Hello, Below it was stated that ' . . . the manufacturing process doesn't over cure the material'. What happens to PCB material that is overcured? Does the dialectric of the material change? Does it cause signal attenuation in the vias? Thank you in advance, David Tremmel 847 557-9574 - Phone 847 557-9573 - Fax http://ValuRecovery.com VALUE RECOVERY Quality is the nature of the service -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Ted Tontis Sent: Viernes, 05 de Octubre de 2007 09:21 a.m. To: [log in to unmask] Subject: Re: [TN] Via plugging with LPI soldermask... Werner, I will be the first to admit I am not an expert in the matter of HWPA and I can only relate to the few articles I have read. You wouldn't find them in unprocessed PCB's because the material around the hole is not cured correctly. As the boards continue through the process they continue to cure, there by shrinking the material causing resin recession. Board material that is correctly cured by the board house is slightly under cured. The reason for this is so that the manufacturing process doesn't over cure the material. As a board reaches its Tg it expands in the Z axis not the x or y axis. Another point is with the different types of resin content, fabric reinforcement and PWB constructions would it difficult to graph or trend the relationship between CTE and hole wall reliability. Ted T -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier Sent: Friday, October 05, 2007 1:40 AM To: [log in to unmask] Subject: Re: [TN] Via plugging with LPI soldermask... Hi Ted, I cannot agree with what you relate from that article as the causes of HWPA and resin recession-if that were so, you would find them in unprocessed PWBs. They are only found after exposure to soldering temperatures, and result directly from the large CTEs of the resin above Tg. Werner --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 -----------------------------------------------------