Patent ID: 6621274
Filing Date: 2003-09-16
Classification: B01D,Y02A

Abstract:
A system for testing for opens in and shorts between conductor traces on a surface of a printed circuit board, the conductor traces having a reference potential, said system comprising:an electron gun assembly for generating an electron beam; an electron optics assembly for directing the electron beam to the conductor traces on the surface of the printed circuit board; a grid located proximate to and substantially parallel with the surface of the printed circuit board, said grid capable of collecting secondary electrons emitted from the printed circuit board, said grid being placed at a first potential before the electron beam is directed to a first point on a conductor trace to charge the conductor trace to a first potential, and being placed at a second potential, the second potential being between the reference potential and the first potential, before the electron beam is directed to a second point on a conductor trace to cause emission of secondary electrons; and signal processing electronics and a CPU for determining whether or not an open or short exists depending on whether secondary electrons are collected by said grid as the electron beam is directed to various locations on the conductor traces on the surface of the printed circuit board.