Experimental investigation and numerical modeling of the thermal behavior of a micro-heater

In micro-heater, heat flux is generated by Joule effect thanks to short electric pulses. This leads to a rapid increase of the micro-heater temperature that reaches a few hundreds degree Celsius in a few microseconds. In addition to this, the cyclic nature of the energizing signal may cause an excessive heat accumulation and hence a reduction of the device life expectancy. It is thus of utmost importance to accurately model heat transfer in the whole device. This work focuses on a 200 dots per inch printing head system which consists of a row of micro-heaters. Structure and chemical composition of a single micro-heater are determined by scanning electron microscopy coupled to an EDX analyzer (energy dispersive X-ray spectrometry). These data are used to build a two dimensional numerical model which represents a micro-heater cross-section. This model gives the spatiotemporal evolution of the temperature field which highlights clearly the thermal loading phenomenon in the micro-heaters. In parallel, electric measurements are performed during the printing process to access to the actual power supplied to the micro-heaters. Infrared thermography was used to measure the thermal response of the micro-heaters to the electrical solicitation. The comparison of experimental and numerical results shows that the numerical model correctly predicts the thermal behavior of micro-heaters.