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May 2006

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Subject:
From:
Jeffrey Bush <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Jeffrey Bush <[log in to unmask]>
Date:
Tue, 23 May 2006 08:24:40 -0400
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Is it possible the pattern has redundant chains supporting continuity after some have cracked?  Cracked barrels generally produce resistance levels well above 5%.  

Jeffrey Bush
Director, Quality Assurance and Technical Support
VERMONT CIRCUITS INCORPORATED 
           76 Technology Drive - POB 1890 
              Brattleboro, Vermont 05302
                Voice - 802.257.4571 ext 21
                    Fax - 802.257.0011
                       <http://www.vtcircuits.com/> 
                           

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of christian ge
Sent: Tuesday, May 23, 2006 2:53 AM
To: [log in to unmask]
Subject: [TN] Thermal cycle test for plated through holes filled with epoxy ink and cap plated on the top

Hello Technetters,

  I need your help on the following thermal cycle test problem.

  Recently we asked our PCB suppliers to do 1000 cycle thermal cycle test for 6L, daisy chain boards with plated through holes filled with epoxy ink and cap plated on the top of the holes( or via-in-pad design).  The resistance change before and after thermal cycle test is less than 5%, however the holes have complete barrel crack.  Have you seen this kind of problem before?  Can I approve the supplier's test result?

  Here are some more information about the test for your reference.
  1) board thickness: 1mm (40mils)
  2) hole size: 20mils, 18mils, 15mils, 10mils.  All have complet barrel crack except the holes of 10mils .

  Thanks for your help in advance!
  Chris


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