US5256975A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Manually-operated continuity/shorts test probe for bare interconnection packages
Assignee: Hewlett Packard Development Co LP
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Filing: 1992-06-01
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Granted: 1993-10-26
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Expires: 2012-06-01
Abstract
Abstract A hand-held test probe is employed which uses a capacitance measuring circuit to measure capacitance as the probe is scanned along a pattern of conductors (pads or pins) at a steady rate. The capacitance measurement is stored in a memory during the scan, then maximums are detected in the stored data, corresponding to the conductor pattern. If a particular conductor has a short or a break in continuity, its capacitance will be more or less than it should be. The detected maximums are compared with recorded values for a known-good printed wiring board for this scan pattern. If the comparison shows a difference greater than a selected threshold, an error is indicated for this pin location. The known-good is scanned in a "learn" mode, in which the capacitance values are stored for each scan, identified by scan number.
Inventors
- 👤 Richard I. Mellitz
- 👤 Ellsworth W. Stearns
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 06:32
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/28; G01R31/2801; G01R31/2805; G01R31/302; G01R31/312
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
210 words
A hand-held test device for detecting continuity or shorts in conductors of printed circuit boards or the like, comprising: a manually operated probe having a conductive point for scanning along one of a preselected set of patterns of said conductors in a regular rate; means connected to said point for measuring capacitance of each conductor touched and for producing an electrical output corresponding thereto; first memory means for storing said electrical output as a sequence of values, one value for each conductor touched; means for scanning said first memory and detecting maximums in the stored electrical outputs and for storing in a second memory an indication of said sequence of maximums; a third memory for storing a sequence of maximums of capacitance values for a known-good circuit board having said one of a preselected set of patterns of said conductors; a comparator responsive to the contents of said second memory and the contents of said third memory for comparing said indications of said maximums with said sequence of maximums and producing a error indication for differences; and said device including a scan memory for separately storing a sequence of maximums of capacitance values for each one of said preselected set of patterns of said conductors for said known-good circuit board.
Claim 2
Dependent Claim
210 words
A hand-held test device for detecting continuity or shorts in conductors of printed circuit boards or the like, comprising: a manually operated probe having a conductive point for scanning along one of a preselected set of patterns of said conductors in a regular rate; means connected to said point for measuring capacitance of each conductor touched and for producing an electrical output corresponding thereto; first memory means for storing said electrical output as a sequence of values, one value for each conductor touched; means for scanning said first memory and detecting maximums in the stored electrical outputs and for storing in a second memory an indication of said sequence of maximums; a third memory for storing a sequence of maximums of capacitance values for a known-good circuit board having said one of a preselected set of patterns of said conductors; a comparator responsive to the contents of said second memory and the contents of said third memory for comparing said indications of said maximums with said sequence of maximums and producing a error indication for differences; and said device including a scan memory for separately storing a sequence of maximums of capacitance values for each one of said preselected set of patterns of said conductors for said known-good circuit board.
Claim 3
Independent Claim
274 words
A method of operating a hand-held test device for detecting continuity or shorts in a set of patterns of conductors on a test circuit board, compared to a known-good circuit board having the same set of patterns of conductors, comprising the steps of: (a) manually scanning a hand-held probe having a conductive point separately along each one of said set of patterns of said conductors of said known-good circuit board at a regular rate; and, for each said step of separately manually scanning: (i) measuring capacitance of each conductor touched and producing an electrical output corresponding thereto; (ii) storing said electrical output as a sequence of values, one value for each conductor touched, then detecting maximums in the stored electrical outputs and storing an indication of said sequence of reference maximums; (ii) separately storing in a scan memory said sequence of reference maximums of capacitance values for each one of said set of patterns of said conductors for said known-good circuit board; (b) again manually scanning said hand-held probe separately along each one of said set of patterns of said conductors of said test circuit board at a regular rate; and, for each said step of again manually scanning: (i) measuring capacitance of each conductor touched and producing an electrical output corresponding thereto; (ii) storing said electrical output as a sequence of values, one value for each conductor touched, then detecting test maximums in the stored electrical outputs and storing an indication of said sequence of test maximums; (iii) detecting differences between said sequence of test maximums and one of said sequences of said reference maximums, and producing a error indication for detected differences.
Claim 4
Independent Claim
274 words
A method of operating a hand-held test device for detecting continuity or shorts in a set of patterns of conductors on a test circuit board, compared to a known-good circuit board having the same set of patterns of conductors, comprising the steps of: (a) manually scanning a hand-held probe having a conductive point separately along each one of said set of patterns of said conductors of said known-good circuit board at a regular rate; and, for each said step of separately manually scanning: (i) measuring capacitance of each conductor touched and producing an electrical output corresponding thereto; (ii) storing said electrical output as a sequence of values, one value for each conductor touched, then detecting maximums in the stored electrical outputs and storing an indication of said sequence of reference maximums; (ii) separately storing in a scan memory said sequence of reference maximums of capacitance values for each one of said set of patterns of said conductors for said known-good circuit board; (b) again manually scanning said hand-held probe separately along each one of said set of patterns of said conductors of said test circuit board at a regular rate; and, for each said step of again manually scanning: (i) measuring capacitance of each conductor touched and producing an electrical output corresponding thereto; (ii) storing said electrical output as a sequence of values, one value for each conductor touched, then detecting test maximums in the stored electrical outputs and storing an indication of said sequence of test maximums; (iii) detecting differences between said sequence of test maximums and one of said sequences of said reference maximums, and producing a error indication for detected differences.
