Method and apparatus for locating power plane shorts using polarized light microscopy

• Main Authors: HALPERIN; ARNOLD, SCAMAN; MICHAEL E, ARGYLE; BERNELL E, YARMCHUK; EDWARD J
• Format: Patent
• Language: English
• Published: 31.10.2000
• Edition: 7
• Subjects: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES; MEASURING; MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES; PHYSICS; TESTING

An apparatus and corresponding method for detecting, locating, or defining a short in a thin-film module. The apparatus includes a mechanical fixture supporting the module. A current source provides a current pulse to the module which produces a magnetic field and heating nearby the short which turns on and off as the pulsed current in the short turns on and off. Polarized light is directed onto the module, with an intermediate element disposed between the module and the source of the polarized light. The intermediate element may be a stress birefringent coating (e.g., a polyimide insulating layer) disposed on the module and onto which the polarized light is directed. The sample is rotated 0 to 45 degrees to maximize the birefringent effect. Alternatively, the intermediate element may be a magneto-optical Faraday rotator. A microscope is used to observe the module, facilitating identification of a short by the twisting of the polarization of the light as the short expands and shrinks in response to the heating or in response to the localized magnetic field. The preferred rotator is a composite having a garnet substrate, an iron garnet film disposed on the substrate, and a thin aluminum mirror layer disposed on the iron garnet film. The apparatus and method of the present invention have several applications.