无焊绕接工艺技术及其应用

介绍在电力电子设备行业为了实现电气连接牢固耐久,抗老化和耐腐蚀,而使用的无焊绕接技术,详细论述了绕接技术的工具选用、工艺过程、绕接点的检验、合格判据,并将绕接技术与传统的锡焊技术进行了比较,指出了绕接技术的优点及应用前景.     

电子信息

△通信配线架系列产品 国营4404厂最近研制成JPX80D型系列产品,并参加’96武汉国际通信展示会深受用户好评。1)JPX80、83型总配线架系列。采用国际先进的绝缘层位移气密性卡接技术和小型化、功能全的保安单元,以及卡接、绕接通用结构的铝合金型材机架;2)FA9保安单元。双接点卡接式30型保     

压接连接工艺技术研究

介绍了压接连接技术的概念和特点,比较了压接连接与锡焊连接的特点及优势;对电子产品中常用的各种冷压端子进行了归类,介绍了闭合压线筒端子、开式压线筒端子的压接方法、工艺技术要求及检验标准;总结了压接工艺中导线的选用与处理方法、工具的使用及要求以及导线端头的处理等通用工艺。     

插针线缆压接工艺技术

文章介绍了插针压接工艺过程的技术要求及质量分析,提出了检验压接的基本方法。     

四继电器接点网络设计九例

设计继电器接点网络时,一般要求尽量少用继电器的接点、簧片.Moore设计四继电器接点网络402 例,力求用最少接点、簧片.后来Ninomiya也进行设计,比Moore少用簧片的有31例.他们设计的网络可以进一步简省.经改进,少用接点的有2例,少用簧片的有7例,现列于表1.其中图3的接点、簧片数(12/18)及图8的接点数11都是最低值,不能再减     

微电子文摘

在物理设计过程中,进行精细布线前,希望对基于网线上接点界盒的互连延迟、每一长度的电容-电阻之水平垂直估算值限界,还希望根据限界盒内和限界盒上的接点之位置估算出接点-接点间的延迟。假定互连线将基于直线斯坦尼树(RST)进行布线,F.K.Chung和F.H.Hwang的研究工作(1979)被用来限界给出线网上限界盒的可能最大/最小RST(这适合于≤10个接点的线网或接点数为二次幂的大量接点的线网)。于是发现,对一个线网来说,Elmore延迟表达式包括两部份:即输出驱动电阻和总线网函数项以及线网拓朴学函数项(最终RC互连树的电阻特性)。这样,便推导出RC互连延迟的界限。利用内部线网接点位置及其知识,就把接点与RC树的输出和     

红外导引头中胶接技术的应用

随着科学技术的飞跃发展，胶接技术在工业、农业及军事工业中得到了广泛的应用。目前，据有关资料报道，各种胶合材料品种达万种以上，产量达千万吨数量级。具有应用广、成本低、操作简便、工艺性好等多种优点。本文介绍集先学、电子、精密机械于一体的红外导引头中、胶接的特点、要求及应用。结合红外导引头的研制，介绍几种胶合的方法。由于选用较为得当，经过试验表明，符合要求。建议可推广其在导引头中应用，促进胶接技术发展。     

大规模电缆终端的超声波卷缩处理

Sonic Connections公司(Walpole,MA)已经发展了一门电缆终端技术:采用超声波能量用于时间和劳力密集的隔离变位连接或焊接。这门技术被称为声波卷缩,该技术尚未获得专利。它可以在超声波焊接过程中对多接点和导线进行机械压接。     

双路电源自动切换的应用

淅川有线电视台采用双路不同变压器电源进入机房 ,来改变机房单路供电时因停电、停播而造成用户看不到电视的故障。开始为人工切换 ,麻烦很大 ,可靠度不高。为此 ,将双路电源改造为自动切换系统 ,应用良好 ,具体方案如下。1　器材(1) 2 2 0Ｖ/2 0Ａ交流继电器 2只 ;(2 )多股铜电源线。2　实施方案(1)将进入机房的双路电源 ,按平时停电次数多、少分为主、备电源 ,2只交流继电器也分为主、备继电器。(2 )具体连接方法①主电源接入主交流继电器的进线接点并接牢 ,同时引 2根线到本交流继电器的线圈接点并接牢 ,负载输出线接入主输出接点。②备…     

