[sdiy] Soldermask for fine pitch TQFP packages

[Seb Francis]

John Luciani wrote:
> One more spec to watch is the minimum width required for the soldermask.
> If the gap results in a soldermask strip that is less than the minimum
> width I increase the gap to the smallest size required to remove the
> strip.
>   

This is a bit tricky as my PCB package only allows the guard gap to be 
specified by pad, or globally, but not by package.  And unfortunately 
the default for all the pads is 10mil ...

So I either just set a global 4mil, or I would have to go through and 
manually change all the pads to 4mil, except any pads that are used by 
packages with pad gap between 8mil and 8mil + min soldermask width.  I'm 
not even sure if this is possible since pads can be shared by multiple 
packages.

What's the worst that could happen if I inadvertently specified a 
soldermask strip that was less than the minimum?  Would it just not 
stick properly and risk peeling off?  Or can something more problematic 
happen?

Seb