Sounds like you have poorly laminated copper to substrate and/or a high
delta CTE. I wouldn't recommend HASL finish for BGA's either. I use ENIG
boards for these, though popular opinion seems to favour immersion silver
for this now.

Peter Duncan



                    Mike Duggan
                    <Mike.Duggan@INT        To:     [log in to unmask]
                    ERMEC.COM>              cc:     (bcc: DUNCAN Peter/Asst Prin Engr/ST
                    Sent by: TechNet        Aero/ST Group)
                    <[log in to unmask]        Subject:     [TN] BGA pads lifting
                    >


                    10/18/01 03:42
                    AM
                    Please respond
                    to "TechNet
                    E-Mail Forum."






We are experiencing a problem that I could definitely use some help trying
to determine what is going on.

The board is a very thin (0.020") pcmcia size card manufactured out of
Getek
material with a Immersion Gold over Electroless Nickel finish.  We are
seeing a fairly high failure rate out of the initial assembled boards.  The
failure mode appears to be broken connections in one particular corner of
the BGA.  The break is actually occurring where it is ripping the pad off
the board.  I have a couple of engineers here that claimed they had the
same
problem on a different board about 2 years ago and solved the problem by
going to a HASL finish from a Immersion Gold over Electroless Nickel
finish.
I find that hard to believe, but am open to suggestions from anyone out on
TechNet.

Mike Duggan
NPI - SQE
Intermec Technologies Corp.
Phone: 319-369-3364
Fax: 319-369-3722
Pager: 800-251-7921
e-mail: [log in to unmask]

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