Silver Paint for Enhanced Cooling

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An intriguing idea to enhance IC device cooling – Arthur Tang.

Ed note: I have not had time to try this, but thought it intriguing enough to post it. The author has a degree in Mechanical Engineering, including 3rd year heat transfer from MIT, and has a number of letter patents. Drop us a line if you try this.

Cooling technology is most effective by radiation cooling. To use this technology, one has to be aware of infrared radiation wavelength, emissivity of surface, radiation source and size, as well as the distance to the radiation sink. The fact that the radiation source and sink is a cooling system goes from internal devices to the surface of the computer case, you also have to look at the room as a radiation sink.

Having said that, we can look at all the thermal problems in a modern computer. The case houses the CPU, video device, memory and harddrive, all of which can be a problem for overclockers. These devices all work best in a limited temperature range. ie., CPU being a CMOS device which can only be operating correctly when internal noise is the lowest.

Noise is generated by residue stress between the gate and silicon, and noise due to high temperatures. Stress is due to difference in coefficient of thermal expansion. CMOS transistors can only be used up to 85 C. CPUs are rated up to 60 C or 70 C.

So how do we use radiation to emit heat? By treating the surface of hot devices.

Device cooling can be improved by silver paint.

Silver paint is made with a minute aluminum powder. The temperature (infrared wavelength) of aluminum powder will emit heat more efficiently because of the size of surface area of the spherical powder into 360 degrees of space.

To illustrate, a 1 watt black plastic rectifier, if painted silver, will operate as a 3 watt rectifier. The new silver thermal grease is an application of better radiation and better conduction. Coating the ceramic cases of CPUs (top and bottom) can also help to reduce heat locally. You can use model airplane silver dope, or silver high temperature paint.

Painting as described is done every day by myself on ICs and on computer chips, such as the Cyrix MII PR300. The difference is whether they work at all.

NOTE: Silver paint may be electrically conductive – if you do this, avoid painting electrical contacts, such as the CPU’s pins!

Arthur Tang

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