Mechanical reliability modeling and characterization for Package-on-Package

POP (package-on-package) integration is achieved by stacking laminate substrate packages in vertical direction and interconnecting them with solder balls. Some mechanical reliability issues were addressed through POP development. In particular, package warpage and Si delamination were dominate issue. Package warpage was characterized with FEM-modeling, Shadow Moire and viscoelastic property measurement. Substrate and mold compound optimization techniques are explained in this paper. Also, Si delamination was characterized with FEM-modeling, a digital image tool (DIT), a scratch tester and a stress senor TEG. Si surface strength was measured with the scratch tester. Si stress and displacement in the package were measured with DIT and stress senor TEG. Design optimization for Si delamination is also explained in this paper. Board level thermal cycling is also critical issue for POP. The effects of underfill material properties on thermal cyclic life performance was studied. Optimum underfill properties are presented. This paper describes POP mechanical reliability characterization with some tools.