When a traffic crash occurs, following vehicles need to change lanes to bypass the obstruction. We define these maneuvers as post-crash lane changes (LCs). In such scenarios, vehicles in the target lane may refuse to yield even after the lane change has already begun, increasing the complexity and crash risk of post-crash LCs. However, the behavioral characteristics and motion patterns of post-crash LCs remain unknown. To address this gap, we construct a post-crash LC dataset by extracting vehicle trajectories from drone videos captured after crashes. Our empirical analysis reveals that, compared to mandatory LCs (MLCs) and discretionary LCs (DLCs), post-crash LCs exhibit longer durations, lower insertion speeds, and higher crash risks. Notably, 79.4% of post-crash LCs involve at least one instance of non-yielding behavior from the new follower, compared to 21.7% for DLCs and 28.6% for MLCs. Building on these findings, we develop a novel trajectory prediction framework for post-crash LCs. At its core is a graph-based attention module that explicitly models yielding behavior as an auxiliary interaction-aware task. This module is designed to guide both a conditional variational autoencoder and a Transformer-based decoder to predict the lane changer's trajectory. By incorporating the interaction-aware module, our model outperforms existing baselines in trajectory prediction performance by more than 10% in both average displacement error and final displacement error across different prediction horizons. Moreover, our model provides more reliable crash risk analysis by reducing false crash rates and improving conflict prediction accuracy. Finally, we validate the model's transferability using additional post-crash LC datasets collected from different sites.

The rising demand for high-power semiconductor devices in sectors such as electric vehicles (EVs), renewable energy conversion, and data centers highlights the need for efficient and reliable thermal management technologies. In this work, we present a simulation-based study of a 1200 V SiC MOSFET wafer-level power package that integrates chip-package co-design, room-temperature wafer bonding, and embedded microfluidic cooling. By utilizing a room-temperature bonding process to mitigate fabrication-induced warpage and optimizing the chip geometry to balance thermal spreading with mechanical stress, this proposed architecture ensures structural integrity while maximizing heat transfer efficiency. Thermal-fluid-mechanical multiphysics modeling results revealed that the proposed wafer-level microfluidic package achieved a 35.14% reduction in total thermal resistance compared with conventional SiC MOSFET power modules. The design demonstrates improvements in junction temperature uniformity and overall heat dissipation efficiency, which is promising for next-generation high-power density applications.

Flexible strain sensors are key components in emerging fields such as soft robotics and wearable electronics, where robust interfacial adhesion, low electrical resistance, and mechanical stability under repeated deformation are essential. Conventional metal films on polymer substrates often exhibit poor reliability due to thermal expansion mismatch and weak interfacial bonding. Therefore, silver sintering has emerged as a promising low-temperature interconnect material with high conductivity and flexibility, yet controlling porosity during sintering and ensuring strong adhesion to polymers remain critical challenges. This work presents a strategy to expand sintered silver for flexible strain sensor applications. On the one hand, the silver (Ag) porosity was controlled from 20% to 40% through a pressureless sintering process; On the other hand, the Ag-polymer interface was reinforced via a nanoscale surface modulation method using a two-step etching treatments, while the 40 min etched sample demonstrated the most uniform performance, with the lowest electrical conductivity average degradation of 2.97%. The proposed approach effectively improves the microstructural integrity and interfacial reliability, paving the way for high-performance, durable, flexible sensors suitable for the next-generation soft electronic systems.

