Pretreatment solution for providing catalyst for electroless plating, pretreatment method using the solution, and electroless plated film and/or plated object produced by use of the method

• US 20040043153A1
• Filed: 08/07/2003
• Published: 03/04/2004
• Est. Priority Date: 08/23/2002
• Status: Active Grant

• Current Assignee: Daiwa Fine Chemicals Co,, Ltd.
• Original Assignee: Daiwa Fine Chemicals Co,, Ltd.
• Inventors: Hyun, Kim Dong, Nakao, Seiichiro, Yoshimoto, Masakazu, Nawafune, Hidemi, Obata, Keigo, Tsuji, Hidenori, Kitamura, Shingo, Okuhama, Yoshiaki
• Granted Patent: US 7,166,152 B2
• Time in Patent Office: Days
• US Class Current: 427/307
• CPC Class Codes: C23C 18/28 Sensitising or activating

Abstract

A pretreatment solution for providing a catalyst for electroless plating and a pretreatment method using the solution are provided.

The pretreatment solution comprises a silver colloidal solution containing, as essential components, at least the following components (I), (II) and (III):

(I) silver colloidal particles,

(II) one or more ions selected from an ion of a metal having an electric potential which can reduce a silver ion to metal silver in the solution and an ion oxidized at the time of reduction of the silver ion, and

(III) one or more ions selected from a hydroxycarboxylate ion, a condensed phosphate ion and an amine carboxylate ion,

the silver colloidal particles (I) being produced by the ion of the metal (II) having an electric potential which can reduce a silver ion to metal silver. When an object to be plated is pretreated by use of the pretreatment solution, provision of an effective catalyst for electroless plating is achieved.

Claims

1. A pretreatment solution for providing a catalyst for electroless plating, comprising a silver colloidal solution containing, as essential components, at least the following components (I), (II) and (III):

(I) silver colloidal particles,

(II) one or more ions selected from an ion of a metal having an electric potential which can reduce a silver ion to metal silver in the solution and an ion oxidized at the time of reduction of the silver ion, and

(III) one or more ions selected from a hydroxycarboxylate ion, a condensed phosphate ion and an amine carboxylate ion,

the silver colloidal particles (I) being produced by the ion of the metal (II) having an electric potential which can reduce a silver ion to metal silver.

2. The pretreatment solution of claim 1, further containing (IV) one or more ions selected from ions of metals of atomic numbers 26 to 30 (or metals of atomic numbers 27 to 30 when the metal (II) is iron).

3. The pretreatment solution of claim 1 or 2, wherein the hydroxycarboxylic acid is one or more carboxylic acids selected from citric acid, tartaric acid, lactic acid, malic acid, glycolic acid and gluconic acid.

4. The pretreatment solution of any of claims 1 to 3, wherein the condensed phosphoric acid is pyrophosphoric acid.

5. The pretreatment solution of any of claims 1 to 4, wherein the amine carboxylic acid is EDTA or/and NTA.

6. The pretreatment solution of any of claims 1 to 5, wherein the metal having an electric potential which can reduce a silver ion to metal silver in the solution is tin, iron or titanium.

7. The pretreatment solution of any of claims 1 to 6, wherein the metal of atomic numbers 26 to 30 is iron.

8. The pretreatment solution of any of claims 1 to 7, wherein the silver colloidal solution further contains one or more ions of acids selected from:

(i) sulfuric acid, hydrochloric acid, nitric acid, fluoroboric acid, fluorosilicic acid, phosphoric acid, sulfamic acid, and

(ii) an organic sulfonic acid.

