Boron nitride (BN) films for thermal conductivity Market | Latest Analysis, Demand Trends, Growth Forecast

Boron Nitride Thin Films Gain Importance in High-Heat Semiconductor Packaging and AI Server Cooling Systems

Boron nitride (BN) films for thermal conductivity are engineered thin-film materials deposited on substrates or electronic interfaces to improve lateral and through-plane heat dissipation while maintaining electrical insulation. These films are increasingly used in semiconductor packaging, RF electronics, electric vehicle power modules, LED systems, advanced computing hardware, and high-frequency communication devices where conventional polymer-based thermal interface materials face thermal stability limitations. The Boron nitride (BN) films for thermal conductivity Market is estimated at approximately USD 410 million in 2026, with semiconductor thermal management and power electronics accounting for more than 48% of total demand volume. Hexagonal boron nitride (h-BN) films dominate commercial utilization due to their high in-plane thermal conductivity, chemical stability, and compatibility with wafer-scale deposition processes.

Market segmentation across the Boron nitride (BN) films for thermal conductivity Market shows strong concentration in:

• Hexagonal boron nitride (h-BN) films
• CVD-grown BN films
• Sputtered BN coatings
• Flexible thermal dissipation films
• Semiconductor packaging applications
• EV and power electronics thermal substrates
• AI and HPC server cooling components

The electronics and semiconductor segment contributes the largest revenue share because of rising chip power density. Advanced processors used in AI accelerators and high-bandwidth memory stacks are now operating at thermal loads exceeding 700 W in server architectures, creating direct demand for electrically insulating thermal films. Thermal conductivity values above 250 W/mK for oriented h-BN structures are increasingly targeted for next-generation packaging integration.

“Heat dissipation challenges are becoming more severe as semiconductor devices operate at higher power densities across EV, AI, and industrial applications. This keeps Boron nitride (BN) films for thermal conductivity closely associated with Thermal Interface Materials for Semiconductor Devices, where efficient thermal transfer is critical for reliability. The market also overlaps with Aluminum nitride (AlN) substrates for power electronics supporting high-temperature device operation. Demand for ultra-high thermal conductivity materials is additionally strengthening linkage with Diamond for semiconductor. “

Semiconductor Packaging Expansion Driving Boron nitride (BN) films for thermal conductivity Market Demand

The largest demand shift in the Boron nitride (BN) films for thermal conductivity Market is linked to advanced semiconductor packaging. High-performance chiplet architectures, 2.5D packaging, and heterogeneous integration have significantly increased heat flux density at package level. Thermal bottlenecks are becoming more severe in AI accelerators, networking ASICs, and automotive power semiconductors.

In March 2025, Taiwan Semiconductor Manufacturing Company announced additional advanced packaging expansion exceeding USD 17 billion for CoWoS and SoIC capacity in Taiwan. The expansion directly increased demand for high thermal conductivity dielectric materials used in package substrates and thermal spreading layers. BN films are increasingly evaluated as ultra-thin thermal dissipation layers for next-generation interposers and substrate interfaces because aluminum nitride and polymer composites face thickness and stress limitations at smaller nodes.

Similarly, in October 2024, Samsung Electronics expanded advanced packaging and HBM manufacturing investments in South Korea with additional AI memory infrastructure spending exceeding USD 7 billion. HBM4 and stacked DRAM architectures require highly stable thermal management materials near TSV structures and memory controllers, where boron nitride films provide electrical isolation advantages over metallic thermal spreaders.

Demand concentration is particularly strong in:

Application Segment	Estimated 2026 Share
Semiconductor packaging	31%
Power electronics	24%
AI/HPC thermal systems	18%
RF and telecom electronics	11%
LED and optoelectronics	9%
Aerospace and defense electronics	7%

The semiconductor packaging segment is also benefiting from wafer-level thermal management adoption. Several substrate manufacturers in Japan and Taiwan are integrating ultra-thin dielectric heat-spreading films into organic package substrates to manage warpage and thermal cycling issues.

Hexagonal BN Films Account for Majority Consumption Across Thermal Dissipation Applications

Hexagonal boron nitride remains the dominant material type within the Boron nitride (BN) films for thermal conductivity Market due to its layered crystal structure and high thermal conductivity parallel to basal planes. Commercial demand is concentrated around h-BN films with thermal conductivity ranges between 100–400 W/mK depending on orientation, deposition method, and crystallinity.

