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Heat sinking compounds

zms

Apr 29, 2016
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I have been searching the net, about this thing, and i have come to know that this thing is basically a kind of filler, which is meant for eliminating invisible air gaps, and hence improving the thermal conductivity between the heat source and the heat sink.

But when i came to hear about this thing for the first time, my very first impression regarding this thing was that it was a kind of substance, which when applied on a small area on a surface of a metal plate(for example), then this thing absorbs all the heat which is conducted via that plate, and the entire heat energy is concentrated on that area over which the compound is applied.

is this true ?
 

davenn

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Sep 5, 2009
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The proper use is to apply it evenly over the whole of the area of the device that mounts against the heatsink
if it isn't applied evenly, hot spots can occur


Dave
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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evenly, but thin!

The heat sink compound is not an especially good conductor of heat. But it's way better than air. You want the most metal to metal contact with the compound filling up the remaining air gaps.
 

shrtrnd

Jan 15, 2010
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The 'thing' is called silicon heat sink compound, an example if you want to look it up is the Dow Corning 340.
It's pretty messy to work with and some people don't apply it properly.
There are several types of heat transfer pads on the market now that are cut from thin sheets to the size of each
particular semiconductor case package type. Instead of messing with the thermal heat-sink compound, you can buy pre-cut-to -size thermal heat transfer pads that are solid, flexible even-thickness for your application.
 

Minder

Apr 24, 2015
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Do not confuse it with Silicone dielectric grease, as some have done, it has the opposite effect!
M.
 

hevans1944

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Jun 21, 2012
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... it was a kind of substance, which when applied on a small area on a surface of a metal plate(for example), then this thing absorbs all the heat which is conducted via that plate, and the entire heat energy is concentrated on that area over which the compound is applied.

is this true ?
No it is NOT true. Ideally, heat-sink compound would not absorb any heat. Instead it would allow whatever heat is generated by the active device to pass freely through the thin layer of heat-sink compound into the attached heat sink, whereupon the heat is transferred to the environment. In actuality, there will be a temperature drop across the heat-sink film, but there is very little heat absorbed in the film because its heat capacity is small.
 
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