Experimental study demonstrates high sinter-bonding strength using copper composite pastes in air, highlighting potential for power module packaging.
Key Points
To evaluate the in situ reduction behavior and sinter-bonding characteristics of CuO-containing Cu flake composite pastes under pressure-assisted bonding in air.
Prepared composite pastes with Cu:CuO mass ratios ranging from 10:0 to 7:3 dispersed in a glycol-based reducing solvent.
Analyzed thermal oxidation suppression, in situ reduction kinetics, and microstructures using TG-DTA, XRD, and cross-sectional microscopy.
Conducted Cu-Cu bonding experiments under air atmosphere at 300 °C and 10 MPa to measure shear strength.
The glycol solvent suppressed Cu flake oxidation and promoted in situ reduction of CuO to Cu nanoparticles, which filled interparticle voids to improve densification.
An excessive Cu:CuO ratio of 7:3 resulted in incomplete CuO reduction, leaving residual oxide phases that degraded sinter-bonding performance.
The 8:2 Cu:CuO paste demonstrated optimal bonding, achieving a dense bond-line and a shear strength of 25.1 MPa after 5 min at 300 °C and 10 MPa.