The degradation study for QFP interconnection structure based on PCMD health index and Darveaux model

Abstract

In electronic assemblies, quad flat package (QFP) is a widely used packaging method and its interconnection structure degradation is an important field in electronic reliability research. Although degradation processes and failure modes of QFP are various, presently, there are few researching articles on the degradation regularity and mechanism under the same failure mode. In this paper, QFP degradation experiment has been carried out. Three typical QFP degradation processes and failure modes are obtained by experiment data and crack microscopic analysis. Degradation features and curves are extracted through the health index from fusion of dynamic principal component and Mahalanobis distance(PCMD). The regularity shows that there is a similar inflection point in degradation rate curves, and degradation rates are significantly different after this point. Then, according to Darveaux failure physical model, the strain energy distribution of the crack initiation and propagation area is obtained by finite element simulation. Results show that average strain energy density in crack initiation area is similar but in crack propagation area is not, resulting in crack initiation at similar time but the crack propagation rate is different.