Feasibility Investigation and Characterization of Liquid Dispersant–Assisted Sintering of Silver to Bond Large‐Area Plates

Abstract

Thermal interface materials (TIMs), which can close the air gaps formed between rough component surfaces and ensure an efficient path for heat transfer, are directly related to the performance and reliability of power modules. [1,2] Conventional TIMs, such as greases, gels, and phase-change materials, are limited in high-temperature electronic packages because of their bottlenecks in heat removal and long-term reliability. [3] Silver paste, as a state-of-the-art TIM, has promising applications in hightemperature power modules due to the excellent thermal conductivity (about 200-300 W mK À1 ) and robust bonding reliability of sintered-silver bondline at elevated temperature, [4][5][6][7] and sinteredsilver packaged power modules are gradually being used in electric vehicles and power grids.The commonly used method to employ silver paste to bond different units in power modules is sintering by temperature profile. Related factors, including the sintering temperature, [8,9] heating rate, [9] sintering time, [10] sintering pressure, [11] and sintering environment, [12,13] have significant effects on the bonding quality. In addition, the bonding quality differs with bonding area too. When the bonding area is small, high bonding quality can be obtained by pressureless sintering process without predrying, and generally the bonding strength decreases with the increasing bonding area. Kim et al. [14] bonded 5 Â 5 mm GaN dies on the direct