Electrodeposition of silver with fluoropolymer nanoparticles

Inactive Publication Date: 2016-02-04
MACDERMID ENTHONE INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention is about electrolytic plating compositions and processes for depositing a composite silver or silver alloy coating onto a substrate. The composition includes a silver ion source, a complexing agent, a pre-mix dispersion of fluoropolymer nanoparticles, and an auxiliary surfactant. The pH of the composition is from about 8 to about 14. The process involves contacting the substrate surface with the electrolytic plating composition and applying an external source of electrons to the composition to electrolytically deposit the composite coating onto the substrate surface. The composite coating comprises silver or silver alloy and the fluoropolymer nanoparticles. The technical effect of the invention is to provide a novel coating that combines the properties of silver or silver alloy with those of fluoropolymer nanoparticles, resulting in improved mechanical properties, such as high hardness and high adhesion, as well as excellent chemical properties, such as high corrosion resistance and high chemical stability.

Problems solved by technology

However, pure silver coatings have a high coefficient of friction (COF).
As a result, high insertion forces are required for electrical connectors coated with silver.
Also, these coatings have poor wear characteristics (poor durability).
Consequently, these characteristics limit the application of pure silver coatings in connector applications.
However, the silver plating solutions disclosed by Abys et al. provide limited stability for the fluoropolymer particles and, in some instances, provide coatings having an undesirable appearance.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0101]The following plating compositions were prepared for the deposition of silver and silver-based composite coatings. The pH of each composition was approximately 9.5. Potassium hydroxide was added as need to maintain this pH.

Bath 1-1Silver (as Ag-MSA)30g / L5,5-dimethylhydantoin130g / LTAMOL NN 940120g / L(sodium salt of a naphthalenesulfonicacid condensation product)potassium methanesulfonate100g / Lwaterbalance to 1 L

Bath 1-2Silver (as Ag-MSA)30g / L5,5-dimethylhydantoin130g / LTAMOL NN 940120g / Lpotassium methanesulfonate100g / LDRYFILM WD-4560 (48% PTFE10 g / L (PTFE massdispersion with concentration)surfactant)waterbalance to 1 L

Bath 1-3Silver (as Ag-MSA)30g / L5,5-dimethylhydantoin125g / LTAMOL NN 940120g / L(sodium salt of a naphthalenesulfonicacid condensation product)potassium methanesulfonate100g / Lpotassium bromideapprox. 100-160 ppmS-106A (cationic fluorosurfactant)3mL / LDC 1430 (antifoam additive)approx. 30-300 ppmwaterbalance

Bath 1-4Silver (as Ag-MSA)30g / L5,5-dimethylhydantoin125g / LTAMOL N...

example 2

[0105]A silver composite coating was deposited on a copper alloy substrate using Bath 1-4 prepared in accordance with Example 1. The coated substrate was then heated at 125° C. for seven days. Coefficient of friction and contact resistance measurements as described in Example 1 were repeated after the thermal aging. The results show that these properties did not change after thermal aging.

example 3

[0106]A solution of silver methanesulfonate was mixed with a PTFE dispersion at a concentration of 10 g / L of PTFE. Samples of the solution were mixed with four different surfactants. The stability of the solutions was examined after five weeks of shelf aging. The results are provided in the following table.

AuxiliarySurfactantStabilityCompositionConc.ObservationsSampleAuxiliary Surfactant(mL / L)After 5 weeksControl——Multi-phase(Ag-MSA +solution; PTFEPTFEcoagulated anddispersion)separated3-1cetyltrimethylammonium3Homogeneouschloridesolution3-2S106A3Homogeneous(fluoroalkyl ammoniumsolutionchloride cationicsurfactant 28-30%)3-3S208M3Homogeneous(fluoroalkyl ammoniumsolutionchloride cationic / anionicsurfactant blend 33%)3-4NEODOL 91-6 (C9-11,3Homogeneous6EO alcohol ethoxylate)solution

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Abstract

Electrolytic plating compositions and electrolytic plating processes for the co-deposition of silver or silver alloy with fluoropolymer nanoparticles are provided. The silver or silver alloy composite coating containing fluoropolymer nanoparticles has enhanced functional properties such as a reduced coefficient of friction. The electrolytic plating composition comprises: (a) a silver ion source comprising silver methane sulfonate (Ag-MSA); (b) a complexing agent comprising a compound comprising a nitrogen-containing heterocyclic ring; (c) a pre-mix dispersion comprising fluoropolymer nanoparticles particles having a mean particle size of from about 10 nm and about 500 nm and a surfactant; and (d) an auxiliary surfactant comprising a cationic fluorosurfactant, wherein the composition has a pH of from about 8 to about 14.

Description

FIELD OF THE INVENTION[0001]The present invention generally relates to electrolytic plating compositions and electrolytic plating processes for the co-deposition of silver or silver alloy with fluoropolymer nanoparticles to provide a silver or silver alloy composite coating with enhanced functional properties.BACKGROUND OF THE INVENTION[0002]In general, pure silver coatings are highly conductive and are harder than gold. For these reasons, these coatings would be especially suited for electrical connectors. However, pure silver coatings have a high coefficient of friction (COF). As a result, high insertion forces are required for electrical connectors coated with silver. Also, these coatings have poor wear characteristics (poor durability). The severity of wear of the coating generally increases with increased normal forces. Consequently, these characteristics limit the application of pure silver coatings in connector applications.[0003]Coatings made from fluoropolymers such as poly...

Claims

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Application Information

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IPC IPC(8): C25D15/00C25D3/46C25D3/64
CPCC25D15/00C25D3/46C25D3/64C25D7/00H01R13/03
InventorLI, JINGYEABYS, JOSEPH A.KUDRAK, JR., EDWARD J.
OwnerMACDERMID ENTHONE INC