JP2019203156A - Electrolytic palladium-copper alloy plating solution for forming palladium-copper alloy peeling foil - Google Patents

Abstract

To provide an electrolytic palladium-copper alloy plating solution for forming a palladium-copper alloy peeling foil, having such features that: peelability from a metal substrate having an oxide film on a surface is good; after peeling from the metal substrate, it is flexible and has less warping (curl); there are few defects such as pin holes and cracks; even if annealing is not performed after plating, it has a uniform alloy composition in a thickness direction of the foil: and there is little difference in the alloy ratio between the front and back.SOLUTION: An electrolytic palladium-copper alloy plating solution according to the present invention contains (A) palladium (II) ammine complex salt, (B) copper (II) salt, (C) a pyrophosphate compound and/or tripolyphosphate compound, (D) a tetravalent selenium compound, and (E) a pyridine sulfonic acid compound. The molar concentration of (C) is adjusted to 0.35 mol/L or more and 1.1 mol/L or less, the value obtained by dividing the molar concentration of the compound belonging to (C) by the molar concentration of copper is adjusted to 4.8 or more to 23.2 or less, and the pH is adjusted to 7.5 or more to 9.5 or less.SELECTED DRAWING: None

Description

  The present invention relates to an electrolytic palladium-copper alloy plating solution for forming a palladium-copper alloy release foil (hereinafter sometimes simply referred to as “electrolytic palladium-copper alloy plating solution”, “palladium-copper alloy plating solution”, or “plating solution”).

  Palladium foil and palladium alloy foil are widely used industrially as decorative materials, dental materials, electronic materials, catalyst materials, and the like. Conventionally, palladium foil and palladium alloy foil are manufactured by melting a raw metal ingot, rolling it and processing it into a foil shape (rolling method).

Since palladium is a noble metal, there is a demand for a palladium alloy foil that is cheaper, thinner, flexible, and has a silver appearance than palladium alone.
However, when trying to obtain a thin foil having a thickness of about 0.5 μm to 20 μm, it has been difficult to stably produce a foil having a uniform thickness and flexibility with few defects by the conventional rolling method. Further, the rolling method has a fatal defect that the cost increases as the foil is made thinner.

On the other hand, as a method for producing a palladium alloy foil, a method of forming a foil by film formation by vapor deposition or sputtering is also known.
However, these methods have a problem that the foil forming speed is very slow and the mechanical strength of the foil is insufficient.

Thus, attempts have been made to produce palladium alloy foils by electrolytic plating.
In Patent Document 1, a palladium plating film is continuously formed on a support by an electrolytic plating method, and after peeling off the palladium plating film, an electrolytic silver plating film is applied on both sides thereof, and heat treatment under an inert gas is performed. A method for producing a palladium alloy foil for obtaining a palladium-silver alloy foil is disclosed.
However, this method has a high manufacturing cost because it is alloyed by heat treatment after plating, and the cost of the foil itself is still high because it contains silver. Moreover, in the case of palladium-silver alloy foil, although it has a silver appearance, since it contains silver, there existed a subject that the discoloration resistance with respect to sulfur gas was scarce and discoloration was easy to occur.

  As a palladium alloy plating solution for producing a palladium alloy film having a silver appearance, palladium nickel alloy plating solution, palladium cobalt alloy plating solution, palladium silver alloy plating solution, palladium tin alloy plating solution, palladium copper alloy plating solution, palladium Zinc alloy plating solutions have been developed.

In these alloys, when the alloy eutectoid rate is the same mass% and the cost is compared, silver is the highest, cobalt, tin, nickel, copper and zinc become cheaper in this order, and palladium copper alloy plating is required in terms of cost and corrosion resistance. ing.
Conventionally, electrolytic palladium copper alloy plating films (coating layers) and electrolytic palladium copper alloy plating solutions have been known as applications for jewelry, sterilizing agents, and hydrogen purification.

Patent Document 2 discloses a palladium copper alloy plating coating layer containing 50 to 95% palladium, and an electrolytic palladium copper alloy plating solution for forming the palladium copper alloy plating coating layer. A jewelry having a palladium copper alloy plating coating layer having a white appearance on a material is described.
However, the plating solution described in the examples of Patent Document 2 uses ethylenediamine or EDTA (ethylenediaminetetraacetic acid) as a complexing agent, and according to the inventor's additional test, the stress of the plating film is high and the appearance is reddish. There was a problem that it was easy to take on.

Patent Document 3 discloses a palladium-copper alloy plating solution containing a soluble palladium salt, a soluble copper salt, a conductive compound, a pyridine ring-containing compound, and a soluble metalloid compound. It is described that a bactericidal member in which palladium 40 to 99% by weight of palladium copper alloy plating layer is coated on at least a part of the material surface is manufactured.
According to the study by the present inventors, by using the plating bath described in the examples of Patent Document 3, although there may be a case where a silver-plated palladium copper alloy plating coating layer may be formed, even in such a case, When the palladium copper alloy plating coating layer was peeled from the metal substrate having the oxide film, the peelability was poor and cracking occurred. In addition, even when it is peeled off from the metal substrate and obtained as a foil, the warping is greatly curled; the alloy ratio is different between the base material side and the plating surface side, so that the color tone of the palladium copper alloy foil is different between the front and back sides; There are challenges.

Patent Document 4 discloses a palladium alloy plating solution containing a palladium complex and a copper salt and containing a neutral amino acid, and describes that a palladium copper alloy plating film having a uniform appearance of 60% by mass of palladium is obtained. (Example 7 of Patent Document 4).
However, according to the follow-up test by the present inventors, the palladium-copper alloy plating film obtained from the plating solution of Patent Document 4 is mostly red, and further, there are many irregularities and cracks in appearance, and it peels off from the substrate. In order to obtain as a foil, the flexibility was remarkably inferior.

Patent Document 5 discloses a palladium-copper alloy plating solution containing palladium sulfate, a complexing agent, and a copper salt. After forming a nickel plating layer as an intermediate layer on a porous stainless steel substrate, a palladium-copper alloy film was formed. A complex is described.
However, when the present inventors made additional trials using the plating solution of Patent Document 5, it was found that the obtained palladium-copper alloy plating film had many appearance irregularities and the color tone was brownish.

Thus, although the palladium copper alloy plating film (coating layer) is formed on the base material, and the electrolytic palladium copper alloy plating solution for that purpose is known per se, the palladium copper alloy formed by these known techniques In the case where the plating film is peeled off and used as a foil, there has been no case of examining whether a foil that can withstand practical use can be obtained (examination of the properties of the foil).
Specifically, by removing the palladium copper alloy plating film from the substrate, there are many problems in obtaining a palladium-copper alloy foil having a uniform silver appearance on both sides and no curling. A copper alloy plating solution is desired.

Japanese Patent No. 3316417 JP-A-6-340983 JP 2000-303199 A JP 2008-081765 A JP 2008-261045 A

The present invention has been made in view of the above-mentioned background art, and its problem is that the peelability from a metal substrate having an oxide film on the surface is good; after peeling from the metal substrate, it is flexible and warps (curls). Fewer defects such as pinholes and cracks; Palladium-copper alloy exfoliation with features such as uniform alloy composition in the foil thickness direction without annealing after plating; It is providing the electrolytic palladium copper alloy plating solution for foil formation.
At the same time, the problem of the present invention is to provide a method for producing a palladium-copper alloy release foil using such a plating solution, a palladium-copper alloy foil, or to add a plating solution by adding a palladium (II) ammine complex salt. Another object is to provide an aqueous solution for preparing a plating solution for preparation.

  As a result of intensive studies to solve the above problems, the present inventor has (A) palladium (II) ammine complex salt, (B) copper (II) salt, (C) pyrophosphate compound and / or tripolyphosphate compound. And (D) a plating solution containing a tetravalent selenium compound and (E) a pyridinesulfonic acid compound, (C) containing a pyrophosphoric acid compound and / or a tripolyphosphoric acid compound in a specific concentration range, and copper It has been found that the above-mentioned problems can be solved by setting the ratio of the molar concentration of (C) pyrophosphate compound and / or tripolyphosphate compound to a specific range, and the present invention has been completed.

That is, the present invention provides (A) palladium (II) ammine complex salt, (B) copper (II) salt, (C) pyrophosphate compound and / or tripolyphosphate compound, (D) tetravalent selenium compound, and ( E) containing a pyridine sulfonic acid compound,
The molar concentration of the compound belonging to (C) is 0.35 mol / L to 1.1 mol / L, and the value obtained by dividing the molar concentration of the compound belonging to (C) by the molar concentration of copper is 4.8 to 23. The electrolytic copper-copper alloy plating solution for forming a palladium-copper alloy release foil is characterized by having a pH of 2 or less and a pH of 7.5 or more and 9.5 or less.

  In addition, the present invention uses the above-described electrolytic palladium copper alloy plating solution for forming a palladium-copper alloy release foil to form a palladium-copper alloy plating film on a metal substrate having an oxide film on the surface. The present invention provides a method for producing a palladium-copper alloy release foil, characterized in that a palladium-copper alloy release foil is obtained by peeling a film from the metal substrate.

Further, the present invention provides a palladium-copper alloy foil having a thickness of 0.5 μm or more and 20 μm or less and an average ratio of palladium of 40% by mass or more and 80% by mass or less, wherein the ratio of palladium on one surface is X _A , when the ratio of the palladium on the other surface was X _B, | is to provide a palladium-copper alloy foil which is a ≦ 15 wt% _| X B _-X a.

Further, the present invention is an aqueous solution for preparing a plating solution for preparing the electrolytic palladium copper alloy plating solution for forming the above-mentioned palladium-copper alloy peeling foil by adding (A) palladium (II) ammine complex salt,
(B) a copper (II) salt, (C) a pyrophosphate compound and / or a tripolyphosphate compound, (D) a tetravalent selenium compound, and (E) a pyridinesulfonic acid compound,
The molar concentration of the compound belonging to (C) is 0.35 mol / L to 1.7 mol / L, and the value obtained by dividing the molar concentration of the compound belonging to (C) by the molar concentration of copper is 4.8 to 23. An aqueous solution for preparing a plating solution, which is 2 or less, is provided.

