KR101483599B1 - An electroless gold plating solution - Google Patents

Abstract

An electroless gold plating solution capable of forming a gold plating film excellent in adhesiveness and not corroding a base metal film such as nickel, copper, cobalt or palladium is disclosed.

Description

Electroless gold plating solution {AN ELECTROLESS GOLD PLATING SOLUTION}

The present invention relates to an electroless gold plating solution. The present invention also relates to an electroless gold plating solution which can be used to deposit gold on the surface of a metal, such as nickel or copper.

Generally, gold plating is used for electronic components such as printed circuit boards, ceramic IC packages, ITO boards, IC cards and the like from the viewpoints of electric conductivity, solderability and physical properties of gold, for example, It is used as a final surface treatment. It is preferable for most of these electronic industrial parts to use electroless plating rather than electroplating because of necessity of performing gold plating on parts having electrical independent parts and complex shapes.

Printed circuit boards usually have electroless nickel plating on the surface of base metals, such as copper interconnects, and electroless gold plating is often done on the surface of the nickel. In this case, a self-catalyzed electroless gold plating solution for depositing gold by the effect of a substitution gold plating solution in which gold is deposited while dissolving a base metal such as nickel, and a reducing agent having catalytic activity to gold is widely known have. Substitution gold plating deposits gold by the substitution reaction between gold and base metal, and even when autocatalytic electroless gold plating is used, the substitution gold plating reaction is used when the autocatalytic electroless gold plating reaction is initiated. In other words, immediately after the electropositive electroless gold plating solution and the object to be plated are contacted, the gold deposition starts due to the substitution reaction between the base metal and the gold. The substitution reaction in the electroless gold plating uses the dissolution of the base metal as the driving force for depositing the gold. Since this substitution reaction is affected by the structure of the base metal, such as grain boundary, etc., a difference in the dissolution level of the base metal is generated. In a region where the metal is more physically weak in the crystal grain boundary of the base metal or the like, for example, the substitution reaction proceeds preferentially relative to the other regions, in other words, there is inconsistency in dissolution of the base metal. The corrosion of the base metal initiated by the uneven dissolution of the base metal causes problems such as localized embrittlement and low solder joint strength of the bond strength of the base metal in which the obtained gold plating film is decomposed.

(For example, Japanese Patent Application Laid-Open No. S59-6365), or further contains a nitrogen-containing compound as a gold deposition control agent (for example, 2000-144441), and a substituted gold plating solution containing a polyethyleneimine (for example, JP 2003-13248 A). However, although the electroless gold plating solution can reduce the corrosion of the nickel coating as the base metal layer to some extent, there is a problem that the deposition rate of the gold plating coating is lowered because the dissolution rate of the nickel coating is reduced

It is an object of the present invention to provide an electroless gold plating solution capable of solving the above-mentioned problems and being uniformly plated to increase the adhesion to the base metal without corroding the base metal.

As a result of intensive investigations to solve the above-mentioned problems, the present inventors have found that the above-mentioned object can be achieved by using an electroless gold plating solution containing a combination of specific components, thereby realizing the present invention. That is, the present invention relates to:

(i) a water-soluble cyanide gold compound;

(ii) a complexing agent; And

(iii) a pyridinium carboxylate compound having a phenyl group or an aralkyl group in the first position, which is used for performing metal plating on the surface of the metal.

In addition, the present invention further provides,

(iv) an electroless gold plating solution containing at least one compound selected from formic acid and a salt thereof, and hydrazine and derivatives thereof as a base metal surface treatment agent.

Further, the present invention relates to:

(i) a water-soluble cyanide gold compound;

(ii) at least one compounding agent selected from ethylenediaminetetramethylenephosphonic acid or derivatives thereof;

(iii) at least one compound selected from a pyridinium carboxylate compound having a phenyl group or an aralkyl group at the first position;

(iv) at least one compound selected from hydrazine and derivatives thereof as a base metal surface treatment agent; And

(v) at least one compound selected from the group consisting of a polycarboxylic acid and a salt thereof, which is used for performing gold plating on the surface of a metal.

