JPS62136559A - Manufacture of copper alloy material for electronic equipment - Google Patents

Abstract

PURPOSE:To improve the strength, electric conductivity and workability by hot working and cold working a Cu alloy contg. restricted amounts of Cr, Sn and P under prescribed conditions. CONSTITUTION:A Cu alloy consisting of 0.2-0.85wt% Cr, 0.02-0.35wt% Sn, 0.003-0.15wt% P and the balance Cu is manufactured by refining. The alloy is hot worked at >=600 deg.C, cooled to <=450 deg.C at >=1 deg.C/sec cooling rate and cold worked. During this cold working, heat treatment at 450-650 deg.C is carried out at least once and the total working rate after the 1st heat treatment is regulated to <=90%.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing a copper alloy material for electronic devices having high electrical conductivity (heat conductivity) and strong mechanical properties.

[Conventional technology]

Generally used for lead frames, lead wires, connectors, contacts, terminals, and electrodes of CU gold alloy electronic devices.
It is known as a practical material with excellent electrical conductivity (heat conductivity) and mechanical properties. In particular, phosphor bronze has a strength comparable to steel or Ni alloy (50 to 70 kg/7), but its electrical conductivity is about 1710 to 115 (10 to 2
5% IAC3). Therefore, for applications that require conductivity and strength, such as semiconductor lead frames, Cu-
2,4wt%Fe-0,12vt%Zn-P alloy (
Hereinafter, wt% is abbreviated as %), Cu-1,5%Fe-0,8
5%Qr-0.55%5n-P alloy is used, conductivity 50-65%lAC3, strength 45-56Kg/Inl7
1.

[Problem that the invention seeks to solve]

In recent years, electronic components have become smaller and more dense, and in particular, highly integrated ICs such as semiconductor ICs require higher conductivity.
Furthermore, it is required to have workability that can withstand precision machining. For example, in place of conventionally mass-produced DIP-type ICs, smaller, higher-density PLCC-type hackses are required, since the Cu-Fe alloy described above causes bending cracks during processing and lacks isotropy as a plate material. Finishing becomes difficult. For this reason, a Cu-Zr-Cr alloy with a conductivity of 80%lAC3 or higher has been proposed, but since active Zr is used, melting must be carried out in a special atmosphere, preferably in a vacuum.
It is not practical due to high cost. Therefore, there is a strong desire to develop an inexpensive CU gold alloy that has high electrical conductivity and mechanical strength to meet the needs of miniaturization and high density, and has workability, especially legally homogeneous workability as a plate and strip. .

[Means for solving problems]

In view of this, as a result of various studies, the present invention has an electrical conductivity of 70 to 90.
%lAC3, a strength of 45 to 80 to 91/-, and a method for producing a copper alloy material for electronic devices that has isotropic and homogeneous workability.

That is, one of the manufacturing methods of the present invention is 0.20 to 0.85% Cr.
, S n 0.02-0.35%, P O, 003-0
．． After hot-working an alloy containing 15% Cu and the remainder consisting of Cu at 600°C or higher, it is cooled to 450°C or lower at a rate of 1°C/Sec or higher, and then processed at least once at 450°C or higher.
It is characterized in that cold working including heat treatment at 650° C. is performed, and the total working rate after the first heat treatment is 90% or less.

Another method of the present invention is Cr0.20-0.8
5%, S no, 02~0.35%, P O, 003~
0.15%, containing 0.5% or less of Ni or Co, the balance being C
After hot working an alloy consisting of LI at 600°C or higher, 4
Cool at a rate of 1°C/sec or more to 50°C or lower,
After that, cold working including at least one heat treatment at 450 to 650°C is performed, and the total working rate after the first heat treatment is 9.
It is characterized by being 0% or less.

In the present invention, as the material to be hot-processed, for example, an ingot having the above-mentioned alloy composition is melted and cast, and the material is heated to 600°C.
The above is usually subjected to hot working at a temperature of 900 to 700°C. Hot-processed materials are immediately cooled to 1°C/S by water or air cooling.
Cool to 450°C or less at a rate of ec or higher, and adjust the surface by milling or the like. This is subjected to 10 to 60% cold working, then heat treated at 450 to 650°C for 15 minutes to 4 hours, cold worked again, and if necessary, reheated to finish it into predetermined dimensions. In this cold working, the total working rate from the first heat treatment is set to 90% or less, and low-temperature annealing at 250 to 400° C. is added as necessary to the cold working.

