KR20070082061A - Pb free solder composition, electronic equipment and pcb with the same - Google Patents

Abstract

A Pb-free solder composition which prevents oxidation of molten solder consistently and effectively, maintains conventional Pb-free soldering temperature and wettability, and can improve soldering adhesive property by containing Si or/and Co in a ternary Sn-Cu-Ag solder composition, and an electronic equipment and a PCB using the same are provided. A Pb-free solder composition comprises 0.1 to 2 wt.% of copper, 0.1 to 4.0 wt.% of silver, 0.001 to less than 0.05 wt.% of silicon, and the balance of tin. The Pb-free solder composition further comprises 0.001 to less than 0.01 wt.% of cobalt. As an electronic equipment comprising a plurality of electronic components adhered by a Pb-free solder alloy, the electronic equipment is characterized in that the Pb-free solder alloy comprises 0.1 to 2 wt.% of copper, 0.1 to 4.0 wt.% of silver, 0.001 to less than 0.05 wt.% of silicon, and the balance of tin. As a PCB(printed circuit board) adhered by a Pb-free solder alloy, the PCB is characterized in that the Pb-free solder alloy comprises 0.1 to 2 wt.% of copper, 0.1 to 4.0 wt.% of silver, 0.001 to less than 0.05 wt.% of silicon, and the balance of tin.

Description

Pb free solder composition, electronic equipment and PCB with the same}

1 is a schematic diagram showing the principle of the amount of oxide suppression of the lead-free solder composition according to the present invention.

FIG. 2 is an element analysis result diagram and a result table of an initial state with respect to the schematic diagram of FIG.

FIG. 3 is an element analysis result diagram and a result table after a 3-hour dross experiment for the schematic diagram of FIG. 1. FIG.

FIG. 4 is an Auger Si measurement peak for the schematic diagram of FIG. 1. FIG.

FIG. 5 is a Auger SiO ₂ measurement peak for the schematic diagram of FIG. 1. FIG.

The present invention relates to a lead-free solder composition and an electronic device and a printed circuit board using the same. More specifically, the present invention contains silicon (Si) in a ternary composition made of tin (Sn), copper (Cu), and silver (Ag) without containing lead that is harmful to the human body, thereby generating oxides by the silicon. This is continuously suppressed to improve the work efficiency of soldering, and the addition of a small amount maintains the conventional lead-free soldering temperature and wettability while preventing discoloration, improving wettability, preventing discoloration, and cobalt (Co) silicon. The present invention relates to a lead-free solder composition, and an electronic device and a printed circuit board using the same, which contain a small amount together to prevent oxide generation, copper erosion, and bonding failure load.

In the conventional case, lead-containing alloys have been used for a long time, and tin-lead-based flexible solders have been used as bonding materials in component mounting of printed circuit boards for a long time. More specifically, soldering is a bonding technique using soldering, and in particular, it is used as a bonding material for mounting small electronic components such as semiconductor chips and resistance chips on a printed circuit board (PCP). As a joining technique using such soldering, it is used as a bonding material for mounting small electronic components such as semiconductor chips and resistor chips, in particular on printed circuit boards.

Joining technology using such a solder is required to be more advanced because of the high density of component mounting in accordance with the recent miniaturization and high functionality of electronic products. On the other hand, as a soldering material, binary process alloys composed of tin (Sn) and lead (Pb) have been mainly used. However, when this is disposed of, lead is leaked, which causes environmental pollution. Reached. This is because lead has a fatal adverse effect on the human body following environmental pollution.

Therefore, in recent years, various environmentally friendly lead-free solder compositions have been developed and attempted by regulating or excluding lead in the manufacture of solder alloys. However, the lead-free solder composition according to the prior art has a higher melting point and lower wettability as compared to the flexible solder, and also causes severe oxidation of the molten solder during soldering, resulting in poor soldering workability, and improved quality and reliability of PCB Assey by soldering. It has a problem of deterioration.

