■ What Is CNT?
CNT is short for Carbon Nanotube.
In Japanese, it is called “kābon nanochūbu” (carbon nanotube).
It is a nanomaterial in which carbon atoms are connected in a tube shape; it is extremely thin and light, and may have high thermal conductivity and electrical properties.
In the field of thermal management, applications are expected in
● High thermal conductivity materials
● Heat dissipation sheets
● Resin composites
● TIM
● Lightweight heat dissipation materials, and so on.
■ Characteristics of CNT
The characteristics of CNT are that it
● Is light
● Can be expected to have high thermal conductivity
● Has high strength
● Has electrical properties
● May be able to be composited by mixing into resin
CNT is an attractive material, especially in fields where weight reduction is important.
In AI servers, robots, aerospace, wearable devices, and so on,
the requirement to be light and release heat will increase.
In that sense, CNT is a material with a promising future.
■ Challenges of CNT
On the other hand, CNT also has challenges.
● Dispersion is difficult
● Uniformity is difficult
● It can be expensive
● There are challenges in processability
● Volume production stability is difficult
● Powder management is required
● Care is needed in applications requiring electrical insulation
What is particularly important is dispersion.
CNT does not deliver performance just by being mixed in.
It must be uniformly dispersed in the material to create paths through which heat flows.
In other words, with CNT, not only the performance of the material itself,
but also how to disperse it is important.
■ What Is Graphene?
Graphene is a material in which carbon atoms are arranged in a single-layer sheet.
It is attracting attention as an extremely thin material with high thermal conductivity and electrical properties.
In the field of thermal management, applications are expected in
● High thermal conductivity sheets
● Heat dissipation films
● Resin composites
● TIM
● Heat spreading materials, and so on.
■ Characteristics of Graphene
The characteristics of graphene are that it
● Is extremely thin
● Is light
● Can be expected to have high thermal conductivity
● Is strong at in-plane heat spreading
● Is expected to be composited with flexible materials
In smartphones, wearable devices, and thin electronic devices in particular,
materials that are thin and light and spread heat are required.
In that sense, graphene is expected to be a next-generation heat spreading material.
■ Challenges of Graphene
Graphene also has challenges.
● Large-area production is difficult
● Uniform quality is difficult
● It can be expensive
● Performance changes with the stacking state
● Compatibility with resins and adhesive materials is important
● Handling during mounting is difficult
In addition, there can be a gap between the ideal performance of single-layer graphene and its performance when used as an actual product material.
In other words, with graphene, performance in research and
performance as a volume production component must be considered separately.
■ What Is Aerogel?
Aerogel is an extremely porous material.
It contains a large amount of air inside and has extremely low thermal conductivity.
That is why it is attracting attention as a thermal insulation material.
Viewed as a thermal management material, aerogel is not a material that releases heat,
but a material that blocks heat.
Its use is expected in EVs, ESS, aerospace, construction, industrial equipment, and so on.
■ Characteristics of Aerogel
The characteristics of aerogel are that it
● Has extremely high thermal insulation
● Is light
● May be usable for thin thermal insulation
● Can be used to protect high-temperature components
● Is expected to be applied to thermal runaway countermeasures
In EVs and ESS in particular, it is attracting attention as a material that suppresses heat propagation between battery cells.
In other words, aerogel is not a material to release heat,
but a material for not spreading dangerous heat.
■ Challenges of Aerogel
On the other hand, aerogel also has challenges.
● It is brittle
● It tends to shed particles
● It is difficult to process
● It can be expensive
● Dust management is required
● Lamination and protective materials are required
● Handling in volume production processes is difficult
What is particularly important is the point that it is high-performance but difficult to handle.
Even if its thermal insulation performance is high, if it sheds particles, cracks, does not hold its shape, cannot be applied, or cannot be transported in volume production processes, adoption becomes difficult.
In other words, aerogel is a material with a large gap between material performance and mountability.
