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August 2007

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Subject:
From:
Dave Dixon <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Dave Dixon <[log in to unmask]>
Date:
Fri, 17 Aug 2007 13:17:16 -0500
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text/plain
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Kerry,
	IMHO that is an excellent question.  I know many engineers who
would never have thought of such a (possibly) simple and elegant
solution!  Have a great weekend,
Dave
 
>
>

Phil,
Dumb question, but can you put the resistor on the bottom of the board,
and live with it?
>
>

Let me start with, I know that we should not rely on the LPI solder mask
as an insulator.  So I need recommendations for a simple and cost
effective solution.

Problem parameters; 0.062 thick FR-4 with 2 oz copper and LPI mask.  PTH
components laying on traces that go under the parts.  PTH parts are
shorting to the traces.

Our fab house is against adding a second layer of LPI mask.  On face
value a second layer sounds good and easy, but I know there are issues
too long to list.

Short of raising the components above the board, applying an insulator
under the components or a new board layout is there a better way of
preventing this shorting problem?

Thanks in advance.

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