Silver plating in electronics manufacture
AssigneeEnthone Inc.
InventorsYung-Herng Yau, Thomas B. Richardson, Joseph A. Abys, Karl F. Wengenroth, Anthony Fiore, Chen Xu, Chonglun Fan, John Fudala
Life of this patent
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Abstract
Compositions and methods for silver plating onto metal surfaces such as PWBs in electronics manufacture to produce a silver plating which is greater than 80 atomic % silver, tarnish resistant, and has good solderability.
Claims49
A process for Ag plating a metal surface comprising:
- contacting the metal surface with a composition comprising a source of Ag ions, a modulating agent comprising an alkylene polyamine polyacetic acid compound, and water;
- and
- forming by immersion displacement a Ag-based coating on the metal surface, wherein the ionic content of the composition is such that it has a room temperature conductivity below about 10 mS/cm, the composition has a pH between 1 and about 3, and the Ag-based coating comprises at least about 80 atomic % Ag (bulk average).
A process for depositing a Ag-based coating over a surface of a copper conducting layer in a printed wiring board substrate, the process comprising:
- contacting the metal surface with a composition comprising:
- a) a source of Ag ions;
- b) an alkylene polyamine polyacetic acid compound;
- c) water;
- and
- d) 3,5-dinitrohydroxybenzoic acid;
- wherein the ionic content of the composition is such that it has a room temperature conductivity below about 25 mS/cm the composition has a pH between 1 and about 3;
- and
- forming by immersion displacement a Ag-based coating comprising at least about 80 atomic % Ag (bulk average) on the metal surface.
A process for depositing a Ag-based coating over a surface of a copper conducting layer in a printed wiring board substrate, the process comprising:
- contacting the metal surface in the printed wiring board substrate with a composition comprising:
- a) a source of Ag ions;
- b) an alkylene polyamine polyacetic acid compound;
- c) an ethylene oxide/propylene oxide block co-polymer additive;
- and
- d) water;
- and
- wherein the ionic content of the composition is such that it has a room temperature conductivity below about 25 mS/cm and the composition has a pH between 1 and about 3;
- and
- forming by immersion displacement a Ag-based coating comprising at least about 80 atomic % Ag (bulk average) on the metal surface.
A process for Ag plating a Cu surface of a printed wiring board substrate comprising:
- contacting the Cu surface with a composition comprising:
- a) a source of Ag ions;
- b) N-(2-hydroxyethyl)ethylenediamine triacetic acid;
- c) an ethylene oxide/propylene oxide block co-polymer additive;
- d) a tarnish inhibitor;
- and
- e) water;
- wherein the composition has pH between 1 and about 3, and a room temperature conductivity of less than about 25 mS/cm;
- and
- forming by immersion displacement a Ag-based coating on the metal surface which comprises at least about 90 atomic % Ag (bulk average).
Dependencies are inferred from the claim text.