JP2012167310A - Copper alloy for electric and electronic parts and copper alloy material with tin-plating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper alloy for electric and electronic parts having high electric conductivity and strength and excellent in a stress-relaxing characteristic and bending workability and excellent in a thermal peeling resistance of the tin-plating.SOLUTION: The copper alloy is composed, by mass%, of 0.01-0.2% Fe, 0.02-0.15% P, 0.05-0.2% Mg, 0.001-0.2% Sn and 0.05-1.0% Zn and the balance Cu with inevitable impurities, and further, S is ≤0.005 mass%, and contents of Fe, Mg and P satisfy the following formulas (1) and (2): (1) 2.5≤([Fe]+[Mg])/[P]≤8.0; and (2) [Mg]/[Fe]≥0.85 [Fe], wherein [Mg] and [P] represent respectively contents of Fe, Mg and P.

Description

  The present invention relates to a copper alloy used as a material for electric / electronic parts, and a copper alloy material with Sn plating using the copper alloy as a base material.

Copper alloys are excellent in strength, conductivity, and thermal conductivity, so they are used in home appliance parts, semiconductor parts such as lead frames for semiconductor devices, electrical / electronic parts materials such as printed wiring boards, switch parts, bus bars, and terminals. -Used in various applications such as mechanical parts such as connectors and industrial equipment.
In addition to strength, electrical conductivity, and thermal conductivity, various properties are required for the copper alloy used in these various applications depending on the application. For example, a bus bar having a contact structure shown in FIG. 1 is known as a bus bar of an in-vehicle junction box (hereinafter abbreviated as “JB”). In this bus bar 1, a female terminal portion 3 having press contact portions 2a and 2b is known. In order to maintain electrical contact with the male terminals 4 such as relays and fuses, the lower portions 5 of the pressure contact portions 2a and 2b of the female terminal portion 3 where stress is concentrated have characteristics such as strength and stress relaxation characteristics. It is required to be excellent. In particular, the stress relaxation characteristic is an important characteristic for maintaining good electrical contact. Further, the plate thickness of the bus bar 1 is usually as thick as 0.64 to 0.8 mm and is difficult to bend as compared to a thin plate. Therefore, bending workability that can withstand various kinds of processing is also an important characteristic.

In addition, due to the recent trend toward lower cost, smaller size, and lighter weight for in-vehicle electrical components, in-vehicle JB busbar materials have a much higher electrical conductivity in addition to the mechanical properties that have been conventionally demanded. Specifically, it is desired to be 60% IACS or more [IACS: International Annealed Copper Standard].
Furthermore, conventionally, the bus bar is used in a state where Sn plating is applied in order to improve the corrosion resistance. Here, as described above, in order to adapt to the recent demands for miniaturization and weight reduction in JB, the number of types in which a semiconductor is directly mounted on a bus bar is increasing, and not only corrosion resistance but also heat resistance of plating after heating, etc. The characteristics of are also becoming important.

  Therefore, various copper alloys have been proposed to cope with these problems. For example, in Patent Document 1, Fe: 0.15 to 0.7% in mass%, P: 0 as a copper alloy suitable for current-carrying parts such as bus bars, connector terminals for automobiles, and terminals for electric / electronic parts. 0.04 to 0.5%, Mg: 0.01 to 0.5%, Sn: 0.5% or less as required, Fe / P ratio, Mg / P ratio and Fe + Mg content within predetermined ranges A regulated copper alloy is disclosed. In Patent Document 2, as a copper alloy used for bus bars, terminals, and other electric / electronic components, Fe: 0.01 to 3.0%, P: 0.01 to 0.4%, Mg: 0.1 to 0.1% A copper alloy containing 1.0% Zn as necessary, 0.005 to 3.0% Zn, 0.01 to 5.0% is disclosed. Similarly, in Patent Document 3, Fe: 0.02 to 0.5%, P: 0.01 to 0.1%, Mg: 0.1 to 1.0%, Sn: 0.1 to 1.0 %, A copper alloy containing Zn: 0.3-2.0% is disclosed.

JP 2007-291518 A (Claims 1 and 3) JP 2007-177274 A (Claims 1, 4 and 5) Japanese Patent Laid-Open No. 03-97816 (Claims)

  In Patent Document 1, it is said that a copper alloy having a high level of electrical conductivity, strength, bending workability and press punchability is obtained, but stress relaxation characteristics and plating heat-resistant peelability after high-temperature and long-time heating are obtained. No consideration has been made. In Patent Document 2, it is said that high strength, high electrical conductivity, and excellent bending workability have been obtained, but no examination has been made on stress relaxation characteristics and plating heat resistance peelability after high-temperature and long-time heating. In Patent Document 3, it is said that a copper alloy excellent in strength, stress relaxation characteristics, and conductivity was obtained. However, in the examples, whether the test temperature is low and the current required level is reached for the stress relaxation characteristics. It is doubtful. Further, bending workability has not been studied.

  The present invention has been made in view of the above-mentioned problems of the prior art, has high conductivity and strength, is excellent in stress relaxation characteristics and bending workability, and further after high-temperature and long-time heating when Sn plating is performed. An object of the present invention is to provide a copper alloy for electric and electronic parts which is excellent in heat peelability.

