Re: Negative Etch (Was Re: gEDA-user: PCB manual routing)

[Tuck Hartshorn <tuck@xxxxxxxxxx>]

On Friday 22 December 2006 16:31, Lares Moreau wrote:
> On Fri, 22 Dec 2006 15:45:23 -0800
>
> Tuck Hartshorn <tuck@xxxxxxxxxx> wrote:
> > http://www.farcircuits.net/supplies.htm
> >
> > They've done hobby/ham circuit boards for years. I just noticed this new
> > listing. Might be of interest.
> > tuck
>
> On a side note regarding the PCBs, the site reads in part:
> "Expose with UV through negative film, develop with Sodium Bicarbonate
> desolved in water, and strip with liquid drano desolved in water."
>
> I am uninitiated in Negative film and usually use positive MGChemicals
> boards. The way written, it is implied that the strip step takes place
> bewteen develop and etch.  Is this the case?

Sure, after the board is exposed, the developer hardens the film (under the 
unexposed area, I suppose). The remaining films  needs to be  stripped off 
before etching. In this case, Drano is recommended. I think but have not 
confirmed that it is NaOH in the Drano that is the stripping agent.
tuck
>
> -Lares


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