Been there, done that, have pieces of broken solder mask to prove it.

If the ground plane is large enough on a sn/pb plated board, the
bubbeling and flaking will occurr.  With a dry film mask, if the
clearance is small enough and the mask thick enough the via pads will
not wet with solder.

Don Vischulis

[log in to unmask] wrote:
>
> It is unlikely that any LPI soldermask will survive such reflow conditions as
> you describe when applied over tin/lead.  Possibly,  a thick (3mils) dryfilm
> soldermask would have a better chance.  Is it possible to use soldermask over
> bare copper, instead?
>
> Mark Dowding
> Regional Technical Specialist
> Insulectro