Thermal Interface Materials (TIM) are not glamourous but are often an essential component found in all manner of electronic and energy storage applications. Indeed, they are absolutely pervasive. They are truly a diverse technology in terms of suppliers, material options, deposition techniques, applications, market requirement and performance levels. This makes them difficult to analyse.

 

In this report, we have analysed all the key established and emerging technology options. This report carefully examines the applications which are extremely diverse. We cover base stations, consumer electronics, power electronics, LEDs, and energy storage. We consider real use cases and product teardowns in order to formulate our analysis and build our market models. We take a granular view for each market category. Indeed, our forecasts are broken into 51 specific sub-segments, as shown below, giving them unparalleled granularity. Finally, we provide our forecasts in area or sqm. We believe that this is the most appropriate metric in analysing the market since, in the absence of one-size-fits-all solutions, the solutions' thickness levels vary.

 

 

Our granular forecasts enable us to develop a detailed view of the key market trends. Here we briefly discuss some top-level trends.

 

The consumer electronic market is today the largest market category. This is because the TIM content per unit is relatively high, but, more importantly, because the annual unit sales are high. Here, TIM is used with the electronics and the batteries. In a typical mobile phone, for example, there are multiple thermal pads connecting the EMI shield lid, which covers multiple ICs, to the framework. There is also typically a heat spreader below the battery as well as behind the display. In some recent versions, a heat pipe is also introduced to act as a compact and efficient heatsink. In laptops, there are usually TIMs atop or below the CPU, GPU, SSD memory and batteries. In general, this is a large market but will not register significant growth as the unit sales are already in the saturation phase.

 

Telecoms is also another significant market. In traditional base stations, TIM is used in both the baseband and the remote radio head unit. The baseband unit itself is typically composed of various parts such as baseband processing board, control board, power supply, and so on. This had been a fast-growing market in recent years as LTE stations were globally rolled out. This trend will continue as LTE is still being rolled out in various parts of the world such as China. However, this trend will go into a fast decline from 2023 onwards. This is because 5G stations will start to be rolled out in more significant numbers. As such, the opportunity will shift towards 5G system.

 

Here, the TIM requirements are likely to be different. The rise of 5G will change the relationship between the baseband unit and the remote radio head. Furthermore, the rise of active antenna arrays will require the integration of many front-end modules, which contain a power amplifier, right behind the antenna array substrate. The fact that air losses at higher frequencies are higher will imply that power amplifier will need to output higher powers even when the gain from the active antenna array itself becomes substantial. Finally, 5G will lead to a proliferation of smaller cells, the so-called micro or femto cells. These require even more compact designs. Indeed, a trend will be to use advanced packaging technologies to achieve as much functional integration as possible per packaged chip. All these trends point towards higher power density per unit area thus more challenging TIM requirements.

 

Data centres are likely to continue their growth rates thanks to both increased new as well as replacement demand. These centres are very energy intensive and heat management is a critical task. TIM are used in almost all components of a data centre including the serve boards, switches, supervisor modules, and power supplies. Here, the employed TIM technologies are not likely to significantly change.

 

Power electronics remain an important market for TIM. In classical power electronic modules, the baseplate is connected via a TIM to a heatsink. However, many designs in high performance applications, including many in electric vehicle traction drivers, are seeking to eliminate the TIM. This is because the TIM is the most thermally resistive section of the thermal path from the semiconductor junction to the heatsink. Indeed, many designs, some of which are already in volume production, have direct cooling, e.g., air or liquid directly cool the baseplate, and have thus eliminated the TIM. This trend suggests that the TIM consumption in electric vehicle power electronics will not grow as fast the power electronics market itself. Note that phase change materials pre-applied by the module maker are popular in power electronic modules since the wetting and spreading property together with the thinness at operating temperatures give rise to high performance which can be better guaranteed. The market remains substantial overall, registering 6% average annual growth rate between 2020 and 2030 across all the categories including home appliances, renewables, industrial, and EV as well as non-EV traction applications.

