion rate and the bond strength of the oxide that depends on silicon and cobalt component are described below with reference to table 7.In addition, from these results, will estimate optimum content at Sn-Cu-Ni-P base Silicon In Alloys and cobalt.

Table 7 has been listed experimental data and the fusion temperature of Figure 24 and 25, the experimental data of variable color degree and bond strength.

Table 7 high temperature SnCuNiP scolder

As shown in table 7, the fusion temperature of Sn4Cu0.1Ni0.005P is 362 ℃, and comprises that the fusion temperature of the Sn4Cu of 4wt%Cu and surplus Sn is 357 ℃.

When the Si of 0.005wt% added Sn4Cu0.1Ni0.005P, fusion temperature was 362 ℃, and when the Si of 0.1wt% added Sn4Cu0.1Ni0.005P, fusion temperature significantly rose to 365 ℃.When the Co of 0.01wt% added Sn4Cu0.1Ni0.005P0.05Si, fusion temperature significantly rose to 364 ℃.In general, according to the metal alloy phasor, if add a small amount of Si that surpasses the high-melting-point (more than 1400 ℃) of predeterminated level in low melting point Sn alloy, the fusion temperature of Sn alloy can significantly increase so.Therefore, the Si content in the Sn alloy need to limit and be lower than certain level.

As shown in table 7, the variable color degree of Sn4Cu0.1Ni0.005P is 16.8, and the variable color degree of Sn4Cu is 19.2.

When the Si of 0.005wt% added Sn4Cu0.1Ni0.005P, the variable color degree was 14.8, and when the Si of 0.05wt% added wherein, the variable color degree significantly was reduced to 10.2, and it is lower than the variable color degree of Sn4Cu and Sn4Cu0.1Ni0.005P.

When the Co of 0.005wt% added Sn4Cu0.1Ni0.005P0.005Si, the variable color degree significantly was reduced to 6.5, and when the Co of 0.01wt% added wherein, the variable color degree significantly was reduced to 4.07.

Therefore, can reach a conclusion, Sn-Cu-Ni-P base alloy can reduce variable color by adding therein a small amount of Si, and since the variable color degree of the basic alloy of the Sn-Cu-Ni-P that oxidation produces also can significantly reduce by adding therein very small amount of Si and Co.

As shown in table 7, comprise 4wt%Cu, 0.1wt%Ni, 0.005%P and surplus Sn Sn4Cu0.1Ni0.005P be 98kgf in conjunction with breaking load, and comprise 4wt%Cu and surplus Sn Sn4Cu be 90kgf in conjunction with breaking load.

When the Si of 0.005wt% adds Sn4Cu0.1Ni0.005P, be 106kgf in conjunction with breaking load, and when 0.05wt%Si adds wherein, significantly be increased to 115kgf in conjunction with breaking load, its be higher than Sn4Cu and Sn4Cu0.1Ni0.005P in conjunction with breaking load.

When the Co of 0.01wt% adds Sn4Cu0.1Ni0.005P0.005Si, significantly be increased to 122kgf in conjunction with breaking load.

Therefore, can reach a conclusion, can the increasing by adding therein a small amount of Si in conjunction with breaking load of Sn-Cu-Ni-P base alloy, and can significantly increase by adding therein very small amount of Si and Co.

As mentioned above, according to the lead-free solder compounds of present embodiment, comprise the Sn-Cu-Ni-P base alloy that has added a small amount of Si, can continue and significantly reduce oxidation, keep wetability, reduce copper corrosion and variable color and increase in conjunction with breaking load.

Yet when the Si amount that adds surpasses to a certain degree, namely quantity surpasses 0.05wt%, and the fusion temperature of solder alloy will increase so, and therefore, preferred Si content is 0.001% to 0.05wt% in the solder alloy.

The Co that adds in the Sn-Cu-Ni-P base alloy can significantly fall low-alloyed fusion temperature temperature and increase the bond strength of binding site.Yet when the Cu that adds was lower than 2wt%, the impact of Cu was inadequate, and when the Cu that adds was higher than 5wt%, fusion temperature had increased on the contrary.Therefore, preferred copper content is 2wt% to 5wt% in the solder alloy.Sn is the requisite component of lead-free solder and uses as underlying metal.

