Specifying the drill size will not prevent fractured barrels or
innerlayer separation. People are designing on the edge of drill tool
capability now. Very small vias are hard to plate and get adequate
copper to survive thermal shock. Just ask for a thermally shocked
cross section of the smallest via on the panel if you need the peace
of mind. JMO
At 03:11 PM 01/17/2006, you wrote:
>I do not have a problem with through-holes for component leads and press-fit
>pins be specified that way (lots of mechanical redundancy), but I sure have
>seen a lot of plated-through vias with fractured barrel walls and
>innerlayer-separation that were not properly spec'ed.
>
>
>
>Werner
>
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