The Materials Science Behind High-Frequency Circuit Reliability: Stability of High-Frequency, High-Speed Hydrocarbon Resins

When designing high-frequency circuits, engineers typically focus first on core electrical performance parameters such as dielectric constant (Dk) and loss factor (Df). However, a successful product must not only excel under ideal laboratory conditions but also maintain stability after years of real-world application—enduring temperature fluctuations, humidity erosion, mechanical vibration, and other challenges. Therefore, high-frequency circuit reliability is a critical lifeline metric as vital as initial electrical performance, rooted in the essence of materials science.
High-frequency, high-speed hydrocarbon resins gain favor in demanding fields like aerospace, automotive electronics, and communication base stations precisely because they deliver exceptional electrical performance while establishing a comprehensive and robust reliability assurance system. This system manifests primarily in three dimensions:

First, exceptional thermal stability. High-frequency circuits, particularly high-power RF circuits, inherently generate significant heat. Additionally, PCB assembly processes subject them to intense thermal shocks during lead-free reflow soldering at approximately 260°C. High-frequency, high-speed hydrocarbon resins achieve a glass transition temperature (Tg) exceeding 180°C through deep hydrogenation, which forms a stable saturated molecular structure. This ensures it maintains a rigid glassy state under most operating and processing temperatures, resisting delamination, warping, and deformation to preserve circuit integrity and fine line spacing. Its thermal decomposition temperature of up to 400°C provides ample safety margin against transient high temperatures.

Second, exceptional environmental tolerance. Moisture is the “invisible killer” of high-frequency circuits. Water molecules, being highly polar, immediately degrade Dk and Df values upon penetrating the substrate, causing circuit performance drift. The molecular backbone of hydrocarbon resin consists of non-polar carbon and hydrogen atoms, inherently endowing it with hydrophobic properties. Its dense cross-linked network structure further blocks water molecule penetration, resulting in a water absorption rate below 0.05%. This “impervious to moisture” characteristic ensures circuits maintain long-term, stable electrical performance whether in humid coastal regions or environments with fluctuating temperature and humidity cycles—a critical factor in enhancing high-frequency circuit reliability.

Third, robust mechanical bonding strength. Multilayer high-frequency circuit boards are complex structures formed by laminating layers of dielectric materials and copper foil. Differences in thermal expansion coefficients (CTE) between materials generate significant internal stresses during repeated temperature cycles. These stresses are the primary cause of catastrophic failures such as multilayer delamination and via cracking. Advanced high-frequency, high-speed hydrocarbon resins employ specialized formulations to effectively regulate their CTE, achieving better compatibility with copper foil and reducing stress at its source. More importantly, unique interfacial bonding technology ensures exceptionally strong adhesion between the resin and copper foil, typically yielding peel strengths exceeding 8 lb/in. This formidable “grip force” guarantees circuit integrity remains rock-solid even under severe thermal shock, effectively preventing board explosions and trace delamination risks.

In summary, high-frequency circuit reliability is a comprehensive challenge encompassing thermal stability, environmental endurance, and mechanical robustness. The value of high-frequency, high-speed hydrocarbon resins lies not only in meeting “performance” demands through exceptional low-loss characteristics, but also in fulfilling the more stringent requirement of “reliability” through this meticulously engineered stability system. It demonstrates to the industry that a premier circuit material must be the perfect integration of short-term performance and long-term dependability. Only then can it truly uphold the promise of cutting-edge technology for the future.