Two dierent, but equally important problems for solder joint reliability are solved. The evaluation of the dynamic stress concentration ®eld in the thin base layer of a damaged solder joint is the ®rst one. It is considered as a rectangular plate with a central macro-crack surrounded with randomly 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 information of the stress concentration ®eld in a damaged solder joint is important 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 ®nite multi-layered system. The solution of this problem may aid the creation of the modern nondestructive evaluation method (NDEM) for a high quality control of products in electronic 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 acoustic and stress concentration ®elds depend on the solder joint damage state. The character of this dependence is discussed.