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The emergence of perpendicular magnetic anisotropy (PMA) in amorphous thin films, which eventually transforms the magnetic spins form an in-plane to the out-of-plane configuration, also known as a spin-reorientation transition (SRT), is a fundamental roadblock to attain the high flux concentration advantage of these functional materials for broadband applications. The present work is focused on unfolding the origin of PMA in amorphous thin films deposited by magnetron sputtering. The amorphous films were deposited under a broad range of sputtering pressure (1.6–6.2 mTorr), and its effect on the thin film growth mechanisms was correlated to the static global magnetic behaviours, magnetic domain structure, and dynamic magnetic performance. The films deposited under low-pressure revealed a dominant in-plane uniaxial anisotropy along with an emerging, however feeble, perpendicular component, which eventually evolved as a dominant PMA when deposited under high-pressure sputtering. This change in the nature of anisotropy redefined the orientation of spins from in-plane to out-of-plane. The SRT in amorphous films was attributed to the dramatic change in the growth mechanism of disorder atomic structure from a homogeneously dispersed to a porous columnar microstructure. We suggest the origin of PMA is associated with the columnar growth of the amorphous films, which can be eluded by a careful selection of a deposition pressure regime to avoid its detrimental effect on the soft magnetic performance. To the author’s best knowledge, no such report links the sputtering pressure as a governing mechanism of perpendicular magnetisation in technologically important amorphous thin films.

3D micro and nanoconductors have emerged as essential components of next generation energy and sensor technologies. This work investigates novel methods to tailor the topography of electroplated 3D conductive components, such as VIAs, using the FEM in COMSOL Multiphysics. This enables meeting the design specifications of flat, convex, or concave substrate-distal electroactive surfaces. Flat conductor surfaces are ideal for microbump soldering and flip-chip fabrication methods and concave/convex designs increase the number of available electrode reaction sites for sensor applications. 2D/3D multiphysics simulations are performed comprising: (1) electrochemistry modeling with the Nernst-Planck and Butler-Volmer formulations for mass transfer and reaction kinetics, and (2) a deformed geometry physics module to track the growing electrode during electrodeposition. Simulation results are compared to directly corresponding experimental work, with positive correlation. Our findings enable tailored and scalable electroactive surface processing options, which can be readily integrated into pre-existing research and industry standard operating procedures.

Ultra-thin soft magnetic amorphous ribbons of Co-Fe-B-Si-Nb alloy were synthesised by a single step rapid-quenching approach to acquire advantage of improved material performance and lower costs over commercial amorphous alloys. The amorphous ribbons of approximately 5.5 µm thicknesses were quenched by a single roller melt spinner in a single-step production process and characterised for their structural and magnetic properties. The disordered atomic structure of amorphous ribbons was confirmed by the X-ray diffraction. A surface morphology study revealed the continuity of ultra-thin ribbons without pores over a large scale. The amorphous alloy showed the ultra-soft magnetic properties in the as-quenched state. The observed thickness dependency of the magnetic properties was attributed to the increased surface roughness and possibly due to a lack of densely packed atomic structure resulting from the extremely high cooling rates experienced by ultra-thin ribbons. We propose that in-situ thinning process of amorphous ribbons significantly reduces the basic material cost and eliminates the need for post-processing steps; hence it provides the opportunity for mass production of high-performance soft magnetic amorphous ribbons at relatively lower costs.

The integration of a high frequency (2-20 MHz) inductor device into the Printed Circuit Board (PCB) of a power converter would enable higher density integration of power converters [1] [2]. High frequency magnetic materials are required to reduce the size of an inductor device. This paper will consider commercially available thin flexible planar magnetic materials with a thickness of less than 500 µm. These materials are shown capable of withstanding laser cutting into toroidal shapes. These magnetic cores are then used to create toroidal inductors which are electrically characterised in order to calculate the magnetic material properties. The standard performance factor [3] of the materials is used to make a comparison across frequencies. An embedded in-PCB toroidal inductor is fabricated with the thin flexible planar magnetic material. Finally, a thermal simulation of the embedded in-PCB inductor is shown and the power loss density limitations of the device are discussed.

