电子系统热管理设计与验证中的结温估算与测量

针对电子系统容易出现的热失效问题,论述在电子系统的热管理设计与验证中,对半导体器件结温的估算和测量方法。通过测量半导体器件内部二极管参数,来绘制二极管正向压降与其温度关系曲线,进而求解出器件的结温估算值,以指导热管理设计;采用热分布测量和极值测量来计算器件的实际结温,对热管理设计进行评估、验证。使用所述估算和测量方法,可到达±5%精确度的半导体结温测算,能够有效评估器件在特定电子系统中的热可靠性,为实现可靠热管理提供可信的数据分析基础。     

温度对压接型IGBT器件内部接触热阻的影响

温度是功率半导体器件备受关注的问题,不仅直接影响功率半导体器件的电气性能,而且还间接影响功率半导体器件的热学和机械特性.压接型IGBT器件内部是电磁场、温度场和结构场的多物理量耦合场,器件内部各组件间的接触热阻是温度场与结构场双向耦合的重要桥梁,也是器件可靠性的重要影响因素.通过单芯片子模组有限元模型分析了各组件间的接触热阻,重点研究了温度对接触热阻的影响,计算了热阻测量前后的接触热阻值,并进行了对比.鉴于目前接触热阻测量方法的局限性,通过测量单个快恢复二极管(FRD)芯片子模组结到壳热阻值与温度的变化关系间接得到接触热阻与温度的关系,并对有限元计算结果进行了验证.     

本期主题索引

安全措施12668安全管理 一软件开发安全装且 一设计板金成形 一控制半导体薄膜 一结构半导体材料 13147 13163 一光吸收 一化合物半导体 一特性 一制备 13152半导体放大器 一制造半导体工艺 13204 13211 一多硅物 一激光应用 一优化半导体激光器 14599 一对准 一光学系统 一可靠性评价 一热工测量 一微型组件 一温度控制 一性能 一应用半导体集成电路 一光刻 一硅半导体技术 一发展 一应用研究半导体器件 一材料分析 一光学性质 一结构 一热疲劳试验 一热特性半导体陶瓷 一制备半导体物理学半导体整流器 一电路分析 一控制 一控制电路 一砷…     

光学和红外辐射的探测

本教科书主要阐述了光学和红外探测的原理,并且介绍了探测器的物理特性以及探测器若干应用。全书共有十一章:①热辐射和电磁波形;②理想光子探测器;③相干或外差探测;④放大器噪声及其对探测器性能的影响;⑤真空光电探测器;⑥半导体器件     

功率半导体器件直流参数测试系统的研发

背景 介绍功率半导体器件应用非常广泛,是各种电子系统及仪器的基础,通常包括功率二极管、三极管、MOS场效应管、结型场效应管、可控硅等。目前,功率半导体器件应用单位涉及航天、航空、高等院校、电子研究所等诸多部门。其制造工艺及其设计水平较原来普通器件在功率上有了很大的提高,     

一种测量小功率二极管及其它中小功率半导体器件热阻的简易方法

半导体器件的功率极限是由它的热阻决定的,要决定一种新器件的最大使用功耗,就必须首光测量热阻.但DO-35玻封二极管的管壳很小,无法直接测量其管芯的温度,从而算出热阻.为此,笔者设计了一种利用半导体器件温度特性测量热阻的方法,避免了复杂的设备和直接测量管芯温度的困难,只要一块数字式万用表就能完成热阻测量,且测量误差小于10%.此外,这种方法可方便地推广到各种其它封装形式的中.小功率半导体器件上,特别是适用于塑料封装和陶瓷封装等无其它方法测量热阻的器件.     

热管理设计中的温度检测

热管理始于温度测量,Maxim开发了各种用于这种测量的温度检测IC。除了不同类型的传感器IC外,电子系统还可以采用其它多项技术测量温度。本文简要介绍了热管理应用中温度检测方法。     

电子系统的热仿真及热测试研究

通过对电子系统热控制技术的介绍,分析了电子系统的可靠性与热仿真之间的关系,阐述了热仿真的优点。详细介绍了热测试的方法和手段,突出了热测试在高热流密度热控技术中的作用,并以实际应用中的热仿真结果与热测试数据进行了比较,进一步说明了热仿真与热测试协同工作,相互验证的重要性。     

