WO2016035645A1 - Palladium plating solution and palladium coating obtained using same - Google Patents

Palladium plating solution and palladium coating obtained using same Download PDF

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Publication number
WO2016035645A1
WO2016035645A1 PCT/JP2015/074073 JP2015074073W WO2016035645A1 WO 2016035645 A1 WO2016035645 A1 WO 2016035645A1 JP 2015074073 W JP2015074073 W JP 2015074073W WO 2016035645 A1 WO2016035645 A1 WO 2016035645A1
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Prior art keywords
palladium
methyl
ethyl
propyl
butyl
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PCT/JP2015/074073
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French (fr)
Japanese (ja)
Inventor
歓三 清原
和也 柴田
隆太 大須賀
中川 裕介
祐弥 大久保
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日本高純度化学株式会社
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Application filed by 日本高純度化学株式会社 filed Critical 日本高純度化学株式会社
Priority to JP2016546588A priority Critical patent/JP6620103B2/en
Priority to KR1020177004224A priority patent/KR102482321B1/en
Priority to CN201580044246.1A priority patent/CN106661735B/en
Publication of WO2016035645A1 publication Critical patent/WO2016035645A1/en

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    • CCHEMISTRY; METALLURGY
    • C23COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23CCOATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/16Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
    • C23C18/31Coating with metals
    • C23C18/42Coating with noble metals
    • CCHEMISTRY; METALLURGY
    • C23COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23CCOATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/16Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
    • C23C18/31Coating with metals
    • C23C18/42Coating with noble metals
    • C23C18/44Coating with noble metals using reducing agents
    • CCHEMISTRY; METALLURGY
    • C23COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23CCOATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/16Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
    • C23C18/52Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating using reducing agents for coating with metallic material not provided for in a single one of groups C23C18/32 - C23C18/50
    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25DPROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D3/00Electroplating: Baths therefor
    • C25D3/02Electroplating: Baths therefor from solutions
    • C25D3/50Electroplating: Baths therefor from solutions of platinum group metals

Definitions

  • the present invention relates to a palladium plating solution having a specific composition, a palladium film obtained by using the palladium plating solution, and in particular, a palladium film on a nickel, nickel alloy, copper or copper alloy film.
  • Precious metal plating particularly gold plating
  • gold plating is widely used because it has excellent corrosion resistance, mechanical characteristics, electrical characteristics, and the like.
  • the gold plating applied on the nickel coating is widely used in the field of electronic and electrical parts because gold has excellent corrosion resistance, mechanical characteristics, electrical characteristics, etc., and nickel has excellent heat resistance as a base metal. It is used.
  • the gold film has been thinned to reduce the cost, and the film physical properties such as heat resistance, which are insufficient due to the thinning of the gold film, can be reduced between the nickel and gold.
  • a method of compensating by forming a film has been proposed and put into practical use.
  • defective parts such as pinholes are generated in the formed palladium film, and the film properties such as heat resistance as expected may not be obtained.
  • Patent Document 1 the pH of the bath is adjusted to 5 to 10, an amine compound and ammonia are used in combination as a complexing agent, and an organic compound containing divalent sulfur is blended.
  • a palladium plating solution is disclosed, and when the plating film is thickened using the palladium plating solution of Patent Document 1, the plating film has a particularly good appearance and a plating film with few cracks can be obtained. The effect is disclosed.
  • Patent Document 2 discloses that an electroless palladium plating solution using a high molecular weight polyethyleneimine having a molecular weight of 300 to 100,000 and an unsaturated alkylamine is excellent in bath stability and is generated in the resulting palladium plating layer. It is disclosed that a uniform and dense film can be formed while reducing or preventing internal stress.
  • Patent Document 3 discloses a complexing agent selected from amines in combination with a palladium compound and a reducing agent selected from hypophosphorous acid and salts thereof, or a reducing agent selected from formic acid and formate.
  • the plating solution composed of a bath stabilizer selected from inorganic sulfur compounds improves the plating injection time, improves the plating unevenness that is a concern of the electroless palladium-phosphorus plating solution, and elutes nickel during palladium plating. It is disclosed that the amount of the deposited palladium film is suppressed and the thermal diffusion between gold and palladium after the high melting point solder mounting, which is a problem of the electroless pure palladium film, is improved.
  • the present invention has been made in view of the above-described background art, and its problem is to reduce the occurrence of defective parts such as pinholes generated in the palladium film, and to reduce the thickness of the gold plating film formed on the palladium film.
  • it is providing the palladium plating solution which can obtain the heat resistance equivalent to what was formed by the conventional gold plating film thickness.
  • the present inventor solved the above problems by forming a palladium film using a palladium plating solution containing a specific pyridinium compound as an essential component. , And found that it is possible to significantly reduce the production cost while maintaining the heat resistance required for palladium ⁇ gold plating film while significantly reducing the gold film thickness.
  • the invention has been completed.
  • the present invention relates to a soluble palladium salt, as well as an alkyl group bonded to the 1st nitrogen atom, and 1 to 5 of the 2nd to 6th positions are an alkyl group, aryl group, carboxy group, alkoxycarbonyl group, Containing a specific pyridinium compound substituted with one or more specific substituents selected from the group consisting of a sulfo group, an alkoxysulfonyl group, an amino group, an alkylamino group, a dialkylamino group and a cyano group
  • a palladium plating solution is provided.
  • the present invention also provides a palladium film obtained by performing palladium plating on a nickel, nickel alloy, copper or copper alloy film using the palladium plating solution. Is.
  • the present invention also provides a contact member for an electronic component characterized by having the palladium film.
  • the present invention also provides an electroless palladium plating solution and an electrolytic palladium plating solution characterized by comprising the above palladium plating solution.
  • the palladium plating solution of the present invention it is possible to remarkably reduce defective plating portions such as pinholes generated in the palladium film, and greatly improve the heat resistance. If a palladium film is formed using the palladium plating solution of the present invention, the film thickness of the palladium film is reduced from the film thickness of the conventional palladium film formed for the same purpose of reducing the film thickness of the gold plating film. Even if it is reduced, film performance such as excellent heat resistance can be maintained.
  • the thickness of the gold plating film formed on the palladium film can be significantly reduced without causing performance degradation such as heat resistance.
  • further significant cost reduction can be realized. That is, the film thickness of the palladium film can be reduced while maintaining the heat resistance required for “palladium plating film ⁇ gold plating film”, and the film thickness of the gold film can be significantly reduced. Therefore, the cost can be greatly reduced.
  • the palladium plating solution of the present invention contains at least a soluble palladium salt as a palladium source, and further contains the “specific pyridinium compound” shown below.
  • the “specific pyridinium compound” means that an alkyl group is bonded to the 1st nitrogen atom, and 1 to 5 of the 2nd to 6th positions are an alkyl group, aryl group, carboxy group, alkoxycarbonyl group, sulfo group, alkoxy group.
  • an alkyl group (—R 1 ) is bonded to a nitrogen atom, so that the nitrogen atom has a positive charge and is a pyridinium compound.
  • hydrogen atoms are excluded from “bonding atoms that are bonded to nitrogen atoms to form pyridinium compounds”. When the bonding atom bonded to the nitrogen atom is a hydrogen atom, it is difficult to obtain the effect of the present invention described above.
  • the alkyl group (—R 1 ) bonded to the nitrogen atom may be either a linear alkyl group or a branched alkyl group, and the number of carbon atoms is not particularly limited. From the viewpoints of performance and availability, an alkyl group having 1 to 5 carbon atoms is preferable, an alkyl group having 1 to 4 carbon atoms is more preferable, 1 to 3 carbon atoms is particularly preferable, and 1 carbon atom is preferable. Or two is more preferable.
  • the pinhole of palladium film increases, the deposition rate of palladium decreases, the appearance of palladium deteriorates, or it is difficult to obtain There is.
  • the group bonded to the nitrogen atom is not an alkyl group (—R 1 ) but a hydrogen atom
  • the above-described effects of the present invention are not exhibited, and in particular, the palladium concentration in the palladium plating solution is When the concentration is high, appearance defects may occur when plating is performed at a high temperature.
  • the “specific pyridinium compound” in the present invention is essential to have the above chemical structure in the palladium plating solution, and may be changed to one having the above chemical structure in the palladium plating solution.
  • the anion of the “specific pyridinium compound” contained in the palladium plating solution of the present invention is not particularly limited. Specifically, for example, sulfate ion, nitrate ion, chlorine ion, bromine ion, iodine ion, etc. Can be mentioned. Anion exchange (salt exchange) may occur in the palladium plating solution. Therefore, anions such as soluble palladium salt, reducing agent, conductive salt, buffer salt, etc. added (added) at the time of preparation are used. Examples include those obtained by salt exchange with ions.
  • the above-mentioned compositions in the palladium plating solution are included in the scope of the present invention. However, it is preferable to add (prepare using) an anion having the above anions (sulfate ion, nitrate ion, chlorine ion, bromine ion, iodine ion, etc.).
  • any one of 1 to 5 positions out of the 2nd to 6th positions is an alkyl group, aryl group, carboxy group, alkoxycarbonyl group, sulfo group, alkoxysulfonyl group. It is essential that it is substituted with one or more substituents selected from the group consisting of a group, an amino group, an alkylamino group, a dialkylamino group and a cyano group. In the present invention, such a substituent is referred to as a “specific substituent”.
  • the “specific pyridinium compound” in the present invention is a 6-membered pyridine ring (pyridinium ring), and since the nitrogen atom is at position 1, it is bonded to 5 carbon atoms constituting the ring other than the nitrogen atom. Any one of 1 to 5 hydrogen atoms is substituted with the above-mentioned specific substituent which may be different.
  • the alkyl group as the specific substituent may be either a linear alkyl group or a branched alkyl group, and may further have a substituent other than an alkyl group, and the number of carbon atoms is not particularly limited, In order to further exert the effect, an alkyl group having 1 to 6 carbon atoms is preferable, an alkyl group having 1 to 5 carbon atoms is more preferable, and an alkyl group having 1 to 4 carbon atoms, that is, a methyl group or an ethyl group A propyl group or a butyl group is particularly preferred. If an alkyl group having too many carbon atoms is bonded, the palladium deposition rate may be reduced or the appearance of the palladium film may be deteriorated.
  • the aryl group as the specific substituent may have a substituent such as an alkyl group and is not particularly limited. Specific examples thereof include a phenyl group, a naphthyl group, a tolyl group, and a xylyl group. It is done.
  • the carboxy group as the specific substituent is a group represented by “—COOH”, and the “alkoxycarbonyl group” is a group represented by “—COOR 11 ” and is a residue of a carboxylic acid ester.
  • R 11 represents an alkyl group or an aryl group, and preferable one is the same as the alkyl group or aryl group as the specific substituent, and particularly preferably a methyl group.
  • the sulfo group as the specific substituent is a group represented by “—SO 3 H” and is also referred to as a sulfonic acid group.
  • the alkoxysulfonyl group as the specific substituent is a group represented by the following general formula (a) and is a sulfonate residue.
  • R 12 represents an alkyl group or an aryl group.
  • R 12 represents an alkyl group or an aryl group, but preferred ones are the same as the alkyl group and aryl group as the specific substituent, and more preferably a methyl group.
  • the amino group as the specific substituent is a group represented by “—NH 2 ”, the alkylamino group is a group represented by “—NHR 13 ”, and the dialkylamino group is represented by “—NR 14 R”. 15 ".
  • R 13 , R 14 , and R 15 each represent an alkyl group or an aryl group that may be different from each other, and preferable ones are the same as the alkyl group and aryl group as the specific substituent, A methyl group is preferred.
  • the cyano group as the specific substituent is a group represented by “—CN”.
  • the specific substituent may have a substituent in the specific substituent as long as the effects of the invention of the present invention are not impaired. Although it is not necessarily limited from the viewpoints of easiness and the like, it is particularly preferable that the specific substituent does not further have a substituent.
  • the 6-membered pyridine ring may have a substituent other than the specific substituent at the 2-position to the 6-position, as long as the effects of the present invention are not impaired.
  • the “substituents other than the specific substituents” are not particularly limited, but are particularly preferably not included.
  • the one or two or more substituents selected from the group consisting of an alkyl group, a carboxy group, an alkoxysulfonyl group, and an amino group are substituted. It is particularly preferable from the viewpoints of easy performance, good plating performance, availability, and the like.
  • the palladium plating solution of the present invention contains a pyridinium compound in which one to three of the 2-position to 4-position of the pyridinium ring are substituted with one or more of the above-mentioned specific substituents. It is preferable in that the effect is more suitably exhibited. That is, in other words, a pyridinium compound in which any one of the 2-position, 3-position, or 4-position of the pyridinium ring is substituted with one or more specific substituents. It is preferable to contain. More preferably, one or two (particularly preferably one) of the 2-position to the 4-position of the pyridinium ring is substituted with one or two (particularly preferably one) of the specific substituents. It contains a pyridinium compound.
  • the pyridinium ring may have a substituent other than the specific substituent, but preferably has no substituent.
  • Particularly preferred pyridinium compounds are those represented by the following general formula (1).
  • R 1 represents an alkyl group
  • R 2 , R 3, and R 4 may be different from each other, hydrogen atom, alkyl group, aryl group, carboxy group, alkoxycarbonyl group, sulfo group.
  • the alkyl group (R 1 ) bonded to the nitrogen atom may be either a linear alkyl group or a branched alkyl group, and the carbon number is not particularly limited, but an alkyl group having 1 to 6 carbon atoms is preferable, and the carbon number is 1 More preferred are ⁇ 5 alkyl groups, and particularly preferred are alkyl groups having 1 to 4 carbon atoms, ie, methyl group, ethyl group, propyl group or butyl group. If an alkyl group having too many carbon atoms is bonded, the effect of the present invention described above will not be exhibited, the pinhole of the palladium film will increase, the deposition rate of palladium will decrease, and the appearance of palladium will be poor.
  • the group bonded to the nitrogen atom is not an alkyl group but a hydrogen atom
  • the effect of the present invention described above is not exhibited, particularly when the palladium concentration in the palladium plating solution is high, An appearance defect may occur when plating is performed at a high temperature.
  • R 2 , R 3 and R 4 may be different from each other, hydrogen atom, alkyl group, aryl group, carboxy group, alkoxycarbonyl group, sulfo group, alkoxysulfonyl group, amino group, alkylamino group, dialkylamino group Or a cyano group, except that R 2 , R 3 and R 4 are all hydrogen atoms.
  • R 2 , R 3 and R 4 the “specific substituent” described above as “more preferable”, “particularly preferable” and the like is more (particularly) more preferable in that the above-described effects are more suitably exhibited.
  • the anion (counter ion) of the general formula (1) is not particularly limited, but specifically, for example, preferable examples include those described above such as sulfate ion, nitrate ion, chlorine ion, bromine ion, iodine ion and the like. Is mentioned.
  • the anion of the general formula (1) specifies the form present in the palladium plating solution of the present invention, and is added (added) to the soluble palladium salt, reducing agent, conductive salt, buffer, which is blended at the time of preparation. Those obtained by salt exchange with anions such as agent salts are also preferred.
  • sulfate ions, nitrate ions, chlorine ions, bromine ions, iodine ions and the like are preferable as the anions (counter ions) of the raw material to be dissolved (formulated and added) in the preparation of the palladium plating solution of the present invention.
  • the above description of the specific pyridinium compound specifies the form present in the palladium plating solution of the present invention.
  • a palladium film without a pinhole By including a specific pyridinium compound, a palladium film without a pinhole can be realized. In addition, by containing a specific pyridinium compound, it has high heat resistance that is dramatically superior to that of the conventional palladium film, so that the film thickness of the conventional palladium film can be greatly reduced. The gold plating film to be formed can be greatly reduced in thickness, and the cost can be greatly reduced.
  • the palladium plating solution of the present invention capable of realizing a palladium film having no pinhole with “a 0.03 ⁇ m-thickness palladium film” is used, even if the palladium film is thinner than that, If the palladium film is thicker than that, a pinhole-free film is obtained and the reliability is further increased.
  • gold films are generally difficult to make pinholes, and palladium films are generally easy to make pinholes. Therefore, when the palladium plating solution of the present invention which is difficult to form pinholes is used, it is not necessary to cover the pinholes of the palladium film with a gold film, the film thickness of the gold film can be reduced, and the cost can be reduced.
  • a palladium plating solution that gives a palladium film with a small energization current is considered to be excellent.
  • An excellent palladium plating solution is a palladium plating solution that always provides film properties such that the energization current is 100 ⁇ A or less.
  • heat resistance is defined as the value evaluated by the method described in the examples and evaluated as such.
  • Heat resistance is a performance essential for a contact member of an electronic component.
  • the contact member of an electronic component must be joined to another member by soldering or wire bonding, and the joining process always includes a heating process of 100 ° C. to 300 ° C. This heating process is also performed once. It often exists multiple times. This heating process oxidizes metals such as copper, copper alloy, nickel, nickel alloy, etc., causing defects such as poor solder joints, increased contact resistance, and poor wire bonding joints. Therefore, it is important to form a surface protective layer by performing noble metal plating such as gold plating or palladium plating for the purpose of preventing the oxidation of copper, nickel and the like.
  • the specific pyridinium compound for example, 1-methyl-2-methylpyridinium, 1-methyl-2-ethylpyridinium, 1-methyl-2-butylpyridinium, 1-methyl-2-sulfopyridinium, 1-methyl-2-methoxysulfonylpyridinium, 1-methyl- 2-position-substituted methylpyridinium such as 2-aminopyridinium, 1-methyl-2-carboxypyridinium, 1-methyl-2-methoxycarbonylpyridinium, 1-methyl-2-phenylpyridinium, 1-methyl-2-cyanopyridinium; 1-ethyl-2-methylpyridinium, 1-ethyl-2-ethylpyridinium, 1-ethyl-2-butylpyridinium, 1-ethyl-2-sulfopyridinium, 1-ethyl-2-methoxysulfonylpyridinium, 1-ethyl- 2-substituted
  • the content of the specific pyridinium compound is not particularly limited, but is preferably 1 ppm to 50000 ppm, more preferably 10 ppm to 30000 ppm, and particularly preferably 20 ppm to 10000 ppm by mass with respect to the total palladium plating solution. Preferably, it is 50 ppm to 5000 ppm, and most preferably 100 ppm to 3000 ppm.
  • the said numerical value shows those total content.
  • the above description about the specific pyridinium compound specifies the form existing in the palladium plating solution of the present invention, but the above-mentioned specific as a raw material to be dissolved in the preparation of the palladium plating solution of the present invention. It is preferable to use a pyridinium compound.
  • soluble palladium salt It is essential for the palladium plating solution of the present invention to contain a soluble palladium salt.
  • the soluble palladium salt is used as a palladium source for the palladium plating solution of the present invention.
  • the soluble palladium salt is not limited to one type of use, and two or more types can be used in combination. The meaning of “soluble” means soluble in water.
  • the soluble palladium salt is not particularly limited and known ones can be used. Specific examples include palladium chloride, palladium sulfate, palladium acetate, palladium nitrate, palladium oxide, dichlorotetraammine palladium, dinitrodiammine palladium, dichloromethane. Diethylenediamine palladium, tetrakis (triphenylphosphine) palladium, dichlorobis (triphenylphosphine) palladium and / or bis (acetylacetonato) palladium are preferable because of their solubility in water and availability.
  • dichlorotetraamminepalladium or dinitrodiamminepalladium is more preferable from the viewpoint that it is not time-consuming to replenish the palladium salt by being supplied as an aqueous solution. Further, from the same viewpoint, dichlorotetraammine palladium is particularly preferable.
  • the content of the palladium salt in the palladium plating solution of the present invention is not particularly limited, and is generally 0.001 g / L to 50 g / L, preferably 0.005 g / L as metal palladium with respect to the whole palladium plating solution. -30 g / L, particularly preferably 0.01 g / L to 20 g / L. If the content of the soluble palladium salt in the palladium plating solution is too small, it may be difficult to form a palladium film having a normal and uniform color tone. That is, there is a case where an abnormal precipitation of palladium is observed when the color and attached color of the palladium film are visually observed.
  • the palladium salt content in the palladium plating solution is too high, there is no particular problem with the performance of the palladium plating solution, but the palladium salt is very expensive and is stored in the palladium plating solution. Doing so can be uneconomical.
  • the above description about the palladium salt specifies the form present in the palladium plating solution of the present invention.
  • the above palladium salt is used as a raw material to be dissolved in the preparation of the palladium plating solution of the present invention. It is preferable to use it.
  • the palladium plating solution of the present invention preferably further contains a reducing agent in addition to the soluble palladium salt and the specific pyridinium compound.
  • a reducing agent hypophosphorous acid, hypophosphite, phosphorous acid, phosphite, formic acid, formate, formaldehyde and the like are particularly preferable.
  • Said reducing agent is not limited to 1 type of use, It can use 2 or more types together.
  • the reducing agent include hypophosphorous acid, sodium hypophosphite, potassium hypophosphite, ammonium hypophosphite, phosphorous acid, sodium phosphite, potassium phosphite, Ammonium phosphite, formic acid, sodium formate, potassium formate, ammonium formate, formaldehyde, etc. have good palladium plating performance, ease of dissolution in water, easy handling as chemicals, easy availability, low cost From the viewpoint of the above, it is preferable.
  • the content of the reducing agent in the palladium plating solution of the present invention is not particularly limited, but is preferably from 1 ppm to 100,000 ppm, more preferably from 10 ppm to 60000 ppm, particularly preferably from 50 ppm to 30000 ppm, based on the whole palladium plating solution. More preferably, it is 100 ppm to 10,000 ppm.
