[SOLVED] Footprint for EL817S1 (SMD version of EL817 / PC817 opto coupler)

Hi fellow KiCad people, probably another KiCad beginner request, but … :wink:

I need to get the footprint for an EL817 (SMD version S1) opto coupler as I found the DIP footprint only. I tried Digikey but it does not offer a solution. The dimensions of the part are ~10mm x 3.9mm.

Can anybody point me towards a suitable SMD footprint for the part? I cannot imagine that the SMD version of this part is sold with no footprint available on the internet. TIA!

Hi b3422,

You might find something suitable in the Kicad footprint library. Opto devices could be a good place to start.
Failing that, you may find something in a Kicad library suitable to modify to your needs and failing that, you could always build a footprint from scratch.

There is lots of information in FAQ at the top of this page.
Maybe start with:https://forum.kicad.info/t/tutorial-how-to-make-a-footprint-in-kicad-5-1-x/11092

Well, that would have been a lot easer for me if you had provided a datasheet. Here is the one that I found:

It looks like all the SMT variants are just a re-forming of the leads on the same 4-pin DIP package. Page 9 of the datasheet gives the manufacturer suggested dimensions for the pad layout for a footprint, and often that is all the designer gets for a footprint (partly because there are so many different EDA packages out there all with incompatible library file formats). What I would do is take the 4-pin DIP package from what ever library I’ve decided is standard for me to modify to a new footprint for this part. Just change the pads from THT to SMT, re-size and position according to the datasheet. Then just double-check the other layers and modify them if needed.

Refer to the link that @jmk provided (and the links in that FAQ item) for a better understanding of footprint (and general library) organization, maintenance, and creating new assets (either from scratch or as I suggested above based on an existing asset). I’d like to highlight one point that a lot of newbies don’t get right away: The libraries that come with KiCad are read only. This is because they will get changed when you upgrade KiCad and if you had saved your own edits there you will loose your edits. You will need to set up your own personal libraries to collect all your new footprints and symbols. This FAQ (which is linked in the FAQ that @jmk provided) gives good and sensible organization ideas for your own libraries.

I’m with jmk.
The Internet is too big to search (long) for a simple footprint.
Making your own footprints (or modifying existing) is quite easy and is an essential part of PCB design.

Lot’s of newbies have an incomprehensible aversion to this and I do not understand why. The quality of the footprint editor and the ease of use was one of the reasons for me to switch to KiCad.


  • Thanks a lot for the links! Looks like there is a bit of RTFM ahead of me
  • I copied and modified a footprint myself with amazing little problems
  • silkscreen and fab lines were not on the grid even when I went down to 5mils. Does it need to be this way??? Seems like I never bothered to check this out so far.

There are a few things which I would like to share:

  • when it comes to recommended footprints (size / location of the pads) it seems a good practise to look out for a data sheet with a sort of latest revision
  • the footprint I used had the silkscreen layer and the fab layer were anywhere but on a grid (???) I had no problem with this “feature”
  • changing the location / size of a soldering pad is easier than I thought it will be
  • as a newbie it seems to be irritating that there is more than one way to get a result (read: to create a footprint), e.g. when it comes to point out where pin 1 of the SMD part is.
  • I found out how to assign multiple footprints to a symbol which I found out about only yesterday (I am on the nightly snapshot in case it matters)

I guess I could go on, but I think I mentioned the most important things I experienced.

Some parts of a footprint are positioned on a 50 µm (0.05 mm) grid.

I know that it comes from experience, but you should expect common footprints like this to already be in the KiCad libraries. As already mentioned, they are an SMD version of a standard DIP package. If you look in Package_DIP, you’ll find that one of the SMDIP-4 variants will be right for you. The pad dimensions might vary a bit, but that depends on the solder fillet size that it was designed for. You’ll also notice that there’s a “Clearance8mm” variant, which should give you a hint that it’s intended for optoisolators.

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