Sorry i lost the original message so am replying to this one. Yes I have reworked a single ball on this same component ( prototype, tset eq. ). i do not recomend it. Used a tiny bit of solder paste and a hot air pencil. Had a teflon coated wire run under the part to keep any stray solder balls from blowing under the part and to keep from reflowing adjacent balls. The part should be removed and reballed or the whole part reflowed.
-----Original Message-----
From: Jason W. Gregory [mailto:[log in to unmask]]
Sent: Wednesday, February 05, 2003 6:59 AM
To: [log in to unmask]
Subject: Re: [TN] Single BGA ball rework
I second David's reply. Also, as far as the BGA being expensive, it sounds
as if your customer is deeming the failed ball to mean scrapping of the
BGA. There are various re-balling methods, such as my favorite, the
Solderquik preform. I'm not too sure of reflowing a single ball.
Jason Gregory
SMT Production Supervisor
LaBarge Inc.
(918)459-2367
(918)459-2221 fax
[log in to unmask]
David Douthit <[log in to unmask]>@ipc.org> on 02/04/2003 11:17:04 PM
Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond
to David Douthit <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
To: [log in to unmask]
cc:
Subject: Re: [TN] Single BGA ball rework
Peter,
I think the more important question is why did it fail in the first
place!!!
David A. Douthit
Manager
LoCan LLC
[log in to unmask] wrote:
> Dear All,
>
> Thanks to everyone who responded to my last plea for information on
> adhesive for teflon. Tetra-etch is the obvious etchant - I must be
getting
> old not to have thought of it, though the bigger problem is actually to
> separate the still-bonded teflon from its flange in order to clean it up,
> re-etch it and bond it back again. Timing is everything though. and I was
> shown a memorandum yesterday, announcing that the OEM of the component is
> changing the teflon component material to GRP. So maybe we'll buy GRP
> replacement bits and bond them on instead of trying to recover the teflon
> mouldings.
>
> OK. Today's topic will either bring out amused smiles or cries of
outrage.
> One of our suppliers designs boards for us (functional, schematic diagram
> stuff only - though they do basic testing of built boards, once someone
> else has specified the layout design rules the PCB, done all the
> manufacturing stuff, etc.). One board is now failing, and they have
> diagnosed that one ball on the outside row of a BGA is no longer making
> contact with the board. Although only a prototype board, it is a Class 3
> type that could ultimately fly.
>
> For various reasons, the supplier is very reluctant to reflow the entire
> BGA or to replace it in order to solve the contact problem (the BGA is
very
> expensive). Instead, they came up with the idea of manually soldering the
> defective contact. [ I can now sense incredulous reactions from here!].
> They discussed their proposal with a local assembly house, who gave them
> the impression that the idea is possible to carry out (with suitable but
> unspecified equipment). Since then they have been insisting that they be
> allowed to repair the faulty BGA with this method. I used my power of
veto,
> strongly..
>
> I thought it might be a subject to put before learned council here,
though,
> in case anyone else has been thinking of trying this sort of repair. Has
> anyone out there come across any [successful] procedure for - or actually
> tried - manually 'touching up' a single BGA ball? If you have, is the
> procedure approved for anything, what is it approved for (board class,
> specific incidents/circumstances, etc), and where can I get a copy of it?
>
> The BGA in question is a large Xilinx XCV600E FPGA (Field Programmable
Grid
> Array, not a pin grid array), 40mm (1.6 inches) square with 5 rows of
balls
> and an open centre portion. The entire top body surface is covered with a
> metal plate. Soldered standoff height is about 20 mils.
>
> Have fun.
>
> Peter
>
> [This e-mail is confidential and may also be privileged. If you are not
the
> intended recipient, please delete it and notify us immediately; you
should
> not copy or use it for any purpose, nor disclose its contents to any
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