So, I'm kinda new to the field and the time has come to design my first PCB heater. The main concept is to drive it using a Raspberry Pi and a temperature sensor as feedback.
Here is the whole procedure I followed in steps.
- Since my AC/DC adapter outputs 12V/3A I need a heater around 4 ohms in order to be efficient.
By using this trace width calculator and applying the following values I managed to get a result of 3.73 ohms and a voltage drop of 11.2V.
current: 3Amps thickness: 35um temp rise: 65 (I want to be able to reach 90C) ambient temp: 25 trace length: 7m
Given that I want a heater of 13mm width I calculated the number of traces that will be created. Which is: \$trace\_length/heater\_width = 7m/13mm = 7000/13 = 538\ traces\$
Then by multiplying \$number\_of\_traces\ *\ trace\_separation = 538\ *\ 0.12mm(120um) = 64.56mm \ heater's\ length.\$
Finally, I have a heater with the following characteristics:
length: 64.5mm width: 13mm trace width: 1.14mm trace separation: 0.12mm
I would like to mention here that in calculator's page there are results for internal and external layers. For my calculations, I used the values of the internal layers and I'm not sure if I did well. So what do you think? Is this procedure and calculations reasonable? Would you suggest a different approach?