Patent US4234631A successfully refreshed from Google Patents.
US4234631A
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Method for immersion deposition of tin and tin-lead alloys
Assignee: TE Connectivity Corp
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Filing: 1979-07-20
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Granted: 1980-11-18
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Expires: 1999-07-20
Abstract
Abstract An aqueous bath useful in, and methods for, immersion plating of tin and tin-lead alloys which give greatly increased deposition rates and thicker coatings of better quality accomplished by incorporating into immersion plating tin bath compositions soluble plumbous salts in the amount from 0.5 grams per liter calculated on the basis of elemental lead to the maximum amount soluble in the bath and a sulphur-containing complexing agent for the tin and lead such as thiourea or a thiourea-type derivative; the bath solution contains stannous chloride, lead chloride, sodium hypophosphite (as a solubility enhancer) and with hydrochloric acid used as an agent for adjusting the pH in the resulting bath from 0.5 to 1.0.
Inventors
- 👤 Thomas F. Davis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 12:48
CPC Classifications
C; C23; C23C; C23C18/00; C23C18/16; C23C18/48; H; H05; H05K; H05K3/00; H05K3/22; H05K3/24; H05K3/244; H05K3/30; H05K3/32; H05K3/34; H05K3/3465; H05K3/3473
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
230 words
A method for the immersion deposition of essentially tin and tin-lead alloys onto copper or copper alloy substrates, comprising immersing said copper or copper alloy substrate into an immersion plating bath which comprises: (a) a soluble plumbous salt in an amount from about 0.5 grams to about 25 grams per liter calculated on the basis of elemental lead including the maximum soluble in said bath; (b) tin as a soluble stannous salt in an amount of from about 5 to 150 grams per liter; (c) a thiourea as a sulfur containing complexing agent in an amount of from about 40 grams per liter to about 150 grams per liter; and (d) sufficient hydrochloric acid or hydrobromic acid to provide a pH for the bath in the range of 0.6 to 1.0; permitting said immersion plating to proceed at a temperature of about 100° F. to 200° F. for a sufficient time to build upon said substrate a tightly adherent layer of essentially tin or tin-lead alloy; wherein, in said deposition of essentially tin, said plumbous salt is present in sufficient amount to act as a rate of deposition enhancer, and wherein said bath will function to deposit said essentially tin and tin-lead alloys onto said copper or copper alloy substrates by immersion deposition at a rate of at least 85 microinches in 5 minutes at a temperature of 170° F.
Claim 2
Independent Claim
230 words
A method for the immersion deposition of essentially tin and tin-lead alloys onto copper or copper alloy substrates, comprising immersing said copper or copper alloy substrate into an immersion plating bath which comprises: (a) a soluble plumbous salt in an amount from about 0.5 grams to about 25 grams per liter calculated on the basis of elemental lead including the maximum soluble in said bath; (b) tin as a soluble stannous salt in an amount of from about 5 to 150 grams per liter; (c) a thiourea as a sulfur containing complexing agent in an amount of from about 40 grams per liter to about 150 grams per liter; and (d) sufficient hydrochloric acid or hydrobromic acid to provide a pH for the bath in the range of 0.6 to 1.0; permitting said immersion plating to proceed at a temperature of about 100° F. to 200° F. for a sufficient time to build upon said substrate a tightly adherent layer of essentially tin or tin-lead alloy; wherein, in said deposition of essentially tin, said plumbous salt is present in sufficient amount to act as a rate of deposition enhancer, and wherein said bath will function to deposit said essentially tin and tin-lead alloys onto said copper or copper alloy substrates by immersion deposition at a rate of at least 85 microinches in 5 minutes at a temperature of 170° F.
Claim 3
Dependent Claim
23 words
A method according to claim 1 wherein the immersion plating bath also includes a leveling agent and a solubility enhancer for said bath.
Claim 4
Dependent Claim
27 words
A method according to claim 2 wherein said solubility enhancer is sodium hypophosphite and is present in an amount of about 10 to 100 grams per liter.
