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AOI – Why is it favored during the PCB Manufacturing -II

 Jan 29, 2018

It has taken a lot of time for the Automated Optical Inspection (AOI) to become one of the favored methods in PCB manufacturing. This method helps ensure fast, accurate, and effective inspection of the electronic assemblies. The previous post discussed several aspects of this technique, including its proper utilization, requirement in the modern PCB production lines, etc. This last installment of post, we will discuss various other aspects of AOI.

Types of Lighting Systems Used for AOI

Illumination of the areas on the PCB is an important requirement in the AOI. The lighting system used for illumination helps identify defects easily. Although most AOI systems use a specific pattern of lighting, still the following are some popular types:

  • LED Lighting: Most new AOI systems use LED light systems for illumination. Many times, LED light sources used in the AOI system may include green, white, and red LEDs. Although considered a stable form of lighting, still it offers flexibility to control the level of lighting. These lighting systems may suffer from reduction in illumination, over the time, which can be easily mitigated by increasing the current of the circuit.
  • Fluorescent Lighting: This is another popular form of lighting used by AOI systems. This lighting also helps identify defects on the finished printed circuit board. These lighting systems require frequent replacement, because the fluorescent bulbs degrade over the time. Otherwise, the AOI systems may be subjected to constantly varying levels and quality of lighting.
  • Ultra-violet and Infra-red Lighting: These lighting sources are rarely used. Ultra-violet and infra-red lighting are basically used to enhance certain manufacturing defects on the PCB.

Thus, the choice of the right lighting system can make a big difference to the results. The angle of illumination is another important aspect in the AOI. This is because tall components may block the light from reaching short components on the PCB. Some complex PCBs or PCBA’s designs may require illumination at lowest angles. This is why the demand for AOI systems with capability of illumination at various angles is increasing.

Various Types of AOI Camera Configurations Used for Image Capture and Analysis

Image capturing is one of the important features of the AOI. It is performed by a sophisticated image capturing system. The system captures image of the PCB assembly, which is then analyzed by the software in the AOI. The following are some important types of camera configurations used by PCB production lines:

  • Single-camera Systems: Most AOI systems utilize a single-camera architecture. These systems can capture images, which help identify misaligned or missing components on the finished printed circuit board. These systems are also ideal for inspecting solder joints in the PCB.
  • Multiple Camera Systems: Many times, AOI systems use multiple camera systems, which provide them an all-round view. For example, there might be side view camera systems, which offer view of rear, front, right, and left viewing angles.

It is important that a printed circuit board production line is well-equipped with an inspection system that ensures the quality of the PCBs produced. This is the only way a PCB manufacturer can improve his reputation and reliability in the market. Both the posts, discuss various beneficial aspects of AOI, which has made it one of the important types of inspection mechanisms in the highly competitive PCB manufacturing industry.  For more information about Automated Optical Inspection (AOI) service, please visit or contact the company at+1(630)616-6680 .