Electrothermal Analysis Research Articles

Thermal analysis for optimized selection of cooling techniques for SiC devices in high frequency switching applications

The inception of wide bandgap power semiconductors has paved way for the evolution of highly efficient power switches. A deep understanding about the thermal characteristics of the SiC power device is essential to utilize its advantages in terms of higher thermal and power handling capability. The primary objective of this paper is to establish an accurate thermal model by proposing and comparing different methodologies for thermal analysis of commercially available SiC device, which in turn will aid to select optimum cooling techniques for higher system efficiency. Exponential curve fitting technique was exploited to deduce the parameters for RC equivalent network model. A high frequency sinusoidal pulse width modulated SiC MOSFET inverter with a fixed load was considered for electro-thermal analysis using a unified software platform PLECS. The effect of switching frequency on heat sink volume was established through simulation studies with imbibed datasheet parameters of a commercial power device. Finally, a 3-D model of the commercially available SiC power MOSFET in SOT-227B package was built to analyse the device heat dissipation profile for an optimized cooling choice. The proposed modelling approach serves to provide a platform for the thermal optimization of power devices and can be extended to other semiconductor devices.

Modeling and Analysis of Electro-Thermal Impact of Crosstalk Induced Gate Oxide Reliability in Pristine and Intercalation Doped MLGNR Interconnects

This work presents the electro-thermal analysis of crosstalk effects in pristine (undoped) and intercalation doped multilayer graphene nanoribbon interconnects (MLGNRs). A temperature dependent distributed $T-$ network model of MLGNR interconnects has been developed for analyzing the crosstalk induced effects. Further, a temperature-aware gate oxide reliability model has been proposed to compute the crosstalk induced overshoot/undershoot impact on ultra-thin gate oxide for CMOS devices in terms of failure-in-time (FIT) for side-contact (SC) pristine as well as top-contact (TC) Arsenic pentafluoride ( $AsF_{5}$ ), Ferric chloride ( $FeCl_{3}$ ) and Lithium ( $Li$ ) intercalation doped and undoped MLGNR interconnects. Subsequently, comparisons with $Cu$ -based interconnects are made over a range of chip operating temperature from 233K to 450K.

EM-Electrothermal Analysis of Semiconductor Power Modules

We present in this paper an advanced electromagnetic (EM)-electrothermal analysis approach for the semiconductor power devices, with illustration on the insulated-gate bipolar transistor (IGBT) modules. This method distinguishes itself by dynamically integrating the EM domain into the circuit-type electrothermal coupling analysis, thus enabling the multi-dimensional simulation that spans in time from nanoseconds to seconds, and in space from chip level to system level. In particular, it contains a parametric-extracted electrothermal model of the IGBT chip and a comprehensive 0-D thermal network as well as an EM network extracted from the 3-D module packaging structure for each paralleling chip. The incorporation of the EM, as well as thermal networks representing the 3-D packaging structure, reveals essential information about the current imbalance, power dissipation imbalance, and thermal imbalance inside the IGBT module with paralleling chips, which have a strong influence on the module reliability. To demonstrate the application of this approach, an unfavorably designed 1700-V/450-A half-bridge IGBT power module is evaluated in the simulation circuit, with experimentally verified electrothermal IGBT chip model and thermal as well as EM networks. The results have shown that the EM-electrothermal analysis can successfully reveal the dynamic interaction among different physical domains and, thus, the current as well as temperature imbalance among the paralleling chips inside the power module. The predicted current imbalance also agrees with that from the experimental test.

Investigation of graphene as a material for electrical contacts in the application of microrelays using finite element modeling

This paper investigates the use of Graphene (Gr) as an electrical contact material for the application of microrelays. Gr is an ideal material for microelectromechanical systems (MEMS) and nanoelectromechanical systems (NEMS). A microrelay has been considered and electrothermal analysis is carried out based on Finite Element Modeling (FEM) using COMSOL Multiphysics simulation tool. Electrical contact surfaces for the material Al, Cu, Ag and Gr have been analyzed. The electrical contact resistance, voltage drop, current density, resistive losses and temperature of the contact interface has been obtained. The results obtained have been verified using theoretical calculations. Also, the combustion voltage of Gr electrical contact has been obtained as 0.2 V at which the Gr reaches its combustion temperature of 623 K. The results show that Gr electrical contact performs better in terms of electrical and thermal performance parameters which would be used in future electrical components.

