星载差分吸收光谱仪热设计与试验研究

星载差分吸收光谱仪是一种高精度的空间光学遥感器,基于被动DOAS技术,利用成像光谱仪获取高光谱、高空间分辨率的光谱信息。载荷的温度水平、温度波动范围对仪器的正常工作与测量精度有较大影响,温控指标要求较高。由于光机结构紧凑复杂,且需兼顾光路系统的温度要求,导致局部散热成为整个系统中的难点。为满足探测器对温度环境的要求,本文针对仪器的结构布局特点及热耗分布情况,提出了被动热控为主,主动热控为辅的设计方案;利用I-DEAS/TMG热分析软件对光谱仪的在轨温度水平进行了仿真计算,得到典型工况下各散热环节的温度分布及温度波动情况。仪器进行了整机热平衡试验,验证了热设计的合理性,并将试验结果与热分析结果进行了对比。试验结果表明：光谱仪各部件温度均能够满足指标要求,热设计合理可行。     

Thermal management for high-power photonic crystal light emitting diodes

An effective heat dissipation structure is a crucial element for stable thermal management in ensuring thermal stability of high power photonic crystal light emitting diodes (PC-LEDs). New integrated structure for effective thermal management is put forward for high power PC-LEDs to reduce the thermal resistance between the chip and heat dissipation device, which can be composed by the heat pipes or an active heat dissipation device. Based on the thermal resistances analyzed, 3D thermal distributions for the device CSM360 with the nominal electric power of 80 W are simulated and analyzed by using of ANSYS. Compared with the general metal fins model, the heat pipes integrated model improves the heat dissipation efficiency of CSM360 by 36.61%, while the active heat dissipation device integrated model improves the heat dissipation efficiency by 60.2% at the temperature of 50 °C on the cold end of the device. The results show that the integrated structure can obtain a significant improvement in thermal management and achieve a reduction in temperature in the working status of CSM360. Heat dissipation experiments are also conducted, and the values of temperature distributions are validated to be coincident with those from simulations.     

Thermal analysis and an improved heat-dissipation structure design for an AlGaInP-LED micro-array device

This paper describes a novel finite element thermal analysis model for an AlGaInP-LED micro-array device. We also conduct a transient analysis for the internal temperature field distribution of a 5×5 array device when a 3×3 unit is driven by pulse current. In addition, for broader applications, a simplified thermal analysis model is introduced and its accuracy is verified. The internal temperature field distribution of 100×100 units is calculated using the simplified model. The temperature at the device center reaches 360.6 °C after 1.5 s. In order to solve the heat dissipation problem of the device, an optimized heat dissipation structure is designed, and the effects of the number and size of the heat dissipation fins on the thermal characteristics of the device are analyzed. This work has been supported by the Young Scientists Fund of the National Natural Science Foundation of China (No.61204055). E-mail:gaofl@jlu.edu.cn       

某高超音速导弹用新型天线透波隔热装置设计

透波隔热装置是高超音速导弹用天线设计的关键部件之一.通过石英纤维增强氮化物陶瓷透波材料和二氧化硅气凝胶复合隔热材料的选用,采用合理隔热装置结构设计,经样件热防护性能测试,有效的降低了天线体及馈线温度,证明该方案满足高超音速导弹天线设计需求,可在后续工程中推广使用.     

深亚微米槽栅PMOS结构对抗热载流子效应的影响

基于流体动力学能量输运模型 ,利用二维仿真软件 MEDICI对深亚微米槽栅 PMOS器件的结构参数 ,如凹槽拐角、负结深、沟道和衬底掺杂浓度对器件抗热载流子特性的影响进行了研究 ,并从器件物理机制上对研究结果进行了解释。研究发现 ,随着凹槽拐角、负结深的增大和沟道杂质浓度的提高 ,器件的抗热载流子能力增强。而随着衬底掺杂浓度的提高 ,器件的抗热载流子性能降低。结构参数影响了电场在槽栅 MOS器件的分布和拐角效应 ,从而影响了载流子的运动并使器件的热载流子效应发生变化。     

Nucleation and control of departure of a high-field domain by a gate electrode

Experimental results are given which show that, in a m.i.s.f.e.t. type GaAs bulk device, a negative voltage applied to the gate electrode can nucleate a high-field domain under the gate electrode, but that its subsequent departure for the anode is allowed or inhibited depending on the device structure and operating conditions.     

