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BGA(Ball Grid Array) 높이 데이타의 고속 측정
조태훈,주효남,Cho Tai-Hoon,Joo Hyo-Nam 한국반도체디스플레이기술학회 2006 반도체디스플레이기술학회지 Vol.5 No.1
Recently, Ball Grid Arrays(BGAs) are getting used more frequently for a package type. The connectors on a BGA consist of a large number of small solder balls in a grid shape on its bottom side. However, since balls of BGAs mounted on PCBs are not visible, inspection before mounting them is indispensable. High speed non-contact 3D measurement technologies are necessary far real-time measurement of ball height, the most important inspection item. In this paper, an accurate 3D data acquisition system for BGAs is proposed that can acquire 3D profile at high speed using a 3D smart camera and laser slit ray projection. Some clipping and morphological filtering operations are employed to remove spiky error data, which occur due to reflections from some ball area to camera direction.
QFN 반도체 패키지의 외형 결함 검사를 위한 효과적인 결함 분류 시스템 개발
김효준,이정섭,주효남,김준식,Kim, Hyo-Jun,Lee, Jung-Seob,Joo, Hyo-Nam,Kim, Joon-Seek 한국융합신호처리학회 2009 융합신호처리학회 논문지 (JISPS) Vol.10 No.2
There are many different types of surface defects on semiconductor Integrated Chips (IC's) caused by various factors during manufacturing process, such as cracks, foreign materials, chip-outs, chips, and voids. These defects must be detected and classified by an inspection system for productivity improvement and effective process control. Among defects, in particular, foreign materials and chips are the most difficult ones to classify accurately. A vision system composed of a carefully designed optical system and a processing algorithm is proposed to detect and classify the defects on QFN(Quad Flat No-leads) packages. The processing algorithm uses features derived from the defect's position and brightness value in the Maximum Likelihood classifier and the optical system is designed to effectively extract the features used in the classifier. In experiments we confirm that this method gives more effective result in classifying foreign materials and chips. 반도체 외관결함에는 발생 요인이 각각 다른 crack, foreign material, chip-out, chip, void 등이 있으며, 검사 시스템에서는 결함 유무 및 결함 분류를 수행하여 효과적인 공정관리가 가능하여야 한다. 본 논문에서는 QFN 패키지 결함의 분류를 위한 알고리즘 및 광학시스템을 제안한다. 제안한 방법에서 분류가 어려운 결함 중 하나인 foreign material 과 chip의 효과적인 분류를 위해 제안한 결함의 위치, 밝기의 특징정보(feature)를 사용한 ML(Maximum Likelihood ratio) 분류방법 및 특징정보 획득에 효과적인 광학계를 제안하였다. 실험 결과에서 분류가 어려운 foreign material과 chip에 대한 신뢰성 높은 분류성능을 보였다.
BGA 소자의 결함검출을 위한 2차원 비젼 검사알고리즘에 관한 연구
김준식,김기순,주효남,Kim, Joon-Seek,Kim, Kee-Soon,Joo, Hyo-Nam 한국조명전기설비학회 2005 조명·전기설비학회논문지 Vol.19 No.7
본 논문에서는 비젼 시스템을 사용하여 마이크로 BGA 소자의 2차원 결함을 검사하는 알고리즘을 제안하였다. 제안한 방법은 정밀도를 높이기 위해 부화소 알고리즘을 사용하였으며, 입력된 영상에서 패키지 영역을 추출하고, 추출된 영역에서 볼 탐색창 방법을 사용하여 볼 영역을 추출한다. 이렇게 추출된 볼 영역에 대해 결함검사에 필요한 파라미터들을 추출하고, 이들을 사용하여 소자의 불량 유무를 판정한다. 모의실험을 통해 볼 검사 정밀도의 평균 오차가 17[${\mu}m$]가 됨을 확인하였다. In this paper, we proposed the 2-dimensional inspection algorithm for micro-BGA(Ball Grid Array) device using a vision system. The reposed method uses the subpixel algorithm for high precision. The proposed algorithm preferentially extracts the package area of device in the input image. After the extraction of package area, each ball areas are extracted by ball search window method. The parameters for inspection are calculated for the extracted ball area. In the simulation results, we have the average error within 17[${\mu}m$].
반도체소자의 고속마킹검사를 위한 vision system 개발
노영동(Woung-Dong Noh),주효남(Hyo—,Nam Joo),김준식(Joon—,oeek Kim) 호서대학교 공업기술연구소 2005 공업기술연구 논문집 Vol.24 No.1
In this paper, we propose the high speed making/surface inspection algorithm, that use adaptive automatic acquisition algorithm and real time matching algorithm of model data. The proposed automatic acquisition algorithm to obtain the adaptive model data extracts the interesting regions to fit in semiconductor characteristics, and create models of several semiconductor regardless of position and type. The proposed real time matching algorithm uses geometrical pattern matching method to minimize effect of external environment of making/surface and only use semiconductor characteristic information. The proposed system has faster processing time than the conventional method. Also the proposed one has a good performance.
