JPH09111464A - Electroless plating liquid, electroless plating method and production of printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electroless plating liq. suppressing a generation of nodule and a decomposition of a bath without reducing a plate depositing speed by preparing the electroless plating liq. specifying each concn. of a copper ion, trialkanolamine, reducing agent and pH adjusting agent. SOLUTION: This electroless plating liq. has 0.005-0.015mol/l copper ion concn., 0.25-0.35mol/l pH adjusting agent concn., 0.01-0.04mol/l reducing agent concn. and 0.1-0.8M trialkanolamine concn. Wherein, copper sulfate, etc. are used as the copper ion, triethanolamine, triisopropanolamine, etc. are used as the trialkanolamine, aldehyde, hypophosphite, etc. are used as the reducing agent and sodium hydroxide, potassium hydroxide, etc. are used as the pH adjusting agent. By this way, the electroless plating liq. maintaining the plate depositing speed and also suppressing the decomposition of the bath and an abnormal deposition is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroless plating method, and in particular, can realize high-speed plating and is excellent in bath stability.
The present invention relates to an electroless plating solution capable of electroless plating without nodules, an electroless plating method using the same, and a method for manufacturing a printed wiring board.

[0002]

2. Description of the Related Art In the formation of a conductor pattern in the manufacturing process of a printed wiring board, a plating resist is provided on a predetermined portion of a base material, and then electroless copper plating is applied to the non-resist portion. Conventionally, a conductor pattern has been formed using an electroless plating bath using EDTA as a complexing agent. In order to apply electroless plating, an adhesive layer for electroless plating whose surface has been roughened in advance is often formed, but the EDTA plating bath has an excellent filling rate of plating in the anchor. Such a plating bath has a low plating deposition rate, and it takes a dozen hours or more to form a conductor circuit having a thickness of several tens of μm in this plating bath, which is not industrially appropriate.

Therefore, in Japanese Patent Laid-Open Nos. H1-168871, S64-52081, and S63-241188, high-speed plating (5 to 10 μm / hour) using trialkanolamine as a complexing agent is possible. Electroless copper plating has been proposed.

[0004]

However, when electroless plating was performed under the conditions described in these publications, the plating bath was decomposed and abnormal deposition called nodule was observed. In particular, the line spacing / line width is 100 μm / 10
When used for forming a conductor circuit of a printed wiring board having a fine conductor circuit of 0 μm or less, the generation of nodules is fatal. As a result of diligent research by the inventors of the present application, it was found that this cause is mainly due to the copper ion concentration and the reducing agent concentration in the bath. The present invention has been made to solve the above problems, and an object thereof is to maintain a plating deposition rate and prevent bath decomposition and abnormal deposition.

[0005]

According to the present invention, "in an electroless plating solution comprising copper ion, trialkanolamine, reducing agent and pH adjusting agent, the concentration of copper ion is 0.0
10 to 0.015 mol / l, the concentration of the pH adjusting agent is
0.25 to 0.35 mol / l and the concentration of the reducing agent is 0.01 to 0.04 mol / l, and an electroless plating method and print using the same. It is a method of manufacturing a wiring board. Further, the present invention is particularly desirable to be used as a plating solution for secondary plating, but as the primary plating solution, "at least one selected from copper ion, nickel ion and cobalt ion using hydroxycarboxylic acid as a complexing agent is used. An electroless plating solution containing two or more kinds of metal sources and a reducing agent and a pH adjusting agent, wherein the electroless plating solution contains an iron compound and / or bipyridyl. Is desirable.

In the present invention, the concentration of copper ions is set to 0.
The reason for setting it to 01 to 0.015 mol / l is that when the copper ion concentration is less than 0.01 mol / l, the deposition rate decreases,
Plating becomes difficult and copper ion concentration is 0.015m
This is because if it is ol / l or more, non-deposition (no plating reaction occurs) occurs. The concentration of the reducing agent is 0.01 to
The reason for setting 0.04 mol / l is 0.01 mol / l
If it is less than 0.0, unsedimentation and termination of the plating reaction occur, but 0.0
This is because nodules and decomposition occur at 4 mol / or less.

The concentration of the pH adjusting agent is 0.25 to 0.25.
The reason why it is necessary to be 0.35 mol / l is
If it is less than 0.25 mol / l, non-segregation occurs, and 0.3
This is because when it exceeds 5 mol / l, phenomena such as generation of nodules and plating particles adhering to portions where plating should not be originally deposited such as plating resist (abnormal deposition) are observed.

