电子元件的特征建模与检查算法研究

本文提出了一种电子元件建模与检查的算法.首先通过3CCD??包相机,红、绿、蓝三色LED结构光源获取PCB图像,图像经预处理凸显出元件的颜色特征;然后通过定位算法来实现元件的精确定位.在此基础上.提取元件的窗口位置,区域形态和逻辑等特征来实现对元件质量的检测;最后通过实验证明本算法的有效性和稳定性.     

基于图像传感器的电子元件外形缺陷检测系统

针对目前人工检测电子元件外形缺陷的不足,研究了图像处理技术,并以晶振为例,设计了基于图像传感器的电子元件外形检测系统.首先对电子元件准确定位,由CMOS图像传感器采集元件外形的图像信息,并采用全局阈值分割法,用硬件完成图像的二值化处理.单片机将得到的二值化数据逐行扫描,并进行分析与比较,以判断该元件是否存在缺陷.实验表明该方法的检测精度可达到±0.039 mm,满足测量的需求,可解决人工检测的不足.     

面向机械分拣系统的电子元件自动识别算法

为了提高电子元件机械分拣系统的效率,提出一种电子元件参数图像自动识别算法。利用矩形分割处理电子元件参数图像,通过黑、白色号标记特征修正图像灰度形态。计算图像横纵坐标、摄像机感光阵列、连接机器坐标与摄像机坐标,获得电子元件参数图像的具体坐标系。拟合坐标系内灰度值导数差值与图像像素点信息,得到元件边缘轮廓信息。凭借多项式差值拟定坐标系点集的差值,确保梯度幅值在区间中存在极大值。利用依靠梯度方向法明确元件参数图像素点大致分布,最后利用核分类器构建监督机器学习模型,引入拉格朗日乘子计算参数图像像素坐标点位置,实现图像自动识别。实验证明,该方法能够精确识别图像内的电子元件位置,且识别效率高。     

数字化阴影法测量光学元件表面面形的研究

提出了阴影检测技术的一种新型数字化方法,用于定量测量光学元件表面的局部面形误差量.在阴影测量装置后搭建数字图像提取和处理系统,运用傅里叶光学原理进行测量方法的数学建模.利用数字图像系统提取阴影检测图像,通过对阴影检测图像特征的分析重构出光学元件面形.仿真结果表明,运用该模型提取一抛物面镜的面形信息,在一维径向方向上可以达到1 λ(λ=632.8 nm)RMS的重构精度,可以满足光学元件加工粗抛光阶段测量的要求.     

交变磁场下焊接缺陷磁光成像特征分析

研究焊接缺陷磁光成像检测方法,基于法拉第旋转效应,分析交变磁场下焊接缺陷磁光成像特征与漏磁场之间的关系。建立焊接缺陷的三维有限元模型,对不同类型和宽度的焊接缺陷漏磁场分布进行模拟,并在交变磁场激励下对不同焊接缺陷进行磁光成像无损检测试验,通过试验验证了焊接缺陷检测模型的有效性。研究结果表明,漏磁场分布与缺陷的类型和宽度密切相关,随着宽度增大,缺陷漏磁场的磁感应强度垂直分量亦增大;在相同宽度下,未熔合、表面裂纹、亚表面裂纹和无缺陷磁光图像灰度峰谷差值呈递减趋势,磁光图像灰度值可与漏磁场强度相匹配;所建焊接缺陷模型和磁光成像试验能有效地描述不同焊接缺陷对漏磁信号和图像灰度值分布的影响,有助于提高焊接缺陷检测和质量评估。     

神光Ⅲ精密光学元件表面广义洁净度检测

根据神光Ⅲ实验样机里的精密光学元件表面实际特点,提出了综合考虑其表面疵病和颗粒残留物的广义洁净度概念及其检测方法,阐述了广义洁净度的含义并提出了具体计算过程.研究了适合多种元件尺寸的检测装置,并利用图像里面不同组织具有不同灰度级实现图像分割,通过提取检测对象的几何、灰度及变换域空间的特征,构成待检测向量,采用支持向量机(SVM)方法进行识别.广义洁净度概念的提出和实现过程,对实际监测精密光学元件表面的质量并分析其损化变迁过程具有重要意义.     

