At 09:30 22/01/98 PST, you wrote:
>     Hi all,
>
>     Our ammonia etcher is followed by a replenisher rinse consists of 4
>     cascade rinse chambers. As I understand, all ammonia etchers are
>     followed by some cinfiguration of replenisher rinse, and when I ask
>     what is the purpose of it, I was told that the rep. rinse is to
>     1) Decrease the copper content in the subsequent rinse water
>     2) Increase the copper content in the etchant that enter the etcher
>     3) Give a finishing touch to the etched panels
>
>     I understand point#1, but not #2 and 3. Why would one want to increase
>     the copper concentration in incoming etchant? Won't that defeat the
>     purpose of feeding "fresh" etchant? And how does rinsing in cold,
>     fresh etchant give a finishing touch to the etched panels?
>
>     Regards,
>
>     Yee T.G.
>     Hadco Corp.

Your point 2 Is not clear to me either . Regarding point 3 : from my own
experience this is quality of rinsing . Alkaline etching solutions creates
sediments while diluted with water , there are also monovalent copper
chlorides , which are insoluble in water . All this is easy removed by fresh
etchant .
This is important point for someone , who is still running reflow of
tin-lead . As well these residues are contributing to copper content in
solder stripper .
Regards

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