JP2984050B2 - Highly conductive copper alloy - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a highly conductive copper alloy mainly used as a material for electronic parts such as a lead frame.

[Prior Art] 1.5 to 3.5% by weight of Fe, 0.05 to 0.3% by weight of Zn, 0.0
Copper alloy containing 05-0.05% by weight of P is a medium-strength, medium-conductivity copper alloy with a tensile strength of 50 kgf / mm2 or more and a conductivity of 60% IACS or more. It has been widely used as various conductive materials including lead frames.

In this alloy, 0.005
0.050.05% by weight of P is added, and P remaining in the alloy forms a compound precipitation phase with Fe, contributing to the improvement of material strength and heat resistance.

When this alloy is to be used as a conductive material, it is processed into a desired shape mainly by press molding or the like.

However, the press workability of this alloy is not always sufficient.In press punching, the mold is worn out by multiple processing, the processing accuracy of the molded product is reduced, burrs are generated and the cut surface is plastically deformed. This causes problems such as generation of residual stress.

[Problems to be Solved by the Invention] The present invention improves the press workability of a conventional Cu-Fe-P alloy, reduces mold wear during press work, prolongs the life of the mold, and provides a press-formed product. It is intended to reduce the residual stress based on the processing accuracy and plastic deformation of the steel.

[Means for Solving the Problems] By using the alloy according to the present invention for press working of electronic device parts such as lead frames, it is possible to reduce mold wear during press working and significantly improve the life of the mold. In addition, the processing accuracy of the press-formed product can be increased, and the residual stress of the formed product can be reduced.

That is, the first invention of the present invention relates to 1.5 to 3.5% by weight of Fe.
And 0.03 to 0.2% by weight of Zn, and the content of each of P and Si is less than 0.001% by weight, and the balance is substantially C
a highly conductive copper alloy characterized by comprising 1.5 to 3.5% by weight of Fe and 0.03 to 3.5% by weight.
0.2% by weight of Zn, and further contains one or more of Sn, Sb, Al and Mg in a total amount of 0.001 to 0.3% by weight, and the content of each of the contained P and Si is 0.001%. It is a highly conductive copper alloy characterized by being less than 10% by weight and the balance substantially consisting of Cu.

[Action] Fe precipitates finely in the copper matrix,
1.5-1.5% because it has the effect of increasing the strength and heat resistance of the alloy
3.5% by weight is contained. Here, if the content is less than 1.5% by weight, the strength and heat resistance are not sufficiently improved, and if it exceeds 3.5% by weight, a coarse Fe phase is crystallized and the plating property, bending workability and the like are reduced.

Zn has a deoxidizing effect on the molten metal during melting, and Zn is contained in the alloy.
The content of 03 to 0.3% by weight improves the weather resistance of solder plating.

Here, if the Zn content is less than 0.03% by weight, the deoxidizing effect of the molten metal and the weathering resistance of the solder are not sufficient, and if it exceeds 0.3% by weight, the conductivity is significantly reduced.
0.03 to 0.2% by weight.

Since P and Si have a deoxidizing effect on the molten metal, P and Si are widely used as an additive element of the copper alloy, and are easily mixed as impurities. However, when each content is 0.001% by weight or more, it is combined with Fe in the alloy to form a dispersed phase.

Since this compound is extremely hard, it wears the mold during press working, and reduces the life of the mold and the working accuracy of the press-formed product. Therefore, the content of each of P and Si in the alloy must be less than 0.001% by weight.

Since Sn, Sb, Al and Mg all have a deoxidizing effect and an effect of increasing the strength of the alloy, they are contained in 0.001 to 0.3% by weight.

Here, if the content is less than 0.001% by weight, the deoxidizing effect and the effect of increasing the strength are not sufficient, and if the content exceeds 0.1% by weight, the electric conductivity is remarkably reduced.
1 to 0.3% by weight.

In the production of the present alloy, ordinary atmospheric melting, atmospheric melting, and vacuum melting are used. However, in order to suppress the oxidation of the molten metal, it is desirable to perform atmospheric melting using nitrogen, argon, or the like, or vacuum melting. The obtained ingot is processed into a thin plate or a strip through hot rolling, cold rolling and intermediate annealing.