  • the said numerical value shows those total content. If the content is too small, it may be difficult to form a palladium film having a normal and uniform color tone. That is, there is a case where an abnormal precipitation of palladium is observed when the color and attached color of the palladium film are visually observed.
  • the content is too high, the palladium plating bath becomes unstable, and expensive palladium is abnormally deposited in the storage container, which requires extra costs for palladium recovery, or the color tone of the palladium film is poor. It may cause.
  • the palladium plating solution of the present invention includes, as necessary, a buffer for keeping the pH of the palladium plating solution constant, a conductive salt for ensuring the conductivity of the palladium plating solution, and a palladium plating solution.
  • a buffer for keeping the pH of the palladium plating solution constant for keeping the pH of the palladium plating solution constant
  • a conductive salt for ensuring the conductivity of the palladium plating solution a palladium plating solution.
  • the buffer contained in the palladium plating solution of the present invention as needed is not particularly limited as long as it is a known buffer, but preferred are inorganic acids such as boric acid and phosphoric acid; citric acid and tartaric acid. And oxycarboxylic acids such as malic acid; These can be used alone or in combination of two or more.
  • the content of the buffer in the palladium plating solution of the present invention is not particularly limited, but is usually 1 g / L to 500 g / L, preferably 10 g / L to 100 g / L, based on the whole palladium plating solution. If the content of the buffering agent in the palladium plating solution is too small, the buffering effect may be difficult to be exhibited. On the other hand, if the content is too large, the buffering effect may not be increased and it may be uneconomical.
  • the conductive salt contained as needed in the palladium plating solution of the present invention is not particularly limited as long as it is a known conductive salt, but preferred are inorganic acid salts such as sulfates, nitrates and phosphates; And carboxylic acids such as oxalic acid, succinic acid, glutaric acid, malonic acid, citric acid, tartaric acid and malic acid. These may be used alone or in combination of two or more.
  • the content of the conductive salt in the palladium plating solution of the present invention is not particularly limited, but is usually 1 g / L to 500 g / L, preferably 10 g / L to 100 g / L, based on the whole palladium plating solution. If the content of the conductive salt in the palladium plating solution is too small, the conductive effect may be difficult to be exhibited. On the other hand, if the content is too high, the conductive effect may not be increased, which may be uneconomical. It is also possible to share the same component as the buffer.
  • the sequestering agent contained as needed in the palladium plating solution of the present invention is not particularly limited as long as it is a well-known sequestering agent, but as preferred, iminodiacetic acid, nitrilotriacetic acid, ethylenediaminetetraacetic acid, etc.
  • the content of the sequestering agent in the palladium plating solution of the present invention is not particularly limited, but is usually 0.1 g / L to 100 g / L, preferably 0.5 g / L to 50 g based on the whole palladium plating solution. / L. If the content of the sequestering agent in the palladium plating solution is too small, the effect of removing the influence of the impurity metal may be difficult to be exhibited, while if too much, the effect of removing the influence of the impurity metal may be increased. It may not be seen and it may be uneconomical.
  • the surfactant contained as needed in the palladium plating solution of the present invention is not particularly limited as long as it is a known surfactant, and is a nonionic surfactant, an anionic surfactant, an amphoteric surfactant or Cationic surfactants are used. These may be used alone or in combination of two or more.
  • Preferred nonionic surfactants include ether type nonionic surfactants such as noniphenol polyalkoxylate, ⁇ -naphthol polyalkoxylate, dibutyl- ⁇ -naphthol polyalkoxylate, and styrenated phenol polyalkoxylate; And amine type nonionic surfactants such as octylamine polyalkoxylate, hexynylamine polyalkoxylate, and linoleylamine polyalkoxylate.
  • ether type nonionic surfactants such as noniphenol polyalkoxylate, ⁇ -naphthol polyalkoxylate, dibutyl- ⁇ -naphthol polyalkoxylate, and styrenated phenol polyalkoxylate
  • amine type nonionic surfactants such as octylamine polyalkoxylate, hexynylamine polyalkoxylate, and linoleylamine polyalkoxylate
  • anionic surfactant examples include alkyl sulfates such as sodium lauryl sulfate; polyoxyethylene alkyl ether sulfates such as sodium polyoxyethylene nonyl ether sulfate; polyoxyethylene alkylphenyl ether sulfates; Salt; and the like.
  • amphoteric surfactant examples include 2-undecyl-1-carboxymethyl-1-hydroxyethylimidazolium, N-stearyl-N, N-carboxymethylbetaine, lauryldimethylamine oxide, and the like.
  • Preferred examples of the cationic surfactant include lauryltrimethylammonium salt, lauryldimethylammonium betaine, laurylpyridinium salt, oleylimidazolium salt, and stearylamine acetate.
  • surfactants can be used alone or in combination of two or more.
  • Nonionic surfactants or amphoteric surfactants are preferred.
  • the content of the surfactant in the palladium plating solution of the present invention is preferably 0.01 g / L to 20 g / L with respect to the whole palladium plating solution.
  • the amount is not limited.
  • the brightener contained as needed in the palladium plating solution of the present invention is not particularly limited as long as it is a well-known brightener. However, it cannot be a specific pyridinium compound in the present invention during palladium plating. And the like ". These may be used alone or in combination of two or more.
  • Examples of the amine compound having a pyridine skeleton include 2-aminopyridine, 3-aminopyridine, 4-aminopyridine and the like.
  • the content of the brightener in the palladium plating solution of the present invention is preferably 0.01 g / L to 20 g / L with respect to the whole palladium plating solution, but it is sufficient that the desired performance is exhibited, and particularly the content. It is not intended to limit.
  • a substrate plated by using a palladium plating solution so that the film thickness of the palladium film is 0.03 ⁇ m is immersed in a 5% by mass sulfuric acid aqueous solution.
  • the pinhole test is performed at a constant voltage of 300 mV, it is a palladium plating solution that gives film properties such that the energization current is 100 ⁇ A or less during the entire period from the start of the test to 5 minutes after the start of the test.
  • the palladium plating solution having such physical properties is a novel palladium plating solution realized for the first time with the palladium plating solution having the above-described composition.
  • the palladium plating solution of the present invention is a 5% by mass sulfuric acid copper substrate plated on a copper plate to have an electroless nickel plating film thickness of 5 ⁇ m and a palladium film thickness of 0.03 ⁇ m.
  • a current does not flow more than 100 ⁇ A for 5 minutes from the start of the test.
  • the “pinhole test” of the present invention is a copper plate material that has been electrolessly nickel-plated and then palladium-plated by a conventional method, removing copper in a circular shape with a diameter of 10 mm to form an anode, and copper A test in which a material is immersed in a 5% by mass sulfuric acid solution as a cathode, a voltage of 300 mV is continuously applied, and a current value to be energized is observed.
  • a defective part such as a pinhole is generated in the palladium film
  • nickel ions and copper ions are dissolved from the pinhole of the palladium film as the anode, and the flowing current value shows a large value.
  • the current starts to flow relatively quickly as compared with an evaluation sample in which a defective portion such as a pinhole is not formed on the palladium film.
  • the limitation of the physical properties described above limits the physical properties of the palladium plating solution, and does not limit the method of using the palladium plating solution.
  • the palladium film actually formed with such a palladium plating solution does not need to be 0.03 ⁇ m.
  • a palladium film having a thickness of less than 0.03 ⁇ m may be formed using the palladium plating solution of the present invention.
  • a palladium film thicker than 0.03 ⁇ m may be formed.
  • the method for producing the palladium plating solution of the present invention is not particularly limited, and known methods including the blending order of each component and the like are used.
  • the palladium film obtained by performing palladium plating using the palladium plating solution of the present invention exhibits the effects described above.
  • the concentration of palladium in the palladium film of the present invention is not particularly limited, but is preferably 90% by mass or more, and 95.0% to 99.99% by mass with respect to the entire “palladium film”. 9% by mass is particularly preferred.
  • the plating conditions of the palladium plating solution of the present invention described above are not particularly limited, but the temperature conditions are preferably 20 ° C. to 90 ° C., particularly preferably 30 ° C. to 70 ° C.
  • the pH of the plating solution is preferably pH 2.0 to 9.0, particularly preferably pH 3.0 to 8.0.
  • the film thickness of the palladium film obtained by performing palladium plating using the palladium plating solution of the present invention is not particularly limited, but is preferably 0.0001 ⁇ m to 5 ⁇ m, more preferably 0.001 ⁇ m to 1 ⁇ m, and particularly preferably 0. 0.005 ⁇ m to 0.5 ⁇ m, more preferably 0.01 ⁇ m to 0.3 ⁇ m.
  • the film thickness of a palladium plating film produced using a conventional palladium plating solution is usually 0.01 ⁇ m to 0.5 ⁇ m in the case of a connector, although it depends on the application.
  • the palladium plating film produced using the palladium plating solution of the present invention can obtain almost the same pinhole test and heat resistance results even when the film thickness is reduced to the conventional range of 30% to 60%.
  • a palladium film obtained by performing palladium plating on a nickel, nickel alloy, copper, or copper alloy film using the palladium plating solution of the present invention is preferable in order to achieve the above-described effects.
  • a nickel or nickel alloy film is more preferable from the viewpoints of heat resistance and the possibility that it may be adversely affected when mixed with palladium plating, and a nickel film is particularly preferable.
  • the palladium plating solution of the present invention is not particularly limited, but is more preferably used for manufacturing a contact member for an electronic component. Therefore, when performing palladium plating using the palladium plating solution of the present invention, it is more preferable to form a nickel plating film as the base plating treatment.
  • the nickel plating solution at this time is not particularly limited, but an electroless nickel solution generally used in practice is preferred, and an electroless nickel-phosphorus solution is particularly preferred.
  • the method of using the nickel plating solution is not particularly limited and is used according to a conventional method.
  • the thickness of the nickel plating film is not particularly limited, but is preferably 0.01 ⁇ m to 20 ⁇ m, and particularly preferably 0.05 ⁇ m to 5 ⁇ m.
  • the palladium plating solution of the present invention is preferably used for forming a base palladium film for forming a gold film by performing gold plating on the palladium film.
  • the thickness of the gold plating film is not particularly limited, but is preferably 0.0001 ⁇ m to 5 ⁇ m, more preferably 0.001 ⁇ m to 1 ⁇ m, and particularly preferably 0.01 ⁇ m to 0.5 ⁇ m.
  • a preferred coating mode of the present invention is a mode in which a gold coating is applied on a palladium coating, and a particularly preferable mode is a mode in which a palladium coating is applied on a nickel coating and a gold coating is applied thereon. It is.
  • the film thickness of a gold film formed on a palladium plating film produced using a conventional palladium plating solution is usually 0.05 ⁇ m to 0.2 ⁇ m in the case of a connector, although it depends on the application.
  • the film thickness of the gold film formed on the palladium plating film produced using the palladium plating solution of the present invention is almost equal to the pinhole even when the film thickness is reduced to the conventional range of 20% to 60%. Test and heat resistance results are obtained.
  • the palladium plating solution of the present invention can be used as an electroless palladium plating solution or an electrolytic palladium plating solution. That is, the present invention is an electroless palladium plating solution made of the palladium plating solution and an electrolytic palladium plating solution made of the palladium plating solution.
  • the above-mentioned “specific pyridinium compound” exerts the above-described effect regardless of whether it is contained in the electroless palladium plating solution or in the electrolytic palladium plating solution.
  • soluble palladium salts specific pyridinium compounds, buffers, conductive salts, sequestering agents, surfactants, reducing agents and brighteners, electroless palladium plating solutions are soluble palladium salts, specific pyridinium compounds and reducing agents.
  • An agent is an essential component, and a buffering agent, a sequestering agent, a surfactant and / or a brightener are included as preferred components.
  • the electrolytic palladium plating solution contains a soluble palladium salt, a specific pyridinium compound and a conductive salt as essential components, and a buffer, a metal ion sequestering agent, a surfactant and / or a brightening agent as preferred components.
  • the content of each component of the electroless palladium plating solution and the electrolytic palladium plating solution is preferably in the above range (more preferably, particularly preferable).
  • the liquid temperature is preferably 30 ° C to 90 ° C, particularly preferably 40 ° C to 80 ° C.
  • the time is appropriately adjusted so that the palladium film thickness is obtained.
  • the liquid temperature is preferably 30 ° C. to 90 ° C., particularly preferably 40 ° C. to 80 ° C.
  • the current density of 0.1A / dm 2 ⁇ 100A / dm 2, 0.5A / dm 2 ⁇ 50A / dm 2 are particularly preferred. The time is appropriately adjusted so that the palladium film thickness is obtained.
  • the specific pyridinium compound that is an essential component of the palladium plating solution of the present invention is considered to have an effect as a kind of crystal modifier.
  • a palladium film is about to be formed by a plating reaction, it is considered that a very rough film grows when the palladium film grows without any control.
  • a rough film means a film having irregularities.
  • the “specific pyridinium compound” is selectively adsorbed on the convex portions and inhibits the growth. By inhibiting plating growth at the convex part where plating growth was fast, the plating reaction to the concave part was promoted and the concave part was filled, and as a result, a plating film without unevenness could be formed. Conceivable.
  • the plating film having no concave portion is a palladium film in which the base metal is uniformly coated with a palladium film and pinholes are extremely small.
  • the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples unless it exceeds the gist.
  • concentration in the composition of a palladium plating solution is a numerical value of the density
  • Examples 1-8, Comparative Examples 1-7 ⁇ Evaluation of electroless palladium plating solution>
  • Dichlorotetraammine palladium solution is 1 g / L in terms of palladium with respect to the entire palladium plating solution
  • each specific pyridinium compound or its comparative compound shown in Table 1 is 1000 ppm
  • formic acid is used as a reducing agent.
  • citric acid was used as a component serving as both a conductive salt and a buffer was adjusted to 100 g / L, and the pH was adjusted to 6.5 to obtain an electroless palladium plating solution.
  • Comparative Example 7 contained neither a specific pyridinium compound nor a comparative compound.
  • the pH of the electroless palladium plating solution was adjusted with a 20% by mass potassium hydroxide aqueous solution and citric acid, the bath temperature of the palladium plating solution was set to 70 ° C., and the following evaluation was performed.
  • electroless nickel plating film was plated according to an ordinary method using “electroless nickel plating solution ICP Nicolon GM” (trade name) (manufactured by Okuno Pharmaceutical Co., Ltd.) to form a film thickness of 5.0 ⁇ m. .
  • ⁇ Pinhole test method As described above, a palladium film having a thickness of 0.03 ⁇ m formed on a nickel plating film on a copper plate is immersed in a 5% by mass sulfuric acid aqueous solution, and POTENTIONSTAT / GALVANOSTAT (manufactured by Hokuto Denko Co., Ltd.) is always used. A constant voltage of 300 mV was applied. Current values ( ⁇ A) at 1 minute, 3 minutes, and 5 minutes from the start of the test were measured.
  • the current value will increase, so from the start of the test until “5 minutes after the start of the test”, it is always judged that the current is 100 ⁇ A or less and that the plating solution is excellent, and the current is smaller. It was determined that the palladium plating solution was more excellent in the case of current.
  • the underlying metal is nickel, the color tone is similar and difficult to judge, but when a uniform palladium film is not formed, a mottled pattern (unevenness) with a size of about 0.5 mm to 3 mm is observed. Therefore, the palladium plating solution in which the mottled pattern (unevenness) was not observed at all was determined to be an excellent palladium plating solution, and when only a less mottled pattern (unevenness) was observed, it was determined to be an excellent palladium plating solution.
  • ⁇ Measurement method of film thickness of palladium film> The thickness of the palladium film was measured in the vicinity of the center of the palladium film on which the palladium plating was performed using a fluorescent X-ray analyzer (SFT 9255, manufactured by Seiko Instruments Inc.) according to a conventional method.
  • SFT 9255 fluorescent X-ray analyzer
  • an evaluation sample was prepared by forming a palladium film with a film thickness of 0.03 ⁇ m on the nickel plating film on the copper plate.
  • a gold film was formed with a predetermined film thickness according to a conventional method to prepare an evaluation sample.
  • the sample for evaluation was heated for 15 hours in an oven whose inside was adjusted to 200 ° C.
  • the surface of the sample for evaluation after heating was measured at an acceleration voltage of 5 kV using a surface Auger; SAM-4300 (manufactured by ULVAC-PHI Co., Ltd.).
  • Evaluation samples satisfying nickel content of less than 10% and copper content of less than 0.5% and palladium plating solutions are judged as “non-defective”, and either nickel or copper is above the specified value.
  • the sample and the palladium plating solution were determined as “defective products”.
  • Examples 11-18 Samples for evaluation similar to those used in Examples 1 to 8 were prepared, and gold films of 0.01 ⁇ m, 0.05 ⁇ m, and 0.1 ⁇ m were formed thereon, respectively.
  • Comparative Examples 11-17 Corresponding samples for evaluation were prepared corresponding to those used in Comparative Examples 1 to 7, and gold films of 0.01 ⁇ m, 0.05 ⁇ m, and 0.1 ⁇ m were formed thereon, respectively.
  • Comparative Examples 11 to 17 When a heat resistance test was conducted, all of Comparative Examples 11 to 17 had a nickel film of 0.1 ⁇ m, which was less than 10% nickel and less than 0.5% copper. In the case of 0.01 ⁇ m and 0.05 ⁇ m gold films, either nickel was 10% or more, or copper was detected 0.5% or more, and both were judged to be defective. In Comparative Examples 11 to 17, it was found that the gold film on the palladium film could not be made sufficiently thin because the heat resistance performance of the palladium film was inferior.
  • Example 21 Evaluation of electrolytic palladium plating solution> With respect to the whole palladium plating solution, the dichlorotetraammine palladium solution is 1 g / L in terms of palladium, the specific pyridinium compound similar to Example 1 (1-methyl-3-carboxypyridinium hydrochloride) is 1000 ppm, and the conductive salt Citric acid was dissolved as a component also serving as a buffer so as to be 100 g / L, and the pH was adjusted to 6.5 to obtain an electrolytic palladium plating solution.
  • the dichlorotetraammine palladium solution is 1 g / L in terms of palladium
  • the specific pyridinium compound similar to Example 1 (1-methyl-3-carboxypyridinium hydrochloride) is 1000 ppm
  • the conductive salt Citric acid was dissolved as a component also serving as a buffer so as to be 100 g / L, and the pH was adjusted to 6.5 to obtain an electrolytic palladium plating
  • Example 21 instead of using the specific pyridinium compound, an electrolytic palladium plating solution was prepared in the same manner as in Example 21 except that the comparative compound (pyridine) of Comparative Example 1 was used.
  • the electroless palladium plating treatment time is adjusted in the range of 30 seconds to 3 minutes so that the film thickness is 0.03 ⁇ m”. Except that the current density of the electrolytic palladium plating treatment was adjusted to 0.5 A / dm 2 before and after 5 seconds so that the film thickness was 0.03 ⁇ m.
  • An evaluation sample was prepared in the same manner as in “Method for forming a test (evaluation) palladium film” in the case of using an electroless palladium plating solution.
  • the palladium film obtained using the palladium plating solution of the present invention has excellent heat resistance characteristics, and can reduce the film thickness of the gold plating film formed on the palladium film due to its excellent heat resistance. Cost reduction can be realized, and it is especially widely used for palladium / gold plating, and it is most suitable for processes having a layer structure of electroless nickel / palladium / gold. Is particularly preferably used.

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Abstract

 The present invention addresses the problem of providing a palladium plating solution in which occurrence of defective parts such as pin holes on a palladium coating is reduced, and in which heat resistance performance equivalent to that obtained conventionally can be obtained even when a gold plating coating formed on the palladium coating is made thinner. The problem was overcome by: a palladium plating solution containing a soluble palladium salt as a palladium source, and a specific pyridinium compound in which an alkyl group is bonded to a nitrogen atom at the 1-position and one to five of the 2- to 6-positions are substituted with one or more specific substituents selected from the group consisting of an alkyl group, an aryl group, a carboxy group, an alkoxycarbonyl group, a sulfo group, an alkoxy sulfonyl group, an amino group, an alkylamino group, a dialkylamino group, and a cyano group; and a palladium coating obtained by performing palladium plating on a nickel, nickel alloy, copper, or copper alloy coating using the palladium plating solution.

Description

パラジウムめっき液及びそれを用いて得られたパラジウム皮膜Palladium plating solution and palladium film obtained using the same
 本発明は、特定の組成を有するパラジウムめっき液、そのパラジウムめっき液を用いて得られたパラジウム皮膜、及び、特に、ニッケル、ニッケル合金、銅又は銅合金の皮膜上のパラジウム皮膜に関するものである。 The present invention relates to a palladium plating solution having a specific composition, a palladium film obtained by using the palladium plating solution, and in particular, a palladium film on a nickel, nickel alloy, copper or copper alloy film.
 貴金属めっき、特に金めっきは、優れた耐食性、機械的特性、電機特性等を有するため、広く用いられている。特に、ニッケル皮膜上に施す金めっきは、金が優れた耐食性、機械的特性、電機特性等を有し、ニッケルが下地金属として優れた耐熱性等を有するため、電子電気部品等の分野で広く用いられている。 Precious metal plating, particularly gold plating, is widely used because it has excellent corrosion resistance, mechanical characteristics, electrical characteristics, and the like. In particular, the gold plating applied on the nickel coating is widely used in the field of electronic and electrical parts because gold has excellent corrosion resistance, mechanical characteristics, electrical characteristics, etc., and nickel has excellent heat resistance as a base metal. It is used.
