Unique adhesion testing and MSL modeling

An unique adhesion testing was developed, in which a corner edge of a mold compound was adhered to a lead frame on a diagonal line while making 90° rotation, in addition, mechanical loading was applied to the corner of interfacial edge between dissimilar materials in three point bend tests. The integrated stress modeling during reflow considered five types of modeling, moisture diffusion during moisture preconditioning and reflow, thermal modeling, hygro-mechanical modeling, thermo-mechanical modeling, and vapor pressure modeling for interfacial adhesion strength in three point bend tests and also interfacial delamination in packages. k1, k2, and θ were used as parameters of interfacial adhesion strengths and package delamination. The comparison of all stress integration versus thermal expansion mismatching induced thermal stress was studied for k1, k2 and θ at the interface between mold compound and lead frame. Parameters of interfacial adhesion, k1, k2 and θ, obtained from 3P bend tests were compared with delamination in packages.