Three dimensional space charge observation of printed circuit boards

We have investigated the ion migration phenomena of printed circuit boards, and found that the pulsed electroacoustic space charge measurement system can monitor the copper ion migration into the epoxy resin from the electrode surface. The migration, however, can proceed in any direction in the specimen simultaneously; therefore, it should be measured in three dimensions. We have measured metal-base epoxy resin insulated printed circuit boards by a newly developed three-dimensional pulsed electroacoustic method. The experimental results show that the space charge density varies in the lateral direction when ion migration occurs in the specimen