JP2642503B2 - Method for removing insulating thin film on glass substrate of EL element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing a thin film using a dry blasting method or a liquid honing method in which an abrasive is sprayed on an object to be polished at a high pressure, and more particularly to a glass substrate for an EL element. The present invention relates to a method for removing an insulating thin film formed thereon.

[Prior art]

The mechanical grinding and polishing of the surface of an object depends on the required amount of grinding, the required surface condition after processing (surface roughness and smoothness), the material and the surface condition and shape of the workpiece. Various methods have been used. Generally, as the above method, a dry blast method or a liquid honing method is often used. In these methods, the abrasive is accelerated at high speed using compressed air, and the abrasive is caused to collide with the workpiece to grind the surface of the workpiece. The above method is relatively easy and has few restrictions on the shape, material, and the like of the workpiece, so that it is widely used industrially. Further, the above method is extremely effective for removing a thin film attached to the surface of an object, and is generally used for removing a piece of film attached to the surface of a jig or the like of a thin film forming apparatus. It is also used for the purpose of removing unnecessary films around the display area of the display element in the manufacturing process. FIG. 5 is a sectional view showing a method of grinding the surface of an object using the dry blast method or the liquid honing method. As shown in FIG. 5, the spray gun 22 sprays the abrasive 23 in a spot shape. Then, in order to uniformly process the entire surface of the workpiece 21 over a wide range, at least one of the injection gun 22 and the workpiece 21 is scanned at a constant speed. In this grinding method, the accelerated abrasive 23 collides with the workpiece 21 and generates minute cracks and defects in the surface layer of the workpiece 21. Then, the cracks and defects are further grown, and a part of the surface layer portion of the workpiece 21 is separated into a minute lump from the workpiece 21. By repeating such an operation, the grinding process proceeds. The main factors that determine the grinding speed in the grinding process are the kinetic energy of the abrasive 23, the elastic modulus of the abrasive 23, the elastic modulus of the workpiece 21, the Poisson's ratio of the workpiece 21 (deformation). Ease). Among the above factors, the elastic modulus of the abrasive 23 and the elastic modulus and Poisson's ratio of the workpiece 21 are determined by the materials of the abrasive 23 and the workpiece 21. For this reason, the conditions that can be changed during actual processing are
The kinetic energy of 23. Where the abrasive
The kinetic energy of 23 is W, the mass of the abrasive 23 is m,
The velocity of the abrasive 23 at the time of collision with the workpiece 21 is represented by v
Then, the following equation (1) holds. W = (1/2) mv ² (1) The mass m of the abrasive 23 is determined by the particle size of the abrasive 23,
The particle size is determined by the type of the abrasive 23. And
The speed v is the pressure P of the compressed air for accelerating the abrasive 23.
Using the distance d from the tip of the spray gun 22 to the workpiece 21 and the mass m of the abrasive 23, the following equation (2) can be used. v = α · P ⁱ / m ^j d ^k (2) (α: constant, i, j, k: multiplier) Of the kinetic energy W of the abrasive 23, perpendicular to the surface of the workpiece 21. Only the component Wz in the appropriate direction has a grinding effect. Therefore, Wz, which is the kinetic energy that is actually effective for grinding, is given by the following equation (3), where θ is the angle between the surface of the workpiece 21 and the ejection direction of the abrasive 23 from the ejection gun 25. Can be calculated by In Wz = (1/2) m (v sinθ) 2 = (1/2) mv 2 sin 2 θ ...... (3) grinding method described above of the object surface, in order to increase the grinding efficiency, the Wz up Θ = 90 ° (the above abrasive
The ejection gun 25 is set so that the ejection direction of the nozzle 23 is perpendicular to the surface of the workpiece 21). The above-mentioned grinding method is not limited to the case of simply grinding the surface of the workpiece and the case of roughening the surface of the workpiece in a satin shape, as described above, the thin film adhered to the surface of the workpiece. It is also used as a method of removing a thin film for removing sapphire.