As mentioned above, each Si that adds in the Sn-Cu base alloy and Co have and prevent the effect that forms the formation of oxide and prevent variable color, and can significantly improve effect by adding together them.

Present embodiment also can be embodied as the PCB of the use leadless welding alloy that comprises that electronic component is mounted thereon or comprise the electronic device of the use leadless welding alloy that a plurality of electronic components are mounted thereon.As mentioned above, the high temperature lead-free solder alloy comprises silicon, 0.001% to 0.01% cobalt and the tin of surplus of P, 0.001wt% to 0.05wt% of nickel, the 0.001wt% to 0.2wt% of copper, the 0.001wt% to 1.0wt% of 2wt% to 5wt%.

Embodiment 3

The lead-free solder compounds that is used for dilution according to present embodiment can comprise nickel (Ni), silicon (Si), phosphorus (P), cobalt (CO) and tin (Sn).

Silicon and cobalt component are described in the effect aspect the anti-oxidation below with reference to Figure 20.

Figure 20 has illustrated the experimental data of the amount of the oxide of being measured by follow procedure.Silicon and cobalt join in the Sn-Ni-P base alloy.Make resulting alloy molten to make solder compound.On hot plane, solder compound in being the SUS crucible of 160mm, diameter is heated to 260 ℃.Then, use diameter to stir respectively solder compound 1 hour, 2 hours and 3 hours as the agitator of 140mm with the speed of 60rpm, and therefrom extract oxide at every turn and carry out weighing.

After this, scolder is solidified, and subsequently from scolder cutting solder sample.The cutting surfaces of polishing solder sample.Then, the composition of the alloying element in the solder sample uses Auger electron spectroscopy (PHI700 is made by Ulvac PHI) to analyze, and this is the instrument that uses the element of X-ray analysis metal surface, to determine whether wherein still to exist alloying element.

Figure 20

As shown in figure 20, the amount of the oxide that forms in the Sn0.06Ni0.005P that comprises 0.06wt%Ni, 0.005wt%P and surplus Sn was respectively 125g after 1 hour, be 195g after 2 hours, and be 320g after 3 hours, and therefore 3 hours formed oxide aggregates are 640g.

When the Si of 0.005wt% adds Sn0.06Ni0.005P, the quantity of oxide was respectively 105g after 1 hour, be 134g after 2 hours, and be 155g after 3 hours, and therefore 3 hours formed oxide aggregates are 394g, and it is lower than the amount of the oxide that forms in not having the Sn0.06Ni0.005P of Si.

In a word, when adding the P of 0.005wt%, interior scum silica frost quantity significantly increases during 2 hours to 3 hours.Yet, when adding the Si of 0.005wt%, during 2 hours to 3 hours the amount of formed oxide and during 1 hour to 2 hours the amount of formed oxide close.Therefore, can reach a conclusion, Si is more effective than P aspect lasting anti-oxidation.In addition, can find out the amount that when adding the Si of 0.05wt%, has further reduced oxide.

When the Co of 0.001wt% adds Sn0.06Ni0.005P0.005Si, the quantity of oxide was respectively 81g after 1 hour, be 99g after 2 hours, and be 110g after 3 hours, and therefore 3 hours formed oxide aggregates are 290g, and it is lower than the oxide aggregate of Sn0.06Ni0.005P and Sn0.06Ni0.005P0.05Si.

When very the Co of a small amount of (0.001wt%) added Sn0.06Ni0.005P0.005Si, the energy of oxidation of fusion welding minimized to the degree identical with the oxidation of the solder alloy that only adds 0.001wt%Si.

Can find out, by adding Si and Co, compare with comparing embodiment, can reduce the amount of oxide.

Therefore, can find out, by in Si-Ni-P base alloy, adding a small amount of Si, compare with the solder compound of typical adding P, formation that can the continuous decrease oxide.Can see that also by further adding therein the very Co of a small amount of (being lower than 0.01wt%), required silicone content reaches minimum during owing to the synergy of Si and Co.

Silicon and cobalt component are described in the impact aspect the wetability below with reference to Figure 21.

