The demand for high-temperature electronics in aerospace, power systems, and geothermal drilling necessitates materials that withstand 300 degrees C+ and thermal fluctuations from -40 degrees C to 300 degrees C. Aluminum nitride (AlN) is promising due to its high thermal conductivity and low CTE, but surface oxidation remains a challenge, particularly when high-temperature inks require sintering at 850 degrees C. This study explores additive processes for Aerosol Jet printed (AJP) conductors and dielectrics on Digital Light Processing (DLP)-printed and commercial AlN substrates to develop reliable packaging for high-temperature applications. Four candidate conductors were evaluated for fine-line printability (<100 mu m), conductivity, and adhesion on different surface oxidation conditions (no oxide/partial oxidation/ full oxidation). A similar adhesion evaluation was conducted on two dielectric materials. X-ray photoelectron spectroscopy (XPS) analysis revealed that three firing cycles at 850 degrees C induce full surface oxidation, and oxidation thickness reached about 670 nm after five cycles. Only one conductor showed good adhesion to the three surface oxidation conditions. This conductor, a thick film gold, was successfully diluted for AJP, achieving a line width of 100 mu m. Additionally, one dielectric exhibited high adhesion (>40 MPa) to the three surface oxidation conditions, while the other dielectric exhibited poor adhesion on no oxide surfaces, but adhesion improved with more oxidation. Ultimately, the down-selected conductor and dielectric achieved stable adhesion after aging at 300 degrees C for 100 hours. Developing processes and materials for high-temperature AlN ceramics can add a valuable new tool to the toolbox of high-temperature research.

Silicon Carbide (SiC) enhancement mode MOS electronics offer several benefits for realizing analog, digital and mixed signal electronics, but limitations on gate dielectric reliability has limited the adoption of MOS in high temperature application. In this work, we report GE’s lateral SiC MOSFETs exceeding previously reported temperature capabilities for SiC MOSFETs with experimental results that have shown that >500°C operation of SiC MOSFETS is possible with >400 hours demonstrated at 620°C, and short-term functionality demonstrated to 800°C. The result shows that MOS-based SiC electronics can continue to be a viable choice for circuit implementations at extreme temperatures >600°C.

Throughout the last few years, there has been a significant increase in demand for high temperature capacitors due to the rising need for electronics in harsh environments, including aerospace, automotive, and oil and gas industries. With the continued growth of electronics in these environments, there is a need for the development of new materials and manufacturing techniques to drive advances in high temperature capacitor technology. Additive manufacturing is one promising approach for producing electronics that can withstand high temperatures, leading to improved performance and reliability in a wide range of applications. The present work describes the fabrication and testing of MIM (metal-insulator-metal) capacitors at high temperatures using gold as the conductor material. The substrates used in this work is 3D printed Lithoz 350D 99.8% alumina. The work details the fabrication process and evaluates the relative permittivity of high-temperature dielectric material. The adhesion strength at the interfaces is examined before and after aging for up to 250hours at temperatures as high as 750°C. The leakage current is measured for 100hours at varying temperatures and the insulation resistance is calculated. Furthermore, the capacitance is monitored during aging at temperatures up to 700°C and frequencies as high as 1MHz. Finally, the capacitance is measured at room temperature before and after subjecting the capacitors to 100 cycles of thermal cycling at three different temperature ranges. The adhesion between all interfaces of the MIM capacitors is found to remain high even after aging at 700°C, leakage currents are minimal and stable, and the capacitance remained very stable during and after aging and after thermal cycling.

In the relentless pursuit of expanding the boundaries of what is achievable under extreme temperature conditions, the precise measurement of RF signals becomes crucial. The ability to capture and analyze RF data in environments with high temperatures not only improves operational efficiency and reliability but also opens up new avenues for scientific investigation. This research introduces a innovative advancement in the field of high-temperature electronics: high-temperature SiO 2 cables equipped with edge launch connectors. These connectors represent a significant advancement in high-temperature electronics, as they are specifically engineered to withstand elevated temperatures, boasting an impressive resilience of up to 600°C. This exceptional temperature tolerance makes them invaluable assets in industries where electronic components are exposed to extreme heat conditions. To verify their performance, the RF characteristics of Coplanar Waveguide (CPW) lines and Metal-Insulator-Metal (MIM) capacitors were evaluated using the innovative SiO 2 cables and edge launch connectors. Remarkably, these connectors demonstrated outstanding performance, maintaining both their structural integrity and RF functionality even after being subjected to temperatures of up to 600°C for three complete cycles, with no signs of degradation observed. This outcome underscores the durability and reliability of these state-of-the-art connectors, positioning them as indispensable instruments for high-temperature RF measurements.

