Patent US4644259A successfully refreshed from Google Patents.
US4644259A
Expired / Lapsed
US
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Nondestructive testing of multilayer ceramic capacitors
Assignee: Philips North America LLC
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Filing: 1984-10-31
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Granted: 1987-02-17
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Expires: 2004-10-31
Abstract
Abstract A method for nondestructive testing of multilayer ceramic capacitors exhibiting piezoelectric effects only during poling by a bias voltage to determine the presence or absence of delaminations. The capacitor is inserted in an impedance bridge, a bias voltage of 1 to 2.5 times the rated voltage is applied and the impedance is measured as a function of frequency. A lower than expected impedance indicates a defective capacitor.
Inventors
- 👤 Otmar H. Boser
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 03:51
CPC Classifications
G; G01; G01R; G01R27/00; G01R27/02; G01R27/26; G01R27/2605; G01R31/00; G01R31/50; G01R31/64
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
134 words
A method for non-destructive testing of multilayer ceramic capacitors exhibiting piezoelectric effects only during poling by a bias voltage to determine the presence of delamination of the layers and non-visible cracks in said capacitors comprising the steps of: determining the resonance frequency and the impedance at resonance for a specific size and type of capacitor; inserting sequentially a number of capacitors of said specific type and size in an impedance bridge; applying a bias voltage to each of said capacitors sequentially, said voltage being between 1 and 2.5 times the rated voltage of said capacitors; measuring sequentially the impedance of each of said capacitors as a function of frequency; comparing said impedances to an expected impedance, such that capacitors having shifts to lower than expected impedance values at resonance frequencies are rejected as defective.
Claim 2
Independent Claim
134 words
A method for non-destructive testing of multilayer ceramic capacitors exhibiting piezoelectric effects only during poling by a bias voltage to determine the presence of delamination of the layers and non-visible cracks in said capacitors comprising the steps of: determining the resonance frequency and the impedance at resonance for a specific size and type of capacitor; inserting sequentially a number of capacitors of said specific type and size in an impedance bridge; applying a bias voltage to each of said capacitors sequentially, said voltage being between 1 and 2.5 times the rated voltage of said capacitors; measuring sequentially the impedance of each of said capacitors as a function of frequency; comparing said impedances to an expected impedance, such that capacitors having shifts to lower than expected impedance values at resonance frequencies are rejected as defective.
Claim 3
Independent Claim
118 words
A method for non-destructive testing of a multilayer ceramic capacitor exhibiting piezoelectric effects only during poling by a bias voltage to determine the presence of delamination of the layers and non-visible cracks in said capacitor comprising the steps of: determining the expected resonance frequency and the expected impedance at resonance for said specific of capacitor; inserting said capacitor in an impedance bridge; applying a bias voltage to said capacitor, said voltage being between 1 and 2.5 times the rated voltage of said capacitor; measuring the impedance of said capacitor as a function of frequency; comparing said impedance to said expected impedance, such that a lower than expected impedance value at resonance frequencies indicates that said capacitor is defective.
Claim 4
Independent Claim
118 words
A method for non-destructive testing of a multilayer ceramic capacitor exhibiting piezoelectric effects only during poling by a bias voltage to determine the presence of delamination of the layers and non-visible cracks in said capacitor comprising the steps of: determining the expected resonance frequency and the expected impedance at resonance for said specific of capacitor; inserting said capacitor in an impedance bridge; applying a bias voltage to said capacitor, said voltage being between 1 and 2.5 times the rated voltage of said capacitor; measuring the impedance of said capacitor as a function of frequency; comparing said impedance to said expected impedance, such that a lower than expected impedance value at resonance frequencies indicates that said capacitor is defective.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-02-16 | 1990-08-18 | 1991-02-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-02-16 | 1994-08-18 | 1995-02-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-02-16 | 1998-08-18 | 1999-02-17 | $7700.00 | Window Closed / Lapsed |