What materials offer the best thermal conductivity for electronics cooling?

I would like to start with graphite and graphene, we can always start with copper, aluminum and silver but here why I chose the future materials in graphite and graphene is because they offer excellent thermal conductivity and is still in research stage; where many possibilities are expected.

Metals are preferred for thermal management in electronics due to their excellent thermal conductivity. Copper (Cu): With a thermal conductivity of ~400 W/mK, copper is ideal for heat sinks and cooling solutions. However, it is heavy (Density = 8.94 g/cm3) and expensive. Aluminum (Al): Although it has a lower thermal conductivity (~235 W/mK) than copper, aluminum is significantly lighter (Density = 2.7 g/cm3) and more cost-effective, making it suitable for applications where weight and cost are critical. However, it is less effective in heat dissipation. Advanced Materials: Graphene-enhanced aluminum composites can improve thermal conductivity without adding weight.

I can recommend using metal nanowires to combine materials, e.g. in the semiconductor industry like LED fabrication. This will create a metal-metal interconnection with highest conductivity (electric and thermal). Just have a look at nanowired.de for more information.

Copper and aluminum AND plain water for maximum joule storage (either for ... plain storage or for transportation of those excess joules)

Metals are commonly used in electronics to keep them cool because they're really good at moving heat. Copper is especially good at this, as it can quickly carry heat away from hot spots. This is why it's often used in heat sinks, which help cool down things like computer processors. Aluminum is another metal that's used for cooling, even though it's not as good at conducting heat as copper. However, aluminum is lighter and cheaper, which makes it a popular choice for many applications where weight and cost are important factors. Both metals help keep electronic devices running smoothly by spreading heat away from the components, which helps maintain a stable temperature.

surely The undisputed champion of thermal conductivity, with a rating of around 2000 W/m·K. However, its high cost and difficulty of machining make it impractical for most electronics applications.

At normal temperature, diamond has the highest thermal conductivity of any known material. However, its extensive use in electronics cooling applications is limited by its high cost and processing complexity. In high-performance heat management applications where cost is less of an issue, synthetic diamond materials are occasionally utilized.

Diamond stands out as a remarkable material for thermal conductivity, surpassing even metals like copper and aluminum. Synthetic diamond materials, engineered specifically for thermal management, exhibit unparalleled thermal conductivity. Despite being costly, diamond's exceptional heat-conducting ability makes it perfect for high-performance electronics where thermal efficiency is crucial. However, its usage is typically limited to specialized applications where performance outweighs cost concerns.

For the highest thermal conductivity, diamond stands unmatched. Synthetic diamond materials, engineered for thermal management, outperform metals like copper and aluminum. Despite their cost, diamonds' exceptional heat conduction makes them ideal for high-performance electronics where thermal efficiency is crucial. Consequently, their use is typically limited to specialized applications where performance takes precedence over cost.

Graphene's exceptional thermal conductivity, exceeding 5000 W/mK, offers significant benefits for electronics cooling: Thermal Interface Materials (TIMs): Graphene enhances TIMs by filling microscopic air gaps, improving thermal contact and heat transfer. Swedish start-up Tenutec uses graphene-based TIMs to address electronics overheating. Heat Spreaders: Apple is considering replacing copper heat sinks with graphene in future iPhone models for better cooling. Flexible Electronics: Graphene’s flexibility and thermal properties are ideal for flexible electronics. Huawei's P30 series uses graphene for heat dissipation. Graphene Composites: Graphene enhances the thermal conductivity of polymer, useful for advanced heat sinks.

Graphene, composed of a single layer of carbon atoms in a hexagonal pattern, is renowned for its exceptional thermal conductivity. Its unique two-dimensional structure gives it extraordinary properties, including superior heat conduction capabilities. Researchers are investigating the use of graphene sheets in electronic devices where space is limited and effective heat dissipation is critical. Although still in the experimental stage, graphene shows potential for transforming electronics cooling with its blend of high conductivity and material strength.

Graphene, a single layer of carbon atoms in a hexagonal lattice, is a standout in thermal conductivity. Its unique two-dimensional structure enables superior heat conduction, making it ideal for electronic devices where space and efficient heat dissipation are critical. Although still under research, graphene sheets hold great potential for revolutionizing electronics cooling due to their exceptional conductivity and material strength.

