Thermal Grease

[W. Kranitz]

Let me expand Garey's comment a little.

The "old" style clear silicone grease is called "Type Z5"
Silicone Compound. It really is a dielectric grease that is
used to seal and waterproof connections. It worked reasonable
well as a heat transfer medium and so was used as a heat sink
compound on old style transistor amplifiers.

The "new" style white silicon grease is called "Type Z9"
Silicon Heat Sink Compound. Some special application versions
of this compound used beryllium oxide, but these were not available
to us mear mortals. Most common versions use aluminum or zinc
compounds. Some of the newer types use Micronized Silver (eg, DYNEX
Silver Thermal Compound). These are used for the high heat transfer
needed for modern microprocessors.

I hoped that helped a little.

Wes
WA4AME


Garey Barrell wrote:

> Jerry -
>
> There are at least two types that I am aware of.
>
> The "old" style was clear silicone grease.
>
> The "new" style is white silicone grease loaded with beryllium oxide.
>
> Both work pretty much the same, the purpose being to fill any  TINY  air
> pockets trapped between what ideally would be two "perfectly" flat
> surfaces.  The idea is that the grease is a better at heat transfer than
> air.  It is NOT a better conductor than metal, so a big blob of grease
> isn't going to transfer much heat between two surfaces that don't touch.!
>
> Proper use calls for only a VERY thin smear.  Most people use WAY too
> much, which of course gets squeezed out when the two pieces are clamped
> together.
>
> By the way, beryllium oxide DUST is considered very toxic if inhaled, so
> I guess you wouldn't want to eat the stuff!
>
> 73, Garey - K4OAH
> Atlanta
>
>
> Jerry Seligman wrote:
>
>> A question came up in discussions with friends. Is the thermal grease
>> used on power transistors, the same as the type used in computers
>> (for example on the CPU chip)?
>> Jerry W7BUN
>>
>
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