Precision measurement using 3-D machine vision for BGA inspection

Pao Yue-kong Library Electronic Theses Database

Precision measurement using 3-D machine vision for BGA inspection


Author: Li, Wun-yin
Title: Precision measurement using 3-D machine vision for BGA inspection
Year: 1999
Subject: Electronic packaging
Ball grid array technology
Moire topography
Moire method
Three-dimensional display systems
Computer vision -- Industrial applications
Hong Kong Polytechnic University -- Dissertations
Department: Multi-disciplinary Studies
Dept. of Manufacturing Engineering
Pages: ix, 96 leaves : ill. ; 31 cm
Language: English
InnoPac Record:
Abstract: Ball grid array (BGA) inspection is to measure the geometric specifications of BGA packages. It is a challenge in semiconductor production. The primary difficulty is the measurement of solder ball shape and co-planarity. It is a non-contact, high precision, high volume, 3-dimensional problem. Moire topography techniques have been widely used as simple and powerful tools for 3-D shape analysis and measurement. Among these, shadow moire method is suitable for contouring the solder ball of BGA. It can give a 2-D interferogram pattern that contains 3-D information of solder ball. In this work, moire topography technique is applied to the BGA inspection. This is the first time that shadow moire, automatic fringe analysis and surface reconstruction techniques are applied in BGA inspection. Since the solder balls are the sphere matrix, and the sizes are limited, it is easy to produce moire pattern onto them by using the experimental configuration shown in Figure 3-01. Through a computer vision system, the pattern is captured and digitized. Using 1-D Fourier transform method, phase value is extracted from fringe pattern. After unwrapping, the 3-D information is obtained. Through these information, the solder ball size, position and co-planarity can be given. BGA inspection can be implemented. This work also emphasizes the fringe analysis process. Using digital image processing techniques, the 3-D information can be extracted from the 2-D interferogram image automatically. A computer simulation and some experiment are present in this work to verify the theories. An actual case of BGA co-planarity measurement is introduced.

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