Sensing properties of sulfonated multi-walled carbon nanotube and graphene nanocomposites with polyaniline

Abstract Here, we discuss one of the simplest approaches for chemical functionalization of in-situ prepared polyaniline (Pani) and its nanocomposites with multi-walled carbon nanotubes (MWCNT) and graphene (GN) in chlorosulphonic acid. The effect of polymerization and functionalization was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analysis, Field emission scanning electron microscopy (FESEM) and electro-thermal analysis. Results also revealed the presence of π−π interactions between Pani and carbon allotropes leading to the formation of charge-transfer complexes. This strong π−π interaction significantly increased the resultant electrical conductivity, stabilizing them as well. Further, theirs back to back sulphonation in chlorosulphonic acid significantly enhanced the solubility in one way but caused a heavy loss in conductivity conversely. The thermoelectric properties of the as-prepared nanocomposites were investigated as a function of MWCNT and GN contents. It was observed that as-prepared Pani/GN nanocomposites showed a greater electrical conductivity as well as an improved thermal stability in terms of DC electrical conductivity retention under isothermal and cyclic ageing conditions compared with Pani/MWCNT and Pani. Finally these oxidative products were also studied for their sensing response towards amine to detect whether the particular compound is either 1°, 2°, or 3° amine.

Electrothermal Optimization of Field Grading Systems of Station Class Surge Arresters

An electrothermal simulation based procedure for the optimization of the field grading systems of station class surge arresters is presented. The main difficulty consists in the numerical solution of the three-dimensional (3-D) field grading system, and the transient electric field problem that arises when a field grading system is introduced. Therefore, we first develop an equivalent axisymmetric arrester model that can reproduce the electric field stress in the resistor column with high accuracy. The model employs a special virtual electrode geometry whose shape and position are determined by a multi-parametric optimization procedure. On the basis thereof, a numerical optimization of the 3-D grading system for an arbitrarily large arrester can be efficiently performed on the basis of transient, electroquasistatic simulations of its axisymmetric equivalent. This procedure is demonstrated for the standard International Electrotechnical Commission (IEC) surge arrester. The detailed electrothermal analysis of this arrester shows that an immense improvement of the field and thermal stress distribution in the resistor column can be obtained.

Electro-thermal assessment of heterojunction tunnel-FET for low-power digital circuits

To overcome the fundamental limitations of conventional MOSFETs, tunnel field effect transistors (TFETs) with strained-SiGe channel (via heterogeneous integration) may be used and is demonstrated using TCAD simulations. We mainly focus on the design and implementation of silicon-germanium (SiGe)-based tunnel field effect transistor, aiming to reduce the device operation voltage down to below 0.5 V. Physics-based electro-thermal simulations are performed for evaluating the self-heating (temperature rise) in the devices. We present the results of the electro-thermal analysis supported by effective 2D and 3D device simulations. Performance improvement in drain current as high as 200% has been achieved.

Electro-thermal assessment of heterojunction tunnel-FET for low-power digital circuits

To overcome the fundamental limitations of conventional MOSFETs, tunnel field effect transistors (TFETs) with strained-SiGe channel (via heterogeneous integration) may be used and is demonstrated using TCAD simulations. We mainly focus on the design and implementation of silicon-germanium (SiGe)-based tunnel field effect transistor, aiming to reduce the device operation voltage down to below 0.5 V. Physics-based electro-thermal simulations are performed for evaluating the self-heating (temperature rise) in the devices. We present the results of the electro-thermal analysis supported by effective 2D and 3D device simulations. Performance improvement in drain current as high as 200% has been achieved.

