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The issues with AOI inspection in PCB assembly

2020-06-26

In the actual production of the current PCB assembly factory, although AOI has higher efficiency than manual visual inspection, after all, the results are obtained through image acquisition and analysis processing, and the related software technology of image analysis processing has not yet reached the level of the human brain. Therefore, in smt patch processing, some special circumstances, such as AOI misjudgment and missed judgment, are inevitable. At present, the main problems of AOI's inspection after smt patching are as follows:


 

1. The definition of the process requirements for more tin, less tin, offset, and skew is different, which can easily lead to misjudgment.

 

2. Capacitance values are different and the specifications and colors are the same, which can easily lead to missed judgment.

 

3. Different character processing methods cause large differences in polarity judgment accuracy.

 

4. Most of the AOI's understanding of virtual welding is ambiguous, resulting in missed judgment.

 

5. There is a problem of detection of Pingyang, shielding cover and shielding point.

 

6. It is impossible to detect solder joints where BGA, FC and other flip-chip components are not visible.

 

7. Most AOI programming is complicated, cumbersome and has a long adjustment time. It is not suitable for scientific research units, small OEM factories, and production units for multi-spec small batch products.

 

8. The detection speed of most AOI products is slow, and the speed of a few AOUI using scanning method is faster, but the rate of misjudgment is higher.

 

9. Some AOIs with lower scores cannot be used for OCR character recognition detection.

 

In response to the problems found above, in addition to adding quality inspection personnel, PCBA factory also need auxiliary equipment. AOI not only has online AOI, but also offline AOI equipment. Therefore, we need to attach great importance to the quality control link. 


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