Washers in M.2 extension board v1.4 too tall

#1

I bought a rockpi4a, rockpi 4a/4b heatsink and rockpi 4.x M.2 Extension board v1.4.

When assembling these three pieces, it showed that the screws nuts from the extension board v1.4 that are intended to be used as distance washers between the rockpi4 and the heatsink where too thick by at least 1 mm.

I tested this by applying a thin layer of the heatsink paste to the SOC, assembling, disassembling and then checking if any the heatsink paste had made it to the heatsink. Which it did not. Then i started to file/rasp off from those four washers, repeating the process a few times, until finally i saw the heatsink paste made good contact with the heatsink on the complete SOC.

Please provide thinner washers with the M.2 extension board that do fit so that the SOC has good contact with the heatsink.

#2

Any picture to show this issue? I think this is not mentioned on the forum before.

#3

No, sorry, i totally forgot to take photos while fixing the issue, and now the rockpi4 is deeply stuck inside my NAS case with 5 SATA disks, ethernet, console, power cabling, so i really don’t want to take it apart and put it together.

I also sent this as email to radxa. For anyone here in the forum who buys the original heatsink and M.2 extension board v1.4, i would just recommend to follow my procedure of applying thin layer of thermal paste, screw together, unscrew and check amount of contact from th thermal paste. If its too little (or none as in my case), have a dremel ready.

I was following btw. the instructions from:

https://wiki.radxa.com/Rockpi4/hardware/M2_extend

Interestingly, on allnets web-page, you can see that they did not insert the two washers (screw nuts) between the rockpi and heatsink:

(second picture, only washer on left screw, not on right screw)

I guess NOT to inserting the washers is one quick way to solve the problem, but you need to have a good feel how strongly to screw in the screws so that that the SOC well connects but is not squeezed.