[Effect]

In the present invention, the alloy composition is limited as described above.
Conductivity 70-90%lAC3, strength 45-60Kl/r
This is to obtain a CLI alloy material having isotropic and homogeneous workability of rrt/r. That is, Cr precipitates above the solid solubility limit of CU and improves strength while maintaining high electrical conductivity.
The r content was limited to 0.2 to 0.85% because 0.2
If it is less than %, sufficient strengthening effect cannot be obtained. This is because if it exceeds 0.85%, excessive precipitated Cr will inhibit workability.

If workability is important, it is desirable that the Cr content is 0.45% or less. As a solid solution, sn strengthens the effect of Or and improves workability.The details are unknown, but the first effect is to suppress the precipitation of coarse Cr grains during the hot working process, and to strengthen the cold working process. Precipitation of fine Cr grains is promoted by processing and heat treatment. However, the reason why the 3N content was limited to 0.02 to 0.35% was because if it is less than 0.02%, the effect is insufficient, and if it exceeds 0.35%, the conductivity will decrease significantly. be.

P suppresses the development of fibrous Cr that causes precipitates and crystal grain orientation during rolling of the CLI-3n-Cr alloy sheet with breakage, and the P content is set to 0.003 to 0.15. %, because if it is less than 0.003%, it will not have the above effect.
This is because if it exceeds 0.15%, the conductivity will decrease significantly. Ni or Co is used in combination with P to make the effect of P more effective, and the Ni or Co content is set to 0.5.
% or less because if it exceeds 0.5%, the conductivity will drop significantly.

Next, after hot rolling the alloy having the above composition at 600°C or higher,
Cool down to 450°C or less at a rate of 1°C/Sec or more,
The reason why such wheat is subjected to cold processing including at least one heat treatment at 450 to 650°C is that the effect of the above 3n content is obtained by hot processing at 600°C or higher, preferably 850 to 100°C, and hot processing is performed. After that, it is realized when the cooling rate to at least 450°C is 1°C/sec or more,
Lower cooling rates result in the development of coarse grains. Next, the hot-worked material in a supersaturated state is subjected to cold working strain to produce 4
It is precipitated into fine particles by heat treatment at 50 to 650°C. This is because cold working is then added again to finish it to the desired dimensions.

In a rolled plate strip, precipitates and crystal grains are oriented by rolling, resulting in directional properties in the mechanical properties in the rolling direction and the direction perpendicular to the rolling direction. Qu-3n-〇r gold alloy This tendency is remarkable, and we learned that the main reason for this is that the 01 grains are deformed into fibers and oriented in the roll direction. This suppresses the growth of Cr.

Further, in the present invention, by controlling the total cold working rate after heat treatment to 90% or less, it is possible to suppress the development of fibers and improve homogeneous workability. This is effective not only in processability but also in etching and plating, which are widely used in electronic component processing. For example, to make plating and etching uniform. In particular, when a high degree of uniformity is required, it is desirable that the cr content be 0.5% or less.

Furthermore, in the present invention, the addition of P improves the deoxidizing effect and castability when the alloy is melted in the atmosphere. Of course, it is also possible to melt in an inert gas, and in this case, the residual oxygen concentration can be maintained more slowly than with active elements such as Ti and Zr, which is advantageous in terms of equipment, and it is also economical, as waste can be turned around. It can be said that this method is excellent in terms of sex.

〔Example〕

An alloy having the composition shown in Table 1 was melted and cast in the atmosphere to a thickness of 30. , width 40. , and water-cooled as an ingot with a length of 250 mm. This was heated to about 850°C and hot rolled to a thickness of 5a11, the hot rolling was finished at 600 to 690°C, and the cooling conditions were immediately changed to cool it. At this time, the average cooling rate up to 450°C was actually measured. Next, this was pickled to remove scale, cold rolled to a thickness of 1.2 m, then heat treated in an Ar atmosphere for 1 hour, and cold rolled again to finish it into a predetermined size. In addition, some are subjected to reheat treatment during cold rolling, and some are heated to 0.5 at 300°C after cold rolling.
Added low temperature annealing for an hour. These processing conditions are shown in Table 2.

