Legislation restricting the usage of "forever chemicals," or per- and polyfluoroalkyl substances (PFAS), is being debated in major markets like the European Union and the U.S. But with certain members of the PFAS family, namely fluoropolymers like polytetrafluoroethylene (PTFE), being considered for next-generation 5G applications, how will this affect the low-loss materials market for 5G?

After all, as 5G telecommunications continue to roll out globally, the need for materials that enable these 5G networks continues to grow. This is particularly true for the 5G frequency band with the most interest and excitement – mmWave 5G. mmWave 5G, operating in high frequency bands between 24 to 100 GHz, offers faster data transfer rates, low latency and higher bandwidth compared to previous wireless technologies, like 3G (less than 1 GHz) and 4G LTE (1 to 2.6 GHz), and even the more commonly deployed 5G frequency band of sub-6 GHz.

However, deploying 5G mmWave technology poses challenges beyond its physical characteristics, such as high transmission loss at higher frequencies, which disrupts the ability of mmWave 5G to deliver high-quality signals to users. Reducing transmission loss will be a key barrier for mmWave 5G to overcome; as such, mmWave 5G will require higher-performing materials that minimize transmission loss to support its growth.

This is where low-loss materials come in. Improving the dielectric properties of these materials, found in every corner of a 5G device from the printed circuit board (PCB) to the antenna to the IC packaging, is critical to reduce transmission loss and enhance 5G signal. This need is fueling the growth of the low-loss materials market for 5G applications, which IDTechEx forecasts to hit $1.8 billion by 2033.

PTFE: Could Proposed Bans Affect This Popular Choice for mmWave 5G

One low-loss material of high interest for mmWave 5G applications is polytetrafluoroethylene (PTFE), a fluoropolymer and, therefore, a member of the per- and polyfluoroalkyl substances (PFAS) family. PTFE has a lower dielectric constant (Dk) and loss tangent (Df) than commonly used low-loss thermoset materials. In fact, IDTechEx's benchmarking studies in their "Low-loss Materials for 5G and 6G 2023-2033" report finds that commercial PTFE laminates have a loss tangent that is, on average, 6x less than commercial epoxy-based laminates. PTFE also offers stable dielectric performance across a range of frequencies and temperatures, as well as heat resistance and corrosion resistance. For these reasons, many are exploring using PTFE, which is supplied by the likes of Rogers Corporation, Taconic and SYTECH (Shengyi Technology Co., Ltd), for their mmWave 5G base stations and customer premises equipment (CPEs). 

However, PTFE does have its drawbacks, such as higher costs and difficulties in manufacturing. Then, there is the pressing question of regulation, given some of the proposed PFAS bans. PFAS are considered "forever chemicals" due to the strength of the fluorine-carbon bond, with several health risks associated with accumulation in the human body. PFAS are transferred to the water cycle during their manufacturing stages, use in industrial processes and end-of-life treatment, leading to inevitable exposure for organisms. 

The manufacture and utilization of PFAS chemicals are becoming subject to increasingly tough regulations. The European Commission banned the use of PFAS in several areas, including fire-fighting foams in 2021, intending to limit their use to applications of critical societal importance, while the European Chemical Agency (ECHA) brought forward a proposal in January 2023 to restrict all uses of PFAS in the E.U. by 2025. In December 2022, the U.S. EPA issued a memo that aims to reduce PFAS discharge to waterways.

Given current and proposed restrictions, some companies are looking to reduce their reliance on PFAS. A notable player in this space is 3M, who announced in December 2022 that it will cease manufacturing and work to discontinue the use of PFAS by 2025. 3M cited regulatory restrictions, consumers becoming "increasingly interested in alternatives," and operational difficulties as primary reasons for exiting the PFAS market. 

The exact legislation affecting PFAS will not be known any time soon. As the proposal submitted to the ECHA enters a consultation period by the scientific committees, many in the industry are calling for fluoropolymers to be differentiated and excluded from these broad bans. The result may have far-reaching implications, but regardless of the outcome, these developments have presented a large amount of uncertainty in the market. 

Emerging Alternatives to PTFE in the Low-Loss Materials Market

In the face of these legislative developments, it's uncertain whether the application of PTFE in mmWave 5G devices will be affected. As a result, companies may consider potential alternatives for PTFE for the mmWave 5G market. IDTechEx has discussed several of these material alternatives in their "Low-loss Materials for 5G and 6G 2023-2033" report, looking at their dielectric performance, mechanical properties, suppliers and market penetration. A few of the most discussed alternatives have been highlighted below:

Hydrocarbon-based Laminates
Hydrocarbon-based laminates offer more than simply not being a part of the PFAS family. Hydrocarbon-based laminates have low passive intermodulation (PIM), contributing to noise and low signal-noise ratio; this is advantageous compared to PTFE, which has poor PIM stability over time. Additionally, hydrocarbons are compatible with conventional circuit board materials, so they can be used to form a composite laminate. Lastly, they are offered at lower costs than PTFE. However, hydrocarbon-based laminates often have high filler content, which can lead to processing difficulties, and it has less stable dielectric performance than PTFE at moderate operating temperatures. 

Poly(p-phenylene ether) (PPE) and Poly(p-phenylene oxide) (PPO)
PPO and PPE are high temperature thermoplastic materials that have been used as the dielectric material in PCBs for numerous markets, including telecommunications. They offer similar (if slightly higher) dielectric constant and loss tangent compared to PTFE but with less environmental concerns and lower cost than PTFE. However, PPO/PPE have higher moisture absorption rates than PTFE. More importantly, their loss tangents increased as operating frequency increased, more than PTFE's loss tangent; the lack of loss tangent stability at higher frequencies may be concerning for certain applications.

Low Temperature Co-fired (LTCC) Sintered Ceramics 
LTCC refers to ceramics with sintering temperature under 1000°C; from a materials properties standpoint, LTCC offer a low-loss tangent ideal for mmWave 5G, high insulation strength and low co-efficient of thermal expansion, which is relevant for manufacturing. Importantly, LTCC enables the manufacture of integrated packages that include embedded components; such packages are small and can be fitted to smaller mmWave 5G devices. However, LTCCs suffer from a higher dielectric constant, complex manufacturing processes and higher costs.

Market Forecasts for Low-loss Materials for 5G and 6G

IDTechEx's latest report, "Low-loss Materials for 5G and 6G 2023-2033," explores the technology developments and market trends driving the growth of the low-loss materials market for next-generation telecommunications, including the new materials being explored. IDTechEx forecasts future revenue and area demand for low-loss materials for 5G while carefully segmenting the market by frequency (sub-6 GHz vs. mmWave), six material types and three application areas (smartphones, infrastructure and CPEs) to provide 60 different forecast lines.