Actual Electronic Devices Research Articles

Flexible Inductance Pressure Sensor for Wearable Electronic Devices

Currently, wearable devices have higher requirements for flexible sensors based on environmental adaptability. Therefore, in order to solve the problem of low sensitivity of current flexible sensors, a new type of flexible inductance pressure sensor is proposed by introducing a ferrite film with high permeability into traditional flexible sensors. The validity and practicability of this method are verified by the research. The results show that the correlation curve of theoretical prediction shows the same trend as the actual curve. Sensor A showed the highest sensitivity of 1.61 kPa−1; Under different bending conditions, the sensitivity difference is 0 ∼ 0.20. When the actual external pressure is increased from 0 to 13.6 Pa, the actual change of inductance is about 0.88%. When the excitation voltage is 0.5 V, the actual inductance output value of sensor A increases from the initial 13.22 μH to 13.26 μH, and the actual change rate is less than 0.30%. In the application of wearable devices, the keys of wearable electronic keyboard have the maximum output voltage variation value, which is greater than 0.15 V, improving the high stability and practicality of the sensor. It is also practical in wearable human respiratory signal detection equipment. In summary, the flexible inductance pressure sensor designed in this study has high performance and practicability in the application of wearable electronic devices, which is of great significance to the development of actual wearable electronic devices.

Prediction of heat transfer characteristics in a microchannel with vortex generators by machine learning

Abstract Because of the prompt improvements in Micro-Electro-Mechanical Systems, thermal management necessities have altered paying attention to the compactness and high energy consumption of actual electronic devices in industry. In this study, 625 data sets obtained numerically according to the change of five different geometric parameters and Reynolds numbers for delta winglet type vortex generator pairs placed in a microchannel were utilized. Four dissimilar artificial neural network models were established to predict the heat transfer characteristics in a microchannel with innovatively oriented vortex generators in the literature. Friction factor, Nusselt number, and performance evaluation criteria were considered to explore the heat transfer characteristics. Different neuron numbers were determined in the hidden layer of each of the models in which the Levethenberg–Marquardt training algorithm was benefited as the training algorithm. The predicted values were checked against the target data and empirical correlations. The coefficient of determination values calculated for each machine learning model were found to be above 0.99. According to obtained results, the designed artificial neural networks can provide high prediction performance for each data set and have higher prediction accuracy compared to empirical correlations. All data predicted by machine learning models were collected within the range of ±3% deviation bands, whereas the majority of the estimated data by empirical correlations dispersed within ±20% ones. For that reason, a full evaluation of the estimation performance of artificial neural networks versus empirical correlations data is enabled to fill a gap in the literature as one of the uncommon works.

Modeling of High-Voltage Nonpunch-Through PIN Diode Snappy Reverse Recovery and Its Optimal Suppression Method Based on RC Snubber Circuit

The snappy reverse recovery (SRR) and failure of high-voltage nonpunch-through (NPT) PIN diodes under extreme working conditions are of great significance to the reliability evaluation of operating diodes in actual power electronic devices. In this article, the analysis of the physical mechanism of the diode SRR and the restrictions of the traditional PT-PIN diode model are made. Then, the traditional model for soft recovery is improved in order to accurately describe the diode SRR characteristics. Simulations of key dynamic performances of the established model agree well with the experimental results. Furthermore, a suppression method for diode SRR based on the optimal RC snubber circuit is proposed. A high-voltage NPT-PIN diode used in the dc−dc converter with different RC snubber circuits is simulated using the proposed diode snappy model and tested. The comparison results show good consistency between the simulated and measured voltage and current peaks and the diode SRR are suppressed effectively. The developed model and results are of much importance to the prediction of the safe operation area of the diode and to the reliability improvement of power electronic device.

