KR101097430B1 - Flexible substrate for display panel - Google Patents

Abstract

The present invention relates to a flexible substrate for a display panel, and an object of the present invention is to minimize the stress generated on the adhesive surface due to the difference in the expansion coefficient between the resin and the metal mask to prevent light leakage of the liquid crystal display device. It is to provide a flexible substrate for a display panel that can be.

The flexible substrate for a display panel according to the present invention includes a metal mask composed of a metal material and a plurality of openings are formed in a lattice pattern, and a heat resistant resin in which inorganic particle fillers are dispersed and impregnated with the metal mask. Characterized in that.

Display, Flexible Board, Metal Mask

Description

Flexible board for display panel {FLEXIBLE SUBSTRATE FOR DISPLAY PANEL}

The present invention relates to a flexible substrate for a display panel, and more particularly, to minimize stress generated on an adhesive surface between a resin constituting the substrate and a metal mask, thereby preventing light leakage from the liquid crystal display. It is to provide a flexible substrate for a display panel.

Currently, a display device (for example, a liquid crystal display device) that is widely used uses a transparent electrode substrate made of a glass material. However, the glass substrate has a limitation in thinning and reducing the weight of the liquid crystal display due to its thick thickness and heavy weight, and is vulnerable to impact resistance.

Accordingly, a flexible substrate made of a plastic optical film material is in the spotlight as a material to replace the conventional glass substrate, and the flexible substrate is very suitable for next-generation display devices such as liquid crystal displays, organic ELs, and electronic papers (e-paper). It has suitable characteristics.

Compared to the glass substrates used in conventional display panels, the flexible substrate made of plastic optical film material is thin, light, flexible, flexible, and can be processed into various forms, thereby reducing the weight, thickness, and The surface display function can be implemented.

Due to the advantages of the flexible substrate as described above, various researches and developments are being made on materials and structures of the flexible substrate.

In detail, in the initial stage of development, there is an example in which a transparent film material made of a plastic polymer is used, and an epoxy resin, an acid anhydride-based curing agent, a composition using an alcohol curing catalyst, or the like is applied as a material of the flexible substrate.

However, the flexible substrate composed of the above materials has a large coefficient of linear expansion, and especially when applied to an active matrix display element substrate, it causes problems such as warpage and disconnection of aluminum wiring in the manufacturing process, and is more resistant to heat than the glass substrate. Thermal characteristics such as coefficient of thermal expansion (CTE) and optical characteristics such as transparency and refractive index are weak, which limits the application of the flexible substrate.

Therefore, in order to apply a plastic optical film material to a display panel substrate, in particular, a matrix display element substrate, heat resistance and transmittance must be satisfied, and above all, to develop a plastic optical film material having a low coefficient of thermal expansion and low surface roughness. It is essential.

As described above, a conventionally known technique for reducing the coefficient of thermal expansion of a plastic optical film material includes a composite film structure including a resin powder, an inorganic filler such as glass cloth, or the like. Development is being presented. For example, Japanese Patent Laid-Open No. 2004-51960 discloses a resin sheet containing an epoxy resin and a glass fabric in the form of glass fabric, and Japanese Patent Laid-Open No. 2004-233851 proposes a transparent substrate made of glass cloth and resin.

However, the conventional composite film structure and its manufacturing method which produce a transparent substrate by impregnating glass cloth with resin had the following problems.

First, the process of producing glass fibers in the form of a fabric is not simple, and especially when the film is made large by using a hot press method, the process becomes long and complicated because it induces film curl. Increasing the production cost, there was a problem that the production of large films is difficult.

Second, when manufacturing a glass cloth impregnated film using a UV cured resin, due to the structural properties of the glass fiber in the form of a fabric and shrinkage phenomenon of the glass cloth, the finished film is not flat surface roughness (Roughness) very There is a problem that the roughness causes a poor quality of the display device.

As another technique, Japanese Patent Laid-Open No. 2006-145934 does not use glass cloth, but instead, a Ni-Fe alloy sheet and a polyimide resin film are bonded to each other, and then baked at 250 ° C., thereby manufacturing a flexible substrate using a thermocompression method. Due to the difference in expansion coefficient therebetween, a stress is generated in the adhesive surface between the metal and the resin, causing a light leakage phenomenon as shown in FIG. 6. This light leakage phenomenon results in a deterioration of contrast when driving the liquid crystal display panel, resulting in poor image quality.