 近年、生産コストの低減のために、金皮膜を薄膜化してコスト低減し、金皮膜の薄膜化により不足する耐熱性等の皮膜物性を、ニッケルと金との間に、金より安価なパラジウムの皮膜を形成することにより補う方法が提案され、実用化されてきている。
 しかしながら、形成されたパラジウム皮膜にピンホール等の不良部が発生し、期待したような耐熱性等の皮膜物性が得られない場合があるという問題があった。
In recent years, in order to reduce production costs, the gold film has been thinned to reduce the cost, and the film physical properties such as heat resistance, which are insufficient due to the thinning of the gold film, can be reduced between the nickel and gold. A method of compensating by forming a film has been proposed and put into practical use.
However, there is a problem that defective parts such as pinholes are generated in the formed palladium film, and the film properties such as heat resistance as expected may not be obtained.
 この問題を解決するために、特許文献1には、浴のpHを5~10に調整し、錯化剤にアミン化合物とアンモニアを併用し、かつ2価の硫黄を含有する有機化合物を配合したパラジウムめっき液が開示されており、特許文献1のパラジウムめっき液を用いて、めっき皮膜の厚付けを行った場合、該めっき皮膜は、外観が特に良好であり、クラックの少ないめっき皮膜が得られる旨が開示されている。 In order to solve this problem, in Patent Document 1, the pH of the bath is adjusted to 5 to 10, an amine compound and ammonia are used in combination as a complexing agent, and an organic compound containing divalent sulfur is blended. A palladium plating solution is disclosed, and when the plating film is thickened using the palladium plating solution of Patent Document 1, the plating film has a particularly good appearance and a plating film with few cracks can be obtained. The effect is disclosed.
 また、特許文献2には、分子量300~100000の高分子ポリエチレンイミンと不飽和アルキルアミンとを併用した無電解パラジウムめっき液が、その浴安定性に優れ、しかも得られるパラジウムめっき層中に発生する内部応力を低減ないし防止しつつ、均一で緻密な皮膜が形成できる旨が開示されている。 Patent Document 2 discloses that an electroless palladium plating solution using a high molecular weight polyethyleneimine having a molecular weight of 300 to 100,000 and an unsaturated alkylamine is excellent in bath stability and is generated in the resulting palladium plating layer. It is disclosed that a uniform and dense film can be formed while reducing or preventing internal stress.
 また、特許文献3には、パラジウム化合物と、次亜リン酸及びその塩から選ばれる還元剤、又は、ギ酸及びギ酸塩から選ばれる還元剤とを併用し、アミン類から選ばれる錯化剤、及び、無機硫黄化合物から選ばれる浴安定剤により構成されためっき液は、めっきインジェクション時間が改善され、無電解パラジウム-リンめっき液の懸念事項であるめっきムラが改善され、パラジウムめっき時におけるニッケル溶出量が抑制され、析出したパラジウム皮膜は、無電解純パラジウム皮膜の課題である高融点はんだ実装後の金-パラジウム間における熱拡散が改善される旨が開示されている。 Patent Document 3 discloses a complexing agent selected from amines in combination with a palladium compound and a reducing agent selected from hypophosphorous acid and salts thereof, or a reducing agent selected from formic acid and formate. In addition, the plating solution composed of a bath stabilizer selected from inorganic sulfur compounds improves the plating injection time, improves the plating unevenness that is a concern of the electroless palladium-phosphorus plating solution, and elutes nickel during palladium plating. It is disclosed that the amount of the deposited palladium film is suppressed and the thermal diffusion between gold and palladium after the high melting point solder mounting, which is a problem of the electroless pure palladium film, is improved.
 しかしながら、これら従来技術では、更に金を薄膜化し高価な金の使用量を抑え、コストダウンを図りながら、もう一方で、安定な耐熱性能を有する皮膜物性を維持するには充分とは言えず、更なる改良が必要であった。 However, in these conventional technologies, it is not sufficient to maintain film physical properties having stable heat resistance performance while reducing the cost by reducing the amount of gold used by further thinning the gold and reducing the cost. Further improvements were needed.
特開昭62-124280号公報Japanese Patent Laid-Open No. 62-124280 特開平5-039580号公報Japanese Patent Laid-Open No. 5-039580 特開2010-261082号公報JP 2010-261082 A
 本発明は、上記背景技術に鑑みてなされたものであり、その課題は、パラジウム皮膜に発生するピンホール等の不良部の発生を少なくし、パラジウム皮膜上に形成される金めっき皮膜を薄膜化しても、従来の金めっき膜厚で形成されたものと同等の耐熱性能を得ることが可能なパラジウムめっき液を提供することにある。 The present invention has been made in view of the above-described background art, and its problem is to reduce the occurrence of defective parts such as pinholes generated in the palladium film, and to reduce the thickness of the gold plating film formed on the palladium film. However, it is providing the palladium plating solution which can obtain the heat resistance equivalent to what was formed by the conventional gold plating film thickness.
 本発明者は、上記課題を解決すべく鋭意検討を重ねた結果、特定のピリジニウム化合物を必須成分として含有するパラジウムめっき液を用いてパラジウム皮膜を形成すれば、前期問題点を解消し、上記課題を解決し、パラジウム\金めっき皮膜に要求される耐熱特性を維持したまま、その金膜厚の大幅な薄膜化を実現し、生産コストを大幅に低減することが可能となることを見出し、本発明の完成に至った。 As a result of intensive studies to solve the above-mentioned problems, the present inventor solved the above problems by forming a palladium film using a palladium plating solution containing a specific pyridinium compound as an essential component. , And found that it is possible to significantly reduce the production cost while maintaining the heat resistance required for palladium \ gold plating film while significantly reducing the gold film thickness. The invention has been completed.
 すなわち、本発明は、可溶性パラジウム塩、並びに、1位の窒素原子にアルキル基が結合され、2位ないし6位の1個ないし5個が、アルキル基、アリール基、カルボキシ基、アルコキシカルボニル基、スルホ基、アルコキシスルホニル基、アミノ基、アルキルアミノ基、ジアルキルアミノ基及びシアノ基からなる群より選ばれた1種又は2種以上の特定置換基で置換された特定ピリジニウム化合物を含有することを特徴とするパラジウムめっき液を提供するものである。 That is, the present invention relates to a soluble palladium salt, as well as an alkyl group bonded to the 1st nitrogen atom, and 1 to 5 of the 2nd to 6th positions are an alkyl group, aryl group, carboxy group, alkoxycarbonyl group, Containing a specific pyridinium compound substituted with one or more specific substituents selected from the group consisting of a sulfo group, an alkoxysulfonyl group, an amino group, an alkylamino group, a dialkylamino group and a cyano group A palladium plating solution is provided.
 また、本発明は、上記のパラジウムめっき液を用いて、ニッケル、ニッケル合金、銅又は銅合金の皮膜上にパラジウムめっきを行うことによって得られたものであることを特徴とするパラジウム皮膜を提供するものである。 The present invention also provides a palladium film obtained by performing palladium plating on a nickel, nickel alloy, copper or copper alloy film using the palladium plating solution. Is.
 また、本発明は、上記のパラジウム皮膜を有することを特徴とする電子部品の接点部材を提供するものである。 The present invention also provides a contact member for an electronic component characterized by having the palladium film.
 また、本発明は、上記のパラジウムめっき液よりなることを特徴とする無電解パラジウムめっき液、及び、電解パラジウムめっき液を提供するものである。 The present invention also provides an electroless palladium plating solution and an electrolytic palladium plating solution characterized by comprising the above palladium plating solution.
 本発明のパラジウムめっき液によれば、パラジウム皮膜に生成するピンホール等のめっき不良部分を著しく低減させ、耐熱性能を飛躍的に向上させることが可能である。
 本発明のパラジウムめっき液を用いてパラジウム皮膜を形成させれば、該パラジウム皮膜の膜厚を、金めっき皮膜の膜厚を低減するという同じ目的で形成していた従来のパラジウム皮膜の膜厚から低減しても、優れた耐熱特性等の皮膜性能を維持できる。
According to the palladium plating solution of the present invention, it is possible to remarkably reduce defective plating portions such as pinholes generated in the palladium film, and greatly improve the heat resistance.
If a palladium film is formed using the palladium plating solution of the present invention, the film thickness of the palladium film is reduced from the film thickness of the conventional palladium film formed for the same purpose of reducing the film thickness of the gold plating film. Even if it is reduced, film performance such as excellent heat resistance can be maintained.
 また、本発明のパラジウムめっき液を用いてパラジウム皮膜を形成させれば、該パラジウム皮膜の上に形成する金めっき皮膜の膜厚を、耐熱性等の性能低下をもたらさずに、大幅に薄膜化することが可能となり、その結果、更に大幅なコストダウンを実現することができる。
 すなわち、「パラジウムめっき皮膜\金めっき皮膜」に要求される耐熱特性を維持したまま、パラジウム皮膜の膜厚を低減でき、また、金皮膜の膜厚を著しく低減できる。そのため、コストを大幅に低減することが可能となる。
In addition, if a palladium film is formed using the palladium plating solution of the present invention, the thickness of the gold plating film formed on the palladium film can be significantly reduced without causing performance degradation such as heat resistance. As a result, further significant cost reduction can be realized.
That is, the film thickness of the palladium film can be reduced while maintaining the heat resistance required for “palladium plating film \ gold plating film”, and the film thickness of the gold film can be significantly reduced. Therefore, the cost can be greatly reduced.
 以下、本発明について説明するが、本発明は以下の実施の具体的形態に限定されるものではなく、技術的思想の範囲で任意に変形して実施することができる。 Hereinafter, the present invention will be described, but the present invention is not limited to the following specific embodiments, and can be carried out by being arbitrarily modified within the scope of the technical idea.
<特定ピリジニウム化合物>
 本発明のパラジウムめっき液は、少なくとも、可溶性パラジウム塩をパラジウム源として含有し、更に、以下に示す「特定ピリジニウム化合物」を含有することが必須である。
 「特定ピリジニウム化合物」とは、1位の窒素原子にアルキル基が結合され、2位ないし6位の1個ないし5個が、アルキル基、アリール基、カルボキシ基、アルコキシカルボニル基、スルホ基、アルコキシスルホニル基、アミノ基、アルキルアミノ基、ジアルキルアミノ基及びシアノ基からなる群より選ばれた1種又は2種以上の特定置換基で置換されたピリジニウム化合物をいう。
<Specific pyridinium compounds>
The palladium plating solution of the present invention contains at least a soluble palladium salt as a palladium source, and further contains the “specific pyridinium compound” shown below.
The “specific pyridinium compound” means that an alkyl group is bonded to the 1st nitrogen atom, and 1 to 5 of the 2nd to 6th positions are an alkyl group, aryl group, carboxy group, alkoxycarbonyl group, sulfo group, alkoxy group. A pyridinium compound substituted with one or more specific substituents selected from the group consisting of a sulfonyl group, an amino group, an alkylamino group, a dialkylamino group and a cyano group.
 「特定ピリジニウム化合物」においては、窒素原子にアルキル基(-R)が結合されていることによって、該窒素原子はプラス電荷を有し、ピリジニウム化合物となっている。本発明においては、「窒素原子に結合してピリジニウム化合物となる結合原子」から水素原子は除かれる。窒素原子に結合している結合原子が水素原子の場合には、前記した本発明の効果が得られ難い。 In the “specific pyridinium compound”, an alkyl group (—R 1 ) is bonded to a nitrogen atom, so that the nitrogen atom has a positive charge and is a pyridinium compound. In the present invention, hydrogen atoms are excluded from “bonding atoms that are bonded to nitrogen atoms to form pyridinium compounds”. When the bonding atom bonded to the nitrogen atom is a hydrogen atom, it is difficult to obtain the effect of the present invention described above.
 窒素原子に結合したアルキル基(-R)は、直鎖アルキル基又は分岐アルキル基の何れでもよく、炭素数も特に限定はないが、前記した本発明の効果を発揮し易く、良好なめっき性能、入手の容易さ等の点から、炭素数1~5個のアルキル基が好ましく、炭素数1~4個のアルキル基がより好ましく、炭素数1~3個が特に好ましく、炭素数1個又は2個が更に好ましい。
 炭素数の多過ぎるアルキル基が結合していると、パラジウム皮膜のピンホールが増加したり、パラジウムの析出速度が低下したり、パラジウムの外観不良が発生したり、入手が困難であったりする場合がある。
The alkyl group (—R 1 ) bonded to the nitrogen atom may be either a linear alkyl group or a branched alkyl group, and the number of carbon atoms is not particularly limited. From the viewpoints of performance and availability, an alkyl group having 1 to 5 carbon atoms is preferable, an alkyl group having 1 to 4 carbon atoms is more preferable, 1 to 3 carbon atoms is particularly preferable, and 1 carbon atom is preferable. Or two is more preferable.
When alkyl groups with too many carbon atoms are bonded, the pinhole of palladium film increases, the deposition rate of palladium decreases, the appearance of palladium deteriorates, or it is difficult to obtain There is.
 また、窒素原子に結合している基がアルキル基(-R)ではなく、水素原子である場合には、前記した本発明の効果が発揮されず、特に、パラジウムめっき液中のパラジウム濃度が高濃度の場合、高温度でめっき処理した場合等に、外観不良を発生させる場合がある。 In addition, when the group bonded to the nitrogen atom is not an alkyl group (—R 1 ) but a hydrogen atom, the above-described effects of the present invention are not exhibited, and in particular, the palladium concentration in the palladium plating solution is When the concentration is high, appearance defects may occur when plating is performed at a high temperature.
 本発明における「特定ピリジニウム化合物」は、パラジウムめっき液中で上記化学構造を有していることが必須であり、パラジウムめっき液中で上記化学構造を有するものに変化したものでもよい。パラジウムめっき液の調液の際に添加する物質の化学構造については特に限定はないが、上記化学構造を有しているものを添加する(用いて調液する)ことが好ましい。 The “specific pyridinium compound” in the present invention is essential to have the above chemical structure in the palladium plating solution, and may be changed to one having the above chemical structure in the palladium plating solution. There is no particular limitation on the chemical structure of the substance to be added at the time of preparing the palladium plating solution, but it is preferable to add (prepare using) one having the above chemical structure.
 本発明のパラジウムめっき液中に含有される「特定ピリジニウム化合物」の陰イオンについては特に限定はないが、具体的には、例えば、硫酸イオン、硝酸イオン、塩素イオン、臭素イオン、ヨウ素イオン等が挙げられる。陰イオンの交換(塩交換)が、パラジウムめっき液中で起こっていてもよく、従って、調液時に配合された(添加された)可溶性パラジウム塩、還元剤、電導塩、緩衝剤塩等の陰イオンと塩交換したものも挙げられる。パラジウムめっき液中の組成として上記のものが本発明の範囲に含まれる。
 ただし、上記陰イオン(硫酸イオン、硝酸イオン、塩素イオン、臭素イオン、ヨウ素イオン等)を有しているものを添加する(を用いて調液する)ことが好ましい。
The anion of the “specific pyridinium compound” contained in the palladium plating solution of the present invention is not particularly limited. Specifically, for example, sulfate ion, nitrate ion, chlorine ion, bromine ion, iodine ion, etc. Can be mentioned. Anion exchange (salt exchange) may occur in the palladium plating solution. Therefore, anions such as soluble palladium salt, reducing agent, conductive salt, buffer salt, etc. added (added) at the time of preparation are used. Examples include those obtained by salt exchange with ions. The above-mentioned compositions in the palladium plating solution are included in the scope of the present invention.
However, it is preferable to add (prepare using) an anion having the above anions (sulfate ion, nitrate ion, chlorine ion, bromine ion, iodine ion, etc.).
 本発明における「特定ピリジニウム化合物」は、2位ないし6位のうちの1個ないし5個の何れかの個数の箇所が、アルキル基、アリール基、カルボキシ基、アルコキシカルボニル基、スルホ基、アルコキシスルホニル基、アミノ基、アルキルアミノ基、ジアルキルアミノ基及びシアノ基からなる群より選ばれた1種又は2種以上の置換基で置換されているものであることが必須である。本発明においては、かかる置換基を「特定置換基」という。
 すなわち、本発明における「特定ピリジニウム化合物」は、6員環であるピリジン環(ピリジニウム環)において、窒素原子は1位であるので、窒素原子以外の環を構成する炭素原子5個に結合した5個の水素のうち、1個ないし5個の何れかの個数が、異なっていてもよい上記の特定置換基で置換されているものである。
In the “specific pyridinium compound” in the present invention, any one of 1 to 5 positions out of the 2nd to 6th positions is an alkyl group, aryl group, carboxy group, alkoxycarbonyl group, sulfo group, alkoxysulfonyl group. It is essential that it is substituted with one or more substituents selected from the group consisting of a group, an amino group, an alkylamino group, a dialkylamino group and a cyano group. In the present invention, such a substituent is referred to as a “specific substituent”.
That is, the “specific pyridinium compound” in the present invention is a 6-membered pyridine ring (pyridinium ring), and since the nitrogen atom is at position 1, it is bonded to 5 carbon atoms constituting the ring other than the nitrogen atom. Any one of 1 to 5 hydrogen atoms is substituted with the above-mentioned specific substituent which may be different.
 特定置換基としてのアルキル基は、直鎖アルキル基又は分岐アルキル基の何れでもよく、更にアルキル基以外の置換基を有していてもよく、炭素数も特に限定はないが、本発明の前記効果をより発揮するために、炭素数1~6個のアルキル基が好ましく、炭素数1~5個のアルキル基がより好ましく、炭素数1~4個のアルキル基、すなわち、メチル基、エチル基、プロピル基又はブチル基が特に好ましい。
 炭素数の多過ぎるアルキル基が結合していると、パラジウム析出速度の低下や、パラジウム皮膜の外観不良を発生する場合がある。
The alkyl group as the specific substituent may be either a linear alkyl group or a branched alkyl group, and may further have a substituent other than an alkyl group, and the number of carbon atoms is not particularly limited, In order to further exert the effect, an alkyl group having 1 to 6 carbon atoms is preferable, an alkyl group having 1 to 5 carbon atoms is more preferable, and an alkyl group having 1 to 4 carbon atoms, that is, a methyl group or an ethyl group A propyl group or a butyl group is particularly preferred.
If an alkyl group having too many carbon atoms is bonded, the palladium deposition rate may be reduced or the appearance of the palladium film may be deteriorated.
 特定置換基としてのアリール基は、アルキル基等の置換基を有していてもよく、特に限定はないが、具体的には、例えば、フェニル基、ナフチル基、トリル基、キシリル基等が挙げられる。 The aryl group as the specific substituent may have a substituent such as an alkyl group and is not particularly limited. Specific examples thereof include a phenyl group, a naphthyl group, a tolyl group, and a xylyl group. It is done.
 特定置換基としてのカルボキシ基は、「-COOH」で表される基であり、「アルコキシカルボニル基」は、「-COOR11」で表される基であり、カルボン酸エステルの残基である。上記式中で、R11は、アルキル基又はアリール基を示し、好ましいものは、前記特定置換基としてのアルキル基やアリール基と同様であり、特に好ましくはメチル基である。 The carboxy group as the specific substituent is a group represented by “—COOH”, and the “alkoxycarbonyl group” is a group represented by “—COOR 11 ” and is a residue of a carboxylic acid ester. In the above formula, R 11 represents an alkyl group or an aryl group, and preferable one is the same as the alkyl group or aryl group as the specific substituent, and particularly preferably a methyl group.
 特定置換基としてのスルホ基は、「-SOH」で表される基であり、スルホン酸基とも言われる。
 特定置換基としてのアルコキシスルホニル基は、以下の一般式(a)で表される基であり、スルホン酸エステル残基である。
The sulfo group as the specific substituent is a group represented by “—SO 3 H” and is also referred to as a sulfonic acid group.
The alkoxysulfonyl group as the specific substituent is a group represented by the following general formula (a) and is a sulfonate residue.
Figure JPOXMLDOC01-appb-C000001
[一般式(a)中、R12は、アルキル基又はアリール基を示す。]
Figure JPOXMLDOC01-appb-C000001
[In General Formula (a), R 12 represents an alkyl group or an aryl group. ]
 一般式(a)中、R12は、アルキル基又はアリール基を示すが、好ましいもの等は、前記特定置換基としてのアルキル基やアリール基と同様であり、更に好ましくはメチル基である。 In general formula (a), R 12 represents an alkyl group or an aryl group, but preferred ones are the same as the alkyl group and aryl group as the specific substituent, and more preferably a methyl group.
 特定置換基としてのアミノ基は、「-NH」で表される基であり、アルキルアミノ基は、「-NHR13」で表される基であり、ジアルキルアミノ基は、「-NR1415」で表される基である。
 上記式中で、R13、R14、R15は、それぞれ異なっていてもよいアルキル基又はアリール基を示し、好ましいものは、前記特定置換基としてのアルキル基やアリール基と同様であり、特に好ましくはメチル基である。
The amino group as the specific substituent is a group represented by “—NH 2 ”, the alkylamino group is a group represented by “—NHR 13 ”, and the dialkylamino group is represented by “—NR 14 R”. 15 ".
In the above formula, R 13 , R 14 , and R 15 each represent an alkyl group or an aryl group that may be different from each other, and preferable ones are the same as the alkyl group and aryl group as the specific substituent, A methyl group is preferred.
 特定置換基としてのシアノ基は、「-CN」で表される基である。 The cyano group as the specific substituent is a group represented by “—CN”.
 上記特定置換基は、本願発明の効果を損なわない範囲において、上記特定置換基に更に置換基を有していてもよいが、前記した本発明の効果を発揮し易く、良好なめっき性能、入手の容易さ等の点から、限定される訳ではないが、上記特定置換基は更に置換基を有していないことが特に好ましい。 The specific substituent may have a substituent in the specific substituent as long as the effects of the invention of the present invention are not impaired. Although it is not necessarily limited from the viewpoints of easiness and the like, it is particularly preferable that the specific substituent does not further have a substituent.