The mechanical reliability of sintered silver joints, widely used in power electronics packaging, is critical for long-term applications such as electric vehicle converters. However, conventional homogeneous modeling often oversimplifies internal microstructural variations and limits the accuracy of stress prediction, especially under thermal cycling. In this study, a region-refined modeling framework is proposed to account for epoxy-regulated porosity and mechanical inhomogeneity across the joint. Pressureless die-attach joints were prepared using submicron silver pastes with varying epoxy contents (0∼4 wt%). The joint was divided into five sub-regions from the center to the fillet for localized characterization. Nanoindentation, SEM, and EDS analyses were conducted to assess region-specific mechanical properties and microstructure. Power-law constitutive models were extracted for each region and implemented into finite element simulations of thermal cycling (−55 ∼ 150 °C, 2 cycles/h, 250 h). The sub-region FEM model more accurately captured local stress concentrations and identified failure-prone areas, particularly near the fillet, compared to conventional homogeneous models. Experimental validation confirmed a good correlation between simulated stress zones and observed degradation. This sub-region strategy provides a robust framework for reliability prediction and design optimization of sintered silver joints in high-performance, large-area packaging applications.

Fluxless tin soldering eliminates flux residues but introduces tin fog, which affects the reliability of electronic packaging. The influence of tin fog was first analyzed through the shear strength of the Al wires bonded on DBC substrates. After aging at 300 °C for 4 h, shear strength increased by 4.5 % on pure copper surfaces but decreased by 22.6 % on tin fog-covered surfaces. Further SEM revealed tin fog created interfacial porosity, reducing strength. Secondly, the impact of tin fog formation during the formic acid reflow process was studied under different formic acid concentrations and different vacuum frequencies during the reflow's preheating stage. Through SEM, EDS, Micro-IR, and XPS tests, the principal components of tin fog were identified as elemental tin, tin dioxide, and organic compounds such as amides and esters. It is found that tin fog forms through a process wherein tin formate produced during formic acid reflow adheres to the substrate surface, which is already adsorbed with organic substances such as esters and amides, and subsequently decomposes at high temperatures to generate derivative products creating the fog. Therefore, to mitigate tin fog formation, tin fog was effectively controlled under a tripled vacuum frequency, resulting in reduced organic residues on substrates. Under such a mitigation strategy, further reliability tests showed that the shear strength of Al wire bonding after aging at 300 °C was comparable to that on clean DBC substrates. This research provides a valuable reference for enhancing the reliability of fluxless soldering in electronic packaging.

Pressureless sintered silver pastes composed of submicron particles represent a promising, cost-effective interconnect solution for power electronics. While epoxy additives are often introduced to modify solvent behavior and enhance mechanical integrity, they can simultaneously degrade electrical and thermal performance, leading to critical trade-offs. In this work, five custom-formulated pastes with varying epoxy contents (0–4 wt%) and two commercial benchmarks were systematically evaluated in terms of shear strength, resistivity, thermal conductivity, and coefficient of thermal expansion (CTE). To optimize across multiple criteria, the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) was employed. The paste containing 2 wt% epoxy achieved the highest composite score, offering a favorable combination of mechanical, thermal, and electrical properties. Long-term reliability was further validated through high-temperature storage and thermal cycling tests. These results highlight that epoxy modulation, when integrated with an optimization framework, offers a viable strategy for tailoring high-performance, reliable sintered silver joints for next-generation power electronic packaging.

This work investigated the impact of die-attach fillet geometry on the reliability of epoxy-based pressure-less sintered silver joints. Three types of sintered silver samples (Ag-0, Ag-1, and Ag-2) with 0%, 1%, and 2% epoxy content were prepared and characterized. Nanoindentation tests combined with inverse calculations were used to determine their elasto-plastic behavior. Fillet formation was influenced by organic solvent composition, dispense volume, and placement pressure, resulting in three geometries: rounded, triangular, and rounded rectangular. Finite element analysis was employed to simulate stress distribution and equivalent thermal strain under thermal cycling conditions (−55°C to 150°C). The simulation results were validated experimentally through shear strength testing and microstructural characterization using scanning electron microscopy (SEM). The findings highlight the significant role of fillet geometry, climbing height, and die-attach thickness in stress distribution and failure mechanisms, providing valuable insights into optimizing the die-attach process to enhance joint reliability in power electronics applications.

