Effects of Various Heating Rate and Sintering Temperatures on the Microstructural and Die-Shear Strength of Sintered Ag-Cu Nanopaste

Electronic devices used in high temperature applications needs to dissipate a large amount of heat and capable to withstand the high temperature. In order to ensure these electronic devices working efficiently in such extreme environment, the die-attach quality in the first level electronic packaging need to be seriously consider. Hence, nanopaste was introduced to attach a semiconductor die onto a substrate. Nanopaste is a mixture of metallic nanoparticles and organic additives (binder, surfactant, solvent). In this study, 80 wt% of Ag nanoparticles and 20 wt% of Cu nanoparticles with average diameter of 40-90 nm, and 50-60 nm, respectively, was combined with commercial V-006A binder, and ethylene glycol as surfactant. Next, the mixture was inserted in vacuum oven at 70oC. To identify the mechanical properties, two polished Cu plates (4.0 cm x 0.7 cm) was joint by stencil printing Ag-Cu nanopaste and sintered in horizontal tube furnace at various sintering temperature (380, 350, 300, 260, 230oC), dwell time of 30 min and different ramp rate (5, 10, 15, 20, 25, 30 °C/min). The bonding strength was measured by performing lap shear test using an Instron universal testing system with a crosshead speed of 0.5 mm/min. The highest bonding strength recorded was 12.77 MPa, at sintering temperature of 260oC and 25oC/min ramp rate.