we try to spec. the >170C tg material rather than the 130 tg we see better z axis during enviromental stress testing when the hole size is <13mils and on b/b vias. we have less barrel cracking. Graham Collins <[log in to unmask]> on 11/08/2001 12:37:43 PM Please respond to "TechNet E-Mail Forum." <[log in to unmask]> To: [log in to unmask] cc: (bcc: Warren Crow/US/I-O INC) Subject: [TN] High Tg FR-4 Hello Technet A question for bare board gurus. Is there a difference in reliability between high Tg and regular Tg FR-4 ( IPC-4101/24 vs IPC-4101/21) in a vehicle type application? The end use application is less than Tg of /21 material, so not in the glass transition range for either material. Typically - is the CTE different between these two? (I expect that depends on the manufacturer to some degree). If there isn't a high temperature operating requirement, why select the high temp FR-4? Thanks! regards Graham Collins Process Engineer, Northrop Grumman Atlantic Facility of Litton Systems Canada (902) 873-2000 ext 6215 --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------