Thermo mechanical Reliability of Low-temperature Low-pressure Die Bonding Using Thin Ag Flake Pastes

To develop an ultra-heat-resistant die attach technology at low temperatures, a series of Ag particle-based novel die bonding materials have been proposed. Among these candidates, the thin Ag flake paste has the gretest potential. Thin Ag flakes were mixed with alcohol as a solvent and were formulated into a paste. These Ag pastes were stencil-printed onto Cu substrates with Ag electrolytic coated finishes, and die bonding was carried out. These samples were bonded at a temperature range from 160 deg C to 200 deg C for 60 min. At 200 deg C, stable die bonding was achieved with Micro-thick and Nano-thick Ag-flake paste. In a thermal cycling test, the die bonding samples were exposed to a thermo cycling in temperature range of -40 deg C to 250 deg C for a holding time of 30 min at each peak temperature.The die bonding with Micro Ag-flake paste exhibits about higher the bonding strength than those with other Ag pastes. The die bonding with Micro Ag-flake paste kept its high strength in thermal cycling.