JP6162161B2 - Electroplating cell and metal film manufacturing method - Google Patents

Description

  The present invention relates to an electroplating cell and a method for producing a metal film. More specifically, the present invention relates to an electroplating cell capable of easily forming a metal film on the surface of a cathode (to-be-plated) and a metal film using the same. Regarding the method.

There is a need for a technique for forming a pattern made of a metal film (hereinafter also referred to as “metal pattern”) on a conductive substrate by a simple method. Conventionally, wet electroplating has been most commonly performed by masking portions other than the metal pattern. However, the mask formation process and the mask removal process are necessary, and there is a problem that the management of the plating solution and the waste liquid treatment cost are high.
In recent years, a method of removing a masking portion after forming a metal film by a “physical method” such as physical vapor deposition or sputtering without such a problem is being adopted. However, these physical metal film forming methods generally have a slow film formation speed and require a vacuum system, which is not an economical high-speed production system.

  On the other hand, as another method that does not require masking, a method in which an ink in which conductive fine powder and a binder are mixed is applied by a “printing method” such as screen printing or ink jet, and then the binder is removed by baking. However, it is difficult to form a circuit having a small volume resistivity by these “printing methods” even if a volatile or sublimable binder is employed.

  By the way, in recent years, in electroplating, gel electrolytes (Patent Document 1) and cation exchange membranes (Patent Documents 2 and 3) are used as an attempt to prevent electrodeposition other than the desired part and to form a circuit without masking. Attempts have been made.

When these diaphragms are used, for example, in Cu plating in which electrodeposition from an aqueous solution is relatively easy, a current density of about 10 mA / cm ² is obtained at room temperature. However, in order to perform further high-speed film formation (high current density electrodeposition), it is necessary to increase the metal ion concentration and raise the temperature, which is expensive.
In particular, metal ions whose electrodeposition reaction (reduction precipitation reaction) competes with the discharge reaction of hydrogen ions (hydrogen generation reaction) (for example, ions of metals with a low deposition potential, such as nickel ions, zinc ions, tin ions). It was difficult to perform electrodeposition using a diaphragm from an acidic to weakly acidic aqueous solution having a high hydrogen ion concentration.

Although the details of the reason are unclear, it seems to be due to the following reasons (1) to (3).
(1) Hydrogen is generated in the electrodeposition portion, and defects (voids) are formed.
(2) Precipitation overvoltage is too small and electrodeposits in the form of fine powder or lump. Therefore, when electrodeposition is performed with the diaphragm and the cathode in close contact with each other, the diaphragm and the electrodeposit are bitten.
(3) Due to the increase in pH at the cathode interface accompanying the generation of hydrogen, hydroxide is generated in the electrodeposition portion, and passivation (increase in bath voltage) proceeds.

  When electrodeposition is performed using a diaphragm, hydrogen ions in the anode chamber liquid are blocked by the presence of the diaphragm, and the pH tends to increase at the cathode interface. For this reason, the above-mentioned problem becomes particularly remarkable. In particular, in an electroplating cell (no cathode chamber solution) in which the diaphragm and the cathode are in close contact, or an electroplating cell with a very small amount of cathode chamber solution, the amount of hydrogen generated by the hydrogen generation reaction is very small. Even if it exists, normal electrodeposition was difficult by the influence of said (1)-(3). Therefore, even with electrodeposition from noble metal ions that should have generated only a very small amount of hydrogen (for example, Cu electrodeposition), the critical current density (film formation rate) is that of a normal electroplating cell having a cathode chamber solution. It was regarded as a problem that it was much lower than that.

  The fundamental cause of the difficulty of high-speed electrodeposition when using a diaphragm as described above is insufficient mobility of ions and accompanying water in the membrane, that is, the development of an ion conduction path in the hydrophilic part. Is considered insufficient. For this reason, it is considered effective to promote the development of ion conduction paths in order to increase the deposition rate.

For example, in Patent Document 4, although not a diaphragm for electroplating, a solution containing a fine void forming component, a matrix component, and an ionic polymer component is formed, and only the fine void forming component is obtained from the obtained film. An ionic membrane for electrodialysis (concentration and separation of ions) obtained by dissolving and removing is disclosed.
This document describes that a fine water-containing structure in an ionic membrane can be developed by such a method. However, the above method is a complicated and not economical process because it is necessary to remove the fine void forming component from the film after film formation.

Patent Document 5 discloses a proton exchange membrane fuel that is not a diaphragm for electroplating, but is obtained by swelling a film made of a fluoropolymer material with water or an organic solvent soluble in water at 100 ° C. or higher. An ion exchange membrane for a battery is disclosed.
This document describes that when the swelling treatment is performed at a high temperature, the moisture content of the ion exchange membrane is difficult to return to the state before the swelling treatment. However, the method exemplified in the document has a problem that it is necessary to perform a swelling treatment on a sodium-type ion exchange membrane and then perform an acid treatment (sulfuric acid treatment) to return the acid form.

Patent Document 6 discloses a method for processing an ion exchange membrane in which an ion exchange membrane having a fluorinated polymer as a skeleton is immersed in a water-soluble organic solvent and then rolled or stretched to reduce the film thickness.
This document describes that the membrane resistance of the ion exchange membrane can be reduced by such a method. However, this method is not only a rolling process but also a complicated method that requires acid cleaning for removing contaminants.

Patent Document 7 discloses a method of manufacturing an ion exchange membrane in which water is held in an ion exchange membrane and dried while the shape of the ion exchange membrane holding the water is fixed.
Patent Document 8 discloses a method of swelling a cation exchange membrane with an organic solvent and then attaching the membrane to a strong frame to remove the solvent from the membrane.
The methods described in Patent Documents 7 and 8 are intended to reduce dimensional changes. In Patent Documents 7 and 8, there is no description that the hydrophilic structure has been developed by these methods and the water content or ionic conductivity has been greatly improved.

Further, in Patent Document 9, a step of forming an organic polymer by a solution casting method and a film obtained by the film formation are immersed in an aqueous solution of an organic compound that is soluble in water and has a boiling point of 100 ° C. or higher. Thus, a method for producing a proton conducting membrane is disclosed which includes a step of equilibrium swelling and a step of evaporating water by heat treatment and drying.
The method described in this document has a problem in that since a heating step is added, the developed hydrophilic structure is destroyed and high ion conductivity cannot be obtained.

  The next problem is that the diaphragm obtained by the above-mentioned known method does not necessarily exhibit high ion conductivity and good electrodeposition performance with good reproducibility. Moreover, there has never been an example in which a method for accurately determining the quality of the hydrophilic structure of the diaphragm has been proposed.

JP 2005-248319 A JP 2012-219362 A International Publication WO2013 / 1225643 JP 2001-070768 A JP-A-6-342665 JP-A-5-255522 JP 2014-086205 A JP 57-023086 A JP 2004-079378 A

The problem to be solved by the present invention is to provide an electroplating cell capable of easily forming a metal film and a method for producing a metal film using the same.
In addition, another problem to be solved by the present invention is that an electroplating cell capable of performing pattern electrodeposition without using a plating solution containing a metal ion that easily generates hydrogen and a metal film using the same. It is to provide a manufacturing method.
In addition, another problem to be solved by the present invention is that high-speed electrodeposition is possible with high reproducibility, and for that purpose, an electrolysis that does not require complicated processes such as a drying step of the diaphragm, an acid treatment step, and a rolling step. An object of the present invention is to provide a plating cell and a method for producing a metal film using the same.
Furthermore, another problem to be solved by the present invention is to provide a method for accurately determining the quality of the hydrophilic portion structure of the diaphragm.

In order to solve the above problems, the electroplating cell according to the present invention is:
An anode chamber for holding the anode chamber liquid;
A diaphragm for isolating the anode chamber and the cathode,
The diaphragm has a peak value (q _peak ) derived from the hydrophilic structure in a scattering spectrum measured in water at room temperature by a small-angle X-ray scattering method of 0.14Å ^-1 (1.4 nm ^-1 ) or less. Become.

  The gist of the method for producing a metal film according to the present invention is to form a metal film on the surface of the cathode using the electroplating cell according to the present invention.

When a special treatment is applied to the diaphragm formed using a normal method or the diaphragm is formed under special conditions, the hydrophilic portion structure in the diaphragm changes. The quality of the hydrophilic portion structure can be accurately determined by analyzing a small angle X-ray scattering (SAXS) spectrum. Specifically, when the peak value (q _peak ) derived from the hydrophilic structure appearing in the SAXS spectrum is 0.14Å ⁻¹ (1.4 nm ⁻¹ ) or less, the diaphragm has a hydrophilic structure (ion channel). Is well developed.

  When electrodeposition is performed using such a diaphragm, ions are smoothly transported in the diaphragm. As a result, high-speed electrodeposition is possible, and precipitation of metal hydroxide is difficult to occur during electrodeposition. Moreover, maskless pattern electrodeposition can be performed at high speed using a plating solution containing metal ions that are likely to generate hydrogen. For example, a metal pattern such as nickel, which has conventionally been difficult to form at high speed, can be easily formed on a conductive substrate.

