Homebrew PCBs

Sounds like pretty good stuff, I'm just glad this water-based stuff doesn't
use any solvents or VOCs and just uses soap and water for cleanup and sodium
carbonate to develop.  I haven't had any problems mounting the boards with a
couple dabs of hot glue on the computer fan that I use to spin it.  Getting
it off is a little more challenging :-) , trying to pry the board off the
fan while it's still wet and not marking it up with fingerprints.  I take
care to pre-balance the thing by eyeballing the way it spins per distance
from a reference point and moving it until I have a nice even spin.  The fan
works surprisingly well, coming up to speed slowly and gradually increasing
to a speed that seems just about right for getting a thin coat without it
being too thing.  Takes a couple minutes to spin and a couple more in the
oven.

Regards,
Larry

On Sat, Dec 5, 2009 at 2:33 PM, designer_craig <cs6061@...> wrote:

>
>
> Back in the 70's and 80' I used Shipley AZ111 which was solvent based. I
> built a spin coater that consisted of an old fractional hp fan motor mounted
> in a 16" x 16" box to catch the extra spun off resist. I think the speed was
> 1700 rpm but I don't remember. I mounted a .063" thick aluminum disk to an
> old fan hub with some flat head screw, the fan blades had been removed. I
> think the disk was about 8 inches in dia. The trick was to get it spinning
> smoothly and not wobble, a little bending and some aluminum tape on the
> underside to balance the disk and it worked great.
>
> I would clean up the board put somme double stickey tape on the disk and
> mount the board. Trick is to get the board centered so it doesn't come
> flying off. Retangular boards were the hardest but I was able to do a
> display board of 10" x 4" with some difficulty.
>
> To get a good coat on the board I would flood the board with resist and rub
> it all over with my finger, this was to make sure all the copper had ben
> wetted, then I would spin it. Spinning didn't take long just a couple of
> seconds. The AZ111's solvent would evaporate very quickly and it would make
> cotton candy like strands if you spun it too long. You didn't want these to
> blow back on your board.
>
> The board would go into a little DYI drying oven for 15 minutes than I
> would coat the second side. Developed it in Shipley developer (sodium
> carbonate solution).
>
> The AZ111 worked great it had nice sharp lines with excelent resistance to
> the etchant, FeCl or hot Ammonium Persulfate. Used Acetone to strip the
> resist after etching.
>
> The coating thickness on the water based stuff is going to depend on the
> viscosity and how fast you spin it as well as the initial quantity. I am
> sure temperature is a factor as well.
>
> Wish I could find this stuff again.
>
> Craig
>
> --- In Homebrew_PCBs@yahoogroups.com <Homebrew_PCBs%40yahoogroups.com>,
> Larry Battraw <lbattraw@...> wrote:
> >
> > Hi, no I am not using a real roller-coating machine, just hand tools. On
> > the suggestion of another member of this group I tried spinning the board
> > after coating it and had _much_ better results. I took an old computer
> fan
> > that had bad bearings and hot-glued a bottle lid to the center of the
> rotor
> > and then hot glued the board with a few dabs of glue to the lid. I ran
> the
> > fan at a reduced voltage so it spun up very nicely and slowly and formed
> a
> > pretty uniform coating of resist although there were buildups on the very
> > edges of the board. Two minutes in the oven at 200F and it seemed to do
> the
> > trick. There are still lighter patches and darker patches but I don't
> think
> > the variation is enough to cause problems and I'm looking forward to
> > exposing my first board to see how well the resist holds up to etchant.
> >
> > Thanks-
> > Larry
> >
> > On Fri, Dec 4, 2009 at 7:17 PM, jcarlosmor <jcarlosmor@...> wrote:
> >
> > >
> > >
> > > Are you using a real roller-coating machine?
> > >
> > > Those photoresists (AQ3000) are intended for professional use and
> generally
> > > does not accept any kind of fake/hobbyiest process.
> > >
> > > You could build a dip-coating machine which is much easier to apply
> than
> > > roller-coating.
> > >
> > >
> > > --- In Homebrew_PCBs@yahoogroups.com <Homebrew_PCBs%40yahoogroups.com><Homebrew_PCBs%
> 40yahoogroups.com>,
>
> > > Larry Battraw <lbattraw@> wrote:
> > > >
> > > > Hi, I recently bought the roller-coating version of this photo resist
> and
> > > am
> > > > having a terrible time getting a board to cure properly. What
> generally
> > > > happens is that the board will cure somewhat well except for a big,
> > > jagged
> > > > "rip" through the center of the board's resist. It looks like a
> ragged
> > > tear
> > > > in the resist and spreads out in sharp edges kind of resembling a
> > > lighting
> > > > strike with the streamers of the defect branching out. If anyone is
> > > > interested I can post a picture of the problem. Has anyone used this
> > > stuff
> > > > and had any success with it? I've tried diluting it since it tends to
> > > > capture bubbles like crazy when spread normally but that just results
> in
> > > a
> > > > pool of concentrated resist in the center of the board and decreasing
> > > > amounts as it reaches the edges of the board. I would really
> appreciate
> > > > some hints since the stuff has great potential to coat large/thick
> boards
> > > > that won't fit in a normal laminator with the dry film resist.
> > > >
> > > > Thanks!
> > > > Larry
> > > >
> > > >
> > > > [Non-text portions of this message have been removed]
> > > >
> > >
> > >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
>
>


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