 6員環であるピリジン環(ピリジニウム環)の2位ないし6位には、本願発明の効果を損なわない範囲において、前記特定置換基以外の置換基を有していてもよいが、前記した本発明の効果を発揮し易く、良好なめっき性能、入手の容易さ等の点から、「前記特定置換基以外の置換基」は、限定される訳ではないが有していないことが特に好ましい。 The 6-membered pyridine ring (pyridinium ring) may have a substituent other than the specific substituent at the 2-position to the 6-position, as long as the effects of the present invention are not impaired. From the viewpoints of easily exerting the effects of the invention, good plating performance, availability, etc., the “substituents other than the specific substituents” are not particularly limited, but are particularly preferably not included.
 前記特定置換基の中でも、アルキル基、カルボキシ基、アルコキシスルホニル基及びアミノ基からなる群より選ばれた1種又は2種以上の置換基が置換しているものが、前記した本発明の効果を発揮し易く、良好なめっき性能、入手の容易さ等の点から特に好ましい。 Among the specific substituents, the one or two or more substituents selected from the group consisting of an alkyl group, a carboxy group, an alkoxysulfonyl group, and an amino group are substituted. It is particularly preferable from the viewpoints of easy performance, good plating performance, availability, and the like.
 更に、本発明のパラジウムめっき液は、ピリジニウム環の2位ないし4位の1個ないし3個が、1種又は2種以上の上記特定置換基で置換されたピリジニウム化合物を含有することが、前記効果を更に好適に発揮する点で好ましい。
 すなわち、言い換えれば、ピリジニウム環の2位、3位又は4位のうちの1個ないし3個の何れかの個数の箇所が、1種又は2種以上の上記特定置換基で置換されたピリジニウム化合物を含有することが好ましい。
 より好ましくは、ピリジニウム環の2位ないし4位のうちの1個又は2個(特に好ましくは1個)が、1種又は2種(特に好ましくは1種)の上記特定置換基で置換されたピリジニウム化合物を含有するものである。
 ピリジニウム環には、特定置換基以外の置換基を有していてもよいが、有していないことが好ましい。
Furthermore, the palladium plating solution of the present invention contains a pyridinium compound in which one to three of the 2-position to 4-position of the pyridinium ring are substituted with one or more of the above-mentioned specific substituents. It is preferable in that the effect is more suitably exhibited.
That is, in other words, a pyridinium compound in which any one of the 2-position, 3-position, or 4-position of the pyridinium ring is substituted with one or more specific substituents. It is preferable to contain.
More preferably, one or two (particularly preferably one) of the 2-position to the 4-position of the pyridinium ring is substituted with one or two (particularly preferably one) of the specific substituents. It contains a pyridinium compound.
The pyridinium ring may have a substituent other than the specific substituent, but preferably has no substituent.
 特に好ましいピリジニウム化合物は、下記一般式(1)で表されるものである。 Particularly preferred pyridinium compounds are those represented by the following general formula (1).
Figure JPOXMLDOC01-appb-C000002
[一般式(1)中、Rはアルキル基を示し、R、R及びRは、互いに異なっていてもよい、水素原子、アルキル基、アリール基、カルボキシ基、アルコキシカルボニル基、スルホ基、アルコキシスルホニル基、アミノ基、アルキルアミノ基、ジアルキルアミノ基又はシアノ基を示し、ただし、R、R及びRの全てが水素原子である場合を除く。]
Figure JPOXMLDOC01-appb-C000002
[In General Formula (1), R 1 represents an alkyl group, and R 2 , R 3, and R 4 may be different from each other, hydrogen atom, alkyl group, aryl group, carboxy group, alkoxycarbonyl group, sulfo group. Group, alkoxysulfonyl group, amino group, alkylamino group, dialkylamino group or cyano group, except that all of R 2 , R 3 and R 4 are hydrogen atoms. ]
 窒素原子に結合したアルキル基(R)は、直鎖アルキル基又は分岐アルキル基の何れでもよく、炭素数も特に限定はないが、炭素数1~6個のアルキル基が好ましく、炭素数1~5個のアルキル基がより好ましく、炭素数1~4個のアルキル基、すなわち、メチル基、エチル基、プロピル基又はブチル基が特に好ましい。
 炭素数の多過ぎるアルキル基が結合していると、前記した本発明の効果が発揮されず、パラジウム皮膜のピンホールが増加したり、パラジウムの析出速度が低下したり、パラジウムの外観不良が発生したり、入手が困難であったりする場合がある。
 また、窒素原子に結合している基がアルキル基ではなく、水素原子である場合には、前記した本発明の効果が発揮されず、特に、パラジウムめっき液中のパラジウム濃度が高濃度の場合、高温度でめっき処理した場合等に、外観不良を発生させる場合がある。
The alkyl group (R 1 ) bonded to the nitrogen atom may be either a linear alkyl group or a branched alkyl group, and the carbon number is not particularly limited, but an alkyl group having 1 to 6 carbon atoms is preferable, and the carbon number is 1 More preferred are ˜5 alkyl groups, and particularly preferred are alkyl groups having 1 to 4 carbon atoms, ie, methyl group, ethyl group, propyl group or butyl group.
If an alkyl group having too many carbon atoms is bonded, the effect of the present invention described above will not be exhibited, the pinhole of the palladium film will increase, the deposition rate of palladium will decrease, and the appearance of palladium will be poor. Or it may be difficult to obtain.
In addition, when the group bonded to the nitrogen atom is not an alkyl group but a hydrogen atom, the effect of the present invention described above is not exhibited, particularly when the palladium concentration in the palladium plating solution is high, An appearance defect may occur when plating is performed at a high temperature.
 R、R及びRは、互いに異なっていてもよい、水素原子、アルキル基、アリール基、カルボキシ基、アルコキシカルボニル基、スルホ基、アルコキシスルホニル基、アミノ基、アルキルアミノ基、ジアルキルアミノ基又はシアノ基を示し、ただし、R、R及びRの全てが水素原子である場合は除かれる。
 R、R及びRとしては、「より好ましい」、「特に好ましい」等として前記した「特定置換基」が、前記効果を更に好適に発揮する点でより(特に)好ましい。
R 2 , R 3 and R 4 may be different from each other, hydrogen atom, alkyl group, aryl group, carboxy group, alkoxycarbonyl group, sulfo group, alkoxysulfonyl group, amino group, alkylamino group, dialkylamino group Or a cyano group, except that R 2 , R 3 and R 4 are all hydrogen atoms.
As R 2 , R 3 and R 4 , the “specific substituent” described above as “more preferable”, “particularly preferable” and the like is more (particularly) more preferable in that the above-described effects are more suitably exhibited.
 一般式(1)の陰イオン(対イオン)については特に限定はないが、具体的には、例えば、好ましいものとして、硫酸イオン、硝酸イオン、塩素イオン、臭素イオン、ヨウ素イオン等、前記したものが挙げられる。
 一般式(1)の陰イオンは、本発明のパラジウムめっき液中に存在する形態を特定するものであり、調液時に配合された(添加された)可溶性パラジウム塩、還元剤、電導塩、緩衝剤塩等の陰イオンと塩交換したものも好ましい。
 ただ、本発明のパラジウムめっき液の調液の際に、溶解(配合、添加)させる原料の陰イオン(対イオン)として、硫酸イオン、硝酸イオン、塩素イオン、臭素イオン、ヨウ素イオン等が好ましい。
 上記の特定ピリジニウム化合物についての記載は、本発明のパラジウムめっき液中に存在する形態を特定するものである。ただし、本発明のパラジウムめっき液の調液の際に、溶解させる原料として、上記の特定ピリジニウム化合物を用いることが好ましい。
The anion (counter ion) of the general formula (1) is not particularly limited, but specifically, for example, preferable examples include those described above such as sulfate ion, nitrate ion, chlorine ion, bromine ion, iodine ion and the like. Is mentioned.
The anion of the general formula (1) specifies the form present in the palladium plating solution of the present invention, and is added (added) to the soluble palladium salt, reducing agent, conductive salt, buffer, which is blended at the time of preparation. Those obtained by salt exchange with anions such as agent salts are also preferred.
However, sulfate ions, nitrate ions, chlorine ions, bromine ions, iodine ions and the like are preferable as the anions (counter ions) of the raw material to be dissolved (formulated and added) in the preparation of the palladium plating solution of the present invention.
The above description of the specific pyridinium compound specifies the form present in the palladium plating solution of the present invention. However, when preparing the palladium plating solution of the present invention, it is preferable to use the specific pyridinium compound as a raw material to be dissolved.
 特定ピリジニウム化合物を含有することにより、ピンホールのないパラジウム皮膜を実現できる。また、特定ピリジニウム化合物を含有することにより、従来のパラジウム皮膜よりも飛躍的に優れた高耐熱性を有することから、従来のパラジウム皮膜の膜厚を大幅に薄膜化可能となり、また、パラジウム皮膜上に形成する金めっき皮膜を大幅に薄膜化可能となり、大幅なコストダウンが実現される。 By including a specific pyridinium compound, a palladium film without a pinhole can be realized. In addition, by containing a specific pyridinium compound, it has high heat resistance that is dramatically superior to that of the conventional palladium film, so that the film thickness of the conventional palladium film can be greatly reduced. The gold plating film to be formed can be greatly reduced in thickness, and the cost can be greatly reduced.
 「ピンホール試験」において、「膜厚0.03μmのパラジウム皮膜」でピンホールのないパラジウム皮膜を実現できる本発明のパラジウムめっき液を用いると、それより薄いパラジウム皮膜であってもピンホールの相対的に少ないものが得られ、それより厚いパラジウム皮膜であれば、更にピンホールのないものが得られて更に信頼性が増す。
 また、金皮膜は一般にピンホールができ難く、パラジウム皮膜は一般にピンホールができ易い。従って、ピンホールのでき難い本発明のパラジウムめっき液を用いると、金皮膜でパラジウム皮膜のピンホールをカバーする必要がなくなり、金皮膜の膜厚を下げることができ、コストダウンが可能となる。
In the “pinhole test”, when the palladium plating solution of the present invention capable of realizing a palladium film having no pinhole with “a 0.03 μm-thickness palladium film” is used, even if the palladium film is thinner than that, If the palladium film is thicker than that, a pinhole-free film is obtained and the reliability is further increased.
In addition, gold films are generally difficult to make pinholes, and palladium films are generally easy to make pinholes. Therefore, when the palladium plating solution of the present invention which is difficult to form pinholes is used, it is not necessary to cover the pinholes of the palladium film with a gold film, the film thickness of the gold film can be reduced, and the cost can be reduced.
 本発明において、「ピンホール試験」は後述するが、「試験開始」から「試験開始後5分」までの全ての間、通電電流が小さいパラジウム皮膜を与えるパラジウムめっき液を優れたものとし、その間、常に通電電流が100μA以下であるような皮膜物性を与えるパラジウムめっき液を優れたパラジウムめっき液とする。 In the present invention, the “pinhole test” will be described later, but during the period from “test start” to “5 minutes after the start of test”, a palladium plating solution that gives a palladium film with a small energization current is considered to be excellent. An excellent palladium plating solution is a palladium plating solution that always provides film properties such that the energization current is 100 μA or less.
 本発明において、「耐熱性」は、実施例記載の方法で評価し、そのように評価したものとして定義する。
 「耐熱性」は、電子部品の接点部材に必須の性能である。電子部品の接点部材は、半田接合やワイヤーボンディングで他部材と接合する必要があり、その接合工程には、必ず100℃から300℃の加熱工程が含まれ、また、この加熱工程も1回ではなく複数回存在することが多い。
 この加熱工程により、銅、銅合金、ニッケル、ニッケル合金等の金属は酸化され、半田接合不良や、接触抵抗の上昇、ワイヤーボンディング接合不良といった不良発生の原因となる。従って、この銅、ニッケル等の酸化を防止する目的で、金めっきやパラジウムめっき等の貴金属めっきを施し表面保護層を形成することが重要である。
In the present invention, "heat resistance" is defined as the value evaluated by the method described in the examples and evaluated as such.
“Heat resistance” is a performance essential for a contact member of an electronic component. The contact member of an electronic component must be joined to another member by soldering or wire bonding, and the joining process always includes a heating process of 100 ° C. to 300 ° C. This heating process is also performed once. It often exists multiple times.
This heating process oxidizes metals such as copper, copper alloy, nickel, nickel alloy, etc., causing defects such as poor solder joints, increased contact resistance, and poor wire bonding joints. Therefore, it is important to form a surface protective layer by performing noble metal plating such as gold plating or palladium plating for the purpose of preventing the oxidation of copper, nickel and the like.
 しかしながら、金めっき皮膜やパラジウムめっき皮膜等の貴金属めっき皮膜を形成していたとしても、貴金属めっき皮膜にピンホールが存在すると、上記加熱工程により貴金属めっき皮膜の下地である銅、ニッケル等が、該ピンホールから最表面に拡散し、酸化され貴金属めっき皮膜を施した効果がなくなってしまうことがある。
 そのため、貴金属めっき皮膜におけるピンホールの存在は、電子部品の接点部材に対して、その耐熱性を有するか否かの指標となる。金めっき皮膜やパラジウムめっき皮膜等の貴金属めっき皮膜のピンホールが少ないということは、優れた「耐熱性」を有しているということを表している。
However, even if a noble metal plating film such as a gold plating film or a palladium plating film is formed, if there is a pinhole in the noble metal plating film, copper, nickel, etc., which are the base of the noble metal plating film, are not treated by the heating process. The effect of diffusing from the pinhole to the outermost surface and being oxidized and precious metal plating film may be lost.
Therefore, the presence of pinholes in the noble metal plating film is an indicator of whether or not the contact member of the electronic component has heat resistance. A small number of pinholes in a noble metal plating film such as a gold plating film or a palladium plating film indicates that it has excellent “heat resistance”.
 上記の特定ピリジニウム化合物の好ましい具体例としては、例えば、
 1-メチル-2-メチルピリジニウム、1-メチル-2-エチルピリジニウム、1-メチル-2-ブチルピリジニウム、1-メチル-2-スルホピリジニウム、1-メチル-2-メトキシスルホニルピリジニウム、1-メチル-2-アミノピリジニウム、1-メチル-2-カルボキシピリジニウム、1-メチル-2-メトキシカルボニルピリジニウム、1-メチル-2-フェニルピリジニウム、1-メチル-2-シアノピリジニウム等の2位置換のメチルピリジニウム;
 1-エチル-2-メチルピリジニウム、1-エチル-2-エチルピリジニウム、1-エチル-2-ブチルピリジニウム、1-エチル-2-スルホピリジニウム、1-エチル-2-メトキシスルホニルピリジニウム、1-エチル-2-アミノピリジニウム、1-エチル-2-カルボキシピリジニウム、1-エチル-2-メトキシカルボニルピリジニウム、1-エチル-2-フェニルピリジニウム、1-エチル-2-シアノピリジニウム等の2位置換のエチルピリジニウム;
 1-プロピル-2-メチルピリジニウム、1-プロピル-2-エチルピリジニウム、1-プロピル-2-ブチルピリジニウム、1-プロピル-2-スルホピリジニウム、1-プロピル-2-メトキシスルホニルピリジニウム、1-プロピル-2-アミノピリジニウム、1-プロピル-2-カルボキシピリジニウム、1-プロピル-2-メトキシカルボニルピリジニウム、1-プロピル-2-フェニルピリジニウム、1-プロピル-2-シアノピリジニウム等の2位置換のプロピルピリジニウム;
 1-ブチル-2-メチルピリジニウム、1-ブチル-2-エチルピリジニウム、1-ブチル-2-ブチルピリジニウム、1-ブチル-2-スルホピリジニウム、1-ブチル-2-メトキシスルホニルピリジニウム、1-ブチル-2-アミノピリジニウム、1-ブチル-2-カルボキシピリジニウム、1-ブチル-2-メトキシカルボニルピリジニウム、1-ブチル-2-フェニルピリジニウム、1-ブチル-2-シアノピリジニウム等の2位置換のブチルピリジニウム;
 1-メチル-3-メチルピリジニウム、1-メチル-3-エチルピリジニウム、1-メチル-3-ブチルピリジニウム、1-メチル-3-スルホピリジニウム、1-メチル-3-メトキシスルホニルピリジニウム、1-メチル-3-アミノピリジニウム、1-メチル-3-カルボキシピリジニウム、1-メチル-3-メトキシカルボニルピリジニウム、1-メチル-3-フェニルピリジニウム、1-メチル-3-シアノピリジニウム等の3位置換のメチルピリジニウム;
 1-エチル-3-メチルピリジニウム、1-エチル-3-エチルピリジニウム、1-エチル-3-ブチルピリジニウム、1-エチル-3-スルホピリジニウム、1-エチル-3-メトキシスルホニルピリジニウム、1-エチル-3-アミノピリジニウム、1-エチル-3-カルボキシピリジニウム、1-エチル-3-メトキシカルボニルピリジニウム、1-エチル-3-フェニルピリジニウム、1-エチル-3-シアノピリジニウム等の3位置換のエチルピリジニウム;
 1-プロピル-3-メチルピリジニウム、1-プロピル-3-エチルピリジニウム、1-プロピル-3-ブチルピリジニウム、1-プロピル-3-スルホピリジニウム、1-プロピル-3-メトキシスルホニルピリジニウム、1-プロピル-3-アミノピリジニウム、1-プロピル-3-カルボキシピリジニウム、1-プロピル-3-メトキシカルボニルピリジニウム、1-プロピル-3-フェニルピリジニウム、1-プロピル-3-シアノピリジニウム等の3位置換のプロピルピリジニウム;
 1-ブチル-3-メチルピリジニウム、1-ブチル-3-エチルピリジニウム、1-ブチル-3-ブチルピリジニウム、1-ブチル-3-スルホピリジニウム、1-ブチル-3-メトキシスルホニルピリジニウム、1-ブチル-3-アミノピリジニウム、1-ブチル-3-カルボキシピリジニウム、1-ブチル-3-メトキシカルボニルピリジニウム、1-ブチル-3-フェニルピリジニウム、1-ブチル-3-シアノピリジニウム等の3位置換のブチルピリジニウム;
 1-メチル-4-メチルピリジニウム、1-メチル-4-エチルピリジニウム、1-メチル-4-ブチルピリジニウム、1-メチル-4-スルホピリジニウム、1-メチル-4-メトキシスルホニルピリジニウム、1-メチル-4-アミノピリジニウム、1-メチル-4-カルボキシピリジニウム、1-メチル-4-メトキシカルボニルピリジニウム、1-メチル-4-フェニルピリジニウム、1-メチル-4-シアノピリジニウム等の4位置換のメチルピリジニウム;
 1-エチル-4-メチルピリジニウム、1-エチル-4-エチルピリジニウム、1-エチル-4-ブチルピリジニウム、1-エチル-4-スルホピリジニウム、1-エチル-4-メトキシスルホニルピリジニウム、1-エチル-4-アミノピリジニウム、1-エチル-4-カルボキシピリジニウム、1-エチル-4-メトキシカルボニルピリジニウム、1-エチル-4-フェニルピリジニウム、1-エチル-4-シアノピリジニウム等の4位置換のエチルピリジニウム;
 1-プロピル-4-メチルピリジニウム、1-プロピル-4-エチルピリジニウム、1-プロピル-4-ブチルピリジニウム、1-プロピル-4-スルホピリジニウム、1-プロピル-4-メトキシスルホニルピリジニウム、1-プロピル-4-アミノピリジニウム、1-プロピル-4-カルボキシピリジニウム、1-プロピル-4-メトキシカルボニルピリジニウム、1-プロピル-4-フェニルピリジニウム、1-プロピル-4-シアノピリジニウム等の4位置換のプロピルピリジニウム;
 1-ブチル-4-メチルピリジニウム、1-ブチル-4-エチルピリジニウム、1-ブチル-4-ブチルピリジニウム、1-ブチル-4-スルホピリジニウム、1-ブチル-4-メトキシスルホニルピリジニウム、1-ブチル-4-アミノピリジニウム、1-ブチル-4-カルボキシピリジニウム、1-ブチル-4-メトキシカルボニルピリジニウム、1-ブチル-4-フェニルピリジニウム、1-ブチル-4-シアノピリジニウム等の4位置換のブチルピリジニウム;
等が挙げられる。
As preferable specific examples of the specific pyridinium compound, for example,
1-methyl-2-methylpyridinium, 1-methyl-2-ethylpyridinium, 1-methyl-2-butylpyridinium, 1-methyl-2-sulfopyridinium, 1-methyl-2-methoxysulfonylpyridinium, 1-methyl- 2-position-substituted methylpyridinium such as 2-aminopyridinium, 1-methyl-2-carboxypyridinium, 1-methyl-2-methoxycarbonylpyridinium, 1-methyl-2-phenylpyridinium, 1-methyl-2-cyanopyridinium;
1-ethyl-2-methylpyridinium, 1-ethyl-2-ethylpyridinium, 1-ethyl-2-butylpyridinium, 1-ethyl-2-sulfopyridinium, 1-ethyl-2-methoxysulfonylpyridinium, 1-ethyl- 2-substituted pyridinium such as 2-aminopyridinium, 1-ethyl-2-carboxypyridinium, 1-ethyl-2-methoxycarbonylpyridinium, 1-ethyl-2-phenylpyridinium, 1-ethyl-2-cyanopyridinium;
1-propyl-2-methylpyridinium, 1-propyl-2-ethylpyridinium, 1-propyl-2-butylpyridinium, 1-propyl-2-sulfopyridinium, 1-propyl-2-methoxysulfonylpyridinium, 1-propyl- 2-substituted propylpyridinium such as 2-aminopyridinium, 1-propyl-2-carboxypyridinium, 1-propyl-2-methoxycarbonylpyridinium, 1-propyl-2-phenylpyridinium, 1-propyl-2-cyanopyridinium;
1-butyl-2-methylpyridinium, 1-butyl-2-ethylpyridinium, 1-butyl-2-butylpyridinium, 1-butyl-2-sulfopyridinium, 1-butyl-2-methoxysulfonylpyridinium, 1-butyl- 2-position-substituted butylpyridinium such as 2-aminopyridinium, 1-butyl-2-carboxypyridinium, 1-butyl-2-methoxycarbonylpyridinium, 1-butyl-2-phenylpyridinium, 1-butyl-2-cyanopyridinium;
1-methyl-3-methylpyridinium, 1-methyl-3-ethylpyridinium, 1-methyl-3-butylpyridinium, 1-methyl-3-sulfopyridinium, 1-methyl-3-methoxysulfonylpyridinium, 1-methyl- 3-substituted pyridinium such as 3-aminopyridinium, 1-methyl-3-carboxypyridinium, 1-methyl-3-methoxycarbonylpyridinium, 1-methyl-3-phenylpyridinium, 1-methyl-3-cyanopyridinium;
1-ethyl-3-methylpyridinium, 1-ethyl-3-ethylpyridinium, 1-ethyl-3-butylpyridinium, 1-ethyl-3-sulfopyridinium, 1-ethyl-3-methoxysulfonylpyridinium, 1-ethyl- 3-position-substituted ethylpyridinium such as 3-aminopyridinium, 1-ethyl-3-carboxypyridinium, 1-ethyl-3-methoxycarbonylpyridinium, 1-ethyl-3-phenylpyridinium, 1-ethyl-3-cyanopyridinium;
1-propyl-3-methylpyridinium, 1-propyl-3-ethylpyridinium, 1-propyl-3-butylpyridinium, 1-propyl-3-sulfopyridinium, 1-propyl-3-methoxysulfonylpyridinium, 1-propyl- 3-substituted propylpyridinium such as 3-aminopyridinium, 1-propyl-3-carboxypyridinium, 1-propyl-3-methoxycarbonylpyridinium, 1-propyl-3-phenylpyridinium, 1-propyl-3-cyanopyridinium;
1-butyl-3-methylpyridinium, 1-butyl-3-ethylpyridinium, 1-butyl-3-butylpyridinium, 1-butyl-3-sulfopyridinium, 1-butyl-3-methoxysulfonylpyridinium, 1-butyl- 3-substituted butylpyridinium such as 3-aminopyridinium, 1-butyl-3-carboxypyridinium, 1-butyl-3-methoxycarbonylpyridinium, 1-butyl-3-phenylpyridinium, 1-butyl-3-cyanopyridinium;
1-methyl-4-methylpyridinium, 1-methyl-4-ethylpyridinium, 1-methyl-4-butylpyridinium, 1-methyl-4-sulfopyridinium, 1-methyl-4-methoxysulfonylpyridinium, 1-methyl- 4-methylpyridinium substituted in 4-position such as 4-aminopyridinium, 1-methyl-4-carboxypyridinium, 1-methyl-4-methoxycarbonylpyridinium, 1-methyl-4-phenylpyridinium, 1-methyl-4-cyanopyridinium;
1-ethyl-4-methylpyridinium, 1-ethyl-4-ethylpyridinium, 1-ethyl-4-butylpyridinium, 1-ethyl-4-sulfopyridinium, 1-ethyl-4-methoxysulfonylpyridinium, 1-ethyl- 4-substituted pyridinium such as 4-aminopyridinium, 1-ethyl-4-carboxypyridinium, 1-ethyl-4-methoxycarbonylpyridinium, 1-ethyl-4-phenylpyridinium, 1-ethyl-4-cyanopyridinium;
1-propyl-4-methylpyridinium, 1-propyl-4-ethylpyridinium, 1-propyl-4-butylpyridinium, 1-propyl-4-sulfopyridinium, 1-propyl-4-methoxysulfonylpyridinium, 1-propyl- 4-position-substituted propylpyridinium such as 4-aminopyridinium, 1-propyl-4-carboxypyridinium, 1-propyl-4-methoxycarbonylpyridinium, 1-propyl-4-phenylpyridinium, 1-propyl-4-cyanopyridinium;
1-butyl-4-methylpyridinium, 1-butyl-4-ethylpyridinium, 1-butyl-4-butylpyridinium, 1-butyl-4-sulfopyridinium, 1-butyl-4-methoxysulfonylpyridinium, 1-butyl- 4-position-substituted butylpyridinium such as 4-aminopyridinium, 1-butyl-4-carboxypyridinium, 1-butyl-4-methoxycarbonylpyridinium, 1-butyl-4-phenylpyridinium, 1-butyl-4-cyanopyridinium;
Etc.
