NXP’s app note about the internals and how to’s footprint design and solder their leadless dual and quad flat packages. Link here (PDF)
The small outline no-lead (SON)/quad flat no-lead (QFN) is a small size, lead-less plastic package with a low profile, moderate thermal dissipation, and good electrical performance. It is a surface mount package with metallized terminal pads located at the bottom surface of the package. SON have terminal pads along two opposite edges of the package versus QFN with terminal pads along the four edges of the bottom surface. SON is sometimes also referred as DFN: Dual flat no-lead package.