■ Next-Generation Materials Are Not Cure-All Materials
CNT, graphene, and aerogel are all attractive materials.
However, they are not cure-alls.
CNT is difficult to disperse.
Graphene is difficult to produce in large areas with uniformity.
Aerogel is brittle and tends to shed particles.
In other words, next-generation materials have amazing performance, while at the same time being materials that are difficult to master.
■ Material Performance and Product Performance Are Different
What is particularly important with next-generation materials is
the point that the performance of the material alone and its performance when incorporated into a product are different.
For example, even if it shows high thermal conductivity in the laboratory, in actual products, performance changes due to
● Thickness
● Contact state
● Adhesive layers
● Protective films
● Processing damage
● Volume production variation
● Aging degradation
In other words, with next-generation materials,
rather than research values,
stable performance after mounting is important.
■ Next-Generation Materials in AI Servers
In AI servers, GPUs, HBM, power supply components, and so on are generating more and more heat.
That is why next-generation materials are required to have
● High thermal conductivity
● Low thermal resistance
● Long-term reliability
● Compatibility with liquid cooling components
● Support for high-density mounting
CNT and graphene are expected to serve as heat spreading and high thermal conductivity materials.
However, because AI servers require continuous operation and high reliability, initial performance alone is unlikely to lead to adoption.
What matters is being usable stably over long periods.
■ Next-Generation Materials in EVs and ESS
In EVs and ESS, battery thermal management is important.
CNT and graphene are expected to serve as heat dissipation materials and composite materials.
Aerogel, on the other hand, is expected to serve as a thermal insulation material.
Especially in thermal runaway countermeasures, materials that release heat and
materials that do not spread heat must be used selectively.
In EVs and ESS, safety, flame retardancy, electrical insulation, and long-term durability are also important.
In other words, next-generation materials are questioned not only on thermal performance, but all the way to
safety
reliability
mass producibility.
■ Next-Generation Materials in Wearables and Smart Devices
In wearable devices and smart devices, it is important to be
● Thin
● Light
● Soft
● Able to conform to curved surfaces
● Close to the human body
● Usable for long periods
CNT and graphene are expected to serve as thin, lightweight heat spreading materials.
However, in products close to the human body, not only thermal performance but also safety, effects on the skin, durability, and flexibility are important.
In other words, next-generation materials for wearables need to achieve both
high performance and peace of mind close to the human body.
■ Next-Generation Materials in Aerospace
In aerospace, weight reduction is extremely important.
That is why there are great expectations for CNT, graphene, and aerogel.
There are requirements such as
● Dissipating heat lightly
● Insulating heat lightly
● Coping with extreme temperature differences
● Use in vacuum environments
● Ensuring long-term reliability
Aerogel in particular is attracting attention as a thermal insulation material.
However, because reliability requirements are extremely high in aerospace applications, not only material performance but also stability during long-term use is important.
■ The Researcher's Perspective: Next-Generation Materials Are Materials of Possibility
In research and development, there are expectations for next-generation materials such as
● High thermal conductivity
● Ultra-light weight
● Ultra-thinness
● High thermal insulation
● Flexibility
● Compositing
● Low thermal resistance
● High reliability
● Space saving
CNT, graphene, and aerogel have the potential to solve thermal challenges that were difficult with conventional materials.
However, what is important even from a researcher’s perspective is whether material performance can be converted into mounted performance.
■ The Shop-Floor Perspective: Next-Generation Materials Tend to Stall at the Wall of Volume Production
On the shop floor, challenges like the following can arise with next-generation materials.
● Cracking
● Shedding particles
● Stretching
● Warping
● Cannot be applied
● Peeling off
● Cannot run on automated machines
● Cost does not work out
● Storage conditions are difficult
● Large quality variation
In other words, next-generation materials may be attractive in the laboratory, but they are not easy on the volume production floor.
Even if the material is excellent, if it
cannot be processed
cannot be applied
cannot be transported
cannot be automated, adoption for volume production becomes difficult.
