JPS63109132A - High-strength conductive copper alloy and its production - Google Patents

Abstract

PURPOSE:To manufacture a high-strength conductive copper alloy excellent in solderability, plating suitability, oxidation resistance, etc., by subjecting a copper alloy having a specific composition containing additive elements such as Cr, Zn, O2, S, Ag, etc., to specific hot and cold workings and heat treatment. CONSTITUTION:The copper alloy consisting of 0.01-1% Cr, 0.01-1% Zn, <=0.004% O2, <=0.002% S, further 0.01-5%, in total, of at least one kind selected from the group consisting of <=0.2% each of Ag, Be, Mg, RE, and Zr, <=0.1% each of Ca, B, In, Y, Tl, Ge, Ga, As, Te, and P, <=0.5% each of Cd, Si, Ti, Sb, and Mn, <=0.05% each of Pb, V, Nb, and Ta, <=1% each of Al, Ni, and Ca, and <=3% Fe, and the balance Cu is subjected to hot working or heat treatment at 850-1,000 deg.C and then cooled down to at least 400 deg.C at a rate of >=5 deg.C/sec. Subsequently, the above copper alloy is cold-worked at >=30% draft, which is then heat-treated at 400-550 deg.C. In this way, the copper alloy excellent is various characteristics such as mechanical strength, electric and thermal conductivities, formability, etc., can be obtained.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a copper alloy that has excellent electrical and thermal conductivity as well as mechanical strength, and a method for producing the same, and particularly relates to a copper alloy that has excellent electrical and thermal conductivity as well as mechanical strength. The present invention relates to a high-strength conductive copper alloy that has various properties necessary for use in equipment parts, and a method for producing the same.

[Conventional technology and its problems]

BACKGROUND OF THE INVENTION Copper alloys, which have excellent mechanical strength and electrical and thermal conductivity, are widely used as materials for electronic and electrical equipment parts such as semiconductor lead frames, connectors, and terminals. In recent years, as devices have become smaller and more highly integrated, copper has a conductivity close to that of pure copper.
There is an increasing demand for alloys with high mechanical strength at room and high temperatures, and this trend is particularly noticeable in semiconductor lead frame materials.

Such high-strength conductive copper alloys include Cu - Cr -
Zr-based alloys and Cu-Ti-based alloys have been known for a long time, but because they use Zr or Ti, which has a strong affinity for oxygen, the manufacturing process is complicated and costs are high.
Not used in large quantities.

On the other hand, Cu-Cr alloys are high-strength conductive alloys that can be manufactured at relatively low cost, such as Cu-0,8
The use of %Or alloy as a lead frame material was reported in Japan Electronic Materials Technology Association Bulletin vol. 1.7, N[L5, P
, 22.

In addition to mechanical strength, electrical and thermal conductivity, lead frame materials are required to have various properties such as solderability, plating properties, oxidation resistance, and moldability, but the following (a) to (e) As described in detail in 2003, the Cu-Cr alloy has many problems with respect to these properties, and there is a demand for the development of an alloy with even more excellent properties. That is, (a) the lead frame is soldered to the printed circuit board, and the bonding strength of the soldered joint must be maintained over a long period of time, but the bonding strength of the Cu-Cr alloy deteriorates significantly over time. This is considered to be a critical problem especially in surface mount type lead frames, which have been rapidly increasing in recent years.

(b) The lead frame is pre-plated with Sn or Sn-Pb at the joint part with the printed circuit board, and Ag or Au plating is applied at the wire bonding part with the semiconductor chip. The adhesion of the plating film is not very good.

(C) In semiconductor packages, P0. ~1
Bonding etc. are performed in the atmosphere at 450°C, and it is necessary that the oxide film is difficult to oxidize under such high temperature atmospheric conditions, and that the oxide film is difficult to peel off when oxidized, and in order to improve the reliability of semiconductor parts. Therefore, it is necessary to further improve the oxidation resistance of the Cu-Cr alloy.

(d) The lead frame material is required to have moldability during pressing, especially without microcracks occurring in the bent portion, but the Cu-Cr alloy does not have very good moldability.

(8)! With the increasing density of J-frames, the width and thickness of the lead portions tend to become smaller and smaller.
-A material with even higher strength than the Cr alloy is required.

[Failure to solve the problem]

The present invention has been made in view of the above points, and its purpose is to provide a high-strength conductive copper alloy with excellent properties such as solderability, plating performance, oxidation resistance, moldability, etc., and its production. The purpose is to provide a method.

That is, the high strength conductive copper alloy according to the present invention is Oro.

