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[ASME ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - San Francisco, California, USA (Monday 27 August 2018)] ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - Next Gen Test-Vehicle to Simulate Thermal Load for IoT FPGA Applications
摘要： As semiconductor device feature size scales and circuit performance increases, power dissipation and thermal management are becoming very important. Attention to thermal considerations is required throughout the chip development cycle from preliminary architecture planning to deployment on customer board and beyond. This paper describes a versatile thermal test vehicle that can be used to address these requirements. We discuss the architecture and implementation of a specially designed test-vehicle chip, followed by its operation. The programmability and flexibility of this vehicle will be highlighted. In addition, we cover other usage of this vehicle which includes modelling of chip-level thermal behavior with different floorplan, simulating thermal loads in IoT FPGA applications, cross-calibrating thermal numerical simulators with measured silicon data and evaluating the thermal impact of different package form-factor / material (such as thermal interface material) and cooling solutions. The abovementioned chip was fabricated using 0.18um technology and assembled in a flip-chip package. The reminder of this evaluation system is a simple, inexpensive tester from which a software is run to program the chip and to measure the spatial & temporal temperature values. Measured thermal data from different use cases are presented in this paper.
关键词： on-chip temperature measurement,thermal management,package development,package-level thermal evaluation,on-die heating,IoT servers,on-die temperature sensing,characterization methodology,thermal evaluation tool
更新于2025-09-23 15:23:52
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[IEEE 2018 24rd International Workshop on Thermal Investigations of ICs and Systems (THERMINIC) - Stockholm, Sweden (2018.9.26-2018.9.28)] 2018 24rd International Workshop on Thermal Investigations of ICs and Systems (THERMINIC) - Structural analysis and modelling of packaged light emitting devices by thermal transient measurements at multiple boundaries
摘要： The paper presents a comprehensive methodology for modeling the electrical, optical, and thermal domains of high-power LEDs, focusing on the XPE2 type from Cree. It introduces optimization algorithms (OPT1 and OPT2) to extract parameters such as series resistance (RS), ideality factor (m), and saturation current (I0) from forward voltage (VF) measurements. A quadratic model for radiant voltage (Vrad) is developed to describe the optical output, and thermal modeling is addressed through structure functions derived from transient thermal measurements. The approach enables accurate prediction of LED performance across varying currents and temperatures, with applications in thermal management and design optimization.
关键词： ideality factor,thermal management,structure function,LED modeling,radiant flux,forward voltage,saturation current,series resistance
更新于2025-09-23 15:23:52
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Thermal Analysis of AlGaN/GaN High-Electron-Mobility Transistors with Graphene
摘要： A thermal analysis of AlGaN/GaN high electron mobility transistors (HEMTs) with Graphene is investigated using Silvaco and Finite Element Method. Two thermal management solutions are adopted; first of all, graphene is used as dissipation material between SiC substrate and GaN buffer layer to reduce thermal boundary resistance of the device. At the same time, graphene is also used as a thermal spread material on the top of the source contacts to reduce thermal resistance of the device. The thermal analysis results show that the temperature rise of device adopting graphene decreases by 46.5% in transistors operating at 13.86 W/mm. Meanwhile, the thermal resistance of GaN HEMTs with graphene is 6.8 K/W, which is much lower than the device without graphene, which is 18.5 K/W. The thermal management solutions are useful for integration of large-scale graphene into practical devices for effective heat spreading in AlGaN/GaN HEMT.
