JP5291494B2 - High strength high heat resistance copper alloy sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copper alloy sheet in which high strength satisfying the tensile strength of &ge;750 MPa (&ge;220 Hv hardness) and high heat resistance are consistent, and further, the smoothness of an etched face is excellent. <P>SOLUTION: The copper alloy sheet has a composition comprising prescribed quantity of at least one selected from Ni, Fe and Co as well as P, Sn, Zn and Cr, and in which the relation in a mass% ratio between at least one selected from Ni, Fe and Co, and P satisfies 4&le;(Ni+Fe+Co)/P&le;12 and also, 3&le;Ni/(Fe+Co)&le;12 is satisfied, and the balance Cu with inevitable impurities. In the alloy structure of the copper alloy sheet, the number of fine phosphide precipitated grains with a grain size of 1 to 20 nm is &ge;300 pieces/&mu;m<SP>2</SP>, the number of coarse crystallized/precipitated grains with a grain size of &gt;100 nm is &le;0.5 piece/&mu;m<SP>2</SP>, and the Sn content in the phosphide precipitated grains is &ge;0.01 by a mass% ratio according to EDX (Energy Dispersive X-ray) spectrometry:Sn/(Ni+Fe+Co+P+Sn). <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a copper alloy plate suitable as a material for electrical and electronic components, particularly a lead frame for a semiconductor device, for example, a lead frame for a QFP package or a QFN package.

  Conventionally, a copper alloy plate made of a Cu—Ni—Si based copper alloy containing Ni and Si is often used for a lead frame material, particularly a high strength lead frame material. Also, Cu—Ni—Si based copper alloy, for example, Ni: 2.2 to 4.2 mass%, Si: 0.25 to 1.2 mass%, Mg: 0.05 to 0.30 mass% The copper alloy (C70250 alloy) to be used is widely used as a general-purpose alloy because of its excellent strength and heat resistance.

  In recent years, with increasing capacity, miniaturization, and higher functionality of semiconductor devices, lead frames have become finer, and in order to facilitate this miniaturization, the thickness of the copper alloy plate used for the lead frame is increased. Is increasingly being made thinner. Along with this, copper alloy plates used in these lead frames for semiconductor devices are required to have higher strength and higher heat resistance. The purpose of high strength is to secure the handling property that decreases with the thinning of the plate and the strength of the final component, and the heat resistance is to remove the distortion after press punching to form the lead frame. The purpose is to prevent softening by heat treatment and to prevent softening due to thermal history in the assembly process of semiconductor components. These apply not only to lead frames, but also to copper alloy plates used for conductive parts such as connectors, terminals, switches, and relays in other electrical and electronic parts. In addition, in etching, which is a processing method suitable for fine wiring processing, there is an increasing demand as an important factor that no smut is generated and that the smoothness of the etched surface of a copper alloy plate is excellent.

  From the background as described above, the copper alloy plate made of the Cu—Ni—Si based copper alloy (C70250 alloy) is excellent in strength and heat resistance, but is an etching process suitable for fine wiring processing. , Smut is generated, and the etching processing surface is inferior in smoothness.

  Therefore, as a copper alloy plate in which the problem of the smoothness of the etched surface is solved, it is made of a Cu—Ni—Fe—P based copper alloy to which Ni is added based on a Cu—Fe—P based copper alloy. A copper alloy plate in which a Ni—Fe—P compound is precipitated in the alloy structure has been proposed (see, for example, Patent Document 1).

JP 2001-335864 A

  However, in the copper alloy plate made of the Cu—Ni—Fe—P based copper alloy described in Patent Document 1, the tensile strength is about 700 MPa, and it is difficult to obtain high strength beyond that. There is. In addition, there is a problem that by performing finish rolling (final cold rolling) at a high processing rate, even if the strength is forcibly increased, the heat resistance is lowered, which is not suitable for practical use.

  The present invention has been made in view of such a problem. The present invention achieves both high strength and high heat resistance with a tensile strength of 750 MPa or more (hardness Hv220 or more) and is suitable not only for stamping but also for fine wiring processing. It is an object of the present invention to provide a copper alloy plate that is free from smut and is excellent in the smoothness of the etched surface even in the etching process.

In order to solve the above-mentioned problems, the high-strength, high-heat-resistant copper alloy plate according to the present invention is in mass%, Ni: 0.4 to 1.0%, one or more of Fe and Co: 0.03 -0.3%, P: 0.05-0.2%, Sn: 0.1-3%, Zn: 0.005-1.5%, Cr: 0.0005-0.05% The relationship between the mass% ratio of P to one or more of Ni, Fe, and Co satisfies 4 ≦ (Ni + Fe + Co) / P ≦ 12 and 3 ≦ Ni / (Fe + Co) ≦ 12, with the balance being Cu and inevitable The alloy structure of the copper alloy plate, wherein the number of fine P precipitate particles having a particle size of 1 nm or more and 20 nm or less is 300 / μm ² or more and the particle size is 100 nm. the number of coarse dispersoids greater than is 0.5 pieces / [mu] m ² or less, wherein P product precipitated grains In Sn content is mass% ratio by EDX analysis, characterized in that at Sn / (Ni + Fe + Co + P + Sn) at 0.01 or more.