  According to the present invention, there is provided a palladium copper alloy foil having a good peelability from a metal substrate having an oxide film on the surface, a soft, low warpage, and a small difference in alloy ratio between the front and back, which has been difficult with a conventional plating solution. An electrolytic palladium copper alloy plating solution for forming can be provided.

  In addition, according to the method for producing a palladium-copper alloy release foil of the present invention, a palladium-copper alloy foil having a thickness of 0.5 μm or more and 20 μm or less, which was difficult by the conventional rolling method, can be stably formed with a high yield. .

  In addition, the palladium copper alloy foil of the present invention has few defects such as pinholes and cracks, improves the yield of products using the palladium copper alloy foil, and is a thin alloy foil that could not be realized by the conventional rolling method Can be provided at low cost, which is industrially useful.

It is an electron micrograph which shows the cross section of the palladium copper alloy peeling foil obtained in Example A10 (magnification 15,000 times). It is an electron micrograph which shows the cross section of the palladium copper alloy peeling foil obtained in Example B1. (Magnification 15,000 times) It is an electron micrograph of the palladium copper alloy peeling foil obtained in Example A10. (A) Photograph observed from the plating surface side (front surface) (500 times magnification) (b) Photograph observed from the substrate side (back surface) (500 magnifications) It is an electron micrograph of the palladium copper alloy release foil obtained in Example B1. (A) Photograph observed from the plating surface side (front surface) (500 times magnification) (b) Photograph observed from the substrate side (back surface) (500 magnifications) It is a figure which shows distribution of palladium and copper which analyzed the cross section of the palladium copper alloy peeling foil obtained in Example A10 using the energy dispersive X-ray analyzer. It is a figure which shows distribution of palladium and copper which analyzed the cross section of the palladium copper alloy peeling foil obtained in Example B1 using the energy dispersive X-ray analyzer. It is the figure which measured the polarization curve of the plating solution of Example A10. It is the figure which measured the polarization curve of the plating solution (conventional plating solution) of Example B1.

  Hereinafter, the present invention will be described. However, the present invention is not limited to the following embodiments, and can be arbitrarily modified and implemented.

[Electrolytic palladium copper alloy plating solution for forming palladium copper alloy release foil]
The electrolytic copper-copper alloy plating solution for forming a palladium-copper alloy release foil of the present invention comprises (A) palladium (II) ammine complex salt, (B) copper (II) salt, (C) pyrophosphate compound and / or tripolyphosphate compound, (D) A tetravalent selenium compound and (E) a pyridinesulfonic acid compound are contained. In the electrolytic palladium copper alloy plating solution of the present invention, the molar concentration of the compound belonging to (C) (hereinafter sometimes referred to as “Cp”) and the molar concentration of the compound belonging to (C) are divided by the molar concentration of copper. The value (hereinafter sometimes referred to as “P ratio”) and pH are within a specific range described later.
Moreover, the electrolytic palladium copper alloy plating solution of this invention may contain the other component mentioned later.

<(A) Palladium (II) Ammine Complex>
The electrolytic palladium copper alloy plating solution of the present invention must contain a palladium (II) ammine complex salt (a complex salt in which ammonia (NH ₃ ) is coordinated to palladium (Pd) ions). The palladium (II) ammine complex salt is used as a palladium source for the electrolytic palladium copper alloy plating solution of the present invention.
The palladium (II) ammine complex salt is not limited to one type, and two or more types can be used in combination.

Specific examples of the palladium (II) ammine complex salt include dichlorotetraammine palladium (II) ([Pd (NH ₃ ) ₄ ] Cl ₂ ), tetraammine palladium (II) sulfate ([Pd (NH ₃ ) ₄ ] SO ₄ ). , Tetraamminepalladium (II) nitrate ([Pd (NH ₃ ) ₄ ] (NO ₃ ) ₂ ), tetraammine palladium (II) sulfamate ([Pd (NH ₃ ) ₄ ] (NH ₂ SO ₃ ) ₂ ), tetraammine Palladium (II) methanesulfonate ([Pd (NH ₃ ) ₄ ] (CH ₃ SO ₃ ) ₂ ), tetraammine palladium (II) hydrochloride ([Pd (NH ₃ ) ₄ ] (OH) ₂ ), tetraammine Palladium (II) carbonate ([Pd (NH ₃ ) ₄ ] CO ₃ ), tetraammine palladium (II) acetate ([Pd (NH ₃ ) ₄ ] (CH ₃ COO) ₂ ), tetraammine palladium (II) oxalate ([Pd (NH ₃ ) ₄ ] C ₂ O ₄ ) and other palladium (II) tetraammine complexes (four ammonia (NH ₃ as ligands)) ) Palladium (II) ammine complex having a molecule); dichlorodiammine palladium (II) ([PdCl ₂ (NH ₃ ) ₂ ]), dinitrodiammine palladium (II) ([Pd (NO ₂ ) ₂ (NH ₃ ) ₂ ] ) And the like (palladium (II) ammine complex salts having two ammonia (NH ₃ ) molecules as ligands); hydrates thereof and the like.
These palladium (II) ammine complex salts easily exert the above-described effects of the present invention, and further have good electrolytic palladium copper alloy plating performance, ease of dissolution in a plating solution, availability, cost, etc. From the viewpoint of

  Of these, dichlorotetraamminepalladium (II) (also known as tetraamminepalladium (II) chloride), tetraamminepalladium (II) sulfate, dichlorodiammine palladium (II), dinitrodiammine palladium (II) Tetraamminepalladium (II) hydrochloride, tetraamminepalladium (II) carbonate, tetraamminepalladium (II) nitrate, tetraamminepalladium (II) acetate; these hydrates are particularly preferred.

  The content of the palladium (II) ammine complex salt in the electrolytic palladium copper alloy plating solution of the present invention (the total content when two or more types are used in combination) is not particularly limited. The metal palladium is preferably 1 g / L to 100 g / L, more preferably 2 g / L to 50 g / L, and particularly preferably 3 g / L to 30 g / L.

If the content of the palladium (II) ammine complex salt in the electrolytic palladium copper alloy plating solution is too small, it may be difficult to form an electrolytic palladium copper alloy film having a uniform color. That is, when the color and surroundings of the electrolytic palladium copper alloy plating film are visually observed, precipitation abnormalities such as burns and unevenness may be observed in the palladium copper alloy plating film.
Moreover, the peelability at the time of peeling the formed palladium-copper alloy film from a metal substrate may deteriorate. That is, the flexibility is poor, and it becomes an alloy plating film that easily breaks when peeled, and may not be used as a foil.

  On the other hand, if the content of the palladium (II) ammine complex salt in the electrolytic palladium copper alloy plating solution is too large, there is no particular problem as the performance of the electrolytic palladium copper alloy plating solution, but the content exceeds the above content. However, the performance of the palladium copper alloy foil obtained by peeling the palladium copper alloy film from the metal substrate is not improved. Further, the palladium (II) ammine complex salt is expensive and may be uneconomical.

<(B) Copper (II) salt>
The electrolytic palladium copper alloy plating solution of the present invention must contain a copper (II) salt. Copper (II) salt is used as a copper source for the electrolytic palladium copper alloy plating solution of the present invention.
The copper (II) salt is not limited to one type, and two or more types can be used in combination.

Specific examples of the copper (II) salt include copper sulfate (II) (CuSO ₄ ), copper chloride (II) (CuCl ₂ ), copper nitrate (II) (Cu (NO ₃ ) ₂ ), copper pyrophosphate (II ) (Cu ₂ P ₂ O ₇ ), copper (II) sulfamate (Cu (SO ₃ NH ₂ ) ₂ ), copper (II) methanesulfonate (Cu (CH ₃ SO ₃ ) ₂ ), copper (II) carbonate (CuCO ₃ ), copper hydroxide (II) (Cu (OH) ₂ ), copper formate (II) (Cu (HCOO) ₂ ), copper acetate (II) (Cu (CH ₃ COO) ₂ ), copper oxalate (II) (CuC ₂ O ₄ ); and their hydrates.
These copper (II) salts are easy to exert the effect of the present invention described above, and from the viewpoints of good electrolytic palladium copper alloy plating performance, ease of dissolution in plating solution, availability, etc. Is also preferable.

  Of these, copper sulfate (II), copper chloride (II), copper nitrate (II), copper pyrophosphate (II), copper acetate (II); these hydrates are particularly preferred from the above points. .

  The content of the copper (II) salt in the electrolytic palladium copper alloy plating solution of the present invention (the total content when two or more types are used in combination) is not particularly limited. The copper is preferably 0.3 g / L to 30 g / L, more preferably 0.5 g / L to 13 g / L, and particularly preferably 1 g / L to 10 g / L.

If the content of the copper (II) salt in the electrolytic palladium copper alloy plating solution is too small, it may be difficult to form an electrolytic palladium copper alloy film having a uniform color. That is, when the color and surroundings of the electrolytic palladium-copper alloy plating film are visually observed, an abnormal precipitation of palladium-copper alloy plating may be observed.
Moreover, the peelability at the time of peeling the formed palladium-copper alloy film from a metal substrate may deteriorate. That is, the flexibility is poor, and it becomes an alloy plating film that easily breaks when peeled, and may not be used as a foil.

  On the other hand, when the content of the copper (II) salt in the electrolytic palladium copper alloy plating solution is too large, the electrolytic palladium copper alloy plating film may become a reddish film. Moreover, even if the plating surface (front surface) of the foil obtained by peeling the film from the metal substrate is not reddish, the surface (back surface) on the substrate side may be reddish.

<(C) pyrophosphate compound, tripolyphosphate compound>
It is essential that the electrolytic palladium copper alloy plating solution of the present invention contains a pyrophosphate compound and / or a tripolyphosphate compound.
In this specification, “pyrophosphate compound” refers to pyrophosphate (H ₄ P ₂ O ₇ ) or a salt thereof, and “tripolyphosphate compound” refers to tripolyphosphate (H ₅ P ₃ O ₁₀ ) or a salt thereof.
The pyrophosphoric acid compound and the tripolyphosphoric acid compound are presumed to act as a complexing agent for the electrolytic palladium copper alloy plating solution of the present invention to enable formation of a palladium copper alloy plating film.

