In volume production design of thermal management components, the following flow is important.

1. Clarify the factors that determine thermal performance

Organize what governs thermal performance, such as

・Contact area

・Thickness

・Compression ratio

・Air bubbles

・Position

・Burrs

・Warping

2. Translate them into important processing characteristics

If thermal performance cannot be measured on every piece, decide the dimensions, appearance and processing conditions related to thermal performance.

3. Check variation in materials and processes

Identify the factors that change in volume production, such as material lots, die wear, tension, pressure, and temperature and humidity.

4. Evaluate by deliberately varying conditions

Check whether the required performance can be maintained even under upper- and lower-limit conditions.

5. Decide a stable processing range

Set a range of conditions that can withstand variation, rather than a single optimal value.

6. Decide inspection and recording methods

Decide what to inspect 100%, what to check by sampling, and which data to keep.

7. Monitor changes

Check not only out-of-specification items, but also trends such as die wear and peeling force.

8. Re-evaluate when changes are made

When materials, equipment, conditions or factories are changed, recheck the necessary items.

Through this flow, components that cool in prototyping can be turned into components that keep cooling in volume production.

In research and development, it is easy to focus on the best results.

The highest thermal conductivity.

The lowest thermal resistance.

The lowest temperature.

Of course, these are important for showing the potential of materials and technologies.

In commercialization, however,

・Average performance

・Variation

・Worst-case conditions

・Changes over time

・Performance after environmental changes

also become important.

Rather than a component where only one of 10 prototypes cools extremely well, a component where all 10 fall within the required range is better suited to volume production.

In other words, from the research stage, it is necessary to look not only at peak performance, but also at reproducible performance.

In thermal analysis, a single value is often entered for thickness, contact area, thermal conductivity and so on.

Mass-produced products, however, have tolerances.

When thickness is at the upper limit.

When contact area is at the lower limit.

When the application position is shifted the most.

When contact pressure is the lowest.

It is necessary to consider whether the required performance can be met even when these overlap.

If performance is checked only with the design center values, some products may miss the target due to volume production variation.

In volume production design, performance must be checked not under the most convenient conditions,

but even under unfavorable conditions that can realistically occur.

Stricter inspection makes it harder for defective products to flow out to customers.

However, inspection alone does not reduce defects themselves.

What should be aimed for in volume production is to create

・Lamination methods that make it hard for air bubbles to get in

・Die management that reveals burrs before they increase

・Transport conditions in which tension is unlikely to change

・Laminated structures that are unlikely to warp

・Carrier designs that stabilize peeling force

・Reference shapes that make the application position unlikely to shift

In other words, it is necessary to evolve from a process that selects good products by inspection

to a process that can stably make good products.

Thermal performance is important.

However, making only the temperature of the finished product a quality item can make daily control difficult.

So the quality department needs to work with development, engineering and manufacturing to decide

・What governs thermal performance

・Which characteristics can be measured in volume production

・Which criteria can protect function

・How often to check

・How far back to trace in abnormal situations

Quality assurance is not producing inspection reports.

It is converting the thermal performance customers need into daily processing control.

Customers sometimes ask, “Can you process this material into this shape?”

If it is just a matter of making one prototype, it can often be processed.

To judge volume production feasibility, however, further checks are needed.

・How many pieces will be made

・Which positions are important for thermal function

・How much temperature change it will be subjected to

・Whether application is manual or automated

・Whether supply is by reel or by sheet

・How long a storage period is required

・Which items need to be guaranteed

・How far tracing is required in abnormal situations

In other words, being able to process and being able to mass-produce are different things.

From the sales and development stage, it is necessary to confirm

whether what the customer needs is a prototype or a stable volume production process.

When moving thermal management components into volume production, at least the following items need to be checked.

Materials

・Has processability been checked with multiple lots?

・Are lot differences in thickness, hardness and adhesive strength understood?

・Are there changes due to storage period?

・Are there changes due to temperature and humidity?

・Have evaluation items for material changes been decided?

Die-cutting

・Have functionally critical dimensions been clarified?

・Is burr height being controlled?

・Are trends in die wear being checked?

・Are adhesive stringing and remaining scrap being checked?

・Can edge quality be maintained after continuous processing?

・Have die replacement and cleaning criteria been set?

Lamination

・Are the acceptance criteria for air bubbles, wrinkles and foreign matter clear?

・Have prohibited areas such as directly above the heat source been set?

・Are nip pressure, speed, tension and temperature being controlled?

・Is pressure uniform across the material width?

・Can quality be maintained after long operation?

・Are trends in stacking position being checked?

Reel supply

・Is component pitch being controlled?

・Are the start of winding, the middle and the end of winding being checked?

・Have upper and lower limits for peeling force been set?

・Is the peeling state stable even after storage?

・Have the effects of winding curl and winding tightening been checked?

・Has the condition after transport been checked?

Assembly

・Has the overall tolerance of the application position been checked?

・Have compression bonding pressure and time been decided?

・Has the relationship between component thickness and amount of compression been checked?

・Has it been decided whether reapplication is allowed?

・Have warping and surface condition of mating components been considered?

