Does the AM6254ATCGGAALW have collapsing or non-collapsing BGA balls?
I've checked the Technical Documentation section, but couldn't find the answer. I guess I'm looking for the wrong term, or not hard enough.
Package information:
Package outline:
Source: Datasheet
Collapsing BGA vs non-collapsing appears to be referring not to the device itself, but to the technology used to define the pads on the PCB.
A PCB will either be designed with NSMD (non-soldermask defined) or SMD (solder-mask defined) pads. In the case of the former, NSMD, the opening in the solder mask is larger than the size of the copper land pad, and so it is the copper that defines the pad size. In the latter case, SMD, the opposite is true, the solder mask opening is smaller than the copper so the pad size is defined by the mask.
When you use NSMD pads, the vertical side walls (thickness) of the copper pad is exposed. As a result the solder from the BGA balls flows down around the sides of the pad and so the chip sinks down onto the board. This is where the term collapsing comes from.
For SMD, the sides are covered by the mask so the balls can't sink around the pad so this is the non-collapsing type.
For pitches >= 0.5mm we typically use NSMD pads as they provide a stronger attachment. For smaller pitches we have to use SMD pads as otherwise the spread from collapsing reduces the clearance between the balls and can lead to shorts.