Experimental study of flat-disk loop heat pipe with R1233zd(E) for cooling terrestrial electronics

• A flat evaporator made of aluminum alloy was designed for ground applications. • R1233zd(E), an eco-friendly refrigerant, was selected as the working fluid. • The LHP could dissipate the heat of 190 W with an effective length of 790 mm. • The thermal performance was stable even at heat sink temperature of 30 °C. • The minimum LHP thermal resistance was 0.197 °C/W at 0 °C heat sink temperature. Flat evaporator loop heat pipes with good thermal performance and compact volume have been widely used in electronic device applications. A flat-disk evaporator loop heat pipe made of aluminum alloy was designed for terrestrial application in this paper. R1233zd(E) was selected as the working fluid for its ultra-low toxicity and environmentally friendly. The pumping force of the system, driving the working fluid circulation, was generated by the sintered capillary wick made from nickel powder. Considering the requirements for electronics and the capillary limit of the wick together, the target temperature was below 75 °C and the effective heat transfer length was set as 790 mm. With a heat sink temperature of −10 °C, it could dissipate the heat of 190 W (11.43 W/cm 2 ). The performance investigation under bad external conditions was also carried out. A relatively broad operating range between the heat load of 10 W (0.60 W/cm 2 ) and 130 W (7.82 W/cm 2 ) was observed with a 30 °C heat sink temperature. However, slight temperature overshoot occurred during the start-up test but the system was able to self-regulate and stabilize quickly. Moreover, the variable heat load test, imitating the heat-dissipating demand for actual electronic devices, demonstrated that this system responded fast and operation failure did not happen. The minimum thermal resistance of the evaporator and the total LHP was 0.134 °C/W and 0.197 °C/W, respectively.

Identifying the coefficients of thermal expansion of an electronic device composed of various materials using the virtual fields method

A method for inverse determination of the coefficients of thermal expansion of an electronic device that is composed of multiple materials, i.e. dissimilar materials, is proposed. The virtual fields method is applied for obtaining the coefficients of thermal expansion. Appropriate virtual displacement fields have been automatically obtained instead of using any arbitrary virtual displacement. This leads to an accurate and effective determination of the coefficient of thermal expansion. Full-field displacement distributions measured by digital image correlation are used as input for the inverse analysis. The validity of the proposed method has been demonstrated by measuring samples made of various materials. Furthermore, the proposed method is applied to samples simulating electronic devices with and without constraints on the boundary. Results show that the coefficients of thermal expansion of an object composed of dissimilar materials are obtained properly. The proposed method is expected to be used for determining the coefficients of thermal expansion of actual electronic devices.

Fatigue Mechanism of Die-Attach Joints in IGBTs Under Low-Amplitude Temperature Swings Based on 3D Electro-Thermal-Mechanical FE Simulations

Fatigue failure of insulated gate bipolar transistor modules (IGBTs) packages under low-amplitude temperature swings is of great significance for the reliability evaluation of IGBTs operating in actual power electronic devices. In this article, failure mechanism of die-attach joints in IGBTs under normal operating and accelerated aging was comparably investigated by a three-dimensional electro-thermal-mechanical coupled model. Results indicated that local viscoplastic deformation of solder alloys around stress concentrated areas caused by material microdefects is the root cause of fatigue of die-attach joints under low-amplitude temperature swings. Fatigue cracks can only initiate and propagate at those plastically deformed areas (activation points). Fatigue of die-attach joints is co-determined by the number of activation points and crack growth rate. Comparably, the whole die-attach solder is in viscoplastic deformation under accelerated aging and the number of activation points has reached its saturation. Fatigue of die-attach joints under accelerated aging is only determined by the crack growth rate. Due to the difference in failure mechanism, it is questionable to directly extend conventional life models to normal operating conditions. Accordingly, an energy-based physical life model for die-attach joints in IGBTs under low-amplitude temperature swings was proposed.

