Hello Henry,
I came across the same problem. A temporary solution for me was to apply a
good layer of peelable solder mask over the underside vias. This reduced my
temperatures under the bga by 20C.
A permanent fix, in my case, was to go double sided reflow with pin in hole
reflow where appropriate.
Hope this helps,
Regards
Eric Dawson

> -----Original Message-----
> From: Henry Rekers [SMTP:[log in to unmask]]
> Sent: Wednesday, June 26, 2002 3:08 PM
> To:   [log in to unmask]
> Subject:      [TN] Reflow on Wave.
>
> Does anybody have any suggestions on avoiding reflow of a 357 ball bga on
> the wave?  I'm dealing with a 6 layer board and I've kept the preheat as
> low
> as possible.  Kapton tape doesn't seem to help.  Has anybody tried any
> custom manufactured sheilding?
>
> Thanks.
>
> Henry J. Rekers
> Manufacturing Engineer.
>
>

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