电子器件用热管散热器及其性能分析

随着电子元件工作频率和集成度不断提高，其散热量也在急剧增加，传统散热器在散热能力上已很难满足要求，这将严重影响设备运行的稳定性，本文通过分析热管的工作原理，建立了将热管应用于散热器的传热模型，分析了热管散热器与传统热器在散热能力和安装、布置、运行等方面上的优势，认为新型热管散热器具有很好的应用前景。     

A novel nanoscale SOI MOSFET with Si embedded layer as an effective heat sink

A novel structure such as nanoscale silicon-on-insulator (SOI) MOSFET with silicon embedded layer (SEL-SOI) is proposed to reduce self-heating effects (SHEs) successfully. The SEL as a useful heat sink with high thermal conductivity is inserted inside the buried oxide. The SEL acts like a heat sink and is therefore easily able to distribute the lattice heat throughout the device. We noticed excellent improvement in the thermal performance of the device using two-dimensional and two-carrier device simulation. Our simulation results show that SHE has been dramatically reduced in the proposed structure. In regard to the simulated results, the SEL-SOI structure has shown good performance in comparison with the conventional SOI (C-SOI) structure when utilised in the high temperature applications.     

电力电子器件封装模块的散热特性

以传统电力电子器件封装模型为基础,介绍了大功率电力电子器件热量传递机理、失效原因。阐述了电力电子器件的主要外部散热方式及发展现状。最后基于有限元软件ANSYS为平台,通过改变电力电子器件内部结构,包括芯片间距、衬板厚度、铜底板厚度,分析了内部结构芯片散热的影响。通过测试发现,当芯片分布均匀时,散热效果最好,导热系数较高的材质,芯片散热效果较为理想。在小范围内,芯片结温随底铜板厚度增加而下降,之后芯片结温随厚度增加而升高。     

一种新的红外热像图分析方法及其在乳腺肿瘤诊断中的应用

本文基于热断层的思想,提出了用于分析人体内热源信息的一种新的热像图分析方法。通过建立有内热源的热传导微分方程,得出方程的解。再结合实际,应用叠加原理将体表的正常体温和异常热源的温度叠加起来,得出了有内热源的体表温度分布表达式,利用该表达式对红外热像图上可能的病变区域的温度数据进行了分析处理。处理过程中选择了两个参考变量:热源的深度h和热源的发热强度q。深度h对应于肿瘤解剖位置的深度,发热强度q对应于肿瘤的性质:良、恶性的判断。临床病例证明,这两个参数对肿瘤的定性、定位是很有效的。     

Parameter sensitivity of narrow-channel MOSFET's

An analytical method is used to examine the threshold voltage sensitivity due to various device parameter fluctuations in the narrow-channel MOSFETs. The analysis is based on a narrow-channel model with a semirecessed field-isolation structure and a short-channel modification. The results show that while the dopant-concentration and fixed-oxide charges fluctuation increases sensitivity, the back-gate bias fluctuation decreases sensitivity as the channel width is reduced. The present strategy is simple and is therefore ideal for miniaturized device processing simulation     

Compact thermal models for internal convection

Objects undergoing heat transfer by convection internally, i.e., not at their boundaries, need special care in their modeling. An extension of the general formulation made earlier for compact thermal models is discussed here in order to cover the case of internal forced convection problems such as micro-channels. The single resistor model based on the heat transfer coefficient h is replaced with a compact model linking all relevant nodes using h as well as fluid thermal capacitance and inertia, such as to satisfy thermodynamic constraints derived earlier for conduction compact models.     

Self-heating effects in a BiCMOS on SOI technology for RFIC applications

Self-heating in a 0.25 /spl mu/m BiCMOS technology with different isolation structures, including shallow and deep trenches on bulk and silicon-on-insulator (SOI) substrates, is characterized experimentally. Thermal resistance values for single- and multifinger emitter devices are extracted and compared to results obtained from two-dimensional, fully coupled electrothermal simulations. The difference in thermal resistance between the investigated isolation structures becomes more important for transistors with a small aspect ratio, i.e., short emitter length. The influence of thermal boundary conditions, including the substrate thermal resistance, the thermal resistance of the first metallization/via layer, and the simulation structure width is investigated. In the device with full dielectric isolation-deep polysilicon-filled trenches on an SOI substrate-accurate modeling of the heat flow in the metallization is found to be crucial. Furthermore, the simulated structure must be made wide enough to account for the large heat flow in the lateral direction.     

