How do I find the area of my polygon? I am trying to design a polygon that can handle up to 10A. Wanting to verify that my polygon is large enough. Thanks.
Why do you want to know the area? Apart from copper thickness, current handling is mostly dependent on width, while voltage drop will be dependent on the length.
KiCadās own calculator tool, accessible from the project manager can get you into the ballpark numbers for a 10A current handling capability.
Knowing the area of a polygon is not sufficient.
I could easily design a polygon that was a m^2 in size that couldnāt handle 1A (for example, think of a dog-bone or dumbbell shaped polygon with large ends and a thin middle, with contacts at the ends).
I would approximate that as a rectangle, using the narrower end as the width. If that can handle the current, than you can be sure that this polygon can.
ETA: A single PTH may not be able to handle 10A, depending on the hole size. At the very least, I would put a copper surround on both sides of the board, and tie them together with vias.
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I donāt know the scale of that thing, but if those vias are of ānormal sizeā Iād guess the track width is less then 5mm. According to KiCadās calculator that would result in a temperature rise of > 10 degrees centigrade. Not a real problem, but you will start creating some voltage drop (also in the calculator) and you will loose some efficiency.
If you want to improve upon that there are also various methods. The most used are:
- Wider tracks.
- Thicker copper.
- Copper on multiple layers.
- Adding solder to the tracks. (make cutout in the solder mask for this).
- Soldering thick wires or bus bars over the tracks.
Pretty simple and the Toolās are includedā¦
ā¢ Calculation happens for a Zone
ā¢ The Zone can be on any Layer
ā¢ Can Copy & Paste your shape to empty area for temporary calculation (thus, avoiding messing up your layout)
Example shows a Copper-Filled shape and a Silk-Polygon
Doesnāt matter what layer gets selected, you just want to get the shape for calcā¦ (I left Silk layer selected in panelā¦)
Result āAreaā is shown at bottom of PCB-Window
UPDATED: Now includes some Pad areas that get subtracted from Areaā¦ Oh, and best to Select the Cu layer in the PCB Panel first in order for them to show in the Zone/etc panel (otherwise they donāt show (in version 7, donāt know about v8ā¦)
Is there anything like an online Finite Element Analysis tool for this sort of thing? It could use gerber files.
I am no expert on finite element analysis, but basically I think it can break down a polygon into a finite number of equipotential pieces and count them up to determine current density and voltage drop. Then there is the question of localized power dissipationā¦
You could look for somethingā¦
Many Graphic programs do it without Gerberā¦ just copy/paste the graphic or import it into the programā¦ example below done in EZdraw. I suspect Inkscape has plugin for it if itās not natively embedded
Would anyone be interested in reviewing my PCB with me to make sure I have designed it properly? Perhaps by Zoom or similar? I would be willing to pay for a little coaching and discussion. I am in US Eastern Time Zone. Or maybe I could send you my file for review and email discussion?
Iām not a fan of LibreCAD but, it can be usefulā¦ itās Free and can easily get Area of Polyline shapes and, can load external images and simply trace them with Polylines and get Areaā¦ other ways to do, I suspectā¦
I have taken a quick look. It was an idea about which I wondered if someone else knew of such a tool.
I think that Mentor (for example) might use FEA to calculate pcb voltage drop. But I get the impression that nobody has offered a lower performance free version of something to do the task. Not being a programmer, I have no idea how much work goes into developing such a tool.
The Saturn PCB Toolkit is my goto for checking current ratings and many other useful calculations
https://saturnpcb.com/saturn-pcb-toolkit/
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