Figure 20 has illustrated the experimental result of wetability.In order to study the wetting time of solder compound, use SP2 solder wettability tester (being made by MaiCom Co., Ltd) with scolder 260 ℃ of lower meltings.Copper tip is immersed in the fusion welding surface 1mm degree of depth to measure the wetting time after immersing 5 seconds.

Figure 21

(Temp: temperature; Wetting Time (sec): wetting time (second); Comparative example: comparing embodiment; Example: embodiment.)

As shown in figure 21, the wetting time that comprises the Sn0.06Ni0.005P of 0.06wt%Ni, 0.005wt%P and surplus Sn is 2.15 seconds.

When the Si of 0.005wt% added Sn0.06Ni0.005P, wetting time foreshortened to for 2.05 seconds.On the contrary, when adding the Si of 0.05wt%, wetting time increases to 2.17 seconds on the contrary.

This may be because when very the Si of a small amount of (0.005wt%) adds scolder, removed oxygen from the base alloy scolder (SnAgCu) of melting, thereby improved wetability.Yet when adding the Si that surpasses 0.05wt% quantity, the increase of the fusion temperature of scolder and extra Si reduce the wetability of fusion welding.In addition, can see, because can the cobalt of a small amount of (being lower than 0.01wt%) minimizes the quantity that adds silicon by adding therein very, the acid resistance that has therefore improved molten braze alloy has also reduced wetability simultaneously.

The copper corrosion rate that depends on silicon and copper component is described below in conjunction with Figure 22.

Figure 22

(Erosion Rate: rate of corrosion; Temp: temperature; Time (sec): time (second); Comparativeexample: comparing embodiment; Example: embodiment.)

As shown in figure 22, the copper corrosion rate that comprises the Sn0.06Ni0.005P of 0.06wt%Ni, 0.005wt% and surplus Sn is 48.8%.

When the Si of 0.005wt% added Sn0.06Ni0.005P, the copper corrosion rate was 46.5%, and added fashionablely as the Si of 0.05wt%, and the copper corrosion rate is 44.5%, and it is less than the copper corrosion rate of Sn0.06Ni0.005.

When very the Co of a small amount of (0.01wt%) added Sn0.06Ni0.005P0.005Si, the copper corrosion rate significantly was reduced to 11.9%.Can see, by in comprising the base alloy of 0.05wt%Si, adding the very Co of a small amount of (being lower than 0.01wt%), can significantly reduce the copper corrosion rate owing to the synergy of silicon and cobalt.

Amount, fusion temperature, speed change degree, wetting time, copper corrosion rate and the bond strength of the oxide that depends on silicon and cobalt component are described below with reference to table 8.In addition, will estimate silicon Sn-Ni-P base alloy and the optimum content of cobalt from these results.

Table 8 has been listed Figure 26,27 and 28 test data, and the test data of fusion temperature, variable color degree and bond strength.

Table 8SnNiP scolder diluent

As shown in table 8, the fusion temperature that comprises the Sn0.06Ni0.005P of 0.06wt%Ni, 0.005wt%P and surplus Sn is 236 ℃.When the Si of 0.005wt% added Sn0.06Ni0.005P, fusion temperature was 236 ℃.When the Si of 0.1wt% added Sn0.06Ni0.005P, fusion temperature was elevated to 238 ℃.

When the Co of 0.01wt% added Sn0.06Ni0.005P0.05Si, fusion temperature was increased to 237 ℃.In general, according to the metal alloy phasor, if add a small amount of Si that surpasses the high-melting-point (more than 1400 ℃) of predeterminated level in low melting point Sn alloy, the fusion temperature of Sn alloy can significantly increase so.Therefore, the Si content in the Sn alloy need to limit and be lower than certain level.

As shown in table 8, the variable color degree that comprises the Sn0.06Ni0.005P of 0.06wt%Ni, 0.005wt%P and surplus Sn is 21.03.

When the Si of 0.005wt% added Sn0.06Ni0.005P, the variable color degree was 18.76, and when the Si of 0.05wt% added wherein, the variable color degree significantly was reduced to 12.02, and it is lower than the variable color degree of Sn0.06Ni0.005P.