关键词： AlGaN/GaN,Thermal Management,High-Electron-Mobility Transistors (HEMTs),Graphene
更新于2025-09-23 15:23:52
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Online Junction Temperature Extraction of SiC Power MOSFETs with Temperature Sensitive Optic Parameter (TSOP) Approach
摘要： Accurate information of the junction temperature of SiC power MOSFETs ensures safe operation and helps reliability assessment of the devices. In this paper, an online junction temperature extraction method is proposed based on the electroluminescence phenomenon of the body diode of SiC power MOSFETs. It is found that during the forward conduction interval of the body diode, visible blue light is emitted around the chip, which ascribes to the radiative recombination in the low doped region of SiC MOSFETs. Experimental results suggest the light intensity changes linearly with the variation of the temperature and behaves as a temperature sensitive optic parameter (TSOP). Further, an electro-thermal-optic model is proposed to reveal the relationship between electroluminescence intensity, forward current and junction temperature. Based on the TSOP, an online junction temperature extraction method is proposed for SiC MOSFETs and verified in a SiC MOSFET based inverter. Compared with state-of-the-art methods, the proposed junction temperature measurement method is contactless and immune from the aging of the package.
关键词： junction temperature extraction,Body diode,thermal management,electroluminescence,SiC MOSFETs
更新于2025-09-23 15:22:29
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[ASME ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - San Francisco, California, USA (Monday 27 August 2018)] ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - Analysis of Thermal Properties of Power Multifinger HEMT Devices
摘要： In this paper, several methods suitable for real time on-chip temperature measurements of power AlGaN/GaN based high-electron mobility transistor (HEMT) grown on SiC substrate are presented. The measurement of temperature distribution on HEMT surface using Raman spectroscopy is presented. We have deployed a temperature measurement approach utilizing electrical I-V characteristics of the neighboring Schottky diode under different dissipated power of the transistor heat source. These methods are verified by measurements with micro thermistors. The results show that these methods have a potential for HEMT analysis in thermal management. The features and limitations of the proposed methods are discussed. The thermal parameters of materials used in the device are extracted from temperature distribution in the structure with the support of 3-D device thermal simulation. The thermal analysis of the multifinger power HEMT is performed. The effects of the structure design and fabrication processes from semiconductor layers, metallization, and packaging up to cooling solutions are investigated. The analysis of thermal behavior can help during design and optimization of power HEMT.
关键词： thermal properties,Raman spectroscopy,thermal management,Schottky diode,power HEMT devices
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Controlling thermal failure of silicon field emitters in a commercial X-ray source
摘要： The need for a low-cost, low-dose 3D imaging capability, as an alternative to CT and MRI scanners, has driven the development of a multi-cathode, stationary Digital Tomosynthesis (s-DT) scanner. Demonstration experiments with an array of cold cathodes as electron sources have been reported by multiple groups. We report the operation of a protoype with a different field emitter composition and geometry, at 60kV, to obtain images of a dental phantom, and the subsequent reconstruction of the raw images to obtain 3D slices. Thermal heating of the emitters was found to be the primary factor limiting performance of the device, and several well-established control mechanisms were employed to mitigate this. These include using a ballast resistance, metal coatings, conditioning, and optimizing the duty cycle at operating voltage. We report on the consequent improvement in device flux, lifetime and yield, and present the future outlook of our device.
关键词： thermal management,digital tomosynthesis,X-ray,field emitters
更新于2025-09-23 15:21:21
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Performance analysis of a heat pump-based photovoltaic/thermal (PV/T) system
摘要： Photovoltaic/thermal (PV/T) system produces both heat and electricity simultaneously with the advantages of better space utilization and higher conversion efficiency over individual solar thermal and solar photovoltaic (PV) system when operated separately. The PV/T system can control the operating temperature of PV by passing a heat transfer fluid through a heat exchanger attached to the rear of the modules. The present study analyses the performance of one such in-house built system, where the heat transfer fluid is refrigerant. Refrigerant-based PV/T system involves the integration of evaporator coils of the heat pump and PV module to form a cogeneration type system known as photovoltaic/thermal–solar assisted heat pump (PV/T–SAHP). The prototype of the PV/T–SAHP was fabricated with a double glass PV module instead of a conventional module with polyvinyl fluoride backsheet. Initially, the performance characteristics of the system are analyzed in detail using the experimental observations under a typical clear sky condition during the transition season. Following, the year-round performance of the system is predicted using an already validated numerical model. It was found that the present system can improve the average electrical efficiency by 15.20% and can achieve a coefficient of performance of 2.96.
