JP2009057256A - Method for joining glass substrate, and display device using glass substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joining method where glass materials can be joined each other without using metallic materials with remarkably different thermal expansion coefficients, and to provide a production device therefor. <P>SOLUTION: Regarding the joining method for directly joining glass materials each other, heating is performed in a vacuum atmosphere in such a manner that a temperature distribution is imparted to the joint. In this way, voids (bubbles) having possibility of being generated at the inside is driven out to the outside of the joint, and the satisfactory joint can be formed. Further, there is no need of excessive pressurization in this invention, residual strain stress after the joining can be suppressed to a low degree. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a glass substrate bonding method including a substrate disposed opposite to each other and a plurality of display elements provided between the substrates, and a display device using the glass substrate.

In recent years, as a next-generation lightweight and thin flat display device, a display device in which a large number of electron-emitting devices are arranged and opposed to a phosphor screen has been developed. As the electron-emitting device, a field emission type device or a surface conduction type device is assumed. Usually, a display device using a field emission type electron-emitting device as an electron-emitting device is a field emission display (hereinafter referred to as FED), and a display device using a surface conduction type electron-emitting device as an electron-emitting device is a surface device. It is called a conduction electron emission display (hereinafter referred to as SED).
The FED has a front substrate and a rear substrate that are arranged to face each other with a predetermined gap, and these substrates are connected to each other through a rectangular frame-shaped side wall to form a vacuum envelope. It is composed. A phosphor screen is formed on the inner surface of the front substrate, and a large number of electron-emitting devices are provided on the inner surface of the rear substrate as electron emission sources that excite the phosphor to emit light. Further, in order to support an atmospheric pressure load applied to the back substrate and the front substrate, a plurality of support members are disposed between these substrates.

  The potential on the back substrate side is approximately 0 V, and the anode voltage Va is applied to the phosphor screen. The red, green, and blue phosphors that make up the phosphor screen are irradiated with the electron beams emitted from the electron-emitting devices, and the phosphors emit light to display an image. Further, since a high voltage is applied to the phosphor screen, high strain point glass is used for the front substrate, the rear substrate, the side walls, and the plate glass for the support member. In such an FED, the gap between the front substrate and the rear substrate can be set to several millimeters or less, which is lighter than a cathode ray tube (CRT) currently used as a display of a television or a computer. Thinning can be achieved.

Here, the method of Patent Document 1 is known as a method of joining the front substrate and the rear substrate. According to this description, the bonding surface between the front substrate and the rear substrate is polished, then cleaned, and the bonding surface is attached with water. As a result, the front substrate and the rear substrate are finally bonded.
Japanese Patent Laid-Open No. 06-298539

  In the conventional method of bonding substrates, the glass substrate is bonded with water and then brought into close contact by putting it into an electric furnace and overheating for a certain period of time. Remains, and it is difficult to obtain a good bonding state.

  The present invention has been made in view of the above problems, and a glass substrate bonding method capable of reducing residual bubbles on a bonding surface of a substrate and obtaining a good bonding state, and a display device using the glass substrate. It is an issue to provide.

In order to achieve the above object, a glass substrate bonding method of the present invention includes a first step in which both bonding surfaces of a first glass substrate and a second glass substrate are arranged to face each other in a reduced pressure atmosphere, A second step of disposing a joining member between the joining surfaces; and sequentially joining the joining member from a portion where the temperature of the joining member is high to a portion where the temperature is low with a temperature gradient inside the joining member. And a third step of bonding to the glass substrate and the second glass substrate. The reduced-pressure atmosphere is preferably 0.1 Pa or less as well as vacuum, and particularly in the vicinity of 1 × 10 ⁻⁴ Pa is preferable for a display device.

  In addition, in claim 1, the temperature of the high temperature portion of the bonding member is preferably 350 ° C. or higher and 400 ° C. or lower and lower than the glass transition point of the first glass substrate or the second glass substrate. .

