JP2009277793A - Substrate for wiring and wiring substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate for wiring and a wiring substrate such that manufacturing steps are greatly decreased, a film manufacturing time of a conductive layer is shortened, larger area is easily obtained, and various substrates have conductive layers. <P>SOLUTION: The substrate for wiring includes a base and a conductive layer formed on the base by using a wet plating method. The base is selected from a group of glass, plastic, and silicon wafers, and the substrate for wiring includes the conductive layer formed substantially entirely over the base. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wiring board and a wiring board. Since the wiring substrate of the present invention forms a conductive layer directly on a substrate such as glass using a wet plating method, the manufacturing process can be greatly reduced, and the time for forming the conductive layer can be shortened. In addition, the area can be easily increased, and a conductive layer can be provided for various substrates. Moreover, since various metal seed | species can be selected, various performance derived from metal seed | species, such as resistance value and a melting temperature, can be provided. Further, when glass or plastic whose wiring substrate is transparent is used, a transparent wiring substrate can be obtained by partially removing the conductive layer of the wiring substrate.

  In recent years, the demand for transparent conductive films has been growing mainly in displays and the like, and there is an urgent need to form a transparent conductive film having high transparency and low resistance at low cost. From the viewpoint of the conductive material of the transparent conductive film, metal conducts electricity well but reflects light (visible light), and graphite also conducts electricity but absorbs visible light and does not show transparency. Can be satisfied, but it is difficult to ensure transparency. Usually, a wide gap semiconductor is used to produce a transparent film that conducts electricity well. In the wide gap semiconductor, since the energy gap corresponds to the ultraviolet region, it is transparent and can exhibit conductivity without absorbing visible light. The conduction mechanism of the wide gap semiconductor is based on the movement of carrier electrons, and the density of carrier electrons is considerably lower than that of metal, so that visible light is not reflected. Therefore, a film made of a wide gap semiconductor transmits visible light well, but a film having a high carrier electron density tends to reduce the transmittance in the infrared region because the carrier electrons reflect infrared light.

  The transparent conductive film obtained in this way is transparent and uses a unique property of conducting electricity well, transparent heaters, electrodes for display elements of notebook computers and mobile phones, electrodes for solar cells, electrodes for plasma display panels The demand is expected to increase further in the future. Substances often used as a transparent conductive film material are indium tin oxide (ITO), zinc oxide (ZnO), tin oxide (SnO), and the like, and at present, the ITO film is a low resistance material.

  In general, ITO transparent conductive films are formed on plastics and glass by various methods such as sputtering, vacuum deposition, sol-gel method, cluster beam deposition, and PLD, and are put on the market.

  However, such a transparent conductive film often uses a vacuum environment for film formation, and various complicated operations are required to create and maintain the vacuum environment. Moreover, a large vacuum environment is required to produce a large transparent conductive film, but it is very difficult to stably maintain the high vacuum condition in the large vacuum environment.

  For example, JP-A-2001-11642 (Patent Document 1) discloses a transparent conductive zinc oxide film having a high visible light transmittance and a low specific resistance value, which is obtained by forming a zinc oxide film by a wet plating method. It is disclosed.

  Since this transparent conductive zinc oxide film is formed by a wet plating method, it is excellent in that it can be easily formed in a large area without requiring a conventional vacuum environment.

  Japanese Patent Laid-Open No. 2006-310401 (Patent Document 2) discloses a metal layer formed by a dry film forming method on one or both sides of a printed wiring board made of a polyimide resin film, and electroplating or non-plating on the metal layer. A printed wiring board manufacturing method is disclosed in which an etching pattern is formed on a printed wiring made of a metal-coated polyimide resin film having a conductive second metal layer formed by electrolytic plating.

