The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 15, 1991
Filed:
Dec. 21, 1989
Rajarshi Ray, Princeton, NJ (US);
AT&T Bell Laboratories, Murray Hill, NY (US);
Abstract
Defective or missing solder bumps (18) on a surface (13) of an article (10) such as a chip carrier are detected by first illuminating the surface with dark field illumination. Next, the image of the surface of the article is captured, typically by a television camera (30). The captured image is processed to detect defects by first creating a window (57) in the image about each group of solder bumps and then creating a bounding box (58) about each bump in each window. Each of a set of attributes, including: the number, size and location of the windows, the size location and number of boxes in each window, and the dimensions, shape and brightness of the image in each box, is measured. The value of each attribute is compared to a reference value, representing the value of the attribute when no defects are present. If the attribute differs by more than a predetermined tolerance for its reference value, than a particular defect is prevent. Verification of certain defects may be accomplished by repeating the above-described process using bright field illumination.