JPH1081926A - Copper alloy for electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper alloy suitable for the lead (lead frame, etc.), terminal, connector, switch, etc., for an electronic device. SOLUTION: This alloy contains 5-42wt.% Zn, 0.1-3wt.% one or >=2 kinds among Sn, Si, Al, Mn, Zr, In, Mg, 0.005-0.5wt.% Pb and 0.005-0.5wt.% Te in total, 0.005-3wt.% one or >=2 kinds among Bi, Ca, Sr and Ba in total and the balance Cu with inevitable impurities. Since the alloy is excellent in electric and thermal conductivities, strength, hot workability, stampability, solderability, platability, etc., the alloy produces a remarkable effect when applied to a lead frame, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to leads for electronic equipment (lead frames for semiconductor devices such as ICs), terminals,
The present invention relates to a copper alloy suitable for a connector, a switch, and the like.

[0002]

2. Description of the Related Art Materials for electronic devices are required to have high electrical and thermal conductivity (conductivity), high strength, excellent plating properties of noble metals such as Ag and solder plating properties, and excellent solderability. Iron-based materials and Cu alloys have been widely used. By the way, the above-mentioned characteristics are becoming more severe in response to the miniaturization, high integration, and high density of semiconductor devices. In particular, lead pins are becoming increasingly multi-pinned, and it is required to improve not only conductivity and strength but also punching workability or etching workability. Under such circumstances, materials for electronic devices include precipitation hardening type Cu-Fe (C1940), Cu-
Copper alloys such as Ni-Si (C7025) and Cu-Cr-Sn have come to be used.

[0003]

In order to increase the electric conductivity, these copper alloys are used in which the amount of alloying elements is reduced as much as possible and the amount of impurities is kept as small as possible. For this reason, the etching property is excellent, but there is a problem that the stamping property is poor. An object of the present invention is to provide a copper alloy for electronic equipment which is excellent in thermal / electrical conductivity (conductivity), strength, hot workability, stamping property, solderability, plating property and the like.

[0004]

According to the first aspect of the present invention,
Contains 5 to 42 wt% of Zn, Sn, Si, Al, Ni, M
n, Ti, Zr, In, Mg, 0.005 to 0.5 wt% Pb,
One or more kinds of 0.005 to 0.5 wt% Te are contained in a total of 0.1 to 3 wt%, and one or more of Bi, Ca, Sr, and Ba are contained in a total of 0.005 to 3 wt%. Including
It is a copper alloy for electronic devices characterized by being composed of a balance of Cu and unavoidable impurities.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The alloying elements of the copper alloy for electronic equipment of the present invention will be described below. Zn improves the stamping property. The reason why the content is specified in the range of 5 to 42% by weight is that if the content is less than 5% by weight or more than 42% by weight, the effect of improving the stamping property cannot be sufficiently obtained. If it is less than 5 wt%, sufficient strength cannot be obtained. If it exceeds 42 wt%, conductivity,
Hot workability, solderability, and plating properties also decrease. A particularly desirable Zn content is 15-38 wt%.

[0006] Sn, Si, Al, Ni, Mn, Ti, Z
r, In, Mg, Pb, and Te improve strength, stamping property, solderability, and plating property, respectively. The reason why the content is specified to be 0.1 to 3% by weight in total is that if the content is less than 0.1% by weight, the effect cannot be sufficiently obtained, and if it exceeds 3% by weight, the hot workability and the electrical conductivity decrease. Of the above elements, Pb and T
e also improves the machinability performed when removing an oxide film after hot working. The content is specified to be 0.005 to 0.5 wt%, respectively, because if the content is less than 0.005 wt%, the effect cannot be sufficiently obtained, and if the content exceeds 0.5 wt%, the stamping property decreases.

[0007] Bi, Ca, Sr, and Ba improve the stamping property and the solderability, respectively. Their content in total
The reason why the content is specified in the range of 0.005 to 3 wt% is that if the content is less than 0.005 wt%, the effect cannot be sufficiently obtained, and if the content exceeds 3 wt%, the hot workability and the electrical conductivity are reduced. These are effective alone, but when they contain a plurality of elements, they form a compound with each other and the effect is further improved.

