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.

Alternative Z-axis connector technologies for high-density 3-D packaging

Abstract: 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 medium, 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. The second interconnection method, which is manufactured by FormFactor, uses a wire bonder to create gold wires with spring-like geometries on an array of metallized pads, fabricated on a test socket or interposer. This paper describes the testing program to determine connector performance and reliability.

Numerical simulation of heat generation during the back grinding process of silicon wafers

Abstract: The optimization of grinding parameters for silicon wafers is necessary in order to increase the reliability of electronic packages. Grinding is a mechanical process performed on silicon wafers during which heat is generated. The amount of heat generated affects the reliability of the wafer, and implicitly that of the final product. This paper describes the work performed to simulate the heat generated during a back grinding process for silicon wafers using the commercial finite element code ABAQUS. The grinding of a silicon wafer with a thickness of 60 μm mounted on a carrier wafer using bond adhesive material was simulated. The heat generated is caused by the friction between the grinding wheel and the backside of the silicon wafer. The computed temperature change due to friction in the wafer was compared with experimental and numerical values, and showed a good correlation. The numerical model developed can be used to better understand the local grinding temperature in the wafers and to estimate the effect of the grinding parameters on the temperature rise.

The utilization of polymer thick film (PTF) and flex technologies for low cost Power electronics packaging of DC/DC down converters

Abstract: Electronic power converters have been designed, produced, and disseminated to the market in mass quantities utilizing a number offabrication techniques; ranging from standard Printed Circuit Board (PCB) technologies for low cost applications, to conventional thick film on ceramic, to Direct Bond Copper (DBC) approaches for high power, higher cost applications Each of these approaches holds a share of the power packaging market, but they all demonstrate a limitation to conventional 2D flat board thinking PCBs, thick films, and DBCs are all technologies which restrict, for the most part, circuit and package designs to two dimensional boards The one potential pathway into the third dimension is through the use of multilayers ; an approach which becomes increasingly difficult with each additional layer added beyond the first, and with the exception of high performance solutions is typically cost prohibitive for the majority of applications This paper will demonstrate the feasibility and viability of an alternative low cost power packaging option which utilizes familiar industry technologies in a unique manner; flexible polymer substrates Flex technology employs industry standard PCB and/or thick film processes, offers the lower cost, higher performance solutions inherent with the majority of polymer plastics, and as a final bonus, essentially frees the designer to more efficiently utilize all three dimensions of space The researchers have demonstrated the feasibility of this low cost alternative solution through the fabrication and testing of Integrated Power Modules (IPMs) which utilize flexible polymer substrates in conjunction with both surface mount and bare dice These DC/DC power converters transform 120V/240V inputs to 9V, 7 Watt outputs, and illustrate through their unique geometrical design the miniaturization advantages of fully utilizing the 3D space offered by flex circuitry

Tunable BaSrTiO3, BaZrTiO3 Ferroelectric Capacitors Embedded Inside Low Temperature Cofired Ceramics (LTCC)

Abstract: This paper describes the design and processing of ferroelectric parallel plate capacitors embedded within a low temperature cofired ceramics (LTCC) structure. A capacitor is fabricated by filling a via hole with ferroelectric paste. Using ferroelectric materials, low-loss barium strontium titanate (BST) and barium zirconate titanate (BZT), as dielectric materials provide a wide range of tunability, in addition to low loss and low production cost. In addition, embedding tunable capacitors (varactors) inside LTCC reduces loss, size, weight, and cost. The paper also gives a comparison between the use of BST and BZT as tunable dielectric materials embedded inside an LTCC with respect to preparation process, applied voltage, shrinking factors, and quality factors.

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