Rick -



Negative etchback is a defect condition where the inner conductor layers of
a multilayer board are recessed relative to the surrounding layers of base
material.  First, it is indicative of a problem in the fabricators post
drilling cleaning processes.  Second, it is an area which tends to produce
faults in the bonding of the plated thru hole barrel to the inner conductive
layers due to its propensity for retaining air bubbles or traces of chemicals
not related to the plating bath.  The net effect tends to be latent board
failures (also pronounced environmental test failures of assembled
product or field failures).



Etchback is an option which may or may not be selected.  Negative
etchback is a defect.  Do you have your term correct?



Regards - Kelly


----- Original Message -----

From: Richard Jones

To: [log in to unmask]

Sent: 7/11/01 3:08:38 PM

Subject: [DC] Etchback





Hello everyone,





Does anyone have any information and/or comments about the value of
requiring

negative etchback on master drawings.



We are leaning toward waiving this requirement if possible.  Most
of our

products are type class 2 and 3, type 3 products.



Thanks,



Rick Jones

Raytheon Systems

Baltimore, MD



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