As demand accelerates for multifunctional devices with a small footprint and minimal power consumption, 2.5D and 3D advanced packaging architectures have emerged as an essential solution that use through-substrate vias (TSVs) as vertical interconnects. Vertical stacking enables chip packages with increased functionality, enhanced design versatility, minimal power loss, reduced footprint and high bandwidth. Unlocking the potential of photolithography for vertical interconnect access (VIA) fabrication requires fast and accurate predictive modeling of diffraction effects and resist film photochemistry. This procedure is especially challenging for broad-spectrum exposure systems that use, for example, Hg bulbs with g-, h-, and i-line UV radiation. In this paper, we present new methods and equations for VIA latent image determination in photolithography that are suitable for broad-spectrum exposure and negate the need for complex and time-consuming in situ metrology. Our technique is accurate, converges quickly on the average modern PC and could be readily integrated into photolithography simulation software. We derive a polychromatic light attenuation equation from the Beer-Lambert law, which can be used in a critical exposure dose model to determine the photochemical reaction state. We integrate this equation with an exact scalar diffraction formula to produce a succinct equation comprising a complete coupling between light propagation phenomena and photochemical behavior. We then perform a comparative study between 2D/3D photoresist latent image simulation geometries and directly corresponding experimental data, which demonstrates a highly positive correlation. We anticipate that this technique will be a valuable asset to photolithography, micro- and nano-optical systems and advanced packaging/system integration with applications in technology domains ranging from space to automotive to the Internet of Things (IoT).

This work presents analytical expressions for the DC inductance of 3D air core inductors with circular cross section pillars (CCSP) and rectangular cross section pillars (RCSP). We consider the following four types of inductor structures: (1) a toroid with CCSP; (2) a toroid with RCSP; (3) a solenoid with RCSP; and (4) a solenoid with CCSP. For each type, a unique analytical model is developed for obtaining DC inductance. High frequency (1-100 MHz) effects on inductance are also discussed. The inductance values predicted by the proposed analytical models of the first three types of inductor structures are in an acceptable agreement with numerical Finite Element Analysis (FEA) solutions, where the maximum difference is 7.3%. Also, our analytical model for the fourth type inductor reduces the error, when correlated with FEA inductance value, up to 6× compared to previously published models. A comparison of results using proposed analytical expressions with published measured values as well as our measurement data demonstrates error ranging from 0.5 to 16.2%, while conventional formulae show errors of up to 143%. The results of the proposed models could serve as a good initial estimate for power supply on chip (PwrSoC) and power supply in package (PSiP) applications.

Background:Prison populations are growing globally with an increase in older and infirm prisoners, as well as longer prison sentences, meaning more prisoners are likely to die while incarcerated. This scoping review explored the experiences of a death in prison custody on staff and relatives.Methods:Ovid MEDLINE, Embase, CINAHL and PsycINFO were professionally searched, followed by a hand search. Empirical and non-empirical studies of deaths in prison custody were screened. Data extraction used Arksey and O’Malley’s framework. Thematic analysis was underpinned by Braun and Clarke for identifying, analysing and reporting patterns. Results:From 12,127 citations retrieved, 174 were selected for full-text review, and 22 were included in the final scoping review. Thematic analysis revealed four themes: (i) transformative effect (ii) time delays, (iii) conflicts of interest, and (iv) support. Prison staff avoided contaminating their personal lives. Families were distressed by inaccurate and untimely information, inappropriate constraints and poor communication. Staff balanced security and humanitarian needs. Bereaved relatives and staff felt isolated, alienated and unsupported. Conclusions and recommendations:Unmet advocacy, communication and social care needs, poor end-of-life and bereavement care could be improved through staff training and social work intervention. Staff need psychosocial support, supervision and counselling.

Increasing switching frequency, enabled by advances in discrete silicon switches, monolithic CMOS/LDMOS switching bridges and GaN HEMTs, have resulted in a lower inductance requirement for the DC-DC power converter. High density, high efficiency magnetic materials are required to support the increasing power semiconductor switching frequencies. Advanced packaging technologies allow magnetic devices to be integrated within the package substrate of the application Printed Circuit Board (PCB). This paper provides an overview of the magnetic core embedding process technology and a procedure to characterise the magnetic material after its co-processing during the PCB manufacturing process.

