Optical inspection system

• US 7,200,259 B1
• Filed: 07/23/2000
• Issued: 04/03/2007
• Est. Priority Date: 07/25/1999
• Status: Expired due to Fees

• Current Assignee: Orbotech Limited (KLA Corporation)
• Original Assignee: Orbotech Limited (KLA Corporation)
• Inventors: Gilat-Bernshtein, Tally, Gold, Uri, Margalit, Tamir, Parente, Eli, Baranovsky, Edward
• Primary Examiner(s): CHAWAN, SHEELA C
• Application Number:
  US10/031,045
• Time in Patent Office: 2,445 Days
• Field of Search: 382/149, 382/151, 382/162, 382/167, 382/173, 382/181, 382/190, 382/199, 382/204, 382/232, 382/254, 382/257, 382/259, 382/299
• US Class Current: 382/149
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/30141 Printed circuit board [PCB]
• CPC Class Codes: G06T 7/0004 Industrial image inspection
• CPC Class Codes: G06T 7/12 Edge-based segmentation
• CPC Class Codes: G06T 7/155 involving morphological operators
• CPC Class Codes: G06V 20/695 Preprocessing, e.g. image segmentation

Abstract

This invention discloses a method for determining a location of a border in a color image, the image comprising at least two color populations, between a first color region associated with a first one of the two color populations and a second color region associated with a second one of the two color populations, both the first color region and the second color region being comprised in the color image, the method includes identifying an approximate border location between the first color region and the second color region, determining a plurality of candidate border locations between the first color region and the second color region, each of the plurality of candidate border locations being determined by applying a corresponding border location method chosen from among a plurality of border location methods, choosing one method from among the plurality of border location methods as a preferred method, and determining a location of a border between the first color region and the second color region by designating one of the plurality of candidate border locations associated with the preferred method as the border. An automated optical inspection device suitable for inspection of patterned articles is also disclosed.

Claims

1. An automated optical inspection device suitable for inspection of an article, comprising:

at least one detector providing a polychromatic image output of at least a portion of an article; and

processing circuitry receiving said polychromatic image output and providing edge detection to sub-pixel accuracy operative to distinguish borders among regions of different color wherein said processing circuitry is operative to distinguish a border between a first color region associated with a first color population and a second color region associated with a second color population by identifying an approximate border location between said first color region and said second color region and determining a location of a border between said first color region and said second color region by using a preferred method for identifying the location of a border between said first color population and said second color population.

2. An automated optical inspection device according to claim 1, wherein said polychromatic image output comprises a color image represented using a color image representation method having a plurality of color defining characteristics, and

each said preferred method is selected from a plurality of available methods, and

the plurality of available methods includes, for each color defining characteristic within the plurality of color defining characteristics, a method comprising performing an edge locating method in a component of the color image associated with said color defining characteristic.

3. An automated optical inspection device according to claim 2 and wherein the edge locating method comprises a sub-pixel contour-element locating method.

4. An automated optical inspection device suitable for inspection of an article, comprising:

at least one detector providing an image output of at least a portion of an article having at least three different regions, each of which regions is distinguished at least by an optical characteristic detectable by said detector; and

processing circuitry receiving said image output and providing edge detection to sub-pixel accuracy operative to distinguish borders of at least two of said at least three different regions, wherein said processing circuitry receives said image output and provides edge detection to sub-pixel accuracy operative to distinguish borders of said at least three different regions.

5. An automated optical inspection device according to claim 4 and wherein said processing circuitry provides mapping based at least partially on said image output which identifies materials in each of said different regions having a common border.

6. An automated optical inspection device suitable for inspection of an article comprising:

at least one detector providing a polychromatic image output of at least a portion of an article;

processing circuitry receiving said polychromatic image output and providing at least one of the following inspection functionalities;

segmentation of said polychromatic image into a segmented color image comprising a plurality of color regions each having one of a plurality of representative color possibilities;

binarization of the segmented color image into a binary image including regions and borders;

morphological erosion of the regions to provide a skeleton representing the regions; and

assignment of color regions to elements in the skeleton;

wherein the processing circuitry is operative to superimpose the skeleton and the segmented color image, and to assign data representative of regions to elements in the skeleton as a function of the superimposition.

7. An automated optical inspection device according to claim 6 and wherein the processing circuitry is operative to assign data representative of regions to elements in the skeleton the superimposed location of an element of the skeleton in a color region.

