Bonding Temperature Effects of Robust Ag Sinter Joints in Air without Pressure within 10 Minutes for Use in Power Module Packaging

Bonding Temperature Effects of Robust Ag Sinter Joints in Air without Pressure within 10 Minutes for Use in Power Module Packaging

Ag sintering technologies have received great attention as it was applied to the inverter of Tesla's electric vehicle Model III. Ag sinter bonding technology has advantages in heat dissipation design as well as high-temperature stability due to the intrinsic properties of the material, so it is useful for practical use of SiC and GaN devices. This study was carried out to understand the sinter joining temperature effect on the robust Ag sintered joints in air without pressure within 10 min. Electroplated Ag finished Cu dies (3 mm × 3 mm × 2 mm) and substrates (10 mm × 10 mm × 2 mm) were introduced, respectively, and nano Ag paste was applied as a bonding material. The sinter joining process was performed without pressure in air with the bonding temperature as a variable of 175 °C, 200 °C, 225 °C, and 250 °C. As results, the bonding temperature of 175 °C caused 13.21 MPa of die shear strength, and when the bonding temperature was raised to 200 °C, the bonding strength increased by 157% to 33.99 MPa. When the bonding temperature was increased to 225 °C, the bonding strength of 46.54 MPa increased by about 37% compared to that of 200 °C, and even at a bonding temperature of 250 °C, the bonding strength exceeded 50 MPa. The bonding strength of Ag sinter joints was directly influenced by changes in the necking thickness and interfacial connection ratio. In addition, developments in the morphologies of the joint interface and porous structure have a significant effect on displacement. This study is systematically discussed on the relationship between processing temperatures and bonding strength of Ag sinter joints.