High-performance Electronic Systems Research Articles

Evaluation of Thermal and Mechanical Properties of Bi-In-Sn/WO3 Composites for Efficient Heat Dissipation.

Phase change materials (PCMs) offer promising solutions for efficient thermal management in electronic devices, energy storage systems, and renewable energy applications due to their capacity to store and release significant thermal energy during phase transitions. This study investigates the thermal and physical properties of Bi-In-Sn/WO3 composites, specifically for their use as phase change thermal interface materials (PCM-TIMs). The Bi-In-Sn/WO3 composite was synthesized through mechanochemical grinding, which enabled the uniform dispersion of WO3 particles within the Bi-In-Sn alloy matrix. The addition of WO3 particles markedly improved the composite's thermal conductivity and transformed its physical form into a putty-like consistency, addressing leakage issues typically associated with pure Bi-In-Sn alloys. Microstructural analyses demonstrated the existence of a continuous interface between the liquid metal and WO3 phases, with no gaps, ensuring structural stability. Thermal performance tests demonstrated that the Bi-In-Sn/WO3 composite achieved improved thermal conductivity, and reduced volumetric latent heat, and there was a slight increase in thermal contact resistance with higher WO3 content. These findings highlight the potential of Bi-In-Sn/WO3 composites for utilization as advanced PCM-TIMs, offering enhanced heat dissipation, stability, and physical integrity for high-performance electronic and energy systems.

Precision-induced localized molten liquid metal stamps for damage-free transfer printing of ultrathin membranes and 3D objects

Transfer printing, a crucial technique for heterogeneous integration, has gained attention for enabling unconventional layouts and high-performance electronic systems. Elastomer stamps are typically used for transfer printing, where localized heating for elastomer stamp can effectively control the transfer process. A key challenge is the potential damage to ultrathin membranes from the contact force of elastic stamps, especially with fragile inorganic nanomembranes. Herein, we present a precision-induced localized molten technique that employs either laser-induced transient heating or hotplate-induced directional heating to precisely melt solid gallium (Ga). By leveraging the fluidity of localized molten Ga, which provides gentle contact force and exceptional conformal adaptability, this technique avoids damage to fragile thin films and improves operational reliability compared to fully liquefied Ga stamps. Furthermore, the phase transition of Ga provides a reversible adhesion with high adhesion switchability. Once solidified, the Ga stamp hardens and securely adheres to the micro/nano-membrane during the pick-up process. The solidified stamp also exhibits the capability to maneuver arbitrarily shaped objects by generating a substantial grip force through the interlocking effects. Such a robust, damage-free, simply operable protocol illustrates its promising capabilities in transfer printing diverse ultrathin membranes and objects on complex surfaces for developing high-performance unconventional electronics.

Comparative Analysis of 5-Level and 7-Level Single-Phase Cascaded H-bridge Multilevel Inverters

The demand for high-performance, efficient, and reliable power electronic systems has been steadily increasing in various industrial applications, including renewable energy systems, electric vehicles, and smart grids. In response to this demand, the Cascaded H-Bridge Multi-level Inverter (CHB-MLI) has emerged as a promising solution, offering advantages such as improved voltage waveform quality, reduced harmonic distortion, and enhanced power handling capabilities. The CHB-MLI is characterized by its modular structure, comprising multiple H-bridge cells cascaded in series. Each H-bridge cell operates with a separate DC power source, enabling the generation of stepped voltage levels at the inverter output. By intelligently controlling the individual H-bridge cells, the CHB-MLI achieves the synthesis of a high-quality multilevel output voltage waveform. The different multi-level inverter topologies are Diode-Clamped MLI, Capacitor-Clamped MLI and Cascaded H-bridge MLI. This paper focused on key aspects like design, simulation, control strategies, performance evaluation, overall comparison and analysis of 5-level and 7-level CHB-MLIs. By addressing these aspects, this paper aimed to contribute to the advancement of power electronics technology and promote the adoption of the CHB-MLI in real-world applications, fostering energy efficiency and sustainability in power conversion systems. Index Terms: Inverter, Multi-level inverter, CHBMLI, switching, SPWM, MCSPWM, gate signal, waveform, harmonics, THD, MATLAB.

