Epoxy Resin with Metal Complex Additives for Improved Reliability of Epoxy-Copper Joint

Abstract

Delamination and cracking of the many epoxy-copper interfaces under stress is one major failure mechanism in power packaging. It has therefore become a critical issue in the upcoming wide-bandgap semiconductor era that is expecting increased power density and device miniaturization. The higher operation temperature and voltage, as well as the harsh operation environments considering humidity factors, have posed great challenges on the robustness of these joints. Under moisture attack, the covalent bond or hydrogen bond formation based mechanism, which can be assisted by coupling agents, are intrinsically susceptible to hydrolysis degradation. Coordination bonds between copper and ligands with O or N doners, on the other hand, are a notably more stable mechanism. Furthermore, the costly and limited-access substrate pre-treatments are deemed less favorable in the fast-paced assembly process. The introduction of coordination compounds in epoxy resin that can function at interfaces without being consumed by the polymer backbone remains an obstacle. To address these issues, in this work an in-formulation metal complex-based modifier for epoxy resin is reported to enhance the adhesion performance of epoxy to copper under temperature-humidity aging. The curing, thermomechanical and chemical assessments are used to provide mechanistic insights into the adhesion and moisture resistance improvement.