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, 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>,
> > 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]
>