I am looking at a part with 0.2mm balls on the bottom, in a 3x3 pattern.
I need to get a trace to the center ball, but one of the outer balls is
not in use.  I'm thinking of just running  the trace under the solder
ball and counting on the soldermask to prevent the ball from attaching
to the PCB.  Good/bad?  I'm a bit worried that when the solderballs
reflow, the lack of a pad under the unused solderball might cause that
side of the part to sit higher, as there wasn't a pad to wick away that
solder.

Shawn Upton, KB1CKT
Test Engineer
Allegro MicroSystems, Inc
[log in to unmask]
603.626.2429/fax: 603.641.5336

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