模拟器件稳态热场正确性的判断方法

对稳态热场,二个水平剖面A和B所夹的薄层上的温差必须严格等于本文提出的平均值定理的计算值．当芯片、基片和底座的截面大小一样时,可以直接根据平均值定理计算出芯片、基片和底座的每一水平剖面上的平均温度,通常可以手工完成;当芯片、基片和底座的截面大小不一样时,可以通过数据合成根据平均值定理计算出芯片、基片和底座的每一水平剖面上的平均温度．如果计算中有的参数如沟道长度不十分清楚时,应作模拟了解该参数对热斑温度的影响,必要时对该参数进一步了解以保证模拟精度．     

计算多芯片多基片模块稳态热场的层次模型

提出的层次模型将包括多芯片多基片模块的复杂热场模拟 ,分解为有确定耦合关系的形状简单的层次单元的热场计算 ,通过迭代将分区计算结果连成模块的热场 .在计算一个层次单元 (芯片、基片或底座 )的热场时 ,将其所在的层次单元 (母层次单元 )的上表面温度 ,作为该层次单元下表面的边界条件 ,而把它上表面上的层次单元 (子层次单元 )的下表面的向下热流作为置于它上表面的等效热源 .通过芯片→基片→底座→基片→芯片→基片…的几轮迭代就可收敛到正确值 .提出的层次单元间的耦合强度 (即每轮计算中 ,母层次单元上表面的温度改变不是全部 ,而是部分用于     

计算多芯片多基片模块稳态热场的层次模型

提出的层次模型将包括多芯片多基片模块的复杂热场模拟，分解为有确定耦合关系的形状简单的层次单元的热场计算，通过迭代将分区计算结果连成模块的热场.在计算一个层次单元(芯片、基片或底座)的热场时，将其所在的层次单元(母层次单元)的上表面温度，作为该层次单元下表面的边界条件，而把它上表面上的层次单元(子层次单元)的下表面的向下热流作为置于它上表面的等效热源.通过芯片→基片→底座→基片→芯片→基片…的几轮迭代就可收敛到正确值.提出的层次单元间的耦合强度(即每轮计算中，母层次单元上表面的温度改变不是全部，而是部分用于更新其子层次单元的下表面的边界条件)保证了所有情况下的迭代收敛.层次模型算法不仅速度数量级地高于普通的模块一体计算，而且热场与产生它的热源关系清楚，便于指导模块设计.计算与测量在实验误差(5℃)内符合.     

精确预计Si BJT微波功率器件峰值结温的方法

三维全热程热电一体地模拟了Si BJT微波功率器件.热场计算包括从芯片的有源区经芯片-粘接层-基片-粘接层-底座直到固定于70℃的安装台面的整个散热过程.在处理热电正反馈时把有源区的60个基本单元(子胞)当成60个并联子胞晶体管进行建模,子胞模型包括子胞晶体管本身、基区横向扩展电阻、发射区横向扩展电阻.热电一体分析除了涉及Vbe随温度变化外,还有子胞发射极有效面积随子胞发射极电流上升而下降的效应（以下称面积效应）.与对有源区各点直接进行分析相比,子胞建模不仅大大简化了计算,而且摸拟结果与器件结构、版图结构、工艺参数关系清楚.模拟预计的热斑温度（204℃）与投片后三个样品的平均测量结果（197℃）在实验误差（10℃）内一致.模拟结果说明面积效应对抑制热电正反馈有重要作用.     

精确预计SiBJT微波功率器件峰值结温的方法

三维全热程热电一体地模拟了 Si BJT微波功率器件 .热场计算包括从芯片的有源区经芯片 -粘接层 -基片 -粘接层 -底座直到固定于 70℃的安装台面的整个散热过程 .在处理热电正反馈时把有源区的 6 0个基本单元 (子胞 )当成 6 0个并联子胞晶体管进行建模 ,子胞模型包括子胞晶体管本身、基区横向扩展电阻、发射区横向扩展电阻 .热电一体分析除了涉及 Vbe随温度变化外 ,还有子胞发射极有效面积随子胞发射极电流上升而下降的效应 (以下称面积效应 ) .与对有源区各点直接进行分析相比 ,子胞建模不仅大大简化了计算 ,而且摸拟结果与器件结构、版图结构、工艺参     

