JPH0836151A - Laminating method of planer substrate - Google Patents

Abstract

PURPOSE:To provide a laminating method of planer substrates so that substrates can be laminated without causing troubles due to swelling of a resin. CONSTITUTION:Two planer substrates 11, 12 are laminated to each other by this method. In this method, a groove 11A to reserve the resin swelling from the substrate 11 is formed in the edge part of the face as the sticking face of one or both planer substrates 11, 12. An adhesive resin 21 is supplied to at least one of the sticking faces of the substrates 11, 12, two substrates 11, 12 are disposed to face each other, and then the resin 21 is spread by a pressing means 32 and hardened to laminate the planer substrates.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for bonding a flat substrate and a thin glass substrate with an adhesive resin.
The present invention relates to a flat plate microlens array for constructing a liquid crystal display element and a method for laminating a flat substrate which is effective when manufacturing a liquid crystal display element using the same.

[0002]

2. Description of the Related Art Conventionally, in a method of laminating flat substrates to each other with an adhesive resin, it is general that the substrates used have the same size. Also,
Even if the sizes are different, it is general that the substrate surface is bonded as it is without any special treatment or processing.

[0003]

In the conventional bonding method described above, the resin developed at the time of bonding the substrates sticks out from the outer peripheral portion of the substrates and adheres to the surface plate surface of the pressure platen device. There was something that happened. For example, when the flat substrate and thin glass are bonded by resin curing in a state of being pressed and adhered by a pressure platen, the resin (burrs) protruding to the outer peripheral portion of the substrate after curing is mechanically removed. It had to be wiped off with solvent and washed. Further, the resin adhering to the surface of the pressure platen needs to be removed in the same manner, which causes a serious problem that productivity is not improved.

Further, when the flat substrates to be bonded have the same size, if the centers of the substrates are deviated (eccentricity) at the time of bonding, portions of one of the substrates protrude. If one of the substrates is a thin glass substrate, the protruding portion of the thin glass substrate is liable to be chipped or cracked during handling of subsequent steps such as cleaning and film formation, resulting in a problem of low yield. It was In the present invention, in the method of bonding flat substrates, the bonding can be performed without causing trouble due to resin protrusion, and when one of the flat substrates is a thin glass substrate, the outer circumference of the thin glass substrate after bonding It is an object of the present invention to provide a flat substrate bonding method capable of reducing chipping and cracking of a portion.

[0005]

In order to solve the above problems, the present invention provides a method of bonding two flat substrates to each other, wherein one or both of the two flat substrates are bonded to each other. A groove for accumulating the resin protruding from the substrates is provided in the peripheral part of the surface to be formed, and the adhesive resin is supplied to at least one surface that is the adhesion surface of the two substrates.
Provided is a method for laminating flat substrates, wherein the two substrates are arranged so that the resin supply surfaces face each other, the resin is spread and cured by a pressing means, and the flat substrates are pasted. To do.

In the case where the thin glass substrate is a glass substrate, in order to reduce the occurrence of chipping or cracking of the thin glass substrate during handling in the subsequent process of the bonded substrate, It is preferable to make the area smaller than the area of the flat portion of the flat substrate.

Further, for use as a flat plate type microlens array for a liquid crystal display device, both of the two low expansion glass substrates are quartz glass substrates, and at least one of the substrates has a bonding surface side surface, It is preferable that the adhesive resin has a fine concavo-convex pattern, and the adhesive resin fills the fine concavo-convex pattern to bond the two substrates.

Examples of the flat substrate that can be used in the present invention include substrates made of materials such as glass, ceramics, metals and resins. In particular, when manufacturing a liquid crystal display element, a glass substrate is used as a flat substrate, and low expansion glass is preferable. Specific examples of the glass substrate include any glass substrate such as soda lime glass, alkali aluminosilicate glass, alkali borosilicate glass, alkali-free glass, crystallized glass and quartz glass. The plate thickness is not particularly limited, and a substrate having a large rigidity of the plate itself or a thin glass substrate having a small rigidity of the plate itself may be used.

On the other hand, as the thin substrate, a substrate made of the above-mentioned material or a glass substrate of the kind given as a specific example can be used. In addition, for the purpose of using the bonded substrate of the present invention as a flat plate type microlens array for liquid crystal display devices, the plate thickness of thin glass is often 0.5 mm or less.

The shape of the resin spill-out preventing groove provided on the outer peripheral portion of the flat substrate and / or the thin glass substrate is as follows.
It is determined that the capacity is sufficient for the volume of the resin protruding. The groove on the substrate surface can be formed by various methods. For example, a glass substrate can be formed by chemical etching using an etchant containing HF, dry etching using CF ₄ plasma, and grinding.