[0008] The copper alloy of the present invention exhibits excellent properties when used as it is. However, by plating Au, Ag, Ni, Pd, these alloys, or solder, etc., the solderability and the stress corrosion cracking resistance are improved. The properties are further improved.

[0009]

The present invention will be described below in detail with reference to examples. Alloys of various compositions shown in Tables 1 and 2 were melted and cast in a high-frequency melting furnace to obtain ingots having a thickness of 30 mm, a width of 100 mm and a length of 150 mm. Next, these ingots are hot-rolled at 980 ° C to a thickness of 10 mm, the oxide film on the surface is removed by cutting, and then cold-rolled into base plates of various thicknesses. In a heat treatment at 450 ° C for 2 hours,
It was cold rolled into a 15 mm plate.

With respect to each of the obtained sheet materials, the conductivity, tensile strength, hot workability, stamping property, solderability, and plating property were examined. Conductivity is JIS-H-0505, tensile strength is
The measurement was performed according to JIS-Z-2241. Hot workability is
Surface cracks after hot rolling were visually observed and examined. Those without cracks were indicated by ○, and those with cracks were indicated by x. The stamping property was evaluated by stamping a QFP160 pin type lead frame from a sheet material using a SKD11 mold and measuring the step of the inner lead. The smaller the step, the better the stamping property. Solderability is determined by eutectic solder (Pb-
63wt% Sn) and heated in air at 150 ° C for 1000 hours, then performed 180 ° close contact bending and bending back, and visually observed the eutectic solder joint at the bent back part and evaluated. did. A sample without peeling was indicated by "O", and a sample with peeling was indicated by "X". Plating properties are as follows: electrolytic degreasing, etching with H ₂ SO ₄ -H ₂ O ₂ solution, immersion in Ag plating bath, plating Ag 5 μm thick, then heating at 475 ° C. for 5 minutes to check for blisters It was observed and evaluated with a microscope. Those without swelling were indicated by ○, and those with swelling were indicated by ×. The results are shown in Tables 3 and 4.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

[Table 3] (Note) *: Step of inner lead, unit μm.

[0014]

[Table 4] (Note) *: Step of inner lead, unit μm.

As is clear from Tables 3 and 4,
Nos. 1 to 11 show excellent characteristics for all the survey items. No. 1 with an appropriate amount of Pb added, and an appropriate amount of Te added
In No. 5, the hot-rolled material was cut particularly well. In contrast, No. 12 of the comparative example was inferior in stamping property and reduced in strength because of a small amount of Zn. No.13 was inferior in stamping property due to the large amount of Zn, and furthermore, conductivity, hot workability, solderability, and plating property were reduced. No. 14 had a small amount of Sn, and No. 17 had a small amount of Si and Al, so that the strength, stamping properties, and solderability were all reduced. No.16 is
Since neither Bi, Ca, Sr, or Ba was contained, the stamping properties and solderability were poor. No.15 has a large amount of Sn and N
o.18 has a large amount of Ni, No.19 has a large amount of Bi, and No.20 has a large amount of Bi.
No. 21 has a large amount of Ca, No. 21 has a large amount of Sr, and No. 22 has a large amount of Ca and Ba.
, The conductivity decreased and cracking occurred during hot working. Both Nos. 23 and 24 of the prior art were inferior in stamping properties. No. 24 had low strength.

The obtained sheet material was examined for susceptibility to stress corrosion cracking according to the ASTM method (G37). As a result, it was confirmed that all were excellent in stress corrosion cracking resistance.

[0017]

As described above, the copper alloy for electronic equipment of the present invention is excellent in electric / thermal conductivity, strength, hot workability, stamping property, solderability, and plating property. High density, high integration, etc. The invention is particularly suitable for leadframes, but with terminals, connectors,
The same effect can be obtained by applying to other conductive materials such as electrodes. Therefore, an industrially remarkable effect is achieved.

Claims (1)

[Claims] 1. A method according to claim 1, wherein said Zn, Sn, Si, A
1, Ni, Mn, Ti, Zr, In, Mg, 0.005-0.
5 wt% of Pb, 0.005 to 0.5 wt% of Te, or a mixture of at least one of 0.1 to 3 wt% of Bi, Ca,
One or more of Sr and Ba in total 0.005
A copper alloy for electronic equipment, characterized by containing about 3 wt% and the balance being Cu and unavoidable impurities.