Hi Krishnan, Much of whether PCBs survive the soldering processes depends on how you have specified your PCBs. TM-650 Section 2.4.24C - Glass Transition Temperature & Z-Axis Thermal Expansion by TMA & Section 2.4.24.1 - Time To Delamination (TMA Method) & Section 2.4.25C - Glass Transition Temperature & Cure Factor By DSC are indeed very important; however, they are only part of the story. The White Paper below can be of great help, because it not only fully explains the need for the above properties, but also explains the differences between Tg by TMA, DSC and DMA test methods. Of course, it also details all the other parameters that are important for properly spec'ing PCBs. Engelmaier Associates, L.C. just finished a multi-client study/white paper titled: "WHITE PAPER REPORT: 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." As indicated by the title, in this report recommendations are made regarding appropriate specifications and ‘FAB Notes’ on drawings for printed circuit boards (PCBs), general procedures to qualify PCB shops and to assure they would be producing PCBs of good quality, and testing procedures to verify quality and reliability. It contains examples—one for SnPb solder assemblies and one for RoHS-compliant Pb-free solder assemblies—of ‘FAB Notes’ serving as general specifications on PCB drawings, a basic questionnaire for new PCB shops to be qualified meant as a suppliment to IPC-1710, as well as recommendations for ongoing activities to assure that qualified PCB shops maintain the quality of the PCBs produced by them. All the recommendations are fully researched and referenced with 51 references. The cost of the 25-page report is $495.-; it will be delivered as a pdf-file upon receipt of a check or purchase order. Attached please find a report outline together with part of a report section to provide you with a sample of the report contents. Regards, Werner Engelmaier Engelmaier Associates, L.C. Electronic Packaging, Interconnection and Reliability Consulting 7 Jasmine Run Ormond Beach, FL 32174 USA Phone: 386-437-8747, Cell: 386-316-5904 E-mail: [log in to unmask], Website: www.engelmaier.com --------------------------------------------------- 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 -----------------------------------------------------