  Therefore, the present inventors have formed Fe—P precipitates and Mg—P precipitates effective for improving the strength and conductivity of Cu—Fe—Mg—P (—Sn—Zn) based copper alloys. The content of Fe, Mg, and P necessary for the study was intensively studied. As a result, the contents of Fe, Mg, P, Sn, and Zn as alloy components are within a specific range, the content of S as an inevitable impurity is suppressed, and the contents of Fe, Mg, and P are further reduced. When satisfy | filling a specific relational expression, it discovered that the said copper alloy had high intensity | strength and electrical conductivity, and also was excellent in the stress relaxation characteristic, bending workability, and Sn plating heat-resistant peeling after high-temperature long-time heating.

That is, the copper alloy for electrical / electronic parts according to the present invention (Claim 1) has Fe: 0.01 to 0.2% by mass, P: 0.02 to 0.15% by mass, Mg: 0.05 to 0.2% by mass, Sn: 0.001 to 0.2% by mass, and Zn: 0.05 to 1.0% by mass, with the balance being Cu and inevitable impurities, S: 0.005% by mass The Fe, Mg and P contents satisfy the following formulas (1) and (2).
2.5 ≦ ([Fe] + [Mg]) / [P] ≦ 8.0 (1)
[Mg] / [Fe] ≧ 0.85 (2)
Here, [Fe], [Mg], and [P] represent the contents of Fe, Mg, and P, respectively.

  The above-mentioned copper alloy for electric / electronic parts is 0 in total in any one or two of Al: 0.001 to 0.030 mass% and Si: 0.001 to 0.030 mass% as necessary. 0.001 to 0.050% by mass or / and (2) one or more of Mn, Ni, Co, and Cr are included in a total amount of 0.0005 to 0.05% by mass.

A copper alloy material with Sn plating according to the present invention (Claim 7) is a copper alloy base material made of the copper alloy for electric / electronic parts and a thickness of 1.0 μm or less formed on the surface of the copper alloy base material. A Cu-Sn alloy layer, and a Sn or Sn alloy layer having a thickness of 0.3 to 1.0 [mu] m formed on the surface of the Cu-Sn alloy layer.
The copper alloy material with Sn plating according to the present invention (Claim 8) is a copper alloy base material made of a copper alloy for electric / electronic parts and a thickness of 1.0 μm formed on the surface of the copper alloy base material. The following Cu-Sn alloy layer and a Sn or Sn alloy layer having a thickness of 0.3 to 1.0 [mu] m formed on the surface of the Cu-Sn alloy layer, the Cu-Sn alloy layer and the Sn or Sn alloy The layer is formed by reflowing an Sn or Sn alloy plating layer formed on the surface of the copper alloy base material.

The copper alloy for electric / electronic parts according to the present invention has high conductivity and strength, is excellent in stress relaxation characteristics and bending workability, and further, Sn or Sn alloy plated copper alloy obtained by performing Sn or Sn alloy plating on this copper alloy The material is excellent in the heat-resistant peelability of the Sn or Sn alloy layer after being heated for a long time at a high temperature. Specifically, the copper alloy according to the present invention has a conductivity of 60% IACS or more, a proof stress of 400 N / mm ² or more in both the parallel direction and the perpendicular direction to the rolling direction, a Vickers hardness of 130 Hv or more, and the rolling direction. The stress relaxation rate after heating at 180 ° C. for 24 hours is 30% or less in both the parallel and perpendicular directions, and the bending axis is R / t = 0.5 (R : Bending radius, t: plate thickness) and bending workability without cracking, and 180 ° bending after heating at 150 ° C. for 1000 hours-no bending of Sn layer by bending back can be achieved.

In addition, in the case of a copper alloy material with Sn plating, since Sn or Sn alloy layer exists on the surface, the solder spreadability when soldering the manufactured terminal to a substrate using Pb-less solder or general solder is excellent. Good solder joint strength can be obtained. Furthermore, for the reflow-treated material, the stress generated in the Sn or Sn alloy layer is reduced, Sn whiskers are not generated, short circuits are not generated even when used for narrow pitch terminals, and the reliability of electronic components is improved. improves.
The copper alloy material and the copper alloy material with Sn plating of the present invention can be effectively used widely as materials for electric and electronic parts such as home appliances, industrial equipment, and automobiles. In particular, when it is used as a material constituting a bus bar for in-vehicle JB, the bus bar can be reduced in size and weight. Moreover, since the copper alloy for electrical / electronic parts according to the present invention can be manufactured by a general copper alloy manufacturing method, it contributes to cost reduction of the bus bar.

It is the schematic which shows the structural example of a bus bar.

Hereinafter, the copper alloy for electrical and electronic parts according to the present invention (hereinafter referred to as “the copper alloy of the present invention”) and the copper alloy material with Sn plating using the copper alloy of the present invention will be described in detail.
The copper alloy of the present invention contains a specific amount of Fe, P, Mg, Sn, and Zn, and the balance is composed of Cu and inevitable impurities, and the content of Fe, Mg, and P is specified. Have the relationship. If necessary, a specific amount of one or more of Al, Si, Mn, Ni, Co, and Cr is contained.
Hereinafter, the numerical range of the content of each component constituting the copper alloy of the present invention, the reason for limiting the numerical range, and the relational expression of the contents of Fe, Mg, and P will be described.

