Heat bondable preforms work well. Once the material bonds and
hardens it does not go any where. There are more than one manufacturer of
these types.
        Regards,
        Ramon

> -----Original Message-----
> From: Genny Gibbard [SMTP:[log in to unmask]]
> Sent: Wednesday, November 06, 2002 10:53 AM
> To:   [log in to unmask]
> Subject:      [TN] heatsinking a PCB
>
> We have a small PCB with SM components mounted on one side and a heatsink
> mounted against the other side over the entire surface of the PCB.  The
> heatsink is grounded, so we use a thermally conductive, electrically
> isolative thermal interface material in between (0.5mm thick), to protect
> signal vias.  We also use some strips of electrically conductive gasket in
> strategic areas to provide good electrical grounding between the two.
> Migration of some substances out of the thermal material onto the PCB over
> time has caused performance problems on random, not all, units.
>
> I was wondering what other methods might exist for heatsinking a PCB,
> possibly permanently bonding the metal heatsink to the PCB in some way.
> Any sources of information for alternatives is appreciated.  We cannot
> change the construction materials of the original PCB, which is a
> multilayer (4 layer) FR4, but we may be able to bond an additional layer
> onto the PCB, in place of the gasketing we use now.
>
> Thanks in advance,
> Genny
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