Low-pressure micro-silver sintering with the addition of indium for high-temperature power chips attachment

Sintered silver paste is a popular material for die attachment technology in power electronics. However, using traditional nano-silver paste when fabricating sintered joints has intrinsic material problems that cannot be overcome, such as the high cost of nano-silver particles and their potential health hazards. In this study, a novel micro-silver paste was utilized for sintering and bonding to overcome the limitations of nano-silver paste. Although the micro-silver paste is an excellent candidate to replace nano-silver paste for sintering processes to reduce the potential harm to humans, the oxidation at copper substrates on both sides of the pure silver joint at 300 degrees C causes mechanical reliability issues in long-term high temperature applications. Therefore, a micro-silver paste was sintered with the addition of indium to address the Cu oxidation problem in this study. It was found that Ag-In intermetallic compounds (IMCs) formed through a transient liquid phase reaction. The results demonstrated that sintered joints comprising Ag-In IMCs and Ag-In solid solution phases could effectively resolve the oxidation issues and significantly enhance the high-temperature reliability. Furthermore, the Ag-In IMCs exhibited excellent mechanical properties, withstanding the thermal stress induced during the thermal cycling test. (C) 2021 The Author(s). Published by Elsevier B.V.

Automated summary

In this study, a novel micro-silver paste was used to address the limitations of traditional nano-silver paste for sintering processes. By adding indium to the micro-silver paste, Ag-In intermetallic compounds and Ag-In solid solution phases were formed, effectively resolving oxidation issues and enhancing high-temperature reliability. The Ag-In IMCs also exhibited excellent mechanical properties, withstanding thermal stress during thermal cycling tests.