Ceramic Housing Research Articles

Discussion of Mechanical Shock Test Stress for Ultra-large-scale CMOS Image Sensors

The ultra-large-scale CMOS image sensors are significantly different from the traditional CMOS image sensors in terms of pixel size, chip size and structure. CMOS image sensors generally come with an optical window structure that is sealed to the ceramic housing by means of adhesive. The optical window material is generally sapphire, and the larger the image element size, the larger the required glass optical window area. Ultra-large size CMOS image sensors in the package before the general optical window thickness, parallelism, light window average transmittance assessment. The object of mechanical impact test assessment is the CMOS image sensor optical window structure and capping process. The paper mainly discusses the typical failure cases of ultra-large-scale CMOS image sensors on the basis of the applicability of mechanical shock test standards, and investigates how to define the mechanical shock test stress from simulation, limit test and the requirements by users. This paper provides the qualification assessment basis of mechanical shock for newly developed products.

A STUDY ON SiC SUSCEPTOR CONFIGURATION FOR MICROWAVE HYBRID HEATING

Microwave hybrid heating (MHH) is a novel method to enhance ceramic sintering at high temperatures. The heating mechanism by MHH involves two directions of heat transfer for materials: microwaves heat the sample from the inside out, while the susceptor provides conventional heating from the outside. This unique heating mechanism offers several advantages, including uniform heating, rapid sintering, and enhanced microstructure and properties of materials. This study investigates the configuration of silicon carbide (SiC) susceptors for microwave hybrid heating. The microwave oven (multi-mode, 2.45 GHz, 1.2 kW) was modified with a ceramic insulator housing to maintain the temperature in the chamber. The effects of different configurations of SiC susceptors and microwave powers on the heating rate and maximum temperature were investigated. SiC susceptor plates were placed in the microwave oven using 3 different configurations, and for each condition, the microwave power was varied at 40, 60, 80, and 100% (480, 720, 960, and 1,200 W). The temperature in the microwave chamber was recorded until it reached 900°C or after 30 min of heating. Using two plates of SiC susceptor at 100 % power resulted in the highest heating rate of 62°C/min to reach 925°C. The results of this study offer guidance for the selection of appropriate heating conditions for individual ceramic materials, which can lead to more effective sintering processes.

Multi-Flanges for Intensive Cell Development and Lct Forlarge Cell and Stack Evaluation

Two new test benches have been developed at Fiaxell. One is the multi-Flanges allowing to test 4cells in one run. All the functionalities of the Open flanges, such as integrated steamer, real or idealcondition testing, ceramic housing on air side, gas processing are kept apart short stacking.The second test rig is the LCT for Large Cell Tester. It has been designed for cell dimensionstarting from 90 X 90 mm and ending with the size of 130 mm X 170 mm. Again all the OpenFlanges functionalities are kept. The LCT is no delivered for short stack of maximum 3 cells. In thesecond part of 2022, heat exchanger made with proper material will be ready for market. It willallows to test up to 30 cells. Figure 1

MOSFE-Capacitor Silicon Carbide-Based Hydrogen Gas Sensors

The features of the wide band gap SiC semiconductor use in the capacitive MOSFE sensors' structure in terms of the hydrogen gas sensitivity effect, the response speed, and the measuring signals' optimal parameters are studied. Sensors in a high-temperature ceramic housing with the Me/Ta2O5/SiCn+/4H-SiC structures and two types of gas-sensitive electrodes were made: Palladium and Platinum. The effectiveness of using Platinum as an alternative to Palladium in the MOSFE-Capacitor (MOSFEC) gas sensors' high-temperature design is evaluated. It is shown that, compared with Silicon, the use of Silicon Carbide increases the response rate, while maintaining the sensors' high hydrogen sensitivity. The operating temperature and test signal frequency influence for measuring the sensor's capacitance on the sensitivity to H2 have been studied.

