Hi Dave
Maplin board! I nearly mentioned that when I replied before. I have had
terrible problems with some batches from the local branch. I think some
of it may sit on the shelf for a long time. I only go and buy it as a
last resort if I really have nothing left in stock and need some board
in a hurry.
I have found that Maplin board needs even longer exposure times. One
batch needed 8 minutes here.
The Mega Electronics pre-sensitised board has always been consistent &
reliable.
http://www.megauk.com/pcb_laminates.phpNever bothered printing double. LaserStar (from Mega) works really well.
http://www.megauk.com/artwork_films.phpBut since work scrapped all their overhead projectors some time ago I
have quite a bit of OHP transparency film which I use for less critical
boards.
Regards
Paul
On 13/05/2013 19:36, dave_donlan wrote:
>
> cheers for the advice I will try another test strip but go over longer
> time.
> The uv box is a converted scanner with four UV 9W tubes from a nail
> curing unit
> The boards are positive photo from Maplins
> it is clear acetate lazer printer. I print 2 images to double up the
> thickness
> Dave
>
> --- In Homebrew_PCBs@yahoogroups.com
> <mailto:Homebrew_PCBs%40yahoogroups.com>, "smilingcat90254"
> <smilingcat@...> wrote:
> >
> > One thing not mentioned so far is to cure the image after
> exposure-development.
> >
> > After the image is developed on the board, some recommend to cure
> the remaining resist by exposing the image to harden the image. Some
> resist may not be compatible with this step so check first.
> >
> > Another issue is resist adhesion. Lots of discussion on this too. I
> always wear rubber glove to keep the board free of oil from my hand
> and to keep chemicals off my hand. Some even have recommended to
> mildly pre-etch the blank then apply the resist. And so on...
> >
> > If you want to be accurate with exposure, you might want to use
> Stouffer's 21 step exposure guide. do a google search if you want one.
> >
>
>
>
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