JP2014165263A - Method of manufacturing transparent electrode material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress swelling at the end of a groove, or protrusion of an electrode due to metal scattering to a part other than the groove after plating, in precision machining by laser, and to form an electrode having a high surface smoothness with high dimensional accuracy.SOLUTION: A laser absorption layer for absorbing laser light is formed on the surface of a substrate, and the laser absorption layer is irradiated with laser while being arranged to face a metal target. Ablation and etching occur at the point irradiated with laser, but since the vicinity thereof is coated with the laser absorption layer, contamination by metal scattering can be prevented. Metal is deposited only at the position irradiated with laser and etched, and the end thereof does not swell. Absorbance of the laser absorption layer for the light of the same wavelength as that of the laser is set to 0.05-3.5.

Description

  The present invention relates to a method for producing a transparent electrode material in which a metal electrode is formed on the surface of a transparent substrate.

  Conventionally, as a method of forming an electrode made of metal on the surface of a base material, after printing an electrode pattern with a composition containing a plating catalyst, a method of forming an electrode by plating treatment, or a base material by sputtering using a mask A method has been adopted in which a trace amount of a metal film is formed on a surface in a pattern, and plating is performed using this as a nucleus to form an electrode. Alternatively, there is a method of forming a patterned electrode by coating an entire base material surface with a metal film by metal vapor deposition or sputtering and then removing an unnecessary metal film by etching.

  However, the electrodes obtained by these conventional methods have a shape that rises from the substrate surface. For example, when used as an organic EL electrode material, a high degree of surface smoothness is required, but the swell of the electrode causes uneven brightness.

  As a method of forming an electrode material with high surface smoothness, a method of embedding a metal after digging a groove on the surface of a base material is known. Grooves are formed on the surface of the substrate using chemical etching or laser, and a plating catalyst is applied to the grooves. Then, a plating process is performed to form an electrode made of metal. However, palladium used as a plating catalyst is very expensive, and its waste liquid treatment is also expensive. Further, in order to form a fine groove with a laser, an expensive short wavelength laser (for example, an excimer laser) is necessary, and the apparatus becomes large.

  Therefore, in recent years, studies on precision processing methods using lasers have been actively conducted. For example, in Patent Document 1, a base material is irradiated with laser light, ablation is generated by the interaction between plasma and laser light, and an etching groove is formed on the base material by the ablation to deposit a metal thin film simultaneously. A method for forming metal wiring is shown.

JP 2005-79245 A

  However, in the method of Patent Document 1, a slight rise occurs at the end of the groove. Further, the metal formed after the plating process is formed so as to protrude from both sides of the groove due to metal scattering to portions other than the groove. This results in the formation of an electrode thicker than the desired width, which hinders the densification of the electrode. Furthermore, there is a problem that problems such as short circuit between adjacent electrodes are likely to occur.

  Therefore, as a result of intensive studies, the inventors of the present invention formed a laser absorption layer that absorbs laser light on the surface of the substrate, and irradiated the laser with the laser absorption layer disposed opposite to the metal target, so that the groove end was raised. Furthermore, the inventors have found that the formation of the groove and the metal transfer can be performed without the metal scattering to the portion other than the groove, and the present invention has been completed. By performing the plating process on the groove formed in this way and transferred with metal, an electrode having high surface smoothness and high dimensional accuracy can be formed.

That is, the method for producing the transparent electrode material of the present invention includes:
(A) A step of forming a laser absorption layer on the surface of the transparent substrate (b) A step of irradiating a laser from the transparent substrate side by placing a metal target at a position facing the laser absorption layer (c) The transparent Removing the laser absorbing layer from the surface of the substrate (d) plating the transparent substrate to form an electrode made of metal, the laser absorbing layer having the same wavelength as the laser; It is a manufacturing method of the transparent electrode material characterized by the light absorbency with respect to light being 0.05-3.5. The absorbance is preferably 0.1 to 1.5.

  According to the present invention, a transparent electrode material with high surface smoothness and high dimensional accuracy can be produced.

FIG. 1 is a schematic view showing a production process of the transparent electrode material of the present invention. FIG. 2 is a schematic diagram showing a cross-sectional shape of the transparent electrode material according to the present invention.

DESCRIPTION OF SYMBOLS 1 Laser oscillation apparatus 2 Laser beam 3 Transparent base material 4 Laser absorption layer 5 Metal target 6 Stage 7 Metal thin film 8 Metal layer by plating

  The manufacturing method of the transparent electrode material of this invention is demonstrated using FIG. Laser light 2 (hereinafter simply referred to as laser light 2) emitted from the laser oscillation device 1 passes through the transparent substrate 3 and reaches the laser absorption layer 4. The laser absorbing layer 4 is ablated by absorbing the laser beam 2 and partially removed. By removing the laser absorption layer 4, the laser beam 2 reaches the metal target 5, and ablation of the metal target 5 occurs. By this ablation, an etching groove is formed on the surface of the transparent substrate 3, and at the same time, a metal thin film 7 (FIG. 2) is deposited. At this time, since the laser absorbing layer 4 remains except for the portion where the etching groove is formed and the metal thin film 7 is deposited on the surface of the transparent base material 3, the contamination due to the ablation of the metal target 5 can be prevented. it can.