GaAs MESFET沟道温度电学法测量的理论分析

1 引言 随着功率GaAs MESFET广泛的应用,它的热可靠性越来越引起人们的极大关注。用器件本身电学参数随温度的变化测量器件的沟道温度—电学法测试,能够非破坏性地快速测量封装后的成品管的沟道温度和热阻。并由此对GaAs MESFET进行考核和筛选,是当今快速筛选和考核的重要方法。 电学法测量出的温度普遍认为是器件有源区上的平均温度,但是这种温度与其器件芯片中的各种温度如最高温度、统计平均温度及芯片表面温度分布的关系如何,还未有过详细的研究。本文将对电学法测得的温度通过建立热模型进行模拟,找出电学平均温度的物理意义以及与其芯片中的各种温度的     

FDTD法分析高速集成电路芯片内互连线

本文首次利用时域有限差分(FDTD)法分析了高速集成电路芯片内半导体基片上的有耗互连传输线的电特性.文中提出了有耗吸收边界条件,推导了不同媒质交界面上的边界条件通用格式.在FDTD分析的基础上,得到传输线各种参数的频变特性,为芯片内电路模拟提供了可靠的参数.     

GaAs场效应微波功率器件稳态热场分析的等效结构模型

提出了用于计算ＧａＡｓ场效应微波功率器件峰值沟道温度的等效结构模型．其中底座与芯片等截面的等效厚度处理和多胞单胞化处理，使计算工作量下降约二个数量级．计算的峰值沟道温度与修正（包括了胞内热场分布影响、胞间热场分布影响和瞬态冷却过程影响）后的电学法测量值的差别约为３℃．文中还用此模型模拟了若干工艺参数对峰值沟道温度的影响     

大功率LED封装有限元热分析

介绍了有限元软件在大功率LED封装热分析中的应用,对一种多层陶瓷金属(MLCMP)封装结构的LED进行了热模拟分析,比较了不同热沉材料的散热性能,模拟了输入功率以及强制空气冷却条件对芯片温度的影响.结果表明当达到热稳态平衡时,芯片上的温度最高,透镜顶部表面的温度最低,当输入功率达到3 W时,芯片温度超过了150℃,强制空冷能显著改善器件的散热性能.     

对流边界层夹卷通量参数化的室内模拟研究

大气对流边界层室内模拟是大气边界层研究的一种常用手段.利用室内对流水槽(150cm×150cm×60cm)模拟了大气对流边界层,以实验获取的平均温度廓线数据和光斑图像为基础对夹卷通量进行了参数化研究.通过分析由光斑图像得到的折射率结构常数廓线获取边界层的结构,然后通过平均温度廓线计算下垫面和混合层顶的热通量.从而计算夹卷通量参数化结果,并以此对理想模型下的边界层发展进行了计算,其结果与水槽模拟的情况较一致.     

Heat dissipation design and analysis of high power LED array using the finite element method

High-power Light Emitting Diode (LED) technology has developed rapidly in recent years from illumination to display applications. However, the rate of heat generation increases with the LED illumination intensity. The LED chip temperature has an inverse proportion with the LED lifetime. High-power LED arrays with good thermal management can have improved lifetime. Therefore, for better optical quality and longer LED lifetime it is important to solve the LED thermal problems of all components. In particular, Metal Core Printed Circuit Board (MCPCB) substrate heat sink design and thermal interface materials are key issues for thermal management. This paper presents an integrated multi-fin heat sink design with a fan on MCPCB substrate for a high-power LED array using the finite element method (FEM). The multi-fin heat sink design and simulation results provide useful information for LED heat dissipation and chip temperature estimation.     

