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     

The use of optical time domain reflectometers to measureradiation-induced losses in optical fibers

Fiber-optics exposed to ionising radiation suffer from induced transmission loss from which recovery can take place over periods up to years after exposure. Measurement of this behavior presents difficulties over the longer times, but is necessary to permit predictions of fiber behavior in applications where long-term exposure to ionising radiation is involved, as in reactor environments, medical applications, space or accelerator instrumentation. This paper presents a summary of a study by a number of laboratories of the NATO Panel IV, Research Study Group 12 Nuclear Effects Task Group into the suitability of the use of optical time domain reflectometry for these measurements. Results are shown which validate this approach when used according to recommended guidelines     

The use of laminate multichip modules for the packaging of 9-GHzdigital multichip circuits

An investigation of the high-frequency performance of laminate multichip module (MCM-L) technology was undertaken with the goal of demonstrating its appropriateness for the development of digital radar receivers operating in the X band (8 to 12 GHz). A seven-chip circuit using digital components on a Gore MCM-L was successfully tested up to 9.6 GHz. An analog-to-digital converter on an MCM-L was successfully tested up to 6 GHz. An extensive characterization of the MCM-L technology using both simulations and measurements was performed to formulate a set of design guidelines for high-frequency applications. A novel dielectric-encapsulated MCM-to-MCM interconnect scheme was proposed and tested     

Applications of superconductivity to packaging

The properties of superconductors are reviewed, and the potential applications of high-temperature superconductors to interconnect technology are examined. Comparison with interconnects composed of normal metals is made. The effect of source and load impedances on both types of interconnect is discussed. Examples are presented in which the use of superconductors can significantly improve digital systems; however, they involve much more than the simple substitution of superconductors for copper. Modeling results show that if all copper interconnects in the ETA-10 liquid nitrogen supercomputer were replaced by superconductors, the computer would not run any faster. It is argued that imaginative use of superconductors will eventually have a major impact on digital systems, nevertheless. Two possibilities are the use of a superconducting ground plane and a high-bandwidth superconducting bus     

Development of bulk nanostructured copper with superior hardness for use as an interconnect material in electronic packaging

In the present study, an attempt is made to synthesize bulk nanostructured copper by optimization of compaction pressure followed by low temperature sintering (200 °C). The selection of compaction and sintering parameters was made keeping in consideration the capability of silicon wafer and temperatures encountered during electronic packaging, respectively. The results revealed that grain size and porosity reduces while microhardness increases with an increase in compaction pressure. The microhardness obtained at limiting 1 GPa pressure was found to be superior when compared to the published values in open literature.     

Materials for high-density electronic packaging and interconnections in the higher packaging levels

This paper concentrates on the materials requirements anticipated for future packaging strategies of electronic components beyond the 1st level package. This includes Wafer Scale Integration (Level 0), hybrid assembly of bare chips in multichip modules (Level 1.5), printed wiring board (PWB) assembly, including surface mount (Level 2), and higher levels (connectors, mother boards, and cables). Furthermore, high-performance digital VLSI logic packaging only is addressed, to the exclusion of memory, analog, and power circuitry (except power supplies).     

基于热瞬态测试方法的楔形锁紧条热阻测试

楔形锁紧条是LRM模块中重要的结构件及传热部件。为了测量楔形锁紧条的热阻,通过使用热瞬态测试方法,采用冷板测试夹具,利用T3ster热测试仪结合其分析软件,测量了一类锁紧条在不同锁紧力矩下的接触热阻;同时根据锁紧条热阻的串并联关系,通过实验设置,使锁紧条一侧绝热,从而分别测得了锁紧条的两个单侧热阻;实验表明模块锁紧条侧的热阻较大,其传热量只占总传热量的30%左右,所测锁紧条在20cNm-60cNm的锁紧力矩范围内,接触热阻数值变化范围在0.44-0.33K/W。实验测试结果为仿真分析中准确设定锁紧条的热阻的位置、大小提供了参考。     

