Need help for package naming (SOP-20)

Schematic Library Symbols
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Hi,
I’m new to KiCad, and creating my own libs (+ 3D models), as I did with the previous software I’ve been using for years…

I’m also new to SMD ; until now, I’ve always been using through hole components, and I’ve always been making my PCBs at home ; I got two pratice kits with tiny components that are still laying untouched on the workbench…

At this time, I never created a PCB with KiCad. I only captured schematics of what I’m doing on breadboards (9 months). But I’ll soon have to make them run on PCBs.

I created a 3D model for this package : https://www.mcielectronics.cl/website_MCI/static/documents/Datasheet_TM1637.pdf

I didn’t find the exact same package in the default libraries. SSOP SOIP QSOP, etc. I’m completely lost in datasheeets, and I didn’t find a clear description for all the “SOP” variants (Wikipedia helped a bit). DIPs are easier…

I don’t know how to name the package. Should it be “SOP-20_7.65x12.7mm_P1.27” ? And I don’t know what footprint (pads) should be associated with this package ; It seems I have to create it.

With the footprint wizard, it could be :
pads : 20, rows : 2, pitch : 1.27, pad width : 0.6, pad length 2.2, row spacing : NOT sure how to calculate row spacing ! Do you know of a reliable link ? Row spacing, pads dimensions, silkscreen spacing, etc. (obviously many rules depend on the PCB naufacturer)

Last question : reading (tons of) datasheets about passive SMD components, they come with different heights (as through hole do…). The KLC says : just add height after “XxY”. Is that correct ? And same for footprints : one height = one footprint ? Correct ?

Switching from one EDA to another + through hole to SMD at the same time is not easy !

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If you are creating a new package, you can name the package whatever you want if its for your own use. You only need to worry about package naming if you plan on contributing to the KiCad library.

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The one figure that jumps out is the e distance. Filtering helps. You can use the measure tool also to double check.

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image1290×999 155 KB

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@Qbort : yes, I know, but using the same conventions makes things more consistant and easier, and I will share my libs on Github. I already shared a few (they are crap, even if some folks liked them - updated ones are on the HDD and will be uploaded soon) : https://github.com/yet-another-average-joe/Kicad-STM32 ; This week I created 400+ 3D components : mainly pinheaders + some other small chinese modules. From scratch, because I like it.

@hermit : I already played with the wizzard. I’ve no problem with it ; (adding 1.27 in the keywords refines even more the search :slight_smile: )

But the wizzard is based on some rules. I’d like to read documents about these rules. Is it documented somewhere on KiCad website ? (I didn’t find)

Writing this, after an hour with Google, I found an interesting document ! https://www.ti.com/lit/an/sbfa015a/sbfa015a.pdf?ts=1599956101073&ref_url=https%3A%2F%2Fwww.google.com%2F

[EDIT] and it adds some confusion… should be SO-20 according to this doc (1.27 pitch), but SOP-20 in the datasheet. My understanding now : SSOP = shrinked (smaller), and SO = SOP. These acronyms are ununderstandable…

I’d like to create this footpint + symbol + 3D model so someone tells me if it is KLC compliant (I already made the 3D model and the symbol). But I first need to find some information about how to design pads, not only by naked eye on the screen.

How do you post images ? I’ve no attachment button…

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The datasheet suggests this to be a standard gullwing package so if there is no fitting one in the lib then you can use the generator found here: https://github.com/pointhi/kicad-footprint-generator/tree/master/scripts/Packages/Package_Gullwing__QFP_SOIC_SO

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Looks like a 300mil wide SOIC (SOIC-20W_7.5x12.8mm_P1.27mm)

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Thank you for the answers !

IPC-7351B and Gull Wing are the keywords to the second question (found on the Github link) : will give all the needed informations about the packages.

SOIC-20W_7.5x12.8mm_P1.27mm is the answer to the first one. I didn’t find because I was searching “SOP” instead of “SOIC”.
Wikipedia : “SOP are sometimes called wide SOIC”.
IPC-7351B : SOIC or SOP : https://www.pcb-3d.com/electric_type/small-outline-packages-sop/

KLC : “[PKG] refers to the name most commonly used in the industry. Generally this implies JEDEC naming but some other standard may be used as required” . On the JEDEC website, SOP and SOIC seem to refer to the same package “Item 11.11-972(E)”.

Do KiCad contributers prefer SOIC ?

I now have more keywords, a better understanding of the KLC, and normative institutions I can refer to.

Thank you all.

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I believe wide SOIC is what this package is most commonly called. At least Texas, Analog and Maxim call it that.
But then, the official lib has SOIC-8, SO-8, SOP-8 and possible more which are all the same footprint.

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