By using the electroless gold plating solution of the present invention, undesired dissolution or corrosion of the base metal can be suppressed, adhesion can be increased, a uniform gold plating film can be formed, and the deposition rate of gold Can be increased.

Further, the electroless gold plating solution of the present invention can deposit a favorable gold coating having excellent appearance and excellent solder bonding strength without causing local corrosion of the base metal, e.g., nickel.

The present invention will be described in detail below. The electroless gold plating solution of the present invention comprises a water-soluble cyanide gold compound, a complexing agent, a pyridinium carboxylate compound having a phenyl group or an aralkyl group at a first position, optionally containing a polycarboxylate, and at least one base metal surface treatment agent, For example, an aqueous solution containing formic acid or a salt thereof, or hydrazine or a derivative thereof.

The water-soluble cyanide gold compound used in the present invention is not particularly limited as long as the cyanide gold compound is water-soluble and can be any cyanide gold compound. The gold cyanide compound can provide gold ions to the plating solution and is usually used in a gold plating solution. Examples of water-soluble cyanide gold compounds of this type include potassium dicyanoaurate (I) and potassium tetracyanaurate (III). One or more water-soluble cyanide gold compounds may be blended.

The electroless gold plating solution of the present invention suitably contains such a water-soluble cyanide gold compound having a gold ion concentration of 0.1 to 10 g / L, for example, preferably 0.5 to 5 g / L.

The complexing agent used in the present invention may be anything used in a known gold plating solution if the material is water-soluble and can stably maintain gold ions in the plating solution. The plating bath containing such a complexing agent may be substantially nickel, Cobalt, or palladium. Examples of such a complexing agent include organic phosphonic acids or salts thereof having a plurality of phosphonic acid groups or salts thereof in the molecule, and aminocarboxylic acids or salts thereof. The phosphonic acid or a salt thereof is preferably, for example, preferably a group having the structure shown below:

-PO ₃ MM '

Wherein M and M 'may be the same or different and are selected from the group consisting of hydrogen atom, sodium, potassium, and ammonium. The number of the phosphonic acid group or its salt in the compound is 2 to 6, preferably 2 to 5.

The organophosphonic acid used in the present invention is preferably a compound having the structure:

In this formula,

X ¹ is a hydrogen atom, a C ₁ -C ₅ alkyl group, an aryl group, an arylalkyl group, an amino group, or a C ₁ -C ₅ alkyl group substituted with -OH, -COOM, or PO ₃ MM '. M and M 'are as described above. M and n are integers of 0 or 1.

As used herein, the term "alkyl group" includes straight chain or branched chain. "C1 to C5 alkyl" means an alkyl group having from 1 to 5 carbon atoms. Examples of the C1 to C5 alkyl groups are methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl or pentyl. Examples of the aryl group include a phenyl group and a naphthyl group. An example of the arylalkyl group is one of the above-mentioned alkyl groups having the above-mentioned aryl group as a substituent. Examples of the amino group include a hydrogen atom on the nitrogen atom and an amino group having the above-mentioned alkyl group and the like.

(2)

Wherein, X ² is, for _{example, -CH 2 -, -CH (OH} ) -, -C (CH 3) (OH) -, -CH (PO 3 MM ') -, -C (CH 3) ( PO ₃ MM ') -, -CH (CH (COOM) - or -C (CH ₃ ) (COOM) -, and the like. M and M' are as defined above.

(3)

In the above formulas, X ³ to X ⁷ are similar to the above-mentioned X ¹ . However, at least two X ³ to X ⁷ are -PO ₃ MM '.