High-temperature electronic circuits are becoming increasingly important in a variety of commercial applications, particularly in extreme high-temperature environments. These circuits are instrumental in applications including on-engine sensors, which must withstand elevated temperatures, such as 150°C for general applications and up to more than 500°C for aircraft engines. Many of these high-temperature electronic circuits and sensors rely on inductors, which are fundamental components for creating filters, oscillators, transformers, and bias chokes. Additive manufacturing or direct write, a cost-effective and efficient production method, has been used to create 2D inductors with intricate designs and integrated components. These 2D printed inductors closely resemble their traditionally manufactured counterparts but offer cost and time advantages. However, 2D inductors face limitations when it comes to increasing their inductance values especially with direct write materials and fabrication methods. To achieve higher inductance, they require more space, often in the form of increased turns within the flat plane. The integration of a core material inside these turns in a 2D inductor is not feasible, and this area has remained unexplored in the literature. This paper introduces a new solution by presenting a conical 3D version of an additively designed high-temperature inductor up to 750°C. This approach incorporates a 3D printed ceramic substrate and aerosol jet printed high-resolution gold inductor conductor. Our approach encompasses parametric design and simulation study addressing the effect of the number of conductors turns, spacing, and core materials type and volume. Results highlight that the integration of ferromagnetic materials, resulted in a remarkable enhancement in the inductance and Q-value of the inductor. Compared to its 2D counterpart, this 3D design achieves a twofold improvement in performance while reducing the footprint by more than half.

Silicon Carbide (SiC) CMOS electronics is a promising approach for realizing high level of integration, especially for implementing digital functions, while significantly reducing the power dissipation on chip compared to NMOS-only, or JFET approaches. Gate oxide in MOSFET-based electronics pose a potential reliability challenge for operating at extreme temperatures. GE has previously developed gate oxide reliability models that predicted reliable operation at 500°C, but experimental validation had not been conducted previously. Recent testing results of testing of 500°C operation of SiC CMOS based integrated circuit over 60 days of continuous operation are presented. The results show the gate oxide surviving extended operating time of both NMOS and PMOS devices at 500°C. and thereby enabling a roadmap towards realizing more complex digital function at extreme temperature >=500°C.

Conventional oil and gas drilling measurement while drilling (MWD) systems are typically designed to operate at temperatures <200°C. To increase the efficiency of drilling unconventional geothermal wells, downhole MWD tools are needed that can operate in the unique thermal challenges encountered in enhanced geothermal systems (EGS). GE demonstrated a 300°C downhole navigation system. The system utilizes GE’s internally developed state-of-the-art MEMS multiple ring Gyroscope (MRG), and a high temperature gyroscope control and readout application specific integrated circuit (ASIC). The MRG, ASIC and associated high temperature, high reliability packaging were integrated to demonstrate the performance and functionality of the gyroscope across the temperature range from room temperature to 300°C. Specialized long-term capable high temperature test platforms were developed to enable the characterization and testing of the gyroscope system and utilized to validate application-relevant lifetime capability.

There is growing interest in extreme temperature electronics to support instrumentation for sensors at temperatures beyond the normal range of electronics. Reliable packaging in the temperature range of more than 300°C has been demonstrated using ceramic multi-chip modules using conventional hybrid circuit technology. This approach typically requires high NRE costs and lead time. Additive manufacturing processes of metals, ceramics, conductors, and dielectrics provides a digital transformation of hybrid circuit manufacturing technology that reduces time and cost for packaging with the added benefits of novel 3D structures and embedded features. Silicon carbide devices have been demonstrated to operate above 300C which requires capable interconnects. This report presents the results of testing to characterize important electrical and mechanical properties of additively manufactured packaging materials (substrates, conductor, dielectrics) and die interconnect methods capable for operation above 300 °C. Characterization of thick film materials were tested for resistance, SIR, and adhesion stability on 96% alumina, 98.4% additively printed alumina, and Corning alumina ribbon ceramic at 300, 500, and 750°C. Methods for direct write interconnects were developed and tested at 300 and 500C for resistance stability and thermal shock. The methods are direct write surface interconnects, embedded interconnects using additive alumina substrates, and flip chip. Reliability testing results, a test method for insitu measurement, and demonstrations using the materials are presented.