(Fe content: 0.01 to 0.2% by mass)
Fe is effective for forming Fe-P-based fine precipitates and improving the strength by precipitation hardening, and by reducing the amount of Fe and P solid solution by precipitating with P and improving the conductivity. It is an element. When the Fe content is less than 0.01% by mass, the effect of improving the strength due to sufficient precipitation cannot be obtained, and the electrical conductivity is not improved. Moreover, when it exceeds 0.2 mass%, while causing the fall of electrical conductivity, it will cause the coarsening of a precipitate and will cause the fall of a stress relaxation characteristic and bending workability. Therefore, the Fe content is in the range of 0.01 to 0.2% by mass. The content of Fe is preferably 0.02 to 0.17% by mass, and more preferably 0.05 to 0.16% by mass.

(P content: 0.02-0.15 mass%)
P is an effective element for forming precipitates with Fe and Mg and improving the strength by precipitation hardening and reducing the amount of solid solution of P, Fe and Mg and improving the conductivity. If the P content is less than 0.02% by mass, precipitates with Fe and Mg are not sufficiently formed, so that the effect of improving the strength cannot be obtained, and the solid solution amount of Fe and Mg is increased, resulting in increased conductivity. The rate drops. On the other hand, if the P content exceeds 0.15% by mass, the Mg solid solution amount decreases and the stress relaxation characteristics decrease, and the P solid solution amount increases and the conductivity decreases. Therefore, the P content is in the range of 0.02 to 0.15 mass%. The content of P is preferably 0.03 to 0.15% by mass, and more preferably 0.05 to 0.12% by mass.

(Mg content: 0.05 to 0.2% by mass)
Mg is effective for forming Mg-P-based fine precipitates and improving the strength by precipitation hardening, and by reducing the Mg and P solid solution amount by precipitation with P, thereby improving the conductivity. It is an element. Further, Mg that does not precipitate and remains in solid solution is effective in improving strength and improving stress relaxation resistance due to solid solution. When the Mg content is less than 0.05% by mass, it is not possible to sufficiently obtain an improvement in strength due to precipitation of Mg—P precipitates and an improvement in solid solution strengthening and stress relaxation resistance due to solid solution Mg. On the other hand, if it exceeds 0.2% by mass, the precipitate becomes coarse and causes a decrease in bending workability, and solid solution Mg increases, leading to a decrease in conductivity. Therefore, the Mg content is in the range of 0.05 to 0.2 mass%. The content of Mg is preferably 0.08 to 0.19% by mass, and more preferably 0.10 to 0.18% by mass.
If the Mg content is high, a large amount of Mg oxide may adhere to the furnace wall of the melting furnace, which may lead to a reduction in the quality of the next casting, and there is a problem of a decrease in production efficiency due to an increase in furnace washing. .

(Relationship of Fe, Mg and P contents)
In the copper alloy of the present invention, it is essential that the contents of Fe, Mg, and P are in a relationship of 2.5 ≦ (Fe + Mg) /P≦8.0 as shown in the relational expression (1). If (Fe + Mg) / P is less than 2.5, the amount of Fe, Mg solid solution decreases and the stress relaxation characteristics deteriorate. On the other hand, if it exceeds 8.0, Mg—P precipitates and Fe—P precipitates are coarsened to lower the bending workability, and the Fe and Mg solid solution amounts are increased, leading to a decrease in conductivity. In order to improve stress relaxation characteristics, a range of 3.0 ≦ (Fe + Mg) /P≦5.0 is desirable. Further, in order to improve the stress relaxation characteristics, the content of Fe and Mg must be in the relationship of Mg / Fe ≧ 0.85 as shown in the relational expression (2).

(Sn content: 0.01 to 0.2% by mass)
Sn is an element effective for improving the strength by solid solution and improving the stress relaxation resistance. If the Sn content is less than 0.001% by mass, the strength and the stress relaxation resistance cannot be sufficiently improved by solid solution, and if it exceeds 0.2% by mass, the electrical conductivity decreases. Therefore, the Sn content is in the range of 0.001 to 0.2 mass%. The content of Sn is preferably 0.005 to 0.15% by mass.

(Zn content: 0.05 to 1.0 mass%)
Zn is an element effective for improving the heat-resistant peelability of Sn plating and solder used for joining electronic components and suppressing thermal peeling. When the Zn content is less than 0.05% by mass, a sufficient effect for improving the Sn plating and the heat-resistant peelability of the solder cannot be obtained. Moreover, when it exceeds 1.0 mass%, electrical conductivity will fall. Therefore, the Zn content is in the range of 0.05 to 1.0 mass%. The Zn content is preferably 0.07 to 0.40 mass%, more preferably 0.10 to 0.30 mass%.

(S content: 0.005 mass% or less)
When copper scrap in the factory or recovered scrap scrap after stamping is used as a raw material, S is included in the copper alloy as an unavoidable impurity, and combines with added elements such as Mg to reduce the amount of solid solution Mg and reduce resistance. Degrading stress relaxation characteristics. Moreover, the compound becomes a starting point of a crack and bending workability falls. By controlling S to 0.005 mass% or less, stress relaxation resistance and bending workability are maintained. In order to reduce S to 0.005% or less, it is possible to perform casting after adding Mg and then casting after confirming that the Mg concentration in the furnace is within the specified range.

