JPH07258804A - Production of copper alloy for electronic equipment - Google Patents

Abstract

PURPOSE:To improve strength, stress relaxation ratio, electric conductivity, bendability, and spring limit value which are required of a copper alloy for electronic equipment. CONSTITUTION:The copper alloy has a composition consisting of 0.05-0.4% Cr, 0.03-0.25% Zr, and the balance Cu with inevitable impurities and containing, if necessary, 0.06-2.0% Zn and further 0.01-1.0%, in total, of one or more elements among Ti, Fe, Ni, Sn, In, Mn, P, Mg, and Si. In the manufacturing process of this copper alloy, the following treatments are successively done: (a) solution heat treatment performed at >=700 deg.C under the conditions where average crystalline grain size does not exceed 40mum; (b) cold rolling at 20-60% draft; (c) aging treatment at 300-700 deg.C; (d) cold rolling at <=30% draft; (e) stress relief annealing at 350-700 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a copper alloy for electronic equipment.
Cu-Cr that can be used to manufacture all kinds of electronic parts such as terminals, connectors, relays and switches, which are required to have excellent strength, conductivity, bendability and stress relaxation characteristics in balance. -A method for manufacturing a Zr-based copper alloy.

[0002]

2. Description of the Related Art Conventionally, among the above-mentioned electronic parts, brass is conventionally used in applications where cost is important, phosphor bronze is used in applications where spring characteristics are important, and nickel silver is used in applications where spring characteristics and corrosion resistance are important. Each has been used.

In recent years, however, electronic devices and their parts are required to be smaller and thinner, and
In applications such as automobile transmission parts that are used in a high temperature environment of about a hundred and several tens of degrees Celsius, highly reliable parts that can withstand harsh environments are desired. The following material properties are desired to meet such requirements. (A) It has sufficient strength to generate a high contact pressure even with a thin plate thickness. (B) The stress relaxation rate is low, and the contact pressure does not decrease even after long-term use at high temperature. (C) The conductivity is high, Joule heat is unlikely to be generated when energized, and the generated heat is easily dissipated. (D) Even if severe bending is performed, the bent portion should not be cracked or roughened. (E) The spring limit value is high so that even high spring stress can be used.

In order to meet such demands, the present applicant has developed a Cu--Cr--Sn alloy (Japanese Patent Laid-Open No. 4-4).
1632, 4-110429 and 4-1415
No. 61, the same Japanese Patent Publication No. 4-141561).

[0005] Cu-Cr-Zr alloys for electronic devices are known per se. For example, according to Japanese Patent Laid-Open No. 5-117789, a semi-continuous casting ingot is hot-rolled, and both surfaces are ground. The method of cold rolling is adopted. However, this treatment method cannot obtain sufficient characteristics (a) to (e).

[0006]

The present inventors have found that Cu-
For Cr-Zr alloys, solution treatment brings about sufficient solid solution state of Cr while avoiding coarsening of recrystallized grains,
It was examined to improve the characteristics (a) to (e) by a method of maintaining the solid solution state of Cr by quenching after solution treatment and performing cold rolling at a strong reduction before and after aging to achieve hardening. However, in this method, the spring limit value, conductivity, and bendability did not reach the current required levels.

Therefore, the present invention is directed to Cu--Cr--Zr.
A manufacturing method that can further exhibit the characteristics of alloying elements of a series alloy, achieve excellent results with respect to the above characteristics a) to e), and particularly improve the spring limit value, bendability, and conductivity. The purpose is to provide.

[0008]

According to the present invention, (a) by weight, Cr: 0.05-0.4%, and Zr: 0.03.
.About.0.25% and the balance is Cu and unavoidable impurities, (b) Cr: 0.05
0.4%, Zr: 0.03 to 0.25%, Zn: 0.0
A copper alloy containing 6 to 2.0% and the balance Cu and unavoidable impurities, or c) Cr: 0.05
~ 0.4%, Zr: 0.03-0.25%, and Z
n: 0.06 to 2.0% is contained, and further Ti, Fe, N
One or more of i, Sn, In, Mn, P, Mg and Si: Manufacture of a copper alloy for electronic devices, which contains 0.01 to 1.0% in total and the balance of Cu and inevitable impurities. In the method, (a) solution treatment performed at a temperature of 700 ° C. or higher and under conditions where the average crystal grain size does not exceed 40 μm, (b) cold rolling with a workability of 20 to 60%, (c) 3
Aging treatment at a temperature of 00 to 700 ° C, (d) processing degree of 30
% Cold or less and (e) strain relief annealing at a temperature of 350 to 700 ° C. are sequentially performed, and the invention relates to a method for producing a copper alloy for electronic devices. The configuration of the present invention will be described below. First, the composition of the copper alloy of the present invention will be described.

