You may wonder if every joint on every board needs inspection. You can inspect everything, but a company that produces boards containing only two or three BGAs may find that an x-ray image of only one device lets it monitor what goes on during production. As an alternative approach, once a process runs well, a manufacturer could inspect every nth board, or a sample lot of boards. The inspection techniques used in these systems vary from single x-ray transmission to sophisticated tomography and laminography. In contrast, tomography and laminography can visually separate components on both sides of a board.
Users can rotate and tilt a PCB and move it in all three dimensions.
Then, you view and interpret the x-ray image. You can manually adjust the magnification, position, and viewing characteristics when you need to see a joint in more detail. In some systems, you can rotate the PCB to view the board at an angle. Manual systems may include software that can perform metrology and image-analysis tasks, such as measuring dimensions, determining the area of voids, and so on. You set the acceptable tolerances for measurements such as voiding and solder-ball size.