  Furthermore, in Claim 1, before the said 3rd process, heating the 1st glass substrate, the 2nd glass substrate, and the said whole joining member at the temperature of 250 degreeC or more and 350 degrees C or less as auxiliary heating. desirable.

  Furthermore, in claim 1, the temperature gradient is desirably 2 ° C./mm or more and 15 ° C./mm or less.

The display device using the glass substrate of the present invention is a first glass substrate, a plurality of display elements formed on the first glass substrate and arranged in a matrix, and opposed to the first glass substrate. In the image display device comprising the second glass substrate disposed and the alignment member bonded to both the first glass substrate and the second glass substrate, the first or second glass substrate and the alignment member Are present in the range of 1 / cm ^{2 to} 10 / cm ² .

  In the present invention, the temperature gradient inside the bonding member bonded between the first glass substrate and the second glass substrate is changed, and the higher temperature portion is expanded more than the lower portion. Since the joining is sequentially performed by bringing the expanded portion into contact with the glass substrate, the joining can be performed while air bubbles are released. Therefore, since it is possible to suppress the generation of more bubbles than necessary on the joint surface, it is possible to control to leave only a predetermined amount of bubbles as necessary. The remaining bubbles have a characteristic function. That is, since the bubbles obstruct the progress of the cracks caused by the thermal stress, the cracks can be prevented from becoming longer or generated.

  ADVANTAGE OF THE INVENTION According to this invention, the joining method of the glass substrate which can suppress generation | occurrence | production of the bubble by the joining surface of the joining member joined between the 1st glass substrate and the 2nd glass substrate, and can obtain a favorable joining state. And a display device using a glass substrate can be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
First, FED will be described as an example of an image display device manufactured by the manufacturing method according to the present embodiment. This FED is shown in FIGS. FIG. 1 is a perspective view showing the entire display device, FIG. 2 is a view showing the inside with a glass substrate partially peeled off, FIG. 3 is a cross-sectional view, and FIG. 4 is a view showing an internal FED structure. This FED includes a front substrate 11 as a first substrate and a rear substrate 12 as a second substrate each made of rectangular glass as an insulating substrate, and these substrates face each other with a gap of about 1.5 to 3.0 mm. Has been placed. The front substrate 11 and the rear substrate 12 have a flat rectangular vacuum envelope 10 whose peripheral portions are sealed with each other via a rectangular frame-shaped side wall 13 as a joining member and the inside is maintained in a reduced pressure atmosphere. It is composed.

  The peripheral portions of the front substrate 11 and the rear substrate 12 are coupled to each other by a joint 40. That is, the side wall 13 functioning as a frame is disposed between the bonding surface located at the inner peripheral edge of the front substrate 11 and the sealing surface located at the inner peripheral edge of the rear substrate 12.

  A plurality of support members 14 are provided in the decompression envelope 10 in order to support an atmospheric pressure load applied to the back substrate 12 and the front substrate 11. These support members 14 extend in a direction parallel to the long side of the vacuum envelope 10 and are arranged at a predetermined interval along a direction parallel to the short side. The shape of the support member 14 is not particularly limited to this, and a columnar support member may be used.

  As shown in FIG. 4, a phosphor screen 16 is formed on the inner surface of the front substrate 11. The phosphor screen 16 is formed of phosphor layers R, G, and B that are issued in three colors of red, green, and blue, and a black absorbing portion 17 on the matrix. The above-mentioned support part 14 is placed so as to be hidden by the shadow of the black light absorbing part. On the phosphor screen 16, an aluminum layer (not shown) is deposited as a metal back.

  As shown in FIG. 3, on the inner surface of the back substrate 12, a number of field emission type electron-emitting devices 22 each emitting an electron beam are provided as electron emission sources for exciting the phosphor layers R, G, and B. Is provided. These electron-emitting devices 22 are arranged in a matrix in a plurality of columns and a plurality of rows corresponding to each pixel, and function as display devices.

