JPH0711448A - Catalytic solution for electroless plating selective to copper-based material - Google Patents

Abstract

PURPOSE:To subject only a Cu-based material in electronic parts to selective electroless plating with a metal by treating the electronic parts with a catalytic soln. for electroless plating contg. a Pd compd. and halide or sulfate of an alkali metal or an alkaline earth metal. CONSTITUTION:A printed board composed of an insulator and a Cu-based conductor is immersed in a catalytic aq. soln. contg. 0.0001-0.5mol/l Pd compd. such as (NH4)2(PdCl6) and 0.1-10mol/l at least one of halides or sulfates of alkali metals such as Na and K or alkaline earth metals such as Ca and Mg to activate the Cu-based conductor and then the printed board is immersed in an electroless plating bath such as an Ni, Pd or Pd-Ni plating bath. A plating layer of Ni, Pd, Pd-Ni, etc., is stably and selectively formed by electroless plating only on the Cu-based conductor of the printed board without causing bridging or skipping phenomenon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper-based material selection type electroless plating catalyst solution.

[0002]

2. Description of the Related Art When electroless plating of Ni, Pd, Pd-Ni, etc. using a hypophosphite compound as a reducing agent is applied to a copper-based material, it is usually used for reducing precipitation of a plating film. After applying a Pd compound as a catalyst on the material, electroless plating is performed. In such a case, the catalyst application method includes two-step treatment with SnCl ₂ solution and PdCl ₂ solution, P
For example, treatment with a dCl ₂ / SnCl ₂ mixed system acidic aqueous hydrochloric acid solution is performed. However, when these treatment methods are applied to a printed circuit board, a ceramic substrate, a chip component or the like in which an insulator and a conductor are integrated, all of the insulating portion and the conductor portion are catalytically activated. As a result, the entire surface is plated in the electroless plating process, and the plating film cannot be formed only on the conductor portion. There is also known a method of catalytically activating a copper-based material by using an acidic aqueous solution of PdCl ₂ in hydrochloric acid. In this case as well, a part of the catalyst component is adsorbed on the insulator part, and the insulator part is formed during the plating process. However, there is a problem that a bridge (plating bridge) phenomenon occurs in which the conductors are partially coupled to each other when a plating film is partially formed on the surface of the conductor and the gap between the conductors is narrow.

As a countermeasure against this, measures have been taken to raise the pH to weaken the catalytic activity, but even if the pH is raised to about 5, the plating bridge cannot be eliminated, while the pH is 6
In the case of the above, colloidal precipitation occurs, which makes practical handling difficult.

Further, the concentration of PdCl ₂ is reduced to weaken the catalytic activity, but in this case, the plating bridge disappears, but on the contrary, the catalytic activity becomes too weak and a part of the plating occurs. There is a problem of causing a phenomenon that cannot be attached (skip phenomenon).

[0005]

In view of the above-mentioned state of the art, the inventor of the present invention is capable of selectively activating only copper-based materials and does not cause skipping phenomenon, bridging phenomenon, etc. We have conducted extensive research to find a catalyst for plating. As a result, it has been found that the above object can be achieved by a catalyst liquid prepared by combining a palladium compound and at least one compound selected from a specific halide and a sulfate, and the present invention has been completed here. It was

That is, the present invention provides (i) a palladium compound 0.0001 to 0.5 mol / l, and (ii) an alkali metal halide, an alkali metal sulfate, an alkaline earth metal halide, and an alkali. 0.1 to 10 mol / l of at least one compound selected from earth metal sulfate, ammonium halide and ammonium sulfate
The present invention relates to a copper-based material selection type electroless plating catalyst solution comprising an aqueous solution containing