Next, let's talk about the plate material obtained. In order to determine the electrical conductivity, tensile strength, and elongation, and at the same time examine the formability of the plate material, we used dies with various edge angles (radius R) to
A press bending test was conducted, and the presence or absence of cracks in the bent portion was determined using a microscope, and the limit R/l (t=plate thickness) without cracking was determined. Measurements were made in the rolling direction of the plate and in the direction perpendicular to rolling. Also, to check plating properties, Hz SO+ -H
After melting with a 20z mixture to a thickness of 1μ, a 5n-10% Pb alloy plating with a gloss of 5μ was performed using a borofluoride solution (using a brightener manufactured by 6 Genryaku Co., Ltd.), and the glossiness was compared. These results were compared to the conventional Cu-2,4%l”e-0,12%
Zn-2 alloy material and Cu-1,5%Fe-0,85%C
A comparison with r-〇, 55% 5n-P alloy is shown in Table 3.

As is clear from Tables 1 to 3, the method of the present invention N011
According to ~6, the conductivity is 90% or more, the strength and elongation are sufficient, the bending workability is also extremely good, and the conventional material N0.19 ~
It can be seen that it is much better than 20. Also, if you compare the present invention method No. 1 and No. 6, P! =N i
The effect of the combined use of the present invention method No. 2 and No. 3 was found.
The effect of low-temperature annealing after finish rolling can be seen by comparing.

On the other hand, comparative methods Nos. 7 to 13, which fall outside the alloy composition range specified by the method of the present invention, and comparative methods No. 14 to 1, whose processing conditions deviate from the alloy composition range specified by the method of the present invention.
It can be seen that all samples No. 7 are inferior in one or more of electrical conductivity, strength, and bending workability. That is, Comparative Method No. 7 with a low Cr content, Comparative Method No. 9 with a low Sn content, and Comparative Method No. 0.11 with a low P content all showed significant deterioration in strength, while Comparative Method No. 7 with a high Cr content , 8, Comparative method with high Sn content NO. 10, Comparative method with high P content and Comparative method with high Ni content, not only did the conductivity decrease significantly, but also the workability deteriorated. Furthermore, even with alloys within the alloy composition range specified in the present invention, coarse crystals develop in Comparative Method No. 14, which has a slow cooling rate after hot rolling, resulting in poor conductivity, strength, and bending workability. I understand.

Comparative method No. 15, in which the heat treatment temperature is low, and Comparative method No. 16, in which the heat treatment temperature is high, result in insufficient precipitation and insufficient electrical conductivity. Comparative method N 0.17, which has the highest total work rate, develops directionality and the workability is not uniform. (Effect of the invention) In this way, by adding P or P and Ni to the cu-cr-sn alloy, J: If the method of the present invention is processed under the following conditions, it has strength and conductivity (thermal conductivity) suitable for use as a copper alloy material for electronic components, especially for miniaturized and high-density semiconductor lead frames,
Moreover, it enables high-level processing, and has a remarkable effect that can respond to highly integrated electronic devices.

Claims (2)

[Claims] (1) Cr0.20~0.85wt%, Sn0.02~
After hot working an alloy containing 0.35 wt%, P0.003 to 0.15 wt%, and the balance consisting of Cu at 600°C or higher, it is cooled to 450°C or lower at a rate of 1°C/sec or higher, and then at least A method for manufacturing a copper alloy material for electronic devices, characterized by subjecting the material to cold working including one heat treatment at 450 to 650°C, and making the total working rate after the first heat treatment 90% or less. (2) Cr0.20~0.85wt%, Sn0.02~
0.35wt%, P0.003-0.15wt%, Ni
Alternatively, an alloy containing 0.5 wt% or less of Co and the balance consisting of Cu is hot worked at 600°C or higher, then cooled to 450°C or lower at a rate of 1°C/sec or higher, and then processed at least once at 450-650°C. 1. A method for producing a copper alloy material for electronic devices, which comprises performing cold working including heat treatment at a temperature of 0.degree.