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Subject: Re: [Homebrew_PCBs] Developing dry film photoresist

From: James <bitsyboffin@...>
Date: 2013-07-07

On 07/07/13 23:31, Kerry Koppert wrote:
>
> I am trying to develop using washing soda (I
> forget the exact strength but I think it was 200g in litre of water).
>

Holy moley, WAY too much.

20 grams of washing soda (sodium carbonate) per litre is fine, if you
are using 200g per litre then I'm not surprised it's giving you
trouble! You do not need a strong solution.

If the water is warm, (not hot, just warm), the developing should take 2
- 3 minutes.

Rub it with your fingers as it's going to help remove the gunk.

PS: After etching, make up some strong washing soda with really hot
water and use that to strip, don't bother with sodium hydroxide (lye),
nasty dangerous stuff, and simply not necessary to use at all.





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