JP2012022243A - Method of forming conductive film pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of forming a conductive film pattern capable of solving problems concerning the simplification of the process, material use efficiency, costs and responses to various substrate sizes, which cannot be solved with conventional methods of manufacturing electrodes such as photolithography and mask sputtering, and capable of obtaining a pattern with high definition even in the ink jet method.SOLUTION: A desired electrode pattern is made with photosensitive application-type electrode materials. In this electrode manufacturing process, the desired electrode pattern can be obtained by applying a first light exposure with the use of a lamp whose source is cost-effective diffusion light, and then applying a second light exposure with larger amount of light than the first light exposure. This process of using two exposures with diffusion light achieves the material use efficiency, costs, responses to various substrate sizes and high-definition electrode patterning that is not successful in the ink jet method, for instance, in manufacturing wiring electrodes, which the traditional manufacturing method cannot achieve.

Description

  The present invention relates to a method for forming a conductive film pattern.

Currently, in the fields of organic EL elements, touch panels, and the like, various shapes and electrode patterns and wiring patterns are used.
Usually, photolithography, mask sputtering, ink jet printing, or the like is used as a method of creating an electrode portion used for an organic EL or a touch panel.

  Among these, when performing fine electrode patterning, photolithography is widely applied. However, photolithography requires a process of forming a photoresist pattern once by laminating a photoresist film on a film formed of the target material, and the process is complicated. The problem that utilization efficiency, such as these, is low and cost becomes expensive accompanies.

  Further, when patterning ITO (Indium Tin Oxide: hereinafter referred to as ITO) used for transparent wiring electrodes, it is generally created by mask sputtering. However, since mask sputtering is inefficient in terms of material usage in conjunction with mask development costs, the problem of high cost and the technical problem that the desired ITO pattern cannot be obtained unless the alignment between the substrate and the mask is set strictly. There is a big problem.

  Furthermore, since the devices that can be handled by the substrate size of the ITO used for the wiring electrodes used in the organic EL and touch panels differ depending on the substrate size, costs due to changes and modifications of the device accompanying the recent increase in substrate size.

  Therefore, for example, Patent Document 1 discusses an organic EL element production method by ink jet printing from the advantages of maskless, material use efficiency, and large area. Also, as disclosed in Patent Document 2, an ink jet method has been proposed as a method of filling a conductive polymer in a concave portion of a TFT in order to improve the quality of an organic EL. In Patent Document 3, a method of forming a wiring on a substrate by an ink jet method is proposed. Has been proposed.

  As described above, in recent years, as a method capable of dealing with simplification of the process, material use efficiency, cost, and various substrate sizes, an element production method and an electrode production method using ink jet have been studied.

JP 2009-231264 A JP 2009-211859 A JP 2009-38185 A

  As described above, photolithography and mask sputtering, which are conventional electrode manufacturing methods, have difficult problems to solve in terms of process simplification, material use efficiency, cost, and various substrate sizes. In view of this, an ink-jet element fabrication method and electrode fabrication method that do not have these problems have been studied.

  However, in the ink jet method, the fineness is remarkably deteriorated due to the wettability between the photosensitive coating electrode material (hereinafter referred to as electrode material) and the target substrate, the discharge amount, and the discharge environment, and a desired pattern contour cannot be obtained. There is. Further, it is known that the conductive ink ejected from the head portion is displaced until it adheres to the substrate, and there is a case where an accurate pattern cannot be formed at a desired position.

  In particular, in the case of a high-resolution display device, if the patterning accuracy of electrodes and wiring is poor, a short circuit or disconnection may occur between pixels, and a normal display function may not be achieved.

  The present invention proposes a method for overcoming the above-described problems and forming electrodes and wiring patterns with high resolution and high accuracy by a simple method. According to the present invention, the process can be simplified much more than the conventional method of forming a metal film or the like, applying a resist, exposing and developing, and etching to form a pattern.

