Tester channel to multiple IC terminals

• US 20040201391A1
• Filed: 04/27/2004
• Published: 10/14/2004
• Est. Priority Date: 05/08/2002
• Status: Active Grant

• Current Assignee: FormFactor Incorporated
• Original Assignee: FormFactor Incorporated
• Inventors: Miller, Charles A.
• Granted Patent: US 7,245,139 B2
• Time in Patent Office: Days
• US Class Current: 324/754
• CPC Class Codes: G01R 1/07378 using an intermediate adapter, e.g. space transformers G01R1/07371 takes precedence
• CPC Class Codes: G01R 3/00 Apparatus or processes specially adapted for the manufacture or maintenance of measuring instruments , e.g. of probe tips
• CPC Class Codes: G01R 31/2889 Interfaces, e.g. between probe and tester G01R31/31905 and G01R1/07364 take precedence
• CPC Class Codes: G01R 31/31723 Hardware for routing the test signal within the device under test to the circuits to be tested, e.g. multiplexer for multiple core testing, accessing internal nodes routing the test signal to or from the device under test G01R31/31926
• CPC Class Codes: G01R 31/318511 Wafer Test
• CPC Class Codes: G01R 31/31905 Interface with the device under test [DUT], e.g. arrangements between the test head and the DUT, mechanical aspects, fixture
• CPC Class Codes: G01R 31/31926 Routing signals to or from the device under test [DUT], e.g. switch matrix, pin multiplexing
• CPC Class Codes: Y10T 29/49082 Resistor making
• CPC Class Codes: Y10T 29/49126 Assembling bases
• CPC Class Codes: Y10T 29/4913 Assembling to base an electrical component, e.g., capacitor, etc.

Abstract

A probe card provides signal paths between integrated circuit (IC) tester channels and probes accessing input and output pads of ICs to be tested. When a single tester channel is to access multiple (N) IC pads, the probe card provides a branching path linking the channel to each of the N IC input pads. Each branch of the test signal distribution path includes a resistor for isolating the IC input pad accessed via that branch from all other branches of the path so that a fault on that IC pad does not substantially affect the voltage of signals appearing on any other IC pad. When a single tester channel is to monitor output signals produced at N IC pads, the resistance in each branch of the signal path linking the pads of the tester channel is uniquely sized to that the voltage of the input signal supplied to the tester channel is a function of the combination of logic states of the signals produced at the N IC pads. The tester channel measures the voltage of its input signal so that the logic state of the signals produced at each of the N IC output pads can be determined from the measured voltage.

Claims

1-21. -21. (canceled)

22. A probe assembly comprising:

a plurality of tester contacts disposed to connect to channels of a tester;

a plurality of device contact elements disposed to contact device terminals;

a first substrate comprising a plurality of first electrical connections;

a second substrate comprising a plurality of second electrical connections, wherein ones of said second electrical connections are electrically connected to ones of said first electrical connections to form signal paths from ones of said tester contacts to ones of said device contact elements; and

a resistor disposed on one of said first substrate or said second substrate, said resistor disposed within one of said signal paths.

23. The probe assembly of claim 22, wherein said device contact elements are disposed on said second substrate.

24. The probe assembly of claim 23, wherein:

said resistor is disposed on said second substrate, and

said second substrate is a space transformer.

25. The probe assembly of claim 24 further comprising a plurality of resistors disposed on said space transformer, and wherein:

a first of said signal paths electrically connects a first one of said tester contacts with a first set of two or more of said device contact elements, and

first ones of said plurality of resistors are disposed between said first one of said tester contacts and said first set of device contact elements.

26. The probe assembly of claim 25, wherein said first ones of said plurality of resistors provide electrical isolation between said device contact elements of said first set.

27. The probe assembly of claim 25 wherein:

a second of said signal paths electrically connects a second one of said tester contacts with a second set of two or more of said device contact elements, and

second ones of said plurality of resistors are disposed between said second one of said tester contacts and said second set of device contact elements.

28. The probe assembly of claim 27, wherein said second ones of said plurality of resistors provide electrical isolation between said device contact elements of said second set.

29. The probe assembly of claim 22 further comprising a third substrate comprising a plurality of third electrical connections, wherein ones of said third electrical connections electrically connect ones of said first electrical connections to ones of said second electrical connections.

30. The probe assembly of claim 29, wherein said third electrical connections comprise spring contacts.

31. The probe assembly of claim 30, wherein said spring contacts extend from opposite surfaces of said third substrate.

32. The probe assembly of claim 22, wherein said tester contacts are disposed on said first substrate.

33. The probe assembly of claim 32, wherein said resistor is disposed on said first substrate.

34. The probe assembly of claim 33 further comprising a plurality of resistors disposed on said first substrate, and wherein:

a first of said signal paths electrically connects a first one of said tester contacts with a first set of two or more of said device contact elements, and

first ones of said plurality of resistors are disposed between said first one of said tester contacts and said first set of device contact elements.