01-5%, Zn0.01-5%, o20. oogs or less, 5 (contains 1002% or less, and further includes Ag0.2% or less, Beα2% or less, Mg0.2% or less, Caα5% or less, cdo, 3% or less, Bα5% or less, AA5% or less,
In: 0.1 or less, Y: 0.5% or less, R, E, 0.
2 or less, Pb 0.03% or less, Ge 0.5% or less,
Gaα1 or less, Si 0.3% or less, Ti 0.3%
Below, Zr 0.2% or less, V 0.03% or less, Nb
Q, 03% or less, Ta 0.03% or less, sbα 3% or less, As 0.5% or less, Te 0.1 or less, Mn 0.3
% or less, Fe 3% or less, Ni 5% or less, Co 5% or less, po, i% or less for a total of 0.01 to 3
%, with the remainder being Cu.

The method for producing a high-strength conductive copper alloy according to the present invention includes hot working or heat treatment of the high-strength conductive copper alloy at 850 to 1000°C, and then cooling the high-strength conductive copper alloy at a rate of 5°C/sea or more to at least 1100°C. Then, after 30% or more cold working, 1F
It is characterized by heat treatment at 00 to 550°C.

[For production]

The high-strength conductive copper alloy according to the present invention is a Cu-Cr-Zn alloy in which fine precipitates of Or are uniformly dispersed, and the object of the present invention is achieved through the cooperative action of precipitated Or and solid solution Zn. This is what I did. That is, precipitated Or has a reinforcing effect with a slight decrease in conductivity, whereas ZnF
It is effective in finely and uniformly precipitating and dispersing iOr, and also improves problems in the Cu-0r alloy, such as solderability, plating performance, oxidation resistance, moldability, etc. Furthermore, the precipitated Or drastically reduces the stress corrosion cracking susceptibility of the Cu--Zn alloy. In order to realize the purpose of the present invention,
As mentioned above, it is necessary to disperse and precipitate Or finely and uniformly; if the precipitated Or becomes coarse, it not only loses its reinforcing effect, but also has harmful effects on solderability, plating properties, moldability, etc. effect.゛In the high strength conductive copper alloy according to the present invention, Or.

The reason why the content ranges of Zn, Os, and S are limited is as follows. That is, the reason why the amount of Cr is set to 0.01 to 5% is that the reinforcing effect is insufficient when α01=j is less than 5%.
If the
This is because it has a harmful effect on processability, etc., and 01-0
It is preferably within the range of 3%. The reason for setting the Zn content to 0.01 to 5% is that if α is less than 05%, the effect of improving the various properties of the Cu-Or gold alloy described above is insufficient, and if it exceeds 5%, the electrical conductivity will decrease. Therefore, α is preferably within the range of 1 to 5%. The ones who made Ol less than α00kichi were o, ooI
This is because if it exceeds &%, elongation, moldability, etc. will be reduced.

The reason why S is set to α002% or less is 0. This is because if the OO exceeds 2%, the precipitated Or becomes coarse.

The Cu-Cr-Zn alloy according to the present invention further contains Ag, B
e, Mg, Ca, Cd, B, +Al5In
, Y, Tl, R, Eo, Pb 1Co.

Ga, Sx, Ti, Zr%V, Nb, Tall
Sb, As, Te, Mn.

Fe1Ni, Co1% or less, P0. , contains at least one type of P within the range of α01 to 3% in total,
By adding these additional components, the above Cu-0
Various properties of the r-Zn alloy are further improved. The effects of these additional components and the reason for limiting the content range will be explained below.

There is almost no decrease in conductivity due to the Agti solid solution component, and Zn
It has a similar effect and improves corrosion resistance. Be has the effect of grain refinement and strengthening, and further suppresses high-temperature oxidation. Mg (a) has a desulfurization and deoxidizing effect, and has almost no decrease in electrical conductivity, and can promote the effect of Zn, but if it is contained in excess, it becomes difficult to manufacture the material. CD is a toxic element. However, there is almost no decrease in electrical conductivity, and it improves strength, heat resistance, solderability, etc.

B acts as a deoxidizing agent. M is a deoxidizing agent and is effective in preventing high-temperature oxidation, but if it is contained in excess, it lowers the electrical conductivity. In, Y%Tl, R, E, desulfurization,
It has a deoxidizing effect, is effective in making the structure finer and more homogeneous, and improves strength, heat resistance, oxidation resistance, etc. Pb has a desulfurization effect, improves heat resistance, and greatly contributes to free machinability and high-speed pressability. Ge is an element effective in suppressing coarsening of precipitated Cr. Sl is useful for improving castability and oxidation resistance. Ti and Zr improve heat resistance and have desulfurization and deoxidizing effects.

