As PCBs have become more complicated, PCB inspection has developed rapidly. Though off-line manual visual inspection using magnifiers and microscopes is still essential, because of the tiny size and number of pieces on a circuit board, that method is greatly limited. Because of the small size of parts and the even tinier size of solder joints, automated optical inspection (AOI) is critical for excellent procedure control and defect detection. Most AOI machines have a top down camera and an angled camera to capture solder joint characteristics and eliminate shadowing produced by parts that are put incredibly close together.

A decent AOI program should be able to identify the essential defects: skew, rotational variations, absence / presence, tombstoning, polarity, and solder joint analysis. These devices should all be capable of doing both 3D (or structured lighting) and 2D (camera) evaluations.

AOI technology can be manual load or in-line. Manual loading requires the worker to load each board one by one, whereas in-line inspects each board as it comes out of the reflow oven on the conveyor. A genuine inspection just takes only a few seconds. Many circuit boards can be examined to 100 percent in 30 seconds (and usually in 15 seconds).

One of two approaches is generally used to program: the data-driven approach or the golden board approach. Usually, the Golden Board approach is more prone to "false failures" when the PCB being tested includes pieces that were not accurately placed the same as the Golden Board. When this transpires, the board fails to pass; this is referred to as a false failure. Data-driven programs understand where parts should be put on the PCB, and everything is contrasted to where the piece should be. These systems driven by data are generally more accurate.

AOI systems should be competent at detecting defects in component placement and solder joint formation automatically, so that production procedure flaws can be detected before they reach the next production stage.

Restronics Southern California's sales team has notable expertise in selecting the best AOI equipment for specific customer needs.