Amorphous BN films continue to find usage in lower-cost electronic insulation applications, but their thermal performance remains lower than crystalline h-BN structures. Cubic boron nitride films occupy a niche position because production cost and deposition complexity restrict broader electronics adoption.

Current segmentation by material structure is estimated as:

• Hexagonal BN films: ~72%
• Amorphous BN films: ~18%
• Cubic BN films: ~10%

The strong preference for h-BN is linked to rapid expansion in GaN and SiC power devices. Wide-bandgap semiconductors operate at higher voltages and temperatures compared to silicon-based systems, creating direct demand for thermally conductive dielectric interfaces.

In January 2026, Wolfspeed increased silicon carbide device production at its Mohawk Valley Fab in the United States to support EV inverter and industrial power demand. Higher operating temperatures in SiC modules have accelerated adoption of ceramic thermal interface materials, including boron nitride-based films and coatings.

China is also becoming a major consumption center. In June 2025, BYD expanded EV power electronics manufacturing capacity in Shenzhen and Xi’an with additional inverter production lines supporting more than 3 million annual vehicle-equivalent power modules. This expansion increased regional demand for thermally conductive insulating materials used in traction inverter assemblies.

Deposition Technology Trends Reshaping Competitive Positioning in the Boron nitride (BN) films for thermal conductivity Market

Deposition technology selection strongly influences film quality, substrate compatibility, and cost structure. Chemical vapor deposition currently leads the Boron nitride (BN) films for thermal conductivity Market because it enables high crystallinity and large-area uniformity needed for semiconductor integration.

Technology segmentation trends for 2026 indicate:

Deposition Technology	Estimated Market Share
Chemical vapor deposition (CVD)	46%
Physical vapor deposition (PVD)	28%
Sputtering	17%
Atomic layer deposition-assisted processes	9%

CVD-grown BN films are preferred in semiconductor and high-frequency electronics because thinner films can maintain thermal conductivity without sacrificing dielectric properties. Japanese and South Korean electronics material suppliers remain heavily concentrated in this segment due to advanced thin-film process capabilities.

In February 2025, Applied Materials expanded materials engineering programs focused on advanced packaging and heterogeneous integration technologies. The company increased R&D spending related to deposition and interface engineering for thermal management layers, indirectly supporting development activity across BN-based thermal film ecosystems.

ALD-assisted hybrid processes are attracting attention for ultra-thin dielectric integration below 10 nm equivalent thicknesses. Although commercial penetration remains limited, these processes are increasingly evaluated for AI accelerator packaging where heat density is approaching physical limitations of conventional TIM materials.

AI Infrastructure and Data Center Heat Density Increasing Demand for Electrically Insulating Thermal Films

AI server infrastructure has emerged as one of the fastest-growing downstream demand centers for the Boron nitride (BN) films for thermal conductivity Market. GPU clusters and AI accelerators generate significantly higher heat loads compared to conventional enterprise servers.

In April 2025, NVIDIA announced expanded Blackwell AI platform shipments with rack-level power consumption crossing 120 kW for certain AI server configurations. Such thermal density increases demand for high-performance thermal interface and heat-spreading materials that can maintain electrical isolation near densely packed interconnects.

Data center construction growth is also influencing the market. In August 2025, Microsoft announced additional AI infrastructure investment programs exceeding USD 30 billion across North America and Europe. Expansion of hyperscale AI infrastructure increases indirect demand for advanced semiconductor thermal materials used in CPUs, GPUs, optical modules, and power delivery systems.

Flexible BN films are gaining traction in:

• AI accelerator substrates
• Optical transceiver modules
• High-density power conversion boards
• Foldable electronics
• RF front-end modules

These films provide lower dielectric loss compared to many oxide-based thermal materials while supporting high-frequency signal integrity requirements.

Boron Nitride Thermal Film Consumption Rising in 5G, RF Electronics, and Satellite Systems

High-frequency electronics represent another strong opportunity area for the Boron nitride (BN) films for thermal conductivity Market. RF power amplifiers and phased-array systems generate localized heat concentrations that degrade signal stability and device reliability.

