Ultimately, as 5G telecommunications continue to roll out globally, the need for the materials that enable these 5G networks continues to grow. Millimeter-wave 5G, which operates in high-frequency bands between 24 and 100 GHz, offers faster data transfer speeds, lower latency, and greater bandwidth compared to previous wireless technologies such as 3G (<1 GHz) and 4G LTE (1–2.6 GHz), and even the more commonly deployed sub-6 GHz 5G frequency band.

However, the deployment of mmWave 5G technology presents challenges beyond its physical characteristics, such as the high transmission loss at higher frequencies, which disrupts mmWave 5G's ability to deliver high-quality signals to users. Reducing transmission loss will be a key obstacle that mmWave 5G technology must overcome, and therefore, this technology will require higher-performance materials that minimize transmission loss to support its growth.

This is where low-loss materials come into play. Improving the dielectric properties of these materials, which are found throughout a 5G device, from the printed circuit board (PCB) to the antenna and integrated circuit packaging, is critical for reducing transmission loss and improving 5G signal strength. This need is driving the growth of the market for low-loss materials for 5G applications, which IDTechEx forecasts will reach $1.8 billion by 2033.

PTFE: Could the proposed bans affect this popular choice for mmWave 5G?
One low-loss material of great interest for mmWave 5G applications is polytetrafluoroethylene (PTFE), a fluoropolymer and therefore a member of the perfluoroalkyl and polyfluoroalkyl (PFAS) family. PTFE has a lower dielectric constant (Dk) and loss tangent (Df) than commonly used low-loss thermoset materials. In fact, comparative studies by IDTechEx conclude that commercial PTFE laminates have a loss tangent that is, on average, six times lower than commercial epoxy-based laminates. PTFE also offers stable dielectric performance across a range of frequencies and temperatures, as well as resistance to heat and corrosion. For these reasons, many are exploring the use of PTFE, supplied by companies such as Rogers Corporation, Taconic and SYTECH (Shengyi Technology Co., Ltd), for their mmWave 5G base stations and customer premises equipment (CPE).

However, PTFE has its drawbacks, such as higher costs and manufacturing difficulties. Furthermore, there is the pressing issue of regulation, given some of the proposed bans on PFAS.

PFAS are considered "forever chemicals" due to the strength of the fluorine-carbon bond, with various health risks associated with their accumulation in the human body. PFAS are transferred to the water cycle during their manufacturing, use in industrial processes, and end-of-life treatment, resulting in unavoidable exposure for organisms.

The manufacture and use of PFAS chemicals are being subject to increasingly stringent regulations. The European Commission banned the use of PFAS in several areas, including firefighting foams, in 2021, with the intention of limiting its use to applications of critical social importance, while the European Chemicals Agency (ECHA) put forward a proposal in January 2023 to restrict all uses of PFAS in the EU by 2025. In December 2022, the US EPA published a memorandum that aims to reduce the discharge of PFAS into waterways.

Given current and proposed restrictions, some companies are trying to reduce their reliance on PFAS. One prominent company in this area is 3M, which announced in December 2022 that it will stop manufacturing PFAS and will work to phase them out by 2025. 3M cited regulatory restrictions, growing consumer interest in alternatives, and operational difficulties as the main reasons for exiting the PFAS market.

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

New alternatives to PTFE in the low-loss materials market

Given these new regulations, it is unclear whether the application of PTFE in mmWave 5G devices will be affected. As a result, companies may consider potential alternatives to PTFE for the mmWave 5G market. IDTechEx has analyzed several of these alternative materials, examining their dielectric performance, mechanical properties, suppliers, and market penetration. Some of the most discussed alternatives are highlighted below:

Hydrocarbon-based laminates
offer more than just the absence of PFAS components. They exhibit low passive intermodulation (PIM), contributing to both noise reduction and a low signal-to-noise ratio. This is advantageous compared to PTFE, which suffers from poor PIM stability over time. Furthermore, hydrocarbons are compatible with conventional circuit board materials, allowing them to be used to create composite laminates. Finally, they are offered at a lower cost than PTFE. However, hydrocarbon-based laminates typically have a high filler content, which can lead to processing difficulties, and their dielectric performance is less stable than PTFE's at moderate operating temperatures.

Poly(p-phenylene ether) (PPE) and poly(p-phenylene oxide) (PPO)
are high-temperature thermoplastic materials that have been used as dielectric materials in printed circuit boards for numerous markets, including telecommunications. They offer a dielectric constant and loss tangent similar to (though slightly higher than) those of PTFE, but with fewer environmental concerns and lower cost. However, PPO/PPE has higher moisture absorption rates than PTFE. More importantly, their loss tangents increase with increasing operating frequency, more so than PTFE's loss tangent; this lack of stability in the loss tangent at higher frequencies can be a concern for certain applications.

Low-temperature sintered ceramics (LTCCs)
offer, from a material properties perspective, a low loss tangent ideal for mmWave 5G, high insulation resistance, and a low coefficient of thermal expansion (CTE), which is important for manufacturing. Most importantly, LTCCs enable the fabrication of integrated packages that include embedded components; these packages are small and can be coupled to smaller mmWave 5G devices. However, LTCCs have a higher dielectric constant, more complex manufacturing processes, and higher costs.

Market forecasts for low-loss materials for 5G and 6G

The IDTechEx report, "Low-Loss Materials for 5G and 6G 2023-2033," explores the technological developments and market trends driving the growth of the low-loss materials market for next-generation telecommunications, including emerging materials. IDTechEx forecasts future revenue and area demand for 5G low-loss materials 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 sixty different forecast lines.