太阳能硅片焊接质量参数在线视觉测量

针对硅电池片高速串焊系统,根据焊接质量参数在线检测的技术指标对视觉测量系统的核心部件进行了选型计算;对视觉测量系统的内部参数进行了标定,完成了畸变校正与像素当量计算;设计了焊后硅片视觉检测流程,研究了图像预处理、图像掩膜ROI提取、改进双阈值Otsu图像分割技术;建立了硅电池片焊带偏移参数测量模型,提出了一种硅电池片焊接质量参数在线视觉测量方法。最后将该在线视觉测量方法应用于某硅电池片高速串焊生产线,其综合检测率和单帧检测时间满足焊接质量在线检测的精度和实时性要求,为提高太阳能电池组件的焊接质量和生产效率打下了良好的技术基础。     

表面贴装元件的特征统计建模检测算法研究

为提高表面贴装元件在线检测的性能和可操作性,提出了一种基于特征的统计建模检测算法。对表面贴装的元件,首先提取并选择分类能力较强的几何和逻辑特征,然后利用统计分析建立元件的分类算法,并引入评价函数改善算法的分类能力,最终实现对片式元件缺件、偏移、歪斜和错件等缺陷的检测。实验结果表明,采用该算法能满足实际检测系统准确性和实时性要求。     

铜始极片表面缺陷检测系统研究与设计

随着生产和工艺的进步,人们对产品的质量要求越来越高。同时,铜始极片作为有色冶金行业的重要中间产品之一,其表面质量的优劣将影响最终产品的性能和质量。为此,依据缺陷的几何特征和光学特征等,提出了始极片表面缺陷检测系统的设计方案。为了保证铜始极片表面缺陷在线系统的实时性,硬件上采用线阵CCD相机与LED光源结合的图像采集装置。系统软件选用VC++语言进行编写,针对实际的目标图像,通过对其进行图像获取、图像预处理、图像分割和特征提取,从而获得始极片表面缺陷图像的识别信息。     

片状元件的波峰焊

近年来,电子元件和集成电路小型化扩展到电子技术各个方面,包括印制电路板在内。印制电路的出现是电子技术发展的重要阶段,可大批量地加工电子电路。为了满足电路复杂性要求,发展了多种印制电路板,如双面板、多层板。如果元件有引线,将引线插入金属化孔内焊接,若是“片状”类型,将封装元件直接焊在印制板表面上。前者是诸如电阻、电容和二极管之类的分立元件,后者是一体化的复杂元件,往往要求表     

板级电路振动分析及元器件布局优化技术研究

印制电路板上承载着各类电子元器件,使质量、刚度分布不均匀,求解印制电路板振动问题时,很难得到满足微分方程和边界条件的精确解。文中试图从弹性力学理论出发,探讨电子设备结构中印制电路板的振动问题,以及其上电子元器件的布局优化问题。运用弹性力学理论,对板的固有频率计算进行了理论推导,同时分析元器件的布局对振动固有频率的影响。从而得到在元器件布局的时候,尽量使元器件靠近约束,元器件较多时,把大而重的元器件靠近约束的结论,并用有限元计算对结论进行验证,理论分析结果和有限元计算结果吻合较好。     

Direct metal printing of 3D electrical circuit using rapid prototyping

Rapid prototyping (RP) is a direct-writing technology that offers several advantages over subtractive manufacturing processing, including low material consumption and easy customizability. Recently, this technique has been studied not only manufacture production parts but also electronic manufacturing applications. In this research, the design and manufacture of printed circuits using RP printing of lead-based alloy having low melting temperature were performed. The bonding strength was measured by strength test. Average bonding strength between solder and universal printed circuit board (PCB) was 69.5 kPa. A simple electrical circuit with five crossing points was constructed to reduce the size of the circuit. In the crossing points, polycaprolactone (PCL) was deposited between top and bottom interconnects to insulate the printed line. Through this process, the size of the circuit board can be reduced about 34% and the number of processing steps was decreased.     

