Functional evaluation of copper in conventional wire bonding as compared to gold

Abstract

In the wire bonding process, the ever increasing gold (Au) price has created a necessity for looking at alternate materials viz., copper (Cu) for wire bonding, allowing Cu wire bonding to make a dramatic progress in recent years. The trend to shift towards Cu wire is expected to advance further in future, thus further improvement of bonding technique is indispensable as there are many challenges viz., handling of fragile pad structure, peeling, cracking below the bond pad, high oxidation rate, hardness and lower bondability of the wire bonds. In this paper, a series of experiments and characterizations (Mechanical, Electrical & SEM (Scanning Electron Microscope) has been conducted with 1mil Au and Cu wires to experimentally prove that Cu is a reliable replacement for Au in wire bonding process.