While silver-based sintered materials are limited by cost and electromigration, and copper faces challenges with oxidation at high temperatures, Cu-based composite sintering materials offer promising alternative solutions. This review examines recent advances in Cu-based composite sintered materials for die-attach in power electronics packaging, focusing on their mechanical, thermal, electrical properties, and reliability. This review systematically categorizes such compounding strategies, including direct mixing, core-shell structures, and alloying, analyzing the impact on composite properties. Furthermore, the reliability of Cu-based composite sintered joints is evaluated, addressing high-temperature storage, thermal cycling, corrosion, and electrochemical migration. Challenges such as oxidation resistance, process optimization, and cost-effectiveness are discussed, together with future research directions. This work aims to support researchers in advancing Cu-based composite sintering materials research and development, broadening material options for high-temperature power electronics packaging applications.

Sintered materials have been widely applied, as an alternative to soldering, for power electronics packaging. One key issue for such die-attach material is to characterize the actual porosity, which is difficult to obtain through SEM cross-section analysis. Therefore, in this work, the optimized Quartet Structure Generation Set (QSGS) algorithm was applied to sintered copper joints under various porosity levels to reconstruct 3D porous structures based on 2D SEM images. Firstly, copper joints with varying porosities were fabricated under different sintering conditions. Reconstructed 3D porous copper models were then generated through the QSGS algorithm to match experimental observations, including porosity and pore size. Finite element analysis (FEA) simulations were further conducted to explore the effects of pores on thermal and electrical performance. This work provides a method for accurately predicting the thermoelectric properties of sintered copper joints and insights for optimizing copper sintering in power electronics applications.

With the increased deployment of power modules in demanding conditions, sintering materials, especially composite sintering materials, have raised growing interest due to their cost-effectiveness and suitability. Therefore, this study explores the viability of Cu–Ag composite sintering material, focusing on solvent influence through microstructure and mechanical behavior analysis. Micron-sized particle-based Cu–Ag composite pastes were designed and compared using eight solvents (four epoxy-free and four epoxy-added) based on fluidity and thermal stability. The sintered joints' performance, assessed through shear strength analysis, showed comparable values to pure silver sintering for both epoxy-free and epoxy-added samples. Optimized samples from each solvent system underwent reliability analysis, demonstrating that Cu–Ag joints with epoxy resin exhibited significantly higher shear strength after high-temperature storage and thermal cycling tests. Micromorphology and elemental composition analysis revealed differences in aging mechanisms, primarily attributed to variations in porosity due to oxide formation and pore filling by epoxy resin under different solvent systems. Further nanoindentation characterization of micromechanical properties, including hardness, modulus, and creep properties, during high-temperature aging, established constitutive models for insights into reliability evolution. In conclusion, the optimized epoxy-added Cu–Ag sintered joints proposed in this study demonstrated exceptional reliability and acceptable micromechanical properties, presenting a promising option for high-temperature power packaging.

A lane-changing (LC) maneuver may cause the follower in the target lane (new follower) to decelerate and give up space, potentially affecting crash risk and traffic flow efficiency. In congested flow, a more aggressive LC maneuver occurs where the lane changer is partially next to the new follower and creates negative gaps, namely negative gap forced LC (NGFLC). Although NGFLC forms the foundation of sideswipe crashes, little has been done to address its impacts and the contributing factors. To tackle this issue, a total of 15,810 LC trajectory samples are extracted from three drone videos at different locations. These samples are categorized into NGFLC and normal LC groups for comparative analysis. Five commonly used conflict indicators are extended into two-dimensional to evaluate the crash risk of LC maneuver. The change of time gaps during LC maneuver are examined to quantify the impact of LC on traffic flow efficiency. We find that NGFLCs significantly increase crash risk, reflected by the number of hazardous LC events and potential crash areas compared to normal LC. Additionally, results reveal that both the lane changer and the new follower tend to maintain a larger time gap after NGFLCs. Factors including time headway, relative speed, and historical gaps in the target lane significantly affect NGFLC incidence. Once the movement of the leader in the original lane is taken into account, the prediction accuracy improves from 81% to 91%. The transferability tests indicate that the findings about the negative impact of NGFLC and the accuracy of its prediction model are consistent across different locations. These findings hold implications for driving assistance systems to better predict and mitigate NGFLCs.

