bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling and Simulation of the Thermal Drift Characteristics of the Piezoresistive Pressure Sensor
Authors: Otmani R. , Benmoussa N. , Ghaffour K.
Published: October 2015

Piezoresistive pressure sensors based on Silicon have a large thermal drift because of their high sensitivity to temperature (ten times more sensitive to temperature than metals). So the study of the thermal behavior of these sensors is essential to define the parameters that cause the drift of the output characteristics. In this study, we adopted the behavior of 2nd degree gauges depending on the temperature. Then we model the thermal behavior of the sensor and its characteristics.
Effect of High Temperature Ageing on Active and Passive Power Devices
Authors: Buttay Cyril , Robutel Remi , Martin Christian , Raynaud Christophe , Dampieni Simeon , Bergogne Dominique , Chailloux Thibaut
Published: October 2015

The power devices needed to build a high-temperature converter (inductors, capacitors and active devices) have been stored at 200°C for up to 1000 hrs. Their characteristics have been monitored. Capacitors and magnetic materials from various manufacturers and technologies are tested, as well as silicon-carbide diodes. It is shown that by carefully choosing the components, it is possible to build a reliable power converter operating at high temperature.
SiC Power Switch Module
Authors: Palmer Michael J. , Johnson R. Wayne , Autry Tracy , Aguirre Rizal , Lee Victor , Scofield James D.
Published: October 2015

A hermetic, multichip power package for silicon carbide devices that will operate in a 200°C ambient and switch 50 to 100 amps has been developed. The Al2O3/MoCu structure, upon which the SiC JFETs and diodes have been attached, was designed in a manner to hermetically seal the device areas. Details of the materials and processes used to fabricate the package are discussed. Die attach, ribbon bonding and lid attach are also described.
Application of High Temperature Electronics Packaging Technology to Signal Conditioning and Processing Circuits
Authors: Riches S T , Cannon K , Johnston C , Sousa M , Grant P , Gulliver J , Langley M , Pittson R , Serban S , Baghurst D , Firmstone M
Published: October 2015

The requirement to install electronic power and control systems in high temperature environments has posed a challenge to the traditional limit of 125°C for high temperature exposure of electronics systems. The leap in operating temperature to above 200°C in combination with high pressures, vibrations and potentially corrosive environments means that different semiconductors, passives, circuit boards and assembly processes will be needed to fulfil the target performance specifications.

Bare die mounted onto ceramic and insulated metal substrates can withstand higher temperatures than soldered surface mount devices on printed circuit boards. The results of the evaluation of electronic interconnect and substrate materials that have been submitted to temperatures of 250°C for up to 2000 hours will be presented, including details on novel adhesive formulations and high temperature insulated metal substrates. The materials and processes developed have been applied to the manufacture of high temperature circuits representative of analogue signal conditioning and processing, using silicon on insulator devices and passive components mounted into HTCC packages and onto thick film on ceramic substrates. Results of the characterisation of these devices and circuits at temperatures of 250°C for up to 2000 hours will be presented.

This work forms part of the UPTEMP project has been set-up with support from UK Technology Strategy Board and the EPSRC, which started in March 2007 with 3 years duration. The project brings together a consortium of end-users (Sondex Wireline and Vibro-Meter UK), electronic module manufacturers (GE Aviation Systems Newmarket) and material suppliers (Gwent Electronic Materials and Thermastrate Ltd) with Oxford University-Materials Department, the leading UK high temperature electronics research centre.
New Battery Possibilities for High-temperature Electronics
Authors: Potanin Alexander A.
Published: October 2015

This paper covers a new type of batteries that allows the following possibilities for high-temperature applications, namely: (a) safety and full operational capability at temperatures up to 275 °C (527 °F); (b) possibility of battery recharging at high temperatures; (c) full operational capability under severe industrial conditions (vibration, shock); (d) environmental safety under transportation, storage, use and disposal; (e) safety under harsh conditions including emergency situations as a fire (this has been demonstrated with discharge tests of battery prototypes placed in a diesel fuel fire). Two technological generations of the battery prototypes have been designed, fabricated and tested over an operating temperature range of 4 °C (39 °F) to 275 °C (527 °F). The battery prototypes have been also tested under super-harsh conditions. The variety of form-factors is available for this type of batteries, including for their application in MWD/LWD tools and long-term power supply of monitoring systems in producing wells. Efforts are underway to develop the third generation of the batteries of sub-micron size (micro-batteries for microelements including high-temperature ones).
A High Temperature (> 250 °C) SiC Schottky Diode Bridge Rectifier for Extreme Environment Applications
Authors: Passmore B. S. , Stabach J. , Storkov S. , Martin D. , Falling G. , Shaw R. , McNutt T.
Published: October 2015

A high temperature, 1200 V / 5 A SiC Schottky diode bridge rectifier packaged in a 4 pin TO-254 hermetically sealed package is presented. The package consists of high temperature (> 250 °C) assembly processes and materials, including the seals, baseplate, power substrate, die attach, and passivation. The forward voltage as well as the reverse leakage characteristics as a function of temperature is presented. In addition, rectification in a 275 °C environment is demonstrated using the bridge TO-254 style package.
Microstructural Evolution and Thermal Stability Characterization of a High Temperature Die Attach Lead-Free System
Authors: Rodriguez Rogie I. , Ibitayo Dimeji , Quintero Pedro
Published: October 2015

