Quantitative fractography analysis of a chip crack in a Si power MOSFET

When a material breaks and a crack forms, the resulting fracture surface will, in most cases, exhibit characteristic fracture marks. Their examination and interpretation, known as fractography analysis, can deliver useful insights about crack formation and propagation. This in turn helps to identify root causes, clarify the distribution of mechanical stress in the sample, or obtain information about material properties. In most cases, fractography analysis is used qualitatively to identify the origin of crack propagation. We report on the quantitative analysis of a specific type of fracture marks, namely Wallner lines, which allows us to calculate the exact coordinates of the crack origin, along with some further characteristic parameters of crack propagation. The approach, first proposed and applied by Rabinovitch et al. [1], is extended and applied to the fragment of a silicon power MOSFET. The approach can be transferred easily to many kinds of fractures and materials where Wallner lines are observed, as it is based on the fundamental mechanism of how they are created.