  More specifically, a conductive cathode layer 24 is formed on the inner surface of the back substrate 12, and a silicon dioxide film 26 having a large number of cavities 25 is formed on the conductive cathode layer. A gate electrode 28 made of molybdenum, niobium or the like is formed on the silicon dioxide film 26. A cone-shaped electron-emitting device 22 made of molybdenum or the like is provided in each cavity 25 on the inner surface of the back substrate 12.

  A matrix-like wiring 21 to which the electron-emitting devices 22 are connected is formed on the back substrate 12, and an end portion thereof is drawn out to the peripheral edge of the back substrate. In the peripheral edge portion of the back substrate 12, an insulating layer 23 is formed on the wiring 21, and the side wall 13 is provided on this insulating layer.

  In the FED configured as described above, a video signal is input to the electron-emitting device 22 and the gate electrode 28 formed in a simple matrix system. When the electron-emitting device 22 is used as a reference, a gate voltage of +100 V is applied when the luminance is highest. Further, +10 kV is applied to the phosphor screen 16. The magnitude of the electron beam emitted from the electron-emitting device 22 is modulated by the voltage of the gate electrode 28, and this electron beam excites the phosphor layer of the phosphor screen 16 to emit light, thereby displaying an image. .

  Thus, since a high voltage is applied to the phosphor screen 16, a high strain point glass is used as the plate glass for the front substrate 11, the back substrate 12, the side wall 13, and the support member 14.

  Next, a method for manufacturing the FED configured as described above will be described in detail.

  First, as shown in FIG. 4, the phosphor screen 16 is formed on the plate glass to be the front substrate 11. In this method, a plate glass having the same size as the front substrate 11 is prepared, and a phosphor layer stripe pattern is formed on the plate glass by a plotter machine. The plate glass on which the phosphor stripe pattern is formed and the plate glass for the front substrate are placed on a positioning jig and set on an exposure table, whereby the phosphor screen 16 is generated by exposure and development.

  Subsequently, the wiring 21 shown in FIG. 1 is formed on the plate glass for the back substrate 12. This is because, for example, a plurality of wirings 21 extending in the X direction by Ag paste or the like are formed in the effective display area and the peripheral portion of the plate glass, and a plurality of wirings 21 extending in the Y direction are respectively formed in the peripheral portion of the plate glass. Only to form. Thereafter, an insulating layer (not shown) is formed on the entire surface of the plate glass so as to overlap the wiring 21. Next, in the effective display area, the remaining wiring 21 extending in the Y direction is formed on the insulating layer, and connected to the wiring previously formed only on the peripheral edge of the plate glass.

  Subsequently, the electron-emitting device 22 is formed on the glass plate for the rear substrate. In this case, a matrix-like conductive cathode layer is formed on the plate glass and connected to the wiring previously formed only on the peripheral edge of the plate glass.

  Subsequently, the electron-emitting device 22 is formed on the glass plate for the rear substrate. In this case, a matrix-like conductive cathode layer is formed on the plate glass, and an insulating film of a silicon dioxide film is formed on the conductive cathode layer by, for example, a thermal oxidation method, a CVD method, or a sputtering method.

Thereafter, a metal film for forming a gate electrode such as molybdenum or niobium is formed on the insulating film by, for example, sputtering or electron beam evaporation. Next, a resist pattern having a shape corresponding to the gate electrode to be formed is formed on the metal film by lithography. Using this resist pattern as a mask, the metal film is etched by wet etching or dry etching to form the gate electrode 28.
Next, the cavity 25 is formed by etching the insulating film by wet etching or dry etching using the resist pattern and the gate electrode as a mask. Then, after removing the resist pattern, a peeling layer made of, for example, aluminum or nickel is formed on the gate electrode 28 by performing electron beam evaporation from a direction inclined by a predetermined angle with respect to the surface of the back substrate 12.