In the present invention, both the copper ion concentration and the reducing agent concentration are lower than those in the known art. JP H
In No. 1-168871 and Japanese Patent Laid-Open No. S64-52081,
It is described that the copper ion concentration is 0.005 to 0.1 M and the formalin concentration is 0.05 to 0.3 M, but the formalin concentration is too high, and a large amount of nodules are generated, resulting in decomposition of the plating bath. (The metal in the plating bath spontaneously precipitates).

Further, in JP-A-63-241188, the copper ion concentration is 0.02 to 0.07M and the formalin concentration is 0.02 to 0.5M. And the stop of the plating reaction occurs. As described above, in the present invention, by lowering both the copper ion concentration and the formalin concentration as compared with known techniques, bath decomposition without lowering the plating deposition rate,
The generation of nodules due to abnormal precipitation can be suppressed.

For this reason, especially the line spacing / line width is 100 μm /
It is advantageous when used for forming a conductor circuit of a printed wiring board having a fine conductor circuit of 100 μm or less. This is because short lines are likely to occur due to the generation of nodules due to the small distance between the lines, but such nodules do not occur under the conditions of the present invention.

The line spacing / line width is 100 μm / 100 μ
m or less means that the line width is 100 μm or less and the line spacing is 1
It means that it is less than 00 μm.

Further, the plating bath having the copper ion concentration and the reducing agent concentration range of the present invention is particularly advantageous in the following constitution. That is, "in a method of forming an adhesive layer for electroless plating on a base material and then performing electroless plating by immersing this base material in an electroless plating solution, the surface described below was subjected to a roughening treatment. A composite metal such as copper-nickel (or cobalt) -phosphorus, which will also be described later, is deposited as a primary plating film on the roughened surface of the adhesive layer for electroless plating, and the primary plating film is coated with a composite metal. Forming an electroless plating solution copper plating film. "

Such a primary plating film has excellent followability to the roughened surface of the adhesive layer for electroless plating, and traces the morphology of the roughened surface as it is. Therefore, the primary plating film has anchors like the roughened surface (see FIG. 3). Therefore, the secondary plating film formed on this primary plating film is
The space of this anchor must have good filling properties. If it is not sufficiently filled, voids remain between the primary plating film and the secondary plating film, causing peeling and poor conduction. The plating film obtained by the range of the plating bath of the present application has very fine deposited particles and excellent filling properties, and therefore has no peeling or poor conduction, and has a high deposition rate, and thus has excellent productivity.

The trialkanolamines used in the present invention are triethanolamine (TEA), triisopropanolamine (TIA), trimethanolamine (TM).
At least one selected from A) and tripropanolamine (TPA) is desirable. This is because the complexing power is excellent. Further, since they form a complex only under the strongly basic condition, they do not become a complex under the neutral condition and do not remain on the conductor circuit, so that conduction failure and migration do not occur.

The reducing agent is preferably at least one selected from aldehydes, hypophosphites (called phosphinates), borohydride salts, and hydrazine. This is because these reducing agents are water-soluble and have excellent reducing power. If a Ni compound is used, hypophosphite is used. The electroless plating solution preferably contains an iron compound and / or bipyridyl. The reason for this is that bipyridyl can suppress the generation of metal oxides in the plating bath and suppress the generation of nodules, and the iron compound is a reaction initiator and can suppress bath decomposition.

The iron compound is preferably potassium ferrocyanide or potassium ferricyanide. The pH
The adjusting agent is at least one selected from sodium hydroxide, potassium hydroxide and calcium hydroxide, and is a basic compound. This is because the trialkanolamine forms a complex under basic conditions. It is preferable that the concentration of the trialkanolamine is 0.1 to 0.8M. This is because the precipitation reaction does not occur unless the concentration of trialkanolamine is in the above range.

Copper ion, nickel ion, and cobalt ion are copper sulfate, nickel sulfate, cobalt sulfate, copper chloride,
Supplied by dissolving copper, nickel and cobalt compounds such as nickel chloride and cobalt chloride. As a method of using the electroless plating solution of the present invention, a catalyst nucleus is provided on the adhesive layer for electroless plating whose surface has been roughened, if necessary, and this is used in claim 1 of the present invention. Generally, a means for precipitating a plating film by immersing in a plating bath composed of the electroless plating solution described in any of 1 to 6 is used. By using such an electroless plating solution, it is possible to obtain a plating film without no deposition, reaction termination, bath decomposition, etc.

