11.3 PowerPAD Package The PowerPAD package provides low thermal impedance for heat removal from the device. The PowerPAD derives its name and low thermal impedance from the large bonding pad on the bottom of the device. The circuit board must have an area of solder-tinned-copper underneath the package. The dimensions of this area depend on the size of the PowerPAD package. Thermal vias connect this area to internal or external copper planes and should have a drill diameter sufficiently small so that the via hole is effectively plugged when the barrel of the via is plated with copper. This plug is needed to prevent wicking the solder away from the interface between the package body and the solder-tinned area under the device during solder reflow. Drill diameters of 0.33 mm (13 mils) work well when 1-oz. copper is plated at the surface of the board while simultaneously plating the barrel of the via. If the thermal vias are not plugged when the copper plating is performed, then a solder mask material should be used to cap the vias with a diameter equal to the via diameter of 0.1 mm minimum. This capping prevents the solder from being wicked through the thermal vias and potentially creating a solder void under the package. (See the Related Documentation section.)
Also, in the pin function table for the thermal pad it says
This pad must be tied externally to a ground plane and the GND pin.
My questions 1) does this mean I need to have a solder connection between the chip and the pad? Or will having enough solder so that the pad on the IC touches the pad on the PCB? 2) If I need a connection, like for pins, how do I heat up the solder underneath enough to reflow? I only have a solder iron, no hot air gun.