It is the Tg determined by TMA that is the one reflecting the CTE changes. Werner -----Original Message----- From: Paul Reid <[log in to unmask]> To: [log in to unmask] Sent: Wed, 12 Nov 2008 2:39 pm Subject: Re: [TN] Tg specification Not all Tgs recorded are reflection of changes in CTE. There are three DMA based Tgs. One each for Young's' modulus, loss modulus, and tan delta. DSC gives a fifth Tg. Pick you operating temperature, test method, point of view ... Best regards, Paul -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Syed Ahmad Sent: Wednesday, November 12, 2008 10:25 AM To: [log in to unmask] Subject: Re: [TN] Tg specification Tg being the transition temperature where CTE (commonly designated as alpha 1) shifts to a higher value, FR4 Tg is no longer 14 or 15 ppm past its Tg. The CTE past the Tg (alpha 2) should be listed on the material datasheet. Higher CTE will cause more reliability problems than a lower CTE depending on the operating temperature at a site or for the system. To determine the effect of Tg, operating temperature needs to be measured or simulated. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Bryan Montney Sent: Tuesday, November 11, 2008 1:49 PM To: [log in to unmask] Subject: [TN] Tg specification I'm looking for a guideline or resource (IPC spec?) on how to select and specify the proper Tg for a given design? I'm not talking about process wise (Tg140 is acceptable in our lead-free processes), but design wise. For example, is Tg140 material sufficient for a board running 80amps through it and sitting in an enclosure on a hot summer day in Arizona? Also, I'm looking for how best to test the Tg robustness during production. Any help would be greatly appreciated. --------------------------------------------------- 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 ----------------------------------------------------- It is the --------------------------------------------------- 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 -----------------------------------------------------