contrex
Posts: 8
Joined: Sat Jul 06, 2019 9:17 am

3M tape with heatsink

Sat Jul 06, 2019 9:34 am

I bought an Rpi 3B+ last year and also got a heatsink kit, RS Stock No. 867-9039. Two large heatsinks and one small, and a short length of kind of tape stuff, with the 3M logo and what looks like the word "Adhesive" printed on it. As far as I can see, the SOC takes a large one, and the Ethernet chip a small one. Not sure what the other large one is for.

I couldn't work out how to use the tape. It seems to be only single layered, one side glossy, the other printed side just matte brown paper. I could prise the glossy layer away with my fingernail; it was sticky on one side, so I stuck that to the bottom of a larger heatsink. Then, I thought, I needed to prise away another layer to reveal the other sticky side. Only I couldn't. It seems like there is only one sticky side. I asked on Raspberry Pi Stack Exchange, and got one comment, a link to a YouTube video about another kind of tape altogether. Then the topic was put on hold for being off-topic.

https://raspberrypi.stackexchange.com/q ... tsink-tape

At length, I just peeled off the tape, and saw that the base of the heatsink was covered with a thin, even layer of tacky adhesive. Nothing ventured, nothing gained, so I stuck the heatsink on the SOC, pressing firmly. After a couple of minutes I could grasp it and pick up the pi, case, and all. I tried running the PI and found that whereas a sysbench CPU benchmark using 4 threads previously got the temp up to 82 C, now it stays around 69-70. It still idles around 52 C.

Did I accidentally find the correct use of the tape?

Image
Last edited by contrex on Sat Jul 06, 2019 11:41 pm, edited 1 time in total.

wh7qq
Posts: 1299
Joined: Thu Oct 09, 2014 2:50 am

Re: 3M tape with heatsink

Sat Jul 06, 2019 9:06 pm

The 3M tape is probably a better choice than the black, gooey excrement that some heat sink mfgrs provide. I used that on my 3B which was overheating on some of the bigger Adafruit tutorials with a lot of java and it barely made any difference in the problem. I scraped it off and cleaned the residual gunk off with "goof off" solvent and replaced it with Arctic aluminum epoxy and it dropped 15 or 20 C. Only trouble is that it is "forever" although I foresee no reason to remove it, ever.

3M is notoriously great on anything that is "sticky-side-down" and sandpapers so if you are getting good results, count yourself fortunate to have found the right stuff. I am not familiar with this particular material but I doubt it matters too much which way you apply it.

Moonmarch
Posts: 98
Joined: Thu Mar 07, 2019 1:34 am

Re: 3M tape with heatsink

Sat Jul 06, 2019 11:51 pm

If you are not completely certain that you are using the correct thermal tape, then buy new heat sinks they are not expensive, here is a link to the product:

Easycargo 15pcs Raspberry Pi Heatsink Kit Aluminum + Copper + 3M 8810 thermal conductive adhesive tape for cooling cooler Raspberry Pi 4, Raspberry Pi 3 B+:
https://www.amazon.com/dp/B07217N5LS/re ... B076ZH6X9L

When I purchase heat sinks the thermal tape is already placed on the underside of the heat sink, I actually use thermal paste instead of thermal tape which is not an adhesive, not safe for everyone, because the heatsinks can slide around, even with heatsinks you will still need ventilation if you are using a case with the RPI computer, some cases include heatsinks, fan, and power supply, here is a link to a product:

Smraza Raspberry Pi 3 B+ Case with Fan, 5V 2.5A Power Supply with ON/Off Switch, 3 Pcs Heat Sinks for Raspberry Pi 3 Model B+, Compatible with Raspberry Pi 3 Model B, Raspberry Pi 2:
https://www.amazon.com/Smraza-Raspberry ... ZEYQ4&th=1

wh7qq
Posts: 1299
Joined: Thu Oct 09, 2014 2:50 am

Re: 3M tape with heatsink

Sun Jul 07, 2019 6:40 pm

The heat-sink and tape in the Amazon reference look good and adequate but it may be unnecessary to go to the bother. First off, the RPi will throttle well in advance of any damage to chip or flesh. Subsequently the command line

Code: Select all

 vcgencmd measure_temp
will return the actual measured chip temp in degrees C. This will provide sufficient information for an informed decision rather than simple uncertainty and it may tell you to "leave well-enough, alone".

Fans are a noisy, dirty, power-hungry invasion on an otherwise blessedly silent computer. If you don't absolutely need them, don't bother. If you are a hard-core gamer, that may call for one but really, you need a bigger, faster computer.