When the Co of 0.005wt% added Sn0.06Ni0.005P0.005Si, the variable color degree significantly was reduced to 9.9, and when the Co of 0.01wt% added Sn0.06Ni0.005P0.005Si, the variable color degree significantly was reduced to 4.5.

Therefore, can reach a conclusion, the variable color degree of Sn-Ni-P base alloy can reduce by adding therein a small amount of Si, and since the variable color of the Sn-Ag-Cu base alloy of solder alloy oxidation also can significantly reduce by adding therein very small amount of Si and Co.

As shown in table 8, comprise 0.06wt%Ni, 0.005wt%P and surplus Sn Sn0.06Ni0.005P be 83kgf in conjunction with breaking load.

When the Si of 0.005wt% adds Sn0.06Ni0.005P, be 94kgf in conjunction with breaking load, and when the Si of 0.05wt% adds wherein, obviously bring up to 96kgf in conjunction with breaking load, its be higher than Sn0.06Ni0.005P in conjunction with breaking load.

When the Co of 0.005wt% adds Sn0.06Ni0.005P0.005Si, be 95kgf in conjunction with breaking load, its be higher than Sn0.06Ni0.005P in conjunction with breaking load.When the Co of 0.01wt% adds Sn0.06Ni0.005P0.005Si, obviously bring up to 100kgf in conjunction with breaking load.

Therefore, can reach a conclusion, can the reducing by adding therein a small amount of Si in conjunction with breaking load of Sn-Ni-P base alloy, and also can significantly reduce by adding therein very small amount of Si and Co.

As mentioned above, according to the lead-free solder compounds of present embodiment, comprise the Sn-Ni-P base alloy that adds a small amount of Si, welding temperature and the wetability that can keep typical lead-free solder compounds, the continuous decrease oxidation reduces copper corrosion rate and variable color, and increases in conjunction with breaking load.

In addition, by in comprising the Sn-Ni-P base alloy of a small amount of Si, adding very small amount of Co, compare with the base alloy that only adds Si, might be significantly and reduce constantly the amount of oxide, reduce copper corrosion and variable color, and increase in conjunction with breaking load, keep simultaneously wetability.

Yet when the Si quantity that adds surpasses to a certain degree, namely quantity surpasses 0.05wt%, and the fusion temperature of solder alloy raises so, and its wetability descends.Therefore, preferred Si content is 0.001wt% to 0.05wt% in the solder alloy.

In addition, though since when adding the very small amount of Co be lower than 0.01wt% Co also demonstrated good effect, so preferred Co content is 0.001wt% to 0.01wt% in the solder alloy.

The Cu that adds in the Sn-Ni-P base alloy has played the effect that slightly reduces the alloy melting temperature and improve the bond strength of junction.Yet when the Cu quantity that adds was lower than 0.1wt%, the effect of Cu was inadequate, and when the Cu quantity that adds surpassed 2wt%, fusion temperature had increased on the contrary.Therefore, preferred copper content is 0.1wt% to 2wt% in the solder alloy.The Ni that adds in the Sn-Ni-P base alloy can avoid the growth of mating surface place intermetallic compound.Preferred Ni content is 0.001wt% to 1.0wt% in the solder alloy.This is because of the increase along with nickel content, and fusion temperature increases, and wetability and dispersed the reduction.The P that adds in the Sn-Cu-P-Ni base alloy plays in welding and reduces the effect that oxide forms, thereby has therefore improved the operability of welding.Preferred P content is 0.001wt% to 0.2wt%.Sn is the requisite component of lead-free solder and uses as underlying metal.

Present embodiment also can be embodied as and comprise use dilution that electronic component is mounted thereon with the PCB of leadless welding alloy or comprise the electronic device of the use dilution usefulness leadless welding alloy that a plurality of electronic components are mounted thereon.As mentioned above, dilution comprises the cobalt of Si, 0.001wt% to 0.01wt% of nickel, 0.001wt% to 0.05wt% of 0.001wt% to 1.0wt% and the tin of surplus with leadless welding alloy.

Dilution according to present embodiment can comprise tin (Sn) with leadless welding alloy, silver (Ag), phosphorus (P), silicon (Si) and cobalt (Co).

