Improving the FE simulation of molded packages using warpage measurements

Due to the constant development of new components in microsystem technology the possibility to guarantee the reliability and lifetime of these components is essential. An efficient method for this purpose is Finite Element (FE) modelling. In order to shorten lengthy and expensive lifetime tests, FE simulations become more and more necessary. To obtain suitable FE models, multitude of material and technical component characteristics are needed. However, due to the rapid development of new materials, the characteristics are often insufficient or even unknown. Therefore additional measurements of the material or the complete system are necessary. Which material data is required depends first and foremost on the component and its usage.In this paper the importance of temperature dependent topographic measurements for the simulation model of a package design (Smart Power Module) will be demonstrated. The warpage of a whole package was measured at different temperatures in order to obtain unknown material behaviour like the chemical shrinkage and polymer relaxation. For this purpose, the Shadow Moiré Measurement Method was utilised.This work will focus on how to obtain experimental data of two different molding compounds (MC) in several stages of lifetime as well as implementing the results in a FE simulation model.     

Design and FE analysis of integrated sensing using gas compressibility for microdroplet generation

As trends in biology, chemistry, medicine and manufacturing have pushed macroscopic processes onto the microscale, robust technologies have become necessary to encapsulate liquids into microdroplets for further manipulation and use. In order to most effectively utilize these microdroplets, real-time sensing is needed during the generation process to monitor the size of the droplet generated, or if generation failed to occur. Current droplet generating technologies operate either in open-loop, with no direct feedback available to the control system to monitor the process, or in closed loop with external sensing, using photography or droplet weight measurement to measure droplet size. By utilizing internal system-based sensing to close the loop, corrections in the dispensing process could be made in real-time in response to malfunctions as they occur. Furthermore, the generator’s operator could be more quickly alerted when a systemic error, such as a clog, continues to occur. One candidate solution to provide system-based sensing is to monitor the pressure of a reservoir of compressible gas kept adjacent to the reservoir of droplet liquid, both within a constant volume fluid chamber. The gas reservoir pressure during the actuation sequence can be related both analytically and empirically to the volume of the droplet ejected from the device, including instances where generation fails and a droplet is not ejected. This paper describes the designs of potential systems to realize this design concept, and the development of a finite element simulation for one of the concepts capable of generating droplets while simultaneously monitoring the pressure of the gas reservoir. A linear relationship between this calculated pressure and the volume of the dispensed droplet is found, validating the sensible property as workable for implementation in a physical system.     

Multisim仿真软件中三极管模型参数的确定

Multisim仿真软件元件库中找不到特定型号三极管时,常常需要新建三极管模型并确定模型参数。从电流特性、输出特性等七个方面分析了三极管G-P模型参数的物理意义,并且通过实例说明了通常情况下三极管模型参数的估算方法。对于模型参数的准确性通过实验的方法加以验证,表明这种估算方法具有较好的仿真度和实用性。     

用透射光谱法测光栅参数的数值模拟

本文基于光栅的严格理论,提出结合透射光谱和优化算法来测量光栅参数的新方法,首先,利用傅立叶模式理论和反射透射系数递推算法(RTCM) ,计算出在2 0 0 -90 0nm波段内的理论透射光谱图,通过在上面叠加不同偏差的高斯噪声来模拟光栅的实际测量曲线,接着在模拟曲线上任取若干个点作为实验测量值,最后利用优化算法进行反演搜索,找到待测光栅的结构参数。文中我们选择了三种类型的光栅对该法进行数值上的模拟,其结果是成功的。该法可能会给光栅参数的测量指明一条新的途径。     

介质体电磁散射的偶极子模型法研究

提出用偶极子模型法来分析介质体的电磁散射.该方法以矩量法和Schaubert-Wilton-Glisson(SWG)基函数为基础,把介质体剖分成一定数量的四面体元.在介质体内,把含有公共面的体元对等效成电偶极子;在介质体表面,把边界面及其对应的体元等效成电偶极子.当等效偶板子单元离观察点大于临界距离时,用偶极子模型法计算阻抗矩阵元素.偶极子模型法简单易操作,不仅能大幅度降低阻抗矩阵的计算时间,还简化了边界条件的处理.数值结果表明了该方法的高效性及与原方法几乎相同的计算精度.     

