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Proceedings Paper

Grating projection Moire interferometry for high-speed 3D inspection of mesoscale objects
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Paper Abstract

In today's manufacturing of PCBs (Printed Circuit Boards), there is an increasing demand on 3-D inspection of mesoscale objects for quality assurance. Two representative examples are the solder pastes on printed circuit board and bumps on FC-BGA (Flip Chip - Ball Grid Array) substrates, of which heights and volumes are precisely controlled to avoid defects in direct surface mounting of semiconductor chips. Despite the demand, no suitable 3-D inspection techniques are available yet, especially for high speed real time quality control of FC-BGA bump heights. Well-established monochromatic or white light interferometry is not easy to produce large measuring ranges up to a few millimeters and become robust to the vibrations on factory floor, while widely-used optical triangulation techniques with structured light illumination fail to provide the measurement precision usually required down to a few micrometers. Moire interferometry may be considered as a hybrid approach that combines the two distinct principles of the monochromatic light interferometry and optical triangulation. Thus, when appropriately configured, moire interferometry is capable of filling the gap between the two principles in terms of measurement range and precision. In this paper we propose a new method of 3-D inspection of meso-scale objects, which is in fact based upon the principle of grating projection moiré interferometry. This method projects a series of line patterns with predetermined phase shifts onto the target object and detects phase information leading to construction of 3-D profiles. Making the most of modern computer vision and digital signal processing technology allows for high speed measurement of 0.6 sec per 15mm×15mm field of view, with a resolution of 1μm for all three (x,y,z) axis.

Paper Details

Date Published: 18 June 2007
PDF: 8 pages
Proc. SPIE 6616, Optical Measurement Systems for Industrial Inspection V, 661625 (18 June 2007); doi: 10.1117/12.726020
Show Author Affiliations
Sang-Yoon Lee D.D.S., IntekPlus Co. (South Korea)
Min-Gu Kang, IntekPlus Co. (South Korea)
Seung-Woo Kim, Korea Advanced Institute of Science and Technology (South Korea)

Published in SPIE Proceedings Vol. 6616:
Optical Measurement Systems for Industrial Inspection V
Wolfgang Osten; Christophe Gorecki; Erik L. Novak, Editor(s)

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