Discharge and electrothermal efficiency analysis of capacitive discharge plasma synthetic jet actuator in single-shot mode

Gas discharge plasma techniques have been applied successfully in a wide range of fields. As one of these techniques, plasma synthetic jet (PSJ) actuator shows promising application in high-speed flow control. However, for practical application to aircraft, the capacity of the power source is very limited. So the energy efficiency optimization of PSJ actuator is vital to its longtime effective performance. The overall efficiency of PSJ actuator can be divided into three parts: discharge efficiency, electrothermal efficiency and exhaust efficiency. In this paper, discharge and electrothermal efficiencies of a home-designed and manufactured two-electrode PSJ actuator working in single-shot mode and normal atmosphere are evaluated experimentally. The influence of circuit parameters and actuator configurations are investigated and analyzed as a reference for optimization. The results show that, discharge efficiency is basically determined by the resistance ratio of the RLC circuit. The parasitic resistance of the circuit has a great influence on discharge efficiency due to the very short length and low resistance of the plasma arc (O (100 mΩ)). Electrothermal efficiency seems to be less affected by the circuit parameters and actuator configurations compared to discharge efficiency. The variation extent of electrothermal efficiency is around 50–70% for the tested conditions. Smaller discharge chamber volume produces PSJ with higher speed, but will reduce electrothermal efficiency. For a certain overall input energy required, a design of smaller capacitance and wider anode-to-cathode distance is highly recommended to increase both discharge efficiency and electrothermal efficiency.

Finite Element-Based Parametric Studies of Nugget Diameter and Temperature Distribution in the Resistance Spot Welding of AISI 304 and AISI 316L Sheets

Resistance spot welding (RSW) of dissimilar metals is prominent in automobile industries to utilize the material properties of both the metals. RSW of dissimilar austenitic stainless steel sheets (AISI 304/316L) is investigated in this paper by varying the process parameters such as welding current and weld time at three different levels. Tensile shear test and macrostructural examinations are carried out to analyze the performance of spot welds. A three-dimensional model is also developed using commercial finite element analysis software ABAQUS FEA to predict the nugget diameter and thermal distribution profile through simultaneous structural electrothermal analysis with temperature-dependent material properties. The generated model is validated by comparing the predicted nugget diameter with experimental nugget diameter. Experimental results show good coherence with the simulation results, and the macrostructure of the spot-welded joints indicates successful welding of dissimilar sheets with defect-free fusion zone.

Electro-thermal RF modeling and performance analysis of graphene nanoribbon interconnects

This paper presents an electro-thermal radio frequency (RF) model and performance analysis for multilayer graphene nanoribbon (MLGNR) interconnects. The number of conduction channels is calculated as a function of temperature and Fermi energy. A comprehensive model is developed to calculate the temperature dependent effective mean free path (MFP) considering different scattering mechanisms. The RF model of doped and undoped metallic top-contact (TC), as well as side-contact (SC) MLGNR interconnects is demonstrated using ABCD parameter based multi-conductor transmission line formalism. The RF performance of arsenic pentafluoride ( $$\text {AsF}_5$$ ), lithium (Li) and ferric chloride ( $$\text {FeCl}_3$$ ) intercalation doped TC-MLGNR interconnects is investigated and compared with pristine (undoped) TC and SC-MLGNR interconnects for different temperatures. For the first time, our investigation shows that the electro-thermal RF performance of TC-MLGNR can be improved by intercalation doping. It is found that $$\text {AsF}_5$$ , Li and $$\text {FeCl}_3$$ intercalated top-contact MLGNR can operate up to a few GHz for semi-global interconnects ( $$100\,\upmu $$ m) and several MHz for global interconnects ( $$500\,\upmu $$ m). Our analysis also proves that the Li intercalated TC-MLGNR shows the best RF performance as compared to conventional copper, pristine, and other type of intercalation doped TC-MLGNR interconnects over the chip operating temperature range from 233 to 378 K. The performance of Li intercalated TC-MLGNR has been found to be improved further by increasing the specularity during fabrication.

Electrothermal coupling analysis and experimental verification for wirebond devices

The thermal performance of a powered wirebond device with package level and board level test specimens was investigated by both analytical and experiment methods. The effects of thickness and thermal conductivity of the molding compound and heat spreader attached to the top surface of the molding compound on the performance of the Au wire and silicon die were modeled and evaluated by three-dimensional electrothermal coupling analysis. An advanced quad flat no-lead (QFN) sample was selected to experimentally measure the maximum allowable current in Au wire for packages either with or without molding compound. Two failure modes, namely the fusing of the wire and the decomposition temperature of the molding compound, were established in analysis. A board level test specimen with a thermal test die was also employed to measure the real time package thermal performance. The major achievement of this work is in the complete combination of modeling, experiment, and optimization for thermal performance evaluation purpose of a powered wirebond device. Results of this physical analysis can provide a reliable and useful guide to estimate the maximum allowable currents in Au wires for a wirebond device under practical application conditions.