 これらの特定ピリジニウム化合物は、前記した本発明の効果を発揮し易く、更に、良好なパラジウムめっき性能、水への溶解のし易さ、入手のし易さ、低コスト等の観点からも好ましい。 These specific pyridinium compounds are preferable from the viewpoints of easily exhibiting the effects of the present invention as described above, and further, favorable palladium plating performance, ease of dissolution in water, availability, and low cost.
 それらの中でも、上記点等から、特に好ましい具体例としては、
 1-メチル-2-メチルピリジニウム、1-メチル-2-エチルピリジニウム、1-メチル-2-ブチルピリジニウム、1-メチル-2-スルホピリジニウム、1-メチル-2-メトキシスルホニルピリジニウム、1-メチル-2-アミノピリジニウム、1-メチル-2-カルボキシピリジニウム等の2位置換のメチルピリジニウム;
 1-エチル-2-メチルピリジニウム、1-エチル-2-エチルピリジニウム、1-エチル-2-ブチルピリジニウム、1-エチル-2-スルホピリジニウム、1-エチル-2-メトキシスルホニルピリジニウム、1-エチル-2-アミノピリジニウム、1-エチル-2-カルボキシルピリジニウム等の2位置換のエチルピリジニウム;
 1-メチル-3-メチルピリジニウム、1-メチル-3-エチルピリジニウム、1-メチル-3-ブチルピリジニウム、1-メチル-3-スルホピリジニウム、1-メチル-3-メトキシスルホニルピリジニウム、1-メチル-3-アミノピリジニウム、1-メチル-3-カルボキシルピリジニウム等の3位置換のメチルピリジニウム;
 1-エチル-3-メチルピリジニウム、1-エチル-3-エチルピリジニウム、1-エチル-3-ブチルピリジニウム、1-エチル-3-スルホピリジニウム、1-エチル-3-メトキシスルホニルピリジニウム、1-エチル-3-アミノピリジニウム、1-エチル-3-カルボキシルピリジニウム等の3位置換のエチルピリジニウム;
 1-メチル-4-メチルピリジニウム、1-メチル-4-エチルピリジニウム、1-メチル-4-ブチルピリジニウム、1-メチル-4-スルホピリジニウム、1-メチル-4-メトキシスルホニルピリジニウム、1-メチル-4-アミノピリジニウム、1-メチル-4-カルボキシルピリジニウム等の4位置換のメチルピリジニウム;
 1-エチル-4-メチルピリジニウム、1-エチル-4-エチルピリジニウム、1-エチル-4-ブチルピリジニウム、1-エチル-4-スルホピリジニウム、1-エチル-4-メトキシスルホニルピリジニウム、1-エチル-4-アミノピリジニウム、1-エチル-4-カルボキシルピリジニウム等の4位置換のエチルピリジニウム;
等が挙げられる。
Among these, from the above points, as a particularly preferred specific example,
1-methyl-2-methylpyridinium, 1-methyl-2-ethylpyridinium, 1-methyl-2-butylpyridinium, 1-methyl-2-sulfopyridinium, 1-methyl-2-methoxysulfonylpyridinium, 1-methyl- 2-methylpyridinium substituted at 2-position such as 2-aminopyridinium, 1-methyl-2-carboxypyridinium;
1-ethyl-2-methylpyridinium, 1-ethyl-2-ethylpyridinium, 1-ethyl-2-butylpyridinium, 1-ethyl-2-sulfopyridinium, 1-ethyl-2-methoxysulfonylpyridinium, 1-ethyl- 2-position-substituted ethylpyridinium such as 2-aminopyridinium, 1-ethyl-2-carboxylpyridinium;
1-methyl-3-methylpyridinium, 1-methyl-3-ethylpyridinium, 1-methyl-3-butylpyridinium, 1-methyl-3-sulfopyridinium, 1-methyl-3-methoxysulfonylpyridinium, 1-methyl- 3-positioned methylpyridinium such as 3-aminopyridinium, 1-methyl-3-carboxylpyridinium;
1-ethyl-3-methylpyridinium, 1-ethyl-3-ethylpyridinium, 1-ethyl-3-butylpyridinium, 1-ethyl-3-sulfopyridinium, 1-ethyl-3-methoxysulfonylpyridinium, 1-ethyl- 3-substituted pyridinium such as 3-aminopyridinium, 1-ethyl-3-carboxylpyridinium;
1-methyl-4-methylpyridinium, 1-methyl-4-ethylpyridinium, 1-methyl-4-butylpyridinium, 1-methyl-4-sulfopyridinium, 1-methyl-4-methoxysulfonylpyridinium, 1-methyl- 4-methylpyridinium substituted at the 4-position, such as 4-aminopyridinium, 1-methyl-4-carboxylpyridinium;
1-ethyl-4-methylpyridinium, 1-ethyl-4-ethylpyridinium, 1-ethyl-4-butylpyridinium, 1-ethyl-4-sulfopyridinium, 1-ethyl-4-methoxysulfonylpyridinium, 1-ethyl- 4-substituted pyridinium such as 4-aminopyridinium and 1-ethyl-4-carboxylpyridinium;
Etc.
 これらの特定ピリジニウム化合物は、前記した本発明の効果をより発揮し易く、更に、良好なパラジウムめっき性能、水への溶解のし易さ、入手のし易さ、低コスト等の観点から特に好ましいものとして挙げられる。 These specific pyridinium compounds are particularly preferable from the viewpoints of easily exhibiting the effects of the present invention described above, and further, from the viewpoint of good palladium plating performance, ease of dissolution in water, availability, low cost, and the like. It is mentioned as a thing.
 本発明において、特定ピリジニウム化合物の含有量については特に限定はないが、パラジウムめっき液全体に対して、質量で、好ましくは1ppm~50000ppm、より好ましくは10ppm~30000ppm、特に好ましくは20ppm~10000ppm、更に好ましくは、50ppm~5000ppm、最も好ましくは、100ppm~3000ppmである。なお、上記の特定ピリジニウム化合物を2種以上含有するときは、上記数値はそれらの合計含有量を示す。 In the present invention, the content of the specific pyridinium compound is not particularly limited, but is preferably 1 ppm to 50000 ppm, more preferably 10 ppm to 30000 ppm, and particularly preferably 20 ppm to 10000 ppm by mass with respect to the total palladium plating solution. Preferably, it is 50 ppm to 5000 ppm, and most preferably 100 ppm to 3000 ppm. In addition, when 2 or more types of said specific pyridinium compounds are contained, the said numerical value shows those total content.
 パラジウムめっき液中の特定ピリジニウム化合物の含有量が少な過ぎると、前記した本発明の効果を発揮し難くなり、パラジウム皮膜に生成するピンホールの数(密度)が増加したり、パラジウム皮膜の外観不良を起こしたりする場合がある。一方、含有量が多過ぎると本発明の上記効果の更なる増加は期待できず不経済となる場合がある。 If the content of the specific pyridinium compound in the palladium plating solution is too small, it becomes difficult to exert the effect of the present invention described above, the number of pinholes (density) generated in the palladium film increases, and the appearance of the palladium film is poor. May occur. On the other hand, when there is too much content, the further increase of the said effect of this invention cannot be anticipated, and it may become uneconomical.
 上記の特定ピリジニウム化合物についての記載は、本発明のパラジウムめっき液中に存在する形態を特定するものであるが、本発明のパラジウムめっき液の調液の際に、溶解させる原料として、上記の特定ピリジニウム化合物を用いることが好ましい。 The above description about the specific pyridinium compound specifies the form existing in the palladium plating solution of the present invention, but the above-mentioned specific as a raw material to be dissolved in the preparation of the palladium plating solution of the present invention. It is preferable to use a pyridinium compound.
<可溶性パラジウム塩>
 本発明のパラジウムめっき液は、可溶性パラジウム塩を含有することが必須である。該可溶性パラジウム塩は、本発明のパラジウムめっき液のパラジウム源として用いられる。可溶性パラジウム塩は、1種の使用に限定されず2種以上を併用することができる。「可溶性」の意味は、水に可溶という意味である。
<Soluble palladium salt>
It is essential for the palladium plating solution of the present invention to contain a soluble palladium salt. The soluble palladium salt is used as a palladium source for the palladium plating solution of the present invention. The soluble palladium salt is not limited to one type of use, and two or more types can be used in combination. The meaning of “soluble” means soluble in water.
 該可溶性パラジウム塩としては、特に限定がなく公知のものが使用できるが、具体的には、例えば、塩化パラジウム、硫酸パラジウム、酢酸パラジウム、硝酸パラジウム、酸化パラジウム、ジクロロテトラアンミンパラジウム、ジニトロジアンミンパラジウム、ジクロロジエチレンジアミンパラジウム、テトラキス(トリフェニルホスフィン)パラジウム、ジクロロビス(トリフェニルホスフィン)パラジウム及び/又はビス(アセチルアセトナト)パラジウムが、水への溶解性、入手の容易さ等から好ましいものとして挙げられる。 The soluble palladium salt is not particularly limited and known ones can be used. Specific examples include palladium chloride, palladium sulfate, palladium acetate, palladium nitrate, palladium oxide, dichlorotetraammine palladium, dinitrodiammine palladium, dichloromethane. Diethylenediamine palladium, tetrakis (triphenylphosphine) palladium, dichlorobis (triphenylphosphine) palladium and / or bis (acetylacetonato) palladium are preferable because of their solubility in water and availability.
 その中でも、水溶液で供給されることによって、パラジウム塩補充の際に手間が掛からない点等から、ジクロロテトラアンミンパラジウム又はジニトロジアンミンパラジウムがより好ましい。更に、同様の観点から、ジクロロテトラアンミンパラジウムが特に好ましい。 Among them, dichlorotetraamminepalladium or dinitrodiamminepalladium is more preferable from the viewpoint that it is not time-consuming to replenish the palladium salt by being supplied as an aqueous solution. Further, from the same viewpoint, dichlorotetraammine palladium is particularly preferable.
 本発明のパラジウムめっき液中の該パラジウム塩の含有量は特に限定はなく、パラジウムめっき液全体に対して、金属パラジウムとして、通常0.001g/L~50g/L、好ましくは0.005g/L~30g/L、特に好ましくは0.01g/L~20g/Lである。
 パラジウムめっき液中の可溶性パラジウム塩の含有量が少な過ぎると、正常の均一な色調のパラジウム皮膜の形成が困難になる場合がある。すなわち、パラジウム皮膜の色や付き回りを目視で観察したときにパラジウムの析出異常が認められる場合がある。
 一方、パラジウムめっき液中のパラジウム塩の含有量が多過ぎる場合は、パラジウムめっき液の性能としては特に問題はないが、パラジウム塩は非常に高価であり、パラジウムめっき液中に含有した状態で保存するのは不経済となる場合がある。
The content of the palladium salt in the palladium plating solution of the present invention is not particularly limited, and is generally 0.001 g / L to 50 g / L, preferably 0.005 g / L as metal palladium with respect to the whole palladium plating solution. -30 g / L, particularly preferably 0.01 g / L to 20 g / L.
If the content of the soluble palladium salt in the palladium plating solution is too small, it may be difficult to form a palladium film having a normal and uniform color tone. That is, there is a case where an abnormal precipitation of palladium is observed when the color and attached color of the palladium film are visually observed.
On the other hand, if the palladium salt content in the palladium plating solution is too high, there is no particular problem with the performance of the palladium plating solution, but the palladium salt is very expensive and is stored in the palladium plating solution. Doing so can be uneconomical.
 上記のパラジウム塩についての記載は、本発明のパラジウムめっき液中に存在する形態を特定するものであるが、本発明のパラジウムめっき液の調液の際に溶解させる原料として、上記のパラジウム塩を用いることが好ましい。 The above description about the palladium salt specifies the form present in the palladium plating solution of the present invention. As a raw material to be dissolved in the preparation of the palladium plating solution of the present invention, the above palladium salt is used. It is preferable to use it.
<還元剤>
 本発明のパラジウムめっき液は、可溶性パラジウム塩、特定ピリジニウム化合物に加えて、更に還元剤が含有されていることが好ましい。該還元剤としては、次亜リン酸、次亜リン酸塩、亜リン酸、亜リン酸塩、ギ酸、ギ酸塩、ホルムアルデヒド等が特に好ましい。
 上記の還元剤は、1種の使用に限定されず2種以上を併用することができる。
<Reducing agent>
The palladium plating solution of the present invention preferably further contains a reducing agent in addition to the soluble palladium salt and the specific pyridinium compound. As the reducing agent, hypophosphorous acid, hypophosphite, phosphorous acid, phosphite, formic acid, formate, formaldehyde and the like are particularly preferable.
Said reducing agent is not limited to 1 type of use, It can use 2 or more types together.
 上記還元剤としては、具体的には、例えば、次亜リン酸、次亜リン酸ナトリウム、次亜リン酸カリウム、次亜リン酸アンモニウム、亜リン酸、亜リン酸ナトリウム、亜リン酸カリウム、亜リン酸アンモニウム、ギ酸、ギ酸ナトリウム、ギ酸カリウム、ギ酸アンモニウム、ホルムアルデヒド等が、良好なパラジウムめっき性能、水への溶解のし易さ、薬品としての取り扱いの容易さ、入手の容易さ、低コスト等の観点から、好ましいものとして挙げられる。 Specific examples of the reducing agent include hypophosphorous acid, sodium hypophosphite, potassium hypophosphite, ammonium hypophosphite, phosphorous acid, sodium phosphite, potassium phosphite, Ammonium phosphite, formic acid, sodium formate, potassium formate, ammonium formate, formaldehyde, etc. have good palladium plating performance, ease of dissolution in water, easy handling as chemicals, easy availability, low cost From the viewpoint of the above, it is preferable.
 本発明のパラジウムめっき液中の上記還元剤の含有量については特に限定はないが、パラジウムめっき液全体に対して、好ましくは1ppm~100000ppm、より好ましくは10ppm~60000ppm、特に好ましくは50ppm~30000ppm、更に好ましくは100ppm~10000ppmである。なお、還元剤を2種以上使用するときは、上記数値はそれらの合計含有量を示す。
 含有量が少な過ぎると、正常の均一な色調のパラジウム皮膜の形成が困難になる場合がある。すなわち、パラジウム皮膜の色や付き回りを目視で観察したときにパラジウムの析出異常が認められる場合がある。一方、含有量が多過ぎると、パラジウムめっき浴が不安定となり、保存容器中に高価なパラジウムが異常析出してしまい、パラジウム回収に余計なコストが必要となってしまったり、パラジウム皮膜の色調不良を引き起こしたりする場合がある。
The content of the reducing agent in the palladium plating solution of the present invention is not particularly limited, but is preferably from 1 ppm to 100,000 ppm, more preferably from 10 ppm to 60000 ppm, particularly preferably from 50 ppm to 30000 ppm, based on the whole palladium plating solution. More preferably, it is 100 ppm to 10,000 ppm. In addition, when using 2 or more types of reducing agents, the said numerical value shows those total content.
If the content is too small, it may be difficult to form a palladium film having a normal and uniform color tone. That is, there is a case where an abnormal precipitation of palladium is observed when the color and attached color of the palladium film are visually observed. On the other hand, if the content is too high, the palladium plating bath becomes unstable, and expensive palladium is abnormally deposited in the storage container, which requires extra costs for palladium recovery, or the color tone of the palladium film is poor. It may cause.
<その他の添加剤>
 本発明のパラジウムめっき液には、上記の成分以外に必要に応じて、パラジウムめっき液のpHを一定に保つための緩衝剤、パラジウムめっき液の導電性を確保するための電導塩、パラジウムめっき液中に不純物金属が混入した場合にその影響を除去するための金属イオン封鎖剤、パラジウムめっき液の泡切れを良好にするための界面活性剤、パラジウム皮膜を平滑にするための光沢剤等を適宣含有させて用いることができる。
<Other additives>
In addition to the above components, the palladium plating solution of the present invention includes, as necessary, a buffer for keeping the pH of the palladium plating solution constant, a conductive salt for ensuring the conductivity of the palladium plating solution, and a palladium plating solution. Appropriate metal sequestering agent to remove the effects of impurities contained in impurities, surfactants to improve the foaming of the palladium plating solution, brighteners to smooth the palladium film, etc. It can be used by declaring it.
 本発明のパラジウムめっき液に必要に応じて含有される緩衝剤としては、周知の緩衝剤であれば特に限定はないが、好ましいものとして、ホウ酸、リン酸等の無機酸;クエン酸、酒石酸、リンゴ酸等のオキシカルボン酸;等が挙げられる。これらは、1種又は2種以上を混合して用いることができる。 The buffer contained in the palladium plating solution of the present invention as needed is not particularly limited as long as it is a known buffer, but preferred are inorganic acids such as boric acid and phosphoric acid; citric acid and tartaric acid. And oxycarboxylic acids such as malic acid; These can be used alone or in combination of two or more.