Phase transformation driven soft magnetic properties have been correlated through different stages of nano-crystallization of Co-based amorphous alloys, via transverse magnetic annealing, by combining structural, magnetothermal, domain imaging, and AC/DC magnetometry techniques. The nano-crystallization starts by nucleation and growth process of soft magnetic meta-stable, thermodynamically favored, Co23B6 phase with less nucleation activation energy compared to other stable phases. In the second crystallisation stage, Co2B and Co3B, as a semi-hard magnetic phase, are identified in the alloys, magnetically annealed at 525 and 550 °C, respectively. Field-induced anisotropy dominates over the residual contributions of magneto-crystalline anisotropy of the phases, precipitated after field annealing at 510, 515, and 525 °C. The anomalous loss is significantly reduced as by annealing in a transverse magnetic field due to the reorientation of the preferred magnetisation axis, and consequently, change in dominant magnetization reversal mechanism from domain wall motion to magnetization rotation. In addition, magnetic annealing causes a measurable decrease in the domain width, which, in turn, promotes pinning and inhibits domain wall motion, thus further favours coherent domain rotation as the primary mechanism of magnetization. The combined mechanism of nanocrystallisation and coherent magnetisation rotation accounts for a 70% decrement in the anomalous loss in the so-processed ribbons at 525 °C, which renders them attractive for applications in mid- and high-frequency power supplies and inverters.

The recent history of Northern Ireland society is one in which denominationally-defined communities have been losing identity in favour of more fluid, diverse and secular forms of social interaction. The practice of hospital chaplaincy reflects this social transition: it is faced with the challenge of redefining itself in non-sectarian ways, as expressed in the migration of hospital chaplaincy from a denominationally-based to person-centred model of care. Six semi-structured interviews were conducted with a representative sample of chaplains working in Health and Social Care (HSC) Trusts in Northern Ireland (NI). Using interpretative phenomenological analysis (IPA) ten key themes were identified that fell into three areas: training for chaplaincy, the delivery of chaplaincy and the relationship between chaplains and the institutions of church and hospital. The themes shed new light on how chaplains are negotiating this transition from a denominational to a post-denominational context; and the tensions and pitfalls they encounter.

Integrated magnetic components are key elements of the power supply on chip modules. Due to the application requirements, these magnetic devices work at very high frequency and have low inductances. Conventional small-signal tests do not provide all the required information about the magnetic device. Hence, it is important to develop new setups to apply large signals to accurately measure the performance of devices under realistic operating conditions, including nonlinear core effects. The proposed experimental setup is suitable to measure the device impedance under different large-signal test conditions, similar to those in the actual converter, since the excitation current can be configured through every winding: ac current up to 0.5 A at frequencies up to 120 MHz and dc bias current up to 2 A through one or both windings. Voltage and current are measured using commercial instrumentation. Due to the characteristics of the probes and the high frequency of the test, the attenuation and delay due to the probes and the experimental setup have to be taken into account when processing the voltage and current waveforms to calculate the impedances. The compensation test to calculate this attenuation and delay is described. Finally, the proposed setup is validated by measuring a two-phase coupled inductor microfabricated on silicon. This work was supported in part by the European Union through FP7 (Project: PowerSwipe) under Grant 318529, in part by the Science Foundation Ireland through the Investigators Programme under Grant 15/IA/3180, and in part by the Spanish Ministry of Economy and Competitiveness and FEDER funds under Project DPI2014-53685-C2-1-R and Project DPI2017-88062-R. This paper was recommended for publication by Associate Editor Matthew A. Wilkowski.

The present work is focused on developing amorphisation capability criteria to predict regions with high amorphous forming ability (AFA) in the Fe-Si-B phase diagram. First, the AFA of Fe-Si-B alloy powders was evaluated by conventional empirical glass forming parameters, which eventually did not guide to the best AFA alloy. Then, AFA analysis was extended to the ternary phase diagram, calculated using CALPHAD, along with superimposed mathematical model based on topological instability factor (λ), estimated critical cooling rate (RC) and critical particle size (dC), to confine the phase diagram regions with larger AFA. The alloy with the highest AFA shows optimum atomic size mismatch when λ = 0.204. Furthermore, the optimal region in the phase diagram to design alloys with high AFA is where Fe2B is the first solid phase under equilibrium solidification. Within these two limits, the alloys with lower liquidus temperatures show the highest AFA for the gas-atomised powders.

