Efficiently design your PCB involving QFN or DQFN packages with this App note from Microchip.
Successful implementation of QFN and DQFN packages requires special consideration for printed circuit board (PCB) layout and solderpaste stencil production. This application note describes the important items to consider.
QFN packages are physically robust, thermally efficient, and occupy much less PCB space than equivalent QFP packages. They generally have superior lead inductance characteristics. They also present some particular design constraints. QFN packages generally have a row (QFN) or two (DQFN) of perimeter pads (“pads”) around a larger central pad (“flag” or “Epad”) encapsulated in a plastic body. These packages are surface-mounted to the target system PCB by a solder reflow process.