Method and device for testing of non-componented circuit boards

• US 7,821,278 B2
• Filed: 01/26/2007
• Issued: 10/26/2010
• Est. Priority Date: 02/08/2006
• Status: Expired due to Fees

• Current Assignee: Xcerra Corporation (COHU Incorporated)
• Original Assignee: Atg Luther & Maelzer GmbH (Mycronic AB)
• Inventors: Rothaug, Uwe, Romanov, Victor
• Primary Examiner(s): Nguyen; Ha T.
• Assistant Examiner(s): BENITEZ ROSARIO, JOSHUA
• Application Number:
  US12/097,819
• Publication Number:
  US 20080272792A1
• Time in Patent Office: 1,369 Days
• Field of Search: 324/158.1, 324754-765, 3562374-2375
• US Class Current: 324/756.07
• CPC Class Codes: G01R 31/2805 Bare printed circuit boards
• CPC Class Codes: G01R 31/309 of printed or hybrid circuits or circuit substrates

Abstract

The invention relates to a method and a device for the testing of noncomponented circuit boards.

The method according to the invention is used to determine deviations of circuit board test points of a series of circuit boards from the CAD data relating to these circuit boards, by scanning the surface of the circuit board by an imaging method and subjecting this image to automatic image analysis so that it may be compared with the CAD data. The CAD data are then suitably corrected so that, with the aid of the corrected CAD data, the circuit board may be tested in a finger tester, with test fingers of the finger tester being controlled on the basis of the deviations found.

Claims

1. Method for the testing of non-componented circuit boards comprising:

recording of predetermined areas of a circuit board to be tested by an imaging process;

determining a form and/or type of circuit board test points lying in the predetermined areas by automatic image analysis;

comparing the determined form and/or type of the circuit board test points with corresponding computer aided design (CAD) data for the circuit board, and determining deviations of the form and/or type of circuit board test points to be tested from the CAD data, and

testing of the circuit board with a finger tester, in which test fingers of the finger tester are controlled on the basis of the determined deviations.

2. Method according to claim 1,

wherein in recording by the imaging process, image data of the predetermined areas of the circuit board to be tested are produced, and firstly in determining the form and/or type of the circuit board test points, image details are selected from these image data which in each case represent one or a predetermined group of circuit board test points, and then these image details are compared with preset patterns and the type of circuit board test points is determined with the aid of this pattern comparison.

3. Method according to claim 2,

wherein after determining the type of the circuit board test points, the form of the circuit board test points is determined through analysis of the relevant image details.

4. Method according to claim 1,

wherein the comparison of the image details with the patterns is made by a correlation method.

5. Method according to claim 3,

wherein the comparison of the image details with the patterns is made by a correlation method.

6. Method according to claim 5,

wherein with the aid of the determined deviations, the CAD data are corrected, and the corrected CAD data are used to create a test program for controlling the test fingers in testing the circuit board.

7. Method according to claim 6,

wherein with the aid of the determined deviations, a correction file for a test program is created and used for controlling the test fingers in testing the circuit board.

8. Method according to claim 7,

wherein an optical method, in which an optical sensor records the predetermined areas of the circuit board to be tested, is used as the imaging method.

9. Method according to claim 8,

wherein an electro-mechanical method, in which the surface of the circuit board to be tested is scanned electrically at a sufficiently high resolution to produce an image of the surface, is used as the imaging method.

10. Method according to claim 9,

wherein the recording of the predetermined areas is carried out in the finger tester.

11. Method according to claim 10,

wherein the recording of the predetermined areas is carried out in a device which is independent of the finger tester.

12. Method according to claim 11, further comprising:

making circuit boards by using several masks which define the form of the circuit board test points, and the predetermined areas recorded by the imaging method cover at least one circuit board test point defined by the masks.

13. Method according to claim 12,

wherein the predetermined areas recorded by the imaging method cover all circuit board test points.

14. Method according to claim 1,

wherein with the aid of the determined deviations, the CAD data are corrected, and the corrected CAD data are used to create a test program for controlling the test fingers in testing the circuit board.

15. Method according to claim 1,

wherein with the aid of the determined deviations, a correction file for a test program is created and used for controlling the test fingers in testing the circuit board.

16. Method according to claim 1,

wherein an optical method, in which an optical sensor records the predetermined areas of the circuit board to be tested, is used as the imaging method.

17. Method according to claim 1,

wherein an electro-mechanical method, in which the surface of the circuit board to be tested is scanned electrically at a sufficiently high resolution to produce an image of the surface, is used as the imaging method.

18. Method according to claim 1,

wherein the recording of the predetermined areas is carried out in the finger tester.

19. Method according to claim 1,

wherein the recording of the predetermined areas is carried out in a device which is independent of the finger tester.

20. Method according to claim 1, further comprising:

making circuit boards by using several masks which define the form of the circuit board test points, and the predetermined areas recorded by the imaging method cover at least one circuit board test point defined by the masks.

21. Method according to claim 1,

wherein the predetermined areas recorded by the imaging method cover all circuit board test points.

22. Method according to claim 1,

wherein the recording of the predetermined areas by automatic image analysis, determining of the form and/or type of circuit test point, and comparing the determined form and/or type with corresponding CAD data, are completed before tests of the circuit board test points are conducted with test fingers.

23. Method according to claim 1,

wherein determining the form and/or type of the circuit board test points by automatic image analysis also includes determining the size of the circuit board test points.

24. Method according to claim 1,

wherein recordings of image details are compared to preset patterns and multiple circuit board test points are identified simultaneously.

25. Method according to claim 1,

wherein determining the form and/or type of the circuit board test points by automatic image analysis includes determining whether the form and/or type of the circuit board test point is a pad field or plated-through hole.

26. Method according to claim 1,

wherein determining the form and/or type of the circuit board test points by automatic image analysis also includes determining whether the form and/or type of the circuit board test point is rectangular or circular.

27. Device for testing of non-componented circuit boards comprising

a unit recording predetermined areas of a circuit board to be tested by an imaging process, and

an evaluation unit

determining the form and/or type of circuit board test points lying in the predetermined areas by means of automatic image analysis,

comparing of the determined form and/or the determined type of the circuit board test points with corresponding CAD data for the circuit board, and

determining deviations on the form and/or type of circuit board test points to be tested from the CAD data, and

test fingers which are controlled on the basis of the deviations found by the evaluation unit.

28. Device according to claim 27,

wherein the evaluation unit performs a correlation on the CAD data.

29. Device according to claim 27,

wherein the unit for recording predetermined areas of a circuit board to be tested using an imaging method has an optical sensor.

30. Device according to claim 27,

wherein the unit for recording predetermined areas of a circuit board to be tested using an imaging method has an electrical sensor with several contact elements.

31. Device according to claim 30,

wherein the sensor is a contact brush.

32. Device according to claim 27,

wherein the device is part of a finger tester.

33. Device according to claim 27,

wherein the device is equipped with a control unit for controlling the test fingers.

34. Device according to claim 27,

wherein determining the form and/or type of the circuit board test points by automatic image analysis also includes determining the size of the circuit board test points.

35. Device according to claim 27,

wherein determining the form and/or type of the circuit board test points by automatic image analysis includes determining whether the form and/or type of the circuit board test point is a pad field or plated-through hole.

36. Device according to claim 27,

wherein determining the form and/or type of the circuit board test points by automatic image analysis also includes determining whether the form and/or type of the circuit board test point is rectangular or circular.