Werner, As I continue reading your message, I have not seen the post condition you describe. How many instances have you and others seen and how do you relate them to whatever thin core and prepreg materials selected for whatever layer so compressed? It all makes sense, but what's really going on here? Does this primarily relate to "normal" MLB's say up to 60 layers on which I have worked or does this more concern HDI type boards? Earl ----- Original Message ----- From: "Werner Engelmaier" <[log in to unmask]> To: <[log in to unmask]> Sent: Friday, September 06, 2002 1:17 PM Subject: Re: [TN] IPC-TM-650-2.6.8, Thermal stress, Plated Through Holes > Hi Earl, > ILS was previously referred to 'post-separation.' > Actually, the forces are not exerted diagonally to the trace/pad to conductor > interface, but radially relative to the PTH barrel. This is the result of the > PTH barrel experiencing the same compression deformation as a submarine on > diving; except, of course, that a submarine has its reinforcement ribs on the > inside and the PTH barrel on the outside [that's the functional and > non-functional lands]. The traces resist the compressive movement of the > barrel and failure can occur at the weakest of 3 links [ plating/flash > interface, flash/foil interface, foil]. When the compressive deformation is > plastic for the copper barrel, hole separation occurs as the resin returns to > its former position on cooling. > > Werner > > -------------------------------------------------------------------------- ------- > Technet Mail List provided as a free 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/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 1.8e 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------