两热源热管散热模组瞬态性能热分析

电子设备散热结构的瞬态性能对判断冷却系统的结构是否合理非常重要却很少被研究。采用热阻网络法,得出了多热源热管散热模组的数学模型。应用MATLAB模拟了热管散热模组在设计工况和变工况下各点温度的瞬态散热特性。结果显示,该热管散热模组的瞬态响应性能较好,其最大温差在散热器部分。瞬态温度响应具有滞后性。热源散热量突然急剧变化时,对热源部分的影响较大而对环境的影响较小。     

一种适用的智能电话集线器

为增加ＪＫ－１０００微波通信系统的话务量，详细介绍了一种以ＴＭ８８１６为开关器件的电话集线器的硬件构成和软件框图，实验已证明这种集线器是可用的。     

基于Ansys优化模块的热设计应用

发热量大的电子器件温度会比较高,过高的温度会影响到器件的正常工作,因此需要用到热仿真软件去进行有效的热设计。优化设计是有限元分析软件(Ansys)的特有模块,利用该模块应用于两种典型的热设计实例,分别是处理器CPU散热器结构和电路板器件分布的优化设计,仿真分析出来的结果显示,CPU散热器的散热性能得到明显的提高,电路板上各器件的温度均得到降低,获得良好的优化效果。     

坦克高温表面相变红外抑制装置传热分析

为了降低坦克高温表面的红外辐射特性,设计了相变红外抑制装置,建立了传热模型,利用FLUENT软件进行了传热分析,并进行了实验验证,温度计算值与实验值对比,最大相对误差小于6.5%。传热分析结果显示,在坦克导热和太阳辐射等因素的作用下,相变材料发生恒温相变,液相率逐渐变大,红外抑制装置温度较坦克表面温度下降40%;坦克内热源温度的升高、相变材料厚度的减小均可导致相变提前开始、相变持续时间缩短;相变材料熔点温度的下降使相变开始时间提前,同时使红外抑制装置的温度降低。     

Validation methodology to analyze the temperature-dependent heat path of a 4-chip LED module using a finite volume simulation

Thermal management in the solid-state lighting sector has become a main issue, due to reliability and efficiency issues. Herein, thermal structure function analysis provides a powerful tool to understand the heat transfer inside operated light emitting diode (LED) modules. In this paper a combined approach of simulation and experiment, as a heat path analysis of a LED module based on four flip chip LEDs, is presented. A validated simulation was used to visualize on the one hand the heat path as isothermals and on the other hand to show an alternative approach of the electrical transient correction. In addition to that, the structure function analysis also included the consideration of influence parameters in terms of different operating conditions (e.g. heat sink temperature, heating current, the use of different thermal interface materials between the device and the heatsink). This was investigated by the statistical Design of Experiments (DOE) approach. The DOE dissected the effect of each input variation to different features of the structure functions. An experimental setup showed, that the temperature of the heat sink caused the dominating effect on the thermal properties of the device. Finally numerical simulation confirmed that these effects came from the temperature dependencies of the thermal conductivities.     

The effect of heat treatments on the properties of Ti/Pt heating elements for gas sensor applications

Ti/Pt as heating element for gas sensor applications was fabricated on silicon (Si) wafer substrate. The fabricated device was subjected to heat treatment at different prescribed time periods for thermal stability. The energy dispersion spectroscopy (EDS) results of the device indicated that there were no Ti traces on the Pt surface after heat treatment at 450 °C for 3 and 4 h in an argon (Ar) atmosphere. A maximum temperature coefficient of resistance (TCR) with a value of 2.88×10^?3 K^?1 was obtained for the device with 3 h heat treatment.     

Time scale matching of dynamically operated devices using composite thermal capacitors

A new thermal management solution is proposed to maximize the performance of electronics devices with dynamically managed power profiles. To mitigate the non-uniformities in chip temperature profiles resulting from the dynamic power maps, solid–liquid phase change materials (PCMs) with an embedded heat spreader network are strategically positioned near localized hotspots, resulting in a large increase in the local thermal capacitance in these problematic areas. The resulting device, called composite thermal capacitor (CTC), can theoretically produce an up-to-twenty-fold increase in the time that a thermally constrained high heat flux device can operate before a power gating or core migration event is required. A prototype CTC that monolithically integrates micro heaters, PCMs and a spreader matrix into a Si test chip was fabricated and experimentally tested to validate the efficacy of the concept and to gain an insight into phase change heat transfer in a spatially-confined environment on the microscale. As the most significant result, an increase in allowable device operating times by over 7× has been experimentally demonstrated, while operating a device at heat fluxes approaching 400 W/cm².