- Stencil parameters for the EP (Exposed Pad) such
as aperture area ratio and the fabrication process have a significant impact on paste
deposition. Inspection of the stencil prior to placement of the QFN package is highly
recommended to improve board assembly yields. If the via and aperture openings are not
carefully monitored, the solder can flow unevenly through the EP. Stencil parameters for
aperture opening and via locations are shown in the RTV package drawing in the Mechanical, Packaging, and Orderable Information.
- The EP of the package must be connected to the
ground plane through a 3 × 3 via array. These vias are solder-masked to avoid solder
flowing into the plated-through holes during the board manufacturing process. Details
about via dimensions are also shown in the RTV package drawing in Mechanical, Packaging, and Orderable Information.
More information on the QFN style package is
provided in QFN/SON PCB Attachment application note.