A preferred plating method using the electroless plating solution of the present invention is to form an adhesive layer for electroless plating whose surface is roughened on a substrate, and to use this adhesive layer for electroless plating. In the electroless plating method of performing secondary plating on this primary plating film after performing primary plating on
The electroless plating solution according to claims 1 to 6 of the present invention is used as the secondary plating ".

Since the primary plating film directly contacts the roughened surface of the adhesive for electroless plating, the strength of the plating film controls the peel strength. For this reason, it is desirable that the primary plating film be fine crystal grains and have high strength. A composite metal such as copper-nickel (or cobalt) -phosphorus can satisfy such conditions and improve peel strength.

However, as described above, such a primary plating film has excellent followability to the roughened surface of the adhesive layer for electroless plating, and traces the morphology of the roughened surface as it is. Therefore, the primary plating film has anchors like the roughened surface (see FIG. 3). Therefore, the secondary plating film formed on the primary plating film must be excellent in filling the space of the anchor. Therefore, when the plating solution of the present invention is used as the secondary plating solution, the deposited particles are very fine and the filling property is excellent, so there is no peeling or conduction failure, and the deposition rate is also high, resulting in excellent productivity. Of.

The primary plating solution preferably contains hydroxycarboxylic acid as a complexing agent and at least two or more selected from copper ions, nickel ions and cobalt ions as a metal source, a reducing agent and a pH adjusting agent. As the hydroxycarboxylic acid, citric acid, tartaric acid, malic acid and the like are preferable. The reducing agent is preferably a hypophosphite such as sodium phosphinate, an aldehyde such as formaldehyde, or hydrazine. As the pH adjuster, basic compounds such as sodium hydroxide, sodium carbonate and ammonia are preferable.

Further, it is desirable that the primary plating bath contains an iron compound and / or bipyridyl as described in claim 10. The reason for this is that bipyridyl can suppress the generation of metal oxides in the plating bath and suppress the generation of nodules, and the iron compound is a reaction initiator and can suppress bath decomposition. As the iron compound, potassium ferrocyanide, potassium ferricyanide and the like are preferable.

Further, it is desirable that the primary plating bath contains a lead compound such as lead nitrate or lead acetate. This is because it is possible to prevent nickel ions from spontaneously precipitating. Next, a method for manufacturing the printed wiring board will be described.

An electroless plating adhesive layer having a roughened surface is formed on a substrate, and a catalyst nucleus is added to the adhesive layer, which is used for electroless plating according to claims 1 to 6 of the present invention. A general method is to form a conductor circuit by immersing in a plating bath containing a plating solution to deposit a plating film. By using such an electroless plating solution, it is possible to obtain a conductor circuit without no deposition, reaction termination, bath decomposition, etc.

Further, an adhesive layer for electroless plating whose surface is roughened is formed on a substrate, and the primary plating is applied to the adhesive layer for electroless plating. In a method for manufacturing a printed wiring board, which performs secondary plating by means of a secondary plating method, the secondary plating method according to claim 1 to 2 of the present invention.
The electroless plating solution of No. 6 is used.

As a substrate, a copper clad laminate is etched to form a copper pattern, or an adhesive layer for electroless plating is formed on a glass epoxy substrate, a polyimide substrate, a ceramic substrate, a metal substrate, etc. and roughened. It is also possible to form a roughened surface and subject it to electroless plating to form a copper pattern.

Next, an adhesive layer for electroless plating is formed on the substrate. It is desirable that the adhesive for electroless plating contains heat-resistant resin particles that have been pre-cured in a heat-resistant resin (heat-resistant resin matrix) that is soluble in acid or oxidant. This is done by stacking the above. The heat-resistant resin particles can be dissolved and removed to form an octopus-shaped anchor.

As the heat-resistant resin particles, a heat-resistant resin powder having an average particle diameter of 10 μm or less, and an average particle diameter of 2 μm
Aggregated particles obtained by aggregating the following heat-resistant resin powders to have an average particle size of 3 times or more the particle size of the particles, heat-resistant powder resin powders having an average particle size of 10 μm or less, and the particles having an average particle size of the particles A mixture with a heat resistant resin powder having a particle diameter of ⅕ or less and 2 μm or less, a heat resistant resin powder having an average particle diameter of 2 μm or less or an inorganic powder on the surface of the heat resistant resin powder having an average particle diameter of 2 μm to 10 μm. It is desirable to be selected from pseudo particles formed by adhering at least one of the above.

Further, as the heat resistant resin matrix,
Photosensitive resin is desirable. This is because the holes for forming via holes can be formed by exposure and development.