8. An automated optical inspection device suitable for inspection of an article, comprising:

at least one detector providing a polychromatic image output of at least a portion of an article, said article comprising an electrical circuit formed on a printed circuit board; and

processing circuitry receiving said polychromatic image output and providing a color image representing said article, the color image comprising a map which indicates borders between different regions of an article and identifies materials in each of said different regions having a common border said different regions including uncoated metal conductors, coated metal conductors, uncoated substrate, and coated substrate.

9. An automated optical inspection device according to claim 8 and wherein colors of portions of said map indicate materials at various regions of the article.

10. An automated optical inspection device according to claim 9 and wherein each color comprises a color chosen from among a predetermined possibility of colors.

11. An automated optical inspection device according to claim 8 and wherein said processing circuitry receives said image output and provides border indication to sub-pixel accuracy.

12. An automated optical inspection device according to claim 8 and wherein the electrical circuit comprises a ball grid array substrate.

13. An automated optical inspection device according to claim 8 and wherein the patterned article comprises a lead frame.

14. An automated optical inspection device according to claim 8 and wherein the different materials include different metals.

15. An automated optical inspection device according to claim 8 and wherein the patterned article comprises an etched metal substrate.

16. An automated optical inspection device according to claim 8 and wherein the patterned article comprises an engraved metal substrate.

17. An automated optical inspection device suitable for inspection of a patterned article, comprising:

at least one detector providing an image output of at least a portion of a patterned article comprising a plurality of materials having detectable borders between the plurality of materials said plurality of materials comprising at least three materials; and

processing circuitry receiving said image output and providing an inspection functionality comprising pattern analysis of image data relating to the borders to provide an indication of the presence of nicks and protrusions along said borders.

18. An automated optical inspection device according to claim 17 and wherein said patterned article comprises an electrical circuit.

19. An automated optical inspection device according to claim 18 and wherein said patterned article comprises a printed circuit board.

20. An automated optical inspection device according to claim 19 and wherein said printed circuit board comprises a ball grid array substrate.

21. An automated optical inspection device according to claim 18 and wherein said patterned article comprises a lead frame.

22. An automated optical inspection device according to claim 18 and wherein said patterned article comprises an etched metal substrate.

23. An automated optical inspection device according to claim 18 and wherein the patterned article comprises an engraved metal substrate.

24. An automated optical inspection device according to claim 17 and wherein said materials include materials from the following group:

uncoated metal conductors, coated material conductors, uncoated substrate, coated substrate.

25. An automated optical inspection device according to claim 17 and wherein said inspection functionality comprising pattern analysis includes:

identifying an ordered plurality of points along a border defined by the image data relating to the borders, each of said ordered plurality of points having at least one neighboring point in the ordered plurality of points;

determining a normal direction to the smooth curve at each of said ordered plurality of points; and

identifying a point of said ordered plurality of points as being part of an irregularity comprising one of a nick and a protrusion based, at least in part, on a local normal difference comprising a difference between the normal direction to the smooth curve at said point and a normal direction to the smooth curve at said at least one neighboring point of said point.

26. An automated optical inspection device suitable for inspection of an electrical circuit, comprising:

at least one detector providing an image output of at least a portion of an electrical circuit comprising multiple materials; and

processing circuitry receiving said image output and providing an output indication of the presence of at least one predetermined material, said processing circuitry providing an output indication of the presence of at least two materials out of a group of at least three predetermined materials.

27. An automated optical inspection device according to claim 26 and wherein said electrical circuit comprises a printed circuit board.

28. An automated optical inspection device according to claim 27 and wherein said printed circuit board comprises a ball grid array substrate.

29. An automated optical inspection device according to claim 28 and wherein said electrical circuit comprises a flat panel display substrate.

30. An automated optical inspection device according to claim 26 and wherein said processing circuitry provides an output indication of the presence of at least three predetermined materials.

31. An automated optical inspection device according to claim 26 and wherein said processing circuitry provides an output indication of the presence of copper.

32. An automated optical inspection device according to claim 26 and wherein said processing circuitry provides an output indication of the presence of gold.

33. An automated optical inspection device according to claim 26 and wherein said processing circuitry provides an output indication of the presence of a solder mask material.

34. An automated optical inspection device according to claim 26 and wherein said processing circuitry provides an output indication of the presence of silver.