Further, when the size of the thin glass substrate is made smaller than the size of the flat portion of the flat substrate in order to reduce the occurrence of chipping or cracking of the thin glass substrate during the handling in the post-process of the bonded substrate, There is no particular limitation on the extent to which the area is reduced. Considering the effective use of the flat substrate, the thin glass substrate may have a shape similar to that of the flat substrate, and the outer peripheral portion may be reduced by about 1 to 3 mm. In this case, the groove provided on the surface of the flat substrate is provided near the outer periphery of the bonding position of the thin glass substrate.

As the adhesive resin used in the present invention, polyester resin, epoxy resin, silicone resin, phosphazene resin, phenol resin, polyimide resin, or any other photocurable and thermosetting resin can be used. . Among them, photocurable resins such as polyester resins, epoxy resins, and silicone resins are preferable in terms of productivity because they cure in a short time.

The resin used is from 0.1 poise to 100
A wide range of viscosity up to Poise can be used. When the viscosity of the resin is low, the time required for developing the resin is short, and high pressure is not required for pressurization. on the other hand,
When the resin has a high viscosity, it takes a long time to develop the resin, and it is necessary to apply a relatively high pressure.
Considering actual work, a resin having a viscosity of about 1 to 50 poises is preferable.

In the above description, the bonding of single-plate flat substrates has been described, but one substrate may of course be a bonded substrate.

[0015]

According to the present invention, when the flat substrates are bonded together, the resin protruding from the substrates is collected in the groove, so that the resin does not protrude to the outer peripheral portion of the substrates. Therefore, the resin does not wrap around to the side opposite to the bonding surface of the substrate, and does not adhere to the surfaces of the upper and lower pressing plates.

Further, since the size of the thin glass substrate is smaller than the size of the flat portion of the flat substrate, even if some eccentricity occurs during bonding, the thin substrate protrudes outside the flat substrate. I can't make a part. Therefore, no chipping or cracking occurs during the handling in the subsequent process.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an outline of a step of laminating a flat substrate on which a resin spillover prevention groove is formed according to the present invention and a thin glass substrate having an outer diameter smaller than that of the flat substrate. (1) First, the flat substrate 11 having the resin reservoir groove 11A formed near the outer periphery of the substrate is placed on the lower pressure platen 31 of the pressure device, and the adhesive resin 21 is dropped on the flat substrate 11. (2) Next, the thin glass 12 which is slightly smaller than the flat glass substrate 11 is bonded to the adhesive resin 21 from the central portion of the thin glass 12 so that air bubbles do not enter. (3) Subsequently, the flat substrate 11 and the thin glass 12 are gently joined by the adhesive resin 21, and the upper pressure platen 32 is attached.
Pressurize with. (4) Furthermore, the pressure-sensitive adhesive resin 21 causes the planar substrate 1 to be pressed.
1 is spread evenly between the thin glass 12 and the thin glass 12, and after the excess resin flows into the resin reservoir groove, the laminated thin glass substrate 10 is irradiated with ultraviolet rays by the ultraviolet irradiation device incorporated in the pressurizing device. Alternatively, the adhesive resin is cured by performing a heat treatment by a heating device (not shown) also incorporated in the pressurizing device.

The ultraviolet irradiation device is preferably incorporated in either the upper pressure platen or the lower pressure platen of the pressure device, or both.

In the above description, the substrate 11 is not particularly limited to a flat substrate, but the bonded substrate according to the present invention is provided with the function of a flat plate type microlens and is used as a counter substrate for a liquid crystal display device or the like. In this case, the substrate 11 is preferably a low expansion glass substrate such as quartz glass. Specific examples will be described below. (Example 1) A radius of 61.75 mm from the center of a quartz glass substrate (outer diameter 125 mm, plate thickness 0.5 ± 0.01 mm)
A rectangular groove having a width of 1 mm and a depth of 0.05 mm was formed at the position of by a chemical etching method. The quartz glass substrate with the peripheral groove was used as a flat substrate and placed on a surface-polished glass lower pressure platen. Next, 0.5 ml of the epoxy photocurable resin (viscosity 1400 cP) was dropped from the cylinder. Subsequently, a quartz glass substrate (outer diameter: 124 mm, plate thickness: 0.2 mm ± 0.01 mm) was used as a thin-walled substrate and bonded to the photo-curable resin from the center so that air bubbles did not enter. This was pressed at a pressure of 5 kgf / cm ² by means of a surface-polished glass upper part pressure table. A 2P molding machine manufactured by Nikka Engineering Co., Ltd. was used as the pressure machine.