  In order to solve the above-mentioned problems, the present invention provides a method for forming a conductive film pattern in which an electronic circuit is formed on a substrate using an electrode material made of a photosensitive organic material, a step of applying an electrode material on the substrate and pre-baking and drying, A method for forming a conductive film pattern comprising: a step of immersing an electrode material in a developer to remove unnecessary portions; and an exposure step of curing the electrode material with light.

  In the present invention, electrodes and wiring are patterned on a glass substrate using screen printing and a spin coater, and the electrode material used is an electrode material mixed with PDOTPSS, polyaniline, or silver particles.

  Usually, when an electrode is made of these materials, it is often applied to a pattern with low definition or the entire substrate. For these reasons, in the case of a pattern with high definition, the electrode part is disconnected at the time of development, or the electrode material remains between the electrodes and the like, resulting in a desired pattern not being obtained.

  In many cases, vertical light (hereinafter referred to as parallel light) that enters perpendicularly to the substrate surface is used as a light source for exposure. The reason for this is that when mask exposure is performed, light that enters in a random direction with respect to the substrate surface (hereinafter referred to as diffused light) exposes unnecessary electrode portions, and a desired pattern is obtained. It is caused by not. However, since the parallel light is usually expensive in terms of equipment, and the parallelism between the substrate and the light source greatly affects the patterning accuracy, it is necessary to fix the substrate position each time exposure is performed. As described above, parallel light has problems in both cost and productivity.

  In the present invention, by using printing and diffused light, an electrode production method is provided that achieves both cost and productivity and has improved patterning accuracy as compared with a normal inkjet method. Further, the present invention uses the first diffused light for the purpose of patterning and the second diffused light having a larger dose than the first exposure for the purpose of developing conductivity.

  According to the electrode preparation method by the double exposure using the electrode material of the present invention, the problem can be solved in the simplification of the process, the material use efficiency, the cost, and the various substrate sizes which are problems in the conventional method. Thus, it is possible to provide electrode patterning including simple, low-cost, and high-precision wiring.

  In the means for solving the problem, the method of applying the electrode material was exemplified by the screen printing and the spin coater, but the application method is not limited to this, and a roll coater, a bar coater, or the like is appropriately selected. it can.

The board | substrate state which gave the outline printing by screen printing to the board | substrate used for this invention is shown typically. 1 schematically shows a state of a substrate subjected to etching used in the present invention. The cross-sectional structure of the electrode material used for this invention is shown typically. The cross-sectional structure of the electrode material after pre-baking used for this invention is shown typically. The cross-sectional structure of the electrode material reaction state after performing the first UV exposure used in the present invention is schematically shown. The cross-sectional structure of the electrode material reaction state after performing the 2nd UV exposure used for this invention is shown typically. The cross-sectional structure of the electrode material reaction state after performing the post-baking used for this invention is shown typically. The state which apply | coated the electrode material on the glass used by this invention is shown as sectional drawing. 1 schematically shows a cross-sectional configuration of the electrode material used in the present invention when UV irradiation is performed through a mask. 1 schematically shows a cross-sectional state of a substrate after the development process used in the present invention. The cross section which gave the wiring containing Pad by the printing of the silver nanopaste beforehand to the transparent film for PET resin etc. which were used by this invention is shown typically. The cross section which apply | coated the photosensitive electrode material by screen printing on the wired film | membrane used by this invention is shown typically. The mounting part used by this invention is mounted, and the cross section at the time of irradiating UV from the film back surface is shown typically. The photosensitive conductive material used by this invention typically shows the cross section when it has electroconductivity.

Hereinafter, the present invention will be described in detail with reference to FIGS. 1 to 7 conceptually showing an electrode preparation method by double exposure using the electrode material according to the present invention.
FIG. 1 schematically shows screen printing by screen printing, and FIG. 2 schematically shows an etched state in FIG.