It is the schematic of the electroplating cell which concerns on the 1st Embodiment of this invention. It is the schematic of the electroplating cell which concerns on the 2nd Embodiment of this invention. 2 is a small angle X-ray scattering (SAXS) profile of a diaphragm deposited under various conditions.

Hereinafter, an embodiment of the present invention will be described in detail.
[1. diaphragm]
The electroplating cell according to the present invention includes an anode chamber for holding the anode chamber liquid and a diaphragm for isolating the anode chamber and the cathode. The electroplating cell may further include a cathode chamber for holding the cathode chamber solution.
In the present invention, the diaphragm has a peak value (q _peak ) derived from the hydrophilic structure of 0.14Å ^-1 (1.4 nm ^-1 ) or less in a scattering spectrum measured in room temperature water by a small angle X-ray scattering method. It consists of something. This point is different from the conventional one.

[1.1. Diaphragm Material]
The following (1) to (4) are listed as necessary conditions for the diaphragm.
(1) When a voltage is applied to the metal ions to be plated, the metal ions can be moved from the anode chamber to the cathode chamber (or the surface of the cathode).
(2) It is non-electron conductive (no metal film is deposited on the diaphragm).
(3) Stable in the plating bath (does not dissolve in the anode chamber solution or the cathode chamber solution and retains sufficient mechanical strength).
(4) When a soluble anode is used as the anode, it is possible to prevent the fine particles (anode sludge) generated by the soluble anode from diffusing into the cathode chamber (acting as an anode back).

As long as these conditions are satisfied, the membrane may be a membrane (microporous membrane) made of a neutral material having pores through which ions can pass. However, in order to enable high-speed film formation, the material of the diaphragm is preferably a solid polymer electrolyte having a desired electrodeposited ion permeability.
When the metal ion to be electrodeposited is a cation, a cation exchange membrane having a cation exchange group (carboxyl group, sulfonic acid group, phosphonic acid group, etc.) is used for the diaphragm.
On the other hand, when the metal ion to be electrodeposited is an anion (for example, an oxyacid anion such as a zincate ion or a stannate ion, a cyanide complex, etc.), the anion exchange group (for example, a quaternary ammonium group) ) Is used.

As a material of the cation exchange membrane, for example,
(1) carboxyl group-containing resins such as carboxyl group-containing acrylic resins, carboxyl group-containing polyester resins, carboxyl group-containing polyamide resins, polyamic acid resins (polyamic acid resins),
(2) sulfonic acid group-containing resin such as perfluorosulfonic acid resin,
(3) Phosphonic acid group-containing resin,
and so on.

From the viewpoint of high heat resistance, chemical resistance, and mechanical strength, the cation exchange membrane is preferably a fluorine-based cation exchange membrane, and more preferably a perfluoro-based electrolyte membrane such as a perfluorosulfonic acid resin membrane.
The diaphragm may be made of one kind of material, or may be made of two or more kinds of materials. Further, the diaphragm may be a joined body, polymer alloy, laminate, or composite of two or more materials. Further, the diaphragm may be an organic / inorganic hybrid film in which alumina, silica or the like is dispersed in a solid polymer electrolyte.

[1.2. Advantages of solid polymer electrolyte membrane]
The reason why a solid polymer electrolyte membrane is particularly preferable as the diaphragm will be described below. This is because, in principle, when a solid polymer electrolyte membrane is used, high-speed plating is possible as compared with the case where a neutral diaphragm (microporous membrane) is used.

The limit current density I _L (maximum electrodeposition rate) depends on the diffusion constant D of metal ions, valence z, electrodeposition ion concentration C, diffusion layer thickness δ on the electrodeposition surface, and transport number α of electrodeposited ions. It is represented by the formula (1) ("About the limiting current density of nickel plating", Shigeo Hoshino et al., Metal Surface Technology, vol.23, No.5, 1972, p263).
I _L = DzFC / (δ (1-α)) (1)

From the equation (1), it can be seen that it is effective to increase the transport number α of the deposited ions as much as possible in order to speed up the plating.
In electroplating using a neutral diaphragm, the transport number α of metal ions in the diaphragm is around α = 0.5. On the other hand, solid polymer electrolyte membranes have large ion transport numbers, and some cation exchange membranes have α close to 1. Therefore, it can be understood from the equation (1) that a large limit current density I _L can be obtained.

By the way, some solid polymer electrolytes have a value of α considerably smaller than 1. In this case, ions that should not move as counter ions permeate the membrane and leak. For example, when a cation exchange membrane is placed in the middle as a diaphragm and the pure water and the anodic chamber liquid are separated, anions gradually leak from the anodic chamber liquid to the pure water side even when there is no external electric field. In particular, among the anions, the hydroxide ion OH ⁻ has a remarkably large diffusion rate as compared with other anions and is likely to leak.
The amount of OH ⁻ leakage increases when the pH of the anode chamber solution is high and the anode chamber solution is left at a high temperature for a long time. This suggests that, when electrodeposition is performed for a long time with a high-temperature anodic chamber solution having a high pH, the metal hydroxide tends to precipitate in the cathode and the film.

When α <1, as described above, in order to maintain electrical neutrality, cations also pair with anions and leak to the electrodeposition surface. For example, alkali metal ions such as Na ⁺ and K ⁺ that are generally contained in the anolyte solution as a buffer component or impurity component have a small hydrated ion radius and a high diffusion rate in the film. ^- and easy to leakage in pairs. That is, when the transport number of metal ions in the diaphragm decreases in the state in which the anode chamber liquid and the diaphragm contain an alkali metal ion component, alkali (NaOH, KOH, etc.) permeates the electrodeposition interface, and the metal hydroxide is formed. It is understood that it becomes easy to precipitate.

  For these reasons, it is preferable to use a diaphragm having a target ion transport number (cation transport number when the electrodeposited ion is a cation, anion transport number when the electrodeposited ion is an anion) as close to 1 as possible. Hereinafter, the approach of the present invention will be described in more detail.

[1.3. Inhibition of hydroxide formation]
In the present invention, the solid polymer electrolyte has an action of suppressing the formation of metal hydroxide from metal ions. For example, considering Ni as the electrodeposit and Ni (OH) ₂ as the metal hydroxide, the precipitation reaction is understood to be balanced by the following equations (2) and (3). The
Ni ²⁺ + 2OH ⁻ Ｎｉ Ni (OH) ₂ (2)
K _sp = [Ni ²⁺ ] · [OH ⁻ ] ² = 5.47 × 10 ⁻¹⁶
OH ⁻ + H ⁺ ⇔H ₂ O (3)
K _w = [H ⁺ ] · [OH ⁻ ] = 1.0 × 10 ⁻¹⁴

That is, the solubility product K _sp of metal hydroxides, and from the ion product K _w of water, the nickel ion concentration does not precipitate the nickel ion as hydroxide = [Ni ^2+], and pH are calculated. As is clear from the equation (2), in order not to generate hydroxide, it is necessary to reduce the Ni ²⁺ ion concentration on the electrodeposition surface as much as possible and reduce the OH ⁻ concentration (increase the hydrogen ion concentration). It is.
Solid polymer electrolyte used in the present invention, since the hydrophilic structure that transmits ions is developed, to stabilize the Ni ²⁺ ions, reduce the free Ni ²⁺ ion concentration (activity), (2) By deviating the balance of the equation to the left, precipitation of metal hydroxide is suppressed. These effects will be described together below.

[1.4. Small angle X-ray scattering (SAXS) spectrum]
In this invention, the quality of the hydrophilic part structure in a diaphragm is analyzed by a SAXS spectrum. In general, the quality of the hydrophilic part structure of the solid polymer electrolyte is discussed in terms of (A) water content and (B) ionic conductivity in a water-containing state. However, the superiority or inferiority of whether the film is suitable for electrodeposition cannot be discussed only with (A) and (B).

For example, many hydrocarbon electrolyte membranes retain higher water content and ionic conductivity (corresponding to acid group ratio or ion exchange capacity) than perfluoro electrolyte membranes. However, when electrodeposition is actually performed in the absence of cathodic chamber liquid, the hydrocarbon-based electrolyte membrane often has a lower limit current density than the perfluoro-based electrolyte membrane.
On the other hand, among perfluoro-based electrolyte membranes, the value of the limit current density varies greatly depending on the type and water treatment conditions, and the value does not necessarily correspond to the formulas (2) and (3). There was found.
Then, when the hydrophilic part structure of these films was analyzed by the SAXS method, it was confirmed that the quality of these films could be determined by optimizing the analysis method.

For example, as described in Hashimoto et al. (Polymer Journal, Vol.63, No.3, p166 (2006)), the hydrophilic part structure of the solid polymer electrolyte membrane by the SAXS method is a certain hydrophilic cluster model. It is assumed that the cluster diameter and cluster density are calculated by approximating the measured scattering spectrum data and discussed. International publication WO2013 / 100079 proposes a solid electrolyte membrane for a redox flow battery in which the value of the hydrophilic part structure parameter obtained by such analysis is limited.
On the other hand, Haubold et al. Calculated the distance between the hydrophilic cluster based on the peak value (q _peak ) in the measured scattering spectrum by a relatively simple method, and discussed the degree of development of the hydrophilic cluster (HGHaubold et al. al., Electrochimica Acta, vol. 66 (15) 1559 (2001)). However, these analysis methods are complicated, and the problem is that the validity of the model and the approximation error between the measured scattering spectrum and the model curve are large.