The heat-resistant resin matrix is preferably a thermosetting resin such as an epoxy resin, a polyimide resin or an epoxy acrylate resin, or a composite of a mixture of these with a thermoplastic resin such as polyether sulfone. Epoxy resin, amino resin (melamine resin, urea resin, guanamine resin) and the like are preferable as the resin particles.

The solubility of the epoxy resin in an acid or an oxidizing agent can be arbitrarily changed by changing the kind of the oligomer, the kind of the curing agent and the crosslinking density. For example, a bisphenol A-type epoxy resin oligomer cured with an amine-based curing agent is easily dissolved in an oxidizing agent. However, the novolak epoxy resin oligomer cured with an imidazole-based curing agent is hardly dissolved in the oxidizing agent.

The acid used in the present invention includes phosphoric acid, hydrochloric acid, sulfuric acid, or organic acids such as formic acid and acetic acid, and the organic acid is particularly preferable. This is because when the roughening treatment is performed, the metal conductor layer exposed from the via hole is hardly corroded.

The oxidant is preferably chromic acid or permanganate (eg potassium permanganate). Especially,
When the amino resin is removed by dissolution, it is desirable to perform a roughening treatment alternately with an acid and an oxidizing agent.

Catalyst nuclei are provided on the roughened surface thus formed. The catalyst nucleus is preferably a noble metal ion or a colloid, and generally uses palladium chloride or a palladium colloid. It is desirable to perform a heat treatment to fix the catalyst core.

Next, a plating resist is applied or laminated in the form of a film, which is then exposed and developed to provide a plating resist pattern. Primary plating is applied to the portion where the plating resist is not formed. Furthermore, not only the copper pattern but also via holes can be formed to manufacture a multilayer printed wiring board.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments in which the present invention is embodied in an electroless plating method in a printed wiring board manufacturing process will be described in detail below. (Example) In this embodiment, a conductor pattern of a printed wiring board is manufactured by a full additive process. Hereinafter, the process will be described step by step.

(1) First, an adhesive for additive is applied on a glass epoxy plate as a base material. The adhesive was prepared as follows. 25 of cresol novolac type epoxy resin (Nippon Kayaku molecular weight 2500) dissolved in diethylene glycol dimethyl ether (DMDG)
% Acrylate, 70 parts by weight of polyether sulfone (PES), 4 parts by weight of imidazole curing agent (manufactured by Shikoku Kasei, product name: 2E4MZ-CN), and caprolactone modified tris (acryloxyethyl) as a photosensitive monomer. ) Isocyanurate (Toagosei, trade name; Aronix M
325) 10 parts by weight, 5 parts by weight of benzophenone (manufactured by Kanto Kagaku) as a photoinitiator, 0.5 part by weight of photosensitizer Michler's ketone (manufactured by Kanto Kagaku), and the average particle size of melamine resin particles with respect to this mixture. After mixing 35 parts by weight of 5.5 μm and 5 parts by weight of an average particle size of 0.5 μm, NM
Mix while adding P, adjust the viscosity to 2000 CPS with a homodisper stirrer, and then knead with three rolls.

(2) This adhesive solution was washed with water and dried on the base material that had been subjected to the plating process, and then applied on the base material 2 using a roll coater, and left standing in a horizontal state for 20 minutes,
Drying (prebaking) was performed at 60 ° C.

(3) The wiring board subjected to the treatment of (2) above was exposed with an ultrahigh pressure mercury lamp of 400 mj / cm ² . Further, the wiring board was exposed to light of about 3000 mj / cm ² by an ultra-high pressure mercury lamp, and heat-treated (post-baked) at 100 ° C. for 1 hour and then at 150 ° C. for 5 hours to obtain dimensional accuracy equivalent to that of a photomask film. 50 μm thickness with excellent opening
The resin adhesive layer of was formed.

This adhesive is obtained by dispersing a resin filler soluble in the roughening liquid in a resin matrix which is hardly soluble in the roughening liquid such as chromic acid and phosphoric acid.
In this case, a surface roughening treatment with chromic acid, potassium permanganate or the like is then carried out by a conventional method to dissolve the resin filler in the adhesive layer 2. Specifically, add potassium permanganate (KMnO ₄ , 60 g / l) adjusted to pH = 13.
Immersion at 70 ° C. for 1 minute and then immersion in phosphoric acid for 30 minutes to dissolve and remove the resin filler to form a roughened surface on which a large number of fine anchors are formed on the surface of the adhesive layer.

