A Bonded Joint Analysis for Surface Mount Components

Abstract

To gain a better understanding of the stress state in surface mount joints and their design considerations, an analysis method of bonded joints is developed and consequently three parameters that govern the stress distribution are identified. The solutions are obtained in terms of trigonometric and hyperbolic functions, and then applied to a simplified surface mount device. Contrary to general belief that the surface mount joints are mainly subjected to shear, it is shown that a peel stress also exists in a joint. Especially in a short joint used to connect stiff members as in direct mounting of chips and chip carriers, the magnitude of the peel stress is far greater than the shear stress.