Thereafter, for example, molybdenum is vapor-deposited as a cathode forming material by an electron beam vapor deposition method from a direction perpendicular to the surface of the back substrate 12. Thereby, the electron-emitting device 22 is formed inside each cavity 25. Subsequently, the release layer is removed together with the metal film formed thereon by a lift-off method. In the atmosphere, the plurality of support members 14 are sealed on the back substrate 12 by the low melting point glass 30, and the back substrate 12 and the front substrate 11 are sealed to each other through the side wall 13.
FIG. 5 is a diagram for explaining in detail a bonding method between glass substrates. For the side wall 13, for example, 8.4 × 10 ⁻⁶ / ° C. having a thermal expansion coefficient within ± 1.0 × 10 ⁻⁶ / ° C. is used. First, the side wall 13 is cut out from a glass plate made of the same material as the back and front glass.

Next, in the case where the surface of the side wall 13 and the glass substrate (11, 12) are bonded in a normal state in which a vacuum is applied up to, for example, 1 × 10 ⁻⁴ Pa in the vacuum, this bonding technique is used, as shown in FIG. Thus, the surface of the side wall 13 and the surfaces of the substrates 11 and 12 are arranged to face each other under a reduced pressure atmosphere. Thereafter, bonding is performed.

  FIG. 14 shows the temperature distribution inside the side wall 13 in the state shown in FIG. 5 before joining. 141 is the temperature of the surface on the element side of the side wall (300 ° C.), 142 is the temperature on the outer surface in the opposite direction to the element side (400 ° C.), and the temperature changes with a gentle curve as shown in 144 is doing. Reference numeral 143 denotes an average temperature gradient inside the side wall 13, which is 5 ° C./mm.

With respect to the display device formed through the above steps, the amount and size of bubbles are measured on the bonding surface between the side wall 13 and the glass substrates 11 and 12 using an ultrasonic microscope. As a result, it was found that bubbles having a diameter of 100 μm or less existed at an average diameter size of 50 μm at 5 / cm ² or less. The bubbles, 400 ° C. The bonding temperature from 350 ° C., if a temperature gradient from 2 ° C. / mm of 15 ° C. / mm, it was found that present in the range of 1 / cm ² or more to 10 / cm ^2. Thereby, if it is the above condition range, since this bubble will obstruct the progress of a crack from the crack which generate | occur | produced by the thermal stress, the enlargement or generation | occurrence | production of a crack can be prevented.

Furthermore, the heating method of a glass substrate is demonstrated using FIGS. FIG. 9 shows a state in which the joined body of two glass substrates shown in FIG. 5 is heat-treated. The heater is composed of a main member 120 and sub members 130 ₁ and 130 ₂ . Further, in FIG. 10, the sub member 130 ₃ has the same shape as the sub member 130 ₂ . Similarly, in FIG. 11, a heat insulating member 150 is formed adjacent to the sub member 130 ₃ . FIG. 12 shows the simplest heater structure, and the heater is composed of only the main member heaters 120. The temperature (400 ° C.) in the region indicated by the main and sub members of each heater is lower than the other regions. Further, the other area surrounded by the square on the paper is the atmosphere and is set to about 300 ° C.

(Embodiment 2)
In the following embodiment, only parts different from the first embodiment will be described. As shown in FIG. 6, a composite of a metal material and a glass material was used instead of the side wall 13 made of the glass material of the first embodiment. 6, 63 ₁ of a metal material, wherein the Fe-Ni alloy, 63 ₂ glass material, here a glass coating. The thermal expansion coefficients of 63 ₁ and 63 ₂ are both within ± 1.0 × 10 ⁻⁶ / ° C. of the thermal expansion coefficient of the glass substrate, for example, 8.4 × 10 ⁻⁶ / ° C. Also in the case of the above embodiment, the same effect as the case of Embodiment 1 can be expected. Furthermore a metal material 63 _1, since it is possible to stress relaxation can be prevented more lengthening of cracks.

