Patent US4093466A successfully refreshed from Google Patents.
US4093466A
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Electroless tin and tin-lead alloy plating baths
Assignee: TE Connectivity Corp
•
Filing: 1975-05-06
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Granted: 1978-06-06
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Expires: 1995-05-06
Abstract
Abstract Salt compositions and baths thereof 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 of 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. Preferably the salt elements are stannous chloride, lead chloride, sodium hypophosphite (as a solubility enhancer) and with hydrochloric acid used as a agent for adjusting the pH in the resulting bath from 0.5 to 1.0.
Inventors
- 👤 Thomas Francis Davis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 09:10
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: 8
Claim 1
Independent Claim
101 words
A salt composition, when diluted with 1 liter of water and sufficient hydrochloric acid to provide a solution having a pH of 0.5 to 1, is suitable for immersion plating of tin-lead alloys at increased rates, the salt composition comprising the proportions of: ______________________________________
a. hydrous stannous chloride
from about 10 to about 150 g,
(SnCl.sub.2 . 2H.sub.2 O)
b. lead chloride from about 1 to about 12 g,
(PbCl.sub.2)
c. sodium hypophosphite
from about 10 to about 100 g,
(NaH.sub.2 PO.sub.2 . H.sub.2 O)
and
d. thiourea from about 15 to about 100 g,
(NH.sub.2 . CS . NH.sub.2)
______________________________________
Claim 2
Dependent Claim
101 words
A salt composition, when diluted with 1 liter of water and sufficient hydrochloric acid to provide a solution having a pH of 0.5 to 1, is suitable for immersion plating of tin-lead alloys at increased rates, the salt composition comprising the proportions of: ______________________________________
a. hydrous stannous chloride
from about 10 to about 150 g,
(SnCl.sub.2 . 2H.sub.2 O)
b. lead chloride from about 1 to about 12 g,
(PbCl.sub.2)
c. sodium hypophosphite
from about 10 to about 100 g,
(NaH.sub.2 PO.sub.2 . H.sub.2 O)
and
d. thiourea from about 15 to about 100 g,
(NH.sub.2 . CS . NH.sub.2)
______________________________________
Claim 3
Dependent Claim
95 words
A salt composition for immersion plating a tin-lead alloy, when diluted with 1 liter of water and sufficient hydrochloric acid to provide a solution having a pH of 0.5 to 1, said salt composition comprising the proportions of: ______________________________________
a. hydrous stannous chloride
from about 5 to about 100 g,
(SnCl.sub.2 . 2H.sub.2 O)
b. lead chloride from about 2 to about 25 g,
(PbCl.sub.2)
c. sodium hypophosphite
from about 60 to about 100 g,
(NaH.sub.2 PO.sub.2 . H.sub.2 O)
and
d. thiourea from about 100 to about 150 g.
(NH.sub.2. CS . NH.sub.2)
______________________________________
Claim 4
Dependent Claim
95 words
A salt composition for immersion plating a tin-lead alloy, when diluted with 1 liter of water and sufficient hydrochloric acid to provide a solution having a pH of 0.5 to 1, said salt composition comprising the proportions of: ______________________________________
a. hydrous stannous chloride
from about 5 to about 100 g,
(SnCl.sub.2 . 2H.sub.2 O)
b. lead chloride from about 2 to about 25 g,
(PbCl.sub.2)
c. sodium hypophosphite
from about 60 to about 100 g,
(NaH.sub.2 PO.sub.2 . H.sub.2 O)
and
d. thiourea from about 100 to about 150 g.
(NH.sub.2. CS . NH.sub.2)
______________________________________
Claim 5
Dependent Claim
13 words
A composition according to claim 1 further comprising gelatin from about 0.1 g.
Claim 6
Dependent Claim
16 words
A composition according to claim 1 further comprising an alkylphenoxy polyethanol surfactant from about 0.1 g.
Claim 7
Dependent Claim
13 words
A composition according to claim 2 further comprising gelatin from about 0.1 g.
Claim 8
Dependent Claim
16 words
A composition according to claim 2 further comprising an alkylphenoxy polyethanol surfactant from about 0.1 g.
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) | 1981-06-05 | 1981-12-05 | 1982-06-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-06-05 | 1985-12-05 | 1986-06-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-06-05 | 1989-12-05 | 1990-06-06 | $7700.00 | Window Closed / Lapsed |