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Showing papers by "Fred Barlow published in 2013"


Journal ArticleDOI
TL;DR: In this paper, a fully integrated silicon carbide (SiC)-based six-pack power module is designed and developed for electric vehicle and hybrid electric vehicle applications, where each switching element is composed of four paralleled SiC junction gate field effect transistors (JFETs) with two antiparallel SiC Schottky barrier diodes.
Abstract: In this paper, a fully integrated silicon carbide (SiC)-based six-pack power module is designed and developed. With 1200-V, 100-A module rating, each switching element is composed of four paralleled SiC junction gate field-effect transistors (JFETs) with two antiparallel SiC Schottky barrier diodes. The stability of the module assembly processes is confirmed with 1000 cycles of -40°C to +200°C thermal shock tests with 1.3°C/s temperature change. The static characteristics of the module are evaluated and the results show 55 mΩ on-state resistance of the phase leg at 200°C junction temperature. For switching performances, the experiments demonstrate that while utilizing a 650-V voltage and 60-A current, the module switching loss decreases as the junction temperature increases up to 150°C. The test setup over a large temperature range is also described. Meanwhile, the shoot-through influenced by the SiC JFET internal capacitance as well as package parasitic inductances are discussed. Additionally, a liquid cooled three-phase inverter with 22.9 cm × 22.4 cm × 7.1 cm volume and 3.53-kg weight, based on this power module, is designed and developed for electric vehicle and hybrid electric vehicle applications. A conversion efficiency of 98.5% is achieved at 10 kHz switching frequency at 5 kW output power. The inverter is evaluated with coolant temperature up to 95°C successfully.

137 citations


Proceedings ArticleDOI
12 Apr 2013
TL;DR: In this paper, the authors used the finite element code ABAQUS to simulate the silicon wafer warpage as a function of the wafer thickness and the film stresses.
Abstract: Wafer warpage is one of the most important challenges in the fabrication of modern electronic devices. Other challenges include handling, tool faults, and misalignments and even wafer breakage. The wafer warpage translates into die warpage that has a remarkable impact on die pick, stack and attach. This paper describes the work performed to simulate the silicon wafer warpage as a function of the wafer thickness and the film stresses using the commercial finite element code ABAQUS. The model accounts for the silicon anisotropy to better simulate the deformation. The computed values of the warpage were compared with experimental data and showed good correlation. The numerical model developed can be used to better understand the relation between the film stress and the wafer warpage. Furthermore it can be used to predict the warpage based on the wafer thickness and the film stress, which can help mitigate the warpage by depositing films to reduce the overall wafer warpage.

15 citations


ReportDOI
26 Nov 2013
TL;DR: In this article, the authors provide a fundamental understanding of the creep fracture behavior of modified 9Cr-1Mo steel welds through modeling and experimentation and recommend a design for an RPV structural health monitoring system.
Abstract: A recent workshop on next-generation nuclear plant (NGNP) topics underscored the need for research studies on the creep fracture behavior of two materials under consideration for reactor pressure vessel (RPV) applications: 9Cr-1Mo and SA-5XX steels. This research project will provide a fundamental understanding of creep fracture behavior of modified 9Cr-1Mo steel welds for through modeling and experimentation and will recommend a design for an RPV structural health monitoring system. Following are the specific objectives of this research project: • Characterize metallurgical degradation in welded modified 9Cr-1Mo steel resulting from aging processes and creep service conditions. • Perform creep tests and characterize the mechanisms of creep fracture process. • Quantify how the microstructure degradation controls the creep strength of welded steel specimens. • Perform finite element (FE) simulations using polycrystal plasticity to understand how grain texture affects the creep fracture properties of welds. • Develop a microstructure-based creep fracture model to estimate RPVs service life . • Manufacture small, prototypic, cylindrical pressure vessels, subject them to degradation by aging, and measure their leak rates. • Simulate damage evolution in creep specimens by FE analyses. • Develop a model that correlates gas leak rates from welded pressure vessels with the amount of microstructural damage. • Perform large-scale FE simulations with a realistic microstructure to evaluate RPV performance at elevated temperatures and creep strength. • Develop more » a fracture model for the structural integrity of RPVs subjected to creep loads. • Develop a plan for a non-destructive structural health monitoring technique and damage detection device for RPVs. « less

