Board mounting an DFN/QFN (Dual/Quad Flat-Pack No lead) application note from ON Semiconductor. Link here (PDF)
The DFN/QFN platform offers a versatility which allows either a single or multiple semiconductor devices to be connected together within a leadless package. These guidelines include printed circuit board mounting pads, solder mask and stencil pattern and assembly process parameters.
from Dangerous Prototypes http://bit.ly/2XQcmgX