Methods and apparatuses for in-line solder paste inspection
AssigneeCognex Corporation
InventorJuha Koljonen
Life of this patent
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Abstract
Inspection of solder paste on a printed circuit board using a histogram of an image before printing (pre-application image) to normalize an image after printing of the printed circuit board (post-application image) is described. Existing lighting and optics used for alignment of the screen-printing stencil to the printed circuit board are used for the solder paste inspection.
Claims28
A method of identifying a first region within a second-state image, the method comprising:
- providing a first-state image having a first region;
- calculating at least one first-state characteristic representative of at least the first region of the first-state image;
- acquiring the second-state image having the first region and the at least one other region, the second-state image differing from the first-state image;
- calculating a second-state histogram representative of the first region and the at least one other region within the second-state image;
- augmenting the second-state histogram using the at least one first-state characteristic by enhancing the representation of the first region relative to at least one other region to provide an augmented second-state histogram;
- and
- identifying the first region within the second-state image using the augmented second-state histogram.
A method of identifying a first region within a second-state image using at least one first-state characteristic of a first-state image, the method comprising:
- providing a model representative of characteristics and position of the first region;
- identifying a first region within the first-state image using the model;
- calculating the at least one first-state characteristic of the first region once identified;
- acquiring the second-state image, the second-state image differing from the first-state image and having a unknown number of other regions;
- calculating a second-state histogram representative of the first region and the unknown number of other regions within the second-state image;
- augmenting the second-state histogram using the at least one first-state characteristic to provide an augmented second-state histogram that substantially eliminates values in the second-state histogram representative of substantially all but the first region and a second region;
- and
- calculating a threshold of the augmented second-state histogram so as to substantially identify the first region relative to the second region.
A method of using a vision system to identify pad regions of a substrate within a post-paste application image, the method comprising:
- providing pre-application image data representative of characteristics of the pad regions before application of paste;
- calculating a pre-paste application histogram of the pad regions before the paste is applied on the substrate using the pre-application image data;
- acquiring a post-paste application image of the substrate after the paste is applied on the substrate;
- calculating a post-paste application histogram of the post-paste application image representative of the pad regions, substrate regions and applied-paste regions;
- augmenting the post-paste application histogram using the pre-paste application histogram by changing the representation of the pad region relative to at least one other region to provide an augmented post-paste application histogram;
- and
- identifying the pad regions within the post-paste application image using the augmented post-paste application histogram.
Dependencies are inferred from the claim text.