Structural Design of Plastic IC Packages

Abstract

Recently the size of integrated circuit chips mounted in plastic packages has rapidly increased, while package dimensions have been restricted or made even smaller. This trend has increased mechanical stresses in the packages, which sometimes cause cracking in the plastic encapsulant. In this paper, plastic encapsulant stress analysis by the finite-element method (FEM), special stress-sensing test chips, and plastic resins, silicon chips and bonding wire strengths are reviewed. A fatigue life estimation technique for packages undergoing temperature cycling, quantitative evaluation of solder reflow cracking and a new adhesive strength evaluation method are also examined.