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《How to use SMT Line to produce a printed circuit board? (6)》
AOI is the abbreviation of Auto Optical Inspection. It is an optical recognition system for detect the quality of PCB parts after SMT assembly. Also to seeing if the solder paste fit the inspection standard. The biggest advantage of AOI is to replace the SMT’s manual inspection by detecting the assembly mistakes and disadvantages automatically. But the blind spot of AOI is unable to inspect the solder pasting for the bottom of components, and the object under the surface.

The AOI can check out tombstone, missing parts, displacement, polarity, solder bridge, air welding. But it cannot judge false welding, BGA soldering, wrong components, wrong polarity, lead lift, and insufficient solder. In conclusion, AOI can provide immediate feedback for SMT preliminary analysis and improve it yield rate. But it will cause misjudge and false reject easily in object of poor light, poor angle, and dark shadow.

《How to use SMT Line to produce a printed circuit board? (3)》

Into the pasta soldering phase, the paste melting and reform the surface mount and electronics components. Meanwhile the solder printing must be maintain in appropriate amount, exact angle, and correct speed. After that the circuit board will into the High-Speed pick & place machine, which is a SMT components placement system. The machine can place the small volume of electronics components in high speed and high precision way, like capacitors, resistors, and integrated circuits onto the circuit board.

In the early 1980’s the high speed pick and place machine separate in two parts: the chip shooter and the machine itself. But the huge cost and inflexibility make them develop new type of all-in-one module, multi-head, gantry machine, that can quickly swapped to different modules. Nowadays, the latest machines even has touchscreen, e-platform, graphical interface, linear motor driven gantry, and the components range can be from 01005 to 80x70 mm, board size up to 600x800 mm, and can use in many industry, such as: consumer goods, electrical industry, medical, automotive equipment.