A method for calculating the theoretical center of solder joints for bga images

Abstract

The invention discloses a method for calculating the theoretical center of a solder joint of a BGA image. The method includes the following steps: Step 1. Obtain a BGA image, and obtain a target point set corresponding to an actual solder joint by performing solder joint analysis on the BGA image; 2. Using the improved mesh template generation method, establish a mathematical model of the physical distribution of the solder joint array on the BGA chip, and obtain a template point set; Step 3, establish an affine model according to the geometric relationship, and establish template points through the affine model. Set to the mapping of the image point set, and calculate the matching relationship between the point sets according to the mapping; Step 4, carry out the point set registration according to the matching point pair obtained in step 3, so that the distance function between the theoretical center and the actual center Minimize, output the theoretical center. The present invention pairs BGA chip images by means of overall mapping, and has the advantages of good positioning effect and accurate results.

Description

technical field [0001] The invention relates to the field of image visual inspection, in particular to a method for calculating the theoretical center of a solder joint of a BGA image. Background technique [0002] BGA packaging technology is an important integrated circuit packaging technology, the full name of which is ball pin 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. BGA components have high production costs and require high yield due to their many pins and small spacing. Therefore, it is necessary to design a computer vision system for detecting BGA chips in automated production to help improve production quality. The system has high precision, high reliability, strong robustness and high efficiency requirements for algorithms. [0003] An existing practical method is the point pattern matching algorithm, which aims to establish the 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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