Steve,
I have never reworked such a beast but here is my two cents on
how I would approach this. I would use a hot air bath or similar system
to heat the board uniformly to 150 degrees C. Next, apply a segment of
the low temp solder alloy wire made by AIM and sold by numerous
companies such as PRB line. It takes about 60 to 90 seconds for this
alloy to melt and fully homogenize with the tin/lead alloy to form a new
low melting alloy. From here you should be able to vacuum pick-up the
socket. A 'solder sucker' can be used to remove the excess molten
solder and if further cleanup is needed, you could use solder wick
(oops, I lifted a pad). The BGA socket will then need to be 're-tinned'
to remove remnants of the low temp solder alloy. From here,
re-attachment like any other socket.
I'll be interested to know what technique you ultimately decide to use.
Regards,
Wade Oberle
Manutronics, Inc 414-947-3477
-----Original Message-----
From: Stephen R. Gregory [SMTP:[log in to unmask]]
Sent: Wednesday, January 06, 1999 6:29 PM
To: [log in to unmask]
Subject: [TN] Assy: Is it possible to rework a BGA
socket?
Hey All you Einsteins out there!!
I gotta' problem...('course you do Steve, or you wouldn't be
bugging the
TechNet now would you?) I had a phone call from a acquaintance
of mine wanting
to bring two prototype boards over to rework a BGA socket,
(actually there's
two on each board). No problem I said, bring em' on over. BOY O'
BOY! Did I
ever open my big yap this time! These sockets aren't like
anything I've ever
reworked before.
They're from a company called CTI, and they're called
"Z-Lok" sockets,
and they're surface mount. They've got this big beefy plastic
housing that
goes all the way down almost to the surface of the PCB, and has
a little metal
handle off to one side that actuates some little "arms" inside
the socket that
grab each ball on the BGA for good contact, but won't deform the
balls so you
can still use the BGA directly on a board after being in the
socket if you
wanted to.
The problem is that the socket has two locating pins on the
bottom, which
are used to accurately locate the socket (into holes drilled in
the fab) when
the board was first built. There was a big time screw-up by
either the fab
vendor, the board lay-out person, or the dimensional drawing for
the socket
itself, but what has happened is that the BGA's contact pins are
now soldered
one row off! I'm being asked if I can pull this socket up, clip
the plastic
pins off, and put it back down on the board the way it's
supposed to
go...sounds like fun huh? This board is 12.5" X 18.5" and .065"
thick...and
the sockets are in the middle of the board.
I called back to CTI (They're in Indiana, but closed now)
to talk with
somebody there to find out how to rework one of these
monsters...if it's
possible.
I personally think that the socket is not meant to be reworked,
it's a test
socket and has to cost at least a hundred bucks or so. I think
that once
they're soldered down that's it. But I thought I'd ask ya'll to
see if any of
you have ever had to attempt something like this. There's only
two of these
boards, I don't wanna take a chance turning em' into scrap if I
can help it...
Thanks!!
-Steve Gregory-
################################################################
TechNet E-Mail Forum provided as a free service by IPC using
LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask]
with following text in the body:
To subscribe: SUBSCRIBE TechNet <your full name>
To unsubscribe: SIGNOFF TechNet
################################################################
Please visit IPC's web site (http://www.ipc.org) "On-Line
Services" section for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask]
or 847-509-9700 ext.312
################################################################
################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe: SUBSCRIBE TechNet <your full name>
To unsubscribe: SIGNOFF TechNet
################################################################
Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################
|
