JP4469679B2 - Manufacturing method of flat panel display - Google Patents

Description

  The present invention is a method for flattening the surface of a glass plate in which concave portions exist on the surface due to scratches or the like, and improves the flatness of the surface of a glass substrate used in a flat panel display (hereinafter referred to as “FPD”). The present invention also relates to a method for flattening the surface of a glass plate that can be suitably used, a glass substrate for FPD having improved flatness by using this method, and an FPD manufactured using this glass substrate.

  A panel serving as an image display unit in an FPD such as a thinned liquid crystal display, plasma display, or organic electroluminescence display as an image display device has a layer structure in which a plurality of members are stacked on a glass substrate surface. FIG. 2 is a schematic view of a panel cross section of a liquid crystal display which is an FPD. The illustrated liquid crystal display panel has a bonded structure in which liquid crystal is held between a pair of glass substrates.

  On one glass substrate 6 constituting the liquid crystal display panel shown in the figure and serving as an image display surface, a polarizing film 17 is laminated on the surface which becomes the outer surface after being bonded, and on the opposite surface, a color filter 8 is provided with a black matrix 7. The overcoat 9, the transparent electrode 10, and the alignment film 11 are sequentially laminated. On the other glass substrate 13, a polarizing film 18 is laminated on the outer surface side of the bonded glass substrate, a thin film transistor 14 and a transparent electrode 15 are formed on the opposite surface, and an alignment film 16 is further laminated. The glass substrates 6 and 13 are bonded together by interposing a spacer 12 for securing a liquid crystal sealing region between the glass substrates and facing the surfaces on which the alignment films of the glass substrates are formed.

  The FPD other than the liquid crystal display also has a structure in which members are laminated on a glass substrate. The FPD is required to be further thinned, and this requirement is met by chemically or mechanically polishing the glass substrate surface.

  One method of chemical polishing is to reduce the thickness of a glass substrate by bringing an aqueous solution in which hydrofluoric acid or the like is dissolved into contact with the glass substrate surface to dissolve the glass substrate surface. On the other hand, mechanical polishing can polish the glass substrate surface by moving the glass substrate in contact with the polishing pad under the condition that the slurry containing cerium oxide is interposed between the glass substrate and the polishing pad. It is used as a method of mechanical polishing. This method of mechanically polishing using a slurry containing cerium oxide is known as a method capable of performing high-precision polishing with high flatness.

  However, the glass substrate before polishing usually has scratches, and when the glass substrate with scratches on the surface is chemically polished, some scratches can be removed, but the size is small. There are also wounds that expand. Furthermore, even after the scratches are removed by chemical polishing, new scratches may occur on the glass substrate surface due to external contact of the glass substrate surface.

  On the other hand, when surface polishing with high flatness is performed by a mechanical polishing method using a slurry containing cerium oxide, the glass substrate surface scratch removal rate is higher than chemical polishing, and the scratches are enlarged. Problems are unlikely to occur.

  If there is a scratch on the surface of the glass substrate, it causes a variation in light refraction on the surface of the glass, resulting in distortion of the image displayed on the FPD. When there is a scratch that can be visually confirmed on the surface of the glass substrate, the distortion of the image displayed by the FPD can be visually confirmed, and this distortion becomes more noticeable as the size of the scratch increases. Degradation is brought about. Further, even if the scratches cannot be visually confirmed, if the scratches are adjacent to each other, there is a problem in that the displayed image is distorted.

  If re-polishing is performed to suppress distortion of the displayed image, it becomes a cumbersome operation involving polishing the glass substrate surface that does not need to be polished, and the thickness is reduced again by polishing. Therefore, the uniformity of the thickness of each glass substrate is impaired. Further, when chemical polishing is performed, there is a scratch that further increases in size, and when mechanical polishing is performed, there is a glass substrate that is cracked by applying mechanical stress to the thinned glass substrate. .

  On the other hand, if the transparent resin is injected into the scratches on the surface of the glass substrate and cured, the flatness of the glass substrate is improved. At this time, even if the glass surface is flat at the time of injection, the resin shrinks at the time of curing, so that the glass substrate after resin curing becomes a glass substrate with insufficient flatness. In order to improve the insufficient flatness, a method of removing a cured resin unnecessary for improving the flatness of the glass substrate from the glass substrate by curing after injection of a resin overflowing from the scratches is used. However, this removal causes the following problems.

