Computed tomography inspection of electronic devices
First Claim
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1. A method of inspecting mechanical/electrical interconnections between electronic components and conductors on a supporting circuit board, comprising the steps of:
- arranging radiation source means to radiate X-rays along and about a plane in a thin sheet through a sector defined by said source means and by an arc lying in said plane, centered on said source means, and located at a selected radius from said source means;
arranging X-ray detector means in said plane in a linear array coinciding with said arc to receive X-rays from said source means;
positioning said board so that said mechanical/electrical interconnections are intersected by said plane while operating said detector means to detect levels of radiation received from said source means during predetermined time intervals and to develop corresponding measurement data signals, and storing said measurement data signals;
rotating said board by a selected angle θ
around an axis normal to said plane;
repeating a selected number of times said steps of operating said detector means, storing said measurement data signals, and rotating said board;
processing said stored measurement data signals by computed tomography techniques to generate image data corresponding to an image of the density distribution of said mechanical/electrical interconnections intersected by said plane; and
comparing said image data to model data to develop defect data indicative of defects in said mechanical/electrical interconnections.
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Abstract
Computed tomography inspection apparatus and method of inspecting electronic devices and features of PCBs/PWBs, such as solder bonds, tracings and vias. The system scans radiation passed through the devices in thin slices and detects attenuated radiation from which it generates data representing slice images with high resolution. The detected image data are analyzed automatically by an image data analyzer which receives model data against which it compares and evaluates the detected image data.
53 Citations
9 Claims
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1. A method of inspecting mechanical/electrical interconnections between electronic components and conductors on a supporting circuit board, comprising the steps of:
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arranging radiation source means to radiate X-rays along and about a plane in a thin sheet through a sector defined by said source means and by an arc lying in said plane, centered on said source means, and located at a selected radius from said source means; arranging X-ray detector means in said plane in a linear array coinciding with said arc to receive X-rays from said source means; positioning said board so that said mechanical/electrical interconnections are intersected by said plane while operating said detector means to detect levels of radiation received from said source means during predetermined time intervals and to develop corresponding measurement data signals, and storing said measurement data signals; rotating said board by a selected angle θ
around an axis normal to said plane;repeating a selected number of times said steps of operating said detector means, storing said measurement data signals, and rotating said board; processing said stored measurement data signals by computed tomography techniques to generate image data corresponding to an image of the density distribution of said mechanical/electrical interconnections intersected by said plane; and comparing said image data to model data to develop defect data indicative of defects in said mechanical/electrical interconnections. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. Means for inspecting mechanical/electrical interconnections between electronic components and conductors of a supporting circuit board, comprising:
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radiation source means for radiating a thin sheet of X rays along a selected plane in a sector; spatial positioning means for positioning said circuit board with said interconnections in said plane and in said sector; data acquisition means for detecting levels of radiation received from said source means and for developing corresponding measurement data signals; scan control means for controlling operation of said source means, said positioning means and said data acquisition means, and including data storage means for receiving and storing said measurement data signals; image data generating means responsive to measurement data signals from said data storage means, and operative to generate image data corresponding to an image of the density distribution of said mechanical/electrical interconnections intersected by said plane; and image data analyzing means including database means for storing model data for said mechanical/electrical interconnections and including image data comparing means for comparing said image data to said model data to develop defect data indicative of defects in said mechanical/electrical interconnections. - View Dependent Claims (9)
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Specification