The effect of component aspect anti-oxidation of silicon and cobalt described below with reference to Figure 23.

Figure 23 shows the experimental data of the amount of oxide.

Figure 23

(Erosion Rate: rate of corrosion; After After 1hour:1 hour; After Afer 2hour:2 hour; After Afer3hour:3 hour; Comparative example: comparing embodiment; Example: embodiment.)

As shown in figure 23, the amount of the oxide that forms in the Sn3Ag0.005P that comprises 3wt%Ag, 0.005wt%P and surplus Sn was respectively 240g after 1 hour, being 275g after 2 hours, was 370g after 3 hours, and therefore 3 hours formed oxide aggregates are 885g.

When the Si of 0.005wt% adds Sn3Ag0.005P, the amount of oxide was respectively 131g after 1 hour, be 145g after 2 hours, and be 179g after 3 hours, and therefore 3 hours formed oxide aggregates are 455g, and it is less than the amount of the oxide that forms in not having the Sn3Ag0.005P of Si.

When the P of 0.005wt% adds fashionablely, scum silica frost quantity significantly increases during 2 hours to 3 hours.Yet, when adding the Si of 0.005wt%, the amount of the oxide that during the amount of the oxide that forms during 2 hours to 3 hours is similar to 1 hour to 2 hours, forms.Therefore, can judge that Si is more effective than P aspect lasting anti-oxidation.In addition, when adding the Si of 0.05wt%, the amount of oxide further descends.

When the Co of 0.01wt% adds Sn3Ag0.005P0.05Si, the quantity of oxide was respectively 60g after 1 hour, be 75g after 2 hours, and be 94g after 3 hours, and therefore 3 hours formed oxide aggregates are 229g, and it is lower than the amount of the oxide of Sn3Ag0.005P and Sn3Ag0.005P0.05Si.

When the Co of 0.005wt% adds Sn3Ag0.005P0.005Si, compare with the comparing embodiment that has added a small amount of Si and Co, can reduce the quantity of oxide.

Therefore, can find out, by in Sn-Ag-P base alloy, adding a small amount of Si, with the typical solders Compound Phase ratio that adds P, formation that can the continuous decrease oxide.Can find out that also by further adding therein the very cobalt of a small amount of (being lower than 0.01wt%), the synergy by Si and Co minimizes required silicone content.

Silicon and cobalt component are described in the effect aspect the wetability below with reference to Figure 24.

Figure 24

(Wetting Time (sec): wetting time (second); Temp: temperature; Comparative example: comparing embodiment Example: embodiment.)

As shown in figure 24, the wetting time that comprises the Sn3Ag0.005P of 3wt%Ag, 0.005wt%P and surplus Sn is 0.7 second.When the Si of 0.005wt% added Sn3Ag0.005P, wetting time was 0.63 second.On the contrary, when the Si of 0.05wt% adds fashionablely, wetting time is increased to 0.72 second on the contrary.

This may be because when very the Si of a small amount of (0.005wt%) adds scolder, removed oxygen from melting base alloy scolder (SnAgP), has therefore increased wetability.Yet, when the Si amount that adds surpasses 0.05wt%, the wetability that the fusion temperature increase of scolder and excessive Si have reduced fusion welding.

In addition, can see that owing to the adding that surpasses the Si that limits the quantity of, the acid resistance of molten braze alloy is improved and simultaneously, by adding therein the very Co of a small amount of (being lower than 0.01wt%), can makes the silicon above limiting the quantity of of adding minimum.

The copper corrosion rate that depends on silicon and cobalt component is described below with reference to Figure 25.

Figure 25

As shown in figure 25, the copper corrosion rate that comprises the Sn3Ag0.005P of 3wt%Ag, 0.005wt%P and surplus Sn is 58.8%.

When the Si of 0.005wt% added Sn3Ag0.005P, the copper corrosion rate was 56.5%, and added fashionablely as the Si of 0.05wt%, and the copper corrosion rate is 31.7%, and it is lower than the copper corrosion rate of Sn3Ag0.005P.

