ON THE THEORY OF THERMAL-STRESSES IN A THIN BONDING LAYER

Thin bonding layers made of solders or metal-filled adhesives are widely used in electronics. They are mostly responsible for the integrity and reliability of computers and other electronic devices. Major concerns are due to thermal stresses arising in the process of electronic packaging. In this article, the analytical theory of thermal stresses is constructed under some natural simplifying assumptions. The assumptions include the thermoelastic behavior of the bonded materials and thermoelastic-plastic behavior of a bonding layer, after the latter is deposited and the composite system is cooled to an operational temperature. The closed system of governing partial differential equations for thermal stresses in a thin bonding layer is derived for any in-plane shape of the layer. Some particular problems are solved in an explicit form and the implication of the solutions for the prediction of planar voids and cracks formation are discussed. (C) 1995 American Institute of Physics.