A multilayer graphene-based tape conducts heat quickly while insulating electricity, offering a thin and flexible solution for cooling compact electronic devices without added bulk or risk.
(Nanowerk Spotlight) Compact electronic devices generate large amounts of heat within very small spaces. As power levels rise and components move closer together, the heat produced by processors and power modules becomes difficult to remove. Excess heat shortens component life and reduces performance, yet the materials used to draw it away often face conflicting demands.
A substance that spreads heat effectively usually conducts electricity too, increasing the risk of short circuits. Insulating materials block current but slow the flow of heat. This tradeoff limits how designers manage high heat flux in mobile processors, thin laptops, and dense power electronics.
Current methods each solve part of the problem but create new ones. Graphite and graphene films conduct heat efficiently along their plane but cannot touch circuit surfaces safely because they carry charge. Metals such as copper and aluminum spread heat quickly but add weight and thickness. Polymer composites and rubbers are light and electrically safe but lose efficiency as they grow thicker.
These limits leave a clear gap for materials that can move heat laterally through layers only a few hundred micrometers thick while remaining electrically insulating.
Recent progress in composite materials has opened new directions. Graphene paper, made by stacking and compressing thin graphene sheets, conducts heat very well along its surface and remains flexible. Hexagonal boron nitride, a ceramic with a similar layered structure, combines good thermal conduction with strong electrical insulation.
Modern polymer adhesives can now form dense networks of hydrogen bonds at contact points, improving the transfer of heat vibrations known as phonons across otherwise resistive gaps. When combined, these ingredients suggest a route toward a material that can spread heat efficiently without carrying current.
That goal defines a study in Advanced Functional Materials (“Graphene Paper‐Based Multilayer Thermally Conductive Tapes with Exceptional Electrical Insulation for High Heat Flux Dissipation”). The paper describes a multilayer tape designed to manage the heat generated by compact, high-power devices. Each layer in the structure performs a distinct task. A graphene paper core carries heat laterally, adhesive layers maintain contact and strength, and an outer composite backing provides insulation and stability. Together they form a flexible, scalable material that moves heat away from processors or power chips while preventing electrical leakage.
Design of multilayer, highly thermally conductive yet electrically insulating tapes (MTCEITs). a) Schematic of the heat dissipation system of a compact electronic device with MTCEIT. b) Surface temperature distribution of tapes with different structures at steady state in the finite element simulations. Maximum equilibrium temperatures of the heat source in finite element simulations as functions of c) thickness proportion of each layer, d) 𝜅// and 𝜅⊥ of the adhesive layer, e) thermal contact resistance between the adhesive layer and the ultrahigh-𝜅// layer (Radh-ultrahigh-𝜅 //), and between the adhesive layer and the backing layer (Radh-backing). (Image: Reprinted with permission by Wiley-VCH Verlag) (click on image to enlarge)
The tape’s core is a graphene paper layer about 100 micrometers thick that serves as the main thermal pathway. Measurements show an in-plane thermal conductivity of about 578 watts per meter kelvin, roughly twice that of aluminum and hundreds of times higher than most polymers. Across its thickness, the same layer conducts only 3 watts per meter kelvin, showing that it channels heat sideways rather than through the thickness.
On each side of the graphene sits an adhesive made from a polymer called PBCOEA mixed with boron nitride nanosheets at ten percent by weight. PBCOEA, short for poly(2-butylamino carbonyl oxy ethyl acrylate), bonds firmly to both graphene and silicone layers. The nanosheets stiffen the polymer and create many contact points that distribute mechanical load. The outermost layer is a silicone rubber filled with boron nitride flakes at seventy percent by weight, forming a flexible but insulating shell that also helps conduct heat.