According to the above-described configuration, a predetermined number or more of P-precipitate precipitated particles having a predetermined particle diameter are generated in the alloy structure, containing one or more elements of P, Sn, and a predetermined amount of Ni, Fe, and Co. When the Sn content of the P compound precipitate particles is a predetermined value or more, the pinning force of the P compound precipitate particles that suppress the movement and disappearance of dislocations is increased, and the strength and heat resistance of the copper alloy plate are improved. Further, in the etching process of the copper alloy plate, the P precipitate precipitate particles are suppressed from causing smut generation, so that the smoothness of the etched surface is improved. In addition, by containing a predetermined amount of Zn, plating used for joining the copper alloy plates and thermal delamination of solder are suppressed, and by containing a predetermined amount of Cr, Cr is cast when the copper alloy plate is manufactured. It concentrates at the crystal grain boundary of the lump and improves hot workability. Furthermore, when the number of coarse crystal / precipitate particles having a particle size exceeding 100 nm is 0.5 / μm ² or less, the smoothness and plating properties of the etched surface are improved.

  Here, in this invention, since Sn was detected in the said P compound precipitation particle | grains, Sn content of the said P compound precipitation particle | grains was prescribed | regulated. The case where Sn is contained in a P compound composed of Ni- (one or more of Fe and Co) -P or the case where Sn is concentrated at the P compound and the matrix interface is considered. In the present invention, the Sn content including all these cases is defined.

Moreover, the high-strength, high heat-resistant copper alloy plate according to the present invention further contains at least one of Al and Mn: 0.0005 to 0.05% by mass% in the copper alloy plate. It is characterized by.
According to the above configuration, the amount of S mixed as an inevitable impurity in the copper alloy is reduced by containing one or more of a predetermined amount of Al and Mn, and the hot workability of the copper alloy plate is improved. To do.

  According to the copper alloy plate according to the present invention, strength (tensile strength and hardness) and heat resistance are increased, and not only in stamping, but also in etching which is a processing method suitable for fine wiring processing, There is no generation of smut, and the smoothness and plating properties of the etched surface are excellent. Moreover, according to the copper alloy plate which concerns on this invention, the thermal peeling of plating and a solder does not generate | occur | produce at the time of joining of a copper alloy plate. Furthermore, according to the copper alloy plate according to the present invention, the hot workability is improved during the production of the copper alloy plate. Thereby, the copper alloy plate according to the present invention is not limited to use as a lead frame material, but can be used as a general material for other electric / electronic parts.

<High-strength, high heat-resistant copper alloy plate (hereinafter referred to as copper alloy plate)>
The copper alloy plate according to the present invention is in mass%, Ni: 0.4 to 1.0%, one or more of Fe and Co: 0.03 to 0.3%, P: 0.05 to 0 0.2%, Sn: 0.1-3%, Zn: 0.005-1.5%, Cr: 0.0005-0.05%, and one or more of Ni, Fe and Co The relationship of mass% ratio of P satisfies 4 ≦ (Ni + Fe + Co) / P ≦ 12 and 3 ≦ Ni / (Fe + Co) ≦ 12, the balance is made of Cu and inevitable impurities, and the grain size is 1 nm in the alloy structure. The number of fine P-compound-precipitated particles of 20 nm or less is 300 / μm ² or more, and the number of coarse crystal / precipitate particles having a particle diameter of more than 100 nm is 0.5 / μm ² or less. The Sn content in the precipitated particles is the mass% ratio by EDX analysis: Sn / (Ni + Fe + Co P + Sn) at 0.01 or more.
Below, the chemical component composition in the copper alloy plate, the number and the Sn content of the P compound precipitate particles, and the reasons for limiting the numerical values of the number of coarse crystal / precipitate particles will be described.

(Ni: 0.4-1.0 mass%)
Ni is an element necessary for improving the strength and heat resistance of a copper alloy sheet by precipitating fine P precipitate particles containing Sn in the alloy structure. When the content is less than 0.4% by mass, the fine P-compound precipitated particles containing Sn are insufficient, so that the effect of increasing the strength and increasing the heat resistance can be effectively exhibited by 0.4% by mass or more. Containment is necessary. However, if it is excessively contained in excess of 1.0% by mass, coarse crystal / precipitate particles are generated in the alloy structure, the smoothness of the etched surface of the copper alloy plate is lowered, and hot workability is reduced. Also decreases. Therefore, the Ni content is in the range of 0.4 to 1.0 mass%. Moreover, the preferable range in this range is 0.5-0.9 mass%.

(One or more of Fe and Co: 0.03 to 0.3% by mass)
By containing one or more of Fe and Co, the heat resistance of the copper alloy plate is improved, and it is effective for suppressing softening due to heat history in the lead frame punching and heat history in the semiconductor assembly process. Like Ni, Fe or Co is an element necessary for precipitating fine P precipitate particles containing Sn in the alloy structure and improving the strength and heat resistance of the copper alloy sheet. When the content of one or more of Fe and Co is less than 0.03% by mass, the fine P precipitate particles containing Sn are insufficient, and the P precipitate particles become precipitate particles mainly composed of Ni and P. In addition, since the effects of increasing the strength and increasing the heat resistance cannot be exhibited effectively, it is necessary to contain 0.03% by mass or more. However, if it is excessively contained in excess of 0.3% by mass, coarse crystal / precipitate particles are generated in the alloy structure, the smoothness of the etched surface of the copper alloy plate is lowered, and hot workability is increased. Also decreases. Accordingly, the copper alloy plate has a content of one or more of Fe and Co in the range of 0.03 to 0.3% by mass. Moreover, the preferable range in this range is 0.05-0.2 mass%.