This paper demonstrates an object orientated GPU accelerated micromagnetic simulator designed to model the material characteristics of complex magnetic alloy systems. The GPU simulator is written in C++ and uses object orientated programming to create a class that stores the magnetic information required to solve the Landau-Lifshitz-Gilbert (LLG) equation for a distribution of magnetic objects. Each magnetic object can be assigned individual properties based on the alloy distribution of interest. The simulator is verified against standard problem 4 of the “Micromagnetic Modelling Activity Group” (μmag). Standard problem 4 is chosen as it provides a benchmark for the modelling tools ability to accurately predict the magnetisation dynamics of a 500 nm × 125 nm × 3 nm Permalloy thin film.

A thermodynamics-based approach, Calculation of Phase Diagram (CALPHAD), combined with topological instability parameters are proposed and experimentally evaluated, in order to optimise in-situ nanocrystallisation of rapidly quenched CoFeB alloys and exploit their remarkable Bs = 1.57 T. The high Ms of the alloy is attributed to the precipitation of the metastable Co7Fe3 nanocrystalline phase dispersed heterogeneously in the amorphous matrix. High Ms of Co7Fe3 phase can also be inferred from the high hyperfine magnetic field of the Fe nuclei deduced from Mossbauer spectra. It is worth noting that the in-situ nanocrystallisation is a volume phenomenon, instead of surface crystallisation at the air-side of ribbons owning to lower cooling rates. We judge, based on nucleation theory, that the formation of the metastable phase is kinetically favoured, when compared to the equilibrium phases, hence promoting the high Ms, when compared with conventional Co-rich amorphous alloys. The local atomic order of nanocrystallised phase was confirmed by X-ray and electron diffraction techniques. Using Mossbauer spectroscopy and the extracted distribution of the hyperfine magnetic field, it is asserted that cobalt atoms form clusters, as they attract each other to form ordered structures, and boron atoms undergo only short-range ordering, likely due to covalent bond formation, governed by the size and electronegativity differences with the atoms in the amorphous matrix. We suggest the proposed CALPHAD-assisted design of nanostructured alloys, along with an in-situ nanocrystallisation, provides a practical scheme to develop novel functional alloys with the best possible balance of coercivity and saturation, exclusively aimed for a high-tech application.

Soft magnetic amorphous materials with ultra-low power loss are highly desirable for high-frequency drive applications. The present work demonstrates the high-frequency power loss performance and underlying loss mechanisms in ultra-thin amorphous alloys. This is achieved by rapid-quenching amorphous alloys of Co-, CoFe- and Fe-rich systems, investigating their amorphous atomic structure, quantifying the saturation magnetostriction constants (λs), imaging magnetic domains at remanent magnetization, analyzing magnetization reversal from various magnetization levels, and finally, investigating the material loss performance over a broad frequency range (f = 50 kHz–2 MHz) at various excitation levels (Bm = 25–100 mT). The ultra-high performance of ultra-thin Co-rich amorphous ribbons, as compared to CoFe- and Fe-rich alloys, was attributed to the significantly low eddy current loss, due to the reduced thickness, and a minimal amount of excess loss, owning to minimal magnetoelastic contributions and magnetization reversal by rotation. The underlying loss mechanisms were analyzed by decomposing material loss into primary components and identifying the magnetization reversal mechanisms using minor hysteresis loops. In the Co-rich amorphous alloys, we suggest that magnetization reversal by rotation dominates, at least at low excitations, while in CoFe- and Fe-rich alloys domain wall displacement prevails and contributes significantly to the excess loss up to the MHz frequency range. Magnetization reversal by rotation in Co-rich alloys could be attributed to the zero/near-zero λs, and eventually low residual stress, leading to a homogeneous magnetic domain structure, as compared to the inhomogeneous “fingerprint-like” complex domains in highly magnetostrictive CoFe-rich alloys.