Molecular beam epitaxy and characterization of ferroelectric quaternary alloy Sc0.2Al0.45Ga0.35N

In this study, we demonstrate ferroelectricity in high-quality monocrystalline quaternary alloy ScAlGaN. Sc0.2Al0.45Ga0.35N films are grown by plasma-assisted molecular beam epitaxy and exhibit a surface roughness of 0.5 nm, limited by the roughness of the underlying molybdenum template. Polarization-electric field and positive-up-negative-down measurements reveal unambiguous ferroelectric switching with a coercive field of ∼5.5 MV cm−1 at 10 kHz and high remanent polarization of ∼150 μC cm−2. Time-dependent measurements suggest that the polarization reversal behavior adheres to the Kolmogorov–Avrami–Ishibashi model and follows a scheme of domain nucleation and growth. Detailed piezoresponse force microscopy studies further elucidate the evolution of polarity reversal domains in wurtzite nitride ferroelectrics and support the notion that the growth of inversion domains occurs via an in-plane motion of the domain walls. The realization of functional ferroelectric quaternary alloys in the wurtzite nitride family extends beyond being a technical demonstration. The additional degree of bandgap, band alignment, lattice parameter, and piezoelectric constant tunability achievable through quaternary alloys unveils a vast dimension through which wurtzite nitride ferroelectrics can be optimally engineered for a broad variety of high-performance electronic, optoelectronic, and acoustic devices and systems.

Electrical performance of La-doped In2O3 thin-film transistors prepared using a solution method for low-voltage driving.

In this paper, La-doped In2O3 thin-film transistors (TFTs) were prepared by using a solution method, and the effects of La doping on the structure, surface morphology, optics, and performance of In2O3 thin films and TFTs were systematically investigated. The oxygen defects concentration decreased from 27.54% to 17.93% when La doping was increased to 10 mol%, and La served as a carrier suppressor, effectively passivating defects such as oxygen defects. In fact, the trap density at the dielectric/channel interface and within the active layer can be effectively reduced using this approach. With the increase of La concentration, the mobility of LaInO TFTs decreases gradually; the threshold voltage is shifted in the positive direction, and the TFT devices are operated in the enhanced mode. The TFT device achieved a subthreshold swing (SS) as low as 0.84 V dec-1, a mobility (μ) of 14.22 cm2 V-1 s-1, a threshold voltage (VTH) of 2.16 V, and a current switching ratio of Ion/Ioff of 105 at a low operating voltage of 1 V. Therefore, regulating the doping concentration of La can greatly enhance the performance of TFT devices, which promotes the application of such devices in high-performance, large-scale, and low-power electronic systems.

Enhanced capillary performance of hierarchical dendritic copper surface for ultrathin heat-spreading devices

High-performance electronic systems require efficient heat dissipation devices. Vapor chambers (VCs) are practical thermal solutions for lightweight portable electronics that have limited heat dissipation space. A functional VC requires an interior wick to sustain the capillary circulation of the condensed fluid back to the heated region. The capillary wick performance can be indexed by the ratio of liquid permeability to the effective pore size of the wick structure. This study describes the capillary behavior of a thin hierarchical dendritic copper film (<100 μm thick) prepared by electrodeposition and thermal sintering. The effects of the electrodeposition current density, deposition time, and sintering temperature on the capillary performance of the dendritic copper films were investigated. The relationship between the wicking capability and dendritic morphology, tailored by the electrodeposition process, was explored. A post-deposition sintering treatment was found to be beneficial for improving the structural integrity, adhesion, and capillary performance of dendritic copper wicks. A very high capillary performance (0.81 μm) was realized on a 30-μm-thick dendritic copper wick that matches the need for ultrathin VCs used in highly compact electronic systems.

