Mica micanite have a blue material with a much higher CTI than FR4, commonly
used for boards on washing machines and earth leakage circuit breakers. This
may suit your purpose.
Dougal Stewart
email: [log in to unmask]
phone: +44 1896 822204
mob: +44 7984 629667
----- Original Message -----
From: "Phil Nutting" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, May 15, 2002 10:03 PM
Subject: [TN] High Voltage tracking on pbc surface
Hi folks,
Today I have a question about high voltage tracking. The actual set of
materials and applications are as follows.
FR4 material, 0.090" thick, two layer, plated through hole, LPI solder mask,
submerged in Shell Diala AX dielectric oil, operating at 100kV. We are
seeing hv tracking marks that run with the grain (fiber directions) of the
FR4 material. This burn marking is in the LPI, but also in the FR4 material
as can be seen in the photo where the LPI has been scrapped off. The
measling is from removing the copper from the board.
Here is the photo http://www.stevezeva.homestead.com/files/HVTracking.jpg.
It is the top left hand photo entitled High Voltage Tracking. Thanks, Steve
Gregory for posting this on your page www.stevezeva.homstead.com.
We have seen this tracking on other boards which do not have the LPI solder
mask, they are bare boards, so that eliminates the LPI as the cause.
One of our engineers had seen this in a former life and it was attributed to
the small air bubbles in the substrate where the fibers were.
Is there a different type of material that will not exhibit this tracking?
Thanks, Phil Nutting
----------------------------------------------------------------------------
-----
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send e-mail to [log in to unmask]: SET
Technet NOMAIL
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700
ext.5315
----------------------------------------------------------------------------
-----
---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------
|
