Bonding Properties of Cu Paste in Low Temperature Pressureless Processes

This study suggests a newly developed pressureless type Cu sinter paste as a bonding material for power electronics. At ECTC2020, we reported on our pressure type Cu paste, but this time we will report on our newly developed pressureless type Cu paste. In this study, we evaluated both the initial bonding properties of the Cu paste and bonding properties after the reliability test. The Au or Ag metallized Si dummy die and TO-247 leadframe were used for evaluation. The bonding sample was prepared by sintering at 200 °C for 60 minutes in a formic acid atmosphere. As indicated by Scanning Acoustic Tomography (SAT) observation, die shear test, and cross-sectional observation as evaluation of the initial bonding state, the bonding state was good. The result of Thermal Cycling Test (TCT) as a reliability test demonstrated that the bonding sample maintained a good bonding state. The newly developed Cu paste can be expected to be as a bonding material for power electronics.