Homebrew PCBs

Jeff,
If you are interested in direct imaging a photo sensitized board search back through the posts around Nov of 09 for Volkan.  He built a UV laser diode direct writer that did spectacular images. The 400 nm blue-ray lasers are available on ebay. He has some images posted under the Files secton of the forum. These UV lasers are very strong >> 100mW.

I took him a board I had coated in AQ3000 (water based photo resist) to try an image. Once we got the exposure set the image was amazing crisp.

Volkan alos built a drum photo plotter.

Both these project on my list of cool things to build.

Craig


--- In Homebrew_PCBs@yahoogroups.com, "Jeff Heiss" <jeff.heiss@...> wrote:
>
> Hi Baxter,
> 
>  
> 
> I read a message from a few months ago on the UV Pen discussion that you
> were experimenting with a UV LED and a microscope objective to focus the LED
> down for resist developing.  How are your experiments going?  Any findings
> yet?
> 
>  
> 
> Jeff
> 
>  
> 
>   _____  
> 
> From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
> On Behalf Of bebx2000
> Sent: Tuesday, December 27, 2011 4:24 PM
> To: Homebrew_PCBs@yahoogroups.com
> Subject: [Homebrew_PCBs] Re: Photoresist
> 
>  
> 
>   
> 
> 
> 
> Hi Jeff,
> I got your email. I have pretty much put my experiments with DIY
> photoresists on the backburner. The patent that I originally cited has very
> precise instructions for making your own. The application was for solder
> mask. I assembled all of the ingredients, but discovered that that I need a
> mixing mill to make a decent emulsion. Elmer's School Glue is basically the
> same formula, PVA and PVac plus surfactants and flow aids. I made up a batch
> using diazo as a sensitizer in the same proportion as the patent, coated a
> blank PCB with a soft hair brush (it levels very nicely because of the
> surfactants) and pre-baked it. I then took a transparency with some pads and
> traces and exposed it with a 150 watt metal halide UV source. The time was
> calculated from the mJ of the patent based upon the UV intensity as measured
> at the surface of the PCB with a UV radiometer.
> 
> After exposure, I washed the board in water with a little gentle rubbing and
> the areas under the black part of the transparency washed away, but not
> perfectly. I didn't bother with the post-bake so perhaps this was part of
> the problem. I also tried just dipping a pre-baked board in a 1% solution of
> ammonium dichromate (as in the second patent), but the exposure time seemed
> to be off. All-in-all I think this is a viable concept, but one needs to
> have patience and setup a systematic sequence of experiments to establish
> the exposure time relative to the amount of sensitizer. 
> Baxter
> N.B. I caution you in the use of ammonium dichromate. It really likes to
> cross-link collagen.
> 
> --- In Homebrew_PCBs@yahoogroups.com
> <mailto:Homebrew_PCBs%40yahoogroups.com> , "Jeff Heiss" <jeff.heiss@>
> wrote:
> >
> > I have been researching and have found that making your own resist looks
> > possible. The ingredients are polyvinyl alcohol (PVA) and ammonium
> > dichromate. An alternative is Elmers glue and ammonium dichromate. Baxter,
> > a member on here was performing experiments in this area. Maybe he can
> > chime in if he is reading? 
> > 
> > 
> > 
> 
> 
> 
> 
> 
> [Non-text portions of this message have been removed]
>