(P: 0.05 to 0.2% by mass)
In addition to deoxidizing action, P combines with one or more of Ni, Fe and Co to form fine P precipitate particles containing Sn in the alloy structure. It is an element necessary for improving heat resistance. If the content is less than 0.05% by mass, the fine P compound precipitate particles containing Sn are insufficient, so that the effect of increasing the strength and increasing the heat resistance can be effectively exhibited to contain 0.05% by mass or more. is necessary. However, if it is excessively contained in excess of 0.2% by mass, coarse crystal / precipitate particles are generated in the alloy structure, and the smoothness of the etched surface of the copper alloy plate is lowered and hot workability is reduced. Also decreases. Therefore, the P content is in the range of 0.05 to 0.2 mass%. Moreover, a preferable range in this range is 0.07 to 0.18 mass%.

(Sn: 0.1 to 3% by mass)
Sn contributes to improving the strength of the copper alloy sheet in a solid solution state. In the present invention, Sn is further analyzed by Sn analysis by EDX analysis on precipitated particles mainly composed of Ni- (one or more of Fe and Co) -P. Is detected. The reason why Sn is detected in the precipitated particle portion is not clear, but it is detected when Sn is contained in the precipitated particles mainly composed of Ni- (one or more of Fe and Co) -P. A mechanism such as a mechanism in which Ni- (one or more of Fe and Co) -P particles are preferentially precipitated and detected in a portion where Sn is concentrated in the matrix is conceivable. In any case, it is conceivable that Sn promotes precipitation of Ni— (one or more of Fe and Co) —P particles. By such a mechanism, it is presumed that the strength and heat resistance of the copper alloy plate of the present invention are further improved as compared with the effect of only Sn solid solution. When the content is less than 0.1% by mass, fine precipitated particles mainly containing Ni- (one or more of Fe and Co) -P and containing Sn are not formed as in the present invention, and high strength is obtained. In order to effectively exhibit the effects of increasing the heat resistance and heat resistance, it is necessary to contain 0.1% by mass or more. However, when the content exceeds 3% by mass, the effect is saturated. On the other hand, a large amount of Sn segregation and coarse crystal / precipitate particles are generated during melting and casting in the production of a copper alloy sheet, Workability also decreases. Moreover, the electroconductivity of a copper alloy plate also falls. Therefore, the Sn content is in the range of 0.1 to 3% by mass. Moreover, the preferable range in this range is 0.2-2.5 mass%.

(Zn: 0.005 to 1.5 mass%)
Zn is an element used for bonding of copper alloy plates to suppress Sn plating and thermal peeling of solder and to improve heat-resistant peeling. In order to exhibit such an effect effectively, it is necessary to contain 0.005 mass% or more. However, when it contains exceeding 1.5 mass% excessively, the wet-spreading property of molten Sn or solder is deteriorated on the contrary. Therefore, the Zn content is in the range of 0.005 to 1.5 mass%. Moreover, a preferable range in this range is 0.01-1.2 mass%.

(Cr: 0.0005 to 0.05 mass%)
Cr is an element necessary for improving the hot workability of an ingot during the production of a copper alloy sheet. It is presumed that Cr is concentrated at the crystal grain boundary of the ingot to improve the strength of the grain boundary at the hot working temperature and contribute to the improvement of hot workability. The copper alloy sheet according to the present invention contains relatively high concentrations of P and Sn in order to achieve both high strength and high heat resistance, so that hot working is relatively difficult and the grain boundary strengthening effect as described above. Cr having an element becomes a necessary element. In order to exhibit such an effect effectively, it is necessary to contain 0.0005 mass% or more. However, if it exceeds 0.05% by mass, not only is the effect saturated, but coarse crystal / precipitate particles are easily generated in the alloy structure, and the smoothness of the etched surface of the copper alloy plate is improved. descend. Therefore, the Cr content is in the range of 0.0005 to 0.05 mass%. Moreover, the preferable range in this range is 0.001-0.03 mass%.

(4 ≦ (Ni + Fe + Co) / P ≦ 12 and 3 ≦ Ni / (Fe + Co) ≦ 12)
When the relationship between the mass% ratio of P to one or more of Ni, Fe and Co and P satisfies 4 ≦ (Ni + Fe + Co) / P ≦ 12 and 3 ≦ Ni / (Fe + Co) ≦ 12, Strength and heat resistance are greatly improved. Further, in order to precipitate the fine P-containing precipitate particles containing Sn according to the present invention as described below, it is essential to satisfy these two formulas. If these two formulas are not satisfied, the object of the present invention It is impossible to achieve both high strength and high heat resistance. Therefore, the relationship between the mass% ratio of P to one or more of Ni, Fe, and Co satisfies 4 ≦ (Ni + Fe + Co) / P ≦ 12 and 3 ≦ Ni / (Fe + Co) ≦ 12. In addition, preferable ranges in this range are 5 ≦ (Ni + Fe + Co) / P ≦ 10 and 4 ≦ Ni / (Fe + Co) ≦ 10.

(Inevitable impurities)
The inevitable impurities referred to in the present invention are elements such as Si, Ti, Zr, Be, V, Nb, Mo, W, and Mg, for example. When these elements are contained, coarse crystal / precipitate particles are easily generated, and at the same time, both high strength and high heat resistance are inhibited. Therefore, it is preferable to make the total content as small as possible 0.5% by mass or less. In addition, elements such as B, C, Na, S, Ca, As, Se, Cd, In, Sb, Pb, Bi, and MM (Misch metal) contained in a small amount in the copper alloy are inevitable impurities. . When these elements are contained, coarse crystal / precipitate particles are likely to be generated and hot workability is reduced, so that the total amount can be suppressed to a minimum of 0.1% by mass or less. preferable.