日本微电子和光电子工业中激光组装技术的应用及展望

本文综述了激光组装技术在日本微电子和光电子工业中的应用及发展前景。目前日本已开发出各种激光器和材料加工技术，并已应用于电子和光电子器件制造业，以满足用户对高性能、轻量化、低能耗移动式数字消费电子产品、宽带光纤通信、低尾气排放效能的灵活控制的小汽车等领域的需求。本文重点阐述固体激光器作为多用途光源在组装具有小特征尺寸的灵敏无源和有源器件的先进微型装置中的应用，以及固体激光器用于电子和光电子器件材料加工领域的代表性应用，如液晶显示器缺陷的调修、功能组件微调、光电子器件光学特性的精调、高密度互连电路的打孔、非晶硅太阳能电池的激光加工以及电子元件的高精度激光焊接(如光学模块、微型继电器和锂离子电池)。最近高功率超短脉冲固体激光器领域的进展使激光加工能力迅速提高．如在滤光片精调中的应用。     

Ni/Cu electroplating,a worthwhile alternative to use instead of Ag screen-printed front side metallization of conventional solar cells

For commercial purposes, it is necessary to manufacture high-efficiency and low-cost solar cells using simple processes. The front contact formation is one of the most critical steps in solar cell processing. Although silver paste screen-printed solar cells are the most widespread on the photovoltaic market, their efficiency is strongly limited as a result of shading and resistive losses, or more precisely the high contact resistance. Cu metallization for crystalline Si solar cells has attracted much attention as an alternative to the screen-printing technology. The low-cost Ni/Cu metal contact is regarded as the next generation of metallization processes to still improve the efficiency with a low specific contact resistance; it is formed using low-cost electroless plating and electroplating. A diffusion barrier should be placed between Cu and Si, to prevent Cu diffusion. Ni is shown to be an adequate barrier to Cu diffusion. For these reasons, geometry optimization of metal contacts of the front face, deposited by commercial processes, is investigated in this paper, in order to improve the spectral response of conventional multicrystalline mc-Si silicon solar cells. Their efficiency variation is analyzed as a function of changes in cell parameters (finger separation distance, height and width of finger, sheet resistance emitter...) using simulation programs in MATLAB, using contours to represent the efficiency evolution in terms of two variables. Efficiency gain of more than 0.7% has been achieved in this study. The simulation results were then compared with experimental data in order to be validated.     

电镀填孔影响因素分析

现有的HDI和IC基板的芯层填通孔方法是一个基于在已敷形的通孔的金属化与整平后,用环氧树脂进行机械填充,及在随后附加介质层积层之前形成一层铜涂覆层的多步流程。新的填通孔技术消除了填充,整平和封装步骤的分离,缩短了电路板制造的流程。讨论了对于一系列基板厚度和孔径的铜通孔填充性能随化学参数,工艺变量和电镀设备设计的变化进行了透析。     

印制线路板电镀均匀性概述

电镀生产实践中,电镀均匀性是检验镀层质量的一个重要指标。本文总结归纳了对表面及孔内镀铜均匀性进行改善的一般性思路与方法,并结合应用实例进行了说明,以期对实际生产提供一定的借鉴与指导意义。     

微电子封装的现状及发展

一、前言目前微电子产业已逐渐演变为设计、制造和封装三个相对独立的产业。由于微电子封装业相对于其它两个产业要求投资少、技术低、劳动力密集、厂房大、投资收益快等特点，因此正在我国迅速发展。二、微电子技术推动封装的发展微电子技术的迅猛发展，集成电路复杂度的增加一个电子系统的大部分功能都可集成在一个单芯片内（即片上系统），这就相应的要求微电子封装具有更高的性能、更多的引线、更密的内连线、更小的尺寸或更大的芯片腔、更大的热耗散能力、更好的电性能、更高的可靠性、更低的单个引线成本等根据美国半导体工业协会等所…     