(Al content: 0.001 to 0.030 mass%)
(Si content: 0.001 to 0.030 mass%)
Al and Si are effective elements for desulfurization in the furnace, and are effective elements for improving the strength and stress relaxation characteristics by solid solution in copper. One or two elements are added as required. Is done.
When Al is added alone, if the Al content is less than 0.001% by mass, the desired effect cannot be obtained, and if it exceeds 0.030% by mass, the conductivity is lowered. The Al content is preferably 0.001 to 0.020 mass%, more preferably 0.005 to 0.015 mass%. Further, when Si is added alone, the desired effect cannot be obtained if the Si content is less than 0.001% by mass, and if it exceeds 0.030% by mass, the conductivity may be lowered, and further, Forms exudates and may cause a decrease in bendability. The content of Si is preferably 0.001 to 0.015 mass%, more preferably 0.005 to 0.010 mass%.
When Al and Si are added simultaneously, the total content is 0.001 to 0.050 mass within the range of Al: 0.001 to 0.030 mass% and Si: 0.001 to 0.030 mass%. %. In this case, preferable contents of Al and Si are the same as the above ranges.

(Mn, Ni, Co, Cr)
Like Mg, Mn, Ni, Co, and Cr form a fine compound with P in the copper alloy and increase the strength and conductivity. Therefore, one or more of Mn, Ni, Co, and Cr are added as necessary. In order to exhibit these effects effectively, 0.0005 mass% or more is required by the total content of 1 type, or 2 or more types. However, when the total content of one kind or two or more kinds exceeds 0.05% by mass, the Mg, Fe solid solution amount may increase and the conductivity may be lowered. Further, the coarsening of the precipitated particles is caused and the bending workability is lowered. For this reason, content of these elements shall be 0.0005-0.05 mass% by the total of 1 type or 2 types or more.

(Other inevitable impurities)
In addition to S, Al, Si, Mn, Ni, Co, and Cr, the copper alloy of the present invention has As, Sb, B, Pb, Ti, V, Zr, Mo, Hf, Ta, B, and Bi as inevitable impurities. , C, Ag, In, and the like. As long as these inevitable impurity elements are contained within a range in which an electrical conductivity of 60% IACS or higher is obtained, other characteristics of the copper alloy of the present invention are not significantly hindered. Moreover, in a Cu-Fe-Mg-P-type copper alloy, these components are usually within the following allowable ranges unless particularly added.

As, Sb, B, Pb, Ti, V, Zr, Mo, Hf, Ta, B, Bi, and C have a remarkably small solid capacity with respect to copper, so when the total amount exceeds 0.1% by mass, Grain boundary segregation or crystallized matter is formed to deteriorate the strength characteristics and bending workability. Therefore, the allowable amount is 0.1% by mass in total.
Ag and In are well known to dissolve in copper, which causes a decrease in conductivity. For this reason, the allowable amount is 0.1% by mass or less in total.

(Copper alloy material with Sn plating)
The copper alloy of the present invention is formed into various forms and shapes depending on the application. For example, the sheet material made of the copper alloy of the present invention, a strip formed by slitting the plate member in the width direction, a form obtained by coiling the strip, and various forms and shapes such as a wire rod are formed. And when using the base material (copper alloy base material) which consists of the board | plate material which consists of the copper alloy of this invention, a stripe | line, etc. as a raw material for electrical / electronic components, on the surface of the copper alloy base material, a Cu-Sn alloy layer and It is preferable to use a copper alloy material with Sn plating on which an Sn or Sn alloy layer is formed.

  The Cu-Sn alloy layer is formed by alloying Cu and Sn at the interface between the copper alloy base material and the Sn or Sn alloy plating layer by forming the Sn or Sn alloy plating layer on the surface of the copper alloy base material. Layer. The Cu-Sn alloy layer prevents Cu in the copper alloy base material from diffusing and oxidizing on the surface of the Sn or Sn alloy layer (barrier effect), thereby reducing the contact reliability of the plated copper alloy material. To prevent. For this function, the thickness of the Cu—Sn alloy layer is desirably 0.1 μm or more. On the other hand, the Cu—Sn alloy layer is brittle and the thickness needs to be 1.0 μm or less in order to reduce the bending workability of the Sn-plated copper alloy material. Therefore, the thickness of the Cu—Sn alloy layer is 1.0 μm or less, preferably 0.1 to 1.0 μm. More preferably, it is 0.2 μm or more for ensuring contact reliability, 0.8 μm or less for bending workability, and further 0.5 μm or less.

