Thermal grease and heat sinks

beenthere

Joined Apr 20, 2004
15,808
Transistor grease is used to maximize thermal transfer to a heat sink. It is a silicone grease mixed with titanium dioxide. It is very white and sticky. Some always gets on your tools and fingers, and then all over your clothes and work area.

The joke is that if someone spills a pound of the stuff, everybody on earth will be leaving white footprints in about three days.
 

Thread Starter

Papabravo

Joined Feb 24, 2006
12,301
Transistor grease is used to maximize thermal transfer to a heat sink. It is a silicone grease mixed with titanium dioxide. It is very white and sticky. Some always gets on your tools and fingers, and then all over your clothes and work area.

The joke is that if someone spills a pound of the stuff, everybody on earth will be leaving white footprints in about three days.
Yup! That's the good stuff all right. For a cleaner alternative check out Sil-pads. You can get a sheet of the stuff and cut the holes with brass tube from a hobby shop.
 

hgmjr

Joined Jan 28, 2005
9,029
For a look at the Sil-pad material that papabravo was referring to follow this link. This particular one happen to be precut for a TO-220.

Nice stuff.

hgmjr
 

Dave

Joined Nov 17, 2003
6,960
D'you know, I've been looking all over the UK for that stuff for the graphics chip heat sink on my laptop, without any success. Anyway someone stole my laptop and I no longer need it - now I find what I need!

Dave
 

beenthere

Joined Apr 20, 2004
15,808
Be careful to read spec's on thermal pads - I still have some pads that conduct heat and electricity. Makes it hard to isolate the heat sink.

There is a cute tendancy now to use a conductive glue on processor sinks. You do a bit of damage getting the processor off the socket, as the sink prevents you from undoing the zif socket latch. The good news is that when a couple of pins pull off, you no longer have doubts about the state of the processor.
 

recca02

Joined Apr 2, 2007
1,211
thanks.
say this really went off topic why not create a new thread out of the heat sink replies
i,m sure some1 will find it useful ;)
 
I call the white heatsink compound "BirdShit"...it gets all over everything.

I now use a clear silicone compound.........I will get the name of it and post it tomorrow.
 

Gadget

Joined Jan 10, 2006
613
I used to use a clear silicon grease compound, but found it didnt have as good Heat transfer as the white gunk.
Its not too messy as long as you dont over do it.... remember, when it comes to heat transfer paste, LESS is more.
 

beenthere

Joined Apr 20, 2004
15,808
That's why you give a good honk on the mounting hardware to force out the excess, and make a wonderful mess.

I have also got fond memories of the old mica insulating pads which were so much fun to work with. They needed the grease on both sides. With TO-3 transistors, the technique was to hold the transistor and butter up the case, trying to avoid getting it on the base and emitter leads. Then the mica went on the applied greas, and got buttered with more grease, again trying to keep it off the leads. By then you had four fingers and a small screwdriver nicely smeared with the grease.

On a related note - anyone ever have the fun of using beryllium oxide pads? These were pretty thick, about 1/16 inch. They were to be used for applications where the voltage on the transistor case was too great for a mica insulator. They were also unbelieveably brittle. You could break one by running a fastener down too hard on one side of the transistor case.

But, a bit of transistor grease would hold the broken ear in place so the BO pad could still be used.
 
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