Laser sintering of thick-film PTC thermistor paste deposited by micro-pen direct-write technology

In this paper, laser sintering has been used to process thermal sensitive material deposited by micro-pen direct-write technology. Lines of thick-film PTC thermistor paste were deposited by micro-pen direct-write technology and irradiated by a continuous-wave laser with varied power density and scanning speed. Line widths, sheet resistivities and temperature coefficients of resistivity were measured as a function of laser power density, scanning speed, coating thickness and overlapped value. The mechanism of laser sintering thermistor paste was discussed. Laser sintering enabled finer thermistor lines to overcome the resolution limitation of micro-pen deposition without the use of any high temperature post processing. The thermistors exhibited excellent electrical performance and resistance tolerance equivalent to traditional oven-fired electronic paste.