Used AOI MachinesLearn more about how AOI equipment from Capital Equipment Exchange may benefit you. The role of automated optical inspection (AOI) systems is crucial for printed circuit board assembly. It’s one of several types of tests that are used in the manufacturing of PCBs, along with in-circuit and flying probe tests. Together they ensure the process is free of defaults and production can run efficiently, keeping costs down and revenues up.

Understanding The AOI Process

AOI is (as its name implies) a visual or “optical,” inspection of a circuit board. Images are taken via camera or X-ray. Once an image is taken, the test may work in several different ways, including template matching, pattern matching, and statistical pattern matching.

  • Template matching is when the automated optical inspection machine compares the image it takes with the image from a "golden board,” AKA the “known good board” (KGB).
  • Pattern matching is when the AOI equipment stores information about both good and bad boards and matches the new image to one of those patterns during the inspection.
  • Statistical pattern matching is similar to pattern matching but is more advanced because it uses statistics to store the results of several boards and possible failures. It can allow for small deviations that may not stop the PCB from working.

AOI equipment may have one camera or multiple cameras. They also use different types of lighting, such as LED, Fluorescent, Infra-red, or Ultra-violet. They can also take still images or video. The process varies and depends on production needs.

AOI Systems & Production

The PCB assembly process varies greatly in complexity. A manufacturer may use automated optical inspection systems at several points during the production process. These systems may be used inline or offline. Some of the most common inspection points include:

  • Bare Board Inspection
  • Pre-Reflow
  • Solder Paste Inspection (SPI)
  • Post-Reflow

Inline Vs. Offline AOI

Inline AOI inspection means the machines are used in the mass production line. This is seen with high-volume, low-mix manufacturing (HVLM). HVLM means the same type of board is assembled without any changes. Inline is also used when a customer demands inspection of every board.

Offline AOI inspection means the equipment is being used outside of a significant production line process. It is most often used for prototypes and first inspections and seen in high-mix, low volume (HMLV) manufacturing. This means the production of fewer boards and more diversity, requiring programming changes.

Both inspection options check for similar defects:

  • Open Circuits
  • Solder Bridges
  • Solder Shorts
  • Excess Solder Paste
  • Missing Components
  • Misaligned Components

Save With Used AOI Equipment

Purchasing used AOI equipment is one way to significantly reduce initial costs and run printed circuit board assembly lines efficiently. When it comes to buying used automated optical inspection machines and systems, Capital Equipment Exchange offers invaluable expertise. With decades of experience, we can help you asses the type or AOI equipment you need for your production process.

We also carry restored AOI systems from top brands in the industry.

  • Koh Young
  • YESTech
  • Breuckmann
  • Nordson
  • Omron

Connect With The Experts

Contact us at Capital Equipment Exchange today to learn more about the type of automated optical inspection systems we recommend or browse our current inventory. We offer demonstrations of all equipment and guarantee that each machine is production-ready.