Hi Tom! Well, the appropriate answer would be "it depends" (cha-ching, Doug Pauls gets another Diet Mt. Dew). In general, mixed metallurgy systems are not as reliable as a non-mixed metallurgy system. The more severe the product use environment, the more impact a mixed metallurgy system has on the overall product integrity. I recommend you look thru the IPC APEX and SMTAI Conference proceedings for the last couple of years - there have been a number of good papers documenting the interaction of SAC305 and SN100C. You can compare those test results and test conditions to your product use environment to see if mixing is appropriate. The NASA DoD Leadfree Solder consortia is investigating a number of mixed metallurgy situations using a wide variety of tests (vibration, thermal cycle, drop shock, etc.) and should be reporting some of those results in the next few months. Good Luck. Dave Hillman Rockwell Collins [log in to unmask] Tom Burek <[log in to unmask]> Sent by: TechNet <[log in to unmask]> 02/16/2009 12:28 PM Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to Tom Burek <[log in to unmask]> To [log in to unmask] cc Subject [TN] Lead Free solder compatibility Hello technetters, I have a lead free solder question. If I have a PCB with a SN100C finish and hand solder a component using a tin Silver solder (SN96.5AG03 Cu.5), is there a possibility of creating a joint that may be less reliable, perhaps more brittle? Thank you Tom Burek, CID+ --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------