Ductile Au₄Al intermetallic compound with crack resistance

The Au–Al intermetallic compounds (IMCs) were commonly regarded as brittle within wire bonding interfaces. Here the in-situ micro-pillar compression tests of Au₄Al IMCs were carried out to verify their intrinsic mechanical property. The result clearly shows that, surprisingly, the Au₄Al IMC is ductile, while the yield stress appeared to be about 1 GPa. Furthermore, upon the compression tests of Au₄Al IMC micro-pillars with initial crack, no brittle fracture was observed; instead, the plastic deformation of Au₄Al was shown via shear band. This work suggests that pristine Au₄Al IMC is ductile and crack-resistant, which provides new insights for wire bonding process and technology.