How about depositing a low temperature solder paste on the PWB pads and
reflow the BGA at a reduced temperature?

Jim Marsico
Senior Engineer
Production Engineering
EDO Electronics Systems Group
[log in to unmask] <mailto:[log in to unmask]>
631-595-5879


        -----Original Message-----
        From:   Rick Thompson [SMTP:[log in to unmask]]
        Sent:   Thursday, April 24, 2003 12:46 PM
        To:     [log in to unmask]
        Subject:        [TN] 'Unique' BGA Reflow Problem

        We have a customer who had a custom BGA built with some additional
components besides the die under the encapsulant. Unfortunately, these parts
were soldered with Sn63Pb37 and the solder reflows and bridges under the
encapsulant during reflow.  Due to time constraints they would like to find
a way to use these while they wait for new parts to be fabbed.  We've tried
various types of shielding, but the convection systems we have heat the
entire part causing the internal reflow.  Does anyone know of a focused
reflow system that would allow reflowing the eutectic balls of a BGA but not
apply enough heat to the top of the component to reflow the other parts?
Would one of the focused IR systems (Ersa, PDR) do this?  Other
possibilities?

        Thanks in advance.

        Rick Thompson

        Sr. SMT Process Engineer
        SMTEK International, Inc.
        +1 (805) 532-2800
        [log in to unmask]

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