35. The probe assembly of claim 34, wherein said first ones of said plurality of resistors provide electrical isolation between said device contact elements of said first set.

36. The probe assembly of claim 34 wherein:

a second of said signal paths electrically connects a second one of said tester contacts with a second set of two or more of said device contact elements, and

second ones of said plurality of resistors are disposed between said second one of said tester contacts and said second set of device contact elements.

37. The probe assembly of claim 36, wherein said second ones of said plurality of resistors provide electrical isolation between said device contact elements of said second set.

38. The probe assembly of claim 22 further comprising a third substrate, wherein:

said device contact elements are disposed on said third substrate,

said second substrate comprises an interposer electrically connecting said first electrical connections to said device contact elements.

39. The probe assembly of claim 38, wherein said resistor is disposed on said interposer.

40. The probe assembly of claim 39 further comprising a plurality of resistors disposed on said interposer, and wherein:

a first of said signal paths electrically connects a first one of said tester contacts with a first set of two or more of said device contact elements, and

first ones of said plurality of resistors are disposed between said first one of said tester contacts and said first set of device contact elements.

41. The probe assembly of claim 40, wherein said first ones of said plurality of resistors provide electrical isolation between said device contact elements of said first set.

42. The probe assembly of claim 40 wherein:

a second of said signal paths electrically connects a second one of said tester contacts with a second set of two or more of said device contact elements, and

second ones of said plurality of resistors are disposed between said second one of said tester contacts and said second set of device contact elements.

43. The probe assembly of claim 42, wherein said second ones of said plurality of resistors provide electrical isolation between said device contact elements of said second set.

44. The probe assembly of claim 38, wherein said third electrical connections comprise spring contacts.

45. The probe assembly of claim 44, wherein said spring contacts extend from opposite surfaces of said interposer.

46. The probe assembly of claim 22 further comprising a plurality of resistors, each disposed within one of said signal paths, wherein at least one of said resistors is disposed on said first substrate and at least one of said resistors is disposed on said second substrate.

47. A method of making a probe assembly, said method comprising:

providing a plurality of electrically interconnected substrates, said substrates providing test signal paths from a plurality of tester channels to a plurality of device contact elements; and

disposing a resistor on one of said substrates in one of said test signal paths.

48. The method of claim 47, wherein:

one of said substrates comprises a space transformer,

said resistor is disposed on said space transformer, and

said device contact elements are disposed on said space transformer.

49. The method of claim 48 further comprising disposing a plurality of resistors on said space transformer, and wherein:

a first of said test signal paths electrically connects a first one of said tester contact with a first set of two or more of said device contact elements, and

first ones of said plurality of resistors are disposed between said first one of said tester contacts and said first set of device contacts.

50. The method of claim 49, wherein said first ones of said plurality of resistors provide electrical isolation between said device contact elements of said first set.

51. The method of claim 47, wherein said plurality of substrates comprise a probe board on which said tester contacts are disposed, and a probe substrate on which said device contact elements are disposed.

52. The method of claim 51 further comprising disposing a plurality of resistors on said probe board, and wherein:

a first of said test signal paths electrically connects a first one of said tester contact with a first set of two or more of said device contact elements, and

first ones of said plurality of resistors are disposed between said first one of said tester contacts and said first set of device contacts.

53. The method of claim 52, wherein said first ones of said plurality of resistors provide electrical isolation between said device contact elements of said first set.

54. The method of claim 53 further comprising disposing a plurality of resistors on said probe substrate, and wherein:

a first of said test signal paths electrically connects a first one of said tester contact with a first set of two or more of said device contact elements, and

first ones of said plurality of resistors are disposed between said first one of said tester contacts and said first set of device contacts.

55. The method of claim 54, wherein said first ones of said plurality of resistors provide electrical isolation between said device contact elements of said first set.

56. The method of claim 47, wherein said plurality of substrates comprise a probe board on which said tester contacts are disposed, a probe substrate on which said device contact elements are disposed, and an interposer disposed between said probe board and said probe substrate.

57. The method of claim 56 further comprising disposing a plurality of resistors on said interposer, and wherein:

a first of said test signal paths electrically connects a first one of said tester contact with a first set of two or more of said device contact elements, and

first ones of said plurality of resistors are disposed between said first one of said tester contacts and said first set of device contacts.

58. The method of claim 57, wherein said first ones of said plurality of resistors provide electrical isolation between said device contact elements of said first set.