JP5708182B2 - Method for forming metal film using solid electrolyte membrane - Google Patents

Description

  The present invention relates to a simple metal film forming method, and more particularly to a metal pattern forming method.

  Metal plating technology is an important technology in electronics, rust prevention and decoration. Therefore, various metal plating techniques have been put into practical use in various fields.

  Patent Document 1 discloses a metal plating method by electroplating. This metal plating method is characterized in that the plating bath used is a gel electrolyte obtained by adding a gelling agent to an organic solvent containing metal ions. Specifically, the method involves immersing a substrate to be plated and a metal plate in this plating bath, electrically connecting the substrate and the metal plate, and applying a predetermined voltage so that the metal ions are to be plated. It is reduced on the surface and deposits a metal film.

  However, the metal plating method described in Patent Document 1 has a problem in that a large amount of waste liquid is generated because cleaning is essential to remove residues on the surface of the metal film after plating. In addition, in order to control the plating deposition rate and the plating surface shape, various parameters such as pH, temperature, metal ion concentration, and stabilizer concentration of the plating solution must be controlled, resulting in a complicated plating solution composition. There was a problem that it was not economical and complicated liquid management was required. Furthermore, when a metal pattern is formed by plating, it is necessary to etch away unnecessary portions after depositing a plating film on the entire surface of the substrate, which requires a great number of steps, which is not economical. .

  Patent Document 2 describes a method for producing a transparent conductive film laminate formed by laminating and forming a transparent conductive film on a polyimide resin layer. In this method, as a middle step, a) a polyamic acid solution is applied on the substrate and dried to form a polyamic acid layer, and b) the polyamic acid layer is impregnated with a solution containing silver ions. A step of attaching silver ions to the polyamic acid layer, and c) a step of reducing silver ions attached to the polyamic acid layer to precipitate metallic silver, whereby a silver layer is formed on the polyamic acid layer. Is forming. Here, the precipitation of metallic silver in the above step c) is specifically performed by a wet reduction method using a reducing agent or a photoreduction method by ultraviolet irradiation.

  Patent Document 3 describes a method of forming an inorganic thin film on a substrate. The method includes a step of forming a resin layer having a cation exchange group on an inorganic thin film forming site on a substrate, a step of contacting a resin layer having a cation exchange group and a metal ion to form a metal salt, The metal salt is subjected to a reduction reaction or a reaction with an active gas to deposit an inorganic substance on the surface of the resin layer. When the metal is deposited as an inorganic substance by the method, the reduction reaction is specifically performed by a wet reduction method using a reducing agent.

  However, the reduction methods used in the methods disclosed in Patent Documents 2 and 3 are disadvantageous in that they are not economical and have a limited range of application because they require special chemicals, equipment, and atmosphere control. .

  As described above, the conventional metal film forming method has not yet been satisfactory from the viewpoint of simplicity, particularly in the case of forming a metal pattern, regarding the plating solution composition, post-treatment, and the like.

JP 2005-248319 A JP 2011-11493 A JP 2008-214684 A

  An object of the present invention is to provide a simple metal film forming method, particularly a metal pattern forming method.

The present invention includes the following inventions.
(1) A step of depositing metal on the cathode substrate by reducing the metal ions by applying a voltage between the cathode substrate and the anode substrate arranged with the solid electrolyte and the solid electrolyte membrane containing metal ions interposed therebetween. A metal film forming method comprising a).
(2) The method for forming a metal film as described in (1) above, wherein the solid electrolyte has a cation exchange group.
(3) The metal film forming method as described in (1) or (2) above, wherein the substrate is a metal or a metal oxide.
(4) The metal film forming method according to any one of (1) to (3), wherein the anode base material has a pattern shape.
(5) The metal film forming method according to any one of (1) to (4), further including a step c) of adding water and / or alcohols to the solid electrolyte membrane before the step a).
(6) The metal film forming method according to any one of (1) to (4), further including a step b) of forming a solid electrolyte membrane on the cathode base material before the step a).
(7) The metal film forming method according to (6), further including a step c) of adding water and / or alcohol to the solid electrolyte membrane before the post step a) of the step b).

  The metal film forming method of the present invention is excellent in simplicity.

