Registration method of special shaped elements and high-density packing components in printed circuit board

Abstract

The invention discloses a registration method of special shaped elements and high-density packing components in a printed circuit board. The method comprises the following steps: firstly, rough positioning: obtaining a rough transformation parameter (m, n, beta) through adopting an SIFT (scale-invariant feature transform) registration method; and secondly, fine positioning: performing inverse transformation on an image I (x, y) to be registered through the rough transformation parameter (m, n, beta) to obtain g (x, y), calculating a minimum energy equation E between g (x, y) and a template image f (x, y), solving partial derivatives of all orders of E and ensuring the partial derivatives are 0, solving a transformation parameter (m, n, theta), ensuring that m' is equal to m plus a, n' is equal to n plus b, and beta' is equal to beta plus theta, calculating energy E under a transformation relation (m', n' and beta'), judging whether E is lower than a set value, performing the next iteration if E is not lower than the set value, finishing the iteration process if E is lower than the set value, and taking m' as a final translation parameter in the x direction, n' as a final translation parameter in the y direction and beta' as a final rotation angle. Compared with the prior art, the method realizes high-precision sub-pixel level positioning, and has high robustness to lighting transformation and noise.

Description

technical field [0001] The invention relates to the field of identification and positioning in precision electronic assembly, in particular to a registration method for special-shaped components in printed circuit boards and high-density packaging components. Background technique [0002] At present, Surface Mount Technology (SMT) has affected the product level in various fields such as communications, home appliances, computers, networks, automation, aviation, aerospace, and navigation, and is an important part of today's microelectronics technology. Among them, visual inspection is a necessary process for surface mount. It separates components of various shapes and specifications from the background, and the focus is to accurately determine the position and angle of the components. Provide high-precision position and angle compensation information. The position or angle offset of components can be judged through image registration. [0003] Image registration is a fronti...

AI Technical Summary

Problems solved by technology

The error of simply using the SIFT algorithm is relatively large, and it cannot meet the actual production requirements. Therefore, based on the SIFT detection results, a minimum energy sub-pixel method is proposed to further accurately position the two images to be registered.

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