Examples of the above-mentioned organic phosphonic acid include aminotrimethylenephosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, ethylenediamine tetramethylenephosphonic acid, diethylenetriaminepentamethylenephosphonic acid and its sodium salt , Potassium salts or ammonium salts, and the like. The complexing agent used in the present invention may be a single type, or may be a blend of two or more types.

Examples of aminocarboxylates include glycerin, imino diacetate, hydroxyethyl ethylenediamine triacetate, tetrahydroxyethylenediamine, dihydroxymethylethylenediamine diacetate, ethylenediamine tetraacetate, ethylenediaminetetra propionic acid and its sodium salt, Potassium salts and ammonium salts.

Examples of the above-mentioned ethylenediamine derivatives having a phosphoric acid group or a salt thereof or an amino carboxylate group or a salt thereof include ethylenediaminetetramethylenephosphonic acid, hydroxyethylethylenediamine triacetate, tetrahydroxyethylenediamine, hydroxymethylethylenediamine di Acetate, ethylenediamine tetraacetate, but ethylenediaminetetra propionic acid and sodium, potassium and ammonium salts thereof are preferably used as a complexing agent in the present invention.

The complexing agent used in the present invention is preferably used in the range of 0.005 to 0.8 mol / L, more preferably 0.02 to 0.6 mol / L. The molar number of the complexing agent contained is preferably equal to or higher than the molar number of gold ions present in the plating solution.

The electroless gold plating solution of the present invention contains a pyridinium carboxylate compound having a phenyl group or an aralkyl group at the first position. These pyridinium carboxylate compounds having a phenyl group or an aralkyl group in the first position induce a uniform gold plating film to deposit as fine gold deposit particles adhering to the surface of the base metal which is the surface of the object to be plated and to increase the gold deposition rate Thereby suppressing the substitution reaction between the gold ion and the base metal in the electroless gold plating solution, thereby suppressing elution of the base metal.

Examples of pyridinium carboxylate compounds having a phenyl group or an aralkyl group in the first position include 1-phenyl-pyridinium-2-carboxylic acid, 1-phenyl-pyridinium-3-carboxylic acid and 1-phenyl- And 1-phenylalkylene-pyridinium carboxylate compounds such as 1-benzyl-pyridinium-2-carboxylic acid, 1-benzyl-pyridinium-3-carboxylic acid, (Phenyl ether) -pyridinium-2-carboxylic acid, 1- (phenylethyl) -pyridinium-3-carboxylic acid, 1- Pyridinium-2-carboxylic acid, 1- (phenylpropyl) -pyridinium-3-carboxylic acid, 1- (phenylpropyl) -pyridinium- (Phenylbutyl) -pyridinium-2-carboxylic acid, 1- (phenylbutyl) -pyridinium-3-carboxylic acid, 1- (phenylbutyl) -pyridinium- 2-carboxylic acid, 1- (phenylpentyl) -pyridinium-3-carboxylic acid, 1- Pentyl) -, and the like pyridinium-4-carboxylic acid and their sodium salts of carboxylic acids, potassium salts or ammonium salts thereof, and compounds of hydroxide, chloride and bromide. One preferred compound of the pyridinium carboxylate compound having a phenyl group or aralkyl group in the first position is 1-benzyl-pyridinium-3-carboxylic acid or a carboxylate thereof. These compounds may be used independently, or two or more types may be blended together and used together.

The pyridinium carboxylate compound having a phenyl group or an aralkyl group in the first position is used in the range of 0.1 to 100 g / L, preferably 5 to 30 g / L.

The electroless gold plating solution of the present invention also preferably includes a base metal surface treatment agent. The base metal surface treatment agent used in the present invention is a substance having an effect of reducing an oxidized metal formed on the surface of a base metal selected from the group consisting of nickel, copper, cobalt, palladium and an alloy including these metals . These materials act as reducing agents, preferentially oxidize the base metal in preference to gold ions, and when combined with a pyridinium carboxylate compound having a phenyl or aralkyl group in the first position, corrosion of the base metal is inhibited, Is increased, a uniform gold plating film is formed, and the gold deposition rate is increased.

