Better Fire Safety for the 5G Revolution

Like 3G, 4G and earlier wireless standards, 5G promises to deliver another leap forward in communications and connectivity, this time marking a particularly significant step. Phones will be able to download complete 4K films in seconds and streaming will become extremely smooth. Augmented reality will assist our shopping decisions, cars, robots and factories will be fully connected to one another, and doctor visits will be possible from 1,000 miles away. The components that truly underpin the 5G revolution are printed circuit boards, or PCBs—thin layers with metal traces and mounted circuits designed to transmit radio signals. To implement the new standard, these PCBs must be installed on countless new base stations and devices and must perform better than before to support the high speeds and frequencies used by 5G. This includes how well they transmit signals, and their resistance to heat and moisture. This also encompasses Clariant's expertise in balancing all of this with reliable and sustainable fire safety.

When people talk about PCBs, they usually mean the entire assembly, but strictly speaking these are only the boards on which the electronic components of the circuit sit.

This board typically consists of copper-clad laminate, or CCL—a lasagna-like arrangement containing multiple layers of insulating material, usually filled with copper traces to conduct currents and signals. The non-conductive layers are made from epoxy resin or other suitable plastics, some of which are reinforced with paper or glass fiber, and the properties of these seemingly insignificant layers in the PCB lasagna are actually quite critical. This begins during manufacturing when components are soldered. As required by the EU's Restriction of Hazardous Substances Directive (RoHS), the heat involved can be quite high, especially when lead-free soldering is used. The relevant PCB parameter here is glass transition temperature, or Tg, which indicates the point at which the hard resin layers become rubbery and soft. Tg is also important when PCBs are used in hot environments, such as in cars or oil drilling, and high heat resistance is generally desired at the higher 5G operating temperatures. Low water absorption is also an advantage as it prevents corrosion of fine metal traces. Another important consideration where heat, moisture and frequency play a role is the electrical properties of the insulating materials. The key performance parameters of the non-conductive layers are the dielectric constant (Dk) and dissipation factor (Df), which need to be kept low to minimize transmission loss and delay. This also reduces power loss and electromagnetic "crosstalk" between fine copper traces—allowing 5G users to comfortably enjoy seamless high-speed communications and hyper-low latency, real-time applications.

Clariant's phosphorus-based flame retardants in the Exolit® OP and Exolit EP series have all the right properties to support these characteristics in high-speed, high-frequency PCBs and turn the 5G standard into reality.

Available both as liquid-processable products (Exolit EP) and very fine powders (Exolit OP), their high phosphorus content, which can also create synergy with other flame retardants, provides high efficiency at low doses. With their high thermal stability, they are suitable for lead-free assembly and packaging of electronics and can "withstand the heat" while 5G transmits at speed. They are also highly hydrophobic, meaning they do not readily dissolve in water or increase its absorption. Clariant's Exolit OP products do not significantly affect the Tg, Dk or Df of the final product, and even at a frequency of 10 gigahertz, a final dissipation factor of only 0.006 can be achieved. More importantly, halogen-free solutions must comply with RoHS regulations for flame retardants in electronics and are particularly a sustainable choice. The phosphinates are produced at Clariant's facilities in Germany using 100% green electricity. The company has also recently launched an environmentally friendly OP Terra product range based on renewable carbon sources. Not only for PCBs, but also for flexible CCLs called FCCLs, encapsulation, thermal management and electromagnetic shielding components, Clariant's halogen-free flame retardants offer ideal solutions. Through their own methods, these products—as advanced as the new 5G technology they help protect—contribute to making 5G both safer and more enjoyable. Exolit® is a registered trademark of Clariant in many countries.