In November 2024, Japan allocated additional semiconductor and advanced electronics funding exceeding USD 6.5 billion targeting advanced materials and next-generation communication systems. Part of this funding supports thermal management material development for RF modules and high-speed communication hardware.

BN films are increasingly preferred in RF electronics because they combine:

• Electrical insulation
• High thermal stability
• Resistance to plasma environments
• Compatibility with compound semiconductor substrates
• Low dielectric constant characteristics

Satellite electronics and aerospace systems are also contributing niche but high-value demand. Thermal cycling resistance and vacuum stability make BN films suitable for space electronics operating under extreme environmental conditions.

The Boron nitride (BN) films for thermal conductivity Market is therefore evolving beyond traditional thermal interface applications toward integrated thin-film thermal engineering across semiconductor packaging, EV power electronics, AI computing systems, and RF communication hardware. Demand growth remains closely tied to chip power density escalation, wide-bandgap semiconductor adoption, and advanced packaging investment cycles across Taiwan, South Korea, China, Japan, and the United States.

 

Asia Pacific Controls Majority Share of Boron Nitride Film Manufacturing Capacity for Thermal Electronics Applications

Asia Pacific accounts for nearly 67% of global production capacity in the Boron nitride (BN) films for thermal conductivity Market, supported by concentration of semiconductor packaging facilities, ceramic material processing infrastructure, thin-film deposition capabilities, and electronics manufacturing ecosystems. Japan, China, South Korea, and Taiwan form the primary manufacturing cluster for boron nitride thermal films, while the United States maintains technological leadership in specialized aerospace-grade and semiconductor-grade BN deposition technologies.

The supply structure remains highly integrated with:

• Semiconductor wafer fabrication
• Ceramic engineering materials
• Advanced packaging substrates
• Power electronics manufacturing
• RF communication hardware
• EV inverter supply chains

Commercial production of boron nitride films requires high-purity boron precursors, advanced deposition systems, controlled crystalline orientation, and cleanroom-compatible thin-film manufacturing. These requirements limit large-scale manufacturing to countries with mature semiconductor materials ecosystems.

Estimated regional production share in 2026:

Region	Estimated Production Share
Asia Pacific	67%
North America	18%
Europe	11%
Rest of World	4%

Japan alone contributes nearly 24% of global high-performance BN film output because of its strong position in advanced ceramics, specialty chemicals, and semiconductor materials engineering.

Japan Maintains Technology Leadership in High-Purity Boron Nitride Thin Film Production

Japan remains one of the most critical production centers for the Boron nitride (BN) films for thermal conductivity Market due to its advanced materials ecosystem and strong semiconductor supply chain integration. Domestic producers focus heavily on high-crystallinity h-BN films for semiconductor packaging, RF electronics, and thermal interface applications.

The country’s production advantage is linked to:

• High-purity ceramic processing
• Precision sputtering technologies
• Semiconductor-grade precursor manufacturing
• Advanced vacuum deposition systems
• Strong substrate manufacturing base

In April 2025, the Japanese government approved additional semiconductor and advanced materials support exceeding USD 8 billion targeting next-generation semiconductor manufacturing and packaging ecosystems. Part of this funding directly supports materials used in thermal management, dielectric layers, and advanced substrates.

Japanese manufacturers are also benefiting from rapid expansion in AI semiconductor packaging. Taiwan and South Korea increasingly import specialty ceramic and thin-film thermal materials from Japan because domestic alternatives still face consistency limitations for high-end semiconductor applications.

The country maintains strong export positioning in:

• CVD-grown h-BN films
• Sputtering targets
• Thermal ceramic coatings
• High-frequency insulating films
• Advanced dielectric thermal layers

Japan’s electronics production ecosystem also supports domestic demand. Automotive electronics production and power semiconductor deployment continue to increase. Hybrid and electric vehicle output from Japanese OEMs exceeded 9 million units combined in 2025, supporting consumption of thermally conductive insulating materials in onboard charging and traction inverter systems.

China Expanding Domestic Capacity Across Boron Nitride Thermal Film and Ceramic Supply Chains

China is the fastest-growing production region in the Boron nitride (BN) films for thermal conductivity Market, driven by rapid investment in semiconductor localization, EV electronics manufacturing, and thermal management materials.

