Effects of firing conditions on thick-film PTC thermistor characteristics in LTCC technology

Thick film resistors are prepared as pastes, which are screen-printed and fired on dielectric substrates such as alumina and widely used in hybrid circuits. The final resistor properties are mostly influenced by the firing conditions and the interactions between the elements in the substrate and the resistor. In this study, conductor – resistor (PTC thermistor) pairs of selected compositions of different chemical origin are post fired on low temperature co-fired ceramic (LTCC) and alumina substrates, the latter being considered as the reference. The effects of firing temperatures on main thermistor characteristics such as temperature coefficient of resistance (TCR), standard deviation of TCR and non- linearity are presented and discussed.