There is a growing interest in the development of microelectronics that can perform reliably and robustly at temperatures above 300 °C. Such devices require stable thermal properties, low thermal drift, and thermal cycling resistance. Conventional hybrid circuit technology demonstrates high‐temperature packages, but the high costs and lead time are significant drawbacks. In contrast, additive manufacturing processes, including aerosol jet printing (AJP), offer cost and time benefits, as well as 3D structures and embedded features. However, the properties and reliability of additive packaging materials at extreme temperatures are not well known. Herein, the reliability at temperatures up to 750 °C in terms of electrical performance and mechanical strength of aerosol jet printed gold thick films onto ceramic substrates are assessed. Thermal coefficient of resistance of printed gold films is measured. The electrical resistance stability and leakage current of printed gold structures are also characterized during over 100 h of aging at temperatures up to 750 °C. Finally, the mechanical adhesion strength of the printed gold films is evaluated after aging for 100 h at temperatures up to 750 °C. The adhesion of the printed gold to the ceramic substrates remains high after aging, very stable resistances and minimal leakage currents have been observed.

There is a rapidly growing interest in the development of electronic microsystems that can maintain functionality in high temperature environments, particularly in power generation and aircraft engines where the operating temperatures can exceed 500 degrees C. The current work presents a major advancement toward development of additively printed electronics made for high temperature applications. Here, the electronic system is represented by gold-based electrical structures that have been printed on 3D printed ceramic substrates. The substrate is alumina-based with a purity level of 99.8% and was fabricated through photopolymerization digital light processing (DLP). An aerosol jet printing technique that can deposit an ink stream down to 10 mu m was utilized to fabricate gold-based electronic structures. The gold ink printability and its adhesion to the ceramic substrate were assessed. Furthermore, the microwave dielectric constant and loss tangent of the alumina substrate were extracted through measurements of the scattering parameters of transmission lines up to 750 degrees C. A 3D printed conformal broadband antenna was successfully fabricated and tested at temperatures up to 850 degrees C. The printed gold structures showed excellent stability and adhesion after aging at temperatures up to 750 degrees C. The substrate dielectric constant slightly increased for temperatures up to 450 degrees C and significantly increased for temperatures between 450 degrees C and 750 degrees C. It was found that the dielectric loss increased as the temperature increased. This work presents an entirely additive manufacturing-based approach to fabricate electronic components including substrates, interconnects, and RF elements for high temperature applications.

High temperature electronics face obvious challenges in terms of high temperature endurance, a wide range of thermal cycling, and fabrication processes. A recent paper demonstrated the stability of 3D printed ceramic substrates with printed gold up to 850°C. The present work addresses approaches to the interconnection of silicon die to such substrates. After screening the materials used to metallize the substrates based on adhesion and the capability of handling high temperatures, three methods of die interconnection were successfully developed: surface mounting, embedding, and flip-chip attach. The resistance of each structure was monitored under high temperature aging up to 500 °C and in thermal cycling between -40 °C and 300 °C, and between room temperature and 500 °C. The flip-chip design was shown to operate successfully in the high temperature aging environment and the embedded design was able to handle the harsh thermal cycling tests.

The 300°C Microelectromechanical system (MEMS) gyroscope project aims to contribute to DOE’s goal of increased geothermal drilling efficiency by 2025 through the development of a 300°C MEMS gyroscope for Measurement While Drilling (MWD). At the conclusion of the 2-year project, the team will develop a 300°C capable MEMS gyroscope containing GE’s patented Multi-Ring Gyroscope Transducer (MRGT) design, custom Silicon-On-Insulator (SOI) based frontend and feedback control electronics, and with demonstrated functionality and lifetime beyond 1000 hours. The project is divided into two budget periods with Go/No-Go decision at the end of the first budget period. The goal for the first budget period is to establish the feasibility of the MRGT and electronics design for meeting the 300°C performance requirements. The goal for the second budget period is to integrate the MRGT with the SOI-based application specific integrated circuit (ASIC) and demonstrate capability to operate at 300°C for 1000 hours. In Budget Period 1 we met the phase 1 goal. We successfully validated the combined MRG, electronics and packaging capability entitlement to achieving 0.5 degrees azimuth uncertainty while enabling operation at significantly higher temperatures than the state-of-the-art. In Budget Period 2, we successfully completed the integration of the MRGT and ASIC with associated high temperature, high reliability packaging to demonstrate the performance and functionality of the integrated gyroscope across the temperature range from room temperature to at 300°C. Furthermore, the team demonstrated operating life of >1,000 hours at 300°C, thus providing a validation of application-relevant lifetime capability.

