# US 11,306,409 B2 · Method to enable electroplating of golden silver nanoparticles

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- Number: US 11,306,409 B2
- Document ID: US11306409B2
- Status: Granted
- Kind: B2
- Application number: 16/849,666
- Filed: 2020-04-15
- Published: 2020-11-26
- Granted: 2022-04-19
- Earliest claimed: 2019-05-23
- Assignees: AG-Nano System LLC
- Applicants: AG-Nano System LLC
- Inventors: Margaret Parker
- Web page: https://patentgrep.com/patent/US11306409B2

## CPC

- C25D 5/12: at least one layer being of nickel or chromium
- C25D 3/12: of nickel or cobalt
- C25D 3/38: of copper
- C25D 3/48: of gold
- C25D 5/14: two or more layers being of nickel or chromium, e.g. duplex or triplex layers
- C25D 5/18: Electroplating using modulated, pulsed or reversing current
- C25D 5/34: Pretreatment of metallic surfaces to be electroplated
- C25D 9/02: with organic materials
- C25D 21/12: Process control or regulation (controlling or regulating in general G05)
- C25D: PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR

## Abstract

A method to enable electroplating of nano-silver like gold material ([Ag25(SR)18]− where SR is a thiolate). The method includes activating a surface of a substrate using first counter flow conditioning rinses (CFCR) with a solution of acetone followed by a solution of alcohol; rinsing the substrate surface; drying using a nitrogen gas; cleaning using a soak-clean solution; activating using an activator solution; rinsing using an ammonia dead rinse solution; conditioning using second CFCR; etching using hydrochloric acid; rinsing third CFCR; depositing woods nickel strike material and electrolytic nickel metal; electrodeposition of a gold strike metal to the surface of the substrate; and electroplating of a nano-silver like gold material and a nano-silver like gold alloy material on to the surface of the substrate using an electroplating solution and a rate of deposition 0.0001 μm/h.

## Claims

### Claim 1

A method of electroplating comprising the successive steps of:
activating a surface of a substrate by a plurality of first counter flow conditioning rinses with a solution of acetone followed by a solution of alcohol;
rinsing the activated surface of the substrate;
drying the activated surface using a nitrogen gas;
cleaning the activated surface using a soak-clean solution comprising a concentration of 15% non-etch type alkaline cleaner;
activating the activated surface using an activator solution comprising a concentration of 20% activator;
rinsing the activated surface of the substrate using an ammonia dead rinse solution comprising a concentration of 5% ammonium hydroxide and deionized water;
conditioning the activated surface of substrate using a plurality of second counter flow conditioning rinses;
etching the activated surface of the substrate using a solution of a concentration of 20% hydrochloric acid;
rinsing the activated surface of the substrate using a plurality of third counter flow conditioning rinses;
depositing a nickel strike material and then electrolytic nickel metal on to the activated surface of the substrate;
electroplating a gold strike metal to the activated surface of the substrate; and
electroplating a nano-silver material on to the activated surface of the substrate using an electrolytic solution and a rate of deposition 0.0001 μm/hr;
wherein
the nano-silver material comprises a molecular formula of [Ag25(thiolate)18]−; and
the electrolytic solution has a pH level of 3.5-6.5.

### Claim 2 (depends on 1)

The method of claim 1, wherein the substrate comprises a connector comprising beryllium copper.

### Claim 3 (depends on 1)

The method of claim 1, wherein the electroplating a nano-silver material further comprises a pulse plating method.

### Claim 4 (depends on 3)

The method of claim 3, wherein the pulse plating method comprises:
a current density of 45-200 ASF;
a pulse frequency of 1-1200 Hz;
an on time of 0.3-3.0 ms;
an off time being 0.5-3.0 ms; and
a duty cycle of 10-50%.

### Claim 5

A method of electroplating a nanomaterial, comprising the successive steps of:
activating a surface of a substrate by a plurality of first counter flow conditioning rinses using a solution of acetone and a solution of an alcohol,
rinsing the activated surface of the substrate;
drying the activated surface of the substrate using a nitrogen gas;
conditioning the activated surface of substrate using a desmear solution comprising a concentration of 15% conditioner;
rinsing the activated surface of the substrate using a deoxidation solution comprising a concentration of 30% deoxidant;
conditioning the activated surface of substrate using a plurality of second counter flow rinses;
rinsing the activated surface of the substrate using a second deoxidation solution comprising a concentration of 10% deoxidant;
rinsing the activated surface of the substrate using a plurality of third counter flow conditioning rinses;
depositing electrolytic copper and electrolytic nickel metal to the activated surface of the substrate;
electroplating a gold strike metal to the activated surface of the substrate of the substrate; and
electroplating a nano-silver nanoparticle to the activated surface of the substrate
wherein
the substrate comprises a brass material or a leaded brass alloy;
the nano-silver nanoparticle comprises a molecular formula of [Ag25(thiolate)18]−;
the electroplating utilizes an electroplating solution,
the electroplating solution has a pH level of 3.5-6.5; and
the electroplating comprises a rate of deposition of 0.0001 μm/hr.

### Claim 6 (depends on 5)

The method of claim 5, wherein the electroplating a nano-silver nanoparticle uses a pulse plating method.

### Claim 7 (depends on 5)

The method of claim 5, wherein
the electroplating a nano-silver nanoparticle comprises a pulse electroplating method;
the pulse electroplating method comprises a plurality of cycles; and
each cycle of the plurality of cycles is configured to deposit a material comprising a smaller grain size compared to a prior cycle of the plurality of cycles.

### Claim 8 (depends on 7)

The method of claim 7, wherein the pulse electroplating comprises:
a current density of 45-200 ASF;
a pulse frequency of 1-1200 Hz;
the plurality of pulse cycles each comprising an on time of 0.3-3.0 ms and an off time of 0.5-3.0 ms; and
a duty cycle being range from 10% to 50%.

### Claim 9 (depends on 7)

The method of claim 7, wherein the pulse electroplating
comprises a rate of deposition of 0.0001 μm/hr;
is performed at a temperature of 120-140° F.; and
comprises a non-cyanide acidic silver electroplating bath solution having a pH of 3.5-6.5 and comprising:
a soluble silver salt;
a thiosulfate complex at 200-500 g/L;
trisodium citrate;
[Ag25(thiolate)18]− nanoparticles at 0.5-10 g/L;
one or more of
silver nitride at 20-120 g/L;
trisodium citrate at 10-100 g/L;
sodium hydroxide at 5-75 g/L;
sodium nitride at 10-100 g/L;
sodium sulfate at 10-100 g/L;
a monosaccharide at 1-5 g/L;
benzoic acid at 1-10 g/L; and
a sodium thiosulfate complex at 200-500 g/L.

### Claim 10 (depends on 9)

The method of claim 9, wherein the substrate comprises a beryllium copper alloy.