Specific examples of the pyrophosphate compound include sodium pyrophosphate, sodium hydrogen pyrophosphate, potassium pyrophosphate, potassium hydrogen pyrophosphate, ammonium pyrophosphate, ammonium hydrogen pyrophosphate, pyrophosphoric acid; hydrates thereof, and the like.
These pyrophosphate compounds are preferable from the viewpoints of easily exhibiting the effects of the present invention described above, and further, good electrolytic palladium copper alloy plating performance, ease of dissolution in a plating solution, availability, and the like. .

  Of these, sodium pyrophosphate, potassium pyrophosphate, ammonium pyrophosphate, pyrophosphoric acid; and hydrates thereof are particularly preferable from the above points.

  A pyrophosphoric acid compound is not limited to 1 type of use, It can also use 2 or more types together.

  Specific examples of the tripolyphosphate compound include sodium tripolyphosphate, potassium tripolyphosphate, ammonium tripolyphosphate, tripolyphosphate; hydrates thereof, and the like.

  Of these, sodium tripolyphosphate, potassium tripolyphosphate; hydrates thereof are particularly preferable from the above points.

  In addition, although potassium tripolyphosphate may contain hardly soluble potassium metaphosphate as an impurity, the thing which does not contain potassium metaphosphate is especially preferable.

  A tripolyphosphoric acid compound is not limited to 1 type of use, It can also use 2 or more types together.

The electrolytic palladium copper alloy plating solution of the present invention may contain only one or both of a pyrophosphate compound and a tripolyphosphate compound as (C), but may contain at least a tripolyphosphate compound. It is preferable to contain.
Furthermore, surprisingly, by using the pyrophosphate compound and the tripolyphosphate compound together, the palladium copper alloy plating film formed on the metal substrate using the electrolytic palladium copper alloy plating solution of the present invention is peeled off from the metal substrate. It is particularly preferable to contain both a pyrophosphate compound and a tripolyphosphate compound because the curl (warpage) of the palladium-copper alloy foil produced in this way can be made particularly small.
Further, even when only the tripolyphosphate compound is added to the plating solution, the pyrophosphate compound is generated as an impurity in the plating solution, so that the curl of the alloy foil can be particularly reduced.

When the pyrophosphate compound and the tripolyphosphate compound are used in combination, the ratio of the tripolyphosphate compound is preferably 0.01 mol or more, particularly 0.1 mol or more, with respect to 1 mol of the pyrophosphate compound. preferable. Moreover, it is preferable that a tripolyphosphoric acid compound is 5 mol or less with respect to 1 mol of pyrophosphoric acid compounds, and it is especially preferable that it is 2 mol or less.
When it is within the above range, it is particularly easy to reduce the curl of the alloy foil.

The content of the pyrophosphate compound and / or tripolyphosphate compound in the electrolytic palladium copper alloy plating solution of the present invention may be 0.35 mol / L or more and 1.1 mol / L or less when the molar concentration is Cp. It is essential. Cp is the total molar concentration of a plurality of pyrophosphate compounds / tripolyphosphate compounds (when using a combination of pyrophosphate compounds and tripolyphosphate compounds, all pyrophosphate compounds and all The total molar concentration of the tripolyphosphate compound).
By controlling the Cp range to the above range, the remarkable effects of the present invention can be achieved.

When the value of Cp in the electrolytic palladium copper alloy plating solution of the present invention is smaller than 0.35 mol / L, it is difficult to form an electrolytic palladium copper alloy film having a uniform color tone. In other words, abnormal deposition of palladium copper alloy plating such as burns and unevenness may be observed.
Moreover, even when such precipitation abnormality is not visually recognized, the metal of the palladium copper alloy foil produced by peeling the palladium copper alloy film obtained by using the electrolytic palladium copper alloy plating solution of the present invention from the substrate. In some cases, the ratio of palladium on the surface that was on the substrate side is reduced, and a reddish appearance is likely to occur.
Furthermore, the difference between the palladium ratio on the plating solution side (front surface) and the palladium ratio on the metal substrate side (back surface) increases, resulting in a silvery appearance on the surface and a reddish appearance on the back surface. This is not preferable because the appearance of the foil differs between the front and back surfaces. Thus, when the difference in palladium ratio between the front and back becomes large, curling (warping) of the foil is likely to occur.

On the other hand, when the value of Cp in the electrolytic palladium copper alloy plating solution is larger than 1.1 mol / L, the electrolytic palladium copper alloy plating film may be burned or uneven.
In addition, defects such as roughness, unevenness, and cracks may easily occur in the plating solution.
Furthermore, the curl (warpage) of the palladium copper alloy foil produced by peeling the palladium copper alloy film obtained by using the electrolytic palladium copper alloy plating solution of the present invention from the substrate may be increased.

  As shown in the examples (Examples B1 to B5, B7 to B8) described later, even if a conventional plating solution having a Cp of about 0.3 mol / L is only coated with a palladium-copper alloy plating layer, it is desirable. In the case of producing a palladium-copper alloy foil by uniformly plating an alloy substrate on a metal substrate having an oxide film and producing a palladium-copper alloy foil by separating the metal substrate as in the present invention, However, the foil curled and could not overcome the problem.

  In order to facilitate the above effects, Cp is preferably 0.45 mol / L or more, particularly preferably 0.55 mol / L or more. Cp is preferably 0.9 mol / L or less, and particularly preferably 0.8 mol / L or less.

In the electrolytic palladium copper alloy plating solution of the present invention, the value (P ratio) obtained by dividing the molar concentration Cp of the (C) pyrophosphate compound and / or tripolyphosphate compound by the molar concentration of copper is within a specific range. Specifically, the P ratio is 4.8 or more and 23.2 or less.
By controlling the P ratio within the above range, the remarkable effects of the present invention are exhibited.

When the P ratio in the electrolytic palladium copper alloy plating solution of the present invention is less than 4.8, the palladium copper alloy film obtained using the electrolytic palladium copper alloy plating solution of the present invention is peeled off from the metal substrate. The difference in the palladium ratio between the front and back sides of the produced palladium-copper alloy foil may increase.
Moreover, the curl (warpage) of the alloy foil may increase.

On the other hand, when the P ratio is larger than 23.2, the electrolytic palladium copper alloy plating film may have burns or unevenness.
Moreover, the curl (warpage) of the alloy foil manufactured by peeling the palladium copper alloy film obtained by using the electrolytic palladium copper alloy plating solution of the present invention from the metal substrate may be increased.

  In order to facilitate the above effects, the P ratio is preferably 6 or more, particularly preferably 8 or more. Moreover, it is preferable that P ratio is 20 or less, and it is especially preferable that it is 17 or less.

  By controlling both Cp and P ratio within the above range, it is possible to produce a palladium copper alloy plating film suitable for producing a palladium copper alloy foil, which was difficult with a conventional plating solution. That is, it is possible to obtain an electrolytic palladium-copper alloy foil with little difference in palladium ratio between the front and back surfaces and little curling.

<(D) Tetravalent selenium compound>
The electrolytic palladium copper alloy plating solution of the present invention must contain a tetravalent selenium compound (Se (IV)). The tetravalent selenium compound is presumed to act as a potential adjusting agent for the electrolytic palladium copper alloy plating solution of the present invention. It is considered that palladium and copper can be stably alloyed with a tetravalent selenium compound even on a metal substrate having an oxide film on the surface.
The tetravalent selenium compound is not limited to one type, and two or more types can be used in combination.

Specific examples of tetravalent selenium compounds include selenious acid (H ₂ SeO ₃ ), selenium dioxide (SeO ₂ ), sodium selenite (Na ₂ SeO ₃ ), potassium selenite (K ₂ SeO ₃ ) and the like. Is mentioned.
These tetravalent selenium compounds easily exert the effects of the present invention described above, and from the viewpoints of good electrolytic palladium copper alloy plating performance, ease of dissolution in plating solution, availability, etc. Is also preferable.

  The content of the tetravalent selenium compound in the electrolytic palladium copper alloy plating solution of the present invention (the total content when two or more types are used in combination) is not particularly limited, and the selenium with respect to the entire electrolytic palladium copper alloy plating solution. As 0.001 g / L to 1 g / L, preferably 0.005 g / L to 0.5 g / L, more preferably 0.01 g / L to 0.1 g / L. Particularly preferred.

  If the content of the tetravalent selenium compound in the electrolytic palladium copper alloy plating solution is too small, palladium and copper may not be alloyed and segregate in some cases.

  On the other hand, when the content of the tetravalent selenium compound in the electrolytic palladium copper alloy plating solution is too large, precipitation abnormalities such as burns and unevenness may be observed in the palladium copper alloy plating film. Moreover, the peelability of the palladium copper alloy foil obtained by peeling the film from the metal substrate may deteriorate.

The hexavalent selenium compound produced by oxidation of the tetravalent selenium compound does not exhibit the effects of the present invention, but does not adversely affect the hexavalent selenium compound, and therefore may be present in the plating solution as an electrolytic byproduct.
On the other hand, since a bivalent selenium compound inhibits the effect of the present invention, it is not preferable to exist in the plating solution of the present invention.

<(E) Pyridinesulfonic acid compound>
It is essential that the electrolytic palladium copper alloy plating solution of the present invention contains a pyridinesulfonic acid compound (a compound having a pyridine (C ₅ H ₅ N) skeleton and a sulfo group (—SO ₃ H)). The pyridinesulfonic acid compound is presumed to act as a crystal adjusting agent for the electrolytic palladium copper alloy plating solution of the present invention.
The pyridinesulfonic acid compound is not limited to one type of use, and two or more types can be used in combination.

Specific examples of the pyridinesulfonic acid compound include pyridine-3-sulfonic acid, pyridine-2-sulfonic acid, pyridine-4-sulfonic acid, sodium pyridine-3-sulfonate, sodium pyridine-2-sulfonate, and pyridine-4. -Sodium sulfonate, potassium pyridine-3-sulfonate, potassium pyridine-2-sulfonate, potassium pyridine-4-sulfonate, ammonium pyridine-3-sulfonate, ammonium pyridine-2-sulfonate, pyridine-4-sulfone Ammonium acid; these hydrates are included.
These pyridinesulfonic acid compounds are easy to exert the effects of the present invention described above, and further, from the viewpoints of good electrolytic palladium copper alloy plating performance, ease of dissolution in plating solution, availability, cost, etc. Is also preferable.