High-Bi alloys are being explored to understand their potential as replacement for high-Pb alloys in high-temperature die-attach applications. Thermal conductivity of these alloys is an important consideration for die-attach applications, where heat dissipation is necessary for reliable operation of the devices. Pure Bi has a thermal conductivity of about 8 W/ $\text{m}\cdot \text{K}$ , which is the lowest among metals. The addition of the alloying elements to Bi had been explored to tailor its thermal, mechanical, and other physical properties. In this study, the role of Cu and Sb on the effective thermal conductivity of the resultant alloys was investigated. The thermal conductivities of these alloys in the bulk form and the three-layer die-attach form were measured using a flash diffusivity technique. Test specimens were developed to replicate a die-attach assembly between the Ni-metallized Si die and Cu substrate using the Bi– $x$ Sb–10Cu alloy (where $x =10$ –20 wt%). The three-layered structure was modeled with the unknown diffusivity of an intermediate layer of the Bi alloy. The alloy microstructure comprises a composite of Bi–Sb solid solution filled with Cu 2 Sb intermetallic particles. The presence of these intermetallic phases is responsible for an effective increase in thermal conductivity of this alloy. With the optimized microstructure developed, the resultant thermal conductivity was obtained at $\sim 24$ W/ $\text{m}\cdot \text{K}$ , which is a threefold increase compared to pure Bi.

There is growing interest in extreme temperature electronics to support the mission needs to sense, actuate, and communicate at temperatures beyond the normal range of operations in commercial and military applications. Reliable packaging in the temperature range of more than 300°C has been demonstrated using ceramic multi-chip modules using conventional hybrid circuit technology. This approach typically requires high NRE costs and lead time. Additive manufacturing processes of metals, ceramics, conductors, and dielectrics provides a digital transformation of hybrid circuit manufacturing technology that reduces time and cost for packaging with the added benefits of novel 3D structures and embedded features. This report presents the results of testing to characterize important electrical and mechanical properties of additively manufactured packaging materials (substrates, conductor, dielectrics) and die interconnect methods needed for 300 to 750 °C electronic packaging designs.

The orientation module of MWD tool provides the critical drill bit orientation information, including azimuth, inclination and toolface in order to control the path of wellbore. Although high end navigation grade gyroscope can meet the accuracy requirement for azimuth finding, the requirements of cost, size and reliability under harsh environment have largely limited the deployment of gyroscopes in MWD tools. To overcome these constraints, GE Research has developed a low cost, MEMS based Multi-Ring Gyroscope (MRG) capable of azimuth-seeking in MWD applications at 300°C. The MRG prototype has been demonstrated to achieve angular random walk (ARW) better than 0.003 deg/rt(hr) and bias instability of 0.01 deg/hr, capable of meeting azimuth finding accuracy better than 0.25 deg. It has also been tested to remain fully operational at 300 °C.

Highly stretchable, bio-compatible interconnects are of particular interest for medical and military applications as Wearable Performance Monitors (WPMs) and sensors. Screen printed trace interconnects on highly compliant Thermoplastic Polyurethanes (TPU) provides a low cost, viable option. But these stretchability has high ramification on the reliability aspects of WPM construction. In this paper, we perform the reliability testing of two screen printed inks under repeated mechanical loads 'as-printed' and after exposure to temperature and humidity.

