Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

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


 





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