Constructal design and experimental validation of a non- uniform heat generating body with rectangular cross-section and parallel circular cooling channels

Non-uniform heat generating phenomenon is omnipresent in real electronic devices. A three-dimensional model with non-uniform heat generation is established in this paper. Both fluid flow and heat transfer behaviors are uncovered with the consideration of constructal theory. Constructal theory enables a heat transfer system to evolve and generate to provide a better flow access for the currents that flow through it. Taking a complex function composed of hot spot temperature and pumping power as the performance indicator, the diameter of cooling channels and the aspect ratio of elemental body are optimized as two degrees-of-freedom. The physical problem is numerically solved by resorting to the finite element method. The optimization was performed by the exhaustive search technique, comparing all results generated by finite element method. The heat generation over the entire body and the volume ratio of cooling channels operate as the prior constraints. On this basis, the optimal geometries of the elemental component are obtained in cases of various heat generating premises. The obtained results demonstrate that the complex function behaves an extreme value for the dimensionless cooling channel diameter. It is observed that the minimum value of the complex function slumps by 29.3% as the number of elements increases from 10 to 30. The overall thermo-fluid performance of the non-uniform heat generating body can be elevated as the elemental body features a square cross-section by releasing the new degree-of-freedom of aspect ratio to morph. Furthermore, alumina ceramics are used as the heat generating substrate and water as the coolant. The validity of the mathematical model is corroborated by experiments. Oriented to industrial applications, it is implied that the coolant entryway should be placed prone to the place where more electronic components or heat generating devices situate. The optimization results can put new suggestions on the thermal design of actual electronic devices from both theoretical and experimental perspectives.

Ion chromatographic determination of total bromine in electronic devices in conjunction with a catalytic reduction debromination pretreatment

A new determination method for total bromine in electronic devices was developed by using ultrasound assisted extraction, copper-catalyzed reductive debromination and ion chromatography (UAE-RD-IC). It was found that all the added brominated flame retardants (polybrominateddiphenyl ethers, polybrominated biphenyls, tetrabromobisphenol A, and hexabromocyclododecane) could be completely debrominated by using copper-based catalysts and reducing agent N2H4•H2O. The complete debromination of brominated flame retardants released all of their bromine in the form of bromide ions, which could be determined by ion chromatography. After the extraction parameters were optimized by achieving the maximum IC signal in the certified reference material GBW(E) 082725, the UAE-RD-IC method was established for the determination of total bromine in solid samples. By analyzing the certified reference material, the Br content was obtained as 695.3 ± 16.0 mg kg−1, being well consistent with its standard value (694.54 ± 30.63 mg kg−1). The relative standard deviation (RSD) of five parallel determinations was 1.7%, indicating the good repeatability of the developed method. The proposed method was further applied to analyze the samples of cables and computer mouse shells. For all these practical samples, the Br contents obtained by the UAE-RD-IC method were in good agreement with that obtained by the standard oxygen bomb combustion-IC method. It was noted that the new method has a detection limit of Br of about 20 mg kg−1, being much lower than that (75 mg kg−1) of the traditional oxygen bomb combustion-IC method for total bromine detection. Therefore, the proposed method was qualified as a practical method to measure total bromine content in actual electronic devices with good analytical performances of accuracy, precision and sensitivity.

The effect of oxidation concentration on the adhesion between flexible substrate and metal layer in metal transfer process using UV curable polymer

There has been a recent trend towards the application of transfer processes to produce an electric circuit on a flexible polymer substrate. However, adhesion between the circuit layer and the target substrate in the transfer process is typically insufficient due to non-conformal contact between two layers or low-surface energy of the target substrate. To solve this problem, ultraviolet (UV) curable resin was proposed as an adhesive layer between the circuit layer and the polymer substrate. This study experimentally analyzed the effect of oxidation concentration on the adhesion between a substrate and metal layer in metal transfer process using UV curable polymer. We also demonstrated that controlling the degree of cure of acrylate UV-curable resin, which varies depending on the oxygen concentration of the atmosphere, was shown to be an effective method to improve adhesion to the polymer substrate and prevent metal patterns from being damaged in the transfer process by adjusting the oxygen concentration under atmospheric conditions. As a feasibility study on the transfer process for actual electronic devices, a metal pattern for RTD (resistance temperature detector) was transferred on a polymer film and characterized with the electrical resistance of the pattern.

