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Dr. H.

Wed Mar 10 2010, 08:03AM

Registered Member #931 Joined: Mon Jul 30 2007, 05:25PM
Location: Bulgaria
Posts: 486

Good day guys

big thanks for your repplyes.

After reading quite a lot of stuff - I've decided to first try the sodium persulfate. I preffer something a bit safer. In the future - If i need faster and cheaper etching - will go to the HCL +H2O2.

IntraWinding- thank you for the very usefull link

Cheers

101111

Wed Mar 10 2010, 04:52PM

Registered Member #575 Joined: Sun Mar 11 2007, 04:00AM
Location: Norway
Posts: 263

HCL + H2O22 is what I am using with good results. The solution can be used several times but sometimes you'll have to add a little more HCL or H2O22 to get some speed in the process, my experience tells me that HCL+H2O2 works best when has good circulation and and is little above room temperature (or warmer) a good strong light might also speed up the process.

JCM

Thu Mar 03 2011, 01:18PM

Registered Member #3559 Joined: Sun Jan 02 2011, 01:19AM
Location:
Posts: 16

I use equal volumes of hydrochloric acid and hydrogen peroxide. Then I add the same volume again of water to slow down the etch rate. If doing fine track etching I use 2 or 3 times the volume of water to the neat mixture.

When it starts to get weak, you can give it some more life by adding some more hydrogen peroxide.

IamSmooth

Thu Mar 03 2011, 01:23PM

Registered Member #190 Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567

I use ammonium persulfate. I buy it on Ebay real cheap. Never had a problem and you can see the board getting etched.

Ken M.

Thu Mar 03 2011, 04:24PM

Registered Member #618 Joined: Sat Mar 31 2007, 04:15AM
Location: Us-Great Lakes
Posts: 628

I use the good ole Ferric chloride, I've got 32oz of the stuff and should last a very long time since I like the brush etch method (also called the sponge method).

Dr. H.

Thu Mar 03 2011, 08:15PM

Registered Member #931 Joined: Mon Jul 30 2007, 05:25PM
Location: Bulgaria
Posts: 486

Good day guys

I have been using sodium persulphate since this thread and I will never go back to ferric chloride - it is much cleaner, doesnt stain clothes and you can see the board being etched.

Cheers

AleSeg

Thu Mar 03 2011, 10:30PM

Registered Member #2727 Joined: Tue Mar 09 2010, 02:39PM
Location: Montevideo - Uruguay
Posts: 33

Hi.

What do you think about this variant:
http://hackaday.com/2011/03/03/simple-pcb-etchant-made-from-chemicals-you-can-put-in-your-mouth
?
see you

Marko

Fri Mar 04 2011, 12:27AM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Hi guys,

I've used H2O2 + HCl for a long time, but only recently I've discovered one bummer regarding it. If you are using toner transfer method (as I think most of you do) the hydrochloric acid apparently tends to attack the mineral coating of the paper (or maybe even the toner itself?) and over time seems to cause the transfer to unbond from the pcb. I discovered that by accident - I left the board overnight in pure muriatic acid without H2O2 (9%) in hope it would soften the mineral gloss which was to stubborn to get off the pcb - the other day the whole print came off. Seems I discovered a good method for removing the toner after etching!
And even leaving the pcb in acid for 30 minutes was enough to cause large holes in the toner- this seems to be the reason why my pcb's turned out best in very high H202-content-fast-etching solutions.

This is probably one of main reasons for holes and perforations we get with toner transfer method - I don't know how other etchants would compare since I never used anything else.

Also, closed containers of H2O2 can and do blow up. On one occasion back in my school, someone left a 1l bottle of 12%H2O2 in sun which resulted in a large explosion. As the chemical spilled on PVC floor it eaten through it completely exposing the concrete beneath - hence, guys, try not to get hot hydrogen peroxide on yourselves.

Inducktion

Sat Mar 05 2011, 12:01AM

Registered Member #3637 Joined: Fri Jan 21 2011, 11:07PM
Location: Buffalo, NY
Posts: 1068

Does it have to be HCL? Or can other acids be used? I have some DeLimer stuff that has Phosphoric acid in it. Would that work? Or is that way to strong?

Martin King

Sat Mar 05 2011, 12:22AM

Registered Member #3040 Joined: Tue Jul 27 2010, 03:15PM
Location: South of London. UK
Posts: 237

Dr. H. wrote ...

but the thing I don't like is that it has a very limited life after desolving it in water ...

It's not that limited, I estimate a tank will last me at least 6 months before I need to renew it. I wrap the tank with cling film when not in use to prevent evaporation. In my early days I used Ferric chloride but then I switched to Sodium Persulphate. It's cheap, clean, fast (needs to be heated though), relatively safe and produces very good results. I can't see any good reason to use anything else TBH.

Martin.

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