Visual BGA inspection on the edge of the BGA package and the geometries of the depiction is very limited and is a function of having access to a periphery of the device. Many times the operator will have to be able to articulate the board underneath the microscope. This also assumes that the edge of the board has not interfered with respect to the edges of the device.
Endoscopic inspection is similar in scope and in its limitations to the visual inspection process. The endoscopic mirror is placed in vicinity to the edge of the BGA so that BGA inspection can occur. The magnification of the inspection instrument is such that unlike optical inspection, the periphery of the BGA ball interface can be seen. The ball to package interface is important because this part of the BGA inspection can determine if the wetting of the ball to the package is sufficient.