Terence O’Donnell

Vibration based electromagnetic micropower generator on silicon

This paper discusses the theory, design and simulation of electromagnetic micropower generators with electroplated micromagnets. The power generators are fabricated using standard microelectromechanical system processing techniques. Electromagnetic two-dimensional finite element anlysis simulations are used to determine voltage and power that can be generated from different designs. This paper reports a maximum voltage and power of 55 mV and 70 W for the first design, incorporating microfabricated two-layer Cu coils on a Si paddle vibrating between two sets of oppositely polarized electroplated Co50Pt50 face centered tetragonal phase hard magnets. A peak voltage and power of 950 mV and 85 W are obtained for the second design, which includes electroplated Ni45Fe55 as a soft magnetic layer underneath the hard magnets. The volume of the device is about 30 mm3.

Precessional dynamics of Ni45Fe55 thin films for ultrahigh frequency integrated magnetics

Future monolithic point of load switched mode power supplies will be expected to meet the energy requirements of miniaturized, high functionality electronic devices. Recently, Ni45Fe55 has emerged as a potentially important material choice for use as a soft magnetic core material within high frequency integrated passive magnetic components. The operating frequency range of the integrated passives which form a key part of the point of load power supply must increase to allow for inductor/transformer miniaturization to become monolithic with power integrated circuits. In this work, an analysis of the high frequency permeability spectra of an electroplated Ni45Fe55 thin film has been carried out to quantitatively analyze the material’s high frequency performance. Complex permeability spectra of the film have been investigated at frequencies up to 9 GHz to identify both the film’s spectroscopic splitting factor (g) and its effective dimensionless damping parameter (α). The Kittel equation is utilized to ident...

Shape-independent permeability model for uniaxially-anisotropic ferromagnetic thin films

A permeability model based on the three-dimensional shape demagnetization effect is developed to estimate the permeability of any uniaxially-anisotropic ferromagnetic thin-film for integrated micromagnetic structures. The model is validated by comparison to measured ferromagnetic thin films (NiFe and CoPRe) with different anisotropies and saturation magnetizations. The dependence of permeability on film-thickness is modeled as a function of the demagnetization effect and verified against fabricated samples of varying thicknesses.

Integrated passives in advanced printed wiring boards

This paper will focus on the work which was carried out under the Brite‐EuRAM funded project, COMPRISE (BE 96‐3371), the objective of which was to develop new materials and manufacturing processes to embed passive components (resistors, inductors, capacitors) within printed wiring structures fabricated from laminate materials. For the realisation of integrated resistors, a commercially available planar resistor material is incorporated in different test structures. The technology consists of a copper foil of standard thickness on which a resistive layer is deposited by means of electroless plating. For the realisation of capacitors in multi‐layered PCB structures, significant progress was made in the development and fabrication of very thin laminates. Higher dielectric constants of these laminate materials enable the increase of the capacitance per unit area. For inductors, both aircore (no magnetic material) and magnetic core components have been investigated.