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DFN and PSON footprint differences

Printed From: PCB Libraries Forum
Category: Libraries
Forum Name: Footprints / Land Patterns
Forum Description: [General or a CAD specific issues / discussions]
URL: https://www.PCBLibraries.com/forum/forum_posts.asp?TID=3495
Printed Date: 19 Jun 2025 at 8:39am


Topic: DFN and PSON footprint differences
Posted By: dramos
Subject: DFN and PSON footprint differences
Date Posted: 16 Jun 2025 at 11:10pm
Hi Tom and Team,

When I am creating footprints I have as a rule of thumb, to use rounded rectangle pads except for DFN, LGA, PQFN and Thermal pads. For this footprints I use rectangle pads

What about PSON? I think that this footprint has the pads underneath the body as a DFN and It should use a rectangle pad, as well.

What is the default recommendation for this footprint type?

Regards,
david


Replies:
Posted By: Tom H
Date Posted: 17 Jun 2025 at 7:13am
PSON is the same as PQFN as both have Pull-Back leads under the package body. 

PSON/PQFN terminal leads come is 2 shapes. 
  1. Rectangular Lead = Rectangular Pad
  2. D-Shaped Lead = Rounded Rectangle Pad
LGAs have 2 terminal lead shapes. 
  1. Square Lead - Square Pad
  2. Round Lead = Round Pad
DFNs have rectangular leads

Thermal Terminal Leads come in 2 shapes.
  1. Rectangular 
  2. Rounded Rectangular 



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Posted By: dramos
Date Posted: 17 Jun 2025 at 10:33pm
Hi,

Many thanks for the explanation! 

I am working on the Calculator Option File, and I would like to share with you one idea.
When we are configuring the default Pin1 orientation, Pad shape... In the Components-Surface Mount , Would be very crazy - no sense idea - to separate into two different options the QFN and PQFN. SON and PSON is another example.

The reason is the next, if we have a PQFN component with rectangular leads of course we will use a rectangular pad, but if we have a QFN footprint with a rectangular lead perhaps would be interesting to use a rounded rectangle pad.
uploads/15739/example1_2025-06-17_22-32-35.png" rel="nofollow - uploads/15739/example1_2025-06-17_22-32-35.png

Thanks for your comments.

Best regards,
david

Posted By: Tom H
Date Posted: 18 Jun 2025 at 9:01am
Is this a New Feature Request? 

If so, you're in the wrong Forum Thread. Go here - 
https://www.pcblibraries.com/forum/product-suggestions_forum33.html" rel="nofollow - https://www.pcblibraries.com/forum/product-suggestions_forum33.html

The component families are grouped together for easy code changes. 



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Posted By: dramos
Date Posted: 18 Jun 2025 at 2:59pm
Hi,
It was not a Feature Request at the beginning of all...

But as I realized that the Option configuration could create confusion between the users, YES I will add it as Request improvement of the program.

Best regards,
david


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