Method for calculating theoretical center of welding spot of BGA image

Abstract

The invention discloses a method for calculating a theoretical center of a welding spot of a BGA image, and the method comprises the following steps: 1, obtaining the BGA image, carrying out welding spot analysis of the BGA image, and obtaining a target point set corresponding to an actual welding spot; 2, establishing a mathematical model of physical distribution of a welding spot array on the BGA chip by adopting an improved grid type template generation method to obtain a template point set; 3, establishing an affine model according to the geometrical relationship, establishing mapping fromthe template point set to the image point set through the affine model, and calculating a matching relationship between the point sets according to the mapping; and 4, performing point set registration according to the matching point pairs obtained in the step 3 to minimize a distance function between a theoretical center and an actual center, and outputting the theoretical center. According to the method, the BGA chip images are paired in an overall mapping mode, and the method has the advantages of being good in positioning effect and accurate in result.

Description

technical field [0001] The invention relates to the field of image visual detection, in particular to a method for calculating the theoretical center of solder joints of a BGA image. Background technique [0002] BGA packaging technology is an important integrated circuit packaging technology, which is called ball grid array packaging technology. It is often used in the packaging of CPU chips in portable computers and is a reliable way to connect chips and external circuits. Because of its many pins and small spacing, BGA components have high production costs and require a high yield rate. Therefore, in automated production, it is necessary to design a computer vision system for detecting BGA chips to help improve production quality. This system has requirements for algorithms with high precision, high reliability, strong robustness and high efficiency. [0003] The existing practical method is the point pattern matching algorithm, which aims to establish a standard point s...

AI Technical Summary

Problems solved by technology

From the results, using the relative position as a feature can solve the point matching problem between different coordinate systems, but when the number of solder joints on the chip is large, calculating the matching degree one by one will consume additional time and affect the real-time performance of the algorithm.

Moreover, when solder joints are missing on the chip, there will inevitably be mismatched point pairs, which will affect the accuracy of the results

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