Kuk Won Ko

An automatic inspection of SMT rectangular chips based on PCA algorithm

In this paper, we present a practical approach to automatic visual inspection of SMT PCBs. There are thousands of chip components mounted on the notebook SMT PCB. The images of those chip components could not be exactly same due to the variance of shift, orientation, scale, and illumination condition. Even so, we could not memorize all kinds of inspection reference values for the different conditions. Most of inspection algorithms with fixed window template such as template matching, Fourier analysis, OCR, etc., do not show good performance for images with shifted, oriented, scaled, and variable illumination conditions. We propose a practical automatic inspection method of SMT rectangular chips; correcting the image variance of shift, orientation, and scale with practical speed, and updating the decision reference values in the inspection process. The performance of the proposed method is tested on numerous samples of rectangular chips on SMT PCB.

Development of vision system for defect inspection of electric parts in the tape and reel package

Tape and reel packaging process is one of the important final manufacturing process of electric chip. During and after this packaging process, the defects of chips in the tape and reel package should be inspected. It is so time and cost consuming task by human inspectors. The main defects of chip in the tape and reel package are orientation chip, a wrong type chip and marking defects of chips. In this paper, the automatic vision system and image processing algorithms are developed to inspect the above defects on tape and reel packaging process. The high speed vision algorithm is based on multi-thread and parallel processing method to meet the inspection time(minimum 200 chips/min). Experiments were performed to evaluate the proposed vision inspection algorithms. The experimental result shows that our algorithm achieves high accuracy and speed for industrial requirement.

Implementation of an Image Restoration with Block Iteration Method for Spatially Variant Blur Models

In image restoration, for spatially variant blur, block-wise iterative method have been proposed. Block-wise iterative method is based on the assumption that the blur approximates to spatially invariant in a small region of the blurred images. These approaches show approximation errors and block artifacts. In this work, we suggest to use block iterative method without approximates to spatially invariant blur considering arbitrary shaped blocks related to shapes of blur models. We can reduce the approximation errors and block artifacts with high speed of iteration convergence. This proposed image restoration method can reduce the computational efforts and is useful to embedded system such as mobile phone and embedded vision system.

Development of automatic inspection of defect of compact camera module

Compact Camera Module(CCM) is widely used in PDA, Celluar phone and PC web camera. With the greatly increasing use for mobile applications, there has been a considerable demands for high speed production of CCM. The major burden of production of CCM is assembly of lens module onto CCD or CMOS packaged circuit board. After module is assembled, the CCM is inspected. In this paper, we developed the image capture board for CCM and the imaging processing algorithm to inspect the defects in captured image of assembled CCMO. The performances of the developed inspection system and its algorithm are tested on samples of 10000 CCMs. Experimental results reveal that the proposed system can focus the lens of CCM within 5s and we can recognize various types of defect of CCM modules with good accuracy and high speed.

Development of the Vision System and Inspection Algorithms for Surface Defect on the Injection Molding Case

The surface defects of plastic after the injection molding process have been inspected human inspector. In this paper, we propose the automated surface inspection system to detect 3D defects on injection molding objects. This vision system is equipped with 4-cameras and 8-illuminations and is designed to find optimal configuration between camera, illumination and object to detect the defects on an object. Also we develop algorithms to detect defects in captured images. The developed surface inspection system reduce the labor costs and time, whereas increase the detection accuracy of the surface defects such as scratch. The proposed algorithm uses the difference of the brightness of the obtained image by the camera and illumination system for acquiring data of the surface of the object. We focus on the surface defect detection of black molding object. Scratch detection is performed by the developed vision inspection system.

Implementation of a Smart IoT Factory Using an Agricultural Grade Sorting Device

The purpose of this study is to implement the smart IoT factory through developing an automatic 6-years fresh ginseng grade classification device. The washed 6-years ginseng from farmland should be sorted 3 rating by a classification criterion such as weight and shape but this classification process has been conventionally performed manually and there are increasing sorting process costs. To overcome this disadvantage, we developed an automatic gin-seng sorting device. The 6 years ginseng put into the device for the classification is designed to perform such as the weight estimation and the shape analyzed by the image processing procedure, and classification result is sent to the factory server over the network. Evaluating the performance of developing machine experiment with 100 6-years ginseng showed a high recognition rate for 94 % for grade 1, 98 % for grade 2, and 90 % for grade 3.

2D/3D Visual Optical Inspection System for Quad Chip

In the manufacturing process of the LQFP/TQFP (Low-profile Quad Flat Package/Thin Quad Flat Package), the requirement of a 3 dimensional inspection is increasing rapidly and a 3D inspection of the shape of a chip has become an important report of quality control. This study developed a 3 dimensional measurement system based on PMP (Phase Measuring Profilometry) for an inspection of the LQFP/TQFP chip and image processing algorithms. The defects of the LQFP/TQFP chip were classified according to the dimensions. The 2 dimensional optical system was designed by the dorm illumination to achieve constant light distribution, In the 3 dimensional optical system, PZT was used for moving 90 degree in phase. The problem of 2 ambiguity was solved from the measured moir? pattern using the ambiguity elimination algorithm that finds the point of ambiguity and refines the phase value. The proposed 3D measurement system was evaluated experimentally.

Development of an eye tracking medical headlamp.

This study investigates a medical headlamp which is designed to adjust LED light automatically on the X axis and Y axis plane as determined a surgeon during a surgery. The needs of surgeons are determined through a CMOS camera which detects the movement of the eye. The system is composed of a mechanical actuator and an electrical control center. The LED lamp actuator (50×24×21 mm3) was designed to be as small as possible. The actuator can be easily attached onto typical goggles and incurs no burden during long-term use due to its light weight of 40g. To determine the movement of the eye, a limited embedded CPU was designed while considering memory, the process speed, simplicity and accuracy. The designed system was tested by exercises such as moving the eye in a zigzag direction and in random up, down, left, and right directions with adjustments for different lightings. Each was tested 100 times (total 1500), showing satisfactory results with 98.72% accuracy.

3D Measurement System of Wire for Automatic Pull Test of Wire Bonding

The bond pull test is the most widely used technique for the evaluation and control of wire bond quality. The wire being tested is pulled upward until the wire or bond to the die or substrate breaks. The inspector test strength of wire by manually and it takes around 3 minutes to perform the test. In this paper, we develop a 3D vision system to measure 3D position of wire. It gives 3D position data of wire to move a hook into wires. The 3D measurement method to use here is a confocal imaging system. The conventional confocal imaging system is a spot scanning method which has a high resolution and good illumination efficiency. However, a conventional confocal systems has a disadvantage to perform XY axis scanning in order to achieve 3D data in given FOV (Field of View) through spot scanning. We propose a method to improve a parallel mode confocal system using a micro-lens and pin-hole array to remove XY scan. 2D imaging system can detect 2D location of wire and it can reduce time to measure 3D position of wire. In the experimental results, the proposed system can measure 3D position of wire with reasonable accuracy.