Hi Val! I'm not sure I have ever seen a position on this formally in IPC. As you know, each method seeks to identify an important material "transition" based on its' response to the stimulii. You get different numbers because the stimulii are different. As you know, I favor and specify TMA which measures physical changes as a function of applied heat. It can be used to generate several useful parameters, Tg, X/Y/Z axes CTE, etc.. These things seem to be of most use to most people. However, if I were concerned about an important PWB material transition under heat and vibration, I might use the DMA numbers more as representing reality under those conditions. Maybe "one" method was never chosen because the importance depends on what you are looking for from the test? Not sure. BTW - Hope you are doing well! Regards, Gerry From: "valerie St. Cyr" <[log in to unmask]> Reply-To: TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask] To: [log in to unmask] Subject: [TN] TMA recommendation Date: Thu, 16 Nov 2006 14:56:52 -0500 Dear Tech Netters, I have read that "IPC recommends" TMA for Tg determination (vs DSC or DMA). I have searched the site for a White Paper without finding one; I have reread both specs looking for any language which would seem to imply one is better than the other for determination of Tg given that the test is one that reacts to thermal inputs, making it perhaps a more useful test wrt to assessing thermal robustness given lead free assembly. I am not trying to establish the differences between the tests. I am trying to establish if IPC is on record somewhere with a recommendation or preference. Anyone know? Thanks, Valerie --------------------------------------------------- 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 ----------------------------------------------------- _________________________________________________________________ Talk now to your Hotmail contacts with Windows Live Messenger. http://clk.atdmt.com/MSN/go/msnnkwme0020000001msn/direct/01/?href=http://get.live.com/messenger/overview --------------------------------------------------- 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 -----------------------------------------------------