Condition monitoring (CM) has already been proven to be a cost effective means of enhancing reliability and improving customer service in power equipment, such as transformers and rotating electrical machinery. CM for power semiconductor devices in power electronic converters is at a more embryonic stage; however, as progress is made in understanding semiconductor device failure modes, appropriate sensor technologies, and signal processing techniques, this situation will rapidly improve. This technical review is carried out with the aim of describing the current state of the art in CM research for power electronics. Reliability models for power electronics, including dominant failure mechanisms of devices are described first. This is followed by a description of recently proposed CM techniques. The benefits and limitations of these techniques are then discussed. It is intended that this review will provide the basis for future developments in power electronics CM.

Condition Monitoring for Device Reliability in Power Electronic Converters: A Review

https://shell.cas.usf.edu/~phanm//PMS.pdf

Giant magnetoimpedance materials: Fundamentals and applications

A power semiconductor device includes trenches disposed in a first base layer of a first conductivity type at intervals to partition main and dummy cells, at a position remote from a collector layer of a second conductivity type. In the main cell, a second base layer of the second conductivity type, and an emitter layer of the first conductivity type are disposed. In the dummy cell, a buffer layer of the second conductivity type is disposed. A gate electrode is disposed, through a gate insulating film, in a trench adjacent to the main cell. A buffer resistor having an infinitely large resistance value is inserted between the buffer layer and emitter electrode. The dummy cell is provided with an inhibiting structure to reduce carriers of the second conductivity type to flow to and accumulate in the buffer layer from the collector layer.

Power semiconductor device

This paper provides a detailed overview of developments in transducer materials technology relating to their current and future applications in micro-scale devices. Recent advances in piezoelectric, magnetostrictive and shape-memory alloy systems are discussed and emerging transducer materials such as magnetic nanoparticles, expandable micro-spheres and conductive polymers are introduced. Materials properties, transducer mechanisms and end applications are described and the potential for integration of the materials with ancillary systems components is viewed as an essential consideration. The review concludes with a short discussion of structural polymers that are extending the range of micro-fabrication techniques available to designers and production engineers beyond the limitations of silicon fabrication technology.

/pdf/new-materials-for-micro-scale-sensors-and-actuators-an-21qnaonn0l.pdf

New materials for micro-scale sensors and actuators An engineering review

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

Giant Magneto-Impedance (GMI) of films with a layered structure has been studied. They are Co-Si-B/Cu/Co-Si-B, Co-Si-B/Ag/Co-Si-B, and Fe-Co-Si-B/Cu/Fe-Co-Si-B with a magnetic closed-loop structure. They also have a certain magnetic configuration, for which the uniaxial anisotropy is perpendicular to both the driving current and the external field. Consequently, both reactance X and resistance R of the films change remarkably due to the external field in the frequency range from 100 kHz to 10 MHz, at which the GMI effect hardly appears in the single layer films of the same thickness. The conductivity difference between the outer and inner layers is important in order to achieve a high impedance change ratio in this frequency range. As a result, the ratios /spl Delta/Z/|Z/sub 0/|=(Z/sub maximum/-Z/sub [Hext=0]/)/Z/sub [Hext=0]/ of Co-Si-B/Ag/Co-Si-B films are 440% for a field of 9 Oe at 10 MHz, and the average sensitivity is 49%/Oe. Furthermore, /spl Delta/Z/|Z/sub 0/| of Co-Si-B/Cu/Co-Si-B and Co-Si-B/Ag/Co-Si-B films at 1 MHz is as much as 140%, and the average sensitivity reaches 15%/Oe. The sensitivity at 1 MHz is higher than that of single-layer magneto-impedance films of the same thickness by three orders of magnitude.

Giant magneto-impedance effect in layered thin films

Giant Magneto-Impedance (MI) effect of CoSiB/SiO/sub 2//Cu/SiO/sub 2//CoSiB films with line structures have been studied. Easy axes have been induced in perpendicular direction to the driving current, and the insulating SiO/sub 2/ layers have prevented the driving current from penetrating into the CoSiB layers. This structure has enabled the effective occurrence of resistance change at a frequency as low as several MHz. As a result, impedance change ratios /spl Delta/Z/Z/sub 0/=(Z/sub maximum/-Z(H/sub ext/=0))/Z(H/sub ext/=0) are much higher than that of any other layered film without insulating layers. The /spl Delta/Z/Z/sub 0/ at 20 MHz is as high as 700% at 11 Oe, and the maximum slope is 300%/Oe.

Enhancement of giant magneto-impedance in layered film by insulator separation

Pb-free high temperature solders for power device packaging

Extraction of Accurate Thermal Compact Models for Fast Electro-Thermal Simulation of IGBT Modules in Hybrid Electric Vehicles

A magnetic sensor element 1 includes a substrate 10, a conductive layer 12 of a conductive material, and a magnetic layer 11 of a magnetic material, which encloses the conductive layer 12. AC is applied to the element from a drive power source 50, and a detector 60 detects an impedance change due to an external magnetic field. The magnetic layer 11 is bestowed with magnetic anisotropy in a direction orthogonal to the direction of energization of the element 1. With the provision of the conductive layer 12 of conductive material and also with magnetic anisotropy imparted to the magnetic layer 1, the element 1 may be made a low resistivity element. A reactance change and a resistance change of the element due to an external magnetic field change, thus can be effectively detected in drive frequencies two orders of magnitude lower than in the case of a prior art magnetic sensor element. The magnetic anisotropy of the magnetic layer 11 is controlled to prevent magnetic field detection dynamic range variations with drive frequency.

Yuji Nishibe

Papers

Giant magneto-impedance effect in layered thin films

Enhancement of giant magneto-impedance in layered film by insulator separation

Pb-free high temperature solders for power device packaging

Extraction of Accurate Thermal Compact Models for Fast Electro-Thermal Simulation of IGBT Modules in Hybrid Electric Vehicles

Multilayered magnetic sensor having conductive layer within megnetic layer