If the board layout permits it, you can inspect the outside balls around the perimeter- if they are fine, the inside ones will most likely be fine as well.
Sometimes, a small piece of front-surface mirror can be used to inspect the sides of the chip obscured by taller components.
Even PCBA companies usually just place and reflow the chip and may only use x-ray to validate the initial build- and then rely on process consistance + functional testing at the end of line.
Even PCBA companies usually just place and reflow the chip and may only use x-ray to validate the initial build- and then rely on process consistance + functional testing at the end of line.