topic Why the two choices for footprints for surface mounted capacitors in RCL library? in Fusion Electronics Forum

Why the two choices for footprints for surface mounted capacitors in RCL library?

markgEVY95 — Thu, 07 Aug 2025 19:25:46 GMT

Does anyone know the reason behind the existence of two choices for footprints for surface mounted capacitors in the RCL library. For example, for capacitors with 0402 case one can select either C0402 or C0402K. The main difference between the two is that pads in C0402K are more closely spaced.

Re: Why the two choices for footprints for surface mounted capacitors in RCL library?

jorge_garcia — Fri, 08 Aug 2025 23:03:15 GMT

Hello @markgEVY95 ,

I hope you're doing well. I don't know the exact reason but I vaguely recall the K being associated with KEMET. Perhaps at some point they had a specialized footprint specified for some reason.

That's the only thing I can think of.

Let me know if there's anything else I can do for you.

Best Regards,

Re: Why the two choices for footprints for surface mounted capacitors in RCL library?

Evert_2N3055 — Sat, 09 Aug 2025 11:38:37 GMT

What I remember is that you have one footprint for wave soldering and the other for paste soldering with a stencil.

For wave soldering you need some more clearance so the wave can reach all the pads.

Not sure if wave soldering is still used, it requires that the component is first glued to the pcb before soldering. Stencil soldering is even for big production now these days the way to go.

Re: Why the two choices for footprints for surface mounted capacitors in RCL library?

chuck_toddN7PTC — Mon, 11 Aug 2025 13:04:39 GMT

Could it be that the two footprints are SMD (Solder Mask Defined) and NSMD (Non-Solder Mask Defined)?

https://www.pcbway.com/blog/technology/SMD_VS_NSMD_981fef82.html

BR -Chuck

Re: Why the two choices for footprints for surface mounted capacitors in RCL library?

markgEVY95 — Mon, 18 Aug 2025 14:23:18 GMT

In my boards, which are all assembled with the reflow method, I used the non-'K' version of surface mounted capacitors, except in one board where I had used both C0402 and C0402K. I think using both versions in the same board confused the board house to the point that they wanted to put 0603 capacitors into the C0402 pads. That is the reason that I've asked the question in my initial post.

The impression that I got from the replies, is that rcl library is old and that it had both versions of the footprint for SMD capacitors for the long time. I am wondering whether Audodesk is till recommending the use this old library in new designs and whether there exists an alternative Fusion public library for passive components.

Re: Why the two choices for footprints for surface mounted capacitors in RCL library?

jorge_garcia — Tue, 26 Aug 2025 18:55:47 GMT

Hi @markgEVY95 ,

The rcl library is old. We now recommend using the Capacitor and Resistor Fusion Electronics libraries.

Let me know if there's anything else I can do for you.

Best Regards,

Re: Why the two choices for footprints for surface mounted capacitors in RCL library?

markgEVY95 — Tue, 26 Aug 2025 19:45:11 GMT

Hi Jorge,

Thanks for the information. There is also the Fusion Inductor library out there.

Mark