高密度表面安装电路板的测试技术探讨

现在的表面安装电路板密度越来越高,而且引脚间距变得越来越小,这些给测试工作带来了困难。同时,又存在另外一些问题,如缺少对多引脚ASIC_s的在线测试图形、缺少探测通道等,所有这些因素都阻碍了测试工程人员实现高缺陷覆盖率的测试工作。本文讨论的是当前使用的测试技术,包括数据图形库、算法图形生成、非向量测试和边界扫描,以及这些技术的综合使用,以实现最优的缺陷覆盖。     

边界扫描器件BSDL描述在测试中的应用

在对描述器件边界扫描特性的BSDL语言进行了深入研究之后，将其应用于边界扫描自动测试图形生成ATPG与故障诊断软件中。本文以EPM7128SL84芯片为例，说明了其BSDL描述在边界扫描测试程序中的应用方法与要点。     

数字IC边界扫描互连故障诊断新方法

介绍了支持JTAG标准的数字集成电路(IC)芯片结构、故障测试模式和运用边界扫描故障测试的原理.实验中分析了数字IC互连故障类型、一般故障诊断流程和互连故障的测试方法,提出了采用无误判抗混淆算法的IC边界扫描互连故障诊断法.通过两块Xilinx 9572 pc84芯片互连电路板进行了实验验证,结果表明,该方法对板级互连故障测试具有定位准确、检测效率高、可靠性高及易于实现的技术优势.     

基于决策表的印刷电路板测试诊断过程优化

针对传统的决策树生成算法之不足,提出了两种改进算法。用实例说明改进处法具有更好的优化效果,且证明了传统算法是改进算法Ⅱ的特例。基于决策表和决策树,构造了电路板故障诊断专家系统,实现了印刷电路板测试诊断过程优化,使故障诊断的平均测试开销最小。     

边界扫描技术在含DSP电路板测试与诊断的研究与应用

针对含DSP电路板的测试与诊断问题,本文提出一种利用边界扫描技术和传统的外部输入矢量测试相结合的方法,对含DSP电路板中的边界扫描器件的器件及非边界扫描器件进行了测试.测试结果表明:该测试方法对边界扫描器件及非边界扫描器件可进行有效的故障检测和故障隔离,并可将故障隔离至最小的测试单元.同时详细阐述了测试诊断方案、硬件设...     

VLSI边界扫描测试故障诊断及其策略研究

介绍了支持JTAG标准的IC芯片结构和故障测试的4-wire串行总线,以及运用边界扫描故障诊断的原理.实验中分析了IC故障类型、一般故障诊断流程和进行扫描链本身完整性测试的方案,并提出了一种外加测试码向量生成的算法.该故障诊断策略通过两块xc9572 pc84芯片互连PCB板的实现方法进行验证,体现了该策略对于芯片故障定位准确、测试效率高、控制逻辑简便易行的优越性.     

基于决策表的CAMAC模件测试诊断过程优化

用决策表表示被测CAMAC模件的测试诊断知识。文章针对传统的决策树生成算法之不足，提出了两种改进算法。实例说明改进算法具有更好的优化效果，且证明了传统算法是改进算法二的特例。基于决策表、决策树构造了CAMAC模件电路板故障诊断专家系统，实现了CAMAC模件测试诊断过程优化，使故障诊断的平均测试开销最小。     

应用边界扫描技术提高电路板可测试性的两种优化问题

边界扫描测试技术很好地解决了VLSI电路诊断、测试的困难问题，得到了广泛的应用。作者在查阅大量文献资料的基础上．总结出了边界扫描技术在提高电路板可测试性上的两种优化问题：即设计过程中设计复杂性和测试性改善的优化，以及在测试生成算法中紧凑性与完备性优化的问题，论文详细分析了这两种问题，分析比较了相关的优化算法，并对这两种优化问题未来的发展方向进行了预测。     

基于边界扫描的板级互连测试模型研究

主要研究边界扫描技术在电路板互连测试中的应用,对互连测试的故障模型和测试方法进行优化.根据电路板制造故障的具体成因和分布情况,对基于边界扫描的板级互连测试模型进行扩展.提出以元器件焊点故障作为基本参考点,增加了网络两端发生不同故障的情况,从而总结出新的故障模型,并给出了针对新故障模型的测试方案.基于新的故障模型的测试可以更加全面地发现电路板的潜在问题,避免在生产测试中因为故障的漏判而反复维修,从而提高生产的效率.     

边界扫描测试的数学模型探讨

边界扫描测试所指的是把一定数量的数字逻辑测试向量,串行输入至被测电路板中,并按照与之相对应的向量来对电路板中所有可能会发生的故障进行诊断,这一系列的测试所构成的就是边界扫描测试向量集合。本文所研究的是建立在布尔矩阵理论上的边界扫描测试模型,提出了这一测试数学模型的形式,研究了短路故障特征矩阵的建立过程,并进行了具体的模型的运算,最后提出了改数学模型的具体应用,具有一定的现实意义。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.