Study On Preparation Technology And Properties Of Cu - Ni - Si Alloy For Lead Frame

Cu-Ni-Si alloy is a typical aging hardening alloys, the characteristics of both high strength and high electrical conductivity, compared with the currently used lead frame material is not magnetic, and thus become the ideal timber for VLSI, hasbroad application prospects, becoming the focus of people’s studies.This article prepared four alloys of Cu-1.5Ni-0.5Si, Cu-2.1Ni-0.5Si, Cu-3.0Ni-0.5Si by casting, and Cu-3.5Ni-0.5Si. Metallographic observation, Brinell hardness, conductivity measurement and EDS analysis of the microstructure and properties of the four alloys thermomechanical treatment were researched. The main conclusions are as follows:1.An added test of [Ni]/[Si] the mass concentration of the element than would significantly affect the electrical conductivity and hardness of the Cu-Ni-Si alloy, when both the mass concentration ratio between4to6, Ni, Si elements can be without surplus, less impact on the the alloy conductivity and hardness, and the strengthening effect.2. Cu Ni-1.5-0.5-Si alloy for optimum process system:after1h solid solution in900℃, then cold deformation in450-500℃aging time of1h to2h, the alloy’s best performance can be obtained. After these process, the conductivity, brinell hardness and tensile strength reached33.4-42.7%IACS,207.08-220.7N/mm2,376.32-465.75MPa.3.Microstructure and EDS analysis showed that precipitated phases in the Cu-Ni-Si alloy during aging is Ni2Si phase, with the increase of aging time and aging temperature, the precipitation of Cu-Ni-Si alloy grew up, so that the strength of the alloy is reduced and the conductivity is increased.