PCB Holes Detection System Research And Implementation

With the rapid development of electronic technology and computer technology, the PCB circuit board is used more and more widely. At present, the package of electronic components is getting smaller and smaller, the integration of circuit board of PCB is also getting higher and higher, with that, more and more holes are on the PCB board and the hole density is increasing. If the drill partial or leakage drill were not found timely, it would lead that the test time of the finished PCB increases greatly, or even the whole PCB scraps. So manufacturers in order to improve the qualification rate of products,the detection requirements of PCB hole location on bare plate is higher and higher. However, at present the majority of manufacturers using artificial visual or two dimensional sampling method obviously can not meet the requirements of fast and accurate detection, while the foreign mature PCB hole detection products are expensive, that keeps some enterprises away.Therefore, this paper based on the situation, puts forward a kind of hole diameter detection device which is based on machine vision,it can be good to make up this gap and has important practical value.PCB hole location testing equipment is an intelligent PCB drilling automation testing equipment.The device can detect high-precision PCB hole position and aperture, the precision can reach 10 um, and the maximum detection PCB size is 500 x720 mm.For test of PCB, it is in the bare copper on the PCB after drilling, plate hole only, the relatively small aperture(around 0.1 mm holes), with higher accuracy(10 um), size is a little big and the hole number is around 25000.Adopting the line scan camera after comprehensive consideration,we do several times scanning to get more than one local images of the entire PCB board,and image preprocessing, image recognition algorithm for each image, and then the bilinear transform for each image, matching them with the standard hole location information.Then,making fast splicing of the measured images’ hole location information, getting the information of the hole location and aperture all on the actual PCB.Finally,the borehole with standard file parsing out information of hole location and aperture after sorting with the sorted information of actual image recognition, use a corresponding matching algorithm to change the first up, and calculate the hole location error and aperture error of each hole.Extra drill and leakage drill will be listed and saved, and it can provide the reference for the user to confirm, and make convenient for processing of subsequent analysis.Experiments show that,the system used the algorithm with good stability,can meet the requirements, achieve rapid and accurate matching, and detect the location information of extra drill and leakage drill holes.