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"Jeff Seeger" <simon.ipc.org!bort.mv.net!rapidcad!jseeger> |
From [log in to unmask] Thu Aug 1 17: |
41:46 1996 |
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Vince Harlan asked:
> I have a 12 layer PWB(Backplane) with 8 ground planes(all 2 oz.).
> Each connector on this assembly has several pins that connect to
> all 8 ground planes. Each connection is thermally relieved by 4
> separate .010" traces(spoked). Each trace is .035" in length.
> The connectors that are on the top layer have been successfully
> flowsoldered, ...
> Does anyone have experience with this type of design and/or are
> there any guidelines that might help me in reevaluating this
Most interesting... These values are roughly 4x the maximums
for IPC-D-275 on thermal reliefs. On *several* occaisions I've
been faced with higher current levels than the IPC std would per-
mit, and have needed to specify hand soldering since I could not
get reassurance (on technet or otherwise) that reliable machine
soldering was possible.
Perhaps it's the .035" long hookup that helps?
Perhaps it's also time to look at IPC-D-275's thermal relief spec-
ification. Can anyone comment on the origins of that spec?
Best regards,
Jeff Seeger Applied CAD Knowledge Inc
Chief Technical Officer Tyngsboro, MA 01879
[log in to unmask] 508 649 9800
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