Predictive reliability using FEA simulations of power stacked ceramic capacitors for aeronautical applications

Viscoplastic finite-element simulation was used to predict reliability of solder joints in a high temperature 4-chips stacked capacitor mounted on a PCB under temperature cycling (-55°C to +125°C, 45min ramps/60min dwells). A three-dimensional (3D) model was built considering the materials properties of a commercial component. Capacitor materials were determined by using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX). Thermomechanical properties, Anand parameters and Darveaux constant of the materials were incorporated into the simulation procedure to evaluate the mechanical strains and the variations in the plastic energy density for the high temperature solder joints of the 4-chips stacked capacitor. The number of cycles before the crack initiation in the solder joint and the number of cycles to failure have been calculated using Darveaux methodology. The obtained results showed that the maximum mechanical strains were localized at the bottom chip. It has been found that the number of cycles to failure exceeded 50,000.