A Study of Permittivity Measurement Reproducibility Utilizing the Agilent 4291B

In the analysis and design of electrical package and printed circuit board structures, engineers frequently rely on measured values of relative permittivity (epsiv_r). Typically, these measurements are performed using off-the-shelf instruments provided by a range of manufacturers. One instrument that is commonly used for measuring epsiv_r over the 1 MHz-1 GHz range is the Agilent 4291B. Using this instrument and Agilent's associated dielectric measurement fixture, a study of epsiv_r measurement reproducibility was performed. This study included five trained operators measuring nine material samples over three days. The material samples included both stacked and unstacked materials, hard and soft materials, and thin and thick materials. With this study, it was possible to estimate the ability of a typical laboratory to reproduce measurements of dielectric constant. In this case, our study showed that the Agilent 4291B system can be used by multiple operators and at different times to measure samples of ABF and FR5 to tolerances between 6% and 12%. Results for other material samples and measurement frequency effects are discussed