JPS63307232A - Copper alloy - Google Patents

Abstract

PURPOSE:To obtain a copper alloy having high strength and high electricconductivity at low cost by specifying the compsn. consisting of Co, Si, Mg and Cu and the compositional relationships thereamong. CONSTITUTION:The copper alloy consists of, be weight, 0.4-1.6% Co, 0.1-0.5% Si, 0.01-0.5% Mg, furthermore, as needed <=1% Sn and/or <=1% Zn and the balance Cu with inevitable impurities, the weight ratio of Si/Co being regulated to 0.2-0.3. In said alloy, the content of expensive Co is decreased, and high strength, high electricconductivity and inexpensiveness are provided thereto. The alloy furthermore combines excellent heat resistance, solderability, plating adhesion, workability, etc. Said copper alloy can be obtd. by melting and casting each alloy component by atmospheric melting or vacuum melting in such a manner that they form the above-mentioned compsn., executing hot working to the obtd. ingot and, if required, thereafter subjecting it to suitable cold working and heat treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a copper alloy used for lead frame materials for semiconductor devices, connector materials for electronic devices, and the like.

[Prior art and problems to be solved by the invention] Conventionally, 42A1 was used as a lead frame material for semiconductor devices.
Iron-based alloys such as toy (Fe-42% (weight %, hereinafter simply referred to as %) Ni alloy) and CDA194 (Cu-2
, 4% Fe-0, 12% Zn-P alloy), phosphor bronze, and other copper alloys are used, but in recent years there has been a demand for higher integration, smaller size, and lower prices of semiconductor integrated circuits. Therefore, there is a need for an alloy for lead frames that has high strength, high conductivity, and is inexpensive.

However, current lead frame alloys such as those mentioned above, such as CDA194, have high conductivity but low strength;
2A11oy and phosphor bronze have high strength but low conductivity and high price.
There is no such thing that completely satisfies the condition of low price.

In addition, Cu-Co, Si-type Corson alloy containing about 2 to 4% CO and about 25% St of CO has high conductivity,
Although it is well known as an alloy that exhibits high strength, it is difficult to use it industrially as a lead frame material because it uses a relatively large amount of expensive Co.

In view of the above problems, the present invention aims to provide a copper alloy that has high strength, high conductivity, and is inexpensive.

[Means and effects for solving the problems] The copper alloy according to the present invention has a high Co content even if the Co content is low by adding only Mg or Mg and Sn and/or Zn to the well-known CLI-CO2Si alloy. It is designed to provide strength while remaining highly conductive.

That is, the first copper alloy according to the present invention has Co 0.4-1
．． 6%, SiO, 1-0.5%, Mg0.01-0.5
%, the balance being Cu and unavoidable impurities, and is characterized by having a weight ratio of 0.2 to 0.3. or,
The second copper alloy contains 0.4-1.6% Co, SiO,1
0.5%, Mg 0.01-0.5%, Sn 1% or less and/or Zn 1% or less, the balance consisting of Cu and unavoidable impurities, and the Si/Co weight ratio is 0.2-0.3. It is a feature.

Next, the reason for adding each component in the copper alloy of the present invention and the reason for limiting the composition range will be explained.

Qo improves the strength and heat resistance of the alloy by forming a compound precipitate called CO□Si together with Si.
The reason for limiting the CO content to 0.4-1.6% is that C
When the Co content is less than 0.4%, the amount of precipitated compounds is insufficient, and even if St, Mg, Sn, and Zn are added, the expected strength and heat resistance cannot be obtained. This is because if it exceeds 6%, the increase in strength tends to be saturated, and the price of the alloy increases due to the increase in Co content. Also, the reason why the Si content is set to 0.1 to 0.5% is that Si
If the content is less than 0.1%, no improvement in properties due to Si content will be obtained, and conversely, if the Si content exceeds 0.5%, the improvement in properties will be saturated, while the conductivity will decrease. be. or,
Mg is a solid solution type element, and by incorporating it into an alloy, the strength can be increased without significantly lowering the conductivity of the alloy. The reason for this is that if the Mg content is less than 0.01%, the expected strength cannot be obtained, whereas if it exceeds 0.5%, the castability and hot workability of the alloy will deteriorate. Further, 1, 'Sn and Zn in the second copper alloy are solid solution elements like Mg, and by incorporating them into the first copper alloy, the strength of the first copper alloy can be further increased. However, the reason why the Sn content is set to 1% or less is that if the Sn content exceeds 1%, the strength of the alloy increases but the conductivity decreases significantly. The following is Zn
This is because if the content exceeds 1%, the soldering properties of the alloy will deteriorate. Further, the Si/Co weight ratio is set to 0.2 to 0.
3 is because the weight ratio of St and CO in the precipitated compound of Co2Si mentioned above is 1:4.2 (#0.
24), and if Co and Si are added in a ratio that greatly deviates from this ratio, excess CO or Sl that does not participate in compound formation will become solid solution in the alloy, resulting in a significant decrease in electrical conductivity.

