Gary....

  I concur with Gary Fararri.  Removing unused innerlayer pads was
commonplace years ago, as us fabricators wanted to minimize the
opportunities for innerlayer trace-to-pad short opportunities.
Unfortunately, as layer counts and board thickness increased, the large
amount of copper thickness that you would be removing created a vast
difference in pressure areas when you would compare a "pad-stack" vs. an
adjacent pad-void area.

  At McCurdy Circuits, we stopped the practice of removing the unused pads
on thick, higher layer-count boards.  In fact, when some designs of 14+
layers came in to our engineering from the customer with pads removed, we
would work with the customer to allow us to ADD BACK the missing pads to
enhance the barrel plating integrity.

  Best regards,

  Scott McCurdy

  SOUTHLAND INTERCONNECT GROUP, INC.
  1801 E. Parkcourt Place
  Building B
  Santa Ana, CA 92701

        Cellphone:           (714) 425-3235

        Email                  [log in to unmask]





   -----Original Message-----
  From: DesignerCouncil [mailto:[log in to unmask]]On Behalf Of Gary
Ferrari
  Sent: Monday, June 24, 2002 9:12 AM
  To: [log in to unmask]
  Subject: Re: [DC] High Performance Electronic Design


    Gary,

    I would suspect that you are getting a high "Z" axis expansion during
hand soldering from the resin rich area caused by the removal of internal
lands on the pad stack. IPC did a study several years ago in this area and
did find substantial evidence that this can occur.

    Regards,

    Gary