  FIG. 3 is a diagram for explaining a situation in which the cured resin portion overflowing from the surface scratches on the glass substrate is removed. FIG. 3 (a) shows a case where the cured resin 20 overfilled on the surface scratches on the glass substrate 19 is formed. It is a cross-sectional schematic diagram showing the overflowing state, and the surface of the resin 20 filling the scratches is in a state of protruding from the surface of the glass substrate 19. FIG. 3B is a diagram illustrating a state in which a portion of the cured resin 20 protruding from the surface of the glass substrate 19 is removed. The removal of the cured resin 20 shown in the figure is performed by rolling the tip of the scraper 21, which is a thin plate having a sharp tip, along the surface of the glass substrate 19. Although the cured resin 20 protruding from the surface of the glass substrate 19 can be removed by rolling the scraper 21 along the surface of the glass substrate 19, the cured resin to be filled in the wound is the surface of the glass substrate 19. There is a case where the cured resin 20a integrated with the resin protruding from the surface is removed, and there is a problem that an unnecessary amount of resin used for injecting the resin again into the portion where the cured resin 20a is removed is increased.

In view of the above circumstances, the present invention provides an FPD manufacturing method that improves the flatness of a glass substrate surface by filling a resin on glass surface scratches that have undergone a chemical polishing process , and realizes a reduction in unnecessary resin usage. The purpose is to provide.

The present invention is intended to improve the flatness of the surface of the glass plate by filling a transparent resin in the recess of the glass substrate surface, of the glass substrate in a state in which a display device of a flat panel display on the back surface, fluoride A thinning process in which an acid-dissolved aqueous solution is contacted to dissolve the surface of the glass substrate , and a curable resin is injected into the recesses present on the surface of the glass substrate , and the curable resin has a jelly-like hardness. The first curable resin that is used in the first filling step in order to completely cover the incompletely covered concave portion and the first filling step to incompletely cure the indented portion until incompletely cured. A second filling step of additionally injecting into the recess to cure the curable resin, and flattening the glass substrate to complete a flat panel display. According to this manufacturing method, incompletely cured resin filled in the first filling step is in progress is contracted by incompletely cured, incompletely cured resin due to be subsequently curing the incompletely cured resin shrinkage Is a small contraction. Further, the resin curing in the second filling step causes the incompletely cured resin filled in the first filling step to be cured more than the resin injected in the second filling step.

According to the present invention, in a second filling step, the method after filling a recess inside on the glass substrate surface by injecting the uncured resin on the incompletely cured resin filled in the first filling step performing resin curing Therefore, the shrinkage rate of the incompletely cured resin is reduced, and the shrinkage of the uncured resin with a small amount of injection has little influence on the flatness, so the flatness of the glass plate after filling is high, The flattening method of the glass plate which reduced the amount of resin to be used is implement | achieved. In addition, the amount of resin injected onto the incompletely cured resin is an amount overflowing the concave portion on the surface of the glass plate, and the resin inside the scratch is simultaneously removed when the overflow resin protruding from the glass substrate surface after the resin is cured is removed. Even if the situation to be removed occurs, since the curing of the incompletely cured resin proceeds more than the resin injected onto the incompletely cured resin, the cured resin to be removed is the resin injected onto the uncured resin. By remaining in the cured product, the amount of resin to be injected again can be reduced.

In addition, the FPD manufactured by the present invention is an FPD with high display quality in which image distortion is suppressed.

  Hereinafter, the present invention will be described based on embodiments. The glass substrate to be planarized in the present embodiment is obtained by bonding a pair of rectangular glass substrates, and a liquid crystal cell region in which liquid crystal is sealed is provided between the pair of glass substrates.

  On the surface of one of the bonded glass substrates, a black matrix and a color filter are laminated in a predetermined pattern on the surface to be the liquid crystal cell region, and then the overcoat, transparent electrode, and alignment film are in the liquid crystal cell region. A glass substrate is sequentially laminated so as to cover the surface of the glass substrate, and a spacer for securing a liquid crystal cell space is dispersed on the alignment film between the two glass substrates. On the surface of the other glass substrate, after a thin film transistor and a transparent electrode are formed in a predetermined pattern, an alignment film layer is laminated thereon so as to cover the surface of the glass substrate serving as a liquid crystal cell region. Bonding of one glass substrate on which a black matrix or the like is formed and the other glass substrate on which a thin film transistor is formed is such that the alignment film forming surfaces of both glass substrates face each other and a sealing agent is interposed between both glass substrates. Has been done by. The liquid crystal cell region is partitioned by the sealing agent, and the sealing agent surrounding the sealing agent that partitions the liquid crystal cell region is interposed between the two glass substrates. The sealing agent surrounding the sealing agent that partitions the liquid crystal cell region plays a role of preventing the polishing liquid from entering the liquid crystal cell present on the bonded glass substrate.

