Optimization of thermal distribution in ceramics and LTCC structures applied to sensor elements

Thermal properties of Pt or RuO₂ thick‐film heaters made on alumina, aluminum nitride or low temperature co‐fired ceramics (LTCC) were compared in the first step of our work. Special holes to improve the heat distribution were included. Several heater layouts were analysed. The heat distribution was measured by an infrared camera, at different heating power. Second, the optimization of LTCC constructions was carried out. The simple structure of LTCC permitted the achievement of a high package density. It was possible to integrate a heating element made from special thick‐film ink as a buried film, inside a substrate. An important step in our technology was the making of the holes. A pattern of holes (achieved by punching or laser cutting) around the heating area permitted a changeable heat gradient. The quality of lamination and the structure of the buried elements were investigated with an ultrasonic microscope.