The need for high power density and high temperature capabilities in today's electronic devices continues to grow. More robust devices with reliable and stable functioning capabilities are needed, for example in aerospace and automotive industries as well as sensor technology. These devices need to perform under extreme temperature conditions, and not show any deterioration in terms of switching speeds, junction temperatures, and power density, and so on. While the bulk of research is performed to source and manufacture these high temperature devices, the device interconnect technology remains under high focus for packaging. The die attach material has to withstand high temperatures generated during device functioning and also cope with external conditions which will directly determine how well the device performs in the field. This literature work seeks to review the numerous research attempts thus far for high temperature die attach materials on wide band gap materials of silicon carbide, gallium nitride and diamond, document their successes, concerns and application possibilities, all of which are essential for high temperature reliability.

Die Attach Materials for High Temperature Applications: A Review

This paper presents an isolated on-board vehicular battery charger that utilizes silicon carbide (SiC) power devices to achieve high density and high efficiency for application in electric vehicles (EVs) and plug-in hybrid EVs (PHEVs). The proposed level 2 charger has a two-stage architecture where the first stage is a bridgeless boost ac-dc converter and the second stage is a phase-shifted full-bridge isolated dc-dc converter. The operation of both topologies is presented and the specific advantages gained through the use of SiC power devices are discussed. The design of power stage components, the packaging of the multichip power module, and the system-level packaging is presented with a primary focus on system density and a secondary focus on system efficiency. In this work, a hardware prototype is developed and a peak system efficiency of 95% is measured while operating both power stages with a switching frequency of 200 kHz. A maximum output power of 6.1 kW results in a volumetric power density of 5.0 kW/L and a gravimetric power density of 3.8 kW/kg when considering the volume and mass of the system including a case.

A High-Density, High-Efficiency, Isolated On-Board Vehicle Battery Charger Utilizing Silicon Carbide Power Devices

This paper evaluates the capability of SiC power semiconductor devices, in particular JFET and Schottky barrier diodes (SBD) for application in high-temperature power electronics. SiC JFETs and SBDs were packaged in high temperature packages to measure the dc characteristics of these SiC devices at ambient temperatures ranging from 25degC (room temperature) up to 450degC. The results show that both devices can operate at 450degC, which is impossible for conventional Si devices, at the expense of significant derating. The current capability of the SiC SBD does not change with temperature, but as expected the JFET current decreases with rising temperatures. A 100 V, 25 W dc-dc converter is used as an example of a high-temperature power-electronics circuit because of circuit simplicity. The converter is designed and built in accordance with the static characteristics of the SiC devices measured under extremely high ambient temperatures, and then tested up to an ambient temperature of 400degC. The conduction loss of the SiC JFET increases slightly with increasing temperatures, as predicted from its dc characteristics, but its switching characteristics hardly change. Thus, SiC devices are well suited for operation in harsh temperature environments like aerospace and automotive applications.

/pdf/power-conversion-with-sic-devices-at-extremely-high-ambient-3bzl7xfoa2.pdf

Power Conversion With SiC Devices at Extremely High Ambient Temperatures

High temperature power electronics has become possible with the recent availability of silicon carbide devices. This material, as other wide-bandgap semiconductors, can operate at temperatures above 500 °C, whereas silicon is limited to 150-200 °C. Applications such as transportation or a deep oil and gas wells drilling can benefit. A few converters operating above 200 °C have been demonstrated, but work is still ongoing to design and build a power system able to operate in harsh environment (high temperature and deep thermal cycling).

/pdf/state-of-the-art-of-high-temperature-power-electronics-3qyx36fnso.pdf

State of the art of high temperature power electronics

In order to take the full advantage of the high-temperature SiC and GaN operating devices, package materials able to withstand high-temperature storage and large thermal cycles have been investigated. The temperature under consideration here are higher than 200 °C. Such temperatures are required for several potential applications such as down-hole oil and gas industry for well logging, aircrafts, automotive, and space exploration. This review focuses on the reliability of a selection of potential components or materials used in the package assembly as the substrates, the die attaches, the interconnections, and the encapsulation materials. It reveals that, substrates with low coefficient of thermal expansion (CTE) conductors or with higher fracture resistant ceramics are potential candidates for high temperatures. Die attaches and interconnections reliable solutions are also available with the use of compatible metallization schemes. At this level, the reliability can also be improved by reducing the CTE mismatch between assembled materials. The encapsulation remains the most limiting packaging component since hard materials present thermomechanical reliability issues, while soft materials have low degradation temperatures. The review allows identifying reliable components and materials for high-temperature wide bandgap semiconductors and is expected to be very useful for researchers working for the development on high-temperature electronics.

