Good morning Kitty; It isn't so much the Glass Transition temperature (Tg) you need to worry about so much as the total summation of the Z-axis expansion both above and below the stated Tg for the processing temperature. Unless chosen carefully a high Tg board can give you a bigger expansion over the applied (process) temperature. As an aside the board design can make matters worse, for example if the aspect ratio of any vias is greater than 6:1 (target 4:1) the likelihood of barrel cracking becomes even more significant with LF. Just to give you something else to worry over, modern laminates tend to absorb moisture very readily and if uncontrolled the extra thermal stress during LF processing can cause delamination. Is the environment where the boards are processed controlled? Hope this helps. Regards Bob Gregory -----Original Message----- From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Kitty Hines Sent: 07 November 2012 23:30 To: [log in to unmask] Subject: [DC] PCB Material for Lead-Free RoHS Hello, I hope all is well with everyone. I'd like to get advice from the experts! And I know where to find them... I have a question regarding Board Material for Lead-free, RoHS design. I am dealing with high-volume/low-cost processes, usually sent overseas for bare board manufacturing. Another issue is, we are using a lead-free FR4 type, HASL finish. 1) When specifying board material, is it necessary to specify a higher temperature rating? 2) What are the advantages? Disadvantages, other than cost? Thank You In Advance for your help, Kitty Kitty Hines The Chamberlain Group, Inc. (630)516-6655 [log in to unmask] ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ ------------------------------------------------------------------------ --------- DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 16.0. To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF DesignerCouncil. To temporarily stop/(restart) delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL/(MAIL) For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ------------------------------------------------------------------------ --------- The data contained in, or attached to, this e-mail, may contain confidential information. If you have received it in error you should notify the sender immediately by reply e-mail, delete the message from your system and contact +44 (0) 1332 242424 (the Rolls-Royce IT Security Director) if you need assistance. Please do not copy it for any purpose, or disclose its contents to any other person. An e-mail response to this address may be subject to interception or monitoring for operational reasons or for lawful business practices. (c) 2012 Rolls-Royce plc Registered office: 65 Buckingham Gate, London SW1E 6AT Company number: 1003142. Registered in England. ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ --------------------------------------------------------------------------------- DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 16.0. To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF DesignerCouncil. To temporarily stop/(restart) delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL/(MAIL) For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ---------------------------------------------------------------------------------