In a conventional visual inspection application, a camera is positioned above the PCB board to obtain an image of the printing position and to transmit the image to the processing system of the visual inspection device. There, the image analysis software will compare the captured image with the reference image stored in the same location in the device memory. In this way, the system can confirm that the applied solder paste is more or less. The same system can also reveal whether the solder paste on the pad location is aligned.
When excess solder paste is applied on the surface of the stencil, the vision system can be used to detect if the slit is clogged with solder paste or if tailing is occurring. After a defect is detected, the device can alert the operator that a problem exists that requires repair. The inspection of printed templates can also provide users with very useful data on print quality and consistency.
In some specific cases, the vision system can be used to detect solder paste on the solder paste the height or size of the size, and sometimes may only use off-line detection system to do these things. The use of this procedure means that a corresponding stacking degree is formed in a given printing template to confirm whether the volume of the solder paste is missing on the same pad.