In SMT, every PCBA has been inspected by AOI. Is manual visual inspection still required?

Last week I did a questionnaire survey---In SMT, every PCBA has been inspected by AOI. Is manual visual inspection still required?

I also received votes from many friends. Some friends answered YES, and some friends answered NO! There are also neutral attitudes, depending on the specific situation!

Regarding the topic of the poll one week ago, I would like to express my own thoughts here. If you have more ideas or suggestions, you can share them and we can learn together!

 In fact, my answer to this topic is YES! As for why, I think I will explain the reasons from two aspects!

The first is AOI itself, and the second is MVI(manual visual inspection)!

AOI(Automatic Optical Inspection)

The principle of AOI detection and the use of optical means to obtain the graphics of the object to be tested, generally obtain the illumination image of the object to be tested through a sensor camera and digitize it, and then use some method to compare, analyze, inspect and judge, which is equivalent to automating and intelligentizing manual visual inspection. Although AOI has higher efficiency than manual inspection, it is after all obtained through image acquisition and analysis and processing. The relevant software technology for image analysis and processing has not yet reached the level of the human brain. In some special cases in actual use, AOI's misjudgment and missed judgment are inevitable!

At present, there are problems in the use of AOI:

1. The process requirements and standards for excessive tin, insufficient tin, offset, and skew are defined differently, which can easily lead to misjudgment;

2. The capacitance values are different, but the size and color are the same, which can easily lead to missed judgments;

3. Different character processing methods cause acute judgments, and the accuracy varies greatly;

4. Most AOIs have ambiguous understandings of cold solder joints;

MVI(Manual Visual Inspection)

In PCBA processing, even if AOI (automatic optical inspection) technology is used, manual visual inspection is still required. Manual visual inspection has the following four advantages:

1. Improve the qualified rate of shipment: Manual visual inspection can effectively reduce product production defects, thereby improving the qualified rate of shipment. Although AOI technology can detect most defects, manual visual inspection can further discover problems that AOI may miss and ensure product quality;

2. Ensure product quality: Manual visual inspection is an important link in ensuring product quality and can prevent defective products from entering the market. Through manual visual inspection, defective products in the production process can be discovered in time, and measures can be taken quickly to remedy the situation and prevent defective products from entering the market;

3. Reduce production costs: Although AOI technology has improved the level of automation and reduced some labor costs, manual visual inspection is still indispensable in some links. Through manual visual inspection, production efficiency and the first inspection pass rate can be further improved, thereby reducing production costs and improving corporate competitiveness;

4. Rapid introduction of new products to the market and development of new products: Manual visual inspection helps to quickly introduce new products to the market and develop new products. Through manual visual inspection, new products can be discovered in time;

This is my answer and why. Do you have better ideas or suggestions? Looking forward to your sharing!