Totally agree. 15 seconds seems very short. With a bunch of fairly standard UV LEDs my Chinese eBay resist takes about 6-7 minutes to expose well.
I also let it cure in the dark for a few minutes after exposing.
I also do another few minutes under UV and let it cure again after developing, before etching.
I have had the resist come off before in the developer when it was under-developed or the developer was too hot. But if it stands up to that, I have not yet had a problem with it falling off during etching.
--- In Homebrew_PCBs@yahoogroups.com, Paul <paul@...> wrote:
>
> Dave
>
> It does of course depend on the UV source and the photo board but 15s
> sounds far too short.
>
> Using laser printed art work on acetate, with my UV box (2 x 8W tubes)
> and using pre coated board (usually from Mega Electronics) I need about
> 3 minutes.
>
> But as folk have suggested try a test strip.
>
> http://www.piclist.com/tecHREF/piclist/biketut/chapter3.html#zzee_link_9_1019487419
>
> Paul
>
> On 12/05/2013 15:07, dave_donlan wrote:
> >
> > Hi guys
> > I am using UV exposure method on clear acetate
> >
> > 15 secs exposure caustic soda developer about a 60 secs
> >
> > hydrochloric acid / peroxide etchant no bubbler just sloshing about
> > but the problem is the protective layer is coming off after a few
> > minuets of etching
> >
> > hydrochloric is 30%
> > peroxide is 9%
> >
> > Any advice please
> > Dave
> >
> >
> >
> > No virus found in this message.
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> >
>
>
>
> [Non-text portions of this message have been removed]
>