・Has evaluation been done with actual volume production equipment?

Inspection

・Have the important characteristics related to thermal performance been decided?

・Have 100% inspection and sampling inspection been separated?

・Is there a method for checking defects that cannot be seen in images?

・Have measurement methods and measurement conditions been standardized?

・Are change trends being monitored, not just out-of-specification items?

・Is inspection data linked to product history?

Traceability

・Can raw material lots be traced?

・Can processing date/time and equipment be checked?

・Can the die used and its number of uses be checked?

・Can reel numbers be traced?

・Can processing conditions and inspection results be checked?

・Can the scope of impact be identified when an abnormality occurs?

What OTIS supports is not peak performance, but reproducible performance

Material manufacturers develop excellent thermal management materials.

Thermal designers decide the necessary heat paths and temperature targets.

Equipment manufacturers design cooling mechanisms.

However, to reproduce that performance repeatedly in mass-produced products, processes are needed to

・Process materials into consistent shapes

・Align stacking positions

・Suppress air bubbles and foreign matter

・Control thickness

・Control burrs and die wear

・Stabilize reel pitch and peeling force

・Record inspection results

・Find abnormal trends early

OTIS is not a company that raises thermal conductivity itself.

Nor is it a company that makes a single prototype that cools best.

What OTIS should aim for is

transferring the thermal performance a material has, stably, to each and every mass-produced piece.

Suppressing 0.1 mm of lifting.

Controlling burrs of several tens of μm.

Keeping even slight air bubbles out of critical areas.

Stacking each layer in the required position.

Supplying in the same state from the beginning to the end of the reel.

Finding changes early even as dies wear.

Through the accumulation of these, thermal performance is reproduced in volume production.

At OTIS, we may be able to contribute to stabilizing volume production of thermal management components through processing and process design such as

・High-precision die-cutting

・High-precision lamination

・Lamination of dissimilar materials

・Graphite processing

・Copper foil and aluminum foil processing

・Insulating film processing

・Foam and flexible TIM processing

・Half-cut processing

・Reel-to-reel processing

・Component supply at a constant pitch

・Shape processing that takes automated application into account

・Process design that takes air bubbles, wrinkles and foreign matter into account

・Study of dies and processing conditions that takes burrs, chipping and stringing into account

・Volume production control that takes die wear into account

・Appearance and position inspection including image inspection

・Component integration that takes customer processes into account

・Traceability of material lots and processing history

・Study of conditions for moving from prototyping to volume production

・Making prototype and evaluation components that assume volume production conditions

The value OTIS provides is not making a single piece exactly per the drawing.

It is

bringing drawings and thermal function closer to the same state, no matter how many tens of thousands of pieces.

OTIS is not a company that specializes in the following fields.

・Formulation development of thermal management materials themselves

・Design of semiconductor chips and GPUs

・Thermal design of entire products

・Dedicated CFD analysis

・Design of heat sinks and liquid cooling devices

・Guaranteeing the thermal performance of customers’ entire finished products

・Design and manufacture of automated application equipment itself

・Guaranteeing material properties in place of material manufacturers

However, by working with material manufacturers, thermal designers, equipment manufacturers and customers, we may be able to contribute in

the area of converting designed thermal performance into components that can be mass-produced through processing.

OTIS alone does not solve every heat problem.

By connecting each area of specialized technology,

we keep the performance a material has from being lost in mass-produced products.

That is OTIS’s role.

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Cooling in prototyping and continuing to cool in volume production are different things

A prototype of a thermal management material was made, and the temperature dropped.

This is a big step forward.

In moving to volume production, however, further questions are needed.

Does it cool even when material lots change?

Does it cool even when dies wear?

Does it cool even when lamination speed fluctuates?

Does it cool from the start to the end of reel winding?

Does it cool even after storage, transport and peeling?

Does it cool even when applied by automated machines?

No matter how many tens of thousands are made, do they fall within the required temperature range?

Only when this can be confirmed does it become volume production technology.

What is needed in volume production is not the single best piece.

It is a process that does not miss the required performance even under the worst conditions.

For that, it is necessary to

・Align dimensions

・Align thickness

・Suppress air bubbles

・Control burrs

・Stabilize stacking positions

・Control tension

・Stabilize peeling force

・Monitor die wear

・Link inspection criteria to function

・Make manufacturing history traceable

Thermal performance is not completed by the figures in a material manufacturer’s catalog alone.

Nor is it completed within the design drawing alone.

Nor is it completed by a prototype cooling just once.

Materials are processed,

laminated,

wound,

transported,

peeled,

applied,

and subjected to temperature changes,

and still every mass-produced product maintains the required performance.

Only when all of this holds is thermal management complete.

Material manufacturers create the potential of thermal performance.

Thermal designers think about the path along which heat flows.

Processing manufacturers build that path repeatedly into mass-produced products.

That is why what OTIS supports is not the single piece that cools best.

It is the processing process that lets every mass-produced component keep cooling in the same way.

Cooling in prototyping is the entrance to technology.

Continuing to cool in volume production is the completion of technology.

 

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.