Characterization of halogen-free package materials using cavity resonators

Dielectric properties of substrate materials have a significant impact on electrical performance of packages including signaling power loss, propagation delay and crosstalk. With the focus on halogen-free (HF) package substrates, it is critical to understand the impact of this material change on high-speed signal integrity. In this paper, a closed rectangular cavity resonator and an open Fabry-Perot cavity resonator are proposed to characterize package materials over 2 GHz - 28 GHz range. The paper first studies the metrology repeatability and sensitivity to sample positioning and sample thickness. Then the proposed metrologies are used for electrical characterization of both HF and halogenated (H) package core materials. Finally, the impact of the core material change on the high-speed signaling performance is investigated through a modeling study for a typical differential input/output (IO) interface.