Heat sink calculation for a BD682 Darlington transistor

I'm trying to determine whether I need a heat sink for a BD682 Darlington transistor.
The data sheet states Pc 14W @ Tc = 25C.

Maximum ambient temperature 40C
Tj max junction temperature 150C
Rjc junction to case 3.12 C/W

Rja junction to ambient 100C/W {SGS Thompson data sheet}

Rja junction to ambient 88C/W {Fairchild data sheet}

The maximum power that the device will have to dissipate is 560 mW.

Do I need a heat sink? I did an internet search but could not find I need. The ones I found all were about calculating the thermal resistance of a heat sink.

The Silicon Chip magazine gave an example of a heat sink calculation for a MOSFET which is relatively simple but I became confused when I tried to do it for the BD682.

Any assistance will be appreciated.

560 milli what equals no heatsink required.

.56W = no heatsink required. The package the device is in will cool itself just ok.