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Help with Muriatic Acid Hydrogen Peroxide etchant...

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kjacobs

New Member
Hello,

I have been using the Muriatic Acid Hydro Peroxide etchant now for the last few projects. The first time I mixed a batch it etched a pc board in about 3 minutes. Incredible, great stuff. I then placed it in a sealed container for the next use.

For the next project a number of weeks later I pulled out the bottle to etch another board and it took a little over a hour to etch a board. Holy cow! So I added a little freshly made stuff to finish that one.

Today I went to do another and same thing. Old solution took forever so I made a brand new fresh batch and etched the board in 3 minutes.

Why is the old solution taking forever? I thought this stuff is supposed to get better as you use it? Is this a temperature problem? Any thoughts would be great...

Thanks
 

Hayato

Member
Well.
HCl does not attack cooper. It needs the Hydrogen Peroxide (H2O2) as an oxidizing agent. But H2O2 is very instable, it decomposes with light and turn into water.

So, you can try adding more H2O2 to the HCl every time you etch the board.
 

PapWiel

New Member
I always store the 3 ingredients separate, and only mix as required, (i.e. ⅓ HCL (hydrochloric acid), ⅓ H2O2 (peroxide) and ⅓ H20 (water)).

Once used, I discard of the solution. I found that it did not work a second time around.
 

Sceadwian

Banned
Yeah, just dump that dissolved copper down the drain.
 

kjacobs

New Member
Thanks for the input all. I guess this stuff is not as reusable as I was led to believe. It is still cheap to make and works great when fresh. Bummer it doesn't keep. Oh well...
 
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Mikebits

Well-Known Member

MrDEB

Well-Known Member
think plumbing

If the etchant sits in a metal pipe for a long time it might etch its way to a leak
3 ingredients?
its only muratic acid and hydrogen peroxide.
what 3rd ingredent are you using?
and no chemical symblos-I is not a chemist
 

chemelec

Well-Known Member
If the etchant sits in a metal pipe for a long time it might etch its way to a leak
3 ingredients?
its only muratic acid and hydrogen peroxide.
what 3rd ingredent are you using?
and no chemical symblos-I is not a chemist
Papwiel Said:
"I always store the 3 ingredients separate, and only mix as required, (i.e. ⅓ HCL (hydrochloric acid), ⅓ H2O2 (peroxide) and ⅓ H20 (water))."

His Third Ingedant is WATER!
If your using a Strong Hydrogen Peroxide, than thats OK.

But if your using the normal 3% Hydrogen Peroxide, Don't add water.
It will Reduce the amount that you can etch.

Use 1/3 Hydrochloric Acid and 2/3 Hydrogen Peroxide.
 

PapWiel

New Member
If the etchant sits in a metal pipe for a long time it might etch its way to a leak
3 ingredients?
its only muratic acid and hydrogen peroxide.
what 3rd ingredent are you using?
and no chemical symblos-I is not a chemist
Well, okay, technically only two ingredients are stored. The third is normal tap water. I use 40% solution Peroxide, that's why it needs to be diluted with water.
 

tytower

Banned
Yeah, just dump that dissolved copper down the drain.
I took this to be sarcasm!

But I wondered what would the disolved copper be . Copper Oxide? Copper Peroxide (Blondie) ? Copper Chlorate ?anyone know
 
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Sceadwian

Banned
That was definitely sarcasm =) I'm not sure it really matters what form the copper is disolved in, as long as it's dissolved it's very absorbable.
 

Hayato

Member
I took this to be sarcasm!

But I wondered what would the disolved copper be . Copper Oxide? Copper Peroxide (Blondie) ? Copper Chlorate ?anyone know
Cooper Chloridre. A green and toxic salt.

Sometimes if you rub this solution with cooper chloridre + acids in steel, then a layer of cooper is deposited on the steel surface, it's nice. :D
 

Sceadwian

Banned
Immersion copper deposit, happens with a lot of solutions with dissolved metal, the copper layer it deposits is almost unusably thin though. If you applied a voltage though you might actually be able to plate out the bulk majority of the copper from the solution making it safe to dispose of. I wouldn't use it for a circuit board though.
 

Hayato

Member
I agree. But the interesting part is that Cooper Chloridre + acid solucion, sometimes, plates steel without the need of external voltage applied.

When you drop a steel/iron nail inside a Cooper Sulphate solution, for example, the metallic cooper will only deposit, forming a sludge.
 

Sceadwian

Banned
That's because of the difference in the metals. The electrical charge is from the difference in the galvanic series of the metals involved, they form natural batteries in the solution, which is why the immersion deposits are thin, they're not auto-catalytic they require the exposed substrate to deposit, once the copper coats the surface of the steel the deposit process stops. If you apply a DC voltage though the process will continue, until most of the metal is deposited onto the substrate. But not evenly.
I worked in the metal finishing industry for 10 years, this is a cause of failure in our Zinc plating occiasonly when we overload our muriatic acid cleaning tanks with brass parts. The line had a fix cleaning cycle which couldn't be changed, ordinarly brass isn't acid dipped for this very reason. After the acid becomes saturated with copper it will immersion deposit on steel subrates, but it also brings a bit of a smut with it which really messes with the electrolytic zinc plating process causing all sort of problems because the current density changes from teh copper substrate relativer to the normal steel one. The most common outcome was a black appearance to the zinc at the high current density areas (edges) of parts.
 
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MrDEB

Well-Known Member
The recipie I follow

1 part muratic acid and 2 parts hydrogen peroxide
pour the acid first THEN add the hydrogen peroxide
 
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