FIG. 1 is a diagram showing an embodiment of the present invention. FIG. 2 is a diagram illustrating manufacturing steps of the metal film forming method according to the first embodiment. 3 is a diagram showing an optical micrograph of a metal film obtained by the metal film forming method of Example 1. FIG.

  In the metal film forming method of the present invention, a voltage is applied to a solid electrolyte film containing a solid electrolyte and metal ions to reduce the metal ions and deposit a metal on the cathode substrate. Thereby, when forming a metal pattern especially, a metal film can be easily formed on a base material with respect to post-treatment and the like.

  Examples of the metal to be precipitated in the present invention include titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, iron, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver, gold, zinc, Examples thereof include cadmium, aluminum, gallium, indium, silicon, germanium, tin, arsenic, antimony, bismuth, selenium, and tellurium. From the viewpoint of specific resistance, silver, copper, gold, nickel, platinum, and palladium are preferable, and silver, copper, gold, and nickel are particularly preferable.

  The solid electrolyte used in the present invention is not particularly limited as long as it can move the metal ions when a voltage is applied, but a resin having a cation exchange group (such as a carboxyl group and / or a sulfone group). Examples thereof include carboxyl group-containing acrylic resins, carboxyl group-containing polyester resins, carboxyl group-containing polyamide resins, and polyamic acid resins (polyamic acid resins). From the viewpoints of heat resistance, chemical resistance and dielectric constant, polyamic acid resins and polyester resins are preferable, and polyamic acid resins are particularly preferable. These resins can be used alone or in combination of two or more.

  The polyamic acid-based resin is a precursor of a condensation type polyimide-based resin obtained by a reaction between a tetracarboxylic acid anhydride and a diamine, and is a ring-opening resin having a free carboxyl group, such as an acid anhydride. It may be a resin using a group tetracarboxylic anhydride (such as pyromellitic anhydride).

  Examples of the tetracarboxylic acid anhydride include alicyclic tetracarboxylic acid anhydrides (such as cyclohexanetetracarboxylic acid anhydride) and aromatic tetracarboxylic acid anhydrides (such as pyromellitic anhydride and naphthalenetetracarboxylic acid anhydride). Carboxylic anhydrides; biphenyl tetracarboxylic anhydrides, biphenyl ether tetracarboxylic acids such as 4,4′-oxydiphthalic anhydride (ODPA, 3,4,3 ′, 4′-diphenyl ether tetracarboxylic anhydride) Bisphenol tetracarboxylic acid anhydrides such as anhydrides, benzophenone tetracarboxylic acid anhydrides, biphenylalkanetetracarboxylic acid anhydrides, biphenylsulfone tetracarboxylic acid anhydrides; 4,4 ′-(4,4′- Isopropylidenediphenoxy) bis (phthalic anhydride) And biphenyl ether tetracarboxylic acid anhydrides having a biphenylalkane skeleton such as BPADA, 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] propane acid anhydride) and the like. Are aliphatic diamines (e.g., linear or branched alkylene diamines such as ethylene diamine, propylene diamine, 1,4-butylene diamine, hexamethylene diamine, and trimethyl hexamethylene diamine, polyether diamines) and alicyclic diamines. (Mensendiamine, isophoronediamine, xylylenediamine hydrogenated product, bis (aminocyclohexyl) alkanes such as diaminodicyclohexylmethane, bis (4-amino-3-methylcyclohexyl) methane, etc.), aromatic diamines such as phenylene Amines, xylylenediamines, bis (aminophenyl) ethers such as 4,4'-diaminodiphenyl ether, bis (aminophenyl) ketones such as 4,4'-diaminodiphenyl ketone, 4,4'-diaminodiphenyl Bis (aminophenyl) sulfones such as sulfone, bis (aminophenyl) alkanes such as 1,1-bis (4-aminophenyl) methane, bis (amino such as 1,3-bis (2-aminophenyl) benzene Phenyl) benzenes, etc.] These acid anhydrides and diamines can be used alone or in combination of two or more, and the tetracarboxylic acid anhydrides include aromatic tetracarboxylic acid anhydrides (pyromellitic anhydride). Etc.) are often used, and the diamine is an aromatic diamine (bis (aminophenyl) A And bis (aminophenyl) ketones, bis (aminophenyl) alkanes, etc.) are often used.

