JPS6096764A - Plating method of copper and copper alloy - Google Patents

Abstract

PURPOSE:To plate copper and copper alloy simply and rapidly without generating problems of toxicity at the time of plating and the contamination of a plating bath, by performing treatment by a solution containing an org. complex of a metal belonging to the Group VIII of the Periodic Table soluble in an org. solvent at a temp. equal to or less than the decomposition temp. of said complex. CONSTITUTION:An organometallic complex represented by formula MmLn [wherein (m) is an integer of 1-4 and (n) is an integer of 2-12] showing solubility to an org. solvent and liberating a metal under heating is prepared. In this case, the aforementioned metal M is one belonging to the Group VIII of the Periodic Table and, as the ligand L, for example, tertiary phosphine is designated. In addition, as the org. solvent, for example, 1,1,2-trichloroethane is used. Herein, plating is applied to copper or a copper alloy by using a plating bath comprising an org. solvent solution of the aforementioned organometallic complex in such a state that copper or the copper alloy is heated to the inherent decomposition temp. of the organometallic complex. The resulting plating is stabilized and closely adhesive strength of plating is extremely excellent.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for plating copper and copper alloys by using an organometallic complex of Group Ⅰ of the periodic table that is soluble in an organic solvent and treating it with a solution containing the organometallic complex. It is related to.

Copper and copper alloys, especially copper, have been increasingly used in recent years mainly as conductive functional materials due to their good electrical and thermal conductivity.

That is, copper is widely used as printed circuit boards with copper foil circuits formed on resin substrates and various contact materials.

Various copper powders can also be used in thermosetting resins dissolved in solvents, such as phenol resins, epoxy resins, urethane resins, melamine resins, unsaturated polyester resins, etc., and thermoplastic resins.
For example, it is used to form a conductive circuit by dispersing it in an acrylic resin (hereinafter referred to as a binder) and making it into a paint, printing a circuit on a metal plate, ceramic plate, resin substrate, etc. using the paint, and then firing it. ing.

Similarly, the paint is also used as an electromagnetic shielding paint or a conductive adhesive for housings containing digital electronic circuits.

However, although copper has excellent electrical conductivity comparable to silver,
It has poor oxidation stability and is oxidized by air even at room temperature, producing copper oxide on the copper surface, which significantly reduces electrical conductivity.
Because of this phenomenon, the range of applications has been limited, despite the low cost and good electrical conductivity.

As for copper powder, since its surface area is larger than that of plate-like materials, it is more susceptible to oxidation, so improving its stability is extremely important.

Several proposals have been made regarding methods for stabilizing copper powder. For example, a method of obtaining a copper-silver composite powder by mechanically joining copper powder and silver powder, a method of electroless plating of copper powder with a stable metal, a method of plating with solder, various organic substances, such as long chain fatty acids. There are methods such as coating with carbon dioxide, contact stabilization with halogenated hydrocarbon compounds, etc.

Both methods are effective, but not perfect. - For example, electroless plating, especially when an alkali metal cyano compound is used in the plating solution, causes problems of toxicity in the working environment and contamination of the plating bath due to the elution of copper ions into the water-soluble plating solution during plating. There are drawbacks such as. Also, metal may fall off during dispersion and blending with a binder.

The present inventors have made earnest efforts to solve these drawbacks and have completed the present invention.

That is, the present invention relates to a method of plating copper and copper alloys by using an organometallic complex of Group I of the Periodic Law that is soluble in an organic solvent, and heating a solution containing the organometallic complex to a temperature below the decomposition temperature of the organometallic complex. It is.

According to the present invention, copper and copper alloys can be plated and stabilized very easily and quickly without problems such as toxicity during plating or contamination of the plating bath, and the adhesion strength of the plating is extremely excellent. There is.

Next, the content of the present invention will be explained in detail.

The organometallic complex used in the present invention is selected from one that exhibits solubility in organic solvents and releases metal upon heating, and has the general formula MmLn (m is an integer from 1 to 4, and n is an integer from 2 to 12). It is indicated by.

The metal M is particularly preferably a metal of Group I of the periodic table, and examples of the ligand include tertiary phosphine, tertiary phosphite, -carbon oxide, linear or cyclic olefin, conjugated olefin, aryl compound, Heterocyclic compounds, organic cyanogen compounds, organic isonitrile compounds, organic mercapto compounds, or combinations of one or more of compounds having alkyl groups, vinyl groups, allyl groups, ethyridine groups, acyl groups, etc. may be halogen, oxygen, hydrogen, nitrogen, etc.

There are no restrictions on the organic solvent as long as it dissolves the organometallic complex, but solvents that are toxic or have a strange odor should be avoided.
Solvents with boiling points above are preferred.

These solvents include halogenated hydrocarbon solvents such as 1.1.2-trichloroethane and 1.1.2.2-tetrachloroethane, and aromatic solvents such as xylene, mesitylene, and tetralin. , dimethylformamide, dimethyl sulfoxide, and the like.

Copper and copper alloys are particularly recommended as the metal to be plated in the present invention. Copper alloys include copper-zinc, copper-tin, copper-nisokel, copper-aluminum, copper-silver, copper-cadmium, copper-
It includes chromium, copper-silicon, copper-lead, copper-barium, etc.

The shape of the copper and copper alloy is not particularly limited, and any shape such as a plate, powder, or pipe can be used.

Of course, partial plating is also possible; for example, if an etched printed circuit board consisting of a circuit made of copper foil is plated by the method of the present invention, only the copper foil portion can be selectively plated.

During plating, it is necessary to heat the solution containing the organometallic complex, and one of the major features of the present invention is to keep the heating temperature below the original decomposition temperature of the organometallic complex.