  Among these, from the above points, pyridine-3-sulfonic acid, sodium pyridine-3-sulfonate, potassium pyridine-3-sulfonate, ammonium pyridine-3-sulfonate; hydrates thereof are particularly preferable. .

  The content of the pyridine sulfonic acid compound in the electrolytic palladium copper alloy plating solution of the present invention (the total content when two or more are used in combination) is not particularly limited. The acid is preferably 0.1 g / L to 100 g / L, more preferably 0.5 g / L to 50 g / L, and particularly preferably 1 g / L to 20 g / L.

  If the content of the pyridinesulfonic acid compound in the electrolytic palladium copper alloy plating solution is too small, it may be difficult to form an electrolytic palladium copper alloy film having a uniform color. That is, there may be a case where a deposition abnormality such as burn or unevenness is observed in the electrolytic palladium copper alloy plating film. Moreover, the peelability at the time of peeling the formed palladium-copper alloy film from a metal substrate may deteriorate. That is, the flexibility is poor, and it becomes an alloy plating film that easily breaks when peeled, and may not be used as a foil.

  On the other hand, when the content of the pyridine sulfonic acid compound in the electrolytic palladium copper alloy plating solution is too large, the curl (warpage) of the palladium copper alloy foil obtained by peeling the film from the metal substrate may increase.

<PH>
The pH of the electrolytic palladium copper alloy plating solution of the present invention is essential to be 7.5 or more and 9.5 or less.
When the pH is less than 7.5, precipitation abnormalities such as burns and unevenness may be observed in the palladium copper alloy plating film. Moreover, the peelability at the time of peeling off the formed palladium-copper alloy film from the metal substrate may be deteriorated (that is, the flexibility is poor and it is easy to break when peeling off).
On the other hand, when the pH is higher than 9.5, a residue tends to adhere when the plating film is peeled off from the metal substrate, and the curl (warpage) of the alloy foil tends to increase.

<Other ingredients>
In addition to the above components (A) to (E), the electrolytic palladium copper alloy plating solution of the present invention may contain other components as needed. Specific examples of other components include an auxiliary conductive salt for improving the conductivity of the plating solution, a pH buffer for keeping the plating pH constant, and a surface activity for improving the degassing of the plating solution. Agents and the like.

<< Auxiliary conductive salt >>
As the auxiliary conductive salt that can be contained as required in the electrolytic palladium copper alloy plating solution of the present invention, known ones can be used. Specific examples include chloride salts, sulfate salts, nitrate salts, nitrite salts, phosphate salts, acetate salts, carbonate salts, and the like.
These are not limited to one type of use, and two or more types can be used in combination.

The content of the conductive salt used in the electrolytic palladium copper alloy plating solution of the present invention is not particularly limited, but is preferably 0.01 to 200 g / L, preferably 0.1 to 150 g / L. L is more preferable, and 1 to 100 g / L is particularly preferable.
If the content of the auxiliary conductive salt in the plating solution is too small, the conductivity of the plating solution may be poor and the voltage during plating may be high. On the other hand, if the content is too large, the palladium copper alloy plating film may be burned or uneven. Precipitation abnormalities may be observed.

<< pH buffer >>
The pH buffering agent contained as necessary in the electrolytic palladium copper alloy plating solution of the present invention is not particularly limited as long as it is a known pH buffering agent. Preferable examples include boric acid, tetraboric acid, citric acid, malic acid, succinic acid, malonic acid, maleic acid, fumaric acid, glycine; salts of these acids (potassium salt, sodium salt, ammonium salt) and the like. .
These may be used alone or in combination of two or more.

The content of the pH buffering agent in the electrolytic palladium copper alloy plating solution of the present invention (the total content when two or more types are used in combination) is not particularly limited, but is 0.1 g / L to 100 g based on the entire plating solution. / L is preferable, and 1 g / L to 50 g / L is particularly preferable.
If the content of the pH buffering agent in the 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.

<< Surfactant >>
The electrolytic palladium copper alloy plating solution of the present invention may contain a surfactant as necessary. As the surfactant, known ones can be used as appropriate, and for example, nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants and the like are used.

  Specific examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester and the like.

  Specific examples of the anionic surfactant include alkyl sulfate ester salts, alkyl sulfosuccinates, β-naphthalene sulfonic acid formalin condensates and the like.

  Specific examples of the cationic surfactant include lauryl ammonium salt.

  Specific examples of the amphoteric surfactant include lauryl sulfobetaine.

  Surfactant may be used individually by 1 type, and 2 or more types may be mixed and used for it. Two or more surfactants may be used in combination across the system.

  The content of the surfactant used in the electrolytic palladium copper alloy plating solution of the present invention is not particularly limited, but is preferably 0.001 to 10 g / L, preferably 0.01 to 5 g. / L is more preferable, and 0.05 to 1 g / L is particularly preferable.

The electrolytic palladium copper alloy plating solution of the present invention is particularly suitable for applications in which a palladium copper alloy plating film is formed on a metal substrate having an oxide film on the surface and then peeled off to obtain a palladium copper alloy release foil. "Electrolytic palladium copper alloy plating solution for forming copper alloy release foil".
As mentioned above, when the palladium copper alloy film formed by plating is peeled off and used as a palladium copper alloy foil, even if it has sufficient performance as a film, when used as a thin foil, peelability, Whether it can withstand practical use in terms of ease of curling, uniformity of the alloy ratio on the front and back, etc. is a problem, but there has been no example of examining the composition of the palladium-copper alloy plating solution from such a viewpoint.
The electrolytic copper / copper alloy plating solution for forming a palladium / copper alloy release foil according to the present invention has a molar concentration (Cp) of the component (C); a value obtained by dividing the molar concentration of the component (C) by the molar concentration of copper (P ratio). ); By adjusting the pH and the like of the solution, the physical properties that are important when used as the above-described foil are improved.

[Method for producing palladium-copper alloy release foil]
The present invention also relates to a method for producing a palladium-copper alloy release foil.
The method for producing a palladium-copper alloy release foil of the present invention uses the above-described electrolytic palladium-copper alloy plating solution for forming a palladium-copper alloy release foil to form a palladium-copper alloy plating film on a metal substrate having an oxide film on the surface. Then, the palladium-copper alloy plating film is peeled from the metal substrate to obtain a palladium-copper alloy release foil.

<Metal base>
The metal substrate used in the production method of the palladium-copper alloy release foil of the present invention (on which the palladium-copper alloy plating film that forms the release foil is formed by the palladium-copper alloy plating solution of the present invention) It is a metal having an oxide film.
Examples of the metal substrate having an oxide film on the surface include stainless steel, titanium, aluminum, chromium; plating surfaces of these metals, and the like. Among them, stainless steel is particularly preferable from the viewpoints of good peeling performance of the electrolytic palladium copper alloy plating film, availability, low cost, and the like.
A substrate such as copper or brass that does not have a uniform oxide film on the surface is not preferable because the adhesion of the plating film is strong and it becomes difficult to produce a release foil.

<Average ratio of palladium>
It is preferable that the average ratio of palladium of the palladium copper alloy release foil manufactured by the method for manufacturing the palladium copper alloy release foil of the present invention is 40% by mass or more and 80% by mass or less.

<Difference in palladium ratio between front and back>
In the palladium copper alloy release foil manufactured by the method for manufacturing a palladium copper alloy release foil of the present invention, the ratio of palladium on the surface that was on the metal substrate side is X ₁ , and the ratio of palladium on the surface that is on the plating solution side is X _When X is ₂ , it is preferable that | X ₂ −X ₁ | ≦ 15 mass%.

<Range of front and back palladium ratio>
In the palladium copper alloy release foil manufactured by the method for manufacturing the palladium copper alloy release foil of the present invention, the palladium ratios X ₁ and X _{2 on} each surface described above are both 40% by mass or more and 80% by mass or less (40% by mass). ≦ X ₁ ≦ 80 mass% and 40 mass% ≦ X ₂ ≦ 80 mass%).

<Cathode current density>
The production method of the palladium-copper alloy release foil of the present invention is such that when the above-described palladium-copper alloy plating solution of the present invention is used for plating on a metal substrate having an oxide film on the surface, the cathode current density is 0.5 A / in dm ² or more 10A / dm ² or less in the range and performs plating process.
When the cathode current density is not less than the above lower limit, the plating deposition rate is sufficient, and the productivity is improved. If it is less than the above lower limit, the plating time may be long, or the foil may be reddish.
On the other hand, when the cathode current density is not more than the above upper limit, the appearance of the deposited film is improved. When larger than the said upper limit, the softness | flexibility of foil may become scarce or the curl (warp) of foil may become large.

In particular, when performing by rack type plating, the cathode current density is more preferably 0.5 to 3.0 A / dm ² .
Moreover, in the case of conditions with a high liquid stirring speed such as submerged jet plating, 0.7 to 10 A / dm ² is more preferable.

<Thickness of foil>
In the method for producing a palladium-copper alloy release foil of the present invention, a palladium-copper alloy plating film is formed so as to be 0.5 μm or more and 20 μm or less, and then the palladium-copper alloy plating film is formed from the metal substrate.
If it manufactures so that the thickness of foil may become more than the said minimum, the intensity | strength of the foil which can endure handling is obtained. When it is less than the above lower limit, the strength of the foil may be insufficient and may be broken.
On the other hand, if it manufactures so that the thickness of foil may be below the said upper limit, productivity will improve and manufacturing cost can be restrained low. When it is thicker than the above upper limit, the manufacturing cost of the foil may increase or the flexibility of the foil may be poor.

<Bath temperature>
The bath temperature (the temperature of the plating solution) for plating by the method for producing the palladium-copper alloy release foil of the present invention is not particularly limited, but is preferably 20 to 90 ° C.
When the bath temperature is equal to or higher than the above lower limit, the appearance of the plated alloy foil is improved. Further, when the amount is not more than the above upper limit, the plating solution is hardly decomposed.
The bath temperature is more preferably 40 to 80 ° C, particularly preferably 50 to 70 ° C.