基于最小二乘拟合法的焊点形状检测

自动光学检查是利用图像处理算法进行电路板故障检测与定位的技术。电路板焊点形状不规则故障，涉及到焊点几何形状的测量。本文提出一种新颖的基于最小二乘拟合法的焊点形状检测算法，对焊点形状轮廓图像进行曲线拟合，确定焊点形状近似的理想圆参数，即圆心和半径，以及焊点形状与理想圆之间的偏差，实验证实了该算法的性能。     

Algorithm of locating PCB components based on colour distribution of solder joints

This paper investigates the methodologies for locating and identifying components on a printed circuit board used for surface mount device inspection. It is the foundation of other inspections, such as solder joint inspections. The proposed approach analyzes the colour distribution patterns of solder joints under three layers of ring-shaped LEDs. All solder joints are recognized and located according to colour distribution patterns and their highlight properties. At the same time, other highlight components, such as markings and via-holes are also recognized and removed. The colour distribution direction of each solder joint is also evaluated. The determined directions offer important clues for the clustering of solder joints. All the solder joints of a component are clustered based on their colour distribution directions and some additional constraints. The protective coating of each component is located based on the position of all clustered solder joints. The experimental results show that the proposed method can recognize most of components effectively.     

印制板阻焊膜制作工艺及品质控制

对印制板采用丝网印刷液态感光成形阻焊剂的制作进行了简单介绍,对该制程的工艺过程和品质控制进行了较为详细的论述.     

Effects of solder joint structure and shape on thermal reliability of plastic ball grid array package

Among the PBGA (plastic ball grid array) packages, a 72-I/O OMPAC (overmolded effect array carrier) package is studied during thermal cycling. The ANSYS software is applied to analyze the effects of some factors on the solder joint for the fatigue life due to elastoplastic deformation of the electronic package; those factors are solder structure, shape, and pitch. The result shows that the maximum equivalent plastic strain range occurs at two interfaces, one is between the solder joint and the substrate, another one is between the solder joint and the printed circuit board. Moreover, the solder shape is determined by the solder height and the pad diameter under a fixed value of solder volume. It is found that the convex-shaped solder with larger height and smaller pitch has smaller maximum equivalent plastic strain range, which leads to the longer fatigue life. In addition, there are two kinds of solder structure: pure solder joint and copper core solder joint. In the copper core solder joint, the eutectic part becomes so small that a larger strain is induced. Therefore, the pure solder joint has smaller maximum equivalent plastic strain range and longer fatigue life than the copper core solder joint.     

PCB焊点及芯线端头识别

智能微型化的医用器械在医疗行业逐渐被人们所重视。这些产品主要是由一些微型电子元器件构成,其中器件核心芯片部分的点线连接结构需通过高精密焊接工作完成。因此焊点和被焊芯线的识别精度要求越来越高,两者是否能准确有效识别直接影响焊接的最终质量。为高质量完成焊接过程中的焊点和芯线识别,本文主要使用电子显微仪器结合上位机VS17+OpenCV软硬结合的方法完成图像处理,对所采集图像中的焊点和芯线端头进行识别。以焊点和芯线端头的颜色及几何特征作为分析对象,经预处理后再通过各自特征分析突出感兴趣区域部分,通过特定颜色阈值选取方式和对比度提升算法完成焊点和芯线端头的分割过程,要求所测量焊点及芯线端头的识别精度误差≤0.1 mm。实验结果表明：本文印刷电路板(PCB)焊点及芯线端头的识别算法能有效识别焊点及芯线端头图中所在位置并显示其像素坐标值;经数据整理分析,本文算法的识别精度误差均控制在允许的误差范围内。     