(P-deposited particles)
The P-precipitate precipitated particles referred to in the present invention are precipitated particles having a particle diameter of 1 nm or more and 20 nm or less when the copper alloy structure is observed with a transmission electron microscope of 100,000 times or more, and the number thereof is 300 / μm. ² or more. These precipitated particles are mainly composed of a P compound composed of Ni- (one or more of Fe and Co) -P, but the Sn content in the precipitated particles is a mass% ratio by EDX analysis. : Sn / (Ni + Fe + Co + P + Sn) is 0.01 or more.

In the present invention, the particle size of the precipitated particles is the maximum diameter of each precipitated particle (the diameter of a circle circumscribing each precipitated particle). Similarly, the number of precipitated particles was determined by measuring the number of precipitated particles (particle size: 1 nm or more, 20 nm or less) in an observation field with a transmission electron microscope of 100,000 times or more, and converting the number as a measured number per 1 μm ² . This is the number referred to in the present invention. At least three arbitrary visual fields are observed and the measurement results are averaged.

  Such fine P precipitate particles containing Sn are newly generated during the production of a copper alloy sheet, for example, during annealing after cold rolling. That is, such fine precipitated particles are compound phases that are finely precipitated from the parent phase by annealing. Therefore, it is not a coarse crystal / precipitate particle that is generated during casting or hot rolling and originally exists in the copper alloy structure. For this reason, such fine precipitate particles cannot be observed unless the copper alloy structure is observed with a transmission electron microscope of 100,000 times or more.

In the present invention, it is defined that the number of such fine P precipitate precipitate particles containing Sn is 300 / μm ² or more. Such fine P-precipitate precipitate particles containing Sn have a pinning force that suppresses the movement and disappearance of dislocations, and are significantly larger than coarse crystal / precipitate particles. Therefore, in the copper alloy of the present invention, as many precipitate particles as possible mainly composed of fine Ni- (one or more of Fe and Co) -P-Sn compounds having a particle size of 20 nm or less exist in the copper alloy structure as much as possible. By doing so, the above-mentioned pinning is increased, and high strength and high heat resistance can be achieved.

  Furthermore, such fine P-precipitate-deposited particles containing Sn having a particle size of 20 nm or less do not become a cause of smut in the etching process, which is a suitable processing method for fine wiring processing, and the etched surface. It does not reduce the smoothness. On the other hand, coarse crystal / precipitate particles not only have a small contribution to high strength and high heat resistance, but also cause smut generation in etching processing and factors that reduce the smoothness of the etched surface. Can also be.

  As described above, the coarse crystal / precipitate particles having a particle diameter of more than 20 nm have a weak pinning force. Therefore, in this invention, the upper limit of the average particle diameter of the fine P compound precipitation particle | grains containing Sn shall be 20 nm. On the other hand, fine precipitate particles having a particle diameter of less than 1 nm are difficult to detect and measure even with a transmission electron microscope of 100,000 times or more, and the pinning is weakened. Therefore, in the present invention, the lower limit of the defined precipitated particles is 1 nm.

If the number of such fine P precipitate precipitate particles containing Sn is less than 300 / μm ² , the number of particles to exhibit the effect is insufficient, and the tensile strength is 750 MPa (hardness Hv220) or higher. It cannot be obtained and the heat resistance is also reduced.

In addition, if the Sn content of the fine P-precipitate precipitate particles containing Sn is less than 0.01 in terms of mass%, a high strength of not less than 750 MPa (hardness Hv220) cannot be obtained, and the heat resistance also decreases. To do. The composition analysis (Sn content) of the precipitated particles is performed by EDX analysis, and the mass% is calculated from the peak intensity of each component (Ni, Fe, Co, P, Sn). Each mass% is calculated by assuming Ni + Fe + Co + P + Sn as 100%, and the mass% ratio of Sn is calculated from this mass% by the formula of Sn / (Ni + Fe + Co + P + Sn). Moreover, at least 5 or more of the deposited particles of 1 nm or more and 20 nm or less in the observation visual field are analyzed, and the measurement results are averaged. Moreover, the typical composition of P compound precipitation particle | grains is the mass% by EDX analysis, Ni: 30-70%, 1 or more types in Fe and Co: 5-60%, P: 5-35%, Sn : It consists of about 1 to 30% of range.

(Coarse crystals / precipitate particles)
In the present invention, the amount of fine P-precipitate precipitated particles containing Sn having a particle size of 1 nm or more and 20 nm or less is specified, but if this specification is satisfied, the object of the present invention is not impaired. It is permissible that coarse crystal / precipitate particles having a crystal grain / precipitate particle diameter exceeding 20 nm are present in an appropriate amount in the copper alloy structure. However, when the copper alloy structure is observed with a scanning electron microscope of 10,000 times or more, the number of crystal / precipitate particles having a particle diameter exceeding 100 nm is 0.5 / μm ² or less. If the number of coarse crystal / precipitate particles having a particle size exceeding 100 nm exceeds 0.5 / μm ^{2, it} may cause smut during etching processing, decrease in smoothness of the etched surface, and plating. It becomes a factor causing problems such as deterioration of the property (generation of protrusions). Moreover, the production | generation of the P compound precipitation particle | grains containing the above-mentioned fine Sn is also inhibited.