Next, after providing the catalyst nuclei necessary for the first deposition of the electroless plated metal, a photosensitive resin such as photosensitive epoxy or photosensitive polyimide is applied, and exposure and development are performed.
As a result, a permanent resist partially having openings is formed on the upper surface of the adhesive layer, as shown in FIG.

Specifically, the following procedure was followed. DM
A cresol novolac type epoxy resin (manufactured by Nippon Kayaku, trade name: EOCN-103S) dissolved in DG (dimethyl glycol dimethyl ether) is sensitized with 25% of the epoxy groups acrylated (molecular weight 400.
0), PES (molecular weight 17,000), imidazole type curing agent (Shikoku Kasei product name 2 PMHZ-PW), photosensitive monomer acrylated isocyanate (Toagosei product name Aronix M215), benzophenone (Kanto Chemical Co., Inc.) as a photoinitiator. , A photosensitizer Michler Ketone (manufactured by Kanto Kagaku), and mixed with NMP with the following composition, and then the viscosity is 3000 cps with a homodisper agitator.
And then kneading with a three-roll mill to obtain a liquid resist. Resin composition: Photosensitive epoxy / PES / M325 / BP
/MK/imidazole=70/30/10/5/0.5
/ 5 This liquid resist is applied onto the resin insulation layer of (7) above using a roll coater and dried at 60 ° C. to a thickness of about 3
A 0 μm resist layer was formed. Furthermore, L / S = 50
A mask film on which a conductor circuit pattern of / 50 was drawn was brought into close contact and exposed with an ultrahigh pressure mercury lamp of 1000 mJ / cm ² . This was spray-developed with triethylene glycol dimethyl ether (DMTG) to form a plating resist with a missing conductor circuit pattern portion on the wiring board. Furthermore, with an ultra-high pressure mercury lamp, 6000 mJ /
cm ² for 1 hour at 1000 ° C, then 150 ° C
Was heat-treated for 3 hours. A permanent resist was formed using this resist resin.

Then, after performing a conventionally known plating pretreatment, primary plating is performed on the openings. Here, as a plating bath for primary plating, an electroless copper-nickel-phosphorus alloy plating bath containing citric acid as a complexing agent is used.

In this embodiment, an electroless copper-nickel alloy plating bath having the following composition is specifically used as the primary plating. The temperature of the plating bath is 50 ℃
The temperature is 80 ° C., and the plating immersion time is 20 minutes to 120 minutes. Metal salt ... CuSO ₄ .5H ₂ O; 1.8 mM NiSO ₄ .6H ₂ O; 51.0 mM Complexing agent ... Citric acid 0.33M reducing agent ... Phosphinic acid Na monohydrate; 0.2M pH adjusting agent ... NaOH; 0.75M Others ... A small amount of stabilizers (bipyridyl, potassium ferrocyanide, etc.). Deposition rate is 1.5 μm / hour

By plating under the above conditions,
Copper with a thickness of about 2 μm is formed in the opening where the resist is not formed.
A nickel-phosphorus plated thin film is formed. Then, the glass epoxy plate is pulled up from the plating bath, and the plating bath adhering to the surface is washed off with water.

Then, the oxide film on the surface layer of the copper-nickel-phosphorus plating thin film is removed by activating the glass epoxy plate with an acidic solution. Then, secondary plating is performed on the copper-nickel-phosphorus plating thin film without performing Pd substitution. Here, the electroless copper plating bath of the present invention is used as the plating bath for the secondary plating. In this embodiment, a plating bath having the following composition is specifically used as the secondary plating. The temperature of the plating bath is 50 ° C to 70 ° C, and the plating immersion time is 90 minutes to 3
60 minutes. Metal salt ... CuSO ₄ .5H ₂ O; 8.6 mM Complexing agent ... TEA; 0.15M Reducing agent ... HCHO; 0.02M Other ... Stabilizer (bipyridyl, potassium ferrocyanide, etc.) A small amount. Deposition rate is 6 μm / hour

By plating under the above conditions,
As shown in, the primary plating film of copper-nickel-
A copper plating film is formed on the surface of the phosphorous plating thin film. Therefore, a conductor pattern composed of two kinds of metal layers can be obtained. As a result of optical microscope observation, no abnormal deposition of nodules or copper was observed (see FIG. 1). In addition, the plating bath was very stable and no decomposition of the plating bath occurred.

