4.1.1 Special Consideration for Packages with Center Pad
Flat packages often come with an exposed pad located on the bottom, often referred to as the center pad or the thermal pad. This pad is not electrically connected to the internal circuit of the chip, but it is mechanically bonded to the internal substrate and serves as a thermal heat sink as well as providing added mechanical stability. This pad must be connected to GND since the ground plane is the best heat sink (largest copper area) of the printed circuit board (PCB).