Fabrication and thermo-mechanical properties of Ag9In4 intermetallic compound

To ensure optimal working conditions for the next-generation power modules, a comprehensive understanding of the thermo-mechanical properties of the joint layer between the chip and substrate is essential. The Ag9In4 intermetallic compound is a promising candidate for the joint layer; however, related material data are not available. This study proposes a straightforward method to fabricate densified and pure Ag9In4 bulk samples. Bulk Ag9In4 with less than 0.1% porosity was fabricated by pouring molten alloy into the water-cooled mold, followed by a two-step heat treatment at 520 °C and 250 °C for 40 h each. Properties, including Young's modulus, hardness, creep behavior, and coefficient of thermal expansion, were measured from 30 °C to 250 °C. As the temperature increased, the Young's modulus of Ag9In4 decreased linearly from approximately 117.9 GPa–95.9 GPa. Correspondingly, the coefficient of thermal expansion increased linearly from 19.2 μm/m/°C to 22.69 μm/m/°C, with an average value of 20.58 μm/m/°C. Moreover, the hardness decreased from 4.1 GPa to 1.7 GPa following an exponential relationship with temperature. At 250 °C, a significant creep phenomenon was detected in Ag9In4. The creep mechanism changed from dislocation climb to dislocation diffusion, with creep stress exponents of 33.1 and 10.6 at 30 °C and 250 °C, respectively. •A simple fabrication method for densified and pure Ag9In4 bulk was proposed.•Thermo-mechanical properties of the Ag9In4 intermetallic compound were studied.•Young's modulus and CTE of Ag9In4 decreased linearly as temperature increased.•Hardness exponentially decreased from 4.1 GPa to 1.7 GPa with temperature.•Creep mechanism shifted from dislocation climb to dislocation diffusion from 30 °C to 250 °C.