There is a need for electromechanical devices capable of operating in high temperature environments (>200°C) for a wide variety of applications. Today's wide-bandgap (WBG) semiconductor based power electronics have demonstrated a potential of operating above 400°C, however they are still limited by packaging. Among the most promising alternative is the Au-Sn eutectic solder, which have been widely used due to its excellent mechanical and thermal properties. However, the operating temperature of this metallurgical system is still limited to ∼250°C owing to its melting temperature of 280°C. Therefore, a higher temperature resistant system is much needed, but without affecting the current processing temperature of ∼325°C typically exhibited in most high temperature Pb-Free solders.

This paper presents the development and characterization of a fluxless die attach soldering process based on gold enriched solid liquid inter-diffusion (SLID). A low melting point material (eutectic Au-Sn) was deposited in the face of a substrate, whereas a high melting point material, gold in this instance, was deposited in its mating substrate. Deposition of all materials was performed using a jet vapor deposition (JVD) equipment where thicknesses were controlled to achieve specific compositions in the mixture. Sandwiched coupons where isothermally processed in a vacuum reflow furnace. SEM and EDS were employed to reveal the microstructural evolution of the samples in order to study the interfacial reactions of this fluxless bonding process. Mechanical characterization of the each individual intermetallic phase was achieved by nanoindentation. Differential scanning calorimetry demonstrated the progression of the SLID process by quantifying the remaining low melting point constituent as a function of time and temperature. Post-processed samples confirmed the inter-diffusion mechanism as evidenced by the formation of sound joints that proved to be thermally stable up to ∼490°C after the completion of the SLID process.
High Temperature Microelectromechanical Systems Using Piezoelectric Aluminum Nitride
Authors: Griffin Benjamin A. , Habermehl Scott D. , Clews Peggy J.
Published: October 2015

We report on the efforts at Sandia National Laboratories to develop high temperature capable microelectromechanical systems (MEMS). MEMS transducers are pervasive in today's culture, with examples found in cell phones, automobiles, gaming consoles, and televisions. There is currently a need for MEMS transducers that can operate in more harsh environments, such as automobile engines, gas turbines, nuclear and coal power plants, and petroleum and geothermal well drilling. Our development focuses on the coupling of silicon carbide (SiC) and aluminum nitride (AlN) thin films on SiC wafers to form a MEMS material set capable of temperatures beyond 1000°C. SiC is recognized as a promising material for high temperature capable MEMS transducers and electronics because it has the highest mechanical strength of semiconductors with the exception of diamond and its upper temperature limit exceeds 2500°C, where it sublimates rather than melts. Most transduction schemes in SiC are focused on measuring changes in capacitance or resistance, which require biasing or modulation schemes that can withstand elevated temperatures. Instead, we are coupling temperature hardened, micro-scale SiC mechanical components with piezoelectric AlN thin films. AlN is a non-ferroelectric piezoelectric material, enabling piezoelectric transduction at temperatures exceeding 1000°C. AlN is a favorable MEMS material due to its high thermal, electrical, and mechanical strength. It is also closely matched to SiC for coefficient of thermal expansion.
Platform for Testing Sensors in HT Geothermal Wells
Authors: Normann Randy
Published: October 2015

This paper describes a logging tool designed for testing new high-temperature aircraft engine sensors deep inside hot geothermal wells. The tool is a complete logging system ready for field testing with a continuous well exposure rating of 10,000 psi and 275 °C. The tool was designed backwards giving engineers of experimental sensors complete access to the front of the logging tool for well access.

As described in this paper, Perma Works provides a simple electrical interface providing power, sensor reference voltage and data channels. Sensor engineers can transmit their data via Perma Works open data channels OR access the logging cable to monitor sensor dynamic signals.

Surface software is easy to modify to record the sensor readings during the well log. The reader will learn more about geothermal logging tools and how the Perma Works tool can aid aircraft engine sensor developers open new markets by proving their sensors in some of the harshest conditions on Earth.
The melting-point increase of Sn-Bi solder joint by Cu particles addition
Authors: Mokhtari Omid , Nishikawa Hiroshi
Published: October 2015

Solder is one of the main materials for interconnects in microelectronic packaging and Sn-Pb solder alloys have been the most common solders for a long time. However, the use of Pb has been very limited because of the negative effects of Pb on the human health and the environment. Therefore, Sn-Bi based solders were recommended as a low temperature solder to replace Sn-Pb solders because of their low temperature melting point. Low temperature melting point of Sn-Bi solders reduces the damage due to the thermal effect of the high temperature on the mechanical properties of the joints. However, its low melting point allows Sn-Bi solders to be used in a limited range of applications. The objective of this research is to enable the Sn-Bi based solders to be used in higher temperature applications. Therefore, this research represents how to increase the melting point of the solder joint after the reflow while keeping the advantage of low melting point before the reflow.

