Mechanical properties and microstructure of low temperature sintered joints using organic-free silver nanostructured film for die attachment of SiC power electronics

In this work, an organic-free silver nanostructured film (SNF) was applied to bond SiC chips and ceramic substrates, which was fabricated by ultrafast pulsed laser deposition (PLD). Unlike the commercial nano silver paste which contains 10%–30% organics, the bonding temperature of SNF could be reduced to only 180 °C, with the average shear strength of 18 MPa, ~3 times higher than the standard MIL-STD-883 K. The average shear strength of sintered joints reached 40 MPa when sintering temperature increased to 250 °C. The shear strength of joints was strongly dependent on their microstructure, especially the porosity and pore distribution of sintered layer. It can be tuned by size distribution and aggregation mode of particles in deposited SNF. Sintering mechanisms and strategies for obtaining appropriate mechanical property and porosity were discussed.