Fred Barlow

Bio: Fred Barlow is an academic researcher from University of Idaho. The author has contributed to research in topics: Power module & Fourier transform. The author has an hindex of 19, co-authored 88 publications receiving 1368 citations. Previous affiliations of Fred Barlow include Virginia Tech & Metropolitan State University of Denver.

Electronic Packaging: Semiconductor Packages

Abstract: Electronic packages contain numerous transistors and integrated circuits, resistors, capacitors, inductors, diodes, in addition to other components, linked through interconnections to form various functional entities. As functional densities increase, the level of integration of the inner circuitry continues to increase on the chip level. Electronic packaging serves a few critical functions such as signal distribution, power distribution, thermal management, rigidity, mechanical stability, and circuitry protection.

Fabrication of Microvias for

Abstract: Advances in screen printing and photoimageable paste technologies have allowed low-temperature cofired ceramic (LTCC) circuit densities to continue to increase; however, the size of vias for -axis interconnections in multilayer LTCC substrates have been a limiting process constraint. In order to effectively exploit the 50-100- m line/spacing capabilities of advanced screen printing and photoimageable techniques, microvia technologies need to achieve 100 m and under in diameter. Three main steps in fabrication of microvias include via formation, via metallization or via fill, and layer-to-layer alignment. The challenges associated with the processing and equipment for the fabrication of microvias are addressed in this paper. Microvias down to 50 m in diameter with spacings as small as 50 m are achieved in 50-254- m-thick LTCC tape layers through the use of a mechanical punching system, whereas the minimum size of 75- m via/spacing is ob- tained using a pulse laser-drilling system in the LTCC tape layers with the same thicknesses as those for the punching test. The quality of punched microvias and laser-drilled microvias will be presented as well. Layer-to-layer alignment is crucial to the con- nection of vias in adjacent LTCC tape layers. Through a stack and tack machine with a three-camera vision system and an adjustable precision stage, less than 25- m layer-to-layer misalignment is achieved across a 114.3 114.3 mm 4.5 4.5 in design area. In a six-layer LTCC test substrate 152 152 0.762 mm , microvias of 50, 75, and 100 m in diameter are successfully fabricated without the use of via catch pads. The cross section of fired microvias filled with silver conductor pastes at various locations of this substrate demonstrates a minor layer-to-layer misalignment in both and directions across the substrate.

Z-Axis interconnection for 3-D high density packaging

Abstract: Electronic packaging continues to produce denser systems. Currently chip packages have more than 1000 I/O, boards have 50-micron lines/spaces, and area array connectors with 1 mm pitch are readily available. To further increase system density, growth into the third dimension (z-axis) is required. However, stacked substrate assemblies have two inherent problems: thermal transfer from the inner layers and reliable, high-density interconnections among all substrates. This paper addresses the result of research on z-axis interconnects suitable for 3-D processor modules. We discuss the advantages and disadvantages for the intended system. One selected interconnection media, which is manufactured by Shin-Etsu, is based on metal wires embedded in a matrix of polymeric material. The wires protrude from the surface of the polymer film. By compressing this material between substrates, contact is made between metallized gold pads on the substrates via the embedded wires. The Shin-Etsu connector allows connections among multiple substrates at 0.5-mm pitch without the need for precision connector alignment because it contains redundant wires at very fine pitch. This paper describes the testing program to determine connector performance and reliability. Daisy chain test vehicles using gold metallization on ceramic substrates were fabricated, assembled and subjected to temperature cycling. Initial test results indicated an incompatibility between the connector material and the substrate, which led to hardware revisions. Daisy chains of 2500 z-axis interconnects have been subjected to over 800 temperature cycles from -45 °C to +85 °C. The resulting system appears to offer a reliable, high-density z-axis interconnection method.