关键词： Refrigerant-based PV/T system,Thermal management of PV module,Double glass PV module,Heat pump
更新于2025-09-23 15:21:01
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An optimized phosphor model coupled with thermal and optical behavior and a thereof ring-shaped phosphor convertor for improving thermal uniformity in laser illuminations
摘要： Due to the high energy density of laser diode (LD), the ?uorescent convertor always su?ers from serious overheating problems, such as thermal quenching, signi?cant e?ciency drop or even material carbonization failure. In this work, we improved the current optical-thermal model by coupling the optical behavior of red (nitride)/yellow (YAG) phosphor and thermal conductivity of di?erent hybrid particles concentrations. According to the theoretical analysis, the thermal sensitive concentration zone was revealed. To avoid the hotspot occurs, a ring-shaped phosphor convertor with two di?erent concentrations was developed. Results showed that the convertor with high-concentration center could reduce the max temperature by 9.4% without obvious optical power loss. Some further research suggestions were also proposed to improve the thermal performances of the laser illumination.
关键词： Thermal management,Phosphor heat generation,Theoretical model,Laser illumination
更新于2025-09-23 15:21:01
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Thermal management of high-power LED based on thermoelectric cooler and nanofluid-cooled microchannel heat sink
摘要： Effective thermal management for light-emitting diodes (LEDs) is critical, as temperature significantly affects their lifetime and performance. In this study, a system combining a thermoelectric cooler (TEC) and a microchannel heat sink (MHS) is investigated experimentally for thermal management of high-power LEDs. Nanofluids and water are used as coolant. The LED substrate temperature (Ts) is measured at various TEC powers, nanofluid concentrations, ambient temperatures of LED (Ta), and ambient temperatures of the fluid radiator (Ta,f). The effective thermal resistance (Rs-fa) of the LED substrate to the ambient of the fluid radiator is analyzed. Correlations of Ts and Rs-fa are obtained. Results show that the Ts is lowest when the TEC works at its rated power, and Ts is lower than Ta at Ta ≥ 55 °C. Using nanofluids instead of water as coolant reduces the Ts by up to 18.5 °C and decreases the thermal resistance by as much as 42.4%. The MHS heat transfer capacity is increased by 38.6%. The Ta,f exhibites greater influence on Ts compared to Ta. Results show that favorable performance of the thermal management of the high-power LED is obtained by the proposed nanofluid-cooled TEC-MHS system, particularly at high ambient temperature of LED.
关键词： Thermal management,Nanofluid,LED,Thermoelectric cooler,Thermal resistance,Microchannel heat sink
更新于2025-09-23 15:19:57
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[Laser Institute of America ICALEO?? 2015: 34th International Congress on Laser Materials Processing, Laser Microprocessing and Nanomanufacturing - Atlanta, Georgia, USA (October 18a??22, 2015)] International Congress on Applications of Lasers & Electro-Optics - New generation of high power reflective focusing optics (HPRFO)
摘要： As the high power laser market continues to grow, so does the need for robust optical solutions that can withstand the inherently harsh environment of laser welding. EWI continues to push the design envelope for high power optics that are capable of withstanding 20 kW or more of laser power for extended periods of time. A second version of EWI’s high power reflective focusing optics, referred to as HPRFO2, incorporates a patented aero window for internal protection of critical components, improved process effluent protection, and a revised beam delivery path. Long focal lengths separate the critical optics from the harsh welding environment without compromising the focal spot size. The previously published results of version one of the HPRFO exhibited minimal focal shift, unmatched by commercially available optics. In this work a production hardened version was designed and tested. Key attributes, which proved successful in version one of the HPRFO, were incorporated in the new design along with changes resulting from lessons learned. Shallower fold angles (compared to original HPRFO) for the asymmetric aspheric mirrors, adaptable effluent management solutions and better thermal management were included in the new design. Initial testing of the HPRFO2 demonstrated promising results and robustness unrivaled by commercially available optics.
关键词： HPRFO,reflective focusing optics,high power laser,thermal management,aero window
更新于2025-09-23 15:19:57