Avoiding misleading artefacts in metallurgical preparation of die attach solder joints in high power modules

• IGBT module cross-sectioning.
• Water-jet cutting.
• Preparation artefacts.

Cross-sectioning power modules, which include multiple layers made of materials with different hardness, still represents a challenge for the failure analysis of thermo-mechanical fatigue effects occurring in the solder joints of high-power devices. In this paper, a power IGBT module has been first submitted to Intermittent Operating Life test and then cross-sectioned by diamond wire sawing and by water jet cutting, respectively. The quality of the samples prepared by both techniques has been compared. Water jet cutting has been shown to be less invasive than diamond wire cutting, since it generates less preparation flaws that can turn into artefacts, which could lead to misleading analytical conclusions.