  Coarse crystal / precipitate particles having a particle size exceeding 100 nm are produced during casting or hot rolling during the production of a copper alloy sheet. Here, the crystal / precipitate particles refer to crystal particles that separate as a crystal phase in a copper alloy structure, precipitate particles that separate as a solid phase that does not form a clear crystal phase, or a mixture thereof. The coarse crystal / precipitate particles having a particle diameter exceeding 100 nm include P-based (Ni—Fe—P, Ni—Co—P, Ni—P) and Ni—Sn. Things exist.

In the present invention, the particle size of coarse crystal / precipitate particles is the maximum diameter of each crystal / precipitate particle (the diameter of a circle circumscribing each crystal / precipitate particle). Similarly, the number of coarse dispersoids is 10,000 times or more dispersoids number in the observation field of view with a scanning electron microscope (particle size: greater than 100 nm) was measured, 1 [mu] m ² per The number measured in the above is the number referred to in the present invention, and at least three arbitrary visual fields are observed and the measurement results are averaged. Although observation is possible with a transmission electron microscope, the scanning electron microscope is easier and suitable because of its large particle size.

The copper alloy plate according to the present invention can further contain one or more of Al and Mn: 0.0005 to 0.05% by mass%.
(One or more of Al and Mn: 0.0005 to 0.05 mass%)
Al or Mn is an element effective for reducing the amount of S that is mixed as an inevitable impurity in the copper alloy and decreases the hot workability. In order to effectively exhibit such an effect, the content of one or more of Al and Mn needs to be 0.0005% by mass or more. However, if it exceeds 0.05% by mass, the effect is not only saturated, but coarse crystal / precipitate particles are easily generated, and the smoothness of the etched surface of the copper alloy plate is lowered. Therefore, a copper alloy plate makes content of 1 or more types of Al and Mn into the range of 0.0005-0.05 mass%. Moreover, the preferable range in this range is 0.001-0.03 mass%.

<Method for producing copper alloy plate>
Next, the manufacturing method of the said copper alloy plate is demonstrated. In order to make the alloy structure of the copper alloy plate to be manufactured have the above-mentioned specified structure, it is not necessary to change the manufacturing process known per se greatly, and it can be manufactured in the same process as a conventional method. That is, a molten copper alloy adjusted to the above component composition is cast. Then, after chamfering the ingot, it is heated or homogenized and then hot-rolled, and the hot-rolled plate is water-cooled. Then, cold rolling, annealing, and washing are repeated several times, and finish (final) cold rolling is performed to obtain a copper alloy plate having a product plate thickness.

  In addition, it is preferable to perform strain relief annealing after the final cold rolling. With the miniaturization and high integration of semiconductor devices, the demand for quality regarding the flatness of the plate and the reduction of internal stress is increasing, and the strain relief annealing is effective in improving these quality. The strain relief annealing may be performed in a temperature range of about 200 to 500 ° C. and a time range of about 1 to 300 seconds.

Here, in order to control the precipitation form in which the number of P-oxide precipitation particles containing Sn having a particle diameter of 1 nm or more and 20 nm or less is 300 particles / μm ² or more, the following conditions are used in the production. It is effective to perform annealing. In addition, in order to control the Sn content of the P precipitate particles so that the mass% ratio by EDX analysis is 0.01 or more, one or more of Ni, Fe and Co in the copper alloy, P and Sn content It is effective to adjust the amount.

  That is, as described above, the fine and fine Sn-containing P precipitates in the present invention are compound phases that are newly finely precipitated from the parent phase by annealing. In order to precipitate such fine P oxide precipitate particles containing Sn, annealing is performed after cold rolling in the manufacturing process of the copper alloy sheet.

  However, it is difficult to precipitate a large number of such fine P-containing precipitate particles containing Sn by only one annealing. When the annealing temperature is increased, the number of precipitated particles increases as the number of precipitated particles increases. , Leading to coarsening. Therefore, it is preferable to perform the annealing in a plurality of times and to control the annealing temperature per time to 430 ° C. or less, to suppress the growth and coarsening of the precipitated particles, and to control the above fine precipitation form. . The annealing time may be in the range of about 5 minutes to 20 hours.

  Furthermore, when cold rolling is performed between these annealings, lattice defects are increased by cold rolling and precipitate nuclei are formed in the subsequent annealing, so that the above-described fine precipitation form is easily obtained.

Therefore, in consideration of these conditions, in the manufacturing process of the copper alloy plate described above, a process of repeatedly performing cold rolling and annealing twice after hot rolling until finishing (final) cold rolling, This is preferable in that the precipitation form of the fine P precipitate particles containing Sn is easily obtained. Further, by controlling the casting conditions and hot rolling conditions so that the number of coarse crystal / precipitate particles having a particle size exceeding 100 nm is 0.5 particles / μm ² or less, the fine P containing Sn is contained. It is preferable to promote the formation of the oxide precipitate particles.

