Electrical assembly testing using robotic positioning of probes

• US 5,469,064 A
• Filed: 09/15/1993
• Issued: 11/21/1995
• Est. Priority Date: 01/14/1992
• Status: Expired due to Fees

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Crook, David T., Schlotzhauer, Ed. O., Kerschner, Ronald K., Heumann, John M., McDermid, John E.
• Primary Examiner(s): Wieder, Kenneth A.
• Assistant Examiner(s): BROWN, GLENN WARNER
• Application Number:
  US08/122,031
• Time in Patent Office: 797 Days
• Field of Search: 324/500, 324/519, 324/522, 324/523, 324/525, 324/537, 324/690, 324/718, 324/724, 324/754, 324/761, 324/758
• US Class Current: 324/537
• CPC Class Codes: F02P 2017/006 using a capacitive sensor
• CPC Class Codes: G01R 1/07 Non contact-making probes
• CPC Class Codes: G01R 31/2806 Apparatus therefor, e.g. test stations, drivers, analysers, conveyors G01R31/2805, G01R31/281, G01R31/2818 take precedence
• CPC Class Codes: G01R 31/2886 Features relating to contacting the IC under test, e.g. probe heads; chucks G01R31/2865 takes precedence, test connections, e.g. test sockets, or probes per se, G01R1/04 or G01R1/06
• CPC Class Codes: G01R 31/3025 Wireless interface with the DUT
• CPC Class Codes: G01R 31/312 by capacitive methods

Abstract

The present invention is an improved printed circuit board test system in which test probes are positioned to electronically engage a selected device or printed circuit board section on a printed circuit board for testing the printed circuit board for manufacturing defects. The printed circuit board test system uses a bed-of-nails test fixture to ground and excite predetermined sites on a first side of the printed circuit board and a robot to mechanically position test probe(s) at selected test sites on a second side of the printed circuit board. A controller is used to control the movement of the robotic tester and the selection of spring probes in the bed-of-nails fixture to be exited, grounded or measured.

Claims

1. A test system for testing an electronic assembly having a first side and a second side, said test system comprising:

an electrical test means;

a bed-of-nails fixture means with mounting means for fixing said first side of said electronic assembly at a predetermined position adjacent said bed-of-nails fixture, said bed-of-nails fixture means having a plurality of test probes arranged to spatially correspond with predetermined electrical test access sites on said first side of said electronic assembly;

at least two test probes for obtaining electrical test access at predetermined sites on said second side of said electronic assembly;

robotic test probe positioning means with at least two test probe heads for individually positioning said at least one two test probes in an X-direction, a Y-direction and a Z-direction spatially adjacent said second side of said electronic assembly, said robotic test probe positioning means repositioning said at least two test probes via said at least two test probe heads during testing relative to each of said predetermined test access sites on said second side of said electronic assembly; and

a controller for implementing and controlling the testing of said electronic assembly, wherein after a user selects a test to be run said controller implements said test and instructs said robotic test probe positioning means to individually move said at least two test probes to selected sites adjacent said second side of said electronic assembly, said controller further instructs said electrical test means to measure, excite and ground selected sites on said first side of said electronic assembly via said bed-of-nails fixture means and to measure, excite and ground selected sites on said second side of said electronic assembly via said at least two test probes.

2. The test system according to claim 1, wherein said at least two test probes comprise at least one non-contact test probe.

3. The test system according to claim 2, wherein said plurality of test probes comprises a plurality of spring probes.

4. The test system according to claim 3, wherein said at least one non-contact test probe capacitively couples to a predetermined site on said second side of said electronic assembly.

5. The test system according to claim 2, wherein said at least two robotic test probe positioning means positions said at least one non-contact test probe directly over selected electrical components or test points on said electronic assembly.

6. The test system according to claim 1 further comprising:

a connector means electrically coupled to said electronic assembly, wherein said connector means provides further electronic test access to said electronic assembly.

7. The test system according to claim 1 further comprising:

a camera coupled to said robotic test probe positioning means, whereby said camera aligns said robotic test probe positioning means with said electronic assembly to compensate for misalignment.

8. A test system for testing an electronic assembly having a first side and a second side, said test system comprising:

an electrical test means;

a bed-of-nails fixture means with mounting means for fixing said first side of said electronic assembly at a predetermined position adjacent said bed-of-nails fixture, said bed-of-nails fixture means having a plurality of test probes arranged to spatially correspond with predetermined electrical test access sites on said first side of said electronic assembly;

at least one test probe for obtaining electrical test access at predetermined sites on said second side of said electronic assembly;

robotic test probe positioning means for positioning said at least one test probe in an X-direction, a Y-direction and a Z-direction spatially adjacent said second side of said electronic assembly, wherein said robotic test probe positioning means further comprises a multi-probe turret for holding a plurality of different types of test probes; and

a controller for implementing and controlling the testing of said electronic assembly, wherein after a user selects a test to be run said controller implements said test and instructs said robotic test probe positioning means to move said at least one test probe to selected sites adjacent said second side of said electronic assembly, said controller further instructs said electrical test means to measure, excite and ground selected sites on said first side of said electronic assembly via said bed-of-nails fixture means and to measure, excite and ground selected sites on said second side of said electronic assembly via said at least one test probe.