In addition, the lead-free solder according to the prior art is used in accordance with the improvement of the soldering process, such as replacement of the reflow oven without the development of near the melting point of 183 ℃ of the conventional solder (Sn37Pb) while satisfying the soldering bonding properties such as wettability. This is because only a very limited number of low melting point metals such as Cu, Ag, Zn, Bi, In, etc. are targeted as the melting point drop addition element.

In addition, the lead-free solder according to the prior art does not satisfy the melting point of 183 ° C of the conventional solder (Sn37Pb) while satisfying the soldering bonding properties such as wettability, corrosion resistance. And most lead-free solders have a small melting point by adding a small amount of low melting point metals such as Cu, Ag, Zn, Bi, In to Sn, but the development of lead-free solders with low melting point (low melting point) is no longer possible. No progress has been made and the limit has been reached.

Therefore, the Ag system of SnAgCu and the non-Ag system alloy of SnCu of melting | fusing point 220 degreeC-230 degreeC are the mainstream now. As described above, in terms of lowering the melting point of the solder, improvement has reached a limit, and development is mainly focused on improving soldering characteristics, improving workability, and improving quality and reliability.

In addition, lead-free solder has a higher melting point, more expensive dross due to the use of expensive raw materials and soldering oxidation, resulting in higher production costs, and increased oxides in the solder solder fillet of PCB Assey. ), The main cause of the deterioration of the quality and reliability of soldering assembly.

In order to solve the above problems, as described in KR 10-0327767, JP 3622788, and JP 3296289, a solder alloy in which an anti-oxidation element such as P, Ni, Ge, and Ga is added to SnAgCu and SnCu-based mother alloy solders has been developed. It is. However, in the case of Ge, Ga, and Ni, which are additional elements, the melting point is increased, and when exposed to thermal processing and thermal fatigue due to hardening, there is a concern that the reliability may be degraded, such as cracks in the solder portion, and thus it is used in a limited manner. .

In particular, when P is added in a large amount, the adverse effect of bridging the soldering portion due to hardening of the solder alloy occurs. In addition, P melts on the soldering surface to prevent oxidation of the molten solder. However, P has a high volatility to temporarily prevent generation of oxides at soldering temperatures around 260 ° C. However, wave soldering (Wave) In the case of soldering and dip soldering, hundreds of kilograms of solder are filled in the molten metal, followed by continuous use for several months by replenishing only a small amount of consumption. It only shows a short dross prevention effect and continuous oxidation has an unexpected problem.

Accordingly, the present invention is to solve the above-mentioned problems, the object of the present invention has a mechanical property and workability comparable to Sn-Pb and Sn-Ag-Cu solder, tin (Sn), copper ( By incorporating silicon (Si) or silicon and cobalt (Co) in a ternary composition composed of Cu) and silver (Ag), the oxidation of the molten solder is prevented continuously and effectively, and despite the addition of an extremely small amount of elements In order to provide a lead-free solder composition and an electronic device and a printed circuit board using the same, the lead-free soldering temperature and wettability can be improved while soldering adhesion can be improved, such as preventing discoloration after soldering and copper pad erosion of a printed circuit board. .

The lead-free solder composition according to the present invention provides a lead-free solder composition containing 0.1 to 4.0% by weight of silver, 0.1 to 2% by weight of copper, less than 0.001 to 0.05% by weight of silicon and tin, and electronic devices and printed circuit boards using the same. do. In addition, the present invention provides a lead-free solder composition that can be expected to further include the synergistic effect of the cobalt content of silicon and cobalt further comprises 0.001 ~ less than 0.01% by weight.

1 is a schematic diagram showing the principle of suppressing the amount of oxide generation of the lead-free solder composition according to the present invention.

