Surface PCB capacitor

[Malecki_gerard]

Good morning,

Is it possible to have in Kicad capacitors made with the surface of the PCB.
For example a 0.5pf capacitor can be made by 2 surface of 4.7 * 4.7 mm.
Are there any symbols, footprints???
Otherwise, it is necessary to imagine some zones, but the schematic is difficult to create in this case.
Some ideas?

cdt

[BlackCoffee]

You can make a Schematic Symbol.
You can make a Footprint.
You can link the Footprint to the Symbol (if desired).

I use and make them per project as needed.

The Capacitance values depend on various factors from PCB dielectric to Copper… etc. Since I use them for Touch Switches only, I don’t worry about the dielectric, preferring to set their sensitivity in programming (usually Arduino).

Two examples… One Schematic Symbol that I link to different Footprints, as needed. And ‘Dumb’ capacitance switches from early prototyping…

With schematic Symbol

[Malecki_gerard]

Hello Blackcoffee,
It’s a nice design.
Actually I’d like to use both layers, but it’s a little bit more complicated to do a footprint (?)
I found this site to calculate my 0.5PF capacitor.
https://chemandy.com/calculators/rectangular-capacitor-calculator.htm

I think you use only one layer, but I wonder if this is more valid for selfs.
Do you have a internet site that does your design and if it has a calculator?
so to do my 0.5 PF

cdt

[Malecki_gerard]

I think it’s more of a “touch” button than a capacitor you made. Thank you

[BlackCoffee]

@Malecki_gerard

Actually I’d like to use both layers, but it’s a little bit more complicated to do a footprint (?)

@Malecki_gerard

calculator?

You can use Both Layers if desired (Yes, as I said, I use them for Touch Switches). If on Two layers, the PCB/materials influence the Dielectric. Not a problem to get what you want but, need to consider environment’s Capacitance influence. And, would most likely want a full size Pad on both Top and Btm (instead of Segment lines). Similar to that shown in the Prototype example above with Acryllic. Either way, I set the Cap sensitivity in Programming.

For a Footprint, you can Draw the Traces (with the Line Drawing tool) and set them to Top/Btm layer’s… Screenshot (I did NOT bother to make Full-Size pads/Traces for this example but, you get the idea…)

Kicad’s ‘Calculator Tools’ (in main panel) has a Transline that can be used for estimation…

[john3]

The plate size is not the only issue in determining capacitance. Distance between the plates and dielectric material is also important, as is routing in proximity of the component.

For example, two traces in close proximity will have capacitive coupling.

[leoheck]

Dude, you make your symbol, footprint, board the way you want. The other guy won’t make it for you, I guess. Come on, don’t be lazy. It is a free software. Download it, and try it yourself.