<Stirring and peristalsis>
In the method for producing the palladium-copper alloy release foil of the present invention, the step of performing the palladium-copper alloy plating process may be performed without stirring, which is a general stirring condition for plating, or may be performed while stirring. When stirring is performed, electrolytic palladium copper alloy plating can be performed on the metal substrate having the oxide film while performing mechanical stirring, air stirring, submerged jet stirring, and the like.
Moreover, when plating by a rack system, it is preferable to perform a plating process while shaking a base | substrate.

<Anode>
The anode used in the step of performing the palladium-copper alloy plating treatment may be an insoluble anode such as titanium, titanium platinum, iridium oxide or the like, and a palladium anode and a copper anode may be used as the soluble anode. A stainless steel anode is not preferable because components such as iron, nickel and chromium are eluted in the plating solution.
In view of easy maintenance, it is particularly preferable to use an insoluble anode.
When using a palladium anode and a copper anode as soluble anodes, calculate the mass ratio of the anode to be equal to the desired alloy ratio of the palladium copper alloy release foil, and immerse the palladium anode and the copper anode in the plating solution, respectively. Is preferred.

<Shape of metal base>
In the method for producing a palladium-copper alloy release foil of the present invention, the shape of the metal substrate serving as the cathode in the step of performing the palladium-copper alloy plating process is not particularly limited. For example, a flat substrate such as a plate shape or a belt shape may be used, or a drum-shaped curved substrate may be used.

<Surface roughness of metal substrate>
The surface roughness of the metal substrate is not particularly limited, but Sa (arithmetic average roughness) is preferably less than 0.5 μm, particularly preferably less than 0.2 μm, from the viewpoint of peelability.
When Sa is larger than 0.5 μm, the peelability of the electrolytic palladium copper alloy foil may deteriorate.

<Plating pretreatment>
As a pretreatment for the plating treatment, general metal plating pretreatment such as degreasing treatment and neutralizing treatment after degreasing can be performed on the metal substrate.
Moreover, in order to improve peelability, surface polishing treatments such as buffing, chemical polishing, and electrolytic polishing can be performed to reduce the surface roughness of the metal substrate.

<Under plating treatment>
In the method for producing a palladium-copper alloy release foil of the present invention, a palladium-copper alloy plating may be directly applied on the pretreated metal substrate, or a thin electrolytic palladium plating film is formed on the metal substrate as a base. Then, a palladium copper alloy plating film may be formed.
As in the case of forming a general palladium copper alloy plating film, it is an object of the present invention (good palladium copper) to perform a base plating treatment that can provide adhesion even on a metal substrate having an oxide film. This may be contrary to the formation of an alloy release foil.

When an electrolytic palladium plating film is formed as a base of the palladium copper alloy plating film, a known electrolytic palladium plating solution can be used. The underlying electrolytic palladium plating film is preferably formed so as to be 10% or less of the desired palladium copper alloy plating film thickness, and particularly preferably formed so as to be 5% or less.
By doing in this way, the peelability from the metal base | substrate which has an oxide film can be improved further, without impairing the characteristic of electrolytic palladium copper alloy peeling foil.
If the underlying electrolytic palladium plating film is formed to be thicker than 10%, the peelability is improved, but the curl (warpage) of the foil may be increased.

<Peeling method>
In the method for producing the palladium-copper alloy release foil of the present invention, when the palladium-copper alloy plating film formed on the metal substrate is peeled from the metal substrate, it is preferably performed by a mechanical peeling method.
For example, it is preferable to make a notch reaching the substrate from the plating layer with a cutter, a wire saw, stamping or the like, and sandwich the plating layer directly to separate, or peel the foil from the metal substrate by water flow or underwater ultrasonic treatment. When the substrate is a rotating drum, a method of peeling only the foil by pressing with a known peeling belt, roller or the like is preferable.

[Palladium copper alloy foil]
The present invention also relates to a palladium copper alloy foil.
The palladium copper alloy foil of the present invention has a thickness of 0.5 μm or more and 20 μm or less, an average ratio of palladium of 40% by mass or more and 80% by mass or less, and the ratio of palladium on one surface is X _A , | X _B -X _A | ≦ 15 mass%, where X _B is the ratio of palladium on the surface.
The palladium copper alloy foil of the present invention has a small difference in palladium ratio between the front and back sides, has a silver appearance on both the front and back sides, is excellent in various properties (such as flexibility) as a foil, and is practically usable. Moreover, the palladium copper alloy foil of the present invention usually contains selenium in the foil.

When an electrolytic plating method is used to obtain a palladium copper alloy film on a metal substrate and the palladium copper alloy foil is peeled off to obtain a palladium copper alloy foil, there is no problem in appearance as a film when a conventional plating solution is used. However, when the film is peeled to form a foil, the foil may have a large difference in the ratio between the front and back surfaces (see Examples B1, B3-B4, B7-B8 in Examples below). This is an unexpected finding obtained for the first time by the present inventors.
As described in the above section [Method for producing palladium-copper alloy release foil], a palladium-copper alloy plating film on a metal substrate using the “electrolytic palladium-copper alloy plating solution for forming a palladium-copper alloy release foil” of the present invention. The palladium-copper alloy plating film is peeled off to obtain a palladium-copper alloy foil (palladium-copper-alloy foil of the present invention) with a small difference in the palladium ratio between the front and back surfaces. It is only an example of the method for obtaining this palladium copper alloy foil, and the palladium copper alloy foil manufactured by other methods is not outside the scope of the “palladium copper alloy foil of the present invention”.

<Thickness>
The palladium copper alloy foil of the present invention has a thickness of 0.5 μm or more and 20 μm or less.
When the thickness of the foil is not less than the above lower limit, the strength of the foil that can withstand handling can be obtained. If it is less than the above lower limit, it may be easily broken.
On the other hand, when the thickness of the foil is not more than the above upper limit, the production cost can be kept low. If it is thicker than the above upper limit, the cost of the foil may increase or the flexibility of the foil may be poor.

<Average ratio of palladium>
The palladium copper alloy foil of the present invention has an average palladium ratio of 40% by mass to 80% by mass.
Here, the “average ratio” is an average of the palladium content ratio in the entire palladium-copper alloy-plated foil, and is measured by the method described in Examples below. That is, the average ratio of palladium in the thickness direction.
The average ratio of palladium is preferably 45% by mass or more, and particularly preferably 50% by mass or more. Moreover, it is preferable that it is 75 mass% or less, and it is especially preferable that it is 70 mass% or less.

It is preferable that the average ratio of palladium is equal to or more than the lower limit because a foil having a silver appearance is obtained. When it is less than the above lower limit, it may have a reddish appearance.
On the other hand, when the average ratio of palladium is not more than the above upper limit, a flexible foil is preferable. When larger than the said upper limit, a softness | flexibility may worsen.

(A) The content ratio (molar ratio) of the palladium (II) ammine complex salt and the (B) copper (II) salt should be about (A) :( B) = 1: 0.3 to 1: 1.8. Therefore, the average ratio of palladium can be easily adjusted to the above range.
Moreover, it is easy to make the average ratio of palladium into the said range by making pH into 7.5 or more and 9.5 or less.

<Difference in palladium ratio between front and back>
Palladium copper alloy foil of the present invention, the proportion of palladium on one side X _A, the ratio of the palladium on the other side in the case of the X _B, | a ≦ 15 wt% _| X B _-X A.
Incidentally, the case of producing a palladium-copper alloy foil of the present invention by the method described in the section [Method of Manufacturing palladium copper alloy peeling foil], X _A ratio of palladium surface (back surface) of a metal base body ( X ₁ ) and X _B are the ratio (X ₂ ) of palladium on the surface (surface) that was on the plating solution side.
When | X _B −X _A | ≦ 15% by mass, the difference in appearance between the front and back surfaces is small, and the curling (warping) of the foil hardly occurs. When | X _B -X _A | is larger than 15% by mass, the appearance may be different between the front and back sides, and the curl (warpage) of the foil may be increased.
It is preferable that | X _B -X _A | ≦ 13 mass%, and it is particularly preferable that | X _B −X _A | ≦ 10 mass%.

  Using the electrolytic palladium copper alloy plating solution for forming a palladium-copper alloy release foil of the present invention in which Cp, P ratio, and pH are adjusted to the specific range, described in the section [Method for producing palladium-copper alloy release foil]. By using this method, it is easy to produce such a radium copper alloy foil with a small difference in palladium ratio between the front and back sides.

<Range of front and back palladium ratio>
In the palladium copper alloy foil of the present invention, the above-described front and back palladium ratios X _A and X _B are both 40% by mass or more and 80% by mass or less (40% by mass ≦ X _A ≦ 80% by mass and 40% by mass ≦ X _B ≦ 80 mass%) is preferred.
It is preferable that X _A and X _B be equal to or more than the lower limit because a palladium-copper alloy foil having a silver appearance can be obtained. If it is less than the above lower limit, a reddish foil may be obtained.
On the other hand, it is preferable that X _A and X _B are not more than the above upper limit because a flexible foil is obtained. If it is larger than the above upper limit, the flexibility of the foil may not be obtained or the curl (warp) of the foil may be increased.

<Selenium>
The palladium copper alloy foil of the present invention usually contains selenium in the foil. The content of selenium is preferably 0.01% by mass or more, particularly preferably 0.1% by mass or more, based on the palladium copper alloy foil, because a flexible foil is easily obtained. Moreover, it is preferable that it is 2 mass% or less, and it is especially preferable that it is 1 mass% or less.
If the selenium content is less than the above lower limit, palladium and copper may segregate, resulting in insufficient alloying.
On the other hand, when the content of selenium is larger than the above upper limit, the appearance of the foil may be blackish or the flexibility of the foil may be insufficient.
The selenium content is measured by the method described in the examples below.

<Flexibility>
The palladium copper alloy foil of the present invention can be bent 180 degrees into a U shape along a stainless steel round bar having an outer diameter of 5 mm. Even after bending, the foil does not break and is excellent in flexibility.

