Sunday, November 21, 2010

What do we do with graphite sheet?

Considering the heat dissipation and thermal resistance of electrical devices is critical issues for engineers.
The newspaper and magazine articles regarding to heat dissipation for electrical devices are very common these days.

Therefore, it is very easy to imagine the race for developing a better heat dissipation material is getting severe.

Although there are many materials with high thermal conductivity, graphite sheet is one of the most popular heat dissipation material in industry.

A graphite sheet is thin, flexible, easy to deform and especially has high thermal conductivity in "in-plane" orientation.
It has thermal conductivity of 5 times as large as silver.

It looks like a gray or black sheet of paper.
You can make ORIGAMI with it!

As you can imagine, graphite sheet is made mostly out of graphite.
Please imagine large sheets of crystals are piling up.
This is the reason why graphite sheet has such a HIGH thermal conductivity for in-plane orientation and LOW for out-of-plane orientation.

In industries, graphite sheets are well used for decreasing the heat concentration for laptop pc and fix the temperature ununiformity for LCD.

With Thermowave Analyzer alone,we could measure both orientation with one single sample.

For example, the difference in thermal conductivities for graphite sheet in different orientations are distinctively different,

In-plane: about 1,000 W/mK
Out-of-plane: about 5W/mK

The values are different by 2 digits!

In-plane thermal conductivity is as high as diamonds.
In another hand, out-of-plane thermal conductivity is as low as ceramics.

Thermal conductivities are calculated from thermal diffusivity measured by TA and heat capacity and density from literature.

If you are interested in testing service or just want to know about TA, please feel free to contact us.


Maryam said...

you are so right
thermal conductivity
high pressure
thermal conductivity

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