The method which was tried in this research in order to increase the melting point of the Sn-Bi solder after the reflow is to convert the whole Sn phase of the solder to Cu6Sn5 and Cu3Sn intermetallics by adding Cu particles to the solder before the reflow. The binary Sn-Bi and Sn-Bi + 30 wt. %Cu particles were investigated in this research. Scanning electron microscopy (SEM) and electron probe micro-analyzer (EPMA) were used to examine the microstructure of the solder parts after the reflow. Various reflow profiles were tried to enable the whole Sn phase react with the added Cu particles. Differential scanning calorimetry (DSC) was also used in this research to investigate the melting point of the solder parts. The results after the reflow at 230°C for 50 min show that almost all Sn phase was successfully converted to the Cu6Sn5 and Cu3Sn phase.
Effect of Sn Component Surface Finish on 92.5Pb-5Sn-2.5Ag
Authors: Schoeller Harry , Anselm Martin , Khan Imran , Cotts Eric
Published: October 2015

This work investigates the effect of Sn component surface finish on the melting temperature, microstructure, and mechanical behavior of 92.5Pb-5Sn-2.5Ag. 92.5Pb-5Sn-2.5Ag was doped with up to 7% Sn to simulate the final composition of a joint after reflow with a component having Sn surface finish. Differential Scanning Calorimetry (DSC) was used to measure the change in matrix liquidus temperature with increasing Sn concentration. Microstructure evaluation and mechanical tests were carried out on 20 mil solder spheres reflowed on high temperature polyimide test coupons. Solder joints of each composition were cross-sectioned to examine the microstructure. The area fraction of β-Sn and Ag3Sn was quantified for each composition using image analysis software. Shear and isothermal fatigue tests of individual solder joints with varying Sn concentrations were conducted at room temperature. Joints were also sheared at 200°C after aging for 1024hrs at 200°C to simulate a downhole environment. The failed interfaces were examined to determine the mode of failure. Beyond providing guidance for surface finish selection, this work examines the microstructure and mechanical behavior of 92.5Pb-5Sn-2.5Ag as a function of Sn concentration and temperature. An understanding of the microstructure-mechanical performance relationship will aid in the development of new alloys for high temperature applications.
Design and Manufacturing of a Double-Side Cooled, SiC based, High Temperature Inverter Leg
Authors: RIVA Raphaël , BUTTAY Cyril , LOCATELLI Marie-Laure , BLEY Vincent , ALLARD Bruno
Published: October 2015

In this paper, we present a small (25×25×3 mm3) power module that integrates two silicon-carbide (SiC) JFETs to form an inverter leg. This module has a “sandwich” structure, i.e. the power devices are placed between two ceramic substrates, allowing for heat extraction from both sides of the dies. All interconnects are made by silver sintering, which offers a very high temperature capability (the melting point of pure silver being 961 °C). The risk of silver migration is assessed, and we show that Parylene-HT, a dielectric material that can sustain more than 300 °C, can completely coat the module, providing adequate protection.
Digital and Analogue Integrated Circuits in Silicon Carbide for High Temperature Operation
Authors: Ramsay E.P , Clark D.T. , Cormack J.D. , Murphy A.E. , Smith D.A , Thompson R.F. , Young R.A.R. , Finney S.
Published: October 2015

A need for high temperature integrated circuits is emerging in a number of application areas. As Silicon Carbide power discrete devices become more widely available, there is a growing need for control ICs capable of operating at the same temperatures and mounted on the same modules. Also, the use of high temperature sensors, in, for example, aero engines and in deep hydrocarbon and geothermal drilling applications results in a demand for high temperature sensor interface ICs.

This paper presents new results on a range of simple logic and analogue circuits fabricated on a developing Silicon Carbide CMOS process which is intended for mixed signal integrated circuit applications such as those above.

A small family of logic circuits, pin compatible with the 74xx series TTL logic parts, has been designed, fabricated and tested and includes, for example, a Quad Nand gate and a Dual D-type flip-flop. These have been found to be functional from room temperature up to 400°C. Analogue blocks have been investigated with a view to using switched capacitor or autozero techniques to compensate for temperature and time induced drifts, allowing very high temperature operation.
Silicon Carbide High Temperature Operational Amplifier
Authors: Vert Alexey , Chen Cheng-Po , Patil Amita , Saia Rich , Andarawis Emad , Kashyap Avinash , Zhang Tan , Shaddock Dave , Shen Zhenzhen , Johnson R. Wayne , Normann Randy
Published: October 2015

Development of silicon carbide operational amplifier offers an attractive alternative building block for the replacement of silicon and silicon-on-insulator analog circuits in harsh environment applications. NMOS-based enhancement mode silicon carbide device technology was utilized to demonstrate feasibility of operational amplifiers for use in harsh environment applications. This study reports on the results of characterization of operational amplifiers at room temperature and high temperatures up to 350°C. The development of high temperature packaging techniques enabled assembly of a functional oscillator board tested up to 350°C. A test fixture with high temperature sockets enabling quick swap of operational amplifiers is also discussed as an important tool in high temperature electronics research and development.
Optimization of a Ceramic Circuit Board Clamp
Authors: Glowka David A. , Normann Randy A.
Published: October 2015

This paper documents the design optimization of a board-mounting system for securing a ceramic or other heavy circuit board to the electronics chassis in a wireline logging tool. A clamp fixes the extreme lower end of the circuit board to the chassis while allowing the board and chassis to undergo differential thermal expansion above that fixed point, through the use of sliding board mounts. After developing equations that describe the stress, deflection, and thermal expansion of the clamp/board assembly, they are used to select the geometry and material options available in the design. Results of a parametric study are presented that demonstrate how material selection determines whether the clamping pressure on the circuit board improves or degrades at elevated temperature, and how the geometries of the clamp components affect the magnitudes of the forces, deflections, and setting torque of the clamp.
500°C Silicon Carbide MOSFET-Based Integrated Circuits
Authors: Chen Cheng-Po , Ghandi Reza , Yin Liang , Zhu Xingguang , Yu Liangchun , Arthur Steve , Sandvik Peter
Published: October 2015

In this work silicon carbide MOSFET based integrated circuits such as operational amplifier. 27-stage ring oscillator and CMOS-based inverter have been designed, fabricated and successfully tested at high temperatures. Silicon carbide MOSFETs remained fully operational from room temperature to 500°C with stable I-V characteristics. Also 27-stage ring oscillator, operational amplifier and CMOS inverter tested and shown to be functional up to 500°C, with relatively small performance change between 300°C and 500°C. High temperature reliability evaluation of these circuits demonstrate stable operation and both the ring oscillator and OpAmp survived more than 100 hours at 500°C.
Pressureless Sintering Progression of a Silver Nanoparticle Attach Material Via Micrographic Analysis
Authors: Molina Manuel , Velasco Andrés , Otaño Wilfredo , Quintero Pedro O.
Published: October 2015

Increasing demand for reliable power electronics for harsh environments, together with regulations in packaging materials, have resulted in new efforts in research and development in this area. The need for an attach material that can be processed at a relatively low temperature yet able to withstand the expected high temperature operating conditions is of particular interest. In this work, sintering of silver nanoparticles is examined through microstructural evolution. An image analysis technique was developed and used to analyze SEM micrographs. Results showed a strong correlation between characteristic structural features and the degree of nanoparticle arrangement prior to the sintering stage. The initial ordering of the nanopowder within the paste, and the availability of smaller particles acting as satellites were found to be pivotal for the progression of the sintering as observed from the formation of continuous structures at a larger length scale. The advancement presented in this work is a useful tool to analyze the progression of the sintering mechanism which can lead to a better understanding and control of particle coagulation and coordination which may result in properties close to that of the bulk material.
The Effects of Repeated Refresh Cycles on the Oxide Integrity of EEPROM Memories at High Temperature
Authors: Reed Lynn , Reddy Vema
Published: October 2015

Data retention in stored-charge based memories, such as Flash and EEPROMs, decreases with increasing temperature. Compensation for this shortening of retention time can be accomplished by refreshing the data using periodic erase-write refresh cycles, although the number of these cycles is limited by oxide integrity. An alternate approach is to use refresh cycles consisting of a rewrite only cycles, without the prior erase cycle. The viability of this approach requires that this refresh cycle induces less damage than an erase-write cycle. This paper studies the effects of repeated refresh cycles on oxide integrity in a high temperature environment and makes comparisons to the damage caused by erase-write cycles.

The experiment consisted of running a large number of refresh cycles on a selected byte. The control group was other bytes which were not subjected to refresh only cycles. The oxide integrity was checked by performing repeated erase-write cycles on each of the two groups to determine if the refresh cycles decreased the number of erase-write cycles before failure. Data was collected from multiple parts, with different numbers of refresh cycles, and at temperatures ranging from 25C to 190C.

The experiment was conducted on microcontrollers containing embedded EEPROM memories. The microcontrollers were programmed to test and measure their own memories, and to report the results to an external controller. This greatly simplified the hardware setup, since only six wires were required to operate and test the memories of 77 microcontrollers. It also allowed data collection from the microcontrollers while the experiment was in progress.

Data is presented showing that refresh cycles do not have a significant impact on oxide integrity. This result shows that the refresh cycle approach will not degrade the oxide and suggests that it will provide a mechanism to extend data retention at high temperatures without affecting device reliability.

The data also showed a bimodal distribution of the number of erase-write cycles necessary to damage the oxide. Although the cause of this distribution is not yet understood, it may provide an additional means to significantly improve EEPROM reliability through appropriate screening.
Thermo-mechanical simulation of sintered Ag die attach for high temperature applications
Authors: Sousa M.F. , Dijk M.v. , Walter H. , Weber C. , Hutter M. , Oppermann H. , Wittler O. , Lang K.D.
Published: October 2015

Diverse electronic packages operate under exceptionally harsh environments, which require extended lifetimes, presenting a significant challenge for the microelectronics community. Operating temperatures above 200°C together with high pressures, vibrations and potentially corrosive environments implies that some technical issues regarding the development of electronic systems that will operate at such high temperature remain. Recent technology has been emerging for high temperature applications, capable of withstanding up to 300°C. Sintered Ag is one potential candidate for die attachment for extreme environments. The present work aims to develop understanding of how and why attach materials for Si dies degrade/fail under harsh environments by investigating sintered Ag material. A 2D axis-symmetric die attach model, commonly used to represent microelectronic package assemblies, was developed. The FE model provided a good understanding of the effect of single parameter variation of different leadframe materials, sintered Ag and chip thicknesses. The effect of the sintered Ag thickness on the plastic strain was very little. Furthermore, on the chip side, the local thermal mismatch between the Si die and the sintered Ag was the most important loading factor. Also, thicker chips generated higher stresses in the die.
GaN Power Module with High Temperature Gate Driver and Insulated Power Supply
Authors: Perrin Rémi , Bergogne Dominique , Martin Christian , Allard Bruno
Published: October 2015

Emerging GaN power switches show advantages for integration in power modules at high temperature and/or high efficiency. These modules are good candidates for embedded power converters in harsh environment such as three phase inverters for Electro-Mechanical Actuators (EMA) in the vicinity of internal combustion engines. The power range is usually within 1 to 5 kW, extending sometimes up to 50 kW, using a high voltage DC bus (HVDC) that is usually comprised between 200 V and 600 V. For aeronautical applications, GaN power switches could challenge SiC transistors for their high switching speed, hence reduced switching losses, therefore lower embarked mass. For automotive applications, it is the relative promise for lower cost per Amp that is pushing this technology up. This is why a project joining GaN device conception, power module development and gate driver optimization using high temperature technologies was set-up. This paper presents the first practical results: a functional GaN power inverter-leg driven by a specific high temperature gate driver with signal and power insulation. This building block requires an auxiliary DC supply with a input voltage of 14 V or 28 V and an external PWM control signal. Current rating is 20 A and breakdown voltage is 200 V.
Integrated Protection Circuits for an NMOS Silicon Carbide Gate Driver Integrated Circuit
Authors: Shepherd Paul , Kaiser Dillon , Glover Michael , Perez Sonia , Francis A. Matt , Mantooth H. Alan
Published: October 2015

Recent work has been done to build a Silicon Carbide (SiC) gate driver IC for use with a 1,200V SiC power MOSFET. Protection circuits form an important part of the complete gate driver/power device system. Under-voltage lockout (UVLO) protection disables the gate driver when power supplies are insufficient to turn the power device fully on. Desaturation detection provides protection to the power device by recognizing over-current conditions and disabling the gate driver for a set duration. The protection circuits described in this paper are integrated with a novel SiC gate-driver architecture utilizing discrete 20 V and 40 V power supplies. Two separate UVLO circuits monitor these power supplies while being powered by the 20 V supply. The desaturation detection circuit ensures that the power device is in its safe operating area. The desaturation detection circuit is designed to work with a 20A SiC MOSFET in less than 500ns, while avoiding false triggering on leading-edge spikes. Bench test results of the two UVLOs and desaturation detection circuits were captured and are compared to simulated results.
High Temperature Analog-to-Digital Converter Reliability Testing
Authors: Ohme Bruce W. , Larson Mark R.
Published: October 2015

Initial test results have been previously reported for a high-temperature (225°C) 12-bit analog-to-digital converter (HTADC12) fabricated using a production high-temperature silicon-on-insulator (SOI) CMOS process and assembled in hermetically sealed ceramic packages (ref. 1). Reliability test results for the HTADC12 are presented including parametric and functional test results from 1500 hours of dynamic life test at 250°C as well 1000 temperature cycles from −65°C to 200°C. Results of post-stress wirebond, and die bond testing are also provided.
High Temperature Laminate Characterization
Authors: Shaddock David , Yin Liang
Published: October 2015

Printed circuit boards have been reported to have limited lifetime at 200 to 250°C. Characterization and modeling high temperature laminates for application at 200 to 250°C was conducted to better quantify the mean lifetime using accelerated testing of key functional parameters. Life testing and model development was applied for via cyclic life, peel strength, and weight loss. Four high temperature laminates consisting of 2 types were evaluated. Via lifetime was characterization using Interconnect Stress Test (IST) coupons. Peel strength was tested using IPC IPC-TM-650 method 2.4.8c. Weight loss was characterized using isothermal aging. Comparison of lifetime is made between the laminate samples.
Temperature dependence of high dielectric strength potting materials for medium voltage power modules
Authors: O'Neal Chad B. , Passmore Brandon , Feurtado Matthew , Stabach Jennifer , McNutt Ty
Published: October 2015

Voltage isolation inside power modules is paramount for functional and reliable operation. The dielectric potting materials are further stressed as the overall size of these modules is reduced due to size, weight, and cost considerations while the operating voltage of the modules continue to increase. Voltage ratings of silicon carbide device technologies will continue to increase above 6.5 kV into the tens of kilovolts in the future. Silicon carbide devices are also often operated at higher junction temperatures in order to take advantage of the high temperature capabilities of the material. As the module temperature increases, the dielectric strength of insulating materials in the module tend to decrease, which is a serious consideration for a compact power module operating at many kilovolts. A plurality of high temperature rated, high dielectric strength potting materials were tested for voltage breakdown and leakage current up to 30 kV and 250 °C. A range of different materials, both conventional and novel, were tested including silicones and parylene. Materials were selected with a dielectric strength greater than 500 V/mil, an operating temperature range of 200 °C or higher, and low hardness and modulus of elasticity with the intent of demonstrating the capability of blocking 20 kV or more in a reasonable thickness. A custom test setup was constructed to apply the voltage to test samples while measuring the breakdown voltage and simultaneous recording the leakage current. Test coupons were designed to provide a range of dielectric thicknesses over which to test the dielectric strength. Although voltage isolation may increase with increased dielectric thickness, the V/mil isolation rate often decreases. The performance degradation of these materials over temperature is plotted and deratings are suggested for use with medium voltages at operating temperatures above 175 °C.
230C Hermetically Sealed SMD Tantalum Capacitors
Authors: Zednicek T. , Biler M. , Petrzilek J. , Pinwill I. , Faltus R.
Published: October 2015

Certain electronic applications, such as oil and gas exploration drilling, are continuously demanding ever higher operating temperatures. Recently operating temperature requirements have increased from 200°C to 230°C with an increased operating life from hours to one thousand hours and beyond. This need is linked with the continuous development of oil drilling heads and sensors and their use for deeper drilling or drilling in more difficult geological conditions. Capacitors with high capacitance value are a common part of the electronic boards used in these applications, but over 125°C/175°C, available capacitor choice is very limited. Tantalum SMD capacitor technology has proved its reliability in operation up to 175°C and there is a limited choice of special designs up to 200°C. Long life wet tantalum capacitors up to 200°C are available from multiple sources, or up to 230°C with reduced operational life from a single source.

Hermetically sealed MnO2 tantalum capacitors have demonstrated their ability to offer unique long life stability at 230C combined with solid, stable and robust design. [1]. The next testing and development presented in this paper discusses the basic behavior of the solid hermetically sealed MnO2 tantalum capacitor above 200°C. A certain type of “wear out” has been observed in a longer exposure at 230°C depending on applied voltage. Nevertheless, the basic capability of the capacitor meets the “best in class” requirement for 230°C 1000hours continuous operating life with 50% voltage derating. The paper discusses and summarizes the “wear out” phenomenon observed at temperatures above 200°C on these capacitors and impact of different voltage derating to operational life at 230°C .
Advanced Ceramic Capacitor Solutions for High Temperature Applications
Authors: Gurav Abhijit , Xu Xilin , Magee Jim , Staubli Paul , Bultitude John , Ashburn Travis
Published: October 2015

For high temperature applications at 150°C or above, such as those in electronics for down-hole drilling, geothermal energy generation and power electronics, a robust dielectric material is necessary for capacitors. Ceramic capacitors using X7R and X8R type dielectrics are designed for applications up to 125°C and 150°C, respectively. At temperatures above 150°C, these X7R/X8R types of ceramic capacitors typically suffer from degradation of reliability performance and severe reduction in capacitance, especially when bias is applied. Recently, a Class-I dielectric material has been developed using Nickel electrodes for high temperature application up to 200–250°C. Due to its linear dielectric nature, this material exhibits highly stable capacitance as a function of temperature and voltage. This paper will report electrical properties and reliability test data on these Class-I type ceramic capacitors in SMD chip and leaded configurations at 150–200°C and above, and discuss possible mechanisms behind the robust reliability of this high temperature dielectric.
Long Term Demonstrated Performance Characteristics for Improved High Temperature Ceramic Capacitors Intended for Use in Extreme, Harsh Environments
Authors: Syammach Mustafa A. , Habibi Mustapha , Syammach Fauzi A.
Published: October 2015

Availability of a reliable and consistent source for high temperature ceramic capacitors has been an ongoing issue for design engineers for the purpose of developing product for applications up to and including +300°C. The general practice has been to de-rate standard X7R ceramic capacitors for high temperature applications and settle for a device characterized by a significant reduction in the critical performance features related to capacitance value, operating voltage, insulation resistance and breakdown voltage, not to mention a substantial roll off in temperature coefficient above +150°C. In addition, the need to provide coated and / or leaded options also presents additional concerns related to operational integrity.

This paper presents packaging options, life tests reliability data and compares performance characteristics for a unique high K, high temperature ceramic capacitor, to the more traditional options. This approach utilizes leading edge, Class II dielectric and packaging materials that have been specifically developed for use at +300°C and then benefit from enhanced reliability when operated at lower temperatures. As shown in this paper, capacitors manufactured with this dielectric material exhibit much higher capacitance per unit volume and significant improvements in insulation resistance, without having to sacrifice mechanical strength, voltage rating or long term reliability.
Advanced Applications of High Temperature Magnetics
Authors: Fraley John R. , Cilio Edgar , Western Bryon
Published: October 2015

In recent years, high temperature magnetic structures have been developed and used for inductors and transformers in high temperature applications ranging from power electronics to wireless telemetry systems. Research in the high temperature magnetics field has led to the development of more advanced magnetic structures that can enable diverse applications ranging from regulators to amplifiers, with far reaching implications for the high temperature electronics community. Current high temperature electronics have shown potential in lab and rig tests, but high temperature electronics systems suffer from the relatively limited lifetime of the semiconductor devices themselves. The advanced magnetics discussed in this paper can be designed to have extreme lifetime capabilities even at elevated temperatures, and as such can have an immediate impact on the implementation of true field deployable high temperature electronic systems. Aerospace, power generation, and automotive industries may especially benefit from this technology, as significant advances in health monitoring and active engine control will be enabled by these advanced magnetic structures.

A theoretical understanding of these advanced magnetic structures is necessary for initial design and feasibility, while the true development and implementation of this technology depends on state of the art high temperature packaging approaches. By combining high temperature, grain-oriented magnetic materials along with high temperature packaging processes, APEI, Inc. has created advanced high temperature magnetic systems that indicate the technology described in this paper is a viable one, with applications across a wide range of high temperature electronics systems.
High-Temperature Characterization and Comparison of 1.2 kV SiC Power Semiconductor Devices
Authors: DiMarino Christina , Chen Zheng , Boroyevich Dushan , Burgos Rolando , Mattavelli Paolo
Published: October 2015

Focused on high-temperature (200 °C) operation, this paper seeks to provide insight into state-of-the-art 1.2 kV Silicon Carbide (SiC) power semiconductor devices; namely the MOSFET, BJT, SJT, and normally-off JFET. This is accomplished by characterizing and comparing the latest generation of these wide bandgap devices from various manufacturers (Cree, GE, Rohm, Fairchild, GeneSiC, and SemiSouth). To carry out this study, the static and dynamic characterization of each device is performed under increasing temperatures (25–200 °C). Accordingly, this paper describes the experimental setup used and the different measurements conducted, which include: threshold voltage, current gain, specific on-resistance, and the turn-on and turn-off switching energies of the devices. The driving method used for each device is also detailed. Key trends and observations are reported in an unbiased manner throughout the paper and summarized in the conclusion.
High Temperature Characterization and Reliability Data of Key Semiconductor Technologies for Power and Control Devices
Authors: Wilkinson Brian , Walters Kent , Ellerman Paul
Published: October 2015

An increasing number of extreme temperature operating applications require temperatures that can range from −65°C to 300°C, driving semiconductor suppliers to innovate new analog, digital, and mixed-signal solutions based on technologies including SiC, GaN, Si, SOI and CMOS.

In addition, the paper will briefly highlight Microsemi's real-world results including characterization and reliability data on discrete power products including diodes and bridge rectifiers, and integrated circuits for demanding applications including down-hole drilling, commercial aviation, power sub-systems and power distribution in military vehicles.
1200V 20A SiC BJTs operating at 250°C
Authors: Lindgren Anders , Domeij Martin , Hjort Tomas
Published: October 2015

Silicon carbide (SiC) bipolar junction transistors (BJTs) are normally-off devices which can block high voltages at high temperature operation. The SiC BJTs can be switched very fast with low losses [2] compared to BJT's made in silicon (Si), and can be operated at temperatures up to and above 250 °C. Vertical 1200V 20A rated high temperature capable NPN SiC BJTs were fabricated and packaged in a high-temperature capable metal package of the type TO-258. The transistors were characterized both statically and in terms of switching. A SPICE model was developed for the transistors, including the parasitic capacitances of the internal pn-junctions, as well as temperature dependence of the current gain and the collector series resistance. Switching measurements were performed showing VCE voltage rise- and fall-times in the range of 20–30 ns. The switching behavior is in qualitative agreement with SPICE simulations.
Package Reliability of the SiC Power Modules in Harsh Environments
Authors: Lang Fengqun , Yamaguchi Hiroshi , Sato Hiroshi
Published: October 2015

To evaluate the package reliability of the SiC power modules in harsh environments, the SiC Schottky Barrier Diodes (SBDs) were die bonded to the Si3N4/Cu/Ni(P) substrate with Au-Ge eutectic solder using a vacuum reflow furnace. The Si3N4/Cu/Ni(P) substrates are active metalized copper (AMC). The bonded samples were isothermally aged at 330°C and tested under thermal cycling conditions in the temperature range of −40–300°C in air. During the isothermal aging, cracks of the Ni(P) layer developed, resulting in oxidation of the Cu power path. Decrease in the die bond strength and increase in the electrical resistivity were observed due to the Cu power path oxidation and the growth of the Ni-Ge intermetalic compound (IMC) in the joint. Under the thermal cycling conditions, the metallization of the substrate suffers from serious surface roughness, which greatly degrades the die-attach reliability. The Al electrode was found to seriously exfoliate from the SiC-SBDs due to the thermal stress. After 521 cycles, almost all the Al electrode exfoliated form the anode. Benefit from the excellent mechanical properties of Si3N4, no detachment of the Cu layer was observed from the Si3N4 substrate after 1079 cycles, while the Cu layer detached from the AlN substrate only after 12 cycles.
High Temperature Reliability Investigations of EEPROM Memory Cells Realised in Silicon-on-Insulator (SOI) Technology
Authors: Grella K. , Vogt H. , Paschen U.
Published: October 2015

Microelectronic manufacturing progresses not only towards further miniaturisation, but also application fields tend to become more and more diverse. Recently there has been an increasing demand for electronic devices and circuits that function in harsh environments such as high temperatures. Under these conditions, reliability aspects are highly critical and testing remains a great challenge. A versatile CMOS process based on 200 mm thin film Silicon-on-Insulator (SOI) wafers is in production at Fraunhofer IMS. It features three layers of tungsten metallisation for optimum electromigration reliability, voltage independent capacitors, high resistance resistors and single-poly-EEPROM cells. Non-volatile memories such as EEPROMs are a key technology that enables flexible data storage, for example of calibration and measurement information. The reliability of these devices is especially crucial in high temperature applications since charge loss is drastically increased in this case. The behaviour of single-poly-EEPROM cells, produced in the process described before, was evaluated up to 450 °C. Data retention tests at temperatures ranging from 160 °C to 450 °C and write/erase cycling tests up to 400 °C were performed. The dependence of write/erase cycling on both temperature and tunnel oxide thickness was studied. These data provide an important foundation to extend the application of high temperature electronics to its maximum limits. The results show that EEPROM cells can be used for special applications even at temperatures higher than 250 °C.
A performance comparison of normally-off and normally-on SiC JFETs toward use in high-temperature power modules
Authors: Schrader R. , Speer K. , Casady J. , Bondarenko V. , Sheridan D.
Published: October 2015

The high-temperature static and dynamic characteristics of the new 1200 V, 45 mΩ, 9 mm2 depletion-mode SiC vertical trench junction field-effect transistor (vtJFET) are compared with those of a 1200 V, 50 mΩ, 9 mm2 enhancement-mode SiC vtJFET. It is shown that both devices are fully capable of high-temperature operation and that each type has its own unique advantages. For applications operating in extreme high-temperature environments, the larger saturation current (~2.5x) and lower on-state resistance (~150 mΩ at 250 °C) of the depletion-mode SiC vtJFET provide very attractive performance at temperatures beyond silicon's fundamental limitations. In addition, operating the normally-on vtJFET at VGS less than 2 V reduces the gate drive's current requirements to a negligible level, which is an important design factor for high-temperature power modules that use multiple die in parallel.
HADES®: a High-Temperature Isolated Gate Driver Solution for SiC-based Multi-kW Converters
Authors: Doucet Jean-Christophe , Saib Aimad , Mourad Christian , Piette François , Vanzieleghem Etienne , Delatte Pierre
Published: October 2015

This paper presents HADES® Gate Driver, a new solution that efficiently drives Silicon-Carbide (SiC) devices in multi-kW converters. It discusses how it allows taking full advantage of SiC technology by placing the gate driver circuits very close to the power transistors: The resulting lower parasitic inductances enable faster switching times and subsequently higher efficiency. Higher operating temperature for both the gate driver and the power transistors also translate into considerable reduction of complexity, size and weight of the system, in particular of the cooling systems. Finally, the paper describes how HADES® reference design is built from a new chipset especially developed for this purpose and designed to operate up to 225°C: THEMIS, ATLAS and RHEA.
An Analysis of OTP ROM Programmable Devices in 1.0um SOI CMOS
Authors: Moody Paul W. , Soares Marshall
Published: October 2015

Recent approaches to provide non-volatile memory for high temperature applications have been performance limited, either by data retention in SOI EEPROM devices, or by using processes not well suited to high temperature. This work examines SOI devices that may provide reliable OTP solutions. Anti-fuse and fuse approaches are analyzed to determine programmability, suitability for in-situ programming, density implications, and data retention.
High Temperature Performance of Oxide Film Capacitors
Authors: Jamison Keith D. , Balliette Bill
Published: October 2015

Film capacitors that perform well at temperatures exceeding 150°C and have energy densities in excess of 1 J/cm3 are an enabling technology for many applications in automotive, geophysical exploration, aerospace, and the military. To address this need Faradox Energy Storage, Inc. has produced and is testing high temperature film capacitors fabricated using amorphous oxides (OxFilm™) as the dielectric material. The capacitors are made by depositing thin films of an oxide dielectric on both sides of a double metalized polyimide substrate to form dielectric-coated electrodes. Currently Faradox is producing 2″ long, 1/4″ diameter 2 uF, 100 VDC capacitors using silicon dioxide as the dielectric material.

In this paper we present test data demonstrating that OxFilm capacitors have relatively stable properties over a wide temperature range. Measurements include capacitor testing at different 3rd Party test facilities and internal testing using a variety of test conditions including:Life testing at 200 and 250°C for over 1000 hours with measurements of capacitance, leakage, dF and ESR.Capacitance versus voltage, temperature and frequencyImpedance, ESR, and dF versus frequency and temperature and voltageData will also be presented that show these capacitors can be cycled between 0°C and 200°C without degrading their performance. Work is ongoing to obtain additional test data with more statistically significant numbers of capacitors.