Double-sided joining IGBT devices by pressureless sintering of nanosilver paste

For the double-sided assembly, thermal stress is one of the key factors that affect the reliability of the assembly. Therefore, we need to reduce thermal stresses in the double-sided assembly by optimizing size and structure. In this study, we fabricated a kind of double-sided assembly using metal tubes instead of bonding wires because the metal tube could load the higher current density than bonding wires. The IGBT device was double-sided attached by pressureless sintering of nanosilver paste with the metal tubes as a buffer. Effects of dimension of the silver tubes and as-printed bondline thickness were discussed in details in this paper. The finite-element method (FEM) was used to study the thermo-mechanical deformation of the double-sided assembly. The die-shearing tests were used to evaluate the bonding strength of double-sided assembly by pressureless sintering of nanosilver paste. It was concluded that we could double-sided attach large-area IGBT device successfully by significant lowering the thermal stress in IGBT using metal tubes.