Survey of High-Temperature Reliability of Power Electronics Packaging Components

This paper discusses the current state of SiC electronics research at Arkansas Power Electronics International, Inc. (APEI) with regard to high-temperature environments and applications. The University of Arkansas (UA) researchers' modeling and characterization of SiC power devices for these high-temperature environments are also discussed. Devices to be covered include SiC Schottky diodes, SiC power MOSFETs, and SiC static-induction-transistors (SITs). The paper reviews the current application of these devices to the specific harsh environments of deep Earth drilling and combat electric vehicles, as well as outline APEI's research work into developing operational SiC motor drives for these systems. It is proposed that this technology development be transferred to NASA space exploration applications. Two areas within the NASA program that would find this technology highly beneficial are (1) probes and landers that must operate in high-temperature environments and (2) ultra-lightweight power electronics for satellite and spacecraft power converter systems.

Silicon-carbide (SiC) semiconductor power electronics for extreme high-temperature environments

This paper presents the challenges and results of fabricating a high temperature silicon carbide based integrated power module. The gate driver for the module was integrated into the power package and is rated for an ambient temperature of 250 °C. The power module was tested up to 300 V bus voltage, 160 A peak current, and 250 °C junction temperature.

High-temperature silicon carbide and silicon on insulator based integrated power modules

The researchers have designed, developed, packaged, and manufactured a complete multichip power module (MCPM) that integrates silicon carbide (SiC) power transistors with silicon on insulator (SOI) control electronics. The SiC MCPM approach targets the reduction of size and the increase in efficiency of power electronic systems resulting in a highly miniaturized, high power density module. The researchers previously presented a single phase 3 kW SiC inverter that was also proven operational to 250degC at 500 W. In this paper APEI, Inc. will present a new SiC three-phase inverter that has been fully tested to 4 kW at 300degC operation. In this paper, the researchers discuss the challenges associated with high-temperature operation of power electronics, including the electrical, mechanical, and thermal design. Many electronic packaging problems have been solved to enable high-temperature operation of these modules. These packaging issues will be discussed as well as remaining problems that still need advancing. Finally, the full temperature and full power (300degC at 4 kW) test results are presented.

A Fully Integrated 300°C, 4 kW, 3-Phase, SiC Motor Drive Module

The researchers at Arkansas Power Electronics International, Inc. have designed, developed, packaged, and manufactured the first complete multichip power module (MCPM) integrating SiC power transistors with silicon on insulator (SOI) control electronics. The MCPM is a 4 kW three-phase inverter that operates at temperatures in excess of 250 °C. Bare die HTMOS SOI control components have been integrated with bare die SiC power JFETs into a single compact module. The high-temperature operation of SiC switches allows for increased power density over silicon electronics by an order of magnitude, leading to highly miniaturized power converters. In this paper, the researchers will discuss the challenges associated with high-temperature operation of power electronics; present the electrical, mechanical, and thermal design of a high-temperature MCPM; discuss the multitude of packaging issues that were solved to reach high-temperature operation; illustrate the high power density and miniaturization achieved by the SiC MCPM; and present the experimental test results of the fully operational 4 kW SiC MCPM.

A High-Temperature Multichip Power Module (MCPM) Inverter utilizing Silicon Carbide (SiC) and Silicon on Insulator (SOI) Electronics

Arkansas Power Electronics International, Inc, (APEI, Inc.) and University of Arkansas researchers have developed a novel, highly miniaturized motor drive capable of operation in excess of 250 degC. The high-temperature multichip power module (MCPM) integrates silicon carbide (SiC) JFET power transistors with high-temperature MOS silicon-on-insulator (SOI) control electronics into a single, highly miniaturized and compact power package. This paper outlines the design philosophy behind the high-temperature MCPM, discuss the high-temperature packaging technologies (including substrate selection, wirebonding, and die attach) developed and employed for module fabrication, illustrate thermal modeling results of the package, and present the results of prototype testing (demonstrating functionality)

Jared Hornberger

Papers

Silicon-carbide (SiC) semiconductor power electronics for extreme high-temperature environments

High-temperature silicon carbide and silicon on insulator based integrated power modules

A Fully Integrated 300°C, 4 kW, 3-Phase, SiC Motor Drive Module

A High-Temperature Multichip Power Module (MCPM) Inverter utilizing Silicon Carbide (SiC) and Silicon on Insulator (SOI) Electronics

High-temperature integration of silicon carbide (SiC) and silicon-on-insulator (SOI) electronics in multichip power modules (MCPMs)