The biggest disadvantage of AOI is that there are some places where grayscale or shadows are not very obvious, and it is easier to misjudgment. These may be distinguished by different colors of lights, but the most troublesome is those that are caused by other parts.SunzonTech\'s smt aoi machines use cutting-edge technology to guarantee high speed and precision with FPC special detection logic and defect analysis. Covered components and solder joints located under the components, because traditional AOI can only detect the places that can be reached by direct light, such as the ribs of the screen frame or the components under the edges, often because AOI cannot detect them. Missed the past.
Therefore, the general circuit board assembly production line not only uses AOI to ensure its assembly quality, but also usually has to undergo ICT (In-CircuitTest) and functional test (FVT) inspections. Some production lines will add an additional AXI (AutomaticX-ray Inspection) , Use X-Ray to check the quality of the solder joints (such as BGA) under the components along the line.
In addition, because optical inspection is subject to factors such as light, angle, resolution, etc., the following shortcomings can only be detected under certain conditions, but it is difficult to achieve a 100% detection rate.
If it is a wrong part with a different shape, or a part with a different print on the surface, AOI should also be able to check it out. But if the appearance is not significantly different, and there is no surface printing, such as resistors and capacitors below 0402 size, these are difficult to detect with AOI.
This must also depend on whether the part itself has a symbol indicating the polarity of the part, or the difference in appearance and shape can be implemented.
Severe foot curling can be judged by the difference in the brightness of light reflections, but slight foot curling can be somewhat difficult. Severe foot deformation can also be easily detected by using AOI. Slight foot warping must depend on the situation. This usually depends on the strictness of the parameter adjustment and the experience value of the engineer or operator.
Generally speaking, the tin bridge is easy to check, but if it is a tin bridge hidden under the part, it is difficult to find. For example, the tin bridge of some connectors occurs at the bottom of the component body, and there is no way to detect it using AOI at this time.