Power Cycling Test Research Articles

Study of the Bias Driven Threshold Voltage Drift of 1.2 kV SiC MOSFETs in Power Cycling and High Temperature Gate Bias Tests

Threshold voltage instability remains a challenging aspect for metal-oxide semiconductor-field-effect-transistors (MOSFETs) made from silicon carbide (SiC). SiC MOSFETs from two manufacturers, with planar and trench gate structure respectively, have been tested under different test procedures, including power cycling and high temperature gate bias tests. The standard power cycling test setup has been modified to enable an in situ threshold voltage read-out procedure with the hysteresis method. The recorded threshold voltage drift has been compared with results from high temperature gate bias tests applying a simple power law fit, with the intention to predict the drift in power cycling tests. For the group with trench MOSFETs comparable results between power cycling and gate stress tests have been achieved.

Power Cycling Performance of 3.3 kV SiC-MOSFETs and the Impact of the Thermo-Mechanical Stress on Humidity Induced Degradation

Recently, silicon carbide (SiC) power modules of the 3.3 kV voltage class became available and are a promising candidate to replace silicon power modules in traction applications. However, the more than three times higher Young’s Modulus compared to silicon leads to a reduced lifetime under thermo-mechanical stress. This could pose a significant obstacle in their implementation, since traction applications are particularly demanding in their mission profiles with respect to load cycling, but also to environmental conditions. Thus, the thermo-mechanical stress is not just limiting the lifetime itself, but might also promote the humidity induced degradation due to delamination or micro-cracks. In this work, multiple power cycling tests at different temperature swings on 3.3 kV SiC MOSFET chips in a power module were performed, to assess their ruggedness under thermo-mechanical stress. Before or afterwards, these modules were tested under standard HV-H3TRB conditions to verify the interaction between thermo-mechanical and humidity stress on the robustness of the modules.

Deception of Heart Rate is Unable to Improve Functional Threshold Power in Cyclists

Introduction: Studies investigating the effects of deception on endurance performance have been somewhat inconclusive. The purpose of this study was to explore the use of biofeedback deception of heart rate (HR) in an attempt to improve athletic performance. Methods: Thirteen individuals (10 men, mean±SD age 29.4±10.2 years) completed two 20-minute functional threshold power (FTP) cycling tests. In the control (CON) condition, their correct HR was displayed, while in the deception (DEC) condition an incorrect HR was displayed (correct HR – 10 bpm). Paired samples t-tests were used to compare cycling variables such as power output, speed and work between conditions. Actual HR was analyzed using 2 (condition) x 10 (time; every two minutes) repeated-measures ANOVAs. Results: Mean power output in the CON condition was 226.7±69.3 W and 222.6±65.4 W in the DEC condition (p>.05). The total amount of work performed was nearly identical between conditions (CON: 709.2± J, DEC: 709.3± J; p>.05). There were no differences in actual HR between conditions (all p>.05). Conclusions: Biofeedback deception of HR was unable to improve performance. Verbal encouragement may be a moderating variable that allows successful deception to occur. Possible future studies are presented that will allow further testing of this hypothesis.

Review on Power Cycling Reliability of SiC Power Device

The rising demand for increased integration and higher power outputs poses a hidden risk to the long-term reliable operation of third-generation semiconductors. Thus, the power cycling test (PCT) is widely regarded as the utmost critical test for assessing the packaging reliability of power devices. In this work, low-thermal-resistance packaging design structures of SiC devices are introduced, encompassing planar packaging with dual heat dissipation, press-pack packaging, three-dimensional (3D) packaging, and hybrid packaging. PCT methods and their control strategies are summarized and discussed. Direct-current PCT is the focus of this review. The failure mechanisms of SiC devices under PCT are pointed out. The electrical and temperature-sensitive parameters adopted to monitor the aging of SiC devices are organized. The existing international standards for PCT are evaluated. Due to the lack of authoritative statements for SiC devices, it is difficult to achieve comparison research results without consistent preconditions. Furthermore, the lifetimes of the various packaging designs of the tested SiC devices under PCTs are statistically analyzed. Additionally, problems related to parameter monitoring and test equipment are also summarized. This review explores the broader landscape by delving into the current challenges and main trends in PCTs for SiC devices.

