quick answer to your question is yes, scale the drilling and L7 image to meet the laminate movement after bond. You should also check your registration system, as this is also a common error on blind via construction - post etch punch is the best solution
Dougal Stewart

email:  [log in to unmask]
phone: +44 1896 822204
mob:    +44 7984 629667
www.pwbsolutions.co.uk
  ----- Original Message ----- 
  From: John Parsons 
  To: [log in to unmask] 
  Sent: Tuesday, January 07, 2003 6:52 PM
  Subject: [TN] FAB: Blind Vias and Layer Scaling


  Greetings All!

  What are you all doing when faced with this situation.  

  We are building an 8 layer board using .005" core with 2x106 preg between cores (finished board thickness around 0.040").  We typically see material shrinkage after pressing of this thickness of core and adjust accordingly by scaling the artwork.  This particular board has blind vias connecting layers 8 and 7.  We are using a sequential lamination process, or not really I guess in this case, but what I am trying to say is that we will be drilling the 7/8 core before pressing (as opposed to controlled depth drilling), imaging the layer 7 circuitry and then plating the via holes - simple so far.  

  The problem is that after pressing and the inherent material movement, the layer 7 circuitry will no longer register properly with the subsequent drill process (post press).  We are not scaling the layer 7 circuitry because unless you also scale the blind drill pattern the two will not register 0 follow me so far :o) .

  At the risk of running off at the mouth I will stop now.  So, the question is, "Is that what you are all doing?"  Scaling the drill pattern, or what?

  Regards
  John Parsons
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