JPS6393837A - Copper alloy for electronic equipment and its production - Google Patents

Abstract

PURPOSE:To improve strength, electric and thermal conductivities, solderability, plating suitability, corrosion resistance, etc., by incorporating specific amounts of Zr, Cr, and Zn and one or more elements among Mg, Ca, etc., by limiting respective contents of O2, P, and S, and by specifying the grain size of a precipitate. CONSTITUTION:This copper alloy has a composition consisting of, by weight, 0.03-0.3% Zr, 0.05-0.5% Cr, 0.01-0.5% Zn, 0.0005-0.05% of one or more kinds among Mg, Ca, misch metal, Ba, Sr, and B, <=0.0030% O2, <=0.0030% P, <=0.0010% S, and the balance Cu and also has a structure in which grain size of a precipitate is regulated to <=10mu. Further, <=0.4% Sn may be incorporated to this alloy. In order to manufacture this copper alloy, an alloy ingot of the above composition is heated to 840-950 deg.C to undergo hot working, cooled rapidly, and then subjected to cold working involving single or more heat treatments at 350-850 deg.C for 5sec-12hr so as to regulate the grain size of the precipitate to <=10mu.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a copper alloy for electronic devices and a method for producing the same. conductivity, soldering is
It has improved plating properties, corrosion resistance, etc.

(Prior art) Copper alloys for electronic devices used for semiconductor lead frames, connector contacts, etc. include phosphor bronze (Cu-3n alloy), brass (Cu-Zn alloy), and nickel silver (Cu-N1 alloy).
-Zn-based alloy), etc. are used. However, brass and nickel silver have the fatal defect of stress corrosion cracking, and cannot be used in applications that involve large mechanical stress. Further, phosphor bronze is most widely used because of its excellent strength and moldability, but it has low conductivity and uses a large amount of expensive Sn. Furthermore, not only is it susceptible to peeling of soldering and 3N and 3N alloy plating, but it is also susceptible to stress corrosion cracking, although this is not the case with brass and nickel silver.

For this reason, in some applications Cu-Fe alloys, such as C1
94(Cu -2,3 wt% Fe -0,12 wt%
Zn-P alloy) (hereinafter wt% is abbreviated as %) and C195 (
Cu-1,5%Fe-0,8%Co-0,6%5n-P
alloy) is used. Although they do not have the strength of 6% 3N phosphor bronze, they have two to three times the conductivity and are not susceptible to stress corrosion cracking. However, not only is the moldability inferior, but also the plating and soldering properties are insufficient.

[Problem that the invention seeks to solve]

Recently, as electronic devices have become smaller, more highly integrated, and more sophisticated,
Copper alloys for electronic devices are now required to have high performance and can meet strong demands for reliability and economy. A copper alloy that satisfies these requirements is desired to satisfy the following properties.

(1) Both strength and electrical conductivity (thermal conductivity) can be improved.

(2) Good moldability.

(3) Corrosion resistance, especially no susceptibility to stress corrosion cracking.

(4) Soldering properties and plating properties, that is, solder joint strength and Sn
High adhesion of plating over a long period of time.

[Means for solving problems]

In view of this, as a result of various researches, the present invention has developed a copper alloy for electronic devices that satisfies the above characteristics and is used in electronic devices, such as semiconductor lead frames and connector contacts, and a method for producing the same.

That is, one of the alloys of the present invention contains 0.03 to 0.3% Zr (
:, r0.05~0.5%, Zn0.01~0.5
%, Mg, Ca, Mitsushmetal (MM), Ba
.

at least one of Sr and B from 0.0005 to 0;
05%, α content is limited to 0.0030% or less, P content is limited to 0.0030% or less, S content is limited to 0.0010% or less, and the precipitate particle size consisting of the remainder Cu and unavoidable impurities is reduced. It is characterized by having a thickness of 10μ or less.

Another alloy of the present invention contains 0.03 to 0.3% Zr, C
Contains r0.05-0.5%, Z n0.01-0.5%, Mg, Ca, Mitsushmetal (MM), Ba.

At least one of Sr and B is added in an amount of 0.0005 to 0.
0.05%, further contains Sn0.4%, and α content is 0.05%.
P content is limited to 0.0030% or less, P content is limited to 0.0030% or less, S content is limited to 0.0010% or less, and the precipitate particle size consisting of the remainder CLI and inevitable impurities is set to 10 μm or less. It is.

In addition, the production method of the present invention has Zr0.03 to 0.3%, Cr0
．． 05-0.5%, Zn0.01-0.5%,
Mg, Ca, Mitsushmetal (MM>, Ba.