Influence of Element Lead (Pb) Content in Tin Plating on Tin Whisker Initiation/Growth

The implementation of the Restriction of Hazardous Substances (RoHS) European Union (EU) Directive in 2005 resulted in the introduction of pure tin as an acceptable surface finish for printed circuit boards and component terminations. A drawback of pure tin surface finishes is the potential to form tin whiskers. Tin whiskers are a metallurgical phenomenon that is associated with tin rich/pure tin materials and has been a topic of intense industry interest. The acceptance and usage of pure tin by the electronics industry component fabricators is understandable as the pure tin surface finishes are inexpensive, are simple plating systems to operate and have reasonable solderability characteristics. However, high performance/harsh environment electronics typically have product life cycles that are measured in decades and therefore are much more susceptible to the potential long term threat of tin whiskers. The GEIA-STD-0005-2 “Standard for Mitigating the Effects of Tin Whiskers in Aerospace and High Performance Electronic Systems” established the definition of the term “Pb-free tin” as : “Pb-free Tin is defined to be pure tin or any tin alloy with <3% lead (Pb) content by weight. A functional definition of “pure tin” was necessary so that the electronics industry could establish tin whisker risk protocols against a known acceptable target value in terms of soldering materials and processes. An investigation was conducted to determine the influence of 1% - 5% elemental lead (Pb) content in tin plating on tin whisker initiation and growth. The investigation results were used in the revision of the GEIA-STD-0005-2 “Standard for Mitigating the Effects of Tin Whiskers in Aerospace and High Performance Electronic Systems” specification technical discussions.

An Overview of Complex Instability Behaviors Induced by Nonlinearity of Power Electronic Systems with Memristive Load

The proposal of the memristor, considered as the fourth basic circuit element, suggests a new possibility for the design of high-performance power electronic systems. However, it also brings new challenges. At present, more and more electrical equipment and systems have demonstrated that their external characteristics can exhibit “8”-shaped hysteresis loops and can be regard as memristive equipment and systems. In order to satisfy the requirements of controllability, flexibility, efficiently, and so on, most memristive equipment and systems are not directly connected to the power grid but instead obtain their own required powering through various forms of power electronic converters. Note that memristive loads are distinctive and demonstrate unique nonlinear behaviors. Similarly, there can be nonlinearity from the resistor (R), inductor (L), or capacitor (C) load, but there is no combination of only R, L, and C that could produce memristive characteristics. In particular, the memristance of memristive devices changes continuously during the operation process; in addition, practical power electronic systems composed of memristive devices and power supplies have strong nonlinear characteristics, which are more likely to result in various complex behaviors and are not conducive to the stable operation of the systems. Therefore, exploring complex instability behaviors of power electronic systems with strong nonlinearity in depth is necessary for better protection and utilization of memristive devices. This paper provides an outline of the status of research on complex behaviors of power electronic systems with memristive load; it is expected to provide guidance for the study of complex behavior of strongly nonlinear systems.

Characterization and Optimization of the Heat Dissipation Capability of a Chip-On-Board Package Using Finite Element Methods

The present study endeavors to investigate the thermal dissipation capability of a chip-on-board package by means of a comprehensive experimental and numerical analysis. For this purpose, a BiCMOS chip is designed and fabricated in conjunction with three different printed circuit board configurations, including a single-sided board, a thermal via board, and a copper frame board. Transient thermal measurements are carried out on all three packages, and the results are subsequently transformed into cumulative structure functions. Then the finite element models are established for each package configuration, and their validity is confirmed through comparison with the experimental structure functions. The models are then characterized in accordance with the JEDEC 38-set boundary conditions, followed by a series of optimizations targeted towards the printed circuit board, including the board stack-up and the board sizes. Parametric studies are performed to quantitatively assess the impact of these parameters on the thermal performance. Finally, the present study provides a comprehensive discussion of the optimal application scenarios for each board configuration, with a view to achieving good thermal performance. The findings of this study will contribute to the development of more thermally effective chip-on-board packages for high-performance electronic systems.

