Visco-elastic-plastic behaviors of polymer-based packaging materials

The viscoelastic and viscoplastic properties of polymer films, an underfill, and a molding compound are reported in this paper. The scale effect is also investigated preliminarily. A constitutive framework from viscoelasticity to viscoplasticity is then proposed to describe the deformation characteristics. The significance of the nonlinear characteristics of polymer films and filled polymers to the selection of adhesives and determination of adhesive strength is discussed.