Giving better fire safety to the 5G revolution

Augmented reality will help us with our shopping decisions, cars, robots and factories fully connect, and doctor's visits become possible from a 1,000 miles away.

The components the 5G revolution literally rests on are printed circuit boards, or PCBs - thin sheets with metal traces and mounted circuits for transmitting radio signals. To implement the new standard, these PCBs must be installed in countless new base stations and devices, and to support the high speeds and frequencies 5G uses, they must perform even better than before. This includes how well they relay signals and resist to heat and moisture - and it also includes Clariant's specialty, balancing all this with reliable and sustainable fire safety.

When people talk about PCBs, they often mean the entire assembly, but properly they are only the board that the electronic components of the circuit sit on. This board usually consists of copper-clad laminate, or CCL - a lasagna-like arrangement often featuring multiple layers of insulating material riddled with copper traces for conducting currents and signals. The non-conductive layers are made of epoxy resin or other suitable plastics, some of them reinforced with paper or glass fiber, and the properties these seemingly unimportant layers of the PCB lasagna have are actually very vital.

This already starts during manufacture, when the components are soldered on. The heat involved can be quite high, especially when lead-free soldering is used, as required by the EU's Directive on the Restriction of Hazardous Substances Directive (RoHS). The relevant PCB parameter here is their glass transition temperature, or Tg, which indicates at what point their rigid resin layers become rubbery and soft.

The Tg is also important when PCBs are used in hot environments, as for instance in cars or oil drills, and high heat resistance is generally desirable in the higher 5G operating temperatures. Low water absorption is also a plus, as it wards off corrosion of the fine metal traces.

Another crucial aspect which heat, moisture and frequency all play into are the electrical properties of the insulating materials. The key performance parameters of the non-conductive layers here are dielectric constant (Dk) and dissipation factor (Df), which both must be kept low to minimise transmission loss and delay.

This also reduces loss of power and electromagnetic "crosstalk" between the fine copper traces - ensuring 5G users smooth high-speed communication and tranquil enjoyment of hyper-low latency and real-time apps.

Clariant's phosphorus-based flame retardants from the Exolit OP and Exolit EP lines have all the right characteristics for supporting these properties in high-speed, high-frequency PCBs and making the 5G standard a reality. Available both as liquid processable product (Exolit EP) and very fine powders (Exolit OP), their high content of phosphorus, which can also be synergised with other flame retardants, gives them high efficiency at low doses.

With their high thermal stability, they are suitable for lead-free assembly and packaging of electronics, and able to ‘stand the heat’ when 5G transmission runs hot. They are also highly hydrophobic, meaning they are not easily dissolved by water or increase its absorption.

Our Exolit OP products neither significantly impact the Tg nor the Dk and Df of the final product, and even at a frequency of ten gigahertz, a final dissipation factor of only 0.006 can be achieved. Just as importantly, the halogen-free solutions need to comply with RoHS regulations for flame retardants in electronics, and are a particularly sustainable choice. Our phosphinates are produced with 100% green electricity at our German plants, and recently we have introduced an earth-friendly OP Terra range of products, based on renewable carbon sources.

Not just for PCBs, but also for flexible CCLs called FCCLs, encapsulation, thermal management and electromagnetic shielding components our non-halogenated flame retardants offer great options. In their own way, they are just as advanced as the new 5G technology they help to protect - and contribute to making both safer and more enjoyable.