A Review Study of Soft Electronic Materials for Epicardial Devices

Purpose: Heart failure is a widespread health concern. A person with a heart failure has 5 years shorter life expectancy compared to a person who has a cancer. Specifically, myocardial disease is usually involved with a treatment accompanied by an electrical conduction system. To alleviate the physical burden to heart due to ventricular pacing, epicardial electronic system made of soft and elastic materials is needed.
 Methodology: In this review, we discuss candidate materials for novel epicardial sensing/stimulation system that matches similar mechanical properties of heart. Materials are categorized as soft conductive materials consist of elastomer and conductive filler and tissue-like low modulus materials. Like hydrogel and its conductive composites.
 Main Findings: The soft nanocomposites integrated with nanomaterials as filler and elastomer/hydrogel as matrix show potential to open a new pathway in high-performance epicardial electronic system that improve accuracy, stability, and long-term usability in diagnosis and treatment of heart diseases.
 Implications: Multifunctional epicardial system that monitors electrical conduction of epicardium surface and stimulate epicardium simultaneously could be a powerful tool to diagnose and treat myocardial disease.
 Novelty: This review study is focused and written in simple terms for readers.

A Highly Efficient Si-/SiC-Based Hybrid Active NPC Converter With a Novel Modulation Scheme

With the increasing demand for high-performance power electronic systems, the semiconductor device utilization has gained significant importance. This article proposes the Si/SiC devices based active neutral-point-clamped converter comprising SiC-based H-bridge structure. A novel pulsewidth modulation (PWM) scheme is also proposed that results in an effective utilization of the switching devices. In the proposed converter, the Si devices are soft-switched for all power-factor loading conditions. Therefore, high efficiency can be obtained even at high switching frequency operation with wide range of power factor values. Further, the conduction losses of the SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s are minimized by strategically selecting the switching states in such a way that the SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s conduct in parallel conduction paths during the null state operation. This leads to further enhanced efficiency. This article presents the detailed operating principle of the proposed topology operated with the presented PWM scheme. Moreover, a device loss analysis is presented to evaluate the conduction and switching losses of the proposed topology. The presented experimental results validate the performance parameters of the proposed topology with the proposed PWM scheme. Finally, the proposed PWM scheme is compared with the existing PWM schemes using efficiency values of the proposed and some of the prominent existing converter configurations.

A New Strategy to Fabricate Nanoporous Gold and Its Application in Photodetector.

Nanoporous gold (NPG) plays an important role in high-performance electronic devices, including sensors, electrocatalysis, and energy storage systems. However, the traditional fabricating methods of NPG, dealloying technique or electrochemical reduction technique, usually require complex experimental procedures and sophisticated equipment. In this work, we reported a unique and simple method to prepare the NPG through a low-temperature solution process. More importantly, the structure of the NPG-based electrode can be further controlled by using the post-treatment process, such as thermal treatment and plasma treatment. Additionally, we also demonstrate the application of the resulting NPG electrodes in flexible photodetectors, which performs a higher sensitivity than common planar photodetectors. We believe that our work opens a possibility for the nanoporous metal in future electronics that is flexible, large scale, with facile fabrication, and low cost.

Simulation and Analysis of Microring Electric Field Sensor Based on a Lithium Niobate-on-Insulator

With the increasing sensitivity and accuracy of contemporary high-performance electronic information systems to electromagnetic energy, they are also very vulnerable to be damaged by high-energy electromagnetic fields. In this work, an all-dielectric electromagnetic field sensor is proposed based on a microring resonator structure. The sensor is designed to work at 35 GHz RF field using a lithium niobate-on-insulator (LNOI) material system. The 2.5-D variational finite difference time domain (varFDTD) and finite difference eigenmode (FDE) methods are utilized to analyze the single-mode condition, bending loss, as well as the transmission loss to achieve optimized waveguide dimensions. In order to obtain higher sensitivity, the quality factor (Q-factor) of the microring resonator is optimized to be 106 with the total ring circumference of 3766.59 μm. The lithium niobate layer is adopted in z-cut direction to utilize TM mode in the proposed all-dielectric electric field sensor, and with the help of the periodically poled lithium niobate (PPLN) technology, the electro-optic (EO) tunability of the device is enhanced to 48 pm·μm/V.

