Cu-Ni-Si-Co-Cr System Alloy for Electronic Materials

Abstract

The problem to be solved by the present invention is to provide a significant improvement in the properties in Cu—Ni—Co—Si alloy by adding Cr, i.e., to provide Corson alloys having high strength and high electrical conductivity. There is provided a copper alloy for electronic materials comprising 1.0 to 4.5 mass % of Ni, 0.50 to 1.2 mass % of Si, 0.1 to 2.5 mass % of Co, 0.003 to 0.3 mass % of Cr, with the balance being Cu and unavoidable impurities, the mass concentration ratio of the total mass of Ni and Co to Si ([Ni+Co] / Si ratio) satisfies the formula: 4≦[Ni+Co] / Si≦5, and with regard to Cr—Si compound whose size is 0.1 to 5 μm dispersed in the material, atomic concentration ratio of Cr to Si in the dispersed particle is 1-5, and area dispersion density thereof is more than 1×104 / mm2, and not more than 1×106 / mm2.

Description

TECHNICAL FIELD[0001]The present invention relates to precipitation hardening copper alloys, in particular, to Cu—Ni—Si—Co—Cr system alloys suitable for use in a variety of electronic components.BACKGROUND ART[0002]A copper alloy for electronic materials that are used in a lead frame, connector, pin, terminal, relay, switch, and various other electronic components is required to satisfy both high strength and high electrical conductivity (or thermal conductivity) as basic characteristics. In recent years, as high integration and reduction in size and thickness of an electronic component have been rapidly advancing, requirements for copper alloys used in these electronic components have been increasingly becoming severe.[0003]Recently, because of considerations related to high strength and high electrical conductivity, the amount in which precipitation-hardened copper alloys are used has been increasing, replacing conventional solid-solution strengthened copper alloys typified by pho...

AI Technical Summary

Benefits of technology

[0012]Patent Document 2 describes that controlling the area number density and size of Cr—Si compounds improves the working properties for etching and press-punching. However, in this Document, Ni is not added, and therefore, it is merely required to consider the conditions for preparing Cr—Si without considering formation of Ni—Si compounds and Co—Si compounds. Therefore, in this Document, it is not discussed how Cr—Si compounds should be controlled in Cu—Ni—Si—Co—Cr system alloy.

[0014]The present inventors conducted thoroughgoing research in order to solve the above-described problems, and have found the following inventions. The present invention provides Cu—Ni—Si—Co—Cr system alloy in which Si is in excess of Ni and Co to ensure the precipitation of Ni silicide in the corresponding amount of added Ni and Co silicide in the corresponding amount of added Co for increasing the strength, while the excessive Si forms compound with added Cr for obtaining high electric conductivity. The important point of the present invention is to control the growth of the compound from Cr and Si, in order to prevent the shortage of Si, which is to be combined with Ni and Co, by overgrowth of Cr—Si compound. Specifically, the present inventors turned our attention to the composition and size of the Cr—Si compound and area number density thereof, and thus, found that the effect can be increased by controlling the temperature during the heat treatment and rate of cooling.

Problems solved by technology

In recent years, as high integration and reduction in size and thickness of an electronic component have been rapidly advancing, requirements for copper alloys used in these electronic components have been increasingly becoming severe.