Fracture of Ag sintering bonding interface on active metal brazing substrates for power electronics

This study investigated the effects of Cu and Ag surface treatments on active metal brazing (AMB) substrates from two manufacturers (A and B) with respect to the sintered bonding characteristics of Ag paste and film. Surface roughness analysis showed that the Ag surface from manufacturer A had higher roughness than the Cu surface, whereas both Cu and Ag surfaces from manufacturer B exhibited comparable roughness values. Ag-paste bonding was highly sensitive to the surface roughness, leading to interfacial defects and void formation. By contrast, Ag-film bonding minimized the influence of surface roughness through a pressure sintering process, forming a uniform and dense interfacial structure. X-ray analysis revealed voids in the Ag-paste bond, whereas voids in the Ag-film bond were smaller than the detectable threshold. Scanning electron microscopy analysis after shear testing revealed that paste bonding resulted in substrate-side fractures, whereas film bonding resulted in chip-side fractures, indicating its higher bond strength. This study demonstrated that Ag film combined with pressure sintering can provide highly reliable bonding quality for high-power electronic module design while also offering key insights into the optimization of bonding processes.