Homebrew PCBs

----- Original Message ----- 
From: "Larry Battraw" <lbattraw@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Saturday, December 05, 2009 3:07 PM
Subject: Re: [Homebrew_PCBs] Re: AQ3000 Waterborne Photoresist questions


> 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.

I see that Mega Electronics is selling a conventional positive-working 
liquid resist for \ufffd85 a litre. It's suitable for spray, dip and spin 
coating.

Leon