Characterization of Multiple Commercial Sintered-Silver Pastes as Die Attachment for Power Electronics Packaging: Materials, Processing, and Properties

Abstract

The low-temperature sintered-silver joining has emerged as an advanced die attachment technology for power electronics packaging. However, the industry still has great misgivings to completely adopt this technology. One of the barriers includes the confusion of different properties caused by a variety of commercial paste materials and sintering profiles. It is significant to solve this confusion by giving a conclusion and guidance after careful review, selection, characterization, comparison, and analysis of different Ag pastes and sintering profiles. This study first made a comprehensive review of commercial Ag paste materials from global suppliers and then narrowed down 12 Ag pastes from seven major suppliers, including Alpha, Henkel, Heraeus, Indium, Kyocera, Namics, and NBE Tech. Afterward, the Ag pastes were processed and characterized from micro and macro aspects. The mechanical, electrical, thermal, and thermomechanical properties were characterized and compared in terms of the formulations of the nano-Ag, micrometer-Ag, hybrid-Ag, and resin-reinforced Ag pastes, and whether the sintering profiles require pressure or not. Porosity was used to predict the relationship between micromorphology and macroproperty based on the modified Gibson-Ashby scaling law. Finally, conclusions and guidance were provided for high-temperature and high-power-density electronics packaging.