[Problems to be solved by the invention]

However, the above-mentioned conventional method for removing a thin film has the following problems. That is, SiO ₂ , Al ₂ O ₃ , TiO ₂ , Si ₃ N ₄
When a very hard thin film made of oxide or nitride such as is adhered to the surface of the workpiece, or a thin film with strong adhesive force adheres to the surface of the workpiece by sputtering, CVD, etc. If the work piece is made of a hard and brittle material, such as glass or ceramic, which tends to cause brittle fracture, as shown in FIG. If the thin film 32 remains partially adhered to the surface or the thin film 32 is completely removed, the surface of the workpiece 21 may be ground as shown in FIG. 6B. . For this reason, there is a problem that it is extremely difficult to set conditions so as to remove only the thin film. Therefore, an object of the present invention is to provide an EL device which can easily remove a hard thin film or a thin film having a strong adhesive force on a glass substrate of an EL device as a workpiece while suppressing damage to the glass substrate. An object of the present invention is to provide a method for removing an insulating thin film on a glass substrate.

[Means for Solving the Problems]

In order to achieve the above object, the method for removing an insulating thin film on a glass substrate of an EL device according to claim 1 of the present invention is directed to a method for removing a thin film adhered to a surface of a glass substrate of an EL device as a workpiece. A method of removing an insulating thin film on a glass substrate of an EL element, which comprises spraying a mixture of water and an abrasive from a gun to remove the thin film from the glass substrate, comprising: It is characterized in that the angle between the mixture and the injection direction is set to less than 90 °. According to a second aspect of the present invention, in the method for removing an insulating thin film on a glass substrate of an EL element according to the first aspect,
It is characterized by being set at less than 60 mm.

[Action]

As shown in FIG. 4, assuming that the angle between the surface of the glass substrate of the EL element as the workpiece and the direction in which the abrasive is jetted is θ, of the collision speed v of the abrasive to the glass substrate, When the component vz in the direction perpendicular to the glass substrate and the component vx in the direction parallel to the surface of the glass substrate are vz = v sin θ and vx = v cos θ, and the mass of the abrasive is m, vz and
Energy Wz and Wx corresponding to vx, ^{respectively, Wz = (1/2) mv 2} sin 2 θ, is ^{Wx = (1/2) mv 2 cos} 2 θ. θ is set to less than 90 °. Therefore, θ
Is set to 90 °, the energy Wz in the direction perpendicular to the surface of the glass substrate, which destroys the insulating thin film attached to the glass substrate, is smaller. However, energy Wx in a direction parallel to the surface of the glass substrate is generated by the smaller Wz, and this energy Wx acts to peel off the thin film attached to the surface of the glass substrate from the glass substrate. . And, since the adhesive force at the interface between the thin film and the glass substrate is smaller than the bonding force between the molecules of the glass substrate and the molecules of the thin film, the thin film can be easily removed from the glass substrate by the above-described action. Peeled off.
In addition, as described above, since energy in a direction perpendicular to the surface of the glass substrate is small, damage to the surface of the glass substrate is reduced, and roughness of the surface of the glass substrate is reduced. Further, as shown in FIG. 3, the above angle is remarkable with the critical point being 60 °, and the surface roughness becomes small.

