standard stencil opening for qfn

[vivian_dao]

yes, i would like to know what is industrial standard stencil opening vs. recommendation stencil opening for qfn

[Sal Hernandez]

The manufacturer's data sheet should provide you with the solder paste layout and dimensions. In general the solder paste pads for should be the same size (or slightly smaller) and shape as the physical pads you will be soldering to. The only exception is the center pad which should have a crosshatch configuration. It is best to review the data sheet for the part you are going to use but here is one example that you may find helpful.

http://www.ti.com/lit/an/sloa122/sloa122.pdf