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Subject: Re: Etching: sodium persulfate vs ammonium persulfate??
Date: Sat, 23 Nov 2002 22:38:42 GMT
NNTP-Posting-Date: Sat, 23 Nov 2002 17:38:42 EST
Organization: Road Runner
Andrew Tweddle wrote:
> Terry King wrote:
>>Somewhere in the 10 years since I last etched a board,
>>Kepro has switched to Sodium Persulphate, with some
>>Does anyone know what the tradeoffs are between
>>sodium persulfate vs ammonium persulfate?
>>I see ammonium persulphate (which I used to favor)
>>sold as an etchant by some suppliers. Isthere
>>some reason for the switch??
>>Regards, Terry King ...In The Woods In Vermont
> The Ammonium ion in aq soln carrys away the copper very effectively.
> Sulphate ion is not as effective as chloride ion at etching copper at
> the same temperature. As a trade off for kitchen sink use. ie. using an
> elevated temperature to move the reaction rate along and relatively
> safe, and non smelly compared to ammonium copper chloride which works
> brilliantly but requires fume hoods, it isn't a bad one.
From my research, sodium persulfate seems a better choice if you want
shelf life. It seems that ammonium persulfate recrystalizes when it
cools down, and becomes useless. However, sodium persulfate can be used
at room temp or heated, and can even be reused again until it's used up.