Fabrication of large-area interconnects by sintering of micron Ag paste

Organics are difficult to be decomposed from large-area interconnects, i.e., more than 12 mm × 12 mm, using sintered Ag nanoparticles. This is mainly due to the lack of contact with air, which leads to insufficient sintering and low shear strength. In this paper, we report robust bonding of large-area interconnects by sintering of 1-2 μm micron Ag paste. Organics could be removed rapidly from the large pores surrounded by coarse necks. At 250 °C, the content of residual organics in sintered silver joints with micron Ag paste was only 2.4%, which is 0.45 times lower than the one with nanoscale Ag paste. Roubus joints with high shear strength of 33.6 MPa were formed by coarse necks. The mechanism and morphological evolution of sintered silver joints with micron Ag paste were also studied. Interestingly, the cavities could be formed and enlarged inside the 1-2 μm Ag micron-flakes due to the increase of tensile stress around the micron-flakes. This may be the main reason for the formation of coarse necks with robust bonding.