An Optical Inspection System for the Solder Balls of BGA using Support Vector Machine Classification
In this paper, the Support Vector Machine (SVM) is utilized to classify the defective solder ball of ball grid array (BGA) so as to promote the accuracy and efficiency of the optical inspection. The terms of inspections include the ball displacement, the ball over scale, the ball undersize, the ball absence, and ball bridging. There are two step of the SVM processing: the training step and the real testing step. The SVM is more efficiency because of the calculation in testing step is no relation to the number of the input vector. As this point, SVM is fit to build up the high dimension input recognize system such as BGA inspection. From the real testing results, the Support Vector Machine is proved to properly identify and classify the shape defects. The two dimensional BGA optical inspecting system is implemented by Visual Basic as the developing tool incorporated with the Halcon's function which is the database of the image processing on Windows operation system. For the development of the processing procedure of the automatic optical inspecting system with the designed lighting system, the precise geometrical information of the solder ball is evaluated by the sub-pixel method to identify the shape of solder ball and its location under the BGA board is offset and rotated at any angle.
A Statistical Approach to Three-Dimensional Shape Inspection of Micro-Solder Balls
This article presents an optical technique for the three-dimensional (3D) shape inspection of micro-solder balls used in ball grid array (BGA) packaging, before attaching them to a board or film. This technique uses an optical source comprising spatially arranged light-emitting diodes (LEDs), and the results are derived based on the specular reflection characteristics of the BGA balls. A vision system is designed to acquire the reflected image from the micro-solder balls. For shape inspection, the locations of the LED point-light-source reflections are determined via image processing, and defects in 3D BGA shapes are detected using statistical information of the relative positions of multiple BGA balls captured in the images. Experiments were conducted to validate our proposed method, and the results revealed that it allows for simultaneous inspection of multiple BGA balls placed arbitrarily in a glass dish, without the need for precise ball-position control.
Current Issues in English Education for Young Learners in East Asia
Recognizing English as an increasingly powerful lingua franca, many governments in East Asia have implemented English-language education at the...