Material Design and Process Conditions of Pressureless Sintered Silver for 200/-40 °C Thermal Cycling Reliability

Abstract:
The next generation of power semiconductor devices require lead-free, die-attach materials for practical use at high temperature operation over 175 °C. Although sintered silver is a promising candidate for replacing conventional solders, it is generally thought to require high-pressure sintering up to 30 MPa for ensuring reliability. In this work, a pressureless sintering method is introduced and it is shown that it has the same reliability as pressure sintering in thermal cycling test between –40 °C and 200 °C. Scanning acoustic tomography and cross sectional images show that the pressureless sintered silver consists of almost the same morphology as the pressure sintered one even after 1000 cycles of thermal cycling.