As shown in the figure, in the case of wave soldering using a solder alloy containing P and Si elements to suppress oxide generation in the SnAgCu master alloy, first, a part of the amount of the added P and Si elements is After being consumed in the deoxidation of the molten solder master alloy, it is dissolved in some molten solder master alloy, but P and Si are hardly dissolved in the molten Sn, and most of the added P and Si elements float on the surface due to the specific gravity difference. Done. In addition, the phosphate and silicon oxide film blocks oxygen and molten solder in the atmosphere to suppress oxide generation of the lead-free solder.

However, in the case of P, a portion of the surface floating on the surface forms an oxide film, but a large portion of the surface is volatilized to the atmosphere, thereby degrading the continuous suppression of oxide generation on the surface of the molten solder. On the other hand, Si does not volatilize to the atmosphere and continuously forms silicon oxide on the surface of the molten solder, thereby suppressing the oxide generation effect. Experimental data on this can be seen through FIGS. 2 and 3.

지점별 성분 데이터를 통해 확인할 수 있다. FIG. 2 is a result of Auger element analysis of a solder alloy cross section by melting and casting a predetermined ingot by melting and casting as actual measurement data of the schematic diagram of FIG. Figure 3 is an Auger element analysis result when the Ingot produced by the same method for 3 hours Dross experiment (oxidation experiment) at 260 ℃. As shown in Fig. 2, in the initial state, phosphorus is floated on the surface of the ingot, and is mostly concentrated at 1.86% by mass at the top, and Si is distributed at the lower part of P.

This can be confirmed by point-specific component data.

지점에서도 P 보다는 Si이 더 잔존하고 있음을 알 수 있다. 또한, Auger의 Peak치를 보면, 상부에는 SiO₂로 간주되는 실리콘 산화물이 형성되어 있는 반면, 하부 방향 2, 3

지점에는 도4에서 알 수 있듯이 SiO₂ Peak치가 아닌 Si Peak가 나타나고 있다. As shown in Fig. 3, in the case of the dross experiment at 260 ° C. for 3 hours, P is 0.06% by mass and Si is 0.08% by mass, and Si remains relatively higher than P.

It can be seen that Si remains more than P at the point. In addition, the peak value of Auger shows that silicon oxide, which is regarded as SiO ₂ , is formed on the upper side, while the lower directions 2 and 3

At the point, as can be seen in Figure 4 SiO ₂ Si peak, not peak value, appears.

From the above results, after P and Si were floated in the order of P. Si due to the specific gravity difference from the molten solder on the surface of the molten solder in the initial stage of melting, P was volatilized to a large extent and only a portion of the oxide film was formed by continuous contact with air. On the other hand, in the case of Si, most of the addition amount forms a silicon oxide film such as SiO ₂ to suppress oxidation of the molten solder.

Looking at the properties and uses of the composition of the lead-free solder composition according to the invention as follows.

Sn (tin) is used as the base metal as an essential component of lead-free solders.

Cu (copper) lowers the melting point slightly, improves the bonding strength of the bonded body, when added in less than 0.1% by weight, the effect is small and the addition of more than 2% by weight, the melting point is increased, 0.1 to 2% Addition in the% range is preferred.

Ag (silver) lowers the melting point of the alloy, has no self-toxicity, improves the spreadability of the bonded base material, and improves the thermal fatigue characteristics. And when added in less than 0.1% by weight, the above-mentioned effect is less, when the addition of more than 4% by weight because the melting point is increased, the addition of 0.1 to 4% by weight is preferred.

Si (silicon) is a main additive element of the present invention, floating and non-volatile, it is added to the solder master alloy of Sn-Ag-Cu in a small amount to suppress the generation of oxides, unlike the phosphorus (P) even after a long time The effect lasts, and it is not only excellent in preventing discoloration of the soldered part after soldering, but also improves anti-corrosion effect.

Co (cobalt) is not flotation, but by adding with Si, a small amount of addition suppresses the formation of oxide during soldering, and further improves soldering properties and workability such as discoloration and erosion prevention.