Next, a method for manufacturing a copper alloy according to the present invention will be explained.

First, an ingot is obtained by melting and casting to obtain the alloy composition of the present invention. At this time, ordinary atmospheric melting or vacuum melting may be used for melting. In addition, as a deoxidizing agent, Si, Mg
, Mn, etc. may be used.

The ingots obtained in this way are processed into products with the desired shape and characteristics by applying hot working as necessary and then performing a combination of appropriate cold working and heat treatment. be done.

〔Example〕

Ordinary piece-shaped electrolytic copper is melted in the atmosphere in a high-frequency melting furnace, and CO, Si, Mg + Sn, and Zn are respectively mixed into intermediate alloys with copper (Co10%, 5i15%) according to the target values.
, Mg 50%) and granular metallic tin and metallic zinc, and then cast into a mold by a normal casting method to obtain an ingot. The composition of the sample was as shown in the table below. 95 of these ingots
After heating at 0° C., a plate having a thickness of 12 mm was obtained by hot rolling. Next, the plate was solidified 11 times on each side to a thickness of 1Q mm, and then cold rolled to a thickness of 0.25 m. In the case of alloys with Co content exceeding 0.6%, this is done at 500°C for 1 hour, and in the case of Co content below 0.6%, this is done at 450°C for 1 hour.
The sample was annealed for a period of time.

As for the evaluation of the samples thus produced, the strength was determined by a tensile test, the electrical conductivity was measured by electrical conductivity (%IAC3), and the workability was evaluated by the elongation at break in the tensile test. Furthermore, heat resistance was evaluated by heating the sample in an argon atmosphere for one hour, then performing a tensile test, and evaluating the temperature at which the strength decreased by 20% as the softening point. Also, the nature of soldering is
After polishing with Scotchbrite and pickling as pretreatment, samples were immersed in a 5N-40% PB solder bath using rosin flux, and the samples were evaluated by observing whether the surface was uniformly wet. In addition, the plating adhesion was determined by soldering after performing the same pretreatment as in the sex test.
For the sample with μm Ag plating, 450'c
The evaluation was made by heating for 5 minutes and observing the presence or absence of blistering.

These results are shown in the table below along with comparative examples produced and evaluated using similar steps.

As shown in the table above, for example, Example No. 2 and Comparative Example No. 11h.
Comparing Example No. 1 and Comparative Example No. 9, the copper alloy according to the present invention has the same Co content but exhibits much higher strength than conventional Cu-Co and St-type gold alloys,
However, it is clear that the conductivities are approximately the same. Therefore, in order to obtain the same level of strength, less Co content is required, resulting in a very low price. In addition, the copper alloy according to the present invention exhibits almost the same strength and extremely high conductivity as compared to conventional high-strength alloys such as 42 Alloy and phosphor bronze, and has excellent heat resistance and solderability.

It is clear that it has both good plating adhesion and workability.

〔Effect of the invention〕

As mentioned above, the copper alloy according to the present invention has almost the same strength and conductivity as the Corson alloy, which is a conventional alloy showing high strength and high conductivity, despite having a lower Co content. . That is, it has extremely important practical advantages of high strength, high conductivity, and low cost, and has great industrial value.

Claims (2)

[Claims] (1) Co0.4-1.6% by weight, Si0.1-0.5
% by weight, Mg 0.01-0.5% by weight, remainder Cu and unavoidable impurities, Si/Co weight ratio 0.2-0.3
copper alloy. (2) Co0.4-1.6% by weight, Si0.1-0.5
A copper alloy consisting of 0.01 to 0.5% by weight of Mg, 1% or less of Sn and/or 1% or less of Zn, the remainder being Cu and unavoidable impurities, and having a Si/Co weight ratio of 0.2 to 0.3.