JPH0356294B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a high-strength copper alloy for high thermal/electrical conductivity used in electric/electronic equipment and heat exchangers, and a method for producing the same. The present invention provides a copper alloy suitable for use as lead materials for small, high-density semiconductors. [Prior art] Copper alloys that have strength and thermal and electrical conductivity (hereinafter abbreviated as conductivity), such as phosphor bronze (Sn4~8wt), are used for external connectors of semiconductor leads, conductive springs such as switch relays, and various terminals. % or less, P0.6wt% or less, balance Cu) (hereinafter wt% is abbreviated as %), but recently, as devices become smaller and more dense, the need for heat dissipation increases due to the increase in heat generation. Furthermore, solderability, plating performance, scale adhesion, and corrosion resistance have become essential conditions for soldering to printed circuit boards and plastic molding. Phosphor bronze has a strength of 50 to 65 Kg/ ^mm2 and is excellent in workability, but its conductivity is low at 10 to 20% IACS, and it contains 4 to 8% of expensive Sn, resulting in poor solder joint strength. Not only does it cause deterioration over time, but it also has the disadvantage of being highly susceptible to stress corrosion cracking. Therefore, Cu−Be
The alloy Cu-Fe alloy came into use. [Problems to be solved by the invention] Although the Cu-Be alloy exhibits a strength of over 100 kg/mm,
Due to its high cost, its use is limited to special applications. In addition, Cu-Fe alloys, such as C-195 alloy (1.5%Fe.Co08%, Sn0.6%, P0.1%, balance
Cu) is relatively cheap and is widely used in lead frames, etc., with an altitude of 45 to 55 Kg/mm ² and a conductivity of 50 to 65.
%IACS, but it contains a large amount of Fe _x P and Fe precipitates, resulting in poor workability, solder joint strength, plating properties, etc. Other Cu-Cr alloys and Icorson alloys (Cu-Ni-Si alloys) are known, but
Although Cu-Cr alloy shows high conductivity of 80% IACS class, its strength is insufficient.Corson alloy not only has unstable properties but also has a large deterioration in solder joint strength.
or Sn-Pb alloy (solder) plating is likely to peel off,
It has become a serious hindrance in applications such as electronic and electrical equipment. There is a need for improved alloys to meet the ever-increasing needs for high-performance alloys, and such alloys are required to have the following properties. (1) Excellent strength, heat resistance, and corrosion resistance. (2) Good homogeneity of workability, conductivity, and stability. (3) High solder joint strength, little deterioration over time, and good plating properties. (4) Good adhesion of oxide scale. [Means for solving the problem] In view of this, the present invention has been developed as a result of various studies,
We have developed a high-strength copper alloy for high thermal and electrical conductivity with excellent strength, solder joint strength, plating properties, oxide scale adhesion, and corrosion resistance, as well as a method for producing the same. That is, one of the alloys of the present invention contains 0.4 to 4% of Ni, Co, or a mixture thereof, and 0.1 to 1% of Si, and further contains Ta, Nb, and Mitsushi Metal (hereinafter referred to as MM) of 1% or less each.
), one or more selected from the group consisting of less than 0.05% Ag, totaling 0.01 to 1%
It is characterized by the fact that it contains Cu and the remainder consists of unavoidable impurities. Another alloy of the present invention contains 0.4 to 4% of Ni, Co or a mixture thereof and Si.
Contains 0.1 to 1% of Ta, Nb, and 1% or less of each.
Contains a total of 0.01 to 1% of any one or two or more selected from the group consisting of Ag with less than MM0.05%,
Furthermore, it contains one or more of Mn 0.5wt% or less, Zn 5% or less, Sn 5% or less, and the remainder
It is special in that it consists of Cu and unavoidable impurities. In addition, the manufacturing method of the present invention includes 0.4 to 4% of Ni, Co, or a mixture thereof, 0.1 to 1% of Si, and furthermore, selected from the group consisting of 1% or less of Ta, Nb, and MM of less than 0.05 Ag. Contains a total of 0.01 to 1% of one or more of the following, or Mn 0.5% or less,
An alloy containing one or more of Zn 5% or less and Sn 5% or less, with the remainder Cu and unavoidable impurities, is hot worked at 650°C or higher and immediately
After cooling down to 350℃ or less at a rate of ℃/sec or more,
It is characterized by cold working of 70% or more and then heat treatment at 400 to 600°C. In the present invention, the above alloy composition is blended and melted by a conventional method, and an ingot is cast by a water-cooled mold casting method, etc., and then hot worked at a temperature of 650°C or higher, preferably 700°C or higher, and immediately cooled by water cooling or air cooling. do. Next, the surface is cleaned by milling, pickling, etc.
70% or more cold working, then 400~600℃
It is preferably finished by heat treatment at 450 to 550°C for 1 minute to 24 hours. Note that cold working and heat treatment can be repeated as necessary. [Function] In the present invention, the addition of Ni, Co or a mixture thereof and Si is an intermetallic compound Ni ₂ Si or/and
Co ₂ Si is precipitated by heat treatment to improve strength and recover electrical conductivity.
The content of Co or a mixture thereof is 0.4-4%, Si