At least one of Sr and B is added in an amount of 0.0005 to 0.
05%, or 3n0.4% or less, α content is 0.0030% or less, P content is 0.0030%
Hereinafter, the S content is limited to 0.0010% or less, and the remaining C
An alloy ingot consisting of u and unavoidable impurities is heated to
After heating to 0℃ and hot working, it is rapidly cooled and then heated to 350℃.
At least one heat treatment at ~850°C for 5 seconds to 12 hours
It is characterized in that it is subjected to cold working more than once to reduce the precipitate particle size to 10 μm or less.

[Effect]

The alloy of the present invention has the above composition, and in particular is an alloy in which Cr and Zr are precipitated and dispersed, and the effects of both are synergistically combined to obtain predetermined characteristics.

Also Mg, Ca, and Mitsushmetal (MM).

Ba, Br, B (hereinafter M (abbreviated as J etc.) are Cr and Zr.
It works effectively to homogenize the precipitation and dispersion of Cr, and particularly improves the efficiency of its action on Cr. However, the effects of these components are within the composition range of the alloy of the present invention, that is, Z r 0.03 to 0.3.
%, Cr 0.05-0.5%, MCI etc. is practically effective at 0.0005-0.05%, Or 0.15-0.35%, Zr 0.1-0
．． The required characteristics can be maximized at 2%. However, if each is below the lower limit, no practical effect will be obtained, and if the upper limit is exceeded, manufacturing defects or a decrease in conductivity will occur.In particular, excessive Cr and Zr will become coarse grains, which will affect moldability, plating properties, and solderability. Attaching has a harmful effect on sexuality, etc.

Zn suppresses the deterioration of the adhesion strength of solder and plating, and is within the range of the present alloy, that is, Zn0.01 to 0.5%,
It is effective desirably at 0.05 to 0.2%, less than the lower limit is ineffective, and more than the upper limit reduces moldability. Sn acts effectively within the range of the present alloy, that is, 0.4% or less, preferably in the range of 0.05 to 0.2%, improves the strength of the alloy, delays the precipitation of Cr, and facilitates hot working. Although stabilized, excess 3n reduces conductivity.

Furthermore, the reason why the α content of unavoidable impurities is limited to 0.0030% or less is that if α is contained in excess of this value, it will be detrimental to the uniform precipitation and dispersion of the alloy components and will make it easier to form coarse precipitates. This not only impedes improvement in strength, but also deteriorates plating and soldering properties, and further reduces moldability, which is harmful to precision machined parts required for electronic devices. In addition, the P content is 0.0030% or less, and the S content is 0.0030% or less.
The reason for limiting it to 0.010% or less is that if these are contained in excess, the high conductivity that is a characteristic of the alloy of the present invention will be significantly impaired, and yA will shrink at the interface with the solder, resulting in poor soldering properties. In particular, S aggregates at grain boundaries and greatly deteriorates hot workability. These impurities do not have much influence on the characteristics as long as they are within the scope of the present invention, but preferably p0.001
It is desirable that the content be 0% or less, and S'4i: 0.0005% or less.

Furthermore, in the alloy of the present invention, the precipitate particle size is 10 μm or less,
The reason why the precipitate particle size is desirably 1 μm or less is because the particle size of the precipitate greatly influences strength, plating properties, soldering properties, etc., and if the particle size exceeds the upper limit, the above-mentioned opening properties are significantly reduced.

The alloy of the present invention has the composition range described above, and properties such as strength can be optimized by the manufacturing method described above. However, the reason why the alloy ingot is heated to 840 to 950°C and hot rolled is to achieve the above-mentioned homogeneous precipitation dispersion through the process of the present invention. Heating cannot achieve homogeneous precipitation dispersion throughout the process of the present invention. Further, it is desirable that the rapid cooling after hot working be carried out quickly; if the cooling takes more than 10 minutes, homogeneous precipitation dispersion cannot be achieved. Next, quench 1350 ~
5 seconds to 12 hours at 850℃, especially 0 at 400-500℃
．． Cold working, which includes heat treatment for 5 to 5 hours or at 600 to 800°C for 10 seconds to 1 hour at least once, is applied to Zr and Cr.
This is to cause homogeneous precipitation, and applying a moderate working strain of at least 10% by cold working before heat treatment also works effectively for homogeneous precipitation.

The above manufacturing conditions are conditions for optimizing the properties of the alloy of the present invention, and it is of course possible to manufacture the alloy even outside these conditions. In addition to the above composition, the alloy of the present invention also contains, for example, a small amount of A.
1. Ni, Co.

Ti, Fe, M0. w, Ta, Nb, Hf.

Ge, Pb, As, Sb, Ga, In, Y.

Tj! , Be, Cd, B i, Se, Te, Ru.

It is also possible to use Act, ALJ, Pd, Pt, etc. in combination. In addition, in the manufacturing method of the present invention, the final finishing rate is 50
% or less, and then combined with temper annealing at 200 to 500°C, a tension leveler, a tension annealer, etc., the properties can be further improved.