Hereinafter, the functions and effects of the composition of the composition of the lead-free solder composition and the electronic device and the printed circuit board using the same according to the composition of the composition through the experimental data will be described in detail.

The lead-free solder composition according to the present invention comprises tin (Sn), copper (Cu), silver (Ag), silicon (Si), and cobalt (Co).

Hereinafter, the antioxidant effect according to the composition range of the silicon and cobalt through the graph 1 will be described in detail.

The following graph 1 is experimental data of the amount of oxidation generated, by selectively or simultaneously dissolving silicon and cobalt in the master alloy of tin-copper-silver-phosphorus and tin-copper-silver to form a soldering composition, The soldering composition was heated to 260 ° C. using a hotplate in a 160 mm diameter SUS crucible. Then, the resultant was stirred for 1 hour, 2 hours, and 3 hours at a rotational speed of 60 rpm using a stirrer having a diameter of 140 mm, and the amount of oxidation was measured by measuring the weight of oxides by time.

Graph 1.

As shown in Graph 1., Sn3Ag0.5Cu containing 0.5% by weight of Cu, 3% by weight of Ag and Sn as remainder was 478 (g) after 1 hour, 540 (g) after 2 hours, and 3 After the passage of time, a total of 1,582 (g) was generated in 564 (g). In comparison, Sn3Ag0.5Cu0.005P containing 0.5% by weight of Cu, 3% by weight of Ag, 0.005% by weight of P and Sn as a balance has 295 (g) after 1 hour and 325 (g) after 2 hours. ), 3 hours later, a total of 1,010 (g) occurred at 390 (g). This is because P plays a role of reducing the amount of oxidation.

However, when the Sn3Ag0.5Cu contains 0.005% by weight of Si, the amount of oxide generated is 270 (g) after 1 hour, 302 (g) after 2 hours, and 345 (g) after 3 hours. ) Was generated, and the amount of oxidation generated was reduced compared to Sn3Ag0.5Cu0.005P. From the above results, when 0.005% by weight of P was added, the occurrence of Dross increased rapidly in the 3 hour period, while 0.005% by weight of Si showed a similar oxidation rate as that of Si, which was more than that of P. It can be said to have a continuous antioxidant effect.

And, if it contains 0.05% by weight of Si, it can be seen that the amount of oxidation generated is further reduced.

In addition, in the case of including 0.005% by weight of Co in Sn3Ag0.5Cu0.005Si, the amount of oxide generated was 215 (g) after 1 hour, 240 (g) after 2 hours, and 264 (g) after 3 hours, total 719 (g) was generated, and the amount of oxidation generated was reduced compared to the Sn3Ag0.5Cu0.005P and Sn3Ag0.5Cu0.005Si.

In addition, in the case of including 0.005% by weight of Co in Sn0.3Ag0.7Cu0.005Si, it can be confirmed that the amount of oxides is reduced by adding a small amount of Si and Co as compared to the comparative material.

Therefore, when a small amount of Si is added to the Sn-Ag-Cu master alloy, it can be seen that the amount of oxidation is continuously prevented compared to the conventional P-added soldering composition, and Si and Co are simultaneously added in small amounts. In this case, it can be confirmed that it is prevented more continuously and effectively.

Hereinafter, the wettability according to the component composition range of silicon and cobalt will be described in detail through Graph 2.

The following graph 2 is experimental data on the wettability. In order to measure the wettability time of the soldering composition, the wettability time after holding for 5 seconds was measured by melting the solder at 260 ° C and immersion at 1mm using a MalCom SP2 Wetting Tester. .

Graph 2.

As shown in Graph 2., the wet time of Sn3Ag0.5Cu containing 0.5% by weight of Cu, 3% by weight of Ag and Sn as remainder was 0.48 sec, compared to 0.5% by weight of Cu, 3% by weight of Ag, P 0.005 Wetting time of Sn3Ag0.5Cu0.005P containing the weight% and the remainder of Sn is 0.51 sec.

