As printed circuit boards have become increasingly complex, PCB inspection has developed quickly. While off-line manual visual inspection (MVI) using magnifiers and microscopes is still required, given the tiny size and number of components on a PCB, that process is greatly limited. Due to the tiny size of components and the even tinier footprint of solder joints, automated optical inspection (AOI) is critical for excellent procedure control and error detection. The majority of AOI systems have an angled camera and a top down camera to acquire solder joint details and eliminate shadowing that can be caused by components that are positioned extremely close together.

Absence / presence, skew, rotational variations, polarity, tombstoning, and solder joint analysis should all be detectable by excellent AOI software. These devices should all be capable of doing both 3D (or structured lighting) and 2D (camera) evaluations.

Equipment for AOI can be in-line or manual load. A manual load requires the operator to load each board individually, whereas in-line examines each board as it exits the reflow oven on the conveyor. An actual inspection just takes a matter of seconds. Many PCBs can be examined to 100% in 30 seconds (in most cases, within 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 circuit board being tested has pieces that were not precisely arranged as the Golden Board. If this transpires, the board does not pass; this is a false failure. Programs that use data recognize where components should be positioned on the circuit board, and everything is compared to where the piece should really be. These systems driven by data are usually more precise.

AOI systems should be competent at pinpointing defects in component placement and solder joint formation automatically, so that manufacturing process faults can be caught before they enter the next production stage.

Restronics's sales staff has extensive expertise in selecting the appropriate AOI equipment for specific customer needs.