A 64-pin Nanowire Surface Fastener Like a Ball Grid Array Applied for Room-temperature Electrical Bonding

Surface-mount techniques primarily depend on soldering. However, soldering techniques have encountered some challenges in recent years. These challenges include rare metal recycling, thermal problems, and Pb toxicity. We recently developed a metallic nanowire surface fastener (NSF) to resolve the abovementioned problems. This fastener can be used to connect electronic components on a substrate at room temperature using the van der Waals force between each nanowire. This study demonstrates a 64-pin NSF that behaves like a ball grid array (BGA) for application to actual electronic devices. The adhesion strength and electrical properties of the NSF were investigated by adjusting the nanowire parameters, such as diameter, length, density (number per area), preload, and shape. The shape control of the nanowires greatly contributed to the improvement of the properties. A maximum adhesion strength of 16.4 N/cm2 was achieved using a bent, hook-like NSF. This strength was 4–5 times the value of the straight NSF. The contact resistivity was 2.98 × 10−2 Ω∙cm2. The NSF fabricated through the simple template method showed the room temperature bonding ability and adaptability to a highly ordered electrode like the BGA.

Adaptive learning rule for hardware-based deep neural networks using electronic synapse devices

In this paper, we propose a learning rule based on a back-propagation (BP) algorithm that can be applied to a hardware-based deep neural network (HW-DNN) using electronic devices that exhibit discrete and limited conductance characteristics. This adaptive learning rule, which enables forward, backward propagation, as well as weight updates in hardware, is helpful during the implementation of power-efficient and high-speed deep neural networks. In simulations using a three-layer perceptron network, we evaluate the learning performance according to various conductance responses of electronic synapse devices and weight-updating methods. It is shown that the learning accuracy is comparable to that obtained when using a software-based BP algorithm when the electronic synapse device has a linear conductance response with a high dynamic range. Furthermore, the proposed unidirectional weight-updating method is suitable for electronic synapse devices which have nonlinear and finite conductance responses. Because this weight-updating method can compensate the demerit of asymmetric weight updates, we can obtain better accuracy compared to other methods. This adaptive learning rule, which can be applied to full hardware implementation, can also compensate the degradation of learning accuracy due to the probable device-to-device variation in an actual electronic synapse device.

Optical and electrical properties of the transparent conductor SrVO3 without long-range crystalline order

It has been shown recently that the perovskite oxide SrVO3 is a transparent conductor with optical and electrical properties outreaching those of the most used material indium tin oxide (ITO). These properties, observed in the crystalline phase, imply the strong potential of SrVO3 for use as a lower cost alternative to ITO, but the possible integration of this perovskite oxide material in actual electronic devices is still an open question. One of the possible approaches for the integration of oxide materials is the use of amorphous thin films, allowing low thermal budgets to preserve the performances of the electronic device. Therefore, in this study, the electrical and optical properties of amorphous or poorly crystallized thin SrVO3 films are investigated.