When the Co of 0.01wt% added Sn3Ag0.005P0.005Si, the copper corrosion rate significantly dropped to 14%.Can see, by in containing the base alloy of 0.05wt%Si, adding the very Co of a small amount of (being lower than 0.01wt%), significantly reduce the copper corrosion rate owing to the cooperative effect of silicon and cobalt.

Amount, fusion temperature, variable color degree, wetting time, copper corrosion rate and the bond strength of the oxide that depends on silicon and cobalt component are described below with reference to table 9.In addition, from these results, will estimate optimum content at Sn-Ag-P base Silicon In Alloys and cobalt.

Table 5 has been listed Figure 23,24 and 25 experimental data and fusion temperature, the experimental data of variable color degree and bond strength.

Table 9SnAgP scolder diluent

As shown in table 9, the fusion temperature that comprises the Sn3Ag0.005P of 3wt%Ag, 0.005wt%P and surplus Sn is 224 ℃.When the Si of 0.005wt% added Sn3Ag0.005P, fusion temperature was 225 ℃.When the Si of 0.1wt% added Sn3Ag0.005P, fusion temperature rose to 228 ℃.

When the Co of 0.01wt% added Sn3Ag0.005P0.05Si, fusion temperature was elevated to 227 ℃.In general, according to the metal alloy phasor, if add a small amount of Si that surpasses the high-melting-point (more than 1400 ℃) of predeterminated level in low melting point Sn alloy, the fusion temperature of Sn alloy can significantly increase so.Therefore, the Si content in the Sn alloy need to limit and be lower than certain level.

As shown in table 9, the variable color degree that comprises the Sn3Ag0.005P of 3wt%Ag, 0.005wt%P and surplus Sn is 11.8.

When the Si of 0.005wt% added Sn3Ag0.005P, the variable color degree was 10.11, and when the Si of 0.05wt% adds wherein, the variable color degree significantly is reduced to 6.7, and it is lower than the variable color degree of Sn3Ag0.005P.

When the Co of 0.005wt% added Sn3Ag0.005P0.005Si, the variable color degree significantly dropped to 4.33, and when the Co of 0.01wt% added Sn3Ag0.005P0.005Si, the variable color degree significantly was reduced to 3.82.

Therefore, can reach a conclusion, Sn-Ag-P base alloy can reduce variable color by adding therein a small amount of Si, and can significantly reduce by adding therein very small amount of Si and Co because the Sn-Ag-P base alloy variable color of solder alloy oxidation.

The below obtained to be listed in the table 9 in conjunction with breaking load.The line that applies the diameter 2mm of Sn-Bi is vertically inserted in the hole of PCB substrate, and apply wave soldering thereon, with the preparation sample.Then, use the tensile testing machine test wherein in conjunction with breaking load (kgf).

As shown in table 9, comprise 3wt%Ag, 0.005wt%P and surplus Sn Sn3Ag0.005P be 87kgf in conjunction with breaking load.

When the Si of 0.005wt% adds Sn3Ag0.005P, be 94kgf in conjunction with breaking load, and add wherein as the Si of 0.05wt% that significantly be increased to 101kgf in conjunction with breaking load, it is higher than Sn ₃Ag _0.005In conjunction with breaking load.

When the Co of 0.005wt% adds Sn3Ag0.005P0.005Si, be 97kgf in conjunction with breaking load, its be higher than Sn3Ag0.005P in conjunction with breaking load.When the Co of 0.01wt% adds Sn3Ag0.005P0.005Si, showing in conjunction with breaking load and to increase to 105kgf.

Therefore, can reach a conclusion, can the improving by adding therein a small amount of Si in conjunction with breaking load of Sn-Ag-P base alloy, and can significantly improve by adding therein very small amount of Si and Co.

As mentioned above, according to the lead-free solder compounds of present embodiment, comprise the Sn-Ag-P base alloy that adds a small amount of Si, can keep solder joint and the wetability of typical lead-free solder compounds, the continuous decrease oxidation reduces copper corrosion and variable color, and increases in conjunction with breaking load.

In addition, by in comprising the Sn-Ag-P base alloy of a small amount of Si, adding very small amount of Co, compare with the base alloy that has only added Si, might highly significant and reduce constantly the amount of oxide, reduce copper corrosion rate and variable color, and increase in conjunction with breaking load, keep simultaneously wetability.

