A hybrid technology for miniaturised inductive device applications

We have fabricated two-dimensional inductive devices by integrating micropatterned magnetic foils of high permeability (µr=100000) with winding patterns realised in printed circuit boards (PCBs) and flex-foil technology. We realise relatively high inductances of 1-10 µH for transformer type devices and a sensitivity of 60 V/T at 30 kHz for fluxgate magnetic induction sensing devices. The same type of device is also used as a current sensor; here we typically find sensitivities of 10 mV/A for excitation currents of a few 100 mA. We think our technology opens the way to a new class of functional and economic sensing devices. Keywords: Planar transformer; Fluxgate sensor; Thin inductive devices; Current sensor; PCB technology; Flex-foil technology