The present invention has been made to solve the above problems, and an object of the present invention is to produce an LCD panel due to the light leakage phenomenon due to the difference in expansion coefficient between the two materials in the adhesive surface with the resin when using the metal sheet as a matrix It is to provide a flexible substrate for a display panel that can prevent the contrast after the fall of the image quality.

In order to achieve the above object, a flexible substrate for a display panel according to the present invention includes a metal mask composed of a metal material and a plurality of openings are formed in a lattice pattern, and inorganic particles filler is dispersed and impregnated with a metal mask. It is characterized by including a heat resistant resin to be provided.

Another flexible display panel for a display panel according to the present invention for achieving the above object is a metal mask composed of a metal material and a plurality of openings in a lattice pattern (Metal Mask), containing a ceramic powder and deposition or spray coating It is characterized in that it comprises a heat-resistant resin impregnated with a resin to be coated on the surface of the metal mask and the resin-coated metal mask through.

Another flexible display panel for a display panel according to the present invention for achieving the above object is a metal mask composed of a metal material and a plurality of openings in a lattice pattern, and etching the surface of the metal mask (Etching) And a heat resistant resin impregnated with the ceramic powder coated on the etched metal mask surface, and the metal mask coated with the ceramic powder.

According to the flexible substrate for a display panel according to the present invention, the dimensional stability of the heat resistant resin having a high coefficient of thermal expansion can be improved, and above all, stress generated on the adhesive surface due to the difference in the expansion coefficient between the resin and the metal mask can be improved. Since it can be minimized, the light leakage phenomenon of the liquid crystal display device can be prevented.

In addition, there is no variation in height, and in particular, when the opening surface of the metal mask is configured to be square, the thermal expansion coefficient can be induced uniformly as the opening surfaces having the same length ratio are arranged at the same interval, so that the coefficient of thermal difference is uniform. It is effective to secure the sex.

In addition, as the height is constant over the entire surface of the metal mask, it is possible to minimize the occurrence of surface roughness (Roughness) defects on the substrate by the impregnated material.

1 (a) to (c) is a view showing a manufacturing process of a flexible substrate for a display panel according to a first embodiment of the present invention, Figure 2 is a AA 'of the flexible substrate completed through the manufacturing process of FIG. Figure 3 is a cross-sectional view, Figure 1 is an embodiment photograph showing a flexible substrate of the present invention actually produced through the manufacturing process.

In the flexible substrate for a display panel according to the first embodiment of the present invention, a metal mask 110 including a plurality of openings having a lattice pattern is manufactured by using Ni-Fe alloy (Alloy), and The metal mask 110 presents a film structure configured to impregnate the inorganic particle filler into the heat-resistant resin 120 containing dispersion.

The film structure of the present invention as described above can improve the dimensional stability of the heat-resistant resin 120 having a high coefficient of thermal expansion, and above all, the stress generated on the adhesive surface due to the difference in the expansion coefficient of the resin and the metal mask 110 ( Since stress can be minimized, the light leakage phenomenon of the liquid crystal display device can be prevented.

In addition, the metal mask has no variation in height, and in particular, when the opening surface of the metal mask 110 is configured to have a square shape, the openings having the same length ratio are arranged at equal intervals, thereby inducing a thermal swelling uniformly. There is an advantage that can ensure the uniformity of the thermal difference coefficient.

In the flexible substrate according to the first embodiment of the present invention, a metal mask having a mesh shape using Ni-Fe alloy is prepared, and the inorganic particle filler is dispersed and contained in the heat resistant resin 120. And impregnating and curing the metal mask 110 in the liquid heat resistant resin 120 containing the inorganic particle filler.

Hereinafter, each manufacturing step, preferred embodiments, and technical features of the flexible substrate for a display panel according to the present invention will be described in detail with reference to FIGS. 1 to 3.

(1) Metal Mask Manufacturing Step

The metal mask 110 of the present invention is impregnated with the heat resistant resin 120 constituting the flexible substrate to lower the high coefficient of thermal expansion of the film itself made of the heat resistant resin 120 to improve the dimensional stability of the substrate.

However, in order to use the substrate made of the heat resistant resin 120 impregnated with the metal mask 110 in the display panel, the problem of transparency and light leakage must be overcome.

In order to solve the transmittance problem, the metal mask 110 of the present invention uses a black matrix of a color filter provided on the front of the LCD panel when the flexible substrate manufactured according to the present invention is used in the LCD. Matrix) and have the same shape.