When the Co quantity that adds surpasses predetermined extent, namely be higher than 0.01wt%, then wetability reduces.In addition, even because adding is lower than the very small amount of Co of 0.01wt% and the silicon of a small amount of (0.05wt%), and Co has also demonstrated good effect, so preferred Co content is 0.001wt% to 0.01wt% in the solder alloy.

The Cu that adds in the Sn-Ag-P base alloy has played the effect that slightly reduces the alloy melting temperature and improve the bond strength of junction.Yet when the Cu quantity that adds was lower than 0.1wt%, the effect of Cu was inadequate, and when the Cu quantity that adds surpassed 2wt%, fusion temperature had increased on the contrary.Therefore, preferred copper content is 0.1wt% to 2wt% in the solder alloy.The Ag that adds in the Sn-Ag-P base alloy has played reduction alloy melting temperature and has improved in conjunction with the dispersiveness of base alloy and the effect of thermal fatigue property.In addition, Ag is nontoxic.But, be that the effect of Ag is inadequate, and when the Ag quantity that adds surpassed 4wt%, fusion temperature had raise on the contrary when the Ag quantity that adds is lower than 0.1wt%.Therefore, preferred Ag content is 0.1wt% to 4.0wt%.The P that adds in the Sn-Cu-P-Ni base alloy plays in welding and reduces the effect that oxide forms, thereby has therefore improved the operability of welding.Preferred P content is 0.001wt% to 0.2wt%.Sn is the requisite component of lead-free solder and uses as underlying metal.

As mentioned above, Si and Co have separately and prevent that oxide from forming and preventing the effect of variable color, and these effects can significantly increase by adding simultaneously them,

Present embodiment also may be embodied as and comprises use dilution that electronic component is mounted thereon with the PCB of leadless welding alloy or comprise the electronic device of the use dilution usefulness leadless welding alloy that a plurality of electronic components are mounted thereon.As mentioned above, dilution comprises the silver of 0.1wt% to 4wt%, the phosphorus of 0.001wt% to 0.2wt%, the silicon of 0.001wt% to 0.05wt%, the cobalt of 0.001wt% to 0.01wt% and the tin of surplus with leadless welding alloy.

Claims

1. a lead-free solder compounds is comprised of the copper of 0.1wt% to 2wt%, the nickel of 0.001wt% to 1.0wt%, the phosphorus of 0.001wt% to 0.2wt%, the silicon of 0.001wt% to 0.05wt%, the cobalt of 0.001wt% to 0.01wt% and the tin of surplus.

2. printed circuit board (PCB) that uses lead-free solder compounds, wherein lead-free solder compounds is comprised of the copper of 0.1wt% to 2wt%, the nickel of 0.001wt% to 1.0wt%, the phosphorus of 0.001wt% to 0.2wt%, the silicon of 0.001wt% to 0.05wt%, the cobalt of 0.001wt% to 0.01wt% and the tin of surplus.

3. electronic equipment that uses lead-free solder compounds, wherein lead-free solder compounds is comprised of the copper of 0.1wt% to 2wt%, the nickel of 0.001wt% to 1.0wt%, the phosphorus of 0.001wt% to 0.2wt%, the silicon of 0.001wt% to 0.05wt%, the cobalt of 0.001wt% to 0.01wt% and the tin of surplus.

4. a high temperature lead-free solder compound is comprised of the copper of 2wt% to 5wt%, the silicon of 0.001wt% to 0.05wt%, the cobalt of 0.001wt% to 0.01wt% and the tin of surplus.

5. printed circuit board (PCB) that uses the high temperature lead-free solder compound, wherein the high temperature lead-free solder compound is comprised of the copper of 2wt% to 5wt%, the silicon of 0.001wt% to 0.05wt%, the cobalt of 0.001wt% to 0.01wt% and the tin of surplus.

6. electronic equipment that uses the high temperature lead-free solder compound, wherein the high temperature lead-free solder compound is comprised of the copper of 2wt% to 5wt%, the silicon of 0.001wt% to 0.05wt%, the cobalt of 0.001wt% to 0.01wt% and the tin of surplus.