Cognex Corporation

Yian Leng Chang

Nigel John Foster

Jane Alice Loizeaux

Ivan A Bachelder

Cyril C Marrion

Karen B Sarachik

A ball grid array inspection and location method and apparatus includes a raw feature finding processor which uses a feature finding algorithm to find ball features (irrespective of number) and generate a list of raw features as an X and Y location for each feature located. An angle estimation processor receives the list of raw features, a user estimated orientation angle, and ball-to-ball pitch information and determines an estimated grid angle. An on-grid check processor receives the estimated grid angle, the list of raw features and the ball-to-ball pitch information and produces a set or list of on-grid features in the form of a list X and Y translation parameters for each feature/ball found on-grid. A correspondence processor receives the list of on-grid features and model grid information and searches for correspondence between the two dimensional array of found grid features and the two dimensional array of model grid features to yield a direct mapping of respective two dimensional spatial relationships between model features and found features, which is used to determine the spatial relationship between model space and physical space in order to position/align balls of the device in physical space in accordance with model balls in model space. A least square fit is effected to refine position of the device in terms of its translation and rotation.

Method and apparatus for locating ball grid array packages from two-dimensional image data

The invention provides a method of locating an object within a client region, where the object has a plurality of portions. The method includes defining a full geometric model of the object; defining a plurality of geometric sub-models of the object; determining coarse candidate poses of the object within the region using an image of the region and the full geometric model of the object; determining the fine pose of each of a plurality of portions of the object using the coarse candidate poses of the object within the region, and at least some of said geometric sub-models, to provide a plurality of object portion fine poses within the region; and then determining the fine poses of the object within the region using said plurality of object portion fine poses of a plurality of portions of the object includes determining the coarse poses of each of a plurality of portions of the object, and using each coarse pose, determining the fine pose of each of the plurality of portions of the object. The invention allows geometric descriptions of objects (such as resistor chips, ball grid array packages, flip chips, etc.) to be specified in an arbitrary coordinate system, such as a physical (real world) coordinate system. This allows the same model to be used when locating the object within the physical world over a wide range of imaging conditions. The invention provides a powerful method for finding objects in images that is efficient in both memory space and computational time.

Object image search using sub-models

A method is provided for finding an image of an object having a concentric profile, wherein the concentric profile has an inner profile and an outer profile, and wherein the inner profile is in concentric relationship with the outer profile. In another general aspect of the invention, a method is provided for finding an image of an object having a concentric profile, the concentric profile having a plurality of constituent profiles, where each profiles of the plurality of constituent profiles scales independently in a fine search phase. The methods of the invention can find circular profiles of a nozzle that scale non-uniformly as well as that scale uniformly, and therefore can be used to find one or more rings or profiles of the image of a nozzle. Further, the methods of the invention can provide superior accuracy regarding the position of the nozzle for many applications. Moreover, certain aspects of the relationship between the inner and outer profiles of the image of the nozzle, such as a bent nozzle condition, can be effectively inspected by the methods of the invention.

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Sudbury, MA, United States of America

Yian Leng Chang