Copper alloy having bendability and stress relaxation property

Abstract

A copper alloy contains 0.01% to 1.0% of Fe, 0.01% to 0.4% of P, and 0.1% to 1.0% of Mg with the remainder being copper and inevitable impurities and has a volume fraction of dispersoids having a particle diameter exceeding 200 nm of 5% or less, in which dispersoids having a particle diameter of 200 nm or less and containing Mg and P have an average particle diameter of 5 nm or more and 50 nm or less. The copper alloy preferably has an average particle diameter of dispersoids containing Fe and P of 20 nm or less. The copper alloy has improved bendability and stress relaxation property.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention The present invention relates to copper alloys having bendability and stress relaxation property. Specifically, it relates to copper alloys suitable as raw materials for copper alloy sheets for use in semiconductor components such as IC lead frames for semiconductor devices; materials for electric / electronic components such as printed wiring boards; switch components; and mechanical components such as bus-bars, terminals, and connectors. [0002] 2. Description of the Related Art Cu—Fe—P alloys have been generally used as copper alloys for the above applications such as IC lead frames for semiconductor devices. Examples of these Cu—Fe—P alloys include a copper alloy (C19210 alloy) containing0.05% to 0.15% of Fe and0.025% to 0.040% of P and a copper alloy (CDA194 alloy) containing 2.1% to 2.6% of Fe, 0.015%to 0.15% of P, and0.05% to 0.20% of Zn. Among copper alloys, these Cu—Fe—P alloys exhibit high strength, high electrical ...

AI Technical Summary

Benefits of technology

[0017] The copper alloy can further contain 0.01 to 1.0 percent by mass of at least one of Ni and Co to further improve the bendability and the stress relaxation property.

[0018] The copper alloy can further contain 0.005 to 3.0 percent by mass of Zn for improving thermal ablation resistance of Sn plating and solder to thereby prevent thermal ablation (heat peeling). The Zn content is preferably 0.005 to 1.5 percent by mass to avoid reduction in electrical conductivity.

[0019] To improve the strength, the copper alloy can further contain 0.01 to 5.0 percent by mass of Sn. The Sn content is preferably 0.01 to 1.0 percent by mass to avoid reduction in electrical conductivity.

[0020] According to the aspect of the present invention, a Cu—Fe—P alloy is combined with Mg to have improved strength and improved stress relaxation property and to reduce coarse dispersoids having a particle diameter exceeding 200 nm.

[0021] The coarse dispersoids having a particle diameter exceeding 200 nm accelerate recrystallization in a hot environment to thereby reduce the stress relaxation property, cause breakage in deformation and promote crack propagation to thereby reduce the bendability.

[0022] To further effectively improve the bendability and the stress relaxation property by the addition of Mg in the Cu—Fe—P alloy, dispersoids containing Mg and P (Mg—P particles) should have an average particle diameter of 5 nm or more and 50 nm or less. These fine Mg—P particles prevent migration of dislocation and grain growth to thereby highly effectively improve the bendability and the stress relaxation property.

Problems solved by technology

The conventional techniques such as adjusting the alloying component in Japanese Patent No. 2977839 and reducing the areal ratio of precipitates in Japanese Unexamined Patent Application Publication No. 2002-294368 are insufficient to improve the stress relaxation property.

These techniques cannot make the alloy to have bendability simultaneously.