Hi Inge, I do not know abput UL's proposal, but there are some defined conditions: T260, T288, T300 & T320 defining temperatures at which time to delamination is measured up to 45 minutes--I also do not know who came up with this measure [288°C???]. Standard FR-4 has a T260 of less thasn 30 minutes and a T288 of less than 5 minutes, whereas a high Tg/highTd material has a T288 of 45 minutes and a T320 of about 25 minutes. Werner --------------------------------------------------- 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 -----------------------------------------------------