Surface breakdown of printed circuit board under magnetic field with reduced pressure
Boxue Du;Xiaohui Zhu;Yu Gao;Xin Lu;
Epoxy resin laminate onto which a pair of copper foil was printed was employed as test samples. The samples were placed in an artificial atmospheric chamber, which was vacuumed by a rotary pump from 100 kPa to 5 kPa. The magnetic field was produced by permanent magnets that were assembled to China magnets make E×B drift away from, into and parallel to the sample surface, respectively. Magnetic flux density was adjusted at 120 mT, 180 mT and 240 mT respectively. By applying a negative bias voltage between the electrodes, the time to surface breakdown was recorded. Obtained results show that when E×B is into the surface, the time to the breakdown is shortened; when E×B is away from the surface, the time to the breakdown is delayed; when E×B is parallel to the surface, the time to the breakdown remains approximately the same as the case without magnetic field. With the decrease of pressure, the time to the breakdown increases and the effect of magnetic field on breakdown appears to be strengthened.http://www.chinamagnets.biz
