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A method for electrolytically passivating a surface of silver, silver alloy, gold, or gold alloy

A technology of electrolytic passivation and silver alloy, which is applied to the surface of gold or gold alloy, silver alloy, and electrolytic passivation of silver, which can solve the problems of passivation failure and insufficient passivation

Pending Publication Date: 2021-05-25
ATOTECH DEUT GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0011] Furthermore, it has been observed that in many cases insufficient passivation
This means, e.g. at increased temperatures, that despite the presence of passivation, over time the passivation fails and in any case undesired rusting occurs

Method used

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  • A method for electrolytically passivating a surface of silver, silver alloy, gold, or gold alloy
  • A method for electrolytically passivating a surface of silver, silver alloy, gold, or gold alloy

Examples

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example

[0112] In the following examples passivation solutions were prepared for comparative purposes and according to the invention. A comparative example is based on US 4,169,022 A.

[0113] In general, the passivation solution is obtained by mixing chromium sulfate (trivalent) and potassium formate and dissolving in water so as to obtain a predefined molar ratio. In each freshly prepared passivation solution, the concentration of trivalent chromium ions was about 1 g / L (about 19.3 mmol / L). The respective pH was adjusted by adding KOH or formic acid.

[0114] For testing, in each example, a copper leadframe (approximately 97% Cu) was utilized that included a surface of pure silver. The silver surface is a silver layer that was previously deposited onto the copper lead frame by Atotech's process Silver Tech MS LED. The layer thickness of the deposited silver layer is approximately 200 nm.

[0115] In each example, electrolytic passivation was performed with the mixed metal oxide ...

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Abstract

The present invention relates to a method for electrolytically passivating a surface of silver, silver alloy, gold, or gold alloy, the method comprising the steps of (i) providing a substrate comprising said surface, (ii) providing an aqueous passivation solution comprising - trivalent chromium ions, and - one or more than one species of carboxylic acid residue anions, (iii) contacting the substrate with said passivation solution and passing an electrical current between the substrate as a cathode and an anode such that a passivation layer is electrolytically deposited onto said surface, wherein the trivalent chromium ions with respect to all species of carboxylic acid residue anions form a molar ratio in the range from 1:10 to 1:400.

Description

technical field [0001] The invention relates to a method and respective passivation solutions for the electrolytic passivation of surfaces of silver, silver alloys, gold or gold alloys. Background technique [0002] Silver is commonly used in decorative and functional applications due to its bright and lustrous appearance and excellent electrical conductivity and temperature characteristics, respectively. On the one hand, silver is used in the manufacture of jewelry, and advantageously, it generally does not cause skin irritation. On the other hand, silver is also used in the manufacture of printed circuit boards and functional connectors for electronic components. Regardless of the intended use, however, substrates comprising respective surfaces of silver suffer from the disadvantage of undesirable rusting over time in the presence of ambient air. This rust typically contains silver sulfide and exhibits undesirable discolorations including, for example, light brown, reddi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C25D9/08
CPCC25D9/08C25D3/06
Inventor R·鲁特O·库尔茨J·塞特亚蒂-利冯子俊
Owner ATOTECH DEUT GMBH