Plugging vias with LPI typically leaves an air pocket in the center of some
of the vias, half way between the top and bottom surfaces.  Given this
condition, some of these vias will develop a hole in the LPI plug as they are
being cured.  The smaller the hole, the greater the chances of liquid
entrapment, particularly when the board is warm and exposed to a cooler
liquid.  Depending on the nature of the entrapped liquid, a field failure
caused by an intermittent via will most likely be in your future.
Depending on your artwork requirements, LPI offers other advantages like
finer resolution and lower cost.  I would seriously consider switching to LPI
if you can avoid depending on it to 100% plug your vias.
         Norm Dill

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