Selective Thermochemical Growth of Hierarchical ZnO Nanowire Branches on Silver Nanowire Backbone Percolation Network Heaters

The development of hydrothermal growth enabled facile growth of ZnO nanowire over a large area at mild environments, yet its usage in actual electronic devices has been restricted due to poor spatial selectivity in the growth and a difficulty in the integration to other components. We introduce a local thermochemical growth of ZnO nanowire branches on Ag nanowire backbone percolation networks by electrical current induced local resistive heating in liquid environment for easy fabrication of metal–semiconductor hierarchical nanowire structure. Through vacuum filtration transfer and laser ablation process, patterned conductive network composed of ZnO nanoparticle functionalized Ag nanowire percolation network was prepared as a conductive network for localized resistive heating. Upon the application of proper bias voltage, highly localized temperature field was generated in the vicinity of the patterned Ag nanowire network heater to induce the selective growth of ZnO nanowire from the Ag nanowire backbone. As the temperature rise is related to the electrical current flow, ZnO nanowire was selectively synthesized at the area subject to the maximum current density, which was defined by the laser ablation technique. It was further confirmed that the characteristics of grown ZnO nanowires could be controlled by changing the growth condition.

Combined analysis of energy band diagram and equivalent circuit on nanocrystal solid

We investigate a combined analysis of an energy band diagram and an equivalent circuit on nanocrystal (NC) solids. We prepared a flat silicon-NC solid in order to carry out the analysis. An energy band diagram of a NC solid is determined from DC transport properties. Current-voltage characteristics, photocurrent measurements, and conductive atomic force microscopy images indicate that a tunneling transport through a NC solid is dominant. Impedance spectroscopy gives an equivalent circuit: a series of parallel resistor-capacitors corresponding to NC/metal and NC/NC interfaces. The equivalent circuit also provides an evidence that the NC/NC interface mainly dominates the carrier transport through NC solids. Tunneling barriers inside a NC solid can be taken into account in a combined capacitance. Evaluated circuit parameters coincide with simple geometrical models of capacitances. As a result, impedance spectroscopy is also a useful technique to analyze semiconductor NC solids as well as usual DC transport. The analyses provide indispensable information to implement NC solids into actual electronic devices.

A Color-Tunable Polychromatic Organic-Light-Emitting-Diode Device With Low Resistive Intermediate Electrode for Roll-to-Roll Manufacturing

A flexible organic-light-emitting diode (OLED) with capability to show 16 million colors is fabricated on plastic barrier-film substrate, which can produce arbitrary shape with arbitrary colors, suitable for artistic expressions. Independently controlled red, green, and blue light-emitting layers are stacked vertically, so that no visible structure can be observed even with magnifiers from right-in-front measurement. In the past, large voltage drop of intermediate electrode was preventing this approach to be applied to actual electronic devices. However, according to the surface mobility control using Fick’s law analysis, low sheet resistance 7.34 $\Omega $ /□ on plastic film is developed, so that 7.17-cm2 area emission is successfully achieved. With optical length optimization for each color stack, more than 100% color reproduction in National Television Committee Standard is achieved by stack design. The device can be used for colored illumination, as well as for organic-light-emitting display pixels for three times emission than the conventional pixel design. The device is fabricated on plastic substrate, so that the polychromatic OLED device is manufacturable with roll-to-roll production line.

Fault self-repair strategy based on evolvable hardware and reparation balance technology

In the face of harsh natural environment applications such as earth-orbiting and deep space satellites, underwater sea vehicles, strong electromagnetic interference and temperature stress, the circuits faults appear easily. Circuit faults will inevitably lead to serious losses of availability or impeded mission success without self-repair over the mission duration. Traditional fault-repair methods based on redundant fault-tolerant technique are straightforward to implement, yet their area, power and weight cost can be excessive. Moreover they utilize all plug-in or component level circuits to realize redundant backup, such that their applicability is limited. Hence, a novel self-repair technology based on evolvable hardware (EHW) and reparation balance technology (RBT) is proposed. Its cost is low, and fault self-repair of various circuits and devices can be realized through dynamic configuration. Making full use of the fault signals, correcting circuit can be found through EHW technique to realize the balance and compensation of the fault output-signals. In this paper, the self-repair model was analyzed which based on EHW and RBT technique, the specific self-repair strategy was studied, the corresponding self-repair circuit fault system was designed, and the typical faults were simulated and analyzed which combined with the actual electronic devices. Simulation results demonstrated that the proposed fault self-repair strategy was feasible. Compared to traditional techniques, fault self-repair based on EHW consumes fewer hardware resources, and the scope of fault self-repair was expanded significantly.

