Stress Relief of Power Module Using Sintered-Silver Die Attachment in Cylinder-Grid-Array (CGA) Pattern

To achieve thermo-mechanical stress reduction while preserving thermal dissipation efficiency, an innovative IGBT packaging architecture was proposed, implementing sintered-silver die attachment in a cylindrical grid array (CGA) pattern instead of the conventional sheet form. The effects of three critical parameters of the CGA pattern, including thickness (0.02-0.120 mm), diameter (0.5-3 mm), and spacing (0.1–2.5 mm), on the junction temperature and thermo-mechanical stress were investigated in detail. The systematic analysis was conducted using FEA simulation with ANSYS Workbench. Furthermore, an orthogonal experimental design was used, significantly reducing experiment sets from 216 to 36 (6 levels per parameter). The extreme difference analysis revealed that the CGA thickness exerted the most significant influence. Thes set #9 was concluded as the optimal parameters, i.e., thickness of 0.08 mm, diameter of 1 mm, and spacing of 1 mm. Compared to package with sintered-silver in sheet-form, the junction temperature increased moderately by 7.2% (14.1°C), but the thermo-mechanical stress of IGBT chip and sintered-silver decreased significantly by 54.5% (56.5 MPa) and 23.6% (3.7 MPa), respectively. The parametric study methodology provides an efficient framework for optimizing advanced packaging architectures under multi-physics constraints.