SMT is an electronic assembly technology. It originated in 60s. It was initially developed by IBM and became mature in the late 80s. This technology is to install electronic components, such as resistors, capacitors, transistors, integrated circuits, etc. on printed circuit boards, and form electrical connections through brazing. The biggest difference between SMT and through hole inserting technology is that the surface mount technology does not have to reserve the corresponding perforation for the pin of the element, and the element size of the surface mount technology is much smaller than that of the through hole inserting technology. Using the surface mount technology can increase the overall processing speed, but because of the miniaturization and the increase of the density of the parts, the risk of the defect of the circuit board is increased, so the error detection has become a necessary part in the circuit board manufacturing process with any surface mount technology.