Interfacial Adhesion Studies using Double Cantilever Beam Method and Shear Testing

The interfacial adhesion between two packaging materials is important to package reliability performance. This paper compares the interfacial characterization technique of hot and standard die shear tests versus the double cantilever beam (DCB) method. The study involved the interfacial adhesion of die attach material to the soldermask, the core surface of an organic substrate, and the silicon die surface. Both room temperature and heated shear tests showed a cohesive failure mode and thus presented difficulties in quantifying the interface adhesion between materials interfaces. The DCB tests resulted in a reproducible adhesive failure under mode 1 condition for the tested interfaces. The computed energy release rate G_c quantified the adhesion between the different interfaces. The package reliability of the different interfaces was assessed in FBGA packages with their failure modes correlated to the adhesion strength and failure modes of the DCB test. The DCB test is recommended as a material selection tool, to be used in conjunction with shear tests for materials or surface selection.