Automated laminography system for inspection of electronics
First Claim
1. A solder connection inspection device comprising:
- an X-ray source comprising;
an electron source for producing a beam of electrons;
an anode having a surface upon which said electron beam impinges; and
an electrical steering device for deflecting said electron beam to different locations on said anode surface, said steering device capable of causing said electron beam to rotate about an axis and to trace a substantially circular path upon said anode surface thus causing said X-ray source to move in a first circular pattern, said first circular pattern defining a first plane;
an X-ray detector for producing X-ray cross-sectional laminographic images of said solder connection, said detector positioned to receive X-rays produced by said X-ray source which have penetrated said solder connection, said X-ray detector comprising;
a converter screen for producing an optical image corresponding to an X-ray image formed by said penetrating X-rays;
means for moving said converter screen such that it rotates about said axis and travels along a substantially circular path defining a second circular pattern, said second circular pattern defining a second plane which is substantially parallel to said first plane;
an optical derotation device for transmitting said optical image from said rotating converter screen to a stationary optical image plane; and
a camera located at said stationary optical image plane for detecting said optical image, said camera havingan electronic output which corresponds to said optical image;
a fiducial element, which, when illuminated by said X-ray source forms a fiducial element image on said detector;
a control system which utilizes information obtained from said fiducial element image to synchronize the circular motions of said X-ray source and converter screen, such that said optical image representations of said X-ray cross-sectional laminographic images are formed at said stationary image plane, said control system comprising;
a sensor which monitors the position of said converter screen along said second circular pattern and transmits coordinates corresponding to the screen position; and
a look up table which receives said coordinates from said sensor and transmits corresponding signals to said steering device thus causing said motion of said X-ray source to be synchronized with said motion of said converter screen; and
a digital image processing system for analyzing said cross-sectional images of said solder connection, said image processing system comprising;
an image digitizer for receiving said electronic image signal from said camera and forming a digital representation of said image which corresponds to said X-ray cross-sectional image of said solder connection; and
a programmably-controlled computational section programmed to access predetermined regions of said digital image and to analyze said regions in accordance with a predetermined set of instructions for specific features indicative of particular types of solder defects.
3 Assignments
0 Petitions
Accused Products
Abstract
A tomographic inspection system wherein the electron beam of a microfocus X-ray tube is deflected in a circular scan pattern onto the tube anode in synchronization with a rotating detector that converts the X-ray shadowgraph into an optical image and derotates the image so as to be viewed and integrated in a stationary video camera. A computer system controls an automated positioning system that supports the item under inspection and moves successive areas of interest into view. In order to maintain high image quality, a computer system also controls the synchronization of the electron beam deflection and rotating optical system, making adjustments for inaccuracies of the mechanics of the system. The computer system can also operate under program control to automatically analyze data, measure characteristics of the item under inspection and make decisions regarding the acceptability of the item'"'"'s quality. The invention produces high resolution images in rapid succession so as to be suitable for use in conjunction with manufacturing production lines and capable of inspecting electronic devices, solder connections, printed wiring boards and other assemblies.
