Sintered Cu-to-Cu Joints using Cu Dendritic Structure Formed by a Dynamic Hydrogen Bubble Template with Cetyltrimethylammonium Bromide

Sintered Cu nanoparticle pastes interconnection for power devices has attracted considerable interest recently. We have developed an organic-free bonding technology using Cu dendritic structures created using the dynamic hydrogen bubble template method as an alternative to Cu nanoparticle pastes. This study investigates the bonding mechanism using Cu dendritic structure formed with and without Cetyltrimethylammonium Bromide (CTAB) as a surfactant in solution. The Cu dendritic structures were sintered under a formic acid atmosphere for 1min at 573 K and 5 MPa, with pre-treatment in formic acid. Shear strengths of 46.5 MPa and 59.8 MPa were observed for without and with CTAB for 5 s and 300 s, respectively. The surfactant of CTAB suppressed the coalescence of the bubble, leading to locally inhomogeneous ion concentration, which can result in the broad particle sizes distribution. The increased electrodeposition thickness (180 µm) and broad particle sizes distribution (170–1700 nm) improved bonding performance.