[Example] Electrolytic copper, electrolytic iron, and electrolytic zinc were weighed so as to have a predetermined composition, and were melted in an argon atmosphere using a high-frequency induction melting furnace. P, Si, Sn, Sb, Al, and Mg-added samples were prepared by adding a copper base alloy containing these elements. After the added elements are completely dissolved, the temperature of the molten metal is set to 1200 ° C,
It was cast into a 35 × 200 × 400 mm3 mold.

Table 1 shows the results of chemical analysis of each sample. Each ingot was formed into a thickness of 30 mm by facing, then hot-rolled at 950 ° C. to a thickness of 10 mm, and cooled with water to room temperature. This was chamfered to remove an oxide film, and then cold-rolled to a thickness of 2.5 mm, and then annealed at 450 ° C. for 4 hours in a nitrogen atmosphere. Further, after annealing at 450 ° C. for 2 hours at 0.5 ° C. by cold rolling, cold rolling was performed again to obtain a 0.25 mm thick sheet material.

This was subjected to strain relief annealing at 250 ° C. for 1 hour to obtain a sample.

Next, regarding the mechanical properties of each sample, a tensile test was performed using a JIS No. 5 tensile test piece, and tensile strength and elongation at break were determined.

 The electrical properties were determined by the four-terminal method.

Regarding the plating property, a sample having Ag plating of about 5 μm was annealed at 400 ° C. for 30 minutes in a nitrogen atmosphere, and the presence or absence of blisters was visually observed.

The solder plating weathering resistance was determined by annealing a sample to which Pb-Sn eutectic solder was applied in air at 150 ° C. for 1000 hours, bending it 180 °, and observing peeling.

Regarding the press formability, a 5 × 15 mm2 rectangular sample was punched a number of times using a press die of carbon tool steel SK1 annealed material. This was performed using

From the observation results, the die life was defined as the number of times of punching at which a burr of up to 20 μm occurred on the sheared surface.

 Table 2 shows the results of each test.

From both tables, the first invention alloy example Nos. 1 and 2 are all 50 kg.
It can be seen that it has a tensile strength of f / mm2 or more, a conductivity of 60% IACS or more, and a mold life of 3000 times or more. On the other hand, Comparative Alloy Example No. 7 with a small amount of Fe and Comparative Alloy Example No. 8 with a large amount of Fe are inferior in strength and plating property, respectively.

Further, the comparative alloy No. 9 containing no Zn has poor solder plating weather resistance, and the comparative alloy No. 10 containing a lot of Zn has inferior conductivity.

Further, in Comparative Alloy Nos. 11 to 13 containing Si and P, the mold life was remarkably reduced.

Also, the second invention alloy examples No. 3 to 6 to which Sn, Sb, Al, and Mg are added.
In, the strength is further improved, and the conductivity is 60% or more.

From the above test results, the alloy of the present invention is excellent in various properties required as electronic device parts materials such as conductivity, strength, plating property, solder plating weather resistance, and the die wear during press punching is small, It turns out that it is a suitable material.

[Effects of the Invention] As is clear from the above description, the alloy of the present invention has strength and strength.
It excels in characteristics required for electronic equipment parts such as lead frames, such as conductivity and heat resistance, and, unlike conventional alloys, does not contain a hard Fe compound in the alloy. Therefore, by using this alloy mainly as a material for press forming, it is possible to significantly reduce the wear of the press die, improve the life of the die, and obtain a molded product excellent in processing accuracy, residual stress and the like. it can.

Claims (2)

(57) [Claims] (1) 1.5 to 3.5% by weight of Fe and 0.01 to 0.3% by weight
A high-conductivity copper alloy comprising: Zn, wherein the content of each of P and Si is less than 0.001% by weight, and the balance substantially consisting of Cu. 2. The method according to claim 1, wherein 1.5 to 3.5% by weight of Fe and 0.01 to 0.3% by weight of Fe are used.
Containing Zn, and further contains one or more of Sn, Sb, Al, and Mg in a total amount of 0.001 to 0.3% by weight, and
A highly conductive copper alloy, wherein the content of each of P and Si is less than 0.001% by weight, and the balance substantially consists of Cu.