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Date: | Wed, 13 Nov 1996 12:47:17 -0500 |
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> I would be concerned about my internal layer connection. All the
> Z-axis thermal stresses are now borne by the innerlayer connections.
>
Ed,
Here are a couple of design approaches to help improve the
spacings, which may or may not be the root cause but sound
like they would help the manifestation of the problem:
1. Reduce pad size rather than eliminate it. I suspect that
you would still get the improved z-axis stability of the top
side pad even if it were a tangency situation. This would
presumably improve your spacing.
2. Use soldermask defined pads. Leaving the pad size the
same, reducing the soldermask opening "some" would also serve
to increase your spacing. My understanding is that while this
approach is being discouraged in BGA attach, it may be useful
in this through-hole application.
Maybe we can get some assembly or reliability comments on
these angles.
Good luck,
--
Jeff Seeger Applied CAD Knowledge Inc
Chief Technical Officer Tyngsboro, MA 01879
[log in to unmask] 508 649 9800
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