(Embodiment 3)
The difference from the first embodiment is that, as shown in FIG. 7, the side wall 13 and the glass substrate 11 are bonded to each other through the frit glass 73 in the atmosphere. The state before joining of the frit glass is fine particles having an average particle diameter of 5 to 20 μm and a maximum particle diameter of 500 μm. It is dispersed in a solvent containing cellulose nitrate, IPA, water or the like to form a paste. The coefficient of thermal expansion of the frit glass is within 1.0 × 10 ⁻⁶ / ° C. with respect to the glass substrate, and the softening point can be set to 300 to 350 ° C.

  The same effect as in the first embodiment can be expected, and a predetermined amount of bubbles is formed in the frit glass in the step of bonding the substrate 11 and the frit glass 73, and then the side wall 13 and the glass substrate 12 are formed. It is possible to reliably control to the predetermined range of the size and amount of the bubbles described above by dividing the process into two joining processes.

(Embodiment 4)
Characterized in that the difference from the third embodiment, as shown in Figure 8, which via a frit glass 73, and a metal material 63 ₁ and the glass substrate 11 provided with the glass material 63 ₂ are joined in the atmosphere And

The same effect as in the third embodiment can be expected. Furthermore a metal material 63 _1, since it is possible to stress relaxation can be prevented more lengthening of cracks.

3 is a perspective view illustrating a display device according to Embodiment 1. FIG. FIG. 3 is a perspective view illustrating part of the display device according to the first embodiment. FIG. 3 is a cross-sectional view showing the display device according to the first embodiment. FIG. 6 illustrates a part of the display device according to Embodiment 1; FIG. 6 illustrates a part of the display device according to Embodiment 1; FIG. 6 illustrates a part of a display device according to Embodiment 2; FIG. 6 illustrates a part of a display device according to Embodiment 3; FIG. 6 illustrates a part of a display device according to Embodiment 4; FIG. 6 illustrates a method for manufacturing the display device according to the first embodiment. FIG. 6 illustrates a method for manufacturing the display device according to the first embodiment. FIG. 6 illustrates a method for manufacturing the display device according to the first embodiment. FIG. 6 illustrates a method for manufacturing the display device according to the first embodiment. FIG. 6 illustrates a method for manufacturing the display device according to the first embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Vacuum envelope 11 Front substrate 12 Back substrate 13 Side wall 16 Phosphor screen 17 Black absorption part

Claims (6)

  A first step in which the bonding surfaces of both the first glass substrate and the second glass substrate are arranged to face each other in a reduced pressure atmosphere; a second step of arranging a bonding member between the two bonding surfaces; A third step of sequentially joining the joining member to the first glass substrate and the second glass substrate from a high temperature portion to a low temperature portion of the joining member with a temperature gradient inside the joining member. A method for joining glass substrates, comprising:   2. The temperature of the high temperature portion of the joining member is 350 ° C. or more and 400 ° C. or less and lower than a glass transition point of the first glass substrate or the second glass substrate. Glass substrate bonding method.   2. The first glass substrate, the second glass substrate, and the whole bonding member are heated at a temperature of 250 ° C. or higher and 350 ° C. or lower as auxiliary heating before the third step. The glass substrate bonding method according to the description.   The said temperature gradient is 2 degreeC / mm or more and 15 degrees C / mm or less, The joining method of the glass substrate of Claim 1 characterized by the above-mentioned. A first glass substrate; a plurality of display elements formed on the first glass substrate and arranged in a matrix; a second glass substrate disposed opposite to the first glass substrate; and the first glass substrate. And the alignment member bonded to both of the second glass substrate, one bubble having a diameter of 100 μm or less is formed on the bonding surface between the first or second glass substrate and the alignment member. / display device using a glass substrate which is characterized by the presence in cm ² or more to 10 / cm ² range. 2. The glass substrate according to claim 1, wherein a difference in coefficient of thermal expansion among the first glass substrate, the second glass substrate, and the alignment member is within ± 1.0 × 10 ⁻⁶ / K. Display device used.

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