Cr When Cr is aged, the present Cr alone precipitates in the matrix phase to improve the strength and heat resistance of the alloy, but if its content is less than 0.05%, it precipitates. However, the desired effect cannot be expected because the content of Cr is not sufficient.
Remains as a Cr phase in the mother phase, resulting in a significant decrease in conductivity and workability. Therefore, the Cr content was determined to be 0.05 to 0.4%.

Zr Zr has an action of forming a compound with Cu and precipitating in the matrix phase by aging treatment to strengthen this, but if the content is less than 0.03%, the precipitation is insufficient. However, if Zr is contained in excess of 0.25%, undissolved Zr remains in the mother phase as the Zr phase even after the solution treatment, and the conductivity and processing Zr content is 0.03 to 0.25 because it causes a remarkable decrease in the property.
Defined as%.

Zn Zn is a component that is added as necessary because it has the function of improving the heat-resistant peeling property of solder, but if the content is less than 0.06%, the desired effect due to the above-mentioned action is obtained. However, if the Zn content exceeds 2.0%, the conductivity and the stress relaxation property deteriorate, so the Zn content was set to 0.06 to 2.0%.

Ti, Fe, Ni, Sn, In, Mn,
Each of P, Mg and Si has the effect of improving the conductivity of the alloy by precipitation strengthening or solid solution strengthening without significantly deteriorating the conductivity of the alloy. Therefore, if necessary, one or more of them may be added. However, if the total content is less than 0.01%, the desired effect due to the above-described action cannot be obtained, while the total content is less than 0.01%. If the content exceeds 0%, the conductivity and workability of the alloy will be significantly deteriorated. For this reason, single addition or 2
Ti, Fe, Ni, Sn, which are added in the case of more than one kind,
The total content of In, Mn, P, Mg and Si is 0.
It was set to 01 to 1.0%. Then, the manufacturing process of the copper alloy of the said composition is demonstrated.

Solution Treatment The solution treatment is to obtain a high-strength material in the subsequent aging treatment by solid-solving Cr, Zr, Ti and the like in the matrix phase. When the solution treatment temperature is higher, the amount of solid solution increases in the matrix of Cr, Zr, Ti, etc., and the strength after aging becomes higher. Therefore, high strength is secured by setting the solution treatment temperature to 700 ° C. or higher. When the solution treatment temperature becomes high and / or the treatment time becomes long, the crystal grains become coarse. If the average crystal grain size after solution treatment exceeds 40 μm, roughening occurs in the bent portion when the final bending process is performed, so it is necessary to limit the average crystal grain size to 40 μm or less. Further, in the solution treatment, the higher the cooling rate, the higher the strength is likely to be obtained. Specifically, it is desirable to perform water cooling.

Cold rolling In the present invention, high strength is obtained by promoting work hardening and precipitation of precipitates in the subsequent aging step by performing cold rolling after the solution treatment. The first cold rolling is performed at a workability of 20 to 60%. The workability of cold rolling is set to 20% or more because if the content is less than 20%, the above-described effect becomes insufficient and desired strength cannot be obtained. In addition, the reason why the workability is 60% or less is that when the workability exceeds 60%, roughening occurs in the bent portion during bending of the final product. The hardness after cold rolling is preferably in the range of Hv 130 to 160.

The aging aging treatment, this in order to improve the strength and conductivity C
Required for u-Cr-Zr system. Aging treatment temperature is 3
The reason for setting the temperature to 00 to 700 ° C. is that it is not economical because the aging treatment is time-consuming and is less than 300 ° C., and if it exceeds 700 ° C., Cr and Zr are solid-dissolved, which is a characteristic of the age hardening alloy This is because conductivity cannot be obtained. The hardness after the aging treatment is preferably in the range of Hv160 to 190.