As casting conditions and hot rolling conditions for controlling the number of coarse crystals / precipitate particles having a particle size exceeding 100 nm to 0.5 / μm ² or less, the cooling rate during casting is increased (coarse crystallization). The cooling rate at the time of solidification for suppressing substances and the cooling rate to 500 ° C. after the solidification for suppressing coarse precipitates are both 0.1 ° C./second or more, preferably 0.5 ° C./second or more. For example, with water cooling, the heating temperature and end temperature of hot rolling are increased (heating temperature: 850 ° C. or higher, end temperature: 650 ° C. or higher), and the cooling rate after hot rolling is also increased (hot rolling). After the completion, the cooling rate up to 300 ° C. is 1 ° C./second or more, preferably 5 ° C./second or more (for example, water cooling) is effective. If the cooling rate during casting is too slow, a large number of coarse crystal / precipitate particles are generated. In addition, when the heating temperature of hot rolling is low, the coarse crystals / precipitate particles generated during casting are not sufficiently dissolved, and the end temperature of hot rolling is lowered, so that the coarse crystals / precipitates are reduced. Many particles are formed. In addition, a large number of coarse crystal / precipitate particles are generated even when the cooling rate after hot rolling is slow.

  In addition, the number measurement and composition analysis of P precipitate particles containing fine Sn and the number measurement of coarse crystal / precipitate particles having a particle size exceeding 100 nm are preferably performed after the final annealing before the final cold rolling. . Although it is possible even after the final cold rolling, there are cases in which observation of P precipitate particles containing Sn with fine dislocations and coarse crystal / precipitate particles having a particle size exceeding 100 nm may be hindered.

Next, examples of the present invention will be described.
As a method for producing a copper alloy plate, a copper alloy having chemical components shown in Table 1 is melted in a high frequency furnace, and then cast into a graphite book mold and a refractory book mold heated to 400 ° C. by tilting. An ingot having a thickness of 70 mm, a width of 200 mm, and a length of 500 mm was obtained. Both molds were water-cooled from 700 to 800 ° C. after the ingot was solidified in the mold. The graphite mold had a sufficient heat capacity and thermal conductivity, and the cooling rate during solidification obtained from the secondary branch spacing of the dendrite arm spacing was 1 ° C./second or more. On the other hand, the refractory mold was heated, and because of its low thermal conductivity, the cooling rate during solidification was less than 0.1 ° C./second. In addition, the copper alloy shown in Table 1 includes elements such as Si, Ti, Zr, Be, V, Nb, Mo, W, and Mg as inevitable impurities in a total amount of 0.01% by mass or less, B, C, Na , S, Ca, As, Se, Cd, In, Sb, Pb, Bi, MM (Misch metal) and the like were included in a total amount of 0.005% by mass or less. Then, a block having a thickness of 70 mm, a width of 80 mm, and a length of 200 mm is cut out from the upper part of each ingot (the part close to the end of casting), the rolled surface is chamfered and heated, and after reaching 900 ° C., 0.5 After holding for ˜1 hour, it was hot-rolled until the thickness reached 16 mm, and water-cooled at a temperature of 700 ° C. or higher. In some cases, the hot rolling conditions (heating temperature, finishing temperature, cooling method) were changed. After chamfering the surface of the rolled sheet to remove the oxide scale, cold rolling and annealing are repeated twice (the number of cold rolling is the same as the number of annealing), and then the final cold rolling is performed to obtain a thickness. A copper alloy plate having a thickness of 0.2 mm was obtained. Table 1 lists the higher annealing temperature as the maximum annealing temperature among the repeated annealing in each example. And after final cold rolling, strain relief annealing was performed.

  With respect to the copper alloy plate thus obtained, in each example, a sample was cut out from the copper alloy plate, and the number of P precipitate particles (hereinafter referred to as fine precipitate particles) containing Sn was observed by microstructure observation and Evaluation of composition analysis (Sn content), tensile test, hardness measurement, conductivity measurement, heat resistance measurement, etching processability (etching property), solder wettability, solder heat release property and hot workability . These results are shown in Tables 2 and 3, respectively. For some examples, the number of coarse crystals / precipitate particles having a particle size exceeding 100 nm (hereinafter referred to as coarse crystals / precipitate particles) was measured, and the Ag plating property was also evaluated. The results are shown in Table 4, respectively.

The observation of the fine precipitated particles was performed by measuring the number of precipitated particles having a particle size of 1 nm or more and 20 nm or less when the copper alloy structure was observed with a transmission electron microscope of 300,000 times by the above-described measurement method. Calculated as μm ² . The composition analysis (Sn content) of the finely precipitated particles was calculated as a mass% ratio by measuring mass% (Ni + Fe + Co + P + Sn = 100%) by EDX analysis (beam diameter: 1 nm).

  The tensile test was performed by preparing a JIS No. 5 test piece cut out parallel to the rolling direction. The hardness test was carried out by applying a load of 4.9 N with a micro Vickers hardness tester. The tensile strength was 750 MPa or more, and the hardness was 220 Hv or more.

  The electrical conductivity was calculated by an average cross-sectional area method by processing a strip-shaped test piece having a width of 10 mm and a length of 300 mm by milling, measuring the electrical resistance with a double bridge resistance measuring device. Conductivity: good at 25% or more.

  For heat resistance, the hardness after heating at 450 ° C. for 1 minute was measured by the above hardness test, and the hardness retention rate (%) = (hardness after heating / hardness before heating) × 100 was evaluated. Hardness retention: good at 90% or more.

The etching processability (etchability) is determined by performing etching using a ferric chloride aqueous solution (specific gravity 1.5) at a liquid temperature of 45 ° C. and a spray pressure of 1.5 kgf / mm ² , and then removing the etched surface (etching). The processed surface was observed with a scanning electron microscope, and the smoothness was evaluated in three stages (A: good, B: rough skin generated, C: large rough skin).