Anisotropic thermal conductivity of layered indium selenide

Layered indium selenide (InSe) has emerged as a promising two-dimensional semiconductor due to its high electron mobility and direct optical bandgap in the few-layer limit. As InSe is integrated into high-performance electronic and optoelectronic systems, thermal management will become critical, thus motivating detailed characterization of intrinsic thermal properties. Here, we report the room-temperature thermal conductivity of exfoliated crystals of InSe along the through-plane and in-plane directions using conventional and beam offset time-domain thermoreflectance (TDTR), respectively. InSe crystals with varying thicknesses were prepared by mechanical exfoliation onto Si(100) wafers followed by immediate encapsulation with a 3-nm-thick AlOx passivation layer to prevent ambient degradation prior to coating with metal films for TDTR measurements. The measured thermal conductivity in the in-plane direction, Λin ≈ 8.5 ± 2 W/m K, is an order of magnitude higher than that in the through-plane direction, Λthrough ≈ 0.76±0.15 W/m K, which implies a high thermal anisotropy ≈11 ± 3. These relatively high anisotropy and low thermal conductivity compared to other layered semiconductors imply that InSe will require unique thermal management considerations when implemented in electronic, optoelectronic, and thermoelectric applications.

The PINNs method discovery to the solution of coupled Wave- Klein-Gordon equations

Recently, the research of PDEs is regarded as one of the most important disciplines. Almost all scientific problems can be described by a differential equation, especially, many physical phenomena can be described by the system of coupled Wave-Klein-Gordon equations, which plays an important role in high-performance computing, control engineering, and electronic power system. Consequently, in our work, we use the PINNs to solve the numerical solution of coupled Wave-Klein-Gordon equations, to help us better understand the nonlinear physical phenomena, and to promote the rapid development of various fields such as in high-performance computing, control engineering, and electronic power system.

A High performance electronic nose system for the recognition of myocardial infarction and coronary artery diseases

Electronic noses are devices that detect the number and level of chemicals in an odor. This is accomplished by means of chemical gas sensors in the device’s structure. The device recognizes the odors that were introduced to it via the software. When we breathe air, several gas exchanges take place in our lungs (e.g., O2-CO2 at the alveola-capillary level). Some gases in our blood are presented with our breath. The detection of these gases can provide information about our health. Nowadays, many diseases can be diagnosed with very high accuracy by using an electronic nose. Despite advances in diagnoses and treatments, cardiovascular disease is still the leading cause of mortality worldwide. Coronary artery disease is the leading cause of cardiovascular mortality and morbidity. The ability to diagnose coronary artery disease from the breath will accelerate the diagnosis, and thus, the initiation of treatment, which may save many lives. This study, involved an investigation of whether or not diseases (e.g., myocardial infarction, stable coronary artery disease) can be diagnosed from exhaled respiratory air using an electronic nose. This involved collecting data on exhaled breath from 33 patients diagnosed with myocardial infarction that underwent a primary percutaneous coronary intervention, 22 patients with stable coronary artery disease and 26 patients without heart disease. An electronic nose containing 19 gas sensors was manufactured for this study. The respondents’ breath was collected in a sterile manner. The statistical features including mean, skewness, kurtosis and derivative variance were extracted from the breath samples. These features were classified for the entire database using the support vector machine classifier by selecting 66 % as a training set and 34 % as a test set. The breath from the myocardial infarction patients were separated from that of the healthy individuals and the stable coronary artery disease patients with a classification accuracy rate of 97.19 %. The breath from the stable coronary artery disease patients were separated from the breath of the healthy control subjects with a classification accuracy rate of 81.48 %. The results reveal that the proposed method has great potential for myocardial infarction, stable coronary artery disease and healthy subjects when the electronic nose is used to record the exhaled respiratory air of the participants.

Bend- and Twist-Insensitive Flexible Multimode Polymer Optical Interconnects

Polymer multimode optical waveguides can enable high-speed short-reach optical interconnection at low cost within high performance electronic systems. The formation of such waveguides on flexible substrates can offer important additional advantages such as light weight, ability to be tightly bent, and reconfigurability which are particularly important in environments where space, weight, and shape conformity are critical, for instance in vehicles and aircraft. The ability of such flexible optical interconnects to be tightly bent and twisted with low excess loss is crucial in enabling their use in systems with limited space and with movable parts. As a result, in this work, we present a new design of such flexible polymer multimode waveguides that achieves improved bending loss performance over the conventional waveguide design. It is experimentally shown that the proposed design achieves a very low excess loss of 0.5 dB for a 3 mm radius bend under a 50 μm MMF launch. In comparison, flexible waveguides with the conventional design exhibit a 2 dB excess loss under the same launch and bend conditions. Additionally, useful rules that associate the twisting loss performance of flexible polymer waveguide samples with their geometric characteristics are derived. It is shown that negligible twisting losses (<0.1 dB for a 50 μm MMF input) can be achieved when the dimensions of the waveguide samples are appropriately selected. The results demonstrate the strong potential of such bend- and twist-insensitive flexible polymer waveguides for use in next-generation vehicles and aircraft.

