Effects of copper particle size on creep deformation in copper paste films

Copper paste films develop creep deformation above 200 or 250 °C similar to copper sputtered and electroplated films. We evaluate the effects of copper particle size on the creep strain rate in the paste films. As the copper particle size changed, differences in the residual stress clearly appeared above 400 °C. For small particle sizes, the compressive stress reached 0 MPa faster during heating and the tensile stress increased more slowly during cooling above 400 °C. This result indicated that the creep strain rate of copper paste films became increased when the particle size decreased.