Measurement of the deflections experienced by electronic chips during weldment

Electronic components can experience, during welding process to a circuit board, out-of-plane displacements whose magnitude may be not compatible with the welding technique tolerances to insure good bonding. Hence, this paper presents an experimental procedure based on Projection Computed-Aided Moiré (PCAM) to study the shape profile of electronic chips subjected to a thermal cycle that simulates a welding process. PCAM is an integrated system where a system of fringes is transformed via software in a continuous phase distribution from which the distorted shape of the chip can be retrieved. In the test case, a voltage stabilizer has been heated at several different temperatures so to reproduce the various conditions which may occur in the welding process. Since the measurement is carried out after that the thermal field became uniform, the deformed shape of the chip will be a quadric surface (i.e., hyperboloid). From the analysis of the chip deformed shape, it appears that the largest displacement gradients experienced by the chips tested in this study are such that good bonding of the welded assembly is however insured.