- 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 may flow unevenly through the EP. Stencil parameters for aperture opening and via locations are shown in the RTV package drawing in Section 13.
- 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 Section 13.
More information on the QFN style package is
provided in QFN/SON PCB Attachment Application Report.