2.5 KiB
FR-1 Trace lengths
The experiment
For the experiment, I used FR-1 that has a thickness of 35µm. On there I will mill 4 trace sizes (0.4 mm, 0,6 mm, 0,8 mm and 1 mm) and they all have the same length of 7.5 cm’s. The traces are seperated by 1 Cm.
In this experiment I will measure the temperature of the traces with a multimeter and a thermal laser. I will also watch the board closely for any damage. Since it is FR-1 I expect it to shows signs of damage under heat
Results
the power. So I grabbed an old robot with 4 stepper motors attached but I could not get them to draw more than 30 watts. So that is why the maximum in this test is 30 watts. I also had a hard time finding a way to measure the temperature of the traces because we only had a heat gun here and the laser was not the place it was actually measuring. So 0,4 mm is not measured properly.
Trace Width Trace | Resistance | Maximum safe wattage | Burn out wattage |
---|---|---|---|
0,4mm | 3,1Ω | 15 | 20 |
0,6mm 2 | 2Ω | 22 | 26 |
0,8mm | 2Ω | 27 | ?? |
1mm | 1,85Ω | ?? | ?? |
- The 0,4 mm trace was the first one I tested. I started with 15 watts and it was stable at 23.8 degrees. After that I increased the wattage to 20 watts and the trace instantly exploded and burned so I could not get temperature readings there.
- The 0,6 mm trace it held up well up to 27 watts where it started getting burn marks within a 5-10 seconds. The temperature rose to 45 degrees celsius. At 29 watts the pcb burned out at 68 degrees celsius.
- When testing the 0,8 mm trace I hit a roof with how much power I could consume with the robot. I could only get up to 30 watts and I did not manage to break the trace. The maximum I found before it started discoloring was 24 watts at 54 degrees celsius. This was measured after it was left on for 2 minutes.
- I could not get to the 1mm trace because the robot could not draw more than 30 watts. So thats why these are not filled in the table.
Recommendations for next time
Make bigger pads to hookup the power easier to the pcb and maybe remove all the excess copper but that takes a super long time.