A Quick Tool for Assessing Mechanical Stresses in Adhesives between Chip & Substrate

Bonding chips to substrates is usually done at high temperatures. After adhesion the system cools down. When the adherends have different thermal properties, the intermediate adhesive becomes subject to large distortions that can cause fracture or failure. Strains and stresses in such configurations can be computed using numerical methods, but they are usually cumbersome. More desirable is an analytic algorithm giving instant albeit approximate results. An analytic formulation that computes quickly stresses within the adhesive is presented together with an example. For this example a simpler analytic formulation is found to give similar results giving support to the primary analysis.