Precipitation in Cu-Ni-Si-Zn alloy for lead frame

The aging of Cu-Ni-Si-Zn alloy for lead frame is investigated. The results showed that the peak of hardening effect occurs after aging for about I h and the electrical conductivity increases continuously with aging times. The hardness of the alloy reached a peak at 430-460 degreesC for 2 h and electrical conductivity reached a peak at 500-550 degreesC and continuously decreased afterwards. The cold rolling prior to the aging treatment was used to increase the precipitation rate. The precipitates responsible for the age-hardening effect are disc-shaped delta-Ni2Si, which has an orthorhombic structure. (C) 2002 Elsevier Science B.V. All rights reserved.