[Plating solution aqueous solution]
Among the components of the electrolytic palladium-copper alloy plating solution of the present invention described in the above section [Electrolytic palladium-copper alloy plating solution for forming a palladium-copper alloy release foil], (A) palladium (II) ammine complex salt is a precious metal (palladium). ) Is extremely expensive, and it may be uneconomical to store for a long time in the state of being contained in the plating solution.
In addition, when (C) pyrophosphate compound and / or tripolyphosphate compound is dissolved in water and (A) palladium (II) ammine complex salt is added and stored at room temperature for a long time, pyrophosphate and / or tripolyphosphate and palladium ammine complex salt are mixed. Salt may salt out.
For this reason, the electrolytic palladium-copper alloy plating solution of the present invention is stored as “Aqueous solution for preparing an electrolytic palladium-copper alloy plating solution containing main components other than (A) palladium (II) ammine complex salt”. When performing, it is also preferable that the user of the plating solution separately uses (A) palladium (II) ammine complex salt.

That is, this invention relates also to the aqueous solution for plating solution preparation for preparing the said electrolytic palladium copper alloy plating solution for palladium-copper alloy peeling foil formation by adding (A) palladium (II) ammine complex salt.
The aqueous solution for preparing a plating solution of the present invention comprises (B) a copper (II) salt, (C) a pyrophosphate compound and / or a tripolyphosphate compound, (D) a tetravalent selenium compound, (E) a pyridinesulfonic acid compound (ie In addition, among the components of the electrolytic palladium-copper alloy plating solution of the present invention described in the above section [Electrolytic palladium-copper alloy plating solution for forming a palladium-copper alloy peeling foil], contains (other than (A)).

  When preparing an electrolytic palladium-copper alloy plating solution for forming a palladium-copper alloy release foil by adding (A) palladium (II) ammine complex salt to the aqueous solution for preparing a plating solution of the present invention, (A) palladium (II) Ammine complex salt may be added directly (as a solid), or (A) palladium (II) ammine complex salt may be dissolved in water to form an aqueous solution, and the aqueous solutions may be mixed.

When mixing aqueous solutions, the amount of the solution is increased by dilution, so the upper limit of the molar concentration (Cp) of the compound belonging to (C) pyrophosphoric acid compound and / or tripolyphosphoric acid in the aqueous solution for plating solution preparation of the present invention is The concentration is preferably higher than that of the electrolytic palladium copper alloy plating solution of the invention.
Specifically, Cp of the aqueous solution for preparing a plating solution of the present invention is 0.35 mol / L or more and 1.7 mol / L or less.

  The value (P ratio) obtained by dividing the molar concentration of the compound belonging to (C) in the aqueous solution for preparing a plating solution of the present invention by the molar concentration of copper is 4.8, as in the case of the electrolytic palladium copper alloy plating solution of the present invention. It is 23.2 or less.

  The pH of the aqueous solution for preparing a plating solution of the present invention is preferably 7.5 or higher, and particularly preferably 8.0 or higher. Moreover, it is preferable that it is 10.0 or less, and it is especially preferable that it is 9.5 or less.

  By adding (A) palladium (II) ammine complex salt to the aqueous solution for preparing a plating solution of the present invention and adjusting the pH to 7.5 or more and 9.5 or less as necessary, the electrolytic palladium of the present invention described above is prepared. A copper alloy plating solution can be prepared.

  The action and principle of obtaining a palladium copper alloy foil with excellent performance by the electrolytic palladium copper alloy plating solution for forming the palladium copper alloy release foil of the present invention in which the Cp, P ratio and pH are adjusted to the specific ranges are not clear. However, the following can be considered. However, this invention is not necessarily limited to the range of the following effects.

  The electrolytic palladium copper alloy plating solution of the present invention is considered to improve the uniformity of the alloy ratio in the film thickness direction due to the specific polarization characteristics. This is presumably because the polarization curve hardly changes even when the cathode potential changes from the initial stage of plating (potential of the metal substrate having an oxide film) to the time during plating (potential of the palladium copper alloy plating film).

  As shown in the examples described later, in the conventional plating solution, on the metal substrate having an oxide film, the polarization curve shifts compared to the case of brass or copper, whereas the electrolytic palladium copper alloy plating of the present invention. The liquid has a characteristic that the polarization curves are almost the same regardless of the base metal species. Therefore, even if the base metal changes from a metal substrate having an oxide film to a palladium copper alloy plating film during plating, the alloy ratio does not change, and it is considered that the uniformity in the film thickness direction is easily maintained.

  Hereinafter, the present invention will be described more specifically with reference to examples and the like. However, the present invention is not limited to these examples as long as the gist thereof is not exceeded.

Examples A1-16, Examples B1-19
<Formation of electrolytic palladium copper alloy plating film>
Using a 50 mm × 70 mm × 0.1 mmt stainless steel plate (SUS304, manufactured by Nilaco Corporation) as a test piece, plating was performed on the test piece in the steps shown in Table 1.
The electrolytic palladium copper alloy plating film was formed using 1 L of an electrolytic plating solution having a bath composition shown in Tables 2 to 5. As potassium tripolyphosphate, “KTP” (manufactured by Nippon Chemical Industry Co., Ltd.) was used. Pyrophosphate used was “diphosphate” (manufactured by Junsei Chemical Co., Ltd., purity 93%). The other components used reagent grade.
The pH was adjusted with potassium hydroxide or sulfuric acid unless otherwise specified. Plating was performed at a bath temperature of 50 ° C. and a current density of 1 A / dm ² for 30 minutes so that the cross-sectional film thickness was 5 to 8 μm. Two platinum-coated titanium meshes were used as the anode, and were placed facing the cathode. While stirring the plating solution at 250 rpm with a stirrer, the cathode was reciprocally swung in a direction parallel to the anode at about 6 m / min during plating.

In Tables 2 to 5, the content of the compound described in the column of “Palladium (II) Ammine Complex” and the column of “Other Palladium (II) Salt” is the content as palladium (Pd). The amount (g / L) is indicated (106.4 g / mol). Similarly, content of the compound described in the column of "copper (II) salt" shows content (g / L) as copper (Cu) (63.55 g / mol). The content of the compound described in the column of “Se (IV)” indicates the content (g / L) as tetravalent selenium.
On the other hand, the content of the compound described in the other column indicates the content (g / L) as the compound (for example, “potassium pyrophosphate” is 330.34 g / mol, “sodium pyrophosphate” "Decahydrate" is 446.05 g / mol).

<Preparation of palladium-copper alloy release foil>
After the test piece on which the electrolytic palladium copper alloy plating film was formed was dried, the test piece was cut to be 40 mm × 60 mm × 0.1 mmt. The test piece after cutting was put into a 500 mL tall beaker, and running water was vigorously applied to peel off the electrolytic palladium copper alloy plating film.

<Evaluation of peelability>
The following three points were evaluated as follows: flexibility of the obtained palladium-copper alloy release foil, curl of the foil, and whether the residue was not attached to the surface of the stainless steel substrate after peeling.

<< Foil flexibility >>
After drying the peeled palladium-copper-alloy foil as described above in an oven at 80 ° C., the surface on the base (stainless steel base) side of the foil is bent 180 degrees into a U-shape along a stainless steel round bar with an outer diameter of 5 mm. It was. The case where it was not fragmented after bending was indicated as “◯”, and the case where it was fragmented into two or more was indicated as “x”.

<< foil curl (warp) >>
The dried foil was placed on a horizontal table, and the curl height of the four corners was measured with a ruler. “◎” if the curl height of all four corners is within 5 mm, “◯” if the curl height of all four corners is within 10 mm, or if the curl height of any corner is 10 mm or more, or if the foil is When it was rounded into a cylindrical shape, it was marked “x”.

<< Substrate surface residue after peeling >>
When the residue could not be visually confirmed on the surface of the test piece (stainless steel) after peeling, “◯” was given, and when the foil residue was visually attached, “x” was given.

<Evaluation of foil appearance>
The uneven appearance and color of the obtained palladium-copper alloy release foil were visually evaluated. Both the front surface side (plated surface side) and the back surface side (stainless steel substrate side) were evaluated.

<< Appearance unevenness >>
When the foil surface had no unevenness and a semi-glossy or glossy and uniform appearance, “◯” was indicated. When the surface of the foil had unevenness and unevenness, “X” was indicated.

<< Appearance color >>
The color of the foil was visually evaluated.

<Evaluation of eutectoid ratio>
The ratio (eutectoid ratio) of palladium in the obtained palladium-copper alloy release foil was evaluated.

<< Average eutectoid ratio >>
The mass of the obtained palladium-copper alloy release foil (about 0.1 g) was measured with a precision balance. Thereafter, the alloy foil was dissolved in 10 mL of concentrated nitric acid, the volume was adjusted with deionized water, and the palladium concentration was measured by an ICP emission analyzer (SPS3000, manufactured by Hitachi High-Tech Science Co., Ltd.) by a conventional method. The palladium eutectoid ratio was calculated by calculating the palladium mass from the measured value and dividing by the precise mass of the alloy foil.

<< Eutectoid ratio of foil surface >>
A 10 mm square was collected from the vicinity of the center of the obtained palladium-copper alloy release foil, and a scanning electron microscope (S-4300, Hitachi High Co., Ltd.) was used for each of the front side (plating surface side) and the back side (stainless base side). While observing with Technologies), the ratio of palladium to copper was analyzed with an energy dispersive X-ray analyzer (EMAX EX-220, manufactured by HORIBA). Five arbitrary rectangular regions of about 100 μm square were analyzed at an acceleration voltage of 15 kV and a magnification of 1,000 times, and the average value was taken as the palladium eutectoid ratio.

  The evaluation results are shown in Tables 2 to 5.

<Evaluation results of peelability, foil appearance and eutectoid ratio of palladium-copper alloy release foil>
In Examples A1 to A9, (C) pyrophosphate compound (potassium pyrophosphate and / or pyrolin) so that Cp is 0.35 mol / L or more and 1.1 mol / L or less and P ratio is 4.8 or more and 23.2 or less. Acid) and (B) copper (II) salt concentrations were varied to produce a palladium-copper alloy release foil.
The obtained palladium-copper alloy release foil was flexible and had good peelability, and had a uniform silver appearance on both the front and back sides. The absolute value of the difference between the front and back palladium eutectoid ratios was within 14% by mass, and a palladium-copper alloy release foil with little curling was obtained.

