Assessment of Thermal Dissipation Ability of Assembled Modules Bonded by Metallic Pastes, Pb-free Solder, and Thermally Conductive Sheet

Thermal management measures greatly affect the reliability of electronic devices. A proper thermal management measure enhances the device's lifetime and prevents premature failures. A effective way to optimize thermal dissipation of assembled device is to choose suitable material to bond chip/substrate and substrate/heat sink locations. Innovative materials such as various metallic pastes and thermal interface material (TIM) sheets have been proposed as candidates for bonding. Although these proposed materials have superior thermal conductivities, their thermal dissipation abilities after assembling have not been sufficiently assessed yet. In this study, 5-layer construction samples were prepared as shown in Fig. 1. Cu paste, Ag paste, conventional Pb-free solder, or thermal conductive sheet were used to bond chip/substrate and substrate/heat sink. The temperatures of the chip surface were monitored after a fixed current flowed into the prepared samples for the designated time. As a result, samples that have metal pastes, either Cu and Ag at both chip/substrate and substrate/heat sink, showed low chip surface temperature, which means having high heat dissipation among all prepared samples.