If the shape of the metal mask 110 is different from that of the black matrix, the transmittance of light is reduced, which affects the brightness of the LCD panel, and also the metal mask 110 where R, G, and B light is transmitted. This is because there is a problem in that some patterns are hidden due to the presence of a pattern of).

Therefore, as shown in FIG. 4, the metal mask 110 of the present invention is configured to have a lattice pattern in which the rectangular opening surfaces 115 are repeatedly formed at regular intervals, and specifically, form a lattice pattern. The thickness of the line (hereinafter, referred to as the line width) and the distance between the lines (hereinafter, referred to as pitch) are the line widths of the vertical and horizontal lines of the black matrix forming the color filter. It should be configured to be close to the pitch, preferably the line width and pitch of the metal mask 110 is preferably configured to be the same as the line width and pitch of the black matrix. This is to ensure good image quality by preventing the emitted R, G, and B light from being disturbed by the lattice pattern of the metal mask 110.

As described above, the metal mask 110 of the present invention is preferably configured to have an aperture ratio of at least 70%. Specifically, the metal mask 110 of the present invention has a vertical width of 50 μm or less, and a horizontal line of 10 The line width within the μm, the pitch is composed of 250 ~ 300㎛, but the line width and pitch is not necessarily limited to this because it is somewhat different depending on the size of the liquid crystal display panel manufacturer and the liquid crystal display device.

The metal mask 110 of the present invention has nickel (Ni) and iron (Fe) as main components, and is preferably manufactured using Ni-Fe Alloy having a thermal expansion coefficient of 7 ppm or less. When the thermal expansion coefficient constituting the metal mask 110 exceeds 7 ppm, the high thermal expansion coefficient of the resin itself may not be attenuated sufficiently. Accordingly, the LCD may be expanded due to shrinkage expansion of the plastic substrate when the LCD process is applied at 180 ° C. This is because a change in the phase difference of the panel pattern cell occurs and a high-definition plastic LCD panel cannot be obtained.

Table 1 below is a comparative data showing the thermal expansion coefficient of Ni-Fe Alloy according to the mixing ratio of nickel and iron.

As can be seen from Table 1, 42Ni-Fe Alloy shows a constant coefficient of thermal expansion all within the range of 20 ℃ to 300 ℃, 36Ni-Fe Alloy has the lowest thermal expansion in the range of 20 ~ 200 ℃ corresponding to the LCD process of 180 ℃ Show coefficients.

The metal mask 110 of the present invention has an expansion coefficient of 7 ppm or less and all have a constant thermal expansion coefficient of 42Ni-Fe Alloy or 36Ni having an lowest thermal expansion coefficient at an LCD process temperature (180 ° C). It is preferable to configure with -Fe Alloy, but is not necessarily limited thereto.

For example, the metal material constituting the metal mask 110 of the present invention may be any type as long as the metal material does not oxidize at a temperature of 7 ppm or less and has an expansion coefficient of 7 ppm or less. This is because when oxidized at 200 ° C. or less, foreign matters due to metal oxidation are mixed in the LCD process.

Hereinafter, a metal mask manufacturing method according to the present invention will be described in detail. Specifically, the method of manufacturing a metal mask grating pattern made of Ni-Fe alloy material and having the same shape as the black mask 110 forming the color filter is as follows.

After attaching a photosensitive dry film on a plate having a thickness of 100 μm or less, stacking and exposing an exposure film having a line width and a pitch of the black mask 110 forming a color filter, the exposure film By developing the pattern, the pattern having the same dimensions as the line width and pitch of the black mask can be secured, and can be produced by performing an etching process of the Ni-Fe alloy film through the secured pattern.

(2) dispersing and containing the inorganic particle filler in the heat resistant resin

As the heat resistant resin 120 constituting the flexible substrate of the present invention, UV curable or thermosetting resin is used, and specific examples thereof include polysulfone, polyether, polyether lmide, and polyarylate. It is preferable to use at least one selected from a heat resistant resin having a glass transition point of 200 ° C. or higher, such as (PAR: polyarylate), but is not necessarily limited thereto.

This is because, when the flexible substrate according to the present invention is applied to a liquid crystal display process requiring a process temperature of 180 ° C. or higher, it is necessary to minimize dimensional stability by minimizing substrate deformation due to the high coefficient of thermal expansion of the resin itself.

