Hi Jack,

        Im sure by now you have received many opinions on the Cupric etch &
regeneration schemes, but I must put in my two cents worth. I have utilized
both the HCl/Peroxide and the Sodium Chlorate/HCl systems. I worked extensively
with the Peroxide system at TI, in both the etching and the regeneration
system. We utilized the Venturi Injection system, mentioned by others for
injecting the peroxide, but found, for our system, that the timing sequence
would not allow enough HCl to be injected. We, therefore injected the HCl
directly into the sump. We controlled the Normality of the HCl with a Rosemount
Conductivity controller and the Oxidation Potential with an ORP
sensor/controller. The ORP must be controlled within a certain range to prevent
Cl gas from evolving as well as obtaining a stable etch rate. To me this was
the better system. While working at Sandia Natl Labs, we utilized the Sodium
chlorate system. I was informed by Steve Wall at Chemcut ( now Ato-tech) that
the Sodium Chlorate/NaCl system might wear on the nozzles more than the other
system. The only explanition I can come up with for the increased wear would be
that there might be some undisolved solids present. At Sandia, the shop was
smalland could not afford the extensive piping for the plumbed HCl and
Peroxide, therefore the choice to utilize Sodium Chlorate was taken. We
utilized HCl in lieu of the NaCl to avoid undisolved solids and wear on the
nozzles. The control was much the same as that at TI and the system worked very
well. A word of caution about Sodium Chlorate, is that as the Dry salt it is
percussion sensitive, being a strong oxidizer, it can detonate on jarring or
pressure ( if it is in conjunction with flammables watch out). This is not a
problem when it is in solution. In the small shop at Sandia, both the Chlorate
and the HCl were Injected into the sump, from small drums via positive
displacement pumps. An excellent resource for the Cupric System is Don Ball of
Chemcut (now Ato-Tech). I'm not sure he is still with them. He has written
numerous articles on the system. In no way would I try the CL regeneration
system, the risk is just too great in my opinion. If I can be of further
assistance you might want to contact me off line.

Good luck,

Les Connally
[log in to unmask]


>  From: Jack Evans <[log in to unmask]>, on 10/21/97 10:12 AM:
>  Good Morning Everyone,
>
>  We are in the process building a new inner layer facility and are
>  considering using Cupric Chloride etchant. Does anyone out their have
>  any suggestion on the safest, cleanest way to control the process ?
>
>  Any suggestions would be appreciated.
>
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