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US 4,538,104 AGranted
In-circuit test apparatus for printed circuit board
AssigneeTest Point 1, Inc.
InventorsBruce S. Douglas, Chester V. Westergart
Life of this patent
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Abstract
An in-circuit test apparatus having a vacuum chamber between a top plate and a base plate. The apparatus has an adjustable bearing block assembly located at each quandrant to provide a precision alignment between the top plate and the base plate. A continuous double-hollow tube is located in a uniform groove in the base plate and forms a seal when held captive between the top plate and the base plate. A plurality of spring probe pressure pins are mounted within the chamber. The pins project through drilled individual access ports in the top plate and make electrical contact with a printed circuit board under test when the top plate collapses under a vacuum.
Claims17
An in-circuit test apparatus for printed circuit boards, comprising in combination:
- a baseplate having a first and second section, said first section including a top surface having a continuous groove about a baseplate edge forming a vertical outer wall, said groove having molded rounded interior corners, a channel slot with a cylindrical cavity at each end and an external penetration through said vertical outer wall, and further including a bottom surrounded by said vertical outer wall having at least one baseplate penetration adjacent to each of said rounded interior corners, said baseplate penetration piercing a shallow rectangular recess having a first threaded receptacle within the baseplate bottom, said second section including an outer frame molded to said first section, said outer frame including a hinge for connecting said outer frame to a tester interface;
- a top plate mounted atop said first section forming a chamber therebetween and having a flat, smooth upper surface, and a bottom surface with a center portion having peripheral edges and including an array of standoff stops distributed about said bottom center portion, and at least a single guide shaft for aligning the top plate with said base penetration and having contoured corners symmetrically matching said rounded interior corners of the baseplate;
- a vacuum inlet fitted to said external penetration through the baseplate vertical outer wall for creating a vacuum within said chamber;
- a first vacuum seal held captive between the top plate and the baseplate and within said continuous groove, the vacuum seal being closed upon itself and sealing said rounded interior corners of the baseplate and said contoured corners of the top plate for maintaining said vacuum within said chamber;
- and
- a bearing block assembly having an adjustable mounting block in physical communication with each of said shallow rectangular recesses within said baseplate bottom and a linear bearing pressed into said block and passing through one of said baseplate penetrations and further comprising a second threaded receptacle located within said guide shaft, said guide shaft passing through said bearing and said block for independently adjusting the top plate relative to the baseplate.
3 more elements
An in-circuit test apparatus for printed circuit boards, comprising in combination:
- a baseplate having a first and second section, said first section including a flat. smooth-surfaced top having a continuous uniform groove along the lengths of a baseplate edge forming a vertical outer wall of the height of said top, said continuous groove having molded rounded interior corners, a molded channel slot parallel to said baseplate edges and inward from said continuous groove with a cylindrical cavity at each end and an external penetration through said vertical outer wall, and further including a smooth-surfaced bottom supported above the bottom edge of said vertical outer wall having at least one baseplate penetration adjacent to each of said rounded interior corners, said baseplate penetration piercing a shallow rectangular recess having at least a single first threaded receptacle within the baseplate bottom, said second section including an outer frame molded to said first section and a center frame member equally dividing said outer frame, each being the height of said vertical outer wall and forming twin rectangular openings;
- a top plate mounted atop said first section forming a chamber therebetween and having a flat, smooth upper surface, and a bottom surface with a center portion having peripheral edges and including an array of standoff stops distributed about said bottom center portion, and further including at least a single guide shaft for aligning the top plate with said baseplate penetration and having a contoured corner symmetrically matching said rounded interior corners of the baseplate;
- a vacuum inlet fitted to said external penetration through the baseplate vertical outer wall for creating a vacuum within said chamber;
- a first vacuum seal held captive between the top plate and the baseplate and within said continuous uniform groove, the vacuum seal being closed upon itself and sealing said rounded interior corners of the baseplate and said contoured corners of the top plate for maintaining said vacuum within said chamber;
- a plurality of return springs mounted within said cylindrical cavities within the baseplate for repositioning the top plate of said vacuum chamber when said vacuum is released;
- a bearing block assembly having an adjustable mounting block in physical communication with each of said shallow rectangular recesses within said baseplate bottom and a linear bearing pressed into said block and passing through one of said baseplate penetrations and further comprising a second threaded receptacle located within said guide shaft, said guide shaft passing through said bearing and said block for independently adjusting the top plate relative to the baseplate.
- a plurality of spring probe pressure pins mounted within said vacuum chamber between the baseplate and the top plate and projecting through the top plate when vacuum is applied making electrical communication with a printed circuit board under test;
- a tester interface hinged to the baseplate and having an electrical coupling between said spring probe pressure pins and an external test device;
- and
- a bottom cover plate connected to said tester interface for routing and protecting said electrical croupling between said spring probe pressure pins and said external test device.
7 more elements
Dependencies are inferred from the claim text.