A Rapid and High-Precision Electronic Non-Metallic Substrate Thickness Detection Sensor Based on Coaxial Resonator

This article proposed a microwave sensor with the characteristic of a simple structure that can be applied to rapid, convenient, safe, and high-precision measurements of the thickness of electronic industry non-metallic substrates produced by industrial line production through the mechanical or manual scan method. The proposed sensor comprises a resonant cavity, a cross-coupling ring (CCR), and a feed port. During operation, the proposed sensor is fed through a conventional SMA, and the proposed CCR enables efficient coupling of microwave signals. Simulation results indicated that the proposed sensor has a practical thickness measurement of
$2500~\mu \text{m}$
for a variety of non-metallic thin plates for the electronics industry, with a theoretical measurement accuracy of
$25~\mu \text{m}$
(less than 1%) and an average frequency shift accuracy of more than 0.634 MHz/
$\mu \text{m}$
. By processing and testing the proposed sensor, the tested results proved its reliable thickness measurement capability of
$25~\mu \text{m}$
within the range of
$2500~\mu \text{m}$
, which also further proved it will hopefully realize the theoretical measurement performance by introducing higher precision processing. It can be predicted that it will be valuable in the rapid inspection of industrial non-metallic substrates since its characteristics are rapid, convenient, safe, and high precision.