Low-temperature and low-pressure sinter-bonding for thermoelectric generator devices using Cu nanoparticle paste

For the successful commercialization of thermoelectric generator (TEG) devices, efficient thermoelectric materials and reliable electrode bonding with high thermal stability are essential. In this study, we synthesized conducting pastes based on Cu nanoparticles and developed a low-temperature and low-pressure sinter-bonding method for TEG devices using these pastes. Cu nanoparticle paste (CNP) bonding layer exhibited high shear strength up to 16.4 MPa, and low thermal contact resistance of 6.4 × 10 -7 m 2 K/W. A 4-chip Bi 2 Te 3 -based TEG device bonded using CNP achieved a power density of 0.76 W/cm 2 under a large temperature gradient of 330 °C. The CNP bonding joints retained their physical properties at temperatures up to 350 °C, thereby extending the operational temperature range of current Bi 2 Te 3 -based TEG devices. This approach overcomes the limitations of conventional Sn-based solders without relying on costly Ag nanoparticles, while achieving improved high-temperature performance of TEG devices. • Developed low-temp, low-pressure Cu nanoparticle paste sinter-bonding method • Achieved high shear strength and low thermal contact resistance in CNP bonding • Fabricated 4-chip Bi₂Te₃-based TEG devices with power density of 0.76 W/cm² • CNP joints maintained performance at temperatures up to 350 °C • Cost-effective alternative to Sn- and Ag-based bonding for thermoelectric devices