9. The pretreatment solution of any of claims 1 to 8, wherein the organic sulfonic acid (ii) is one or more acids selected from an aliphatic sulfonic acid represented by the following general formula (A):

(X₁)_n—

R₁—

SO₃H

wherein R₁ represents an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms or an alkynyl group having 2 to 5 carbon atoms;

X₁ represents hydrogen, a hydroxyl group, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an aryl group, an aralkyl group, a carboxyl group or a sulfonic group and may be present at any position of R₁; and

n is an integer of 0 to 3,

or the following general formula (B);

wherein R₂ represents an alkyl group having 1 to 5 carbon atoms or an alkylene group having 1 to 3 carbon atoms, the alkylene group may have a hydroxyl group at any position;

X₂ represents halogen, i.e., chlorine or/and fluorine, chlorine or/and fluorine may substitute for one to all hydrogen atoms coordinated to the alkyl or alkylene group, and chlorine or fluorine as a substituent may be present at any position;

Y represents hydrogen or a sulfonic group, and the number of substitutions of the sulfonic group represented by Y is 0 to 2,

and an aromatic sulfonic acid represented by the following general formula (C);

wherein X₃ represents a hydroxyl group, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an aryl group, an aralkyl group, an aldehyde group, a carboxyl group, a nitro group, a mercapto group, a sulfonic group or an amino group, and together with a benzene ring, two X₃s can form a naphthalene ring; and

m is an integer of 0 to 3.

10. The pretreatment solution of any of claims 1 to 9, wherein the silver colloidal solution further contains one or more saturated aliphatic alcohols which have 10 carbon atoms or less and only a hydroxyl group as a substituent, selected from a linear saturated aliphatic mono-, di- or tri-alcohol represented by the following general formula (1):

C_nH<sub>2n+2−

m</sub>(X)_m

wherein n is an integer which is larger than m but not larger than 10;

m represents an integer of 1 to 6;

Xs each are hydrogen or a hydroxyl group and may be the same or different, at least one of Xs is a hydroxyl group, and Xs may be bonded to any positions of any carbon atoms; and

the carbon chain may be branched,

a cyclic saturated aliphatic mono-, di- or tri-alcohol represented by the following general formula (2);

C_nH<sub>2n−

m</sub>(X)_m

wherein n is an integer which is larger than m but not larger than 10;

m represents an integer of 1 to 6;

Xs each are hydrogen or a hydroxyl group and may be the same or different, at least one of Xs is a hydroxyl group, and Xs may be bonded to any positions of any carbon atoms; and

the carbon chain may be branched,

and a linear saturated aliphatic mono-, di- or tri-alcohol having an ether linkage represented by the following general formula (3);

C_nH<sub>2n+2−

m</sub>O₁(X)_m

wherein n is an integer which is larger than m but not larger than 10;

m represents an integer of 1 to 4;

l represents an integer of not larger than n−

2;

Xs each are hydrogen or a hydroxyl group and may be the same or different, at least one of Xs is a hydroxyl group, and Xs may be bonded to any positions of any carbon atoms;

the carbon chain may be branched; and

O represents ether oxygen and is present between any two carbon atoms.

11. The pretreatment solution of any of claims 1 to 10, wherein the saturated aliphatic alcohols which have 10 carbon atoms or less and only a hydroxyl group as a substituent are one or more alcohols selected from methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, t-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 1,6-hexanediol, 2,5-hexanediol, 1,2-ethanediol (ethylene glycol), 1,2-propanediol (propylene glycol), 1,3-propanediol (trimethylene glycol), 1,2,3-propanetriol (glycerol) and sorbitol.

12. The pretreatment solution of any of claims 1 to 11, wherein the silver colloidal solution further contains a colloid dispersant.

13. The pretreatment solution of any of claims 1 to 12, wherein the silver colloidal solution further contains a sulfur-containing compound.

14. The pretreatment solution of any of claims 1 to 13, wherein the silver colloidal solution further contains a palladium colloid in an amount of not larger than {fraction (1/100)} of the silver colloid.

15. The pretreatment solution of any of claims 1 to 14, wherein the silver colloidal solution further contains a pH buffer.

16. The pretreatment solution of any of claims 1 to 15, wherein the silver colloidal solution further contains one or more reducing compounds.