As a result, the photo-curable resin sandwiched between the two quartz substrates spread out within the substrate surface, and the excess resin flowed into the outer peripheral groove formed in the flat substrate. After the development of the resin and the inflow into the groove were completed, ultraviolet irradiation was performed.
The ultraviolet irradiation conditions were 53 mW / cm ² and 150 seconds. The resin thickness after curing was about 38 μm. Under the curing conditions of this time, the Shore D hardness of the photocurable resin is about 87, and the adhesive strength to the glass substrate is about 80 kgf.
It was / cm ² .

No resin squeeze-out was observed in the bonded substrate obtained in Example 1 above, and no resin wraparound to the surface opposite to the bonding surface was observed. Further, there was no protrusion of the thin glass substrate due to the eccentricity between the flat substrate and the thin glass substrate, and therefore, the thin glass was not chipped or cracked in the subsequent process.

(Embodiment 2) An example of a method for manufacturing a flat lens array using the method shown in Embodiment 1 will be described.

First, a quartz glass substrate (outer diameter 125 mm,
A Cr film was formed as a hydrofluoric acid-resistant protective film by a sputtering method on the surface having a plate thickness of 0.5 ± 0.01 mm.
Next, small openings were formed in the Cr film in a predetermined lens array pattern by photolithography in which photoresist was applied, exposed, and developed. The formed small aperture array is
It is a hexagonal lattice array, and thereby a honeycomb type lens array is obtained. It is desirable that the diameter of the small opening is sufficiently smaller than the diameter of the lens to be finally obtained. At the same time, a line opening having a width of 1 mm was formed at a position with a radius of 61.75 mm from the center of the substrate.

Cr having the small opening and the peripheral line opening
The film-coated substrate was immersed in an etchant containing hydrofluoric acid (HF) and sodium dodecylbenzenesulfonate (DBS) as a surfactant to perform chemical etching.
Here, the concentrations of hydrofluoric acid and sodium dodecylbenzenesulfonate were 10% by weight and 0.1% by weight, respectively. As a result, in the circular opening, the surface of the quartz glass substrate is isotropically etched starting from the circular opening of the Cr film, and a concave portion that is a part of a sphere is obtained.
In addition, in the line opening, the etching proceeds isotropically starting from the line opening of the Cr film to form a groove having a semicircular cross section. This first-stage etching is stopped while leaving a flat boundary portion having a slight width between the adjacent concave portions.

Then, after removing the Cr film from the surface of the quartz glass substrate, it was immersed again in the above etchant to etch the entire surface of the substrate. By this two-step etching,
Etching progressed in the peripheral portion of the recess, and the boundary between adjacent recesses became a ridgeline with a sharp upper end. That is, in a plan view, each has the same hexagonal shape, and the adjacent recesses are in a close-packed arrangement in which the adjacent recesses are in close contact with each other. The groove having a semicircular cross section was slightly shallowed by the second-stage etching.

The quartz glass substrate having the above-mentioned microlens pattern and the outer peripheral groove was placed on a surface-polished lower pressing plate made of glass. Next, 0.5 ml of the epoxy photocurable resin (viscosity 1400 cP) was dropped from the cylinder. Subsequently, a quartz glass substrate (outer diameter 124 mm,
A plate having a thickness of 0.2 mm ± 0.01 mm) was used as a thin substrate and bonded to the photo-curable resin from the center so that air bubbles did not enter. This was pressed at a pressure of 5 kgf / cm ² by means of a surface-polished glass upper part pressure table.

As a result, the photo-curable resin sandwiched between the two quartz substrates spread out within the substrate surface, and the excess resin flowed into the outer peripheral groove of the flat substrate. After the inflow of the resin into the peripheral groove was completed, ultraviolet irradiation was performed. The ultraviolet irradiation conditions were 53 mW / cm ² and 150 seconds. The resin thickness after curing was about 38 μm.

As described above, in the bonded substrate having the microlens function obtained in Example 2, no resin squeeze-out at the outer peripheral portion was observed.

The radius of curvature of the convex portion of the lens of the microlens array manufactured this time was 24.3 μm, and the depth of the outer peripheral groove was 20 μm. The refractive index of quartz glass is 1.46, and the refractive index of the filled epoxy resin is 1.59.
It was 5. A He-Ne laser was used to irradiate parallel rays and the focal length of the lens was measured.
It was found to be 0 μm (in air). Further, it was found that the spot diameter in the vicinity of the focal position was 5.3 μm, and that it had an excellent condensing characteristic of about the diffraction limit.

Further, a liquid crystal display device can be constructed by using the obtained bonded substrate having a microlens function.

In the above-described example of the second embodiment, the concave portion is formed on the quartz glass substrate by the etching method, but the method of supplying the sol-gel solution on the substrate and transferring the shape of the stamper to the substrate also causes the microlens and the outer periphery to be transferred. The recess of the groove can be formed.

