Engineers have boosted the performance of 3D inductor technology by adding as much as three orders of magnitude more induction to meet the performance demands of modern electronic devices.
The microchip inductor is capable of tens of millitesla-level magnetic induction. Using fully integrated, self-rolling, magnetic, nanoparticle-filled tubes, the technology ensures a condensed magnetic field distribution and energy storage in 3D space — all while keeping the tiny footprint needed to fit on a chip.
Traditional microchip inductors are relatively large 2D spirals of wire, with each turn of the wire producing stronger inductance. In previous work, the team developed 3D inductors using 2D processing by switching to a rolled membrane paradigm, which allows for wire spiraling out of plane and is separated by an insulating thin film from turn to turn. When unrolled, the previous wire membranes were 1 millimeter long but took up 100 times less space than the traditional 2D inductors.
The wire membranes reported in this work are 10 times the length at 1 centimeter, allowing for even more turns — and higher inductance — while taking up about the same amount of chip space.
Previously, the self-rolling process was triggered and took place in a liquid solution; however, allowing the process to occur in a vapor phase provided better control to form tighter, more even rolls. Another key development in the new microchip inductors is the addition of a solid iron core. The researchers filled the already-rolled membranes with an iron oxide nanoparticle solution using a tiny dropper. Capillary pressure sucks droplets of the solution into the cores where it dries, leaving iron deposited inside the tube. This adds properties that are favorable compared to industry-standard solid cores, allowing these devices to operate at higher frequency with less performance loss.
Though a significant advance on earlier technology, the new microchip inductors still have a variety of issues to be addressed including heat dissipation. If properly addressed, the magnetic induction of the devices could be as large as hundreds to thousands of millitesla, making them useful in a wide range of applications including power electronics, magnetic resonance imaging, and communications.