The origins of sub-Ferromagnetic Resonance (FMR) multimodal behavior in the magnetic susceptibility spectrum of amorphous CoZrTaB magnetic thin films are investigated using Brown's diffusion model describing continuous diffusion of magnetic spins. Brown's diffusion model is regressed onto experimental data for the amorphous CoZrTaB magnetic thin films with thicknesses spanning 80-530nm. The mathematical model presented successfully reproduces the thickness dependent dynamic magnetic susceptibility of the amorphous CoZrTaB magnetic thin films with strong statistical significance. The model proposes the formation of additional energy wells in the uniaxial anisotropy energy plane of the material after a critical film thickness. The sub-FMR resonance peaks arise when the frequency of the external excitation field approaches the natural frequency of the well. Furthermore, the additional energy wells in the anisotropy energy plane cause a breakdown in the axial symmetry of the anisotropy energy plane. This breakdown of axial symmetry results in dynamic coupling between the transverse (chi(perpendicular to)) and longitudinal (chi(parallel to)) magnetic susceptibility. This dynamic coupling results in the initial low frequency step-down in the magnetic susceptibility observed in the thicker CoZrTaB magnetic thin films. It is found that the application of an external bias magnetic field along the easy axis of the amorphous CoZrTaB magnetic thin films suppresses the sub-FMR resonance peaks by restoring the axial symmetry of the anisotropy energy plane.

The effect of surface roughness in thin film magnetics on magnetic susceptibility and Dynamic Magnetic Hysteresis (DMH) loops are investigated using Brown’s continuous diffusion of magnetic spins model. The magnetic relaxation time of the magnetic thin films is determined by regressing the two-mode approximation for the magnetic susceptibility onto experimental data obtained for Ni45Fe55. There is a moderate linear correlation between the magnetic relaxation time and the surface roughness to the thickness (SRT) ratio. The area of the DMH loops and the non-linear dynamic magnetic susceptibility strongly depend on the magnetic relaxation time and the SRT of the films. The thin films exhibit a strong linear relationship between the coercivity and the SRT ratio, along with a strong logarithmic dependence of the dynamic magnetic susceptibility on the SRT ratio.

With increasing switching frequencies for passive components in power supplies, there lies a demand for materials that exhibit excellent soft magnetic properties at high frequencies. Electrical resistivity is of particular importance, as a high value is of significant importance in suppressing eddy current loss. The present work is focused on improving material with ultra-soft magnetic properties at high working frequencies by making nanocomposite CoZrTaB–SiO2 thin films using co-sputtering. The films show an increasing trend of resistivity with SiO2 incorporation, attributed to the high degree of electron scattering based on a metal–insulator–metal network. The ultra-low coercivity (Hc ∼ 0.1 Oe) and enhanced anisotropic field (Hk ∼ 42 Oe) of films were correlated to the ferromagnetic exchange coupling, which were significantly affected by a small concentration of SiO2. Relatively high permeability, ultra-low loss response, and high ferromagnetic resonance frequency make this material a promising candidate for replacing conventional magnetic cores in passives, in addition to noise suppression applications.

The present work demonstrates the high-frequency core loss performance of Fe-based amorphous and nanocrystalline powder cores, initially produced by gas atomised powder, consolidated using sieved particles ≤20 µm, and isolated by a precise insulating layer of polymer to limit the inter- and intra-particle eddy currents to attain enhanced performance. The large glass forming ability (GFA) of the gas atomised powder, reflected by different glass forming instruments, such as the supercooled region (ΔTX = 54 °C) and the reduced glass transition temperature (Trg = 0.56), is consistent with the substantial amorphisation capability of the alloy. To the best of our knowledge, this is the first-ever report to reveal a large ΔTX in the Finemet-type alloy powders, an essential parameter to gas-atomise the amorphous powders with significantly lower cooling rates compared to the melt-spun ribbons. Further, subsequent annealing of the amorphous powders, between the exothermic events guided by differential scanning calorimetry (DSC), lead to the growth of a fine nanocrystalline structure of grains ≤15 nm, thanks to the positive enthalpy of mixing of Cu with the constituents to act as a nucleation agent, to retain the excellent soft magnetic properties. The DC soft magnetic properties of the powders were significantly improved on thermal annealing, confirmed by hysteretic loops, quantified by reduced coercivity HC