 本発明のパラジウムめっき液中の緩衝剤の含有量は特に限定はないが、パラジウムめっき液全体に対して、通常1g/L~500g/L、好ましくは10g/L~100g/Lである。
 パラジウムめっき液中の緩衝剤の含有量が少な過ぎると、緩衝効果が発揮され難い場合があり、一方、多過ぎる場合は緩衝効果の上昇が見られず不経済の場合がある。
The content of the buffer in the palladium plating solution of the present invention is not particularly limited, but is usually 1 g / L to 500 g / L, preferably 10 g / L to 100 g / L, based on the whole palladium plating solution.
If the content of the buffering agent in the palladium plating solution is too small, the buffering effect may be difficult to be exhibited. On the other hand, if the content is too large, the buffering effect may not be increased and it may be uneconomical.
 本発明のパラジウムめっき液に必要に応じて含有される電導塩としては、周知の電導塩であれば特に限定はないが、好ましいものとして、硫酸塩、硝酸塩、リン酸塩等の無機酸塩;シュウ酸、コハク酸、グルタル酸、マロン酸、クエン酸、酒石酸、リンゴ酸等のカルボン酸;等が挙げられる。これらは1種又は2種以上を混合して用いることができる。 The conductive salt contained as needed in the palladium plating solution of the present invention is not particularly limited as long as it is a known conductive salt, but preferred are inorganic acid salts such as sulfates, nitrates and phosphates; And carboxylic acids such as oxalic acid, succinic acid, glutaric acid, malonic acid, citric acid, tartaric acid and malic acid. These may be used alone or in combination of two or more.
 本発明のパラジウムめっき液中の電導塩の含有量は特に限定はないが、パラジウムめっき液全体に対して、通常1g/L~500g/L、好ましくは10g/L~100g/Lである。
 パラジウムめっき液中の電導塩の含有量が少な過ぎると、電導効果が発揮され難い場合があり、一方、多過ぎる場合は、電導効果の上昇が見られず不経済の場合がある。
 また、前記緩衝剤と同一の成分で共用することも可能である。
The content of the conductive salt in the palladium plating solution of the present invention is not particularly limited, but is usually 1 g / L to 500 g / L, preferably 10 g / L to 100 g / L, based on the whole palladium plating solution.
If the content of the conductive salt in the palladium plating solution is too small, the conductive effect may be difficult to be exhibited. On the other hand, if the content is too high, the conductive effect may not be increased, which may be uneconomical.
It is also possible to share the same component as the buffer.
 本発明のパラジウムめっき液に必要に応じて含有される金属イオン封鎖剤としては、周知の金属イオン封鎖剤であれば特に限定はないが、好ましいものとして、イミノジ酢酸、ニトリロトリ酢酸、エチレンジアミンテトラ酢酸等のアミノカルボン酸系キレート剤;ヒドロキシエチリデンジホスホン酸、ニトリロメチレンホスホン酸、エチレンジアミンテトラメチレンホスホン酸等のホスホン酸系キレート剤;等が挙げられる。これらは1種又は2種以上を混合して用いることができる。 The sequestering agent contained as needed in the palladium plating solution of the present invention is not particularly limited as long as it is a well-known sequestering agent, but as preferred, iminodiacetic acid, nitrilotriacetic acid, ethylenediaminetetraacetic acid, etc. Aminocarboxylic acid-based chelating agents; phosphonic acid-based chelating agents such as hydroxyethylidenediphosphonic acid, nitrilomethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid; and the like. These may be used alone or in combination of two or more.
 本発明のパラジウムめっき液中の金属イオン封鎖剤の含有量は特に限定はないが、パラジウムめっき液全体に対して、通常0.1g/L~100g/L、好ましくは0.5g/L~50g/Lである。
 パラジウムめっき液中の金属イオン封鎖剤の含有量が少な過ぎると、不純物金属の影響を除去する効果が発揮され難い場合があり、一方、多過ぎる場合は不純物金属の影響を除去する効果の上昇が見られず不経済の場合がある。
The content of the sequestering agent in the palladium plating solution of the present invention is not particularly limited, but is usually 0.1 g / L to 100 g / L, preferably 0.5 g / L to 50 g based on the whole palladium plating solution. / L.
If the content of the sequestering agent in the palladium plating solution is too small, the effect of removing the influence of the impurity metal may be difficult to be exhibited, while if too much, the effect of removing the influence of the impurity metal may be increased. It may not be seen and it may be uneconomical.
 本発明のパラジウムめっき液に必要に応じて含有される界面活性剤としては、周知の界面活性剤であれば特に限定はなく、ノニオン系界面活性剤、アニオン系界面活性剤、両性界面活性剤又はカチオン系界面活性剤が用いられる。これらは1種又は2種以上を混合して用いることができる。 The surfactant contained as needed in the palladium plating solution of the present invention is not particularly limited as long as it is a known surfactant, and is a nonionic surfactant, an anionic surfactant, an amphoteric surfactant or Cationic surfactants are used. These may be used alone or in combination of two or more.
 ノニオン系界面活性剤としては、好ましいものとして、ノニフェノールポリアルコキシレート、α-ナフトールポリアルコキシレート、ジブチル-β-ナフトールポリアルコキシレート、スチレン化フェノールポリアルコキシレート等のエーテル型ノニオン系界面活性剤;オクチルアミンポリアルコキシレート、ヘキシニルアミンポリアルコキシレート、リノレイルアミンポリアルコキシレート等のアミン型ノニオン系界面活性剤;等が挙げられる。
 アニオン系界面活性剤としては、好ましいものとして、ラウリル硫酸ナトリウム等のアルキル硫酸塩;ポリオキシエチレンノニルエーテル硫酸ナトリウム等のポリオキシエチレンアルキルエーテル硫酸塩;ポリオキシエチレンアルキルフェニルエーテル硫酸塩;アルキルベンゼンスルホン酸塩;等が挙げられる。
Preferred nonionic surfactants include ether type nonionic surfactants such as noniphenol polyalkoxylate, α-naphthol polyalkoxylate, dibutyl-β-naphthol polyalkoxylate, and styrenated phenol polyalkoxylate; And amine type nonionic surfactants such as octylamine polyalkoxylate, hexynylamine polyalkoxylate, and linoleylamine polyalkoxylate.
Preferred examples of the anionic surfactant include alkyl sulfates such as sodium lauryl sulfate; polyoxyethylene alkyl ether sulfates such as sodium polyoxyethylene nonyl ether sulfate; polyoxyethylene alkylphenyl ether sulfates; Salt; and the like.
 両性界面活性剤としては、好ましいものとして、2-ウンデシル-1-カルボキシメチル-1-ヒドロキシエチルイミダゾリウム、N-ステアリル-N,N-カルボキシメチルベタイン、ラウリルジメチルアミンオキシド等が挙げられる。
 カチオン系界面活性剤としては、好ましいものとして、ラウリルトリメチルアンモニウム塩、ラウリルジメチルアンモニウムベタイン、ラウリルピリジニウム塩、オレイルイミダゾリウム塩又はステアリルアミンアセテート等が挙げられる。
Preferred examples of the amphoteric surfactant include 2-undecyl-1-carboxymethyl-1-hydroxyethylimidazolium, N-stearyl-N, N-carboxymethylbetaine, lauryldimethylamine oxide, and the like.
Preferred examples of the cationic surfactant include lauryltrimethylammonium salt, lauryldimethylammonium betaine, laurylpyridinium salt, oleylimidazolium salt, and stearylamine acetate.
 これらの界面活性剤は、1種又は2種以上を混合して用いることができる。好ましくはノニオン系界面活性剤又は両性界面活性剤である。 These surfactants can be used alone or in combination of two or more. Nonionic surfactants or amphoteric surfactants are preferred.
 本発明のパラジウムめっき液中の界面活性剤の含有量は、パラジウムめっき液全体に対して、好ましくは0.01g/L~20g/Lであるが、所望の性能を発揮すればよく、特に含有量を限定するものではない。 The content of the surfactant in the palladium plating solution of the present invention is preferably 0.01 g / L to 20 g / L with respect to the whole palladium plating solution. The amount is not limited.
 本発明のパラジウムめっき液に必要に応じて含有される光沢剤としては、周知の光沢剤であれば特に限定はないが、パラジウムめっき中で本発明における特定ピリジニウム化合物になり得ない「ピリジン骨格を有するアミン化合物」等が挙げられる。これらは1種又は2種以上を混合して用いることができる。
 ピリジン骨格を有するアミン化合物としては、2-アミノピリジン、3-アミノピリジン、4-アミノピリジン等が挙げられる。
The brightener contained as needed in the palladium plating solution of the present invention is not particularly limited as long as it is a well-known brightener. However, it cannot be a specific pyridinium compound in the present invention during palladium plating. And the like ". These may be used alone or in combination of two or more.
Examples of the amine compound having a pyridine skeleton include 2-aminopyridine, 3-aminopyridine, 4-aminopyridine and the like.
 本発明のパラジウムめっき液中の光沢剤の含有量は、パラジウムめっき液全体に対して、好ましくは0.01g/L~20g/Lであるが、所望の性能を発揮すればよく、特に含有量を限定するものではない。 The content of the brightener in the palladium plating solution of the present invention is preferably 0.01 g / L to 20 g / L with respect to the whole palladium plating solution, but it is sufficient that the desired performance is exhibited, and particularly the content. It is not intended to limit.
<パラジウムめっき液の物性>
 本発明のパラジウムめっき液は、パラジウムめっき液の物性として、パラジウムめっき液を用いて、パラジウム皮膜の膜厚が0.03μmになるようにめっき処理した基材を、5質量%硫酸水溶液に浸漬し、一定電圧300mVでピンホール試験をしたときに、試験開始から試験開始後5分までの全ての間、通電電流が100μA以下であるような皮膜物性を与えるようなパラジウムめっき液である。
 かかる物性を有するパラジウムめっき液は、前記した組成のパラジウムめっき液で初めて実現された新規なパラジウムめっき液である。
<Physical properties of palladium plating solution>
In the palladium plating solution of the present invention, as a physical property of the palladium plating solution, a substrate plated by using a palladium plating solution so that the film thickness of the palladium film is 0.03 μm is immersed in a 5% by mass sulfuric acid aqueous solution. When the pinhole test is performed at a constant voltage of 300 mV, it is a palladium plating solution that gives film properties such that the energization current is 100 μA or less during the entire period from the start of the test to 5 minutes after the start of the test.
The palladium plating solution having such physical properties is a novel palladium plating solution realized for the first time with the palladium plating solution having the above-described composition.
 本発明のパラジウムめっき液は、パラジウムめっき液の物性として、銅板上に、無電解ニッケルめっき皮膜5μm、パラジウム皮膜膜厚を0.03μmになるようにめっき処理した銅板基材を、5質量%硫酸溶液に浸漬し、電圧300mVでピンホール試験をした場合に試験開始から5分までの間、電流が100μAより多く流れないような物性を有するものであることが好ましい。 The palladium plating solution of the present invention is a 5% by mass sulfuric acid copper substrate plated on a copper plate to have an electroless nickel plating film thickness of 5 μm and a palladium film thickness of 0.03 μm. When immersed in a solution and subjected to a pinhole test at a voltage of 300 mV, it preferably has a physical property such that a current does not flow more than 100 μA for 5 minutes from the start of the test.
 本発明の「ピンホール試験」とは、常法により、無電解ニッケルめっき処理、その後、パラジウムめっき処理された銅板材を、口径10mmの円状に銅を除去して開口して陽極とし、銅材を陰極として5質量%硫酸溶液に浸漬し300mVの電圧を加え続け、通電する電流値を観察する試験をいう。
 パラジウム皮膜にピンホール等の不良部が生成していると、陽極であるパラジウム皮膜のピンホールからニッケルイオンや銅イオンが溶解し、流れる電流値が大きな値を示す。また、パラジウム皮膜にピンホール等の不良部が生成していない評価用サンプルに比べると比較的早く電流が流れ始める。
The “pinhole test” of the present invention is a copper plate material that has been electrolessly nickel-plated and then palladium-plated by a conventional method, removing copper in a circular shape with a diameter of 10 mm to form an anode, and copper A test in which a material is immersed in a 5% by mass sulfuric acid solution as a cathode, a voltage of 300 mV is continuously applied, and a current value to be energized is observed.
When a defective part such as a pinhole is generated in the palladium film, nickel ions and copper ions are dissolved from the pinhole of the palladium film as the anode, and the flowing current value shows a large value. In addition, the current starts to flow relatively quickly as compared with an evaluation sample in which a defective portion such as a pinhole is not formed on the palladium film.
 上記物性の限定は、パラジウムめっき液の物性を限定するものであって、かかるパラジウムめっき液の使用方法を限定するものではない。かかるパラジウムめっき液にて実際に形成されるパラジウム皮膜は0.03μmである必要はなく、本発明のパラジウムめっき液を用いて、例えば、膜厚0.03μm未満のパラジウム皮膜を形成してもよいし、膜厚0.03μmより厚いパラジウム皮膜を形成してもよい。 The limitation of the physical properties described above limits the physical properties of the palladium plating solution, and does not limit the method of using the palladium plating solution. The palladium film actually formed with such a palladium plating solution does not need to be 0.03 μm. For example, a palladium film having a thickness of less than 0.03 μm may be formed using the palladium plating solution of the present invention. However, a palladium film thicker than 0.03 μm may be formed.
 本発明のピンホール試験を実施した場合に、パラジウムめっき膜厚が0.05μm以下のパラジウム膜厚では(従って0.03μm以下のパラジウム膜厚では)、試験開始から「試験開始後5分」までの間、電流が100μAより多く流れないような物性を有するパラジウムめっき液は従来存在しなかった。 When the pinhole test of the present invention is carried out, when the palladium plating film thickness is 0.05 μm or less (thus, when the palladium film thickness is 0.03 μm or less), from the start of the test to “5 minutes after the start of the test” In the past, there was no palladium plating solution having such a physical property that current does not flow more than 100 μA.
<パラジウムめっき液の製造方法>
 本発明のパラジウムめっき液の製造方法は、特に限定はなく、各成分の配合順序等を含めて公知の方法が用いられる。
<Method for producing palladium plating solution>
The method for producing the palladium plating solution of the present invention is not particularly limited, and known methods including the blending order of each component and the like are used.
<パラジウム皮膜>
 本発明のパラジウムめっき液を用いてパラジウムめっきを行うことによって得られたパラジウム皮膜は、前記した効果を奏する。
 本発明のパラジウム皮膜中のパラジウムの濃度(パラジウム純度)は特に限定はないが、「パラジウム皮膜」全体に対して、パラジウムが90質量%以上であることが好ましく、95.0質量%~99.9質量%が特に好ましい。
<Palladium film>
The palladium film obtained by performing palladium plating using the palladium plating solution of the present invention exhibits the effects described above.
The concentration of palladium in the palladium film of the present invention (palladium purity) is not particularly limited, but is preferably 90% by mass or more, and 95.0% to 99.99% by mass with respect to the entire “palladium film”. 9% by mass is particularly preferred.
<パラジウムめっきの条件>
 上記した本発明のパラジウムめっき液のめっき条件は特に限定されるものではないが、温度条件としては、20℃~90℃であることが好ましく、特に好ましくは30℃~70℃である。また、めっき液のpHはpH2.0~9.0であることが好ましく、特に好ましくは、pH3.0~8.0である。
<Palladium plating conditions>
The plating conditions of the palladium plating solution of the present invention described above are not particularly limited, but the temperature conditions are preferably 20 ° C. to 90 ° C., particularly preferably 30 ° C. to 70 ° C. The pH of the plating solution is preferably pH 2.0 to 9.0, particularly preferably pH 3.0 to 8.0.
 本発明のパラジウムめっき液を用いてパラジウムめっきを行うことによって得られるパラジウム皮膜の膜厚に特に限定はないが、好ましくは0.0001μm~5μm、より好ましくは0.001μm~1μm、特に好ましくは0.005μm~0.5μm、更に好ましくは0.01μm~0.3μmである。 The film thickness of the palladium film obtained by performing palladium plating using the palladium plating solution of the present invention is not particularly limited, but is preferably 0.0001 μm to 5 μm, more preferably 0.001 μm to 1 μm, and particularly preferably 0. 0.005 μm to 0.5 μm, more preferably 0.01 μm to 0.3 μm.
 従来のパラジウムめっき液を用いて作製したパラジウムめっき皮膜の膜厚は、用途にもよるが、コネクターの場合は、通常は、0.01μm~0.5μmであった。本発明のパラジウムめっき液を用いて作製したパラジウムめっき皮膜は、膜厚を従来の30%~60%の範囲に減少させたときでも、ほぼ同等のピンホール試験や耐熱性の結果が得られる。 The film thickness of a palladium plating film produced using a conventional palladium plating solution is usually 0.01 μm to 0.5 μm in the case of a connector, although it depends on the application. The palladium plating film produced using the palladium plating solution of the present invention can obtain almost the same pinhole test and heat resistance results even when the film thickness is reduced to the conventional range of 30% to 60%.
 本発明のパラジウムめっき液を用いて、ニッケル、ニッケル合金、銅又は銅合金の皮膜上にパラジウムめっきを行うことによって得られたパラジウム皮膜は、前記した効果を奏するために好ましい。中でも、ニッケル又はニッケル合金の皮膜上が、耐熱性、パラジウムめっきに混入し悪影響を及ぼす可能性がない等の点からより好ましく、ニッケル皮膜上が特に好ましい。 A palladium film obtained by performing palladium plating on a nickel, nickel alloy, copper, or copper alloy film using the palladium plating solution of the present invention is preferable in order to achieve the above-described effects. Among these, a nickel or nickel alloy film is more preferable from the viewpoints of heat resistance and the possibility that it may be adversely affected when mixed with palladium plating, and a nickel film is particularly preferable.
<パラジウムめっき液の用途と積層された全体のめっき皮膜>
 本発明のパラジウムめっき液は、特に限定はないが、電子部品の接点部材の製造に用いられることが更に好ましい。
 従って、本発明のパラジウムめっき液を用いてパラジウムめっきを行うときは、下地めっき処理としてニッケルめっき皮膜を形成させておくことが更に好ましい。
 このときのニッケルめっき液は特に限定されるものではないが、一般的に実用されている無電解ニッケル液が好ましく、無電解ニッケル-リン液が特に好適である。ニッケルめっき液の使用方法は、特に限定はなく常法に従って使用する。
<Use of palladium plating solution and overall plating film laminated>
The palladium plating solution of the present invention is not particularly limited, but is more preferably used for manufacturing a contact member for an electronic component.
Therefore, when performing palladium plating using the palladium plating solution of the present invention, it is more preferable to form a nickel plating film as the base plating treatment.
The nickel plating solution at this time is not particularly limited, but an electroless nickel solution generally used in practice is preferred, and an electroless nickel-phosphorus solution is particularly preferred. The method of using the nickel plating solution is not particularly limited and is used according to a conventional method.
 該ニッケルめっき皮膜の膜厚は、特に限定されるものではないが、0.01μm~20μmであることが好ましく、0.05μm~5μmが特に好ましい。 The thickness of the nickel plating film is not particularly limited, but is preferably 0.01 μm to 20 μm, and particularly preferably 0.05 μm to 5 μm.
 本発明のパラジウムめっき液は、パラジウム皮膜の上に金めっきを行って金皮膜を形成させるための、下地のパラジウム皮膜形成用に用いることが好ましい。
 該金めっき皮膜の膜厚は、特に限定されるものではないが、0.0001μm~5μmであることが好ましく、0.001μm~1μmがより好ましく、0.01μm~0.5μmが特に好ましい。
 本発明の好ましい皮膜の態様は、パラジウム皮膜の上に金皮膜が施された態様であり、特に好ましい態様は、ニッケル皮膜の上にパラジウム皮膜が施され、その上に金皮膜が施された態様である。
The palladium plating solution of the present invention is preferably used for forming a base palladium film for forming a gold film by performing gold plating on the palladium film.
The thickness of the gold plating film is not particularly limited, but is preferably 0.0001 μm to 5 μm, more preferably 0.001 μm to 1 μm, and particularly preferably 0.01 μm to 0.5 μm.
A preferred coating mode of the present invention is a mode in which a gold coating is applied on a palladium coating, and a particularly preferable mode is a mode in which a palladium coating is applied on a nickel coating and a gold coating is applied thereon. It is.
 従来のパラジウムめっき液を用いて作製したパラジウムめっき皮膜の上に形成させる金皮膜の膜厚は、用途にもよるが、コネクターの場合は、通常は、0.05μm~0.2μmであった。本発明のパラジウムめっき液を用いて作製したパラジウムめっき皮膜の上に形成させる金皮膜の膜厚は、膜厚を従来の20%~60%の範囲に減少させたときでも、ほぼ同等のピンホール試験や耐熱性の結果が得られる。 The film thickness of a gold film formed on a palladium plating film produced using a conventional palladium plating solution is usually 0.05 μm to 0.2 μm in the case of a connector, although it depends on the application. The film thickness of the gold film formed on the palladium plating film produced using the palladium plating solution of the present invention is almost equal to the pinhole even when the film thickness is reduced to the conventional range of 20% to 60%. Test and heat resistance results are obtained.
 本発明の前記パラジウムめっき液は、無電解パラジウムめっき液としても、電解パラジウムめっき液としても用いられる。すなわち、本発明は、前記のパラジウムめっき液よりなる無電解パラジウムめっき液であり、前記のパラジウムめっき液よりなる電解パラジウムめっき液でもある。
 前記した「特定ピリジニウム化合物」は、無電解パラジウムめっき液中に含有されても、電解パラジウムめっき液中に含有されても、前記した効果を発揮する。
The palladium plating solution of the present invention can be used as an electroless palladium plating solution or an electrolytic palladium plating solution. That is, the present invention is an electroless palladium plating solution made of the palladium plating solution and an electrolytic palladium plating solution made of the palladium plating solution.
