There is also the issue of hole wall roughness and nailheading.  This 
     has been discussed here before, but is being overlooked.  The 
     inclusion of the non-functionals has a direct, and negative, effect on 
     the hole quality.
     
     MB

______________________________ Reply Separator _________________________________
Subject: Re[2]: Non-Functional PadMy View-- non-functional pads
Author:  [log in to unmask] at SMTPLINK-HADCO
Date:    10/18/95 2:31 PM


     Another MAJOR manufacturing concern, that seems to keep being 
     overlooked, is the much greater propensity for drill bit breakage when 
     drilling through all those layers of Cu.!
     
     
______________________________ Reply Separator _________________________________
Subject: Re: Non-Functional PadMy View-- non-functional pads
Author:  [log in to unmask] at INTERNET 
Date:    10/18/95 11:40 AM
     
     
> > 
> >  The advantages of keeping this pad far out-weigh the minor advantage of 
> >  deleteing this from your artwork. 
>     (see some of the other responces good stuff) 
> 
     
What might those advantages be?
     
I've heard of an old-wives-tale of Z-axis control and pad lifting, 
but that is a false rumor, they don't cotrol anything of the sort. 
There's also the theory of thermal support for the hole barrel 
during solder/desolder.....however there's not enough metal with 
nonfunctional holes to amount to much thermal help.
     
Then there's manufacturing concerns......
By removing the nonfunctional pad you are not just doing cosmetic work.
In fact your are reducing the POTENTIAL of remaining copper during etching, 
which could be overlooked at layer inspection and cause needless 
shorting to planes.
You are also eliminating needless rejects because the anualar ring of the 
non-functional pads doesn't meet spec.