  The bonded glass substrate in the present embodiment is chemically polished on the surface. In this chemical polishing, an aqueous solution in which hydrofluoric acid is dissolved is used as a polishing liquid, and the glass substrate surface is dissolved by immersing the bonded glass substrate in this polishing liquid to make the glass substrate thinner. After the glass substrate is immersed in the polishing liquid, a cleaning process for removing the polishing liquid from the surface of the glass substrate is performed. On the glass surface after chemical polishing, there are concave portions due to scratches caused by the glass substrate surface scratches existing before the polishing and scratches caused by external contact of the glass substrate surface until the polishing is completed. Yes.

  FIG. 1 is a diagram for explaining a planarization method in the present embodiment. In this flattening method, the resin is filled into the concave portion of the glass substrate surface where scratches existing on the glass substrate surface are formed in a plurality of times, and this filled resin is not filled after filling with the curable resin. After the first resin filling step for complete curing and the second resin filling step after the first resin filling step, the second resin filling step for filling the curable resin in the concave portions where the scratches are formed, and the second resin filling step A step of removing the cured resin protruding from the surface of the glass substrate is provided. In the present embodiment, the first resin filling step is performed once. However, the second resin filling step may be performed after the first resin filling step is repeated. When the first resin filling step is repeated, the resin is cured little by little. When an ultraviolet curable resin is used, since the ultraviolet irradiation energy irradiated for resin curing is small, the liquid crystal and the like are deteriorated. It will be prevented.

  FIG. 1A is a schematic cross-sectional view of a glass substrate 1 having a scratch 2 on the surface. This glass substrate 1 represents only the glass plate portion of the bonded glass substrate after chemical polishing. On the surface of the glass substrate 1, there is a scratch 2 having a size that can be visually confirmed, which causes distortion of the display image on the liquid crystal display. The scratches present on the surface of the glass substrate are indefinite shapes for both the planar shape and the internal shape viewed from above the scratches that can be observed externally, and the planar shape has a diameter of 50 μm or more. The diameter of a planar scratch in the specification refers to the maximum diameter of a scratch when viewed in plan.

  FIG. 1B is a schematic cross-sectional view showing a state in which the resin 3 is injected into the scratch existing on the surface of the glass substrate 1 in the first resin filling step. A curable resin is used as the resin injected into the wound. As this curable resin, a methacrylic acid resin or an acrylic acid resin having a refractive index after curing of the same degree as that of glass is selected and used in order to prevent distortion of the display image. Further, as the curable resin, a curable resin such as a thermosetting resin or a photo-curing resin can be used. In this embodiment, the anaerobic condition is cured when both the anaerobic condition and the ultraviolet irradiation condition are met. An ultraviolet curable resin is selectively used.

  The resin is injected into the wound using an injector such as a microsyringe. At this time, the amount of the resin injected into the wound is preferably an amount that does not fill the wound. In addition, when the size of the scratch is small and it is difficult to inject the resin into the inside of the wound with an injector, the resin is applied to the surface of the glass substrate, and the resin applied to the wound is allowed to penetrate into the inside of the wound. In order to complete the injection of the resin into the wound, for example, the coated resin is pressed and penetrated into the wound by covering the surface of the coated resin and pressing the film.

  FIG.1 (c) is a cross-sectional schematic diagram of the glass substrate 1 showing the state which the resin 3 inject | poured into the damage | wound was incompletely hardened. Incomplete curing of the resin 3 is performed by covering a scratched surface while adhering a film that transmits an ultraviolet wavelength (not shown) that cures the resin 3 (not shown) to the resin, thereby curing the resin 3 after blocking the resin surface from the outside air. This is performed by irradiating with ultraviolet rays having a wavelength. This ultraviolet irradiation is performed so that the resin 3 is not completely cured. In the present embodiment, the irradiation is performed until the resin 3 is incompletely cured and has a jelly-like hardness. The irradiation time of the ultraviolet rays at which the resin has a jelly-like hardness is appropriately set depending on the type of the resin 3. By irradiating with ultraviolet rays, the incompletely cured resin is in a contracted state as compared with before the start of curing.

  If there is an incompletely cured resin that does not fit in the wound, it is not a completely cured resin, so if you scrape the scraper along the glass substrate, you can easily scrape off the resin that does not fit in the wound. it can.

