Hi Charlie! Ooh, a good metallurgy question! I have also experienced "blue" solder joints which were traced to two situations: 1) the use of solder alloys containing high Pb compositions; 2) Sn 63 printed wiring assemblies which have been "over etched" due to excess cleaning. We have nicknamed the phenomena "Barney boards" in honor of Barney the purple dinosaur. We were able to confirm (using SERA and Auger analysis) that the blue-purpleish color is due to the surface being predominately Pb oxide instead of being Sn oxide dominated. I'll send Steve G. a nice picture of a "barney board" so you can compare it to your situation. We determined (for our use application) that the condition was cosmetic in nature and would not impact the functionality of the assembly. Good Luck. Dave Hillman Rockwell Collins [log in to unmask] Charlie Pitarys <charlie_pitarys@ To: [log in to unmask] KYZEN.COM> cc: Sent by: TechNet Subject: [TN] Blued solder joints <[log in to unmask]> 04/09/2003 02:56 PM Please respond to "TechNet E-Mail Forum."; Please respond to Charlie Pitarys What would be the cause of blue tint, hue, specks etc to be visible on the surface of solder joints. Is it just alloy composition? I have seen this in the past typically in high temp reflow /high lead alloy, copper lead frame devices around the die attach fillet. Now it is being seen on a 63/37 alloy solder smt reflow. It was not seen in the past, the cleaning chemistry is buffered to protect the metal etc. and has been in use for many years without seeing this phenomena! Maybe if a crappy traditional high ph saponifier was used and the solder joint was dull and gray it would not be as noticeable? Perhaps the copper is leaching to the surface from the tinned component lead or HASL surface? My suspicion is that trace amounts of copper is present on the surface of the solder joint after reflow. That when exposed to reflow temperatures it picks up this bluish color. Charlie --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------