A quantitative model to understand the microflow-controlled sintering mechanism of metal particles at nanometer to micron scale

In this paper, the particle size effect on the sintering behaviors of Cu particles at nanometer to micron scale is explored. The results show that micron-sized particles could form obvious sintering necks at a low temperature of 260 °C, exhibiting a shear strength as high as 64 MPa. A power relation of x ∝ a0.8 between sintering neck radius (x) and particle radius (a) is discovered, and a sintering model with a quantitative relational expression of (x/a)5 = 160γδDt/3akT is proposed by considering the surface tension driven microflow process between adjacent particles to predict the growth of sintering necks. It is concluded that the sintering process of particles at nanometer to micron scale is controlled by microflow mechanism instead of diffusion mechanism. Our proposed model provides a new theoretical basis for understanding the kinetic growth mechanism of sintering necks of metal particles.