 

The LED market is very substantial. TIM are used in many LEDs. The LED packaging technology is diverse including die-on-lead-frame, die-on-ceramic, die-on-metal-core-PCBS, and so on. In general lighting, TIM is often used in moderate- to high-power LED lights to connect the metal-insulator-substrate or board with the heatsink. The use of LEDs in automotive lighting is also substantially growing. In the exterior of car, there are many light sources including front light, rear right, signal lights, and so on. The use of TIM will grow nearly hand-in-hand with the penetration of LEDs in automotive lighting. In headlamps, traditional light sources will compose only 55% (75% today) of the total in 2023 with the rest using standard or Matrix LEDs. LEDs are also used in LCD displays. Here, too, often a heat spreader layer is used in both backlit and edge lit LCD displays. This is a notable market given the huge aggregate surface area of annually produced screens.

 

 

The big driver of change however is the energy storage market, or more specifically the lithium ion battery market in electric vehicles. This is because the rise of electric vehicles will translate into growing demand for batteries. Furthermore, the growth in range of electric vehicles will translate into large battery capacities. These are large batteries composed of many cells. Thermal management is a key issue, which underpins efficient performance and is also safety critical in order to prevent thermal runaway.

 

There are today many different ways in which thermal interface materials are used in battery modules. This is natural as a dominant settled design has yet to emerge. In nearly all cases, there is potted thermal interface materials on the bottom plate of the battery pack, creating a thermal path between the cells and the heatsink. In some cases, there are head spreaders in-between the individual cells, further promoting heat conduction. In some designs, to prevent thermal failure spreading between cells, an insulating cushion foam, e.g. PU, is deployed. In pouch cells there can also be layers of gap pads.

 

This market will register dramatic growth over the coming decade, thereby completely changing the market composition for TIMs. This growth is driven by (a) rise in the addressable market which is essentially the growth in all manners of electric vehicles, and (b) the high thermal material content per battery pack and indeed per kWh deployed. As a consequence, we forecast that this market segment will grow from nearly zero to more than half of the total market (in sqm terms) by 2025. This will indeed be a dramatic transformation.

 

Thermal interface materials can take numerous forms (and names), from gap pads/fillers to conductive adhesives, thermal greases, and beyond. There are a variety of property considerations for a TIM given its specific applications this includes the adhesiveness, viscosity, coefficient of thermal expansion (CTE), bond line thickness, reworkability, and longevity. However, the most significant is the through-plane conductivity and the thermal contact resistance (the interface of the interface material). The trend towards higher performance TIM will continue as devices utilize more dense arrangements of ICs.

 

This report looks at all the incumbent materials, such as the prevalent ceramic-filled silicones, phase change materials (PCM), and more.

 

In addition, this report looks at new emerging materials and how they are processed. It is important to consider routes to manipulating the alignment of conductive fillers. Alignment, particularly for anisotropic additives, can either provide a cost saving by using less material for same performance or improve the performance for the same filler content. This should also be considered in conjunction with the mechanical performance the matrix material provides. Achieving alignment can be done in multiple routes: mechanical, magnetic, electrical, dielectrophoresis, or in how the conductive fillers are grown.

 

Many are turning to advanced carbon for higher conductivity either as a conductive filler in a polymer matrix or standalone. This includes graphite, pitch-based carbon fiber, carbon nanotubes, and graphene. As shown in the figure below, achieving vertical alignment gives the potential for high conductivity up to ca. 80 W/mk.

 

One of the most notable examples is the adoption of carbon fiber in the Samsung Galaxy Note9. IDTechEx has been informed that carbon fiber based TIM is also in use for power electronic devices in electric vehicles, a variety of military applications, high performance computing and more.

 

Graphite through to graphene as sheets, pastes or vertically aligned in pads have all received a significant amount of attention. All report significant conductivity improvements and show current and future promise in LEDs, consumer electronics, base stations and more.

Carbon nanotubes have been known since the early 1990s and have been explored as a conductive filler, but more notable is the extensive research in vertically aligned forests/arrays (VACNT). There are still notable challenges, from how the VACNT are transferred after growth through to how they achieve uniform contact resistance. However, significant collaborations and announcements from many of the leading players in China and Japan indicate that this a promising future area.

 

One of the challenges with using advanced carbons is that they are electrically conductive; this means the device must be designed accordingly. Ceramics are preferred for this amongst other reasons. There are trends to more spherical or flake like particles where appropriate, but concerning emerging material there is more interest around boron nitride nanostructures. Boron nitride nanotubes (BNNT) or nanosheets (BNNS) are both starting to become commercial.

BNNTs have a wide variation in property and cost with still a limited number of players, but many are progressing from the lab to pilot plants and even full-scale production. Most cite TIM as a key target market with already some promising results and interest from significant industries.

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