5% Nb and Ta have the effect of refining grains and making the structure uniform, and have a reinforcing effect, and also have a desulfurizing effect.

sb is particularly effective in improving the reliability of solder joints and Sn-plated parts. As, To, and Ga have the effect of refining grains and improving heat resistance, and also greatly contribute to free machinability and high-speed pressability. Mn has desulfurization and deoxidizing effects, improves oxidation resistance, and enhances the effects of Zn, such as improving solderability. Fe, Ni, Co1% or less, P0. has the effect of grain refinement and reinforcing action, and these are particularly effective components when a trace amount of P coexists. P has the effect of deoxidizing and improving hot water flow. However, if it is contained excessively, not only will the electrical conductivity decrease, but the precipitated Cr will become coarser, so it must be kept at 0.05% or less.
It is preferably within the range of 5%.

If the total amount of the above additional components is less than 0.005%, Cu −
The effect of further improving various properties of the Or-Zn alloy is insufficient, and if each is contained in excess or the total amount exceeds 3%, the electrical conductivity will decrease, the precipitated Cr will become coarser, and the workability will deteriorate. This causes inconveniences such as a decrease in
It is necessary to limit the content within the above range.

The precipitation of Or in the Cu-Or-Zn alloy is also influenced by the molding method of the Cu-Cr-Zn alloy, and in the present invention, precipitation of Or is carried out by hot working or heat treatment at 850 to 1000°C. Or is homogeneously dissolved in solid solution,
Thereafter, the Cr is maintained in a solid solution state by cooling to at least 400°C at a rate of 5°C/sec or more,
400-550 after cold working of 30% or more
The Or is finely and uniformly precipitated by heat treatment at .degree. In the present invention, the hot working or heat treatment temperature is limited to a range of 850 to 1000°C because if the temperature is less than 8500°C, Cr will not dissolve sufficiently homogeneously.
This is because if the temperature exceeds 000°C, there is a danger that part of the material will melt.

Also, the reason why the cooling rate up to 400°C was limited to at least 5°C/sec is because if it is less than 5°C/sec, some Cr will precipitate during the cooling process.
It is desirable to cool at a rate of /SθC or higher. 1 more
The reason for performing cold working of 30% or more before heat treatment at I00 to 550°C is to promote fine and uniform precipitation of Or by applying working strain, and for working of less than 50%, the above-mentioned Precipitation is not promoted sufficiently. The reason why the heat treatment temperature is limited to the range of qoo to 550°C is because if it is less than 1I00°C, sufficient precipitation will not be obtained within a practical time, and the conductivity will not be sufficiently recovered. If it is exceeded, the precipitate will become coarse. In the present invention, processing and heat treatment can be repeated as necessary, and finishing can also be achieved by processing after heat treatment. Furthermore, it is also effective to add a tension repeller, tensicon annealer-1 low-temperature annealing, etc., and by these, the Cu-O
It is possible to remove residual stress in the r-Zn alloy, improve moldability, etc.

[Example 1] The present invention will be explained in more detail below using Examples.

Various copper alloy ingots with compositions shown in Table 1 (55x100x3
00m) was heated to 920°C, hot-rolled to a thickness of 5 gourds, and then cooled with water. The hot rolling temperature is approximately 700°C, and l1
It took about 10-15 seconds to cool down to 00°C.

The hot-rolled sheet was milled, then cold-rolled to a thickness of α'+5+m, and heat-treated at 1450° C. for 25 minutes.

Next, it was cold rolled to α25 and finished by heat treatment at 280° C. for 30 minutes.

The tensile strength, elongation, electrical conductivity, bending workability, bonding strength of solder joints, adhesion of plating films, and peeling resistance of oxide films for the various copper alloy samples obtained as shown in Table 1 and above. , oxidation resistance, etc. were evaluated by the following methods, and the results are summarized in Table 2.

The bending workability was determined by bending the sample 90° using a V block with various tip radii according to JIS Z22II&.
The minimum R/l (t: plate thickness) at which no cracking occurs was determined.

The joint strength of the solder joint was determined by soldering an O wire to a sample, holding the sample at 150° C. for 300 hours, and then performing a tensile test.

The adhesion of the plating film was determined by electrolytically degreasing the sample, pickling it, plating it with 5 μm of Ag, and heating it on a hot plate at 1175° C. for 5 minutes to check for blistering.

The peeling resistance of the oxide film was determined by testing the sample at 250-1+00°C.
After heating on a hot plate to form an oxide film of each Kashihara size, a peel test was conducted using the adhesive tape method to determine the maximum thickness without peeling, that is, the adhesion scale limit. In addition, oxidation resistance was determined by determining the oxide film thickness after heating for 3 ml at 300° C. by the Cand reduction method, and comparing the oxidation rate. Note that the oxide film thickness was a CuO equivalent value.

As is clear from Table 2, Examples 1 to 15 of the present invention have strength,
It provides satisfactory values not only for elongation and conductivity, but also for bending workability, solder joint strength, plating properties, oxidation resistance, and oxide film peeling resistance.