Based on the above processing principle, the base material needs to be transparent to the oscillation wavelength of the laser beam. More specifically, the absorbance is preferably less than 0.05. When the absorbance is higher than this, there arises a problem that the substrate itself absorbs the laser light and is ablated. There is also a problem that the processing efficiency is lowered due to the laser light absorption of the base material itself.

  The laser absorption layer in the present invention is composed of a dye for absorbing laser light and a medium for dispersing the dye. When the medium itself has an absorption band at the oscillation wavelength of the laser, a configuration not containing a dye can also be used. Examples of materials that can be used as a medium for dispersing the dye include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene terephthalate-isophthalate copolymer, and terephthalic acid-cyclohexanedimethanol-ethylene glycol copolymer. Polyester resins such as polyester resins, polyamide resins such as nylon 6, polyolefin resins such as polypropylene and polymethylpentene, acrylic resins such as polyacrylate, polymethacrylate and polymethyl methacrylate, styrene resins such as ABS resin, triacetyl Examples thereof include cellulose resins such as cellulose, imide resins, and polycarbonates. Of these, polyester resins such as polyethylene terephthalate and polyethylene naphthalate are preferably used because of their low cost.

  Examples of dyes for absorbing laser light include inorganic pigments such as titanium dioxide, iron oxide, zinc yellow, and carbon black, organic dyes represented by rhodamine, methyl violet, malachite green, phthalocyanine, perylene, and derivatives thereof. , Pigments and the like can be used.

  As a laser absorption layer, it is necessary for the light absorbency in the oscillation wavelength range of a laser to be 0.05-3.5. Moreover, it is preferable that it is 0.1-1.5. When the absorbance is less than 0.05, it is difficult to form an etching groove on the base material, or it is difficult to form a metal thin film due to insufficient metal transfer amount to the base material. There is a problem that accuracy decreases.

The form of forming the laser absorption layer on the substrate is not particularly limited, and it can be formed by direct application to the substrate, lamination of the laser absorption layer and the substrate, or the like. Examples of the method of directly coating on the substrate include existing coating methods such as a bar coater, a micro gravure coater, a dip coater, a spray coater, and an ink jet.

  The thickness of the laser absorption layer is preferably 50 nm to 1 μm, more preferably 300 nm to 600 nm. When the thickness is less than 50 nm, the laser absorption effect is low. When the thickness is more than 1 μm, it is difficult to form the etching groove of the base material, or the metal transfer amount to the base material is insufficient, and it is difficult to form the metal wiring.

  A laser that can be used is a pulsed laser having a pulse width of nanoseconds to femtoseconds, and examples of the light source include YAG and Ti: Sapphire. The strength is preferably 10 mW to 1.5 W. When the strength is less than 10 mW, it is difficult to form an etching groove on the base material.

  Examples of the metal target include copper, tin, palladium, gold, silver, platinum, nickel, aluminum, and alloys thereof. The metal thickness is preferably about 1000 mm to 1 cm, more preferably about 1 μm to 1 mm. If the thickness is too thin, it becomes difficult to form metal wiring due to insufficient amount of metal transferred to the substrate, and if it is too thick, it tends to be impractical in terms of weight and cost.

  After the laser irradiation, the laser absorbing layer is removed from the substrate. As a removal method, washing with a solvent is used. As the solvent, a solvent capable of dissolving the laser absorption layer is preferable. For example, water, alcohols such as methanol, ethanol, n-propyl alcohol and isopropyl alcohol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and isophorone, aromatic hydrocarbons such as toluene and xylene, propylene glycol monomethyl Ether, propylene glycol monomethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl acetate, 3-methoxybutanol, 3-methoxybutyl acetate, 1,3-butylene glycol, dipropylene Glycol methyl ether, tripropylene glycol methyl ether , Tripropylene glycol methyl ether, propylene glycol n-propyl ether, dipropylene glycol n-propyl ether, tripropylene glycol n-butyl ether, dipropylene glycol methyl ether acetate, propylene glycol acetate, 1,3-butylene glycol diacetate, Glycols and derivatives thereof such as 1,4-butanediol diacetate, 1,6-hexanediol diacetate, dipropylene glycol dimethyl ether, dipropylene glycol methyl-n-propyl ether, glycerin and derivatives thereof such as glycerin and triacetin, Methyl acetate, ethyl acetate, isopropyl acetate, n-propyl acetate, butyl acetate, cyclohexanol Acetic esters such as Seteto, .gamma.-butyrolactone, N- methyl pyrrolidone, N, N- dimethylformamide, dimethyl sulfoxide, dimethyl acetamide, dimethyl carbonate, dioxane, tetrahydrofuran, solvent naphtha, and the like. One of these solvents may be used, or a mixture of a plurality of kinds may be used.

