Jason,
to acheive better throwing power i.e. surface to hole ratio in high aspect
ratio plating you can do one of the following:
Plate at lower current density for  alonger time (less productive).
Use an additive system that has more suppression, it will suppress plating in
the higher current density (CD) areas, or the surface, and  allow the lower CD
areas, in this case the middle of the hole, to catch up.
Use pulse reverse plating where the CD is redistributed ( Electrically) to
acheive the same goal as above.
I hope this helps.
George milad
Technical Marketing Manager
LeaRonal Inc.

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