Automatic optical inspection (AOI) is an automated visual inspection of the printed circuit board (PCBA) Assembly ,is the service provided by East India Technologies, where a camera autonomously scans the device under test for both catastrophic failure (e.g. missing component) and quality defects (e.g. fillet size or shape or component skew). It is commonly used in the manufacturing process because it is a non-contact test method. It is implemented at solder paste inspection (SPI), post-reflow and pre-wave.

AOI will detect the following defects on the line 

  • Billboarding
  • Component offset
  • Component polarity
  • Component presence or absence
  • Component Skew
  • Excessive Solder Joints
  • Flipped component
  • Height Defects
  • Insufficient Paste around Leads
  • Insufficient Solder Joints
  • Lifted Leads
  • No Population tests
  • Paste Registration
  • Severely Damaged Components
  • Solder Bridges
  • Tombstoning
  • Volume Defects
  • Wrong Part
  • Bridging

These are common defects in SMT and wave process.

 

Despite the major improvements that have been made, modern circuits are far more complicated than boards were even a few years ago. The introduction of surface mount technology and the subsequent further reductions in size mean that boards are particularly compact. Even relatively average boards have thousands of soldered joints, and these are where the majority of problems are found.

This increase in the complexity of boards also means that manual inspection is not a viable option these days. Even when it was an acceptable approach, it was realised that it was not particularly effective as inspectors soon tired and poor and incorrect construction was easily missed. With the marketplace now requiring high volume, high-quality products to be brought to market very quickly very reliable and fast methods are needed to ensure that product quality remains high. AOI, automatic optical inspection is an essential tool in an integrated electronics test strategy that ensures costs are kept as low as possible by detecting faults early in the production line.

One of the solutions to this is to use automated or automatic optical inspection systems. Automated optical inspection systems can be placed into the production line just after the soldering process. In this way, they can be used to catch problems early in the production process. This has a number of advantages. With faults costing more to fix the further along the production process they are found, this is obviously the optimum place to find faults. Additionally, process problems in the solder and assembly area can be seen early in the production process and information used to feedback quickly to earlier stages. In this way, a rapid response can ensure that problems are recognised quickly and rectified before too many boards are built with the same problem.