effect on dissipation with potting compound

[Simon]

If I'm putting a part into potting compound that conducts heat 10x better than Air would it be fair to multiply the amount of W the package can dissipate in free air by 10x, naturally there is more than 10x the surface area of potting compound than there is package surface area.

[AndyC_772]

You need to know the thermal conductivity from the die to the package, as well as from the package to ambient.

In some devices, particularly smaller ones, the die already runs considerably hotter than the surface temperature of the device. Improving the thermal conductivity from the device package to the environment won't, therefore, have a major effect on the die temperature.

[Simon]

Right good point, so reinforces my solution of using SMPS rather than a linear reg that can't handle the power

[tszaboo]

Most of the dissipation of the devices (well SMD at least) goes into the board. Also with air, the air moves so conductivity doesnt really matter that much, while the airflow does. I wouldn't be surprised, if you are not using special potting for thermal management, you actually have to derate the component.

Think about the whales vs human. Whales have bigger body and more surface, but if you drop both of them into ice cold weter, the human will die, because the core temperature will quickly drop.

[Simon]

the air wont be moving in any case except by natural convection