9. The test system according to claim 8, wherein said controller selects an appropriate test probe from said plurality of different types of test probes when a test is selected, whereby said controller instructs said robotic test probe positioning means to rotate said multi-probe turret to said appropriate test probe.

10. A test system for testing an electronic assembly having a first side and a second side, said test system comprising:

an electrical test means;

a bed-of-nails fixture means with mounting means for fixing said first side of said electronic assembly at a predetermined position adjacent said bed-of-nails fixture, said bed-of-nails fixture means having a plurality of test probes arranged to spatially correspond with predetermined electrical test access sites on said first side of said electronic assembly;

at least one test probe for obtaining electrical test access at predetermined sites on said second side of said electronic assembly;

robotic test probe positioning means for positioning said at least one test probe in an X-direction, a Y-direction and a Z-direction spatially adjacent said second side of said electronic assembly;

a controller for implementing and controlling the testing of said electronic assembly, wherein after a user selects a test to be run said controller implements said test and instructs said robotic test probe positioning means to move said at least one test probe to selected sites adjacent said second side of said electronic assembly, said controller further instructs said electrical test means to measure, excite and ground selected sites on said first side of said electronic assembly via said bed-of-nails fixture means and to measure, excite and ground selected sites on said second side of said electronic assembly via said at least one test probe; and

a carousel of different types of test probes positioned within said robotic test probe positioning means range of travel, whereby said robotic test probe positioning means switches test probes when instructed to do so by said controller.

11. A test system for testing an electronic assembly having a first side and a second side, said test system comprising:

an electrical test means;

a bed-of-nails fixture means with mounting means for fixing said first side of said electronic assembly at a predetermined position adjacent said bed-of-nails fixture, said bed-of-nails fixture means having a plurality of test probes arranged to spatially correspond with predetermined electrical test access sites on said first side of said electronic assembly;

at least one test probe for obtaining electrical test access at predetermined sites on said second side of said electronic assembly;

robotic test probe positioning means for positioning said at least one test probe in an X-direction, a Y-direction and a Z-direction spatially adjacent said second side of said electronic assembly;

a controller for implementing and controlling the testing of said electronic assembly, wherein after a user selects a test to be run said controller implements said test and instructs said robotic test probe positioning means to move said at least one test probe to selected sites adjacent said second side of said electronic assembly, said controller further instructs said electrical test means to measure, excite and ground selected sites on said first side of said electronic assembly via said bed-of-nails fixture means and to measure, excite and ground selected sites on said second side of said electronic assembly via said at least one test probe; and

a camera coupled to said robotic test probe positioning means, whereby said camera aligns said robotic test probe positioning means with said electronic assembly to compensate for misalignment, wherein said camera performs optical inspections of said electronic assembly to check for defects in said electronic assembly.

12. A test system for testing an electronic assembly having a first side and a second side, said test system comprising:

an electrical test means;

a bed-of-nails fixture means with mounting means for fixing said first side of said electronic assembly at a predetermined position adjacent said bed-of-nails fixture, said bed-of-nails fixture means having a plurality of test probes arranged to spatially correspond with predetermined electrical test access sites on said first side of said electronic assembly;

at least one test probe for obtaining electrical test access at predetermined sites on said second side of said electronic assembly;

robotic test probe positioning means for positioning said at least one test probe in an X-direction, a Y-direction and a Z-direction spatially adjacent said second side of said electronic assembly;

a controller for implementing and controlling the testing of said electronic assembly, wherein after a user selects a test to be run said controller implements said test and instructs said robotic test probe positioning means to move said at least one test probe to selected sites adjacent said second side of said electronic assembly, said controller further instructs said electrical test means to measure, excite and ground selected sites on said first side of said electronic assembly via said bed-of-nails fixture means and to measure, excite and ground selected sites on said second side of said electronic assembly via said at least one test probe; and

a camera coupled to said robotic test probe positioning means, whereby said camera aligns said robotic test probe positioning means with said electronic assembly to compensate for misalignment, wherein said camera also provides vision for positioning of said at least one test probe over fine pitch elements on said second side of said electronic assembly, wherein said positioning of said at least one test probe is performed by said robotic test probe positioning means.

