Let's take another angle!  It seems you all ready have the necessary 
     psi and etchant coming from your spray bars, nozzles and sump.  This 
     is evident since the perimeter of the panel etches fine, but the 
     center of the panel overetches towards the center due to solution 
     puddling.  
     
     1. I recommend you look at the spray nozzle aperture.  I recommend     
        using a fan nozzle with respect to a cone nozzle (whick allows for 
        such puddling).  Look at other available nozzle apertures on the 
        market.  
     
     2. Angle your spray bars at a 20° to 45° (assuming the plane is in the 
        Y) facing the flow of panels.  This will allow a continuous flow of 
        solution across the panel. This effiectively minimizes the amount 
        of solution puddle.
     
     3. If applicable, install an after market agitation kit.  This allows  
        the spray bars to rotate within a 60° movement.  Again, use fan 
        nozzles.
     
     One or a combination of the above will assist your issue.  Depending 
     on your direction, you may have to tweek the psi slightly.  Later.
     
     John Gulley
     Inet Inc.
     
     
     
     


______________________________ Reply Separator _________________________________
Subject: Etcher Pressure Setting
Author:  "tgyee" <[log in to unmask]> at Internet
Date:    7/15/97 9:54 AM


     Can anybody tell me what is an effective pressure setting to minimize 
     the puddling effect that occur at the center of a panel during 
     etching?
     
     It is often the case that the line width at middile part of an etched 
     panel is 0.5 to 1 mil wider than the line width at the edges for 1 oz 
     cladding. Anybody have any comment on this?
     
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