JP3032869B2 - High strength and high conductivity copper-based alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field The present invention relates to a high-strength and high-conductivity copper-based alloy suitable as a material for electric / electronic parts represented by a lead frame and the like.

(B) Conventional technology Recently, with the development of the electronics industry, the amount of electric and electronic component materials such as lead frames has increased, and high reliability has been required in terms of characteristics, and cost has been further reduced. Is required.

Here, the lead frame is a "single frame structure that supports the IC leads during and after the manufacturing process".
The required properties are: (1) Good thermal and electrical conductivity.

One of the main functions of the lead frame is to dissipate the heat generated in the chip to prevent the Si chip from deteriorating. Good electrical conductivity is required to reduce heat generation. Here, since a proportional relationship is generally recognized between the thermal conductivity and the electrical conductivity, the evaluation is typically represented by measuring the magnitude of the electrical conductivity.

(2) High strength.

Since the lead frame supports the leads of the IC during and after the manufacturing process, sufficient strength is required for this.
The evaluation criteria are high tensile strength and proof stress,
And that the stiffness (strength of the waist) is sufficient.

(3) Have sufficient heat resistance.

It is expected that the lead frame will be heated to some extent during or after the manufacturing process. Therefore, sufficient heat resistance is required so as not to cause strength deterioration due to such a thermal load. However, in practice, if the heat-resistant temperature is too high, it is expected that there will be disadvantages in terms of cost, such as an increase in the annealing temperature during material production. Therefore, practically 350
It is sufficient if the resin is not softened by heating at a temperature of about several minutes.

(4) Good bending workability.

In most lead frames, the lead portion is bent, so that good bending workability is required. Examples of the evaluation include a VW bending test and a repeated bending test.

(5) Good plating adhesion and weather resistance.

The lead frame has Ag and Au plating on the inner leads,
Since the outer leads are often subjected to solder plating, good plating adhesion and weather resistance are required.

The lead frame is required to have the various characteristics described above.

However, conventionally, an inexpensive material having the above-mentioned various properties at the same time cannot be obtained.

(C) Disclosure of the Invention The present invention relates to a copper-based alloy having the above-mentioned various characteristics required for materials for electric / electronic parts such as lead frames,
More specifically, the present invention provides a copper-based alloy having excellent strength, elasticity, and thermal (electric) conductivity, and excellent heat resistance, bending workability, and the like.

That is, the present invention provides Co: 0.01 to 0.5 wt%, Cr: 0.005 to 0.05 wt%.
%, P: 0.01 to 0.3 wt%, with the balance being a high-strength and high-conductivity copper-based alloy consisting of Cu and unavoidable impurities.

The copper-based alloy of the present invention is disclosed in Japanese Patent Application No.
The Cr-Co-P-based high-strength high-conductivity copper-based alloy described in No. 1 is added with Cr in the above range, and is subjected to age hardening by heat treatment for solution treatment and aging, thereby further improving strength. The tensile strength is significantly improved compared to the above Cu-Co-P alloy,
A fundamental feature is that a copper-based alloy having the above-mentioned various characteristics more suitable as a melting material for electric and electronic parts such as a lead frame can be provided.

Next, the reason why the component composition range of the copper-based alloy according to the present invention is limited as described above will be described.

(1) Co: Co forms a solid solution in a copper matrix to improve strength and elasticity, and further forms a compound with P and precipitates by dispersing.
Strength and elasticity are further improved while improving heat conductivity and electric conductivity. It is also an element that contributes to improvement in heat resistance.

However, if the Co content is less than 0.01% by weight, the above effects cannot be sufficiently obtained. On the other hand, if the Co content exceeds 0.5% by weight, thermal conductivity and electrical conductivity are significantly deteriorated even in the presence of P. Becomes economically disadvantageous, for example, the annealing temperature of the steel becomes high. Therefore, the Co content is in the range of 0.01 to 0.5 wt%.

(2) Cr: When Cr is contained in an amount of less than 0.005 wt% or more than 0.05 wt%, the rate of hardening after aging is reduced, and does not sufficiently contribute to improvement in strength, thermal conductivity, and electrical conductivity. .

 Therefore, the Cr content is in the range of 0.005 to 0.05 wt%.

(3) P: P acts as a deoxidizing agent for the molten metal, forms a compound with Co, and disperses and precipitates, thereby improving strength and elasticity while improving thermal conductivity and electric conductivity.

However, if the P content is less than 0.01% by weight, the above-mentioned effects cannot be sufficiently obtained. On the other hand, if the P content exceeds 0.3% by weight, the thermal conductivity and the electrical conductivity are significantly deteriorated even in the presence of Co. It also has an adverse effect on processability. Therefore, the P content is 0.01
0.30.3 wt%.

 Next, the present invention will be described with reference to examples.

(D) Examples Example 1 Copper base alloys No. 1 to No. 1 whose chemical component values (% by weight) are shown in Table 1.
No. 6 (alloy of the present invention) and No. 7 to No. 14 (comparative alloy) were each melted using a high-frequency vacuum melting furnace, and were melted to 20 × 40 × 150
m) Cast into the soul.