17. The pretreatment solution of any of claims 1 to 16, wherein the reducing compound is an alkyl or phenyl phosphine.

18. The pretreatment solution of any of claims 1 to 17, wherein the alkyl phosphine is tris(3-hydroxypropyl)phosphine.

19. The pretreatment solution of any of claims 1 to 18, wherein the reducing compound is a phenolic compound or ascorbic acid.

20. The pretreatment solution of any of claims 1 to 19, wherein the silver colloidal solution has a pH of 3 to 11.

21. The pretreatment solution of any of claims 1 to 20, wherein the silver colloidal solution is prepared by adjusting the pH of a solution containing at least the components (II) and (III) and, as required, the component (IV) to 3 to 11 in advance and then mixing a solution having a silver compound dissolved therein into the solution.

22. The pretreatment solution of any of claims 1 to 20, wherein the silver colloidal solution is prepared by mixing a solution having a silver compound dissolved therein into a solution containing at least the components (II) and (III) and, as required, the component (IV) and then adjusting the pH of the resulting solution to 3 to 11.

23. The pretreatment solution of any of claims 1 to 19, wherein the silver colloidal solution has a pH below 3.

24. The pretreatment solution of any of claims 1 to 19 or 21, wherein after prepared by the method of claim 21, the silver colloidal solution has its pH adjusted to below 3.

25. The pretreatment solution of any of claims 1 to 24, which is prepared by heating the solution to at least 50°

C. at the time of addition of the solution having a silver compound dissolved therein.

26. The pretreatment solution of any of claims 1 to 25, which is prepared by leaving the resulting solution to stand for at least 24 hours after addition of the solution having a silver compound dissolved therein.

27. The pretreatment solution of any of claims 1 to 26, which is prepared by heating the resulting solution to at least 50°

C. when it is left to stand for at least 24 hours.

28. The pretreatment solution of any of claims 1 to 27, wherein the silver colloidal solution is a solution prepared by additionally adding one or more acids or salts thereof selected from a hydroxycarboxylic acid, condensed phosphoric acid, an amine carboxylic acid (and salts thereof) after addition of the solution having a silver compound dissolved therein.

29. A pretreatment method for providing a catalyst for electroless plating, comprising a step of immersing an object to be plated in the silver colloidal solution of any of claims 1 to 28 or coating the solution on the object to be plated.

30. The pretreatment method of claim 29, further comprising a step of immersing the resulting object in a solution containing a reducing agent or an acid solution or coating the solution on the resulting object subsequently to the immersion or coating step.

31. The pretreatment method of claim 30, wherein the solution containing a reducing agent is a solution containing any of a hypophosphite, a dimethylamine borane, sodium borohydride, a tetravalent titanium ion and a divalent cobalt ion.

32. The pretreatment method of any of claims 29 to 31, further comprising a drying step subsequently to the immersion or coating step or subsequently to the step of immersing the object in the solution containing a reducing agent or the acid solution or coating the solution on the object.

33. The pretreatment method of any of claims 29 to 32, further comprising a degreasing step, an etching step or/and a conditioning step prior to the immersion or coating step.

34. An electroless plating method comprising a step of giving electroless plating to an object to be plated which has been treated by the pretreatment method of any of claims 29 to 33.

35. The electroless plating method of claim 34, wherein the electroless plating is copper plating or silver plating.

36. An electroless plating method comprising using the silver colloidal pretreatment solution of any of claims 1 to 28 while carrying out electrolysis using tin as an anode.

37. The electroless plating method of claim 36, wherein a membrane is used at the time of electrolysis of the silver colloidal solution.

38. The electroless plating method of claim 37, wherein the membrane is an ion exchange membrane.

39. An electroless plated film or/and electroless plated object produced by use of the plating method of any of claims 34 to 38.

40. An electric/electronic material (component), a cell material (component) and an optical communication material (component) produced by use of the electroless plated film or/and electroless plated object of claim 39.

41. An electric/electronic apparatus, a cell and an optical communication device manufactured by use of the electric/electronic material (component), the cell material (component) and the optical communication material (component) of claim 40.