Nondestructive high-temperature broadband dielectric properties measurements: Analysis and measurements.

摘要

A metallized ceramic coaxial probe has been developed for nondestructive high temperature broadband dielectric properties measurements. The probe is constructed out of alumina and metallized with a 3.0 mil thick layer of moly-manganese, and a 0.5 mil thick layer of nickel plating. Measurements have been done up to temperatures as high as 800;An uncertainty analysis to quantify the errors due to differential thermal expansion between the inner and outer conductors of metal coaxial probes was conducted. For this case a two dimensional (2D) cylindrical Finite-Difference Time-Domain (FDTD) code was developed. It is shown that air gaps on the order of 0.1 mm, between the inner conductor and the material under test can cause errors as high as 170% in the measurement of the input impedance. The FDTD code was also used to estimate errors due to rough surfaces.;The FDTD code was further utilized to facilitate the use of the new probe for nondestructive complex permittivity measurements of electrically "thin" samples. It is shown that by backing the material under test with a standard material of known dielectric constant, and based on iterative calculations using the developed 2D FDTD code, the complex permittivity of thin samples can be measured accurately while using reasonable computational resources.;Finally, with the developed knowledge from the error analysis, and the new FDTD code for thin-sample measurements, the probe was used to make high temperature measurements of the dielectric properties of thin substrates which are often used in semiconductor and microwave integrated circuit applications. Accurate results for substrates as thin as 0.6 mm, and at temperatures as high as 800