PCB Technical - How to check the quality after PCB soldering, and what are the methods

Inspection after PCB soldering is very important for companies and customers. In particular, many companies have strict requirements on electronic products. If they are not inspected, performance failures are prone to occur, which affects product sales, and also affects corporate image and reputation. So, how to check the quality of PCB after soldering?

How to check the quality after PCB soldering, and what are the methods

One, PCB triangulation method

What is triangulation? That is, the method used to check the three-dimensional shape. At present, the triangulation method has been developed and used and a device capable of detecting its cross-sectional shape has been designed. However, because this triangulation method is incident from different light sources and different directions, the observation results will be different. Essentially, all objects are inspected through the principle of light diffusion. This method is the most suitable and effective. As for the situation where the welding surface is close to the mirror condition, this method is not suitable and it is difficult to meet the production requirements.

2. Light reflection distribution measurement method

This method mainly uses welding parts to detect decorations, incident light inward from an oblique direction, set up a TV camera above, and then inspect it. The most important part of this method of operation is how to know the surface angle of the PCB solder, especially how to know the illuminance information, etc. It is necessary to capture the angle information through various light colors. On the contrary, if it is irradiated from above, the angle measured is the reflected light distribution, and it is enough to check the inclined surface of the solder.

Three, change the angle for camera inspection

How to detect PCB after soldering? To use this method to detect the quality of PCB after soldering, there must be a device that can change the angle. This device generally has at least 5 cameras, multiple LED lighting equipment, uses multiple images, and uses visual conditions for inspection, which is relatively reliable.

4. Focus detection and utilization method

For some high-density circuit boards, after PCB soldering, the above three methods are difficult to detect the final result, so the fourth method is needed, that is, the focus detection method. This method is divided into multiple, such as the multi-segment focus method, which can directly detect the height of the solder surface to achieve a high-precision detection method. If 10 focus surface detectors are set at the same time, the focus surface can be obtained by seeking the maximum output to detect The location of the solder surface. If it is detected by the method of irradiating the object with a fine laser beam, as long as the 10 specific pinholes are staggered in the Z direction, the lead device with a pitch of 0.3mm can be successfully detected.

The above four methods are some of the inspection methods used by PCBA processing manufacturers to conduct external inspection of PCB boards.