Claim 5
Dependent Claim
37 words
A method according to claim 1 wherein said tin is present in said immersion plating bath in the form of stannous chloride, the plumbous salt is present as lead chloride, and the solubility enhancer is sodium hypophosphite.
Claim 6
Dependent Claim
34 words
A method according to claim 1 wherein the ratio of lead to tin dissolved in the immersion plating bath ranges from 2% to 30% calculated on the basis of the weight of the metal.
Claim 7
Dependent Claim
33 words
A method according to claim 1 wherein the concentration of lead in the immersion plating bath is sufficiently low to limit the lead composition in the resulting deposit to less than 2% .
Claim 8
Dependent Claim
77 words
A method according to claim 1 for the deposition of essentially tin wherein the immersion plating bath comprises the following composition: ______________________________________
Component Grams/Liter
______________________________________
a. hydrous stannous chloride
from about 10 to about 150
(SnCl.sub.2 . 2H.sub.2 O)
b. lead chloride from about 1 to about 12
(PbCl.sub.2)
c. sodium hypophosphite
from about 10 to about 100
(NaH.sub.2 PO.sub.2 . H.sub.2 O)
d. thiourea from about 40 to about 100
(NH.sub.2 . CS . NH.sub.2)
______________________________________
Claim 9
Dependent Claim
71 words
A method according to claim 1 wherein the immersion plating bath comprises the following composition: ______________________________________
Component Grams/Liter
______________________________________
a. hydrous stannous chloride
from about 5 to about 100
(SnCl.sub.2 . 2H.sub.2 O)
b. lead chloride from about 2 to about 25
(PbCl.sub.2)
c. sodium hypophosphite
from about 60 to about 100
(NaH.sub.2 PO.sub.2 . H.sub.2 O)
d. thiourea from about 100 to about 150
(NH.sub.2 . CS . NH.sub.2)
______________________________________
Claim 10
Dependent Claim
21 words
A method according to claim 1 wherein the immersion plating bath further contains gelatin in the amount of about 0.1 grams/liter.
Claim 11
Dependent Claim
26 words
A method according to claim 1 wherein the immersion plating bath further contains an alkyl phenoxy poly(oxyalkyl) ethanol surfactant in the amount of about 0.1 grams/liter.
Claim 12
Dependent Claim
63 words
A method according to claim 1, for the deposition of tin-lead alloys containing about 90%-95% lead and 5-10% tin, which comprises immersing said substrate in a bath composition containing about 15-25 grams/liter of lead chloride, 6-10 grams/liter of tin chloride, 60-100 grams/liter of sodium hypophosphite, 100-150 grams/liter of thiourea and 50-100 ml/liter of hydrochloric acid, with a pH range of 0.5 to 1.0.
Claim 13
Dependent Claim
63 words
A method according to claim 1 for the deposition of alloys containing about 60% tin and 40% lead, which comprises immersing said substrate in a bath composition containing about 15-25 grams/liter of tin chloride dihydrate, 8-12 grams/liter of lead chloride, 60-100 grams/liter of sodium hypophosphite, 100-150 grams/liter of thiourea and 50-100 ml/liter of hydrochloric acid with a pH range of 0.5 to 1.0.
Claim 14
Dependent Claim
66 words
A method according to claim 1 for the deposition of alloys containing about 10% lead and 90% tin, which comprises immersing said substrate in a bath composition containing about 6 grams/liter of lead chloride, about 25 grams/liter of tin chloride dihydrate, about 60-100 grams/liter of sodium hypophosphite, about 100-150 grams/liter of thiourea, and 50-100 ml/liter of hydrochloric acid with a pH range of 0.5 to 1.0.
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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) | 1983-11-18 | 1984-05-19 | 1984-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-11-18 | 1988-05-19 | 1988-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-11-18 | 1992-05-19 | 1992-11-18 | $7700.00 | Window Closed / Lapsed |