Sounds interesting. I did a google search and what you are talking about
seems to be called Dichromated Gelatin. It is used for making holograms.
Apparently it can support very fine detail, so it might be useful as a
photo-resist.
Here is a link:
http://www.holowiki.com/index.php/Dichromated_Gelatin_Chemistry<
http://www.holowiki.com/index.php/Dichromated_Gelatin_Chemistry>Also, it is
called ammonium Dichromate not bichromate.
James.
On Thu, Jul 29, 2010 at 7:04 PM, Athar Kaludi <ceo_premium@...> wrote:
>
>
> Hi All
>
> I come across a guy making a printing block of Printing press on Zinc Plate
> by exposing in sunlight by negative film. Then after developing he etch to
> remove unexposed area of Zinc.
>
> I suppose the same can be applied for PCB. I asked and learned the process
> there.
>
> The process require to mix 3 table spoon of Gelatin in 250 ml of water
> slowly gently heating for 20 - 30 minutes. Dissolved gelatin become gel like
> - upon cooling mix 2 - 4 gms of Ammonium bichromate [yellow orange powder]
> in gelatin. The byproduct is light sensitive now so use in subdued light
> only and keep in brown bottle.
> Layer the gel on cooper clad and completely dry. Now expose via circuit
> film for 4 - 5 min in sunlight. Develop in tap water and dry. Etch the
> Copper clad in etching solution and circuit is ready.
>
> Any one used this process or can any thing better known to users to add to
> this will be appreciated and helpful.
>
> Athar Kaludi
> Karachi, Pakistan
> Premium PCB Manufacturing
>
>
>
> [Non-text portions of this message have been removed]
>
>
>
[Non-text portions of this message have been removed]