• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.3442-3447
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• 2014

A simple method to evaluate the hygroscopic characteristics of polymer of microelectronic plastic package is suggested. To evaluate the characteristics, specimens were prepared, and the internally absorbed moisture masses were measured as a function of the absorbing time and calculated numerically. The hygroscopic pressure ratio was calculated by heat transfer analysis supported by commercial FEM code because the hygroscopic diffusion equation has the same form as the heat transfer equation. The moisture masses were then summed by the self developed code. The nonconductive polymers had quite different characteristics for the different lots, even though they were the same products. The absorbed moisture mass variations were calculated for several different characteristics, and the optimal curve of the mass variation close to experimental data was selected, whose solubility and diffusivity were affected by the hygroscopic characteristics of the material. The method can be useful in the industrial fields to quickly characterize the polymer material of the semiconductor package because the fast correspondence is normally required in industry. The weight changes in the aluminum-nonconductive-polymer joint due to moisture absorption were measured. The deformed system was also measured using the Moire Interferometry system and compared with the results of finite element analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.5
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• pp.909-916
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• 2009

This paper presents the automatic vision algorithm to generate and calibrate reference phase plane to improve the accuracy of 3D measuring machine of using phase shifting projection moire method, which is not traditional N-bucket method, but is based on direct image processing method to the pattern projection image. Generally, to acquire accurate reference phase plane, the calibration specimen with well treated surface is needed, and detailed calibration method should be performed. For the cost reduction of specimen manufacturing and the calibration time reduction, on the specimen, not specially designed, with general accuracy level, an efficient calibration procedure for the reference phase generation is proposed. The proposed vision algorithm is developed to extract the line center points of the projected line pattern from acquired images, derive the line feature information consisting of its slope and intercept by using sampled feature points, and finally generate the related reference phase between line pairs. Experimental results show that the proposed method make reference phase plane with a good accuracy under noisy environment and the proposed algorithm can reduce the total cost to make high accurate calibration specimen, also increase the accuracy of reference phase plane, and reduce the complex calibration procedure to move grid via N-bucket algorithm precisely.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.1
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• pp.81-87
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• 2012

This paper focuses on three-dimensional measurement system of micro balls on micro Ball-Grid-Array(BGA) packages in-line. Most of visual inspection system still suffers from sophisticate reflection characteristics of micro balls. For accurate shape measurement of them, a specially designed visual sensor system is proposed under the sensing principle of phase shifting moire interferometry. The system consists of a pattern projection system with four projection subsystems and an imaging system. In the projection system, four subsystems have spatially different projection directions to make target objects experience the pattern illuminations with different incident directions. For the phase shifting, each grating pattern of subsystem is regularly moved by PZT actuator. To remove specular noise and shadow area of BGA balls efficiently, a compact multiple-pattern projection and imaging system is implemented and tested. Especially, a sensor fusion algorithm to integrate four information sets, acquired from multiple projections, into one is proposed with the basis of Bayesian sensor fusion theory. To see how the proposed system works, a series of experiments is performed and the results are analyzed in detail.

• Korean Journal of Optics and Photonics
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• v.19 no.5
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• pp.376-380
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• 2008

This paper presents the Projection Moire method using a line scan camera. The high resolution feature of a line scan camera makes it possible to scan an image quickly, thus enabling a much quicker 3D profile. This method uses a high resolution line scan camera making it possible to scan an image at high speed simultaneously measuring the 3D profile of a large FOV. When using a high resolution scan camera, a full FOV is scanned, thus requiring just one movement of a projection grating. As a result, the number of grating movements is reduced drastically. The end result is a faster and more accurate 3D measurement. Moving the grating too quickly causes vibration in the imaging system, which will normally be required to apply a stitching technique when using an area scan camera. However the technique is not required when using a line scan camera. Compared with the previous techniques, it has the advantages of simple hardware without moving mechanical parts - single exposure for obtaining three-dimensional information. A method using a high resolution line scan camera can be used in mass production to measure the bump height of wafers or the bump height of package substrates.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.428-431
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• 2004

This paper proposes a new 3-D display without glasses using $Moir\acute{e}$ system. It is possible to create a new three-dimensional expression that is different from conventional 3-Dimages. In this study we have geometrically analyzed the process by which moire takes on a three-dimensional property and validated the results of this analysis.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.204-205
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• 2002

근래 활발히 연구되고 있는 광통신 분야에서 광섬유는 중요한 위치를 차지하고 있으며 현재까지 여러 가지 연구가 되어져 왔다. 광섬유 중 플라스틱 광섬유는 근거리 광통신 분야에 사용을 위해서 활발한 연구와 개발이 이루어지고 있다. 이러한 광섬유의 특성을 결정짓는 중요한 요소 중 하나가 광섬유의 굴절률 분포이다. 광섬유의 굴절률 분포는 광 전송특성을 결정짓는 요소로서 이러한 이유 때문에 좋은 전송특성을 위해 GRIN 광섬유의 개발과 연구가 이루어져 왔다. (중략)

• Optical Science and Technology
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• v.2 no.2
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• pp.31-37
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• 1998

오늘날 삼차원 영상인식에 대한 산업적 수요는 꾸준히 증가하고 있으며, 이에 대응하여 다양한 광계측 원리들이 개발되어 시험되고 있다. 모아레 기법도 삼차원 영상인식을 위해 많은 발전을 거듭하고 있으며 현재 시도되는 다른 광계측 방법들에 대해 다양한 기술적 경쟁력을 갖고 있다. 본 기술소개에서는 삼차원 영상인식을 위해 최근 국내외에서 활발히 진행되고 있는 모아레 기법의 현재의 연구 현황 및 앞으로의 발전 전망에 대해 정리하였다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.1 no.3
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• pp.164-170
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• 1977

Johnson 의 직교이방성재료압출시의 slip line 해를 모아레법으로 검토하였다. 모아레식편상에 slipline 장과 유사한 모아레무늬를 얻어 이론해와 비교하였으며, 모아레무늬 해석법으로 변형후의 상당스트레인 속도분포를 구하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.04b
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• pp.92-96
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• 1993

Modern NC machine tools require a more and more exact monitoring and control of cutting process. A very important parameter is tool wear used to optimize cutting data and to change tools at the right time. In this study, a real-time multi-tool fracture method is proposed for measuring crater from fringe patterns generated by uni-shadow-moire. An optical technique using laser for non-contact measurement of tool fracture is presented. The technology in which the tool is illuminated by a beam of He-Ne laser and then the image of tool fracture CCD camera.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.11
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• pp.7-14
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• 2007