Non-Destructive X-Ray Orientation Mapping of Die-Attach Solder for Thermal Cycling Test

Crystallographic orientation microscopy (OM) using electron backscatter diffraction (EBSD) is sensitive to dislocation density and subgrain boundaries. However, destructive EBSD-OM cannot allow us to track dislocation multiplication, subgrain-boundary formations, and degradation of lead-free solder due to cyclic thermal stresses. In this study, we propose a non-destructive orientation mapping method for die-attach solder, which is based on three-dimensional X-ray diffraction microscopy (3DXRD). Difficulty in applying 3DXRD to plate-shaped samples like die-attach solder is overcome by developing laminographic 3DXRD. We succeed in non-destructive orientation mapping for a die-attach solder layer between a die and a direct-bonded-copper substrate subjected to a thermal cycling test. The non-destructive orientation mapping method will facilitate the development of reliable power modules by non-destructively quantitatively evaluating the degradation of die-attach lead-free solder.