Pressureless sintering of nanosilver paste at low temperature to join large area (≥100 mm2) power chips for electronic packaging

We achieve robust bonding of large area power chip (≥100 mm2) based on pressureless sintering of silver particles at low temperature, i.e., 250 °C. The particle size of silver ranges from 0.02 to 2 µm and most organics can be evaporated rapidly from 70 °C to 180 °C. It is not necessary for metallic bond to be formed entirely by silver nanoparticles. Instead, silver microparticles also can rapidly grow up and aggregated together by atom diffusion from the silver nanoparticles. This point of view leads to a new way to bond the large area chips without additional pressure. The sintered silver joint shows high shear strength, low porosity, high thermal conductivity, and low void ratio.