A New Tool for Reliability Analysis of Designs for Next-Generation Power Electronics Packages
Power electronics systems must be reliable. Once in the field, assured performance is a must. However, competitive trends towards miniaturization, decreasing cost and increasingly shorter times between new design conceptualization and product delivery place ever greater pressure on the reliability engineer. Specifically, they must be able to predict the reliability of new power electronics designs without the necessity of costly and time-consuming qualification tests. This capability is difficult, however, since it requires knowledge of power electronics, thermal engineering and materials science. Within CPES, an interdisciplinary team of scientists has recently pooled their expertise to address this challenge. As a result, an innovative new protocol has been developed to evaluate the reliability of new designs for multilayered structures required by next generation, miniaturized power electronics packages containing extremely thin, highly brittle embedded layers. The method incorporates well-established fracture mechanics and stochastics principles coupled with an understanding of the effects of different design variables on the driving forces for failure. Led by Dr. J.D.v.Wyk (CPES-VT) and Dr. M.C. Shaw (CPES Outreach partner at California Lutheran University), the approach is based on experimental measurements of both the statistical parameters of the delicate ceramic substrates and their intrinsic fracture toughness. Parametric numerical analyses are performed of the mechanical stresses that develop within the multilayers under different conditions. Analyses of both the experimental and numerical results then yield the predicted reliability of the design. As CPES continues to mature its packaging approaches, and embraces the packaging challenges of the future (for example, double-sided cooling, harsher environments, intelligent packaging for damage monitoring), this approach to the predictive design of reliability becomes increasingly essential.