灌封工艺方案与产品结构设计的匹配性研究

在高可靠微电路模块设计中,封装结构通常采用产品灌封的方式,以满足产品抗冲击振动、恶劣环境、导热、绝缘等要求。剖析了某灌封模块样品的应力失效典型案例。采用仿真与试验验证相结合的方式进行验证,提出了灌封工艺方案与产品结构设计匹配性与适宜性的研究方法。该方法为后续灌封方案与产品结构匹配性提供了理论指导和技术支持。     

某高压电源组件灌封工艺技术分析与研究

主要通过灌封工艺技术在某高压电源组件"三防"的应用与研究,从灌封工艺路线的设计、灌封材料的优选、关键工序的控制等几个方面分别进行了详尽的分析;并结合多批次实际生产的检验与研究,证明此灌封工艺完全满足产品的设计要求.     

一种先“浸”后“灌”的环氧灌封工艺

环氧树脂真空灌封工艺技术,是电子器件和组件干式密封绝缘的重要工艺技术。但在实际使用中经灌封的磁芯线圈类电子器件,由于其结构的特殊性,灌封料不能完全浸透线圈匝间内,在环境试验时,磁芯线圈电感量指标变化大,不满足技术指标。本文通过生产过程中一起电感线圈合格率低问题,开展了工艺实验,结合环氧树脂灌封和浸渍相关理论,对电感线圈灌封工艺方法进行了改进,采取对磁芯线圈先浸绝缘漆再灌封的混合工艺方法,较好的解决此问题。     

电路灌封体的失效机理分析

在面对高强冲击、剧烈振动和高低温冲击等恶劣环境时,对离线存储测试装置中电路系统运行的可靠性提出了更高的要求。为了确保电路系统在恶劣环境中的正常工作,需对存储测试装置中的电路模块进行灌封加固。利用环氧树脂对电路模块进行灌封,形成的电路灌封体在试验过程中时常会出现运行失效的现象。通过分析表明:应力集中是引起电路灌封体失效的主要因素。分析了灌封过程中导致应力集中的原因,并从灌封材料、灌封工艺以及产品设计几个方面对缓解灌封体内部应力集中的方法进行了分析和探讨。     

基于正交试验的板级电路模块热分析

利用ANSYS的APDL参数化编程语言,建立了灌封电路模块的有限元模型。选取挠性印制电路板(FPCB)厚度、上、下灌封体厚度、空气对流系数和环境温度等7个参数作为关键因素,安排正交试验。结果表明:上、下灌封体厚度等因素都对灌封电路模块工作温度有显著影响,其中空气对流系数的影响最为显著。初始设计的灌封电路模块工作温度为460.94K,通过增加灌封体的厚度,选择高热导率的灌封材料,保证良好的通风散热,控制环境温度,可以将模块的工作温度降到329.11K。     

室外LED显示模块的灌封工艺设计

文章介绍了室外LED显示模块灌封的目的和灌封工艺设计。对灌封材料和堵缝材料的选择,灌封工艺方案的确定和工艺流程的安排等方面进行了分析。另外,文章还阐述了灌封过程中容易出现的几个问题,同时提出了相应的解决方案。     

微电路模块板级磁芯组装失效机理与工艺设计

板级磁芯是国防军工及航空航天领域使用的微电路模块的重要组成部分,其组装的可靠性对产品性能起着至关重要的作用。为从根源上解决板级磁芯粘接的可靠性问题,文中通过分析板级磁芯粘接失效机理,创新性地引入可靠的磁芯粘接胶和新的灌封工艺设计,对磁芯粘接胶和灌封工艺进行针对性的探索;并采用含玻珠的新磁芯粘接胶对板级磁芯进行粘接,淘汰真空浸入式灌封而采用新的旋转灌封工艺,形成高可靠的板级磁芯组装工艺技术,彻底地解决板级磁芯粘接面开裂的问题。研究得出：板级磁芯组装失效的根源是磁芯粘接力不足以抵抗环境试验和产品内部的灌封胶应力,采用新型板级磁芯粘接胶、改进灌封方式和磁芯填充工艺是避免板级磁芯组装失效的有效工艺途径。     

小型高压变压器的固体灌封研究

根据小型单次高压脉冲变压器（以下简称高压变压器）的特殊结构和要求，提出了采用固体绝缘材料灌封替代绝缘油封的技术和工艺。在新技术和工艺指导下，固体灌封的高压变压器耐压强度达到１００ＫＶ（指脉冲电压）以上，耐温性能和综合性能也得到了提高。     

绝缘导热有机硅灌封材料的研制与应用

阐述了传统灌封材料不足之处,说明了研制绝缘导热灌封材料的目的和意义,同时着重介绍了绝缘导热有机硅灌封材料的研制、施工工艺、性能及其在我所某雷达高压发射机组件上的应用.     

大功率集成功放模块工艺研究

在各类电子产品集成度越来越高的前提下,大功率集成功放模块也同样面临着集成度不断提高的要求,如何使其效率更高、体积更小、重量更轻、成本更低、更加可靠耐用已成为大功率集成功放模块工艺研究的主要方向。文章介绍了一种大功率集成功放模块的封装结构设计及组装工艺,功率半导体模块是把若干分立器件及内部电路进行组装,然后用环氧树脂灌封而成的新型器件。它具有体积小、外壳与电极绝缘、可靠性高、安装方便等优点。在研制过程中借鉴了国外知名企业产品的工艺技术,同时也充分利用了现有成熟的半导体集成电路的封装技术。     

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.