The palladium compound used in the catalyst solution of the present invention is not particularly limited, and in addition to the water-soluble palladium compound, a palladium compound which can be dissolved in an acid to form an aqueous solution can be used. Specific examples of palladium compounds suitable for use in the present invention include (NH ₄ ) ₂
[PdCl ₆ ], (NH ₄ ) ₂ [PdCl ₄ ], [PdCl
₂ (NH ₃ ) ₂ ], [PdI ₂ (NH ₃ ) ₂ ], [Pd (NO
₂ ) ₂ (NH ₃ ) ₂ ], K ₂ [PdCl ₆ ], K ₂ [PdC
l ₄ ], K ₂ [Pd (NO ₂ ) ₄ ], Na ₂ [PdCl ₄ ],
Na ₂ [Pd (NO ₂ ) ₄ ], PdBr ₂ , PdCl ₂ , P
dI ₂ , Pd (NO ₃ ) ₂ .2H ₂ O, PdO, PdS
O ₄ , PdS, [Pd (NH ₃ ) ₄ ] Cl ₂ , [Pd (NH
₃ ) ₄ ] (NO ₃ ) ₂ , Pd (C ₂ H ₃ O ₂ ) ₂ , Pd (N
O _{3) 2,} can be cited _{[Pd (NH 3) 4]} (OH) 2 and the like. The addition amount of the palladium compound is 0.0001.
To about 0.5 mol / l, preferably 0.0005 to 0.
It may be about 1 mol / l, and if it is less than 0.0001 mol / l, the skip phenomenon tends to occur, and 0.5 mol / l
If it exceeds, it is uneconomical, which is not preferable.

In the catalyst solution of the present invention, at least one compound selected from alkali metal halides, alkali metal sulfates, alkaline earth metal halides, alkaline earth metal sulfates, ammonium halides and ammonium sulfates. Needs to be used in combination with a palladium compound.

Examples of alkali metals suitable for use in the catalyst solution of the present invention include potassium and sodium, examples of alkaline earth metals include calcium and magnesium, and examples of halogen include chlorine, iodine and bromine. It can be illustrated. Preferred specific examples of the compound used in combination with the palladium compound include potassium chloride, magnesium chloride, calcium chloride, ammonium chloride, potassium iodide, potassium bromide, potassium sulfate, sodium sulfate, ammonium sulfate and the like. These compounds can be used alone or in appropriate combination, and the amount thereof is about 0.1-10 mol / l, preferably 0.5-.
It may be 5 mol / l. If the amount used is less than 0.1 mol / l, the bridge phenomenon is likely to occur, and if it exceeds 10 mol / l, it may not be completely dissolved, which is not preferable.

The method for preparing the catalyst solution of the present invention is not particularly limited, and for example, a method of directly adding a palladium compound to an aqueous solution containing a halide, a sulfate or the like to dissolve it, or a HCl compound as a solubilizing agent , H ₂ SO ₄ or the like dissolved in an acid and mixed with an aqueous solution containing a halide, a sulfate or the like.

The pH of the catalyst solution of the present invention is not particularly limited, but when adjusting the pH, an acid such as HCl or H ₂ SO ₄ or an alkali compound such as NaOH is used as necessary. Good.