In the present invention, the peak value (q _peak ) pointed out by Haubold et al. Is in the vicinity of 0.15Å ⁻¹ (1.5 nm ⁻¹ ) so that calculation is not arbitrarily performed without depending on complicated analysis. Focusing on the structure of the hydrophilic part found in the material, the development of the hydrophilic part of the membrane was examined. As a result, 0.14Å ^-1 (1.4nm ^-1) or less at the peak value (q _peak) climate hydrated state, particularly preferably at 0.11Å ^-1 (1.1nm ^-1) or less, electrostatic In the analysis, it was found that the critical current density can be remarkably increased while maintaining the film strength.
On the other hand, when the peak value (q _peak ) exceeds 0.14Å ^-1 (1.4 nm ^-1 ), the development of the hydrophilic portion becomes insufficient. For this reason, hydroxide is easily generated in the film, and it is difficult to perform electrodeposition at a high current density.

In the SAXS spectrum of the diaphragm obtained in the normal film formation process, a peak appears in the vicinity of 0.15Å ^-1 (1.5 nm ^-1 ). On the other hand, when the diaphragm is processed using the method described later, the peak value (q _peak ) may be less than 0.08Å ^-1 (0.8 nm ^-1 ), or a clear peak may not be observed. In this case, since the hydrophilic portion is in an excessively developed swelling state, there is a possibility that the membrane strength cannot be maintained with a membrane made only of a solid polymer electrolyte.
In such a case, as described later, the solid polymer electrolyte is preferably used in combination with a membrane reinforcing structure (support material).

As described above, as described above, from the viewpoint of high heat resistance, chemical resistance, and mechanical strength, a perfluoro electrolyte membrane made of perfluorosulfonic acid resin or the like is preferable. Among solid polymer electrolyte membranes, perfluoro-based electrolyte membranes have a peak value (q _peak ) within the above-described range by _performing an appropriate treatment.
On the other hand, the hydrocarbon-based electrolyte membrane remains untreated and does not have a clear peak in the vicinity of 0.15１．５ ^-1 (1.5 nm ^-1 ) based on the hydrophilic portion structure after the treatment described later. There is something. This indicates that the ion channel is not sufficiently formed after the film formation, and that the structural change hardly occurs even if the processing described later is performed. Such materials are deemed unsuitable for the purposes of the present invention.

[1.5. Cast molding]
As a manufacturing method of a diaphragm,
(A) A material constituting the diaphragm is dissolved or dispersed in an organic solvent to form a cast solution, which is applied to a glass container or the like, and then heated to volatilize the organic solvent (cast molding method),
(B) A method of melting the material constituting the diaphragm at a high temperature and forming it with an extrusion molding machine (melt extrusion molding method),
and so on.
Among these, the film obtained by the cast molding method has a peak value (q _peak ) in the range of 0.14Å ^-1 (1.4 nm ^-1 ) or less, compared with the film obtained by the melt extrusion molding method. Easy to suppress. Therefore, it has been found that the cast molding method is preferable as a method for producing a diaphragm.

The details of why the cast molding method is preferable are unknown. Cast molding generally has a lower molding (firing) temperature than extrusion molding and can be formed without crushing the hydrophilic structure, but this point seems to be related to the peak value (q _peak ).
In cast molding,
(A) type of organic solvent,
(B) a solvent ratio of water as a solvent for developing the hydrophilic portion and a poor solvent (a solvent having low polarity) that prevents excessive development of the hydrophilic portion (that is, a water content ratio in the cast solvent),
(C) How to raise the temperature during solvent removal drying,
(D) maximum drying temperature,
It is said that the development of the hydrophilic portion can be controlled in a desirable shape by such means.
The solid polymer electrolyte becomes incompatible with water during electrodeposition (when water is contained) by optimizing these conditions and performing cast molding, or by performing the treatment described later after cast molding. As a result, it is considered that a high limit current density was achieved while maintaining the film strength.

In cast molding, generally, a mixed solvent of water and a hydrophilic organic solvent composed of alcohol, glycol, cellosolve (glycol ether) or the like is used. In order to develop the hydrophilic portion, a water-cellosolve-based or water-t-butyl alcohol-based mixed solvent is preferable as described later.
The maximum drying temperature during casting is preferably 120 ° C to 180 ° C, more preferably 130 to 150 ° C. When the drying temperature is less than 120 ° C., firing is insufficient, and the film strength is significantly reduced in a water-containing state. When the drying temperature exceeds 180 ° C., the elimination of acid groups starts and the ionic conductivity of the film decreases, which is not preferable.
In order to give the film after cast molding sufficient strength to be self-supporting, a certain degree of drying is required. At this time, if the drying conditions are optimized, the peak value (q _peak ) can be within the above-described range.
On the other hand, in order to obtain a high-strength diaphragm, it is necessary to dry the diaphragm sufficiently after casting. However, excessive drying may adversely affect the hydrophilic structure. In such a case, it is preferable to perform the process mentioned later after cast molding. Combining cast molding with the processing described below makes it possible to achieve both strong ion channel formation and high film strength.

[1.6. Membrane reinforcement structure]
The diaphragm may further include a membrane reinforcing structure in order to maintain the membrane strength and suppress the dimensional change when containing water.
In the present invention, the material and structure of the membrane reinforcing structure are not particularly limited.
As the membrane reinforcing structure, for example,
(A) Nonwoven fabric, woven fabric, or mesh made of polyamide (PA), polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), etc.
(B) a stretched and porous polytetrafluoroethylene (PTFE) porous film,
and so on.
In particular, the PTFE porous membrane is suitable as a membrane reinforcing structure because it suppresses the dimensional change of the diaphragm and has good wettability with the electrolyte. In addition, by optimizing the molding conditions of the porous membrane, the dimensional change in the horizontal direction of the diaphragm when containing water is suppressed, and swelling in the vertical direction (film thickness direction) is allowed. Therefore, in a water-containing state, the bending rate of the conductive path in the hydrophilic portion is reduced, and electrodeposition can be performed smoothly.

[1.7. Additive for plating]
[A. Overview of organic additives for plating]
In the present invention, the diaphragm may further contain an additive for plating.
The “plating additive” refers to an organic compound having a function of improving the smoothness (gloss) of a deposited film and preventing the formation of pits (macro defects).
The plating additive may be an ionic compound or a nonionic compound. The plating additive may be a water-soluble compound or may be a compound that is sparingly soluble in water.
Here, the “ionic compound” refers to an ion-binding compound such as an acid, a base, and a salt thereof (for example, sodium lauryl sulfate).
The “nonionic compound” refers to a covalently bonded compound such as polyethylene glycol or polypropylene glycol that has no charge.
“Water-soluble” means that the solubility in water at room temperature exceeds 1 g / L.
“Slightly soluble in water” means that the solubility in water at room temperature is 1 g / L or less.

In the case of nickel plating, as a plating additive, specifically,
(1) A primary brightener (for example, benzenesulfonic acid, saccharin, etc.) that refines the crystals of the plating film to give gloss.
(2) secondary brightener (for example, formaldehyde, butynediol, etc.) having a smoothing function of the plating film,
(3) A surfactant (for example, sodium lauryl sulfate) that improves the wettability by reducing the surface tension of the plating bath and prevents pits,
(4) Complexing agents that are strong ligands to precipitated metal ions and prevent the formation of hydroxide precipitates (for example, organic acids, aminocarboxylic acids, polyethyleneimines, polyamines, etc.)
Is mentioned.

Other additives include thiourea, benzothiazole, sodium naphthalene sulfonate, boronic acid, propargyl alcohol, coumarin and the like. These are all organic additives (secondary brighteners) that impart smoothness.
Also in plating other than nickel plating, commonly used organic additives can be added to the diaphragm. Further, in other plating such as copper plating, commonly used additives can be similarly used.

In normal electroplating, an appropriate amount of the plating additive is added to the plating bath, and the amount of consumption must be controlled. However, the management of the consumption amount of the additive is generally complicated.
In the present invention, the minimum amount of additive is added to the diaphragm. Therefore, when there is a cathodic chamber solution, the additive is gradually eluted from the diaphragm, so that the effect can be exhibited for a long time. Even when there is no cathodic chamber solution, the additive fixed to the diaphragm exhibits a strong interaction with the surface of the deposited metal and can improve the physical properties and smoothness of the deposited metal.

  That is, the rate at which the additive is oxidized and decomposed at the counter electrode (anode) or reduced by the object to be plated (cathode) and consumed can be extremely reduced. Therefore, the concentration control of the additive is not necessary. In addition, the electrodeposition efficiency decreases when additives are added excessively to the plating bath, and the film flexibility and solderability decrease due to the concentration of products decomposed by the electrode in the plating bath. Will never happen.