Claim 5
Dependent Claim
21 words
A device according to claim 1 including means for selectively loading a sequence from said scan memory to said third memory.
Claim 6
Dependent Claim
33 words
A device according to claim 3 including means for storing with each said sequence a sensitivity value indicating a threshold for producing said error indication, said comparator being responsive to said sensitivity value.
Claim 7
Dependent Claim
23 words
A device according to claim 3 including means for invoking a "learn" mode to generate said sequence of maximums in said third memory.
Claim 8
Dependent Claim
26 words
A device according to claim 5 including means for generating an average value of each of said maximums in said third memory in said "learn" mode.
Claim 9
Dependent Claim
32 words
A device according to claim 6 including means for storing in said third memory a count of the number of scans in said "learn" mode for said selected one of said patterns.
Claim 10
Independent Claim
213 words
A method of operating a hand-held test device for detecting continuity or shorts in conductors of printed circuit boards or the like, comprising the steps of: manually scanning a hand-held probe having a conductive point along one of a preselected set of patterns of said conductors at a regular rate; measuring capacitance of each conductor touched and producing an electrical output corresponding thereto, by means connected to said point; storing said electrical output in first memory means as a sequence of values, one value for each conductor touched; scanning said first memory and detecting maximums in the stored electrical outputs and storing in a second memory an indication of said sequence of maximums; storing in a third memory a sequence of maximums of capacitance values for a known-good circuit board having said one of a preselected set of patterns of said conductors; comparing the contents of said second memory and the contents of said third memory for detecting differences between said indications of said maximums and said sequence of maximums, and producing a error indication for detected differences; and including the step of separately storing in a scan memory a sequence of maximums of capacitance values for each one of said preselected set of patterns of said conductors for said known-good circuit board.
Claim 11
Independent Claim
213 words
A method of operating a hand-held test device for detecting continuity or shorts in conductors of printed circuit boards or the like, comprising the steps of: manually scanning a hand-held probe having a conductive point along one of a preselected set of patterns of said conductors at a regular rate; measuring capacitance of each conductor touched and producing an electrical output corresponding thereto, by means connected to said point; storing said electrical output in first memory means as a sequence of values, one value for each conductor touched; scanning said first memory and detecting maximums in the stored electrical outputs and storing in a second memory an indication of said sequence of maximums; storing in a third memory a sequence of maximums of capacitance values for a known-good circuit board having said one of a preselected set of patterns of said conductors; comparing the contents of said second memory and the contents of said third memory for detecting differences between said indications of said maximums and said sequence of maximums, and producing a error indication for detected differences; and including the step of separately storing in a scan memory a sequence of maximums of capacitance values for each one of said preselected set of patterns of said conductors for said known-good circuit board.
Claim 12
Dependent Claim
29 words
A method according to claim 2 including the step of selectively loading one of said sequences of reference maximums to a temporary memory before said step of detecting differences.
Claim 13
Dependent Claim
22 words
A method according to claim 8 including the step of selectively loading a sequence from said scan memory to said third memory.
Claim 14
Dependent Claim
34 words
A method according to claim 10 including the step of storing with each said sequence a sensitivity value indicating a threshold for producing said error indication, said comparator being responsive to said sensitivity value.
Claim 15
Dependent Claim
24 words
A method according to claim 10 including the step of invoking a "learn" mode to generate said sequence of maximums in said third memory.
Claim 16
Dependent Claim
27 words
A method according to claim 12 including the step of generating an average value of each of said maximums in said third memory in said "learn" mode.
Claim 17
Dependent Claim
33 words
A method according to claim 13 including the step of storing in said third memory a count of the number of scans in said "learn" mode for said selected one of said patterns.
Claim 18
Dependent Claim
40 words
A method according to claim 9 including the step of storing with each said sequence of reference maximums a sensitivity value indicating a threshold for producing said error indication, said step of detecting differences being responsive to said sensitivity value.
Claim 19
Dependent Claim
21 words
A method according to claim 15 including the step of invoking a "learn" mode to generate said sequence of reference maximums.
Claim 20
Dependent Claim
24 words
A method according to claim 16 including the step of generating an average value of each of said reference maximums in said "learn" mode.
Claim 21
Dependent Claim
34 words
A method according to claim 17 including the step of storing a count of the number of scans in said "learn" mode for each one of said patterns of conductors of said test board.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-10-25 | 1997-04-26 | 1997-10-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-10-25 | 2001-04-26 | 2001-10-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-10-25 | 2005-04-26 | 2005-10-26 | $7700.00 | Window Closed / Lapsed |