Hi Bill - I don't think Scott's dull solder joint appearance is due to large lead dendrites formed by slow cooling as described by Mather and Hagge. The Ag/Pd/PT termination finish can produce some "interesting" microstructure phases which could be the root cause of the grainy, dull solder joint appearance. Same basic principle but just another microstructure phase root cause. Either way, your recommendation of Scott chasing down the thermal history of the solder joints is spot on. I actually have the original Mather/Hagge paper in our Technical Reference library! That paper was published at the 6th Annual China Lake Soldering Technology Seminar Proceedings in 1982. There is also an excellent photograph of a large lead dendrite (due to slow cooling) causing solder joint surface roughness in the International Tin Research Institutes "Metallurgy of Soldered Joints in Electronics" Publication #708, page 36. Dave [log in to unmask] Sent by: TechNet <[log in to unmask]> 01/14/2009 06:26 PM Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to [log in to unmask] To [log in to unmask] cc Subject Re: [TN] Dull and Grainy Leaded Solder Joints What is the cooling rate of the grainy looking joints? Dull solder joints was reported in the early days of vapor phase soldering, until Mather & Hagge of Rockwell Collins found that it was an artifact of slow cooling of the joints which altered the grain structure of the solder joints. Accelerating the cooling rate solved the problem. Details can be found in their paper: "Kinetics of Intermetallic Compound Formation and of Base Metal Dissolution into Molten Solder During Vapor Phase Soldering", John C. Mather and John K. Hagge, Collins Telecom Products Div'n., Cedar Rapids. Perhaps Doug Pauls, Dave Hillman or Roy Keen would have a publication citation where the paper can be found. I just have a photocopy of it. Bill Kenyon Global Centre Consulting 3336 Birmingham Drive Fort Collins, CO 80526 Tel: 970.207.9586 Cell: 970.980.6373 **************A Good Credit Score is 700 or Above. See yours in just 2 easy steps! ( http://pr.atwola.com/promoclk/100000075x1215855013x1201028747/aol?redir=http://www.freecreditreport.com/pm/default.aspx?sc=668072%26hmpgID=62%26bcd=De cemailfooterNO62) --------------------------------------------------- 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 -----------------------------------------------------