Investigation on Anisotropy Shrinkage and Conductivity of Ag Microwires Sintering Assisted by the Tamping Effect of Alternating Electric Field

Abstract

Alternating electric fields with different periods and duty ratios were applied during the sintering of Ag microwire to improve its shrinkage and conductivity. Compared with the electrostatic field with the same electric field intensity of 800 V cm−1, the shrinkage rates of Ag microwires heated in the alternating electric field with the period of 15 min, 30 min and 45 min are demonstrated to improve 1.064%, 1.864% and 1.066% at most with different duty ratios, respectively. Besides, the conductivities and grain sizes of Ag microwires heated in the alternating electric field with the period of 15 min, 30 min and 45 min are corresponding with the shrinkage rates when duty ratio changes. According to the experimental data, the optimal sintering properties of the alternating electric field with the period of 15 min, 30 min and 45 min are at the duty ratios of 9:1, 4:1 and 4:1, respectively. However, when the duty ratio is certain, the sintering properties of the alternating electric field with the period of 30 min are the best, followed by the period of 45 min, and the sintering properties of the he alternating electric field with the period of 15 min turn out to be the worst in the three alternating electric field groups. These results can be explained by the nonlinearity of the sintering process and “tamping effect” of the alternating electric field. This method may further improve the density and conductivity of Ag microwires, which are used as interconnects after sintering.