【Example】

Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 is a sectional view of one embodiment of a method for removing an insulating thin film on a glass substrate of an EL element according to the present invention. In the above embodiment, the insulating thin film 7 made of SiO ₂ and Si ₃ N ₄ having a thickness of 2000 to 3000 ° attached to the surface of the workpiece 1 made of a glass substrate by the liquid honing method is polished with an alundum system of JIS No. 1200 Material 3 is removed. As shown in FIG. 1, the angle θ between the surface of the workpiece 1 made of the glass substrate and the direction of the abrasive 3 sprayed from the spray gun 2 is set to 45 °. The distance between the tip of the injection gun 2 and the workpiece 1 is set to 8 cm. In order to uniformly process the entire surface of the workpiece 1 over a wide range, at least one of the spray gun 2 and the workpiece 1 is scanned at a constant speed. The abrasive 3 is accelerated by compressed air at a compressed air pressure of 2.0 kg / cm ² and collides with the insulating thin film 7 attached to the surface of the workpiece 1. At this time, of the kinetic energy of the abrasive 3, a component in a direction perpendicular to the surface of the workpiece 1 destroys the insulating thin film 7, while the kinetic energy of the abrasive 3 out of the kinetic energy of the abrasive 3 The component in the direction parallel to the surface of the workpiece 1 peels off the insulating thin film 7 from the workpiece 1 and removes the same. FIG. 2B shows the surface state of the workpiece 1 after the insulating thin film 7 has been removed according to the above embodiment. FIG. 2 (A) shows the surface condition of the workpiece when the thin film is removed with θ = 90 ° as in the prior art, and the other conditions are the same as in the above embodiment.
As can be seen from FIGS. 2 (A) and 2 (B), in the above embodiment, both the center line average roughness Ra and the maximum roughness Rmax of the surface of the workpiece are improved to 1/10 or less as compared with the conventional example. it can. FIG. 3 shows the center line average roughness Ra of the surface of the workpiece when the angle θ is set to various values in the above embodiment. As can be seen from FIG. 3, the center line average roughness Ra decreases sharply when the angle θ is set to less than 60 °, and the surface condition of the workpiece can be improved. The scanning speed of the spray gun or the workpiece is much lower than the collision speed of the abrasive particles, and is negligible in practical use. Therefore, if the inclination angle of the spray gun and the distance between the spray gun and the workpiece are kept constant, scanning may be performed in any direction with respect to the abrasive material spraying direction.

【The invention's effect】

As is clear from the above description, the method for removing an insulating thin film on a glass substrate of an EL element according to the present invention is a method for removing an insulating film as an object to be processed.
Since the angle between the surface of the glass substrate of the EL element and the direction in which the abrasive is jetted is set to less than 90 °, unlike the case where the angle is set to 90 ° as in the conventional case, the abrasive is made of the glass substrate. Has a force to peel off the insulating thin film adhered to the surface of the substrate from the glass substrate in the horizontal direction. Therefore, according to the present invention, the insulating thin film can be removed without spraying the abrasive at an excessive speed, minimizing damage to the surface of the glass substrate, and easily forming a hard and strong adhesive thin film. Under optimal conditions, it can be removed from the glass substrate.
Further, since the surface roughness of the glass substrate after processing can be significantly reduced as compared with the related art, the problem of coverage when a thin film is formed in a subsequent step can be solved. When the angle is less than 60 °, the surface roughness of the glass substrate is remarkably small.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of one embodiment of a method for removing an insulating thin film on a glass substrate of an EL element according to the present invention, FIG. 2 is a cross-sectional view of the surface of the glass substrate after removing the insulating thin film, and FIG. FIG. 4 is a characteristic diagram showing the relationship between the average roughness of the glass substrate after the removal processing of the insulating thin film and the inclination angle θ of the abrasive injection direction, FIG. 4 is an explanatory diagram of the velocity component decomposition of the abrasive by the inclination angle θ, and FIG. FIG. 6 is a cross-sectional view for explaining a conventional method for removing a thin film, and FIG. 6 is a cross-sectional view showing how a thin film is removed by a conventional method for removing a thin film. 1,21… Workpiece, 2,22… Injection gun, 3,23… Abrasive, 7,32… Thin film.

Continuation of the front page (72) Inventor Hiroshi Kishishita 22-22, Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (56) References JP-A-50-109471 (JP, A) JP-A-62-41100 ( JP, A) JP-A-55-127173 (JP, A) JP-A-61-3611 (JP, A)

Claims (2)

(57) [Claims] A mixture of water and an abrasive is sprayed from a gun toward an insulating thin film adhered to a surface of a glass substrate of an EL element as a workpiece, and the insulating thin film is sprayed from above the glass substrate. A method for removing an insulating thin film on a glass substrate of an EL element, wherein an angle between a surface of the glass substrate and a direction of injection of a mixture from the gun is set to less than 90 °.
A method for removing an insulating thin film on a glass substrate of an EL element. 2. The method for removing an insulating thin film on a glass substrate of an EL device according to claim 1, wherein said angle is set to less than 60 °. Method.