In traditional aerospace power modules, tin-lead solder with poor reliability is used for large-area substrate connections. In this work, sintered silver is used to join the large-area substrates. The mechanical properties, fracture mode and microstructure of large-area sintered silver joints are studied. The results show that the mechanical properties of the joints are good, and the average shear strength of the sample is 45.18 MPa, showing a cohesive failure and ductile fracture mode. No defects such as voids, cracks or delamination are found in the sintered silver bond-line. The microstructure of the bond-line is dense and uniform with a porosity of 4.82%. It is shown that the improved large-area sintered silver process requires only single printing. By increasing the heating rate to enhance the density of sintered silver and reducing sintering pressure to 2 MPa, the modified process can meet the requirements of substrate bonding in aerospace power modules.