Thixotropy and printability study of intense pulsed light sinterable copper paste formulations for flexible substrates

At present, most of the reported articles on IPL sintering of flexible copper paste focus mainly on the effects of IPL sintering parameters and copper powder modification methods on conductive copper patterns, which ignores the influence of thixotropy, printing and other properties that are of great concern in industrial production on the conductive copper pattern. In this article, four resin materials with distinctive mechanical properties, heat resistance, and stability are selected to develop a flexible copper paste formulation for IPL sintering. By focusing on the thixotropy and printing properties of different flexible copper pastes formulations, we found the relationship between these two properties and the performance of conductive copper patterns. The results show that thixotropy property affects the printing property, and the printing property affects the density and boundary definition of the conductive copper pattern film layer after sintering, thus affecting the conductivity. Finally, we obtained a flexible copper paste formulation suitable for IPL sintering with a printed line width of 35.47 μm, a line space of 31.55 μm, and a square resistance of 15.7 mΩ/◻.