Integrated motors and controllers for 42 V automotive auxiliary motor applications

Abstract: This work focuses on technical barriers to the implementation of controllers for auxiliary electric motors for automotive applications. It addresses the integration of three-phase brushless DC motors and advanced microelectronic packaging techniques into compact motor controllers. The proposed packaging techniques are focused on thermal performance utilizing minimum supplemental cooling. The primary focus of this discussion is the reduction of thermal resistance by the elimination of interfaces between the power devices and the heat sink. The initial application of this work is targeted at variable speed compressors for 42 V vehicles.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

A Survey of Wide Bandgap Power Semiconductor Devices

Abstract: Wide bandgap semiconductors show superior material properties enabling potential power device operation at higher temperatures, voltages, and switching speeds than current Si technology. As a result, a new generation of power devices is being developed for power converter applications in which traditional Si power devices show limited operation. The use of these new power semiconductor devices will allow both an important improvement in the performance of existing power converters and the development of new power converters, accounting for an increase in the efficiency of the electric energy transformations and a more rational use of the electric energy. At present, SiC and GaN are the more promising semiconductor materials for these new power devices as a consequence of their outstanding properties, commercial availability of starting material, and maturity of their technological processes. This paper presents a review of recent progresses in the development of SiC- and GaN-based power semiconductor devices together with an overall view of the state of the art of this new device generation.

Overview of Dual-Active-Bridge Isolated Bidirectional DC–DC Converter for High-Frequency-Link Power-Conversion System

Abstract: High-frequency-link (HFL) power conversion systems (PCSs) are attracting more and more attentions in academia and industry for high power density, reduced weight, and low noise without compromising efficiency, cost, and reliability. In HFL PCSs, dual-active-bridge (DAB) isolated bidirectional dc-dc converter (IBDC) serves as the core circuit. This paper gives an overview of DAB-IBDC for HFL PCSs. First, the research necessity and development history are introduced. Second, the research subjects about basic characterization, control strategy, soft-switching solution and variant, as well as hardware design and optimization are reviewed and analyzed. On this basis, several typical application schemes of DAB-IBDC for HPL PCSs are presented in a worldwide scope. Finally, design recommendations and future trends are presented. As the core circuit of HFL PCSs, DAB-IBDC has wide prospects. The large-scale practical application of DAB-IBDC for HFL PCSs is expected with the recent advances in solid-state semiconductors, magnetic and capacitive materials, and microelectronic technologies.

Eliminate Reactive Power and Increase System Efficiency of Isolated Bidirectional Dual-Active-Bridge DC–DC Converters Using Novel Dual-Phase-Shift Control

Abstract: This paper proposes a novel dual-phase-shift (DPS) control strategy for a dual-active-bridge isolated bidirectional DC-DC converter. The proposed DPS control consists of a phase shift between the primary and secondary voltages of the isolation transformer, and a phase shift between the gate signals of the diagonal switches of each H-bridge. Simulation on a 600-V/5-kW prototype shows that the DPS control has excellent dynamic and static performance compared to the traditional phase-shift control (single phase shift). In this paper, the concept of ldquoreactive powerrdquo is defined, and the corresponding equations are derived for isolated bidirectional DC-DC converters. It is shown that the reactive power in traditional phase-shift control is inherent, and is the main factor contributing to large peak current and large system loss. The DPS control can eliminate reactive power in isolated bidirectional DC-DC converters. In addition, the DPS control can decrease the peak inrush current and steady-state current, improve system efficiency, increase system power capability (by 33%), and minimize the output capacitance as compared to the traditional phase-shift control. The soft-switching range and the influence of short-time-scale factors, such as deadband and system-level safe operation area, are also discussed in detail. Under certain operation conditions, deadband compensation can be implemented easily in the DPS control without a current sensor.

Wearable Electrochemical Sensors and Biosensors: A Review

Abstract: This article reviews recent advances and developments in the field of wearable sensors with emphasis on a subclass of these devices that are able to perform highly-sensitive electrochemical analysis Recent insights into novel fabrication methodologies and electrochemical techniques have resulted in the demonstration of chemical sensors able to augment conventional physical measurements (ie heart rate, EEG, ECG, etc), thereby providing added dimensions of rich, analytical information to the wearer in a timely manner Wearable electrochemical sensors have been integrated onto both textile materials and directly on the epidermis for various monitoring applications owing to their unique ability to process chemical analytes in a non-invasive and non-obtrusive fashion In this manner, multi-analyte detection can easily be performed, in real time, in order to ascertain the overall physiological health of the wearer or to identify potential offenders in their environment Of profound importance is the development of an understanding of the impact of mechanical strain on textile- and epidermal (tattoo)-based sensors and their failure mechanisms as well as the compatibility of the substrate employed in the fabrication process We conclude this review with a retrospective outlook of the field and identify potential implications of this new sensing paradigm in the healthcare, fitness, security, and environmental monitoring domains With continued innovation and detailed attention to core challenges, it is expected that wearable electrochemical sensors will play a pivotal role in the emergent body sensor networks arena