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Just wondering if anyone has tried placing a heatsink on their pi zero? I have an extra one laying around and was thinking about adding it while I'm prepping for my kickstarter arrival, but don't want to have to later remove it due to clearance issues.
I haven't heard from anyone that added a heat sink. If anyone has, I'd like to know, myself.
I have attempted to add a heatsink to the Freeplay Zero and here is my story ....

In my experience, the pi Zero doesn't really get too crazy hot, now it definitely gets warm but with the open game slot there is quite a bit of air flow. I have modded a game cart to 'cover' the slot opening and i still have not noticed any considerable heat difference even with the game slot closed.

I would suggest, before doing anything rash like gluing a heatsink onto your pi, that you attempt to monitor the pi temperature. Perhaps write a script which periodically logs values from
Code:
/opt/vc/bin/vcgencmd measure_temp
This will give you a sense if there is a true need for heat dissipation.

But all that aside, i have tried 3 different configurations for a heat sink on the pi.
1. a 'normal' or even 'tiny' heat sink will not fit on top of the cpu, this is due to other passive components appearing on the freeplay board (essentially there is an inductor in the way)
2. I have a 'ground down' heat sink from a previous experiment which is essentially a slightly ridged piece of aluminum with most of the blades ground down. This would fit between the CPU and the board. But after thinking about it further, i figure that it was not 'really' doing very much. only measurements would prove the effectiveness.
3. After a long evening of playing with my freeplay zero and fiddling with heat sinks, i thought ... perhaps i can mount the heatsink to the 'bottom' of the board under the CPU. Now logically this makes very little sense as the heat would have needed to dissipate from the chip and through the board before the sink would be of any help. But hey, a normal pi heat sink does fit in the case on the 'underside' of the zero board. But again, this is probably a silly idea and not really a functional suggestion.

In summary, i suggest setting up a temp logging script (i'll try to do that later tonight and share), and rather than add a full sized sink try a low profile (~6mm height) if needed. And above all, don't glue the sink to your pi before assembling everything first, triple check that everything will fit! And if putting electronic parts in close quarters, try to use some kapton or electrical tape to prevent shorts.

-Sam
I can confirm with the latest Freeplay Zero v1.0 boards, there is approximately 7-8mm clearance between the top of the Pi Zero CPU to the FPZ mainboard once it is mounted. However, you do not want to get that close with any heatsink you choose.

The inductor Sam mentions above is several mm to the side of where the CPU mounts and will not interfere on a Pi Zero W unless you use an abnormally large heatsink. I don't know if this changed from older versions of the board, but my Freeplay Zero v1.0 that I purchased from the Kickstarter campaign in June this year did not have anything in the way.

Please note, I am using a Raspberry Pi Zero W. If you use the original Raspberry Pi Zero, the CPU is mounted a few mm to the right, and you may hit the SMD component or the inductor (at the very least come very close). If you use one of the other Pi Zero models, you can cut or grind away part of the heatsink or simply mount it slightly off center to gain the clearance you need.
Here's a good picture showing the difference in the Pi Zero models. The Zero W is the left most one. Notice on the Zero W the CPU is closer to the HDMI port and on the other Zero models the CPU is closer to the micro USB ports.

The Pi Zero doesn't need too much cooling. However, if you overclock, like to play for hours on end, are concerned about the cramped quarters, or just believe that its better to be safe than sorry, then I recommend getting a heatsink no larger than 6mm tall (height including thermal tape). Most of the ones sold for Raspberry Pi's or included with Pi cases are this size. Some vary in length and width, but larger ones may require you to cut or grind away material.

The one I have is a generic 14mm x 14mm x 5mm heatsink. It is exactly the same as the ones Ed Mandy (Flavor) sells on the freeplaytech.com website and work well on both the CM3 and FPZ. 

Top down view: Plenty of clearance. You can also barely see the inductor about 5mm to the right of the heatsink. The lighting was poor in this shot. If you go larger than 6mm tall, you may hit the surface mounted component next to the inductor.


[Image: Vu5G8lMh.jpg]


Side view: Notice the slope from mounting. This non-parallel mounting of the Pi Zero is inherent to the design of the FPZ. This will leave you with less clearance in the back than the front. Here you can see the inductor clear as day with the heatsink in the background.

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