I have not had much success reflowing an individual ball or even reflowing
the entire part for a ball or 2 that were not connected...even on much
smaller micro BGA's. I recommend removing the part, reballing the part,
proper board prep and proper reflow with a BGA rework system.
Good Luck,
Bruce Misner
> ----------
> From: Charles Caswell[SMTP:[log in to unmask]]
> Reply To: TechNet E-Mail Forum.;Charles Caswell
> Sent: Wednesday, February 05, 2003 10:28 AM
> To: [log in to unmask]
> Subject: Re: [TN] Single BGA ball rework
>
> 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
> other
> > person. Thank you.]
> >
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