Hi Lenny, Unless you make very simple, thin PCBs the change is highly recommended. However, Tg is not the whole story, you also should choose a material with a Td(5%) of >= C and a thermal expansion TE(50<=>260C) of <=3.2% . Generally, you should pick a material with an STII>=215 [the STII combines the effects of Tg, Td and TE]. If you want to get some background and other suggestions, I would recommend you get my White Paper: "Recommendations for PCB FAB Notes and Specifications in Printed Circuit Board Drawings for SnPb and Lead-Free Soldering Assemblies, the Qualification of PCB Shops and Activities to Assure Continued Quality. Werner Future workshops: Reliability Issues with Lead-Free Soldering Processes, September 22, Schaumburg Failure Mode and Root Cause Analyses Reliability (Fatigue, Brittle Fracture, ENIG), September 22, Schaumburg Solder Joint Reliability: Parts 1 & 4, Oct. 9, Moscow, Russia Solder Joint Reliability: Part 4, Oct. 17, Timisoara, Rumania Solder Joint Reliability: Parts 1 & 4, Oct. 22, Tallinn, Estonia ************** Looking for a car that's sporty, fun and fits in your budget? Read reviews on AOL Autos. (http://autos.aol.com/cars-Volkswagen-Jetta-2009/expert-review?ncid=aolaut00030000000007 ) --------------------------------------------------- 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 -----------------------------------------------------