Inductive proximity sensors within a ceramic package manufactured by material extrusion of binder-coated zirconia

The embedding of electric components into additively manufactured structures offers enormous potential for extending the functionality and applications of parts produced by additive manufacturing (AM). However, the production of electric components embedded with 3D-printed ceramic structures has been a significant challenge due to the complexity of the manufacturing process and the high-temperature post-processing it requires. In the present study, an inductive proximity sensor with a 3D-printed ceramic housing and embedded sensing elements was designed and produced using a hybrid manufacturing process in which the printing process is paused and a sensing element is embedded into the printed structure. Sensing elements materials were carefully selected and intra-sensor structures were developed to ensure that the sensing element would survive in a high-temperature sintering environment. In the developed process, binder-coated zirconia containing 87 wt% was used as feedstock in a piston-based material extrusion process to fabricate the ceramic housing for the sensor, and platinum wire was used in the sensing element. The subsequent debinding and sintering processes achieved a nearly fully dense ceramic housing that protects the sensor in harsh environments. The successfully fabricated sensor was tested by measuring the change of distance between the inductive and metallic target and determining if the changes in distance would alter the inductance of the sensor. Results show that the sensing element maintains functionality throughout each fabrication step, and the fully packaged sensor also demonstrates the ability to work properly at high temperatures (in the range of 200–400 °C). At a frequency of 2 MHZ and a voltage of 1 V, the inductive sensor has a measurement range of approximately 7.0 mm. Additive manufacturing of the sensor housing enabled precise control of the geometry, dimensions, and infill density. Because the developed methodology allows for control of the type and structure of the sensing element, it can be used in the manufacture of a wide variety of sensors or smart components.

RF Pogo-Pin Probe Card Design Aimed at Automated Millimeter-Wave Multi-Port Integrated-Circuit Testing

A prototype RF probe card is assembled to test the feasibility of Pogo-pins as robust probe tips for the automized testing of multiple-port millimeter-wave circuits. A custom-made ceramic housing machined from a low-loss dielectric holds an array of 157 Pogo-pins, each with 2.9 mm-length in fixed positions. The ceramic housing is then mounted onto a probe-card PCB for power-loss measurements on two signal-ground Pogo-pin connections arbitrarily selected from the array. The probing results on a test circuit with a simple thru-line indicate a successful power transfer with a small insertion loss of less than 0.5 dB per single Pogo-pin connection up to 25 GHz. A new probe card design using shorter Pogo-pins is being prepared to extend the operation frequency to beyond 40 GHz.

Flexible and Modular Fully Metallic Housing Concept for Solid Oxide Fuel Cells

The state-of-the-art alumina oxide housings used in single cell test rigs are fragile, inflexible and expensive. They are designed for a specific cell geometry, a change of the cell type - changing the cell thickness - or a change in the cell size is not intended and is thus associated with an immense expenditure of effort and time. In detail, the state-of-the-art ceramic frame concept is vulnerable to a fracturing of the frame or an insufficient contacting of the cell if a change in the cell thickness occurs. The connection of the ceramic housing with the typically metallic tubing of the gas supply is fragile, prone to develop leakages and is time consuming to replace and thereby prevents a change of the cell size. Gold wire seals used at the cathode side are a common source of leakage. Furthermore, the whole ceramic housing is sensitive to fracturing due thermal or load induced stress, and thus prevents fast thermal cycling of the specimen.This paper presents a modular, fully metallic housing concept which enables a fast and easy change of the cell size due to the utilization of a baseplate and a robustness towards different cell thicknesses due to the usage of a flexible metallic frame. The utilization of metal instead of alumina oxide reduces the manufacturing costs. Furthermore, an additional sealing on the cathode side enables a separation of the contacting pressure via a pneumatic piston from the sealing pressure applied via metallic screws. The force of the sealing pressure is not applied onto the cell and is thereby limited by the material constraints and not by the mechanical stability of the cell. For accurate voltage measurements, sense wires are separated from the current collection and are electrically isolated from the metallic housing. Thermocouples are used to measure the temperature distribution inside the anodic part of the housing, as close as possible to the cell. The chromium evaporation of the cathode part of the housing is reduced by a protective coating and the utilization of double layered tubes. In the end, the results of preliminary tests are presented.