Predominant high melting point solders for high-temperature and harsh environment electronics (operating temperatures from 200 to 250 °C) are Pb-based systems, which are being subjected to RoHS regulations because of their toxic nature. In this study, high bismuth (Bi) alloy compositions with Bi-XSb-10Cu (X from 10 wt % to 20 wt %) were designed and developed to evaluate their potential as high-temperature, Pb-free replacements. Reflow processes were developed to make die-attach samples made from the cast Bi alloys. Die-attach joints made from Bi-15Sb-10Cu alloy exhibited an average shear strength of 24 MPa, which is comparable to that of commercially available high Pb solders. These alloy compositions also retained original shear strength even after thermal shock (TS) between −55 °C and +200 °C and high-temperature storage (HTS) at 200 °C. Brittle interfacial fracture sometimes occurred along the interfacial NiSb layer formed between Bi(Sb) matrix and Ni metallized surface. In addition, heat dissipation capabilities, using flash diffusivity, were measured on the die-attach assembly and were compared to the corresponding bulk alloys. The thermal conductivity of all the Bi–Sb alloys was higher than that of pure Bi. By creating high volume fraction of precipitates in a die-attach joint microstructure, it was feasible to further increase thermal conductivity of this joint to 24 W/m·K, which is three times higher than that of pure Bi (8 W/m·K). Bi–15Sb–10Cu alloy has so far shown the most promising performance as a die-attach material for high-temperature applications (operated over 200 °C). Hence, this alloy was further studied to evaluate its potential for plastic deformation. Bi–15Sb–10Cu alloy has shown limited plastic deformation in room temperature tensile testing in which premature fracture occurred via the cracks propagated on the (111) cleavage planes of rhombohedral crystal structure of the Bi(Sb) matrix. The same alloy has, however, shown up to 7% plastic strain under tension when tested at 175 °C. The cleavage planes, which became oriented at smaller angles to the tensile stress, contributed to improved plasticity in the high-temperature test.

An advanced thermal interface material comprised of dense and orderly arrays of 10‐µm high Cu nanosprings with tunable normal and shear compliance, lateral stability due to spring intertwining, and thermal resistance below 1 mm 2 KW −1 is presented. The Cu nanospring films possess the compliance of soft polymers but up to 100 times higher thermal conductivity than materials with similar elastic modulus. This unique combination of mechanical and thermal properties makes it possible for the first time to populate the large empty space in the materials selection chart of thermal conductivity versus elastic modulus.

In an effort to replace Pb-based solders commonly used in high-temperature electronics (operating at 200°C or higher) with a new high-temperature capable material, we have developed a transient liquid phase (TLP) bonding between bismuth (Bi) and nickel (Ni) in our previous study. To address the reliability concerns and also to warrant the manufacturing efficiency of the TLP bonds, the current study was focused on the optimization of the interlayer structure and alloying via: i) thin bond-line-thickness (BLT) (<; 10 um), ii) intermediate BLT (20-40 um), and iii) thick BLT (> 60 um). These TLP bonded coupons were then tested for bonding reaction, microstructure development, and mechanical reliability. A thin BLT was made via sputter deposition of Bi on Ni-metallized die, which enabled a Ni layer (≈ 1 um) remaining during reflow without being completely consumed. The intermediate BLT sample was made using a Bi preform as in our previous study. For the thick BLT case, a powder/paste of Bi-xNi (from x=0 to 21.9 wt.%) was used. In particular, as pure Bi will not react with the Cu metallized surface (or Cu substrate), an interlayer consisting of Bi-Ni mixed powder/paste will enable Cu surface to be bondable with this TLP system. In this paper, the reflow conditions and the interlayer microstructures for the Bi-Ni TLP bonding with the three different approaches are discussed.

The development of reliable Flexible Hybrid Electronics (FHE) that are light, wearable and conforming to the human body while still preserving full operational integrity requires among other an understanding of the fatigue behavior of interconnects such as traces on flexible substrates (Polyimide, Polyethylene Terephthalate, etc.). There are different loading modes of potential concern, such as tension, bending and peeling. The present study addresses effects of tension on aerosol printed AgNP (silver nano-particles) traces. These traces are nano-porous and as such inherently brittle, but the presence of a flexible substrate has major effects on their behavior. Electroplated Cu traces are included for reference. Major increases in electrical resistance were observed for even minor deformation but inspection by SEM did not reveal any damage, and the presence of the substrate prevents the detection of changes in trace properties through direct measurement of deformation vs. the applied loads. Studies of the evolution of damage were therefore limited to characterization of the resistance vs. variations in strain. Interpretations of results were further complicated by the time-dependent viscoelastic deformation of the substrate. Nevertheless, systematic trends are appearing.