Ron,

When a fabricator qualifies his process to UL they receive a
flammability rating for the use of a specific material, material
thickness and solder mask combination. Just because a solder mask
material or board laminate material has a certain rating when rated
individually, the rating can be very different when rated together as a
unit.

You should check the flammability rating of the material combination
your supplier is providing you against the heat generated by your device
in the concentrated area.

Furthermore, I would have them investigate any trace substances that nay
have been left on the board from the assembly process. Small, thin and
loose substances typically have a low flash temperature and can be the
catalyst for further destruction.

Regards,

Gary Ferrari
Ferrari Technical Services
860-350-9300

Scott, Ron wrote:
> All,
>
> I have a customer that is having an isuue with their boards bursting
> into flame when using one of our devices. Our device comes in two
> flavors, TQFP & QFN. The QFN is the device that ignites the board. My
> question is: Does FR4 have a flash point? I'm quite familiar with Tg
> ratings but I haven't heard about a flash point. Is there such a thing?
> If so, where can I find information? Manufacturer will not reveal board
> material to me.
>
> Cheers,
>
> Ron Scott C.I.D.
> Texas Instruments
> Storage Products Group
> Tel: 214.567.4715
> Cell: 972.816.7978
> Fax: 972.761.5070
> [log in to unmask]
>
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