High temperature, high frequency micro-inductors for low power DC-DC converters

The development of micro-inductors is still a challenge to improve the integration level of low power DC-DC converters. The temperature rise due to self-heating or higher ambient temperature represents a risk for system operation. Unfortunately, the use of a heat sink increases the size of the converter and it is more difficult to extract the heat flow dissipated from a smaller area. The increase in the allowable operating temperature offers a solution to achieve a high integration level while ensuring proper heat management. This paper presents the fabrication process of micro-planar inductors with magnetic layers (YIG). The influence of the temperature on the magnetic material and on the inductor performances is studied up to 280 °C. Fabricated micro-inductors are tested using a LCR meter in the 10 kHz to 110 MHz frequency range and over a large temperature range, from 30 °C to 280 °C.