  In the present invention, the electrode material 2 is partially coated on the glass substrate 1 by screen printing, or is entirely coated by a spin coater. When the desired pattern is partially high-definition, the usage amount of the material 2 can be reduced by printing the outline of the pattern in advance by screen printing as compared with the spin coater. Further, in the etching process described later, since the material 1 to be eluted is reduced, it is possible to increase the number of continuous use of the etching solution.

FIG. 3 schematically shows a cross-sectional configuration of the electrode material used in the present invention.
After passing through the coating step, as a first heating step, heat is applied from the back surface of the substrate 1 using a hot plate in order to vaporize the solvent 3 in the coating electrode material 2 on the substrate 1 (hereinafter referred to as pre-baking). Here, when heat is applied from the surface of the substrate 1, the electrode material 2 is dried from the surface, so that the volume shrinkage rate between the inside and the surface is different, and the inside of the material cannot follow the volume change of the surface, so that the electrode may crack. is there. Therefore, it is desirable to apply heat from the back surface so that the internal solvent can be vaporized without delay.

  There are two reasons for vaporizing the solvent 3. In the electrode material 2 used in the present invention, silver particles or silver nanoparticles (hereinafter referred to as metal particles) are dispersed in a photosensitive polymer dissolved in the solvent 3. The distance between them becomes close, and the second heating step (hereinafter referred to as post-bake) described later facilitates the bonding between the metal particles 4, and as a result, the electric resistance can be lowered. Moreover, since the density | concentration of the photosensitive polymer becomes high, it can react with UV efficiently and can be sensitized with a low exposure amount.

  FIG. 4 shows a cross-sectional view of a substrate cross-sectional state after pre-baking (photosensitive polymer 5 after pre-baking), and FIG. 5 shows an electrode material reaction state after the first UV exposure (an organic active species is expressed). The obtained photosensitive polymer 7) is shown as a cross-sectional view. After the pre-baking, exposure with UV light 6 is performed. As an exposure method, there is generally exposure through a mask (hereinafter referred to as mask exposure). A light-shielding portion to be a pattern is formed in advance on the glass substrate 1, and a coating type photosensitive material is applied thereon, and then the back surface. Although an exposure method for obtaining a desired pattern by exposure from above (hereinafter referred to as back exposure) can also be applied, when a source electrode and a drain electrode are formed in a TFT, the back exposure is desirable because the channel width is very narrow.

  When the exposure method as described above is used, a UV irradiation amount of about 1% to 10% with respect to the reaction exposure amount of the electrode material 2 is exposed as diffused light (hereinafter referred to as a first UV exposure). In this case, in the vicinity of the electrode film surface in the mask opening, the UV light and the photosensitive polymer in the electrode material 2 react to generate reactive species. There are two types of reaction active species generated in this way, reaction as an organic reaction active species and reaction as a metal complex. The former has a role as a resist material that does not elute into the developer in the etching process, and the latter It exists between the metal particles 4 and has the role of expressing the conductivity of the electrode.

  In the mask light shielding portion, the UV light also travels to the electrode material 2 immediately below the light shielding portion. Originally, the UV light to be exposed is smaller than the reaction exposure amount of the electrode material 2, and the light amount of the UV light in the mask opening portion. The exposure amount of the UV light that wraps directly under the mask light-shielding part is even smaller, does not react with the electrode material, and does not generate reactive species.

  As described above, after performing the first UV exposure, by etching using a developer, a portion where reactive active species are present does not elute the electrode material, and only a portion where reactive reactive species does not exist is eluted. A desired high-definition electrode pattern can be obtained (hereinafter, development step). However, although the function as an organic reactive active species in the vicinity of the surface is expressed at the first exposure dose, the conductive function as a metal complex is not expressed.

  FIG. 6 schematically shows a reaction state of the electrode material subjected to the second UV exposure (photosensitive polymer 8 in which a reaction as a metal complex is expressed). By irradiating with UV light having an exposure amount sufficiently larger than the reaction exposure amount of the electrode material 2 described in FIG. 5, the function as a metal complex can be developed as well as the organic reaction active species.

