Characterizing the Anisotropic Dielectric Constant of Package Material Considering the Fiber-Weave Effect

The anisotropic nature of the dielectric constant (Dk) in package materials is notably impacted by the presence of glass fiber weaves, resulting in distinct Dk values between the XY plane and the Z direction. This study presents a theoretical analysis and numerical calculation of the directional variations in dielectric constants induced by glass cloth fibers. These calculations are further validated through EM cavity resonator simulations, confirming their accuracy. For the first time, it is conclusively demonstrated that in substrate materials containing glass fibers, the equivalent dielectric constant in the plane is higher than that in the perpendicular direction. This finding offers significant guidance for the design of high-frequency and high-speed electronic products.