Paper Title
Non-destructive Detection of Prepreg Defects in Multilayer PCB

Abstract
Prepreg is a composite and often is highly anisotropic in nature. This coupled with his resistive properties, severely restricts detection of deeper defects in multilayer PCB, where it finds application.In this work, a systematic methodology has been presented for the detection of defects in prepreg isolating layers. Different test samples with artificial defects of different sizes and depth were fabricated for experimental studies. Both one-sided and two-sided lock-in thermography test methods were explored.As a result of numerical modeling, of the heat conduction problem in PCB with different constructions, the optimal combination of parameters of the thermographic non-destructive procedure at zero noise has been developed for each specific case.Experiments were conducted to verify the corresponding theoretical predictions. Keywords - Printed Circuit Board, Nondestructive Testing, Thermal Image, Prepreg.