软钎焊接头质量实时检测与控制方法研究

本文设计了利用焊点红外辐射的激光软钎焊质量检测及控制的试验装置。以热释电元件作为红外探测器,研制了分离式的加热—探测光学单元。试验结果表明,软钎焊过程中焊点的红外辐射信号中包含了有效的焊点上钎料加热、熔化的信息,经计算机处理及反馈控制,初步实现了对激光软钎焊焊点质量的实时检测及控制     

计算机在激光红外焊点检测仪中的应用

计算机在激光红外焊点检测仪中的应用宋佩英，唐开元，吴志林，蔡凤群（上海市激光技术研究所，２００２３３）激光红外焊点检测仪，在电子工业自动化生产过程中用于印制板焊点的质量检测及监控锡焊工艺，具有重复精度高、测量迅速、操作方便等优点。激光红外焊点检测仪中...     

SMT激光软针焊焊点质量实时检测系统的研究

本文通过对ＳＭＴ激光软钎焊焊接接头形成过程的分析，研制出焊点质量实时检测系统，系统同样实用于ＳＭＴ焊点焊后质量检测。     

SMT激光软钎焊焊点质量实时检测系统的研究

本文通过对ＳＭＴ激光软钎焊焊接接头形成过程的分析，研制出焊点质量实时检测系统，系统同样实用于ＳＭＴ焊点焊后质量检测。     

激光／红外法SMT软钎焊接头缺陷检测

利用自行研制的激光／红外质量检测系统对激光／红外辐射响应方法检测存在于ＳＭＴ接头中的种种缺陷的可行性进行了研究，结果表明激光／红外信号能够很好地反映焊点钎料的多少、焊点表面的状态等影响接头质量的因素。分析了对应不同缺陷的红外辐射信号特征，通过建立焊点缺陷－红外辐射之间关系的数据库，初步实现了ＳＭＴ焊点的质量检测。     

跨接片激光软钎焊工艺技术研究

跨接片能够解决异质材料热失配的问题，因此被广泛地应用于微波组件中射频信号的连续传输。针对微波组件用跨接片激光软钎焊工艺开展研究，优化了焊膏涂覆方式和激光焊接的工艺流程，对比分析了跨接片激光软钎焊和手工焊接的焊点力学性能及微观组织，并开展了温度循环试验。结果表明：相比跨接片手工焊接的方式，激光焊接的焊点剪切力平均值更大、标准差更小；从微观组织可以看出跨接片采用激光软钎焊焊点的金属间化合物厚度均匀且连续，符合标准要求。按照某型雷达产品环境应力筛选规范开展跨接片温度循环加严试验，试验后焊点无缺陷，符合产品要求。     

彩电合格焊点及其激光检测

激光／红外印制电路板焊点检测系统，是８０年代中期出现的世界上最先进的焊点质量检测手段，其检测速度、检测精度、检测可靠性和重复性、自动化程度，都是人工目视等其它方法远远不可比拟的。笔者对大量试验结果进行分析，可以认为：焊点激光红外检测数据、润湿角大小、焊点外形及抗拉强度数值、焊料重量值和合金层，可以作为判断焊点合格与否的标准。     

SMT激光软钎焊自动焊接系统的研究

本文研制成功激光软钎焊焊点示教系统，并且实现了激光器电源的计算机控制，能对激光输出功率和加热时间进行精密调节。同时，对几种典型元件的激光软钎焊工艺规范进行了探索。     

彩电焊点激光检测阈值标准

激光／红外焊点质量检测系统，是目前国际上最先进的无损检测方法，它比传统的目测法有诸多技术优势：速度快、可靠性高、重复性好，并且是检测高密度的ＳＭＴ小焊点的最佳方法。上海电视一厂和上海激光所合作研制成功国内第一台焊点激光检测系统，由激光注入部分、Ｘ－Ｙ二维平台、红外探测器和计算机系统组成。经过较长时间实测（从流水线上直接取样），获得５３万个数据，制订出了彩电基板合格焊点的红外信号阈值标准。     

红外技术在印制电路板焊点质量检测中的应用

印刷电路板焊点质量的激光红外自动检测技术是红外技术在无损检测领域的一个十分成功的应用,具有良好的经济效益和社会效益。本文说明了激光红外焊点自动检测系统出现的必然性,较详细地介绍了该系统的工作原理、应用情况以及最新进展。     

电子装联三维结构垂直线和面印刷及回流焊工艺研究

在电子装联领域,焊点通常都位于PCB平面。然而,随着散热、信号屏蔽等要求越来越高,器件及通路的分散性要求焊点能够在三维结构上延伸,从而形成了三维结构的焊点。在回流焊时,垂直(Z轴)方向上的焊料必然要受到重力的影响,特别是在要求连续的线、面焊接时,控制焊料的向下流动是保证焊接质量的难点。针对这一问题,从焊膏性能、印刷工艺和回流工艺三个方面进行分析和实验,不仅获得了连续均匀焊点,而且达到了批量印刷、单次回流的工艺要求,同时减少了器件的热冲击次数。     

The effect of soldering process variables on the microstructure and mechanical properties of eutectic Sn-Ag/Cu solder joints

Fundamental understanding of the relationship among process, microstructure, and mechanical properties is essential to solder alloy design, soldering process development, and joint reliability prediction and optimization. This research focused on the process-structure-property relationship in eutectic Sn-Ag/Cu solder joints. As a Pb-free alternative, eutectic Sn-Ag solder offers enhanced mechanical properties, good wettability on Cu and Cu alloys, and the potential for a broader range of application compared to eutectic Sn-Pb solder. The relationship between soldering process parameters (soldering temperature, reflow time, and cooling rate) and joint microstructure was studied systemati-cally. Microhardness, tensile shear strength, and shear creep strength were measured and the relationship between the joint microstructures and mechani-cal properties was determined. Based on these results, low soldering tempera-tures, fast cooling rates, and short reflow times are suggested for producing joints with the best shear strength, ductility, and creep resistance.     

