Evaluation of scattered wave and stress concentration field in a damaged solder joint

Two different, but equally important problems for solder joint reliability are solved. The evaluation of the dynamic stress concentration field in the thin base layer of a damaged solder joint is the first one. It is consider ed as a rectangular plate with a central macro-crack surrounded with random ly distributed microcracks, subjected to uniform time-harmonic tension. The damaged solder joint state is described by the model of Gross and Zhang [1 ] (International Journal of Solids and Structures 29, 1763-1779). The infor mation of the stress concentration field in a damaged solder joint is impor tant to understand the mechanisms in the base components of all electronic packages. The second problem is ultrasonic wave scattering in a solder joint damaged by micro-cracks, considered as a two-dimensional finite multi-layered syste m. The solution of this problem may aid the creation of the modern nondestr uctive evaluation method (NDEM) for a high quality control of products in e lectronic industry. The method of the solution of both boundary-value problems is a direct BIEM (boundary integral equation method). The numerical results obtained for a solder joint with real geometry and physical properties show how the acoust ic and stress concentration fields depend on the solder joint damage state. The character of this dependence is discussed. (C) 1999 Academic Press.