Hi, a little while ago I made an LED audio visualizer. Recently I've been wanting to make it better by putting it on a PCB. I created the schematic, but have come across the problem of what width to make the power traces. I've been trying to do some research but with not much luck. When I made the project with wires I used 18AWG to carry 5v 18amps, I have a 300 led ws2812b, 60 per meter, this should take about 18amps to power with each LED needing 60mA.
The current design that I have has the 18awg wire soldered to the board to provide power from my 5v 60amp power supply.
The board has 1mm width traces from Ground and 5v running to the Arduino Nano V3 that will be plugged into the board. There are also traces that run power the LEDs and a MSGEQ7 audio chip (connected by a breakout board).
I have 0.254mm width traces running data from the audio chip to the Arduino Nano and the same width trace running from the Arduino to the data line of the LEDs.
All components run on 5v.
I used EasyEDA to create the schematics. The red traces are on top of the board, the blue are underneath. Color does not represent anything other than that.
Any help with understanding what width to make the traces on the board that carry power is very appreciated. If you need anymore information I will be apply to reply as soon as I can. Thank you.
If you see any other flaws with my plans, I'm all ears!
Why not feed your ledstrip directly from your power supply?
Sorry I cannot help you with exact width. But order of magnitude will be 5mm wide... or as much as you can fit in between your connector.
Usually you keep as much copper on your print as possible. That will all be gnd. So that will solve your gnd current problem.
You cannot have 18 A go along a pin connection like that. The space between two pins is not enough for your track width.
Everything else is on the board and It's a bit easier to run it from the board since I have a data link to the LEDs. I pretty much did what you said with the entirely wire version of this.
Would you possibly know of any sources that could help me understand how to find the width? Thank you.
I did try a track width calculator, but I got confused on some of the inputs because I currently don't know what they might be, most prominent being the thickness of the trace. I think when I get to printing out a board I'll use pcbway.com, but I don't know what thickness they accept, and what's acceptable on a board.
D4 data probably should have a resistor, that goes to the LEDs.
A0 takes data from the audio chip, probably should add one there too for safety.
Thanks for pointing that out, I don't know why I didn't think of that.
What do you think the thickest I could go would be?
Or better yet, how could I change my design so that I don't need such thick and wide traces?
If I only have the traces going directly to the LEDS have a width of 6mm would I need to have the other powered traces be the same, or could they be skinner without burning out?
Most of the sources and calculators I used found that 18 was okay, and in practice it's worked. In the name of safety and using the LEDs for extended periods of time I would say you are probably correct, but for my purposes 18 seems to be okay. It hasn't over heated or had any issues.
the system will rarely draw the full 18amps. for that to happen all 300 leds would need to be at full brightness which means I blew my speakers out before I melted a wire lol
Thank you for your input though.
What would the maximum amps be that could go through a pcb?
You can use tracks on the board if you have calculated their width not in general way, but based on the thickness applied by your pcb manufacturer. In the table from your post #8 you used thickness 1mm - it definitely wrong. PCBWAY usally uses 0.03 -0.05mm thickness, so for 18A you will need the track of 40-60mm wide.
In such cases, it is also recommended to tin the tracks with an additional layer of solder.
Would I be able to make the traces that go directly to the LEDs as thick as they need to be while the rest stay about 1mm or would that end up frying the other traces?
My understanding of how this works is that the current being drawn will only go down those traces and not the others.
Only the gnd (which should be almost anywhere) and the trace to your led vcc need to be that thick. And indeed, you wil probably be very far below 18A all the time. Also peak currents may be higher without frying anything.
And check the standard copper width! For high current circuits you may use thicker copper layer, but for smaller components you need thinner copper layers. Here you have both, so you need a compromize. With a small soldering iron it may be difficult to solder the ground plane if it is very thick. Also it will store more heat and your component will be at high temp for a longer period...
