Intense pulsed light sintering of thick conductive wires on elastomeric dark substrate for hybrid 3D printing applications

Abstract

Recent developments in 3D/4D printing for functional materials and devices require embedding conductive wires within a 3D printed part. One common approach is to direct-ink-write conductive silver nanoparticle (NP) ink on a 3D printed structure and subsequently sinter the ink. Intense pulsed light (IPL) sintering is a promising choice due to its advantage of rapid sintering. Despite the extensive studies of IPL sintering metal NPs on plastic foil, its use for hybrid 3D/4D printing has not been fully explored. In this paper, we studied the multi-cycle sintering method that alternates between light exposure cycle and cooling cycle to IPL sintering silver NP ink on a widely used commercial 3D printed elastomeric dark material. We investigated how the light energy can affect the sintered conductive wire quality by varying light exposure cycle, cooling cycle and the distance from light source to the sample, with fixed multiple small pulses. Numerical analysis, in situ temperature measurements, in situ resistance measurements, and microstructure characterization results confirmed the effectiveness of the multi-cycle IPL sintering method in obtaining thick conductive wires on the light absorbing substrate. Peeling tests and electromechanical experiments were performed to evaluate the interfacial and electromechanical properties of the sintered wire. We reported the phenomenon of wrinkles on the substrate and analyzed the mechanism by using finite element method. The proposed method can be applied to other 3D printed materials with different conductive wire dimension and thus have the potential to be integrated with the printed stretchable device for hybrid 3D printing and 4D printing in the future.