Influence of Cu micro/nano-particles mixture and surface roughness on the shear strength of Cu-Cu joints

With the optimal mass ratio (9/1) of 100 nm-1 μm particles, the bonding layer showed a highly dense sintering structure and was thinner than that of only 100 nm particles, the shear strength of the Cu-Cu joint was over 20 MPa even at relatively low temperature 250 °C and pressure of 4 MPa. The sawtooth structure formed between the bonding layer and the copper substrates can increase the bonding area and further promote the shear strength of joint, the optimal surface roughness of copper substrate for maximum enhanced effect was Ra = 189.9 ± 5.4 nm.