Safety Without Interference: Developing Flame Retardants for High end application PCBs

Nothing sits still in our fast-paced world – especially modern technology. Technological advancements have increased our reliance on data, and as a result, large volume data must be processed at faster rates. While the semiconductor landscape dynamically evolves to meet data requirements, managing large data sets presents complexities, particularly when it comes to communication between semiconductor chips and other components.

At the heart of this communication lies the packaging—specifically, the printed circuit boards (PCBs) and interposers that physically connect to the chips. These packages play a pivotal role in determining the speed and quality of the data. Yet, if not optimized effectively, they can also become disruptive bottlenecks in fields such as healthcare, media, transportation, AI servers and energy. Dedicated to leading safe progress, ICL is using flame retardant innovation to create a positive impact on packaging signal communication.

The factors influencing signal performance

There are various physical factors that influence signal performance, including trace surface roughness and cross-sectional properties. However, the resin surrounding these traces is equally crucial – especially its dielectric constant (DK) and dissipation factor (Df).

The DK impacts the signal speed within the traces. This is due to dipoles, or static charges, which exert an electrostatic force on the electrons involved in signal and data transmission. Their rate of change directly correlates with the resin's dielectric constant.

The Df, on the other hand, quantifies how the resin environment affects signal loss and noise introduction. Energy dissipation from the metal to the surrounding resin environment can weaken the signal, leading to a drop in signal strength and signal-to-noise ratio.

The resin that encapsulates the PCB traces is not a homogenous material; rather, it incorporates various additives for property control. Flame retardant additives play a crucial role in safety enhancements and regulatory compliance, and therefore their presence in the PCB resin is mandatory. Yet unless they are specifically tailored to the resin's DK/Df properties, they are liable to impair the signal.

The Extreme Low-loss FR challenge

Low DK/Df materials for PCBs are categorized into five classes: Mid-Loss; Low-Loss; Very Low-Loss; Ultra Low-Loss; and Extreme Low-Loss. Each classification corresponds to specific application needs, with higher categories (such as Extreme Low-Loss) resulting in lower latency and faster signal propagation within the PCB.

To achieve Extreme Low-Loss for both the resin and PCB, flame retardants and additives must be compatible with the resin while ensuring optimal signal performance. Traditionally, halogens have been used as flame retardants in PCB resins. Unfortunately, halogens are highly electronegative elements, and their presence introduces dipoles that contribute substantially to the material’s dielectric constant. Halogens may be sufficient for traditional PCB, but they cannot comply with today's high speed and frequency data processing needs.

At the FRontier: Tailoring flame retardants to specific resin characteristics

Achieving Extreme Low-Loss classification for both semiconductor resin and PCB is becoming a global prerequisite. This requires the inclusion of reactive, non-halogenated flame retardants that meet resin requirements while ensuring optimal signal performance.

In 2023, ICL established FRontier, a groundbreaking initiative dedicated to developing innovative and sustainable FR solutions. Aware of the need for optimized data processing and high-volume communication transference, ICL's FRontier experts work diligently with semiconductor companies and PCB and resins manufacturers to address their most acute needs.

New and effective flame retardants are developed in state-of-the-art R&D labs, and are tailored to specific resin characteristics. Every company in the industry has a preferred resin type, and therefore each FR solution must be expertly crafted according to material specifications.

"Low loss PCB laminates are the new industry standard, and flame retardant solutions must evolve accordingly", says Dr. Ronny Costi, Business Development Manager and FRontier Lead at ICL. "Safety and compliance are always the top priority, but that's not the entire story anymore. FR additives must also 'stay clear' of communication signals. In the past, this wasn't an important requirement, but in today's world it is absolutely imperative."

Crafting unique solutions isn’t new to ICL and its FR experts. The focus on flame retardants for low loss PCBs joins additional breakthroughs achieved at ICL's R&D labs, including advanced FRs for electric vehicles, new wash-durable flame retardants for cotton textiles, and more. But with the FRontier initiative, ICL is tackling the world's most acute challenges via a collaborative approach. Internally, ICL encourages collaborations across different company divisions. Externally, ICL's experts team up with bright minds from various scientific research fields, in an ambitious attempt to reach unprecedented FR innovation.

"Tailoring FR solutions for the semiconductor market is a goal we take very seriously", says Costi. "When it comes to flame retardants for high-end laminates, we are confident in our ability to respond to every need. The more complex the mission, the more dedicated we are to developing a precise response."

Looking to improve your resin's signal speed and integrity with an optimized FR solution? Reach out to our experts at [email protected]