Thermo-mechanical modeling of thermal stress during multi-cycle intense pulsed light sintering of thick conductive wires on 3D printed dark substrate

Abstract

Due to its advantage of rapid, selective and no contact sintering, the intense pulsed light (IPL) sintering of the conductive wires is promising to simplify the hybrid printing of the fully printed electronics. However, this fast IPL sintering process is often plagued with reproducibility of the results and morphological deterioration in the product. Since exposure to high-intensity light generates temperature gradient inside samples, accurate prediction of the thermally induced residual stresses is the key issue in improving the reproducibility of the IPL sintering. In this study, we investigated how total light energy, light exposure cycle and cooling time affect the thermal stress. The finite element analysis was used to study the in-situ evolution and reduction method of thermal stresses during multi-cycle IPL sintering of thick conductive wires on 3D printed substrate, and the experiments were used to verify the analytic results. The position and sintering stage that generated the maximum thermal stress was found, then light exposure cycle and cooling time were varied to reduce the maximum thermal stress. Finally, a higher total energy combined with multi-cycle sintering method was proposed to reduce the maximum thermal stress and obtain good sintering performance. The proposed method is reliable for optimizing the pulsed light setting. This work provides an insight for optimizing the sintering methodology to improve the IPL sintering stability.