If necessary, a chelate compound can be added to the catalyst solution of the present invention, whereby the catalyst solution can be kept more stable. Specific examples of the chelate compound include ethylenediaminetetraacetic acid (EDTA),
Ethylenediaminetetraacetic acid disodium salt (EDTA ・ 2
Na), hydroxyethyl ethylenediamine triacetic acid (H
EDTA), diethylenetriaminepentaacetic acid (DTP
A), triethylenetetramine hexaacetic acid (TTHA), ethylenediaminetetrapropionic acid, ethylenediaminetetramethylenephosphonic acid, diethylenetriaminepentamethylenephosphonic acid, nitrilotriacetic acid (NTA), iminodiacetic acid (IDA), iminodipropionic acid (ID
P), aminotrimethylenephosphonic acid, aminotrimethylenephosphonic acid pentasodium salt, methylamine, ethylamine, propylamine, dimethylamine, trimethylamine, dimethylethylamine, benzylamine, 2-
Naphthylamine, isobutylamine, isoamylamine, methylenediamine, ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, diethylenetriamine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine, cinnamylamine, p-methoxycinnamic Luamine, ammonia, 1-hydroxyethylidene-
1,1-diphosphonic acid, 1-hydroxyethylidene-
1,1-diphosphonic acid trisodium salt, citric acid, tartaric acid, malic acid, malonic acid, glycine, alanine, N-methylglycine, glycosamine, dimethylglycine, hydantoic acid, aminovaleric acid, β-alanine, valine,
Norvaline, leucine, norleucine, isoleucine,
Serine, cysteine, asparagine, aspartic acid,
Glutamic acid, ornithine, lysine, arginine, glutamine, diaminopropionic acid, citrulline, hydroxy-L-lysine, diaminobutyric acid, aminoadipic acid, kanaline, kynurenine, diaminopimelic acid, homocysteine, histidine, methionine, aspartyl-histidine, alanyl-alanine , Alanyl-β-alanine,
β-alanyl-β-alanine, glycyl-lysine, alanyl-ornithine, lysyl-lysine, ornithyl-ornithine, glycyl-ornithine, β-alanyl-lysyl-lysine, ornityl-lysyl-lysine, glycyl-ornithyl-ornithine, imidazoline, 2,4,5-Triphenyl-2-imidazoline, 2,2'-bis (2-
Imidazoline), pyridine, morpholine, bipyridyl,
Examples thereof include pyrazole and triazine.

Further, a nonionic, cationic, anionic, amphoteric surface active agent may be added to the catalyst solution, whereby the surface tension of the catalyst solution is lowered and the surface of the copper-based material is reduced. The catalytic activity of can be made uniform. Furthermore, the addition of thioureas can lower the deposition potential of the copper-based material and accelerate the substitution with palladium. Examples of thioureas include thiourea, dimethylthiourea, trimethylthiourea, allylthiourea, acetylthiourea,
Examples thereof include ethylene thiourea and phenyl thiourea.
Further, as a pH buffering agent, hydrochloric acid-potassium chloride, potassium hydrogen phthalate-hydrochloric acid, potassium hydrogen phthalate-sodium hydroxide, potassium dihydrogen phosphate-sodium hydroxide, boric acid-sodium hydroxide, sodium hydrogen carbonate-
Sodium hydroxide, disodium hydrogen phosphate-sodium hydroxide, sodium hydroxide-potassium chloride, tris (hydroxymethyl) aminomethane-hydrochloric acid, sodium acetate-acetic acid, etc. can also be added. The surfactants, thioureas and pH buffers can be used alone or in an appropriate mixture as needed. Chelate compounds, surfactants, thioureas and pH buffers are not essential components in the catalyst liquid of the present invention, but in order to effectively exert the effect of addition, the amount of chelate compound added is The addition amount of the surfactant is preferably about 0.01 to 2 mol / l, the addition amount of the surfactant is preferably about 0.01 to 10 g / l, and the addition amount of the thioureas is 0.0
The amount of the pH buffer added is preferably about 1 to 3 mol / l, and the addition amount of the pH buffer is preferably about 0.01 to 1 mol / l.

The catalyst solution of the present invention selectively activates a copper-based material, and by using this catalyst solution, an insulator and a conductor such as a printed circuit board, a ceramic substrate, and a chip component are integrated. Also for the material, only the copper-based material can be selectively catalytically activated to perform electroless plating only on the copper-based material portion.

As the copper-based material to be applied, copper, brass, phosphor bronze, nickel silver and the like can be mentioned. These materials themselves or various substrates are plated with these materials by plating, vapor deposition, paste or the like. It can be applied to those with a coating of a system material.

The treatment method with the catalyst solution of the present invention may be the same as the treatment with an ordinary catalyst solution, and the solution temperature is about 10 to 90 ° C
Preferably, the object to be treated may be immersed in the catalyst solution at about 25 to 70 ° C. for about 10 seconds to 10 minutes. If the liquid temperature is too low, the skip phenomenon is likely to occur, and if the liquid temperature is too high, the bridge phenomenon is likely to occur.

