You need to use the pads. I would not recommend paste. The pre-smashed dimensions of the pads are 1.5mm thick and one is 20mmx20mm and the other is 15mmx15mm. (so, two 20x20x1.5's would have you covered easily.) Also missing is the torque on the heatsink. However there was a lot of effort on the pictures and I appreciate that!

Use non-conductive thermal pads, 20x20x1.5 and 15x15x1.5 are what you need.

I know this is old, but the pads are 1.5mm thick.. one is 20x20 and the other is 15x15. Don't use paste, you'll be re-applying it every few months as it runs out the side and makes a mess of the PWB.

I would not recommend paste. You need to use the pads. they are 1.5mm thick and one is 20mmx20mm and the other is 15mmx15mm. (so, two 20x20x1.5's would have you covered easily.) Also missing is the torque on the heatsink. However there was a lot of effort on the pcitures and I appreciate that!