I never had a problem with cooling rate all the way up to 42mm package.  I
have experienced warping on a smaller 'glob top' due to the fast heating
ramp of vapor phase.  I now only use a convection oven with a 1 - 2 C/sec
heat ramp.

Jim Kittel

> -----Original Message-----
> From: Craig Hillman [SMTP:[log in to unmask]]
> Sent: Thursday, August 05, 1999 4:00 AM
> To:   [log in to unmask]
> Subject:      [TN] Large BGA's
>
> Hello Technetters,
>
>         Standard vapor phase reflow profiles suggest cooling rates of
> between 1-4 degrees C/sec. Has anyone found it necessary to
> drastically reduce the cooling rate, down to C/minute, for large
> BGA's (45mm x 45mm)?
>
> Thanks in advance,
> Craig
>
>
> Dr. Craig Hillman
> CALCE Electronic Products and Systems Consortium
> University of Maryland
> College Park, MD  20742
> (301)-405-5316
> [log in to unmask]
>
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