Muttenz, November 23, 2020 – Like 3G, 4G and the wireless standards that went before, 5G
promises to bring us another leap in communication and connectivity – and this time a particularly
huge one. Phones will be able to download whole 4k movies in seconds, and streaming becomes
ultra-smooth. 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 minimize
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.
Giving better fire safety to the 5G revolution
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 synergized 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 10 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.