US4373656A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of preserving the solderability of copper
Assignee: AT&T Inc
•
Filing: 1981-07-17
•
Granted: 1983-02-15
•
Expires: 2001-07-17
Abstract
Abstract A method for preserving the solderability of copper conductors comprises stabilizing a cleaned, mildly etched conductor surface with a phosphoric acid-glycol solution then immersing the surface in imidazole followed by a rinse to remove excess imidazole.
Inventors
- 👤 John L. Parker, Jr.
- 👤 Robert B. Ranes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 20:07
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/22; H05K3/28; H05K3/282; C; C23; C23F; C23F11/00; C23F11/08; C23F11/10; C23F11/14; C23F11/149; H05K2203/00; H05K2203/05; H05K2203/0562; H05K2203/0591
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
48 words
A method of preserving the solderability of a copper surface comprising: stabilizing the surface with an aqueous solution comprising a mixture of an acid phosphate and a glycol; treating the stabilized surface with a protective azole; and rinsing the azole treated surface so as to remove excess azole.
Claim 2
Independent Claim
48 words
A method of preserving the solderability of a copper surface comprising: stabilizing the surface with an aqueous solution comprising a mixture of an acid phosphate and a glycol; treating the stabilized surface with a protective azole; and rinsing the azole treated surface so as to remove excess azole.
Claim 3
Dependent Claim
13 words
The method recited in claim 1 wherein the acid phosphate is phosphoric acid.
Claim 4
Dependent Claim
16 words
The method recited in claim 1 wherein the glycol is a low molecular weight alkyl glycol.
Claim 5
Dependent Claim
19 words
The method recited in claim 1 wherein the stabilizing solution comprises a mixture of phosphoric acid and ethylene glycol.
Claim 6
Independent Claim
16 words
The method recited in claims 1, 2, 3 or 4 wherein the azole is an imidazole.
Claim 7
Dependent Claim
36 words
The method recited in claim 4 wherein the azole is imidazole and wherein the concentration of concentrated phosphoric acid and ethylene glycol in the stabilizer solution is about 34 weight percent and 3.7 weight percent, respectively.
Claim 8
Dependent Claim
16 words
The method recited in multiple claim 5 wherein the imidazole concentration is at least 2 g/l.
Claim 9
Dependent Claim
15 words
The method recited in claim 6 wherein the imidazole concentration is at least 2 g/l.
Claim 10
Dependent Claim
27 words
The method recited in claim 8 wherein the imidazole is heated to about 140° F. and the surface is contacted with the imidazole for about 1 minute.
Claim 11
Dependent Claim
19 words
The method recited in claim 1 wherein the surface is exposed to a mild etching solution prior to stabilization.
Claim 12
Dependent Claim
15 words
The method recited in claim 10 wherein the mild etching solution comprises a soluble persulfate.
Claim 13
Independent Claim
62 words
A method of preserving the solderability of a copper surface comprising: etching the surface with a mild etching solution comprising a soluble persulfate; stabilizing the etched surface with an aqueous solution comprising phosphoric acid and an alkyl glycol; treating the stabilized surface with imidazole; and rinsing the imidazole treated surface so as to leave only a thin protective film of imidazole remaining.
Claim 14
Independent Claim
62 words
A method of preserving the solderability of a copper surface comprising: etching the surface with a mild etching solution comprising a soluble persulfate; stabilizing the etched surface with an aqueous solution comprising phosphoric acid and an alkyl glycol; treating the stabilized surface with imidazole; and rinsing the imidazole treated surface so as to leave only a thin protective film of imidazole remaining.
Claim 15
Dependent Claim
19 words
The method recited in multiple claim 5 wherein the copper surface comprises the conductors of a printed circuit board.
Claim 16
Dependent Claim
31 words
The method recited in multiple claim 5 wherein the copper comprises the conductors of a printed circuit board and including the step of soldering circuit components on said printed circuit board.
Claim 17
Dependent Claim
18 words
The method recited in claim 12 wherein the copper surface comprises the conductors of a printed circuit board.
Claim 18
Dependent Claim
30 words
The method recited in claim 12 wherein the copper comprises the conductors of a printed circuit board and including the step of soldering circuit components on said printed circuit 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) | 1986-02-14 | 1986-08-16 | 1987-02-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-02-14 | 1990-08-16 | 1991-02-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-02-14 | 1994-08-16 | 1995-02-15 | $7700.00 | Window Closed / Lapsed |