The surge of fifth-generation communication has intensified
the
demand for advanced dielectric layers in flexible copper-clad laminates
(FCCL). These layers must ensure a low dielectric constant (D
k) and dielectric loss (D
f) at high frequencies while meeting essential criteria, including
thermal and chemical stability, flexibility, and low water uptake
to achieve signal transmission efficiency and FCCL reliability. Herein,
we have developed flexible dielectric layers based on poly(phenylene
oxide)-g-poly(butadiene) (PPO-g-PB)
that exhibit low D
k and Df
values at high-frequency regimes. Two PPO-g-PB samples with different PB graft densities were synthesized
to explore the effect of PB side chains on the thermophysical properties
of the resulting PPO-g-PB film. The as-synthesized
PPO-g-PB demonstrated excellent film-forming ability,
allowing for straightforward fabrication through a simple casting
process followed by thermal curing. To determine the potential of
these dielectric polymers in high-frequency communication applications,
dielectric properties of thermally cured PPO-g-PB
(TC-PPO-g-PB) were investigated at high-frequency
regimes (from 10 to 110 GHz). Furthermore, we also monitored the water
uptake behavior and changes in dielectric properties during an 85
°C and 85% relative humidity reliability test to demonstrate
the practical application of these dielectric polymers as advanced
dielectric materials.