Rudy:
The cost of hydrochloric acid can be significant in the operation of cupric chloride systems.
Aside from the HCl consumed in the reaction
3Cu + NaClO(3) + 6HCl ------> 3CuCl(2) + 3H(2)O + NaCl
(with sodium chlorate systems but could be calculated for peroxide also), what is sometimes
overlooked is the HCl lost in the "bleed" from the system. For example, if a customer is
operating at 2.0 N HCl and generating 100 gallons of cupric bleed per day, 20 gallons of the
"bleed" is HCl (assuming tech HCl is approximately 10 N), which must be added to volume
chemically consumed.
A cost breakdown on the operation would be as follows:
1. 100 gallons of bleed x 24 oz. copper/gal = 150 pounds of copper etched
2. Mass of sodium chlorate required to etch 150 pounds (1072 mols) of copper =
83.5 pounds (357 mols)
3. Volume of HCl (assuming 10 N tech HCl) required to etch 150 pounds of copper =
56.6 gallons (2144 mols)
4. Volume of HCl in the bleed = 20 gallons (because the "bleed" will also be at 2.0 N)
5. Total volume of HCl required = 76.6 gallons
6. Cost of sodium chlorate (assuming $0.60/pound, which is realistic for dry OR on a dry
weight basis for predissolved LIQUID sodium chlorate) = $50.10
7. Cost of HCl (assuming $1.00/gallon) = $76.60
Best Regards,
Ted Stern
"" wrote:
> Thanks to Mark M for the compliment.
>
> Generally, the lower the acid, the better the "etch ratio", or the less the
> "undercut", and the slower the etch....
>
> The higher the Copper, the faster the etch.
>
> And, yes, Mark is right, high acid can lead to attack on Titanium.
>
> And in the US, the cost of the HCl is a trivial part of the cost of the etch,
> the oxidizer (Peroxide, or Chlorate) is the costly part, so that should
> really not be the deciding factor.
>
> Rudy Sedlak
> RD Chemical Company
>
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