SODF OR DFN
Printed From: PCB Libraries Forum
Category: Libraries
Forum Name: Altium
Forum Description:
URL: https://www.PCBLibraries.com/forum/forum_posts.asp?TID=3634
Printed Date: 16 Apr 2026 at 2:01am
Topic: SODF OR DFN
Posted By: dramos
Subject: SODF OR DFN
Date Posted: 15 Apr 2026 at 10:23am
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Hi Tom and Team, I was working in this SOD-523 diode, onsemi part number https://www.onsemi.cn/pdf/datasheet/rb751s40t1-d.pdf" rel="nofollow - RB751S40T1G . Suddenly, I had a doubt with a value because the length of the pin is 0.30mm REF, I was thinking to use +/-0.05mm of tolerance but I said to my self: "how PCBFE resolve this question? and I've gone to the Parts area and bingo! it is ready to download. After downloading I opened it and It was not similar to a SOD-523, it seems more a DFN component.  Could we consider this kind of components a DFN and why? My first impression has been: the footprint is no correct but then... and why not? I attached the downloaded file as well. uploads/15739/onsemi_RB751S40T1G.fpx" rel="nofollow - uploads/15739/onsemi_RB751S40T1G.fpx My component was more "traditional"  I attached as well my component fpx uploads/15739/david_RB751S40T1G.fpx" rel="nofollow - uploads/15739/david_RB751S40T1G.fpx Anyway I am not very happy with my footprint and as now we have a new feature where we can modify the corners of a footprint when the pad is rounded rectangle or chamfered pad.  Using this feature I created the inner corners of the component squared and outer corners rounded. the inner corners are under the component and perhaps are more close to s DFN... What's your opinion?  Thanks for your comments, they are always really appreciated. Regards, David
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Replies:
Posted By: Tom H
Date Posted: 15 Apr 2026 at 10:47am
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This package is definitely a SODFL package. A DFN is a BTC package where the terminal lead are completely under the package body. DFNs do not have terminal leads that protrude outside the package body. SODFL:  DFN:  ------------- Stay connected - follow us! https://twitter.com/PCBLibraries" rel="nofollow - X - http://www.linkedin.com/company/pcb-libraries-inc-/" rel="nofollow - LinkedIn |
Posted By: dramos
Date Posted: 15 Apr 2026 at 11:49pm
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Dear Tom and Team, Yes, I thought the same about SODF and DFN. So I consider that the footprint I created is correct. In the other hand, it is my question about the shape of the internal corners of the pad. On our company, when we create a footprint we build it with Nominal density option and Most density option. The program allows to do it in a very fast and easy way. In both cases, the value Side and Heel is 0.00. It could be similar to the value 0.00 that we have in the Periphery parameter on a DFN. Furthermore, there are some SODF components where the lead is below the body, for example the mentioned RB751S40T1G. Yesterday, when I saw the component that I downloaded I started thinking that perhaps it had sense and It could be done using the new features that Altium developed. I know that it could be a crazy idea, but I would like to start this discussion with you because in PCBFE you have a big and long knowledge. You've been involved in footprints for decades. In my company there is not a dedicated librarian to share with him this kind of ideas. Anyway, thanks for your comments. david |