China currently contributes approximately:

• 29% of total BN film manufacturing volume
• More than 40% of boron precursor processing
• Nearly 35% of downstream power electronics consumption

Large-scale growth is linked directly to domestic semiconductor investment cycles. In May 2025, SMIC expanded advanced process and specialty semiconductor production capacity in Shanghai and Shenzhen with multibillion-dollar equipment additions targeting domestic chip manufacturing growth. Higher local wafer and packaging output increased consumption of thermal management films used in package substrates and power electronics.

The EV ecosystem is another major demand driver. In 2025, China’s new energy vehicle production crossed 16 million units, supported by aggressive industrial policy and inverter manufacturing expansion. Power modules based on SiC and GaN architectures require thermally conductive dielectric materials capable of operating under elevated voltage and temperature conditions.

Chinese suppliers are increasingly active in:

• Flexible BN thermal films
• Polymer-BN hybrid thermal layers
• Sputtered boron nitride coatings
• Thermal management sheets for consumer electronics

However, high-end semiconductor-grade h-BN films still rely partly on imported deposition technologies and process equipment from Japan and the United States. Yield consistency, impurity control, and crystalline orientation remain key competitive gaps for several domestic suppliers.

Taiwan and South Korea Influence Demand More Than Raw Production Volume

Taiwan and South Korea hold disproportionate influence in the Boron nitride (BN) films for thermal conductivity Market because they dominate advanced semiconductor packaging and memory manufacturing, even though their raw BN material output is smaller than China or Japan.

Taiwan contributes nearly 21% of global semiconductor-driven BN film demand through:

• Advanced packaging
• AI accelerator assembly
• High-density substrate manufacturing
• Chiplet integration

In September 2025, Taiwan Semiconductor Manufacturing Company accelerated CoWoS advanced packaging expansion with monthly packaging capacity targets exceeding 85,000 wafers. This expansion increased procurement of thermal spreading materials and dielectric heat dissipation films used in package-level thermal management.

The country’s packaging ecosystem increasingly requires:

• Ultra-thin dielectric films
• High thermal conductivity interface layers
• Thermal stress reduction materials
• Heat-spreading coatings for interposers

South Korea remains heavily concentrated in memory and display electronics. Demand for boron nitride thermal films is closely tied to HBM production growth and OLED electronics manufacturing.

In January 2026, SK hynix announced additional HBM packaging and memory expansion investments supporting AI server deployment. Thermal density in stacked memory systems is increasing rapidly, creating demand for thin dielectric thermal films capable of operating within compact package architectures.

South Korea also maintains a strong position in flexible electronics and OLED panels, where flexible BN films are increasingly evaluated for thermal spreading in foldable devices and high-refresh-rate displays.

North America Strengthening Specialized BN Film Production for AI Infrastructure and Aerospace Electronics

North America accounts for approximately 18% of global Boron nitride (BN) films for thermal conductivity Market production, but its role is concentrated in high-value applications rather than mass-volume manufacturing.

The United States leads in:

• Aerospace-grade BN films
• Semiconductor R&D applications
• Defense electronics
• AI computing thermal systems
• Advanced deposition technologies

Federal semiconductor incentives continue to reshape the production landscape. In August 2024, the United States Department of Commerce approved additional CHIPS Act funding programs supporting semiconductor material and packaging ecosystems. Multiple packaging and substrate facilities announced expansion plans tied to thermal management material localization.

AI infrastructure growth is strongly influencing domestic BN film demand. GPU and accelerator systems used in hyperscale AI clusters require advanced thermal materials capable of handling sustained high-power operation.

Estimated North American end-use split:

End-use Sector	Share of Regional Demand
AI and HPC systems	33%
Aerospace and defense	21%
Semiconductor packaging	27%
EV power electronics	12%
RF communication systems	7%

In June 2025, Intel expanded advanced packaging activities in Arizona linked to heterogeneous integration and AI processor manufacturing. These developments support growing consumption of thermally conductive dielectric materials integrated into package structures and substrate interfaces.

Europe Focuses on Automotive Power Electronics and Industrial Thermal Management Systems

Europe contributes nearly 11% of total production in the Boron nitride (BN) films for thermal conductivity Market, with Germany and France serving as the major industrial centers. Regional demand is strongly linked to automotive electrification and industrial power systems.

