"... Fab house knows too little about the product to
influence that--it is the customers that need to get themselves more
educated."

A very true statement in many cases, which again, brings us back to the old
"It depends!".  The original question from this thread was a very generic
one.  The responses received might all apply depending on the product, its
application and the price one is willing to pay for it.  Werner's original
reply was qualified with something to the effect of "high reliability, HDI
PCB's..." wherein his approach may apply but it certainly cannot be applied
as a generic "catch all" especially if it is called out by someone who does
not posses the necessary "education" in ALL of the related disciplines (PC
fabrication, design and assembly).

John Parsons
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier
Sent: Tuesday, January 17, 2006 4:56 PM
To: [log in to unmask]
Subject: Re: [TN] <List>Re: [TN] Drill and plated hole callouts

Hi Eddie,
In a sense you are of course correct that the reliability of the PTV is not
a
function of how the hole is spec'ed. However, knowing the drilled hole
diameter (and other parameters) allows calculation of the reliability of the
Cu
barrel; as well as proper FEA to determine the loading at the innerlayer
attachments.
And even a good Fab house cannot afford the resources needed to understand
and measure PTV reliability. How often do they measure tensile strength and
elongation? Do they ever measure ductility, since elongation is a rather
poor
indicator of foil ductility? Do they [can they afford to] run IST or HATS
tests on
any of their coupons?
Granted, most Fab houses to a good quality job, but in the high-end PCB
cases
good quality is not adequate--good design and material choice has to be part
of the picture and the Fab house knows too little about the product to
influence that--it is the customers that need to get themselves more
educated.

Werner

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