  The base material used in the present invention is not particularly limited as long as it has conductivity, but metal oxides such as indium tin oxide (ITO), indium zinc oxide, indium oxide, tin oxide, iridium oxide, and osmium oxide are used. Examples include a thin film, graphite, a doped silicon thin film, a metal thin film, and the like. Examples of the metal include copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, platinum, tin, zirconium, tantalum, titanium, lead, magnesium, manganese, and alloys thereof. As the cathode substrate, ITO, tin oxide, copper, and aluminum are preferable from the viewpoint of material cost, and ITO, tin oxide, and copper are particularly preferable. As the anode base material, platinum, gold and iridium oxide are preferable from the viewpoint of oxidation resistance, and platinum and iridium oxide are particularly preferable. A preferable combination of the cathode base material and the anode base material is ITO and platinum, tin oxide and platinum from the viewpoint of material cost and stability.

  The thickness of the substrate is preferably 0.1 to 5 μm, particularly 0.5 to 1 μm when a metal oxide is used, and 5 to 1000 μm, particularly 10 to 100 μm when a metal is used. Preferably there is.

  In the method of the present invention, when a substrate having a pattern shape is used as the anode substrate, a metal pattern can be formed on the cathode substrate. The metal pattern that can be formed according to the present invention is not particularly limited as long as it is a shape in which a current flows, and examples thereof include a mesh, a solid, a comb, and other various electric circuit patterns.

  The present invention includes a step (a) of reducing metal ions and precipitating metal on the cathode substrate by applying a voltage between the cathode substrate and the anode substrate disposed with the solid electrolyte membrane interposed therebetween. When a metal ion in the solid electrolyte membrane is reduced and deposited as metal on the cathode substrate surface in the vicinity of the cathode substrate that is the substrate to be plated by applying a voltage, a gradient of the metal ion concentration in the solid electrolyte membrane occurs. To do. As a result of metal ions moving through the solid electrolyte membrane using this concentration gradient as a driving force, metal deposition on the surface of the cathode substrate proceeds continuously. Here, the voltage applied between both electrodes is preferably 0.01 to 100 V, and particularly preferably 0.05 to 2 V. The voltage is preferably applied at 0 to 100 ° C. (preferably 10 to 25 ° C.) and 0.01 to 100 minutes (preferably 0.05 to 5 minutes).

  The present invention may include a step b) of forming a solid electrolyte membrane containing a solid electrolyte and metal ions on the cathode substrate before the step a). The solid electrolyte membrane can be formed by coating a cathode base material with a solid electrolyte and then adding metal ions. Alternatively, the solid electrolyte membrane can also be formed by coating the cathode substrate with a mixture containing a solid electrolyte and metal ions.

  The metal ions are added to the solid electrolyte in the form of an aqueous solution, that is, an aqueous solution of a water-soluble metal compound. The water-soluble metal compound may be, for example, a halide (chloride or the like), an inorganic acid salt (sulfate such as copper sulfate or nickel sulfate, a nitrate such as silver nitrate), an organic acid salt (acetate or the like), and the like. . From the viewpoint of material cost, it is preferable to use an inorganic acid salt. These water-soluble metal compounds can be used alone or in combination of two or more. The aqueous solution containing metal ions contains a water-soluble organic solvent (alcohols, etc.), a pH adjuster (base, amines such as ethylenediamine, etc .; acid, eg hydrochloric acid, etc.), a buffer, etc., if necessary. Also good.

  The concentration of the metal ion in the aqueous solution is not particularly limited, and is, for example, 0.01 to 1000 mM, preferably 0.05 to 100 mM.

  The cathode substrate may be coated with a solid electrolyte or a mixture containing a solid electrolyte and metal ions by a conventional film forming method (or coating method) such as a dipping method, a spray coating method, a spin coating method, a roll coating method, or the like. It can be performed by coating. The same method can also be used when metal ions are added as an aqueous solution of a water-soluble metal compound after the cathode substrate is coated with a solid electrolyte.

  The coating by the dipping method is preferably performed at a contact time of 0.01 to 100 minutes (preferably 0.05 to 10 minutes) at 0 to 100 ° C. (preferably 5 to 20 ° C.).