Copper sintering has gained great attention as a die-attach technology for power electronics because of its potential cost effectiveness and high reliability under harsh working conditions. However, the mechanism of how the intrinsic pores within such sintered joints influence the thermal and electrical properties still needs further investigation. The evolution of pores within such sintered joints is difficult for in-situ observation during the sintering process and reliability tests, while the porosity level greatly affects the thermal and electrical properties. In this work, four two-dimensional (2D) models with various random pore structures were established based on the Quartet Structure Generation Set (QSGS) algorithm. Then, finite element method (FEM) simulations were conducted to simulate the heat and current conduction in the sintered materials. Subsequently, the distribution of temperature as well as the electric potential in the porous sintered materials were further discussed. Lastly, both the thermal and the electrical conductivities were calculated, followed by a concluded parabolic relationship of thermal and electrical conductivities with the porosity. These findings offer insights into optimizing and predicting copper sintered joint performance and accelerate the wide application of copper sintering.

With the popularization of wide band-gap power modules in offshore wind power systems and water surface photovoltaic power stations, packaging materials face challenges of corrosion by salt, blended with high humidity. Copper-silver (Cu-Ag) composite sintered paste was proposed by researchers as a novel die-attach material for a lower cost and anti-electro migration ability. However, the potential difference between copper and silver forms galvanic corrosion in a high-humidity environment, resulting in accelerated failure combined with salt mist. To further promote the application of composite sintered materials, a copper-silver double-sphere galvanic corrosion model based on finite element simulation was proposed in this paper. The relationship between corrosion rate and time of different Cu-Ag particle size combinations under different sintering degrees was predicted by initial exchange current density. Through the electrochemical characterization of the sintered samples, the optimal combination of materials was further discussed. The accuracy of the model was also verified. The conclusions obtained from both the experiments and simulation work provide guidance for future anti-corrosion analysis, as well as the reliability improvement of novel composite sintered materials.

Aquatic community dynamics are closely dominated by flow regime and water quality conditions, which are increasingly threatened by dam regulation, water diversion, and nutrition pollution. However, further understanding of the ecological impacts of flow regime and water quality conditions on aquatic multi-population dynamics has rarely been integrated into existing ecological models. To address this issue, a new niche-based metacommunity dynamics model (MDM) is proposed. The MDM aims to simulate the coevolution processes of multiple populations under changing abiotic environments, pioneeringly applied to the mid-lower Han River, China. The quantile regression method was used for the first time to derive ecological niches and competition coefficients of the MDM, which are demonstrated to be reasonable by comparing them with the empirical evidence. Simulation results show that the Nash efficiency coefficients for fish, zooplankton, zoobenthos, and macrophytes are more than 0.64, while the Pearson correlation coefficients for them are no less than 0.71. Overall, the MDM performs effectively in simulating metacommunity dynamics. For all river stations, the average contributions of biological interaction, flow regime effects, and water quality effects to multi-population dynamics are 64%, 21%, and 15%, respectively, suggesting that the population dynamics are dominated by biological interaction. For upstream stations, the fish population is 8%–22% more responsive to flow regime alteration than other populations, while other populations are 9%–26% more responsive to changes in water quality conditions than fish. For downstream stations, flow regime effects on each population account for less than 1% due to more stable hydrological conditions. The innovative contribution of this study lies in proposing a multi-population model to quantify the effects of flow regime and water quality on aquatic community dynamics by incorporating multiple indicators of water quantity, water quality, and biomass. This work has potential for the ecological restoration of rivers at the ecosystem level. This study also highlights the importance of considering threshold and tipping point issues when analyzing the “water quantity-water quality-aquatic ecology” nexus in future works.

