Method and Device for Testing of Non-Componented Circuit Boards

• US 20080272792A1
• Filed: 01/26/2007
• Published: 11/06/2008
• Est. Priority Date: 02/08/2006
• Status: Active Grant

• Current Assignee: Xcerra Corporation (COHU Incorporated)
• Original Assignee: Atg Luther & Maelzer GmbH (Mycronic AB)
• Inventors: Rothaug, Uwe, Romanov, Victor
• Granted Patent: US 7,821,278 B2
• Time in Patent Office: Days
• US Class Current: 324/754
• 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 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 the following steps:

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 circuit board 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 deviations found.

19. 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.

20. Method according to claim 19,

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.

21. Method according to claim 20,

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

22. Method according to claim 20,

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

23. Method according to claim 1,

wherein with the aid of the deviations found, 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.

24. Method according to claim 22,

wherein with the aid of the deviations found, 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.

25. Method according to claim 1,

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

26. Method according to claim 24,

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

27. 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.

28. Method according to claim 26,

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.

29. Method according to claim 1,

wherein an electromechanical 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.

30. Method according to claim 28,

wherein an electromechanical 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.

31. Method according to claim 1,

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

32. Method according to claim 30,

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

33. 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.

34. Method according to claim 32,

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

35. Method according to claim 1,

wherein for the testing of circuit boards which have been made by means of several masks which define the form of the circuit board test points, the predetermined areas recorded by the imaging method cover at least one circuit board test point defined by each mask.

36. Method according to claim 34,

wherein for the testing of circuit boards which have been made by means of several masks which define the form of the circuit board test points, the predetermined areas recorded by the imaging method cover at least one circuit board test point defined by each mask.

37. Method according to claim 1,

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

38. Method according to claim 36,

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

2-18. -18. (canceled)

39. Device for the testing of non-componented circuit boards comprising

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

an evaluation unit

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

for 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

for determining deviations on the circuit board to be tested from the CAD data.

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

40. Device according to claim 39,

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

41. Device according to claim 39,

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

42. Device according to claim 39,

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.

43. Device according to claim 42,

wherein the sensor is a contact brush.

44. Device according to claim 39,

wherein the device is part of a finger tester.

45. Device according to claim 39,

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