Second Cold Rolling In the present invention, cold rolling after aging treatment brings about work hardening, and further refines the precipitate formed in the preceding aging treatment to further increase the strength significantly. . The reason why the workability at this time is 30% or less is that if the workability exceeds 30%, roughening occurs in the bent portion during bending of the final product. The hardness after the second cold rolling is Hv17.
It is preferably in the range of 0 to 200.

In the present invention, in order to improve the spring property and recover the ductility from the above-mentioned working and heat treatment conditions, the strain relief annealing should be carried out in the range of 350-350.
Strain relief annealing is performed at 700 ° C. The strain relief annealing temperature is 350 ° C to
The reason for setting the temperature to 700 ° C. is that sufficient spring properties and ductility cannot be obtained at temperatures lower than 350 ° C., and if it exceeds 700 ° C., re-dissolution of precipitates occurs and the strength remarkably decreases.

The process and manufacturing conditions of the present invention are defined as follows.
This is related to the steps after the solution heat treatment for adjusting the average crystal grain size to 40 μm or less, and the steps and manufacturing conditions before that may be arbitrary. That is, the steps such as solution treatment, hot rolling, intermediate annealing, and cold rolling which are mainly performed for reducing the ingot surface before the solution treatment are not specified. However, when the crystal grains are coarsened by hot rolling or the like, it is necessary to adjust the average crystal grain size to 40 μm or less immediately before solution treatment by cold rolling or a combination of cold rolling and intermediate annealing. is there.

[0019]

[Action]

(A) In the present invention, as described above, the alloy composition and manufacturing conditions are determined so that solid solution and aging of Cr and Zr occur sufficiently, and after sufficiently hardening by aging treatment, cold working with a relatively light workability is performed. The strength was increased by rolling. (B) The alloy composition was limited as described above, and the stress relaxation rate was reduced by sufficiently causing the precipitation reaction by the aging treatment. (C) Good electrical conductivity was obtained by setting the alloy composition and manufacturing conditions so that the aging of Cr and Zr sufficiently occurred. (D) If the average grain size of the copper alloy having the composition of the present invention after solution treatment is limited to 40 μm or less and the workability of the subsequent two cold rolling operations is made to be relatively mild, cold rolling
Excellent bendability is achieved in the aging state. (E) The spring limit value can be increased by determining the alloy composition and manufacturing conditions so that precipitation of Cr and Zr sufficiently occurs, and further performing optimum strain relief annealing.

[0020]

EXAMPLES Next, the effects of the present invention will be described more specifically with reference to examples showing particularly preferable composition ranges. First,
Mainly made of electrolytic copper or oxygen-free copper, copper chromium master alloy, copper zirconium master alloy, zinc, titanium, nickel,
Using tin, indium, manganese, magnesium and copper-phosphorus master alloys as auxiliary materials, copper alloys of various composition shown in the tables of FIGS. It was cast into a 30 mm ingot.
Next, after making each of these ingots a predetermined thickness by hot working or cold working, solution treatment (850 ° C. × 1 to 10 minutes) for adjusting the average crystal grain size in the table, the first time Cold rolling, aging treatment, final cold rolling, and strain relief annealing were sequentially performed under the conditions shown in Table 1 to obtain a 0.25 mm plate.

Then, various test pieces were sampled from the obtained plate material and a material test was conducted to evaluate the characteristics as a material for electronic equipment. The evaluated properties are strength, elongation, conductivity, spring property, bendability, stress relaxation property, and solder heat peeling property. The strength and elongation were measured by a tensile test, and the conductivity was determined by the conductivity (% IACS). As for the spring property, the spring limit value (Kb) was measured. The bendability was evaluated by performing bending with a W bending tester and visually observing the bent portion to examine the degree of skin roughness and the presence or absence of cracks. In addition, the evaluation results are indicated by ◯: no skin roughness and cracking occurred, X: skin roughness or cracking occurred.

Regarding the stress relaxation characteristics, one end of a strip-shaped test piece was fixed and a stress was applied to the other end to apply a bending stress, and this state was maintained at 150 ° C. for 1000 hours,
The strain that remained when the stress was released was measured.