Standalone micro-reformer for on-demand hydrogen production from dimethyl ether

Entering a new era of sustainable energy generation and consumption, micro-fuel cells are showing great potential for providing high energy density to consumer electronics, and micro-reactor technology can indeed enable their integration by providing hydrogen on-demand from hydrocarbons. In this work, we present the design and fully scalable wafer-level fabrication of a MEMS-based catalytic micro-reactor tested in real-life operating conditions by means of a 3D printed ceramic housing. The device consists of an array of thousands of vertically aligned micro-channels, 500 μm in length and 50 μm in diameter, for an overall superficial area per unit volume of 120 cm2 cm−3 and it embeds a thin-film heater for efficient reaction start-up. For the first time, functionalization of the micro-reactor is entirely achieved by atomic layer deposition (ALD) and rapid thermal processing (RTP), resulting in the uniform coating of a Pt/Al2O3 heterogeneous catalyst hereby tested for steam reforming (SR) and partial oxidation (POX) of dimethyl ether (DME). Here, conversion rates up to 74% and hydrogen selectivity of ~60% are obtained by steam reforming at 650 °C, while a specific volumetric hydrogen production of 4.5 mLH2 mL−1DME cm−3REACTOR at 600 °C is obtained from DME POX.

A New Press Pack IGBT for High Reliable Applications With Short Circuit Failure Mode

The modular multilevel converter (MMC or M2C) technology becomes the mainstream solution in today's voltage source converter-high voltage direct current (VSC-HVDC) transmission lines because of its unique performance. Recently press pack IGBT (PPI) has come into focus as a preferred realization for high power rating VSC-HVDC stations, it could offer the highest current rating IGBTs and advanced features in reliability. A new PPI is introduced in this paper, which is designed for several innovative improvements based on the application demands from VSC-HVDC systems. The chip is optimized for low on-state voltage with advanced trench technology, and well protected in a chip-stack by double side sinter process. The disc package is designed with hermetic sealed ceramic housing to avoid environmental erosion and could provide a robust feature of short circuit failure mode (SCFM), which is fully qualified under the worst-case scenario. In addition to the PPI device, system solutions had also been developed and investigated to support field developments, including electrical and mechanical design. An example of a power stack is analyzed in commutation loop, pressure distribution, and power losses.

Effect of selected representative biomass gasification tar compounds on Ni-GDC solid oxide fuel cells

Contaminants as particulate matter, sulfur, chlorine and tar should be removed from biosyngas to avoid damaging solid oxide fuel cells. However, there is no sufficient information on tar effect since they might be potentially used as a fuel, or they might cause performance losses and irreversible damages. Therefore, this study aims to assess whether tar can be reformed inside the SOFC and used as fuel. Short-duration experiments were conducted on Ni-GDC cells operating with simulated biosyngas containing different concentrations of representative tar compounds from biomass gasification. While benzene and ethylbenzene could be regarded as additional fuels even at concentrations as high as 15 g/Nm3, naphthalene and phenanthrene act as contaminants for the SOFC electrochemical and catalytic reactions, even at concentrations of 0.3 and 0.05 g/Nm3. However, the effect on these reactions appeared almost completely reversible. Solid carbon deposited on the SOFC ceramic housing in proximity of the inlet. Post-mortem analysis should be performed to asses the tar effect on the cell anode.

Pump Thrombosis, Scratching the Surface

Pump thrombosis (PT) remains a serious complication in patients supported with a ventricular assist device (VAD). In our institution, HeartWare HVAD patients with PT are thrombolysed with systemic Alteplase infusion until restoration of normal power consumption or maximum infusion duration of 20 hours. Although most PT events resolve with single thrombolysis, PT can re-occur requiring further thrombolysis and/or pump exchange. In this prospective exploratory observational study, we opened and inspected all explanted pumps that required thrombolysis for PT. VADs were retrieved post-heart transplantation and opened for inspection. All impeller (rotor) surfaces, and internal upper and lower pump housing surfaces were inspected and photographed. From August 2017 through September 2019, 7 patients (mean age 54±7.6 years, 57% male) were thrombolysed for PT with a median duration of support to first thrombolysis of 307 days (range, 99 to 852 days). Five patients were thrombolysed once, 1 twice and 1 three times. Clinical parameters and pump power consumption returned to normal for each thrombolysis event for all patients. Inspection of the pump at explant was normal in all cases, except for the patient thrombolysed multiple times. In that patient (thrombolysed on days 99, 154, 204), the lower surface of the impeller was worn on one edge, suggesting impeller imbalance with corresponding marking on the ceramic housing surface. (Image) CONCLUSION: Patients with recurrent PT episodes requiring thrombolysis may have changes in pump surface not previously reported. Pump replacement may be warranted in these cases. Whether this is due to impeller instability or other factors is unknown. Routine inspection of explanted pumps may provide insights into thrombosis mechanisms.