The plating additive is preferably a water-soluble compound that is generally used in electroplating, but may be a compound that is sparingly soluble in water. For example, saccharin is relatively poorly soluble in water, but dissolves well in organic solvents. Therefore, if saccharin is dissolved in an organic solvent and impregnated into a diaphragm, the additive gradually dissolves into the cathode chamber solution. As a result, the gloss effect can be exhibited for a long time. This is an advantage that cannot be achieved when sodium saccharin (Na salt), which is readily soluble in water, is added to the bath.
Particularly in nickel plating, the additive is preferably an organic compound containing N or P such as saccharin. This is because such an organic compound has a large effect of improving the smoothness and physical properties of the film.

Examples of the organic compound containing N, which is an additive for nickel plating, include amines, ammonium, imidazolium, pyridinium, amide, aminocarboxylic acid, betaine, and salts (compounds) thereof. Ammonium is particularly preferably a compound having quaternary ammonium as the cation moiety. This is because the quaternary ammonium compound has a large effect of increasing the smoothness of the film.
An example of the organic compound containing P, which is an additive for nickel plating, includes a phosphonium compound.

These additives may be used alone or in combination of two or more. The additive lowers the surface tension of the plating solution,
(1) Hydrogen gas generated from the cathode, or
(2) A substance (so-called “surfactant”) having a large action for promoting degassing of oxygen gas generated from an insoluble electrode (anode) may be used.
When a cation exchange membrane is used as the diaphragm, when a surfactant is used as an additive, the surfactant is preferably a cationic surfactant or a double-sided surfactant. Since these surfactants have an electrostatic interaction with the acid groups of the cation exchange membrane, they are easily fixed to the cation exchange membrane.
On the other hand, when an anion exchange membrane is used as the diaphragm, when a surfactant is used as the additive, the surfactant is preferably an anionic surfactant or an amphoteric surfactant.
In particular, it is preferable to use a cation exchange membrane as the diaphragm and a cationic surfactant or an amphoteric surfactant as the additive.

[B. Amount of additive added]
The amount of additive used in normal electroplating is several hundred ppm to several thousand ppm.
On the other hand, when an additive is added to the plating bath and impregnated and adsorbed on the diaphragm (the “direct method” described later), the amount of additive necessary to obtain a good metal film is the same as that of a normal electroplating method. Significantly less than that. This is the same when an additive is added to the diaphragm in advance.

The amount of the plating additive is preferably an amount that combines (ion exchange) with 0.1 to 50% of the ion exchange capacity of the membrane. When the amount of the additive is less than 0.1%, the effect of the additive is not observed. On the other hand, if the amount of the additive exceeds 50%, the ionic conductivity of the membrane is lowered and the bath voltage is increased.
For example, consider a case where an ion exchange membrane having a thickness of 25 μm, a size of 30 mm × 30 mm, and an ion exchange capacity of 1 mEq / g is in contact with a 70 g plating bath. When an additive having a molecular weight of about 300 is ion-bonded 1: 1 with the ion exchange group of the membrane, the amount of the additive that binds (ion exchange) with 0.1 to 50% of the ion exchange capacity of the membrane is:
(1) 0.2 ppm to 90 ppm in weight ratio with respect to the plating bath weight of 70 g,
(2) From 0.004 wt% to 2 wt% with respect to the film weight,
Each corresponds.

When the diaphragm to which the additive for plating is added is used, the amount of the additive for plating can be reduced as compared with the conventional method. This is due to the following reason.
(1) Electrodeposition using a diaphragm prevents the additive from moving to the anode chamber and being consumed by oxidative decomposition.
(2) If the additive is fixed to the diaphragm, the additive gradually moves to the cathode chamber during the electrodeposition, and the necessary amount is replenished.
(3) If electrodeposition is performed using a diaphragm, the amount of the cathode chamber liquid can be reduced to zero or extremely small. Since the additive concentration on the surface of the deposited metal can be increased, the required amount of additive may be very small.

[C. Method of adding plating additives]
Specific methods for adding the plating additive include the following methods.
(A) A method in which a necessary amount of an additive is dissolved in a plating bath, the plating bath is brought into contact with the diaphragm, and the additive is impregnated and adsorbed on the diaphragm (direct method).
(B) When the additive is water-soluble, a method of dissolving the additive in water to obtain a treatment liquid, bringing the treatment liquid into contact with the diaphragm, and fixing the additive to the diaphragm by ion exchange (ion exchange treatment method) .
(C) When the additive is sparingly soluble in water, the additive is dissolved in an organic solvent to form a treatment liquid, the diaphragm and the treatment liquid are brought into contact with each other, and the additive is fixed in the diaphragm (organic solvent impregnation) Law).
(D) A method in which an additive is dissolved or dispersed in a solution in which the material of the diaphragm is dissolved in an organic solvent, this solution is cast on the substrate surface, and the solvent is removed by drying (cast molding method).
(E) When the diaphragm is made of a meltable material, the diaphragm material and additives are heated and kneaded, and the kneaded product is extruded to form a film (melt extrusion method).

Among the methods described above, the ion exchange treatment method is simple and most economical. According to the ion exchange treatment method, the additive can be uniformly added to the diaphragm, the water-containing treatment can be easily performed, and no special treatment apparatus is required. The additive acts mainly on the electrodeposition surface side. Therefore, instead of bringing both surfaces (entire surface) of the film into contact with the treatment liquid, only one side (electrodeposition surface side) of the film may be brought into contact with the treatment liquid to apply the additive.
The addition using the ion exchange treatment method can be performed simultaneously with the water-containing treatment of the diaphragm described later. Similarly, the addition using the organic solvent impregnation method can be performed simultaneously with the diaphragm swelling treatment described later.

[D. Advantages of adding plating additives to the diaphragm]
Control of the concentration of the additive for plating and removal of waste products derived from the additive are also major problems in ordinary electroplating.
On the other hand, according to the method of the present invention, since it is only necessary to add a very small amount of additive to the diaphragm, electrodeposition can be performed without controlling the concentration of the plating solution. Further, it is substantially unnecessary to remove waste products derived from the oxidation / reduction of the additive, and the diaphragm can be used repeatedly. In addition, if the additive in the diaphragm is exhausted heavily, the amount of additive added to the diaphragm may be adjusted in consideration of the amount of electricity applied, or the additive may be periodically re-added to the diaphragm. it can.

[1.8. Diaphragm thickness]
The thickness of the diaphragm is not particularly limited as long as electroplating is performed smoothly. Specifically, the thickness of the diaphragm is preferably 0.01 μm to 200 μm, and more preferably 10 μm to 100 μm.

[1.9. Metal ions]
The diaphragm may further contain metal ions (for example, metal ions constituting the metal film) in addition to or instead of the plating additive.
From the same concept as the restriction of Na ⁺ , K ⁺ , and Cs ⁺ ions in the anode chamber liquid described later, the weight content of Na ⁺ , K ⁺ , and Cs ⁺ ions in the diaphragm is 1% or less (acid group exchange The rate is 50% or less). In general, a cation exchange membrane is commercially available in which 100% of the acid groups are exchanged with an alkali ion such as Na ⁺ (Na body). However, when electrodeposition is performed using such a diaphragm, alkali metal ions are liable to leak to the electrodeposition surface, which promotes the formation of metal hydroxide and is not preferable.

Therefore, it is preferable to use a cation exchange membrane (H form) that is not exchanged with Na ⁺ or a cation exchange membrane in which 50% or less of the acid groups are exchanged with alkali ions. In addition, it is more preferable that the cation exchange membrane is previously washed with a strong acid such as sulfuric acid, nitric acid or hydrochloric acid before electrodeposition in order to suppress the formation of metal hydroxide.

[2. Manufacturing method of diaphragm]
The diaphragm according to the present invention is
(1) A method of performing a swelling treatment on a film immediately after film formation (hereinafter referred to as “precursor film”),
(2) A method of subjecting the precursor film to water treatment,
(3) A method of further subjecting the precursor film to a water treatment after the swelling treatment,
Etc. can be manufactured.
When the film formation conditions are optimized, the target hydrophilic structure may be formed immediately after the film formation. However, in general, it is difficult to achieve both hydrophilic structure and film strength. On the other hand, when the above-described treatment is performed on the diaphragm after film formation, not only the desired hydrophilic portion structure can be formed with good reproducibility but also high film strength can be obtained.

[2.1. Swelling treatment]
[2.1.1. Definition]
“Swelling treatment” refers to a treatment of immersing the precursor film in a hydrophilic organic solvent or a mixed solvent of water and a hydrophilic organic solvent. The treatment liquid may contain the above-described plating additive.
When the precursor film is immersed in a hydrophilic organic solvent or a mixed solvent thereof at a predetermined temperature under predetermined conditions, the precursor film swells. At that time, when the swelling condition is optimized, an ion conductive path develops, and a diaphragm having the above-described hydrophilic portion structure is obtained. When electrodeposition is performed using the diaphragm thus obtained, the formation of metal hydroxide in the film can be suppressed.
In this case, as a result, the transport number of electrodeposited ions is improved, the continuity of the electrodeposition interface (diaphragm / cathode) is improved, and the diaphragm is sufficiently hydrated by electroosmotic water. Therefore, even when hydrogen is by-produced on the cathode, interfacial voids are less likely to be generated, and electrodeposition defects due to film thirst can be prevented.