The above-mentioned “specific pyridinium compound” exerts the above-described effect regardless of whether it is contained in the electroless palladium plating solution or in the electrolytic palladium plating solution.
 前記した、可溶性パラジウム塩、特定ピリジニウム化合物、緩衝剤、電導塩、金属イオン封鎖剤、界面活性剤、還元剤及び光沢剤のうち、無電解パラジウムめっき液は、可溶性パラジウム塩、特定ピリジニウム化合物及び還元剤を必須成分とし、緩衝剤、金属イオン封鎖剤、界面活性剤及び/又は光沢剤を含有好適成分とする。
 また、電解パラジウムめっき液は、可溶性パラジウム塩、特定ピリジニウム化合物及び電導塩を必須成分とし、緩衝剤、金属イオン封鎖剤、界面活性剤及び/又は光沢剤を含有好適成分とする。
 無電解パラジウムめっき液、電解パラジウムめっき液とも、それぞれの成分の含有量は、前記した範囲が好ましい(より好ましい、特に好ましい)。
Among the above-mentioned soluble palladium salts, specific pyridinium compounds, buffers, conductive salts, sequestering agents, surfactants, reducing agents and brighteners, electroless palladium plating solutions are soluble palladium salts, specific pyridinium compounds and reducing agents. An agent is an essential component, and a buffering agent, a sequestering agent, a surfactant and / or a brightener are included as preferred components.
Further, the electrolytic palladium plating solution contains a soluble palladium salt, a specific pyridinium compound and a conductive salt as essential components, and a buffer, a metal ion sequestering agent, a surfactant and / or a brightening agent as preferred components.
The content of each component of the electroless palladium plating solution and the electrolytic palladium plating solution is preferably in the above range (more preferably, particularly preferable).
 無電解パラジウムめっきの場合は、常法に従って行なえばよく特に限定はないが、液温30℃~90℃が好ましく、40℃~80℃が特に好ましい。また、時間は、前記のパラジウム膜厚となるように適宣調整する。 In the case of electroless palladium plating, there is no particular limitation as long as it is carried out according to a conventional method, but the liquid temperature is preferably 30 ° C to 90 ° C, particularly preferably 40 ° C to 80 ° C. The time is appropriately adjusted so that the palladium film thickness is obtained.
 電解パラジウムめっきの場合は、常法に従って行なえばよく特に限定はないが、液温30℃~90℃が好ましく、40℃~80℃が特に好ましい。また、電流密度0.1A/dm~100A/dmが好ましく、0.5A/dm~50A/dmが特に好ましい。また、時間は、前記のパラジウム膜厚となるように適宣調整する。 In the case of electrolytic palladium plating, it may be carried out in accordance with a conventional method, but there is no particular limitation, but the liquid temperature is preferably 30 ° C. to 90 ° C., particularly preferably 40 ° C. to 80 ° C. Also, preferably the current density of 0.1A / dm 2 ~ 100A / dm 2, 0.5A / dm 2 ~ 50A / dm 2 are particularly preferred. The time is appropriately adjusted so that the palladium film thickness is obtained.
<作用・原理>
 本発明のパラジウムめっき液が、著しくピンホール等の不良部分が少ないパラジウム皮膜を形成できる作用・原理は明らかではないが、以下のことが考えられる。ただし本発明は、以下の作用・原理が成り立つ範囲に限定されるわけではない。
<Action and principle>
Although the action / principle that the palladium plating solution of the present invention can form a palladium film with extremely few defective parts such as pinholes is not clear, the following can be considered. However, the present invention is not limited to the range where the following actions and principles are established.
 本発明のパラジウムめっき液の必須成分である特定ピリジニウム化合物は、一種の結晶調整剤としての効果を持つと考えられる。めっき反応でパラジウム皮膜が形成されようとするときには、なにも制御されずにパラジウム皮膜が成長すると非常に粗い皮膜が成長すると考えられる。粗い皮膜ということは、凹凸が存在する皮膜ということである。
 この凸部分に選択的に「特定ピリジニウム化合物」が吸着し、成長を阻害しているものと考えられる。めっき成長の速かった凸部分でめっき成長が阻害されることにより、凹部分へのめっき反応が促進され、凹部分が埋められて行き、結果的に凹凸のないめっき皮膜を形成することができたと考えられる。凹部分がないめっき皮膜とは、均一にパラジウム皮膜で下地金属を被覆し、ピンホールが著しく少ないパラジウム皮膜である。
The specific pyridinium compound that is an essential component of the palladium plating solution of the present invention is considered to have an effect as a kind of crystal modifier. When a palladium film is about to be formed by a plating reaction, it is considered that a very rough film grows when the palladium film grows without any control. A rough film means a film having irregularities.
It is considered that the “specific pyridinium compound” is selectively adsorbed on the convex portions and inhibits the growth. By inhibiting plating growth at the convex part where plating growth was fast, the plating reaction to the concave part was promoted and the concave part was filled, and as a result, a plating film without unevenness could be formed. Conceivable. The plating film having no concave portion is a palladium film in which the base metal is uniformly coated with a palladium film and pinholes are extremely small.
 以下に実施例及び比較例を挙げて本発明を更に具体的に説明するが、本発明は、その要旨を超えない限りこれらの実施例に限定されるものではない。
 また、パラジウムめっき液の組成中の濃度の数値は、その成分が結晶水を含むものである場合は、結晶水を入れない質量から求めた濃度の数値である。
 含有量に関する「%」は、特に記載がない限り「質量%」を示し、「ppm」は「質量ppm」を示す。また、耐熱性の評価方法における、ニッケルと銅の「%」は、「atm%(原子基準濃度)」を示す。
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples unless it exceeds the gist.
Moreover, the numerical value of the density | concentration in the composition of a palladium plating solution is a numerical value of the density | concentration calculated | required from the mass which does not put crystallization water, when the component contains crystallization water.
“%” Regarding the content indicates “mass%” unless otherwise specified, and “ppm” indicates “mass ppm”. In the heat resistance evaluation method, “%” of nickel and copper indicates “atm% (atomic reference concentration)”.
実施例1~8、比較例1~7
<無電解パラジウムめっき液の評価>
 パラジウムめっき液全体に対して、ジクロロテトラアンミンパラジウム溶液を、パラジウム換算で1g/L、表1に示す各実施例及び各比較例に記載の特定ピリジニウム化合物若しくはその比較化合物をそれぞれ1000ppm、還元剤としてギ酸を1000ppm、及び、電導塩と緩衝剤を兼ねた成分としてクエン酸を100g/Lとなるように溶解し、pHを6.5に調整して無電解パラジウムめっき液とした。ただし、比較例7は特定ピリジニウム化合物も比較化合物も含有させなかった。
Examples 1-8, Comparative Examples 1-7
<Evaluation of electroless palladium plating solution>
Dichlorotetraammine palladium solution is 1 g / L in terms of palladium with respect to the entire palladium plating solution, each specific pyridinium compound or its comparative compound shown in Table 1 is 1000 ppm, and formic acid is used as a reducing agent. Was dissolved at 1000 ppm, and citric acid as a component serving as both a conductive salt and a buffer was adjusted to 100 g / L, and the pH was adjusted to 6.5 to obtain an electroless palladium plating solution. However, Comparative Example 7 contained neither a specific pyridinium compound nor a comparative compound.
 「比較化合物」としては、ピリジン、ピリジン-3-スルホン酸、ピコリン、キノリンスルホン酸、2,3-ジアミノピリジン、3-(3-ピリジル)アクリル酸を用いた。
 また、比較例7として、「特定ピリジニウム化合物」も「比較化合物」も含有させずに、同様に調製したパラジウムめっき液も評価した。
As “comparative compounds”, pyridine, pyridine-3-sulfonic acid, picoline, quinolinesulfonic acid, 2,3-diaminopyridine, and 3- (3-pyridyl) acrylic acid were used.
In addition, as Comparative Example 7, a palladium plating solution prepared in the same manner was evaluated without containing the “specific pyridinium compound” and the “comparative compound”.
 無電解パラジウムめっき液のpHは、20質量%水酸化カリウム水溶液とクエン酸にて調整し、パラジウムめっき液の浴温は、70℃に設定し、以下に記載の評価を行った。 The pH of the electroless palladium plating solution was adjusted with a 20% by mass potassium hydroxide aqueous solution and citric acid, the bath temperature of the palladium plating solution was set to 70 ° C., and the following evaluation was performed.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
<試験用(評価用)のパラジウム皮膜の形成方法>
 各実施例及び各比較例で調製したパラジウムめっき液を用いて、表2に示す工程にて、10mm×10mmの銅板上の無電解ニッケルめっき皮膜5.0μm上に、パラジウム皮膜を、その膜厚が0.03μmとなるように、無電解パラジウムめっき処理の時間を30秒~3分の範囲で調整して施した。
<Method for Forming Palladium Film for Testing (Evaluation)>
Using the palladium plating solution prepared in each example and each comparative example, a palladium film was formed on the electroless nickel plating film 5.0 μm on a 10 mm × 10 mm copper plate in the step shown in Table 2, and the film thickness thereof Was adjusted so that the electroless palladium plating time was 30 seconds to 3 minutes.
 なお、無電解ニッケルめっき皮膜は、「無電解ニッケルめっき液 ICPニコロン GM」(商品名)(奥野製薬工業株式会社製)を用いて、常法に従いめっき処理し、膜厚5.0μmに形成した。 In addition, the electroless nickel plating film was plated according to an ordinary method using “electroless nickel plating solution ICP Nicolon GM” (trade name) (manufactured by Okuno Pharmaceutical Co., Ltd.) to form a film thickness of 5.0 μm. .
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
<ピンホール試験の方法>
 上記したように、銅板上のニッケルめっき皮膜上に形成させた膜厚が0.03μmのパラジウム皮膜を、5質量%硫酸水溶液に浸漬し、POTENTIONSTAT/GALVANOSTAT(北斗電工株式会社製)を用い、常に一定電圧300mVを印加した。
 試験開始から1分、3分、5分における電流値(μA)を測定した。
<Pinhole test method>
As described above, a palladium film having a thickness of 0.03 μm formed on a nickel plating film on a copper plate is immersed in a 5% by mass sulfuric acid aqueous solution, and POTENTIONSTAT / GALVANOSTAT (manufactured by Hokuto Denko Co., Ltd.) is always used. A constant voltage of 300 mV was applied.
Current values (μA) at 1 minute, 3 minutes, and 5 minutes from the start of the test were measured.
 ピンホールがあると電流値が大きくなるので、試験開始から「試験開始から5分」までの間、常に通電電流が100μA以下である場合に優れたパラジウムめっき液であると判定し、より小さい通電電流の場合により優れたパラジウムめっき液であると判定した。 If there is a pinhole, the current value will increase, so from the start of the test until “5 minutes after the start of the test”, it is always judged that the current is 100 μA or less and that the plating solution is excellent, and the current is smaller. It was determined that the palladium plating solution was more excellent in the case of current.
<パラジウム皮膜の外観(色調均一性)の評価方法>
 上記したように、銅板上のニッケルめっき皮膜上に形成させた膜厚が0.03μmのパラジウム皮膜について、そのパラジウム皮膜の真上30cmのところから目視で観察して、パラジウム皮膜の表面の色調を観察した。
<Evaluation method of appearance (color tone uniformity) of palladium film>
As described above, about the palladium film with a film thickness of 0.03 μm formed on the nickel plating film on the copper plate, the color tone of the surface of the palladium film is visually observed from 30 cm directly above the palladium film. Observed.
 下地金属がニッケルであることから、色調が似ており判定が難しいが、均一なパラジウム皮膜が形成されていない場合には、大きさ0.5mm~3mm程度のまだら模様(ムラ)が観察されるので、該まだら模様(ムラ)が全く観察されないパラジウムめっき液を優れたパラジウムめっき液であると判定し、より少ないまだら模様(ムラ)しか観察されない場合により優れたパラジウムめっき液であると判定した。 Since the underlying metal is nickel, the color tone is similar and difficult to judge, but when a uniform palladium film is not formed, a mottled pattern (unevenness) with a size of about 0.5 mm to 3 mm is observed. Therefore, the palladium plating solution in which the mottled pattern (unevenness) was not observed at all was determined to be an excellent palladium plating solution, and when only a less mottled pattern (unevenness) was observed, it was determined to be an excellent palladium plating solution.
<パラジウム皮膜の膜厚の測定方法>
 パラジウムめっきが施されたパラジウム皮膜の中心付近を、蛍光X線分析装置(セイコーインスツルメンツ株式会社製、SFT9255)を使用して、常法に従ってパラジウム皮膜の膜厚を測定した。
<Measurement method of film thickness of palladium film>
The thickness of the palladium film was measured in the vicinity of the center of the palladium film on which the palladium plating was performed using a fluorescent X-ray analyzer (SFT 9255, manufactured by Seiko Instruments Inc.) according to a conventional method.
<耐熱性の評価方法>
 ピンホール試験用に作製した評価用サンプルと同じ工程で、銅板上のニッケルめっき皮膜上に膜厚0.03μmでパラジウム皮膜を形成させて評価用サンプルを作製した。
 パラジウム皮膜の上に金皮膜を施す場合は、パラジウム皮膜を形成させた後に、常法に従い所定の膜厚で金皮膜を形成させて評価用サンプルを作製した。
 その評価用サンプルを、庫内が200℃に調整されたオーブンで15時間加熱した。
 加熱後の評価用サンプルの表面を、表面オージェ;SAM-4300(アルバックファイ株式会社製)を用い、加速電圧5kVで測定した。
<Method for evaluating heat resistance>
In the same process as the evaluation sample prepared for the pinhole test, an evaluation sample was prepared by forming a palladium film with a film thickness of 0.03 μm on the nickel plating film on the copper plate.
In the case of applying a gold film on the palladium film, after forming the palladium film, a gold film was formed with a predetermined film thickness according to a conventional method to prepare an evaluation sample.
The sample for evaluation was heated for 15 hours in an oven whose inside was adjusted to 200 ° C.
The surface of the sample for evaluation after heating was measured at an acceleration voltage of 5 kV using a surface Auger; SAM-4300 (manufactured by ULVAC-PHI Co., Ltd.).
 ニッケル10%未満であり、かつ銅0.5%未満であることを満足する評価用サンプル及びパラジウムめっき液を「良品」と判定し、ニッケル、銅の何れかが上記規定値以上である評価用サンプル及びパラジウムめっき液を「不良品」と判定した。 Evaluation samples satisfying nickel content of less than 10% and copper content of less than 0.5% and palladium plating solutions are judged as “non-defective”, and either nickel or copper is above the specified value. The sample and the palladium plating solution were determined as “defective products”.
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
 表3から分かるように、本発明の無電解パラジウムめっき液を用いると、ピンホール試験で、試験開始から「試験開始後5分まで」の時間、常に100μAより大きい電流が流れず、かつ、パラジウム皮膜の目視での外観に、まだら模様やムラが観察されず、色調均一性が良好で、パラジウムの析出異常が認められなかった。
 また、耐熱性試験では、何れもニッケルが10%未満であり、かつ銅が0.5%未満であり全て「良品」と判定された。
 一方、特定ピリジニウム化合物を含有しない電解パラジウムめっき液では、ピンホール試験結果、又は、パラジウム皮膜の外観(色調均一性)の何れか又は両方が劣っていた。
 また、耐熱性試験では、何れもニッケルが10%以上であり、全て「不良品」と判定された。
As can be seen from Table 3, when the electroless palladium plating solution of the present invention is used, in the pinhole test, a current greater than 100 μA does not always flow during the time from the start of the test to “5 minutes after the start of the test”, and the palladium In the visual appearance of the film, no mottled pattern or unevenness was observed, the color tone uniformity was good, and no abnormal precipitation of palladium was observed.
In the heat resistance test, nickel was less than 10% and copper was less than 0.5%, and all were judged as “good”.
On the other hand, in the electrolytic palladium plating solution not containing the specific pyridinium compound, either or both of the pinhole test result and the appearance (color tone uniformity) of the palladium film were inferior.
In the heat resistance test, nickel was 10% or more, and all were judged as “defective products”.
実施例11~18
 実施例1~8で用いたものと同様の評価用サンプルを作成し、その上に、0.01μm、0.05μm及び0.1μmの金皮膜をそれぞれ形成させた。
Examples 11-18
Samples for evaluation similar to those used in Examples 1 to 8 were prepared, and gold films of 0.01 μm, 0.05 μm, and 0.1 μm were formed thereon, respectively.
 耐熱性試験を実施したところ、実施例11~18の何れもが、何れの膜厚の金皮膜の場合でも、ニッケルが10%未満であり、かつ銅が0.5%未満であったため、全て良品と判定された。 When a heat resistance test was conducted, all of Examples 11 to 18 were less than 10% nickel and less than 0.5% copper in all cases of the gold film. It was determined to be good.
比較例11~17
 比較例1~7で用いたものに対応させて同様の評価用サンプルを作成し、その上に、0.01μm、0.05μm及び0.1μmの金皮膜をそれぞれ形成させた。
Comparative Examples 11-17
Corresponding samples for evaluation were prepared corresponding to those used in Comparative Examples 1 to 7, and gold films of 0.01 μm, 0.05 μm, and 0.1 μm were formed thereon, respectively.
 耐熱性試験を実施したところ、比較例11~17の何れもが、0.1μmの金皮膜の場合は、ニッケル10%未満、かつ銅0.5%未満であり、良品と判定されたものの、0.01μm及び0.05μmの金皮膜の場合は、何れもニッケルが10%以上であるか、又は、銅が0.5%以上検出され、何れも不良品と判定された。
 比較例11~17は、パラジウム皮膜の耐熱性能が劣っているため、パラジウム皮膜の上の金皮膜を十分に薄くできないことが分かった。
When a heat resistance test was conducted, all of Comparative Examples 11 to 17 had a nickel film of 0.1 μm, which was less than 10% nickel and less than 0.5% copper. In the case of 0.01 μm and 0.05 μm gold films, either nickel was 10% or more, or copper was detected 0.5% or more, and both were judged to be defective.
In Comparative Examples 11 to 17, it was found that the gold film on the palladium film could not be made sufficiently thin because the heat resistance performance of the palladium film was inferior.
実施例21
<電解パラジウムめっき液の評価>
 パラジウムめっき液全体に対して、ジクロロテトラアンミンパラジウム溶液を、パラジウム換算で1g/L、実施例1と同様の特定ピリジニウム化合物(1-メチル-3-カルボキシピリジニウム塩酸塩)を1000ppm、及び、電導塩と緩衝剤を兼ねた成分としてクエン酸を100g/Lとなるように溶解し、pHを6.5に調整して、電解パラジウムめっき液とした。
Example 21
<Evaluation of electrolytic palladium plating solution>
With respect to the whole palladium plating solution, the dichlorotetraammine palladium solution is 1 g / L in terms of palladium, the specific pyridinium compound similar to Example 1 (1-methyl-3-carboxypyridinium hydrochloride) is 1000 ppm, and the conductive salt Citric acid was dissolved as a component also serving as a buffer so as to be 100 g / L, and the pH was adjusted to 6.5 to obtain an electrolytic palladium plating solution.
比較例21
 実施例21において、特定ピリジニウム化合物を用いる代わりに、比較例1の比較化合物(ピリジン)を用いた以外は、実施例21と同様にして電解パラジウムめっき液を調液した。
Comparative Example 21
In Example 21, instead of using the specific pyridinium compound, an electrolytic palladium plating solution was prepared in the same manner as in Example 21 except that the comparative compound (pyridine) of Comparative Example 1 was used.
<試験用(評価用)のパラジウム皮膜の形成方法>
 前記無電解パラジウムめっき液を用いた場合の、「その膜厚が0.03μmとなるように、無電解パラジウムめっき処理の時間を30秒~3分の範囲で調整して施した。」の部分を、「その膜厚が0.03μmとなるように、電解パラジウムめっき処理の電流密度を0.5A/dmで、5秒間の前後で調整して施した。」と代えた以外は、前記無電解パラジウムめっき液を用いた場合の「試験用(評価用)のパラジウム皮膜の形成方法」と同様にして、評価用サンプルを作製した。
<Method for Forming Palladium Film for Testing (Evaluation)>
When the electroless palladium plating solution is used, “the electroless palladium plating treatment time is adjusted in the range of 30 seconds to 3 minutes so that the film thickness is 0.03 μm”. Except that the current density of the electrolytic palladium plating treatment was adjusted to 0.5 A / dm 2 before and after 5 seconds so that the film thickness was 0.03 μm. An evaluation sample was prepared in the same manner as in “Method for forming a test (evaluation) palladium film” in the case of using an electroless palladium plating solution.
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006
 表4から分かるように、本発明の電解パラジウムめっき液(実施例21)を用いると、ピンホール試験で、試験開始から「試験開始後5分まで」の時間、常に100μAより大きい電流が流れず、かつ、パラジウム皮膜の目視での外観に、まだら模様やムラが観察されず、色調均一性が良好で、パラジウムの析出異常が認められなかった。
 また、耐熱性試験では、ニッケルが10%未満であり、かつ銅が0.5%未満であり、「良品」と判定された。
 一方、特定ピリジニウム化合物を含有しない電解パラジウムめっき液(比較例21)では、ピンホール試験結果が劣っていた。
 また、耐熱性試験では、ニッケルが10%以上であり、かつ銅が0.5%以上であり、「不良品」と判定された。
As can be seen from Table 4, when the electrolytic palladium plating solution of the present invention (Example 21) was used, a current greater than 100 μA did not always flow in the pinhole test from the start of the test to “5 minutes after the start of the test”. In addition, no speckled pattern or unevenness was observed in the visual appearance of the palladium film, the color tone uniformity was good, and no abnormal precipitation of palladium was observed.
