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.

LTCC based MEMS impingement coolers

Abstract: This paper deals with the cooling of high-density electronics using MEMS based impingement coolers. The coolers have been created from micro jet arrays based on both silicon micro machining and Low Temperature Co-fired Ceramic (LTCC). Some of the advantages of LTCC are that the technology offers hermeticity, matched thermal expansion coefficient (TCE) to minimize packaging-induced thermo mechanical stresses, and the ability to form cavities and other complex structures into the substrate material. Micro Jet Array (MJA) coolers have been fabricated and tested using both silicon, and hybrid silicon LTCC designs. In the present work, the demonstration of the hybrid technology incorporating both the Si and the LTCC fabrication techniques is discussed. The fabrication of the MJA in LTCC offers many advantages when compared to the conventional silicon based MJA. The limitations of the silicon based micro jet array are the wafer thickness required to withstand the inlet air pressure and the difficulties associated with bonding multiple wafers. In comparison the LTCC based design has the potential to be lower in cost and is much simpler to manufacturer.

Evaluation of Ceramic Substrates for High Power and High Temperature Applications

Abstract: Ceramic substrates with thin film and thick film conductor traces are widely used in microelectronic packages for high temperature operation. In high power applications where the maximum current in the package may be hundreds of amperes, much thicker conductive traces are normally required. For such applications, Direct Bonded Copper (DBC), Direct Bonded Aluminum (DBA) or Active Metal Bonded (AMB) substrates are good candidates. These substrates provide low electrical resistance and high ampacity, thereby enable the design of high power circuits for high temperature operation. The most commonly observed failure mode in these substrates is the delamination of metal layer from the ceramic. The lifetime of a ceramic substrate can be significantly reduced by the processing conditions such as maximum process temperature, and the process gases that the substrates are exposed to. It has also been shown that the propagation of cracks in the ceramic can be abated by dimpling the metal layers along edges and corner...

Finite element modeling of a back grinding process for Through Silicon Vias

Abstract: The optimization of grinding parameters for silicon wafers is necessary in order to maximize the reliability of electronic packages. This paper describes the work performed to simulate a back grinding process for Through Silicon Via (TSV) wafers using the commercial finite element code ABAQUS. The grinding of a TSV silicon wafer with a thickness of 120 μm mounted on a backing tape was simulated. The wafer was thinned to a thickness of 115.5 μm, by simulating the grinding with a diamond particle cutting through successive silicon and copper layers. The computed residual stresses induced in the wafer were compared with experimental values, and the plastic deformation in the simulated ground surface was compared with literature data and showed good correlation. The numerical model developed can be used to better understand the local grinding parameters in the TSV wafers and the effect of the of the copper vias on the wafer properties.

Time Delay Extraction from Frequency Domain Data Using Causal Fourier Continuations for High-Speed Interconnects

Abstract: We present a new method for time delay estimation using band limited frequency domain data representing the port responses of interconnect structures. The approach is based on the spectrally accurate method for causality characterization that employs SVD-based causal Fourier continuations, which was recently developed by the authors. The time delay extraction is constructed by incorporating a linearly varying phase factor to the system of equations that determines the Fourier coefficients. The method is capable of determining the time delay using data affected by noise or approximation errors that come from measurements or numerical simulations. It can also be employed when only a limited number of frequency responses is available. The technique can be extended to multi-port and mixed-mode networks. Several analytical and simulated examples are used to demonstrate the accuracy and strength of the proposed technique.

A Die Attach Design for Thermoelectric Generator Packages for Automotive Applications

Abstract: The requirement to achieve high reliability for the die attach in thermoelectric generator (TEG) package design is key to their viability and safe operation in automotive applications. In this study, the reliability of die attach material Al 718 (88% Al, 12% Si) during high temperature operating conditions is discussed. A novel approach is outlined to determine the damage parameter for accurate reliability predictions using a scalable test vehicle fabrication, testing, and finite element analysis (FEA) simulations. In addition, a new TEG package design is proposed that can withstand extreme environmental conditions and exhibit enhanced mechanical reliability by minimizing the likelihood that sublimation and oxidation of the semiconductor dies occurs. The proposed design of TEGs is analyzed using finite element simulations. Prototype models were fabricated and tested to validate the computational predictions. Continuum damage mechanics was used to predict the fatigue life of TEG packages using computational modeling of cyclic damage evolution. The results demonstrated that the proposed die attach design can be commercially viable for high-temperature TEG applications.

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