〔Example〕

An alloy ingot with the composition shown in Table 1 (width 40711111, thickness 40M, length 300mm) was externally machined and then heated at 875℃ for 1
Heat for 5 minutes and make a 10. It was hot-rolled into a sheet and cooled to below 100'C by water-cooling. The rolling time was about 3 minutes, and the rising temperature was 670-700°C.

This was face-sided and cold-rolled to a thickness of 1.2 mm, then heat-treated at 450°C for 25 minutes, and then rolled to a thickness of 0.4 mm.
It was cold rolled to n and then heat treated again at 450°C for 30 minutes. This was further rolled to a thickness of 0.2m and then heated to 300°C.
The mixture was heat-treated for 15 minutes. These include tensile strength, electrical conductivity, bending formability, and corrosion resistance.

Solderability and plating properties were investigated. These results were compared to the conventional alloy C194 (Cu-2,3%Fe-0,1
2%Zn-P alloy) and 6% phosphor bronze (Cu-6%5n-
A comparison with P alloy) is shown in Table 2.

Bending formability is determined by examining the state of cracks in the bent part through a V-bending test of 90" squares with various tip radii (R), and determining the ratio (R/ The corrosion resistance was determined according to JIS C8306 (stress corrosion cracking), and the cracking time was determined by the constant load (50% of tensile strength) method in 3vol 1% N113 steam.The soldering resistance was 9 m in diameter. Connect the lead wire with eutectic solder to the middle of the
After aging at 150° C. for 600 hours, the bonding strength was determined by a pull test. The plating properties were tested by plating 5n-5%Pb alloy plating to a thickness of 7.5μ in a borofluoride bath, holding it at 105°C for 2000 hours, and then bending it 180°. The peeling was examined using a microscope.

As is clear from Tables 1 and 2, the alloy Nα1 of the present invention
-6 all have excellent properties, and even compared to conventional alloys, the strength is comparable to 6% phosphor bronze Nα13, and the conductivity is C194N.
(It turns out that it is much better than 112.

On the other hand, the solder joint strength of the comparative alloy Na8, which does not contain Zn, is significantly inferior, and the comparative alloys Nα7, which contain a large amount of Cr,
Comparative alloy Nα9, which has a high α content and a large precipitate grain size, and comparative alloy NQIO, which has a high P content, not only have poor bending workability but also poor plating properties and solder joint strength. Also Sn
It can be seen that the comparative alloy N011, which has a large content, shows a significant decrease in electrical conductivity.

〔Effect of the invention〕

As described above, according to the present invention, strength, electrical/thermal conductivity, moldability, corrosion resistance, plating properties, soldering properties, etc.
Far superior to conventional alloys, it can be used as a spring material for semiconductor lead frames, connector switches, etc. in electronic equipment.
It has remarkable industrial effects, such as increasing reliability and facilitating miniaturization, high integration, and high functionality.

Claims (3)

[Claims] (1) Zr0.03-0.3wt%, Cr0.05-0
．． 5wt%, Zn0.01-0.5wt%, Mg
, Ca, Mitsushmetal (MM), Ba, Sr, and at least one of B at 0.0005 to 0.05 wt%
Contains α content of 0.0030wt% or less, P content of 0.0030wt% or less, and S content of 0.0010wt.
% or less, and the particle size of precipitates consisting of the balance Cu and unavoidable impurities is 10 μm or less. (2) Zr0.03-0.3wt%, Cr0.05-0
．． 5wt%, Zn0.01-0.5wt%, Mg
, Ca, Mitsushmetal (MM), Ba, Sr, and at least one of B at 0.0005 to 0.05 wt%
Contains 0.4wt% or less of Sn, O_2 content of 0.0030wt% or less, and P content of 0.0030w.
t% or less, the S content is limited to 0.0010wt% or less, and the precipitate particle size consisting of the remainder Cu and unavoidable impurities is reduced to 10%.
A copper alloy for electronic devices characterized by having a thickness of μm or less. (3) Zr0.03-0.3wt%, Cr0.05-0
．． 5wt%, Zn0.01-0.5wt%, Mg
Contains 0.0005 to 0.05 wt% of at least one of Ca, Mitsushi metal (MM), Ba, Sr, and B, or contains 0.4 wt% or less of Sn, and has an O_2 content of 0.0030 wt% or less. , P content 0.003
0wt% or less, the S content is limited to 0.0010wt% or less, and the remainder is Cu and inevitable impurities.
After hot working by heating to 840 to 950°C, quenching, and then cold working including at least one heat treatment at 350 to 850°C for 5 seconds to 12 hours to reduce the precipitate particle size to 10 μm or less. A method for producing a copper alloy for electronic devices, characterized by: