bluuebunny/crossref_metadata_2025 huggingface dataset:
Joining of Sintered Alumina Substrates and LTCC Green Tapes via Cold Low Pressure Lamination
Authors: Hambuch Michael , Gora Frieder , Beart Karin , Wittmann Frieder , Roosen Andreas
Published: October 2015

In microelectronics there is a continuous trend for devices of higher integration and improved heat dissipation. For the manufacture of ceramic based microelectronic devices the following technologies can be applied. Thick-film hybrid technology uses sintered ceramic substrates, mostly Al2O3, which are screen printed with functional pastes, followed by firing at 850 °C. Alumina substrates provide very good heat conductivity (25 W/mK), but there are only two sides to carry a metallization. An improved miniaturization can be accomplished by multilayer systems using the LTCC technology. LTCC devices are manufactured by screen-printing, stacking and lamination of ceramic green tapes, followed by co-firing. A drawback of LTCCs is their low heat conductivity (3 W/mK) due to their high glass content. By combining hybrid and LTCC technology the advantages of both methods like good thermal conductivity and high multilayer integration, can be joined.

Because the failure rate is too high to laminate green tapes on sintered ceramic substrates via thermo compression, Cold Low Pressure Lamination (CLPL) has been used as an alternative lamination process. CLPL is a lamination method, where the joining of the components is performed at room temperature by application of very low pressure (<5 MPa) by using a double sided adhesive tape. During heat treatment the adhesive film keeps the tapes together until the adhesive is completely decomposed; during further temperature increase the tapes are joined by sintering. The paper describes the materials used and processing steps to join the sintered material with the green tapes and discusses effects which occur during firing. These effects like edge curl and crack formation are mainly due to stresses which occur during constrained sintering. Their control can be influenced by changing process parameters.
A 10 MHz to 80 GHz BGA Transition from Chip to LTCC Interposer for Chip Scale Packages
Authors: Thrasher Bradley A. , McKinzie William E. , Nair Deepukumar M. , Smith Michael A. , Beikmohamadi Allan , Hughes Elizabeth D. , Parisi James M.
Published: October 2015

Presented here are the design, fabrication, and measurement results of a low temperature cofired ceramic (LTCC) chip-to-interposer transition utilizing a flip-chip ball grid array (BGA) interconnect that provides excellent electrical performance up to and including 80 GHz. A test board fabricated in LTCC is used as the interposer substrate and another smaller LTCC part is used as a surrogate chip for demonstration purposes. The BGA chip-to-interposer transition is designed as a back-to-back pair of transitions with an assembly consisting of an LTCC interposer, an LTCC test chip, and a BGA interconnect constructed with 260 μm diameter polymer core solder balls. The LTCC material employed is DuPont™ GreenTape™ 9K7. Full-wave simulation results predict excellent electrical performance from 10 MHz to 80 GHz, with the chip-to-interposer BGA transition having less than 0.5 dB insertion loss at 60 GHz and less than 1 dB insertion loss up to 80 GHz. In an assembled package (back-to-back BGA transitions), the insertion loss was measured to be 1 dB per transition at 60 GHz and less than 2 dB per transition for all frequencies up to 80 GHz.
Cobalt oxide addition effects on the microstructure and electronic properties of CuZn ferrites
Authors: Hsiang Hsing-I , Tu Jui-Huan , Kuo Wen-Chin , Tsai Chi-Yao , Mei Li-Then
Published: October 2015

The effects of cobalt oxide addition on the microstructure and electrical properties of CuZn ferrites were investigated. CuZn ferrites with compositions of (CuO)0.2(ZnO)0.8(Co3O4)x/3 (Fe2O3) 0.986-2x; x = 0 , 0.02, 0.04, 0.08, 0.1 were synthesized using a solid state reaction. It was observed that the addition of cobalt will change the amounts and distribution of Cu2+, Cu+, Fe2+, and Fe3+ in the grain and grain boundary. The segregation of copper ions at the grain boundary was observed as the substitution of cobalt was increased. Moreover, as the x value was increased above 0.04, second phases of CuO and ZnO were found. The different amounts and distribution of Cu2+, Cu+, Fe2+, and Fe3+ in the bulk and grain boundary for samples added with different amounts of cobalt changed the conductivity activation energies of the bulk and grain boundary, and hence affected the space polarization and dielectric properties.
Towards hydrogen detection at room temperature with printed ZnO nanoceramics films activated with halogen light
Authors: NGUYEN Van Son , JUBERA Véronique , GARCIA Alain , LUCAT Claude , DEBEDA Hélène
Published: October 2015

Though semiconducting properties of ZnO have been extensively investigated under hazardous gases, research is still necessary for low-cost sensors working at room temperature. Study of printed ZnO nanopowders based-sensor has been undertaken for hydrogen detection. A ZnO paste made with commercial nanopowders is deposited on interdigitated Pt electrodes and sintered at 400°C. ZnO layer structure and morphology are first examined by XRD, SEM and emission/excitation spectra prior to the study of the effect of UV-light on the electrical conduction of the semiconductor oxide. Then, the response to hydrogen shows that low UV-light provided by a halogen light enhances gas sensitivity and allows detection at room temperature with sensitivity equivalent to those obtained in dark condition at 150°C. A sensitivity S≈44% is obtained for 300 ppm hydrogen at room temperature under halogen lamp illumination whereas a sensitivity S≈38% is measured at 150°C in the dark. Moreover, it is demonstrated that very low UV-light power (15 μW/mm2) provided by the halogen lamp is sufficient to give sensitivities as high as those obtained with UV LED (7.7 mW/mm2). These results are comparable to those obtained for 1 or 2D ZnO nanostructures working at room temperature or at temperature until 250 °C.
Thick Film Pastes for Power Applications
Authors: Modes Christina , Bawohl Melanie , Langer Jochen , Reitz Jessica , Eisert Anja , Challingsworth Mark , Garcia Virginia , Groman Sarah
Published: October 2015

Electronic circuits made by thick film technology are commonly used today in electronic circuitry for automotive applications. Densely packed multi-layer hybrid circuits are very well established for motor and transmission management in standard gasoline fuelled vehicles. As automotive technology shifts from mechanical systems to electrical systems and toward more electrically driven vehicles, such as hybrid electric vehicles and full electric vehicles, thick film systems need to be adapted to fit the challenges and needs of these new applications.

The following is a description of a new set of thick film pastes, both precious and base metal, which have attributes and performance suitable for power electronics in automotive applications. The materials provide a means to use common thick film technology to build power circuits to meet the new needs, such as high current carrying capacity and thermal dissipation.
Biocompatible low temperature co-fired ceramic for biosensors
Authors: Luo Jin , Eitel Richard
Published: October 2015

Low temperature co-fired ceramic (LTCC) electronic packaging materials are applied for their ease of fabrication, three dimensional features and integration of multifunctional component, such as optical and electrical functions. For these reasons LTCC is attractive for biomedical microfluidics and Lab-on-a-Chip systems. However, commercial LTCC systems, optimized for microelectrics applications, are not designed for biomedical applications, and have unknown cytocompatibility. In the current work, LTCC has been developed starting with materials of known composition and biocompatibility. The developed LTCC, fabricated from a lime silicate glass and pure alumina, exhibits low sintering temperature (<1000°C) and high density. Alumina reacts with the glass and forms anorthite type crystalline phase CaAl2Si2O8 at temperature 900°C. A commercial gold electrode paste has also been co-fired with the LTCC, with no delamination, cracks nor camber observed. In-vitro biocompatibility of LTCC has been evaluated using human umbilical vein endothelial cells (HUVEC). The HUVECs attach and spread on the surface of the LTCC substrates, and also in the leachate obtained by soaking LTCC in cell media for seven days. The cell density and percentage of live cells on LTCC surface are comparative with those of control. Results indicate the developed LTCC materials are biocompatible and suitable for biomedical applications.
Reliability of electronics assembled using SAC + Zn solder pastes
Authors: Kotadia H.R. , Panneerselvam A. , Green M.A. , Clode M.P. , Mannan S.H. , Steen H.
Published: October 2015

A method of preparing SAC solder with addition of 1.0-1.5wt.% Zn to Sn-3.8Ag-0.7Cu solder alloy such that a standard solder paste reflow process results in good soldering is described. Solder-substrate couples were aged at 150°C for 1000h, and results on temperature cycling (−20 to 175°C) and shear testing of solder joints is also described. The added Zn segregated to the interfacial IMCs so that Cu6Sn5 became (Cu,Zn)6Sn5 and (Cu,Ni)6Sn5 became (Cu,Ni,Zn)6Sn5. The reliability of assemblies utilizing Electroless Nickel Immersion Gold (ENIG) using the Zn enhanced solder is compared to that of standard SAC solder alloy for potentially reliable operation at temperature up to 185°C.
DM300 - A 300°C Geothermal Directional Module Development
Authors: MacGugan D
Published: October 2015

Enhanced high-temperature geothermal drilling operations require accurate directional drilling measurements to efficiently configure the borehole. A rugged, 300°C capable directional drilling module, Honeywell's DM300, provides the geothermal drilling operator with accurate indications of tool-face angle, inclination, and heading of the down-hole assembly. The DM300 system incorporates two orthogonal arrays of accelerometers and magnetometers with their associated electronic circuitry as well as system level circuitry. The sensors and electronics are packaged in a sealed 1 ¼″ diameter titanium housing. The DM300 high-temperature electronics approach utilizes custom Honeywell developed ASICs that leverage our proven HTSOI4™ silicon-on-insulator technology to successfully operate at 300°C. Vibrating beam MEMS accelerometers provide an inherently digital acceleration signal, through measurement of beam vibration phase using counting methods. Flux-gate magnetometers incorporate a custom voltage-to-frequency converter digitizing ASIC. The magnetometer ASIC integrates several system level functions to reduce chip count in the overall system design. Active cooling is not required for these DM300 features to operate, perform, and survive in a 300°C down-hole environment. This paper presents system concept design and implementation through a two phase development. The current development phase focuses on the development and characterization of the sensors, their associated electronics, and packaging into a 300°C capable housing. A future development phase will incorporate a 300°C capable Gate Array ASIC and EEPROM. The Gate Array functions capture the digital sensor signals and provides SPI bus interface as required for a deployable directional drilling module.
Communications System using a 1K22Monoconductor Cable for Down-hole Measurement Tools
Authors: Mijarez Rito , Pascacio David , Guevara Ricardo , Rodríguez Joaquín , Pacheco Olimpia
Published: October 2015

Progressively deeper and hotter oil wells have driven design modification that enhances the performance in sensors and downhole electronic instruments. Oil reservoirs in Mexico are located at mean depths of 6,000 m; as a consequence, the requirements for measuring thermodynamic and geophysical parameters are challenging. This paper describes a bidirectional communication system that exchanges data from a down-hole high pressure and high temperature (HP/HT) measurement tool to the surface installation. The communication medium is a 7 km mono-conductor 1K22 logging cable used also as a power supply transmission line. The system consists of a proprietary downhole measurement tool, composed of a HT/HP sensor and a high temperature DSP-based electronic device, and a data acquisition equipment located in the surface installation. The system employs a communication algorithm that automatically switches the modulation technique and changes the carrier frequency to avoid issues derived from noise interference, cable attenuation and thermal drift of the front end passive elements. The laboratory tests results provide a firm basis for testing and evaluating the system in the field.
Characterization of the Vectron PX-570 Crystal Oscillator for Use in Harsh Environments
Authors: Li Jacob , Patterson Richard L. , Hammoud Ahmad
Published: October 2015

Computing hardware, data-acquisition systems, communications systems, and many electronic control systems require well-controlled timing signals for proper and accurate operation. These signals are, in most cases, provided by circuits that employ crystal oscillators due to availability, cost, ease of operation, and accuracy. In some cases, the electronic systems are expected to survive and operate under harsh conditions that include exposure to extreme temperatures. These applications exist in terrestrial systems as well as in aerospace products. Well-logging, geothermal systems, and industrial process control are examples of ground-based applications, while distributed jet engine control in aircraft, space-based observatories (such as the James Webb Space Telescope), satellites, and lunar and planetary landers are typical environments where electronics are exposed to harsh operating conditions.

To ensure these devices produce reliable results, the digital heartbeat from the oscillator must deliver a stable signal that is not affected by external temperature or other conditions. One such solution is a recently introduced commercial-off-the-shelf (COTS) oscillator, the PX-570 series from Vectron International. The oscillator was designed for high-temperature applications and as proof, the crystal oscillator was subjected to a wide suite of tests to determine its ruggedness for operation in harsh environments.

The tests performed by Vectron included electrical characterization under wide range of temperature, accelerated life test/aging, shock and vibration, internal moisture analysis, ESD threshold, and latch-up testing. The parametric evaluation was performed on the oscillator's frequency, output signal rise and fall times, duty cycle, and supply current over the temperature range of −125 °C to +230 °C. The evaluations also determined the effects of thermal cycling and the oscillator's re-start capability at extreme hot and cold temperatures. These thermal cycling and restart tests were performed at the NASA Glenn Research Center. Overall, the crystal oscillator performed well and demonstrated very good frequency stability. This paper will discuss the test procedures and present details of the performance results.
SILICON CARBIDE “SUPER” JUNCTION TRANSISTORS OPERATING AT 500 °C
Authors: Sundaresan Siddarth , Singh Ranbir , Johnson R. Wayne
Published: October 2015

1200 V/ 3 mm2 active-area SiC “Super” Junction Transistors (SJTs) display current gains as high as 88 and majority carrier operation up to 250 °C. The SJT operation shifts from purely unipolar to bipolar-mode at temperatures ≥ 300 °C. The leakage currents at a blocking voltage of 1200 V remain below 100 μA, even at 325 °C. Temperature-independent turn-on and turn-off times < 15 ns are measured up to 250 °C. A short-circuit withstand time of 22 μs at VDS=800 V, and a single-pulse avalanche energy of 20.4 mJ are measured. No degradation of the blocking I-V characteristics was observed after a 934 hour repetitive avalanche stress test.
High-Temperature Reliability of Direct-Bond-Copper Substrates with Sealed Edges
Authors: Yao Yiying , Chen Zheng , Boroyevich Dushan , Ngo Khai D. T.
Published: October 2015

Recent reports have shown the reliability of direct-bond-copper (DBC) substrates was significantly improved by sealing their edges with polymeric materials. In this work, DBC substrates with and without sealed edges had been prepared. Parylene HT and Nusil R-2188 had been chosen as sealing materials. Parylene HT was applied to the edges of the DBC by chemical vapor deposition (CVD), and Nusil R-2188 by programmable fluid dispensing. The DBC substrates with and without sealed edges were cycled between −55°C to 200°C. The cycled substrates were monitored by optical microscope and scanning electron. DBC substrates whose edges were not sealed were found to fail in approximately 100 cycles. No failure was observed in DBC substrates coated with parylene HT before 300 cycles. Samples whose edges were sealed with Nusil R-2188 exhibited the highest lifetime under the thermal cycling condition of −55°C – 200°C. After 300 cycles, neither detachment of Nusil from DBC surfaces nor failure at Cu/Al2O3 interface was detected. After 900 cycles, 30 μm – 60 μm cracks appeared at the edges of Cu/Al2O3 interface, which are signaling the early stage of substrate failure. Additionally, Nusil was found to be partially detached from DBC surfaces. The improvement in reliability is attributed to the release of thermo-mechanical stress concentrated at the edges of the Cu/Al2O3 interface.
Investigation of Thick Film Technology for High Temperature Applications
Authors: Zhou Zhangming , Cui Jinzi , Yu Fang , Fang Kun , Shen Zhenzhen , Johnson R. Wayne , Vert Alexey , Zhang Tan , Shaddock David
Published: October 2015

For electronics operating at 300°C, thick film technology has been proposed as a suitable interconnection technology to create modules. This work examines the leakage current with constant bias (100V) at 300°C. The leakage current increased significantly within the first few hours of aging. The effect of 300°C aging with dc bias on the adhesion of multilayer thick film test structures was also studied. The aged adhesion was a function of bias polarity. Fracture surface analysis results are presented. Bi in the PtPdAu conductor appears to play a role in both the leakage current and adhesion phenomena observed.
SOI Based Voltage Regulator for High-Temperature Applications
Authors: McCue B. M. , Greenwell R. L. , Laurence M. I. , Blalock B. J. , Islam S. K. , Tolbert L. M.
Published: October 2015

Developments in automotive (particularly hybrid-electric vehicles), aerospace, and energy production industries have led to expanding research interest in integrated circuit (IC) design toward high-temperature applications. A high-voltage, high-temperature silicon-on-insulator (SOI) process allows for circuit design to expand into these extreme environment applications. Nearly all electronic devices require a reliable supply voltage capable of operating under various supply voltages and load currents. These supply voltages and load currents can be either DC or time-varying signals.

In this work, a stable supply voltage for embedded circuits is generated on chip via a voltage regulator producing a stable 5-V output voltage. Although applications of this voltage regulator are not limited to gate driver circuits, this regulator has been developed to meet the demands of a gate driver IC. The voltage regulator must be able to provide reliable output voltage over an input range from 10 V to 30 V, a temperature range of −25°C to 200°C, and output loads from 0 mA to 200 mA. Additionally, low power stand-by operation is provided to help reduce heat generation resulting in lower operating junction temperature. The designed voltage regulator has been successfully tested from −50°C to 200°C while demonstrating an output voltage variation of less than 10 mV under the full range of input voltage. Additionally, line regulation tests from 10 V to 30 V show a 12-ppm/V supply sensitivity. Full temperature and input voltage range tests reveal that the no-load supply current draw is within 17 mA while still providing in excess of 200-mA load current upon demand. Modifications to the existing design or off-chip biasing can widen the range of attainable output voltages and drive capabilities.
SOI-Based Integrated Gate Driver Circuit for High-Temperature Applications
Authors: Greenwell R. L. , McCue B.M. , Laurence M.I. , Fandrich C.L. , Blalock B.J. , Tolbert L.M. , Islam S.K.
Published: October 2015

The growing demand for hybrid electric vehicles (HEVs) has increased the need for high-temperature electronics that can operate at the temperatures that exist under the hood of these vehicles. In many cases this requires the use of thermal management systems to allow for the use of components not designed to operate at the ambient temperatures found in the engine compartment of an HEV. These systems add weight and complexity, which can increase the overall cost and reduce the efficiency of the vehicle. The alternative is to develop circuits and systems capable of operating with reduced or no thermal management. To this end, the latest version of our high-temperature gate driver integrated circuit (IC) has been developed. Designed and implemented on a 0.8-micron bipolar-CMOS-DMOS (BCD) on silicon-on-insulator (SOI) process, this gate driver chip is intended to drive silicon carbide (SiC) and other wide-bandgap (WBG) power field-effect transistors (FETs) for DC-DC converters and traction drives in HEVs. To enable this, the gate driver IC, which includes on-chip voltage regulators and protection circuitry, has been designed to operate at and successfully tested up to 200°C ambient temperature. Successful operation of the circuit at this temperature with minimal or no heat sink, and without liquid cooling, will help to achieve higher power-to-volume as well as power-to-weight ratios for the power electronics modules in HEVs.
High temperature solders containing Aluminum and Zinc
Authors: Kotadia H.R. , Mokhtari O. , Bottrill M. , Clode M. P. , Green M. A. , Mannan S. H.
Published: October 2015

In this study, we will consider the effect of adding 1–1.5wt.% of Al and Zn to SAC alloy solders in order to limit IMC growth between the solder and the contact metallization. The Al and Zn react strongly with the surfaces on the electronic component and the substrate metallizations that are to be joined. At the solder joint interface, the IMC layer continues to grow at high temperatures and, being brittle, becomes the weakest link in the solder joint. In present work, the interfacial reaction studies were carried out on Cu and Ni(P) substrates. The resultant solder joint microstructure after reflow and isothermal aging at 150 °C up to 500h were investigated under scanning electron microscopy (SEM) with energy-dispersive x-ray analysis (EDX) for phase identification and optical microscopy (OM) for qualitative and quantitative analysis. Our experimental results have confirmed that addition of Al and Zn alloys forms Al-Cu and Cu-Zn on Cu substrate and Al-Ni on Ni(P) substrate respectively. In addition, results have confirmed that addition of Zn alloys plays a crucial role in the composition of IMCs. Addition of Zn (>1wt.%) into basic SAC solder alloy, leads to massive spalling on Cu substrate during reaction. It has been found that additions of Zn into SAC solder alloy can significantly suppress the IMC growth during the aging treatment.
New Rechargeable Battery for Application in a Wide Temperature Range
Authors: Caja Josip , Dunstan T. Don , Caja Mario
Published: October 2015

At this time there is no rechargeable battery available which can deliver required currents in a wide operating temperature range, such as from ambient or low temperature to higher temperatures (e.g. 150°C). In this paper a CC size rechargeable Li-ion molten salt battery which can operate in the temperature range from room temperature to 130°C is presented. The cell has open circuit voltage of 2.3V for fully charged cell. It exhibits high coulombic efficiency. The cell can operate at low currents as well as at high currents; however, at very high currents coulombic efficiency decreases. It can operate at temperatures greater than 130°C but its cycle life is shorter. The battery demonstrates very good safety features. Short-circuiting, overcharge, deep discharge, or reverse charge does not result in violent reaction. These properties make this cell a very good candidate for application in drilling and logging industry. In addition, these cells could help in extending the drilling capabilities of tools.
Nanocomposite Film Dielectrics for High Temperature Power Conditioning Capacitors
Authors: Slenes Kirk , Bragg Lew
Published: October 2015

Emerging power electronics in a broad range of military, aerospace, hybrid vehicle, renewable energy and down-hole drilling applications rely on advances in dielectric materials for capacitors. Compact capacitors possessing low dielectric loss and high operating temperature capability are needed for power conditioning in advanced converter and inverter designs for these applications. Wound film capacitors represent the preferred capacitor technology but are limited by low operating temperature capabilities, < 150°C, and low volumetric efficiency, capacitance per unit volume less than 1.0 μF/cc.

TPL is developing processes and manufacturing techniques for fabrication of advanced capacitor films comprised of high temperature polymers modified with ceramic nanoparticles. The selected polymers enable high temperature operation and the ceramic nanoparticles enhance volumetric efficiency by increasing the dielectric constant. The fabricated films are directly adaptable to conventional wound film capacitor construction methodologies.

This paper provides an overview of TPL's experience to-date with a film dielectric material system comprised of fluorenone polyester polymer and titanate nanoparticle filler. The fluorenone polyester polymer was selected to provide a stable operating temperature of at least 300°C, while the addition of the titanate powder increases the dielectric constant and, in turn, the volumetric efficiency of wound film capacitors constructed with this film system. The targeted device for the film is a 500 to 800 V filter capacitor for high temperature power conditioning applications.
Design of High Temperature EMI Input Filter for a 2 kW HVDC-fed Inverter
Authors: Robutel Remi , Martin Christian , Morel Herve , Buttay Cyril , Bergogne Dominique , Gazel Nicolas
Published: October 2015

In this paper, a high temperature EMI input filter for a SiC JFET inverter is designed and tested in operating conditions at 200°C. Inverter EMI issues, design procedure and characterizations of selected components are presented in details. The feasability based on industrially available materials and components is demonstrated with a low temperature dependence of EMI Spectrum.
Modeling and Design of High Temperature Silicon Carbide DMOSFET Based Medium Power DC-DC Converter
Authors: Potbhare Siddharth , Akturk Akin , Goldsman Neil , McGarrity James M. , Agarwal Anant
Published: October 2015

Silicon Carbide (SiC) is a promising new material for high power high temperature electronics applications. SiC Schottky diodes are already finding wide acceptance in designing high efficiency power electronic systems. We present TCAD and Verilog-A based modeling of SiC DMOSFET, and the design and analysis of a medium power DC-DC converter designed using SiC power DMOSFETs and SiC Schottky diodes. The system is designed as a 300W boost converter with a 12V input and 24V/36V outputs. The SiC power converter is compared to another designed with commercially available Silicon power devices to evaluate power dissipation in the DMOSFETs, transient response of the system and its conversion efficiency. SiC DMOSFETs are characterized at high temperature by developing temperature dependent TCAD and Verilog-A models for the device. Detailed TCAD modeling allows probing inside the device for understanding the physical processes of transport, whereas Verilog-A modeling allows us to define the complex relationship of interface traps and surface physics that is typical to SiC DMOSFETs in a compact analytical format that is suitable for inclusion in commercially available circuit simulators.
High Temperature CMOS Reliability and Drift
Authors: Rose Shane
Published: October 2015

Quartzdyne precision pressure transducers are required to continuously operate at 200°C for more than 5 years (>1 year at 225°C). Future electronics are targeted for 250°C operation. The current transducer electronics are based on 3 custom ASICs; an Oscillator, Voltage Regulator and a Frequency counter. Understanding custom integrated circuit component drift and interconnect life at temperature is crucial for the next generation of sensor applications.

In this study, basic components are aged under bias at 225°C, 250°C and 275°C. Components include P-FET transistors, polysilicon resistors, and a diode connected PNP transistor. Measured parameter drift versus temperature and electrical stress is used to estimate device drift over time. Measured voltage regulator drift is compared with estimated drift based on resistor and diode measurements.

Standard aluminum circuit interconnect life is measured at 3 current densities and temperatures. A modified current density guide is derived from Black's equation. Measured circuit interconnect life is shown to increase when diffusion barriers are present. Powered Quartzdyne hybrid circuit life results at 225°C are compared to expected lifetimes.
Characterization and Reliability of custom digital ASIC designs using a 0.8μm bulk CMOS process for high temperature applications
Authors: Watts Mark , Rose Shane
Published: October 2015

With today's quickly changing technology, part obsolescence often forces unanticipated and costly design changes outside the normal product life cycle. Custom ASICs can be used to fill this gap and gain other advantages such as reduced parts count, higher performance, and higher reliability. Two digital 0.8μm bulk CMOS ASICs have been successfully implemented, providing higher reliability and performance than their replacement parts at 225°C. In this paper we examine some of the design issues encountered during their implementation, including process selection, library characterization at 225°C and above, performance, testing and qualification. External analog circuitry was integrated to further reduce parts count and increase reliability. In conclusion, we have found bulk CMOS to be an acceptable process for custom ASICs in high temperature environments.
New Generations of Highly Integrated High Temperature DC-DC Converters
Authors: Delatte Pierre , François Thomas , Baldwin David , Beranek Jan , Gradincic Zlatan , Vanzieleghem Etienne
Published: October 2015

This paper presents YELLOWSTONE, a single chip, low-voltage, synchronous Buck DC-DC converter implementing a current mode PWM controller with built-in N & P-channel power MOSFETs. It aims to be used as a Point-of-Load (PoL) switched mode power supply with a maximum output current of 500mA. It generates from a typical +3.3V or +5V voltage input a lower voltage output between +0.9V and +3.3V configurable by an external resistor network. It has been specified and designed for operation at temperatures from −55°C to +225°C. Synchronous rectification increases efficiency and reduces external components count. The circuit achieves power efficiencies in excess of 90%. The chip implements a current mode PWM control which enables a fast response to line and load transient variations. A high switching frequency (1.5MHz typical with internal clock and up to 2MHz with external clock) has been selected enabling a dramatic reduction of the number and size of passive external components. The current mode control made possible to use a simple compensation loop and to integrate it. High integration level, tiny IC package (5mm*5.5mm) and small external passive components, lead to a very small footprint for the complete PoL function, i.e. as small as 0.25inch2 (10mm*15mm).
A System On Chip (SOC) ASIC chipset for Aerospace and Energy Exploration Applications
Authors: Tulpule Bhal , Ohme Bruce , Larson Mark , Behbahani Al , Gerety John , Steines Al
Published: October 2015

This paper describes the design, key features and applications of a System On Chip (SOC) ASIC (Application Specific Integrated Circuit) chipset which was developed by Embedded Systems LLC as a part of the Smart Node based distributed control system architecture under an Air Force SBIR (Small Business Innovative Research) program {4}. The analog part of the SOC chipset has been implemented by Honeywell International under a subcontract using their high temperature SOI (Silicon On Insulator) Process. The complete chipset is expected to be available in early 2015.

The key feature of the SOC chipset is that it is a reconfigurable and scalable building block that can be used to interface with most typical aerospace control system sensors and actuators. The SOC chipset captures all of the necessary functions required to power and interface with sensors such as RTD (Resistance Temperature Detectors), Strain Gauges (SG), Thermo Couples (TC) and transducers for measuring mass flow, speed, position or angle. The SOC chipset also contains all of the pre- and post-processing functions to convert electrical signals into digital words and send them on a data bus under the control of a host microprocessor. Finally, the SOC chipset contains PWM (Pulse Width Modulation) circuitry required to interface with external drives for actuators, motors, shutoff Valves etc. The SOC chipset can be powered from a Mil-Std-704F compliant power source or a conditioned DC power source. The chipset can be combined with other devices, such as memory, processor and A to D Converter to implement a high temperature capable Smart Node for localized management of sensors and actuators as a part of a distributed architecture or used as a scalable building block in a more complex function such as a FADEC (Full Authority Digital Engine Control). It is believed that the versatility of the SOC chipset makes it a well suited, affordable, scalable building block for not only aerospace controls but also for diverse applications such as down-hole drilling, energy exploration, wind farms etc. where high temperature electronics and /or high level of miniaturization is required.
“Has Microelectronic MCM Technology Matured and is it Capable of Servicing the Widespread Needs of Down Well 225°C Operating Applications in the Oil and Gas Industry?”
Authors: Hunt Bob , Tooke Andy
Published: October 2015

This paper reviews development and qualification work performed on 225°C operating temperature modules based on ceramic thick film multi-layer substrates supporting embedded thick film resistors, assembled passive and active components with ‘chip and wire’ connections and sealing in hermetic metal and ceramic cavity packages. It considers aspects of development and importantly investigates product qualification which includes shock and vibration at elevated temperatures as well as thermal shock and temperature cycling. In conclusion there is an attempt to answer the question “Has microelectronic MCM technology matured and is it capable of servicing the widespread needs of down well 225 °C operating applications in the Oil and Gas industry?”
Characterization of a Large Area Silicon Carbide PiN Diode at Temperatures up to 900°C
Authors: Richmond Jim , Cheng Lin , Agarwal Anant , Palmour John
Published: October 2015

For the first time, a large area Silicon Carbide (SiC) PiN diode was measured to determine the forward and reverse characteristics at temperatures up to 900°C. The diode characterized had a chip area of 64 mm2 and used a conventional SiC PiN structure with a 75 um N type blocking layer thickness. A normal rating for this device at room temperature would be 50 amps at 100 A/cm2 and 6 kV. Since a package capable of operating at 900°C was not available, methods were developed to heat and verify the temperature of the diode die, provide electrical connections to the die and provide adequate insulation to minimize temperature gradients across the die. Even at this extreme temperature the diode maintained typical diode characteristics and maintained surprisingly good performance.
An Airborne High Temperature SiC Power Converter for Medium Power Smart Electro Mechanical Actuators
Authors: Bergogne Dominique , Dubois Fabien , Martin Christian , Falahi Khalil El , Phung Luong Viet , Buttay Cyril , Dhokkar Sonia , Allard Bruno , Meuret Régis , Morel Hervé
Published: October 2015

Normally-On Silicon Carbide (SiC) JFETs are good candidates for power switches in high temperature applications, in Three-Phase Voltage-Fed Inverters used to drive Electro-Mechanical Actuators (EMA) for the more electrical aircraft where the ambient varies from −55 °C to 200 °C. The power of the EMA is in the 1 to 5 kW range, the DC bus voltage is 540 V. It is also necessary to implement passive subsystems such as Electro-Magnetic-Interference (EMI) filters, power inductors, transformers, packaging and interconnection solution that withstand the wide temperature range. The gate driver for normally-On devices must include a safe solution against short-circuit in the event of a power supply failure. The experimental converter is built using engineering samples such as SiC JFETs, SOI drivers and laboratory made components such as inductive wire wound, nano-crystalline core components, SOI integrated driver, assembled with a high temperature package and technology. Finally, the Smart EMA test bench is presented.
Stress Intensity of Delamination in a Sintered-Silver Interconnection
Authors: DeVoto D. J. , Paret P. P. , Wereszczak A. A.
Published: October 2015

In automotive power electronics packages, conventional thermal interface materials such as greases, gels, and phase-change materials pose bottlenecks to heat removal and are also associated with reliability concerns. The industry trend is toward high thermal performance bonded interfaces for large-area attachments. However, because of coefficient of thermal expansion mismatches between materials/layers and resultant thermomechanical stresses, adhesive and cohesive fractures could occur, posing a reliability problem. These defects manifest themselves in increased thermal resistance. This research aims to investigate and improve the thermal performance and reliability of sintered-silver for power electronics packaging applications. This has been experimentally accomplished by the synthesis of large-area bonded interfaces between metalized substrates and copper base plates that have subsequently been subjected to thermal cycles. A finite element model of crack initiation and propagation in these bonded interfaces will allow for the interpretation of degradation rates by a crack-velocity (V)-stress intensity factor (K) analysis. A description of the experiment and the modeling approach are discussed.
Modeling of Thermomechanical Behaviour of Wire Bonded Electronic Devices under Combined Thermal and Vibration Loads
Authors: Man R. , Liu C. , Mirgkizoudi M. , Riches S.
Published: October 2015

This paper has extended the investigation of the combined effects of thermal and vibration loadings by numerical and finite element analysis (FEA) of the stresses and strains in Au ball-wedge wire bonded devices. A comparison with Cu and Al wires was also performed. The finite element model was established in order to predict the stresses and strains induced in the bond wires by analysing the thermal coefficient of expansion which is affected by temperature, excitation frequency of the bond wires during vibration and the subsequent changes from different wire bonding profiles. The effect of combined loading was found to increase the stresses by decreasing the resonant frequency that the wire experiences. The material seems to have a more significant effect in increasing the stresses than the loop height of wire bonds. The work has demonstrated the usefulness of numerical methods to permit the reasonable predictions of the complex mechanical behaviour of wire bond under the combined high temperature and vibration testing regimes.
SMD and Leaded Ceramic Capacitors for High Temperature Applications
Authors: Gurav Abhijit , Xu Xilin , Magee Jim , Bultitude John , Ashburn Travis
Published: October 2015

For high temperature applications at 150°C or above, such as in electronics for down-hole drilling, geothermal energy generation, power electronics and automotive under the hood electronics, a robust dielectric material is necessary for capacitors. Common X7R and X8R type ceramic capacitors are designed for applications up to 125°C and 150°C, respectively. At temperatures above 150°C, these types of capacitors typically suffer from degradation of reliability performance and severe reduction in capacitance, especially under DC bias conditions. 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. Multi-layer ceramic capacitors (MLCCs) made from this material can be qualified as X9G. 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 along with a discussion of possible mechanisms behind the robust reliability of this high temperature dielectric.
Reliability of Au-Ti for High Temperature Termination on Ferrite LTCC Inductors
Authors: Galipeau James , Gerlach Matt
Published: October 2015

While ferrite Low Temperature Co-fired Ceramic (LTCC) inductor and transformer developments have undergone thermal shock and high temperature aging that focused on the stability of their electrical characteristics (resistance, inductance), little attention has been paid to their termination reliability at high temperatures. Testing has been done on AgPt and AgPd terminations with Ag5Cd95 and Pb88Sn10Ag2 solders for 2000 and 25 hrs, respectively. However, Ag5Cd95 is unusable in commercial applications due to ROHS restrictions while Pb88Sn10Ag2 is undesirable because of the high lead content. Sn96 solder and wire bonding are common attachment methods that have not been vetted. Initial investigations show that high Sn solders may interfere with bonding between the AgPt and AgPd termination materials and the ferrite bulk of the part. An alternative terminal structure for using Sn96 solder is created by electroplating Au and Ni; however, electroplating to ferrite is challenging due to the masking involved. Also, the preferred materials for wire bonding are thick film, thin film or electroplated Au. To this end an alternative termination structure using Au sputter deposited onto sputter deposited Ti is being investigated. This structure was chosen for its potential to be a lower cost alternative to thick film Au and for its potential for simpler manufacturing than electroplating. Tests involved measuring bond strength and resistance after thermal ageing and thermal shock. Baseline solder joint pull tests show strength comparable to other termination methods. Some issues with solder wetting of the terminals have been noted.
POL and LDO for Harsh Environment Applications
Authors: Khanna Ramesh , Venkataraman Srinivasan
Published: October 2015

Harsh Environment approved components/ designs require high reliability as well as availability of power to meet their system needs. The paper will explore the various design constrains imposed on the high temperature designs. Down hole oil and gas industry requires high reliability components that can withstand high temperature.

Discrete component selection, packaging and constrains imposed by various specification requirements to meet harsh environment approval are critical aspect of high-temp designs. High temperature PCB material, PCB layout techniques, trace characteristics are an important aspect of high-temperature PCB design and will be explored in the article. Buck Converters are the basic building blocks, but in order to meet system requirements to power FPGA's where low output voltage and high currents are required. Converter must be able to provide wider step down ratios with high transient response so buck converters are used. The paper with explore the various features of a buck-based POL converter design. Low noise forces the need for Low-dropout (LDO) Regulators that can operate at high Temperatures up to 210°C. This paper will address the power requirements to meet system needs.
Characterization of LTCC-Thick Film Technology for 300°C Packaging
Authors: Zhang Tan , Shaddock David , Vert Alexey , Zhang Rui , Johnson R. Wayne
Published: October 2015

Economic geothermal well construction and reservoir characterization requires high temperature logging tools and sensors with the long-term operation capability of 300°C. Low temperature co-fired ceramic (LTCC) and thick film technology make them a potential candidate for building interconnects to SiC device and functional analog or digital circuits to operate at that temperature. In this work, single conductor layer LTCC substrates have been fabricated to characterize the thick film Au adhesion under 300°C aging. Via reliability has been evaluated on the multi-layer LTCC substrates under temperature cycling of 35–325°C. In addition, die attach, wire bonding and stud bumping assembly techniques has been investigated.
Implementation of Silicon-on-Insulator (SOI) Control Electronics to Accelerometers for High Temperature Applications
Authors: Riches S T , White I , Rickard G , Chadwick G
Published: October 2015

The requirement to install control systems integrated with sensors in high temperature environments has posed a challenge to the traditional limit of 125°C for conventional electronics. There is a need to operate at temperatures of 200°C and above in restricted space for example in down-well, aero-engine or geothermal applications in combination with high pressures, vibrations and potentially corrosive environments.

Piezo-electric accelerometers based on ferro-electric ceramics have been used in a wide range of applications for measuring vibrations, fluid flow and turbulence and are capable of operating as a transducer alone at temperatures up to 250°C, which has made them attractive in sensing applications for down-well drilling and aero-engine health and usage monitoring. However, the electronics traditionally used to carry out the signal conditioning and processing (e.g. charge to voltage conversion, filtering) has been limited to a qualification limit of 125°C, which results in a reduced sensitivity of the transducer output as the signal conditioning and processing cannot be performed close to the sensor.

With the development of Silicon-On-Insulator (SOI) semiconductor technology, which can operate at temperatures of up to 250°C, many of the signal conditioning and processing operations can be carried out in-situ with the accelerometers to create a new generation of high temperature products. In addition, the integration of many of the functions that used to require discrete components into one SOI based device has led to further miniaturisation opportunities and a protection against obsolescence of specialist analogue devices.

This paper will describe the migration of the traditional low temperature electronics to a high temperature SOI based ASIC device and the implementation of high temperature electronics packaging technology to instrumentation for piezo-electric accelerometers, leading to products that are suitable for high temperature monitoring in restricted spaces in down-well drilling and aero-engine applications.