Weibull analysis of soldered MLC under bending load stress

A two-dimensional numerical model of MLCs is used to calculate the over all stress distribution of soldered and bent MLCs. Together with bending measurements the stress distribution leads to the Weibull parameters of three different MLC sizes. The material dependent Weibull parameters have been found to be different for each size. One possible reason under investigation are size related residual stresses due to manufacturing which are neglected in the simulation. Residual stress measurements have been carried out at the surface of three different MLC sizes near their terminations. Compressive stresses with high stress gradients were found near the terminations. These gradients may influence the accuracy of the measurement. The measured stresses are not constant from MLC size to MLC size and influences the determination of the Weibull parameters. The residual stresses influence the reliability of MLCs and should therefore be considered in future simulations. (C) 1999 Elsevier Science Limited. All rights reserved.