If a large amount of the organic solvent remains in the membrane after the swelling treatment with the organic solvent, the ionic conductivity is inhibited. Therefore, the organic solvent used for the swelling treatment is preferably a solvent having a high solubility in water (that is, a hydrophilic organic solvent). The organic solvent is particularly preferably one that is completely compatible with water. A hydrophilic organic solvent is suitable as an organic solvent for the swelling treatment because water replacement after the swelling treatment is easy.
Further, when the swelling treatment is performed only with the hydrophilic organic solvent, the precursor film may be excessively swollen and the peak value (q _peak ) may be too small. In such a case, it is preferable to adjust the degree of swelling using a mixed solvent of a hydrophilic organic solvent and water.

[2.1.2. Specific example of hydrophilic organic solvent]
Examples of the hydrophilic organic solvent include low molecular weight alcohols, glycols, ketones, ethers, glycol ethers, nitriles, amides, sulfoxides, N-containing organic solvents, S-containing organic solvents, and organic acids. Any one of these hydrophilic organic solvents may be used, or two or more thereof may be used in combination.

Among hydrophilic organic solvents, those that mix with water in any proportion (compatible)
(A) lower alcohols such as methanol, ethanol, n-propanol, iso-propanol, t-butyl alcohol,
(B) low molecular weight glycols such as ethylene glycol and propylene glycol;
Etc.

Acetone is mentioned as a ketone.
Examples of ethers include THF, 1,2-dimethoxyethane (monoglyme, dimethyl cellosolve), and 1,3-dioxane.
Examples of the glycol ether include methyl cellosolve (ethylene glycol monomethyl ether), ethyl cellosolve (ethylene glycol monoethyl ether), and butyl cellosolve (2-butoxyethanol, ethylene glycol monobutyl ether).
Examples of the N-containing organic solvent include acetonitrile, DMF (dimethylformamide), and DMA (dimethylacetamide).
Examples of the S-containing organic solvent include DMSO (dimethyl sulfoxide).
Examples of the organic acid include formic acid and acetic acid.

Among the above solvents, the hydrophilic organic solvent is preferably at least one selected from the group consisting of ethanol, t-butyl alcohol, methyl cellosolve, ethyl cellosolve, and butyl cellosolve. Among them, butyl cellosolve is particularly preferable because it has a large effect of reducing the peak value (q _peak ).

[2.1.3. Processing conditions]
The swelling treatment may be performed at room temperature or may be performed under heating. In general, the higher the temperature of the swelling treatment, the easier the ionic conduction path develops. In order to shorten the swelling treatment time, the swelling treatment temperature is preferably 40 ° C. or higher.
On the other hand, if the swelling treatment temperature is too high, the swelling proceeds excessively, causing a decrease in film strength. In addition, the ion exchange group in the diaphragm may fall off. Accordingly, the swelling treatment temperature is preferably 180 ° C. or lower.

As the swelling treatment time, an optimum time is selected according to the swelling treatment temperature. In general, the higher the swelling treatment temperature, the longer the desired ion conductive path can be developed.
Furthermore, the swelling treatment may be performed under normal pressure, or may be performed under pressure in a pressurized container.

After the swelling treatment, the diaphragm is dried as necessary. In this case, if the drying temperature is too high, the hydrophilic structure may be broken or the ion exchange group may be eliminated during drying. Therefore, when drying, the drying temperature is preferably less than 160 ° C.
Moreover, you may further perform the water-containing process mentioned later after a swelling process. In this case, it is preferable to perform the hydrous treatment as it is without drying the membrane after the swelling treatment. When the hydrous treatment is performed while maintaining the swollen state, the hydrophilic portion structure is further developed, and the conductivity and transport number of the electrodeposited ions are improved.

  In the diaphragm formed by the cast molding method and the melt extrusion method, the hydrophilic organic solvent generally does not remain at a detectable level. Therefore, in the electroplating cell using a diaphragm, when a hydrophilic organic solvent is detected from a diaphragm, it can be estimated that the diaphragm processed by this invention was used.

[2.2. Water treatment]
[2.2.1. Definition]
“Water-containing treatment” refers to a treatment in which a precursor film or a film after swelling treatment is brought into contact with water or water vapor. Specifically, the hydrous treatment is performed by immersing the precursor film or the film after the swelling treatment in water, or exposing the precursor film or the film after the swelling treatment to water vapor. The water for water treatment may contain the above-mentioned plating additive.
The precursor film may be directly subjected to water treatment. Even if it is only a water-containing process, a hydrophilic part structure can be developed by optimizing conditions. However, when a hydrous treatment is performed on the membrane after the swelling treatment, the hydrophilic portion structure is further developed, and at the same time, all or a part of the hydrophilic organic solvent in the membrane can be replaced with water.
When the water-containing treatment is performed on the membrane after the swelling treatment, it is not always necessary to replace 100% of the hydrophilic organic solvent with water. However, if electrodeposition is performed using a diaphragm in which a large amount of organic solvent remains, problems such as contamination of the electrodeposition bath, odor, and flammability may occur. Therefore, it is preferable to perform the water treatment so that the residual amount of the organic solvent is 10% or less with respect to the membrane weight.

[2.2.2. Processing conditions]
The water treatment may be performed at room temperature or may be performed under heating. In general, the higher the temperature of the water treatment, the more easily the ion conductive path develops. In order to shorten the water treatment time, the water treatment temperature is preferably 40 ° C. or higher. The temperature of the hydrous treatment is more preferably 100 ° C. or higher. That is, the water-containing treatment is preferably performed by immersing the membrane in boiling water or exposing the membrane to water vapor.
On the other hand, when the water treatment temperature is too high, the swelling proceeds excessively, causing a decrease in film strength. In addition, the ion exchange group in the diaphragm may fall off. Therefore, the water treatment temperature is preferably 180 ° C. or lower.

As the water treatment time, an optimum time is selected according to the water treatment temperature. In general, the higher the water treatment temperature, the longer the target ion conductive path can be developed.
In addition, when the water treatment is performed after the swelling treatment, the organic solvent can be replaced with water in a shorter time as the water treatment temperature increases. In addition, when water treatment is performed using water, the solvent desorption time can be shortened by irradiating with ultrasonic waves during the water treatment.

[3. Electroplating cell (1)]
FIG. 1 shows a schematic diagram of an electroplating cell according to the first embodiment of the present invention.
In FIG. 1, the electroplating cell 10 includes an anode chamber 12, a cathode chamber 14, and a diaphragm 16. The anode chamber 12 is filled with the anode chamber liquid 20, and the anode 22 is immersed in the anode chamber liquid 20. Furthermore, the anode 22 is connected to the positive electrode of the power source 24.
The cathode chamber 14 is filled with a cathode chamber solution 24, and a cathode 26 is immersed in the cathode chamber solution 24. Further, the cathode 26 is connected to the negative pole of the power supply 24. When plating is performed using the electroplating cell 10, a metal film 28 is deposited on the surface of the cathode 26.

  The anode chamber 12 is for holding the anode chamber liquid 20. Similarly, the cathode chamber 14 is for holding the cathode chamber liquid 24. The size and shape of the anode chamber 12 and the cathode chamber 14 and the materials constituting them are not particularly limited, and an optimum one can be selected according to the purpose. The cathode chamber 14 and the cathode chamber liquid 24 are not necessarily required and can be omitted.

  The anode chamber 12 is filled with an anode chamber liquid 20 having a predetermined composition. Similarly, the cathode chamber 14 is filled with a cathode chamber liquid 24 having a predetermined composition. The amount of the anode chamber solution 20 and the cathode chamber solution 24 is not particularly limited, and an optimum amount can be selected according to the purpose. The details of the anode chamber solution 20 and the cathode chamber solution 24 will be described later.

The anode 22 may be any material as long as the surface is made of a conductive material. The anode 22 may be entirely made of a conductive material, or only the surface thereof may be made of a conductive material. Further, the anode 22 may be an insoluble electrode or a soluble electrode.
The cathode 26 is an object to be plated. The cathode 26 may be any material as long as the surface is made of a conductive material. The cathode 26 may be entirely made of a conductive material, or only the surface thereof is made of a conductive material.

The diaphragm 16 is for isolating the cathode 26 (to-be-plated object) from the anode chamber 12. In the case of the electroplating cell 10 including the cathode chamber 14, the diaphragm 16 is provided at the boundary between the anode chamber 12 and the cathode chamber 14. On the other hand, when there is no cathode chamber 14, the diaphragm 16 is provided in contact with the surface of the cathode 26. Since the details of the diaphragm 16 are as described above, the description thereof is omitted.
Further, the power source 24 is not particularly limited, and any power source that can apply a predetermined voltage between the anode 22 and the cathode 26 may be used.