Lane-changing (LC) in congested traffic has been identified as a trigger for the sudden deceleration behavior of the new follower in the target lane, leading to severe traffic disturbances. Thus, investigating the response of the new follower to an LC maneuver is an important research topic in the literature. To date, numerous efforts have been devoted to understanding the impact of the lane changer on the new follower after the insertion, while less attention has been given to this influence during the pre-insertion stage (anticipation). Therefore, this paper aims to establish a new car-following (CF) model to capture the new follower's driving behavior during anticipation. Specifically, we introduce an attention mechanism deviating from Newell's CF rules to quantify the impact of anticipation. Then, we apply a neural network with an attention layer to estimate the attention mechanism and incorporate it into the Newell CF model, which yields a new CF model, denoted as CF_Attention. Using real-world trajectory data, we design three experiments and select three representative CF models to validate the CF_Attention. The results indicate that the CF_Attention outperforms the other models in predicting the new follower's trajectory, which is not affected by the heterogeneous behavior of the new follower and the anticipation duration. Additionally, the CF_Attention is proven effective in capturing the speed-space relationship and the formation of oscillation. Finally, our transferability test suggests that the CF_Attention is promising for different locations and times without requiring retraining. The results of this study could advance the integration of the LC impact and CF behavior, and could be implemented into commercial traffic simulation programs to describe vehicle movements in traffic flow more accurately.

Recent years, the sintered silver paste was introduced and further developed for power electronics packaging due to low processing temperature and high working temperature. The pressure-less sintering technology reduces the stress damage caused by the pressure to the chip, improves reliability, and is widely applied in manufacturing. Currently, most existed studies are focused on alcohol-based sintered silver pastes while resins have been demonstrated to improve the bonding properties of solder joints. Hence, the performance and sintering mechanisms with epoxy-based silver paste need to be further explored. In this work, a methodology for multifactor investigation is settled on the epoxy-based silver paste to reveal the relationship between the strength and the different influence factors. We first analyzed the characteristics of commercialized epoxy-based silver paste samples, including silver content, silver particle size, organic composition, sample viscosity, and thermal conductivity. Samples were then prepared for shear tests and microstructure analysis under different pressure-less sintering temperatures, holding time, substrate surface, and chip size. Full factor analysis results were further discussed in detail for correlation. The influence factors were ranked from strong to weak as follows: sintering temperature, substrate surface, chip size, and holding time. Finally, a thermal cycling test was carried out for reliability analysis. Epoxy residues are one of the possible reasons, which result in shear strength decreasing exponentially.

The development of silicon-based high-power devices, e.g. IGBTs, has reached its application limits in terms of high-temperature and high-frequency harsh operating conditions. Wide bandgap (WBG) power devices (such as silicon carbide, SiC) are currently one of the most promising power devices for replacement. Due to their intrinsic bandgap, SiC high-power devices have proven their superior performance in high-frequency and high-temperature working scenarios. With the increasing demand of high-power semiconductor devices in industries such as new-energy vehicles, high-speed railway systems, and aerospace, the conditions of SiC power semiconductor devices have become more and more complex, which brings challenges to electronic packaging technology. Due to thermal management and reliability requirements for SiC power devices, customized advanced heat dissipation structures, and high-temperature soldering materials have been introduced in power device packaging technology. The reliability verification of these new electronic packaging technologies is often time-consuming and labor-intensive, so designers hope to obtain results consistent with actual experimental data through the utilization of computer-aided design methods, such as finite-element analysis (FEA), which will greatly reduce the number of iterations of physical prototypes and the development time. This article reviewed and discussed the application of FEA in the latest packaging technology, including the extraction of the thermal resistance network of the SiC power module, the thermal simulation of the novel efficient cooling structure, the thermo-mechanical analysis of the high-temperature packaging material, and the long-term reliability FEA of the SiC power devices.