FEDEVEL
Platform forum

Mirco , 05-25-2025, 10:04 AM

Hello everyone, I would like to make a pcb with a serpentine that acts as a heater to ensure a constant temperature at imu. The serpentine would be placed in the intermediate layers of the PCB. Is it possible to make this? How can I act to reduce the noise?

QDrives , 05-25-2025, 03:32 PM

Of course it is possible to make this.

But I do not understand your 'noise' question.
Or are you talking about thermal noise? If so, you do not want to heat it.

Mirco , 05-25-2025, 09:00 PM

With "noise" i by noise i mean electromagnetic noise. is it possible that the presence of the serpentine can increase the presence of electromagnetic noise on the various signals?

QDrives , 05-25-2025, 10:07 PM

Of course it will increase the possibility of EMI issues. Both emission and immunity. You are creating an antenna.
However, if you do it right, there is no problem.

Robert Feranec , 05-26-2025, 07:16 AM

Carl made some videos about heating PCB, for example this one, but he has more: https://youtu.be/r0csHZveVvY?si=Ua6WSd3P_rRHBmwA

Mirco , 05-26-2025, 07:27 AM

Thank you so much! I will update the post to ask for advice🙂

Mirco , 05-26-2025, 07:28 AM

Thank you so much for your support, very kind!

Mirco , 05-27-2025, 11:04 AM

Is it obviously necessary to use a current regulator? If so, what type of current limiter is best suited to work with a maximum current of 0.5A in the heater and the power supply is 5V? @QDrives

QDrives , 05-27-2025, 09:36 PM

To get 0.5A with a 5V supply you need 10 ohm resistance. That would be very hard to get with a PCB trace.
PCB tool kit: 100mm long 0.1mm wide inner layer 35um trace will have 0.62 ohm and will cause 20°C rise with 1A.

There are 2 ways to limit the current:
- Linear, but the linear regulator will heat up much more than the traces.
- Add an inductor and use a switch mode 'regulator'. Naturally this will cause more EMI, hence the inductor. A MCU can also drive the PWM, so you do not need a special regulator.

Mirco , 05-28-2025, 07:42 AM

Thanks for the reply.
The coil design is:
- Power dissipation: 2W
- Current: 0.5A
- Power supply: +5V
Coil resistance = 8 Ohm, with track length L = 1330 mm (approx).

I actually use an NMOS to drive the coil, driven by PWM. Of course I have a temperature feedback.
So if I use a PWM, I don't need a current limiter?

In addition, the coil design could be wrong, in fact I would like to reach a temperature of 60°C.
If you think the design is wrong, could you recommend me a guide to follow to make a good coil design?
Thanks again

QDrives , 05-28-2025, 03:27 PM

It depends, if you get something like 8 ohm (16x16mm 0.1mm track width and spacing) with 5V you get 0.625A and 3.125W.
Add the MOSFET resistance for the calculation.
With that high resistance there is no need for an inductor too, unless you are switching a higher frequency (> 1kHz).
For higher temperatures, you need more power and/or remove plane cooling.