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US4439338A Expired / Lapsed US ⏱️ 0.0 years remaining

Solution for stripping a layer of tin or tin-lead alloy from a substrate by means of a spraying operation

Assignee: ALFACHIMICI SpA AN ITALIAN JOINT-STOCK Co
•
Filing: 1982-09-21
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Granted: 1984-03-27
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Expires: 2002-09-21
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Abstract

Abstract The invention relates to a chemical solution capable of selectively stripping a layer of tin or tin-lead alloy from a substrate, generally of copper, by means of a spraying operation, without requiring the use of any specially designed machine, inasmuch as the solution does not exhibit any particular aggressiveness in respect of the metal materials of which the spraying machines are usually made, and is nevertheless able to selectively strip and maintain in solution the tin or the tin-lead alloy, without etching the copper substrate. The solution comprises mainly an acid of organic nature appertaining to the group including the class of the alkylsulfonic acids having a number of carbon atoms from 1 to 4, such as in particular the methanesulfonic acid. The solution also contains an aromatic nitro-substituted compound including a solubilizing group, which is adapted to oxidize the tin-lead alloy and to facilitate the etching action of the organic acid. A further component of the solution is formed by thiourea or alkyl-substituted or aryl-substituted thioureas, whose function consists in preventing the tin from being deposited again onto the copper substrate.

Inventors

  • 👤 Francesco Tomaiuolo
  • 👤 Michele Capano

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-03 00:38
CPC Classifications
C; C23; C23F; C23F1/00; C23F1/44

Claims Analysis

Total Claims: 11
Claim 1
Independent Claim 104 words
A solution for selectively stripping a layer of tin or tin-lead alloy from a substrate, comprising in aqueous solution: a first component being an organic acid of the group consisting of the alkylsulfonic acids having a number of carbon atoms from 1 to 4; a second component being an organic oxidizer of the group consisting of the aromatic nitro-substituted and polynitro-substituted compounds having at least one group --NO 2 and a solubilizing group --SO 3 H or --COOH, and their alkaline salts; and a third component being a compound of the group consisting of thiourea and alkyl-substituted or aryl-substituted thioureas having low molecular weight.
Claim 2
Dependent Claim 104 words
A solution for selectively stripping a layer of tin or tin-lead alloy from a substrate, comprising in aqueous solution: a first component being an organic acid of the group consisting of the alkylsulfonic acids having a number of carbon atoms from 1 to 4; a second component being an organic oxidizer of the group consisting of the aromatic nitro-substituted and polynitro-substituted compounds having at least one group --NO 2 and a solubilizing group --SO 3 H or --COOH, and their alkaline salts; and a third component being a compound of the group consisting of thiourea and alkyl-substituted or aryl-substituted thioureas having low molecular weight.
Claim 3
Dependent Claim 25 words
A stripper solution as set forth in claim 1, wherein said organic acid is contained with a concentration ranging from 1 g/l to the saturation.
Claim 4
Dependent Claim 25 words
A stripper solution as set forth in claim 2, wherein said organic acid is contained with a concentration ranging from 30 g/l to 120 g/l.
Claim 5
Dependent Claim 29 words
A stripper solution as set forth in claim 3, wherein said organic oxidizer having a solubilizing group is contained with a concentration ranging from 0.5 g/l to the saturation.
Claim 6
Dependent Claim 29 words
A stripper solution as set forth in claim 4, wherein said organic oxidizer having a solubilizing group is contained with a concentration ranging from 20 g/l to 70 g/l.
Claim 7
Dependent Claim 25 words
A stripper solution as set forth in claim 5, wherein said third component is contained with a concentration ranging from 0.1 g/l to 50 g/l.
Claim 8
Dependent Claim 25 words
A stripper solution as set forth in claim 6, wherein said third component is contained with a concentration ranging from 1 g/l to 10 g/l.
Claim 9
Dependent Claim 16 words
A stripper solution as set forth in claim 1, wherein said organic acid is methanesulfonic acid.
Claim 10
Dependent Claim 31 words
A stripper solution as set forth in claim 1, which is adapted to be applied by means of a spraying operation at a temperature ranging from 0° C. to 70° C.
Claim 11
Dependent Claim 31 words
A stripper solution as set forth in claim 9, which is adapted to be applied by means of a spraying operation at a temperature ranging from 15° C. to 25° C.

References Cited (Backward Citations)

US2698781A Cited
US2956956A Cited
US3365401A Cited
FR2102030A5 Cited
US3677949A Cited
DE2412134A1 Cited
US4004956A Cited
US4009299A Cited
US4374744A Cited
US4397753A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1987-03-27 1987-09-26 1988-03-27 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1991-03-27 1991-09-26 1992-03-27 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1995-03-27 1995-09-26 1996-03-27 $7700.00 Window Closed / Lapsed

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