US3909680A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Printed circuit board with silver migration prevention
Assignee: Panasonic Holdings Corp
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Filing: 1974-05-23
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Granted: 1975-09-30
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Expires: 1994-05-23
Abstract
Abstract In a printed circuit board, on which there are formed printed components such as resistors and capacitors and printed conductors, which comprise silver or silver powder and resin, such as an electrode of a component and a connecting conductor, there are provided under coating layer and/or an over coating layer comprising insulating resin and an organic inhibitor so as to prevent migration of silver from the conductor of a higher potential to the conductor of a lower potential.
Inventors
- 👤 Eiichi Tsunashima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 23:26
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/22; H05K3/28; H05K1/00; H05K1/16; H05K1/167; H05K1/02; H05K1/03; H05K1/0313; H05K1/0353; H05K1/0366; H05K1/09; H05K1/092; H05K1/095; H05K2201/00; H05K2201/02; H05K2201/0275; H05K2201/0284; H05K2201/0293; H05K2201/07; H05K2201/0753; H05K2201/0769; H05K2201/09; H05K2201/09209; H05K2201/095; H05K2201/09581; H05K2203/00; H05K2203/12; H05K2203/122; H05K2203/14; H05K2203/1461; H05K3/0094; H05K3/38; H05K3/386; H05K3/40; H05K3/4038; H05K3/4053; H05K3/4069; H05K3/46; H05K3/4644; H05K3/4664
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
124 words
IN A PRINTED CIRCUIT BOARD HAVING AT LEAST ONE SURFACE THEREOF ELECTRICALLY INSULATING MATERIAL AND AT LEAST ONE PRINTED ELECTRONIC COMPONENT ON SAID SURFACE AND AT LEAST TWO CONDUCTORS ON SAID SURFACE WHICH DURING OPERATION OF THHE CIRCUIT WILL BE AT DIFFERENT POTENTIALS AND AT LEAST ONE OF WHICH IS CONNECTED TO SAID COMPONENT, SAID CONDUCTORS HVING A COMPOSITION WHICH IS AT LEAST PARTLY SILVER, THE IMPROVEMENT COMPRISING A COATING LAYER COMPOSED OF ELECTRICALLY INSULATING RESIN AND AN ORGANIC INHIBITOR AND WHICH IS ONE THE SURFACE OF SAID CIRCUIT BOARD AND COVERING AT LEAST PART OF THE SURFACE OF SAID CONDUCTORS FOR INHIBITING MIGRATION OF SILVER, WHICH IS CONTAINED IN SAID CONDUCTOR, FFROM THE CONDUCTOR OF HHIGHER POTENTIAL TO THE CONDUCTOR OF LOWER POTENTIAL.
Claim 2
Dependent Claim
124 words
IN A PRINTED CIRCUIT BOARD HAVING AT LEAST ONE SURFACE THEREOF ELECTRICALLY INSULATING MATERIAL AND AT LEAST ONE PRINTED ELECTRONIC COMPONENT ON SAID SURFACE AND AT LEAST TWO CONDUCTORS ON SAID SURFACE WHICH DURING OPERATION OF THHE CIRCUIT WILL BE AT DIFFERENT POTENTIALS AND AT LEAST ONE OF WHICH IS CONNECTED TO SAID COMPONENT, SAID CONDUCTORS HVING A COMPOSITION WHICH IS AT LEAST PARTLY SILVER, THE IMPROVEMENT COMPRISING A COATING LAYER COMPOSED OF ELECTRICALLY INSULATING RESIN AND AN ORGANIC INHIBITOR AND WHICH IS ONE THE SURFACE OF SAID CIRCUIT BOARD AND COVERING AT LEAST PART OF THE SURFACE OF SAID CONDUCTORS FOR INHIBITING MIGRATION OF SILVER, WHICH IS CONTAINED IN SAID CONDUCTOR, FFROM THE CONDUCTOR OF HHIGHER POTENTIAL TO THE CONDUCTOR OF LOWER POTENTIAL.
Claim 3
Dependent Claim
24 words
The improvement as claimed in claim 1 in which said coating layer is an under coating layer between said circuit board and said conductor.
Claim 4
Dependent Claim
31 words
The improvement as claimed in claim 1 in which said coating layer is an over coating layer over the conductor and at least part of the circuit board around the conductor.
Claim 5
Dependent Claim
41 words
The improvement as claimed in claim 1 in which there is an under coating layer between said circuit board and said conductor and an over coating layer over the conductor and at least part of the circuit board around the conductor.
Claim 6
Dependent Claim
25 words
The improvement as claimed in claim 1 wherein said organic inhibitor is a compound taken from the group consisting of amine compounds and azole compounds.
Claim 7
Dependent Claim
54 words
The improvement as claimed in claim 1, wherein said circuit board has a hole therethrough, there is a conductor on the opposite surface of said circuit board, and extends through said hole for connecting the component and the conductors on both the surfaces of said board, and said coating layer extends through said hole.
Claim 8
Dependent Claim
51 words
The improvement as claimed in claim 1, wherein there is a conductor on the opposite surface of said circuit board and said conductor extends over the edge of said board for connecting the component and the conductors on both surfaces of said board, and said coating layer extends over said edge.
Claim 9
Dependent Claim
58 words
The improvement as claimed in claim 1, further comprising a further conductor of an electrically conductive material other than silver on one surface of said board surrounding said component and said conductor whereby there is no potential difference of the other surface of the circuit board the coating layer at the edge of said board can be omitted.
Claim 10
Dependent Claim
39 words
The improvement as claimed in claim 1, wherein there is a plurality of conductors positioned in at least two layers and an over coating layer over each of said conductors whereby said conductors are separated by a coating layer.
Claim 11
Dependent Claim
27 words
The improvement as claimed in claim 1, wherein said coating layer has a further coating layer thereon for covering pin holes in the first mentioned coating layer.
Claim 12
Dependent Claim
22 words
The improvement as claimed in claim 1, wherein said coating layer is only over said conductor which operates at the high potential.
Claim 13
Dependent Claim
22 words
The improvement as claimed in claim 1, wherein said coating layer is over the whole of said surface of said circuit board.
Claim 14
Dependent Claim
20 words
The improvement as claimed in claim 1, wherein said coating layer is only at the portions corresponding to said conductors.
Claim 15
Dependent Claim
17 words
The improvement as claimed in claim 1, wherein said coating layer is over both of said conductors.
Claim 16
Dependent Claim
21 words
The improvement as claimed in claim 14, wherein said component is a printed resistor having a composition of silver and resin.
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) | 1978-09-29 | 1979-03-31 | 1979-09-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-29 | 1983-03-31 | 1983-09-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-29 | 1987-03-31 | 1987-09-30 | $7700.00 | Window Closed / Lapsed |