[4. Method for producing metal film using electroplating cell (1)]
[4.1. Preparation of anode chamber solution]
First, an anode chamber solution 20 containing metal ions to be deposited on the cathode (substrate) 26 is prepared. The anode chamber liquid 20 is made of a water-soluble metal compound containing a metal element to be precipitated dissolved in water. The anodic chamber liquid 20 may further be
(1) Water-soluble organic solvents (alcohols, etc.)
(2) pH adjusters (bases, such as amines such as ethylenediamine; acids, such as hydrochloric acid),
(3) Buffer (for example, organic acid)
Etc. may be included.

[4.1.1. Water-soluble metal compound]
In the present invention, the metal to be deposited is not particularly limited, and an optimum metal can be selected according to the purpose. Examples of the metal to be deposited include titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, iron, cobalt, rhodium, iridium, nickel, tin, palladium, platinum, copper, silver, zinc, cadmium, Aluminum, gallium, indium, silicon, germanium, arsenic, antimony, bismuth, selenium, tellurium, and the like can be given.

Among these, silver, copper, gold, nickel, tin, platinum, and palladium are preferable as the metal to be deposited. This is because any of these metals can be electrodeposited from an aqueous solution, and the specific resistance of the metal film is small.
Ni is usually a metal that easily generates hydrogen from the surface of the cathode 26 during electroplating, and also easily generates hydroxide. However, when the present invention is applied to Ni plating, generation of hydrogen and generation of hydroxide can be suppressed.

Examples of water-soluble metal compounds include:
(1) halides such as chlorides,
(2) inorganic acid salts such as sulfates (for example, copper sulfate, nickel sulfate), nitrates (for example, silver nitrate),
(3) Organic acid salts such as acetate,
and so on. In view of material costs, inorganic acid salts are preferred.
The anode chamber liquid 20 may contain any one of these water-soluble metal compounds, or may contain two or more kinds.

  The concentration of the water-soluble metal compound contained in the anode chamber liquid 20 is not particularly limited, and an optimal value is selected according to the type of the water-soluble metal compound. The metal ion concentration in the anodic chamber liquid 20 is 0.001 M / L to 2 M / L, preferably 0.05 M / L to 1 M / L.

It is preferable that the anodic chamber liquid 20 is substantially basic and does not substantially contain ions (for example, Na ⁺ , K ⁺ , and Cs ⁺ ) that have a small hydrated ion radius and easily pass through the diaphragm 16. As a result of our confirmation, it has been found that when these ions are included as a component of the anode chamber liquid 20 in excess of 0.1 M / L, metal hydroxide is easily generated at the interface of the diaphragm 16. That is, it is desirable to limit the concentration of ions (particularly Na ⁺ , K ⁺ , Cs ⁺ ) other than electrodeposited ions contained in the anode chamber liquid 20 to 0.1 M / L or less. For these reasons, when adding a surfactant to the bath, it is preferable to use a surfactant that does not contain alkali metal ions.
On the other hand, among alkali metal ions, Li ⁺ ions have a relatively large hydrated ion radius and are difficult to permeate the diaphragm 16. Therefore, it may contain more than 0.1 M / L as a component of the anode chamber liquid 20.

[4.1.2. pH adjuster]
A pH adjusting agent is added to the anode chamber liquid 20 as necessary. The pH of the anode chamber liquid 20 is not particularly limited, and an optimum value is selected according to the type of the water-soluble metal compound.
If the pH is too low, the reduction reaction on the cathode 26 is mainly a hydrogen generation reaction. For this reason, the electrodeposition efficiency is greatly reduced, which is not economical. Accordingly, the pH is preferably 1 or more.
On the other hand, if the pH is too high, the metal hydroxide is easily involved on the electrodeposition surface, and the smoothness is lowered. Accordingly, the pH is preferably 6 or less.

[4.1.3. Buffering agent]
In some cases, a cation component other than metal ions necessary for electrodeposition is added to the anode chamber liquid 20 for the purpose of pH buffering action, improvement of conductivity for lowering the bath voltage, improvement of throwing power, and the like. In that case, instead of a compound containing Na ⁺ , K ⁺ , and Cs ⁺ ions, Li ⁺ ions having a large hydrated ion radius and difficult to permeate the diaphragm, or Mg 2 ⁺ , Ca ²⁺ , Addition of an inorganic compound containing Sr ²⁺ , Ba ²⁺ , and Al ³⁺ ions to the anode chamber liquid 20 is effective in suppressing metal hydroxide.
It is also effective to add organic compounds containing weak basic ions such as ammonium, amine, imine, imidazolium, pyridinium, pyrrolidinium, piperidinium, morpholinium and the like, which have a weak metal hydroxide-forming ability.

However, the electrodeposited metal ion concentration in the anode chamber liquid 20 and the metal ion concentration in the diaphragm 16 are in an equilibrium relationship. Therefore, the concentration of these compounds is preferably as low as possible so that the transport number of the metal ion concentration in the diaphragm 16 is not significantly reduced. Specifically, the concentration of these compounds is preferably 0.1 M / L or less, and the occupation ratio (acid group exchange rate) of these cations in the diaphragm 16 (particularly in the cation exchange membrane) is 50% or less. It is preferable that For example, in a cation exchange membrane having an acid group of 1 meq / g (EW = 1000), an Na ⁺ ion exchange rate of 50% corresponds to a membrane weight content of about 1.2%.

[4.1.4. Amount of anode chamber liquid]
The amount of the anode chamber liquid 20 is not particularly limited, and an optimal amount can be selected according to the purpose.

[4.2. Preparation of cathode chamber solution]
[4.2.1. Composition of cathode chamber solution]
Next, a cathode chamber solution 24 is prepared. Since the composition of the cathode chamber liquid 24 is the same as that of the anode chamber liquid 20, the description thereof is omitted.

[4.2.2. Amount of cathode chamber liquid]
The amount of the cathode chamber liquid 24 is not particularly limited, and an optimum amount can be selected according to the purpose.
In the present invention, the amount of the cathode chamber liquid 24 may be small. Specifically, the amount of the cathode chamber liquid 24 may be 100 μL / cm ² or less per unit area of the cathode 26. Further, the cathode chamber 14 and the cathode chamber liquid 24 can be omitted, that is, the diaphragm 16 and the cathode 26 can be brought into close contact with each other.

  Even in a state where there is substantially no cathode chamber liquid 24, a very small amount of water is transported from the diaphragm 16 to the electrodeposition surface (the surface of the cathode 26) by the electroosmosis phenomenon. Therefore, a continuous interface is formed between the diaphragm 16 and the cathode 26, and an electrochemical reaction (electrodeposition) can be performed. In order to improve the adhesion between the diaphragm 16 and the surface of the cathode 26, it is preferable to perform electrodeposition in a state where both are pressurized using a pressurizing mechanism as required.

  As described above, there is no known method for depositing a metal, which is substantially free of the cathode chamber solution 24 and easily generates hydrogen, from an aqueous solution at high speed using an electroplating cell using the diaphragm 16. If electroplating is performed in a state substantially free of the cathode chamber liquid 24, the shape of the anode 12 can be transferred to the object to be plated, and a metal pattern can be easily formed without a mask. Further, since there is no cathodic chamber solution 24, it is possible to eliminate the adhesion and carry-out of the plating solution to the object to be plated, and the water washing step and the waste water treatment step after electrodeposition can be greatly simplified.

[4.3. Electrodeposition]
A predetermined amount of the anode chamber liquid 20 and the cathode chamber liquid 24 are put into the anode chamber 12 and the cathode chamber 14, respectively. Next, a voltage is applied between the anode 22 and the cathode 26 arranged with the diaphragm 16 interposed therebetween using the power source 24. As a result, the metal ions in the cathode chamber liquid 24 are reduced, and a metal film 28 is deposited on the cathode 26.
As the deposition of the metal film 28 proceeds, the metal ion concentration in the cathode chamber solution 24 decreases. As a result, a metal ion concentration gradient is generated between the cathode chamber solution 24 and the anode chamber solution 20. Using this concentration gradient as a driving force, metal ions in the anode chamber liquid 20 diffuse into the cathode chamber liquid 24 through the diaphragm 16.

The voltage applied between the electrodes, the temperature of the plating bath during electrodeposition, and the electrodeposition time are not particularly limited, and an optimum value can be selected according to the purpose.
For example, in the case of nickel plating, the voltage is preferably 0.01 to 100V, and more preferably 0.05 to 10V. The temperature of the plating bath is preferably 0 to 100 ° C, more preferably 10 to 25 ° C. Furthermore, the electrodeposition time is preferably from 0.01 to 100 minutes, and more preferably from 0.05 to 5 minutes.

[5. Electroplating cell (2)]
The electroplating cell according to the second embodiment of the present invention includes an anode chamber for holding the anode chamber liquid and a diaphragm for isolating the anode chamber and the cathode. Moreover, the said diaphragm consists of what can selectively permeate | transmit the metal ion contained in the said anode chamber liquid.
That is, the electroplating cell according to the present embodiment does not include a cathode chamber for holding the cathode chamber solution. This point is different from the first embodiment.

