Formation of Wavy Crack in Double-Layered Ag and CuO/Ag Sintering Die Attach Assemblies Subjected to Thermal Shock Testing

This paper describes the effect of adding copper oxide (CuO) nanoparticles into silver (Ag) nano-paste on the mechanical reliability of CuO/Ag sintering die attach by means of thermal shock testing (TST). CuO nanoparticles with the diameter of 100~300 nm, which are produced by atomized heating method, are contained with 0.5 wt% in an Ag nano-paste. The CuO/Ag and pure Ag pastes are dried separately, and then dried Ag sheet is laminated onto dried CuO/Ag sheet on a Cu plate. A sintering process is conducted at 300 °C and 60 MPa for 10 min to make a die bonding assembly with a silicon carbide (SiC) die. The double-layer sintered SiC die attach assemblies (DAAs) with various thickness ratios are subjected to TST. With increasing CuO/Ag layer thickness, the delamination is suppressed. Considering crack propagation direction, the mechanism of DAAs delamination suppression is discussed based on cross sectional scanning electron microscopy (SEM) observation, finite element analysis (FEA), and mechanical property evaluation results under uniaxial tension.