A good example of a CMC material used in the nuclear and aerospace industries are SiC/SiC. These composites are made using high strength silicon carbon fiber and densified using numerous methods to create a matrix. These methods include: 1) Slurry or pre-ceramic polymers infiltration and pyrolysis (PIP) 2) Melt infiltration using silicon based alloys 3) Chemical Vapor Infiltration (CVI) Prior to matrix densification the SiC fibers are coated with a very thin interface coating. This coating provides multiple functions including environmental/oxidation protection of the fibers. The interface coating is key to creating a non-brittle composite as the coating deflects cracks around the fibers and provides “pull-out” or sliding.

Ceramic Matrix Composites (CMCs) are widely used in automobile, aircraft components, and electronics due to their high hardness, thermal stability, and electrical insulation. However, they suffer from poor thermal conductivity and brittleness. Incorporating graphene into ceramics like Silicon Carbide (SiC), Alumina (Al2O3), and Tantalum Carbide (TaC) can enhance thermal conductivity, fracture toughness, and even tunable electrical properties. Graphene's high thermal and electrical conductivity, combined with its strength, improves heat transfer and resists microcrack formation, thus enhancing the overall thermal/mechanical properties of the ceramic composite. This is essential for effective heat dissipation in high-temperature applications.

Ceramic materials can be used as auxiliary elements in heat dissipation in applications where the operating temperature is too high to use metals as dissipating elements. Despite their lower thermal conductivity compared to metals, ceramics can withstand aggressive chemical environments, which may limit the application of metallic systems.

Ceramic composites, while not typically known for heat conduction, can offer significant thermal conductivity. These materials are particularly valuable in electronics where electrical insulation is needed, as ceramics are usually electrically non-conductive. By integrating conductive materials, ceramic composites can effectively manage heat while ensuring electrical isolation, making them suitable for specialized applications in advanced electronics.

High thermal conductivity ceramics, such aluminum nitride (AlN) and beryllium oxide (BeO), are employed in specific electronic applications where thermal management and electrical insulation are crucial.

Phase Change Materials (PCMs) like Paraffin Wax absorb and release large amounts of thermal energy during phase changes, making them ideal for thermal management in Li-ion battery packs. While conventional PCMs have low thermal conductivity (0.17 – 0.35 W/mK), graphene-enhanced hybrid PCMs exhibit thermal conductivity two orders of magnitude higher, maintaining PCM's latent heat storage ability. This allows one to reduce the temperature rise inside the battery. For example, this hybrid graphene PCM significantly reduces temperature rise inside battery packs, from ~37°C (without PCM) to ~10°C during charge-discharge cycles. [Ref. Goli, Pradyumna, et al. Journal of Power Sources 248 (2014): 37-43.]

Phase change materials (PCMs) are substances that can absorb and release large amounts of heat as they change from one phase to another, such as from solid to liquid and vice versa. This property makes them valuable in regulating temperature fluctuations in electronics. PCMs can help stabilize the operating temperature of devices by absorbing excess heat when temperatures rise and releasing it when temperatures fall, effectively acting as a thermal buffer.

Phase change materials (PCMs) are highly effective for thermal management in electronics due to their ability to store and release large amounts of heat during phase transitions. These materials change state, for example from solid to liquid, when absorbing heat, which helps in stabilizing temperatures. As they revert to their original state, they release the stored heat. This cyclical process makes PCMs ideal for applications where precise temperature control is critical, providing a reliable solution for thermal buffering and improving the efficiency and lifespan of electronic devices.

Certain liquid metals, including alloys based on gallium, have a high heat conductivity and can be helpful in situations where conformal cooling is necessary, like the cooling of electronic components with uneven shapes.

Graphene, known for its unparalleled thermal conductivity, is ideal for applications requiring lightweight and durable materials. However, large-scale production has been a challenge. Nevertheless, companies like Levidian Nanosystems have revolutionized this by producing high-quality, cost-effective graphene from methane, making it scalable. Their LOOP100 system can produce 14.25 tonnes of graphene from 75 tonnes of methane. Improved manufacturing has expanded graphene's potential. In electric vehicle battery systems, it enhances cooling and efficiency, leading to longer-lasting batteries. Its electrical and thermal conductivity also make it ideal for optoelectronic devices, improving heat management.

It's crucial to take into account aspects like thermal conductivity, price, weight, mechanical qualities, and compatibility with other materials in the system when choosing a material for electronics cooling. In order to meet other design requirements and maximize thermal performance, a combination of materials is frequently used.