Thanks for all your responses.  Designers are excellent reference
material!

Here is what I found from the fabrication side (land-less vias in fab):

- Pads are not required for good plating (as I thought) but to keep the
hole wall from being etched away.  This is OK if you don't mind the hole
wall being etched a few mils.  One caveat is to make sure you tell the
vendor you need the hole plated or they might tent over it before
plating.

- Pads can be removed after plate and etch in a second drill operation
using controlled depth drilling.

As usual these requirements may add cost.

For boards already fabricated the solutions are:

- Insulating pad over via (soldermask - technically not an acceptable
insulator, epoxy, mylar etc.)

- Remove pad with drill or knife.  With this method you must be very
careful (as you can imagine) and you will probably want to recoat the
area with solder or other coating to cover any bare copper exposed by
removing the pad (corrosion issues). Additionally there is a possibility
(I'm not sure how great) of separating or tearing the hole wall plating
from the hole wall.

I don't know what our project team will do yet.  I did find out a couple
other facts I did not know (this is not a board I worked on) - the
metalized part is soldered to the board (a filled area) and there is no
soldermask.

Again thanks for all your help and responses.

Ben Davis
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