Passive cooler in Raspberry Pi 3

Following the article that teaches how to monitor the temperature of a Raspberry Pi 3, let’s describe a process to avoid the temperature to rise without a fan-based cooler.

Necessary parts:

  • A cut tool, for example a mini drill.
  • A heatsink 1.38 x 1.38 inches (saved from an old motherboard).
  • A BGA heatsink 20 x 20 x 1 mm. (can be obtained in ebay).
  • A Raspberry Pi 3 case.
  • Thermal paste.
  • A piece of hard plastic (saved from a case, for example).
  • Scissors.

First of all the heatsink can be obtained from an old motherboard. The following was obtained from an old Asus MB, this was the chipset heatsink.

It is important to point out this heatsink was cut with the mini drill.

The idea is to put this heatsink over the Pi 3 processor. Unfortunately, as can be seen in this photo,

just adding the heatsink over the processor can short-circuit some component because the heatsink is a good electricity conductor. To solve this issue lets add between the main processor and the heatsink, a small heatsink (BGA), to increase the gap between the other components and also, make a plastic mask, to add an extra isolation level.

With the help of a paper sheet, lets make a mask letting exposed only the processor, and after that, let’s use this paper sheet as a template to the plastic. The result should be just like the image that follows:

After adding this mask in the Pi 3, let’s put the thermal paste over the processor and add the BGA heatsink (as shown):

Over this heatsink, we will add more thermal paste and add the second and bigger heatsink. In the next photo there is a test to see if this approach made any difference:

In this particular case, the temperature never got over 145,4 F.

Now, with the help of the mini drill, a hole was cut a bit smaller than the heatsink ( in order to increase the pressure between the heatsink and the processor) and keep all in the right place.

I believe this is enough to cool down any Pi 3. It is worth to remember that the BGA heatsink bundled with many cases must be used to cool down the integrated circuit in the other side of the board, that’s why a new BGA heatsink must be acquired.