Examples A10, A12, A13, A15, A16 have a Cp of 0.35 mol / L or more and 1.1 mol / L or less, a P ratio of 4.8 or more and 23.2 or less, and (C) as potassium pyrophosphate and tripolyline An alloy foil was prepared with a plating solution to which both potassium acid was added.
The obtained palladium-copper alloy release foil had a uniform silver appearance on both sides. By adding potassium tripolyphosphate, a palladium copper alloy release foil with less curling was obtained.

In Example A11, Cp is 0.35 mol / L or more and 1.1 mol / L or less, P ratio is 4.8 or more and 23.2 or less, and (C) is an alloy foil with a plating solution to which only potassium tripolyphosphate is added. Produced. In addition, about 10 mass% potassium pyrophosphate is contained in the plating solution as an impurity of added potassium tripolyphosphate.
The obtained palladium-copper alloy release foil had a uniform silver appearance on both sides. A palladium copper alloy release foil with very little curling was obtained.

In Example A14, Cp was 0.35 mol / L or more and 1.1 mol / L or less, P ratio was 4.8 or more and 23.2 or less, and (C) sodium pyrophosphate and sodium tripolyphosphate were added as pyrophosphate compounds. An alloy foil was prepared with a plating solution.
The obtained palladium-copper alloy release foil had a uniform silver appearance on both sides. A palladium copper alloy release foil with very little curling was obtained.

Example B1 uses (C) potassium pyrophosphate as the pyrophosphate compound, Cp is less than 0.35 mol / L (Cp = 0.30 mol / L), and P ratio is less than 4.8 (P ratio of 3. An alloy foil was prepared with the plating solution 2).
The obtained palladium-copper alloy release foil had good flexibility and peelability, but curled into a cylindrical shape when peeled from the substrate. Moreover, although the foil surface (plating surface side) had a silver appearance, the foil back surface (substrate side surface) was pink and the appearance was different between the front and back of the foil.

Example B2 uses (C) potassium pyrophosphate as the pyrophosphate compound, Cp is less than 0.35 mol / L (Cp = 0.30 mol / L), and P ratio is less than 4.8 (P ratio of 1. An alloy foil was prepared with the plating solution 3).
The obtained palladium-copper alloy release foil had good flexibility and little curl, but had a pink appearance on both the front and back sides. Moreover, palladium was only eutectoid with an average ratio of 2%.

Example B3 uses (P) potassium pyrophosphate as the pyrophosphate compound, and Cp is less than 0.35 mol / L (Cp = 0.30 mol / L), but the P ratio is 4.8 or more (P ratio 4). .8) An alloy foil was prepared using the plating solution.
The obtained palladium-copper alloy release foil had good flexibility, but the difference between the front and back palladium was as large as 22%, the curl of the foil was large, and it was rounded into a cylindrical shape.

Example B4 uses (P) potassium pyrophosphate as the pyrophosphate compound, and Cp is less than 0.35 mol / L (Cp = 0.30 mol / L), but the P ratio is 4.8 or more (P ratio 9 .6) An alloy foil was prepared with the plating solution.
The obtained palladium-copper alloy release foil had good flexibility, but the difference between the front and back palladium was as large as 21%, the curl of the foil was large, and it was rounded into a cylindrical shape.

Example B5 uses (P) potassium pyrophosphate as the pyrophosphate compound, and Cp is less than 0.35 mol / L (Cp = 0.30 mol / L), but the P ratio exceeds 23.2 ( P ratio 38.5), (B) An alloy foil was prepared with a plating solution having a low copper (II) salt concentration.
The obtained palladium-copper alloy peeled foil had good flexibility, but the curl of the foil was large and it was rounded into a cylindrical shape.

Example B6 uses (A) dinitrodiammine palladium (II) as a palladium (II) ammine complex salt, adds ammonium nitrate instead of potassium pyrophosphate, and (D) tetravalent instead of tetravalent selenium compound. (E) Electroplating was attempted with a plating solution in which nicotinamide was added instead of the pyridinesulfonic acid compound.
However, after electrolysis, no plating film was formed on the substrate, and an alloy foil could not be obtained.

Example B7 uses (C) potassium pyrophosphate as the pyrophosphate compound, Cp is less than 0.35 mol / L (Cp = 0.30 mol / L), and P ratio is less than 4.8 (P ratio 3). An alloy foil was prepared with the plating solution (2). Dichlorodiammine palladium (II) was used as the (A) palladium (II) ammine complex salt of the plating solution used, and dissolved by adding ammonia.
The obtained palladium-copper alloy release foil had good flexibility and peelability, but curled into a cylindrical shape when peeled from the substrate. Moreover, although the foil surface (plating surface side) had a silver appearance, the foil back surface (substrate side surface) was pink and the appearance was different between the front and back of the foil.

In Example B8, an alloy foil was prepared in the same manner as in Example B1, except that copper (II) chloride was used as the (B) copper (II) salt.
The obtained palladium-copper alloy release foil had good flexibility and peelability, but curled into a cylindrical shape when peeled from the substrate. Moreover, although the foil surface (plating surface side) had a silver appearance, the foil back surface (substrate side surface) was pink and the appearance was different between the front and back of the foil.

In Example B9, electrolytic plating was attempted with a plating solution in which ammonium chloride was added instead of (C) pyrophosphate compound.
However, after electrolysis, no plating film was formed on the substrate, and an alloy foil could not be obtained.

In Example B10, electrolytic plating was performed with a plating solution to which picolinic acid was added instead of (E) the pyridinesulfonic acid compound.
The obtained film had a pink appearance, had poor flexibility, and cracked when peeled from the substrate.

In Example B11, electrolytic plating was performed with a plating solution in which a pentavalent antimony compound (Sb (V)) was added instead of the (D) tetravalent selenium compound.
The obtained film had a brown appearance and poor flexibility, and was cracked when peeled from the substrate.

In Example B12, electrolytic plating was attempted with a plating solution in which ammonium chloride was added instead of (C) pyrophosphate compound and (D) pentavalent antimony compound was added instead of tetravalent selenium compound.
However, after electrolysis, no plating film was formed on the substrate, and an alloy foil could not be obtained.

Example B13 uses (A) palladium sulfate instead of palladium (II) ammine complex, (C) ammonium nitrate instead of pyrophosphate compound, (D) pentavalent antimony compound instead of tetravalent selenium compound The electroplating was attempted with the plating solution to which was added.
However, after electrolysis, no plating film was formed on the substrate, and an alloy foil could not be obtained.

In Example B14, potassium pyrophosphate was added as the (C) pyrophosphate compound, and an alloy foil was produced with a plating solution having Cp = 0.60 mol / L and a P ratio of 4.3.
The obtained palladium-copper alloy release foil had good flexibility and peelability, and there was little curl (warpage) when peeled from the substrate. However, although the foil surface (plated surface side) had a silver appearance, the foil back surface (surface on the substrate side) was pink, the appearance was different on the front and back of the foil, and the difference in palladium ratio between the front and back was large. .

In Example B15, potassium pyrophosphate was added as the (C) pyrophosphate compound, and an alloy foil was produced with a plating solution having Cp = 1.18 mol / L and a P ratio of 24.9.
The obtained palladium-copper alloy release foil had good flexibility and the same ratio of palladium on the front and back, but the curl (warpage) was large.

In Example B16, potassium pyrophosphate was added as the (C) pyrophosphate compound, and an alloy foil was prepared with a plating solution having a Cp = 0.60 mol / L, a P ratio of 4.8, and a pH of 6.5.
The obtained palladium-copper alloy release foil was burnt and poor in flexibility, and cracked when peeled from the substrate.

In Example B17, potassium pyrophosphate was added as the (C) pyrophosphate compound, and an alloy foil was produced with a plating solution having Cp = 0.60 mol / L, a P ratio of 38.5, and a pH of 10.5.
The obtained palladium-copper alloy release foil had good flexibility, but the peelability from the substrate was poor, and the residue of the palladium-copper alloy adhered to the spots. The alloy foil has a large curl (curvature) and is rounded into a cylindrical shape.

In Example B18, only potassium tripolyphosphate was added as a compound belonging to (C), and an alloy foil was produced with a plating solution having a Cp = 0.22 mol / L, a P ratio of 2.4, and a pH of 8.0.
The obtained palladium copper alloy foil had good flexibility and very little curling. However, the foil surface (plated surface side) has a pink appearance with unevenness, and the foil back surface (substrate side surface) has a pink color, and a foil having a silver appearance could not be obtained.

In Example B19, only potassium tripolyphosphate was added as a compound belonging to (C), Cp = 0.44 mol / L, P ratio was 28.3, tetravalent selenium compound was contained at 2 g / L, and pH was 8.0. An alloy foil was prepared with the plating solution.
The resulting film had a silver appearance, but was poor in flexibility and cracked when peeled from the substrate.

<Physical properties of electrolytic palladium copper alloy release foil>
<< State of foil cross section >>
The cross section of the palladium-copper alloy release foil obtained in Example A10 and Example B1 was observed with a scanning electron microscope (S-4300, manufactured by Hitachi High-Technologies Corporation). A carbon protective layer is formed on the palladium copper alloy release foil peeled off from the stainless steel substrate with a focused ion beam processing observation device FB-2100 (manufactured by Hitachi High-Technologies Corporation), and then a cross-section is formed by etching processing for observation. A sample was used. The sample was tilted 45 ° and observed with a scanning electron microscope.

  FIG. 1 shows a cross section of the foil obtained from Example A10, and FIG. 2 shows the foil obtained from Example B1. Both were alloy foils having no defects such as cracks and pinholes in the thickness direction of the foil.

<< Surface condition on the front and back of foil >>
FIG. 3 (Example A10) and FIG. 4 (Example B1) show the results of observation of the surface of the palladium-copper alloy release foil peeled from the substrate obtained in Example A10 and Example B1 with a scanning electron microscope. 3A and 4A are the plating surface side (front surface), and FIGS. 3B and 4B are the substrate side (back surface).
The alloy foil obtained in Example A10 was an alloy foil having no defects such as cracks and pinholes on the front surface and the back surface.
Similarly, the alloy foil obtained in Example B1 was also an alloy foil having no defects such as cracks and pinholes on the front and back surfaces.