  In this printed circuit board, copper is coated on a polyimide resin film by a metallization method, and a copper metal layer of about 8 microns in total is formed thereon by using a plating method, and an alkaline etching solution is formed from the metal layer. A comb pattern with a pitch of 50 μm is formed. In this method, a polyimide resin film is provided with a metal layer formed by a dry film forming method and a conductive second metal layer formed by electroplating or electroless plating on the metal layer. By ensuring the conductivity on the plastic film and using an alkali metal hydroxide during the etching, the residual problem of metal components, which has been a problem in conventional pattern processing, and the reliability in recent microfabrication patterns It is excellent in that the disappearance can be solved.

JP 2001-11642 A JP 2006-310401 A

  In the metal oxide wet plating disclosed in Japanese Patent Application Laid-Open No. 2001-11642, the obtained film is transparent, but the wet plating takes a long time of several hours, and the problem of poor film forming work efficiency remains. Has been. In addition, in the method of forming a metal layer carrying a conductive layer on a polyimide resin film disclosed in JP-A-2006-310401 using both a dry method and a wet method, a dry method and a wet method are used. However, the dry method creates a vacuum environment and deposits a metal layer by vapor deposition or sputtering, which requires complicated work and labor to create and maintain the vacuum environment. The problem of areaization remains.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have invented a wiring board and a wiring board that achieve the object of the present invention.

That is, the present invention is as follows.
(1) A wiring substrate comprising a conductive layer formed on a base material and a wet plating method.
(2) The wiring substrate according to (1), wherein the base material is a base material selected from the group consisting of glass, plastic, and a silicon wafer, and a conductive layer is formed on substantially the entire surface of the base material.
(3) The wiring board according to (1) or (2), wherein the wet plating method is an electroless plating method.
(4) Any one of (1) to (3), wherein the metal species used for the conductive layer is at least one selected from the group consisting of gold, silver, copper, zinc, nickel, tin, and chromium. The printed wiring board.
(5) The wiring substrate according to any one of (1) to (4), wherein the base material is transparent.
(6) A wiring board having wiring created by partially removing the conductive layer from the wiring board according to any one of (1) to (5).
(7) A current collecting electrode comprising the wiring board according to (6).
(8) The collector electrode according to (7), which is a collector electrode of a solar cell.

  Since the wiring substrate of the present invention forms a conductive layer directly on a substrate such as glass using a wet plating method, the manufacturing process can be greatly reduced, and the time for forming the conductive layer can be shortened. In addition, the area can be easily increased, and a conductive layer can be provided for various substrates. Moreover, since various metal seed | species can be selected, various performance derived from metal seed | species, such as resistance value and a melting temperature, can be provided. Further, when glass or plastic whose wiring substrate is transparent is used, a transparent wiring substrate can be obtained by partially removing the conductive layer of the wiring substrate. The present invention provides a wiring board and a wiring board having such merits.

