2006 年 9 巻 2 号 p. 119-122
The internal charge behaviour of insulation layers of printed circuit boards is discussed. Internal charges due to ion impurities can move under adc electric field, and the internal electric field is determined by the charges. The charge behaviour is strongly influenced by temperature and humidity. We have newly developed an in-situ space charge measurement system that can measure the space charge profiles in an environmental chamber at 85°C and 85%. Larger levels of internal charge were observed at higher humidity, and the electric fields near the electrodes were increased. The in-situ space charge measurement system should contribute to the study of ageing phenomena of insulation layers of PCBs.