Al Slagle,
     
     PCB shops amaze me sometimes, one minute they want to remove 
     non-functional lands, the next minute they want to add thieving 
     (robber bars) to low density areas to assist plating thicknesses and 
     the Z-axis thickness (especially for thick copper boards).  What up 
     with these guys!  Is it really necessary to remove these lands if no 
     holes are drilled at that location.
     Correction!   Holes are drilled at this location.  A
          non-functional pad is an inner layer pad (with a hole) that
          has no traces associated with it at that layer.  That is why
          these non-anchored pads may float during lamination.  The
          hole is most definitely there.
          Thieving is an entirely different issue.  This typically is
          requested on outer layers where plating is involved.  If the
          copper to be plated is imbalanced, overplating or burnt
          plating sometimes occurs on isolated features in order to
          get enough plating to the dense areas of the outer layers. 
          That's "What (sic) up with these guys!"

          Hey, maybe we can start removing non functional conductors
     that are difficult to remove with most CAD systems.
     
     But with all fairness, I worked for a respected PCB shop and now work 
     for a very respected assembly shop and in many ways I understand the 
     perils each side.  Guess what, I'm still a strong advocate for PCB 
     vendors.
     
     Thomas John Gulley 
     PCB Project Coordinator 
     
     email: [log in to unmask]
     


______________________________ Reply Separator _________________________________
Subject: pull-pads
Author:  [log in to unmask] at halsic_ccsmtp
Date:    10/19/95 8:20 AM


Al Slagle wrote:
__________________________________________________________________
>AS DESIGNERS, WE OFTEN REMOVE SPECIFIC INTERNAL PADS BECAUSE OF DESIGN 
>CONSIDERATIONS; HIGH VOLTAGE, DENSITY PROBLEMS, RIGID-FLEX PCB'S, >WHATEVER.
     
>BUT, WHEN FAB SHOPS WANT TO DO SO WE BAULK.
     
>WE HAVE TO PULL PADS TO CREATE A VALID PCB DESIGN.
     
>THEY WISH TO PULL PADS TO INCREASE THEIR YIELDS.
     
>SO THE NEXT LOGICAL QUESTION IS; IF YOU ARE GOING INCREASE YOUR YIELDS AND 
>INCREASE YOUR PROFITS WHEN PRODUCING OUR BOARDS. ARE YOU ALSO GOING TO 
>PASS ALONG SOME OF THE SAVINGS BACK TO YOUR CUSTOMERS??
     
>TELL US HOW MUCH WE MIGHT BE LOWERING OUR COSTS, AND THEN LET'S DECIDE.
     
     
>AL SLAGLE
>CAD DESIGNER
>HONEYWELL DASD
____________________________________________________________________
     
     
     
If the pads are pulled is the design invalid??? 
maybe sometimes but not always.
     
If your design causes a decrease in yields will you pay more for the 
product, if an alternative design does not have a detrimental efect?
     
Why would you baulk if the change does not impact performance?
     
brian