In addition, the heat-resistant resin 120 constituting the flexible substrate of the present invention is a low-expansion inorganic to prevent light leakage caused by the excessive difference in the coefficient of thermal expansion between the metal mask 110 and the heat-resistant resin 120 impregnated in the resin It was comprised so that a particle filler might contain dispersion.

As the inorganic particle filler, it is preferable to use ultrafine ceramic powder having a particle size of 150 nm or less and a coefficient of thermal expansion of 8 ppm or less. This may be included in the heat-resistant resin 120 using the cera membrane powder having a particle size of more than 150 nm, scattering of light that passes through the film may occur, resulting in a decrease in transmittance and unclear image quality. Because.

In addition, it is preferable to mix content of the said inorganic particle filler in the range which does not reduce a board | substrate transmittance, and it is good to comprise in the compounding ratio within 5-50 wt% specifically ,.

This means that when the inorganic particle filler content is less than 5wt%, the high expansion coefficient of the heat resistant resin 120 itself cannot be sufficiently lowered, so that stress generated at the adhesive surface between the metal mask 110 and the resin cannot be minimized. When the content exceeds 50wt%, the transmittance of the resin itself is lowered, and thus it cannot be used as a display panel substrate.

(3) impregnating a heat resistant resin with a metal mask

The manufacturing process of the flexible substrate according to the present invention is completed by impregnating the prepared metal mask 110 in the liquid heat resistant resin 120 containing the inorganic particle filler and curing. Coating and coating operations of the liquid heat-resistant resin 120 can be achieved by using a slit die coater (Slit Die Coater), etc. This is a known technique, detailed description thereof will be omitted.

The flexible substrate of the present invention manufactured through the above process attenuates the high coefficient of thermal expansion of the heat resistant resin 120 itself due to the low coefficient of thermal expansion of the metal mask 110 composed of Ni-Fe alloy to improve the dimensional stability of the substrate. In addition, by dispersing the ultrafine ceramic powder in the resin impregnated with the metal mask 110, it is possible to prevent light leakage caused by an excessive difference in the expansion coefficient between the resin and the metal mask 110.

Hereinafter, another embodiment for preventing light leakage of a substrate made of a heat resistant resin impregnated with a metal mask will be described.

According to another embodiment of the present invention, after coating a resin containing a ceramic powder (hereinafter referred to as a mixed resin) on a surface of a metal mask patterned in a specific form, the mixed metal coated metal mask is first implemented. Similarly to the example, the flexible substrate is completed by impregnation curing with a heat resistant resin.

As the ceramic powder contained in the mixed resin, a thermal expansion coefficient of 7 ppm or less and a particle size of 150 nm or less are preferably used. This is because when the particle size exceeds 150 nm, the stress at the interface with the resin cannot be sufficiently reduced. For example, it is preferable to use alumina or zirconia, but is not necessarily limited thereto.

The mixed resin coated on the surface of the metal mask may be deposited by immersing the metal mask in the liquid mixed resin solution or by spray coating. In addition, as the resin constituting the mixed resin, UV-curable or thermosetting resin is used as in the first embodiment, and specific examples thereof include polysulfone, polyether, polyether lmide and polya. It is preferable to use at least one selected from heat-resistant resins having a glass transition point of 200 ° C. or more, such as a rel: polyarylate, but is not necessarily limited thereto.

According to another embodiment of the present invention, a flexible substrate is formed by etching a surface of a metal mask patterned into a specific shape, coating ceramic powder on the etched metal mask surface, and then impregnating and curing the heat resistant resin. To complete.

The ceramic powder coated on the surface of the metal mask may preferably use a thermal expansion coefficient of 7 ppm or less and a particle size of 150 nm or less.

That is, the other embodiments of the present invention as described above, like the first embodiment, proposes a film structure for minimizing light leakage by attenuating stress generated at the adhesive surface of the heat-resistant resin impregnated with the metal mask and the metal mask. .

Table 2 is measurement data obtained by actually fabricating the flexible substrate according to the first embodiment of the present invention and measuring the respective characteristics.

The flexible substrate used in Table 2 was a polyarylate-based heat-resistant resin, and the ultrafine ceramic powder contained in the heat-resistant resin was a spodumene mineral powder having a refractive index of 1.63 of polyarylate. It was prepared by a method of preparing by placing in a flame and cooling by vaporization. The thermal expansion coefficient of the powder was 1.2 ppm, and an average particle size of 100 nm or less was used.

