Thermal Resistance Analysis of Sn Bi Solder Paste Used as Thermal Interface Material for Power Electronics Applications

Abstract

To promote heat dissipation in power electronics, we investigated the thermal conduction performance of SnBi solder paste between two Cu plates. We measured the thermal resistance of SnBi solder paste used as thermal interface material (TIM) by laser flash technique, and a thermal resistance less than 5 mm2 K/W was achieved for the SnBi TIM. The SnBi solder also showed a good reliability in terms of thermal resistance after thermal cycling, indicating that it can be a promising candidate for the TIM used for power electronics applications. In addition, we estimated the contact thermal resistance at the interface between the SnBi solder and the Cu plate with the assistance of scanning acoustic microscopy. The experimental data showed that SnBi solder paste could be a promising adhesive material used to attach power modules especially with a large size on the heat sink.