When a component’s outer shape has sharp corners, stress tends to concentrate during peeling and temperature changes.

From sharp corners,

・Peeling of the adhesive layer may start

・Thin films may tear

・Graphite may chip

・Interlayer delamination may progress

By giving corners an appropriate radius, it may be possible to

・Distribute stress

・Stabilize peeling

・Make scrap removal easier

・Reduce snagging during transport

However, making the radius too large affects the necessary heat source coverage area and insulation distance.

Therefore, corner shapes must also be decided from the standpoint of both thermal performance and process stability.

In reel supply, components are lined up at fixed intervals.

This interval is managed as the pitch.

Automated machines pick up the next component based on the set feed amount.

If the pitch varies, the suction position of the automated machine and the actual component position no longer match.

Causes of pitch variation include

・Stretching of the carrier film

・Changes in transport tension

・Dimensional changes due to temperature and humidity

・Meandering during processing

・Die feed error

・Deformation during winding

Even if outer dimensions are correct, if the arrangement on the reel is off, it cannot be used stably on automated machines.

In reel supply, both

dimensional accuracy of individual products and positional accuracy as a continuous strip are necessary.

In reel supply, it is necessary to clarify

・The top and bottom of the component

・The orientation of the adhesive surface

・The peeling direction

・The winding direction

・The orientation of holes and cutouts

・The front and back of the component

Especially with graphite and rolled metal foil, the material direction may relate to mechanical properties and how heat spreads.

Even if the outer shape of the component is the same, placing it in a different orientation may change

・Ease of peeling

・Ease of bending

・Susceptibility to cracking

・The direction in which heat spreads

Therefore, in supply specifications, not only quantity and reel width, but also

material direction and functional direction must be clarified.

When a person applies components, they press down a slightly warped one.

If it is hard to peel, they change the angle.

If the component position is off, they check visually and correct it.

Automated machines repeat the same operation under set conditions.

That is why, even if one component can be handled by an automated machine, it does not necessarily mean it can be mass-produced.

What is needed is that

・Warping

・Peeling force

・Pitch

・Thickness

・Position

・Suction pickup

・Surface condition

are all within a fixed allowable range.

A component suited to automation is not a component that moved correctly just once.

It is a component that moves the same way even across thousands or tens of thousands of pieces.

With thin components or components that are sticky, automated machines sometimes pick up two at the same time.

If two overlap,

・Thickness increases

・The amount of compression changes

・Contact pressure changes

・Thermal resistance increases

・It interferes with surrounding components

may result.

In other words, double picking is not just a supply error.

It is a functional defect in which the very laminated configuration of the thermal management component changes.

Possible countermeasures include

・Layout design on the carrier

・Stabilizing peeling force

・Monitoring vacuum pressure

・Thickness inspection

・Image inspection

・Static electricity countermeasures

Thin films and light components can become charged during peeling.

Static electricity may cause the component to

Reattach to the carrier

Stick to the nozzle

Overlap with another piece

Change posture partway through transport

Attract dust and particles

Thermal management components can also generate conductive foreign matter, such as graphite particles and metal particles.

If these adhere to insulating parts, it leads not only to heat problems but also to electrical problems.

Therefore, in automated supply,

・Static elimination

・Grounding

・Humidity control

・Peeling speed

・Transport route

・Collection of foreign matter

must also be included in process design.

To stabilize automation, shapes that do not remain in the finished product are sometimes provided temporarily.

For example,

・Suction tabs

・Margins for starting peeling

・Position recognition marks

・Connecting parts for transport

・Support frames

・Bridges for scrap removal, and so on.

Looking only at the finished product drawing, these seem wasteful.

However, having those shapes makes it possible to

・Suppress deformation during peeling

・Secure a suction surface

・Stabilize transport posture

・Make position recognition easier

・Protect narrow shapes

In other words, mass-produced components need both shapes that realize product functions and

shapes that make the process work.

When thermally conductive materials, insulating materials, adhesive materials, and so on are applied separately, each requires

・Peeling

・Suction pickup

・Positioning

・Application

・Inspection

The more components there are, the more opportunities there are for positional misalignment and foreign matter contamination.

So if multiple materials can be laminated with high precision in advance and supplied as an integrated component, it may lead to

・Fewer applications

・Shorter takt time

・Stable positional accuracy between components

・Fewer parts to manage

・Fewer opportunities for foreign matter contamination during application

This is a major value that processing manufacturers can provide to customers’ processes.

On the other hand, consolidating too many functions into a single component may make it

・Larger

・Thicker

・Harder

・More prone to warping

・Harder to peel

・Harder to pick up by suction

・Entirely defective if one layer is defective

For example, if heat dissipation material, insulating material, EMI material, and sealing material are all integrated, the customer’s application processes decrease.

However, the laminated configuration becomes complex, and managing differences in thermal expansion and positional accuracy becomes difficult.

What matters is not minimizing the number of components.

It is choosing the configuration that can be mass-produced most stably, including the customer’s process.

In AI servers, GPUs, HBM, power supply components, optical communication components, and so on are arranged at high density.