  Solder wettability was evaluated by the ratio of wet area after applying a non-active flux on a strip-shaped test piece, dipping in a solder bath (Sn-40% Pb) maintained at 245 ° C. for 5 seconds (A: whole surface wet) , B: Pinhole generation, C: Less than 95% wetted area).

  For the heat-resistant peelability of the solder, a weakly active flux was applied to a strip-shaped test piece, immersed in a solder bath (Sn-40% Pb) maintained at 245 ° C. for 5 seconds, and then heated in an oven at 150 ° C. for 1000 hours. The test piece was subjected to 180 ° bending back processing to observe whether or not the solder in the processed part was peeled off (A: no peeling, B: slight peeling, C: full peeling).

  The hot workability was evaluated by the appearance of the material after the hot rolling process when producing the plate material of the example (A: good, B: generation of ear cracks, C: large ear cracks).

Coarse crystal / precipitate particles are observed by measuring the number of coarse crystal / precipitate particles having a particle diameter exceeding 100 nm when the copper alloy structure is observed with a scanning electron microscope of 10,000 times by the above-described measurement method. Measured and calculated as pieces / μm ² .

Ag plating is performed using a cyan-based Ag plating solution with a thickness of 1 μm, and the number of protrusions (locally Ag plating thickness is increased to become protrusions) is measured with a 30-fold stereo microscope. The number of pieces / cm ² was calculated and evaluated in three stages. A: Good (less than 0.5 pieces / cm ² ), B: Somewhat bad (0.5 to 5 pieces / cm ² ), C: Bad (5 pieces / cm ² or more).

As shown in Tables 1 to 4, Examples (Nos. 1 to 19) have a copper alloy composition range defined in the claims, and each of them also includes Al or Mn selectively within a predetermined range. . And the casting in the manufacturing method, hot rolling, and annealing are also manufactured within preferable conditions. In addition, when the copper alloy structure was observed with a transmission electron microscope of 300,000 times, the number of fine P precipitate particles (fine precipitate particles) having a particle size of 1 nm or more and 20 nm or less and containing Sn was 300 / μm ² or more, and its Sn content (ratio by mass%) was 0.01 or more. Further, when the copper alloy structure was observed with a scanning electron microscope of 10,000 times, the number of coarse crystal / precipitate particles having a particle diameter exceeding 100 nm was 0.5 / μm ² or less.

  As a result, the copper alloy sheets of the examples (No. 1 to 19) had characteristics of a tensile strength of 750 MPa or more and a hardness of Hv 220 or more, and the conductivity was 25% IACS or more. Furthermore, the heat resistance was 90% or more in terms of hardness retention, and both high strength and high heat resistance were achieved, and the etching property, solder wettability, solder heat release property and hot workability were good. In addition, the copper alloy plate of Example (No. 2) was also good about Ag plating property.

On the other hand, in the comparative example (No. 20), the amount of P is lower than the lower limit, and (Ni + Fe + Co) / P is higher than the upper limit. Therefore, although annealing was performed within preferable conditions, the number of fine precipitated particles was less than the lower limit of 300 / μm ² , and the tensile strength, hardness, and heat resistance (hardness retention) were low.

  In Comparative Example (No. 21), the number of finely precipitated particles satisfies the scope of claims, and the tensile strength, hardness, and heat resistance are good, but the P amount exceeds the upper limit, and (Ni + Fe + Co) / P Is below the lower limit, coarse crystal / precipitate particles were formed, and the etching property, the heat-resistant peelability of the solder and the hot workability were reduced.

In the comparative example (No. 22), the amount of Ni, (Ni + Fe + Co) / P and Ni / (Fe + Co) are below the lower limit. For this reason, the number of fine precipitated particles was below the lower limit of 300 / μm ² , and the tensile strength, hardness, and heat resistance (hardness retention) were low.

  In the comparative example (No. 23), the number of fine precipitated particles satisfies the scope of claims, and the tensile strength, hardness, and heat resistance are good, but the Ni amount exceeds the upper limit, so that it is coarse. Crystalline / precipitate particles were formed, and the etching property was lowered.

In the comparative example (No. 24), the Fe amount is 0.01%, which is below the lower limit, and Ni / (Fe + Co) is higher than the upper limit. For this reason, the number of fine precipitated particles was below the lower limit of 300 / μm ² , and the tensile strength, hardness, and heat resistance (hardness retention) were low.

  In Comparative Example (No. 25), the number of finely precipitated particles satisfies the scope of claims, and the tensile strength and hardness are good, but the Fe amount exceeds the upper limit, and Ni / (Fe + Co) has the lower limit. The composition of fine precipitated particles deviates from the proper range, and the heat resistance (hardness retention rate) is low, and coarse crystals / precipitate particles are generated. Etching, solder wettability / hot working Decreased.

  In Comparative Examples (Nos. 26 to 29), the amounts of Ni, Fe and P satisfy the scope of the present invention, the number of finely precipitated particles also satisfies the scope of the present invention, and the tensile strength and hardness are good. Since (Ni + Fe + Co) / P or / and Ni / (Fe + Co) deviated from the scope of claims, the composition of fine precipitated particles deviated from an appropriate range, and heat resistance (hardness retention) was low.

In the comparative example (No. 30), the amount of Co is lower than the lower limit, and Ni / (Fe + Co) is higher than the upper limit. For this reason, the number of fine precipitated particles was below the lower limit of 300 / μm ² , and the tensile strength, hardness, and heat resistance (hardness retention) were low.

