共查询到15条相似文献,搜索用时 203 毫秒
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根据p-n结的光生伏特效应,采用交变光源照射待测LED芯片,在封装的短路支架上激励出光生短路电流;通过对该微弱电流信号的测量,判断引脚式封装的LED芯片在压焊工艺中/后的功能状态及焊线质量,实现LED芯片的非接触检测。构建了以单片机为控制核心的测试系统,采取了提高系统检测准确性和检测效率的措施,实现了系统控制、数据处理分析等功能。实验结果表明,该系统能正确检测红光、黄光及绿光LED芯片,系统检测效率高,单个LED芯片的检测时间仅为10ms,适用于实际LED生产时引脚式封装工艺过程中的在线检测。 相似文献
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LED芯片在线检测方法研究 总被引:2,自引:0,他引:2
对于封装过程中的LED芯片的检测目前还没有行之有效的方法,基于p-n结的光生伏特效应和法拉第定律,提出一种非接触式的针对LED封装过程中芯片质量及芯片与支架之间连接状态的检测方法。根据实际LED芯片所处的闭合短路状态,感应回路由绕在高磁导率条形磁芯上的多匝线圈构成。磁芯采用不同搭接方式以提高检测的信噪比,根据实验结果确定了磁芯的最佳搭接方式。实验结果表明,该方法具有较高的检测精度,可以实现对闭合短路状态微安量级光生电流的检测。计算结果与实验结果吻合较好。 相似文献
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线阵CCD单板旋切厚度在线测量系统 总被引:3,自引:0,他引:3
线阵CCD作为一种高灵敏度光电传感器,广泛用于非接触检测领域中.本文介绍的线阵CCD单板旋切厚度在线测量系统,以8031单片机为核心,实现对单板旋切厚度的非接触在线测量,通过LED显示器显示测量结果.并由打印机隔时打印.测量精度达±1.4μm.该系统具有速度快、精度高、对环境要求低等特点. 相似文献
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Epoxy-packaging is widely used in light-emitting diode (LED) packages to protect LED chips and magnify the chip light. Surface flaws in LED packages affect not only the appearances of LEDs but also their functionality, efficiency and stability. Due to the high demand for productivity and quality, bare-eye-inspection approach becomes extremely inadequately. Therefore, this research proposes a machine-vision-based system for detecting tiny flaws occurred in the domed surfaces of LED epoxy-packing. We apply grey relational analysis to the frequency components in block discrete cosine transform domain, and significantly attenuate the large-magnitude frequency components that represent the background texture of the surface based on their corresponding grey relational grades. Then, by reconstructing the declined frequency components, we eliminate not only random texture but also uneven illumination patterns and retain anomalies in the restored image. This approach overcomes the difficulties of inspecting tiny flaws from uneven illumination backgrounds. Experimental results show that the proposed method can effectively inspect tiny flaws in LED domed surfaces. 相似文献
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We have developed a reel-to-reel microchip mounting system that continuously mounts LED chips and other microchips on meter-long flexible printed circuit board (PCB) tape for 1.2-m-long standard LED light tubes. Mounting microchips on meter-long PCBs is difficult because a large chip mounter is expensive and the chip positioning stage is difficult to move in a meter-wide area with an accuracy of hundreds of micrometers. Hence, we developed a new microchip mounting system that utilizes a small chip mounter and reel winding machines. The system repeatedly moves the long PCB tape by a certain length with the reel winding machines and mounts the chips on it. The PCB tape (which is 5 mm wide) is made by fabricating long PCB tapes which are 25 cm × 26.6 m through a roll-to-roll PCB process and slitting them into meter-long tapes. The reel-to-reel system repeatedly mounts chips by adjusting their positions through image processing of the copper wiring pattern on the PCBs. Our constructed system mounted 24 LED chips with a pitch of 5 cm with an accuracy of 0.082 mm to form a 1.2-m-long LED tape. The luminance of the tape is 12.4 lx at a distance of 1 m, which is the luminance of outdoor corridor lighting. Therefore, this system can be used for meter-long tape lighting. 相似文献
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LED芯片的定位是LED芯片检测、分选等后封装过程的关键步骤,其定位速度和精度直接决定了LED芯片检测设备的生产效率。为了提高芯片定位的精度,提出了基于视觉伺服的反馈补偿技术,有效补偿了芯片定位误差;为了提高芯片定位的速度,在视觉伺服系统的基础上,针对LED芯片的特点,提出形状匹配优化算法,通过减小匹配过程中匹配的面积和搜索的角度,有效弥补了因视觉运动补偿所消耗的时间。通过以上两方面提高了LED芯片定位精度和速度,满足LED芯片高精和高速的定位需求。 相似文献
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Zhou Diyi Gong Shihua Wang Ziyue Li Delong Lu Huaiqing 《Journal of Intelligent Manufacturing》2021,32(5):1345-1359
Journal of Intelligent Manufacturing - In the manufacturing process of LED chips, the accuracy of the LED chip visual localization system affects the quality of LED chip production directly. There... 相似文献
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Gotz A. Gracia I. Cane C. Morrissey A. Alderman J. 《Journal of microelectromechanical systems》2001,10(4):569-579
Demonstrates the feasibility of integrating fragile micromachined chips into a complex three-dimensional (3-D) multichip module (MCM) microsystem for a biomedical application. The system is based on the vertical integration of the different parts: micropumps and valves, a multisensor chip for on-line control of the system and a signal-processing chip. In this paper, packaging of the microsystem is studied in order to minimize the induced stress that can affect the integrity of the different micromachined parts of the system. Standard commercially available components and materials were used so as to minimize costs for the case of high volume packaging. For testing the approach, a multisensor chip which includes thin silicon membrane-based devices has been used as the main test structure to compare different packaging materials. In addition, for the fabrication of such a sensor chip in an efficient mode, technological modules needed to fabricate sensors on complementary metal-oxide-semiconductor (CMOS) wafers are discussed. The definition of standardized "add-on" sensor modules to the CMOS process of a foundry is intended to limit the development cost of smart sensors 相似文献