Around them,

・TIM

・Graphite

・Copper foil

・Insulating film

・EMI material

・Adhesive material, and so on are used.

Warping or positional misalignment of components may cause

・Inability to sufficiently cover the heat source

・Uneven contact pressure

・Exposure of conductive material from the insulating layer

・Shifts in the automatic application position

In addition, server heat generation changes with operating state.

Laminated components must maintain the same position and contact state even through repeated temperature changes.

In thermal management components for AI servers, not only high thermal performance, but also maintaining a shape that can be automated even after temperature changes is important.

In advanced semiconductors and 3D packaging, heat sources and components are small, and positional accuracy is also strict.

Even if a component’s dimensional change is only tens of μm, its position relative to the heat source may change.

In addition, forcibly pressing a warped component can apply local stress to thin chips and joints.

That is why

・Differences in thermal expansion

・Warping after lamination

・Automatic application position

・Compression bonding pressure

・Changes after temperature cycling

must be evaluated together.

In EVs and next-generation batteries, large-area heat dissipation materials, insulating materials, and cushioning materials are used between cells, modules, and cooling plates.

The larger the component, the larger the absolute amount of dimensional change due to temperature changes.

Furthermore, in the automotive environment, large temperature changes are repeated, such as

・Low temperatures in winter

・High temperatures in summer

・Heat generation during fast charging

・Driving and stopping

・Temperature differences between day and night

Differences in thermal expansion of laminated materials may cause

・Edges to lift

・Layers to delaminate

・Contact pressure to change

・Sealing performance to decline

・Temperature differences between cells

In components for EVs, not only initial flatness, but also

keeping a large area in a uniform contact state over a long period is important.

In smartphones and wearable devices, graphite, metal foil, insulating films, adhesive materials, and so on are used in extremely thin states.

Making them thin allows space inside the product to be used effectively.

On the other hand, problems increase, such as being

・Prone to warping

・Prone to wrinkling

・Hard to pick up by suction

・Prone to stretching during peeling

・Susceptible to static electricity

If reinforcing materials are added for automation, thickness and thermal resistance may increase in turn.

Therefore, while considering

・Temporary support films

・Appropriate carrier stiffness

・Shapes that are easy to pick up by suction

・Suppression of warping after peeling

・Management of material direction

it is necessary to design thinness and process stability at the same time.

In wearable medical devices and biosensors, components are sometimes made to follow the human body or curved surfaces.

Flexibility is necessary.

However, inside, multiple functions are required, such as

・Heat dissipation

・Insulation

・Adhesion

・Sensor protection

・Waterproofing

If the hardness and thermal expansion of dissimilar materials do not match,

・Edges may lift

・Position may shift while worn

・The contact state of sensors may change

・Local temperature unevenness may arise

In this field, not only the shape during automated supply, but also

shape conformity after being applied to the human body or curved surfaces must be considered.

In materials research, properties of individual materials are measured, such as

・Thermal conductivity

・Coefficient of linear expansion

・Elastic modulus

・Adhesive strength

・Moisture absorption

In actual products, however, multiple materials are used in a laminated state.

Deformation of a laminate changes depending on

・The combination of materials

・The thickness of each layer

・Lamination order

・Hardness of the adhesive material

・The shape of partial lamination

・Temperature and humidity

・Constraint from surrounding components

Even if the properties of individual materials are known, it is not possible to fully determine how the laminate will warp or where it will peel.

Therefore, evaluation must look not only at the performance of individual materials, but at

warping, dimensional change, peeling, and automated suppliability in the actual laminated configuration.

Dimensions are right immediately after processing.

The lamination position is also right.

It looks flat on the reel.

That alone is not enough for a mass-produced component.

This is because the component is then

・Stored

・Transported

・Fed out from the reel

・Peeled

・Picked up by suction

・Applied

・Subjected to temperature changes

Processing quality is not correctness at the moment of processing.

It is maintaining the correct shape and function until the moment the customer uses it.

When supplying thermal management components using dissimilar materials to automated processes, the following points must be checked.

Material configuration

・Whether differences in thermal expansion between materials are not too large

・Whether the laminated structure is not asymmetric

・Whether the thickness and hardness of each layer are appropriate

・Whether the adhesive material can absorb stress

・Whether the adhesive layer does not shift at high temperatures

・Whether there is no dimensional change due to moisture absorption

・Whether adhesion can be maintained after temperature cycling

Lamination

・Whether tension differences between materials can be managed

・Whether it is flat even after the release film is removed

・Whether stress does not concentrate at partial lamination boundaries

・Whether position does not shift after high-temperature storage

・Whether the lamination order suits both processability and thermal performance

Reel supply

・Whether the core diameter suits the bending characteristics of the component

・Whether curl from winding is acceptable

・Whether adhesive materials and foams do not deform due to winding tightness

・Whether quality is stable from the start to the end of winding

・Whether component pitch is stable

・Whether the wound state can be maintained after transport

Peeling and suction pickup

・Whether peeling force is neither too high nor too low

・Whether evaluation is done at the actual peeling angle and speed

・Whether narrow parts or sharp corners deform during peeling

・Whether a suction surface is secured

・Whether the suction position matches the center of gravity

・Whether soft components can be supported during transport

・Whether the adhesive surface does not stick to the nozzle

Image recognition and application

・Whether the camera can recognize the component outline

・Whether front/back and orientation can be distinguished

・Whether recognition shapes do not obstruct the heat path

・Whether edges do not lift during application

・Whether the necessary contact area can be secured after compression bonding

Evaluation

・Whether it is checked not only immediately after processing but also after storage