Programmable and scalable transfer printing with high reliability and efficiency for flexible inorganic electronics.

Transfer printing that enables heterogeneous integration of materials in desired layouts offers unprecedented opportunities for developing high-performance unconventional electronic systems. However, large-area integration of ultrathin and delicate functional micro-objects with high yields in a programmable fashion still remains as a great challenge. Here, we present a simple, cost-effective, yet robust transfer printing technique via a shape-conformal stamp with actively actuated surface microstructures for programmable and scalable transfer printing with high reliability and efficiency. The shape-conformal stamp features the polymeric backing and commercially available adhesive layer with embedded expandable microspheres. Upon external thermal stimuli, the embedded microspheres expand to form surface microstructures and yield weak adhesion for reliable release. Systematic experimental and computational studies reveal the fundamental aspects of the extraordinary adhesion switchability of stamp. Demonstrations of this protocol in deterministic assemblies of diverse challenging inorganic micro-objects illustrate its extraordinary capabilities in transfer printing for developing high-performance flexible inorganic electronics.

Light based synthesis of metallic nanoparticles on surface-modified 3D printed substrates for high performance electronic systems

Additive Manufacturing is capable of producing highly complex and personalised products. However, innovation in both material science and processing is required to achieve the performance, reliability and miniaturization of modern mass-produced electronic systems. This article presents a new digital fabrication strategy that combines 3D printing of high-performance polymers (polyetherimide) with light-based selective metallisation of copper traces through chemical modification of the polymer surface, and computer-controlled assembly of functional devices and structures. Using this approach, precise and robust conductive circuitry is fabricated across flexible and conformal surfaces omitting the need to connect and assemble separate circuits. To show how this process is compatible with existing electronic packaging techniques a range of modern components are solder surface mount assembled to selectively metalized bond pads. To highlight the potential applications stemming from this new capability, high frequency wireless communications, inductive powering and positional sensing demonstrators are manufactured and characterised. Furthermore, the incorporation of actuation is achieved through selective heating of shape memory alloys with a view towards routes towards folding and deployable 3D electronic systems. The results in this paper show how this process provides the required mechanical, electrical, thermal and electromagnetic properties for future real-world applications in the field of robotics, medicine, and wearable technologies.

Characterization of net coolant flow rate to copper boiling surfaces using two-phase particle image Velocimetry and dielectric fluid

Particle Image Velocimetry (PIV) has been widely used in fluid mechanics for various single and two-phase flow visualization studies. Using PIV, the net coolant flow rate required for quenching a copper circular heated surface under high heat flux pool boiling applications was quantified. The flow rate was calculated using a control surface analysis of all the periphery vectors surrounding the pool boiling activity. The vectors were deconstructed into their relevant Cartesian components using a custom Matlab code. The acquired data may be useful for empirical modeling of many practical high-performance electronic systems including thermosiphons and multi-component liquid immersion cooled servers. Boiling heat transfer fluxes ranging from 5.5 W/cm2 to 11 W/cm2 yielded quenching fluid flow rate requirements ranging from 1.7 g/s to 93.6 g/s. The highest heat flux tested, 11 W/cm2 is near the Critical Heat Flux (CHF) for the PF-5060 working fluid with a resulting maximum heat transfer coefficient of 8.8 kW/(m2K). With subcooled boiling conditions, it was found that as little as 2.5 °C reduction in pool temperature below the saturation point resulted in a 42% reduction in required coolant flow rate. A further reduction in the cooling flow rate requirement, 87% below the saturated pool condition, was found when the subcooling level was increased to 5 °C. When subcooling is introduced, transient conduction near the microlayer vapor/surface/liquid interface of bubble formation begins to be the dominant heat transfer mechanism.