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From [log in to unmask] Tue Sep 17 08: |
36:37 1996 |
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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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