The present invention will be described in detail below.
<Wiring board, wiring board>
The wiring substrate as used in the present invention refers to a substrate provided with a conductive layer on the surface of a base material for drawing wiring, and the surface may be one or both sides of the base material. In order to freely draw the wiring, the conductive layer is preferably provided on almost the entire surface. The wiring board of the present invention refers to a wiring drawn by partially removing the conductive layer from the wiring board of the present invention.
<Removal>
The partial removal of the conductive layer from the wiring substrate of the present invention means that the conductive layer provided on almost the entire surface is partially removed by a known method in order to draw the wiring. Known methods include chemical etching with acid or alkali materials, physical etching with laser or mechanical methods, etc., but any method can remove the conductive layer created by wet plating method. There is no hindrance.
<Base material>
Examples of the substrate used in the present invention include glass, plastic, and silicon wafer. Glass is produced by mixing silicon dioxide as the main component and various metal compounds as subcomponents as powder, and rapidly cooling those that have been melted at high temperature to form a liquid state. Examples include plate glass and heat-resistant glass. In addition, as plastic, thermosetting resins such as phenol resin, epoxy resin, melamine resin, urea resin, unsaturated polyester resin, alkyd resin, polyurethane resin, thermosetting polyimide resin, high density, medium density, low density, etc. Various polyethylene resins, polypropylene resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl acetate resins, acrylonitrile butadiene styrene resins, acrylic resins, polyamide resins such as nylon, polyacetal resins, polycarbonate resins, polyphenylene ether resins And thermoplastic resins such as polybutylene terephthalate resin, polyethylene terephthalate resin, and cyclic polyolefin (COP). Furthermore, a silicon wafer that is a thin disk of high-purity silicon can be used.
<Transparent substrate>
In particular, among the above-mentioned base materials, a base material that is transparent regardless of the thickness, or a base material having a transparency of about 10 mm in thickness and a transmittance of 50% or more, is described above by using a wet plating method. A wiring board having transparency and conductivity by forming a wiring board by forming a conductive layer on substantially the entire surface of a substrate and partially removing the conductive layer of the wiring board. Is obtained. The wiring board thus obtained can also be used as a substrate with a transparent conductive film. Normally, metal as a conductive material of a transparent conductive film can conduct electricity well, but reflects light (visible light), and graphite also conducts electricity but absorbs visible light and does not show transparency, so conductivity can be satisfied. Although it is possible, it is difficult to ensure transparency. In general, a wide gap semiconductor is used to produce a transparent film that conducts electricity well. In the wide gap semiconductor, since the energy gap corresponds to the ultraviolet region, it is transparent and can exhibit conductivity without absorbing visible light. The conduction mechanism of the wide gap semiconductor is based on the movement of carrier electrons, and the density of carrier electrons is considerably lower than that of metal, so that visible light is not reflected. Therefore, a film made of a wide gap semiconductor transmits visible light well, but a film having a high carrier electron density tends to reduce the transmittance in the infrared region because the carrier electrons reflect infrared light.

In the substrate with a transparent conductive film of the present invention, since the light transmitting portion and the wiring portion exhibiting conductivity exist separately, the wavelength distribution of the transmitted light is not changed. Therefore, a high transmittance in the near-infrared region, which has been difficult with a transparent conductive film using a wide gap semiconductor, can be exhibited.
<Wet plating>
In the present invention, the wet plating method is preferable from the viewpoint of easy area enlargement and uniform coating of a metal thin film. The wet plating method is roughly classified into an electrolytic plating method and an electroless plating method. Either method may be used in the present invention, but the electroless plating method is preferable because a surface treatment in which a metal thin film is coated on glass, plastic or the like that does not conduct electricity can be performed. The wet plating referred to in the present invention refers to a surface treatment in which a substrate surface is coated with a metal thin film in a liquid, and the wet plating method refers to a method therefor. In the present invention, the surface of the substrate is coated with a metal thin film using a known wet plating, and a conductive layer is provided. The electroless plating method is usually a method of fixing a nucleus such as palladium and growing various metals from the nucleus. Electroless nickel plating, electroless nickel-tungsten alloy plating, electroless copper plating, electroless tin plating, Examples include electroless gold plating. As the core of the electroless plating used in the present invention, palladium is usually used. However, there is no problem if it is a known method, and other metals may be used.

The metal species used in the wet plating method of the present invention preferably contains at least one metal selected from the group consisting of gold, silver, copper, zinc, nickel, tin, and chromium. It may be a composite with other metals such as tungsten. For example, in the case of a wiring board that requires low resistance, a metal having a low resistance such as gold, silver, or copper is used. In the case of a wiring board that requires hardness, a metal such as chrome is used. Various physical properties can be changed depending on the metal species. The plating thickness of the wet plating according to the present invention may be any thickness as long as the conductive function can be exhibited, but from the viewpoint of partially removing the conductive layer of the wiring board, the conductive layer is too thick in the case of a too thick plating layer. Therefore, workability at the time of removal is deteriorated. The thickness of the conductive layer by wet plating is preferably 500 nm to 1 mm, more preferably 550 nm to 0.8 mm.
<Application>
The wiring board and wiring board of the present invention can be used as a wiring board and a collecting electrode that are usually used. When the board is transparent, a transparent panel (collecting electrode) such as a flat panel display such as an LCD, a solar cell, and a touch panel. Electric electrode), an antistatic film, an electromagnetic shielding material, and the like.

