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.]
>
> ---------------------------------------------------
> Technet Mail List provided as a free service by IPC using LISTSERV 1.8e
> To unsubscribe, send a message to [log in to unmask] with following text in
> the BODY (NOT the subject field): SIGNOFF Technet
> To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
> To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
> Search the archives of previous posts at: http://listserv.ipc.org/archives
> Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
> information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
> -----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
-----------------------------------------------------
|
