Jamie Baumgart asked about the removal of non-functional pads.  I 
asked this question about a month ago and received a lively response 
from the TechNet members.  Although IPC-D-275 para 5.3.2.5 states 
that non-functional pads "should" be included, most board manufacturers 
who responded recommended the removal of them.  Reliability seems to 
be an issue in both camps.  If reliability is an issue, given the 
same thickness, a double sided board would be more 
suspect than a multi-layer board with non-functional pads 
included.  Wouldn't exculding them from pad stacks liken them to a 
pad on a double sided board?  It's a question that generates a lot of 
opinions, but what I think we need is something more definitive from 
IPC.  I've included one response I received that seems to walk the 
fence. Since Gary is the chairman of the Printed Circuit Board Design 
Commitee so his response was vauled most.

Tom Hybiske

------- Forwarded Message Follows -------
 To:            mail@ih [log in to unmask]
Date:          31-May-95 16:41:18 -0400
From:          mail@ih [log in to unmask]
Subject:       Re: Nonfunctional Lands

Generally non-functional lands should be included in the pad stack for
multilayer boards. This is primarily a reliability issue. Results from the
IPC small hole round robin program indicated failure in small holes in the
resin rich areas. By leaving the non-functional lands in the stack, you
reduce the resin rich areas around the holes. However, when laminating high
layer count boards, all the lands tend to present a compression problem.
Therefore, it is advisable to remove some of the lands in the stack. It is
suggested to balance the removal in the z-axis.

Gary Ferrari
Tech Circuits