Dielectric Properties of Insulation Layers of Printed Circuit Boards at High Frequencies

Complex permittivities of various polymeric materials used as insulation layers of printed circuit boards were measured at frequency range from 1 MHz to 110 GHz by using a newly developed waveguide penetration dielectric measurement system using and five commercial systems. The new system has been originally developed for measuring lossy liquid specimens, such as tissue-equivalent liquids, and can also measure the complex permittivity of rod shape solid specimens, without reference materials. Experimental results reveal that the data measured by four different methods were in good agreement. The dielectric loss tandelta of most of insulation layers can become more than 0.01 at GHz order and the anisotropy is considerably high. Permittivities are strongly influenced by the humidity and the temperature. This work can contribute to clarify the dielectric properties of materials used in printed circuit boards that would affect the total loss of components as well as the electromagnetic compatibility characteristics