The Sn or Sn alloy layer is formed on the surface of the copper alloy base material for the purpose of improving solderability, corrosion resistance, etc., and has not been consumed by the formation of the Cu-Sn alloy layer. It is a Sn alloy plating layer, and as a result, it will be formed on the Cu-Sn alloy layer formed on the surface of the copper alloy base material. The thickness of the Sn or Sn alloy layer is preferably 0.3 to 1.0 μm. When the thickness of the Sn or Sn alloy layer is less than 0.3 μm, the solder wettability at the time of soldering is lowered, and the solder joint strength is lowered. On the other hand, if it is thicker than 1.0 μm, the scrap of Sn or Sn alloy deposited on the surface is oxidized when the terminal is inserted, and the stress distribution on the plating outermost surface becomes non-uniform, thereby promoting the generation of whiskers. Furthermore, if there are many scraps that accumulate, if vibration or the like occurs, it may fall into the circuit and cause a conduction failure. The thickness is desirably 0.8 μm or less, and more desirably 0.7 μm or less.
In the case of a Sn alloy layer, Cu, Ag, Bi, etc. are mentioned as structural components other than Sn. These are all desirably less than 10% by mass.

It is preferable to perform a reflow process on the Sn-plated copper alloy material in which the Sn or Sn alloy plating layer is formed on the surface of the copper alloy base material. Thereby, the Sn plating copper alloy material by which the Cu-Sn alloy layer and the Sn or Sn alloy layer which the Sn or Sn alloy plating layer fuse | melted was formed in the surface of a copper alloy base material is obtained.
Also in the Sn-plated copper alloy material after the reflow treatment, the thickness of the Cu—Sn alloy layer is preferably 1.0 μm or less. On the other hand, in order to produce a barrier effect (diffusion of Cu from a copper alloy material into Sn or Sn alloy layer or vice versa), the thickness of the Cu—Sn alloy layer is preferably 0.1 μm or more. The thickness of the Cu—Sn alloy layer is desirably adjusted to 0.1 to 1.0 μm by reflow treatment. Moreover, also about Sn layer, in order to ensure solderability, it is preferable that thickness is 0.3-1.0 micrometer.

(Copper alloy manufacturing method)
Although the manufacturing method of the copper alloy of the present invention is not particularly limited, it may be manufactured by an ordinary method in which each step of casting, hot rolling, cold rolling, annealing, finish rolling, and low temperature annealing is sequentially performed. it can.
Casting can be performed by casting a copper alloy melt prepared by mixing Cu, Fe, P, Mg, Sn, Zn, and S with the above component composition. If there is a lot of S in the component composition analysis of the molten metal, desulfurize with Mg, then check again whether Fe, P, Mg, Sn, Zn and S are within the specified range, and if within the specified range, cast Can be taken.

  Hot rolling can be performed by soaking the ingot obtained by casting at 850 to 950 ° C. for 30 minutes to 3 hours, subsequently rolling to a predetermined thickness, and further quenching at 700 ° C. or higher. it can. In this hot rolling, if the rolling temperature is too low, recrystallization may be incomplete and a non-uniform structure may be formed. If the rolling temperature is too high, surface oxidation occurs vigorously, causing an increase in the amount of chamfering and reducing the yield. And after hot rolling, it water-cools.

Next, cold rolling is a step of rolling a hot-rolled rolled sheet at a normal reduction of 70% or more before annealing and finish rolling in the next step. By this cold rolling, the crystal grain size and its variation after the subsequent annealing can be adjusted.
In order to improve (recover) the strength and conductivity of the copper alloy sheet, annealing is performed by recrystallization and precipitation treatment of P compounds (Fe—P precipitates, Mg—P precipitates) to form fine precipitates. It is this process. This annealing can be performed by heating at 450 to 600 ° C. for 15 minutes to 10 hours.

Finish rolling is a process of rolling to a desired thickness. In this finish rolling, when the copper alloy or Sn-plated copper alloy material of the present invention requires bending workability, it is preferable to set the processing rate to 50% or less.
The low-temperature annealing is performed for the purpose of removing the strain due to finish rolling and increasing the stress relaxation characteristics and the spring limit value. This low-temperature annealing can be usually performed by heat treatment at 250 to 500 ° C. for 5 seconds to 10 hours.
The final average crystal grain size is desirably adjusted to be about 2 to 10 μm when measured by the cutting method described in JISH0501.

The copper alloy material with Sn plating using the copper alloy of the present invention as a base material (copper alloy base material) can be manufactured by performing Sn or Sn alloy plating following the low temperature annealing. Thus, a copper alloy base material, a Cu—Sn alloy layer made of an alloy of the copper alloy base material and Sn or Sn alloy plating, and a Sn or Sn alloy layer (Sn or Sn alloy remaining on the Cu—Sn alloy layer). Sn plating copper alloy material which has a plating layer) can be obtained.
When reflow treatment is not performed, it is desirable to perform bright Sn plating, for example, stannous sulfate 40 g / l, sulfuric acid 100 g / l, cresol sulfonic acid 30 g / l, dispersant 20 g / l, brightener In a plating bath containing 10 ml / l of formalin, 5 ml / l of formalin, and the like, using a Sn plate as the counter electrode with a bath temperature of 20 ° C. and a current density of 2.5 A / dm 2. Examples of the Sn alloy plating include Sn—Cu plating, Sn—Ag plating, and Sn—Bi plating. The content of Cu, Ag, and Bi is preferably about 10% by mass or less.