Terahertz Detection With a Low-Cost Packaged GaAs High-Electron-Mobility Transistor

We present experimental results of an investigation into the performance of a commercial, packaged GaAs high-electron-mobility transistor (HEMT) as a detector of terahertz (THz) radiation in the frequency ranges 0.22–0.32 and 0.520–0.650 THz. Enclosed in a standard ceramic housing and without a dedicated antenna for radiation coupling, the transistor is capable of sensitive direct detection (power detection) of THz radiation at room temperature. The device responsivity shows a strong variation with wavelength, indicating that various device features (transistor metallization, contact pads, wires) act as an effective THz antenna. With the THz radiation focused with a parabolic mirror (and without a substrate lens), the maximum responsivity reaches 2.5 and 0.72 V/W with values of the minimum optical noise-equivalent power (NEP) of 1.4 and 2.5 nW/ $\sqrt{\mathrm{Hz}}$ at the sensitivity peaks at 0.271 and 0.632 THz, respectively. The performance of the HEMT, in comparison with antenna-coupled FET detectors optimized for THz detection (TeraFETs), can be assessed better if the responsivity and the NEP are referred to the effective antenna cross-section determined experimentally for the device. We arrive at a cross-sectional responsivity of 42 V/W (1.6 V/W) and a cross-sectional NEP of 135 pW/ $\sqrt{\mathrm{Hz}}$ (1250 pW/ $\sqrt{\mathrm{Hz}}$ ) at 0.271 THz (0.632 THz), for measurements through the ceramic cap. The cross-sectional NEP values are about one order of magnitude at 0.271 THz and two orders of magnitude at 0.632 THz higher than those achieved with the best TeraFETs, yet in a range where they enable many practical applications at low cost for the detector.

Numerical analysis of flow configurations and electrical contact positions in SOFC single cells and their impact on local effects

Predictable long-term operation is key to the industrial roll-out of SOFC technologies; as one of the primary factors hindering steady and reliable operation, performance degradation is one of the main challenges facing SOFC development. A homogeneous temperature profile is essential to the steady long-term operation of SOFC cells. In order to investigate and improve the temperature distribution across the cells, a ceramic housing was developed for an industrial scale (100×100mm2) SOFC single cell with the aid of a spatially resolved numerical model. This study investigated the influence of co-, counter-, and cross-flow configurations, as well as various electrical contact positions in order to analyse the current density distribution and temperature evolution within the cell. The chemical and electrochemical performance of the model were validated with in-house experimental data gained from operating the cell within the developed cell housing under three hydrogen/nitrogen mixtures of varying levels of humidification. The simulations revealed that the outermost parts of the cathode are subject to diffusion limitations, which can lead to local air starvation effects. Moreover, they showed that the position of the cell's electrical contacts has a distinct impact on the current density distribution, in addition to affecting the temperature profile of the cell. This study found that the counter-flow configuration, in combination with placing the electrical contacts on the inlet side of the cathode led to the most homogeneous current density and temperature distribution across the cell. Most importantly, the position of the electrical contacts was identified as having a major influence on the cell's current density profile, and these position changes were able to homogenize the temperature distribution across the electrolyte. This configuration is thus proposed as a viable method of both ensuring the steady long-term operation of SOFCs and prolonging their lifetimes.

Measurements and Analyses of Electro-Exploding Products Generated by Semiconductor Bridge Igniters

In an effort to investigate the characteristics of electro-exploding products generated by Al/CuO-semiconductor bridge igniters, high-speed camera and spectrum diagnosis systems are employed in this paper. By using the high-speed camera system, the electro-exploding processes are recorded and the results indicate that electro-exploding processes include extrinsic conduction, intrinsic excitation, melting, vaporization, plasma discharging, and Al/CuO combustion. During this process, the spatial dimensions of plasma could reach to 8.7 mm in vertical direction under excitation energy of $47~\mu \text {F}/50~\text {V}$ . Meanwhile, the Al/CuO films are ejected from ceramic housing by plasma shock wave, combust upon plasma and plume. According to the results from the spectrum diagnosis system, it is noted that the temperature maintains 4000–6500 K for $65~\mu \text{s}$ .