Examples of base metal surface treatment agents include formic acid and its salts, such as formic acid, sodium formate, potassium formate, ammonium formate; And hydrazine and its derivatives, such as hydrazine, hydrazine hydrate and hydrazine sulfate, hydrazine chloride and its salts. The base metal surface treatment agents used in the present invention can be used individually or two or more types can be blended and used together.

The base metal surface treatment agent used in the present invention is used in the range of 0.1 to 20 g / L, preferably 1 to 15 g / L.

The electroless gold plating solution of the present invention preferably further comprises a polycarboxylic acid or a salt thereof. The polycarboxylic acid or its salt adheres to the surface of the base metal to inhibit pinhole corrosion and forms a salt with the base metal ion eluted with the plating liquid to form a salt to stabilize the plating liquid. Examples of the polycarboxylic acid or its salt include oxalic acid, maleic acid, fumaric acid, malic acid, citric acid, adipic acid and sodium salt, potassium salt or ammonium salt thereof and the like. Citric acid or tri-potassium citrate is preferred. The polycarboxylic acid or its salt may be used individually, or two or more types may be blended and used together.

The polycarboxylic acid or its salt used in the present invention is present in the range of, for example, 0 to 100 g / L, preferably 30 to 75 g / L.

The pH of the electroless gold plating solution of the present invention is preferably 3 to 8, more preferably 5 to less than 7. The pH of the gold plating solution of the present invention is adjusted using, for example, sodium hydroxide, potassium hydroxide, ammonium hydroxide, sulfuric acid, sulfurous acid, HCl, phosphoric acid, cyanic acid, sulfamic acid, organic sulfonic acid, phosphonic acid or carboxylic acid. In addition, a pH stabilizer may also be provided if necessary. Examples of pH stabilizers include phosphates, phosphites, borates, carbonates, cyanates and the like.

If desired, the electroless gold plating solution of the present invention may contain a wetting agent to increase the wetness of the base metal to be coated. The wetting agent can be used without limitation, especially if the wetting agent is a material conventionally used in a gold plating solution. Examples of wetting agents include nonionic surfactants such as polyoxyalkylene alkyl ethers, polyoxyalkylene alkyl phenyl ethers, polyoxyethylene polyoxypropylene glycols, fatty acid polyalkylene glycols, fatty acid polyalkylene sorbitan and fatty acids Alkanolamides; Anionic surfactants such as fatty acid carboxylates, alkanesulfonates, alkylbenzene sulfonates; And cationic surfactants such as alkylamines and the like.

If desired, the electroless gold plating solution of the present invention may also contain a brightener to increase the gloss of the gold-plated film and make the gold-plated film particles more dense. The polish can be used without limitation, particularly as long as the polish is a material commonly used in gold plating solutions. Examples of polishes include thallium, arsenic, lead, copper, antimony, and the like. The electroless gold plating solution of the present invention may contain compounds other than those mentioned above to the extent that the properties of the plating solution do not adversely affect.

When gold plating is performed using the electroless gold plating solution of the present invention, the method may be the same as a normal electroless plating method. Generally, an object to be plated is immersed in an electroless gold plating solution, and the electroless gold-plated film is maintained at a temperature of the plating solution within the indicated range to obtain a film made of nickel, cobalt, copper, palladium, May be formed on the surface of the base metal. For example, the gold plating solution of the present invention can be suitably used as an electroless gold plating solution for depositing gold on the surface of a metal such as nickel or copper.

When gold plating is performed using the electroless gold plating solution of the present invention, the temperature (liquid temperature) of the gold plating solution is 50 to 100 캜, preferably 70 to 95 캜. The plating time is usually 1 to 60 minutes, preferably 10 to 30 minutes. In the case of performing gold plating using the electroless gold plating solution of the present invention, reflux filtration of the plating solution using a filter is particularly preferable, but the plating solution may be subjected to mixing, exchange filtration, or reflux filtration .

