Automated X-ray Defect Inspection on Occluded BGA Balls Using Hybrid Algorithm

Automated X-ray defect inspection of occluded objects has been an essential topic in semiconductors,autonomous vehicles,and artificial intelligence devices.However,there are few solutions to segment occluded objects in the X-ray inspection efficiently.In particular,in the Ball Grid Array inspection of X-ray images,it is difficult to accurately segment the regions of occluded solder balls and detect defects inside solder balls.In this paper,we present a novel automatic inspection algorithm that segments solder balls,and detects defects fast and efficiently when solder balls are occluded.The proposed algorithm consists of two stages.In the first stage,the defective candidates or defects are determined through the following four steps:(i)image preprocessing such as noise removal,contrast enhancement,binarization,connected component,and morphology,(ii)limiting the inspec-tion area to the ball regions and determining if the ball regions are occluded,(iii)segmenting each ball region into one or more regions with similar gray values,and(iv)determining whether there are defects or defective candidates in the regions using a weighted sum of local threshold on local variance.If there are defective candidates,the determination of defects is finally made in the following stage.In the second stage,defects are detected using the automated inspection technique based on oblique computed tomography.The 3D precision inspection process is divided into four steps:(i)obtaining 360 projection images(one image per degree)rotating the object from 0 to 360 degrees,(ii)reconstructing a 3D image from the 360 projected images,(iii)finding the center slice of gravity for solder balls from the axial slice images in the z-direction,and getting the inspection intervals between the upper bound and the lower bound from the center slice,and(iv)finally determining whether there are defects in the averaged image of solder balls.The proposed hybrid algorithm is robust for segmenting the defects inside occluded solder balls,and improves the performance of solder ball segmentation and defect detection algorithm.Experimental results show an accuracy of more than 97%.

Application of ultrasonic inspection in monitoring dynamic healing of mandibular fracture in rabbit model

Objective:To investigate the feasibility of ultrasonic diagnosis for monitoring fracture healing. Methods:Thirty rabbit models with fraction of mandible body were established by surgically removing partial lower jawbone.At the 1st,2nd,4th,6th,8th and 12th week after the operation, they were examined by X-ray and ultrasound,respectively.All detection results were scored according to a generally accepted standard.Spearman rank correlation analysis was conducted to explore the relationship between the results of the two inspection methods.Results:In each healing stage,the results of the ultrasonic inspection were basically consistent with those of the X-ray examination,as supported by a Spearman rank correlation coefficient of 0.892(P【0.001). Conclusions:Non-invasive ultrasonic inspection can be used instead of X-ray examination to monitor and diagnose fracture healing.

A novel x-ray circularly polarized ranging method

Range measurement has found multiple applications in deep space missions. With more and further deep space ex- ploration activities happening now and in the future, the requirement for range measurement has risen. In view of the future ranging requirement, a novel x-ray polarized ranging method based on the circular polarization modulation is proposed, termed as x-ray circularly polarized ranging （XCPolR）. XCPolR utilizes the circular polarization modulation to process x-ray signals and the ranging information is conveyed by the circular polarization states. As the circular polarization states present good stability in space propagation and x-ray detectors have light weight and low power consumption, XCPolR shows great potential in the long-distance range measurement and provides an option for future deep space ranging. In this paper, we present a detailed illustration of XCPolR. Firstly, the structure of the polarized ranging system is described and the signal models in the ranging process are established mathematically. Then, the main factors that affect the ranging accuracy, including the Doppler effect, the differential demodulation, and the correlation error, are analyzed theoretically. Finally, numerical simulation is carded out to evaluate the performance of XCPolR.