The mechanisms that limit the power loss performance in melt-spun amorphous ribbons have been investigated through DC and AC magnetic characterization methods. The measured total power loss is resolved into hysteresis, eddy current, and anomalous losses. The anomalous loss is found to account for more than 90% of the total loss, which significantly reduced by annealing in a transverse magnetic field. This is attributed to the reorientation of preferred magnetisation axis perpendicular to the length of ribbons. Transverse magnetic annealing promotes the relative contribution of domain rotation over domain wall motion during magnetisation reversal process. Magnetic annealing also causes a measurable decrease in the domain width, which promotes pinning and inhibits domain wall motion, thus further favoring coherent domain rotation as the primary mechanism of magnetization. This combination accounts for a 75% decrease in the total power loss in the so-processed ribbons and renders them attractive for applications in mid-and high-frequency power supplies and inverters.

Advances in power conversion technologies have highlighted the need for development of new class of magnetic components (inductors, transformers etc) with lower footprint and higher efficiency. Presently, the sizes of these magnetic components have been limited due to the use of low flux density ferrite as a core material. In this paper, the assembly and working of an amorphous ribbon transformer with low loss performance as a replacement for ferrite based ones were studied. The minimum amount of power loss of the material was measured as

Novel heat removal and power delivery topologies are required to enable ‘extreme 3D integration’ with cube-sized compute nodes. Therefore, a technology roadmap is presented supporting memory-on-logic and logic-on-logic in the medium and long-term, by (i) dual-side cooling and integrated voltage regulators, and (ii) interlayer cooling and electrochemical power delivery.

The emergence of miniaturized and integrated Power Supply on Chip (PwrSoC) and Power Supply in Package (PwrSiP) platforms will be enabled by the application of thin-film, integrated magnetics on silicon. A process flow for, and the design of, a thin-film coupled-inductor, switching at 60MHz, is described. Based on the large signal characterization data, measured up to 100MHz, the efficiency of the inductor is calculated to be 91.7% for a power of 0.5W.

Thickness dependent competing magnetic anisotropy energies were investigated to explore the global magnetic behaviours of FineMET amorphous thin films. A dominant perpendicular magnetization component in the as-deposited state of thinner films was observed due to high magnetoelastic anisotropy energy which arises from stresses induced at the substrate-film interface. This perpendicular magnetization component decreases with increasing film thickness. Thermal annealing at elevated temperature revealed a significant influence on the magnetization state of the FineMET thin films and controlled annealing steps leads to ultra-soft magnetic properties, making these thin films alloys ideal for a wide range of applications.

In this work, a new set-up is presented to characterize the large signal electrical parameters of on-Silicon integrated coupled inductors for Power Supply on Chip. The proposed system is suitable to perform the measurements under different large-signal test conditions given by the dc bias current up to 2 A and ac current through one or both windings, with amplitudes ranging from 0 A to 0.5 A at frequencies up to 120 MHz. Since a key issue when measuring at high-frequencies is the error due to the attenuation and time skew between the channels, an additional test is performed to characterize the measurement system and compensate the voltage and current waveforms.

Advances in wide bandgap semiconductors have facilitated an increase in switching frequencies of power supplies. Higher switching frequencies are key to reducing the size of power components. However, miniaturization of magnetic passive components at high frequencies is still a challenge. Soft magnetic high flux density thin films are being widely researched as a replacement for ferrite cores. The existing thin film solutions have an inferior power loss performance compared to the best-in-class ferrites (500–600 ${\rm kW}/{\rm m}^{3}$ at 500 kHz and 100 mT peak field) for the same frequency. In this paper, we discuss details of a post-processing technique for nanocrystalline thin film to achieve a power loss density of 200 ${\rm kW}/{\rm m}^{3}$ at 500 kHz with peak flux density of 100 mT.

