Abstract: A non-contact testing device for detecting continuity or shorts in conductors of a printed circuit board or integrated circuit employs a laser-activated plasma to make electrical connection between a test probe and a node under test. The plasma is generated in air in a small chamber which is subjected to a concentrated laser pulse, and the plasma exits the chamber due to its self-generated pressure. An electrically-conductive plume of ionized gas (i.e., plasma) is thus used to probe a circuit without making physical contact by a probe. Preferably, the chamber is a conical shape with metallic walls, and the laser pulse is directed into the chamber by a fiber optic cable ending at the large end of the chamber. The plasma exits an orifice at the small end of the conical chamber. The device may be moved about by an X-Y positioning mechanism to probe the circuit under test.

Abstract: A test cell for non-contact testing a circuit board for shorts and opens includes a hermetically sealable container for that circuit board, at least one wall of the container providing access to permit a circuit board to be positioned at an imaging plane inside the container. A pair of planar electrodes positioned inside the container are spaced on opposite sides of and parallel to the imaging plane and these electrodes are connected to contacts on the exterior of the container so that the electrodes can be releasably connected to an external voltage source to provide an electric field inside the container which extends perpendicular to the imaging plane. One of these electrodes and the container wall adjacent thereto are transparent to light from a pulsed laser positioned outside the container which is arranged to image a selected spot on a conductor of a circuit positioned at the imaging plane.

Abstract: A circuit is tested for unwanted shorts and opens by positioning the circuit between a pair of electrodes in a chamber filled with an inert gas with the circuit conductors facing one of the electrodes. The circuit is charged by applying a selected voltage to the electrodes to produce an electric field extending generally perpendicular to the circuit, the voltage polarity being such that the one electrode carries the negative electrical charge. The circuit is then subjected to a pulsed laser beam brought to a focus between the one electrode and a selected spot on a conductor of the circuit so as to ionize the chamber gas at the beam focus to form a plasma so that an electric charge is imparted to that spot and to other circuit conductor portions having electrical continuity with that spot.