In electric vehicles and hybrid electric vehicles, insulated-gate bipolar transistor (IGBT) power module trends to dissipate higher heat flux due to increased power rating and reduced package size. An inefficient cooling method will result in stringent thermal reliability problems. Therefore, there is a strong need for innovative and efficient cooling technologies in order to tackle these issues. In this article, a localized direct phase-change cooling strategy is applied and integrated with direct bonded copper in IGBT power module. Vapor chamber with light weight, high thermal conductivity, and even temperature uniformity replaces original copper baseplate. Layers of thermal grease and original cooling plate are removed, leading to a further reduction in thermal resistance. In order to evaluate the new module, a thermal model and an experiment were built to analyze temperature distribution in layers, junction temperature, temperature uniformity, and thermal resistance. Results indicate the integrated thermal management system outperforms traditional cooling solutions on the cooling capacity. Improvements on junction temperature, temperature uniformity, and total thermal resistance are 34.6%, 76.6%, and 41.6%, respectively. The results illustrate the potential of phase-change cooling by vapor chamber. It provides a new perspective in the compact and efficient design of power electric modules.

The growing interest in wireless high-data-rate communications at millimeter waves for both terrestrial networks and satellite communications is stimulating novel solutions to overcome the strong atmospheric attenuation. In particular, the development of high-throughput satellite communication systems for Internet distribution is fundamental to complementing the terrestrial networks and to cover regions not connected to terrestrial backbones, such as at sea or remote areas. Ku-band and Ka-band satellite systems are presently available. Recently, the W-band (71-76 GHz and 81-86 GHz) has been allocated for multigigabit transmissions, providing 5-GHz bandwidth for both uplink and downlink. However, it has been estimated that for enabling high-throughput W-band satellite communication systems, transmission power higher than 50 W is needed. In this paper, a 71-76 GHz double-corrugated waveguide (DCW) traveling-wave tube (TWT) is designed as an amplifier for high-data-rate satellite downlink, with about 70-W output power. The dispersion characteristic of the designed DCW is experimentally validated by a cold test. The proposed TWT is also a test vehicle, scaled in frequency, for a future novel 220-GHz DCW TWT for terrestrial wireless networks.

Nuclear fusion energy is perhaps one of the most demanding challenges that the scientific community is facing. Unfortunately, the plasma is affected by microturbulence, which is still not fully understood, but which can degrade plasma confinement. The 0.346-THz backward-wave oscillator (BWO) is the enabling device for a high-k plasma collective scattering diagnostic that will provide unprecedented insight on turbulence thereby contributing to the realization of fully operational fusion reactors. This paper describes the final fabrication phase of the 0.346-THz BWO for the collective scattering diagnostic jointly performed in an international project, involving three leading institutions in vacuum electronics. The advancements in technology will open the route to new families of terahertz vacuum electron devices to enable new terahertz applications and provide industry with new advanced processes.

Reliability is a critical performance metric for power semiconductor switches and power electronic systems. Yet guidance on how to test and quantify that reliability is fragmented in the existing literature, particularly with the rapid adoption of wide-bandgap (WBG) devices and novel packaging technologies. This review brings guidance on what designers, reliability engineers, and researchers need to know about power cycling testing (PCT). We provide three major contents: first, introducing how new materials and packaging shift dominant failure mechanisms; second, comparing the main PCT standards joint electron device engineering council (JEDEC), automotive electronics council (AEC), international electrotechnical commission (IEC), and automotive qualification guideline (AQG) and explaining why the “test-to-fail” standard principle is overtaking legacy “test-to-pass” rules; and third, summarizing the unique challenges and existing solutions of applying PCT methods to WBG and ultra-WBG devices. Notably, to the best of the authors’ knowledge, this is the first in-depth analysis of the newly released IEC 60749-34:2025 and AQG 324:2025, benchmarked against their earlier editions. Moreover, by collecting more than 200 testing samples from the existing literature, we also offer the first generic lifetime model that spans Si, SiC, multiple bond-wire materials, and die-attach technologies. Finally, the limitations and associated open questions are discussed to identify future research opportunities.

A type of 3.3-kV/450-A half-bridge insulated-gate bipolar transistor power module combining the silicon (Si) and silicon carbide (SiC) technologies has been developed and reported in this article, for the miniaturization of the Chinese high-speed railway rolling stock traction inverters. This module is developed by integrating the next-generation industrial standard high-voltage packaging topology and the state-of-the-art 3.3 kV wide bandgap semiconductor chip technology, to reduce the waste power dissipation during operation, which in turn can lead to effective downsizing of key components in the traction inverter design. The module layout characteristics and the SiC Schottky barrier diodes design for substitution of the conventional Si fast recovery diodes will be described in detail. The mechanical, thermal, and electrical performances of the hybrid module are compared comprehensively with the Si-based counterpart. Based on the experimental results, an inverter system level evaluation of both modules is also conducted by electro-thermal simulation. The hybrid module shows advantages in loss reduction leading to great potential of system miniaturization, which is a cost effective solution for massive upgrading of the existing high-speed train traction inverters.

We present in this paper an advanced electromagnetic (EM)-electro-thermal 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 electro-thermal 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 electro-thermal model of the IGBT chip and a comprehensive zero-dimensional (0D) thermal network as well as an EM network extracted from the three-dimensional (3D) module packaging structure for each paralleling chip. The incorporation of the EM as well as thermal networks representing the 3D packaging structure discloses essential information about the current imbalance, power dissipation imbalance and thermal imbalance inside the IGBT module with paralleling chips, which have strong influence on the module reliability. To demonstrate the application of this approach, an unfavorably designed 1700V/450A half-bridge IGBT power module is evaluated in the simulation circuit, with experimentally verified electro-thermal IGBT chip model and thermal as well as EM networks. Results have shown that the EM-electro-thermal 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.