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 

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 -----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