Side Angle View
Another tool for inspection is side angle viewing. It sheds light at an angle from one side of a PCB where the camera is mounted on the other side. Using this method, we can view two to three rows deep of BGA balls. Such a device views the first, second, and third peripheral ball rows on the BGA package. But the light cannot go into a fourth, fifth, or sixth. Nonetheless, it provides an effective process indicator of how ball collapse has been performed.
The advanced ERSASCOPE optical inspection system we use on our assembly floor views BGA- and micro BGA-populated PCBs from different angles, particularly with the critical side angle views to accurately inspect such small packages as micro BGAs.