This instructable will explaining the easiest possible way with the least sophisticated equipment on how to replace a BGA. This method requires the following:
1. New device to be placed (or previously reballed device)
2. StencilQuik(TM) stay in place stencil matching the pattern of the BGA
3. Solder paste
4. Miniature squeegee
5. Reflow source
6. Magnification system for inspection
This technique eliminates the need for a high end rework system. while an x-ray is not on this list (and by all rights should be)
Step 1: Clean the Location
Using a low lint, low charge-generating wipe, clean the area with isopropyl alcohol or other approved cleaner.
Step 2: Align and Place the Stencil
After removing the backing from the rework stencil, start in a corner and slowly align and place the stencil aligning the apertures with the pads on the board.
Step 3: Apply Pressure to Activate Adhesive
Apply pressure to the stencil surface on order to activate the adhesive.
Step 4: Squeegee Solder Paste Into Apertures
Using a micro squeegee slightly larger than the device squeegee solder paste in to the apertures. Use the correct solder alloy. Move the squeegee back/forth until all of the apertures are clean. Using a static free and lint free cloth wipe the surface and the extra solder paste from the stencil.
Step 5: Place the Replacement Device in the Stencil Apertures
Place the device in to the stencil apertures. You can tactically "feel" the solder balls as they fit in to the stencil apertures. Be careful to not apply too much downward pressure or you will "squeeze out" the solder paste. Make sure the orientation of the part is correct using the reference designator.
Step 6: Reflow and Inspect
Using a low end reflow source follow the profile for the given solder alloy. This heart source can be lower end system. Inspect the solder balls to make sure that they are uniformly collapsed. The stencil also acts as a "band aid" for any damaged mask material.