  Examples of the method for removing the laser absorption layer include an immersion method, ultrasonic cleaning, two-fluid cleaning, and the like. These may be used alone or in combination.

  An electrode pattern having a desired metal thickness is formed by plating a substrate on which an etching groove is formed by the above-described method and a metal thin film is deposited. A general electroless plating process can be used as the plating process, and the metal for plating is selected from, for example, copper, nickel, tin, cobalt, aluminum, palladium, gold, silver, platinum and the like. When a thick metal layer is formed, a method of first forming a thin metal layer by electroless plating and then growing the metal layer by electrolytic plating can be employed.

  The dimensional accuracy of the fabricated electrodes is measured using a digital microscope (VHX-600, KEYENCE) to measure the difference in line width before and after the plating process and the straightness of the line after the plating process according to JIS B 0621. And evaluated. The surface smoothness was measured using a scanning confocal laser microscope (OLS-3000, Olympus), and the center line average roughness (Ra value) of the metal part was measured using the attached analysis software. It was evaluated by calculating.

[Example 1]
As a base material, 0.7 mm-thick alkali-free glass was cut into a 5 cm square and used. On the base material surface, a 10% cyclohexanone diluted product of 15 wt% cyclohexanone solution of polyester resin (Byron 270: Toyobo Co., Ltd.) and red dye (Aizen Spiron Red DEH: Hodogaya Chemical Co., Ltd.) is used at a volume ratio of 4: 1. A laser absorption layer having a thickness of 0.35 μm was formed by mixing and applying with a bar coater. The absorbance of this laser absorption layer with respect to light having a wavelength of 532 nm was 0.15. As a metal target, a polyimide film with copper foil (copper thickness to 8.5 μm) is used, and a pulsed YAG laser (532 nm) is irradiated at a repetition frequency of 50 kHz, an irradiation intensity of 0.4 W, and a scanning speed of 2000 mm / min. Etching grooves were formed at the same time, and a metal thin film was deposited at the same time. The line width of the etching groove was 9 μm. The substrate was immersed in cyclohexanone and subjected to ultrasonic cleaning for 1 minute to remove the laser absorption layer, and then an electroless copper plating process was performed at a liquid temperature of 50 ° C. for 150 seconds to finally form an electrode having a width of 10 μm. The Ra of the metal part was 54 nm, and the straightness of the line was 1.3 μm. The composition of the electroless plating solution is as shown below.

(Electroless copper plating solution)
Complexing agent (ADEKA Corporation EDP-300) 40g / L
CuCl ₂ 5g / L
NaOH 10g / L
Bipyridine 5mg / L
Formaldehyde 5g / L

[Example 2]
Example 1 except that a 15 wt% cyclohexanone solution of polyester resin and a 7.5-fold diluted product of red dye were mixed at a volume ratio of 4: 1 and a laser absorption layer having a thickness of 0.35 μm was formed on the substrate surface. The same processing was performed. The absorbance of the laser absorption layer with respect to light having a wavelength of 532 nm was 0.2. Moreover, the width | variety of the obtained etching groove | channel was 11 micrometers, and the electrode of width 15 micrometers was obtained after electroless copper plating. Ra of the metal part was 61 nm, and the straightness of the line was 1.7 μm.

[Example 3]
Example 1 except that a 6 wt% cyclohexanone solution of polyester resin and a 7.5-fold diluted product of red dye were mixed at a volume ratio of 4: 1 and a laser absorption layer having a thickness of 0.15 μm was formed on the substrate surface. The same processing was performed. The absorbance of the laser absorption layer with respect to light having a wavelength of 532 nm was 0.2. Moreover, the width | variety of the obtained etching groove | channel was 13 micrometers, and the electrode of width 16 micrometers was obtained after electroless copper plating. Ra of the metal portion was 70 nm, and the straightness of the line was 1.1 μm.

[Example 4]
Example 1 except that a 15 wt% cyclohexanone solution of polyester resin and a 1.5-fold diluted product of red dye were mixed at a volume ratio of 4: 1 and a laser absorption layer having a thickness of 0.35 μm was formed on the substrate surface. The same processing was performed. The absorbance of the laser absorption layer with respect to light having a wavelength of 532 nm was 1.0. Moreover, the width | variety of the obtained etching groove | channel was 12 micrometers, and the electrode of width 15 micrometers was obtained after electroless copper plating. Ra of the metal part was 40 nm, and the straightness of the line was 1.9 μm.

