Circuit board contact contamination probe

• US 4,225,819 A
• Filed: 10/12/1978
• Issued: 09/30/1980
• Est. Priority Date: 10/12/1978
• Status: Expired due to Term

• Current Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Inventors: Grau, Thomas G., Tompsett, David E.
• Primary Examiner(s): Tokar, Michael J.
• Application Number:
  US05/950,725
• Time in Patent Office: 719 Days
• Field of Search: 324/72.5, 324/158 F, 324/158 P, 324/73 R, 324/73 PC
• US Class Current: 324/415
• CPC Class Codes: G01R 1/07328 for testing printed circuit boards
• CPC Class Codes: G01R 31/68 Testing of releasable connections, e.g. of terminals mounted on a printed circuit board

Abstract

Apparatus for detecting the presence of contamination films and foreign material on the conducting fingers of a circuit board. The apparatus includes a guide block assembly (11) designed to receive and momentarily hold a circuit board (100) and a spring biased hold down bar (25) for securely holding the circuit board in the guide block assembly. The apparatus further includes apparatus (23, 31) for use in positioning a plurality of probe assemblies (33) to simultaneously engage a pair of electrodes (330) with each one of the circuit board conducting fingers (101). A controller (43) enables switch apparatus (42) to selectively connect each pair of electrodes with electrical resistance measuring apparatus (50) to measure the resistance of any contamination film and foreign material appearing on a circuit board conducting finger between the electrodes of each electrode pair.

Claims

1. Apparatus for testing circuit boards (100), said apparatus having

circuitry (50) for measuring electrical resistance, and

testing apparatus (1) for coupling said measuring circuitry to conducting fingers (101) of a circuit board

CHARACTERIZED IN THAT

said testing apparatus comprises

a probe assembly (33) having electrodes (330) corresponding to each of the circuit board conducting fingers, said electrodes each comprising a needle member and a contact member,

guide apparatus (11) for receiving and holding the circuit board,

positioning apparatus (20, 21, 23, 24, 25, 26, 30, 31, 32) for securing the circuit board to said guide apparatus and for positioning said probe assembly to simultaneously engage said contact members of a pair of said electrodes with each circuit board conducting finger, and

coupling apparatus (40, 42, 43, 44-, 45-, 46-, 400, 401, 402) for sequentially connecting said needle members and said contact members of each of said pair of engaged electrodes with said measuring circuitry to measure the resistance of a contamination film and foreign material appearing on a conducting finger between said contact members of said engaged pair of electrodes.

2. The circuit board testing apparatus of claim 1

CHARACTERIZED IN THAT

said probe assembly comprises

a pair of electrodes (330),

plug apparatus (331, 332) for resiliently mounting pairs of said electrodes on said positioning apparatus, and

compliant spring members (333) for biasing said electrode contact members in engagement with the circuit board conducting fingers.

3. The circuit board testing apparatus of claim 2

CHARACTERIZED IN THAT

said guide apparatus comprises

a block assembly (11) arranged for receiving the circuit board and for aligning each conducting finger of the circuit board with respect to corresponding pairs of said electrodes.

4. The circuit board testing apparatus of claim 3

CHARACTERIZED IN THAT

said positioning apparatus comprises

resiliently biased apparatus (24, 25, 26) for retaining the circuit board in fixed relationship to said block assembly,

carrier apparatus (30, 31) for securely holding said plug apparatus and for moving said electrode pairs in and out of engagement with the circuit board conducting fingers, and

operating apparatus (20, 21, 22, 23, 32) coupled to said resiliently biased apparatus and to said carrier apparatus for enabling said resiliently biased apparatus to clamp the circuit board to said guide apparatus and for enabling said carrier apparatus to move said electrode pairs into engagement with the circuit board conducting fingers.

5. The circuit board testing apparatus of claim 4

CHARACTERIZED IN THAT

said coupling apparatus comprises

a pair of terminals (400) for each of said electrodes,

terminal mounting apparatus (40) for mounting said terminals on said carrier apparatus in fixed relationship to said electrode pairs,

wiring apparatus (401, 402) for connecting said terminal pairs with said electrodes, and

selectively coupling apparatus (42, 43, 44-, 45-, 46-) for sequentially connecting ones of said terminal pairs to said measuring circuitry.

6. The circuit board testing apparatus of claim 5 in which

said measuring circuitry comprises a voltage measuring device (502) and a current supply (501)

CHARACTERIZED IN THAT

said selectively coupling apparatus comprises

a controller (43), and

switch apparatus (42) controlled by said controller for selectively coupling the voltage measuring device and the current supply to said pairs of electrodes.

7. The circuit board testing apparatus of claim 6

CHARACTERIZED IN THAT

said wiring apparatus comprises

a first pair of conductors (401, 402) for connecting one electrode of said electrode pairs to a first pair of said terminals, and

a second pair of conductors (401, 402) for connecting another electrode of said electrode pairs to a second pair of said terminals.

8. The circuit board testing apparatus of claim 7

CHARACTERIZED IN THAT

each of said electrodes comprises

a needle member (3300) having an axial bore sized for receiving a first conductor and having a land on one end thereof for terminating a second conductor of one of said conductor pairs,

a contact member (3301) terminating said first conductor and affixed to an end of said needle member opposite said land end thereof for engaging a circuit board conducting finger, and

a collar member (3302) affixed to said needle member for restricting movement of said electrode in said plug apparatus.

9. The circuit board testing apparatus of claim 8

CHARACTERIZED IN THAT

said plug apparatus comprises

a plug assembly (331, 332) holding said collar member in a fixed relationship to said compliant spring member for mounting said pair of electrodes so that each electrode contact member may be positioned a distance apart along a centerline of a conducting finger and biased in engagement with the circuit board conducting finger.

