JP2008204979A - Wiring formation method by ink jet system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide wiring formation by an ink jet system that is refined and superior in light transmittance. <P>SOLUTION: A metallic fine grain-containing solution is applied to a surface-treated substrate by an ink jet method, and the substrate is baked and a wiring pattern is formed thereon. Then, surface-treated films other than a part where the wiring pattern is formed are removed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a surface treatment method and pattern formation in wiring formation by an inkjet method.

  In general, drawing by an ink jet method is being developed for various pattern formations because of the simplicity of the apparatus and the ease of pattern formation, including printers. In particular, in the industrial field, studies are being made on the use in the fields of wiring pattern formation, which has been conventionally performed by photolithography, and liquid crystal color filter manufacture, which has been manufactured through many processes.

  The inkjet method can eject a single droplet when needed from one nozzle, so it can easily form an arbitrary pattern, and since there are few wasted solutions, it is also promising from an environmental standpoint. Yes.

  One example of application to the industrial field is a color filter forming technique for liquid crystal panels. A color filter of a liquid crystal panel generally requires many manufacturing facilities and processes because many photolithography processes such as development, exposure, and etching are repeated in three colors of RGB. On the other hand, when a color filter is prepared by an ink jet method, it can be manufactured by filling each ink jet head with RGB inks and applying and curing a necessary amount only in a necessary place.

  In addition, in the same liquid crystal panel manufacturing process, applications are also being studied in fields such as coating of alignment films and spacers.

  Further, in the field of wiring formation, various fields have been studied due to the same advantages as described above. In the field of wiring formation, a narrow line width is required in the flow of high-density mounting. In screen printing, which is often used at present, a line width of about 20 to 30 μm is the limit, but the ink jet method has a possibility of realizing a line width equal to or less than that.

  If such a line width can be realized, it can be applied to wiring of a large area substrate such as a liquid crystal display or a plasma display.

  However, in the case of the ink jet system, it is necessary to lower the viscosity of the ink in order to eject the ink as compared with screen printing or the like. If the viscosity is low, a phenomenon occurs in which the dots or line widths spread due to wetting and spreading after printing on the substrate. In order to prevent these problems, in general, when wiring is formed using an inkjet method, wetting and spreading are prevented by applying a surface treatment to the coated substrate to keep the contact angle of the coated substrate with ink high.

  On the other hand, if the contact angle with the substrate is kept high, the adhesion between the ink and the substrate is lowered. Therefore, there is a method of increasing the adhesion by providing minute irregularities on the surface of the coated substrate. These two methods are combined to maintain optimum wetting spread and adhesion.

  When the uneven surface treatment of the substrate surface described above is performed, the surface is generally roughened, so that the transparency of the substrate decreases. In the case of a resin substrate such as a circuit wiring board, there is no problem, but there is a problem that the above method cannot be used when it is necessary to transmit light like wiring of a plasma display.

  In order to solve the above problems, the present invention includes a step of forming a surface treatment film on a substrate, a step of applying a metal fine particle-containing solution on the substrate, and a step of firing the substrate coated with the metal fine particles. And a step of removing the surface treatment film in a portion where the metal fine particles are not applied on the substrate coated with the metal fine particles. By this method, the surface treatment film other than the portion where the metal fine particles are applied does not remain.

  Another feature of the present invention is that the substrate on which the wiring is formed in the above method is glass. By this method, a substrate having a high light transmittance can be realized.

  Another feature of the present invention is that oxygen plasma is used as a method of removing the surface treatment film by the above method. The surface treatment film can be easily removed by this method.

  In the wiring forming method by the ink jet method according to the present invention, fine metal wiring can be achieved without reducing the transmittance by removing the surface treatment film after forming the wiring. For this reason, high-density fine wiring can be formed on a large-area glass substrate such as a plasma display by an inexpensive and simple process.

  Hereinafter, as an embodiment of the present invention, a method for forming wiring on a glass substrate of a plasma display panel will be described.

  FIG. 1 shows a process of applying a surface treatment to a glass substrate.

Process (1)
The glass substrate 1 is subjected to oxygen plasma 11 cleaning in order to improve adhesion with the surface treatment liquid. In this example, soda-lime glass generally used for plasma display was used as the glass substrate. As oxygen plasma treatment conditions, irradiation was performed for 3 minutes at 300 W under a vacuum of 20 Pa at room temperature.