In recent years, increased demand for high aspect ratio MEMS structures has driven the need for thick photoresist fabrication processes. In this work, the optimization of a thick photoresist process using a negative tone resist (THB-151N) is described. A thickness of 85 μm is obtained with an aspect ratio of 17:1 in a single coating process, with a 5 μm pitch. Conventional UV lithography is used and its parameters are optimized in order to achieve straight and near vertical sidewall profiles. The developed patterns are used as a mold to electroplate high aspect ratio copper windings of micro-inductors and micro-transformers. A high aspect ratio yields a copper track with a large cross sectional area resulting in a lower DC resistance. This enables a further reduction in the footprint area allowing for a more efficient manufacturing process and smaller device size. Unlike other high aspect ratio resist such as SU-8, this resist does not need a post exposure bake and can be readily removed after metal electroplating.

The present work investigates the emergence of multiple modes in the high-frequency permeability spectrum of Co-Zr-Ta-B amorphous thin films. Amorphous thin films of different thicknesses (t=100-530 nm) were deposited by DC magnetron sputtering. Their static and dynamic soft magnetic properties were investigated to explore the presence of multi-magnetic phases in the films. A two-phase magnetic behavior of the thicker films (≥333 nm) was revealed by the in-plane hysteresis loops. Multiple resonance peaks were observed in the high-frequency permeability spectrum of the thicker films. The thickness dependent multiple resonance peaks below the main ferromagnetic resonance (FMR) can be attributed to the two-phase magnetic behaviors of the films.

An analytic model for stripline micro-inductors is presented which accurately approximates finite-element solutions while also allowing for variation of a wide range of parameters. Optimized models for magnetic enhancement layers are validated with measured results of different materials. The effects of these device and material models are applied to analyze stripline devices operating above 100 MHz. The effects of geometry on inductance, Q-factor, and current-carrying capability are presented for the materials in question.

As result of its high resistivity and good magnetic properties, electrodeposited amorphous Co–P (a-Co–P) is an attractive material for use in the integration of on-chip inductors into silicon process technology. However as an amorphous material, the properties of a-Co–P are dramatically changed upon crystallization. This paper reports a novel electrodeposited magnetic alloy, a-Co–P–Re that shows a significantly improved thermal performance in comparison to a-Co–P, retaining coercivity, Hc

Triaxial fluxgate sensors working in parallel mode with electroplated Permalloy (Ni80Fe20) cores were manufactured utilizing a low-cost printed circuit board technology and subsequently characterized. Sensor versions with various core shapes are compared and they are all shown to be capable of measuring low intensity magnetic field in three axes. It was found that the sensor sensitivity in the xy plane is influenced by the core material anisotropy (133 and 151 V/T in x and y axes respectively for T-shaped core sample). Despite much higher demagnetization ratio the sensitivity in z axis is higher (310 V/T for T-shaped core sample) as a result of higher core cross-section and pickup coil construction. The effects of two excitation modes - serial and separated - are investigated. It is shown, that serial excitation mode results in sensor axes tilt within xy plane, the actual tilt value being dependent on the core shape (14deg/6deg/6deg with Cross-/T-/X-shaped core sensor, respectively). The results suggest that the narrower the core, the lower axes tilt results. The alternative separated excitation mode substantially reduced the axes tilt below 2deg but increased the sensor output hysteresis in z axis reading (from less than 0.3% to 1.5% in plusmn50 muT sweep).

A novel fluxgate sensor with a single ferromagnetic core capable of measurement in three principal axes is presented. The sensor manufacturing process and internal coil structure is explained and its excitation is modelled using FEM. The sensor was implemented utilizing multilayer printed circuit board copper routes and electroplated through holes to create appropriate coils. The sensor magnetic core was electroplated on the printed circuit board surface and through holes using Permalloy (Ni80Fe20). The core material properties were identified using a PCB based transformer device showing relative permeability of 2300 at 50 kHz. Sensor excitation effects are investigated with special emphasis on sensor axis orthogonality revealing a significant sensitivity axis tilt due to excitation means. The sensor is characterised in terms of sensitivity, linearity and noise. Measurements show a significant influence of core material anisotropy on sensitivity (90 V/T in x axis vs. 112 V/T in y axis). The z-axis sensitivity (198 V/T) is significantly higher due to the different core geometry in corresponding direction and different number of pick-up coil turns.