Iterative circle fitting based on circular attracting factor

An intuitive method for circle fitting is proposed. Assuming an approximate circle(CA,n) for the fitting of some scattered points, it can be imagined that every point would apply a force to CA,n, which all together form an overall effect that "draws" CA,n towards best fitting to the group of points. The basic element of the force is called circular attracting factor(CAF) which is defined as a real scalar in a radial direction of CA,n. An iterative algorithm based on this idea is proposed, and the convergence and accuracy are analyzed. The algorithm converges uniformly which is proved by the analysis of Lyapunov function, and the accuracy of the algorithm is in accord with that of geometric least squares of circle fitting. The algorithm is adopted to circle detection in grayscale images, in which the transferring to binary images is not required, and thus the algorithm is less sensitive to lightening and background noise. The main point for the adaption is the calculation of CAF which is extended in radial directions of CA,n for the whole image. All pixels would apply forces to CA,n, and the overall effect of forces would be equivalent to a force from the centroid of pixels to CA,n. The forces from would-be edge pixels would overweigh that from noisy pixels, so the following approximate circle would be of better fitting. To reduce the amount of calculation, pixels are only used in an annular area including the boundary of CA,n just in between for the calculation of CAF. Examples are given, showing the process of circle fitting of scattered points around a circle from an initial assuming circle, comparing the fitting results for scattered points from some related literature, applying the method proposed for circular edge detection in grayscale images with noise, and/or with only partial arc of a circle, and for circle detection in BGA inspection.

Assessing high-energy x-ray and proton irradiation effects on electrical properties of P-GaN and N-GaN thin films

The effects of ionizing and displacement irradiation of high-energy x-ray and 2-MeV proton on GaN thin films were investigated and compared in this study.The electrical properties of both P-GaN and N-GaN,separated from power devices,were gauged for fundamental analysis.It was found that the electrical properties of P-GaN were improved as a consequence of the disruption of the Mg-H bond induced by high-dose x-ray irradiation,as indicated by the Hall and circular transmission line model.Specifically,under a 100-Mrad(Si)x-ray dose,the specific contact resistance pc of P-GaN decreased by 30%,and the hole carrier concentration increased significantly.Additionally,the atom displacement damage effect of a 2-MeV proton of 1×10^(13)p/cm^(2)led to a significant degradation of the electrical properties of P-GaN,while those of N-GaN remained unchanged.P-GaN was found to be more sensitive to irradiation than N-GaN thin film.The effectiveness of x-ray irradiation in enhancing the electrical properties of P-GaN thin films was demonstrated in this study.

Application of molybdenum target X-ray photography in imaging analysis of caudal intervertebral disc degeneration in rats

BACKGROUND Conventional plain X-ray images of rats,the most common animals used as degeneration models,exhibit unclear vertebral structure and blurry intervertebral disc spaces due to their small size,slender vertebral bodies.AIM To apply molybdenum target X-ray photography in the evaluation of caudal intervertebral disc(IVD)degeneration in rat models.METHODS Two types of rat caudal IVD degeneration models(needle-punctured model and endplate-destructed model)were established,and their effectiveness was verified using nuclear magnetic resonance imaging.Molybdenum target inspection and routine plain X-ray were then performed on these models.Additionally,four observers were assigned to measure the intervertebral height of degenerated segments on molybdenum target plain X-ray images and routine plain X-ray images,respectively.The degeneration was evaluated and statistical analysis was subsequently conducted.RESULTS Nine rats in the needle-punctured model and 10 rats in the endplate-destructed model were effective.Compared with routine plain X-ray images,molybdenum target plain X-ray images showed higher clarity,stronger contrast,as well as clearer and more accurate structural development.The McNemar test confirmed that the difference was statistically significant(P=0.031).In the two models,the reliability of the intervertebral height measured by the four observers on routine plain X-ray images was poor(ICC<0.4),while the data obtained from the molybdenum target plain X-ray images were more reliable.CONCLUSIONMolybdenum target inspection can obtain clearer images and display fine calcification in the imaging evaluation of caudal IVD degeneration in rats,thus ensuring a more accurate evaluation of degeneration.

Rolling Deformations and Residual Stresses of Large Circular Saw Body

Rolling path squeezes and rolling residual stresses of large diameter circular saw body for wood, generated by rolling pressure from 10 up to 120 bar were examined. X-ray diffraction, Barkhausen noise (BN) and Full Width of the peak at a Half Maximum (FWHM) (o) methods for evaluation of residual stresses were used. Dependencies of a tangential rolling residual stresses inside rolling paths upon rolling pressure p (bar) and rolling area A (mm2) were evaluated. The rolling pressure, as large as 60 bar, resulting in the rolling squeeze as high as 0.04 mm2, and, tangential residual compression stresses inside a rolling path, as large as ?TI = ?822 MPa, was considered to be the largest for the practical application.

