I'm curious to know how you would repair the missing conductor of an
isotherm spoke connection and not compromise the drilled hole connection?

Dave Rooke
Circo Craft - Pointe Claire

_______ reply separator ________
>Dave Hillman posted:
>>     What is the effect, if any, of
>>     one of the four "spokes" going from a grounded pad to the clad area
>>     being broken.  I've been under the opinion that one of the four
>>     "spokes" being disrupted would not cause significant reduction in the
>>     electrical or thermal properties of the grounded through.  Would you
>>     gentlemen please give your opinion of the effect of one spoke being
>>     damaged and whether you feel a repair is needed."
>>
>>
>>     Dave Hillman
>>     Rockwell Collins
>>     [log in to unmask]
>Dave,
>        The effect of one spoke being broken is the loss of 25% of the
>copper crossectional area of the path to that via.  This would create
>additional power loss in the rest of the spokes and would increase the
>temperature of the copper and the board at that point.  The result is some
>loss of the reliability of that particular hole and some (probably very
>small) increase in the total voltage drop in that net. Whether or not to
>repair the missing spoke is impossible to answer without knowing the end
>use (ie, required MTBF of the board) and the built in redundancy (ie, how
>many holes can fail before the whole board is a failure).  Here, where most
>of work goes into far away and unrepairable locations and we do
>one-of-a-kind stuff, we'd repair it.
>        Howard Feldmesser
>        Johns Hopkins University Applied Physics Laboratory
>
>
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