Why is 3D AOI Required During PCB Assembly?

3D AOI is a method of inspecting SMT boards at the component level before soldering, using cameras and computers to map each board in 3D. The system is programmed by our trained assembly technicians using customer-supplied Gerber files, CAD files and our own digital library of component specifications. All of this allows the 3D AOI system to compare component layouts between the assembled PCB and the original CAD design.

The main benefit of 3D AOI is that it reduces errors during pick and place during PCB assembly. If a component is placed in the wrong orientation or position on the board, or if any component is slightly out of position, the 3D AOI system will spot the problem and alert our assembly technicians to this error, the board and the pick and place machine must be corrected in two ways programming. This, combined with our First Article Inspection process, ensures we complete the entire production process.

Why do you need to inspect PCBs?

Inspection is a critical step in any PCB production process. It helps you spot deficiencies so you can correct them and improve your overall operations.
Inspection of the PCB can reveal any defects that may have arisen during the manufacturing or assembly process. It can also help reveal any design flaws that may exist. Inspecting the PCB after each stage of the process enables you to find defects before moving on to the next stage, which saves you from wasting more time and money on defective products. It also helps you find one-off defects that affect one or more PCBs. This process helps ensure consistent quality of your boards and final product.

What is an Optical Inspection System?

Optical inspection systems are best understood as replacements for human QC operators. Optical inspection systems are looking at the original part or assembly and verifying that it is within acceptable parameters. Optical inspection systems can be used at any point in the manufacturing process. Ideally, it would be used both during production and for post-product inspection.
OCR may or may not be part of the optical inspection system. If so, the system can record the serial number of the defective item or identify printed text on the PCB that is defective.

What is an Automated Optical Inspection System?

In short, it provides fully automated inspection using optical systems. The biggest benefit of this process is speed. A 3D AOI system can verify component placement before you move on to the next stage of production and can keep pace with high-volume manufacturing processes. That’s not possible if you rely on teams of human quality control technicians. For example, combining 3D AOI with a part placement system can increase cycle times while reducing defect rates.

What’s more, automated 3D inspection allows you to improve the overall quality of your operations. For example, an automated optical system can inspect the layout of a printed circuit board before melting the solder. Defects in boards and solder can be found before and after reflow. However, preflow is always cheaper because you don’t waste time and energy melting the solder. And you can repair a damaged SMA connector or reposition it without removing the solder. You can find defects early and fix them. You don’t have to worry about the 2D system missing voids in the solder or ignoring missing components. And you don’t have defects escaping and reaching end users, because you rely on statistical sampling.

How does Automated Optical Inspection work?

The automated optical inspection or AOI process has an automated visual inspection unit that scans the equipment, looking for defects. Automated optical inspection can check for various problems. At the most basic level, it works by looking down the board to verify that components are present and in the correct location. Some systems use lasers in addition to lights and cameras that mimic human inspectors.

What is 3D AOI?

3D AOI stands for 3D Automated Optical Inspection. 3D AOI inspects assembled printed circuit boards and other electronic products in three dimensions. This is in contrast to 2D AOI, or two-dimensional automated optical inspection. This usually involves a camera to verify that the item meets quality standards, whether that’s making sure it’s the right size or that the item is in the right place.

3D AOI systems use vertical and side cameras to view all sides of the board. This is why 3D AOI can recognize when components are skewed or flipped. Smarter systems can identify defects such as excessive solder joints and une

ven solder. These systems rely on multi-level lighting to provide sufficient light for the machine vision lens. Circular lighting is ideal because it eliminates the possibility of shadows that could cause false calls. One thing that stands in favor of 3D AOI is that it can identify defects at 10 ppm or less. This reduces the risk of green-lighting an assembled board when there are actually small defects that could cause the assembled board to fail.

We provide PCB inspection services as stand-alone solutions and as part of turnkey build or contract manufacturing services. We’d love to work with you to determine the best inspection process for your needs and provide you with the high-quality PCBA services your project requires.

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