The electroless gold plating solution of the present invention has excellent stability and can form a uniform gold plated film with good appearance at an increased gold deposition rate that is well deposited on the base metal. Furthermore, the electroless gold plating solution of the present invention has excellent properties to minimize pinhole corrosion and grain boundary corrosion of nickel plating when nickel is base metal.

Specific examples of the present invention will be shown below, but the present invention is not limited to these specific examples.

Examples 1-22

An electroless nickel plated film having a thickness of about 5 탆 was coated with a conventionally known electroless nickel plating solution (Ronamax (trademark) SMT-115, manufactured by Rohm & Haas Electronic Materials Co. Ltd. ) Was formed on a copper-clad laminate of about 5 cm x 10 cm pattern.

L of potassium dicyanoaurate, 50 mg / L of potassium cyanide, 150 g / L of ethylenediamine tetramethylene phosphonic acid, 10 g / L of potassium formate, 94.3 g / L of potassium hydride An electroless gold plating solution was prepared as an aqueous solution added to a 48% aqueous solution of chloride and 0.5 g / L of sodium 1-benzyl-pyridinium-3-carboxylate chloride. This electroless gold plating solution was adjusted to pH 5.3 by the addition of additional potassium hydroxide.

The above-mentioned specimens were immersed in an electroless gold plating solution at a liquid temperature of 90 DEG C for 10 minutes to form a gold plated film. The film thickness of the formed gold-plated film was measured using a fluorescent x-ray thickness meter, and the gold-plating deposition rate was measured. Further, the formed gold-plated film was visually observed to evaluate occurrence of lack of deposition and color. The results are shown in Table 1.

The formed gold-plated film was stripped using a gold plating stripping solution Enstrip AU-78M (manufactured by Meltex Inc.), and the surface of the base metal nickel surface was stripped using FE-SEM JSM-7000F (manufactured by JEOL Ltd.) The occurrence of corrosion was observed. Observation results are shown in Table 1. Here, 1 = excellent, 2 = somewhat fine (minimum corrosion), 3 = partial corrosion, 4 = significant corrosion, and 5 = abundant corrosion.

Similar to Example 1 except that the compounds shown in the following Table 1 were used in place of the aqueous solution containing chloride of sodium 1-benzyl-pyridinium-3-carboxylate, the electroless gold plating A solution was prepared, electroless gold plating was performed, and a coating was observed. The results are shown in Table 1.

compound amount
g / L Deposition rate 탆 / 10 min Gold-plated film appearance Corrosion of nickel plated film Example 1 A 48% aqueous solution (g / L) of chloride of sodium 1-benzyl-pyridinium-3- 0.5 0.092 splendor 2 compare
Example 1 Reaction products of imidazole and epichlorohydrin 0.5 0.029 splendor 3 compare
Example 2 Sulfopropylethyl polyethyleneimine 0.5 0.041 splendor 2 compare
Example 3 Reaction products of morpholine and epichlorohydrin 0.5 0.036 splendor 3 compare
Example 4 Dimethylaminoethyl methacrylate quaternary compound 0.5 0.029 splendor 3 compare
Example 5 Reaction product of dimethylamine, ammonia and epichlorohydrin 0.5 0.026 splendor 3 compare
Example 6 Polyethyleneimine (average molecular weight 1300) 0.5 0.010 splendor One compare
Example 7 Polyethyleneimine (average molecular weight 2000) 0.5 0.012 splendor One Specific Example 2 A 48% aqueous solution (g / L) of the chloride of 1-benzyl-pyridinium-3- 1.0 0.090 splendor 2 Example 3 A 48% aqueous solution (g / L) of the chloride of 1-benzyl-pyridinium-3- 5.0 0.071 splendor 2 compare
Example 8 Polyvinylpyrrolidone (average molecular weight measured 5,000) 0.5 0.066 splendor 3 compare
Example 9 Picoric acid 5.0 0.120 splendor 4 compare
Example 10 Isonicotinic acid 5.0 0.109 splendor 4 compare
Example 11 3-Picoline amine 5.0 0.111 splendor 5 compare
Example 12 4-phenylpropyl-pyridine N.A. N.A. N.A. N.A.

