■ Heat Moves in Three Ways
There are broadly three ways in which heat moves.
They are
1.Thermal conduction
2.Convection
3.Radiation
Heat problems in future industries basically consist of combinations of these three.
① Thermal Conduction: Heat Transfers by Touch
The first is thermal conduction.
This is the phenomenon in which heat moves through an object.
For example,
● Touching a hot pot
● Heat transferring from a CPU to a heat sink
● Metal getting hot
In other words, thermal conduction is heat flowing because things are in contact.
■ Metals Conduct Heat Easily
In general, metals such as
● Copper
● Aluminum
conduct heat easily.
Conversely,
● Air
● Resin
● Foam materials
conduct heat poorly.
In other words, in thermal management, what to put in contact is extremely important.
■ Why Are Air Layers So Dangerous?
What matters here is air.
In fact, air conducts heat very poorly.
In other words, even a slight air layer formed by
● Lifting
● Steps
● Poor contact
can greatly worsen thermal performance.
■ The Problem of the Final 0.1mm of Heat
In future industries,
● Miniaturization
● Higher density
● Stacking
will advance.
As a result, the importance of contact rises sharply.
For example, even just
● Lifting of a few tens of μm
● Tiny steps
● Uneven pressure
can greatly change thermal performance.
In other words, in the future, the final 0.1mm of heat will be extremely important.
② Convection: Air and Liquids Carry Heat
Next is convection.
This is the phenomenon in which a fluid carries heat.
For example,
● Cooling with fans
● Air conditioners
● Water cooling
● Liquid cooling
In other words, the air or liquid itself moves while holding heat.
■ In the AI Era, Liquid Cooling Is Spreading
In AI data centers, the amount of heat generated is increasing rapidly.
As a result, air cooling alone is starting to reach its limits.
That is why liquid cooling technologies are now advancing rapidly, such as
● Water cooling
● Cold plates
● Immersion cooling
The reason is simple: liquids carry heat more easily than air.
■ Robots and EVs Are Also Fighting Convection
In EVs and robots, too, convective cooling is used for
● Battery cooling
● Motor cooling
● AI chip cooling
In the future, however,
● Miniaturization
● Quieter operation
● Weight reduction
will also be required.
In other words, wanting to cool and wanting to make it smaller collide.
③ Radiation: Heat Transfers Even at a Distance
The last is radiation.
This is the phenomenon in which heat flies as infrared radiation.
For example,
● The heat of the sun
● The heat of a bonfire
● Heat dissipation in outer space
In other words, radiation is a phenomenon in which “heat moves even without contact.”
■ In Space, Radiation Takes the Lead
On Earth, because there is
● Air
● Water
thermal conduction and convection are strong.
But space is a vacuum.
In other words, there is no air.
As a result, heat can hardly be released except by radiation.
That is why radiation design is extremely important for space equipment.
■ Real Thermal Management Involves All of Them at Once
What matters here is that real heat problems involve neither thermal conduction alone nor convection alone.
For example, in a CPU,
CPU
↓ (thermal conduction)
TIM
↓ (thermal conduction)
Heat sink
↓ (convection)
Air: multiple mechanisms are combined in this way.
■ Thermal Management Is Designing Escape Routes for Heat
In other words, thermal management is not eliminating heat
but creating escape routes for heat.
This is the essence.
■ Why Is Contact Important?
At this point, it becomes clear why, on the shop floor,
● Lifting
● Steps
● Pressure
● Contact area
are so important.
Heat does not flow according to theoretical performance alone.
In reality, it changes greatly depending on how things are in contact.
■ The Researcher's Perspective: How to Optimize Heat Transfer
In research and development, people consider
● Thermal conductivity
● Thermal resistance
● Heat dissipation structures
● Convection efficiency
● Emissivity
In other words, thermal design is also heat flow design.
■ The Shop-Floor Perspective
Heat does not flow as theory predicts
On the actual shop floor, heat transfer changes greatly due to
● Poor contact
● Air layers
● Uneven pressure
● Tiny misalignment
● Material deformation
In other words, good materials alone do not make a good thermal design.
■ Heat Problems Are Decided by the Process
For example, thermal performance also changes with
● Lamination
● Pressure
● Steps
● Processing accuracy
● Automation stability
In other words, thermal management is determined not only by material performance,
but by making the process work.
■ What Matters from OTIS's Perspective
From OTIS’s perspective, what matters in heat problems includes
● Microfabrication
● Contact stability
● High-precision lamination
● Thin-film processing
● Contact between dissimilar materials
● Volume production stability
In other words, OTIS is committed to making a state in which heat flows work in volume production.
■ What OTIS Can Do
At OTIS, through
● Microfabrication
● High-precision die-cutting
● High-precision lamination
● Processing of thermal management materials
● Stacking of irregular shapes
● Support for automated supply
we may be able to contribute to the contact conditions that make heat flow work.
■ Outside OTIS's Expertise
On the other hand, OTIS is not a company that specializes in
● Dedicated CFD analysis
● Heat-generating device design
● Cooling equipment design
● Power generation system design
However, in the area of making heat solutions work in volume production processes, we may be able to play an important role.
■ Summary
Thermal management is the design of escape routes for heat
Heat moves in three ways:
1.Thermal conduction
2.Convection
3.Radiation
And in real heat problems, these intertwine in complex ways.
In other words, thermal management is not eliminating heat,
but designing where and how to release heat.
And in future industries, the final contact conditions for heat will become increasingly 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.