After casting, each casting was rolled to a thickness of 10 mm by hot rolling at 850 ° C., followed by water quenching and pickling after hot rolling.

The hot-rolled material obtained as described above was cold-rolled to a thickness of 5 mm (a reduction of 50%), heat-treated at a temperature of 550 ° C. for 120 minutes, and quenched with water and pickled. The same heat treatment was repeated to make the plate thickness 1.25 mm.

Next, this heat-treated material was subjected to a solution treatment at a temperature of 900 ° C. for 60 minutes, and after the heat treatment, quenched with water and pickled. Next, this heat-treated material was aged at a temperature of 530 ° C. for 30 minutes, and after the heat treatment, quenched with water and pickled. Furthermore, this heat-treated material
The steel sheet was cold-rolled to a thickness of 250 mm, annealed at a temperature of 250 ° C. for 30 minutes, and then quenched with water and pickled.

Using the test materials thus obtained, test specimens were prepared, and the hardness, tensile strength, electrical conductivity, and bending workability were measured. The results are shown in Table 1.

The hardness, tensile strength and electrical conductivity were measured according to JIS-Z-2244, JIS-Z-2241 and JIS-H, respectively.
−0505.

The bending workability is measured by 90 ° W bending test (CES-M-0002-6, R
= 0.1 mm, bending in the rolling direction and the direction perpendicular to the rolling direction). The mark with good mountain surface at the center was evaluated as ○, the wrinkle was evaluated as Δ, and the crack was evaluated as ×. .

From the results shown in Table 1, the copper-based alloys of No. 1 to No. 6 according to the present invention have excellent balance of hardness, tensile strength and electric conductivity, and also have good bending workability. Therefore, it is a copper-based alloy having very excellent characteristics suitable as a material for electric / electronic parts such as a lead frame.

On the other hand, the comparative alloys No. 7 to No. 10, which do not contain Cr,
It is inferior to the copper-based alloy of the present invention in overall properties such as tensile strength.

In addition, comparative alloys No. 11 and No. 1 containing almost no Cr and Co
In 2, the conductivity is high but the hardness and strength are not enough,
Comparative alloy No. 13 which contains almost no P and comparative alloy No. 14 where the content of Cr is higher than the specified range have relatively high hardness and strength but low electrical conductivity, and both are for electrical and electronic parts such as lead frames. The material did not have sufficient properties.

Example 2 Hardness, tensile strength, electrical conductivity, heat resistance, bending workability, solder weatherability and plating of the alloy No. 3 of the present invention shown in Table 1 of Example 1 and one kind of commercially available brass (C2600EH). The adhesion was tested and measured. Table 2 shows the results.

Measurement tests for hardness, tensile strength, electrical conductivity, and bending workability are the same as those in Example 1.

In addition, the solder weather resistance is measured by plating the test piece with molten solder (Sn-40
% Pb, dip, 260 ° C x 5 seconds, using weakly active rosin flux), and hold at 150 ° C for 1000 hours. Were evaluated as ○, and those peeled were evaluated as ×.

Also, in the plating adhesion test, a test piece was coated with a 3 μm-thick Ag plating and held at 500 ° C. for 10 minutes. Was determined.

Further, the heat resistance test was performed at a temperature (holding for 30 minutes) at which the hardness of the sample became 80% of the initial hardness.

From the results shown in Table 2, the copper-based alloy of the present invention has remarkably improved electric conductivity and heat resistance as compared with brass, which is a conventional material for electric and electronic parts such as lead frames. I understand.

Therefore, it is clear that the copper-based alloy of the present invention is extremely excellent as a material for electric / electronic parts such as a lead frame as compared with conventional brass or the like.

(E) Effects of the Invention As is clear from the above examples, the copper-based alloy according to the present invention has high strength, high elasticity, high electrical conductivity, high thermal conductivity, and has good workability, solder weatherability, Although it is excellent in heat resistance and can be applied to various uses, it is a high-strength and highly-conductive copper-base alloy particularly suitable as a material for electric and electronic parts such as lead frames.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI C22F 1/00 661 C22F 1/00 661A 680 680 (72) Inventor Mitsuhiro Kosaka 277-1 Tobukicho, Hachioji-shi, Tokyo Room 114 (56) References JP-A-56-90946 (JP, A) JP-A-59-193233 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C22C 9/00-9/10 C22F 1/00-1/08 H01L 23/48

Claims (1)

(57) [Claims] (1) Co: 0.01 to 0.5 wt% Cr: 0.005 to 0.05 wt% P: 0.01 to 0.3 wt% The balance consists of Cu and unavoidable impurities, and is subjected to cold working immediately after the solution treatment. Copper alloy gold material that has been subjected to aging treatment without hardness: hardness: 143 HV or more, tensile strength: 45.
A high-strength, high-conductivity copper-based alloy characterized by having an electrical conductivity of at least 8 kgf / mm ² and an electrical conductivity of at least 67.8% IACS.