Construction and validation of the Wingate index model for elite athletes

ObjectiveThe gold standard for measuring anaerobic fitness is the power cycle ergometer test, but this method is expensive and time-consuming, and it has negative effects on pre-competition performance. This study aims to utilize the strong correlation between accessible body composition indices and less accessible anaerobic power bicycle indices to establish and verify a Wingate Index Model. MethodsA cohort of 993 male (age: 22.56 ± 3.30 years) and 450 female (age: 21.47 ± 2.70 years) athletes who participated in diverse sports were enrolled and completed the high-intensity power cycle test and body composition test, and the model formula was established based on these data. Totally, 283 participants were randomly selected to verify the formula using SPSS 22.0 and GraphPad Prism 9.4.1. ResultsThere was no significant difference between the value derived from the confirmed formula and the measured value of the instrument among the elite athletes (p > 0.05). The probabilities that the values obtained by the formula would fall within the 95 % confidence interval were as follows: Mpower(mean power): 94.7 %, Mpower/W(mean power/weight): 96.8 %, total work: 94.7 %, Ppower(peak power): 94.7 %, Ppower/W(peak power/weight): 95.8 %, and fatigue index: 93.6 %. ConclusionBy constructing and validating multiple regression equations for the anaerobic power cycle and body composition indices, this study showed that the probabilities of the values obtained from the equations falling within the 95 % confidence interval were 94.7 % for Mpower, 96.8 % for Mpower/W, 94.7 % for total work, 94.7 % for Ppower, 95.8 % for Ppower/W, and 93.6 % for fatigue index. Therefore, these equations may have some practical value in predicting the elite athlete population.

Optimizing Insulated-Gate Bipolar Transistors’ Lifetime Estimation: A Critical Evaluation of Lifetime Model Adjustments Based on Power Cycling Tests

This paper presents a detailed refinement and validation of two well-known lifetime prediction models for IGBTs, namely CIPS08 and SKiM63, using experimental power cycling test data. This study focuses on adapting these models to reflect the operational conditions and degradation patterns to more accurately fit different IGBT types and applications. Key modifications include recalibrating the scale factor and temperature coefficients in the SKiM63 model and refining the CIPS08 model coefficients (β1 = −2.910, β2 = 1083.714, β3 = −4.521) based on the impact of temperature fluctuations, bond wire diameter, and electrical stresses observed during power cycling tests. These adjustments provide a significant shift from traditional values, with the recalibrated models offering a better fit, as evidenced by a reasonable coefficient of determination (R2) and root mean square error (RMSE). Utilizing Monte Carlo simulations with a 5% uncertainty, the study calculates the B10 lifetimes of PV inverters, demonstrating a substantial reduction from 43 years in the unmodified model to 13 years in the modified model. This emphasizes the critical need for ongoing modification and validation of predictive models based on the actual operational data to enhance the reliability and efficiency of IGBTs in power electronic systems.

Failure Characterization of Discrete SiC MOSFETs under Forward Power Cycling Test

Failure Characterization of Discrete SiC MOSFETs under Forward Power Cycling Test

Assessing thermal resistance as a degradation metric for solder bump arrays in discrete SiC MOSFET packages

The development of innovative power electronics solutions for automotive applications introduces new reliability requirements for electronic assemblies and interconnection technologies. Many of the reliability methods used in power electronics require extensive experimental data, resulting in long product design cycles. This work focuses on developing a simulation-driven approach to assess the solder joint reliability of a discrete silicon carbide MOSFET by monitoring its degradation under power cycling in the thermal and thermo-mechanical domains using the thermal resistance of the stack as a failure metric. Active power cycling tests are performed to determine the loading condition at which end-of-life is reached due to a 20% increase in thermal resistance. Numerical analysis using finite element simulations is conducted to gain a physical understanding of the failure criterion, allowing to monitor solder degradation based on the thermal resistance and to pinpoint failure at individual interconnects within a solder bump array. The proposed methodology aims to accelerate the quality assurance and product qualification processes of discrete power electronic devices.

4H-SiC/SiO2 Interface Degradation in 1.2 kV 4H-SiC MOSFETs due to Power Cycling Tests

Power cycling tests (PCTs) assess the reliability of power devices by closely simulating their operating conditions. A PCT was performed on commercially available 1.2 kV 4H-SiC power metal–oxide–semiconductor field-effect transistors to observe its impact on the 4H-SiC/SiO2 interface. High-resolution transmission electron microscopy and electron energy loss spectroscopy measurements showed variations in the length of the 4H-SiC/SiO2 transition layer, depending on whether the device was power cycled. Moreover, the total resistance at Vg >> Vt in Rtot − (Vg-Vt)−1 graph increased to 16.5%, while it changed more radically to 47.3% at Vg ≈ Vt. The threshold voltage shifted negatively. These variations cannot be expected solely through the wearout of the package.

