Characterization of Delamination in Fiber-Reinforced Epoxy-Based PCB Laminates, Using an EBG-Enhanced Planar Microwave Sensor

A strategy to detect the extent of delamination in fiber-reinforced epoxy-based thermoset polymer used in printed circuit board (PCB) laminates by a planar microwave microstrip sensor has been proposed in this paper. The sensitivity of the sensor probe is improved using electromagnetic band gap (EBG) structures surrounding the planar sensor. The proposed EBG cells acts as a bandstop filter and suppress the propagation of surface wave current. The sensitivity measured in terms of the reflection coefficient of the sensor on the sample was found to increase by 9.5 dB for the sensor with EBG when compared to the sensor without EBG. The sensor is designed and verified through finite-integration-based simulations and validated through measurements after fabrication. The delamination factors for various extents of delamination are detected using the probe and exhibit an accuracy of about 85%.