Pretreatment of iron-based substrates for electroless plating

Patent metadata

Field	Value
Publication number	US-2018187309-A1
Application number	US-201715398809-A
Country	US
Kind code	A1
Filing date	Jan 5, 2017
Priority date	Jan 5, 2017
Publication date	Jul 5, 2018
Grant date	—

Abstract

A method of electrolessly plating an iron-based substrate, including immersing an iron-based substrate in an acidic solution, immersing the iron-based substrate in a basic complexing solution, immersing the iron-based substrate in a catalytic metal solution including a catalytic metal, and immersing the iron-based substrate in an electroless nickel plating solution or an electroless cobalt plating solution.

First claim

What is claimed is:

1 . A method of electrolessly plating an iron-based substrate, comprising:
immersing an iron-based substrate in an acidic solution; immersing the iron-based substrate in a basic complexing solution; immersing the iron-based substrate in a catalytic metal solution including a catalytic metal; and immersing the iron-based substrate in an electroless nickel plating solution or an electroless cobalt plating solution.

2 . The method of claim 1 , wherein the acidic solution is a hydrochloric acid solution.

3 . The method of claim 2 , wherein the hydrochloric acid solution has a concentration in the range of about 5% to about 20% by weight.

4 . The method of claim 3 , wherein the acidic solution is a 10% hydrochloric acid solution.

5 . The method of claim 1 , wherein the basic complexing solution is a potassium sodium tartrate solution or sodium citrate solution with a pH in the range of 7 to about 9.

6 . The method of claim 5 , further comprising maintaining the pH of the potassium sodium tartrate solution or sodium citrate solution at a pH of about 8 with a 2 molar sodium hydroxide solution or a 10% hydrochloric acid solution to prevent re-oxidation.

7 . The method of claim 1 , wherein the catalytic metal is palladium.

8 . The method of claim 7 , wherein the catalytic metal solution contains 55 ppm Pd from dissolved PdSO 4 and 10% sulfuric acid.

9 . The method of claim 1 , further comprising rinsing the iron-based substrate with deionized water.

10 . The method of claim 1 , wherein the electroless nickel plating solution includes a hydrated nickel sulfate salt, and sodium hypophosphite (NaH 2 PO 2 ), dimethylamine borane (DMAB), or sodium borohydride (NaBH 4 ).

11 . A method of nickel plating an iron-based substrate, comprising:
immersing an iron-based substrate in a 10% hydrochloric acidic solution; immersing the iron-based substrate subsequently in a sodium potassium tartrate (KNaC 4 H 4 O 6 ) or sodium citrate (Na 3 C 6 H 5 O 7 ) solution with a pH of about 8; immersing the iron-based substrate subsequently in a catalytic metal solution including dissolved PdSO 4 and a 10% sulfuric acid solution; and immersing the iron-based substrate in an electroless nickel plating solution prepared using a nickel sulfate salt and sodium hypophosphite (NaH 2 PO 2 ).

12 . The method of claim 11 , further comprising subsequently rinsing the iron-based substrate in deionized water.

13 . The method of claim 12 , wherein the iron-based substrate is immersed in the electroless nickel plating solution for about 1 hour, where the electroless nickel plating solution is maintained at a temperature of about 95° C. for the 1 hour.

14 . The method of claim 11 , wherein the iron-based substrate is immersed in the catalytic metal solution for a duration of about 2 minutes.

15 . The method of claim 11 , wherein the iron-based substrate is immersed in the sodium potassium tartrate (KNaC 4 H 4 O 6 ) or sodium citrate (Na 3 C 6 H 5 O 7 ) solution for a duration of about 5 minutes to about 10 minutes.

16 . The method of claim 11 , wherein the iron-based substrate is immersed in the 10% hydrochloric acidic solution for a duration of about 5 minutes.

17 . A method of nickel plating an iron-based substrate, comprising:
immersing an iron-based substrate in a 10% hydrochloric acidic solution; immersing the iron-based substrate subsequently in a potassium sodium tartrate solution with a pH of about 8; immersing the iron-based substrate subsequently in a catalytic metal solution including about 25 ppm to about 75 ppm Pd from dissolved PdSO 4 and 10% sulfuric acid; and immersing the iron-based substrate in an electroless nickel plating solution at a temperature in the range of about 20° C. to about 95° C., where the electroless nickel plating solution is prepared using a hydrated nickel sulfate salt (NiSO 4 ) and sodium hypophosphite (NaH 2 PO 2 ), dimethylamine borane (DMAB), or sodium borohydride (NaBH 4 ).

18 . The method of claim 17 , further comprising rinsing the iron-based substrate with deionized water before immersing the iron-based substrate in an electroless nickel plating solution.

19 . The method of claim 17 , wherein nickel plating is formed on the iron-based substrate by the electroless nickel plating solution, and the nickel plating has a phosphorus content of about 1% to about 20%.

20 . The method of claim 19 , further comprising heat treating the nickel plating.

Assignees

• IBM

Inventors

• Dimilia Doreen D
• Luo Yu
• Nowak Janusz J
• Romankiw Lubomyr T

Classifications

• C23C18/168

  Control of temperature, e.g. temperature of bath, substrate · CPC title

• C23C18/1844

  with use of organic or inorganic compounds other than metals, first · CPC title

• C23C18/34 Primary

  using reducing agents · CPC title

• C23C18/36

  using hypophosphites · CPC title

• C23C18/1637

  metallic substrate · CPC title