Characterization and simulation analysis of laser-induced crystallization of amorphous silicon thin films

The effect of laser energy density on the crystallization of hydrogenated amorphous silicon (a-Si:H) thin films was studied theoretically and experimentally. The thin films were irritated with a frequency-doubled (λ=532 nm) Nd:YAG pulsed nanosecond laser. An effective finite element model was built to predict the melting threshold and the optimized laser energy density for crystallization of intrinsic amorphous silicon. Simulation analysis revealed variations in the temperature distribution with time and melting depth. The highest crystalline fraction measured by Raman spectroscopy (84.5%) agrees well with the optimized laser energy density (1000 mJ/cm²) in the transient-state simulation. The surface morphology of the thin films observed by optical microscopy is in fairly good agreement with the temperature distribution in the steady-state simulation.     

Experimental analysis and optimization of a photo resist coating process for photolithography in wafer fabrication

This investigation is applied the Taguchi method and combination the analysis of variance (ANOVA) to the photo resist (PR) coating process for photolithography in wafer manufacturing. Plans of experiments via nine experimental runs are based on the orthogonal arrays. In this study, the thickness mean and the uniformity of thickness of the PR are adopted as the quality targets of the PR coating process. This partial factorial design of the Taguchi method provides an economical and systematic method for determining the applicable process parameters. Furthermore, the ANOVA prediction of the thickness mean and the uniformity of thickness for the PR has been applied in terms of the PR temperature, chamber humidity, spinning rate, and dispensation rate by means of the designs of experiments (DOE) method. The PR temperature and the chamber humidity are found to be the most significant factors in both the thickness mean and the uniformity of thickness for a PR coating process. Finally, the sensitivity study of optimum process parameters was also discussed.     

Numerical simulation of shock wave phenomena in hydrodynamic model of semiconductor devices

We propose a finite element method to investigate the phenomena of shock wave and to simulate the hydrodynamic model in semiconductor devices . An introduction of this model is discussed first. Then some scaling factors and a relationship between the changing variables are discussed. And then, we use a finite element method (P1-iso-P2 element) to discrete the equations. Some boundary conditions are also discussed. Finally,a sub-micron n+-n-n+ silicon diode and Si MESFET device are simulated and the results are analyzed. Numerical results show that electronic fluids are transonic under some conditions.     

基于容性耦合夹的汽车电子传导骚扰测试方法研究

目前在汽车电子电磁兼容测试领域,普遍采用电压法和电流探头法对零部件/模块的传导发射进行测量.近年来,著名德系车厂提出了一种全新的基于容性耦合夹的传导骚扰测试方法(CV-Test).本文对这一新的测试方法进行了介绍,同时给出插入损耗的校准方法.采用基于容性耦合夹的方法进行传导骚扰的测试正成为汽车电子电磁兼容测试领域一种新的动向,逐步被车企认可和采用,具有较好的应用前景.     

Use of transportable test stations for measuring satellite coverage dependent parameters during IOT campaigns

The in-orbit tests of the satellite coverage dependent parameters require the rotation of the satellite around its pitch and roll axes in order to ‘bring’ the various coverage locations onto one fixed IOT station. Alternatively, several transportable test stations can be located at different sites in the coverage area in order to measure the satellite performances on site. Although the second technique does not provide enough measurement points to reconstruct the complete coverage of shaped beam antennas, it presents several advantages for which it is still used by EUTELSAT for the IOTs of its satellites in conjunction with measurements based on the satellite attitude movements. In particular, the transportable test stations are used to test the stability of satellite EIRP and IPFD at the edges of the coverage areas, where the performances are more sensitive to the pointing errors induced by thermal deformation or satellite attitude changes. This paper presents the common experience gained by EUTELSAT and ESA in testing the coverage dependent parameters of the first and second generation of EUTELSAT satellites. In particular, the paper deals with the use of the transportable test stations during the EUTELSAT II F1 to F3 acceptance tests and with the test campaigns performed at several sites in the eastern European countries. In the first case, the transportable test stations were used in conjunction with satellite rotations around the pitch axis in order to measure the coverage dependent parameters along several cuts parallel to the equatorial plane at different roll angles. In the second case, the transportable test stations were used to periodically repeat the EIRP measurements of many satellite channels over several hours in order to test the EIRP stability of the EUTELSAT II satellites. For both cases, the paper presents a synthesis of the most significant IOT results together with a comparison between these results and the values of the coverage dependent parameters predicted on the basis of the on-ground tests.     