Ceramic and hybrid support insulators for UHVDC systems

The requirements for UHVDC installations in terms of length, mechanical strength, permissible deflection, creepage distance, shed profiles and pollution resistance are still a challenge for all existing technologies and solutions. Based on the positive long time experience with solid core porcelain post insulators and the pollution experience of insulators with silicone housings the fundamental concept of both were used to develop a new type post insulator with inside ceramic core and housing of silicone. The challenge was to provide a reliable and economical solution, which combines the advantages of both technologies. Realising the needs for high strength, low deflection under load for many applications PPC Insulators Austria began the development of hybrid post insulators. The ceramic solid core design provides superior advantages in terms of bending strength, also for torsion load and compression load. The silicone rubber housing allows thinner sheds and greater creepage distances, provides improved long term pollution flashover performance and protects the core from short circuit arc damage. As design for DC hybrid post insulators was chosen upright tapered, uniform and underhung tapered insulators columns stacked of single hybrid insulator sections. The single sections could be varied in core diameter, length, creepage distance, fittings and holepattern. The shed profile used for DC applications was defined according the recommendations given by CIGRE. Selected design tests, electrical and mechanical type tests were conducted according to the relevant parts of IEC standards for composite and ceramic insulators. Also a long term test installation was performed to establish a confidence in this product. The long term test installation has been energized at 725 kV DC and later the voltage was increased to 761 kV DC. The tests have served well in providing final qualification. Beside these voltage tests measurements of ESDD/NSDD, hydrophobicity and also visual inspections were carried out. The mechanical properties were driven from the seismic requirements and have been calculated by finite element modelling of the reactor and its support structure. For post insulators with silicone rubber sheds and with solid core porcelain may be the most stable solution and this type has been adopted in different 800 kV projects. One of the new insulator was chosen for smoothing reactor support for 800 kV DC system in India.

Results for a New SOFC-Stack Design with Parallel-Connected Cells

The TU Clausthal and CUTEC institute have teamed up to design, build and test a new stack architecture, based on repeating units with cells connected in parallel. This approach allows the use of electrically conducting seals like brazes and can be realized without any glass sealing. Unlike conventional (serially connected) stacks, where all cells operate at the same current but individual voltage, in this setup each cell contributes as much current as possible at a common voltage. Thereby accelerated degeneration caused by undervoltage and the associated oxidation of the nickel catalyst can be completely overcome. The concept uses two cells in electrical parallel connection with the anodes facing each other to form a repeating unit. Two designs have been realized: An all ceramic housing made from 3YSZ, sealed with reactive air brazing (RAB) and a metallic one with a Crofer 22 APU housing, joined by laser beam welding. The housing materials have been chosen with respect to their thermal expansion coefficient (TEC) matching the TEC of the used ESC cells. Special interconnectors have been produced via hydroforming to create an even flow field while providing sufficient contact area. The paper will focus on the test results of the repeating units under various operation conditions and the analysis of the degradation of components and joints. Polarization curves for the twincell repeating unit and the individuell cells under H2 and air at 880°C are depicted in figure one. Figure 1

Results for a New SOFC-Stack Design with Parallel-Connected Cells

The TU Clausthal and CUTEC have teamed up to design, build and test a new SOFC stack architecture, based on repeating units with cells connected in parallel. This approach allows the use of electrically conducting seals like brazes and can be realized without any glass sealing. Unlike conventional (serially connected) stacks, where all cells operate at the same current but individual voltage, in this setup each cell contributes as much current as possible at a common voltage. Thereby accelerated degeneration caused by undervoltage and the associated oxidation of the nickel catalyst can be completely overcome. The concept uses two cells in electrical parallel connection with the anodes facing each other to form a repeating unit. Two designs have been realized: An all ceramic housing made from 3YSZ, sealed with reactive air brazing (RAB) and a metallic one with Crofer 22 APU housing, joined by laser beam welding.