Conventionally, a method of plating is known in which an organometallic complex in an organic solvent is decomposed by heating it to a temperature higher than its thermal decomposition temperature, and the metal is precipitated and deposited on the metal to be plated. According to this method, the metal mainly precipitates in the form of powder or resin on the metal to be plated, making it difficult to obtain continuous and uniform plating.

Generally, the decomposition temperature of organometallic complexes is high, so there were many problems associated with processing at high temperatures.

Furthermore, when using a metal bath containing an organometallic complex, in the immersion method, if the bath temperature is heated above the decomposition temperature of the organometallic complex contained inside, the entire amount of the organometallic complex decomposes at once. It cannot withstand repeated use because metal precipitates. In this case, if the metal to be plated itself is heated, this problem can be avoided, but temperature control is difficult, and depending on the metal to be plated, heating to a high temperature may not be allowed.

The present invention uses an organometallic complex solution to heat copper and copper alloy to a temperature below the decomposition temperature of the organometallic complex to precipitate the metal in the organometallic complex. The present invention relates to a method for uniform plating.

Therefore, according to the present invention, even when plating is performed by dipping, the entire amount of the organometallic complex in the plating bath does not decompose at once, and it can be used repeatedly by simply adding the bone that has been reduced due to plating.

The method of plating copper and copper alloys according to the present invention is not limited to the dipping method, but may also include conventional methods such as brush coating, printing, and spraying.

Furthermore, the plated copper and copper alloy obtained by the present invention can be further plated with another metal using the method of the present invention, and further can be plated by electroless plating, electrolytic plating, vapor deposition, sputtering, ion plating, etc. There is no hindrance to plating using this method.

The present invention will be explained in detail below using Examples.

Example 1 Di-μm chloro-bis(η-2-me9-)rea-1-nor)dipalladium(II) was dissolved in xylene and 0.1w
It was made into a t% solution. When this complex solution was heated to 120°C4 and a phosphor bronze plate was immersed for 5 minutes, it was pulled out and exposed. It was done. When the surface of the palladium-plated phosphor bronze plate thus obtained was observed using a scanning electron microscope/energy dispersive X-ray micro riser, it was found that the surface was uniformly covered with radium.

The complex solution bath can be used repeatedly until the yellow color of the complex solution disappears and it becomes a colorless and transparent solution. Continuous use for a long period of time was possible by adding 1 calorie of the complex.

The obtained palladium bronze plate L;! Even after repeated bending 10 times, there was no peeling, cracking, cracking, etc. in the plating layer.

Example 2゜Di-μm chlorobis(η-2-methylallyl)dipalladium(II) heated to 120°C in the same manner as in Example 1.
When the brass plate was immersed in a 0.1 wt % xylene solution for 5 minutes and then pulled up, only the part that had been immersed in the complex solution was plated with palladium showing a silvery metallic luster.

Example 3 Trans[chloro(benzyl)bis(triphenylphosphine)]palladium(n) was dissolved in xylene, and 0.
A 1 wt % complex solution was prepared. When this complex solution was heated to 120°C and the phosphor bronze plate was immersed for 5 minutes, it was removed from the bath.
Only the part of the phosphor bronze plate that had been immersed in the complex solution was plated with palladium, giving it a white silver metallic luster.

Example 4 °G μm chlorotetracarponyl nirodium (I) was dissolved to prepare a 0.1 wt % complex solution. This complex solution was heated to 120° C., and the phosphor bronze plate was immersed for 5 minutes, and then removed from the bath. Only the portion of the phosphor bronze plate that had been immersed in the complex solution was plated with rhodium, showing a white silvery metallic luster.

The surface of the thus obtained rhodium mesokiline bronze plate was found to be uniformly covered with rhodium by scanning electron microscope/energy dispersive X-ray microanalyzer observation.

The plating bath can be used repeatedly until the yellow-orange color of the complex solution disappears and the solution becomes colorless and transparent, and furthermore, it can be used continuously for a long period of time by adding Gμm chlorotetracarponylnirodium (I) complex as appropriate. .

Even when the obtained Menkirin bronze plate was repeatedly bent 10 times, no peeling or cracking occurred in the plating layer.

Example 5 2.05 g of di-μm chloro-bis(η-2-methyllyryl)dipalladium (n) was dissolved in 200 g of xylene to prepare a palladium plating bath. Electrolytic copper powder Log in the plating bath
After stirring thoroughly at room temperature, the mixture was heated to 120°C and stirred at this temperature for 30 minutes.

The yellow color of the complex solution disappeared and the plating bath became colorless and transparent, and the copper powder turned black. The palladium-plated copper powder thus obtained was filtered and thoroughly dried to obtain 10% palladium-plated copper powder.

When the obtained 10% palladium-mebuki copper powder was observed using an optical microscope, the surface of the copper particles showed a white silver metallic luster, and when observed using a scanning electron microscope and an energy dispersive X-ray microanalyzer, the surface was uniformly coated with palladium metal. was.

Example 6゜ 10 g of copper powder and 0.9 di-μm chloro-bis(η-2-methylallyl) dipalladium (n) were prepared in the same manner as in Example 5.
A blackish brown 5% palladium plated copper powder was obtained from 75 g.

Example 7 In the same manner as in Example 5, 10 g of copper powder, di-μm chloro-
bis(η-2-methylallyl)dipalladium(II),
0. A brown 1% palladium-plated copper powder was obtained from 187 g.

Patent applicant: Nissan Chemical Industries, Ltd.

Claims (1)

[Claims] A method of plating copper and copper alloys using an organometallic complex of group Ⅰ of the periodic table that is soluble in an organic solvent at a temperature below the decomposition temperature of the complex.