Effects of some parameters on warpage and bump-joint stresses of COG packages

The purpose of this study is to investigate the parameters such as thermal loads, adhesive material properties and fillets, hump materials, and moisture to affect the warpage and hump-joint stresses of the COG (Chip-on-Glass) packages with ACF (Anisotropic Conductive Film). Two- and three-dimensional finite element models are employed for calculating the warpage and bump- joint stresses in tenns of such parameters. In addition, the real-time full-field Twyman-Green interferometry is used for measuring the out-of-plane deformations of the specimens and providing validation of the warpage calculated from finite element models. And Suhir´s close-form solution of a die-substrate assembly is applied for looking into insight of thermo-mechanics especially for adhesive stresses and correlated with finite element results. The results show that the fillets strongly affect the warpage of the COG specimens by changing the convex shape of warpage for those without fillets to the saddle shape for those with fillets.