The reason why the content is limited to 0.1 to 1% is because if the content is less than the lower limit, a sufficient effect cannot be obtained, and if the content exceeds the upper limit, not only the conductivity decreases but also processability is impaired. The stoichiometric ratio of Ni ₂ Si and Co ₂ Si is 5.2:1, and it is desirable that the blending ratio of Ni, Co, or a mixture thereof and Si be close to the stoichiometric ratio within the above composition range. , excess Ni,
Co or Si lowers electrical conductivity and also causes a decrease in workability and solder connection strength. Ta, Nb, MM 0.01~1% each, Ag 0.01~
The addition of one or two of these 0.05% is to further improve the strength and stabilize the properties, and the total content of one or more of these is 0.01 to 1%. The reason for this limitation is that if the content is less than the lower limit, a sufficient effect cannot be obtained, and if the content exceeds the upper limit, not only will the conductivity decrease, but also the cost will increase and processability will be impaired. In other words, the precipitation of Ni ₂ Si and/or Co ₂ Si is complicated not only by alloy composition and heat treatment conditions but also by processing conditions, making the actual properties unstable.
works to stabilize the characteristics. The mechanism of action is not clear, but it is thought that they combine with Si and consume unreacted Si to improve strength. These also work to make crystals finer and improve workability during manufacturing. In particular, MM improves press formability, and Ag,
MM improves heat resistance. Furthermore, the addition of one or more of Mn, Zn, and Sn further enhances the effects of the above-mentioned additive elements.
This is to improve the strength and further stabilize the properties, and the reason why the Mn content is limited to 0.5% or less, the Zn content to 5% or less, and the Sn content to 5% or less is that the content exceeds these limits. This is because if the temperature is increased, the conductivity will be significantly lowered. Furthermore, in addition to the above effects, Mn is effective in improving solder joint strength and hot workability, Zn is effective in improving solder joint strength, and Sn is effective in improving workability. Effective in improving heat resistance. Increasing the amount of added elements decreases the conductivity, so for practical purposes it is especially recommended to use Mn below 0.3%, Zn below 2%,
Sn2% or less is useful. The above alloy of the present invention has a temperature of 650°C or higher, preferably 700°C.
After hot working at ℃ to 950℃, immediately cooling to 350℃ or less at a rate of 10℃/sec or more, cold working to 70% or more, and then heating to 400 to 600℃, preferably
The properties are maximized by heat treatment at 450-550℃. The reason why the alloy of the present invention is hot worked at 650°C or higher and immediately cooled to 350°C or lower at a rate of 10°C/sec or higher is to suppress coarse precipitation. Next, after performing cold working of 70% or more,
The reason why heat treatment is performed at ~600°C is to uniformly disperse and precipitate fine precipitates by heat treating with processing strain applied, and cold working of less than 70% does not result in uniformly dispersed precipitates. Also, the heat treatment temperature is 40℃
If the temperature is below 600℃, precipitation will take a long time and the precipitated particles will become ultra-fine particles, making processability and solder joint strength unstable. to degrade. Further, after the heat treatment, cold working and reheat treatment can be repeated as necessary. That is, after heat treatment and cold working to a desired size, heat treatment is performed at 250 to 350°C to release some of the processing strain and improve elongation and moldability. [Example] An alloy having the composition shown in Table 1 was melted, cast into an alloy, and machined into a material with a width of 80 mm, a thickness of 50 mm, and a length of 300 mm.
mm ingot. This was heated to 870℃ and hot rolled to a plate thickness of 50mm at about 730℃, and then immediately rolled to 350℃.
After cooling to ℃ (water cooling, air cooling, furnace cooling), pickling was performed. This was first cold rolled and then heat treated, and then partially subjected to second cold rolling and then reheated. These manufacturing conditions are shown in Table 2. The above board was tested for tensile strength, elongation, electrical conductivity, heat resistance, solder joint strength, scale adhesion, plating property, and corrosion resistance, and the results were compared to conventional 7/3 brass (Zn 29.7%, balance Cu). , phosphor bronze (Sn6.1%,
P0.15%, balance Cu), C195 (Fe1.6%, Co0.8%,
Table 3 shows a comparison between Sn0.6%, P0.05%, balance Cu). Heat resistance was determined by measuring the hardness after heating at 500℃ for 1 minute, and solder joint strength was determined by measuring a solder joint with a diameter of 5 mm.
A pull test was conducted after heating at 150°C for 300 hours. The scale adhesion was determined by heating on a hot plate at 250 to 400°C in the atmosphere and then performing a tape peeling test to determine the minimum film thickness at which peeling started. The film thickness was measured by the cursor reduction method. Plating property is H ₂ SO ₄ −
After etching the surface to a thickness of approximately 0.3 μm with a H ₂ O mixture, a 3 μm thick Isian silver plate was applied, and this was heated at 470°C for 5 minutes to check for blisters on the surface.
It was tested using a stereoscopic microscope. Corrosion resistance
Based on JISC8306, 30 in 3Vol1% NH gas
A constant load of Kg/mmm ² was applied, and the time until breakage was investigated. In addition, the heat resistance and solder joint strength in the table ( )
The values inside are the measured values before the test.