European manufacturers emphasize:

• SiC power electronics
• Industrial automation
• Automotive inverter systems
• Rail electrification components
• Renewable energy power conversion systems

In February 2025, Infineon Technologies expanded silicon carbide semiconductor investments in Germany and Austria to support EV and industrial electrification demand. Thermal management materials became increasingly important as higher switching frequencies and power densities created elevated thermal stress in module packaging.

Germany remains the largest regional consumer because of:

• Automotive electronics manufacturing
• Industrial automation systems
• Renewable power conversion equipment
• EV drivetrain electronics

European supply chains are also focusing on thermal reliability standards. Automotive-grade BN films increasingly require qualification for long-duration thermal cycling, vibration resistance, and moisture stability under harsh operating environments.

Application Split Shows Semiconductor and Power Electronics Dominance Across Regional Consumption

Regional consumption patterns within the Boron nitride (BN) films for thermal conductivity Market continue to reflect semiconductor and electrification investment concentration.

Estimated global application split for 2026:

Application	Estimated Share
Semiconductor packaging and substrates	31%
Power electronics and EV systems	24%
AI servers and HPC hardware	18%
RF and telecom electronics	11%
Consumer electronics and displays	9%
Aerospace and defense systems	7%

The highest growth rates are currently visible in AI server infrastructure and wide-bandgap semiconductor applications. Both sectors require thermally conductive electrically insulating films with stable performance under high heat flux density, making boron nitride-based thin films increasingly important across advanced electronics manufacturing ecosystems.

 

Competitive structure in Boron nitride (BN) films for thermal conductivity Market remains material-led rather than film-only

The Boron nitride (BN) films for thermal conductivity Market is still not a pure film-supplier market in the same way as PET film, PI film, or copper foil. Most commercial supply is controlled by companies making high-purity h-BN powders, engineered BN fillers, BN coatings, pyrolytic BN components, and thermal interface materials that are converted into films, sheets, coatings, laminates, or dielectric heat-spreading layers by downstream formulators. For 2026, the top eight suppliers and material platform owners are estimated to control nearly 58–64% of value in the addressable BN thermal film and BN-based thermal layer ecosystem.

Company	Relevant product position	Estimated 2026 share in BN thermal film ecosystem
3M	3M™ Boron Nitride Cooling Fillers for TIMs, CCLs, polymers	12–14%
Saint-Gobain Boron Nitride	hBN powders, CeraGlide® BN coatings, thermal management BN materials	10–12%
Momentive Technologies	BN powders, BN coatings, thermal management ceramic materials	9–11%
Denka Company	Hexagonal boron nitride powder and BN coating agent	7–9%
Resonac	SHOBN™ UHP hexagonal BN fillers for gap fillers and thermal adhesives	6–8%
Shin-Etsu Chemical	Pyrolytic boron nitride and thermal interface material platforms	4–6%
Goodfellow	Boron nitride film and BN ceramic materials for R&D/industrial use	2–4%
Specialist CVD/2D material suppliers	h-BN films for semiconductor R&D and device-level applications	8–12% combined

3M holds one of the strongest positions in thermally conductive BN filler platforms used in polymer films, thermal interface pads, adhesives, and copper-clad laminate systems. 3M states that its Boron Nitride Cooling Fillers provide in-plane material thermal conductivity of about 400 W/m·K and can improve polymer thermal conductivity by 2–8 times compared with alumina fillers. This matters for the Boron nitride (BN) films for thermal conductivity Market because many commercial “BN film” products are not freestanding CVD BN layers; they are BN-filled polymeric films, pads, adhesive sheets, and laminate layers used in electronics cooling.

Saint-Gobain Boron Nitride is another major participant, with a portfolio covering hexagonal boron nitride materials, CeraGlide® boron nitride coatings, and thermal management solutions for electronics. Its BN powders are positioned for electronic cooling, low-loss dielectric applications, and high-frequency circuit materials. The company’s strength is not limited to one film product; it is positioned across powder morphology, coatings, and engineered BN material supply used by formulators producing thermal films and dielectric layers.

Momentive Technologies has strong relevance in high-purity BN powders and coatings. Its BN materials are used because boron nitride has high thermal conductivity among electrically insulating materials and functions as a thermal management filler in polymers. Momentive also offers thermal management silicones, including greases, adhesives, encapsulants, liquid-dispensed thermal pads, and gap fillers, which gives it downstream participation in electronic cooling materials beyond raw BN powders.

