I have seen some people use insulative pallets that keep the parts on the
back side from reflowing. They can make them flush hold downs on the top so
you can solder stencil your board in the pallet. I've used one, GSC at
www.goGSC.com. There a quite a few that do it and a web search on reflow
pallets should yield most of them.
jg
----------
> From: Rick Thompson <[log in to unmask]>
> To: [log in to unmask]
> Subject: [TN] Intel uBGA Flash, Bottom Side SMT?
> Date: Friday, October 30, 1998 5:03 PM
>
> We've been asked by a customer to run boards with Intel uBGA flash memory
on
> both sides of the board. My first impression was that the mass of the
part
> vs. the ball area would not provide sufficient tension to hold the bottom
> side parts in place when reflowing the top. However, the customer does
not
> want epoxy used to attach the bottom side parts due to shock testing they
> have to perform.
>
> Question: Anyone using these parts successfully on bottom side SMT?
> Anything I should watch out for?  The components in question are 7.67mm x
> 16.37mm with a 56 ball array in the center. Ball width is .35mm with a
.75mm
> pitch.
>
> Thanks in advance.
>
>                 Rick Thompson
>                 Ventura Electronics Assembly
>                 2665A Park Center Dr.
>                 Simi Valley, CA 93065
>
>             [log in to unmask]
>
>                 (805) 584-9858 voice
>                 (805) 584-1529 fax
>
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