190 Citations
45 Claims
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1. A solder connection inspection device comprising:
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an X-ray source comprising; an electron source for producing a beam of electrons; an anode having a surface upon which said electron beam impinges; and an electrical steering device for deflecting said electron beam to different locations on said anode surface, said steering device capable of causing said electron beam to rotate about an axis and to trace a substantially circular path upon said anode surface thus causing said X-ray source to move in a first circular pattern, said first circular pattern defining a first plane; an X-ray detector for producing X-ray cross-sectional laminographic images of said solder connection, said detector positioned to receive X-rays produced by said X-ray source which have penetrated said solder connection, said X-ray detector comprising; a converter screen for producing an optical image corresponding to an X-ray image formed by said penetrating X-rays; means for moving said converter screen such that it rotates about said axis and travels along a substantially circular path defining a second circular pattern, said second circular pattern defining a second plane which is substantially parallel to said first plane; an optical derotation device for transmitting said optical image from said rotating converter screen to a stationary optical image plane; and a camera located at said stationary optical image plane for detecting said optical image, said camera having an electronic output which corresponds to said optical image; a fiducial element, which, when illuminated by said X-ray source forms a fiducial element image on said detector; a control system which utilizes information obtained from said fiducial element image to synchronize the circular motions of said X-ray source and converter screen, such that said optical image representations of said X-ray cross-sectional laminographic images are formed at said stationary image plane, said control system comprising; a sensor which monitors the position of said converter screen along said second circular pattern and transmits coordinates corresponding to the screen position; and a look up table which receives said coordinates from said sensor and transmits corresponding signals to said steering device thus causing said motion of said X-ray source to be synchronized with said motion of said converter screen; and a digital image processing system for analyzing said cross-sectional images of said solder connection, said image processing system comprising; an image digitizer for receiving said electronic image signal from said camera and forming a digital representation of said image which corresponds to said X-ray cross-sectional image of said solder connection; and a programmably-controlled computational section programmed to access predetermined regions of said digital image and to analyze said regions in accordance with a predetermined set of instructions for specific features indicative of particular types of solder defects. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A laminographic apparatus for inspecting an electrical connection comprising:
an imaging system for producing a cross-sectional image of said electrical connection, wherein said imaging system comprises; a source of penetrating radiation at a first location for generating said cross-sectional image of said electrical connection; and a detector at a second location for sensing the penetrating radiation representative of said cross-sectional image; a fiducial element, which, when illuminated by said source of penetrating radiation forms a fiducial element image on said detector; and a control system which coordinates the positions of said source of penetrating radiation and said detector utilizing information obtained from said fiducial element image. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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30. An apparatus for producing X-ray laminographs of an object comprising:
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an X-ray source wherein X-rays are produced by an electron beam impinging upon a target; an electrical steering device for deflecting said electron beam to different portions of said target thus moving the location, wherein said X-rays are produced by said X-ray source; an X-ray detector positioned to receive X-rays produced by said X-ray source; means for coordinating said X-ray detector position with said X-ray source motion such that a laminographic image is formed by said detector; a test object having a fiducial feature which forms an image of said fiducial feature on said X-ray detector when said test object is positioned between said X-ray source and said X-ray detector; and a feedback control system which utilizes information obtained from said image of said fiducial feature on said X-ray detector for synchronizing the motion of the X-ray source with the motion of the X-ray detector. - View Dependent Claims (31, 32, 33, 34, 35)
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36. A method of inspecting an electrical connection between electrical components mounted on a printed circuit board comprising the steps of:
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providing a source of transmissive energy; moving said source of transmissive energy; providing a detector for detecting said transmissive energy; moving said transmissive energy detector; positioning a fiducial element between said source of transmissive energy and said detector such that said fiducial element forms an image on said detector; controlling the motion of said transmissive energy with the motion of said detector with a feedback system that derives feedback alignment information from said fiducial element image on said detector; producing a cross-sectional image of said electrical connection utilizing said transmissive energy, wherein said cross-sectional image represents a peripheral plane adjacent to a surface of said printed circuit board; searching said cross-sectional image for predetermined characteristics; and analyzing said predetermined characteristics of said cross-sectional image to determine the quality of said electrical connection. - View Dependent Claims (37, 38, 39, 40, 41, 42, 43)
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44. A method of producing X-ray laminographs of an object comprising the steps of:
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providing a source of X-rays wherein X-rays are produced by an electron beam impinging upon a target; directing said electron beam to different portions of said target, thus moving a location wherein said X-rays are produced by said X-ray source; detecting X-rays produced by said X-ray source with an X-ray detector; moving the location of said X-ray detector; positioning a test object having a fiducial element between said X-ray source and said X-ray detector such that said test object fiducial element forms an image on said X-ray detector; and synchronizing the motion of said location of the production of said X-rays with the motion of said X-ray detector with a feedback system that derives feedback alignment information from said image of said test object fiducial element on said detector. - View Dependent Claims (45)
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Specification