After activation with the catalyst solution, electroless plating is performed to selectively form a plating film on the copper-based material. The catalyst solution of the present invention is not particularly limited as an electroless plating solution, but is particularly effective when an electroless plating solution such as Ni, Pd, Pd-Ni using a hypophosphorous acid compound as a reducing agent is used. .

When the catalyst solution of the present invention is used, pretreatments such as degreasing and pickling may be carried out by conventional methods, and electroless plating conditions may be usual.

[0019]

EFFECTS OF THE INVENTION By using the catalyst solution of the present invention, it is possible to selectively perform electroless plating only on a copper-based material, and a material consisting of an insulator and a conductor such as a printed circuit board, a ceramic substrate, and a chip part. Against the skip phenomenon,
It is possible to form a good plating film only on the conductor portion without causing a bridge phenomenon or the like.

[0020]

EXAMPLES The present invention will be described in more detail with reference to examples.

[0021]

[Example 1] A hole was drilled in a glass epoxy copper clad laminate,
After performing electroless copper plating and electrolytic copper plating, an etching resist layer is formed, and then etching, etching resist layer peeling, solder resist printing, character printing,
The following treatment was performed on a 100 × 170 × 16 mm copper-plated through-hole printed wiring board for mixed mounting of double-sided surface mounting components and single-sided insertion type components obtained through the outer shape processing step.

After the printed wiring board is immersed in degreasing and pickled,
60 g of ammonium persulfate aqueous solution at 30 ℃
After soaking for 2 seconds to perform soft etching, and then pickling, a catalyst was applied under the catalyst liquid composition and conditions shown in Table 1. Then, electroless plating of each of Ni, Pd, and Pd-Ni having the following compositions was performed to examine whether or not the skip phenomenon and the bridge phenomenon occurred. In the case of evaluating the skip phenomenon, the plating time was 30 seconds, and in the case of evaluating the bridge phenomenon, the plating time was 30 minutes.

Electroless Ni plating solution Nickel sulfate (hexahydrate) 20 g / l Malic acid 20 g / l Sodium hypophosphite (monohydrate) 30 g / l Lead acetate (trihydrate) 1 mg / l pH (ammonia water 6 bath temperature 85 ° C. deposition rate approximately 8 μm / h electroless Pd plating solution palladium chloride 0.01 mol / l ethylenediamine 0.08 mol / l thiodiglycolic acid 20 mg / l sodium hypophosphite 0.06 mol / L pH 8 Bath temperature 50 ° C Deposition rate Approximately 1 µm / h Electroless Pd-Ni plating solution Palladium chloride 0.01 mol / l Nickel chloride 0.1 mol / l Ethylenediamine 0.08 mol / l Thiodiglycolic acid 20 mg / l Sodium hypophosphite 0.06 mol / l pH 8 Bath temperature 50 ° C. Deposition rate approx. 2 μm / h

[0024]

[Table 1]

As a result of the above test, No. 1 containing neither halide nor sulfate was added. When the catalyst solutions 1 to 6 were used, the skip phenomenon was not observed in each of the Ni, Pd, and Pd-Ni plating films, but the bridging phenomenon was often observed. On the other hand, N which is the catalyst liquid of the present invention
o. When using the catalyst solutions of 7 to 28, Ni, Pd,
For each Pd-Ni plating film, the plating film can be formed only on the copper-plated portion of the printed wiring board,
No skipping phenomenon or bridging phenomenon was observed.

Claims (1)

[Claims] 1. (i) Palladium compound 0.0001-
0.5 mol / l, and (ii) at least one selected from alkali metal halides, alkali metal sulfates, alkaline earth metal halides, alkaline earth metal sulfates, ammonium halides and ammonium sulfates. 2. A copper-based material selection type electroless plating catalyst solution comprising an aqueous solution containing the compound of 0.1 to 10 mol / l.