Steve,
A thought just came to me. How about using a vapor phase machine to
reflow the connector solder connections and then bring the assembly out
of the vapor chamber quickly and simply lift the connectors off, before
the solder can cool. There may be some solder touch up required on
other components or haywire's, but that is relatively easy. Minimal
damage should occur to the connector since the vapor phase will limit
the temperature to about 215 Deg C.
Jim Kittel.
>-----Original Message-----
>From: Wade Oberle [SMTP:[log in to unmask]]
>Sent: Thursday, January 07, 1999 6:19 AM
>To: [log in to unmask]
>Subject: Re: [TN] Assy: Is it possible to rework a BGA socket?
>
>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-
>
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