Fabrication, simulation, and characterization of planar inductors

A planar inductor with excellent magnetic characteristics was successfully prepared by screen printing high solid content iron-based alloy magnetic pastes onto copper-clad laminates (CCL). The sample was then cold-isostatic pressed (CIP) to increase the packing density. To solve the problems of low electrical resistivity and low power handling capability of alloy powders for power inductor applications, an epoxy resin vehicle was added to form an insulating layer on top of the iron-based alloy powder surfaces and distribution gaps between the alloy powders. A central column was formed by punching in the center of the planar inductor and filled with magnetic paste to increase the inductance, magnetic flux channeling, and storage energy. A planar inductor 8.5 mm x 7.0 mmx 0.4 mm in size with an inductance value of about 2.7 mu H at 1 MHz, a quality factor of 10-13, and inductance decline rate of about 5% at a DC bias of 2.5 A can be successfully prepared using the proposed method. A 3D electromagnetic field finite element analysis tool (ANSYS Maxwell R19.3) was used to simulate the coil geometry and magnetic paste formulation effects on the magnetic flux density distribution, and the planar inductor electromagnetic properties to identify the optimal parameters. The differences between the simulation and the experimental planar inductor DC-bias superposition characteristics were compared. The deviations between the measured and simulated results are only within 6%, suggesting that the simulation has very high accuracy and reliability.

Automated summary

A planar inductor with excellent magnetic characteristics was successfully prepared by screen printing high solid content iron-based alloy magnetic pastes onto copper-clad laminates, followed by cold-isostatic pressing to increase packing density and adding an insulating layer using epoxy resin. Using a central column filled with magnetic paste, the inductance, magnetic flux channeling, and storage energy of the planar inductor were increased. The accuracy and reliability of the proposed method were validated through simulation and experimental results comparison, with deviations within 6%.