On Sat, 28 May 2016 09:29:41 -0400, you wrote:
>What about ammonium persulfate ? when I worked at the electronics plant that
>was what we used to etch our boards. It is clear and turns blue as it etches
>. we used to put it in a corningware baking pan and warm it with a hot plate
>underneath . if you put more into the mix it of course eats away the copper
>faster. In time it will take the shine off the corningware in the area where
>the heat source was.
Same kind of problem with price, I think. I could only buy it from a
chemical supply plant, and it's rather expensive.
>
>Have also used ferric chloride , it also works better if you warm it. Ferric
>chloride is usually used in sewage treatment plants to coagulate the solids.
Had used that for years, hard to find in good sized lots, 30
bucks/gallon or more plus shipping.
Peroxide and muriatic acid is far cheaper.
If I could find a cheap source of ammonium persulphate, that would be
nice.
The stuff in the pool supply stores (Oxy-shock) is 10 bucks/kilo, and
has trace ingredients (undisclosed). It does work, but I'm not happy
at that price.
Harvey
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>
>
>From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
>Sent: Friday, May 27, 2016 8:07 PM
>To: Homebrew_PCBs Mailing List
>Subject: [Homebrew_PCBs] Substitute for Sodium Persulphate
>
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>I have a commercial etching tank, composed of formed acrylic plastic
>and two fish tank pumps.
>
>It's designed for sodium persulphate etchant.
>
>I can get a pool shock persulphate etchant for about 10 dollars for 1
>KG, and you need about 1 KG for a single run (no idea how many boards
>that is, but it's about 1-2 gallons of etchant).
>
>The normal HCl/H2O2 etchant that I use would no doubt eat the pumps to
>pieces.
>
>So a question would be: Can I use high concentration H2O2 (say from a
>beauty supply store, no idea how much that might be, but presumably
>less than the 1.25 dollars/quart that I can get H2O2 for...)? Just by
>itself, I suspect that it might not work, would activating that
>etchant with a little chloride ions (perhaps salt?) work?
>
>Has anyone looked for a substitute for Sodium persulphate (potassium
>persulphate will also work, but equally expensive, I think)?
>
>Is there an etchant that will work for this kind of situation?
>
>Harvey
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