Printed microinductors on flexible substrates for power applications

Abstract

A low-profile microinductor was fabricated on a copper-clad polyimide substrate where the current carrying coils were patterned from the existing metallization layer and the magnetic core was printed using a magnetic ceramic-polymer composite material. Highly loaded ferrite-polymer composite materials were formulated, yielding adherent films with 4 3900 G at +5000 Oe applied dc field. These composite magnetic films combine many of the superior properties of high temperature ceramic magnetic materials with the inherent processibility of polymer thick films. Processing temperatures for the printed films were between 100 C and 130 C, facilitating integration with a wide range of substrates and components. The quality factor of the microinductor was found to peak at = 18 5 near 10 MHz, within the optimal frequency range for power applications. A flat, nearly frequency independent inductance of 1.33 H was measured throughout this frequency range for a 5 mm 5 mm component, with a dc resistance of 2.6 and a resonant frequency of 124 MHz. The combination of printed ceramic composites with organic/polymer substrates enables new methods for embedding passive components and ultimately the integration of high inductors with standard integrated circuits for low profile power electronics.

Design and characteristics of flexible radio-wave absorber consisted of functional NiCuZn ferrite–polymer composites

“…6 shows the calculated return losses of a single-layer absorbing material consisting of the composites and terminating with a back conductor of a 10 mm thick absorbing layer using Eqs. (1) and (2). A return loss of −10 dB is generally regarded as a guideline of an excellent absorber, which is equivalent to about 90% of the radiowave energy dissipated by the absorber under normal incidence.…”

“…Electrical components are integrated to flexible substrates by screen printing as well as inkjet printing technologies in applications such as electronics papers, flexible smart cards, and radio-frequency identification systems [1][2][3]. Electromagnetic disturbances emerging from electrical components operating in radio-wave frequencies cause error-operation in precision instruments or error-reading in wireless identifications.…”

Novel Applications of Ferrites

“…As in all other applications, a strong need for miniaturization has also marked the developments in this area in the last few years. In addition to standard methods to obtain ferrite thin films (such as sputtering, laser ablation, sol-gel), screen or stencil printed ceramic-polymer composites have been investigated [36], combining the remarkable magnetic properties of ferrites with the processability of polymer thick films. These polymer thick films can be cured at temperatures about 200 • C or less, leaving only the polymer binder and the ferrite filler.…”

Electrical and temperature characterization of flexible planar inductor

“…Therefore, the inductor is a key component which affects the coupling efficiency and distance between transponder and reader. Most of literature was focused on the research of material characterizations and composites, as have been reported [3,[6][7], however, very few studies have investigated the temperature properties of the ferrite-polymer composite components.…”