In addition, in order to measure the degree of light leakage, the flexible substrate of the present invention between the two polarization (Polarization) film, which is an optical film, the method of measuring the luminance with BM-7 by irradiating a backlight (BLU, Backlight Unit) from the back The degree of light leakage was measured through. The comparative example of Table 2 corresponds to the conventional board | substrate which adhere | attached the metal sheet which has an opening ratio of 85% to polyarylate resin.

Referring to Table 2, the flexible substrate according to the present invention can secure a transmittance of 85% or more and a thermal expansion coefficient of 20 ppm or less corresponding to appropriate conditions when manufacturing a liquid crystal display panel, and at the same time, a flexible substrate including a metal sheet. Compared with this, it can be seen that the light leakage can be greatly reduced.

5 is a photograph showing a state in which light leakage is removed by applying the flexible substrate according to the present invention. As shown in FIG. 5, the liquid crystal display device employing the flexible substrate according to the present invention can minimize light leakage when the panel is driven. Accordingly, a high-definition plastic LCD can be prevented by reducing contrast caused by light leakage. Panels can be produced.

In the above, although the preferred embodiment of the present invention has been described and illustrated, it is obvious that various changes and changes can be made without departing from the spirit and scope of the following claims. Such modified embodiments should not be understood individually from the spirit and scope of the present invention, but should fall within the claims appended to the present invention.

1 (a) to (c) illustrate a manufacturing process of a flexible substrate for a display panel according to a first embodiment of the present invention.

2 is a cross-sectional view taken along line A-A 'of the flexible substrate completed through the fabrication process of FIG.

3 is an embodiment showing a flexible substrate of the present invention actually manufactured through the manufacturing process.

4 is an embodiment showing a metal mask according to the present invention.

5 is a photograph showing a state in which light leakage is removed by applying the flexible substrate according to the present invention.

Figure 6 is a photograph showing a light leakage phenomenon occurs when driving a conventional liquid crystal display device applying a substrate.

Claims (12)

Flexible substrate for display panel comprising a metal mask (Metal Mask) consisting of a metal material and a plurality of openings of the lattice pattern, and a heat-resistant resin dispersed in the inorganic particle filler and impregnated with the metal mask . The method of claim 1, The inorganic particle filler is a ultrafine ceramic powder having a particle size of 150 nm or less and a thermal expansion coefficient of 8 ppm or less. The method of claim 1, The content of the inorganic particle filler contained in the heat resistant resin is a flexible substrate for a display panel, characterized in that 5 to 50wt%. A metal mask composed of a metal material and having a plurality of openings formed in a lattice pattern, a resin containing ceramic powder and coated or formed on the surface of the metal mask through deposition or spray coating; A flexible substrate for display panel, comprising a heat resistant resin impregnated with a metal mask. A metal mask composed of a metal material and having a plurality of openings formed in a lattice pattern, a ceramic powder coated on the etched metal mask surface by etching the surface of the metal mask, and the ceramic powder A flexible substrate for display panel, comprising a heat resistant resin impregnated with a coated metal mask. The method according to claim 4 or 5, The ceramic powder has a thermal expansion coefficient of 7 ppm or less and a particle size of 150 nm or less. The method according to any one of claims 1, 4 or 5, The shape of the metal mask is a flexible substrate for a display panel, characterized in that formed in the same shape as the shape of the black matrix (Black Matrix) of the color filter (Color Filter). The method according to any one of claims 1, 4 or 3, The metal material is a flexible substrate for a display panel, characterized in that the thermal expansion coefficient of 7ppm or less. The method according to any one of claims 1, 4 or 5, The line width and the pitch of the metal mask are the same as the line width and the pitch of the black matrix. The method according to any one of claims 1, 4 or 5, The metal mask is configured to have an aperture ratio of at least 70%. The method according to any one of claims 1, 4 or 5, The metal material is a flexible substrate for a display panel, characterized in that 36Ni-Fe alloy (Alloy) or 42Ni-Fe alloy. The method according to any one of claims 1, 4 or 5, The heat resistant resin is a heat resistant resin having a glass transition point of 200 ° C. or higher, and is at least one selected from polysulfone, polyether, polyether lmide, and polyarylate (PAR: polyarylate). A flexible substrate for display panel, characterized by the above-mentioned.

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