Image analysis – Applications – Manufacturing or product inspection
Reexamination Certificate
1998-12-31
2002-08-27
Couso, Jose L. (Department: 2621)
Image analysis
Applications
Manufacturing or product inspection
C382S146000, C382S147000, C382S150000, C382S151000, C348S086000, C348S087000, C348S094000, C348S095000
Reexamination Certificate
active
06442291
ABSTRACT:
RESERVATION OF COPYRIGHT
The disclosure of this patent document contains material which is subject to copyright and/or mask work protection. The owner thereof has no objection to facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the U.S. Patent and Trademark Office patent file or records, but otherwise reserves all copyright and/or mask work rights whatsoever.
BACKGROUND OF THE INVENTION
The invention pertains to machine vision and, more particularly, to methods and articles of manufacture for inspecting ball grid array devices.
In automated assembly processes, such as those for assembling electronic circuit boards, it is important to determine the exact location of components prior to their placement for final assembly. For example, an assembly system must know the axial position and angular orientation of each component before placing its leads on appropriate solder pads of a printed circuit board.
Accuracy in positioning is ever more critical as the ratio of the size of the electronic components to the number of conductive leads increases. Such is the case with ball grid array (BGA) devices. These are small surface mounted devices containing tens or hundreds of conductive solder “bumps” arranged in regular patterns, e.g., rectangular arrays, “checker boards”, et cetera. Because the bumps are so closely spaced, accurate placement and alignment with solder pads on the circuit board is imperative.
The art suggests a few approaches to determining the orientation of BGA devices. These approaches are primarily binary techniques based on “blob” analysis of the solder bump array images. A drawback of the approaches is that, due to their binary nature, they are highly susceptible to lighting conditions or device-to-device variations. Moreover, they require that correspondence steps be performed to remove extraneous features, or noise. Those correspondence steps are typically very time consuming. While some approaches have attempted to reduce that time by limiting the correspondence step to a small subset of the bumps, those approaches suffer reduced accuracy.
An object of this invention is to provide improved methods for machine vision analysis and, particularly, improved methods for inspection of ball grid array devices.
A more particular object of this invention is to provide improved methods for BGA device inspection that permit the placement and orientation of those components to be readily and accurately determined.
Yet still another object of the invention is to provide such methods that can execute quickly, and without consumption of excessive resources, on a wide range of machine vision analysis equipment.
Still yet another object of the invention is to provide articles of manufacture comprising a computer usable medium embodying program code for carrying out improved such methods.
SUMMARY OF THE INVENTION
The foregoing objects are attained by the invention which provides, in one aspect, a method of inspecting an image to locate a ball grid array surface-mounted device characterized by an array of similar surface features, e.g., solder bumps. The method includes the steps of inspecting the image to find its surface features and to determine their locations (referred to herein as their “observed” locations); comparing expected locations of those features with the observed locations to identify missing surface features; reinspecting the image in the vicinity of apparently missing surface features to verify if the feature is really missing or to find those features and to determine their “observed” locations; and determining, from the observed locations of the surface features, the position and/or angle of the ball grid array surface-mounted device.
The invention can be used to determine the position and/or angle of ball grid array surface-mounted devices with surface features in any of many array configurations, e.g., a regular lattice, a checker board lattice, a reverse checker board lattice, a regular lattice with a holes.
In further aspects, the invention calls for finding the convex hull (i.e., perimeter) and hull angle (i.e., angular orientation of the perimeter) of the observed surface features. From those, a grid of expected locations of the surface features can be generated. Each of the observed locations can be assigned to the closest vertex on the grid. A score is then generated based on the number of surface features assigned to each vertex and the distance between each such vertex and its assigned surface features.
In a related aspect of the invention, the position and/or angle of the ball grid array surface-mounted device can be determined by performing a rigid body fit of the observed locations of surface features to the grid of expected locations.
These and other aspects of the invention are evident in the drawings and in the description that follows.