FIG. 7 schematically shows a reaction state of the electrode material after post-baking (photosensitive polymer 8 after post-baking). As described with reference to FIG. 6, the photosensitive polymer after the second exposure also exhibits a function as a metal complex, but it alone has a high electric resistance. By post-baking here, the metal particles 4 are sintered, the particles are bonded to each other, and the metal complex is present so as to fill the gaps between the metal particles 4, so that the electric resistance is low, which is sufficient as an electrode. Function can be obtained.
Embodiments of the present invention will be described below with reference to the drawings.

  A patterning method in this embodiment will be described with reference to FIGS. In this embodiment, it is used when creating a high-definition electrode pattern having a space between electrodes of about 10 μm to 100 μm, such as a wiring electrode of a touch panel.

  FIG. 8 shows a state where the electrode material 21 is applied on the glass substrate 20 as a cross-sectional view. Electrode material 21 (Toray: Raybrid) is printed by screen printing. The film thickness to be applied is about 4 μm to 10 μm, and it is easy to obtain a desired pattern while keeping the electric resistance low.

  Next, a prebaking process is performed. Here, the coated glass substrate 20 is heated from the back surface. Since the solvent of the electrode material 21 used in this embodiment has a high boiling point, the heating conditions are preferably about 80 to 100 ° C. and 60 to 120 sec. When these heating temperatures are low or the heating time is short, the solvent in the electrode material 21 does not volatilize, and the surface may become sticky. Further, the reaction due to UV exposure is less likely to occur thereafter. On the other hand, when the heating temperature is high or the heating time is long, the electrode material 21 reacts excessively with heat, and organic reactive species are expressed in the entire coated area. This pattern is difficult to obtain.

FIG. 9 is a cross-sectional view in which UV exposure is applied to the configuration of FIG. 8 through a mask.
After the electrode material 21 is heated according to the conditions, the film surface is exposed through the mask 10 as the first exposure. Exposure amount at this time is preferably 10 mJ / cm ² from 3 mJ / cm ^2. The exposure amount beyond this is affected by the scattered light up to the electrode material 21 layer located immediately below the light-shielding portion of the mask 10 in FIG. 9, and a reaction occurs, so that a desired pattern cannot be obtained.

FIG. 10 shows a cross-sectional view of the substrate after the development process.
Since the electrode material 21 applied immediately below the light shielding part of the mask 10 is less affected by UV exposure, the organic reactive active species do not appear and the resist material does not function as a resist. Further, since the electrode material 21 other than the portion directly under the light shielding portion of the mask 10 is exposed with UV, an organic reactive active species is expressed, and since it has a function as a resist, it is not etched and the electrode material 21 remains. Therefore, a desired pattern can be obtained in this state. An aqueous sodium carbonate solution is used as the developer in this step, and the weight concentration is preferably 2% to 5%. As the developing method, the vibration developing method is used. However, it is also possible to use a method of dipping (dip development), a method of developing by dropping a developer on the substrate (step paddle development), or the like. In any of the development methods, it is necessary to adjust the temperature-controlled developer and development time according to the film thickness of the electrode. In the vibration developing method used in this example, the developing solution temperature is kept at room temperature (20 ° C.), and development is performed at a frequency of about 10 Hz to 50 Hz for about 3 to 10 minutes.

Next, second exposure having a larger exposure amount than the first exposure is performed by back exposure. The exposure dose at this time was sufficiently larger than the reaction exposure dose of the electrode material 21 (preferably 500 mJ / cm ² to 1000 mJ / cm ² ), and 500 mJ / cm ² was exposed in this example. Thereby, reaction as a metal complex advances in the electrode material 21, and a conductive function can be expressed.

  Next, a post-bake process is performed. At this time, baking is performed under conditions of a temperature of about 180 ° C. to 200 ° C. and about 1 hour.

