Effect of sintering environment on silver-copper die-attach nanopaste

In this work, a silver-copper (Ag-Cu) nanopaste that designed for high-temperature die-attach applications has been reported. This nanopaste was prepared by mixing Ag and Cu nanoparticles with an organic binder system, in which the weight ratio of nanoparticles and organic binder system was fixed at 87:23. The prepared nanopaste was then sintered at 380°C with a dwell time of 30 min and ramp rate of 5°C/min. A different sintering environment, namely open air, nitrogen and argon, was employed during the sintering process, which aimed to study its effect on the physical and electrical properties of sintered Ag-Cu nanopaste. X-ray diffraction analysis detected the formation of Ag₉₇Cu₃, Ag₁Cu₉₉ and CuO compounds in the sintered nanopaste, irrespective of its sintering environment. A larger grain, revealed by scanning electron microscopy, was formed as the sintering was done in open air. The electrical study indicated that the nanopaste sintered in open air has higher electrical conductivity than other sintering environment. This study concluded that open air environment was the optimum sintering environment for Ag-Cu nanopaste.