10. Apparatus for testing circuit boards (100), said apparatus having

circuitry (50) for measuring electrical resistance, and

test apparatus (1) for coupling said measuring circuitry to conducting fingers (101) of a circuit board

CHARACTERIZED IN THAT

said testing apparatus comprises

a plurality of electrodes (330),

a probe assembly (33) for resiliently mounting a pair of said electrodes,

a block assembly (11) for receiving a circuit board and for aligning a conducting finger of the circuit board with said probe assembly,

resiliently biased retaining apparatus (24, 25, 26) for securely holding the circuit board in said block assembly,

carrier apparatus (30, 31) for securely holding said probe assembly,

operating apparatus (20, 21, 22, 23, 32) coupled to said resiliently biased retaining apparatus and said carrier apparatus for enabling said resiliently biased retaining apparatus to clamp the circuit board to said block assembly and for enabling said carrier apparatus to move said pair of electrodes into engagement with the circuit board conducting finger,

coupling apparatus (40, 42, 43, 44-, 45-, 46-, 400, 401, 402) for selectively connecting said pair of engaged electrodes with said measuring circuitry to measure the resistance of contamination films and foreign material appearing on the conducting finger between said pair of electrodes.

11. The circuit board testing apparatus of claim 10

CHARACTERIZED IN THAT

said probe assembly comprises

a plug assembly (331, 332, 333) for spring mounting said pair of electrodes on said carrier apparatus in a spaced-apart relationship along a centerline of a corresponding circuit board conducting finger.

12. The circuit board testing apparatus of claim 10

CHARACTERIZED IN THAT

said coupling apparatus comprises

a pair of first conductors (401) each coupled to one electrode of said pair of electrodes,

a pair of second conductors (402) each coupled to one electrode of said pair of electrodes,

switch apparatus (42) coupled to said first and second conductors for coupling said pair of electrodes to said measuring circuitry, and

control apparatus (43) for controlling said switch apparatus to select said pair of electrodes.

13. The circuit board testing apparatus of claim 12

CHARACTERIZED IN THAT

each of said electrodes comprises

a needle member (3300) having an axial bore sized for receiving one of said first conductors and having a land on one end thereof for terminating one of said second conductors, and

a contact member (3301) terminating said one first conductor and affixed to an end of said needle member opposite said land end thereof.

14. The circuit board testing apparatus of claim 13 in which

said measuring circuitry comprises a voltage measuring device (502) and a current supply (501).

CHARACTERIZED IN THAT

said switch apparatus comprises selectively coupling apparatus (421, 422, 423) controlled by said control apparatus for selectively connecting said current supply with said pair of first conductors and said voltage measuring device to said pair of second conductors.

15. Apparatus for testing circuit boards (100), said apparatus having

a constant current source (501),

a voltage measuring device (502), and

testing apparatus (1) for coupling said constant current source and said voltage measuring device to conducting fingers (101) of a circuit board

CHARACTERIZED IN THAT

said testing apparatus comprises

a plurality of electrodes (330) each of said electrodes having a needle member (3300) and a contact member (3301) affixed to an end of said needle member,

plug apparatus (331, 332, 333) for resiliently mounting pairs of said electrodes,

guide apparatus (11) for receiving a circuit board and for aligning each conducting finger of the circuit board with respect to a corresponding pair of said electrodes,

resiliently biased apparatus (24, 25, 26) for retaining the circuit board in a fixed relationship to said guide apparatus,

carrier apparatus (30, 31) for securely holding said plug apparatus and for moving pairs of said electrodes into and out of engagement with the circuit board conducting fingers,

operating apparatus (20, 21, 22, 23, 32) coupled to said resiliently biased apparatus and to said carrier apparatus for enabling said resiliently biased apparatus to clamp the circuit board to said guide apparatus and for enabling said carrier apparatus to simultaneously move said electrode contact members into engagement with the circuit board conducting fingers,

controller apparatus (43) for selecting ones of said pairs of contacts, and

coupling apparatus (40, 42, 44-, 45-, 46-, 400, 401, 402) coupled to said pairs of electrodes and controlled by said controller apparatus for selectively coupling said voltage measuring device to said electrode contact members and said constant current source to said electrode needle members to measure the resistance of contamination films and foreign matter appearing on the conducting fingers between a pair of said electrodes.

16. Apparatus for testing conducting fingers of a circuit board, said apparatus comprising

a plurality of electrodes each having a needle member and a contact member,

means for receiving and holding the circuit board,

means for mounting pairs of said electrodes,

means for positioning said mounting means to simultaneously engage said contact members of a pair of said electrodes with each circuit board conducting finger,

means for measuring electrical resistance, and

means for selectively connecting said electrical resistance measuring means to both said needle members and said contact members of each engaged pair of said electrodes to measure the resistance of contamination films and foreign material appearing on a circuit board conducting finger between said pair of electrode contact members.

17. A method of testing a circuit board with test apparatus comprising a probe assembly having electrodes comprised of a needle member and a contact member corresponding to each circuit board conducting finger, guide apparatus for receiving a circuit board, and electrical resistance measuring means, said method comprising the steps of

receiving and securing a circuit board to the guide apparatus,

positioning the probe assembly with respect to said secured circuit board to simultaneously engage the contact members of a pair of the electrodes with each circuit board conducting finger, and

selectively coupling the electrical resistance measuring means to the needle members and the contact members of each pair of said engaged electrodes to detect the presence and measure contamination films and foreign material appearing on a circuit board conducting finger between the contact members of an engaged pair of electrodes.