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As I am about to assemble my construction (Raspi 3B with 2 HATs on top + tuner + amplifier board next to the Pi) into a fairly tight (18 cm × 11 cm × 4.5 cm) metal enclosure, which will be then built into a car dashboard, I'd like to know how to lead the excess heat of the Pi's CPU to a massive aluminum heatsink, which is located some 9 cm away from the Pi's CPU on the left side of the enclosure. The amp and the regulators touch the heatsink and are therefore not problematic, but the Pi and the heat it produces might be an issue: As the Pi will decode and play MP3 files, CPU load may grow quite high for extended periods of time.

So: What should I employ to get the heat the Pi produces to the heatsink? The only solution I've found is copper tape (1 cm wide) attached both to the heatspreader of the CPU, and the heatsink. Would that be sufficient?

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  • you can answer your own question experimentally ... attach a short lenth of the copper tape to the CPU ... run the RPi ... measure how warm is the free end of the copper tape ... you will probably find that the tape is insufficient for transporting heat
    – jsotola
    Jan 6, 2022 at 2:05
  • laptops use teeny heat pipes for this sort of thing...but that's probably overkill here.
    – user10489
    Jan 6, 2022 at 3:12
  • A heatpipe is not flexible, so I can't use it here.
    – Neppomuk
    Jan 6, 2022 at 21:25

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You could use a peltier or liquid cooler. You can see examples in PCs. I hope you have protected the power supply for the harsh environment it will see in a car. Also check the maximum temperature expected in that area, I think it is rated at 85C. And then when you doubt it think of Arizona in the desert during August in the sun. Also I believe the Raspberry Pi 3+, has a 'soft' temperature limit of around 60C. When this reached it will slow the clock before it reaches the hard limit at 85C, the clock speed will be reduced from 1.4GHz to lower frequencies, decrease the temperature rise to the components. I would not recommend this especially if you plan on building them for sale. You can validate this by reading AEC-Q100 for the classes and what they indicate. https://electronics.stackexchange.com/questions/301826/how-to-determine-temperature-grade-for-automotive-electronic-components

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  • As far as Peltier coolers are concerned: Don't use them! They are very inefficient and unreliable. I know this from my own experience.
    – Neppomuk
    Aug 11, 2022 at 20:49

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