Abstract Gallium amalgam alloys are investigated for lead-free microminiature interconnect materials. The applicability of amalgam interconnects is explored through basic materials characterizations, wetting, dispensing, and adhesion studies. Two amalgam compositions consisting of (65% Ga - 30% Cu - 5% Ni) and (60% Ga - 32% Cu - 8% Ni) are studied. Through the course of this work a new micro-dispensing technology was developed which leverages existing industry infrastructure. These studies show amalgams can be formed uniformly and cured to a high degree of hardness. The uncured amalgams wet the majority of surfaces encountered in electronic interconnects, which include bare copper, Cu/Ni/Au, Al/Cu/Ni/Au, Al/Ti/Pt/Au, and aluminum metallization. Microstructural analysis of the cured amalgams reveals the formation of Ga-Cu and Ga-Ni intermetallic compounds and voids. In addition, the amalgams exhibit adequate adhesion by forming relatively strong interfacial bonds with common metallization systems.
Baldwin et al. (Sun,) studied this question.