Phil
If your components survive a lead free profile you can solder the entire assembly with that profile. If you need a low temp profile you can solder lead free BGA's with 235°C at the solder ball. Even with 230°C. In trials we soldered SnAgCu balls with SnPb solder with 210°C. The ball alloyed with the solder without melting. The problem there is the coplanarity.
In the next issue of Soldering and Surface mount Technology of Emerald Publications there should be an article of us about this subject. At least the review has been done quite a while ago.

Best regards

Guenter



EMPA
Swiss Federal Laboratories  for Materials Testing and Research
Centre for Reliability
Guenter Grossmann,  Senior Engineer

8600 Duebendorf
Switzerland

Phone: xx41 1 823 4279
Fax :     xx41 1 823 4054
mail:     [log in to unmask]

---------------------------------------------------
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
-----------------------------------------------------