  In this embodiment, a new component mounting method on a flexible substrate (hereinafter referred to as FPC) will be described with reference to FIGS. As a structure, it consists of the transparent resin film 12, the part (henceforth Pad) which mounts a mounting part, the wiring 11, a conductive adhesive material, and a mounting component in order from a board | substrate. Since the fineness required in this embodiment is such that the interelectrode space is 100 μm or more, the first exposure used in Embodiment 1 is not necessary.

  Pad and wiring 11 are printing of silver nano paste by an ink jet method. (Mitsubishi Paper). In addition, the mounted parts are made of a photosensitive electrode material (Toray: Raybrid) as a conductive adhesive.

  The application conditions, pre-bake conditions, and post-bake conditions for the photosensitive electrode material 14 in this example are the same as those in Example 1. The exposure is performed only once, and the conditions are the same as the second exposure conditions in the first embodiment. Next, a creation method will be described.

  In FIG. 11, a transparent film 12 such as a PET resin is preliminarily provided with a wiring 11 containing a pad by printing a silver nano paste.

  FIG. 12 is a cross-sectional view in which a photosensitive electrode material 14 is applied on a wired film 12 by screen printing using a screen printing plate 13. FIG. FIG. By applying the photosensitive electrode material 14 onto the pad, it is possible to adhere to a portion (hereinafter referred to as a land) corresponding to the pad of the mounted component due to its adhesiveness.

FIG. 14 is a cross-sectional view when the photosensitive conductive material 17 is cured and has conductivity.
Adhesion with the mounting component 15 can be ensured by pre-baking after mounting the mounting component 15. Thereafter, the photosensitive electrode material 14 used as an adhesive can be made conductive by irradiating UV from the back side and then post-baking.
As described above, an FPC that is cheaper than usual and easy to create is created.

  According to the present invention, in creating a wiring electrode such as a tag (hereinafter referred to as RFID) that exchanges information in a non-contact manner through a touch panel or infrared rays, simplification of processes, material use efficiency, cost, and various types that are problems in the conventional method. In response to various substrate sizes, the problem is solved, and electrode patterning including wiring with high accuracy, low cost and high accuracy is provided.

  In addition, it can be used as an adhesive for mounting components, and the present invention can provide an FPC that is inexpensive and easy to create.

DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Electrode material 3 Solvent containing photosensitive polymer 4 Metal particle 5 Photosensitive polymer after pre-baking 6 Ultraviolet ray 7 Photosensitive polymer in which organic active species are expressed 8 Photosensitivity in which reaction as metal complex is expressed Polymer 9 Photopolymer after post-baking 10 Mask 11 Wiring electrode 12 Transparent film 13 Screen printing plate 14 Photosensitive electrode material 15 Mounting component 16 Land 17 Photosensitive electrode material after curing 20 Glass substrate 21 Electrode material

Claims (6)

In a method for forming a conductive film pattern in which an electronic circuit is formed by an electrode material made of a photosensitive organic material on a substrate,
Applying electrode material on the substrate and pre-baking and drying,
Immersing the electrode material in a developer to remove unnecessary portions;
An exposure step of curing the electrode material with light;
A method for forming a conductive film pattern, comprising:   A method for forming a conductive film pattern, comprising: a pre-exposure step of irradiating the electrode material with light through a predetermined mask before the step of removing unnecessary portions of the electrode material.   The method for forming a conductive film pattern according to claim 1, wherein the electrode material is a coating type material having fluidity.   4. The conductive film pattern formation according to claim 1, wherein the pre-baking and drying is performed in a range of 80 ° C. to 100 ° C. for 60 seconds to 120 seconds. 5. Method. 3. The method for forming a conductive film pattern according to claim 2, wherein the preliminary exposure step performs exposure within a range of 3 mJ / cm ² to 10 mJ / cm ² . 6. The method for forming a conductive film pattern according to claim 1, wherein the exposure step performs exposure within a range of 500 mJ / cm ² to 1000 mJ / cm ² .

Images