This is a placeholder topic for “Heat Sink Thermal Tape - 3M 8810 - 80mm x 80mm” comments.
Get that heat sink stuck on good and strong with 3M’s thermal tape. Specifically designed for attaching heat sinks to ICs. Works better and is less messy than thermal…Read more
Is thermal tape stackable i.e. How effective is this tape to equalise the hieght or IC’s of varying thickness. For instance the RPi4 CPU and power supply (SKU: CE09095) or network chip using a single heatsink. Obviously you could use individual heatsinks (SKU: CE05645) however I believe a larger heatsink over the CPU would enable sustainable heavy workloads (At present the larger heat sinks don’t cover all three chips simultaneously and could be sold with the smaller heat sink in pairs).
Thermal tape is extremely thin and is likely not the best to use stacked as there would likely be a fair few layers to make any difference in height and any air that gets trapped between the layers would act as an insulator making the thermal qualities basically negligible.
Do you know of a working alternative using different spacers or sources of material?
For instance, the CM4 heatsinks from Wave Share use two thermal strips, both different thicknesses.
Hey @Jeffrey6126 - there are likely examples that have done this in the wild but we’re not quite at the bleeding edge of highly-integrated thermal design
RE: stacking thermal tapes
Every new physical interface between materials will increase the overall thermal resistance.
Stacking conductive tapes will certainly work in theory - we just don’t know how well. I’m sure it’s super-good-enough to warrant a little experiment.
You’ll be doubling the number of thermal interfaces, and doubling the material thermal resistance - but it’s still likely to be a net improvement.
Give it a go! We haven’t tried it before but it’ll work in theory.
Your explanation is logical, and I agree that we should avoid stacking!
I did a little more research, and thermal pads comes in different thicknesses and also supplied with different conduction ratting.
I found a source that is 0.5 mm, 1.0 mm and 1.5 mm thicknesses for nvme drives etc. at 6 W/mk;
however, I have opted to experiment with a three pack that conducts 12.8 W/mk
The experiment is to achieve greater passive cooling by adding a heat sink (without fans).
I purchased 10 of your Raspberry Pi 4 Large heat sinks (SKU: CE09095), but when attempting fit them noticed a height imbalance and insufficient coverage!
My solution will be to find a suitable replacement to balance the heatsink and make it more secure/effective (see attached).
I let you know how it goes.