On the other hand, the conventional example FLY 1 which does not contain Zn has poor strength and has unsatisfactory values in many practical properties such as bending workability, solder joint strength, plating properties, and oxidation resistance. In addition, Comparative Example No. 21 with insufficient Zn content has poor solder joint strength,
The oxidation resistance etc. are poor, and on the other hand, No. 22 with an excessive amount of Zn has a low electrical conductivity. Comparative Example No. 23, which had an insufficient amount of Or, had poor strength, while Comparative Example No. 1124, which had an excessive amount of Or, cracked during manufacturing and had a poor yield. Plating properties are also poor. Comparative example NIL25, which has an excessive amount of Os, has the same results as No. 2,
On the other hand, part 26 with an excessive amount of S shows cracks during manufacturing and has poor plating properties and poor plating properties. F as an additional component
Comparative example N1127 with an excessive amount of e has low conductivity and is inferior in bending workability, solder joint strength, plating properties, etc.
Comparative Example m28, in which the amount was excessive, had low conductivity and inferior solder joint strength. Comparative Example No. 1129, which has an excessive amount of Pb, has poor bending workability. Comparative Example N1130.51, which has a small content of additional components, has insufficient strength etc.

[Example 2] A copper alloy ingot having the Nal composition shown in Table 1 was
After heating to 0° C., the material was hot rolled to a thickness of 5III and then cooled with water. Thereafter, cold rolling and heat treatment were performed in the same manner as in Example 1. The obtained material was used as a comparative example N[L
The characteristics are also listed in Table 2 as Ill.

The same copper alloy ingot was heated to 900°C and then hot rolled to a thickness of 5mm. The hot rolling temperature is approximately 700°C, and 40°C
It was air cooled to 0°C in 5 minutes, ie, at a cooling rate of L7°C/sec. The above-mentioned hot-rolled sheet was thereafter cold-rolled and heat-treated in the same manner as shown in Example 1, and the resulting material was designated as Comparative Example No. 51 and its properties are also listed in Table 2.

As is clear from Table 2, all of the Comparative Examples m41.51 have insufficient strength, and 9,N[L41 has poor plating properties.

[Effects of the Invention] As described above, the copper alloy according to the present invention has excellent strength and conductivity, and has a wide range of practically essential properties such as solderability, plating performance, oxidation resistance, and moldability. It is a high-strength conductive copper alloy with excellent properties, and is particularly useful as a material for parts of electronic and electrical equipment, such as semiconductor lead frames, as well as various connectors, terminals, springs, conductors, heat sinks, etc.

Claims (3)

[Claims] (1) Cr0.01-1%, Zn0.01-1%, O_
Contains 20.004% or less, S 0.002% or less, and further contains Ag 0.2% or less, Be 0.2% or less, Mg 0.2%.
Below, Ca0.1% or less, Cd0.5% or less, B0.1
% or less, Al 1% or less, In 0.1% or less, Y 0.1%
Below, Tl is 0.1% or less, R. E. (Rare earth elements) 0.
2% or less, Pb 0.05% or less, Ge 0.1% or less, G
a0.1% or less, Si0.5% or less, Ti0.5% or less, Zr0.2% or less, V0.05% or less, Nb0.05
% or less, Ta 0.05% or less, Sb 0.5% or less, As
0.1% or less, Te 0.1% or less, Mn 0.5% or less,
Fe3% or less, Ni1% or less, Co1% or less, P0.1
% or less, the total content is 0.01 to 5%,
A high-strength conductive copper alloy characterized in that the remainder consists of Cu. (2) In the copper alloy according to claim 1, C
The contents of r and Zn are respectively Cr0.1~0.5% and Zn0.
．． A high-strength conductive copper alloy characterized by having a content of 1 to 1%. (3) Cr0.01-1%, Zn0.01-1%, O_
Contains 20.004% or less, S 0.002% or less, and further contains Ag 0.2% or less, Be 0.2% or less, Mg 0.2%.
Below, Ca0.1% or less, Cd0.5% or less, B0.1
% or less, Al 1% or less, In 0.1% or less, Y 0.1%
Below, Tl is 0.1% or less, R. E. 0.2% or less, Pb
0.05% or less, Ge 0.1% or less, Ga 0.1% or less, Si 0.5% or less, Ti 0.5% or less, Zr 0.2%
Below, V0.05% or less, Nb0.05% or less, Ta0
．． 0.05% or less, Sb 0.5% or less, As 0.1% or less,
Te 0.1% or less, Mn 0.5% or less, Fe 3% or less,
A copper alloy containing a total of 0.01 to 5% of at least one of Ni 1% or less, Co 1% or less, and P 0.1% or less, and the balance consisting of Cu, is hot worked or heated at 850 to 1000°C. After treatment, cool at a rate of 5°C/sec or more to at least 400°C, then cold work by 30% or more, and then cool to 400°C.
A method for producing a high-strength conductive copper alloy, comprising heat treatment at 550°C.