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Reply To: | TechNet E-Mail Forum. |
Date: | Wed, 9 Jun 2004 10:29:26 -0400 |
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I would bet some residual copper/contaminated are encapsulated under the
mask at this site - the mask can also be thin or have poor wetting the
conductor side walls causing voids in the mask. Properly processed PCB
surfaces with adequate soldermask application will yield a good
insulation ~ 2500 V/mil.
Jeffrey Bush
Director, Quality Assurance and Technical Support
76 Technology Drive - POB 1890
Brattleboro, Vermont 05302-1890
Tel. 802.257.4571.21 Fax. 802.257.0011
[log in to unmask]
http://www.vtcircuits.com
-----Original Message-----
From: Scott Lefebvre [mailto:[log in to unmask]]
Sent: Tuesday, June 08, 2004 2:32 PM
To: [log in to unmask]
Subject: [TN] Soldermask Dielectric DC properties
We have a PCB that two traces have shorted and blown a set of traces on
the PCBs. The trace width and spacing is correct for 150 V and is not a
new design. We recently changed PCB shops. We found some residual
moisture about 1/8" square in close proximity of two traces after
assembly and after test. The traces were entirely covered with LPI
soldermask.
I understand that the moisture should be removed prior to test. My
question is shouldn't the soldermask have insulated the two traces from
the moisture?
Scott
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Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
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