US4882202A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Use of immersion tin and tin alloys as a bonding medium for multilayer circuits
Assignee: Techno Instruments Investments 1983 Ltd
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Filing: 1987-10-21
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Granted: 1989-11-21
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Expires: 2007-10-21
Abstract
Abstract A novel immersion tin composition is disclosed containing both thiourea compounds and urea compounds. A method for improving the adhesion of printed circuit boards to one another in a multilayer board and for minimizing or eliminating smear in a multilayer board is also disclosed comprising coating the metal layers of the individual circuit boards with an immersion tin coating prior to laminating them to form a multilayer board.
Inventors
- 👤 Abraham M. Holtzman
- 👤 Joseph Relis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 13:13
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/22; H05K3/24; H05K3/244; C; C23; C23C; C23C18/00; C23C18/16; C23C18/1601; C23C18/1633; C23C18/1655; C23C18/1658; C23C18/166; C23C18/52; C23C18/54; H05K3/38; H05K3/382; H05K3/384; H05K2203/00; H05K2203/07; H05K2203/0703; H05K2203/072; H05K3/46; H05K3/4611
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
103 words
A process for improving the adhesion properties of a metal layer of a circuit board to a non-conductive surface of a circuit board comprising coating said layer with an immersion metal composition, said immersion metal composition comprising: (a) a thiourea compound (b) a urea compound (c) a metal salt said metal salt being selected from the group of salts based on the Group IVA metals including tin, Group VIII metals, Group IB metals, Group IIB metals and Group IIIA metals, said urea compound and thiourea compound each being present in an amount sufficient to enable said composition to function as an immersion composition.
Claim 2
Dependent Claim
103 words
A process for improving the adhesion properties of a metal layer of a circuit board to a non-conductive surface of a circuit board comprising coating said layer with an immersion metal composition, said immersion metal composition comprising: (a) a thiourea compound (b) a urea compound (c) a metal salt said metal salt being selected from the group of salts based on the Group IVA metals including tin, Group VIII metals, Group IB metals, Group IIB metals and Group IIIA metals, said urea compound and thiourea compound each being present in an amount sufficient to enable said composition to function as an immersion composition.
Claim 3
Dependent Claim
30 words
The process of claim 1 where said thiourea compound and said urea compound comprise a thiourea nucleus and a urea nucleus with the same substituents on each of said nuclei.
Claim 4
Dependent Claim
17 words
The process of claim 1 where said thiourea compound comprises thiourea and said urea compound comprises urea.
Claim 5
Dependent Claim
47 words
The process of claim 1 further comprising a compound selected from a member of the group consisting of a Group VIII metal salt, a Group IVA metal salt with the exception of tin, a Group IIB metal salt or a Group IB metal salt or mixtures thereof.
Claim 6
Dependent Claim
31 words
The process of claim 1 where said composition further comprises a salt of an element selected from a member of the group consisting of iron, cobalt, or nickel or mixtures thereof.
Claim 7
Dependent Claim
12 words
The process of claim 5 where said salt comprises a nickel salt.
Claim 8
Dependent Claim
11 words
The process of claim 1 further comprising a salt of lead.
Claim 9
Dependent Claim
11 words
The process of claims 4 or 5 further comprising a surfactant.
Claim 10
Dependent Claim
13 words
The process of claims 4 or 5 further comprising polyoxyethylene nonyl phenol surfactant.
Claim 11
Dependent Claim
54 words
The process of claim 1 where the components of said composition are present in the following amounts on a molar basis: (a) about 10 to about 125 parts of a thiourea compound (b) about 10 to about 125 parts of a urea compound (c) about 1 to about 15 parts of a tin salt.
Claim 12
Dependent Claim
46 words
The process of claim 10 further comprising the following components on a molar basis: (d) about 5 to about 40 parts of a chelating agent (e) about 5 to about 110 parts of a reducing agent (f) about 1 to about 30 parts of an acid.
Claim 13
Dependent Claim
59 words
The process of claim 10 further comprising a compound selected from the group consisting of a Group VIII metal salt, a Group IVA metal salt with the exception of tin, a Group IIB metal salt or a Group IB metal salt or mixtures thereof in an amount from about 0.2 parts to about 55 parts on a molar basis.
Claim 14
Dependent Claim
114 words
A process for improving the adhesion properties of a metal layer of a circuit board to a non-conductive surface of a circuit board comprising coating said layer with an immersion metal composition, said immersion metal composition comprising: (a) a thiourea compound (b) a urea compound (c) a metal salt (d) a chelating agent (e) a reducing agent (f) an acid said metal salt being selected from the group of salts based on the Group IVA metals including tin, Group VIII metals, Group IB metals, Group IIB metals and Group IIIA metals, said urea compound and thiourea compound each being present in an amount sufficient to enable said composition to function as an immersion composition.
Claim 15
Dependent Claim
114 words
A process for improving the adhesion properties of a metal layer of a circuit board to a non-conductive surface of a circuit board comprising coating said layer with an immersion metal composition, said immersion metal composition comprising: (a) a thiourea compound (b) a urea compound (c) a metal salt (d) a chelating agent (e) a reducing agent (f) an acid said metal salt being selected from the group of salts based on the Group IVA metals including tin, Group VIII metals, Group IB metals, Group IIB metals and Group IIIA metals, said urea compound and thiourea compound each being present in an amount sufficient to enable said composition to function as an immersion composition.
Claim 16
Dependent Claim
15 words
The process of claim 1 or 13 where said tin salt comprises a stannous salt.
Claim 17
Dependent Claim
14 words
The process of claim 13 where said reducing agent comprises an aldehyde reducing agent.
Claim 18
Dependent Claim
24 words
The process of claim 13 where said acid comprises a mineral acid and said tin salt comprises a stannous salt of a mineral acid.
Claim 19
Dependent Claim
17 words
The process of claims 1 or 13 or 4 or 5 where said metal layer comprises copper.
Claim 20
Dependent Claim
20 words
The process of claims 1 or 13 or 4 or 5 where said printed circuit board comprises a multilayer 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) | 1992-11-20 | 1993-05-22 | 1993-11-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-11-20 | 1997-05-22 | 1997-11-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-11-20 | 2001-05-22 | 2001-11-21 | $7700.00 | Window Closed / Lapsed |