U-DFN3030-4 footprint anyone?


#1

Please internet, tell me that I don’t need to put down this funny footprint by hand myself and that someone (awesome) else has done it already and can share it publicly?:

I really hope that this footprint is doable and it’s not part of the “arbitrary shaped pads kicad limitation”-like threads :confused:

I’m also a bit suspicious that it would be safe to just use a DFN-4 as snapeda.com seems to suggest, what do you think?


#2

Seeing that the minimum width of a pad is actually 0.5mm (dimension X) I think it’s quite large, and the larger the pads and clearances, the less important the actual dimensions are. I would use something simpler with good conscience.

See also the Note:

The suggested land pattern dimensions have been provided
for reference only, as actual pad layouts may vary depending on application. These numbers
may be modified based on user equipment capability or fabrication criteria.


#3

Thanks for the suggestion! I’m still a bit hesitant to simplify it towards a DFN-4 since the footprint comes from a (low Vf) SMD full bridge rectifier which can have a few watts through it:

So I guess that the thermals that the device might sustain (up to a max of 215 degrees), are the reason of that amount of pad surface?


#4

KiCad Stepup might help designing complex: Kicad StepUp: The Sketcher for Footprint generation

For complex footprints kicad nightly (or the pre releases of v5) is better suited. (Support for custom polygon pads)


#5

Hi,
as @Rene_Poschl already suggested, you may consider to use StepUp for complex fps.
In this case k5 is suggested (poly-line and round rect pads are useful).
I recently added the ability to accept arcs in poly-line pads for fp generation.
Arcs will be discretized to poly-lines and then the pad will be compatible with the actual k5 fp format.
Moreover in FreeCAD you may use a background image, scaled accordingly to your real dimension, as a canvas to draw your pads, as a facility to your designing.
The image could be the screenshot you took from the datasheet.


#6

Thanks for all the feedback, much appreciated! Luckily Natasha and her team from SnapEDA replied within 24 hours, correcting the footprint and even providing a KiCad-compatible one :smiley:

See here: https://www.snapeda.com/parts/SBR05M60BLP-7/Diodes%20Inc./view-part/

Awesome service!