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| Date: | Tue, 23 May 2006 08:01:42 -0500 |
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Hi gang! Another possibility would be if the fill material for the plated
thru holes is conductive (e.g. CB100 which is silver filled). The test
might register a "false positive" with the barrel cracking but the
electrical continuity being maintained by the conductive hole material.
Dave Hillman
Rockwell Collins
[log in to unmask]
Jeffrey Bush
<Jeffrey.Bush@VTC
IRCUITS.COM> To
Sent by: TechNet [log in to unmask]
<[log in to unmask]> cc
Subject
05/23/2006 07:24 Re: [TN] Thermal cycle test for
AM plated through holes filled with
epoxy ink and cap
plated on the top
Please respond to
TechNet E-Mail
Forum
<[log in to unmask]>
; Please respond
to
Jeffrey Bush
<Jeffrey.Bush@VTC
IRCUITS.COM>
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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