Hi folks! Well, as Steve mentioned, the typical "blue" tint seen on a solder joint is the result of Pb oxide dominating the solder joint surface instead of the usual Sn oxide. Overcleaning is a classic way of producing "Barney pwbs" but since Paul is using an Sn96Ag4 solder alloy we can't be dealing with Pb oxide. I don't know of any Sn oxide species that are "blue" in appearance. My guess is that the blue appearance is due to some Ag surface species - silver sulfide can have a "blueish" appearance. If you had a flat enough surface you can use the SERA equipment to identify some silver surface species (silver oxide, silver chloride, silver sulfide). I'll see if any of my references can provide any help. A majority of the time these types of observations have only cosmetic impact and not a product integrity impact (someday the bright and shiny myth will be extinct!). Dave Hillman Rockwell Collins [log in to unmask] Steve Gregory <[log in to unmask] To: [log in to unmask] M> cc: Sent by: TechNet Subject: Re: [TN] Blue leads <[log in to unmask]> 12/15/2003 03:23 PM Please respond to "TechNet E-Mail Forum."; Please respond to SteveZeva Hi Paul! I had an experience with what we called "Blue Solder" once, but it was traced back to our cleaning process...you can see a picture of it on my web page at: http:www.stevezeva.homestead.com and look at "Blue Solder". What we discovered was that the airknife cycle in between the wash and rinse cycle was drying out the chemistry on the solder joints before we could get it rinsed of. Once we shortened the airkife cycle, the appearance went away. This was dealing with 63/37 solder too, not SN96 solder... Dave Hillman has some pictures on my page next to the "Blue Solder" one, he called "Barney Boards" because of the purple appearance of the solder. I can't quite remember what the situation was with that...maybe he will see this and refresh our memories. -Steve Gregory- > We just ran a long time heat run at 175C on a board made with Sn96/4Ag. > The leads turned blue. > > I don't have my CRC handy. What caused the blue? Is it silver halide? IS > there another tin oxide I am not aware of which turns blue? Or even > copper? > > > > > Paul Stolar > Materials/Reliability Engineer > Manufacturing Reliability Lead Engineer > Baker Atlas > 713-625-5376 > --------------------------------------------------- Technet Mail List provided as a 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/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------