Further, in the heat resistance test, nickel was less than 10% and copper was less than 0.5%, which was judged as “good”.
On the other hand, the electrolytic palladium plating solution not containing the specific pyridinium compound (Comparative Example 21) was inferior in the pinhole test result.
Further, in the heat resistance test, nickel was 10% or more and copper was 0.5% or more, which was judged as “defective product”.
実施例22~28、比較例22~27
<電解パラジウムめっき液の評価>
 実施例22~28、比較例22~27に対応させて、表1に示した実施例2~8及び比較例2~7に記載の特定ピリジニウム化合物若しくはその比較化合物をそれぞれ1000ppm用いた以外は、実施例21と同様に電解パラジウムめっき液を調液して同様に評価した。ただし、比較例27は特定ピリジニウム化合物も比較化合物も含有させなかった。
Examples 22 to 28, Comparative Examples 22 to 27
<Evaluation of electrolytic palladium plating solution>
Corresponding to Examples 22 to 28 and Comparative Examples 22 to 27, except that 1000 ppm of the specific pyridinium compound described in Examples 2 to 8 and Comparative Examples 2 to 7 shown in Table 1 or its comparative compound was used, respectively. In the same manner as in Example 21, an electrolytic palladium plating solution was prepared and evaluated in the same manner. However, Comparative Example 27 contained neither a specific pyridinium compound nor a comparative compound.
 本発明の電解パラジウムめっき液(実施例22~28)を用いると、ピンホール試験で、試験開始から「試験開始後5分まで」の時間、常に100μAより大きい電流が流れず、かつ、パラジウム皮膜の目視での外観に、まだら模様やムラが観察されず、色調均一性が良好で、パラジウムの析出異常が認められなかった。
 また、耐熱性試験では、何れもニッケルが10%未満であり、かつ銅が0.5%未満であり全て「良品」と判定された。
 一方、特定ピリジニウム化合物を含有しない電解パラジウムめっき液では、ピンホール試験結果、又は、パラジウム皮膜の外観(色調均一性)の何れか又は両方が劣っていた。
 また、耐熱性試験では、全てニッケルが10%以上であるか、又は、銅が0.5%以上であり「不良品」と判定された。
When the electrolytic palladium plating solution of the present invention (Examples 22 to 28) is used, a current exceeding 100 μA does not always flow in the pinhole test from the start of the test to “5 minutes after the start of the test”, and the palladium film In the visual appearance, no mottled pattern or unevenness was observed, the color tone uniformity was good, and no abnormal precipitation of palladium was observed.
In the heat resistance test, nickel was less than 10% and copper was less than 0.5%, and all were judged as “good”.
On the other hand, in the electrolytic palladium plating solution not containing the specific pyridinium compound, either or both of the pinhole test result and the appearance (color tone uniformity) of the palladium film were inferior.
In the heat resistance test, nickel was 10% or more, or copper was 0.5% or more, and it was determined as “defective”.
 本発明のパラジウムめっき液を用いて得られたパラジウム皮膜は、優れた耐熱特性を有し、その優れた耐熱性からパラジウム皮膜上に形成する金めっき皮膜の膜厚を減らすことができ、大幅なコストダウンを実現できるものであり、特に、パラジウム\金めっきに広く利用されるものであり、更に、無電解ニッケル\パラジウム\金という層構成を有するプロセスに最適であり、電子機器部材のめっき分野に特に好適に利用されるものである。 The palladium film obtained using the palladium plating solution of the present invention has excellent heat resistance characteristics, and can reduce the film thickness of the gold plating film formed on the palladium film due to its excellent heat resistance. Cost reduction can be realized, and it is especially widely used for palladium / gold plating, and it is most suitable for processes having a layer structure of electroless nickel / palladium / gold. Is particularly preferably used.

Claims (12)

  1.  パラジウム源としての可溶性パラジウム塩、並びに、1位の窒素原子にアルキル基が結合され、2位ないし6位の1個ないし5個が、アルキル基、アリール基、カルボキシ基、アルコキシカルボニル基、スルホ基、アルコキシスルホニル基、アミノ基、アルキルアミノ基、ジアルキルアミノ基及びシアノ基からなる群より選ばれた1種又は2種以上の特定置換基で置換された特定ピリジニウム化合物を含有することを特徴とするパラジウムめっき液。 Soluble palladium salt as a palladium source, and an alkyl group is bonded to the nitrogen atom at the 1-position, and 1 to 5 at the 2-position to the 6-position are an alkyl group, aryl group, carboxy group, alkoxycarbonyl group, sulfo group A specific pyridinium compound substituted with one or more specific substituents selected from the group consisting of an alkoxysulfonyl group, an amino group, an alkylamino group, a dialkylamino group and a cyano group. Palladium plating solution.
  2.  ピリジニウム環の2位ないし4位の1個ないし3個が、1種又は2種以上の上記特定置換基で置換された特定ピリジニウム化合物を含有する請求項1に記載のパラジウムめっき液。 The palladium plating solution according to claim 1, comprising one or three of the 2-position to 4-position of the pyridinium ring containing a specific pyridinium compound substituted with one or more of the specific substituents.
  3.  1位の窒素原子に、メチル基、エチル基、プロピル基又はブチル基が結合された上記特定ピリジニウム化合物を含有する請求項1又は請求項2に記載のパラジウムめっき液。 The palladium plating solution according to claim 1 or 2, which contains the specific pyridinium compound in which a methyl group, an ethyl group, a propyl group, or a butyl group is bonded to a nitrogen atom at the 1-position.
  4.  上記可溶性パラジウム塩が、塩化パラジウム、硫酸パラジウム、酢酸パラジウム、硝酸パラジウム、酸化パラジウム、ジクロロテトラアンミンパラジウム、ジニトロジアンミンパラジウム、ジクロロジエチレンジアミンパラジウム、テトラキス(トリフェニルホスフィン)パラジウム、ジクロロビス(トリフェニルホスフィン)パラジウム及び/又はビス(アセチルアセトナト)パラジウムである請求項1ないし請求項3の何れかの請求項に記載のパラジウムめっき液。 The soluble palladium salt is palladium chloride, palladium sulfate, palladium acetate, palladium nitrate, palladium oxide, dichlorotetraammine palladium, dinitrodiammine palladium, dichlorodiethylenediamine palladium, tetrakis (triphenylphosphine) palladium, dichlorobis (triphenylphosphine) palladium and The palladium plating solution according to any one of claims 1 to 3, which is / or bis (acetylacetonato) palladium.
  5.  更に、還元剤として、次亜リン酸、次亜リン酸塩、亜リン酸、亜リン酸塩、ギ酸、ギ酸塩及び/又はホルムアルデヒドを含有する請求項1ないし請求項4の何れかの請求項に記載のパラジウムめっき液。 Furthermore, hypophosphorous acid, hypophosphite, phosphorous acid, phosphite, formic acid, formate and / or formaldehyde as a reducing agent is claimed in any one of claims 1 to 4. 2. Palladium plating solution described in 1.
  6.  上記特定ピリジニウム化合物が、
     1-メチル-2-メチルピリジニウム、1-メチル-2-エチルピリジニウム、1-メチル-2-ブチルピリジニウム、1-メチル-2-スルホピリジニウム、1-メチル-2-メトキシスルホニルピリジニウム、1-メチル-2-アミノピリジニウム、1-メチル-2-カルボキシピリジニウム、1-メチル-2-メトキシカルボニルピリジニウム、1-メチル-2-フェニルピリジニウム、1-メチル-2-シアノピリジニウム;
     1-エチル-2-メチルピリジニウム、1-エチル-2-エチルピリジニウム、1-エチル-2-ブチルピリジニウム、1-エチル-2-スルホピリジニウム、1-エチル-2-メトキシスルホニルピリジニウム、1-エチル-2-アミノピリジニウム、1-エチル-2-カルボキシピリジニウム、1-エチル-2-メトキシカルボニルピリジニウム、1-エチル-2-フェニルピリジニウム、1-エチル-2-シアノピリジニウム;
     1-プロピル-2-メチルピリジニウム、1-プロピル-2-エチルピリジニウム、1-プロピル-2-ブチルピリジニウム、1-プロピル-2-スルホピリジニウム、1-プロピル-2-メトキシスルホニルピリジニウム、1-プロピル-2-アミノピリジニウム、1-プロピル-2-カルボキシピリジニウム、1-プロピル-2-メトキシカルボニルピリジニウム、1-プロピル-2-フェニルピリジニウム、1-プロピル-2-シアノピリジニウム;
     1-ブチル-2-メチルピリジニウム、1-ブチル-2-エチルピリジニウム、1-ブチル-2-ブチルピリジニウム、1-ブチル-2-スルホピリジニウム、1-ブチル-2-メトキシスルホニルピリジニウム、1-ブチル-2-アミノピリジニウム、1-ブチル-2-カルボキシピリジニウム、1-ブチル-2-メトキシカルボニルピリジニウム、1-ブチル-2-フェニルピリジニウム、1-ブチル-2-シアノピリジニウム;
     1-メチル-3-メチルピリジニウム、1-メチル-3-エチルピリジニウム、1-メチル-3-ブチルピリジニウム、1-メチル-3-スルホピリジニウム、1-メチル-3-メトキシスルホニルピリジニウム、1-メチル-3-アミノピリジニウム、1-メチル-3-カルボキシピリジニウム、1-メチル-3-メトキシカルボニルピリジニウム、1-メチル-3-フェニルピリジニウム、1-メチル-3-シアノピリジニウム;
     1-エチル-3-メチルピリジニウム、1-エチル-3-エチルピリジニウム、1-エチル-3-ブチルピリジニウム、1-エチル-3-スルホピリジニウム、1-エチル-3-メトキシスルホニルピリジニウム、1-エチル-3-アミノピリジニウム、1-エチル-3-カルボキシピリジニウム、1-エチル-3-メトキシカルボニルピリジニウム、1-エチル-3-フェニルピリジニウム、1-エチル-3-シアノピリジニウム;
     1-プロピル-3-メチルピリジニウム、1-プロピル-3-エチルピリジニウム、1-プロピル-3-ブチルピリジニウム、1-プロピル-3-スルホピリジニウム、1-プロピル-3-メトキシスルホニルピリジニウム、1-プロピル-3-アミノピリジニウム、1-プロピル-3-カルボキシピリジニウム、1-プロピル-3-メトキシカルボニルピリジニウム、1-プロピル-3-フェニルピリジニウム、1-プロピル-3-シアノピリジニウム;
     1-ブチル-3-メチルピリジニウム、1-ブチル-3-エチルピリジニウム、1-ブチル-3-ブチルピリジニウム、1-ブチル-3-スルホピリジニウム、1-ブチル-3-メトキシスルホニルピリジニウム、1-ブチル-3-アミノピリジニウム、1-ブチル-3-カルボキシピリジニウム、1-ブチル-3-メトキシカルボニルピリジニウム、1-ブチル-3-フェニルピリジニウム、1-ブチル-3-シアノピリジニウム;
     1-メチル-4-メチルピリジニウム、1-メチル-4-エチルピリジニウム、1-メチル-4-ブチルピリジニウム、1-メチル-4-スルホピリジニウム、1-メチル-4-メトキシスルホニルピリジニウム、1-メチル-4-アミノピリジニウム、1-メチル-4-カルボキシピリジニウム、1-メチル-4-メトキシカルボニルピリジニウム、1-メチル-4-フェニルピリジニウム、1-メチル-4-シアノピリジニウム;
     1-エチル-4-メチルピリジニウム、1-エチル-4-エチルピリジニウム、1-エチル-4-ブチルピリジニウム、1-エチル-4-スルホピリジニウム、1-エチル-4-メトキシスルホニルピリジニウム、1-エチル-4-アミノピリジニウム、1-エチル-4-カルボキシピリジニウム、1-エチル-4-メトキシカルボニルピリジニウム、1-エチル-4-フェニルピリジニウム、1-エチル-4-シアノピリジニウム;
     1-プロピル-4-メチルピリジニウム、1-プロピル-4-エチルピリジニウム、1-プロピル-4-ブチルピリジニウム、1-プロピル-4-スルホピリジニウム、1-プロピル-4-メトキシスルホニルピリジニウム、1-プロピル-4-アミノピリジニウム、1-プロピル-4-カルボキシピリジニウム、1-プロピル-4-メトキシカルボニルピリジニウム、1-プロピル-4-フェニルピリジニウム、1-プロピル-4-シアノピリジニウム;
     1-ブチル-4-メチルピリジニウム、1-ブチル-4-エチルピリジニウム、1-ブチル-4-ブチルピリジニウム、1-ブチル-4-スルホピリジニウム、1-ブチル-4-メトキシスルホニルピリジニウム、1-ブチル-4-アミノピリジニウム、1-ブチル-4-カルボキシピリジニウム、1-ブチル-4-メトキシカルボニルピリジニウム、1-ブチル-4-フェニルピリジニウム、1-ブチル-4-シアノピリジニウム;
    の何れか1種又は2種以上の特定ピリジニウム化合物である請求項1ないし請求項5の何れかの請求項に記載のパラジウムめっき液。
    The specific pyridinium compound is
    1-methyl-2-methylpyridinium, 1-methyl-2-ethylpyridinium, 1-methyl-2-butylpyridinium, 1-methyl-2-sulfopyridinium, 1-methyl-2-methoxysulfonylpyridinium, 1-methyl- 2-aminopyridinium, 1-methyl-2-carboxypyridinium, 1-methyl-2-methoxycarbonylpyridinium, 1-methyl-2-phenylpyridinium, 1-methyl-2-cyanopyridinium;
    1-ethyl-2-methylpyridinium, 1-ethyl-2-ethylpyridinium, 1-ethyl-2-butylpyridinium, 1-ethyl-2-sulfopyridinium, 1-ethyl-2-methoxysulfonylpyridinium, 1-ethyl- 2-aminopyridinium, 1-ethyl-2-carboxypyridinium, 1-ethyl-2-methoxycarbonylpyridinium, 1-ethyl-2-phenylpyridinium, 1-ethyl-2-cyanopyridinium;
    1-propyl-2-methylpyridinium, 1-propyl-2-ethylpyridinium, 1-propyl-2-butylpyridinium, 1-propyl-2-sulfopyridinium, 1-propyl-2-methoxysulfonylpyridinium, 1-propyl- 2-aminopyridinium, 1-propyl-2-carboxypyridinium, 1-propyl-2-methoxycarbonylpyridinium, 1-propyl-2-phenylpyridinium, 1-propyl-2-cyanopyridinium;
    1-butyl-2-methylpyridinium, 1-butyl-2-ethylpyridinium, 1-butyl-2-butylpyridinium, 1-butyl-2-sulfopyridinium, 1-butyl-2-methoxysulfonylpyridinium, 1-butyl- 2-aminopyridinium, 1-butyl-2-carboxypyridinium, 1-butyl-2-methoxycarbonylpyridinium, 1-butyl-2-phenylpyridinium, 1-butyl-2-cyanopyridinium;
    1-methyl-3-methylpyridinium, 1-methyl-3-ethylpyridinium, 1-methyl-3-butylpyridinium, 1-methyl-3-sulfopyridinium, 1-methyl-3-methoxysulfonylpyridinium, 1-methyl- 3-aminopyridinium, 1-methyl-3-carboxypyridinium, 1-methyl-3-methoxycarbonylpyridinium, 1-methyl-3-phenylpyridinium, 1-methyl-3-cyanopyridinium;
    1-ethyl-3-methylpyridinium, 1-ethyl-3-ethylpyridinium, 1-ethyl-3-butylpyridinium, 1-ethyl-3-sulfopyridinium, 1-ethyl-3-methoxysulfonylpyridinium, 1-ethyl- 3-aminopyridinium, 1-ethyl-3-carboxypyridinium, 1-ethyl-3-methoxycarbonylpyridinium, 1-ethyl-3-phenylpyridinium, 1-ethyl-3-cyanopyridinium;
    1-propyl-3-methylpyridinium, 1-propyl-3-ethylpyridinium, 1-propyl-3-butylpyridinium, 1-propyl-3-sulfopyridinium, 1-propyl-3-methoxysulfonylpyridinium, 1-propyl- 3-aminopyridinium, 1-propyl-3-carboxypyridinium, 1-propyl-3-methoxycarbonylpyridinium, 1-propyl-3-phenylpyridinium, 1-propyl-3-cyanopyridinium;
    1-butyl-3-methylpyridinium, 1-butyl-3-ethylpyridinium, 1-butyl-3-butylpyridinium, 1-butyl-3-sulfopyridinium, 1-butyl-3-methoxysulfonylpyridinium, 1-butyl- 3-aminopyridinium, 1-butyl-3-carboxypyridinium, 1-butyl-3-methoxycarbonylpyridinium, 1-butyl-3-phenylpyridinium, 1-butyl-3-cyanopyridinium;
    1-methyl-4-methylpyridinium, 1-methyl-4-ethylpyridinium, 1-methyl-4-butylpyridinium, 1-methyl-4-sulfopyridinium, 1-methyl-4-methoxysulfonylpyridinium, 1-methyl- 4-aminopyridinium, 1-methyl-4-carboxypyridinium, 1-methyl-4-methoxycarbonylpyridinium, 1-methyl-4-phenylpyridinium, 1-methyl-4-cyanopyridinium;
    1-ethyl-4-methylpyridinium, 1-ethyl-4-ethylpyridinium, 1-ethyl-4-butylpyridinium, 1-ethyl-4-sulfopyridinium, 1-ethyl-4-methoxysulfonylpyridinium, 1-ethyl- 4-aminopyridinium, 1-ethyl-4-carboxypyridinium, 1-ethyl-4-methoxycarbonylpyridinium, 1-ethyl-4-phenylpyridinium, 1-ethyl-4-cyanopyridinium;
    1-propyl-4-methylpyridinium, 1-propyl-4-ethylpyridinium, 1-propyl-4-butylpyridinium, 1-propyl-4-sulfopyridinium, 1-propyl-4-methoxysulfonylpyridinium, 1-propyl- 4-aminopyridinium, 1-propyl-4-carboxypyridinium, 1-propyl-4-methoxycarbonylpyridinium, 1-propyl-4-phenylpyridinium, 1-propyl-4-cyanopyridinium;
    1-butyl-4-methylpyridinium, 1-butyl-4-ethylpyridinium, 1-butyl-4-butylpyridinium, 1-butyl-4-sulfopyridinium, 1-butyl-4-methoxysulfonylpyridinium, 1-butyl- 4-aminopyridinium, 1-butyl-4-carboxypyridinium, 1-butyl-4-methoxycarbonylpyridinium, 1-butyl-4-phenylpyridinium, 1-butyl-4-cyanopyridinium;
    The palladium plating solution according to any one of claims 1 to 5, wherein the palladium plating solution is any one or two or more specific pyridinium compounds.
  7.  上記還元剤が、次亜リン酸、次亜リン酸ナトリウム、次亜リン酸カリウム、次亜リン酸アンモニウム、亜リン酸、亜リン酸ナトリウム、亜リン酸カリウム、亜リン酸アンモニウム、ギ酸、ギ酸ナトリウム、ギ酸カリウム、ギ酸アンモニウム及び/又はホルムアルデヒドである請求項5又は請求項6に記載のパラジウムめっき液。 The reducing agent is hypophosphorous acid, sodium hypophosphite, potassium hypophosphite, ammonium hypophosphite, phosphorous acid, sodium phosphite, potassium phosphite, ammonium phosphite, formic acid, formic acid The palladium plating solution according to claim 5 or 6, which is sodium, potassium formate, ammonium formate and / or formaldehyde.
  8.  パラジウムめっき液を用いて、パラジウム皮膜の膜厚が0.03μmになるようにめっき処理した基材を、5質量%硫酸水溶液に浸漬し、一定電圧300mVでピンホール試験をしたときに、試験開始から試験開始後5分までの全ての間、通電電流が100μA以下であるような皮膜物性を与えるようなものである請求項1ないし請求項7の何れかの請求項に記載のパラジウムめっき液。 The test was started when a substrate plated with a palladium plating solution so that the film thickness of the palladium film was 0.03 μm was immersed in a 5 mass% sulfuric acid aqueous solution and a pinhole test was performed at a constant voltage of 300 mV. The palladium plating solution according to any one of claims 1 to 7, wherein the plating physical property is such that an energization current is 100 µA or less for all of from 5 to 5 minutes after the start of the test.
  9.  請求項1ないし請求項8の何れかの請求項に記載のパラジウムめっき液を用いて、ニッケル、ニッケル合金、銅又は銅合金の皮膜上にパラジウムめっきを行うことによって得られたものであることを特徴とするパラジウム皮膜。 It is obtained by performing palladium plating on the nickel, nickel alloy, copper or copper alloy film using the palladium plating solution according to any one of claims 1 to 8. Characteristic palladium film.
  10.  請求項9に記載のパラジウム皮膜を有することを特徴とする電子部品の接点部材。 A contact member for electronic parts, comprising the palladium film according to claim 9.
  11.  請求項1ないし請求項8の何れかの請求項に記載のパラジウムめっき液よりなることを特徴とする無電解パラジウムめっき液。 An electroless palladium plating solution comprising the palladium plating solution according to any one of claims 1 to 8.
  12.  請求項1ないし請求項8の何れかの請求項に記載のパラジウムめっき液よりなることを特徴とする電解パラジウムめっき液。 An electrolytic palladium plating solution comprising the palladium plating solution according to any one of claims 1 to 8.
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