Interfaces often control performance more than the bulk materials. Microscopic gaps between layers can act as barriers that trap heat. Tests show that the thermal contact resistance between the adhesive and copper surfaces was only 8.9 square millimeters kelvin per watt, even without added pressure. The researchers link this to hydrogen bonding, which helps transfer phonons, the microscopic vibrations that carry heat in solids, across the interface. The polymer also fills surface roughness, increasing the true contact area and lowering resistance.
When the full tape stack was measured, its in-plane thermal conductivity reached 121 watts per meter kelvin and its through-plane value was 1.3 watts per meter kelvin at a total thickness near 300 micrometers. These numbers show that the structure maintains strong lateral heat flow while keeping electrical insulation intact. Removing the adhesive layer reduced both conductivities, confirming that it improves internal contact even though its own conductivity is modest, around 0.6 watts per meter kelvin.
Electrical performance was equally stable. Volume resistivity measured about 5 × 10¹¹ ohm centimeter at 100 volts and remained high at 1000 volts. Breakdown strength averaged 36.9 kilovolt per millimeter, meaning the material can withstand strong electric fields without failure. In the multilayer geometry, most of the field falls across the insulating outer layers, while the graphene core remains shielded.
Numerical modeling helped identify the factors that most influence heat removal. The simulations linked a three-watt heat source to a forced-air sink and compared different tape configurations. The most efficient version, containing a high-conductivity core and optimized adhesive, kept the simulated heat source near 60 degrees Celsius.
The results showed that the greatest improvements come from increasing the share of the graphene layer, improving the adhesive’s through-plane conductivity, and reducing interface resistance between layers.
Mechanical tests showed that the tape remains flexible and robust. It can bend to a radius of about 5 millimeters without damage and stretch to more than ten times its original length before breaking, depending on the graphene thickness. At 100 micrometers, the selected structure reached a tensile strength of 9 megapascals, showing that the bonding between layers holds firmly. Such flexibility allows the tape to fit curved or irregular surfaces inside devices.
The team also tested the tape in real electronic assemblies. In a thin laptop cooled by heat pipes, adding the tape over the pipes improved heat flow to the fan and chassis. The central processor stabilized at 78 degrees Celsius during load, nine degrees lower than in the unmodified system and six degrees lower than when using a commercial high-conductivity composite film. Thermal imaging showed a more uniform temperature field, meaning heat reached the fan more effectively.
A smartphone test demonstrated the same principle in a fanless system. A 285-micrometer thick piece of the tape placed under the back cover above the system-on-chip reduced peak temperature by 5.4 degrees Celsius compared with the unmodified phone. A commercial film rated at 50 watts per meter kelvin achieved only minor improvement. The cooler surface also stabilized operation. Without the tape, frame rates during 4K video playback fluctuated as the processor throttled under heat. With the tape, variation fell to less than 0.1 frame per second, keeping playback smooth and consistent.
The study outlines how to tune the structure for performance. Adding more graphene layers increases thickness but reduces total conductivity because each new interface adds resistance. Raising the boron nitride fraction in the silicone backing improves both in-plane and through-plane conduction up to about seventy percent by weight before flexibility begins to drop.
The tape remains thermally stable up to about 260 degrees Celsius, well above the operating range of most electronics. At 135 degrees, its in-plane conductivity falls to 87 watts per meter kelvin, a decrease attributed mainly to the temperature sensitivity of the graphene core and silicone composite.
Taken together, these results show how careful structural design can balance rapid heat spreading with strong electrical insulation in a single flexible material. The multilayer tape surpasses conventional insulating films of similar thickness and can be manufactured with scalable methods such as doctor blading, rolling, and hot pressing. Its ingredients, including graphene paper, boron nitride fillers, and silicone rubber, are already available through established supply chains, and the polymer adhesive can be produced using standard synthesis techniques.
This study provides a detailed example of how composite architecture can solve the opposing demands of heat management and insulation. The work suggests a path toward lighter, quieter devices that control temperature through material design rather than mechanical cooling. As electronic components grow more compact and power dense, materials of this kind may help sustain performance and reliability without adding bulk or complexity.
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