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May 1998

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Subject:
From:
Bev Christian <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Fri, 29 May 1998 08:04:26 -0400
Content-Type:
text/plain
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text/plain (69 lines)
Jeremy,
My guess is you will still get some solder wicking down the hole.  Anyone
else try this yet?  But I don't understand why you can't rework your BGAs,
not that you should have to rework many anyway.  AirVac, SRT, Conceptronics
and others make very nice equipment for BGA rework.

regards,
Bev Christian

> ----------
> From:         Jeremy POLLARD[SMTP:[log in to unmask]]
> Sent:         Friday, May 29, 1998 1:00 AM
> To:   [log in to unmask]
> Subject:      [TN] BGA Footprint
>
> Hello,
> am hoping that someone out there has experience with BGA footprints.
>
> We have completed Rev 1 of a double Eurocard PCB, 10 Layers with 7 x 356
> pin BGA devices on board. While everything went well with this run and we
> had no problems with ball connections, it is impossible to perform any
> rework or modifications if required.
> The footprint was the recommended pad with track out to a via or  " Dog
> bone". On the next revision we would like to do the following, Elimnate
> the "dogbone", place a through hole in the actual pad for the ball and
> adjust the solder paste stencil so that the volume of paste deposited
> allows for the hole through the board.
> I would use a hole size of 0.3mm (12mil) to 0.4mm(16mil) certainly no
> larger.
> This approach should enable us to rework dodgy joints from the solder side
> of the PCB
> It will also allow us access possibly to test the pins from the BGA.
>
> Has anyone done this ?
> Was it succesfull in a production environment ?
>
> Many thanks foryour help.
>
> regards
>
> jeremy
>
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