In FIG. 2, the schematic of the electroplating cell which concerns on the 2nd Embodiment of this invention is shown.
In FIG. 2, the electroplating cell 40 includes an anode chamber 12, a diaphragm 16, an anode 22, a cathode 26, a power supply 24, and a pressurizing device 42.

The anode chamber 12 is for holding the anode chamber liquid 20. In the upper part of the anode chamber 12, a supply hole 12 a for supplying the anode chamber liquid 20 from the anode chamber liquid tank (not shown) into the anode chamber 12 is provided. A discharge port 12 b for discharging the anode chamber liquid 20 from the anode chamber 12 to a waste liquid tank (not shown) is provided on the side surface of the anode chamber 12.
An anode 22 is fitted into the opening at the lower end of the anode chamber 12. Further, the diaphragm 16 is bonded to the lower surface of the anode 22.
A pressurizing device 42 is provided on the upper surface of the anode chamber 12. The pressurizing device 42 is for moving the anode chamber 12, the anode 22, and the diaphragm 16 in the vertical direction.

  A base 46 is disposed below the anode chamber 12. On the upper surface of the base 46, a cathode (to-be-plated object) 26 is disposed. An energization section 48 is provided on the outer periphery of the upper surface of the cathode 26. The energization section 48 is for applying a voltage to the cathode 26 and is provided so as to surround a film forming region on the surface of the cathode 26. In the example shown in FIG. 2, the energizing portion 48 has a ring shape, and the distal end portion of the diaphragm 16 can be inserted into the ring. Furthermore, the anode 22 and the energization unit 48 (that is, the cathode 26) are connected to the power source 24.

In the present embodiment, an electrode capable of supplying the anode chamber liquid 20 to the surface of the diaphragm 16 is used for the anode 22. Specific examples of the anode 22 include a porous electrode having a pore diameter that allows the anode chamber liquid 20 to pass therethrough, a pattern electrode having a predetermined shape pattern, and the like.
In the case where the continuous metal film 28 is not formed, the void existing inside the anode 22 is used as the anode chamber, that is, the anode 22 is impregnated with a necessary amount of the anode chamber liquid, so 12 can also be omitted.
Other points regarding the anode chamber 12, the diaphragm 16, the anode 22, the cathode 26, and the power source 24 are the same as those in the first embodiment, and thus the description thereof is omitted.

[6. Method for producing metal film using electroplating cell (2)]
First, as shown in FIG. 2A, the cathode 26 is arranged on the base 46 in a state where the base 46 and the diaphragm 16 are separated from each other, and the energization unit 48 is arranged around the cathode 26. Further, the anode chamber liquid 20 is supplied into the anode chamber 12 through the supply hole 12a. The anode chamber liquid 20 is supplied to the surface of the diaphragm 16 through a gap (not shown) in the anode 22.
Next, as shown in FIG. 2B, the anode chamber 12 is moved downward using the pressurizing device 42, and the lower surface of the diaphragm 16 and the upper surface of the cathode 26 are brought into contact with each other. At this time, the pressing force of the pressurizing device 42 is adjusted, and an appropriate pressure is applied to the interface between the diaphragm 16 and the cathode 26.

  In this state, when a predetermined voltage is applied to the anode 22 and the energizing portion 48 (that is, the cathode 26) using the power supply 24, a metal film 28 is deposited on the interface between the diaphragm 16 and the cathode 26. At this time, if a new anode chamber liquid 20 is replenished into the anode chamber 12 through the supply hole 12a while discharging the exhausted anode chamber liquid 20 from the discharge port 12b as necessary, plating is continuously performed. be able to. After a predetermined time has elapsed, the anode chamber 12 is raised using the pressurizing device 42, and the diaphragm 16 and the cathode 26 are separated.

[7. Action]
When a special treatment is applied to the diaphragm formed using a normal method or the diaphragm is formed under special conditions, the hydrophilic portion structure in the diaphragm changes. The quality of the hydrophilic portion structure can be accurately determined by analyzing a small angle X-ray scattering (SAXS) spectrum. Specifically, when the peak value (q _peak ) derived from the hydrophilic part structure appearing in the SAXS profile is 0.14Å ^-1 (1.4 nm ^-1 ) or less, the diaphragm has a hydrophilic part structure (ion channel). Is well developed.

  When electrodeposition is performed using such a diaphragm, ions are smoothly transported in the diaphragm. As a result, high-speed electrodeposition is possible, and precipitation of metal hydroxide is difficult to occur during electrodeposition. Moreover, maskless pattern electrodeposition can be performed at high speed using a plating solution containing metal ions that are likely to generate hydrogen. For example, a metal pattern such as nickel, which has conventionally been difficult to form at high speed, can be easily formed on a conductive substrate.

(Example 1, Comparative Example 1)
[1. Water treatment of diaphragm]
A hydrous treatment was performed on a perfluorosulfonic acid-based cation exchange membrane (thickness: 183 μm, size: 30 mm × 30 mm). The water treatment conditions are
(A) Immersion in pure water at 80 ° C. for 2 hours + Immersion in pure water at room temperature overnight (Example 1) or
(B) Immersion in room temperature pure water overnight (Comparative Example 1),
It was.

[2. Test method and results]
[2.1. Small angle X-ray scattering (SAXS) spectrum]
The membrane was sandwiched with a Kapton (registered trademark) bag while containing water, and the scattering spectrum was measured by the SAXS method. FIG. 3 shows SAXS profiles of the diaphragms obtained in Example 1 and Comparative Example 1. In FIG. 3, the SAXS profile in the dry atmosphere of Comparative Example 1 is also shown. The peak values derived from the hydrophilic structure (q _peak ) are 0.14Å ^-1 (1.4 nm ^-1 ) (Example 1) or 0.17 ^{-1 -1} (1.7 nm ^-1 ) (comparative example), respectively. 1).

[2.2. Ni constant current electrodeposition]
[1. Then, Ni was subjected to constant current electrodeposition of Ni under the conditions of room temperature and 200 mA / cm ² × 30 minutes using a DC constant current power source with an upper limit voltage of 70V. A platinum plate having a size of 2 cm × 2 cm and a thickness of 300 μm was used for the anode and the sample electrode (cathode), respectively. The plating solution (anode chamber solution and cathode chamber solution) contains 1 M / L NiSO ₄ and 0.5 M / L CH ₃ COOH, and the pH is adjusted to 3.0 with a 20 wt% NaOH aqueous solution. Was used. The concentration of NaOH in the plating solution was 0.08 M / L. The amounts of the anode chamber solution and the cathode chamber solution were 17.5 g, respectively. Further, both the anode chamber and the cathode chamber were electrodeposited without stirring.

After electrodeposition, the liquid volume in both chambers was measured. The rate of increase of the cathodic chamber liquid (unit time, the amount of increase per unit cross-sectional area) was determined, and this was taken as the water transfer rate by electroosmosis.
The Ni ²⁺ concentrations of the anode chamber solution and the cathode chamber solution were determined by a simple spectrophotometric analyzer: Digital Pack Test (DPM-NiD) manufactured by Kyoritsu Chemical. The concentration ratio C (cathode chamber solution Ni ²⁺ concentration / anode chamber solution Ni ²⁺ concentration) was calculated, the electrodeposition efficiency was corrected, and the Ni ²⁺ ion transport number (αNi ²⁺ ) was calculated.

Table 1 shows the results. The peak value (q _peak ) of Example 1 was lower than that of Comparative Example 1. Moreover, in Example 1, the transport number of Ni ²⁺ ions (αNi ²⁺ ) and the water transfer rate were larger than those of Comparative Example 1, and it was confirmed that a hydrophilic portion was developed.

[2.3. Ni plating test]
Ni plating was performed using the electroplating cell shown in FIG. The anode chamber liquid 20 includes [2.2. ] Was used. An aluminum plate plated with Au was used for the cathode 26, and a Pt / Ti porous body was used for the anode 22. Anode 22 / diaphragm / cathode 26 were laminated and pressurized at 0.5 MPa. In this state, constant current electrodeposition was performed under conditions of 10 mA / cm ² × 10 minutes.
When the diaphragm of Example 1 was used, normal Ni electrodeposition was possible. On the other hand, when the diaphragm of Comparative Example 1 was used, a green precipitate thought to be nickel hydroxide was generated on the electrodeposited surface, and a metallic glossy film could not be obtained.

(Examples 2-3)
[1. Swelling treatment of diaphragm + water treatment (1)]
The cation exchange membrane made of the same material as in Example 1 was subjected to swelling treatment. Ethanol (Example 2) or butyl cellosolve (Example 3) was used as the hydrophilic organic solvent. The swelling treatment conditions were room temperature and 10 minutes. Further, the undried film after the swelling treatment was subjected to a water treatment at 80 ° C. for 2 hours.

