Method and apparatus for electrical and optical inspection and testing of unpopulated printed circuit boards and other like items
First Claim
1. An apparatus using the electrical and photo-emissive properties of a gaseous atmosphere for the electrical and physical inspection and testing by optical means of ites such as printed circuit boards, ceramic substrates, and other like items which contain or include electrically conductive parts, paths, and surfaces whose electrical and physical continuity and conformance to a standard is to be verified, said apparatus comprising a sealable substantially airtight chamber for containing a gaeous atmosphere while allowing access to the interior thereof for the placement of items under test, means for introducing a gaseous atmosphere capable of cathode luminescence at a low pressure into the sealable chamber with an item to be tested in place within the chamber, a movable probe disposed within the sealable chamber for coupling one terminal of a source of excitation electric potential to desired test points located within an x-y plane on the surface of an item under test, said sealable chamber having a transparent partition disposed over the location of an item under test for allowing viewing of the surface of an item being tested, and means for coupling a remaining terminal of said source of excitation electric potential to a conductive surface in said sealable chamber substantially opposite the surface of an item under test whereby cathode luminescence is produced within the sealable chamber around test points excited by said movable probe and around all points having electrical continuity therewith.
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Accused Products
Abstract
This application describes a novel method and apparatus for the electrical and mechanical inspection and testing of unpopulated electronic printed circuit boards, ceramic substrates and other items which have conductive pathways formed thereon, interconnecting conductive pads and other conducting surfaces. Examination and testing is accomplished by placing a printed circuit board or other item to be tested within a sealed chamber which contains a gaseous atmosphere capable of cathode luminescence such as argon, neon and the like. The sealed chamber includes a transparent panel or partition which allows viewing of the printed circuit board or other item under test and preferably is electrically conductive. One terminal of a source of excitation electric potential is connected to the transparent conductive panel and the other terminal is applied to one of the metallic runs or paths on the surface of the sample item to be tested. The electric field produced between the metallic run or path on the sample item and the transparent panel or window in the sealed chamber causes the gas immediately adjacent to the run to emit light or other electromagnetic radiation in accordance with the well-known "cathode luminescence" phenomenon. The light or other emissions thus produced forms a pattern which matches in size and shape the conductive pathway or run on the sample item which has been electrically excited. The observed pattern is then compared to a known or desired pattern to determine whether it meets a preset standard.
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Citations
33 Claims
- 1. An apparatus using the electrical and photo-emissive properties of a gaseous atmosphere for the electrical and physical inspection and testing by optical means of ites such as printed circuit boards, ceramic substrates, and other like items which contain or include electrically conductive parts, paths, and surfaces whose electrical and physical continuity and conformance to a standard is to be verified, said apparatus comprising a sealable substantially airtight chamber for containing a gaeous atmosphere while allowing access to the interior thereof for the placement of items under test, means for introducing a gaseous atmosphere capable of cathode luminescence at a low pressure into the sealable chamber with an item to be tested in place within the chamber, a movable probe disposed within the sealable chamber for coupling one terminal of a source of excitation electric potential to desired test points located within an x-y plane on the surface of an item under test, said sealable chamber having a transparent partition disposed over the location of an item under test for allowing viewing of the surface of an item being tested, and means for coupling a remaining terminal of said source of excitation electric potential to a conductive surface in said sealable chamber substantially opposite the surface of an item under test whereby cathode luminescence is produced within the sealable chamber around test points excited by said movable probe and around all points having electrical continuity therewith.
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20. A method using the electrical and photo-emissive properties of a gaseous atmosphere for electrical and physical inspection and testing by optical means of items such as electronic printed circuit boards, ceramic substrates, and other like items which contain or include electrically conductive parts, paths and surfaces for detection of discontinuities, (breaks), undesired conductive areas (shorts), or irregularities in the size or shape of such item and being implement with an apparatus comprising a sealable substantially airtight chamber having a transparent partition disposed over the location of an item under test for allowing viewing of the item being tested;
- said method comprising introducing an item to be tested into the interior of the chamber and sealing it closed in a substantially airtight manner, introducing a gaseous atmosphere capable of cathode luminescence at a location pressure into the interior of the chamber along with an item under test, coupling one terminal of a source of excitation electric potential with a movable probe to selected test points located within an x-y plane on the surface of an item being tested, and coupling a remaining terminal of said source of excitation electric potential to a conductive surface in said sealable chamber substantially opposite the surface of an item under test whereby cathode luminescence is produced within the sealable chamber around test points excited by the movable probe and around all points having electrical continuity therewith which is observed through the transparent partition.
- View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
Specification