Temperature impact on inductance and resistance values of a coreless inductor (Cu/Al2O3)

This article is devoted to the inductance and resistance evolution of a coreless inductor depending on temperature. The inductors are fabricated of thin copper films deposited on an alumina substrate and characterized up to 10MHz with an impedance analyzer. Two types of measurements are carried out: after inductor annealing and in a thermal cycle (25–200°C). These measurements allow the effect of annealing and the thermal cycle on the inductance value as well as the resistance value to be determined. The inductance value depicts nearly no temperature dependence while the resistance value remains invariable when annealing up to 150°C and increases for higher temperatures due to copper oxidation and the modification of the interface and volume properties of the copper. On the other hand, in the thermal cycle, the resistance value increases with increasing temperature and then decreases in the cooling phase to regain its initial value (R=R0). The resistance evolution is due to copper resistivity evolution depending on temperature. The inductors remain functional in a high temperature environment without any deterioration. •Temperature behavior of resistance and inductance in a range from room temperature up to 200°C is investigated.•The component is not deteriorated after a healing and a cooling cycle or annealing.•Copper oxidation and modification of the interface and volume copper properties are shown after annealing.