As a technician that does frequent board level repair rework some questions have come to mind. While the majority of my work is legacy i.e. vintage (1968) we will face these concerns in the near future. The boards I primarly work on are Nuclear graded Class IE, (high reliability, seismically qualified, etc.) high dollar boards, typically in the 3-10g range and are not throw-aways, most have components that are no longer manufactured. I am looking to the industry to find best practices, this is one of the places that was suggested for posting. Any help you can give me would be appreciated. With pre RoHS solders most if not all of major manufacturers used 63/37 solders and repair rework was easy, one just used 63/37. With the adoption of RoHS controls and the subsequent use of many different alloys of lead free solders, (at least 6 I know of), the following comes to mind: 1. Are there compatibility issues mixing between the various alloys of lead-free employed currently in electronics manufactures? In strength and reliability primarly. 2. How does the technician determine the correct alloy of lead-free solder to use? 3. How does the technician determine what alloy was originally used by the manufacturer? 4. Will IPC 7711A / 7721A standards be updated to delineate alloy determination and / or an alternate methods for the complete removal of lead-free solders and subsequent repair using 63/37 or lead-free alloys? Pat Goodyear Control Technician Pacific Gas and Electric Company Diablo Canyon Nuclear Power Plant PO Box 56 Avila Beach, CA. 93424 805-545-4312 ______________________________________________________________________ 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 16.0 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 For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------