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September 2006

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Subject:
From:
R Sedlak <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, R Sedlak <[log in to unmask]>
Date:
Wed, 13 Sep 2006 06:46:34 -0700
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text/plain (84 lines)
Edward:
  You are spot on the money... details which are too easy to overlook.

  Rudy Sedlak

Edward Szpruch <[log in to unmask]> wrote:
  Rudy,
Two additional points, both of crucial importance :
- tight control of temperature
- tight control of spray pressures ( upper and lower spray , across etching chamber and real exact jobs - post etch spray nozzles )
Regards
Edward


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of R Sedlak
Sent: Wednesday, September 13, 2006 12:01 PM
To: [log in to unmask]
Subject: [TN] Ammoniacal Etch

Joe, Wayne, and others...

A couple of words about ammoniacal etch which might help shed some light on the situation.

90+% of the pcb fabricators control ammoniacal etch using only density (Baume').

This was adequate when we called 10 mil line and space "fine lines", but really is not adequate for today's world...

Think about the fact that Cupric etch has three conditions which are monitored:

Metal content (By density)
Acidity (Usually by conductivity)
Cuprous Content (By ORP)

If you were going to control ammoniacal with the same precision you would control by the following

Metal Content (By density)
pH (Comparable to Acidity in the Cupric etch)
Cuprous Content (which is controlled by air flow through the chamber)

So, in many ways the ammoniacal etch today could be considered to be operating on luck. The system works best when it is used continuously. The system is pushed to its limits when operated intermittently.

Rudy Sedlak
RD Chemical Company


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