11 citations


Proceedings ArticleDOI
12 Apr 2013
TL;DR: A new method is proposed to check and enforce causality by using raw bandlimited data that is extended periodically using a polynomial interpolation and computing the Hilbert Transform of the periodically extended data via accurate FFT.
Abstract: Causality verification and enforcement is an essential step in generating high speed electric package macromodels and it often accomplished in two steps: vector fitting measured system parameters into a rational function representation and then performing the Hilbert Transform integrations to check and if needed enforce causality. This procedure suffers from various approximation, truncation, and discretization errors. Besides, the measured or simulated system data are known only on the finite bandwidth, while the Hilbert Transform has to be computed on the infinite domain. To avoid these errors as well as inaccuracy of extrapolation of the transfer function to infinity, a new method is proposed to check and enforce causality by using raw bandlimited data that is extended periodically using a polynomial interpolation and computing the Hilbert Transform of the periodically extended data via accurate FFT.

5 citations


Journal ArticleDOI
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.

2 citations


Proceedings ArticleDOI
12 Apr 2013
TL;DR: This paper compared residue perturbation with and without error control in order to calculate how passivity enforcement affects the original model accuracy.
Abstract: Passivity enforcement techniques are widely used in DRAM package model development. The Hamiltonian method is one of the common methods used for checking/enforcing passivity of these multiport networks. Enforcing the passivity for non-passive models is not trivial because it is built on several approximation steps starting from building the macromodel, which captures the frequency domain response, and ending with a suitable spice model for the DRAM circuits. Several approximation steps take place to achieve that result, and multiple constraints are used to preserve the original design characteristics. In this paper, we compared residue perturbation with and without error control in order to calculate how passivity enforcement affects the original model accuracy.

Journal ArticleDOI
01 Jan 2013
TL;DR: In this article, the authors proposed a commercially viable thermoelectric generator assembly that can be used in passenger vehicles to be able to withstand extreme environmental conditions, where three-dimensional models of full scale TEG were analyzed using finite element analysis (FEA).
Abstract: The objective of this work is to design a commercially viable thermoelectric generator (TEG) assembly that can be used in passenger vehicles to be able to withstand extreme environmental conditions. Since the operating temperatures of the TEGs can reach temperature levels higher than 500 °C, aluminum braze alloys offer a good high temperature solution for die attach. However, the evolution of fatigue damage in the aluminum braze must be understood in order to ensure an acceptable reliability of the TEG. In this paper, the proposed design of TEG package assembly was evaluated under extreme temperature conditions. Three-dimensional models of full scale TEG were analyzed using finite element analysis (FEA). The failures of aluminum alloy based braze (high temperature form of solder) material in the TEG application was investigated. Low cycle fatigue using direct cyclic approach was considered for the reliability analysis. Continuum damage mechanics approach was used to study the fatigue failure due to power ...

Journal ArticleDOI
01 Jan 2013
TL;DR: In this article, the challenges in electronic packaging for extreme environment based on experimental work of the researchers and conducted reliability testing to evaluate high speed devices suitable for these applications, substrates, die attach, wire bonding, and encapsulation and housing.
Abstract: The paper addresses the challenges in electronic packaging for extreme environment based on experimental work of the researchers and conducted reliability testing to evaluate high speed devices suitable for these applications, substrates, die attach, wire bonding, and encapsulation and housing. In particular, the researcher's work has focused on SiC power devices with low loss high voltage Schottky diodes with significant applications, high temperature JFETs and SiC MOSFETs (double trench), and GaN microwave devices. The paper provides recommendations for selection of devices, substrates, die attach, and encapsulation and housing for these applications.