  In the case of performing reflow treatment, for example, Sn plating is performed in a plating bath containing 50 g / l stannous sulfate, 80 g / l sulfuric acid, 30 g / l cresolsulfonic acid, 10 g / l brightener, and the like. Then, the bath temperature is 30 ° C., an Sn plate is used as the counter electrode, and the current density is 3 A / dm 2. Subsequently, the Sn-plated copper alloy material is reflowed. By this reflow process, it can be set as the structure where the copper alloy base material and Sn layer were joined more closely through the Cu-Sn alloy layer. The reflow treatment can be usually performed by heating at 240 to 600 ° C. for 3 to 30 seconds after Sn plating. Examples of the Sn alloy plating include Sn-Cu plating, Sn-Ag plating, and Sn-Bi plating as well as bright Sn plating. Similarly, the content of Cu, Ag, and Bi is desirably about 10% by mass or less.

The copper alloy produced in this way has a high conductivity of 60% IACS or higher, a high strength of 400 N / mm ² or more in both the parallel and perpendicular directions to the rolling direction, and a Vickers hardness of 130 Hv or higher. Furthermore, stress relaxation characteristics (both parallel and perpendicular to the rolling direction are stress relaxation rates of 30% or less after heating at 180 ° C. for 24 hours), bending workability (bending axis is parallel to the rolling direction) Excellent in Sn plating heat-resistant peeling characteristics (Sn plating does not peel by 180 ° bending-bending after heating at 150 ° C. for 1000 hours) It becomes.
In the present invention, the conductivity is preferably 65% IACS or more, and more preferably 70% IACS or more. In order to obtain such high electrical conductivity, the contents of Fe, Mg, and P related to precipitation are set to (Fe + Mg) / P: 2.5 to 3.5, and Mg / Fe: 1.0 to 1.5. For that composition, if the processing rate of cold rolling, the subsequent annealing conditions (temperature and time), and the low-temperature annealing conditions are prototyped within the range of the above-mentioned manufacturing conditions, the heat treatment conditions that can be optimized can be determined from them. Good.

Examples of the present invention will be specifically described below in comparison with comparative examples.
No. in Tables 1 and 2 After melting the copper alloy of the component composition shown to 1-42, it casted to the book mold, and obtained the ingot of thickness 45mm. The ingot was soaked at 900 ° C. for 1 hour, then hot rolled to a thickness of 15 mm, and quenched at 700 ° C. or higher. Next, both sides of the hot-rolled sheet after quenching were polished by about 1 mm in thickness to remove surface oxide scale and scratches. Then, it cold-rolled to thickness 1.07-1.28mm. At this time, the target plate thickness was changed according to the processing rate in the next finish rolling. Next, after recrystallization and precipitation annealing at 500 to 550 ° C. for 2 hours, finish rolling was performed to a thickness of 0.64 mm. And it annealed at 350 degreeC for 20 second low temperature, and obtained the sample of the copper alloy plate.

  In Table 1, No. In all of 1-42, the balance composition is Cu, and the elements whose contents are not described in Table 1 are below the detection limit, and As, Sb, B, Pb, Ti, V, Zr, Mo, Hf, Ta , B, Bi, C, and Ag, In, Al were also 0.01% by mass or less, respectively.

No. For each of the samples 1-42, the crystal grain size, electrical conductivity, Vickers hardness, mechanical properties (0.2% proof stress), stress relaxation rate measurement, and bending workability were evaluated according to the following test methods. . The results are shown in Tables 3 and 4.
(Measurement of crystal grain size)
After polishing the sample surface, etching and taking a structure photograph with an optical microscope, the direction of the line segment is perpendicular to the sheet width direction and the sheet width direction from the structure photograph by the cutting method specified in JIS-H0501 , And three directions inclined by 45 ° in the plate width direction, and the average value of three locations was taken as the crystal grain size. No. 1 to 42 all had an average crystal grain size in the range of 2 to 10 μm.

(Measurement of conductivity)
The volume resistivity was measured by a four-terminal method using a double bridge in accordance with a nonferrous metal material conductivity measurement method defined in JIS-H0505. The measured volume resistivity was divided by the volume resistivity 1.7241 × 10 ⁻⁸ Ωm of Universal Annealed Copper Standard and expressed as a percentage to obtain the conductivity (% IACS).
(Measurement of Vickers hardness)
In accordance with the microhardness test method defined in JIS-Z2248, the Vickers hardness was measured at a test load of 4.90 N (= 0.5 kgf).

(Measuring mechanical properties)
A JIS No. 5 tensile test piece having a longitudinal direction in the rolling direction (LD: Longitudinal Direction) and a vertical direction (TD: Transverse Direction) was produced by machining. Each of the two test pieces (LD, TD) was subjected to a tensile test according to JIS-Z2241. The tensile strength corresponding to the permanent elongation of 0.2% was determined as the proof stress.