13. A test system for testing an electronic assembly having a plurality of electronic components, said electronic assembly having a first side and a second side, said test system comprising:

an electrical test means;

a connector means coupled to said electronic assembly for providing electrical access to said electronic assembly;

a bed-of-nails fixture with mounting means for fixing said first side of said electronic assembly at a predetermined position adjacent said bed-of-nails fixture, said bed-of-nails fixture having a plurality of test probes arranged to spatially correspond with predetermined measurement, excitation and ground sites on said first side of said electronic assembly;

at least two test probes for measuring, exciting or grounding predetermined sites on said second side of said electronic assembly;

robotic test probe positioning means with at least two test probe heads for individually positioning said at least two test probes at predetermined positions in an X-direction, a Y-direction and a Z-direction spatially adjacent said second side of said electronic assembly; and

a controller for implementing and controlling the testing of said electronic assembly, whereby after a user selects a test to be run said controller instructs said robotic test probe positioning means to individually move said at least two test probes to selected sites adjacent said second side of said electronic assembly, said controller further instructs said electrical test means to measure, excite and ground selected sites on said first side of said electronic assembly via said bed-of-nails fixture and to measure, excite and ground selected sites on said second side of said electronic assembly via said at least two test probes.

14. A test system according to claim 13 further comprising:

a camera coupled to said robotic test probe positioning means for aligning said robotic test probe positioning means with fiducials on said electronic assembly, said camera also provides vision for positioning of said at least two test probes over fine pitch elements on said second side of said electronic assembly, wherein said positioning of said at least two test probes is performed by said robotic test probes positioning means.

15. A test system for testing an electronic assembly having a first side and a second side, said test system comprising:

a first set of at least two test probes for measuring, exciting or grounding predetermined sites on said first side of said electronic assembly;

a first robotic test probe positioning means with at least two test probe heads for individually positioning said at least two test probes of said first set of test probes at predetermined positions in an X-direction, a Y-direction and a Z-direction spatially adjacent said first side of said electronic assembly;

a second set of at least two test probes for measuring, exciting or grounding predetermined sites on said second side of said electronic assembly;

a second robotic test probe positioning means with at least two test probe heads for individually positioning said at least two test probes of said second set of test probes at predetermined positions in an X-direction, a Y-direction and a Z-direction spatially adjacent said second side of said electronic assembly; and

a controller for implementing and controlling the testing of said electronic assembly, whereby after a user selects a test to be run said controller instructs said first robotic test probe positioning means to move said at least two test probes of said first set of test probes spatially adjacent to selected sites on said first side of said electronic assembly and to measure, excite or ground selected sites on said first side of said electronic assembly, said controller further instructs said second robotic test probe positioning means to move said at least two test probes of said second set of test probes spatially adjacent to selected sites on said second side of said electronic assembly and to measure, excite or ground selected sites on said second side of said electronic assembly.

16. A test system according to claim 15 further comprising a connector means coupled to said electronic assembly for providing electrical access to said electronic assembly.

17. A method of testing an electronic assembly for defects, said electronic assembly having a first side and a second side, such that when an electrical signal is supplied to a predetermined site on said electronic assembly, a measuring means measures a parameter of a corresponding signal detected by a test probe at a different predetermined site on said electronic assembly and indicates an error if the measured parameter is not within predetermined limits, said method comprising the steps of:

(a) supplying ground to predetermined sites on said first side of said electronic assembly with a plurality of test probes on a bed-of-nails test fixture;

(b) supplying a signal to at least one predetermined site on said first side of said electronic assembly with at least one test probe on said bed-of-nails test fixture;

(c) individually, robotically positioning a test probe with a test probe head to a predetermined site spatially adjacent to a predetermined site on said second side of said electronic assembly;

(d) sensing a signal with said test probe at said predetermined site spatially adjacent to a predetermined site on said second side of said electronic assembly; and

(e) measuring said sensed signal with a measuring system to determine if the signal falls within predetermined limits.

18. The method according to claim 17, said method comprising the initial steps of:

robotically positioning a test probe spatially over each of said plurality of test probes in said bed-of-nails test fixture;

correspondingly exciting each of said plurality of test probes in said bed-of-nails test fixture;

sensing a signal at each test probe in said bed-of-nails test fixture as each test probe is excited; and

measuring said sensed signal to determine if each test probe in said bed-of-nails test fixture is properly wired.

19. The method according to claim 17, wherein said robotically positioned test probe is a non-contact test probe.

20. The method according to claim 17, said method comprising the further step of:

performing back trace with a second test probe to determine the location of any faulty components or wiring, said back trace being performed whenever an error is detected by said measuring system.

21. A method of testing for defects in an electronic assembly having a first side and a second side, such that when an electrical signal is supplied to a predetermined site on said electronic assembly, a measuring means measures a parameter of a corresponding signal detected by a test probe at a different predetermined site on said electronic assembly and indicates an error if the measured parameter is not within predetermined limits, said method comprising the steps of:

(a) supplying electrical test access to a plurality of predetermined sites on said first side of said electronic assembly with a plurality of test probes in a bed-of-nails test fixture;

(b) supplying an electrical signal to a predetermined site on said second side of said electronic assembly with a test probe individually robotically positioned with a test probe head over said predetermined site;

(c) sensing a signal with a predetermined test probe of said plurality of test probes in said bed-of-nails test fixture at a predetermined site of said plurality of sites on said first side of said electronic assembly; and

(d) measuring said sensed signal with a measuring system to determine if the signal falls within predetermined limits.