Process (2)
A surface treatment liquid obtained by diluting a fluororesin mixed with silica particles with a solvent is applied to the surface of the glass substrate and heated at 130 ° C. for 15 minutes to form the surface treatment film 2. Here, depending on the concentration of the fluororesin 21 and the mixing amount of the silica particles 22, the adhesion and wet spread with the metal fine particles applied in the next step are affected. In this example, the trade name Novec (registered trademark) manufactured by 3M was used as the fluorine resin 21. Other materials include OPTOOL DSX (registered trademark) manufactured by Daikin Industries. The fluorine-based resin used here forms a monomolecular film and does not react with the surface even if the concentration exceeds a certain level. Therefore, the concentration is suitably 5% or less. Further, the mixing amount of silica particles is preferably 10% or less from the viewpoint of light transmittance.

Step (3)
An arbitrary metal wiring pattern 3 is formed by applying a metal fine particle-containing solution (for example, silver nano paste made by Harima Kasei Co., Ltd.) onto the glass substrate 1 on which the surface treatment film 2 is formed using an inkjet coating apparatus. In this example, solvent-based silver nano-ink is used, and baking is performed at 250 ° C. for 30 minutes after pattern formation to ensure conductivity by removing the solvent and bonding fine particles.
Although the wiring formation is completed at the above steps (1) to (3), the surface treatment film 2 contains silica particles 22 for improving adhesion, and the light transmittance of the glass substrate 1 is improved. Is low. For this reason, the surface treatment film 2 in portions other than the wiring is removed in the next step.

Step (4)
The glass substrate 1 after firing is irradiated with oxygen plasma 11 at 300 W for 3 minutes, and only the fluorine-based resin film 21 is removed. By using oxygen plasma, only the resin is removed by chemical etching, and the metal wiring portion remains. Irradiation conditions are determined by the thickness and type of the surface treatment film 2.

Process (5)
In the removal of the fluorine-based resin film by the oxygen plasma in the step (4), the silica particles 22 that are ceramic remain on the glass substrate 1 and are removed by washing with water spray or the like.

  FIG. 2 is an external view of the ink jet head drawing apparatus according to the present invention.

  The ink jet head unit 32 is attached to an X guide 4 operable in the X direction shown in the figure, and the substrate holder 5 can be driven in the Y direction, so that a glass substrate can be seen from an arbitrary distance by a signal from the head drive driver. The metal fine particle-containing solution can be applied to any position on 1. The metal fine particle-containing solution is continuously supplied from a metal fine particle-containing solution tank (not shown) through the solution supply pipe 6. In addition, when the glass substrate is replaced or when the apparatus is stopped, the inkjet head unit 32 moves to the head maintenance unit 7 to prevent the solution from drying, and cleaning and cleaning the surface of the inkjet head unit 32 (surface on which liquid is discharged). An operation such as a dummy discharge for discarding a cap, and possibly an old solution is performed.

  When the wiring forming method of the present invention is used, not only the wiring for the plasma display of this example but also the wiring forming on the glass that needs to ensure the light transmittance such as the window heater for automobiles can be directly made.

The figure which shows the process of the wiring formation method of this invention 1 is an external view showing an embodiment of an ink jet coating apparatus used for wiring formation according to the present invention.

Explanation of symbols

  1 is a glass substrate, 2 is a surface treatment film, 3 is a metal wiring pattern, 4 is an X guide, 5 is a substrate holder, 6 is a solution supply pipe, 7 is a head maintenance unit, 11 is oxygen plasma, 21 is a fluororesin film, 22 is a silica fine particle, 32 is an inkjet head part.

Claims (3)

  A step of forming a surface treatment film on the substrate, a step of applying a fine particle-containing solution on the substrate, a step of firing the substrate coated with the metal fine particles, and a metal fine particle on the substrate coated with the metal fine particles. A method of forming a wiring by an ink jet method, including a step of removing the surface treatment film in a portion not coated. In the wiring formation method by the inkjet system according to claim 1,
A method of forming a wiring by an ink jet method, wherein the substrate on which the wiring is formed is glass. In the wiring formation method by the inkjet system according to claim 1,
Ink-jet wiring formation method using oxygen plasma as a method of removing the surface treatment film

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