Microstructure evolution of eutectic Sn-Ag solder joints

Laser and infrared reflow soldering methods were used to make Sn-Ag eutectic solder joints for surface-mount components on printed wiring boards. The microstructures of the joints were evaluated and related to process parameters. Aging tests were conducted on these joints for times up to 300 days and at temperature up to 190°C. The evolution of microstructure during aging was examined. The results showed that Sn-Ag solder microstructure is unstable at high temperature, and microstructural evolution can cause solder joint failure. Cu-Sn intermetallics in the solder and at copper-solder interfaces played an important role in both the microstructure evolution and failure of solder joints. Void and crack formation in the aged joints was also observed.     

倒装焊器件返修工艺

在焊接过程中,返修工作始终是其必不可少的一个组成部分.根据多年来SMT生产实践经验,针对目前倒装焊器件的种类,简单介绍了FC器件焊接故障定位的三种方式及加热焊接设备再流焊炉、返修台、热风枪的选用原则,详细介绍了倒装焊器件重新加热、拆植焊、拆焊、特殊返修四种返修工艺方法,可供有关人员参考.     

SMT激光软钎焊质量监测方法研究

本文作者研究了一种激光软钎焊接合部质量的实时监测方法,这一方法利用加热过程中接合材料之间的热电势与接合界面温度之间的对应关系,并根据有效加热热量(在阈值以上界面温度对加热时间的积分)与接合面积之间的规律,实时监测接合质量。实验结果表明,在软钎焊温度范围内,接合材料间热电势与界面温度之间具有良好的线性关系;实测有效加热热量充分地表现了接合部被加热及钎料的熔化情况,可以作为监测或控制激光软钎焊接合质量的参数。     

埋头焊接的可靠性

埋头焊接是针对通孔插装元器件的一种特殊焊接方法.介绍了埋头焊接的优点,通过UG软件建立了电路板和焊点的三维有限元模型,利用焊点在近似试验载荷条件下的应力应变三维有限元数值模拟,就"先剪后焊"埋头焊接方法形成的焊点和普通焊点强度做了对比,给出了焊点的应力变化,并结合振动分析试验、温度循环试验和基于2D图像的X射线检测和分析,证明了埋头焊接方法应用的可行性.     

PBGA器件焊点的可靠性分析研究

根据PBGA器件组装特点,分析了器件焊点的失效机理,并针对实际应用中失效的PBGA器件在温度循环前后,分别使用染色试验、切片分析、X-射线分析等方法进行失效分析.分析结果显示样品PBGA焊点存在不同程度的焊接问题,并且焊接质量的好坏直接影响器件焊点抵抗外界应变应力的能力.最后,开展了PBGA器件焊接工艺研究和可靠性试验,试验结果显示焊接工艺改进后焊点的可靠性良好.     

回流焊对SnAgCu焊点IMC及剪切强度的影响

研究了回流焊次数对Sn-0.3Ag-0.7Cu-xNi/Cu(x=0,0.05)焊点的界面反应及其剪切强度的影响。结果表明:随着回流焊次数的增加,界面金属间化合物(IMC)Cu6Sn5和(Cu1-xNix)6Sn5的厚度均增加。在钎料中添加w(Ni)为0.05%,可有效抑制IMC的生长,与回流焊次数无关。回流焊次数对Sn-0.3Ag-0.7Cu/Cu和Sn-0.3Ag-0.7Cu-0.05Ni/Cu的剪切强度影响都不大,五次回流焊后剪切强度略有下降,剪切强度分别为21MPa和25MPa。发现断裂面部分在钎料中,部分在钎料和IMC之间。     

Eddy Current Induced Heating for the Solder Reflow of Area Array Packages

This paper presents a feasibility study of using eddy current induced heating for the solder reflow of area array packages. With a high frequency electromagnetic field, Sn 3.5% Ag lead-free solder balls were heated to melt and wet the solder pads on an organic substrate. The experimental results showed that such a solder reflow process could be implemented effectively in a wide processing window. With an infrared temperature sensor, it was found that the temperature difference between the solder balls and the FR4 board might reach 80 , indicating a rather localized heating mechanism. In addition, the heating and cooling rates during the soldering were found very high. This is another feature of the induction heating reflow process. It was also found that the generated temperature in the solder balls would depend on the size of the solder balls. This characteristic may be used to perform selective soldering of flip chip BGA packages. Furthermore, the developed soldering process was applied to the board level reflow of actual components. The result verified that the induction heating reflow is a feasible soldering process in actual applications.     

Solder connections for high frequency applications between flexible and rigid printed circuit boards

This article examines the backplane connector technology for high frequency use and presents a novel concept for shielded enclosures without air vents. The experimental soldering of connections between a flexible printed circuit (flex, for short) and a FR4-board as part of a backplane connector is presented. A very high contact density is reached by soldering vias on the flex to pads on the FR4; this soldering was performed both with ordinary Sn/Pb solder material and as well with lead-free solder alloy. The solder joints were examined using a scanning electron microscope (SEM) and the electrical properties of the flex/solder joint structure were measured.