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Comparing 2D and 3D AOI (Automated Optical Inspection)

Various types of Automated Optical Inspection (AOI) systems are available for the thorough inspection of numerous products, especially helpful in keeping up with the rapidly increasing production of printed circuit boards (PCB). Most commonly, 2D and 3D AOI solutions are used. 

The purpose of AOI is to use the optics to capture the images of a PCB and ensure that all of its components are present and appropriately fitted. AOI can easily detect any defect, which helps in the regulation of the quality of the manufacturing process. Moreover, most of the AOI systems can inspect all types and sizes of components present in a PCB.

The original AOI solutions had the capability of handling 2D measurements such as inspecting board and component features and checking their coordinates and measurements. In recent times, 3D AOI has also become very popular because, along with 2D AOI features, it can determine the height dimensions, leading to more precise coordinates.  

1. Types of Defects

Many different problems can occur with a PCB board. These include missing components, displaced or twisted wires, usage of an incorrect component, insufficient soldering, excessively thick joints, bent IC pins, and lack of wetting. To remove these defects, careful inspection of the assembled and soldered components is essential. Both 2D and 3D automatic vision inspection is used to detect faults. 

Nowadays, 3D AOI solutions are preferred most of the time to detect faulty components and soldering because the components have become extremely small over the years. As a result, 2D AOI techniques are often ineffective for finding complex defects. However, for more minor issues like missing wires or components, high-quality 2D AOI is still used because it is comparatively cheaper and gives reliable results. In short, 3D AOI machines can detect more types of defects, such as issues in the hidden ICs, whereas 2D AOI is restricted to the visible components.

2. Height Measurement

Automated inspection is much better than manual production for several reasons. One of the most important reasons why the AOI machine is important is that it is impossible to manually inspect the vast quantity of gloves that are being produced nowadays. It means that manual inspection cannot work for glove inspection, especially during the COVID-19 pandemic, when high-quality gloves are needed in large quantity.

Moreover, machine vision is much better than human vision. There are many minor as well as major possible defects in gloves that may be ignored by the human eye. As a result, there is always a higher risk of quality loss in manual inspections. Using the AOI machine, human errors are eliminated from the glove inspection. Very slight defects can be detected by the machines and therefore, an organization and manufacturers can maintain the high quality of steady glove production.

AOI machines make use of ultraviolet, x-ray, and infrared rays to thoroughly examine the gloves. On the massive production lines that are needed today, AOI machines can inspect thousands of products like masks, PPEs, and gloves in a short amount of time.

3. Limitations of 2D AOI Solutions

In terms of camera resolution, size of sensors, image quality, frame rate, the structure of the angled cameras, options for producing full-resolution HD pictures, and algorithm-based image comparison, 2D AOI is reliable because these features are very commonly used in automated vision inspection. It shows that AOI is more sophisticated and efficient than ever before. It is an extremely reliable method of conducting a post-reflow inspection. 

However, 2D AOI systems have their limitations, which becomes evident when you compare them with 3D AOI solutions. 2D AOI systems cannot examine hidden solder joints, measure the connectors, or optimize defect rates in many cases. In such instances, 3D AOI is used to overcome the limitations of the 2D AOI. 3D AOI provides many other features, along with the functionalities of a state-of-the-art 2D AOI system. Most 3D AOI machines offer all-in-one solutions. They come with the features of 2D machines, along with additional functions.

4. Rate of Defects Detection

Other than the image quality and processing tool, the rate of defect detection and throughput plays a vital role in AOI’s overall performance. The better the features and the algorithms behind the system, the better will be its use in automated defect evaluation. It is easier and quicker for a 3D AOI system to detect defects because they are much faster and efficient than a 2D AOI machine.

5. Automated X-ray Inspection

X-ray inspection is an integral part of any AOI machine as it is used for determining the quality of hidden solder joints. Both 2D and 3D AOI systems support X-ray inspection. However, 3D AOI solutions have more advantages than 2D AOI machines because they are able to perform an inspection of PCB on both sides through X-ray.  

Moreover, the entire components are thoroughly inspected. A 2D AOI machine may not be able to detect a fault in a hidden solder joint, but a 3D AOI machine can easily detect it. The only disadvantage of using an X-ray inspection with a 3D AOI system is that it is expensive with a lower throughput, which can slow down the entire process.

6. Results Reliability

Since 3D technology is more advanced than 2D, it is obvious that 3D AOI machines will eventually replace 2D AOI systems. The new 3D AOI solutions are being developed on a daily basis to reduce the cost of inspection and speed up the process. These modern machines have already eliminated many issues that were present in 2D AOI technology, which means that the results produced through 3D AOI are much more reliable.

7. Overall Features

2D AOI systems use a high-quality camera for the inspection of solder joints, ICs, throughput, and other parts. However, it is limited when it comes to the inspection of hidden joints and measuring of the connectors. An efficient 3D AOI solution is able to inspect the hidden components and function in a better and more advanced method. Since 3D technology also contains the features of 2D technology, users can expect an extensive and accurate inspection of the products using 3D AOI machines.

The Bottom Line

It would be wrong to say that which AOI system is better than the other. Both 2D and 3D automated optical inspection machines have their own set of advantages and disadvantages. The best of implementing AOI solutions is to use a combination of 2D and 3D AOI machines in a balanced way. Wherever 2D AOI is not working, they can use the 3D AOI systems. It will allow the manufacturers to inspect the products quickly, efficiently, and economically. For more information, feel free to get in touch with us. 

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