Electroless Nickel Etch Chemistry, Method Of Etching And Pretreatment

Patent metadata

Field	Value
Publication number	US-2022127729-A1
Application number	US-202117512511-A
Country	US
Kind code	A1
Filing date	Oct 27, 2021
Priority date	Oct 28, 2020
Publication date	Apr 28, 2022
Grant date	—

Abstract

Etchant solutions, pretreatment and methods for etching electroless nickel on metallic materials are provided herein. More specifically, etchant solutions for selectively removing electroless nickel from the surface of metallic materials containing copper, and optionally as containing stainless steel, methods of etching and pretreatment are provided.

First claim

We claim:

1 . An etchant solution for treating metallic surfaces, the etchant solution comprising: hydrogen peroxide, sodium m-nitrobenzoate (NBCA) and ethylenediamine tetra acetic acid (EDTA).

2 . The etchant solution of claim 1 , wherein the concentration of hydrogen peroxide is from about 0.5 M to about 13 M.

3 . The etchant solution of claim 1 , wherein the concentration of sodium m-nitrobenzoate (NBCA) is from about 0.4 M to about 0.6 M.

4 . The etchant solution of claim 1 , wherein the concentration of ethylenediamine tetra acetic acid (EDTA) acid is from about 0.05 M to about 0.25 M.

5 . The etchant solution of claim 1 wherein the pH of the solution is in the range of about 3.9 to 5.0.

6 . The etchant solution of claim 1 wherein the etchant solution has a molar concentration in the range of about 3.0-4.0 M hydrogen peroxide, 0.4-0.5 M NBCA and 0.05-0.10 M EDTA.

7 . The etchant solution of claim 1 wherein the etchant solution has a concentration of about 1.9 vol % to 2.35 vol % hydrogen peroxide, 0.175 M to 0.235 M NBCA and 0.02 to 0.04 wt % EDTA.

8 . The etchant solution of claim 1 wherein the etchant solution has a concentration of about 15.0 wt % hydrogen peroxide, 8.5 wt % NBCA and 1.5 wt % EDTA.

9 . The etchant solution of claim 1 further including a pH buffer.

10 . A method of removing electroless nickel on at least one surface of a substrate, the substrate including copper and optionally stainless steel, comprising the steps of: exposing the substrate to an etchant solution comprising hydrogen peroxide, sodium m-nitrobenzoate (NBCA) and ethylenediamine tetra acetic acid (EDTA); and
etching the electroless nickel on the surface of the substrate to remove the electroless nickel.

11 . The method of claim 10 wherein the etching step does not substantially remove the copper.

12 . The method of claim 10 wherein the etching step is carried out at a temperature from about 25 to about 55° C.

13 . The method of claim 10 wherein the etching step is carried out for a time of about 1 to 15 minutes.

14 . The method of claim 10 wherein the electroless nickel is etched at an etch rate of about to about 25 nm/min to about 150 nm/min at a pH of above 3.9.

15 . The method of claim 10 wherein the etchant solution has a molar concentration in the range of about 3.0-4.0 M hydrogen peroxide, 0.4-0.5 M NBCA and 0.05-0.10 M EDTA.

16 . The method of claim 10 wherein the etchant solution wherein the etchant solution has a concentration of about 1.9 vol % to 2.35 vol % hydrogen peroxide, 0.175 M to 0.235 M NBCA and 0.02 M to 0.04 M EDTA.

17 . The method of claim 10 wherein the etchant solution has a concentration of about 15.0 wt % hydrogen peroxide, 8.5 wt % NBCA and 1.5 wt % EDTA.

18 . The method of claim 10 wherein the substrate is exposed to the etchant solution by any one or more of: immersing, spraying or dipping.

19 . A pretreatment solution for treating a metallic substrate having electroless nickel on the metallic substrate, comprising: oxalic acid and water.

20 . The pretreatment solution of claim 19 wherein the pretreatment solution has a concentration of oxalic in the range of 1.0 wt. % to 10.0 wt. %

21 . The pretreatment solution of claim 20 wherein the concentration of oxalic acid is in the range of about 5.0 wt. % to 8.0 wt. %.

22 . A method of removing electroless nickel on a surface of a substrate, comprising the steps of:
pretreating the surface of the substrate with a solution comprised of oxalic acid and water; and subsequently etching the surface of the substrate with an etchant solution comprised of hydrogen peroxide, sodium m-nitrobenzoate (NBCA) and ethylenediamine tetra acetic acid (EDTA).

23 . The method of claim 22 wherein the pretreating step is carried out for a time of about 10 seconds to 1 minute, and at a temperature of about 40° C.

24 . The method of claim 22 wherein the etching step is carried out for a time of about 1 to 2 minutes, and at a temperature of about 25° C.

25 . The method of claim 22 wherein the concentration of oxalic acid is in the range of about 5.0 wt. % to 8.0 wt. %.

26 . The method of claim 22 wherein the etchant solution wherein the etchant solution has a concentration of about 0.5 M to 13 M hydrogen peroxide, 0.3 M to 0.6 M NBCA, and 0.05 to 0.25 M EDTA.

Assignees

• Hutchinson Technology

Inventors

• Horner Matthew J
• Vangara Gowtham V
• Riemer Douglas P

Classifications

• C23F1/28

  for etching iron group metals · CPC title

• C23F1/44 Primary

  Compositions for etching metallic material from a metallic material substrate of different composition · CPC title

• C23F1/30 Primary

  for etching other metallic material · CPC title