Bump Design Optimization for Copper Pillar FCBGA Package

摘要

An interfacial delamination between the under bump metallurgy (UBM) and the aluminum (Al) pad was observed in a Cu pillar bump (CPB) experiment. Finite element analysis was employed to study the failure mechanism and bump design optimization. Simulation result shows that CPB sustains largest tensile stress during thermal cycling test. Larger diameter pillar can reduce this tensile stress significantly at high temperature environment and confirmed by an evaluation experiment.