A knowledge-based object oriented DFM advisor for surface mount PCB assembly

The volume and complexity of printed circuit boards (PCBs) that use surface mount technology has increased tremendously over the past decade. The intricacy of the design and manufacturing functions associated with this domain is continuously increasing. Several researchers have documented the significance of the design functions on product life cycle costs. In the surface mount PCB assembly area, the integration of the design and manufacturing activity is hampered by the lack of sufficient, in-depth manufacturing knowledge among the PCB designers. Also, the heuristic nature of manufacturing knowledge coupled with the frequent advances in the state-of-the-art has resulted in the lack of widespread in-depth process knowledge.This research focused on the design and development of a knowledge-based methodology which can be used to assist the design engineer in the surface mount PCB assembly domain. The rules relate primarily to the solderability, cleanability and reflow aspects of the design. An object oriented programming (OOP) methodology is used. The OOP framework allows for structured and modular development and implementation of the knowledge-based design advisor. It allows for the easy maintenance and update of the software along with the integration of knowledge bases and databases. The system has been partitioned into three major components — the user interface, the update mechanism along with the inference engine, and the database management utility. An important feature of this research has been the focus on updateability of the design advisor with respect to data and knowledge (rules). The logic or the rules within the system have been developed in an updateable format. The calculations required during the firing of the rules are performed by dynamic linked libraries (dlls). The design advisor has been developed in the Windows operating system using the C++ language. The database manipulation functions are handled by CodeBase 5.0 libraries.Glossary Chip Component Typically stands for resistors, capacitors, diodes, and other passive components. It could include integrated circuits also. - LCCC The leadless ceramic chip carrier is a ceramic package with leads around and down the sides of the package. - Component A single part or a combination of parts that together performs a specific design function. - Component lead The wires or conductors that extend from a component. They provide mechanical and physical connections. - Coplanarity Used to denote the relationship of leads or pads (on a board) to each other in the horizontal plane. - CTE The coefficient of thermal expansion (CTE) represents in linear terms the expansion of material as the temperature changes (increases). - CTE mismatch The absolute difference in the thermal expansion of two materials. - Flux A chemically and physically active material that promotes wetting of solder and helps in the formation of a solder joint. - Fine pitch component A component with a lead pitch less than 0.65 mm lead pitch. - Integrated circuits Electronic components assembled together on a single substrate to perform a specific electrical function. Typical surface mount packages that contain integrated circuits include quad flat packs, plastic leaded chip carriers, and small outline devices. - Ionic contaminants Residues on the printed circuit board after the assembly process including flux, finger prints, etc. - Land A conductive pattern etched on an unpopulated board. Typically used for the connection of components. - MELF A metal electrode face bonded chip carrier with metalized connections. - Printed circuit board A board with metal interconnecting traces. - Surface mount component A component that is designed to be mounted and attached (typically by soldering) onto the surface of a printed circuit board in contrast to the traditional insertion mounting method. - Solder An alloy of different metals typically with a melting point less than 200°C. - Solder paste Solder particles, flux, and other binders are combined together to form a paste. The size of the solder particles and the volume of the constitutents are tightly controlled. - Stencil A thin sheet of metal with a circuit pattern etched or cut into it. Typically used for depositing solder paste. - Via A plated through hole used to connect two or more layers of a board. - Wetting The formation of a smooth, uniform, and unbroken film of solder to a metal surface.     

The development of the physical fundamentals of contact soldering as a factor for reducing the number of defects in electronic devices

Automated control systems employ electronic components that are connected with a printed circuit board (PCB) by soldered joints. At elevated temperatures and with high vibration levels, soldering defects may occur that are characterized by the deterioration or complete loss of contact with the PCB, which can lead to the failure of the system. In this work, an approach is proposed to considerably improve the reliability of soldered joints.     

汽车电气电子系统EMC设计存在的问题及其改进技术

为解决汽车电气电子系统EMC设计存在的问题,从线束干扰、车内电磁干扰、印制线路板的电磁兼容等问题出发,指出减小导线串扰、优化线路板、抑制机电部件干扰、采用屏蔽和滤波等技术,能够有效地改善整体兼容性,为汽车电气电子系统EMC设计提供参考。