(Measurement of stress relaxation rate)
The stress relaxation rate was measured by the cantilever method. That is, a strip-shaped test piece having a width of 10 mm that has a length direction parallel to the rolling direction of the plate (LD) and a perpendicular direction (TD) is cut out, and one end thereof is fixed to the rigid body test stand. To do. When a 10 mm deflection is applied to the test piece at a fixed distance from the fixed end, the surface stress corresponding to 80% of the 0.2% proof stress of the material in each direction at the fixed end is aligned with the sampling direction of the test piece. To load. The distance from the fixed end of the position where the deflection is given was calculated according to the Japan Copper and Brass Association Technical Standard (JCBA-T309: 2004) "Stress Relaxation Test Method by Bending Copper and Copper Alloy Thin Sheet Strip". The test piece fixed to the rigid body test stand and subjected to bending is held after being held in an oven heated to a constant temperature and then taken out. The permanent distortion δ when the bending amount d (10 mm) is removed is measured, and the stress relaxation rate RS = Calculate (δ / d) × 100. Heating conditions are specified by JASO of the Japan Society of Automotive Engineers for 1000 hours of heating at 150 ° C. In this test, the Larson Miller conversion method (LM , P. = T (20 + logt)), and an accelerated test was performed under heating conditions at 180 ° C. for 24 hours corresponding to 1000 hours at 150 ° C. In Table 1, No. 1 and no. It is confirmed that the values obtained when using No. 5 and heating at 150 ° C. for 1000 hours and when heated at 180 ° C. for 24 hours are equivalent.

(Evaluation of bending workability)
The bending workability was evaluated according to the W-bending test method defined in Japan Copper and Brass Association Standard JBMA-T307. That is, a test piece having a width of 10 mm and a length of 30 mm was cut out from a copper alloy plate, and Good Way (bending axis was perpendicular to the rolling direction, hereinafter referred to as “GW”) and Bad Way (bending axis was parallel to the rolling direction). In the following, a bending test of “BW” was performed at R / t = 0.5 (R: bending radius, t: plate thickness). The presence or absence of cracks in the bent portion was visually observed with a 100 × optical microscope and evaluated according to the following criteria. In this technical field, it is sufficient that the evaluation is AC evaluation with no crack in the following evaluation.
A: No wrinkle, B: Small wrinkle, C: Medium to large wrinkle, D: Small crack, E: Large crack.

Next, no. Using a copper alloy of 1, 10, 34, and 35 as a base material, the surface of the base material was subjected to bright Sn plating and reflow Sn plating under the following conditions to obtain a sample of a copper alloy material with Sn plating.
(Glossy Sn plating conditions)
Gloss Sn plating was performed on the surface of the base material under the conditions described above.
(Reflow Sn plating conditions)
Under the conditions described above, Sn plating was performed on the surface of the base material, and then reflow treatment was performed by heating at 380 ° C. for 13 seconds.

About each sample of the obtained copper alloy material with Sn plating, the thickness of the Sn layer and the thickness of the Cu-Sn alloy layer were measured according to the following method, and the heat-resistant peeling test and the solder wettability test of Sn plating were performed according to the following test methods. Went. The results are shown in Table 5.
(Measurement of Sn layer thickness and Cu-Sn alloy layer thickness)
The thickness of the Sn layer was measured using a fluorescent X-ray film thickness meter (Seiko Electronics Co., Ltd .: SFT3200). Thereafter, only the Sn layer was peeled off, and the thickness of the Cu—Sn alloy layer was measured.
(Heat-resistant peel test of Sn plating)
A test piece cut to a size of 30 mm in length and 10 mm in width was heated in an oven at 150 ° C. for 1000 hours, and then subjected to a 180 ° bending return test with a diameter of 2 mm using a mandrel 180 ° bending jig. The appearance of the Sn layer was observed by attaching and removing the tape on the inner side, and the presence or absence of peeling was examined.

(Solder wettability test)
Commercially available Sn-3 mass% Ag-0.5 mass% Cu solder is held at 260 ± 5 ° C. and melted, and each specimen is melted at a dipping speed of 25 mm / sec, a dipping depth of 12 mm, and a dipping time of 5 sec. Soaked. A solder checker (manufactured by Resuka Co., Ltd .; SAT5100 type) was used as a soldering apparatus, and an inactive flux (Nippon Alpha Metals Co., Ltd .; α100) was used as the flux. The solder wettability was evaluated as ○ (good) when the wetting time was less than 2 sec, and x (bad) when 2 sec or longer.

As shown in Table 3, the contents of Mg, Fe, P, Sn, Zn and S are within the scope of the present invention, and the contents of Fe, Mg and P satisfy the relational expressions (1) and (2). No. 1 to 25 copper alloys have electrical conductivity, hardness, proof stress (LD / TD), stress relaxation properties (LD / TD), and bending workability (GW). /B.W.) Are all excellent.
As shown in Table 5, No. No. 1 or 10 having a copper alloy as a base material and Sn layer thickness and Cu—Sn alloy phase thickness within the scope of the present invention. Nos. 43 to 48 are both excellent in peel resistance after heating and solder wettability with both the bright Sn plating material and the reflow Sn plating material.

On the other hand, as shown in Table 4, no. As described below, the copper alloys of 26 to 42 are inferior in any of the above characteristics.
No. In No. 26, since the Fe content is excessive, P decreases due to the formation of the Fe—P compound, but there are many solid capacities of Fe and Mg that do not precipitate, and the stress relaxation characteristics are inferior.
No. In No. 27, since the Fe content is insufficient, formation of the Fe—P compound is insufficient and the strength is low.
No. No. 28 has an excessive content of P, so that the Mg solid solution amount decreases. D. / T. D. Both have large stress relaxation rates.
No. In No. 29, the P content is insufficient, the formation of P compound is insufficient and the strength is low, and the Mg content is insufficient, so that the stress relaxation rate is large.

