Optimization of Intense Pulsed Light Sintering Considering Dimensions of Printed Cu Nano/Micro-paste Patterns for Printed Electronics

An intense pulsed light (IPL) was irradiated for the sintering of screen-printed copper (Cu) nano/micro-paste patterns on a polyimide substrate. The pattern widths and intervals affect the sintering behavior owing to the opto-thermal relationship during IPL irradiation. The temperature histories of the patterns during the IPL sintering process were predicted using a self-developed heat transfer simulation program. By comparing the experimental and simulation results, the tendency according to the size of the Cu pattern was confirmed. At the same IPL irradiation energy, the wider the pattern and the narrower the interval between the patterns, the higher the heat generated. To demonstrate the tendency, in situ resistance monitoring of the Cu patterns was conducted and their microscopic structures were investigated using a scanning electron microscope. Through the tendency of IPL sintering according to the widths and intervals of the Cu pattern, guidelines of IPL sintering process for electrodes with multi-size pattern were suggested: A dummy pattern was added between the existing digitizer patterns to achieve uniform sintering in all regions. When IPL sintering was conducted with the dummy patterns, the uniformly sintered line resistance could be obtained in entire areas of the digitizer pattern.