Bonding and High-Temperature Storage Performance of Die Attachment with Ag Paste Sintering on Bare Direct Bonding Aluminum (DBA) Substrate
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Sintering Ag particles for connection of power devices is a hot topic due to the superior thermal and electrical properties of Ag to conventional solder paste. However, there are still some dilemmas for the sintering Ag particles such as high cost of nano Ag particles, requirements of pressure and surface metallization. In this work, we realized a robust die attachment on bare DBA substrate with sintering micron Ag flake particles. The bonding strength of die attachment can reach about 35 MPa under pressureless, atmospheric, and 200 °C sintering condition. By analysis the structure of sintered Ag particles, we found the micron flakes can be sintered into a uniform porous structure as low as 200 °C. The sintered die attachment structure shows a imitate attachment to the bare DBA substrate according to TEM observations of bonding interface. The high-temperature storage results indicate this die attachment has excellent thermal reliability that no significant degradation occurred even after 1000 h aging at 250 °C.
KeywordsAg paste sintering Direct bonding aluminum (DBA) Al–Ag bonding High-temperature storage
This work was supported by the JST Advanced Low Carbon Technology Research and Development Program (ALCA) project “Development of a high-frequency GaN power module package technology” (Grant No. JPMJAL1610). The author acknowledges the financial support from the Ministry of Education, Science and Culture of Japan for his research in Osaka University, and is also thankful to the Comprehensive Analysis Center of Osaka University for use of TEM, Daicel Company in Japan for providing the solvent, and the Network Joint Research Centre for Materials and Devices, Dynamic Alliance for Open Innovation Bridging Human, Environment and Materials.