A gold plating solution containing 4-phenylpropyl-pyridine separated as an oil and used as Comparative Example 12 and gold plating were not possible.

As shown in Table 1, when the plating solutions of Examples 1 to 3 including 1-benzyl-pyridinium-3-carboxylic acid were used, the corrosion of the nickel plating as the base metal was suppressed and the deposition rate of the gold plating was obviously increased Respectively.

The aqueous solutions shown in Tables 2 and 3 were prepared as electroless gold-plating solutions. The electroless gold plating solution pH was adjusted by addition of additional potassium hydroxide. Similar to Example 1, the specimens were immersed in an electroless gold-plating solution, and the presence of the obtained gold-plated film and the occurrence of corrosion of the nickel-plated film were evaluated. The results are shown in Table 2 and Table 3.

An electroless gold plating solution was prepared similarly to example 1 except that the added amount of 1-benzyl-pyridinium-3-carboxylic acid, the base metal treating agent, and the pH of the plating solution were as shown in Table 5. [ The solder bond strength was evaluated by the following method, and the stability of the bath was also evaluated.

Example 23

Solder Bond Strength Test

The specimen on which the electroless gold-plated film was formed was subjected to reflow treatment three times at a pre-heating temperature of 170 占 폚 and reflow 240 占 폚, and then the ball mount was performed under the conditions shown in Table 4 below. Respectively. The test was carried out using 10 specimens under each condition and the average value was calculated as the bond strength. The results are shown in Table 5.

Bath stability test

100 mL of the electroless gold plating solution was poured into a lidless screw tube, heated to a solution temperature of 90 DEG C using a water bath, and measured under these conditions to evaluate the stability of the bath when the electroless gold plating solution was separated.

Example 24

An aqueous solution of pH 6.5 was prepared by mixing 1.5 g / L potassium dicyanoaurate, 50 mg / L potassium cyanide, 150 g / L ethylenediamine tetramethylene phosphonic acid, 3.5 g / L hydrazine, 20 g / L sodium A 48% aqueous solution of chloride of 1-benzyl-pyridinium-3-carboxylate and 94.3 g / L potassium hydroxide was added as an electroless gold-plating solution.

Example 25

An electroless gold-plated bath was prepared similar to the electroless gold-plated bath of Example 24, except that 20 grams of potassium formate was used instead of hydrazine. A stability check was performed on these plating solutions. The results are shown in Table 6.

A plating solution containing polyethyleneimine instead of 1-benzyl-pyridinium-3-carboxylic acid (Aurolectroless (trademark) SMT-250 electroless gold plating solution, Rohm & Haas Electronic Materials Co. Ltd.) was used as a conventional electroless gold plating solution As a comparative example, a stability test was performed. The results are shown in Table 6.

Example 26

Validation of polycarboxylic acid

56 g of tripotassium citrate was mixed with 1.5 g / L of potassium dicyanoaurate (I), 100 mg / L of potassium cyanide, 150 g / L of ethylenediamine tetramethylenephosphonic acid, 7 g of hydrazine, -Benzyl-pyridinium-3-carboxylate and an aqueous solution of 94.3 g / L of potassium hydroxide to prepare an electroless gold plating solution. Additional potassium hydroxide was added to adjust the pH of the electroless gold plating solution to 6.5. Using this electroless gold plating solution, a gold-plated film was formed similar to that of Example 1, and various tests were performed as described below.