  FIG.1 (d) is a cross-sectional schematic diagram of the glass substrate which passed through the 2nd resin filling process. The resin 4 used in the second resin filling step is the same resin as the resin 3 that can be used in the first resin filling step. The resin injecting method and the curing method of the injected resin are as follows. The same method as the one resin filling step is taken. In the second resin filling step, the amount of resin 4 injected is such that a sufficient amount of resin is injected to fill the scratches, and resin curing is performed until the resin 4 is cured. At this time, since the resin 3 that has been incompletely cured in the first resin filling process has already contracted due to this incomplete curing, the further contraction of the resin 3 is very small, and a small amount of the resin 3 as viewed from the internal volume of the entire wound. Even if the resin injected in the second resin filling step contracts, the volume change of the entire resins 3 and 4 filled in the wound becomes minute. Therefore, the flatness of the glass substrate due to the shrinkage of the resins 3 and 4 is suppressed. Further, since the curing of the resin 3 filled in the first resin filling step proceeds with the resin curing in the second resin filling step, the resin 3 filled in the first resin filling step The resin becomes harder than the resin 4 filled in the resin filling step.

  FIG.1 (e) is the schematic diagram showing the state which removes the cured resin which protrudes from the glass substrate which passed through the 2nd resin filling process. The removal of the cured resin is performed in order to remove unnecessary resin 4b that impairs the flatness of the glass substrate 1, and this unnecessary resin 4b is excessively filled in the scratches on the surface of the glass substrate 1 to form glass. Resins that protrude from the surface of the substrate 1 and impair the flatness of the glass substrate 1 are targeted. Unnecessary resin 4b is removed by scraping the resin along the surface of the glass substrate 1 and scraping the resin. After removing the unnecessary resin 4b, the resin 4 filled in the scratches in the second resin filling step is filled with only the resin 4a necessary for filling the scratches on the surface of the glass substrate 1 and improving the flatness. Resin 4b that remains and is unnecessary for the flatness of glass substrate 1 is scraped off by scraper 6. Even if the resin 4a is removed together when the resin 4b is removed by the scraper 8, the resin 3 filled below the resin 4a is a cured resin having a higher hardness than the resin 4a. Removal with the resin 4a is prevented. Therefore, when the resin 4a is removed, there is no need to refill the resin including the filling amount of the resin 3 inside the wound, and the amount of the resin used can be reduced.

  A polarizing film is attached to the surface of the glass substrate that has been subjected to the planarization method, and a liquid crystal display is manufactured using the glass substrate to which the polarizing film is attached.

  In the said embodiment, although demonstrated about the glass substrate for liquid crystal displays which bonded a pair of glass substrate, the glass substrate used as the object planarized in this invention may be one glass substrate before bonding. Moreover, the glass substrate used for FPDs other than a liquid crystal display may be sufficient.

  The flattening method in the above embodiment is a method in which a glass surface scratch is directly filled with a resin and cured, but an undercoating treatment is performed on the scratch surface before filling the resin to improve the adhesion between the resin and the glass. Also good.

  Moreover, you may use what mixed the glass powder and / or resin powder which have the same refractive index and light transmittance as a glass substrate as resin used at the 1st resin filling process in the said embodiment.

It is a figure for demonstrating embodiment of the planarization method which concerns on this invention. It is a schematic diagram of the panel cross section of a liquid crystal display. It is a figure for demonstrating the condition which removes the cured resin part overflowing from the glass substrate surface crack.

Explanation of symbols

1 Glass substrate 2 Scratches 3, 4, 4a, 4b Resin 5 Scraper

Claims (4)

A thinning step in which an aqueous solution in which hydrofluoric acid is dissolved is brought into contact with the surface of the glass substrate in a state where the display element of the flat panel display is provided on the back surface, and the surface of the glass substrate is dissolved,
A first filling step of injecting a curable resin into a concave portion present on the surface of the glass substrate , and incompletely curing the curable resin until the curable resin has a jelly-like hardness, and covering the concave portion incompletely ;
The so incompletely covered recess to completely cover a second filling step of curing when used the same said curable resin the curing resin by adding injected into the recess in the first filling step,
A flat panel display manufacturing method completed by flattening a glass substrate . The manufacturing method according to claim 1, wherein the curable resin is an ultraviolet curable resin that is cured by irradiation with ultraviolet rays . The manufacturing method according to claim 2, wherein the curable resin is an anaerobic ultraviolet curable resin that cures when both anaerobic conditions and ultraviolet irradiation conditions are met . The manufacturing method according to claim 1, wherein the flat panel display is a liquid crystal display in which a liquid crystal cell region in which liquid crystal is sealed is provided between a pair of glass substrates .

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