基于最大匹配原则的变电运行培训仿真评估新方法

对于变电运行培训工作而言,仿真评估方法的作用主要是判断培训效果.影响判断准确性的因素主要是所使用仿真评估方法的实效性.本文从评价机制应具备的作用入手,对基于最大匹配原则的变电运行培训仿真评估新方法进行分析和研究.     

印制板焊接试验方法与测试评价

焊接试验方法是考察印制板质量和可靠性的重要方法之一,本文通过对3种具体试验方法的标准介绍和比较,结合实际试验案例进行原因分析,为PCB检验人员正确掌握以上试验方法提供技术指导。     

Numerical study on performance of pyramidal and conical isotropic etched single emitters

A full three-dimensional model was implemented in order to investigate the electrical characteristics of conical and pyramidal isotropic etched emitters. The analysis was performed using the finite element method (FEM). The simulations of both emitters were modeled using a combination of tetrahedral and hexahedral elements that are capable of creating a mapped and regular mesh in the vacuum region and an irregular mesh near the surfaces of the emitter. The electric field strengths and electric potentials are computed and can be used to estimate the field enhancement factor as well as the current density using the Fowler-Nordheim (FN) theory. The FEM provides results at nodes located at discrete coordinates in space; therefore, the surface of the emitter can be generated through a function interpolating a set of scattered data points. The emission current is calculated through integration of the current density over the emitter tip surface. The influences of the device geometrical structure on its potential distribution, electric field and emission characteristics are discussed.     

基于自由空间法的液体等效电参数测试系统的研究

自由空间法是一种非限制测试环境的测量方法,它能被应用于实验室测量或室外实地测量中。本文运用自由空间法测试水溶液的介电常数并将其与使用同轴探头法的测试结果进行比较,得出同轴探头法与自由空间法的测试结果基本吻合的结论,从而验证自由空间法的准确性和此测试系统的可行性。     

自由旋涡气动窗口设计以及全流场数值模拟

为了解决低腔压大功率气体激光器传统固体输出窗口的热吸收问题,多采用自由旋涡气动窗口替代传统固体输出镜的方法。通常,自由旋涡气动窗口的设计采用无粘特征线方法结合经验修正．扩压段的设计采用理论分析结合经验的方法。基于对气动窗口整个流场的数值模拟来设计气动窗口的研究还不太完善,利用超声速自由旋涡流动结构并结合数值模拟的方法．设计了自由旋涡气动窗口,用数值模拟的方法得到了较理想的扩压段宽度和位置,最后对气动窗口全流场进行了模拟,结果表明自由旋涡气动窗口的设计是可行的。     

Extraction method for polycrystalline TFT above and below threshold model parameters

A procedure is presented to extract above and sub-threshold model parameters in polysilicon TFTs. It is based on the integration of the experimental data current, which has the advantage of reducing the effects of experimental noise. This method is applied to the linear and saturation regions for the above-threshold regime and allows the extraction of all the above-threshold and sub-threshold parameters. We already presented a unified extraction method for the above threshold parameters of a-Si:H and polysilicon TFTs, where the above-threshold regime the mobility is modeled as a function of the gate voltage to a power. An integration procedure is used to extract the device model parameters. In this paper, we complete the extraction procedure to cover all the device operation regions, that is the sub-threshold and above-threshold regimes. The extraction procedure provides in addition the possibility of monitoring the crystallization process of a-Si:H TFTs into polysilicon, which has become a widely used process of fabricating low temperature polysilicon TFTs. The process of polycrystallization manifests itself by a variation and change in sign of one of the model parameters. Extracted parameters can be correlated to input parameters required by AIM-Spice circuit simulator for device modeling. The accuracy of the simulated curves using the extracted parameters is verified with measurements.     

