Intermetallic Compound Formation in Au/Al Thermosonic Wire Bonding During High Temperature Annealing at 150 °C as a Function of Wire Material

The paper is focused on the Au-Al intermetallic compound (IMC) formation and growth as well as the void formation in thermosonic wire bond ball contacts. Three different wire types were bonded on two different Al pad metallization with optimized bonding parameter, stressed by high temperature storage (NTS) conditions at 150degC up to 200 hours and investigated by light microscopy (LM), scanning electron microscopy (SEM) in addition to energy dispersive X-ray analysis (EDX). It was found that the investigated Pd-doped 2N wire exhibited both the lowest IMC growth as well as defect formation rate in comparison to the additionally investigated 4N and 4.5N wires