John,

Rather than looking for a different solder mask material you might want to
change the board design to SMOBC (solder mask over bare copper).  If
you change to SMOBC, the tin could not reflow & therefore cause the
solder mask to bubble & lift.

>>> JOHN OSULLIVAN
<[log in to unmask]> 08/14/97 04:49pm >>>
  REGARDING           Solder mask material

With regard to different solder mask material I'm interested in finding out if
some solder mask materials have differnet thermal masking abilities.
The reason I ask is because of a board I am wave soldering which has
heavy
copper layers internally, which forces me to pass the board through the
preheat stage (and over wave) very slowly. The board was
manufactured using
all over tin/lead reflow. The tin/lead under the solder mask on large tracks
are reflowing grosely and causing the soldermask to bubble/blister and
crack
off, failing the infamous 'tape test'.

Any comments.

Dennis Ostendorf
aaeee2o @snds.com