The heat-resistant peeling property of the solder was investigated by plating the material with a solder (90% Sn-10% Pb) having a thickness of 5 μm.
Hold in a high temperature tank at 150 ° C for up to 1000 hours, during which 1
It was taken out every 00 hours and subjected to 90 ° bending reciprocation once to examine the start time of solder peeling. 1000
If the peeling did not occur until the time, the investigation result was "1000.
h ”was displayed.

The results of these investigations are shown in the tables of FIGS.
From the results shown in these tables, the following is clear. That is, all of the alloys 1 to 16 of the present invention are excellent in strength, conductivity, bendability, and stress relaxation characteristics, and sufficiently good evaluations of other characteristics can be obtained.

On the other hand, Comparative Alloy 17 has a poor strength because the Cr content is not sufficient, and Comparative Alloy 1
In Nos. 8 and 19, the Zr and Cr contents exceeded the respective upper limits, and thus the conductivity and bendability were poor. Next, since the Zn content of the comparative alloy 20 exceeds the upper limit, the stress relaxation characteristics and the conductivity are inferior. Comparative alloy 21 has a crystal grain size after solution treatment that exceeds the upper limit value, and comparative alloy 22 has a workability in the first cold rolling that exceeds the upper limit value. Since the workability of the final cold rolling exceeds the upper limit, bendability is poor.
In Comparative Example 23, the workability of the first cold rolling exceeds the adjustable value, and in Comparative Example 25, the temperature of the stress relief annealing exceeds the upper limit value, so that the strength is inferior. is there.

[0026]

By adopting the manufacturing method of the present invention, it becomes possible to obtain a copper alloy having good strength, conductivity, bendability and stress relaxation characteristics, and to reduce the size of electronic devices,
An extremely useful effect in industry is brought about, such as being able to greatly contribute to thinning.

[Brief description of drawings]

FIG. 1 is a table showing the composition and production conditions of the alloy of the present invention.

FIG. 2 is a table showing the composition and manufacturing conditions of comparative alloys.

FIG. 3 is a table showing characteristics of the alloys in Table 1.

FIG. 4 is a table showing the properties of the alloys of Table 2.

Claims (3)

[Claims] 1. Cr: 0.05-0.4% by weight
And Zr: 0.03 to 0.25%, and
In the method for producing a copper alloy for electronic devices, the balance of which is Cu and inevitable impurities, (a) a temperature of 700 ° C. or higher and an average crystal grain size of 40 μ
Solution treatment performed under conditions not exceeding m, (b) cold rolling with a working degree of 20 to 60%, (c) aging treatment at a temperature of 300 to 700 ° C., (d) cold rolling with a working degree of 30% or less. A method for producing a copper alloy for electronic devices, which comprises sequentially performing the steps of rolling and (e) strain relief annealing at a temperature of 350 to 700 ° C. 2. A weight ratio of Cr: 0.05 to 0.4.
%, Zr: 0.03 to 0.25%, Zn: 0.06 to
In a method for producing a copper alloy for electronic devices, which contains 2.0% and the balance is Cu and inevitable impurities, (a) at a temperature of 700 ° C. or higher and an average crystal grain size of 40 μm.
Solution treatment performed under conditions not exceeding m, (b) cold rolling with a working degree of 20 to 60%, (c) aging treatment at a temperature of 300 to 700 ° C., (d) cold rolling with a working degree of 30% or less. A method for producing a copper alloy for electronic devices, which comprises sequentially performing the steps of rolling and (e) strain relief annealing at a temperature of 350 to 700 ° C. 3. A weight ratio of Cr: 0.05 to 0.4.
%, Zr: 0.03 to 0.25%, and Zn: 0.0
6 to 2.0% of Ti, Fe, Ni, Sn,
One or more of In, Mn, P, Mg, and Si: In a method for producing a copper alloy for electronic devices, which contains 0.01 to 1.0% in total, and the balance of Cu and inevitable impurities, B) At a temperature of 700 ° C or higher and an average crystal grain size of 40μ
Solution treatment performed under conditions not exceeding m, (b) cold rolling with a working degree of 20 to 60%, (c) aging treatment at a temperature of 300 to 700 ° C., (d) cold rolling with a working degree of 30% or less. A method for producing a copper alloy for electronic devices, which comprises sequentially performing the steps of rolling and (e) strain relief annealing at a temperature of 350 to 700 ° C.