US5076906A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for testing encapsulation integrity
Assignee: Raytheon Co
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Filing: 1991-01-31
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Granted: 1991-12-31
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Expires: 2011-01-31
Abstract
Abstract A procedure is disclosed for detecting and documenting flaws in the glassivation layer protecting the active device region of an integrated circuit. A droplet of dilute sulfuric acid solution is placed on top of the glassivation layer and a positively biased electrode is immersed in it. The leads coupled to circuit under the glassivation layer are coupled to a more negative voltage. The release of hydrogen bubbles into the solution through flaws in the glassivation via an electrolysis reaction are readily observable. Defects in a glassivation layer over nichrome devices may be documented by reversing the polarity of the bias to cause a reversal of the electrolysis process and a release of oxygen from the defective sites. This causes oxidation and disfigurement of the nichrome which can be documented using ordinary photographic means. Defects in a glassivation layer over aluminum may be documented by replacing the droplet of dilute sulfuric acid with a droplet of dilute sodium chloride; the resulting disfigurement may be photographed.
Inventors
- 👤 Aaron C. DerMarderosian, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 22:12
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/28; G01R31/316
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
67 words
A method for detecting voids in an insulating encapsulation layer overlying an electrical circuit including an electrically conductive region, said method comprising the steps of: a. covering said encapsulation layer with an electrolytic solution comprising deionized water; b. applying an electrical potential between said electrolytic solution and said electrically conductive region; and c. observing said encapsulation layer for the evolution of gas bubbles through said electrolytic solution.
Claim 2
Independent Claim
67 words
A method for detecting voids in an insulating encapsulation layer overlying an electrical circuit including an electrically conductive region, said method comprising the steps of: a. covering said encapsulation layer with an electrolytic solution comprising deionized water; b. applying an electrical potential between said electrolytic solution and said electrically conductive region; and c. observing said encapsulation layer for the evolution of gas bubbles through said electrolytic solution.
Claim 3
Dependent Claim
20 words
The method according to claim 1 wherein said electrolytic solution comprises a weak solution of sulfuric acid in deionized water.
Claim 4
Dependent Claim
20 words
The method according to claim 2 wherein said applying step includes applying the more positive potential to said electrolytic solution.
Claim 5
Dependent Claim
24 words
The method according to claim 3 wherein said applying step includes applying an electrical potential substantially within the range of 5 to 7 volts.
Claim 6
Dependent Claim
21 words
The method according to claim 3 wherein said applying step includes applying an electrical potential for approximately 15 to 20 seconds.
Claim 7
Dependent Claim
20 words
The method according to claim 2 wherein said applying step includes applying the more negative potential to said electrolytic solution.
Claim 8
Dependent Claim
19 words
The method according to claim 6 wherein said applying step includes applying an electrical potential of approximately 10 volts.
Claim 9
Dependent Claim
21 words
The method according to claim 6 wherein said applying step includes applying an electrical potential for approximately 10 to 15 seconds.
Claim 10
Dependent Claim
20 words
The method according to claim 1 wherein said electrolytic solution comprises a weak solution of sodium chloride in deionized water.
Claim 11
Dependent Claim
20 words
The method according to claim 9 wherein said applying step includes applying the more negative potential to said electrolytic solution.
Claim 12
Dependent Claim
18 words
The method according claim 10 wherein said applying step includes applying an electrical potential of approximately 10 volts.
Claim 13
Dependent Claim
19 words
The method according to claim 10 wherein said applying step includes applying an electrical potential for approximately 20 seconds.
Claim 14
Independent Claim
82 words
A method for detecting voids in an insulating encapsulation layer overlying an electrical circuit having an electrically conductive region, said method comprising the steps of: a. covering said encapsulation layer with an electrolytic solution comprising a weak solution of sulfuric acid in deionized water; b. applying a first electrical potential to said electrically conductive region and a second, more positive potential to said electrolytic solution; and c. observing said encapsulation layer for the evolution of hydrogen gas bubbles through said electrolytic solution.
Claim 15
Independent Claim
82 words
A method for detecting voids in an insulating encapsulation layer overlying an electrical circuit having an electrically conductive region, said method comprising the steps of: a. covering said encapsulation layer with an electrolytic solution comprising a weak solution of sulfuric acid in deionized water; b. applying a first electrical potential to said electrically conductive region and a second, more positive potential to said electrolytic solution; and c. observing said encapsulation layer for the evolution of hydrogen gas bubbles through said electrolytic solution.
Claim 16
Independent Claim
84 words
A method for detecting voids in an insulating encapsulation layer overlying an electrical circuit having an electrically conductive region including nichrome, said method comprising the steps of: a. covering said encapsulation layer with an electrolytic solution comprising a weak solution of sulfuric acid in deionized water; b. applying a first electrical potential to said electrically conductive region and a second, more negative potential to said electrolytic solution; and c. observing said encapsulation layer for the evolution of oxygen gas bubbles through said electrolytic solution.
Claim 17
Independent Claim
84 words
A method for detecting voids in an insulating encapsulation layer overlying an electrical circuit having an electrically conductive region including nichrome, said method comprising the steps of: a. covering said encapsulation layer with an electrolytic solution comprising a weak solution of sulfuric acid in deionized water; b. applying a first electrical potential to said electrically conductive region and a second, more negative potential to said electrolytic solution; and c. observing said encapsulation layer for the evolution of oxygen gas bubbles through said electrolytic solution.
Claim 18
Independent Claim
84 words
A method for detecting voids in an insulating encapsulation layer overlying an electrical circuit having an electrically conductive region including aluminum, said method comprising the steps of: a. covering said encapsulation layer with an electrolytic solution comprising a weak solution of sodium chloride in deionized water; b. applying a first electrical potential to said electrically conductive region and a second, more negative potential to said electrolytic solution; and c. observing said encapsulation layer for the evolution of oxygen gas bubbles through said electrolytic solution.
Claim 19
Independent Claim
84 words
A method for detecting voids in an insulating encapsulation layer overlying an electrical circuit having an electrically conductive region including aluminum, said method comprising the steps of: a. covering said encapsulation layer with an electrolytic solution comprising a weak solution of sodium chloride in deionized water; b. applying a first electrical potential to said electrically conductive region and a second, more negative potential to said electrolytic solution; and c. observing said encapsulation layer for the evolution of oxygen gas bubbles through said electrolytic solution.
References Cited (Backward Citations)
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1994-12-30 | 1995-07-01 | 1995-12-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-12-30 | 1999-07-01 | 1999-12-31 | $3760.00 | Window Closed / Lapsed |
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