Effect of geometric dimensions on thermoelectric and mechanical performance for Mg2Si-based thermoelectric unicouple

The generating efficiency of thermoelectric generation (TEG) depends not only on the thermoelectric (TE) performance of TE device, but also on its mechanical performance. And choosing suitable TE materials and geometric dimension can improve the working performance of TE device. Mg₂Si is one of the most promising TE materials in the medium temperature range, and Mg₂Si-based TE devices have broad application prospects. In this paper, a three-dimensional finite model of the Mg₂Si-based TE unicouple used for recovering vehicle exhaust waste heat is constructed for the performance analysis. The TE performance and mechanical performance of the Mg₂Si-based TE unicouple under the influence of different geometric dimensions are investigated, respectively. The curves of the output power, the power conversion efficiency and the thermal stress distribution varying with different geometric dimensions are discussed in detail. The calculated result would be helpful for further understanding of the TE and mechanical properties of the Mg₂Si-based TE unicouple, and it can also provide guidance for further strength check and optimum geometric design of TE unicouples in general.     

193nm光刻投影物镜单镜支撑仿真分析及实验研究

光刻是大规模集成电路制造过程中最为关键的工艺,光刻的分辨力主要取决于光刻投影物镜的光学性能。光刻投影物镜光学元件面形精度为纳米量级,其对光学元件的加工及物镜单镜支撑提出了极高的要求。为193nm光刻投影物镜高精度的单镜面形,设计了一种运动学单镜支撑结构。运用有限元法(FEM)分析光刻投影物镜单镜运动学支撑结构在重力下物镜镜片的面形变化量,经分析物镜镜片的峰值(PV)值为15.46nm,均方根(RMS)误差为3.62nm。为了验证有限元计算精度,建立了可去除参考面面形及被测面原始面形的方法。经过分析对比,仿真结果与实验结果面形的PV值为2.356nm,RMS误差为0.357nm。研究结果表明,所设计的基于运动学193nm光刻投影物镜单镜支撑结构能够满足193nm光刻投影物镜系统对于物镜机械支撑结构的要求。     

Experimental behavior evaluation of series and parallel connected constant phase elements

Fractional-order capacitors are the core building blocks for implementing fractional-order circuits. Due to the absence of their commercial availability, they can be approximated through appropriately configured passive or active integer-order element topologies. Such a topology, constructed using Operational Transconductance Amplifiers (OTAs) and capacitors has been implemented in monolithic form through the AMS 0.35 μm CMOS process, and the fabricated chips are employed here for the experimental evaluation of the behavior of networks constructed from fractional-order capacitors connected in series or in parallel.     

Finite element method investigation into nanoimprinting of aluminum/polyimide bi-layer substrates

Finite element method (FEM) simulations are performed to investigate the nanoimprinting of aluminum/polyimide bi-layer substrates at temperatures ranging from 25 to 200 °C. In constructing the FE analysis model, the mechanical properties of the aluminum and polyimide layers are obtained from thermo-mechanical micro-force tensile tests. The validity of the FE model is confirmed by comparing the results obtained for the formation height ratio in single-layer aluminum substrates with the experimental results. Thereafter, simulations are performed to investigate the effects of the aluminum-to-polyimide thickness ratio and the substrate temperature on the imprint pressure required to obtain a complete filling of the mold cavities. The simulation results show that under low temperature conditions (i.e. <100 °C), the imprint pressure reduces as the aluminum-to-polyimide thickness ratio decreases. In addition, for temperatures lower than 100 °C, the use of a polyimide layer reduces the imprinting force by around 38% compared to that required to imprint a single-layer aluminum substrate of an equivalent total thickness. However, for temperatures higher than 150 °C and a polyimide-to-substrate thickness ratio of more than 40%, the imprint force reversely enlarged due to the strain-hardening of the polyimide film at elevated temperatures. The simulation results obtained for the variation of the imprint pressure with the aluminum thickness ratio, the polyimide thickness ratio, and the substrate temperature are compiled in the form of a contour chart. The chart provides a convenient means of establishing suitable processing conditions for a variety of nanoimprinting applications.