  In Comparative Example (No. 31), the number of finely precipitated particles satisfies the claims, and the tensile strength and hardness are good, but the Co amount exceeds the upper limit, and Ni / (Fe + Co) has the lower limit. The composition of fine precipitated particles is not within the proper range, resulting in low heat resistance (hardness retention) and coarse crystal / precipitate particles. Etching, solder wettability, hot working Decreased.

  In Comparative Example (No. 32), the number of finely precipitated particles satisfies the scope of claims, and the tensile strength and hardness are good, but the total of Fe amount and Co amount exceeds the upper limit, and Ni / ( Fe + Co) is lower than the lower limit, so the composition of fine precipitate particles is out of the proper range, the heat resistance (hardness retention) is low, and coarse crystal / precipitate particles are generated, etching property, solder wetting And hot workability decreased.

  In the comparative example (No. 33), the number of finely precipitated particles satisfied the scope of the claims, but since the Sn amount was below the lower limit, the tensile strength and hardness were insufficient. In addition, as shown in Table 3, the Sn content of the finely precipitated particles was below the lower limit.

  In the comparative example (No. 34), the number of fine precipitated particles satisfies the scope of claims, and the tensile strength and hardness are good, but the Sn amount exceeds the upper limit, so that coarse crystals and precipitates are present. Product particles were generated, and heat resistance (hardness retention) and etching property were lowered, and conductivity and hot workability were also greatly lowered.

  In Comparative Example (No. 35), the number of finely precipitated particles satisfied the scope of claims, and the tensile strength, hardness, and heat resistance (hardness retention) were good, but the Zn content was below the lower limit. As a result, the heat-resistant peelability of the solder decreased.

  In Comparative Example (No. 36), the number of finely precipitated particles satisfies the scope of claims, and the tensile strength, hardness, and heat resistance (hardness retention) are good, but the Zn amount exceeds the upper limit. As a result, solder wettability decreased.

  In Comparative Example (No. 37), the number of finely precipitated particles satisfied the scope of claims, and the tensile strength, hardness, and heat resistance (hardness retention) were good, but the Cr amount was below the lower limit. As a result, hot workability decreased.

  In the comparative example (No. 38), the number of finely precipitated particles satisfies the scope of claims, and the tensile strength, hardness, and heat resistance (hardness retention) are good, but the Cr amount exceeds the upper limit. As a result, coarse crystal / precipitate particles were generated and the etching property was lowered.

In the comparative example (No. 39), the composition of the copper alloy satisfies the claims, but the maximum annealing temperature is too high exceeding the preferable upper limit, and the number of fine precipitated particles is below the lower limit of 300 / μm ² . It was. For this reason, tensile strength, hardness, and heat resistance (hardness retention) were remarkably low.

In the comparative example (No. 40), since the heating temperature / end temperature of hot rolling is low, a large number of coarse crystals / precipitate particles having a particle size exceeding 100 nm are generated, and the etching property and Ag plating property are lowered. Since the number of fine precipitate particles was less than 300 / μm ^{2 due} to the formation of coarse crystal / precipitate particles, the tensile strength and heat resistance were also lowered.

In the comparative example (No. 41), since the cooling method after hot rolling is air cooling, the cooling rate is slow, and a large number of coarse crystal / precipitate particles having a particle diameter exceeding 100 nm are generated. ), The etching property and the Ag plating property were lowered, and the number of fine precipitate particles was less than 300 / μm ^{2 due} to the formation of coarse crystal / precipitate particles, so the tensile strength and heat resistance were also lowered.

Since the comparative example (No. 42) was cast into a heated refractory book mold, the cooling rate during solidification was slow, and a large amount of coarse crystallized material was crystallized. Therefore, the crystallized product does not disappear even by heating at the time of hot rolling, and a large number of coarse crystal / precipitate particles having a particle size exceeding 100 nm are formed, and the etching property and Ag are the same as in the comparative example (No. 40). In addition to a decrease in plating performance, the number of fine precipitate particles was less than 300 / μm ^{2 due} to the formation of coarse crystal / precipitate particles, so the tensile strength and heat resistance also decreased.

Claims (2)

In mass%, Ni: 0.4-1.0%, one or more of Fe and Co: 0.03-0.3%, P: 0.05-0.2%, Sn: 0.1 -3%, Zn: 0.005-1.5%, Cr: 0.0005-0.05%, and the relationship between one or more of Ni, Fe and Co and the mass% ratio of P is 4 ≦ (Ni + Fe + Co) / P ≦ 12 and 3 ≦ Ni / (Fe + Co) ≦ 12, and the balance is a copper alloy plate made of Cu and inevitable impurities,
In the alloy structure of the copper alloy plate, the number of fine P precipitate particles having a particle size of 1 nm or more and 20 nm or less is 300 particles / μm ² or more, and the number of coarse crystal / precipitate particles having a particle size of more than 100 nm is 0.5 / μm ² or less,
A high strength and high heat resistance copper alloy plate, characterized in that the Sn content in the P-compound precipitated particles is 0.01 or more by mass% ratio by SnX (Ni + Fe + Co + P + Sn) by EDX analysis.   2. The high-strength, high-heat-resistant copper according to claim 1, wherein the copper alloy plate further contains, by mass%, one or more of Al and Mn: 0.0005 to 0.05%. Alloy plate.