The Smraza kit shown on the Amazon reference is attractive and attractively priced but I am very suspicious of the power supply with built in switch. Past experience with in-line switches is that the contacts add resistance which at RPi voltage and current levels, may drop the output below the threshold level and leads to erratic behavior or even shutdowns. Maybe worse, they invite switching off the RPi from the power line without a proper software shutdown that may result in SD card corruption and boot failures.
Last edited by wh7qq on Sun Jul 07, 2019 7:37 pm, edited 1 time in total.

jahboater
Posts: 4595
Joined: Wed Feb 04, 2015 6:38 pm

Re: 3M tape with heatsink

Sun Jul 07, 2019 6:57 pm

wh7qq wrote:
Sun Jul 07, 2019 6:40 pm
First off, the RPi will throttle well in advance of any damage to chip or flesh. Subsequently the command line

Code: Select all

 vcgencmd measure_temp
I suggest

Code: Select all

vcgencmd get_throttled
It shows (1) if the Pi is throttled, (2) if it has throttled since last boot, or if there are/have been other problems such as under voltage.

Moonmarch
Posts: 98
Joined: Thu Mar 07, 2019 1:34 am

Re: 3M tape with heatsink

Mon Jul 08, 2019 1:17 am

For the additional fan I personally don't use the 5V fan even though I do have a fan that is compatible with the GPIO pins, because I'm under the impression the RPI computer will not provide enough voltage to the fan, and I assume there is no fan speed control either which means the fan will be running full speed, I instead use a external powered Thermaltake fan with speed control.

If the products do not meet your expectations search Amazon for different RPI accessory kits, I see there are not enough negative reviews about the Smraza product, and I assume this product is not low quality.

Your RPI computer can increase in temperature if you are using Chromium browser for hours on a hot day, more specifically if Chromium does start to slow down and you see CPU usage at 100% frequently, yes your computer will increase in temperature, with all the cooling products that
I use the temperature can increase over 50C, and my computer idles at 35C, anyhow talking about video games not all games are multithreaded which means the computer does not use more than 25% CPU, I'm only joking around.

wh7qq
Posts: 1299
Joined: Thu Oct 09, 2014 2:50 am

Re: 3M tape with heatsink

Mon Jul 08, 2019 8:03 pm

jahboater wrote:
Sun Jul 07, 2019 6:57 pm
wh7qq wrote:
Sun Jul 07, 2019 6:40 pm
First off, the RPi will throttle well in advance of any damage to chip or flesh. Subsequently the command line

Code: Select all

 vcgencmd measure_temp
I suggest

Code: Select all

vcgencmd get_throttled
It shows (1) if the Pi is throttled, (2) if it has throttled since last boot, or if there are/have been other problems such as under voltage.
I have had a lot of trouble finding lucid explanations of the output of

Code: Select all

vcgencmd get_throttled
It outputs in hex and the meanings and results are sometimes not clear. (like what level it reports "undervoltage", etc) I avoided recommending it here for that reason.If you have a good and reliable reference for this, it would help a lot of folks if you would post it.

jahboater
Posts: 4595
Joined: Wed Feb 04, 2015 6:38 pm

Re: 3M tape with heatsink

Wed Jul 10, 2019 7:33 am

wh7qq wrote:
Mon Jul 08, 2019 8:03 pm
If you have a good and reliable reference for this, it would help a lot of folks if you would post it.
I don't I am afraid, other than this for the 3B+

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1010000000000000101  <- 19 bits  rpi 3b+
|||             |||_ under-voltage
|||             ||_ currently throttled
|||             |_ arm frequency capped
|||_ under-voltage has occurred since last reboot
||_ throttling has occurred since last reboot
|_ arm frequency capped has occurred since last reboot
But I don't care much. If the value is anything other than 0x0, then there is a problem.
I always use "official" PSU's, so the problem will likely be throttling.

The "sticky" value is useful for the Pi4 which can throttle very briefly.

I just run this script in another terminal window, whilst running the stress test or whatever.
Its pretty obvious whats happening.

Code: Select all

#!/bin/bash
vcgencmd get_config int
for src in h264 isp uart pwm emmc pixel vec hdmi dpi ; do \
  echo -e "$src:\t$(vcgencmd measure_clock $src)" ; \
done
Counter=14
DisplayHeader="Time       Temp     CPU     Core     GPU          Health          Vcore"
while true ; do
  let ++Counter
  if [ ${Counter} -eq 15 ]; then
    echo -e "${DisplayHeader}"
    Counter=0
  fi
  Health=$(perl -e "printf \"%19b\n\", $(vcgencmd get_throttled | cut -f2 -d=)")
  Temp=$(vcgencmd measure_temp | cut -f2 -d=)
  Clockspeed=$(vcgencmd measure_clock arm | awk -F"=" '{printf ("%0.0f",$2/1000000); }' )
  Corespeed=$(vcgencmd measure_clock core | awk -F"=" '{printf ("%0.0f",$2/1000000); }' )
  GPUspeed=$(vcgencmd measure_clock v3d | awk -F"=" '{printf ("%0.0f",$2/1000000); }' )
  CoreVolt=$(vcgencmd measure_volts | cut -f2 -d= | sed 's/000//')
  echo -e "$(date '+%H:%M:%S')  ${Temp}  $(printf '%4s' ${Clockspeed})MHz $(printf '%4s' ${Corespeed
  sleep 5
done
I expect my Pi's to be 0x0 all the time.

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