Gate-Oxide Degradation Monitoring of SiC MOSFETs Based on Transfer Characteristic With Temperature Compensation

Gate-oxide degradation is a concern in SiC MOSFETs especially in safety critical applications such as aerospace and electric vehicles (EV). To address this concern, this paper presents an accurate gate-oxide degradation monitoring solution based on the SiC devices’ transfer characteristics. Specifically, a plug-in circuit for gate driver is proposed to extract the transconductance ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g_m</i> ) and threshold voltage ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V_th</i> ) values from transfer characteristic. By using the threshold voltage as gate-oxide aging reference and transconductance as the junction temperature reference, the two precursors are combined to obtain a temperature and package degradation independent estimate of the gate-oxide health. High-temperature gate bias (HTGB) and DC power cycling tests are used to confirm <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g_m</i> ’s sensitivity to gate-oxide degradation and insensitivity to package degradation in kelvin-sourced discrete SiC MOSFETs. A simple circuit is proposed for on-board <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g_m</i> measurement using the voltage drop on the common source inductance of the MOSFET. The measured <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g_m</i> is converted into digital pulse width, which can be easily measured using a microcontroller. A comprehensive comparison is presented to demonstrate the merits of the proposed method. Lastly, the accuracy and sensitivity of temperature and aging measurements using the proposed method is validated experimentally.

Thermal Performance and Reliability of Liquid Metal Pastes with Solid Metal Particles as Thermal Interface Materials for the Cooling of Computing Electronics

In recent years, we have developed a series of gallium-based liquid metal pastes containing low content solid metal particle additives (LMPMPs) to enhance thermal performance and control bondline thickness (BLT) of prepared liquid metal composites as thermal interface materials (TIMs). This new material is synthesized via in-situ by introducing gallium oxide into liquid metal alloys. In our recent research, we intensively investigated thermal properties of different primary liquid metal alloys containing small amounts of metal additives, and ran extensive reliability tests including power cycling, thermal cycling, and aging tests on the synthesized LMPMPs. In this paper, the thermal properties of the synthesized LMPMPs with different liquid metal alloys are studied with reliability tests that focus on power cycling by monitoring thermal resistance of LMPMPs over time using a custom power cycler. We have found power density, BLT, and different liquid metal alloys have a significant impact on thermal properties and reliability of LMPMPs. We also conducted thermal aging tests on Cu-LMPMPs-Cu sandwich specimens at 85°C in an ambient atmosphere to study the deterioration of thermal conductivity of LMPMPs over time, measured by laser flash analyzer using the layered structure method. Highly accelerated stress test (HAST) with a profile of 110°C, 85RH%, and 264 hours was used to study the decomposition of liquid metal alloys. Thermal cycling test with a profile of -40 to 125°C was employed to investigate the pump-out of LMPMPs. It has been proven that LMPMPs have much better thermal performances than polymer-based thermal grease.

Power Cycling Reliability with Temperature Deviation of Pressureless Silver Sintered Joint for Silicon Carbide Power Module

SiC devices can enhance power conversion in electric vehicles. However, traditional soldering techniques are limited by their low melting temperatures. Therefore, we used pressureless Ag sintering to assemble a 1200 V/200 A SiC metal-oxide-semiconductor field-effect transistor power module and compared the long-term reliability, electrical properties, and driving performance of the module with those of a similar module assembled using the solder Sn-3.0Ag-0.5Cu (SAC305). To assess sinter joint reliability, we performed power cycling tests over two temperature ranges, 50–150°C and 50–175°C, for 15,000 cycles. Subsequently, we compared the breakdown voltage (BVDSS) and drain-source on-resistance (RDS(ON)) of the SiC power modules and performed cross-sectional analyses of the device bonding interfaces. No difference in BVDSS was found between the Ag-sintered and SAC305-soldered joints. However, the RDS(ON) exhibited minimal variation for the Ag-sintered module but significantly varied for the SAC305-soldered module, suggesting that the former better maintained its characteristics. Furthermore, the electrical characteristics of the SAC305-soldered module underwent more significant alterations with increasing temperature change during power cycling, indicating that cracks propagated throughout the SAC305 soldered joint over time. Therefore, Ag sintering was quantitatively validated as the superior die attachment technology compared to soldering for long-term reliability.

Demonstration of a small‐scale power generator using supercritical CO2

AbstractThe supercritical CO2 (sCO2) power cycle could improve efficiencies for a wide range of thermal power plants. The sCO2 turbine generator plays an important role in the sCO2 power cycle by directly converting thermal energy into mechanical work and electric power. The operation of the generator encounters challenges, including high temperature, high pressure, high rotational speed, and other engineering problems, such as leakage. Experimental studies of sCO2 turbines are insufficient because of the significant difficulties in turbine manufacturing and system construction. Unlike most experimental investigations that primarily focus on 100 kW‐ or MW‐scale power generation systems, we consider, for the first time, a small‐scale power generator using sCO2. A partial admission axial turbine was designed and manufactured with a rated rotational speed of 40,000 rpm, and a CO2 transcritical power cycle test loop was constructed to validate the performance of our manufactured generator. A resistant gas was proposed in the constructed turbine expander to solve the leakage issue. Both dynamic and steady performances were investigated. The results indicated that a peak electric power of 11.55 kW was achieved at 29,369 rpm. The maximum total efficiency of the turbo‐generator was 58.98%, which was affected by both the turbine rotational speed and pressure ratio, according to the proposed performance map.

