I'm working on a prototype board that requires a 600 pin BGA. This is a metal top BGA being placed on a 11" x 17" PCB about .62" thick.
The part is 1.77" square with a 50 mil pitch and 30 mil bump diameter. The bumps are located on the perimeter of the part only.
I'm worried about localized board warpage in the area of the BGA stressing the joints. The board will be a dual reflow but the BGA won't be placed until after the first reflow and we don't have any problems currently with board warpage. So I normally wouldn't expect any problems, but something always seems to sneak in. This part is much larger than anything else we've placed and not very forgiving so I want to make sure I've investigated all the possible ramifications.