We have investigated CoNiFe and CoNiFe–C electrodeposited by pulse reverse plating (PRP) and direct current (DC) techniques. CoNiFe(PRP) films with composition Co 59.4 Fe 27.7 Ni 12.8 show coercivity of 95 A m −1 (1.2 Oe) and magnetization saturation flux ( μ 0 M s ) of 1.8 T. Resistivity of CoNiFe (PRP) is about 24 μΩ cm and permeability remains almost constant μ r ′ ∼475 up to 30 MHz with a quality factor ( Q ) larger than 10. Additionally, the permeability spectra analysis shows that CoNiFe exhibits a classical eddy current loss at zero bias field and ferromagnetic resonance (FMR) when biased with 0.05 T. Furthermore, a crossover between eddy current and FMR loss is observed for CoNiFe-PRP when baised with 0.05 T. DC and PRP plated CoNiFe–C, which have resistivity and permeability of 85, 38 μΩ cm, μ r ′=165 and 35 with Q >10 up to 320 MHz, respectively, showed only ferromagnetic resonance losses. The ferromagnetic resonance peaks in CoNiFe and CoNiFe–C are broad and resembles a Gaussian distribution of FMR frequencies. The incorporation of C to CoNiFe reduces eddy current loss, but also reduces the FMR frequency.

Electroplating is compatible with the deposition of relatively thick layers i.e. several μm to 10s- of μm. However eddy current losses mean that thick layers will have an inferior frequency response. We have used a low content phosphorous bath together with pulse reverse plating to generate Co-rich and Co-deficient multi-nanolayers of CoP having improved saturation magnetisation and a better frequency response. The plating parameters have been optimised in order to produce a material with low loss, and a high permeability of around 700 retained up to 103 MHz for a sample with a thickness of 1.7 μm and a resistivity of 136 μΩ cm.

This paper presents an electromagnetic based generator which is suitable for supplying generating power from human body motion and has application in providing energy for body worn sensors or electronics devices. A prototype generator has been built and tested both by a shaker at resonance condition and also by human body motion during walking and slow running. The experimental results will show that the prototype could generate 300 μW to 2.5 mW power from human body motion. The measured results are analyzed and compared with the theoretical model.

This paper discusses the technologies required to produce magnetics on silicon for power supply on chip. Prototypes of micro-inductors have been fabricated using techniques such as thick copper coil deposition and improved magnetic materials. The measured maximum Q factor and inductance value are 5 at 2.5 MHz and 38 nH/mm2, respectively. The impact of seed layers and core overlap has been identified to be significant at high frequencies. Using the validated analytical model, the electrical performance of micro-inductors in a buck converter can be predicted and efficiency of 85.9 with a power density of 15.8 W/cm2 can be achieved.

This paper describes the design and testing of a planar fluxgate current sensor, which is totally embedded in printed circuit board (PCB) and which is suitable for sensing currents in the printed circuit board traces. Fluxgate excitation and pickup coils are implemented as racetrack shaped copper winding in the printed circuit board internal layers. These are surrounded by an electroplated magnetic core consisting of a thin film of nickel iron alloy. The sensor has been tested over a 2 A current range. Sinusoidal excitation at 10 kHz, 30 kHz and 50 kHz has been used. The sensitivity has been measured at 200 mV/A for 50 kHz excitation. The power dissipation has been measured at approximately 2.6 W for a sinusoidal excitation.

The lamination of the core in thin film magnetic components is necessary to reduce the eddy current losses of the structure at high frequencies. The usual way to achieve lamination of the core is by physical vapor deposition (PVD) techniques. These methods are however costly and the deposition of layers is non selective. In this article, an almost entirely aqueous-based electrochemical process for the lamination of magnetic cores is presented. The process uses an electrodepositable photoresist Eagle 2100 ED codeposited with a catalyst (palladium). The Eagle layer is left as an insulator and the catalyst allows the activation of the layer for subsequent metallization. The process can be reproduced as many times as required for producing the multilayers. It is also selective: it does not require multiple photolithography steps. As a demonstration of the multilayer process, a core constituted of two layers of Ni/sub 80/Fe/sub 20/ (6 /spl mu/m each layer), separated by an Eagle insulating layer, electroplated over three-dimensional structures, was produced.