In addition, when the Sn3Ag0.5Cu contains 0.005% by weight of Si, the wetting time is 0.44 sec, and when the Si0.05% by weight is included, the wetting time is 0.49 sec, which is reduced compared to the Sn3Ag0.5Cu0.005P wetting time. Wetting time was found to be higher than Sn3Ag0.5Cu.

In addition, when 0.01 wt% of Co is included in Sn3Ag0.5Cu0.05Si, the wetting time is 0.50 sec, and when we include 0.005 wt% of Co in Sn0.3Ag0.7Cu0.005Si, the wetting time is 1.10sec.

Therefore, when 0.005% by weight of Si is added to the Sn-Ag-Cu master alloy, the wettability is slightly improved, but when the weight is 0.05% by weight or more, the wettability may be confirmed. The wettability is slightly improved by removing oxygen in the molten master alloy solder (SnAgCu) by adding a very small amount of Si to 0.005% by weight, but when added by 0.05% by weight or more, it is melted by excess Si with an increase in melting point. It is considered that the wettability of solder is poor. In addition, when Si and Co are added in small amounts simultaneously, the wettability is further improved, but when Co is added in a large amount, for example, 0.01 wt% or more, the wettability is lowered.

Hereinafter, the copper erosion according to the composition range of the silicon and cobalt through the graph 3 will be described in detail.

The following graph 3 is experimental data on copper erosion amount, in order to measure copper erosion amount, the solder is melted and maintained at 260 ° C., and copper wire having a diameter of 0.8 mm is immersed in a molten solder at a depth of 30 mm for 60 seconds, and then The copper wire was taken out and the weight before and after dipping was measured to obtain the erosion rate (%), and the average value of five samples was calculated.

Graph 3.

As shown in Graph 3, the copper erosion amount of Sn3Ag0.5Cu containing 0.5% by weight of Cu, 3% by weight of Ag, and Sn was 58.3%, compared with 0.5% by weight of Cu, 3% by weight of Ag, and 0.005% by weight of P. The copper erosion amount of Sn3Ag0.5Cu0.005P including% and Sn as remainder is 58.1%.

And, if the Sn3Ag0.5Cu containing 0.005% by weight of Si, copper erosion amount is 54.3%, when containing 0.05% by weight of Si, copper erosion amount is 41.7%, Sn3Ag0.5Cu and Sn3Ag0.5Cu0.005P erosion amount It can be confirmed that the reduction compared to the.

In addition, in the case of including 0.01 wt% of Co in Sn3Ag0.5Cu0.005Si, it can be seen that the concentricity is significantly reduced to 21.1%.

Therefore, when a small amount of Si is added to the Sn-Ag-Cu master alloy, the copper erosion amount can be confirmed to be reduced, and when Si and Co are added in small amounts at the same time, the amount of copper erosion is significantly reduced.

Hereinafter, referring to Table 1, the amount of oxide generation, melting point, discoloration, wetting time, copper erosion rate, and bonding strength according to the composition range of silicon and cobalt are described in detail, and the silicon included in the Sn-Ag-Cu mother alloy through this. And the optimum content of cobalt.

Table 1 is a comprehensive experimental data for each composition range of silicon and cobalt including the above-described graphs 1,2 and 3, and adding test data of melting point, discoloration and bonding strength.

Table 1.

First, as shown in the melting point data of Table 1, the melting point of Sn3Ag0.5Cu containing 3% by weight of Ag, 0.5% by weight of Cu and Sn as remainder is 220 ° C, and 3% by weight of Ag and 0.5% by weight of Cu. Melting point of Sn3Ag0.5Cu0.005P containing%, P 0.005 weight%, and Sn remainder is 221 degreeC. The melting point is 220 ° C. when the Sn 3 Ag 0.5Cu is included in 0.005% by weight of Si, and when the Sn 3 Ag 0.5Cu is contained 0.1% by weight of Si, the melting point is slightly increased to 224 ° C.

