PAS 61338-1-5-2010 Waveguide type dielectric resonators – Part 1-5: General information and test conditions – Measurement method of conductivity at interface between conductor layer and dielectric substrate at microwave frequency (Edition 1.0)
Microwave circuits are popularly formed on multi-layered organic or non-organic substrates. In the microwave circuits@ the attenuation of planar transmission lines such as striplines@ microstrip lines@ and coplanar lines are determined by their conductor loss@ dielectric loss and radiation loss. Among them@ the conductor loss is a major factor in the attenuation of the planar transmission lines. A new measurement method is needed to evaluate the conductivity of transmission line on or in the substrates such as the organic@ ceramic and LTCC (low temperature co-fired ceramics) substrates. The IEC 61338-1-3 described the measurement method for the surface resistance Rs and effective conductivity ??on the surface of the conductor. The term ??is designated as ?? in this PAS@ and is called surface conductivity (Figure 1). This PAS describes a measurement method for resistance and effective conductivity at the interface between conductor layer and dielectric substrate designated as Ri and?? respectively@ and are called interface resistance and interface conductivity. For the transmission line in the substrates@ the electric current is concentrated at the interface between conductor layer and dielectric substrate@ because the skin depth ??in the conductor is the order of ?? in thickness at the microwave frequencies. In microstrip lines@ the current is concentrated at the interface@ rather than at the open face of the conductor. Furthermore@ in copper-clad organic substrates@ the interface side of the copper foil has rugged structure to hold the strong adhesive strength. In LTCC substrates@ the interface between the conductor and ceramics has a rough structure@ depending on the co-firing process and the material compositions. The interface conditions increase the conductor loss. Therefore@ the evaluation of Ri and ?? is important to design microwave circuit and to improve the conductor fabrication process. This measurement method has the following characteristics: ?C the interface resistance Ri is obtained by measuring the resonant frequency f0 and unloaded quality factor Qu of a TE01??mode dielectric rod resonator shown in Figure 2; ?C the interface conductivity ?? and the relative interface conductivity ??ri =??i / ??0 are calculated from the measured Ri value@ where ??0 = 5@8x107 S/mis the conductivity of standard copper; ?C the measurement uncertainty of ??ri ( ????ri ) is less than 5%.