A Novel Metamaterial Enhanced Microwave Testing System for Bare PCB Substrates Using Image Rendering Approach

This paper proposes a method for detection of cracks in bare printed circuit board sheets before etching of interconnects and mounting dies. A microwave planar sensor probe is designed, and the impedance matching property is used for anomaly detection in flame retardant-4 sheets. The proposed technique and apparatus is first validated through finite-integration-based technique and then through measurement. The resonant frequency information thus obtained is then plotted on a 2-D gradient representation matrix. A novel Windows VB-based application software is developed to determine the dimensions of the crack in the sample through various interpolation operations and dimensioning technique on the image matrix. These are then effectively displayed in a graphical user interface.