Mean time to lose lock for the “Langevin”-typedelay-locked loop

The classical result of Kramers (1940), originally related to chemical reaction rates, is applied in this letter to a second-order all-pole, coherent code tracking delay-locked loop (DLL). A very simple, explicit expression for the leading order term of the mean time to lose lock (MTLL) is presented. The dependence of the MTLL on the loop tension (offset) due to Doppler shift and code clock mismatch is given, and optimal loop parameters which minimize the MTLL are proposed     

Reliability of industrial packaging for microsystems

Packaging concepts for silicon-based micromachined sensors exposed to harsh environments are explored. By exposing the sensors directly to the media and applying protection at the wafer level the packaging and assembly will be simplified as compared to conventional methods of fabrication.Protective coatings of amorphous silicon carbide and tantalum oxide are suitable candidates with etch rates below 0.1 Å/h in aqueous solutions with pH 11 at temperatures up to 140°C. Si-Ta-N films exhibit etch rates around 1 Å/h. Parylene C coatings did not etch but peeled off after extended exposure times at elevated temperatures. The best diamond-like carbon films we tested did not etch, but delaminated due to local penetration of the etchants.Several glue types were investigated for chip mounting of the sensors. Hard epoxies, such as Epotek H77, on the one hand exhibit high bond strength and least degradation and leakage, but on the other hand introduce large sensor output drift with temperature changes. Softening of the Epo-tek H77 was observed at 70°C.An industrially attractive thin-film anodic silicon-to-silicon wafer bonding process was developed. Glass layers are deposited at 20 nm/s (1.2 μm/min) by electron-beam evaporation and bond strengths in excess of 25 N/mm² are obtained for bonding temperatures higher than 300°C.Through-hole electrical feedthroughs with a minimum line width of 20μm and a density of 250 wires per cm were obtained by applying electro-depositable photo-resist. Hermetically sealed feedthroughs were obtained using glass frits, which withstand pressures of 4000 bar.     

Development of packaging technologies for microsystems

It is well known that packaging plays a very important role in developing microsystems. Packaging accounts for about 60%～80% of cost and function of a microsystem. Package is required to provide mechanical protection, media separation or coupling, signal conditioning, etc.     

Development of packaging technologies for microsystems

［1］ESASHI M. MEMS packaging and assembly[A]. Pacific Rim Workshop on Transducers and Micro/Nano Technology[C]. Xiamen, China, 2002, 1-10. ［2］TAKIZAWA T, YAMAMOTO S, ITOI K, et al. Conductive interconnection through thick silicon substrates for 3D packaging[A]. MEMS 2002 Technical Digest of 15th IEEE Int Conf on Micro Electro Mechanical Systems[C]. Las Vegas, USA, 388-391. ［3］WANG Z.F, CAO W, ARULVANAN P, et al. Packaging of a fiber optical MEMS switch[A]. Proc. of 4th Electronics Packaging Technology Conf[C]. Singapore, 2002, 96-100. ［4］NAJAFI K. Micropackaging technologies for integrated Microsystems[A]. Proc of SPIE[C]. San Jose, CA. USA, 2003,Vol. 4979, 1-19.     

锁相同步技术在不间断电源中应用的几个问题

本文研究了三种相位反馈控制方案,讨论了它们应用的条件和应注意的问题。实验结果对进一步改进UPS电源的性能有实际价值。     

船闸闸门底枢的结构仿真

闸门是水工建筑物中的重要组成部分,是活动的挡水装置,用以调节流量、控制水位、保证工程效益的发挥。闸门形式的选定,将直接关系到水工建筑物的结构形式。闸门底枢是人字闸门、三角闸门中重要的支承运转部件,起到支撑闸门构件的作用,以及作为叶门旋转中心轴。底枢是人字闸门中最容易发生故障的部件,因而需对其进行详细的分析设计和结构仿真。     

汽车万向节电镀锌螺栓断裂的原因分析

汽车万向节紧固螺栓（以后简称螺栓）在镀锌处理后机械性能下降，在试运行过程中就已断裂。为探讨镀锌螺栓断裂的原因，对断裂螺栓进行了测试分析。