Below, based on an Example, this invention is demonstrated in detail. In addition, the evaluation method used by this invention is also as showing in each Example.
<Making electroless silver plating>
Example 1
Using a polyethylene terephthalate O3 grade (thickness: 125 μm) manufactured by Teijin DuPont as a substrate, wet electroless silver plating was performed on the substrate using the following method.

The base material is degreased with Okure Pharmaceutical Co., Ltd. A-screen A-220 (building bath concentration 50 g / L, temperature 50 ° C., immersion time 5 minutes), washed with water and then sodium hydroxide (concentration 200 g / L, temperature) 70 to 75 ° C.) and PBT enchant TR (concentration 200 ml / L, immersion time 20 minutes) manufactured by Okuno Pharmaceutical Co., Ltd. Thereafter, the substrate was washed with hot water at a temperature of 60 ° C. and an immersion time of 3 minutes, and then concentrated hydrochloric acid (concentration 100 ml / L, room temperature) and TMP neutralizing additive (concentration 20 ml / L, immersion time) manufactured by Okuno Pharmaceutical Co., Ltd. 2 minutes), and after nucleating with catalyst C (concentration 40 ml / L, room temperature) and concentrated hydrochloric acid (concentration 150 ml / L, immersion time 5 minutes) manufactured by Okuno Pharmaceutical Co., Ltd., Okuno Pharmaceutical Industries Electroless silver plating is performed on the polyethylene terephthalate substrate with Muden Silver MGS (MGS-1: 100 ml / L, MGS-2: 400 ml / L, MGS-3: 10 ml / L at room temperature for 10 minutes) manufactured by Co., Ltd. A wiring board was obtained. The thickness of the electroless silver plating was 600 nm.
Examples 2-3
Example 2 uses a slide glass as a base material, Example 3 uses a silicon wafer (250 μm) as a base material, electroless silver plating is performed on each base material by the same method as Example 1, and for wiring A substrate was obtained. For conductivity evaluation, measurement was performed according to JIS K 7194 using a four-terminal four-probe system Loresta-GP (manufactured by Dia Instruments).

The conductivity evaluation results of Examples 1 to 3 were all sheet resistances of 0.1 to 0.2Ω / □, indicating good low resistance.
<Etching>
A mesh Teflon (registered trademark) tape with a 1 mm square window cut off was applied to the electroless silver-plated surface of the wiring board prepared in Examples 1 to 3, and then immersed in 30% hydrochloric acid. Then, the electroless silver plating in the portion not masked was removed, washed with water, and then the masking tape was peeled off to obtain a grid-like electroless silver plating substrate as a wiring substrate.
<Conductivity evaluation and transparency evaluation>
The conductivity evaluation was measured according to a four-terminal four-probe method JIS-K-7194.

  The conductivity evaluation results of Example 1, Example 2, and Example 3 were 0.5Ω / □, 2Ω / □, and 1.3Ω / □, respectively, in terms of sheet resistance, indicating good low resistance.

  Moreover, transparency evaluation measured the total light transmittance based on ASTMD-1003.

  The total light transmittances of Example 1, Example 2, and Example 3 were 85%, 88%, and 90%, respectively, which were 80% or more, indicating good transparency.

Claims (8)

  A wiring substrate comprising a base material and a conductive layer formed using a wet plating method on the base material.   The wiring substrate according to claim 1, wherein the base material is a base material selected from the group consisting of glass, plastic, and a silicon wafer, and a conductive layer is formed on substantially the entire surface of the base material.   The wiring substrate according to claim 1 or 2, wherein the wet plating method is an electroless plating method.   The wiring substrate according to claim 1, wherein the metal species used for the conductive layer is at least one selected from the group consisting of gold, silver, copper, zinc, nickel, tin, and chromium. .   The wiring substrate according to claim 1, wherein the base material is transparent.   The wiring board which has the wiring produced by removing a conductive layer partially from the wiring board as described in any one of Claims 1-5.   A current collecting electrode comprising the wiring substrate according to claim 6.   The current collecting electrode according to claim 7, which is a current collecting electrode for a solar cell.