Simulating the dynamic electrothermal behavior of power electroniccircuits and systems

The simulator solves for the temperature distribution within the semiconductor devices, packages, and heat sinks (thermal network) as well as the currents and voltages within the electrical network. The thermal network is coupled to the electrical network through the electrothermal models for the semiconductor devices. The electrothermal semiconductor device models calculate the electrical characteristics based on the instantaneous value of the device silicon chip surface temperature and calculate the instantaneous power dissipated as heat within the device. The thermal network describes the flow of heat from the chip surface through the package and heat sink and thus determines the evolution of the chip surface temperature used by the semiconductor device models. The thermal component models for the device silicon chip, packages, and heat sinks are developed by discretizing the nonlinear heat diffusion equation and are represented in component form so that the thermal component models for various packages and heat sinks can be readily connected to one another to form the thermal network     

深低温大功率电阻阵列封装结构研究

电阻阵列的封装需求向着集成度高、大功率、深低温方向发展。为了满足130 K以下低温工作、稳态功率100 W以上的深低温应用需求，提出了一种利用液氮进行制冷的集成封装结构，并利用有限元仿真和实测验证相结合的方法验证了装置的制冷能力。结果表明，热沉钼与陶瓷电极板的厚度均为2 mm的情况下，加热功率在0.1~192.76 W区间内，有限元仿真得到的温度与实测温度最大误差小于7.67%，引起误差的主要原因是封装结构件的体热阻及界面热阻随温度发生变化而仿真时采用恒定热阻。结构能够在加热功率小于211.90 W的工况下正常工作。在设计的100 W稳定加热工况下，芯片衬底温度不高于101.9 K，热应力为5.66 MPa，满足设计要求。     

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。     

智能交通摄像机工作热负荷实验评价

利用红外热像技术,对某新型智能交通摄像机工作热负荷状况进行实验研究,并针对相机核心功耗元件DSP（数字信号处理器）和FPGA（现场可编程门阵列）开展了模拟芯片实验。原机实验结果表明,相机工作热负荷对芯片性能的影响不容忽视,即便处于只进行图像采集而不做图像处理的较低功耗模式下,不加散热器时DSP芯片表面温度已接近设计上限,因而有必要进行相机散热结构优化设计。模拟芯片实验证实,芯片功率对其表面温度有显著影响,功率越高,芯片温度呈近似线性增长,同时散热器瞬时储热能力有所减弱,因此合理控制芯片功率可有效降低相机工作热负荷。对比分析相机辅助散热器热阻可知,该散热器效率较低,存在进一步优化潜力。     

Electrothermal simulation of an IGBT PWM inverter

An electrothermal network simulation methodology is used to analyze the behavior of a full-bridge, pulse-width-modulated (PWM), voltage-source inverter, which uses insulated gate bipolar transistors (IGBTs) as the switching devices. The electrothermal simulations are performed using the Saber circuit simulator and include control logic circuitry, IGBT gate drivers, the physics-based IGBT electrothermal model, and thermal network component models for the power-device silicon chips, packages, and heat sinks. It is shown that the thermal response of the silicon chip determines the IGBT temperature rise during the device switching cycle. The thermal response of the device TO247 package and silicon chip determines the device temperature rise during a single phase of the 60-Hz sinusoidal output. Also, the thermal response of the heat sink determines the device temperature rise during the system startup and after load-impedance changes. It is also shown that the full electrothermal analysis is required to accurately describe the power losses and circuit efficiency     

An investigation of thermal enhancement on flip chip plastic BGApackages using CFD tool

This paper demonstrates the advantage of applying Predictive Engineering in the thermal assessment of a 279 inputs/outputs (I/Os), six-layer, depopulated array flip chip PBGA package. Thermal simulation was conducted using a computational fluid dynamics (CFD) tool to analyze the heat transfer and fluid flow in a free convection environment. This study first describes the modeling techniques on a multilayer substrate, thermal vias, solder bumps, and printed circuit board (PCB). For a flip chip package without any thermal enhancement, more than 90% of the total power was conducted from the front surface of the die through the solder ball interconnects to the substrate, then to the board. To enhance the thermal performance of the package, the heat transfer area from the backside of the die needs to increase dramatically. Several thermal enhancing techniques were examined. These methods included a copper heat spreader with various thicknesses and with thermal pads, metallic lid, overmolded with and without a heat spreader, and with heat sink. An aluminum lid and a heat sink gave the best improvement; followed by a heat spreader with thermal pads. Both methods reduced thermal resistance by an average of 50%. Detailed analyses on heat flow projections are discussed     

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.