"... 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 --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------