Effect of roughness and edge shape on mmWave microstrip line

Abstract

The use of mmWave is increasing in various fields, such as mobile communication and automotive radar. Furthermore, as the frequency increases and related technologies advance, miniaturization of mmWave devices is required. For the miniaturization of devices, it is advantageous to use thin substrate boards. Two main methods for fabricating thin boards are the Laminating and Sputtering methods. Those two ways have different conductor roughness levels as well as types of adhesion between dielectrics and conductors. Thin boards for mmWave are composed of low dielectric loss substrate but have significant conductor loss due to thin thickness. Therefore, because conductor loss accounts for a large portion of the total loss, the effect of conductor characteristics such as conductor roughness and edge shape can not be negligible. Furthermore, since the effect of roughness and edge shape gets significant as the frequency increases, it needs to be analyzed. In this study, we analyze the impact of conductor roughness and edge shape on mmWave microstrip line with low dielectric loss thin board for each fabrication method to investigate the effect of roughness and edge shape.