No. In No. 30, the Mg content is excessive, and the precipitates are coarsened, so that the bending workability is lowered.
No. No. 31 has a low Mg content due to a lack of Mg content, resulting in a low Mg solid content and a low Mg solid volume. D. / T. D. Both have large stress relaxation rates.
No. No. 32 has an excessive Sn content, resulting in an increased Sn solid capacity and a low electrical conductivity.
No. No. 33 has a large stress relaxation rate because the Sn content is insufficient.
No. No. 34 has an excessive Zn content, so the amount of Zn solid solution increases and the conductivity is low.
No. 35 is excellent in electrical conductivity, strength, stress relaxation characteristics and bending workability, but the Zn content is insufficient and, as will be described later, peeling of Sn plating occurs in both the bright Sn plating material and the reflow Sn plating material. It was.

No. 36, when the content of S exceeds the allowable value, it binds to Mg having a strong affinity, and the Mg solid capacity decreases. D. The stress relaxation rate is large. Bending workability is also reduced.
No. In No. 37, the total content of Al and Si is excessive, the solid solution amount of Al and Si is increased, and the electrical conductivity is low.
No. In No. 38, since the value of (Fe + Mg) / P is excessive, the compound is coarsened and bending workability is lowered.
No. No. 39 has a low value of (Fe + Mg) / P, so that the Fe and Mg solid volumes decrease. D. / T. D. Both have large stress relaxation rates.
No. In No. 40, the value of (Fe + Mg) / P is excessive and the contents of Sn and Zn are excessive, bending workability is lowered, the solid solution amount of Sn and Zn is increased, and the conductivity is also low.
No. No. 41 has an excessive value of (Fe + Mg) / P and an excessive total content of Al and Si, the bending workability is lowered, the solid solution amount of Al and Si is increased, and the conductivity is considerably low.
No. No. 42 has a Mg / Fe value that is too low, resulting in a decrease in Mg solid volume. D. / T. D. Both have large stress relaxation rates.

Moreover, as shown in Table 5, the Sn layer thickness and the Cu—Sn alloy layer thickness are within the scope of the present invention. Nos. 43 to 52 have excellent solder wettability with both the bright Sn plating material and the reflow Sn plating material. However, a copper alloy (alloy No. 35) with insufficient Zn content is used as a base material. As for 50 and 52, peeling of Sn plating arose.
No. Sn layer thickness and Cu—Sn alloy phase thickness are outside the scope of the present invention. Nos. 53 to 58 are inferior in solder wettability regardless of whether the alloy composition satisfies the provisions of the present invention. Furthermore, a copper alloy (alloy No. 35) whose Zn content is insufficient is used as a base material. 57 and 58 also caused Sn plating peeling.

1 Busbar
2a, 2b Pressure contact part 3 Female terminal part 4 Male terminal 5 Lower part

Claims (8)

Fe: 0.01-0.2 mass%, P: 0.02-0.15 mass%, Mg: 0.05-0.2 mass%, Sn: 0.001-0.2 mass%, and Zn : 0.05-1.0% by mass, the balance is made of Cu and inevitable impurities, S: 0.005% by mass or less, and Fe, Mg and P contents are represented by the following formulas (1), (2 ), A copper alloy for electrical and electronic parts.
2.5 ≦ ([Fe] + [Mg]) / [P] ≦ 8.0 (1)
[Mg] / [Fe] ≧ 0.85 (2)
Here, [Fe], [Mg], and [P] represent Fe, Mg, and P contents, respectively. Furthermore, Al: 0.001-0.030 mass%, Si: 0.001-0.030 mass% 1 type or 2 types are included in total 0.001-0.050 mass%, It is characterized by the above-mentioned. Item 4. A copper alloy for electrical and electronic parts according to item 1. The copper alloy for electrical / electronic parts according to claim 1 or 2, characterized by containing 0.0005 to 0.05 mass% in total of one or more of Mn, Ni, Co and Cr. The copper alloy for electric / electronic parts according to any one of claims 1 to 3, wherein the stress relaxation rate after heating at 180 ° C for 24 hours is 30% or less. The copper alloy for electrical / electronic parts according to any one of claims 1 to 3, wherein the electrical conductivity is 65% IACS or more. The copper alloy for electrical / electronic parts according to any one of claims 1 to 3, wherein the electrical conductivity is 70% IACS or more. A copper alloy base material comprising the copper alloy for electric / electronic parts according to any one of claims 1 to 6, and a Cu-Sn alloy layer having a thickness of 1.0 µm or less formed on a surface of the copper alloy base material And a Sn or Sn alloy layer having a thickness of 0.3 to 1.0 μm formed on the surface of the Cu—Sn alloy layer. A copper alloy base material comprising the copper alloy for electric / electronic parts according to any one of claims 1 to 6, and a Cu-Sn alloy layer having a thickness of 1.0 µm or less formed on a surface of the copper alloy base material And a Sn or Sn alloy layer having a thickness of 0.3 to 1.0 μm formed on the surface of the Cu—Sn alloy layer, and the Cu—Sn alloy layer and the Sn or Sn alloy layer are formed of the copper alloy mother layer. A copper alloy material with Sn plating, which is formed by reflowing an Sn or Sn alloy plating layer formed on the surface of the material.

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