Inspection Techniques Using Scanning Acoustic Microscopy for Silver Sintering Applications in Power Electronic Modules

This work presents a practical perspective to Scanning Acoustic Microscopy (SAM) for Ag-sintering applications in power electronic modules and devices. It aims to present typical challenges to consider whilst performing C-SAM for inspecting and analysing microstructures within power electronic devices, with emphasis on silver-sintered interconnects. The study presents a vast number of acoustic images (discrete devices in TO-247 packages, power modules, and also custom samples of substrates and devices), where several defects are identified, including voids, cracks, and delamination. Challenges for Ag-sintered layers inspection related to advanced surface finishes are also revealed and discussed in detail. The suitability of C-SAM for inspecting small and large areas of Ag-sintered interfaces is discussed, and showcased with custom samples, and a commercial power module.