Sulphonated polyaniline/MWCNTs nanocomposite: preparation and promising thermoelectric performance

Here is concise description of in situ prepared polyaniline and its nanocomposite with multi-walled carbon nanotubes followed by sulfonation. Thus, prepared materials were characterized by Fourier transform infrared spectroscopy, X-ray diffraction analysis, field emission scanning electron microscopy and electro-thermal analysis. Incorporation of ultrasonicated multi-walled carbon nanotubes significantly increased the electrical conductivity due to π–π interaction of polyaniline with multi-walled carbon nanotubes and its back to back sulfonation further rendered fortification. Finally, as-prepared nanocomposite showed greater electrical conductivity as well as improved thermal stability in terms of DC electrical conductivity retention under isothermal and cyclic aging conditions.

Electro-thermal buckling of elastically supported double-layered piezoelectric nanoplates affected by an external electric voltage

PurposeThermal buckling of double-layered piezoelectric nanoplates has been analyzed by applying an external electric voltage on the nanoplates. The paper aims to discuss this issue.Design/methodology/approachDouble-layered nanoplates are connected to each other by considering linear van der Waals forces. Nanoplates are placed on a polymer matrix. A comprehensive thermal stress function is used for investigating thermal buckling. A linear electric function is used for taking external electric voltages into account. For considering the small-scale effect, the modified couple stress theory has been applied. An analytical solution has been used by taking various boundary conditions.FindingsEEV has a considerable impacted on the results of various half-waves in all boundary conditions. By increasing EEV, the reduction of critical buckling temperature in higher half-waves is remarkably slower than lower half-waves. By considering long lengths, the effect of EEV on the critical temperature will be markedly decreased.Originality/valueThis paper uses electro-thermal stability analysis. Double-layered piezoelectric nanoplates are analyzed. A comprehensive thermal stress function is applied for taking into account critical temperature.

Electrothermal Analysis With Nonconvective Boundary Conditions

Electrothermal analogy allows heat conduction and heat convection to be modeled as a simple resistive or RC network. A practical environment in which a chip is located is often not purely convective. Nonetheless, the environment is typically approximated as convective for simplicity of analysis. This yields inaccuracy of temperature estimation; ad-hoc calibration process is necessary to match estimation and measurement by empirically adjusting thermal parameters. In this brief: 1) we extract electrothermal analogy through mathematical derivation and 2) this allows us to understand how the basic resistive network can be modified to handle non-convective environment accurately. The new network is applied in the estimation of steady-state and transient temperature as well as in thermal design power. A smartphone under the sunlight is assumed as an example of non-convective environment. Estimation of steady-state temperature using our network is compared to actual measurement, which demonstrates its accuracy.

Ambient Temperature-Induced Device Self-Heating Effects on Multi-Fin Si n-FinFET Performance

Device self-heating effects (SHEs) in nonplanar Si MOS transistors such as fin field-effect transistors (FinFETs) and nanowire FETs have become a serious issue in designing well-tempered CMOS devices for future logic nodes. The device thermal contact resistances are strongly influenced by both the ambient temperature and within device lattice temperature. The ambient heat energy coupling through the thermal contact resistances will strongly impact device SHE in FinFETs due to increase in the surface-to-volume ratio of confined geometry thin Si Fin. In this paper, we report a 3-D quantum-corrected electrothermal numerical device analysis involving a coupled hydrodynamic and thermodynamic transport models for a target Si 3-Fin bulk n-FinFET. The numerical device simulations quantitatively predicted the impact of ambient and electrical contact temperatures on device short-channel effect immunity and performance. The simulation parameters are calibrated with the state-of-the-art Si FinFET measurement data from the literature. Our numerical simulation findings establish the phenomena of ambient temperature-induced device SHE on Si n-FinFETs performance for sub-14-nm technology nodes. The simulation predictions establish the fact that the thermal contact resistances and the within-chip ambient temperature ( ${T}_{A}$ ) have adverse effects on device lumped thermal resistance ( ${R}_{\text {th,eff}}$ ) and performance metrics. Finally, we have numerically analyzed the FinFET design solutions (tapered source and drain regions) to improve the tolerance against the ambient temperature-induced SHE.