【table】

【table】

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〔Effect of the invention〕

In this way, the alloy of the present invention satisfies various properties required for electrical/electronic equipment and heat exchangers, including strength and conductivity, and can be used in various electrical/electronic equipment, including semiconductors, to reduce the size and size of such equipment. It has remarkable industrial effects such as making it possible to increase the density and increase the density.

Claims (1)

[Claims] 1 Ni, Co or a mixture thereof at 0.4 to 4 wt%
Contains 0.1 to 1wt% of Si, and further contains less than 1wt% of each
Ta, Nb, Mitsushi Metal, Ag less than 0.05wt%
A high-strength copper alloy for high thermal and electrical conductivity, comprising a total of 0.01 to 1 wt% of one or more selected from the group consisting of, and the balance being Cu and unavoidable impurities. 2 Ni, Co or a mixture thereof at 0.4 to 4 wt%
Contains 0.1 to 1wt% of Si, and further contains less than 1wt% of each
Ta, Nb, Mitsushi Metal, Ag less than 0.05wt%
Contains a total of 0.01 to 1 wt% of one or more selected from the group consisting of, and further contains one or more of Mn 0.5 wt% or less, Zn 5 wt% or less, Sn 5 wt% or less. A high-strength copper alloy for high thermal and electrical conductivity, with the remainder being Cu and unavoidable impurities. 3 Ni, Co or a mixture thereof at 0.4 to 4 wt%
Contains 0.1 to 1wt% of Si, and further contains less than 1wt% of each
Ta, Nb, Mitsushi Metal, Ag less than 0.05wt%
Contains a total of 0.01 to 1 wt% of one or more selected from the group consisting of, or
Contains one or more of Mn 0.5wt% or less, Zn 5wt% or less, Sn 5wt% or less, and the remainder
An alloy consisting of Cu and unavoidable impurities is hot worked at 650℃ or higher, and then immediately heated to 350℃ at a rate of 10℃/sec or higher.
A method for producing a high-strength copper alloy for high thermal and electrical conductivity, which comprises cooling to a temperature below, cold-working 70% or more, and then heat-treating at 400 to 600°C.