Also, you need to give information on the spray nozzles you are using.  They interact with the pump pressure to give a droplet pattern for complete board coverage, but not allow etchant puddling on the top side.  Remote question also - are you etching innerlayers with no holes in panel, or are you etching outer layers (more likely since you are using alkaline) that have through holes.  I have seen etch machines that flip boards over halfway through chamber to equalize top and bottom.   Very unlikely you are etching vertically, but that eliminates puddling on top side. Final small factor - what is etch resist - photoresist or some metal like tin plating.  Heaven forbid you have nickel gold etch resist - that undercuts badly due to galvanic interaction between copper and nickel.   
 
Denny Fritz
 
 
-----Original Message-----
From: Louis Hart <[log in to unmask]>
To: TechNet <[log in to unmask]>
Sent: Fri, Jan 15, 2016 2:46 pm
Subject: Re: [TN] Pump pressure in a etching machine

Ramani, what trace width and spacing are you working with? How thick is the copper?  Louis Hart
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ramani
Sent: Friday, January 15, 2016 8:54 AM
To: [log in to unmask]
Subject: [TN] Pump pressure in a etching machine

Hi,

Can anybody suggest is is the pressure required to do 4x4 pcbs using alkaline enchant.

Regards

Ramani

Sent from my iPad

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