Extraocular Surgical Approach for Placement of Subretinal Implants in Blind Patients: Lessons from Cochlear-Implants.

In hereditary retinal diseases photoreceptors progressively degenerate, often causing blindness without therapy being available. Newly developed subretinal implants can substitute functions of photoreceptors. Retina implant extraocular surgical technique relies strongly on cochlear-implant know-how. However, a completely new surgical approach providing safe handling of the photosensor array had to be developed. The Retina Implant Alpha IMS consisting of a subretinal microphotodiode array and cable linked to a cochlear-implant-like ceramic housing was introduced via a retroauricular incision through a subperiosteal tunnel above the zygoma into the orbit using a specially designed trocar. Implant housing was fixed in a bony bed within a tight subperiosteal pocket in all patients. Primary outcomes were patient short term safety as well as effectiveness. Nine patients participated in the first part of the multicenter trial and received the subretinal visual implant in one eye. In all cases microphotodiode array pull-through procedure and stable positioning were possible without affecting the device function. No intraoperative complications were encountered. The minimally invasive suprazygomatic tunneling technique for the sensor unit as well as a subperiosteal pocket fixation of the implant housing provides a safe extraocular implantation approach of a subretinal device with a transcutaneous extracorporeal power supply.

Colored ceramic foams with tailored pore size and surface functionalization used as spawning plates for fish breeding

The growing demand for reliable porous substrate materials for aquaculture of marine ornamental fishes (i.e. substrate spawners) requires a controllable processing in combination with a straightforward functionalization to adjust both, the material properties and the surface physico-chemical characteristics. In this study, highly porous ceramic foams made of alumina obtained by direct foaming are presented, which are conditioned for controlled aeration of egg clutches laid by clownfishes serving as model organisms for marine substrate spawners. Increasing stirring velocities during preparation of high alkane phase emulsified suspensions (HAPES) lead to decreased µm-scaled foam pore sizes, while similar high open porosities of around 80% are achieved. Wet-chemical silanization using hexadecyltrimethoxysilane (HDTMS) followed by subsequent oxygen plasma treatment of the foam surface is applied to generate bifunctionalized foams with hydrophobic matrix and hydrophilic surface properties. Under marine aquarium conditions, external aeration through the hydrophobic matrix of the foam is applied marginally below bubble point pressures resulting in a significant increase of the dissolved oxygen concentration of the surrounding water close to the foam surface without formation of undesired air bubbles. In accordance with increased foam pore sizes oxygen saturation rates of 0.26, 0.49 and 0.85%/min are obtained ensuring high oxygen concentrations at the spawning plate within a few hours. Assemblies of five bifunctionalized spawning plates to a ceramic housing are accepted by clownfish pairs, laying their eggs directly on the aerated ceramic substrate. The presented spawning plates are highly promising for sustainable aquaculture of marine ornamental fishes aiming to improve the survival rate of early life stages.

Temperature characterization of flip-chip packaged piezoresistive barometric pressure sensors

In order to miniaturize piezoresistive barometric pressure sensors, a new flip-chip packaging technology has been developed. The thermal expansions of chip and package are different. So in a standard flip-chip package the strong mechanical coupling by the solder bumps would lead to stress in the sensor chip, which is unacceptable for piezoresistive pressure sensors. To solve this problem, in the new packaging technology the chip is flip-chip bonded on compliant springs to decouple chip and package. As the first step of the packaging process an under bump metallization (UBM) is patterned on the sensor wafer. Then solder bumps are printed. After wafer-dicing the chips are flip-chip bonded on copper springs within a ceramic cavity housing. Due to the compliance of the springs, packaging stress is induced into the sensor chip. As sources of residual stress the UBM and the solder bumps on the sensor chip were identified. Different coefficients of thermal expansion of the silicon chip, the UBM and the solder lead to plastic straining of the aluminum metallization between UBM and chip. As a consequence the measurement accuracy is limited by a temperature hysteresis. The influence of the chip geometry, e.g., the thickness of the chip or the depth of the cavity, on the hysteresis was investigated by simulation and measurements. As a result of this investigation a sensor chip was designed with very low residual stress and a temperature hysteresis which is only slightly larger than the noise of the sensor.