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Re: copper plating - Electrode Tips



Original poster: "Brent Turner by way of Terry Fritz <twftesla-at-qwest-dot-net>" <bturner-at-apc-dot-net>

Terry -

Yes, proper pH is critical to a successful plating job. Too much acidity
and you oxidize the surfaces and also the plating layer - hence that
spongy stuff. Not enough and the plating layer doesn't bond with the
material being plated.

That guy at work with the copper desktop is right -- one chemical used
in electroplating is urea. (Likely derived as uric acid from human pee.)
Also goes by the name thiurea (if I remember my spelling.) I use to do
my own tin-plating on copper printed circuits that I'd make in my
garage, and the system won't work without the urea. (Never tried peeing
into it though. *grin*)

Current density is also critical so as to form a slowly building layer.

I've heard that ordinary table sugar will help produce a hard, shiny
plating.

You might want to dig around some used book stores or a few engineering
college libraries to find books on electroplating.

- brent




Tesla list wrote:
> 
> Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>
> 
> Hi Mike,
> 
> For copper plating tungsten, for easy soldering....
> 
> I found "ZEP Commercial Root Kill" at Home Depot.  It is used to keep roots
> out of sewer lines.  99.0% Copper Sulfate Pentahydrate and 1% "other".  I
> assume that is "the right stuff"...  I could not find anything specific
> that was sulfuric acid...  Mostly caustic lye type compounds...
> 
> I dissolved "some" in water and added a section of 1/4 inch copper tube
> (anode (+)) and a tungsten rod (cathode (-)).  Didn't work well at all.
> Just formed soft black spongy stuff (really cool though).  More current
> more mess...
> 
> I then found some Phosphoric Acid used as the common "PH Down" for
> adjusting the PH of aquarium water.  With a very liberal squirt of the
> acid, the reaction changed completely to an obviously much better state.
> So the acid part seems very important.  I tried a lot of current with a
> little bubbling and the soft layer of copper wipes off.  I am trying a much
> lower current now...  I can probably get sulfuric acid from the pharmacy.
> One of the local pharmacists looks like he personally tests everything
> before he sells it... he probably has the right attitude about ordering
> "anything" I need :-))
> 
> A guy at work did a beautiful perfect shiny copper plating job a few months
> back on his desk.  He was explaining it all to me but one of the main
> ingredients of the plating bath was human urine...  and then I didn't want
> to know anymore :-p  I'll go ask him more now that I know the true value of
> such information...
> 
> I just checked the 1/2 inch long bit of 1/8 inch rod in the solution at
> 10mA.  A "little" better but still rubs off...  I think the solution
> contents are probably a bit critical...  Needs more research on how one can
> make the bath with readily available chemicals.  I do have a nice gram
> scale...  Seems to need better chemicals....
> 
> Chemystery was never my strong subject, but doing me best :-))
> 
> I also got some stuff to try some silver brazing and all that.  Wow!, you
> think I am bad at chemystery!!  I solder extremely well.  But welding...  I
> can incinerate just about anything with a MIG welder and my fancy MAPP gas
> torch has a "ludicrous" heat setting...  So I am all ready to go!!! :-D
> The guys at the welding shop have now learned to try and keep the crazy
> long haired guy in the suit on the premises while I am asking for a few
> boxes of acetylene and a few bags of liquid oxygen cause "I want to heat
> something up really bad"...  While the guy in back frantically calls the
> BATF ;-)))  Fortunately the day job gets a ton of $$$$ stuff from there so
> they are super nice no mater what...  They usually give me fun dewars of
> LN2 nice and cheap just to get rid of me...  When needed, asking for an
> MSDS sheet for leather welding gloves always works :-)))
> 
> I have some pals that can do this stuff for me, but having too much fun
> myself :-)))
> 
> Cheers,
> 
>         Terry
> 
> >At 06:46 PM 8/12/2001 -0400, you wrote:
> >  Yes, copper sulfate is a commonly used algicide.   Although all the
> >plating baths I have ever used contained sulfuric acid, I don't know that it
> >is really necessary.  I think it merely adds to the conductivity of the
> >solution and increases the efficiency.  That probably doesn't really matter
> >if one is just plating a small piece or two.
> >  Actually,  if you want to take the time to do it, you can make a saturated
> >solution of copper sulfate and use a lead anode(+ electrode for anyone
> >unfamiliar with the term).  You will deposit copper metal on the cathode,
> >release oxygen bubbles from the lead anode and generate sulfuric acid.  The
> >hydrogen ions (from splitting water molecules) replace the copper ions
in the
> >solution.  Once you have generated a bit of sulfuric acid, you can replace
> >the lead anode with a hunk of copper to continue plating forever with that
> >solution.  You might want to add a bit more copper sulfate crystals if the
> >concentration get very low from the acid generation.
> >Mike
> >
> >