Method for detecting defects of printed circuit board (PCB) based on skeleton extraction and range conversion

Abstract

The invention discloses a method for detecting defects of a printed circuit board (PCB) based on skeleton extraction and range conversion. The method comprises the following steps of: checking an index table to extract a single-pixel skeleton; deleting skeleton branches; and searching for range value domain abnormity, and classifying PCB defects according to abnormal conditions. According to the method for detecting defects of the PCB based on skeleton extraction and range conversion, useless points can be deleted on the premise of not influencing the quantity of connected domains by extracting the single-pixel skeleton in a way of checking the index table, and the extracted skeleton is of a single pixel and has high generality and high practicability; skeleton branches are deleted, and range value domain abnormity is searched, so that calculation deviations can be reduced without influencing the speed and accuracy of skeleton tracking; and branches can be deleted, so that the calculation amount of skeleton search is reduced, and the efficiency of defect identification is increased.

Description

Technical field [0001] The invention relates to the field of detecting defects of printed circuit boards, in particular to a method for detecting defects of printed circuit boards based on skeleton extraction and distance conversion. Background technique [0002] Printed circuit board is the main component of various electronic products, known as the "mother of electronic products". It is required for any electronic equipment and products, and its performance greatly affects the quality of electronic products . Almost every kind of electronic equipment is inseparable from PCB, from electronic watches and calculators, to aerospace, military weapon systems, etc., which contain all kinds of PCB boards of different sizes. In recent years, with the continuous improvement of production technology, PCBs are rapidly developing in the direction of ultra-thin, small components, high density, and fine pitch. This trend has brought many challenges and difficulties to quality inspection. Th...

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Problems solved by technology

The advantage of the reference comparison method is that it is conceptually intuitive and the circuit implementation is simple. The disadvantage is that it requires precise alignment of the spatial positions of the PCB to be inspected and the standard PCB, otherwise there will be more false alarms; the second is the non-reference method, which is to detect whether the PCB meets the design requirements. The rules are mainly for dimensional verification, that is, to check whether the dimensions of conductors and pads meet the width and gap required by the design standards. Anything that does not meet the requirements of the design rules is considered a potential defect. Its advantage is that no reference is required. PCB, so it does not need to be aligned, the disadvantage is that it cannot detect defects that meet the design size, such as missing a wire on the PCB, etc.

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