InSb Czochralski Growth Single Crystals for InGaSb Substrates

ABSTRACTThe massive crystal growth of single crystal semiconductors materials has been of fundamental importance for the actual electronic devices industry. As a consequence of this one, we can obtain easily a large variety of low cost devices almost as made ones of silicon. Nowadays, the III-V semiconductors compounds and their alloys have been proved to be very important because of their optical properties and applications. It is the case of the elements In, Ga, As, Sb, which can be utilized for the fabrication of radiation sensors. In this work we present the results obtained from the ingots grown by the Czochralski method, using a growth system made in home. These results include anisotropic chemical attacks in order to reveal the crystallographic orientation and the possible polycrystallinity. Isotropic chemical attacks were made to evaluate the etch pit density. Metallographic pictures of the chemical attacks are presented in this work. Among the results of these measurements, the best samples presented in this work showed mobilities of 62.000 cm2/V*s at room temperature and 99.000 cm2/V*s at liquid nitrogen temperature. Typical pit density was 10,000/cm2. The Raman spectra present two dominant peaks associated at Transversal Optical (TO)- and Longitudinal Optical (LO)-InSb, the first vibrational mode is dominant due to the crystalline direction of the ingots and second one is associated to high defects density.

Research on Electrical Power System with Information Modeling and SCL Description of IED for Transformer Condition Monitoring Based on IEC61850

A transformer is a critical device in an electrical power system substation. Monitoring its condition, including insulation material statuses, is imperative. This article discusses the information modeling techniques of IEC61850 and modeling steps of condition-monitoring IED, analyzes the reporting service, focuses on the characteristics of transformer condition monitoring, rationally develops and makes use of logical nodes and data in the IEC61850 standard, conducts modeling for the actual intelligent electronic device (IED) of transformer condition monitoring and describes the model with substation configuration description language (SCL). The configuration file of this model has passed the test done with standard syntax (Schema mode).

Application Study of 3D Display Technology in EDA Experiment

Experiment is an important part in the teaching process of electronic technology course, and EDA virtual experiment provides an interactive, active participatory and responsive learning environment for the students by creating a virtual environment. This learning environment can help students to grasp the theoretic knowledge from classroom learning faster and better, deepen the understanding of basic concepts and principles and be familiar with the use of commonly used electronic instruments, which would promote the cultivation of students' quality. Moreover, in the environment of 3D display, students can observe three-dimensional objects from different perspectives and won't be confused with the excessive crosses of conductor design, so as to strengthen their feelings on the actual electronic devices.

Nanocharacterization of Relaxation Properties in Organic Thin Film Electronic Materials

AbstractWith increased molecular complexity of organic thin film electronics, novel characterization methods are required to provide nanoscale material property information. Particularly important in polymer thin film electronics are methods characterizing the mobility properties of materials that are in amorphous unsteady states. If the unsteady nature of materials is paired with dimensional and interfacial constraints in anisotropic systems, such as thin films, it produces material systems of great challenges with enormous engineering potentials. Two examples are addressed in this paper, involving desired and undesired supramolecular alignments in polymer thin films, the spectral stability in organic blue-light emitting diodes and the electro-optical (EO) activity in organic non-linear optical (NLO) materials, in conjunction with novel scanning probe microscopy (SFM) based characterization tools. The nanoscopic methods discussed here, i.e., shear modulation force microscopy (SM-FM), and nanoscale isothermal friction analysis (NIFA), offer a quantitative approach for investigating the mobility/stability of organic semiconductor polymer films. Thereby, local properties such as energy barriers for sub-molecular motions (relaxations) and critical transition temperatures can be directly inferred from organic films that are used in actual electronic devices.