Electrical characterization of multi-layered printed circuit boards

Multi-layered printed circuit boards (PCB) are an insulating system that sometimes is affected by failures, due to several possible causes. Three following main "weak areas" within the insulation have been identified: (1) the interface between the layers (it can form a privileged path for a total discharge); (2) the presence of gaseous or metallic inclusions in the dielectric, especially in regions affected by divergent fields; (3) the metal coated drilled holes adopted to connect different layers - even in this case the presence of regions with divergent fields can initiate a discharge path. The matter in point has a validity as a method to approach the problem. Therefore, the outcome of an experimental study aimed at deciding the best type of specimen geometry capable of mimicking the role of the above defects along a possible failure mechanism is presented and discussed. Actually, two groups of test patterns and the relevant tests are reported and commented upon.