Homebrew PCBs

there is also the possibility to use either hcl or sulphuric acid in combination with hydrogen peroxyde.
the hcl H2O2 method is very related to "air oxygen regenerated cupric cloride" but much faster and a bit 
different i think.
the sulphuric acid method seems to be good when using metal film resist and also stainless tanks are 
fine. (this seems to be a more selective etchant).

with using h2o2 and hcl you can get etching to happen fine in 30 seconds (i did around 10 some times).
without much stirring etc, simply put in in jar.

i belive it is faster than (air) cucl etching because also the conversion from plain copper and hcl to 
CuCl2 is utilised for etching and not only CuCl2 enriched to Cu2Cl2. (hope i got this right).
this is only a guess by me. also regeneration is done instantly while etching.

i also did messy fe3cl, but don't like it.

regards
stefan


22.05.2003 17:23:22, "Marty Grove" <MartyGrove@...> wrote:

>First of all, thanks for the replies concerning the various reasons you are
>all constructing boards.  I\ufffd\ufffdm sure I\ufffd\ufffdll find the ongoing discussions
>interesting in this group.
>
> 
>
>I suppose I\ufffd\ufffdll offer something to the group by making a submission on this
>subject of Etchants.  Since I don\ufffd\ufffdt know what everyone is using for
>etchants at home (and I\ufffd\ufffdm not doing any type of this work at home myself),
>I can offer what I know from the industry.  My experience has been that the
>three major etchant types used are:
>
> 
>
>1)      Ammoniacal (Ammonium chloride)
>
>2)      Cupric Chloride
>
>3)      Ferric Chloride
>
> 
>
>Typically I find Ammonium Chloride and Cupric Chloride used for producing
>circuit boards, and Ferric Chloride used in the chemical milling industry.  
>
> 
>
>For home use, I would think that either Cupric Chloride or Ferric Chloride
>would be preferred.  Ammonium Chloride (as someone pointed out earlier)
>produces quite an ammonia smell, which is much worse when the solution is
>heated.  However, if you are using tin / tin lead as an etch resist, then
>Ammonical Chloride is \ufffd\ufffdtypically\ufffd\ufffd required (this may not be the case in
>home etching scenarios) since other etchants will etch away tin / tin lead
>resist.
>
> 
>
>Cupric Chloride and Ferric Chloride share a few similarities.  In the old
>days, both were rejuvenated using the oxidizer \ufffd\ufffdchlorine gas\ufffd\ufffd, then later
>people started using Hydrogen Peroxide, but now a-days people use Sodium
>Chlorate (salt water, for example).  This oxidizer can easily be made at
>home by mixing a clean rock salt with water, allowing the water to absorb
>as much salt as possible.  Then the salt water (brine) is added to the
>etchant to rejuvenate it.  Note\ufffd\ufffd this rejuvenation process is only for
>Cupric Chloride or Ferric Chloride\ufffd\ufffd not Ammonium Chloride.  There is a
>great deal of technical detail that can be discussed when adding an
>oxidizer to the etchant (such as monitoring the oxidation reduction
>potential), but I\ufffd\ufffdm not sure if that is needed for this group.  Let me
>know if you would like that information and I\ufffd\ufffdll put something together,
>or I\ufffd\ufffdm sure this information could easily be found on the Internet.  
>
> 
>
>Cupric Chloride and Ferric Chloride also need a certain amount of
>Hydrochloric Acid, another item fairly easily obtained (Muratic Acid can be
>used, and it is much easier to obtain).  And of course, both Cupric and
>Ferric will need a certain amount of Copper and Ferric Iron ions in
>solution for the whole etching process to occur.  Again, much detail is
>available for these two components (monitoring the Hcl level with methods
>such as titration or electronically, and monitoring the specific gravity of
>copper / Iron levels\ufffd\ufffd very easily done with a hydrometer).
>
> 
>
>Of the three, the Ferric Chloride is probably the easiest to dispose.  I
>have been told those years ago, some cities encouraged manufacturing plants
>using Ferric Chloride to dump the solution down the drain when they wanted
>to dispose of it.  Apparently, it helped keep the city pipes clean!  NOTE:
>(here\ufffd\ufffds my disclaimer) I am in no way suggesting that you do this with
>your ferric chloride etchant.
>
> 
>
>I\ufffd\ufffdll leave it there for now.  I\ufffd\ufffdll just add that I remember many years
>ago when I took an electronics class, I used Ferric Chloride as my etchant
>(just poured it out of a gallon jug and \ufffd\ufffdswished\ufffd\ufffd my board around until
>the exposed copper was gone.  Worked pretty well for a single sided, single
>layer board, but I also remember that board had line widths and spaces of
>about a half inch.  
>
> 
>
>Thanks for letting me contribute.  Take care.
>
>Marty
>
> 
>
> 
>
> 
>
> 
>
> 
>
>-----Original Message-----
>From: wturchyn [mailto:wturchyn@...] 
>Sent: Thursday, May 22, 2003 10:18 AM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: [Homebrew_PCBs] Etchant options?
>
> 
>
>A previous poster made the following comment:
>    I did 'em myself using Radio Shack FeCl\ufffd\ufffd.  I tried Ammonium
>    Persulfate once, but NO WAY at home, ever again!  Whew!
>
>I had used messy ferric chloride when I made some hobby PCBs about 25 
>years ago, but I have seen other less-staining etchants are now 
>available, such as ammonium persulphate and sodium persulphate.
>
>What are most people using at home, and what are the pros and 
>cons of the various etchants?  Cost?  Shelf life?  Ease of use?  
>Safety?  Cleanliness?  Availability?
>
>WT
>Winnipeg, Canada
>
>
>
>
>
>
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