Evaluation of Electrical Model Parameter Changes in SiC Power MOSFETs During Power Cycling Test

Evaluation of Electrical Model Parameter Changes in SiC Power MOSFETs During Power Cycling Test

Investigation on Saturation Voltage Increment of Multichip Press-Pack IGBTs Under Power Cycling Tests

Investigation on Saturation Voltage Increment of Multichip Press-Pack IGBTs Under Power Cycling Tests

Predicting Lifetime of Semiconductor Power Devices Under Power Cycling Stress Using Artificial Neural Network

This paper analyzes the problem of modeling the lifetime in semiconductor power devices subjected to power cycling stress using Artificial Neural Networks (ANNs). The paper discusses the optimal configuration of ANNs for the considered problem, aiming at minimizing the error in the predicted lifetime and at reducing the required number of training data. Moreover, being the device lifetime a stochastic parameter, the suitability of ANNs is verified in the case of variability in the input training data. Power cycling tests are conducted on IGBT devices and experimental number of cycles to failure are adopted for the training process of the ANN.

Failure Mode Classification of IGBT Modules Under Power Cycling Tests Based on Data-Driven Machine Learning Framework

Failure Mode Classification of IGBT Modules Under Power Cycling Tests Based on Data-Driven Machine Learning Framework

Time-Varying Cumulative Damage Recursive Method for Power Semiconductor Devices

Accurate simulation of power semiconductor devices failure process is one of the most important means to clarify the failure mechanism and evaluate the device reliability, which is induced by the associated internal temperature gradient acting on the mismatch of coefficients of thermal expansion between adjacent layers and internal temperature gradients. This paper investigates the microstructure change of the new and replaced modules using the CT scanner, which represents that the void distribution of the die-attach solder layer is an important factor to indicate the reliability status of the power semiconductor devices. A multiple physical field model combining time-varying cumulative damage recursive method is proposed to simulate the damage accumulation and the physical failure process based on mesh automatic updated method and material failure formula. The number of cycles to failure, thermal resistance, and junction temperature extracted from power cycling test results are used to validate the accuracy of the parameter variation. The physical outline of the voids is extracted to prove the consistency of the microstructure change. This method is intended for operational management and also provided the foundation for the design and development of power electronic devices with high power and high reliability.

A remaining useful life prediction method of SiC MOSFET considering failure threshold uncertainty

AbstractDifferent methods have been developed to predict power devices' remaining useful life (RUL). The existing methods need to specify the failure thresholds corresponding to failure precursors of power devices based on historical data. However, there might be heterogeneity in failure threshold between different devices despite being from the same batch, which can severely affect the RUL prediction performance. Aiming at this problem, this article proposes an RUL prediction method based on the non‐linear Wiener process considering the failure threshold uncertainty. To incorporate the failure threshold uncertainty into the RUL prediction, the truncated normal distribution is employed to characterize this uncertainty. The maximum‐likelihood estimation method is used to estimate the model parameters based on the historical degradation data. Then, the parameters can be dynamically updated by the Bayesian paradigm each time a new piece of condition monitoring (CM) data of the interested device in service is observed. This makes the predicted RUL dependent on the real‐time health conditions of the interested device in service. The effectiveness of the proposed method is validated with the power cycling testing results of SiC MOSFETs. Experimental results reveal that the proposed method can reduce the prediction error by 10.273%.

Influence of thermal interface material using discrete Si-IGBTs and consideration of power cycling conditions

In this work, the influence of different thermal interface materials (TIMs) on junction temperature and power cycling capability of discrete Si IGBT in TO-247 package is investigated. A difference in the total thermal resistance (junction - heat sink) up to a factor of ten when using different heat conductive foils or paste is to be expected. A temperature deviation between the maximum junction temperature of up to 50 K is possible under the same conditions (i.e. equal, load current, Tvjmin, ton, VGE) during the power cycling test. If the current is increased to achieve the same Tvjmax, the power cycling capability is reduced. This influence and also the electrical insulating capacity of the different TIMs should be taken into account in the application. The cause of failure is bond wire degradation due to increase in forward voltage without solder deterioration in all power cycling tests.