In addition, the melting point slightly increased to 223 ° C. when 0.01 wt% of Co was included in Sn 3 Ag 0.5 Cu 0.05 Si. From the above results, when a small amount of Si having a high melting point of 1400 ° C. or higher is added to the low melting point Sn alloy in the state of metal alloy state, the melting point increases rapidly, but the melting point rise is insignificant compared to the amount of Si added. This is probably due to the surface of the molten solder.

Next, in order to measure the discoloration of the alloy composition, the color change data of Table 1 was made by depositing an oxygen-free copper (99.99%) of 25X31X0.3mm at 260 ° C for 3 seconds to make a specimen, and then heating the specimen at 250 ° C for 10 minutes. The degree of discoloration was measured using a chromatic aberration meter of the Minolta CM3700B model.

As shown in Table 1, the discoloration degree of Sn3Ag0.5Cu containing 3% by weight of Ag, 0.5% by weight of Cu and Sn as remainder is 16.47, compared with 0.5% by weight of Cu, 3% by weight of Ag, and 0.005% by weight of P. And Sn3Ag0.5Cu0.005P including Sn as a remainder is 19.31.

And, when the Sn3Ag0.5Cu containing 0.005% by weight of Si, discoloration is 15.66, when including 0.05% by weight of Si, the discoloration is significantly reduced to 6.6, Sn3Ag0.5Cu and Sn3Ag0.5Cu0.005P It can be seen that the reduction compared to the degree of discoloration.

In addition, when the amount of Sn3Ag0.5Cu0.005Si contained 0.005% by weight of Co, the degree of discoloration is 3.46, when including 0.01% by weight of Co, it can be seen that the degree of discoloration is significantly reduced to 3.02.

Therefore, when a small amount of Si is added to the Sn-Ag-Cu master alloy, it is confirmed that the discoloration degree is reduced. When Si and Co are added in small amounts at the same time, the discoloration degree is significantly reduced.

Next, the bond breaking load (kgf) data of Table 1 was measured by vertically inserting a wire of 2 mm diameter plated with tin-bismuth into the hole of the PCB board to measure the bond breaking load, and then wave-soldered a specimen to make a tensile tester. The bond breaking load (kgf) was measured using

As shown in Table 1, the bonding load of Sn3Ag0.5Cu containing 0.5% by weight of Cu, 3% by weight of Ag and Sn as a balance is 84kgf, compared with 0.5% by weight of Cu, 3% by weight of Ag and 0.005% by weight of P. The junction break load of Sn3Ag0.5Cu0.005P containing% and Sn as remainder is 89 kgf.

And, when including 0.005% by weight of Si in the Sn3Ag0.5Cu, the bond breaking load is 95kgf, when including 0.05% by weight of Si, significantly improved to 105kgf, the Sn3Ag0.5Cu and Sn3Ag0.5Cu0.005P It can be confirmed that it is improved compared to the junction breaking load of.

In addition, when including 0.005% by weight of Co in Sn3Ag0.5Cu0.005Si, the bonding breakage load was 96kgf, and when including 0.01% by weight of Co, it can be seen that the bonding breakdown load was significantly improved to 112kgf.

Therefore, when a small amount of Si is added to the Sn-Ag-Cu master alloy, it can be confirmed that the bonding fracture load is improved. When Si and Co are added in small amounts at the same time, the bonding fracture steel is significantly improved.

As described above, the lead-free solder composition according to the present invention maintains the conventional lead-free soldering temperature and wettability by adding a small amount of Si to the Sn-Ag-Cu master alloy, the amount of oxides is continuously reduced, and copper erosion This decreases, the discoloration decreases, and the bond breaking strength increases. In addition, when a small amount of Co is added to the Sn-Ag-Cu master alloy containing a small amount of Si, the amount of oxides is continuously reduced, copper erosion is reduced, and discoloration is reduced, compared with Si alone. As a result, the junction break load increases.