■ Problems That Tend to Occur in Volume Production of Next-Generation Materials
In volume production processes, the following kinds of problems can occur with next-generation materials.
● Cracking during die-cutting
● Particle shedding
● Edge crumbling
● Interlayer delamination
● Lamination defects
● Poor compatibility with adhesive materials
● Breakage during transport
● Deformation during winding
● Jamming during supply to automated machines
● Lot-to-lot variation
These affect not only thermal performance but also yield, ease of assembly, and quality assurance.
In other words, with next-generation materials, how to process the material and how to supply it is extremely important.
■ OTIS's Perspective
OTIS is not a company that develops CNT, graphene, or aerogel themselves.
However, we may be able to contribute in the area of making next-generation thermal management materials into a form that can be used in volume production processes.
What matters from OTIS’s perspective is
● Processing into the intended shape
● Taking particle shedding and cracking into account
● Stacking with protective films
● Laminating with adhesive materials
● Laminating with dissimilar materials
● Creating supply formats that are easy to handle in automated processes
● Suppressing variation in volume production
● Converting materials into forms that are easy to use in customers’ processes
With next-generation materials, the higher the material performance, the more difficult processing and mounting can become.
That is precisely why technology that converts material performance into volume production value is important.
■ What OTIS Can Do
At OTIS, through
● Evaluating the processing of next-generation thermal management sheet materials
● Evaluating the processing of CNT- and graphene-based sheet materials
● Evaluating the processing of aerogel-based thermal insulation materials
● High-precision die-cutting
● Microfabrication
● High-precision lamination
● Stacking with protective films
● Lamination with adhesive materials
● Lamination of dissimilar materials
● Reel supply
● Designing supply formats for automated processes
and more, we may be able to contribute to bringing next-generation thermal management materials closer to a state in which they can be used in volume production.
Especially in AI servers, EVs, ESS, wearable devices, and aerospace, not only material performance but also weight reduction, thinness, safety, and mass producibility are important.
■ Outside OTIS's Expertise
On the other hand, OTIS is not a company that specializes in
● Development of CNT materials themselves
● Development of graphene materials themselves
● Aerogel manufacturing
● Nanomaterial synthesis
● Powder design
● Resin formulation design
● Dedicated thermal simulation analysis
However, in the area of making next-generation materials into a form that can be used in volume production processes,
we may be able to play an important role.
■ Industries Where This Technology Will Be Important
★★★★★ AI servers
★★★★★ EVs and batteries
★★★★★ ESS and energy storage systems
★★★★☆ Wearable devices
★★★★☆ Aerospace
★★★★☆ Smartphones
★★★★☆ Robots
■ Summary
Next-generation materials create value only once they take a “usable form”
CNT, graphene, and aerogel have great potential as thermal management materials.
CNT and graphene have the potential for light weight, high thermal conductivity, and thinness.
Aerogel has the potential for light weight and high thermal insulation.
However, next-generation materials are not adopted just because they are high-performance.
In reality, the questions are
● Can it be processed?
● Can it be applied?
● Will it not crack?
● Will it not shed particles?
● Can it be automated?
● Does the cost work out?
● Is it stable in volume production?
In other words, the real challenge of next-generation materials is whether material performance can be converted into value that can be used in volume production.
In future thermal management, not only new materials themselves, but also the technology to process those materials into the intended shapes, thicknesses, accuracies, and supply formats and to put them into a state in which they can be incorporated into actual products will be important.
Column Supervisor: Koji Kakumoto (President, OTIS Co., Ltd.)
After studying abroad and working in planning and development at a trading company, he joined OTIS Co., Ltd. in 2011. While primarily working in the Corporate Planning Department, he has also served concurrently in manufacturing and technical divisions, and since 2018 has served as President, working to drive business growth and strengthen the organization.
This article is a general technical explanation intended for educational purposes and does not refer to any specific company, product, or technology.