气溶胶光学吸湿增长特性测量方法研究进展

吸湿性气溶胶会吸收环境空气中的水分, 其粒径会随相对湿度的增加而发生变化, 从而导致气溶胶的光学特 性 (如消光、散射、吸收系数与单次散射反照率等) 发生显著的变化。气溶胶光学吸湿增长因子 (湿状态与干状态下 光学参数的比值) 是衡量气溶胶光学吸湿增长能力的特征参数, 是计算大气能见度和气溶胶辐射强迫的关键输入量, 它的准确测量对于气溶胶环境和气候效应的评估具有重要意义。光学吸湿增长测量系统主要包括湿度调节系统和光 学测量装置, 通过湿度调节系统改变样品的相对湿度, 再结合光学测量装置实时测量光学参数的变化, 从而实现光学 吸湿特性的在线测量。鉴于气溶胶吸湿性研究的重要意义, 重点分析对比了现有的光学吸湿增长测量方法及应用, 并 对下一步气溶胶光学吸湿增长特性测量技术和研究方向做了展望。     

应用于低对比度扩展目标观测的大型阵列太阳自适应光学电子系统的设计与实现

自适应光学由于能够显著提高空间分辨率,在天文观测领域日益得到广泛的应用。与通常应用于恒星观测的夜天文自适应光学技术相比,对太阳表面低对比度扩展目标的观测校正一直是自适应光学中的难点。该文针对太阳观测中的低对比度扩展目标特性,采用FFT协方差相关算法,初步实现了大型阵列自适应光学电子系统。该系统采用阵列DSP和FPGA协同工作的架构,由低阶相关跟踪系统和高阶波前处理系统两部分组成。初步实验结果表明,系统能够满足预先设计的要求,并且具有较好的灵活性、通用性和扩展性。     

An improvement of thermal conductivity of underfill materials for flip-chip packages

Effective heat dissipation is crucial to enhance the performance and reliability of electronic devices. In this work, the performance of encapsulants filled with carbon fiber was studied and compared with silica filled encapsulants. Encapsulants filled with mixed combination of fillers for optimizing key properties were also investigated. The thermal and electrical conductivities were investigated and glass transition temperature (Tg), thermal expansion coefficient (TCE), and storage modulus (E') of these materials were studied with thermal analysis methods. The composites filled with both carbon fiber and silica showed an increase of thermal conductivity three to five times of that of silica filled encapsulants of the same filler loading while maintaining/enhancing major mechanical and thermal properties.     

Correlation of scanning thermal microscopy and near-field cathodoluminescence analyses on a blue GaN light emitting device

A scanning near-field thermal microscope and a scanning electron microscope/scanning near-field optical microscope hybrid system for near-field cathodoluminescence investigations were used to characterize blue GaN LEDs. Optoelectronic, electronic and thermal device properties are determinable with highest resolution. These results provide an interesting perspective with respect to failure analyses and reliability of the devices.     

Adhesion measurement for electronic packaging applications usingdouble cantilever beam method

Multilayers and interfaces are ubiquitous in microelectronics devices, interconnect and packaging structures. As the interface integrity becomes the major concern of performance, yield, and reliability, the need to evaluate the fracture and delamination behavior of various interfaces increases. This work focused on quantifying interfacial adhesion performance of a typical electronics packaging structure, flip-chip-on-organic-substrate. A series of experiments and analyzes were conducted to investigate the adhesion and fracture behaviors of the underfill/silicon and underfill/organic substrate interfaces. The experimental techniques for the interfacial fracture experiments were developed to produce the double-cantilever-beam (DCB) specimens and to establish a reproducible testing protocol. To extract the interfacial fracture energies, a closed-form solution was developed based on a beam-on-elastic-foundation model. A two-dimensional elastoplastic finite element analysis (FEA) model was also implemented to examine effects of mode-mixity, thermal/residual stresses, and underfill plasticity. The techniques allow for reproducible determination of underfill/printed circuit board (PCB) and underfill/silicon chip interfacial adhesion strength. The developed techniques are also readily applicable to evaluate interfacial adhesion performance for many other similar electronic packaging systems. This provides capabilities in optimizing material selections and process conditions to improve interfacial adhesion performance, Additionally, the interfacial fracture energy measured with high accuracy can provide a basis for realistic modeling of thermo-mechanical reliability of electronic components     

Comparative study of thermally conductive fillers for use in liquidencapsulants for electronic packaging

Thermal management plays a very vital role in the packaging of high performance electronic devices. Effective heat dissipation is crucial to enhance the performance and reliability of the packaged devices. Liquid encapsulants used for glob top, potting, and underfilling applications can strongly influence the package heat dissipation. Unlike molding compounds, the filler loading in these encapsulants is restrained. This paper deals with the development and characterization of thermally conductive encapsulants with relatively low filler loading. A comparative study on the effect of different ceramic fillers on the thermal conductivity and other critical properties of an epoxy based liquid encapsulant is presented     

