Creating A Track Resistor - Page 1
Forum section: electronics / projects

author: tmd63
author_rank: Contributor
timestamp: December 20, 2023, 10:14:13 pm
content: I have an unusual issue that I need some help with.I have to create a resistor heater using a 1.6mm PCB and having 1oz copper. The trace will be serpentine across the PCB and it needs to withstand 10A at 24V Max.. The power will be varied at the source, but the heated trace must fit on a 100mm by 60mm PCB which gives a maximum area of 6,000 mm2, assuming 0.5mm gap with a 3mm trace, How do I work out the trace area used without resorting to graphical methods and trial-error?

author: tooki
author_rank: Super Contributor
timestamp: December 20, 2023, 11:03:00 pm
content: This calculator may be useful: just leave one field blank and it will calculate it based on the others.https://www.eeweb.com/tools/trace-resistance/A 3mm wide trace would have to be 15+ meters long to give you the resistance you need (2.4 ohms). Try a lot thinner.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: December 21, 2023, 01:13:56 am
content: Quote from: tmd63 on December 20, 2023, 10:14:13 pmWhat temperature do you want this to heat/regulate to ?Keep in mind the resistance can change 30% or more, and you may need to worry about the copper thickness variations.

author: EPAIII
author_rank: Super Contributor
timestamp: December 21, 2023, 08:27:37 am
content: Depending on the temperature you need, copper laminate may de-laminate from the PCB. And as others have said, the resistance can vary.Just my humble opinion, but I think you would be a lot better off with a grid of surface mount resistors or better yet, some resistance wire made for heater elements and held in place with mechanical means (like wires through holes in the PCB or just weaving it above and below the board - mostly above, of course).https://www.mcmaster.com/products/heater-wire/easy-to-form-nickel-chromium-alloy/

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: December 21, 2023, 07:31:45 pm
content: Or buy a flexible heater like Minco and bond it on. It's the right part for the job!

author: babysitter
author_rank: Frequent Contributor
timestamp: December 22, 2023, 02:20:11 am
content: I once made a few prototypes of PCB with electrodes for some electrochemical stuff on one side, and ~12 mil Au plated Cu traces on the other side in Hilbert curve inspired path (had some bumps to go around) with 4-wire attachment for heating. Measuring voltage drop allowed some idea about the temperature of the structure.BRHendrik

author: tmd63
author_rank: Contributor
timestamp: April 24, 2024, 05:17:40 pm
content: The trace was to operate from -40 to 70 degC but I have no idea as to the Mass it was being attached to.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: April 24, 2024, 08:07:57 pm
content: Quote from: tmd63 on April 24, 2024, 05:17:40 pmDid you get a working solution to your December post problem above ?15 seconds with a trace calculator finds that a 3mm trace, even 10,000mm long is 1.62 ohms,ie you have blown your PCB area budget, while still well short of your resistance budget.240W into a board that small, will rocket past 70'C very quickly.