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 & DEG;C and 250 & DEG;C for 40 h each. Properties, including Young's modulus, hardness, creep behavior, and coefficient of thermal expansion, were measured from 30 & DEG;C to 250 & DEG;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 & mu;m/m/& DEG;C to 22.69 & mu;m/m/& DEG;C, with an average value of 20.58 & mu;m/m/& DEG;C. Moreover, the hardness decreased from 4.1 GPa to 1.7 GPa following an exponential relationship with temperature. At 250 & DEG;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 & DEG;C and 250 & DEG;C, respectively.

Automated summary

To ensure optimal working conditions for next-generation power modules, it is crucial to have a comprehensive understanding of the thermo-mechanical properties of the joint layer between the chip and substrate. This study proposes a straightforward method to fabricate densified and pure Ag9In4 bulk samples, which can be a promising candidate for the joint layer. The properties of Ag9In4, including Young's modulus, hardness, creep behavior, and coefficient of thermal expansion, were measured over a temperature range of 30°C to 250°C.