Abstract
Space charge accumulation in insulating material under a high electric field is said that it is closely related to the breakdown of the insulating material. Since a thin insulating film is used as a flexible printed circuit board, such high stress might be generated in the film. Therefore, it is required to measure the space charge distributions accumulated in such thinner insulating layers to evaluate the characteristics them. We tried to improve the positional resolution of the PEA system to measure the space charge distributions in such thin insulating films. It is found that the improvement enables us to measure the space charge distribution with a positional resolution of about 2.5µm.