Harlan,
     
     Potentially hellish problems from z-axis expansion especially if your 
     boards are high-rel. If connection to any inner layer is required, 
     better to put inner layer pads on ALL layers of a pth required to 
     provide for electrical connectivity.
     
     What price inspection or field failures?
     
     Hope this helps,
     
     Regards,
     
     Clive ff
     


______________________________ Reply Separator _________________________________
Subject: DES: Internal Connections On PWBs
Author:  [log in to unmask] at INTERNET
Date:    14-03-97 16:45


     
     This will keep TechNet hopping!
     
     
     I have a PWB with plated, unsupported holes (large pad on bottom and 
     only a "target pad" on top).  Currently my electrical connections are 
     made on the bottom.
     
     Here's my question:
     
     What trouble am I going to get into if I make an electrical connection 
     on an internal layer?  
     
     PWB material is FR4.
     Layer count is 8.
     Proposed electrical connection on layer 5. 
     No blind or buried vias.
     
     Thanks in advance!
     Harlan
     [log in to unmask]
     
     
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