A low noise multi-channel readout IC for X-ray cargo inspection

A low noise multi-channel readout integrated circuit （IC） which converts a detector current to analog voltage for X-ray cargo inspection is described. The readout IC provides 32 channels of a circuit having a maxi- mum dynamic range of 15 bit and is comprised of integrator gain selection, timing generator, shift register chain, integrator array, sample/hold （S/H） stage amplifier etc. and occupies a die area of 2.7 × 13.9 mm2. It operates at It was fabricated using 0.6 μm standard CMOS process, 1 MHz, consumes 100 mW from a 5 V supply and 4.096 V as reference, and has a measured output noise of 85 μVms on 63 pF of integrator gain capacitance and 440 pF of photodiode terminal capacitance so that steel plate penetration thickness can reach more than 400 mm.

面向环形管道的电力巡检机器人设计与环境建图

在大型水电站中,离相封闭母线(isolated phase enclosed bus,IPB)只能通过预防性试验对设备状态进行检查,难以目视外观检查。为解决这种密闭狭小空间的环形管道的巡检困难问题,提出一种可在水平、竖直段上行走的轮式攀爬机器人。首先,对攀爬机器人移动和附着方式进行对比分析,根据实际工况,选用轮式推力附着方式并基于该方式对机器人整体结构进行力学分析;通过搭建的模拟IPB管道内的运动实验。结果表明:巡检机器人满足水电站内IPB管道的检修需求且具有良好的适应性;设计基于柱坐标的点云配准方法,解决了管道内无法正确建图的问题,且计算时间优于激光雷达里程计建图(lidar odometry and mapping,LOAM)及迭代最近点(iterative closest point,ICP)算法,拓展了激光雷达点云建图的应用范围。

收口式圆形检查井标准化砌筑施工技术及经济分析

砖砌检查井在城市地下基础设施的供电、给排水、排污、通讯、燃气等管道工程中的应用十分广泛,一般在管道交汇及转弯处、管径或坡度改变处、以及直线管道上每隔一定距离设置,便于设备的安装、检查与维修。对于收口式圆形排水检查井,传统砌筑工艺普遍存在井室尺寸偏差大、圆顺度及垂直度不良、井壁收口不准确等缺陷。针对现有技术工艺的不足,研发一种用于收口式圆形检查井砌筑的测控工具,代替以往模具法、垂线法及经验目测的落后工艺,确保收口式圆形检查井的设计直径、井壁圆顺度与垂直度、以及收口段井室尺寸满足设计要求,通用于常规孔径的圆形检查井施工,可多次周转使用,有效简化工序、提高工效,节约人力资源及辅助材料,实现降本增效、节材环保。

大型非球曲面超精密复合加工机床

详细介绍了“大型非球曲面超精密复合加工机床”．该机床具有磨削、铣削、车削等多种加工功能,采用了高精度的FANUC系统,在X横向导轨上设计了独特的卸荷系统,在Z垂直导轨上设计了精确的配重系统,主轴转速为150 r／min,可加工最大尺寸为φ1 200 mm的工件．用高精度的电感测微仪和自准直仪对机床进行了检测,结果表明:其数控系统位置及控制分辨率为0．05μm,主轴回转精度为26 nm．最后,用该机床进行了超精密加工试验,经检测,其加工工件的表面粗糙度Ra优于15 nm,实现了大型非球曲面的超精密加工．

基于弦中点Hough变换的同心圆检测方法

给出了一种基于Hough变换的同心圆检测方法,其核心思想是降低经典Hough变换圆检测中的Hough累积维数,将经典Hough变换圆检测时的三维参量统计,转变成基于弦中点的圆心和半径的参量统计。根据圆上所有点的内切圆必经过圆中心的事实,提取黑白边缘图像来建立二维数组累加器,依照像素点分布扫描边缘图像,累加器计数,计算出圆心位置,对每个圆心进行半径累积,确定同心圆半径集。与经典的Hough变换检测方法相比,该方法降低了计算复杂度。