[2. Test method and results]
[2.1. SAXS spectrum measurement and Ni constant current electrodeposition]
Using the obtained diaphragm, the SAXS spectrum measurement and Ni constant current electrodeposition were performed in the same manner as in Example 1. FIG. 3 shows SAXS profiles of the diaphragms obtained in Examples 2 and 3. Table 2 shows the results. Table 2 also shows the results of Comparative Example 1.
From Table 2, when the diaphragm is subjected to swelling treatment and water treatment, the peak value (q _peak ) is further reduced, and the Ni ²⁺ ion transport number (αNi ²⁺ ) and the water transfer rate are further improved. I understand that

[2.2. Ni plating test]
Using the obtained diaphragm, a Ni plating test was conducted in the same manner as in Example 1. However, the plating was performed by constant current electrodeposition at 100 mA / cm ² × 10 minutes.
As described above, when the diaphragm of Comparative Example 1 was used, a green precipitate that appeared to be nickel hydroxide was generated on the electrodeposition surface, and a metallic glossy film could not be obtained. On the other hand, when the diaphragms of Examples 2 and 3 were used, normal Ni electrodeposition was possible.

(Examples 4-5, Comparative Examples 2-4)
[1. Swelling treatment of membrane + water treatment (2)]
As the diaphragm, a perfluorosulfonic acid cation exchange membrane (film thickness: 50 μm) made of a material different from that of Example 1 was used. This diaphragm is an unreinforced cast film. The diaphragm was subjected to swelling treatment. Butyl cellosolve was used as the hydrophilic organic solvent. The swelling treatment conditions were room temperature and 10 minutes. Further, the hydrated membrane after the swelling treatment was subjected to water treatment at 80 ° C. × 2 hr (Example 4). Moreover, only the water-containing process was performed with respect to the unreinforced film | membrane used in Example 4 on the same conditions as the comparative example 1 (comparative example 2).

As the diaphragm, a PTFE reinforcing film (film thickness: 50 μm) containing a perfluorosulfonic acid resin of the same material as in Example 4 and a fiber structure made of PTFE was used. This diaphragm was subjected to swelling treatment and water-containing treatment under the same conditions as in Example 4 (Example 5). In addition, the reinforcing membrane used in Example 5 was subjected to water treatment under the same conditions as Comparative Example 1 (Comparative Example 3).
Furthermore, a hydrous treatment of 80 ° C. × 2 hr was performed on a hydrocarbon-based cation exchange membrane (film thickness: 10 μm) (Comparative Example 4).

[2. Test method]
[2.1. SAXS spectrum measurement and Cu constant current electrodeposition]
Using the obtained diaphragm, the SAXS spectrum was measured in the same manner as in Example 1. In addition, constant current electrodeposition was performed in the same manner as in Example 1. However, 1M CuSO ₄ was used for the plating bath. The Cu electrodeposition conditions were 200 mA / cm ² × 10 minutes. Table 3 shows the results.
In Comparative Example 4, a peak in the vicinity of 0.17Å ^-1 (1.7 nm ^-1 ) derived from the hydrophilic portion structure was not observed. On the other hand, the peak values (q _peak ) of Examples 4 and 5 were lower than those of Comparative Examples 2 and 3, respectively. The transport number (αCu ²⁺ ) and water transfer rate of Cu ²⁺ ions of Examples 4 and 5 were also larger than those of Comparative Examples 2 and 3, respectively, and it was confirmed that the hydrophilic portion was developed. .

[2.2. Cu plating test]
A plating test was conducted in the same manner as in Example 1 using the obtained diaphragm. However, [2.1. The Cu plating solution produced in the above was used. The plating was performed by constant current electrodeposition at 20 mA / cm ² × 10 minutes.
When the diaphragms of Examples 4 and 5 were used, normal Cu electrodeposition was possible. On the other hand, when the diaphragms of Comparative Examples 2 and 3 were used, the film and the electrodeposition surface were bitten and closely adhered, and normal electrodeposition could not be performed. Further, in Comparative Example 4, although the moisture content of the diaphragm was large and the moisture treatment was performed at 80 ° C. × 2 hr, the membrane and the electrodeposition surface were bitten and adhered normally. Electrodeposition could not be performed.

(Examples 6 to 8, Comparative Example 5)
[1. Swelling treatment of diaphragm + water treatment (3)]
The cation exchange membrane made of the same material as in Example 1 was subjected to swelling treatment. Examples of the hydrophilic organic solvent include (a) butyl cellosolve (Example 6), (b) butyl cellosolve containing 2 wt% saccharin (Example 7), or (c) 10% of membrane acid groups corresponding to quaternary ammonium groups. Butyl cellosolve (Example 8) to which hexadecyltrimethylammonium bromide (HDTMA) was substituted was used. The swelling treatment conditions were room temperature and 10 minutes. Further, the undried film after the swelling treatment was subjected to a water treatment at 80 ° C. for 2 hours.
In addition, a cation exchange membrane made of the same material as in Example 1 was subjected to an ion exchange treatment overnight at room temperature in an aqueous solution to which the same amount of HDTMA as in Example 8 was added (Comparative Example 5).

[2. Test method]
Using the obtained diaphragm, the SAXS spectrum measurement and Ni constant current electrodeposition were performed in the same manner as in Example 1. Further, a Ni plating test was conducted in the same manner as in Example 1. However, the electrodeposition conditions for Ni were 100 mA / cm ² × 10 minutes. Table 4 shows the results.
In Table 4, the results of Comparative Example 1 are also shown. In Table 4, “◯” indicates that a film having a normal metallic luster was obtained. Further, “x” represents that a green precipitate that seems to be nickel hydroxide was generated, and a film having a metallic luster was not obtained.
From Table 4, when the diaphragm is subjected to swelling treatment and water-containing treatment, even when saccharin or HDTMA is added during the swelling treatment, a good water-containing structure is maintained, and hydroxide at the electrodeposition interface It was shown that electrodeposition is possible without causing precipitation of.

(Example 9, Comparative Example 6)
[1. Swelling treatment of diaphragm + water treatment (4)]
The cation exchange membrane made of the same material as in Example 1 was subjected to swelling treatment. T-Butyl alcohol was used as the hydrophilic organic solvent. The swelling conditions were room temperature and 10 minutes. Next, water treatment at 80 ° C. × 2 hr was performed on the diaphragm after swelling treatment without drying the diaphragm (Example 9).
After carrying out the swelling treatment in the same manner as in Example 9, a vacuum drying treatment at 190 ° C. × 2 hr was carried out to remove the organic solvent. Next, a water treatment was performed in the same manner as in Example 9 (Comparative Example 6).

[2. Test method and results]
[2.1. SAXS spectrum measurement and Ni constant current electrodeposition]
Using the obtained diaphragm, the SAXS spectrum measurement and Ni constant current electrodeposition were performed in the same manner as in Example 1.
In the case of Example 9, q _peak = 0.13Å ^-1 (1.3 nm ^-1 ), and the water movement rate was 16.7 µg / cm ² / min. On the other hand, in the case of Comparative Example 6, q _peak = 0.17Å ^-1 (1.7 nm ^-1 ), water transfer rate = 12.0 µg / cm ² / min, and no development of the hydrophilic portion structure was observed.

[2.2. Ni plating test]
Using the obtained diaphragm, a Ni plating test was conducted in the same manner as in Example 1. However, the plating was performed by constant current electrodeposition at 100 mA / cm ² × 10 minutes.
When the diaphragm of Example 9 was used, a film having a metallic luster was obtained. On the other hand, when the diaphragm of Comparative Example 6 was used, a green precipitate that appeared to be nickel hydroxide was generated on the electrodeposition surface, and a metallic glossy film could not be obtained.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention.

  The electroplating cell according to the present invention can be used for forming various metal films.

DESCRIPTION OF SYMBOLS 10 Electroplating cell 12 Anode chamber 14 Cathode chamber 16 Diaphragm 20 Anode chamber liquid 22 Anode 24 Cathode chamber liquid 26 Cathode 28 Metal film

Claims (6)

An anode chamber for holding the anode chamber liquid;
A diaphragm for isolating the anode chamber and the cathode,
The diaphragm is
It consists of a perfluorosulfonic acid-based cation exchange membrane, and
In scattering spectrum measured in water at room temperature by small-angle X-ray scattering method, electroplating peak value derived from the hydrophilic portion structure (q _peak) consists 0.14Å ^-1 (1.4nm ^-1) or less is intended cell.   The electroplating cell according to claim 1, wherein the electroplating cell is not provided with a cathode chamber for holding the cathode chamber solution. The electroplating cell according to claim 1 , wherein the diaphragm includes a membrane reinforcing structure. The electroplating cell according to any one of claims 1 to 3 , wherein the diaphragm includes a plating additive.   The diaphragm has the peak value (q _peak ) Is 0.12cm ^-1 (1.2 nm ^-1 The electroplating cell according to any one of claims 1 to 4, wherein: The manufacturing method of the metal membrane | film | coat which forms a metal membrane | film | coat on the surface of the said cathode using the electroplating cell of any one of Claim 1-5 .

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