Cu-Ni-Si SYSTEM ALLOY FOR ELECTRONIC MATERIALS

Abstract

An object of the present invention is to provide a Corson alloy having significantly improved characteristics, i.e. high strength and high electrical conductivity, by enhancing the effect of addition of Cr to a Cu—Ni—Si system alloy. There is provided a copper alloy for electronic materials comprising 1.0-4.5% by mass Ni, 0.50-1.2% by mass Si, 0.003-0.3% by mass Cr wherein the weight ratio of Ni to Si satisfies the expression: 3≦Ni / Si≦5.5, and the balance being Cu and incidental impurities, wherein particles of Cr—Si compounds having a size of 0.1 μm to 5 μm are dispersed in the alloy and the dispersed particles having an atomic concentration ratio of Cr to Si of 1 to 5 and a dispersion density of no more than 1×106 / mm2.

Description

FIELD OF THE INVENTION[0001]The present invention relates to precipitation hardening copper alloys, and in particular, to Cu—Ni—Si—Cr system alloys suitable for use in components for various electronic devices.BACKGROUND OF THE INVENTION[0002]Copper alloys for electronic materials used in components for various electronic devices such as lead frames, connectors, pins, terminals, relays, and switches must satisfy both high strength and high electrical conductivity (or high thermal conductivity) as basic characteristics. Recent rapid advances of high integration and reductions in size and thickness of electronic components have accelerated requirements for higher performances of copper alloys used in components for electronic devices.[0003]In recent years, in consideration of high strength and high electrical conductivity of copper alloys for electronic materials, the use of precipitation hardening copper alloys has increased, in place of traditional solid solution strengthened copper...

AI Technical Summary

Benefits of technology

[0012]An object of the present invention is to provide a Corson alloy having significantly improved characteristics, i.e. high strength and high electrical conductivity, by enhancing the effect of Cr contained in a Cu—Ni—Si system alloy.

[0013]Through extensive research for solving the problem, the inventors have accomplished an invention as described below. In a Cu—Ni—Si system alloy, the Si content is in excess of the Ni content so that nickel silicide is surely precipitated from the contained Ni in order to improve the strength, while the excess Si is combined with the contained Cr to achieve high conductivity of the alloy. The essence of the present invention is to control the excess growth of particles of Cr—Si compounds so as to prevent a shortage of Si, which combines with Ni. In particular, the inventors have found that the control of the temperature and cooling rate of the heat treatment can enhance such effects, through investigation on the preferred composition, size, and number density of particles of the Cr—Si compounds.

[0021]The present invention can provide the Corson copper alloy having significantly improved strength and electrical conductivity suitable for electronic materials due to the positive effect of Cr, which is an element contained in the alloy.

Problems solved by technology

This means the significant progress in performance is unfulfilled yet.