Electroless plating activation

Patent metadata

Field	Value
Publication number	US-11109493-B2
Application number	US-201916286352-A
Country	US
Kind code	B2
Filing date	Feb 26, 2019
Priority date	Mar 1, 2018
Publication date	Aug 31, 2021
Grant date	Aug 31, 2021

Abstract

A method of initiating and controlling electroless nickel plating on copper substrates carried into a plating bath on a continuous stainless steel web where the copper is electrically bussed or in physical contact with the steel is described. A bias current is applied to the plating bath and a feedback loop is established to determine initiation of plating as well as to ramp down the biasing current to prevent electro- or electroless plating of the web.

First claim

We claim:

1. An electroless method of plating a metal on a substrate comprising:
providing a substrate upon which to plate a metal, the substrate being carried by a web;
introducing the web, including the substrate upon which to plate the metal, into a plating bath;
establishing a voltage existing in said bath by placing an electrode in contact with the bath and in contact with a roller contacting the web outside the bath;
determining a reference voltage at which plating will initiate on the substrate; and,
applying a bias current to the web sufficient to initiate plating only on the substrate but not on the web.

2. The method of claim 1 , wherein the metal to be plated comprises nickel.

3. The method of claim 2 , wherein the substrate comprises copper.

4. The method of claim 1 , wherein the web comprises stainless steel.

5. The method of claim 2 , wherein palladium may be is provided in contact with the substrate of copper.

6. The method of claim 1 , wherein the step of supplying current controls the reference voltage.

7. The method of claim 1 , wherein the substrate upon which to plate the metal is a plurality of discrete copper traces.

8. The method of claim 1 , wherein the web is continuous, but the substrate upon which to plate the metal are discrete traces carried by the web.

9. The method of claim 1 , wherein the substrate is copper and the web is stainless steel.

10. The method of claim 9 , wherein the ratio of area of the substrate bussed to the area of the web affects the plating on the substrate.

11. The method of claim 1 , wherein the applying of bias current is adjusted to maintain a constant reference voltage to assure continuous initiation of plating as the web is fed into the bath.

12. The method of claim 1 , further comprising sensing of the reference voltage to determine plating initiation and ramping down the bias current to prevent electro- and electroless-hybrid plating.

13. The method of claim 4 , wherein the bias current is dependent on the state of passivation of the stainless steel web.

14. A method of electroless nickel plating only on a copper substrate carried by a continuous stainless steel web on not on the web itself comprising:
introducing a continuous stainless steel web into a plating bath;
wherein the plating bath comprises nickel to be plated on the substrate;
arranging a continuous substrate, or a plurality of spaced substrates, of copper bussed to the stainless steel web;
applying a bias current to the web to initiate the nickel plating on the copper substrate.

15. The method of claim 14 , further including the step of establishing a reference voltage existing on the web in the bath.

16. The method of claim 15 , wherein the step of establishing the reference voltage comprises placing a reference electrode in contact with the bath containing the web near the point of entry of the web into the bath and measuring the voltage difference with a roller in contact with the web before it enters the bath.

17. The process of claim 14 , further comprising sensing the reference voltage to determine plating initiation and ramping down the bias current to prevent electro- or electroless-hybrid plating.

18. The method of claim 14 , further comprising adjusting the bias current to maintain a constant reference voltage to assure continuous initiation of plating on the copper substrate as the web is introduced into the bath.

19. The method of claim 14 , wherein palladium is placed in contact with the copper of the substrate.

20. A method of electroless nickel plating only on a copper substrate carried by a continuous stainless steel web and not on the web itself comprising:
introducing a continuous stainless steel web into a plating bath;
wherein the plating bath comprises nickel to be plated on the substrate;
arranging a continuous substrate, or a plurality of spaced substrates, of copper bussed to the stainless steel web;
establishing a voltage difference between the bath containing the stainless steel web and the web before it enters the bath by placing a reference electrode in contact with the bath;
applying a bias current to the web to initiate the nickel plating on the copper substrate;
sensing the voltage to determine plating initiation; and,
ramping down current to prevent electro- or electroless-hybrid plating.

Assignees

• Hutchinson Technology

Inventors

• Riemer Douglas P
• Fischer Kurt F

Classifications

• H05K3/4661 Primary

  Adding a circuit layer by direct wet plating, e.g. electroless plating; insulating materials adapted therefor (other insulating materials H05K3/387) · CPC title

• C23C18/1675

  Process conditions · CPC title

• C23C18/1671 Primary

  Electric field · CPC title

• C23C18/1831

  Use of metal, e.g. activation, sensitisation with noble metals · CPC title

• C23C18/32

  Coating with nickel, cobalt or mixtures thereof with phosphorus or boron (C23C18/50 takes precedence) · CPC title