光纤环绕制的实现技术

光纤陀螺的应用对光纤环的绕制提出了更高的要求，为满足工程化的需求，本文就光纤环四级绕法的实现技术和方法进行了研究。     

Major factors to the solder joint strength of ENIG layer in FC BGA package

Since electroless nickel and immersion gold (ENIG) process was implemented as the surface finish of printed circuit board (PCB) substrate, there have been lots of reports on the brittle fracture between the Ni–P (phosphorous) layer and solder which results in the poor solder joint strength performance. Galvanic corrosion during immersion Au plating process and P-content in Ni–P layer were considered as major factors in the solder joint strength of ENIG layer in this investigation. The attempt to reduce the galvanic corrosion attack in Ni–P layer was made by changing immersion Au plating process to partial electroless Au plating process. Reducing the galvanic corrosion attack was proved to be effective to improve the solder joint strength of ENIG layer. Evaluation of the solder joint performances in variation with the thickness of the Ni layer leads to the conclusion that the thicker Ni layer has the better solder joint strength performances. The result also showed that higher P-content in Ni layer is more favorable to the solder joint strength.     

Mechanisms and solutions to the brittle solder joint in electroless Ni plating

Brittle solder joints in Electroless Ni electroless Pd immersion Au (ENEPIG) surface finishes are one of the key reliability issues in electronics assembly. Previous characterization of the reflow process has indicated that interfacial voids formed after solder reflow are responsible for the decreases in solder joint strength. However, the mechanisms behind the formation of these voids in the ENEPIG process remain unclear. In this paper, the interaction between various aspects of the ENEPIG process and solder joint strength were investigated. Surface roughness, morphology, and nano-pitting at the interface between electroless Pd and Ni-P were characterized. The size and density of nano voids inside Ni₂SnP were measured after the specimens were reflowed with Sn4Ag0·5Cu solder ball. Additionally, high speed shear solder joint strength measurements were made. The results indicated that anion adhesion induced nano-pitting at the interface between the Ni₂SnP intermetallic and Pd, resulting in the formation of a nano void layer during reflow. These interfacial voids lead to lower solder joint strength. Based on the results, a solution to prevent the brittle solder joint failures is suggested.     

铝钛异种合金的激光熔钎焊

提出了一种连接Al/Ti异种合金的新工艺，即采用激光为热源，AlSi12为填充材料，实现了Ti-6Al-4V钛合金和LF6铝合金的激光熔钎焊连接。激光熔钎焊是一种局部加热焊接过程，通过调整激光加热参数，控制填充材料的润湿铺展及界面金属间化合物的形态和数量，从而控制接头质量。在实验过程中，填充焊丝实时送入，通过改变激光功率、间隙大小、光斑尺寸、焊接速度、送丝速度、激光辐照位置等工艺参数，以获得对接头的不同加热效果。研究了不同参数下的钎缝成形规律、接头界面特点及接头拉伸强度。结果表明，采用激光熔钎焊工艺连接Al/Ti异种合金可以获得成形良好、强度较高的接头，但焊接过程对工艺参数要求严格;接头厚度方向不同位置的界面金属间化合物的厚度和形态各不相同;热输入较低情况下，钎料与钛合金材料作用不充分，接头易从界面处断裂;热输入较高时，接头容易从铝合金侧熔合区附近断裂。     

工艺参数对铍青铜微电阻点焊质量的影响

改变焊接电流、焊件表面粗糙度及电极端面直径,对铍青铜微电阻点焊进行了研究,分析了工艺参数对接头拉剪力和焊核直径的影响.结果表明:电极端面直径为3.2 mm时获得的接头性能最好.随着电极端面直径的减小,接头性能降低.表面粗糙度较小时,获得的接头性能较好, 当表面粗糙度增加到某一值后,其对接头性能的影响不明显.     

