Can we stack gap pads?

[cupoftea]

Hi,
We want a 5mm thick piece of gap pad. so can we stack the following 2mm and 3mm pieces on top of each other?
The gap pad will be 70mm x 30mm

Farnell 3267478
MPGCS-020-150-3.0AA 150x150x3mm £26

https://uk.farnell.com/multicomp-pro/mpgcs-020-150-3-0aa/thermal-pad-silicone-150x3mm-blue/dp/3267478?ost=mpgcs-020-150-3.0aa

Farnell 3267476
MPGCS-020-150-2.0AA 150x150x3mm £19

https://uk.farnell.com/multicomp-pro/mpgcs-020-150-2-0aa/thermal-pad-silicone-150x2mm-blue/dp/3267476?ost=mpgcs-020-150-2.0aa

 

[FvM]

2 W/mk is at the lower edge of available gap pad conductivity. A 5x5x5 mm cube would e.g. have a thermal resistance of 100 K/W

see an example what's available on the market https://amecthermasol.co.uk/product/?cat=thermally-conductive-materials&family=thermal-pads-

 

[cupoftea]

Hi,
We have purchased Gap pad Farnell 3267483 (3mm thick) and 3267482 (2mm thick)
(They are both 3W/m.K)

Farnell 3267483 gap pad
https://uk.farnell.com/multicomp-pro/mpgcs-030-150-3-0a/thermal-pad-silicone-150x3mm-blue/dp/3267483
Farnell 3267482 gap pad
https://uk.farnell.com/multicomp-pr...-silicone-150x2mm-blue/dp/3267482?ost=3267482

We need 5mm Gap pad and 70 x 30mm.
Though this gap pad comes on a brown piece of paper and it is severely difficult to get it off this brown paper backing.

There is actually a microscopically thin film layer of glue on the back of the gap pad….but this actually sticks to the brown paper backing, and when you try to remove the brown paper

You also remove the “glue film”…or rather, you don’t completely remove it, but when removing the brown paper you end up with the glue film getting ripped and creased up and lying over the gap pad,

Which is obviously not wanted.

...its also squishy and deforms too easily. Also I put the 70x30x5mm piece on the ESD mat and it got stuck to it and I had to get it off with a blade…but I then left a "gap pad stain" on the ESD mat.

 

[FvM]

Gap pad must be pressed between component and heatsink, in so far glue layer is primarily an assembly tool.

--- Updated Jan 8, 2024 ---

...its also squishy and deforms too easily. Also I put the 70x30x5mm piece on the ESD mat and it got stuck to it and I had to get it off with a blade…but I then left a "gap pad stain" on the ESD mat.

Yeah, need some practice.

 

[cupoftea]

I must admit its severely difficult to get the brown paper off without creasing up the gap pad surface. You have to use a blade to start it off..but even then its really difficult.

 

[FvM]

Guess Farnell doesn't sell much if this, maybe it's beyond expiration date.