Mura 검출을 위한 Model Fitting 및 Least Square Estimator의 비교
오창환(Chang-Hwan Oh),주효남(Hyo-nam Joo),류근호(Keun-Ho Rew) 제어로봇시스템학회 2008 제어·로봇·시스템학회 논문지 Vol.14 No.5
Detecting and correcting defects on LCD glasses early in the manufacturing process becomes important for panel makers to reduce the manufacturing costs and to improve productivity. Many attempts have been made and were successfully applied to detect and identify simple defects such as scratches, dents, and foreign objects on glasses. However, it is still difficult to robustly detect low-contrast defect region, called Mura or blemish area on glasses. Typically, these defect areas are roughly defined as relatively large, several millimeters of diameter, and relatively dark and/or bright region of low Signal-to-Noise Ratio (SNR) against background of low-frequency signal. The aim of this article is to present a robust algorithm to segment these blemish defects. Early 90"s, a highly robust estimator, known as the Model-Fitting (MF) estimator was developed by X. Zhuang et. al. and have been successfully used in many computer vision application. Compared to the conventional Least-Square (LS) estimator the MF estimator can successfully estimate model parameters from a dataset of contaminated Gaussian mixture. Such a noise model is defined as a regular white Gaussian noise model with probability $1-\varepsilon$ plus an outlier process with probability $varepsilon$. In the sense of robust estimation, the blemish defect in images can be considered as being a group of outliers in the process of estimating image background model parameters. The algorithm developed in this paper uses a modified MF estimator to robustly estimate the background model and as a by-product to segment the blemish defects, the outliers.
FPD 결함검사를 위 한 Vision Inspection System 설계에 관한 연구
박성재(Sung-Jea Park),김민수(Min-Su Kim)),김준식(Joon-Seek Kim),주효남(Hyo Nam Joo) 호서대학교 공업기술연구소 2005 공업기술연구 논문집 Vol.24 No.1
A system is designed and developed to acquire accurate images and to detect cell defects of Flat Panel Displays. Detailed analysis and experiments are performed to design and select the lighting, optical and camera sub-system as well as mechanical motion and position control sub-system. Sample images are acquired using the developed system and the processed result shows the good performance in detecting simple cell defects.
BGA 소자의 볼 정점 높이 측정을 위한 스테레오 비젼 알고리즘 개발
이상신(Sang-Sin Lee),박영순(Young-Soon Park),김준식(Joon-Seek Kim),주효남(Hyo Nam Joo) 한국조명·전기설비학회 2005 한국조명·전기설비학회 학술대회논문집 Vol.2005 No.5월
In this paper, We proposed the stereo image modeling using 2-dimensional images captured by the high resolution cameras to inspect the ball defects of BGA(Ball Grid Array) device. The proposed algorithm consists of the package/ball area extraction part, the FOV(Field of View) calibration part, the top point matching part, and ball height measurement part, in the package/ ball area extraction part, the package and ball areas are separately extracted in a left and right image by the extraction algorithm. Through the experiment, we draw out the result.
카메라를 이용한 BGA 소자의 2차원 결함검출 알고리즘 개발
김기순(Kee-Soon Kim),김준식(Joon-Seek Kim),주효남(Hyo Nam Joo) 한국조명·전기설비학회 2005 한국조명·전기설비학회 학술대회논문집 Vol.2005 No.5월
In this paper, we proposed the 2-dimensional inspection algorithm for micro-BGA(Ball Grid Array) device using a vision system. The proposed method uses the subpixel algorithm for high precision. The proposed algorithm perferentially extracts the package area of device in the input image. After the extraction of package areas are extracted by ball search window method. The parameters for inspection are calculated for the extracted ball area. In the simulation results, we have the average error within 17㎛.
이정섭(Jung-Seob Lee),권오민(Oh-Min Kwon),주효남(Hyo-Nam Joo),김준식(Joon-Sik Kim),류근호(Keun-Ho Rew) 제어로봇시스템학회 2008 제어·로봇·시스템학회 논문지 Vol.14 No.5
In this paper, new inspection method is proposed for the surfaces of lead frame and IC"s. Optimal optical system and the accurate algorithm for the surface inspection are needed in machine vision area. The proposed optical system is composed of rectangular oblique light illumination and coaxial light illumination for the higher contrast and the results shows the better performances through experiments. The markings of IC surface are inspected using the accurate proposed method using the partitioned correlation coefficient, and the result shows reduction of under kill ratio compared to the previous method.