You are correct, its not a huge advantage being able to apply
your own "dry film photoresist" for conventional print and etch.
However, for producing plated through hole boards, the dry film
is mandatory. The only possible advantage I can see is that it
reduces cost, since blank PCB is much cheaper, especially if you
get off-cuts from fabricators. Although it sure is a _lot_ better
to use than spray on liquid resists, such as Electrolube PRP.
One other minor advantage is that if you mess up the exposure in
some way, you can easily strip the resist off and start again.
As far as I'm aware, photoresist can only be directly exposed
with very expensive UV lasers. Normally a red light sensitive
film is exposed with a laser to make a photomask, then the
photoresist is contact exposed under high power gas discharge UV
lamps.
Stefan Trethan wrote:
> But i still don't really know which advantage the dry (wet) film has.
> May you lay out the advantages compared to presensitized boards?
> As i understand it is only a method of applying photoresist?
> The only advantage i see is when using rotary drum-like laser exposure
> plotter.
> Sure it is good for something - you wouldn't use it if not... please tell
> me.
>
> thanks..
> st
>
>