I have a very great interest in learning more about the effects of trying to solder a 99% tin BGA solderball using a 63/37 tin/lead solder paste, and especially the problems seen in trying to solder an interposer (pin array) with these different alloys. Any info you can steer me towards would be extremely helpful, and I would be very grateful for it. Thanks, R. Dean Stadem [log in to unmask] -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman Sent: Tuesday, August 09, 2005 2:41 PM To: [log in to unmask] Subject: Re: [TN] [DC] Lead-free design changes and impacts? Hi Bill! There's nothing rocket science about the paper we published at the CMAP conference in May at Toronto. The basic principles are that if you subject a Pbfree solderball (BGA, CSP, FC - area array components) to a tin/lead reflow soldering process, you have the potential of getting a very non-uniform solder joint microstructure which can degrade the solder joint integrity. The degradation is due to the fact that your are diffusing the tin/lead into the Pbfree solderball instead of melting the solderball. The severity of the degradation is going to be dependent on the level of microstructure non-uniformity and your use environment. Additionally, ENIG finishes appear to be more problematic than immersion tin or immersion silver pwb surface finishes. Rockwell Collins isn't the first to document this phenomena - there have been a number of very good papers on the topic at several of the electronic conferences [our Rockwell photos just look better than the photos in the other papers : - ) ]. Most of the papers document that if you can achieve a uniform solder joint microstructure then the solder joint integrity isn't compromised. I'll ask Steve to post the ppt file on his website. I can send the paper out to those folks who have an interest. Dave Hillman Rockwell Collins [log in to unmask] "Brooks,Bill" <[log in to unmask] > To Sent by: TechNet [log in to unmask] <[log in to unmask]> cc Subject 08/09/2005 12:31 Re: [TN] [DC] Lead-free design PM changes and impacts? Please respond to TechNet E-Mail Forum <[log in to unmask]> ; Please respond to "Brooks,Bill" <[log in to unmask] > Ioan, I will check with Dave Hillman on Technet and forward your comments to our Manufacturing Engineers... since we are still planning to be using eutectic tin/lead solder for some time we need to be conscious of that issue and make sure to get the BGA packages with tin/lead solder balls or we run the risks you speak of... Thanks. I will also notify our purchasing department that they need to watch for any changes to BGA packages going lead free... Perhaps Dave will have more data he can post or send to me to help inform us of the potential for failures on BGA lead free packages when soldered with Tin/lead solder. Best regards, Bill -----Original Message----- From: Tempea, Ioan [mailto:[log in to unmask]] Sent: Tuesday, August 09, 2005 9:46 AM To: [log in to unmask] Subject: Re: [DC] Lead-free design changes and impacts? Yep, big trouble. Check with Dave Hillman on TN, he very recently wrote a paper showing what is happening. You have a good intuition, the 2 alloys will not completely mix giving reliability issues of which the most important is cracking at the interface with the PCB. Regards, Ioan > -----Original Message----- > From: DesignerCouncil [SMTP:[log in to unmask]] On Behalf Of Brooks,Bill > Sent: Tuesday, August 09, 2005 12:20 PM > To: [log in to unmask] > Subject: [DC] Lead-free design changes and impacts? > > There is one potential change that I really have not had time to look into > yet... maybe someone else has already looked at the BGA packages and > determined whether or not the 'lead-free' solder balls under the > packages will be an issue if you're soldering process does not go lead-free???... > Those with RoHS exemptions will still be buying lead-free parts > because they > can't get the tin/lead versions anymore, they will be phased out... > Will they run into soldering problems if the lead-free solder balls > don't collapse at eutectic solder melting temps? > > Best regards, > > Bill Brooks - KG6VVP > PCB Design Engineer, C.I.D.+, C.I.I. > Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510 Datron World > Communications, Inc. > _______________________________________ --------------------------------------------------- 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 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- 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 847-615-7100 ext.2815 -----------------------------------------------------