3 - Assembly of electronic circuits

A camera system with various illumination modes captures images of the unit under test (UUT, or device under test, DUT). One or more cameras capture these images from the top or from various angles. Since the field of view (FOV) is limited and typically smaller than the actual UUT, AOI systems need to take a number of images per PWB. Beside the cameras and lenses, proper illumination is a very important part of the system. Different illumination types can be applied, such as spot light, diffuse light or side illumination. After the images have been taken and stored, software analyses the images and comes to a fail/pass result for each component and its features of interest.

The X-ray inspection is used to detect failures in hidden solder joints, e.g. in BGA joints.

The wetting balance is used to test the wetting properties of the solder alloy, the wettability of PCB pads, and the wettability of component leads prior to soldering.

The shear test is used to test the mechanical strength of solder joints after the soldering.