Further, the cross-cut was observed with an optical microscope, but no voids or the like were found at the interface between the primary plating film and the secondary plating film. Cross-cut (cross-section) photographs are not described herein. This is because it is difficult to confirm the difference between the primary plating film and the secondary plating film. Therefore, a schematic diagram is shown in FIG.
It was decided to describe in. In FIG. 3, an adhesive 2 for electroless plating having a roughened surface 3 on the surface is formed on a substrate 1, and a primary plating film 4 and a secondary plating film 5 are present thereon. Further, the plating film is formed between the plating resists 6. Furthermore, the peel strength was measured and found to be 1.8 kg / cm. The peel strength was measured according to JIS-C-6481.

Comparative Example 1 Basically the same as in Example 1, but the copper ion concentration was 0.003M. In this case, metal ions in the plating solution were deposited and decomposed in the bath in about 5 hours after the bath was set up. Furthermore, when plating was performed immediately after the bath was built up, there was no nodule, but the plating did not adhere well and the deposition rate was halved to 3 μm / hour.

Comparative Example 2 Basically the same as in Example 1, but the copper ion concentration was 0.017M. In this case, a phenomenon called so-called non-deposition was observed in which the reaction of the plating bath did not occur.

Comparative Example 3 Basically the same as in Example 1, but the reducing agent concentration was 0.08M. in this case,
The non-deposition was observed, and the termination of the plating reaction was observed even when the plating reaction occurred.

Comparative Example 4 Basically the same as in Example 1, but the reducing agent concentration was 0.06M. in this case,
Nodules were generated (see Fig. 2), and abnormal deposition was observed in the plating bath and filter. Further, as a result of cross-cut optical microscope observation, peeling was observed at the interface between the primary plating film and the secondary plating film.

[0053]

As described in detail above, according to the present invention, bath decomposition and nodules can be prevented without lowering the plating deposition rate.

[Brief description of the drawings]

FIG. 1 is an optical micrograph showing a metal structure of a conductor circuit plated by a plating bath of the present invention.

FIG. 2 is an optical micrograph showing a metal structure of a conductor circuit plated by a plating bath of Comparative Example 4.

FIG. 3 is a schematic sectional view showing a layer structure of a primary plating film and a secondary plating film.

[Explanation of symbols] 1 substrate 2 adhesive for electroless plating 3 roughened surface 4 primary plating film 5 secondary plating film 6 plating resist

Claims (10)

[Claims] 1. An electroless plating solution comprising copper ions, a trialkanolamine, a reducing agent and a pH adjuster, wherein the concentration of copper ions is 0.005 to 0.015 mol / l,
The electroless plating solution, wherein the pH adjusting agent has a concentration of 0.25 to 0.35 mol / l and the reducing agent has a concentration of 0.01 to 0.04 mol / l. 2. The electroless plating solution according to claim 1, wherein the concentration of trialkanolamine in the electroless plating solution is 0.1 to 0.8M. 3. The electroless plating solution according to claim 1, wherein the trialkanolamine is at least one selected from triethanolamine, triisopropanolamine, trimethanolamine, and tripropanolamine. 4. The electroless plating solution according to claim 1, wherein the reducing agent is at least one selected from aldehyde, hypophosphite, borohydride and hydrazine. 5. The pH adjusting agent is sodium hydroxide,
The electroless plating solution according to claim 1, which is at least one selected from potassium hydroxide and calcium hydroxide. 6. The electroless plating solution according to claim 1, wherein the electroless plating solution contains an iron compound and / or bipyridyl. 7. The electroless plating solution has a line spacing / line width of 1
The electroless plating solution according to any one of claims 1 to 6, which is used for producing a printed wiring board having a conductor circuit of 00 µm / 100 µm or less. 8. A method of forming an adhesive layer for electroless plating on a base material and then performing electroless plating by immersing the base material in an electroless plating solution, wherein the electroless plating bath comprises: An electroless plating method comprising using the electroless plating solution according to claim 1. 9. A method for producing a printed wiring board, comprising: forming an adhesive layer for electroless plating on a substrate; and then immersing the substrate in an electroless plating solution to perform electroless plating, wherein the electroless plating is performed. A method for producing a printed wiring board, characterized in that the electroless plating solution according to any one of claims 1 to 6 is used as the solution. 10. A hydroxycarboxylic acid as a complexing agent,
In an electroless plating solution containing a reducing agent and a pH adjusting agent, using at least two or more kinds selected from copper ions, nickel ions and cobalt ions as a metal source, the electroless plating solution contains an iron compound and / or bipyridyl. An electroless plating solution characterized by being formed.