Just a friendly update: IPC-TR-486 is not yet available. -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Werner Engelmaier Sent: Friday, June 22, 2001 8:21 AM To: [log in to unmask] Subject: Re: [TN] stitch bars on double-sided boards Hi Gary, In a message dated 06/21/2001 13:45:20, [log in to unmask] writes: >Werner: I would argue your point, in that by having interfacial connections in a MLB >composite, that you are mechanically re-inforcing the hole wall barrel. This is important >on thicker boards, as the more interstitial connections, the less prone you are to hole >wall pull-away. Hence the reason for the stitched vias in DS products. >Gary Erickson Hole wall pull-away is not really a reliability threat, but PTV barrel cracking definitely is. And the point I made is experimentally substantiated in IPC-TR-579 "Round Robin Reliability Evaluation of Small Diameter Plated Through Holes in Printed Wiring Boards." And of course, the connections of the barrels to the innerlayer can get stressed enough to fail as well. A study on innerlayer separation (ILS) or post separation has just been finished and published, IPC-TR-486, "Report on Round Robin Study to Correlate Interconnect Stress Test (IST) with Thermal Stress/Microsectioning Evaluation for Detecting the Presence of Innerlayer Separations." Werner Engelmaier ---------------------------------------------------------------------------- ----- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------- ----- --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------