Temperature Dependence of Viscoelastic Deformation of Resin for Plastic Packaging

Abstract

The resin for plastic packaging is experimentally investigated for viscoelastic deformation under various temperature conditions. The elastic constants are represented in terms of temperature conditions. The creep compliance is formulated by a viscoelastic model of four elements. The stress and strain of the resin model during the cooling process are analyzed by the finite-element method with heat transfer analysis. The deformation of a two-layered model of the resin and material in the cooling process is compared with the experimental results. The thermal deformation is predicted well by the analyzed results. The thermal residual stresses of the resin block and the plastic packaging model in the cooling process are also analyzed. The resin block has large thermal internal stress due to the temperature gradient between the outer surface and the central part. The plastic packaging model also contains large thermal stress in the resin as well as at the interfaces among the resin, chip and lead frame.