PQFN/PSON Footprint Name

Here is a component manufacturer that produces QFN packages with D-shape Package Leads -

 

Here is their recommended footprint with Rectangular footprint pads. Also notice that the Component Thermal Tab has a Chamfer Corner by Pin 1 and rounded corners on the others, but the manufacturer recommends a solid square with no chamfer or rounded corners. So it's really a "User Option".

Also note that the manufacturer is calling the footprint a "Land Pattern" and they are using the IPC-7351 Land Pattern Naming Convention with the JEDEC variation in the Land Pattern Name (W6) to discriminate the Thermal Pad size.

 

 

The minimum SMT component to component body or component pad to component pad gap is 10 mil (0.25 mm) for different components.

 

The minumum pad to pad gap on the same component is 6 mils (0.15 mm).

 

The minimum pad to thermal pad gap on the same component is 8 mils (0.20 mm).

 

You can also get more information by reading my blog here -

http://blogs.mentor.com/tom-hausherr/ 

 

Copy/Paste the entire Blog into a Word document or print it out to PDF. We don't know how long Mentor Graphics will keep it available.

 

 

I use fabrication shops and common sense most of the time.

 

Example: I went to Google and typed "DFM Guidelines" and I found this PDF file -

 

This document produced in Hawaii surveyed several California Fabrication shops -

You say to pull your planes back 40 mils but traces 20 mils. To me this means that you have traces without a reference plane below them. I wouldn't do that.

 

The main reasons why features need to be pulled back from the board edge is the answer to your question. Is it because the fabrication shop is V-scoring or using a router. When breaking up the panel into individual boards, V-Scoreing can leave rough edges that need to be panelerized plus the process requires recessed features as not to damage them.

 

Does your panel need to remain intact for assembly? If so, there will be breakaway rat-bite holes in the router process.