Soldering SnPb solderballs with SnAgCu works. The problem of the maximum temperature can be overcome by vapour phase soldering at 240°C ( even 230°C) and prior drying of the components.
About reliability there are various reports. Woodrow from Boeing claimed that PB contamination in SnAgCu solder joints is even beneficial.
Best regards
Guenter
>-----Ursprüngliche Nachricht-----
>Von: TechNet [mailto:[log in to unmask]] Im Auftrag von Iven, Jowan
>Gesendet: Mittwoch, 9. Dezember 2009 09:24
>An: [log in to unmask]
>Betreff: Re: [TN] SnPb SOLDER BALLS WITH SAC SOLDER PASTE
>
>I agree with you Ioan,
>
>Most leaded bga's have maximum temperature specifications below the
>lead-free process.
>So why worry about the balls when the bga is electrically damaged?
>
>
>Regards
>
>Jowan Iven
>Process Engineer
>Neways Advanced Applications
>
>
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Ioan Tempea
>Sent: Tuesday, December 08, 2009 2:54 PM
>To: [log in to unmask]
>Subject: Re: SnPb SOLDER BALLS WITH SAC SOLDER PASTE
>
>Hi Lee,
>
>First, how would you reflow a leaded BGA at LF temperatures without
>popping it?
>
>Then, the closest paper I have, coming your way in a second, is
>something from AIM saying that Pb will deposit at the points that cool
>the slowest, making brittle Pb pockets at the interface with the pad.
>
>Regards,
>
>Ioan Tempea, ing.
>Ingénieur Principal de Fabrication / Senior Manufacturing Engineer
>T | 450.967.7100 ext.244
>E | [log in to unmask]
>W | www.digico.cc
>
>N'imprimer que si nécessaire - Print only if you must
>
>
>
>------Original Message------
>From: Lee Whiteman
>Sender: TechNet
>To: [log in to unmask]
>Subject: [TN] SnPb SOLDER BALLS WITH SAC SOLDER PASTE
>Sent: Dec 8, 2009 08:17
>
>I know about the problems with soldering BGAs with SAC solder balls and
>SnPb solder paste and read plenty of papers pro and con.
>
>I heard about a report where if you solder BGAs with SnPb solder balls
>using SAC solder paste, the resulting solder joint will be unreliable.
>Has
>anyone heard of anything like that? If there are any cross-sections or
>papers that you can share with me, that would be great.
>
>Thanks again.
>
>Lee Whiteman, PMP
>Senior Member Engineering Staff
>L-3 Communications East
>Telephone: (856) 338-3508
>FAX: (856) 338-2906
>E-Mail: [log in to unmask]
>
>
>
>
>
>SENTEC
>11 Canadian Road, Unit 7.
>Scarborough, ON M1R 5G1
>Tel: (416) 899-1882
>Fax: (905) 882-8812
>www.sentec.ca
>
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