[Example 5]
Example 1 except that a 0.7 mm-thick non-alkali glass 5 × 10 cm cut product was used as the substrate, polystyrene was used as the laser absorption layer, and a laser absorption layer having a thickness of 0.35 μm was formed on the substrate surface. Treated in the same way. The absorbance of the laser absorption layer with respect to light having a wavelength of 532 nm was 0.5. Moreover, the width | variety of the obtained etching groove | channel was 9 micrometers, and the electrode of width 12 micrometers was obtained after electroless copper plating. The Ra of the metal part was 100 nm, and the straightness of the line was 1.2 μm.

[Example 6]
The treatment was performed in the same manner as in Example 5 except that polyimide was used as the laser absorption layer, and a laser absorption layer having a thickness of 0.35 μm was formed on the substrate surface. The absorbance of the laser absorption layer with respect to light having a wavelength of 532 nm was 0.5. Moreover, the width | variety of the obtained etching groove | channel was 13 micrometers, and the electrode of width 13 micrometers was obtained after electroless copper plating. The Ra of the metal part was 61 nm, and the straightness of the line was 1.3 μm.

[Example 7]
The treatment was performed in the same manner as in Example 5 except that polymethyl methacrylate was used as the laser absorption layer, and a laser absorption layer having a thickness of 0.35 μm was formed on the substrate surface. The absorbance of the laser absorption layer with respect to light having a wavelength of 532 nm was 0.5. Moreover, the width | variety of the obtained etching groove | channel was 13 micrometers, and the electrode of width 15 micrometers was obtained after electroless copper plating. The Ra of the metal part was 63 nm, and the straightness of the line was 1.0 μm.

[Example 8]
A black dye (Aizen Spiron Black MH sp: Hodogaya Chemical Industry Co., Ltd.) was used as the pigment, and the same treatment as in Example 1 was performed except that a laser absorption layer having a thickness of 0.35 μm was formed on the substrate surface. . The absorbance of the laser absorption layer with respect to light having a wavelength of 532 nm was 0.5. Moreover, the width | variety of the obtained etching groove | channel was 13 micrometers, and the electrode of width 20 micrometers was obtained after electroless copper plating. Ra of the metal part was 47 nm, and the straightness of the line was 1.2 μm.

[Comparative Example 1]
A laser absorption layer was not formed on the surface of the base material, and the other processes were performed in the same manner as in Example 1. The width of the obtained etching groove was 25 μm, and the width of the electrode obtained after electroless copper plating was 44 μm. Ra of the metal part was 350 nm, and the straightness of the line was 10 μm.

[Comparative Example 2]
A 15 wt% cyclohexanone solution of polyester resin and a 300-fold diluted product of red dye were mixed at a volume ratio of 4: 1 and processed in the same manner as in Example 1 except that a laser absorption layer having a thickness of 0.35 μm was formed. The substrate was not etched, and metal deposition could not be confirmed even when the electroless copper plating treatment was performed. The absorbance of the laser absorption layer with respect to light having a wavelength of 532 nm was 0.005.

As a result, in Examples 1 to 8, since the line width after plating does not increase significantly with respect to the groove width after etching, the design is easy. Further, since the Ra value is as small as 100 nm or less, the surface irregularities are also small. Further, the straightness was as good as 1.9 μm or less. On the other hand, in Comparative Example 1, the line width after plating is greatly increased with respect to the groove width after etching. This is because there was contamination due to ablation of the metal target on both sides of the groove after etching. Due to this contamination, the Ra value and the straightness value also increased, the surface irregularities were large, and the line width after plating was not stable. In Comparative Example 2, since the absorbance of the laser absorption layer is low, the laser absorption layer itself does not ablate. Therefore, the laser absorbing layer was not removed and the surface of the base material was not exposed, so that no etching groove or metal thin film was formed.

  It can be used as an electrode material for organic EL, LED, solar battery, touch panel.

Claims (2)

(A) A step of forming a laser absorption layer on the surface of the transparent substrate (b) A step of irradiating a laser from the transparent substrate side by placing a metal target at a position facing the laser absorption layer (c) Removing the laser absorbing layer from the surface of the transparent substrate (d) plating the transparent substrate to form an electrode made of metal, and the laser absorbing layer has the same wavelength as the laser The manufacturing method of the transparent electrode material characterized by the light absorbency with respect to light of 0.05-3.5. 2. The method for producing a transparent electrode material according to claim 1, wherein an absorbance of the laser absorption layer with respect to light having the same wavelength as that of the laser is 0.1 to 1.5.