Comparative Example 1 First, a quartz glass substrate (outer diameter 125 mm, plate thickness 0.5 ± 0.
01 mm) was placed on a surface-polished glass lower pressure platen. Next, an epoxy-based photocurable resin (viscosity 1
0.5 ml of 400 cP) was dripped from the cylinder. Subsequently, a quartz glass substrate (outer diameter 125 mm, plate thickness 0.2 mm
(± 0.01 mm) was joined to the photo-curable resin from the center so that air bubbles did not enter, and this was pressed at a pressure of 5 kgf / cm ² by the surface-polished glass upper part pressure table.

As a result, the photocurable resin sandwiched between the two quartz substrates was spread on the surface of the substrate having an outer diameter of 125 mm. The resin was cured by ultraviolet irradiation while being pressed by the upper press plate made of glass. The ultraviolet irradiation conditions were 53 mW / cm ² and 150 seconds.

In the bonded substrate obtained in Comparative Example 1, the excess resin overflows from the glass substrate,
It wraps around on the opposite side of the joined surface. Mechanically peel the bonded substrate from the glass upper pressure platen, mechanically remove the resin protrusion (burrs) on the outer peripheral edge surface of the thin wall bonded substrate, and use an organic solvent such as acetone to bond the bonded substrate and glass It was necessary to clean the upper and lower pressure platens.

Further, in a part of the outer circumference, the thin glass substrate protruded from the flat substrate and was in a state of being easily chipped or cracked by handling or the like.

[0036]

According to the present invention, the resin that has spread on the outer peripheral portion of the flat substrate and / or the thin glass substrate is provided with a retaining groove for preventing the resin from protruding from the substrate. There is no. Therefore, the resin does not wrap around to the surface opposite to the bonding surface of the substrate, nor adhere to the surfaces of the upper and lower pressing plates.

Further, since the area of the flat portion of the thin glass substrate is smaller than the area of the flat portion of the flat substrate, even if some eccentricity occurs at the time of bonding, the thin substrate extends beyond the flat substrate. I can not do the part that I did. Therefore, there is no chipping or cracking during the handling in the subsequent process.

Further, when the obtained laminated glass substrate is provided with the function of a flat plate type microlens and is used as a counter substrate for a liquid crystal display device or the like, the surface of the lens is clean and there are few peripheral defects. It can be used as a flat plate type microlens array, and the quality of a liquid crystal display device can be improved.

[Brief description of drawings]

FIG. 1 is a schematic view of a step of laminating a flat glass substrate and a thin glass substrate on which a resin spillover preventing groove is formed according to the present invention.

[Explanation of symbols]

 10 Laminated Flat Substrate 11 Flat Substrate 11A Resin Reservoir Groove Formed on Peripheral Substrate 12 Thin Glass 21 (Transparent) Adhesive Resin 31 Lower Pressurizing Plate 32 Upper Pressurizing Plate 41 UV Rays

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenjiro Hamanaka, 3-5-11, Doshumachi, Chuo-ku, Osaka City, Osaka Prefecture Nippon Sheet Glass Co., Ltd. (72) Kenji Morio, 3-chome, Doshomachi, Chuo-ku, Osaka City, Osaka Prefecture 5th-11th Nippon Sheet Glass Co., Ltd.

Claims (5)

[Claims] 1. A method of bonding two flat substrates together, wherein a resin protruding from the substrates is collected in a peripheral portion of a surface serving as an adhesive surface of one or both of the two flat substrates. A groove is provided, an adhesive resin is supplied to at least one surface that is an adhesive surface of the two substrates, the two substrates are arranged so that the resin supply surfaces face each other, and the resin is applied by a pressing means. A method for laminating a flat substrate, which is characterized in that: 2. The method for laminating flat substrates according to claim 1, wherein one of the two flat substrates is a thin substrate, and the size of the substrates is smaller than the size of the other flat substrate, and The groove provided on the other planar substrate is a method for laminating the planar substrate provided near the outer periphery of the laminating position of the substrate. 3. The method of bonding flat substrates according to claim 1, wherein both of the two flat substrates are low expansion glass substrates, and one surface of the low expansion glass substrates on the bonding surface side. Has a fine uneven pattern, the adhesive resin fills the fine uneven pattern,
A method for laminating flat substrates for bonding the two substrates. 4. The method for laminating flat substrates according to claim 3, wherein the low expansion glass substrate is a quartz glass substrate, and one of the glass substrates has a thickness of 0.5 mm or less. How to match. 5. The method for laminating flat substrates according to claim 1, wherein the adhesive resin is a photocurable resin or a thermosetting resin, and the viscosity thereof is 1 to 50 poise. Laminating method.