Jerry,
There should not be a problem with double-sided BGAs if:
1) your oven uses rails and not a mesh belt
2) it moves smoothly
3) the BGAs are light enough that the liquid surface tension of the molten
soler is enough to hold it to the board.  Without doing the math I would
expect that with the number of I/Os for a BGA that you should be OK, unless
you are trying to start off with a BGA with an embedded copper heat sink!!

I have no corporate disasters to report on this front.  However, I will tell
you to be particularly careful of moisture storage of BGAs.

regards,
Bev Christian
Nortel

> ----------
> From:         Jerry Cupples[SMTP:[log in to unmask]]
> Sent:         Tuesday, June 23, 1998 6:15 PM
> To:   [log in to unmask]
> Subject:      [TN] ASSY: BGA sanity check
>
> Hello, TechNet....
>
> Soldering (inline convection furnace) BGA's on both sides of a board is
> beyond my own experience, but it seems to violate a principle (at least an
> imaginary one) related to the controlled collapse, or perhaps liquids
> under
> tension.
>
> For a board design using 3 commercial BGA packages (PBGA 256, eutectic
> balls on 1.27 mm pitch), am I obstinately blocking the path of progress by
> requesting that this package style be confined to only one surface of a
> new
> board design?
>
> If you are doing this today and it is a piece of cake, go ahead and brag;
> but I would prefer to hear that caution is well advised, i.e. tales of
> misery, shame and corporate disaster resulting from such mistakes. ;-)
>
>
> cheers,
>
>
>
>
> Jerry Cupples
> Interphase Corporation
> Dallas, TX USA
> http://www.iphase.com
>
> ################################################################
> TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
> ################################################################
> To subscribe/unsubscribe, send a message to [log in to unmask] with
> following text in the body:
> To subscribe:   SUBSCRIBE TechNet <your full name>
> To unsubscribe:   SIGNOFF TechNet
> ################################################################
> Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional
> information.
> For technical support contact Hugo Scaramuzza at [log in to unmask] or
> 847-509-9700 ext.312
> ################################################################
>

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet 
################################################################
Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################