The gold-plated solution containing tri-potassium citrate is particularly notable for the deposition rate of the gold-plated film, the appearance of the gold-plated film, the solder bond strength, and the bath stability compared to gold-plating solutions that do not contain tri- potassium citrate . However, when a gold plating solution containing tri-potassium citrate was used, the pinhole-type corrosion of the nickel plated film was significantly reduced.

Validation of pyridinium carboxylate compounds having a phenyl group or aralkyl group in the first position

As shown in Table 6 below, a 48% aqueous solution of chloride of sodium 1-benzyl-pyridinium-3-carboxylate was added to a solution of 2 g / L potassium dicyanoaurate (I), 45 g / L of ethylenediamine tetraacetate and 67.5 g / L of tripotassium citrate was added to the aqueous solution added to water, and the pH of the aqueous solution was adjusted using potassium hydroxide.

The specimen used in Example 1 was immersed in an electroless gold plating solution having a liquid temperature of 85 DEG C for 10 minutes to form a gold-plated film. The formed gold-plated film was stripped using a gold-stripping solution Enstrip AU-78M (Meltex Inc.) and the surface corrosion of the nickel base metal was observed using FE-SEM JSM-7000F (JEOL, Ltd.) . Observations are shown in Table 7 (1 = Excellent, 2 = Slightly Excellent (Minimal Corrosion), 3 = Partial Corrosion, 4 = Slightly Corrosive and 5 = Very Corrosive).

Table 7

Addition amount pH Corrosion of Nickel Plating Membrane Comparative Example 20 0 5.5 5 Embodiment 27 10 5.5 3 Embodiment 28 20 5.5 3 Embodiment 29 30 5.5 3 Embodiment 30 40 5.5 3 Example 31 20 5.0 3

It was confirmed that the pinhole type corrosion of the nickel plated film can be reduced by adding chloride of sodium 1-benzylpyridinium-3-carboxylate to the electroless gold plating solution.

Claims (9)

(i) a water-soluble cyanide gold compound; (ii) a complexing agent; And (iii) at least one compound selected from a pyridinium carboxylate compound having a phenyl group or an aralkyl group at the first position, An electroless gold plating solution used to perform metal plating on a metal surface. The method according to claim 1, (iv) an electroless gold plating solution characterized by further comprising at least one compound selected from the group consisting of formic acid and its salts, hydrazine and derivatives thereof as a base metal surface treatment agent. The electroless gold plating solution according to claim 2, wherein the base metal surface treatment agent is a compound selected from hydrazine and derivatives thereof. The electroless gold plating solution according to claim 1, wherein the complexing agent is at least one compound selected from a phosphoric acid group or a salt thereof, or an ethylenediamine derivative having an aminocarboxylic acid group or a salt thereof. The electroless gold plating solution according to claim 1, wherein the pyridinium carboxylate compound having a phenyl group or an aralkyl group in the first position is at least one compound selected from a 1-phenylalkylene pyridinium carboxylate compound. 3. The method of claim 2, (v) at least one compound selected from a polycarboxylic acid and a salt thereof. (i) a water-soluble cyanide gold compound; (ii) at least one compounding agent selected from ethylenediaminetetramethylenephosphonic acid or a derivative thereof; (iii) at least one compound selected from a pyridinium carboxylate compound having a phenyl group or an aralkyl group in the first position; (iv) at least one compound selected from hydrazine and derivatives thereof as a base metal surface treatment agent; And (v) at least one compound selected from a polycarboxylic acid and a salt thereof. An electroless gold plating solution used to perform metal plating on a nickel or copper surface. The electroless gold plating solution according to claim 7, wherein the pyridinium carboxylate compound having a phenyl group or an aralkyl group in the first position is 1-benzylpyridinium-3-carboxylic acid or a carboxylate thereof. 8. The plating solution according to claim 7, wherein the pH is less than 5 to 7.