基于3D摄影测量盾尾质量检测技术

为保证盾构施工安全,防止盾尾在施工过程中漏浆,施工前须对盾尾圆度进行检测。通过对3D摄影测量检测系统测量设备、测量原理及方法进行阐述,并通过实例对盾尾各部分相对于标准设计图形的具体偏差进行分析。主要结论如下:1)采用3D摄影测量新技术,能快速、准确地检测出盾尾圆度;2)3D摄影测量技术方法在盾尾质量检测上的成功应用,为盾构等重大装备构件尺寸误差质量比对提供了一种新方法。

高精度插件引脚机器视觉检测系统的研究与开发

电子元器件引脚检测是印刷电路板在插件时必不可少的环节,而引脚的合格与否差别十分细微,需用精确和快速的检测方法进行判定。结合直立电容引脚图像的特点,在对引脚图像二值化分割的基础上,对连通区域的特征(面积和圆度)进行分析,排除噪声干扰,精确定位目标的位置,实现了对直立电容引脚的数目、尺寸和间距的检测。对比检测实验和重复测试稳定性实验结果表明:该检测方法的检测精度高,速度快,可以满足电子元器件引脚在线检测的要求。

基于圆形匹配与数据融合的大口径平行光管视差自动检测方法研究

目前平行光管视差检测多采用五棱镜法,由于人工读数存在较大的误差,提出了一种基于圆形匹配与数据融合的大口径平行光管视差自动检测方法。选用高清相机对大口径平行光管分划板成像,通过大津法二值化、开运算去滤波、边缘检测、圆形匹配、数据融合等方法得到图像圆心所在位置;最终给出视差计算结果。视差计算的过程中,可以实现多点测试,即可以给出视差变换的曲线,可以给平行光管的调校带来方便。试验表明自动视差测量装置的检测结果准确,并具有良好的可重复性。

中央巡视制度的反腐效用提升思路探讨

虽然巡视制度在十八大后发挥了显著的反腐功能,但从长期发展的角度看其反腐效用还有待进一步发挥。巡视制度本身还有待进一步精细化,相关人的行为还需进一步规范。巡视制度理论研究、政治体制、信息不对称问题与制度执行人的动机和能力都会影响和制约巡视制度反腐效用。进一步提升巡视制度反腐效用的思路是,以"环形监督"理论假设突破"线性监督"中的难题;精细优化巡视制度,解决执行人动机和能力问题;进一步规范相关人行为;借助互联网信息技术解决巡视工作信息不对称问题。

基于序贯截尾检验的激光制导炸弹精度评估方法研究

通过CEP的计算方法,推导得到激光制导炸弹的落点偏差。基于序贯截尾检验方法,采用Monte-Carlo法仿真得到截尾数,通过分析不同的CEP指标,对激光制导炸弹的投放精度进行评估。仿真试验亦验证了在设定的截尾数范围内,增加投弹数量可以适当提高激光制导炸弹投放精度指标。

圆周孔系位置度的测量

利用综合检具和三坐标两种方法对圆周孔系位置度进行了检测,通过综合检具的设计、使用,有效地解决了孔系位置度检验效率低的问题;利用三坐标,坐标系的粗建、平移、旋转,对测量结果进行了优化处理。旨在为机械领域检验工作者提供一定的借鉴意义。

圆形盾构隧道断面自动化检测系统研究与开发

该文首先,分析了研究和开发圆形盾构隧道断面自动化检测系统的必要性。接着,研究了系统整体设计和软件功能设计,提出了新的更加适用和易于软件实现的平面拟合方法和空间圆拟合方法。在一个工程实例中应用了所开发的系统,并且和其他算法得到的结果进行了比较。结果表明了所开发的系统的可行性和实用性。

纬编针织智能化技术与系统开发

结合近几年纬编针织智能化技术和应用系统开发方面的研究,阐述国内外相关技术与系统开发情况。详细介绍圆纬机生产过程中采用的实时监控系统和织物疵点检测系统,纬编针织物自动验布系统和织物结构自动识别系统,以及针织CAD与CAM系统,并详细阐述各个系统的工作原理和工作特点。纬编针织智能化技术有助于生产过程的智能化,可以减少用工、提高生产效率,但智能化系统的可靠性与稳定性还有待进一步提高。