Lifetime estimation of modular cascaded H-bridge MLPVI for grid-connected PV systems considering mission profile

Recently, in grid-connected Photovoltaic (PV) systems, the modular cascaded H-bridge Multilevel PV Inverters (MLPVIs) has attracted many researchers because of high-quality output waveform with each semiconductor device operating at the lower switching frequency and a possibility to reach high-voltage without using the step-up transformer in high-voltage grid-connected PV systems, which reduce the system cost. The inverter is one of the most unreliable parts of the PV system operating in different environmental conditions, and the MLPVI requires more number of power semiconductor switches, which increases the probability of failure. In order to provide reliable operation, it is important to predict the lifetime of an inverter by considering the mission profile. This paper mainly concentrates on the lifetime estimation of the modular cascaded H-bridge MLPVI by considering the mission profile. The power loss calculation and electro-thermal analysis have been conducted to unveil the thermal loading of MLPVI. A cycle counting algorithm has been applied to recognize the mean junction temperature and amplitude of the temperature swings of each thermal cycle. A Monte Carlo analysis is used to obtain the lifetime distribution of the power devices by considering the parameter variation. At last, the lifetime of a 5-kW grid-connected 1-phase, 5-level modular cascaded H-bridge MLPVI is studied based on the lifetime models of power devices.

Inverse electro-thermal analysis of the material removal mechanism in electrical discharge machining

This paper shows the integrated mathematical and experimental investigation of material removal in electrical discharge machining (EDM), on the basis of electro-thermal approach. In the present model, the amount of heat energy is the equivalent to EDM’s electrical energy, so that the heat source characteristics of the discharge zone are a function of the discharge current and discharge duration. Modeling and optimization of the EDM process were conducted using the inverse heat conduction problem based on the desirable temperature distribution within a workpiece. The developed inverse model is able to determine temperature and heat flux in electrodes for the machining conditions installed during the material removal EDM process. By using the heat flux density, in contrast to previous approaches, the concept of this study enables the optimization relation between the power and duration of the heat source of a single pulse discharge. The crater dimensions at the workpiece are obtained on the basis of temperature isotherms above the melting temperature of the workpiece. The crater size enables good prediction of material removal rate and surface roughness for different EDM parameters. The inverse electro-thermal model’s predictions are compared with the experimental results.

Strategy for enhancing reliability and lifetime of DC-AC inverters used for wind turbines

Lifetime of wind turbine inverters is below expectations therefore, novel design and drive strategies are timely required to achieve optimum life span.In this work, a novel driving strategy to mitigate stresses on inverters is proposed. First, an electro thermal analysis was carried out using finite element modelling methods. Subsequently, the outcomes of the models were validated using DC/AC IGBT based power inverter module interfaced to 1.1 kW electrical outputs of a horizontal wind turbine operated under different wind speeds. Real time data was collected using both dSPACE system and high speed thermal imaging camera. The proposed driving method is based on adjusting the switching frequency according to wind speed. Edge detection scheme was embedded in Simulink to determine temperature fluctuations caused by variations in wind speed profile. Effects of these fluctuations are mitigated by regulating the switching frequency and power losses based on a look up table and interpolation method. The proposed strategy of operation reduces cyclic temperature depended lifetime span (total lifetime consumption) to 1.45 × 10−5 cycles compared to 1.88 × 10−5 when operated under conventional fixed frequency. Wire-bond thermal stress was also reduced from 54.5 MPa, for the fixed switching frequency, to 45.5 MPa. This represents about 21% reduction in total lifetime consumption of inverter's wire-bond which, brings huge benefits to wind energy industry.

DC-electro softening in soda lime silicate glass: An electro-thermal analysis

DC-electric field-induced softening was investigated in soda lime glass. The application of a DC current causes a migration of Na ions towards the cathode resulting in the formation of a sodium depleted layer close to the anode where a localized voltage drop ignites electrical arcs through the glass. This effect is strongly asymmetric with respect to the applied DC polarity and, at the anode, it induces strong photoemission (optical transition of alkali elements) sharp rise in temperature and increased electrical resistance. It appears that electrolytic effects and sodium migration play a fundamental role as triggering mechanisms of DC-electric field-induced softening.