REFERENCES:
patent: 3816722 (1974-06-01), Sakoe et al.
patent: 3936800 (1976-02-01), Ejiri et al.
patent: 3967100 (1976-06-01), Shimomura
patent: 3968475 (1976-07-01), McMahon
patent: 3978326 (1976-08-01), Shimomura
patent: 4011403 (1977-03-01), Epstein et al.
patent: 4115702 (1978-09-01), Nopper
patent: 4183013 (1980-01-01), Agrawala et al.
patent: 4200861 (1980-04-01), Hubach et al.
patent: 4254400 (1981-03-01), Yoda et al.
patent: 4300164 (1981-11-01), Sacks
patent: 4385322 (1983-05-01), Hubach et al.
patent: 4441124 (1984-04-01), Heebner et al.
patent: 4441206 (1984-04-01), Kuniyoshi et al.
patent: 4534813 (1985-08-01), Williamson et al.
patent: 4541116 (1985-09-01), Lougheed
patent: 4570180 (1986-02-01), Baier et al.
patent: 4577344 (1986-03-01), Warren et al.
patent: 4581762 (1986-04-01), Lapidus et al.
patent: 4606065 (1986-08-01), Beg et al.
patent: 4617619 (1986-10-01), Gehly
patent: 4630306 (1986-12-01), West et al.
patent: 4688088 (1987-08-01), Hamazaki et al.
patent: 4706168 (1987-11-01), Weisner
patent: 4728195 (1988-03-01), Silver
patent: 4730260 (1988-03-01), Mori et al.
patent: 4731858 (1988-03-01), Grasmueller et al.
patent: 4736437 (1988-04-01), Sacks et al.
patent: 4742551 (1988-05-01), Deering
patent: 4764870 (1988-08-01), Haskin
patent: 4771469 (1988-09-01), Wittenburg
patent: 4783826 (1988-11-01), Koso et al.
patent: 4783828 (1988-11-01), Sadjadi
patent: 4783829 (1988-11-01), Miyakawa et al.
patent: 4831580 (1989-05-01), Yamada
patent: 4860374 (1989-08-01), Murakami et al.
patent: 4860375 (1989-08-01), McCubbrey et al.
patent: 4876457 (1989-10-01), Bose
patent: 4876728 (1989-10-01), Roth
patent: 4903218 (1990-02-01), Longo et al.
patent: 4907169 (1990-03-01), Lovoi
patent: 4914553 (1990-04-01), Hamada et al.
patent: 4922543 (1990-05-01), Ahlbom et al.
patent: 4926492 (1990-05-01), Tanaka et al.
patent: 4932065 (1990-06-01), Feldgajer
patent: 4953224 (1990-08-01), Ichinose et al.
patent: 4955062 (1990-09-01), Terui
patent: 4959898 (1990-10-01), Landman et al.
patent: 4962423 (1990-10-01), Yamada et al.
patent: 4972359 (1990-11-01), Silver et al.
patent: 4982438 (1991-01-01), Usami et al.
patent: 5012402 (1991-04-01), Akiyama
patent: 5046190 (1991-09-01), Daniel et al.
patent: 5054096 (1991-10-01), Beizer
patent: 5060276 (1991-10-01), Morris et al.
patent: 5063608 (1991-11-01), Siegel
patent: 5073958 (1991-12-01), Imme
patent: 5081656 (1992-01-01), Baker et al.
patent: 5081689 (1992-01-01), Meyer et al.
patent: 5086478 (1992-02-01), Kelly-Mahaffey et al.
patent: 5090576 (1992-02-01), Menten
patent: 5091861 (1992-02-01), Geller et al.
patent: 5091968 (1992-02-01), Higgins et al.
patent: 5093867 (1992-03-01), Hori et al.
patent: 5113565 (1992-05-01), Cipolla et al.
patent: 5115309 (1992-05-01), Hang
patent: 5119435 (1992-06-01), Berkin
patent: 5124622 (1992-06-01), Kawamura et al.
patent: 5133022 (1992-07-01), Weideman
patent: 5134575 (1992-07-01), Takagi
patent: 5143436 (1992-09-01), Baylor et al.
patent: 5145432 (1992-09-01), Midland et al.
patent: 5151951 (1992-09-01), Ueda et al.
patent: 5153925 (1992-10-01), Tanioka et al.
patent: 5159281 (1992-10-01), Hedstrom et al.
patent: 5159645 (1992-10-01), Kumagal
patent: 5168269 (1992-12-01), Harlan
Cognex Corporation
Couso Jose L.
Desire Gregory
Powsner David J.
LandOfFree
Machine vision methods and articles of manufacture for ball... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Machine vision methods and articles of manufacture for ball..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Machine vision methods and articles of manufacture for ball... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2878529