I Agree with Nigel... If the time-temperature product is high enough to produce mixing the bulk solder joint should be good but not perfect... However it is all a compromise anyway...If you can get only RoHS balls on BGAs and you need to use 6337 for the connection, the process of reballing will introduce undetectable additional defect sites in the component that will lead to decreased reliability of the final product and you will loose the reliability edge you are attempting to gain... Paul Paul Edwards Surface Art Engineering -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Nigel Burtt Sent: Thursday, June 10, 2010 8:33 AM To: [log in to unmask] Subject: Re: [TN] rohs, BGAs & assembly Will be OK providing your assembly can withstand high enough reflow temperature to get the RoHS balls to melt. usually problem is not with the BGA, but with other parts that won't like to get that hot! NPL in the UK have public domain technical papers on this which you can download from their website --------------------------------------------------- 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 ----------------------------------------------------- ============================================================================== This email and any attachments thereto may contain private, confidential, and privileged material for the sole use of the intended recipient. Any review, copying, or distribution of this email (or any attachments thereto) by others is strictly prohibited. If you are not the intended recipient, please contact [log in to unmask] immediately and permanently delete the original and any copies of this email and any attachments thereto. ============================================================================== ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ --------------------------------------------------- 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 -----------------------------------------------------