LAUSR

Abstract In this study, the relationship between the composition ratio of Bi-Sn and the thermal conductivity of a hybrid bonding layer composed of Cu nanoparticles and eutectic Bi-Sn powder was investigated. The hybrid bonding layer was used to bond two Cu plates. The bonded sample was subjected to a high-temperature (225 °C) storage test for 100 h. The sample thermal conductivity was measured during the test. The large Sn mixing ratio of the Bi-Sn powder suppressed the decrease in the thermal conductivity of the hybrid bonding layer due to the high-temperature storage. This is because the high composition ratio of Sn decreased the ratio of the sintered Cu portion and increased the ratio of the alloyed Cu-Sn portion in the parent phase, which was hardly oxidized. In addition, the Sn-rich Bi-Sn powder suppressed the Bi segregation at the bonding interface, thereby enhancing Bi dispersion in the parent phase.