However, in the case of containing a large amount of Si, that is, containing 0.05% by weight or more, the melting point is slightly increased, and considering the inferior wettability to the joined object, the optimum content of Si is less than 0.001 to 0.05% by weight. to be.

In addition, when Co is contained in a large amount, that is, when it is contained in 0.01 weight% or more, wettability is inferior. In addition, with a small amount of 0.05% by weight of Si, even when the addition of a very small amount shows excellent effects, the optimum content of Co is 0.001 to less than 0.01% by weight.

In addition, Cu (copper) in the Sn-Ag-Cu master alloy slightly lowers the melting point, improves the bonding strength of the conjugate, and when added below 0.1% by weight, the effect is small and added in excess of 2% by weight. In this case, the melting point is increased, so the optimum content of copper is 0.1 to 2% by weight, and Ag (silver) lowers the melting point of the alloy, has no self-toxicity, improves the spreadability of the bonded base material, and improves thermal fatigue characteristics. When it is improved and added at less than 0.1% by weight, the above-mentioned effect is small and the addition of 4% by weight or more increases the melting point, so the optimum content of silver is 0.1 to 4.0% by weight. Sn (tin) is used as the base metal as an essential component of lead-free solders.

In addition, the lead-free solder composition according to the present invention can be used in the form of Cream, Bar, Wire, it is implemented by an electronic device including a plurality of electronic components are fixed by the lead-free solder alloy. The electronic device is applicable to various products such as a computer, a digital video camcorder, a digital television, a digital camera, a mobile communication terminal, and the like.

In addition, the present invention is a printed circuit board is fixed by a lead-free solder alloy, the lead-free solder alloy is 0.1 to 2% by weight, 0.1 to 4.0% by weight of silver, less than 0.001 to 0.05% by weight of silicon, and tin remaining The printed circuit board is implemented. In addition, the lead-free solder alloy is further comprised of less than 0.001 ~ 0.01 wt% cobalt.

The present invention described above is not limited to the above-described embodiments, and various permutations, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be obvious to him.

As described above, according to the present invention, it has a mechanical property and workability comparable to Sn-Pb and Sn-Ag-Cu, and is a ternary bath composed of tin (Sn), copper (Cu), and silver (Ag). By incorporating silicon (Si) or silicon and cobalt (Co) into the material, the oxidation of the molten solder is prevented continuously and effectively, and the conventional lead-free soldering temperature and wettability are maintained despite the addition of very small amounts of elements. At the same time, there is an effect of providing a lead-free solder composition and an electronic device and a printed circuit board using the same, which are capable of improving solderability such as discoloration prevention and wettability after soldering and copper pad erosion prevention of a printed circuit board.

Claims (7)

0.1-2 weight percent copper, 0.1-4.0 weight percent silver, 0.001-0.05 weight percent silicon, and tin Lead free solder composition. The method of claim 1, Cobalt further comprises 0.001 to less than 0.01% by weight Lead free solder composition. An electronic device comprising a plurality of electronic components fixed by a lead-free solder alloy, The lead-free solder alloy includes 0.1 to 2 wt% copper, 0.1 to 4.0 wt% silver, 0.001 to less than 0.05 wt% silicon, and tin Electronics. The method of claim 3, The lead-free solder alloy is Cobalt further comprises 0.001 to less than 0.01% by weight Electronics. The method of claim 3, The electronic device is one of a computer, a digital video camcorder, a digital television, a digital camera, and a mobile communication terminal. Electronics. A printed circuit board fixed by a lead-free solder alloy, The lead-free solder alloy comprises 0.1 to 2% by weight of copper, 0.1 to 4.0% by weight of silver, 0.001 to less than 0.05% by weight of silicon, and tin. Printed circuit board. The method of claim 6, The lead-free solder alloy is Cobalt further comprises 0.001 to less than 0.01% by weight Printed circuit board.

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