・Whether warping after peeling is checked

・Whether evaluation is done under actual automated machine conditions

・Whether it is checked after high temperature, low temperature, and high humidity

・Whether positional misalignment and peeling after temperature cycling are checked

・Whether the start, middle, and end of winding of the reel are checked

Die-cut to the outer shape on the drawing.

Each layer laminated at the specified position.

Passes dimensional inspection.

If this much can be done, it looks complete as a processed product.

However, what customers need is not a component that has just come out of the processing machine.

It is a component that, inside the customer’s equipment,

・Can be fed out stably

・Can be peeled without deforming

・Can be recognized correctly

・Can be reliably picked up by suction

・Can be applied to the same position

・Can maintain thermal performance even after temperature changes

Thermal management materials move even after processing.

They stretch with temperature.

They stretch with tension.

They bend with winding.

They deform with peeling.

They shift within the adhesive layer.

That is why what OTIS should consider is not only whether materials can be cut and applied.

It is whether the necessary shape and function can be maintained until the moment the customer uses it.

This is where a precision processing company has meaning in contributing to thermal management.

At OTIS, we can contribute to turning dissimilar materials into thermal management components that can be used in volume production processes, through processing and supply design such as the following.

・High-precision lamination of dissimilar materials

・Lamination processing of metal foil and resin film

・Lamination processing of graphite and insulating materials

・Composite processing of thermally conductive materials and adhesive materials

・Partial lamination

・Die-cutting of multilayer laminated components

・Half-cut processing

・Reel-to-reel processing

・Product placement at a fixed pitch

・Examining release film and carrier configurations

・Designing winding direction and component orientation

・Shape processing that takes suction position into account

・Processing reference shapes that are easy for image recognition

・Lamination studies that take warping after peeling into account

・Component integration that reduces the number of automatic applications

・Checking supply quality, including image inspection

・Examining supply formats that take customer equipment conditions into account

The value OTIS provides is not lining materials up on reels.

It is putting thermal management materials into a state in which they can be incorporated in the correct position without stopping the customer’s process.

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

・Formulation development of thermal management materials themselves

・Chemical design of adhesives themselves

・Thermal design of entire products

・Dedicated CFD analysis

・Design and manufacture of automatic application equipment itself

・Development of industrial robot bodies

・Design of automation systems for customers’ entire factories

・Semiconductor chip design

・Design of entire cooling equipment

However, by working with materials manufacturers, equipment manufacturers, and customers, we can contribute in the area of designing and manufacturing processed components that connect material properties with the conditions of volume production equipment.

★★★★★ AI servers and data centers

★★★★★ Semiconductors and advanced packaging

★★★★★ EVs and next-generation batteries

★★★★★ Smartphones and smart devices

★★★★★ Wearable devices

★★★★☆ Medical devices

★★★★☆ Robots and automation equipment

★★★★☆ Optical communication equipment

★★★★☆ Aerospace

★★★★☆ Energy equipment

A thermal management component suited to automation is one whose shape does not change until the very end

By combining dissimilar materials, a single component can be given multiple functions, such as

・Heat dissipation

・Insulation

・Fixing

・Cushioning

・EMI countermeasures

・Sealing

However, each material differs in

・How it expands with heat

・How it changes with humidity

・How it stretches under tension

・How easily it bends

・How it moves during peeling

・How its adhesive layer deforms

That is why, even if it matches the drawing during processing, that alone is not enough.

It is wound onto a reel.

It is stored.

It is transported.

It is peeled from the carrier.

It is picked up by suction on an automated machine.

It is applied to the product.

It is repeatedly subjected to temperature changes.

If the component cannot maintain the necessary shape and position through all of this, thermal performance will not be achieved.

A component suited to automation is not simply a component that a robot can lift.

It is a component that

・Does not warp

・Does not stretch

・Does not deform during peeling

・Can be recognized in the correct orientation

・Can be picked up at a fixed position

・Can be applied to the same position

・Can maintain its contact state even after temperature changes

In other words, automated supply is not handing materials over to machines.

It is maintaining the shape and function of materials until the moment the customer uses them.

A thermal management component is not complete when it comes out of the processing machine.

It is wound onto a reel, transported, stored, peeled, picked up by suction,

applied, and subjected to temperature changes, and still keeps conducting heat where it is needed.

Only when all of that works does it become a mass-produced part.

What OTIS supports is not only the moment materials are cut.

It is the design that allows thermal management materials to keep functioning in the correct shape until the very end of the volume production process.

 

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.