Microstructural Response of Highly Porous Sintered Nano-silver Particle Die Attachments to Thermomechanical Cycling

• DOI: 10.1007/s11664-023-10870-4
• Publication Date: 2024-01-05T13:03:15Z
• Authors: Pearl A. Agyakwa; Stuart Robertson; Jingru Dai; Bassem Mouawad; Zhaoxia Zhou; Changqing Liu; C. Mark Johnson
• Keywords: Equiaxed crystals; Power cycling

Abstract This paper deals with the performance of sintered nano-silver bonds used as wide-bandgap power module die attachment technology. The specifically explores fine-scale microstructures highly porous attachments under cycling to provide a deeper understanding significance porosity reliability-related microstructural parameter. Attachments prepared at 220°C using pressure 6 MPa for 1 s (parameters known generate approximately 50% from previous work) and subsequently subjected 650,000 cycles between 50°C 200°C are assessed. A correlative workflow integrating x-ray computed tomography, focused ion beam (FIB) electron backscatter diffraction (EBSD) data is applied merge meso- nanoscale features illuminate degradation mechanisms. as-sintered Ag layer has high volume heterogeneously distributed pores, consists randomly oriented equiaxed grains whose sizes vary depending on local density region sampled. Power promotes grain growth loss twin boundaries, these changes more pronounced within dense regions attachment. In contrast, copper substrate appears undergo some refinement, deformation twins visible finer-grained zones during cycling. Cracks, which appear start off layer, propagate across Ag-Cu boundary transgranularly through fine-grained little tortuosity. These observations discussed context reliability behaviour. Graphical