35. An automated optical inspection device according to claim 26 and wherein said processing circuitry provides an output indication of the presence of photoresist residue.

36. An automated optical inspection device according to claim 26 and wherein said processing circuitry provides an output indication of the presence of oxidized metal.

37. An automated optical inspection device according to claim 26 and wherein said image output represents a portion of the electrical circuit as viewed through a translucent overlay.

38. An automated optical inspection device suitable for inspection of a patterned article, comprising:

at least one detector providing an image output of at least a portion of a patterned article through a translucent overlay at least partially covering the patterned article; and

processing circuitry receiving said image output and providing an output indication which is independent of the translucent overlay, said processing circuitry being operative to provide an indication of parts of the pattern covered by the translucent overlay and parts of the pattern not covered by the translucent overlay.

39. An automated inspection device according to claim 38 and wherein the patterned article comprises an electrical circuit.

40. An automated inspection device according to claim 39 and wherein the electrical circuit comprises a printed circuit board.

41. An automated inspection device according to claim 40 and wherein the printed circuit board comprises a ball grid array substrate.

42. Apparatus for automatically optically inspecting color images of objects, comprising:

a sensor operative to acquire polychromatic images of an object;

an image processor operative to process the polychromatic images and output a report indicating candidate defects and features chosen from among a predetermined set of features, and to provide an image of a region surrounding each said candidate defect and feature, said image processor including a binary image processor operative to process binary images generated from the polychromatic image, and a color image processor operative to process the polychromatic images.

43. Apparatus according to claim 42 and further comprising a morphological image processor operative to generate a skeleton map from a multicolor image derived from the polychromatic image.

44. An automated optical inspection device suitable for inspection of an article and comprising:

at least one detector providing an image output of at least a portion of an article having at least three different regions, each of which regions is distinguished at least by an optical characteristic detectable by said detector; and

processing circuitry receiving said image output and providing edge detection to sub-pixel accuracy operative to distinguish borders of at least two of said at least three different regions, wherein said processing circuitry provides mapping based at least partially on said image output which identifies materials in each of said different regions having a common border.

45. An automated optical inspection device suitable for inspection of an article comprising:

at least one detector providing a polychromatic image output of at least a portion of an article;

processing circuitry receiving said polychromatic image output and providing at least one of the following inspection functionalities;

segmentation of said polychromatic image into a segmented color image comprising a plurality of color regions each having one of a plurality of representative color possibilities;

binarization of the segmented color image into a binary image including regions and borders;

morphological erosion of the regions to provide a skeleton representing the regions; and

assignment of color regions to elements in the skeleton;

wherein the processing circuitry is operative to assign data representative of regions to elements in the skeleton the superimposed location of an element of the skeleton in a color region.

46. An automated optical inspection device suitable for inspection of an article comprising:

at least one detector providing a polychromatic image output of at least a portion of an article; and

processing circuitry receiving said polychromatic image output and providing a color image representing said article, the color image comprising a map which indicates borders between different regions of an article and identifies materials in each of said different regions having a common border, said different materials including different metals.

47. An automated optical inspection device suitable for inspection of a patterned article comprising:

at least one detector providing an image output of at least a portion of a patterned article comprising a plurality of materials having detectable borders between the plurality of materials, said materials include materials from the following group;

uncoated metal conductors, coated material conductors, uncoated substrate, coated substrate; and

processing circuitry receiving said image output and providing an inspection functionality comprising pattern analysis of image data relating to the borders to provide an indication of the presence of nicks and protrusions along said borders.

48. An automated optical inspection device suitable for inspection of a patterned article comprising:

at least one detector providing an image output of at least a portion of a patterned article comprising a plurality of materials having detectable borders between the plurality of materials; and

processing circuitry receiving said image output and providing an inspection functionality comprising pattern analysis of image data relating to the borders to provide an indication of the presence of nicks and protrusions along said borders, said inspection functionality comprising pattern analysis including;

identifying an ordered plurality of points along a border defined by the image data relating to the borders, each of said ordered plurality of points having at least one neighboring point in the ordered plurality of points;

determining a normal direction to the smooth curve at each of said ordered plurality of points; and

identifying a point of said ordered plurality of points as being part of an irregularity comprising one of a nick and a protrusion based, at least in part, on a local normal difference comprising a difference between the normal direction to the smooth curve at said point and a normal direction to the smooth curve at said at least one neighboring point of said point.