Greg,

The profile for flex differs little from any other PCB. You always start by
following the solder supplier's preheat/reflow recommendations. The two
things that can be different is the much lower thermal  mass (though that
depends on fixturing) and the differences in IR coupling. Both of these
issues are so part/process dependent that I can't give you a general rule to
follow. The only way to know is to measure it. Take care to get an actual
reading of the pad surface and watch for hot spots as evidenced by locally
discolored adhesive.

The real trick with flex is the prebake to eliminate the absorbed moisture
and thereby prevent delamination. Getting that right is far more important
than just about anything you might logically do with the profle. Also, flex
circuit adhesives have varying degrees of solder temperature resistance so
take the time to find out what you're really working with.

Andy Magee
Flex Guru
[log in to unmask]

Greg Jones wrote:

> Andy:
>
> Do you have any information on thermal profiles, especially how they may
> differ from standard reflow or wave solder profiles?
>
> Thanks,
>
> Greg Jones
> Technical Writer
> KIC Thermal Profiling

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