<< Eutectoid ratio distribution in foil cross section direction >>
The palladium-copper alloy release foil obtained in Example A10 and Example B1 was embedded with a resin for electron microscope observation so that the cross-section was in the vertical direction, and mechanically polished to obtain a sample for cross-section observation. The obtained sample surface was sputter coated with platinum, and the ratio of palladium to copper was analyzed with a scanning electron microscope and an energy dispersive X-ray analyzer. FIG. 5 (Example A10) and FIG. 6 (Example B1) show the results of measuring the distribution of palladium and copper by performing a line scan in the thickness direction of the cross section of the alloy foil. In the graph of palladium and copper count numbers, the left side (0 μm position) is the stainless steel substrate side, and the right side is the plating surface side.

  In the alloy foil of Example A10, palladium and copper were uniformly distributed from the stainless steel substrate side to the plating surface side. Visually, the front and back surfaces were silvery in appearance.

  On the other hand, in the alloy foil of Example B1, the count number of palladium was small on the stainless steel substrate side, and palladium was inclined and distributed by about 1 μm from the stainless steel substrate side to the plating surface side. In contrast, copper was uniformly distributed from the stainless steel substrate side to the plating surface side. That is, copper was rich with respect to palladium on the stainless steel substrate side, and the composition ratio in the cross section direction of the alloy foil was not uniform. Visually, the surface on the stainless steel substrate side was pink.

<< Selenium (Se) eutectoid ratio >>
0.1389 g of the palladium-copper alloy release foil obtained in Example A10 was dissolved in 10 mL of concentrated nitric acid, the volume was adjusted to 20 mL with deionized water, and then an ICP emission analyzer (SPS3000, manufactured by Hitachi High-Tech Science Co., Ltd.) was used. The selenium concentration was measured at The measurement wavelength of selenium was λ = 206.279 nm in order to avoid interference with the palladium peak.
As a result, the selenium concentration was 28.5 ppm. The selenium eutectoid ratio was calculated by calculating the mass of selenium from the measured value and dividing by the mass of the alloy foil. The palladium copper alloy release foil obtained in Example A10 contained 0.4% by mass of selenium.
For the palladium copper alloy foils obtained in Examples A1 to 9, Examples A11 to 16, Examples B1 to 5, B7 to 8, Examples B10 to 11, and Examples B14 to 19, the selenium eutectoid is the same as in Example A10. The ratio was measured. The results are shown in Tables 2-5.

  From the palladium copper alloy foil obtained from Example B16, selenium was not detected and the flexibility was poor. On the other hand, the palladium copper alloy foil obtained from Example B19 contained 2.7% by mass of selenium, but the flexibility of the foil was poor.

<Polarization behavior of electrolytic palladium copper alloy plating solution for forming palladium copper alloy release foil>
For the plating solutions of Example A10 and Example B1, the current value was measured while scanning the potential, and the polarization curve was measured. For the working electrode, three types of stainless steel (SUS304), brass, and copper were used. The counter electrode was a platinum wire and the reference electrode was a silver / silver chloride electrode.
The measurement conditions are shown in Table 6, and the measurement results are shown in FIGS.

  FIG. 7 shows the result of measuring the polarization curve of the palladium-copper alloy plating solution of Example A10 by changing the metal species of the working electrode. It can be seen that when the working electrode is immersed in the plating solution and the potential is polarized negatively, the current curves almost overlap.

  On the other hand, FIG. 8 is a polarization curve of Example B1 (conventional plating solution). It can be seen that the current curves do not overlap and that the deviation of the polarization curves is large particularly in a metal substrate (SUS304) having an oxide film. As described above, the conventional plating solution is easily affected by the oxide film of the base metal. Therefore, when plating on a metal substrate having an oxide film under a constant current density condition, the cathode potential tends to fluctuate during coating with the palladium copper alloy plating film, and the alloy ratio in the film thickness direction is not uniform. It seems to be easy to become.

When the electrolytic copper-copper alloy plating solution for forming a palladium-copper alloy release foil of the present invention is used, the peelability from a metal substrate having an oxide film is good, and after peeling from the metal substrate, it is flexible and warps (curls). A palladium-copper alloy foil with few defects such as pinholes and cracks can be obtained. In particular, a palladium-copper alloy release foil having a uniform alloy composition with respect to the thickness direction of the foil and a small difference in the alloy ratio between the front and back surfaces can be obtained.
The palladium-copper alloy plating solution of the present invention is widely used for forming palladium-copper alloy foils used in decorative articles, dental materials, electronic materials, catalyst materials, and the like.

1: Palladium copper alloy foil 2: Plated surface side 3: Base side

Claims (16)

(A) palladium (II) ammine complex salt, (B) copper (II) salt, (C) pyrophosphoric acid compound and / or tripolyphosphoric acid compound, (D) tetravalent selenium compound, and (E) pyridinesulfonic acid compound Containing
The molar concentration of the compound belonging to (C) is 0.35 mol / L to 1.1 mol / L, and the value obtained by dividing the molar concentration of the compound belonging to (C) by the molar concentration of copper is 4.8 to 23. 2. An electrolytic palladium-copper alloy plating solution for forming a palladium-copper alloy release foil, having a pH of 7.5 or less and 9.5 or less.   The electrolytic palladium-copper alloy plating solution for forming a palladium-copper alloy release foil according to claim 1, containing at least a tripolyphosphate compound as (C).   (A) Palladium (II) ammine complex salt is dichlorotetraammine palladium (II), tetraammine palladium (II) sulfate, dichlorodiammine palladium (II), dinitrodiammine palladium (II), tetraammine palladium (II) nitrate, tetraammine palladium. (II) sulfamate, tetraammine palladium (II) methanesulfonate, tetraammine palladium (II) hydrochloride, tetraammine palladium (II) carbonate, tetraammine palladium (II) acetate and tetraammine palladium (II) oxalate The electrolytic palladium-copper alloy plating solution for forming a palladium-copper alloy release foil according to claim 1 or 2, which is one or more compounds selected from the group consisting of these hydrates.   The (B) copper (II) salt is copper sulfate (II), copper chloride (II), copper nitrate (II), copper pyrophosphate (II), copper sulfamate (II), copper methanesulfonate (II) One or more compounds selected from the group consisting of copper carbonate (II), copper hydroxide (II), copper formate (II), copper acetate (II), copper oxalate (II) and hydrates thereof The electrolytic copper-copper alloy plating solution for forming a palladium-copper alloy release foil according to any one of claims 1 to 3. On the metal substrate having an oxide film on the surface, the cathode current density is in the range of 0.5 A / dm ² or more and 10 A / dm ² or less, the average ratio of palladium is 40 mass% or more and 80 mass% or less, and the thickness is 0.5 μm. The palladium copper alloy peeling film obtained by forming a palladium copper alloy plating film having a thickness of 20 µm or less and peeling the palladium copper alloy plating film from the metal substrate. 5. The electrolytic copper-copper alloy plating solution for forming a palladium-copper alloy release foil according to claim 4.   A palladium copper alloy plating film is formed on a metal substrate having an oxide film on its surface using the electrolytic palladium copper alloy plating solution for forming a palladium copper alloy release foil according to any one of claims 1 to 5. A method for producing a palladium-copper alloy release foil, characterized in that the palladium-copper alloy release foil is formed by peeling the palladium-copper alloy plating film from the metal substrate.   The method for producing a palladium-copper alloy release foil according to claim 6, wherein the metal substrate is stainless steel, titanium, aluminum, chromium, or a plated surface of these metals.   The method for producing a palladium-copper alloy release foil according to claim 6 or 7, wherein an average ratio of palladium in the palladium-copper alloy release foil is 40 mass% or more and 80 mass% or less. In the palladium copper alloy release foil, when the ratio of palladium on the surface that was on the metal substrate side is X ₁ and the ratio of palladium on the surface that is on the plating solution side is X ₂ , | X ₂ −X ₁ | ≦ It is 15 mass%, The manufacturing method of the palladium copper alloy peeling foil in any one of Claims 6 thru | or 8. The method for producing a palladium-copper alloy release foil according to claim 9, wherein 40 mass% ≦ X ₁ ≦ 80 mass% and 40 mass% ≦ X ₂ ≦ 80 mass%. 11. The claim according to claim 6, wherein the palladium copper alloy plating film is formed with a thickness of 0.5 μm or more and 20 μm or less in a cathode current density of 0.5 A / dm ² or more and 10 A / dm ² or less. The manufacturing method of palladium copper alloy peeling foil of description. A palladium copper alloy foil having a thickness of 0.5 μm or more and 20 μm or less and an average ratio of palladium of 40% by mass or more and 80% by mass or less, wherein the ratio of palladium on one side is X _A , and the palladium on the other side the ratio when the _{X B, | X B -X a} | Pd - Cu alloy foil which is a ≦ 15 mass%. The palladium copper alloy foil according to claim 12, wherein 40 mass% ≦ X _A ≦ 80 mass% and 40 mass% ≦ X _B ≦ 80 mass%.   The palladium copper alloy foil according to claim 12 or 13, containing selenium.   The palladium copper alloy foil according to claim 14, wherein the selenium content is 0.01 mass% or more and 2 mass% or less. (A) Plating solution for preparing an electrolytic palladium-copper alloy plating solution for forming a palladium-copper alloy peeling foil according to any one of claims 1 to 5 by adding a palladium (II) ammine complex salt An aqueous solution for preparation,
(B) a copper (II) salt, (C) a pyrophosphate compound and / or a tripolyphosphate compound, (D) a tetravalent selenium compound, and (E) a pyridinesulfonic acid compound,
The molar concentration of the compound belonging to (C) is 0.35 mol / L to 1.7 mol / L, and the value obtained by dividing the molar concentration of the compound belonging to (C) by the molar concentration of copper is 4.8 to 23. An aqueous solution for preparing a plating solution, which is 2 or less.