Thermo-Viscoelastic Analysis of Deflection in CSP Electronic Device Packages

Abstract

In the present paper, a deformation induced in a new bonding technology of chip-scale package (CSP) using resin encapsulation sheets is examined numerically and experimentally. Deflections after cooling from a bonding temperature are measured experimentally for various kinds of substrate and the thickness of an integrated circuit using a laser beam. In particular, a simple theory on the basis of a multilayered plate theory considering a viscoelastic property in the substrate is presented, and the thermo-viscoelastic analysis for the deflection of CSP is performed. Furthermore, the thermo-elastoplastic finite element method analysis is performed under the same temperature history. We could show that the simple formula for multilayered plates based on the thermo-viscoelatic theory can estimate fairly well the deflection of CSP in experiment.