Japanese and Korean material suppliers shape premium BN thermal film conversion

Denka is important in the high-purity h-BN supply chain. Its boron nitride powder is positioned for thermal conductivity, heat resistance, corrosion resistance, electrical insulation, and additive use in multiple matrix systems. Denka also lists BN coating agents for heat-resistant demolding applications, and its electronics material catalog places ceramic powders and molded parts within heat dissipation and IC-sealing resin ecosystems. This supports Denka’s role as an upstream supplier for BN-filled thermal films and dielectric heat-spreading layers rather than only bulk ceramic parts.

Resonac is relevant through SHOBN™ UHP hexagonal boron nitride powder, used in gap fillers and thermal adhesives requiring heat radiation with electrical insulation. The company’s thermal filler portfolio positions BN as a material for high thermal conductivity, high thermal stability, corrosion resistance, low dielectric constant, and high insulation. In the Boron nitride (BN) films for thermal conductivity Market, Resonac’s share is strongest where BN fillers are compounded into silicone films, adhesives, and thermal gap materials for power modules and high-density electronics.

Shin-Etsu Chemical’s direct BN relevance is mainly pyrolytic boron nitride. The company describes PBN as a high-purity ceramic manufactured by CVD at around 2,000°C, with heat resistance, thermal shock resistance, thermal conductivity, chemical resistance, and electrical insulation. Shin-Etsu also has a thermal interface materials business covering silicone-based TIMs, pads, greases, and gap-filling materials. For strict film-market classification, Shin-Etsu should be treated as a specialty BN ceramic and TIM platform supplier, not as a confirmed mass producer of h-BN thermal films.

Goodfellow occupies a smaller but visible position in BN film and research-grade supply. Its BN film material information highlights thermal conductivity, electrical insulation, dielectric strength, and suitability for microelectronics, photonics, LEDs, and integrated circuits. Goodfellow’s role is stronger in prototyping, R&D, and specialty material procurement than in large-volume electronics thermal film supply.

Boron nitride thermal film suppliers compete on morphology, purity, orientation and convertibility

Competition in the Boron nitride (BN) films for thermal conductivity Market is not determined only by nominal thermal conductivity. Buyers evaluate platelet size distribution, surface treatment, resin compatibility, dielectric loss, viscosity impact, film-forming behavior, and ability to maintain insulation after thermal cycling. This is why powder and filler companies remain central to the film market. A BN powder that disperses cleanly into silicone, epoxy, polyimide, or copper-clad laminate resin systems can capture more value than a higher-conductivity material that creates brittleness or poor adhesion.

The premium segment is moving toward:

• oriented h-BN films and sheets for higher in-plane conductivity;
• BN-filled thermal interface films for AI processors, GPUs, and power modules;
• BN-containing copper-clad laminates for 5G and high-speed electronics;
• CVD or pyrolytic BN films for semiconductor, photonics, and compound semiconductor applications;
• hybrid BN-alumina or BN-silicone structures where cost and processability matter.

The market share picture therefore remains semi-fragmented. 3M, Saint-Gobain, Momentive, Denka, and Resonac form the strongest material-supplier group, while thin-film specialists and 2D-material suppliers serve semiconductor R&D, photonics, and prototype device integration. No single company controls more than 15% of the 2026 Boron nitride (BN) films for thermal conductivity Market because the supply chain is divided between raw BN, engineered filler, coating, film conversion, and end-use thermal interface design.

Recent industry developments influencing BN thermal film demand

• January 2024 – Momentive Technologies highlighted BN for thermal management, citing the role of hexagonal BN fillers in improving heat dissipation and reliability of electronic components and assemblies. This supports rising use of BN in electronic cooling films, pads, adhesives, and encapsulants.
• April 2026 – Resonac expanded technical positioning around surface-treated BN fillers for high-thermal-conductivity materials, reinforcing demand from gap fillers, thermal adhesives, and electrically insulating heat-dissipation systems.
• October 2025 – Denka invested through its CVC fund in boron nitride nanotube development, indicating continued Japanese interest in advanced BN nanomaterials with thermal conductivity, mechanical strength, and electrical insulation properties.
• March 2026 – 3M released application material around BN Cooling Fillers for TIM and copper-clad laminate applications, directly linking BN materials with heat management and signal transmission in PCB layers.