High-performance Cu-Cu interconnects attained through air sintering of oleylamine-capped Cu nanoparticles for power electronics packaging

Cu nanoparticles exhibit excellent properties as high-temperature-resistant, conductive, heat-dissipating, and connecting materials. However, their susceptibility to oxidation poses a major challenge to the production of high-quality sintered bodies in the air, severely limiting their widespread adoption in power electronics packaging. This study presents a novel approach to the synthesis of Cu nanoparticles capped with oleylamine ligands. By employing a simple solvent-cleaning process, effective control of the density of oleylamine ligands on particle surfaces was achieved, resulting in high-performance Cu nanoparticles with both oxidation resistance and air-sintering susceptibility. Moreover, through our research, the solvent-cleaning mechanism was clarified, a model for the oleylamine ligand decomposition was developed, the air-sintering behavior of Cu nanoparticles was analyzed, and the impacts of both the sintered bodies and interfaces on the sintering performance were explained. Additionally, Cu nanoparticles subjected to 5 cleaning rounds followed by sintering at 280 degrees C and 5 MPa in air were confirmed to be able to produce the highest shear strength (49.2 +/- 3.51 MPa) and lowest resistivity (6.15 +/- 0.32 mu Omega<middle dot>cm). Based on these results, flexible capacitive pressure sensors with Cu sintered electrodes were fabricated and demonstrated a stable pressure-capacitance response over the temperature range of 25-250 degrees C. These findings underscore the impressive robustness and durability of sintered structures and the potential for high-temperature applications of oleylamine-capped Cu nanoparticles. Our study provides reliable application demonstrations for the low-cost manufacture of high-performance power electronics packaging structures that can operate in high-current-density, high-heat-flow-density, high-temperature, and high-stress environments. (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic),(sic)(sic),(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic), (sic)5(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)280 degrees C,5 MPa,(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(49.2 +/- 3.51 MPa),(sic)(sic)(6.15 +/- 0.32 mu Omega<middle dot>cm)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)25-250 degrees C(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)-(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)..