  Drying may be performed after coating. In this case, under reduced pressure (for example, 0.01 to 1 atm), at 0 to 100 ° C. (preferably 5 to 25 ° C.), for 1 to 100 minutes (preferably 5 to 30 minutes). Preferably it is done.

  The thickness of the solid electrolyte membrane is not particularly limited, and is, for example, 0.01 to 100 μm, preferably 0.1 to 10 μm.

  The present invention further includes step c) of adding water and / or alcohol to the solid electrolyte membrane before step a), before step a), if step b) is included, before step a). You may go out. Thereby, the moving speed of ions in the solid electrolyte membrane can be improved. Examples of the alcohols include monohydric alcohols such as methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol and octanol, such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1 , 3-butanediol, 1,5-pentanediol and hexylene glycol and other dihydric alcohols such as glycerin, trimethylolethane, trimethylolpropane, 5-methyl-1,2,4-heptanetriol and 1,2, Mention may be made of trihydric alcohols such as 6-hexanetriol. Of these, methanol and ethanol are preferred. What consists of 1 type, or 2 or more types of mixtures chosen from water and said alcohol can be used. In this case, the ratio of water and alcohols is preferably 0.01 to 1, and particularly preferably 0.01 to 0.5.

  The present invention may further include a step d) of removing the solid electrolyte membrane after forming the metal film by the step a). For example, the solid electrolyte membrane can be physically removed by a simple method such as peeling. When ITO or tin oxide is used as the cathode base material, the peelability of the solid electrolyte membrane is particularly good.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to this.

[Example 1]
A polyamic acid varnish [manufactured by Hitachi Chemical DuPont Microsystems, PIX] is spin-coated on an indium tin oxide (ITO) glass substrate [manufactured by Nippon Sheet Glass Co., Ltd., glass with high-temperature film-forming ITO], and drying treatment is performed at 60 ° C. For 5 hours. This ITO substrate was immersed in a 200 mM aqueous silver nitrate solution at room temperature for 5 minutes to adsorb silver ions in the polyamic acid film and dried. Water was dropped on the polyamic acid film, and a platinum grid having a mesh shape was installed thereon. Gold electrodes were placed on the platinum grid and the ITO substrate, and a voltage of 2 V was applied for 3 minutes. When the gold electrode and the platinum grid were removed, it was confirmed that a mesh-shaped silver film was deposited at the interface between the polyamic acid film and the ITO base material. Next, the polyamic acid film was peeled off to obtain an ITO base material that was pattern-plated with silver. This manufacturing process is shown in FIG. The obtained metal film was observed using an optical microscope.

  An optical micrograph of the metal film obtained by the metal film formation method of Example 1 is shown in FIG. 3 that the metal film obtained by the metal film forming method of the present invention is a continuous film having a shape corresponding to the metal mask.

  The metal film forming method of the present invention can be preferably applied to pattern plating on an electronic circuit board and silicon semiconductor internal electrodes.

Claims (5)

A) a step of depositing metal on the cathode substrate by reducing the metal ions by applying a voltage between the cathode substrate and the anode substrate disposed between the solid electrolyte and the solid electrolyte membrane containing the metal ion. A metal film forming method comprising :
Before step a), further comprising step b) of forming a solid electrolyte membrane on the cathode substrate;
The solid electrolyte is a resin having a carboxyl group,
The substrate is indium tin oxide (ITO), indium zinc oxide, indium oxide, tin oxide, iridium oxide, osmium oxide, graphite and doped silicon, copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, The above method, which is at least one selected from the group consisting of gold, platinum, tin, zirconium, tantalum, titanium, lead, magnesium, manganese, and alloys thereof . The metal film forming method according to claim 1, wherein the resin having a carboxyl group is a polyamic acid resin. The method for forming a metal film according to claim 1 or 2, wherein the solid electrolyte membrane has a thickness of 0.01 to 100 µm.   The metal film forming method according to claim 1, wherein the anode base material has a pattern shape. Prior to step a) after step b), further look including the step c) adding water and / or alcohols to the solid electrolyte membrane,
Alcohols are methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,5 -At least one selected from the group consisting of pentanediol, hexylene glycol, trimethylolethane, trimethylolpropane, 5-methyl-1,2,4-heptanetriol and 1,2,6-hexanetriol , The metal film formation method of any one of Claims 1-4 .

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