Fast tilt correction method for QFN chip pin image

Abstract

The invention discloses a fast tilt correction method for a QFN chip pin image. The fast tilt correction method comprises the following steps: (1) collecting the QFN chip pin image, and carrying out filtering and binarizing treatment; (2) extracting the contour of a central bonding pad of the chip image by using a polygon approximation method; (3) proposing an improved Harris corner detection algorithm, and acquiring contour vertexes; (4) carrying out straight line fitting on the vertex with a farthest distance by utilizing a least square method, and taking a straight line as an angle identification direction; and (5) rapidly correcting the chip pin image and removing white edges by taking a centroid coordinate of the image as a rotation center. The correction method provides a certain theoretical basis for correcting a QFN chip more quickly and accurately, and improves the visual detection efficiency of QFN packaging defects.

Description

technical field [0001] The invention belongs to the field of image processing algorithm design, and proposes an improved Harris corner detection algorithm, combined with a polygonal approximation method, to design a method for fast tilt correction of a pin image of a QFN chip. Background technique [0002] QFN (Quad Flat No-lead Package) is a leadless package, which is square or rectangular. It uses the middle pad at the bottom of the package to conduct heat, and there are conductive pads around the periphery of the package around the middle pad for electrical connection. There will be a certain dimensional error in the production process of QFN chips, so there will be a margin when manufacturing the loading port of the tray, but this will cause tilting when the chip is placed, which will affect the visual inspection of the chip packaging quality. [0003] At the same time, due to the small size of the chip, the manual detection and identification method with low accuracy is...

AI Technical Summary

Problems solved by technology

There will be a certain dimensional error in the production process of QFN chips, so there will be a margin when manufacturing the loading port of the tray, but this will cause tilt when the chip is placed, which will affect the visual inspection of the chip packaging quality

[0003] At the same time, due to the small size of the chip, the manual detection and identification method with low accuracy is far from meeting the requirements of the current chip production. It is urgently needed to develop an effective technology that can quickly and accurately correct the chip image. solved problem

The research on QFN chips in the prior art mainly focuses on QFN chip structure improvement, manufacturing process, appearance inspection and QFN chip defect detection. At present, no literature and patents related to the rapid correction method of QFN chip image tilt have been found. Therefore, Designing a fast tilt correction method for QFN chip pin images to fill in the lack of existing research in this area is particularly important for improving the efficiency of visual inspection of QFN package defects

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