To make sure I fully understand your problem:

1. You apply LPI solder mask onto ground planes which have through holes. The
ground planes are copper and the LPI mask is applied/processes/cured, as
normal.

2. Next, you apply a temporary solder mask (by squeeze bottle or screened)
onto the through holes and dry/cure.

3. You run the boards through normal wave solder operation and and remove the
temporary solder mask with a hot water spray.

4. Afterwards, you see "lifting" of the solder mask around the through hole
areas which extends for 5-30 mils.

If this is your problem, I think I may know what is causing it. Many of the
water soluble temporary solder masks contain ammonia/amines to make them
water soluble. These ammonia/amines are alkaline and LPI solder masks are
sensitive to alkaline materials (they can be stripped with high temperature
sodium hydroxide solutions).  The ammonia/amines attack the LPI solder mask
at its weakest point (the bond to the copper) and cause it to lift.

Possible solutions to your problems might be:

1. Check the preclean of copper before solder mask to make sure the bond is
optimum. An anti tarnish might help here.

2. Make sure the LPI mask is exposed properly, not over developed and cured
properly.

3. Try to apply and cure the temporary mask quickly and then run the boards
through the wave solder quickly and remove the temporary mask. This
phenomenon is time dependent. Especially make sure the temporary mask is
cured quickly. The solvent/ammonia/amines in the temporary mask working on
the solder mask can be very aggressive, so at least get rid of the solvents.

4. Change to a non ammonia/amine based temporary mask. There are many
available that do not contain these materials.

Hope this helps.

Larry Fisher

Allen Woods & Associates