The main problem is linked to the huge amount of connections that should be routed. There is a very dense ball matrix and using a single traces escape routing, only 2 rows per layer can be connected. Totally 9 sequential layers are needed to connect all the pads. A good challenge, there’s no doubt about it. In attachment few images of measurement made on pitch X and Y and on the hole diameters of BGA.
BGA pitch 0,200 mm
Somacis plant in Castelfidardo is very close to finish the tests that will break another barrier. The Italian headquarters are producing a test board that will use a BGA with a pitch of 0,2 mm. Something unbelievable till few years ago is very close to become a new starting point to further challenges. Key characteristics are very demanding for PCB, with BGA Pad diameter of 100 µm and tracks and gaps of 30 µm.