A novel structure to realize crack-free plastic package during reflow soldering process-development of CSS (chip side support) package

Reports a novel structure of a plastic package without a die-pad whereby adhesion strength is improved and thermal stress reduced. The non-die-pad structure has been realized by the chip side support (CSS) method. Furthermore, this paper describes the derivation of an equation that can be used as a criterion for judging package cracking or delamination by comparing the shear strength with the shear stress. The equation for shear stress can be estimated by the finite element method.