Real-time system for monitoring the electro-thermal behaviour of power electronic devices used in boost converters

Reliability of power electronic devices (PEDs) is a key issue to secure power supplies in modern word, especially, those generated from renewable energy sources. Thermal stress due to switching frequency and environmental conditions are commonest cause of currently unsatisfactory PEDs reliability scores.In this paper, the electro thermal performance of PEDs and related parameters are critically investigated using three types of differently manufactured insulated gate bipolar transistors (IGBTs). Namely, punch through (PT), non-punch through (NPT) and field stop (FS) silicon trench gate technologies.First, currents and voltages of the examined IGBTs were measured under different operating temperatures, switching frequencies and electrical loading conditions.Second, power losses of the examined devices were calculated, in real time, based on their measured currents and voltages using realistic mathematical model embedded in a dSPACE system. Subsequently, the power losses for each device were used as an input to a finite element model to graphically predict heat distributions for each of the monitored devices.Compared to expensive measurements taken by high-resolution thermal imaging cameras, the accuracy of the developed system achieved 97%. The obtained results demonstrate the developed model would serve as an inexpensive and powerful tool for monitoring PEDs thermal conditions.     

Valleytronics,Carrier Filtering and Thermoelectricity in Bismuth: Magnetic Field Polarization Effects

Valley polarization of multi‐valleyed materials is of significant interest for potential applications in electronic devices. The main challenge is removing the valley degeneracy in some controllable way. The unique properties of bismuth, including its anisotropic electronic structure and Dirac valley degeneracy, make this material an excellent system for valleytronics. It is demonstrated theoretically that the direction of an externally applied magnetic field in the binary‐bisectrix plane has a profound effect not only on the charge, but also on the thermal transport along the trigonal direction. The rotating field probes the electronic mass anisotropy and tunes the contribution from a particular Dirac valley in the electrical resistivity, Seebeck coefficient, and thermal conductivity at moderate temperatures and field strengths. It is further shown that the field polarization of the transport properties is accompanied by selective filtering of the carriers type providing further opportunities for thermoelectric transport control.     

航空航天用电子封装材料及其发展趋势

随着航空航天领域的迅速发展,其应用的电子器件不断微型化、高度集成化,并且可靠性要求越来越高,其电子封装材料具有更高的热导率及与芯片热膨胀系数的匹配性,还要求其电子封装材料具有更低的密度。BeO、AlN、Al/SiC与AlSi由于具有高热导率、低密度及与芯片材料良好的热膨胀匹配性,非常符合航空航天用电子封装材料的发展趋势,并已经逐步在取代常用的一些封装材料。重点介绍了四种材料的性能优势,以及它们之间的性能对比与应用前景分析。     

Thermal Modeling, Analysis, and Management in VLSI Circuits: Principles and Methods

The growing packing density and power consumption of very large scale integration (VLSI) circuits have made thermal effects one of the most important concerns of VLSI designers. The increasing variability of key process parameters in nanometer CMOS technologies has resulted in larger impact of the substrate and metal line temperatures on the reliability and performance of the devices and interconnections. Recent data shows that more than 50% of all integrated circuit failures are related to thermal issues. This paper presents a brief discussion of key sources of power dissipation and their temperature relation in CMOS VLSI circuits, and techniques for full-chip temperature calculation with special attention to its implications on the design of high-performance, low-power VLSI circuits. The paper is concluded with an overview of techniques to improve the full-chip thermal integrity by means of off-chip versus on-chip and static versus adaptive methods.     

Plastic encapsulated components for cars

Thermal management in electronics packaging is important. Thermal stress greatly affects reliability and aging of electronic circuits. Our group developed a thermal simulation tool named TRESCOM for investigating thermal problems in electronic packaging. We used this tool for steady-state and dynamic analyses of the thermal qualities of PLCC and CLCC components. Our investigation demonstrated the surprising result that the thermal performance of the plastic encapsulated components is superior to hermetically sealed ceramic components. We conclude that plastic packages are reliable and can compete with ceramic packages at the elevated temperatures that are found in automotive applications     

Heat-pipes for electronic devices and evaluation of their thermalperformance

This paper reports on the performance of miniature heat-pipes developed for cooling of electronic equipment, and on evaluating the notebook computer cooling systems in which they are used. Experiments for the miniature heat-pipe were conducted on their thermal properties and reliability. The results indicate the miniature heat-pipe can be applied to electronic equipment cooling. Evaluating tests of the cooling system using this miniature heat-pipe have clarified the effectiveness of the miniature heat-pipe