Method for detecting planeness of PCB based on network projection

Abstract

The invention provides a method for detecting the planeness of a PCB based on a network projection. The method comprises the steps that the PCB is put on a horizontal operating platform; a light source over a dam board, and the dam board are installed over the PCB; a camera is installed in an included angle of 60 degrees formed between a side and the horizontal operating platform; the light source projects the shadow of a standard grid on the dam board on the PCB by the dam board; the camera takes a picture of the shadow of the grid on the PCB from the included angle of 60 degrees. An analysis device comprising a picture processing device and a data processing device analyses the picture taken by the camera so as to decide whether the PCB meets the requirement of the planeness. The method provided by the invention simply and accurately realizes the detection of the planeness of the PCB.

Description

technical field [0001] The invention relates to the field of PCB (printed circuit board), in particular to a method for detecting the flatness of a PCB board based on grid projection. Background technique [0002] With the rapid development of microelectronics technology, the current electronic digital products, such as mobile phones, tablet computers, notebook computers, etc., are developing in the direction of thinner and thinner. Due to the thinner and thinner requirements of product design, the components on the PCB motherboard used inside the product The density is getting higher and higher, and components with hundreds or even thousands of soldering pins are also configured on the PCB board. Devices with such a large number of pins currently use SMT surface mount technology. The flatness of the pin plane is relatively high. If the flatness of the PCB board does not meet the requirements, there will be concave and convex areas on the board surface, so that the pins will...

AI Technical Summary

Problems solved by technology

[0002] With the rapid development of microelectronics technology, the current electronic digital products, such as mobile phones, tablet computers, notebook computers, etc., are developing in the direction of thinner and thinner. Due to the thinner and thinner requirements of product design, the components on the PCB motherboard used inside the product The density is getting higher and higher, and components with hundreds or even thousands of soldering pins are also configured on the PCB board. Devices with such a large number of pins currently use SMT surface mount technology. The flatness of the pin plane is relatively high. If the flatness of the PCB board does not meet the requirements, there will be concave and convex areas on the board surface, so that the pins will not fully contact the pads on the PCB board during soldering, resulting in empty soldering, Welding, etc., so before welding, the flatness of the PCB board needs to be tested

[0003] The current detection of PCB flatness mainly relies on manual visual inspection. This detection method is too subjective and cannot guarantee the consistency of flatness detection standards. On the other hand, the sensitivity of artificial visual inspection is low and cannot guarantee the accuracy of PCB flatness requirements

[0004] A method for detecting the flatness of a PCB board is provided in the related art. A laser distance measuring device is arranged vertically above the PCB board. By moving the PCB board horizontally, the distance from the laser distance measuring device to multiple points on the board surface is measured. These distances are analyzed to determine the flatness of the board surface. However, due to the different reflectivity of various materials to the laser, the distance measurement value of the laser sensor is greatly affected by the surface characteristics of the measured object. Due to the spread of various materials on the PCB board, Such as metal pads, insulating varnish, printing ink, etc., which make the error of this detection method larger

[0005] The fixed-point ranging method in the above technology will cause large errors due to the large number of vias on the PCB board.

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