PGS Graphite Sheets:

Releases Heat from Electronic Devices Simply by Adhering to Them

Electronic devices, especially CPUs, can suffer decreased performance due to the heat that they create, hence the need for fans inside desktop computers. In the case of small mobile devices, like smartphones and tablets, all of their parts have to be packed together in a small space, exacerbating the heat problem. Not being able to release all of the heat generated by the CPU or other components can lead to discoloration of LCD screens. The solution for this problem is the PGS Graphite Sheet, developed by Panasonic.

Photo: Illustration of PGS® Graphite Sheet crystalline structure and its general view

High-temperature graphitized macromolecular film

Graphite is a native element, once known as "plumbago," and found in nature or formed as an artificial carbon. Crystalline graphite is highly thermally conductive, but in order for it to withstand the high-density packaging necessary for mobile devices, it had to be made thinner and more flexible.

Panasonic has developed a method of rearranging carbon structures to crystallize, by exposing films comprised of certain macromolecules (polyimide, etc.) to ultra-high temperatures in an inert gas environment, and then further heating the dispersed matter (known as the "precursor"). Aligning carbon atoms in extreme temperatures of 3000 degrees Celsius does require very high levels of temperature control technology, but Panasonic developed this technology as early as the 1990's.

The process of creating graphite sheets from macromolecular film

When preliminary firing (a carbonization process) is performed on macromolecular film made up of condensed macromolecules, a precursor is created. Then, main firing (a graphitization process) is conducted to promote crystalline growth.

Efficiently releases heat, blocks radio waves

Although the alignment of carbon atoms in PGS Graphite Sheets is not quite at the level of diamond, its thermal conductivity is 2-to-5 times higher than copper, which has some of the highest thermal conductivity among metals.

PGS Graphite Sheet Thermal Conductivity Chart

Graph: Thermal conductivity of various substances (a-b plane)  Diamonds have the highest thermal conductivity of approximately 2,000. PGS10 micrometer boasts a thermal conductivity of about 1,900 to rival that of the diamond. The thermal conductivity decreases as the film thickness increases from PGS10 micrometer to PGS17 micrometer, to PGS25 micrometer, to PGS40 micrometer, to PGS50 micrometer, to PGS70 micrometer and to PGS100 micrometer (approximately 700 for PGS100 micrometer). The thermal conductivity of pure copper is less than 400 and that of aluminum is less than 200. It gets smaller toward zero in the order of magnesium alloy, stainless steel and heat-conduction sheets. The thermal conductivity of PGS® Graphite Sheets in the in-plane direction is about 2 to 5 times that of copper. The material of PGS® Graphite Sheets has very high thermal conductivity.

Due to its layered crystalline structure, there is a high level of heat conduction in one direction of its layers (transmission on the same layer), while at the same time, transmitting against the layer (transmission between layers above or below) displays a low level of thermal conductivity, of about only 1/100th, making it extremely useful for conducting heat in a specified direction. In addition to its heat conducting properties, it also functions as an electromagnetic shield, making it possible to mitigate the problem of electromagnetic waves at the same time as releasing heat.

So flexible, light and thin, it can be folded into an origami crane

PGS Graphite Sheets can be created with thicknesses between 10 and 100μm. They are so thin, it would take a stack of 76 of them to equal the thickness of a standard credit card (0.76mm). They have a specific gravity of 1-2g/cm3, a level slightly higher than that of water, and much lighter than copper's specific gravity of 8.82g/cm3.

Even though it is so thin and light, it would be difficult to process if it were fragile when bent, but PGS Graphite Sheets are so flexible that a square sheet can be folded into an origami crane. Furthermore, bending resistance tests which fold, open, and repeat, reveal that it has a high level of flex resistance, to 30,000 folds.

Use in a Cellular Phone (Heat distribution before and after implementation)

It reduces heat spots on the surface of a smartphone. The PGS® Graphite Sheet is used near the battery, RF chip, PA and LCD. The result of the analysis of heat maps of smartphone surfaces with and without PGS shows a heat spot reduction effect of the PGS® Graphite Sheet.

Thin, light, pliable, and even highly thermally-conductive in specified directions and protective against electromagnetic waves, PGS Graphite Sheets are utilized in a wide array of machinery, including smartphones, cell phones, digital cameras, computers, and semiconductor manufacturing equipment, in order to efficiently release heat produced out of sight.

In addition, because PGS Graphite Sheets are made of carbon, there is extremely little impact on the environment (RoHS compliant), making them a material which is good for the planet.

The latest information

Panasonic's PGS Graphite Sheets are continuing to make progress. In addition to furthering engagement with the ICT field of smartphones and tablets, Panasonic is also developing new applications of anti-heat solutions in the automotive and industrial fields.

Releases heat just by adhering! Panasonic's PGS Graphite Sheets