Softening-resistant copper alloy and method of forming sheet of the same

Abstract

A softening-resistant copper alloy contains Fe in an Fe content in the range of 0.01 to 4.0% by mass. The copper alloy has a cube orientation density of 50% or below and a mean grain size of 30 μm or below after being annealed at 500° C. for 1 min. A copper alloy sheet forming method of forming a copper alloy sheet comprises, in successive steps: a hot rolling process for hot-rolling a copper alloy sheet of the copper alloy according to any one of claims 1 to 4, at least two working cycles each of a cold rolling process and an annealing process, and a finish cold rolling process. Reduction ratio for each of the cold rolling processes of the working cycles is in the range of 50 to 80%, and reduction ratio for the finish cold rolling process is in the range of 30 to 85%.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a softening-resistant copper alloy having high softening resistance and a method of forming a sheet of the softening-resistant copper alloy. The softening-resistant copper alloy having high softening resistance can be effectively applied to various fields including the electric, the electronic and the mechanical field. [0003] 2. Description of the Related Art [0004] The recent progressive advancement of device miniaturization, device thinning and weight reduction of various devices including electronic devices has urged the rapid progress of the miniaturization and weight reduction of copper alloy parts including lead frames, terminals and connectors for those small, lightweight devices. [0005] For example, a copper alloy containing Fe in a small Fe content is sued widely for forming lead frames for semiconductor devices. A copper alloy designated by CDA194 excellent in strength, ele...

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Benefits of technology

[0012] The present invention has been made in view of those problems in the prior art techniques an it is an object of the present invention to provide a copper alloy suitable for the miniaturization and weight reduction of copper alloy parts for electric and electronic devices and capable of maintaining high strength even if the copper alloy is processed by a heat treatment, such as an annealing process, and a method of forming a sheet of the copper alloy.

[0016] According to the present invention, a stable copper alloy having high softening resistance can be produced by controlling cube orientation density after annealing at 500° C. for 1 min to 50% or below. Reduction of strength that occurs in the sheet of the conventional material when the sheet is treated by a heat treatment for annealing or the like can be suppressed to the least unavoidable extent. Consequently, even in a case where decrease in dimensional accuracy of parts due to residual stress induced in the parts by a stamping process or the like is expected, strength reduction due to annealing can be suppressed, decrease in dimensional accuracy can be prevented, and copper alloy parts of stable quality can be produced.

Problems solved by technology

Such a heat treatment often softens the workpiece, and the workpiece treated by the heat treatment is unable to maintain its initial mechanical strength.

However, it is impossible to achieve the miniaturization, weight reduction and improvement of softening resistance of copper alloy parts satisfactorily simply through the adjustment of the chemical composition of the copper alloy.

However, high softening resistance intended by the present invention cannot be guaranteed by the technique disclosed in Patent document 2.

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