嵌入式数字视频监控系统中的媒体存储研究

基于目前较流行的嵌入式数字视频监控系统,提出了一种媒体存储的策略。该策略通过设计双缓冲媒体流算法、设计硬盘预分配空间和连续文件存储、多路存储轮转式调度算法以及媒体信息索引等,在较高的媒体编码数据量下,实现了不丢帧的稳定存储,并能快速而准确地检索,清晰流畅地回放历史视频。在长时间的测试中验证了该存储策略的实用性和可靠性。     

钎料熔滴键合接头的成型过程与微观组织特征

本文利用钎料熔滴键合方法实现了传感器与基板焊盘之间的互连，对这种工艺下的接头形态、接头的形成过程及微观组织特征进行了研究。结果表明，熔滴的初始温度是影响焊点形态的关键因素，只有当初始温度达到一定值时才能形成完整焊点；润湿铺展过程中，熔滴接触焊盘的瞬间将发生扁平变形，随后扁平端的回收将促进润湿铺展的进行，另外，两侧焊盘导热条件的差异使得两侧润湿铺展过程异步进行；钎料熔滴能够利用其自身携带的热量与两侧焊盘形成良好的冶金结合，界面反应充分，同时快速的凝固条件使得接头微觋细织细小，均匀。     

Development of system specification for laser-optimized 50-/spl mu/m multimode fiber for multigigabit short-wavelength LANs

This paper presents the scientific arguments used in the specification development process by the Telecommunications Industry Association (TIA) Working Group FO-2.2.1 to develop the new multimode fiber and vertical-cavity surface-emitting laser specifications for high-speed application in data communications. Numerous engineering and commercial tradeoffs are described. The specification minimizes the link failure rate and overall link cost through utilization of communication-theory-based modeling and experimental verification. This was balanced against the reality of manufacturing costs attempting to maximize the yield of individual link components. The specific application used as an example has 50-/spl mu/m graded-index multimode fiber operating at 10 Gb/s (e.g., 10 Gb/s Ethernet and fiber channel). The link performance is determined by the interaction of the fiber intermodal dispersion measured by the differential modal delay, and the transceiver launch distribution into the multimode fiber measured by encircled flux. A theoretically based model and the simulation approach that were used to simulate 40 000 links are described. The information from these simulations was used to determine the specification limits. In addition, sensitivity to the specification limits was evaluated. The experimental results of a round robin conducted by the TIA are presented, which confirm that the modeled performance would yield the expected results in actual practice.     

变形镁合金AZ31B的激光焊接工艺研究

本文以AZ31B变形镁合金为主要对象 ,研究镁合金的激光焊接工艺特点 ,探讨焊接工艺参数对接头组织及性能的影响。结果表明 ,激光脉宽是影响焊接接头性能的主要工艺参数 ,通过控制激光脉冲宽度可以获得高质量的镁合金焊接接头。组织观察发现镁合金激光焊接接头焊缝组织致密 ,晶粒细小 ,热影响区不明显 ;另外硬度试验显示 ,母材、热影响区、焊缝硬度相当。在本试验条件下采用YAG激光焊接工艺能够成功的实现变形镁合金AZ31B的连接 ,接头强度可达母材的 95 %。     

金属-橡胶多层粘接结构超声检测信号处理方法

针对由金属和多层橡胶胶粘而成的多层粘接结构,综述了当前用超声脉冲回波法对其检测所用到的信号处理的一般过程和方法,并分析和比较了它们的优点和不足,为超声方法应用于多层粘接结构的检测指明了方向。     

Taking the Internet to the people

This paper describes how ethnographers from Intel Corp. circled the globe from 2001 to 2005 to determine how computers are being used by typical people in different cultures. The team investigated communities in more than 10 countries in Asia, Europe, Latin America, and North Africa, visiting more than 100 homes and businesses. They observed that at the Internet outposts they visited, even the computer illiterate reap the advantages of the Web. These public Internet facilities are solving real problems, defying cookie-cutter categorizations of nonoriginality, and becoming a growing and vital force in the vast developing world.