Patent Application
20110061805
1. Field of the Invention
The present invention relates to an image display apparatus manufacturing method in which bonding of base materials is performed by irradiation of a laser beam.
2. Description of the Related Art
In an image display apparatus of a field emission type, voltage is applied to a high vacuum region formed between a face plate and a rear plate, and electrons emitted from an electron-emitting device region on the rear plate are irradiated to a phosphor region on the face plate to cause phosphors in the phosphor region to emit light, whereby an image is displayed. Here, as a bonding method which can be used when bonding various base materials such as the face plate, the rear plate and the like, there is a method disclosed in Japanese Patent Application Laid-Open No. 2000-106108 or a method disclosed in Japanese Patent Application Laid-Open No. 2008-517446 (Translation of PCT Application).
Japanese Patent Application Laid-Open No. 2000-106108 describes a method of manufacturing a cathode ray tube which includes a face plate having a phosphor layer of drawing an image of the cathode ray tube and a funnel cone portion of acting as an outer container of the cathode ray tube and in which the funnel cone portion and the face plate respectively having different thermal expansion coefficients have been glass-bonded (frit-sealed) to each other. In this method, glass frit to be used in the glass bonding has two or more kinds of different thermal expansion coefficients, and the glass frit is used by laminating components so as to gradually change the thermal expansion coefficient of the glass frit between the thermal expansion coefficient of the face plate and the thermal expansion coefficient of the funnel cone portion.
Japanese Patent Application Laid-Open No. 2008-517446 (Translation of PCT Application) describes a method of bonding two plates to each other as dynamically changing, according to need, movement speed and/or power of a laser beam emitted from a laser to uniformly heat frit along a sealing line having an electrode occupied area and a non-electrode area.
However, when these methods are used when the face plate, the rear plate and the like are bonded, there is a possibility that damages, especially disconnection and/or short circuit of wirings, occur in respective base materials. Further, there is a possibility that sufficient airtightness cannot be obtained. Thus, further improvement is desired.
The present invention aims to provide an image display apparatus manufacturing method which can, in bonding of base materials by irradiation of a laser beam, reduce damages to the base materials due to the laser beam, especially suppress occurrence of disconnection and short circuit in wirings, and achieve reliability and excellent airtightness.
The present invention is directed to an image display apparatus manufacturing method which includes a bonding step of positioning a frame member between a first substrate having numerous electron-emitting devices and a second substrate positioned opposite to the first substrate and having a fluorescent film of displaying an image in response to irradiation of electrons emitted from the electron-emitting devices, and bonding the frame member and the first substrate to each other and the frame member and the second substrate to each other, wherein the image display apparatus manufacturing method is characterized in that: the bonding step further includes arranging an underlying layer on the frame member, arranging, on the underlying layer, a bonding material having a width equal to or smaller than a width of the underlying layer, facing a bonding face of the first substrate or the second substrate and a face of the frame member on which the bonding material has been arranged, to each other, and, after bringing the first substrate or the second substrate opposite to the face of the frame member on which the bonding material has been arranged into contact with the bonding material, bonding the first substrate or the second substrate opposite to the face of the frame member on which the bonding material has been arranged and the frame member to each other, by irradiating a laser beam to the bonding material through at least the underlying layer; the underlying layer includes a material which absorbs the laser beam easily as compared with the bonding material; and the laser beam is irradiated to a range which is equal to or larger than the width of the bonding material and less than the width of the underlying layer.
Further, the present invention is directed to a laser bonding method which comprises: arranging an underlying layer on a base material; arranging, on the underlying layer, a bonding material having a width equal to or smaller than a width of the underlying layer; facing a bonding face of another base material and a face of the base material on which the bonding material has been arranged, to each other; and, after bringing the another base material into contact with the bonding material, bonding the two base materials to each other by irradiating a laser beam to the bonding material through at least the underlying layer, wherein the laser bonding method is characterized in that the underlying layer includes a material which absorbs the laser beam easily as compared with the bonding material, and the laser beam is irradiated to a range which is equal to or larger than the width of the bonding material and less than the width of the underlying layer.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
An image display apparatus manufacturing method is directed to a manufacturing method which includes a bonding step of positioning a frame member between a first substrate having numerous electron-emitting devices and a second substrate positioned opposite to the first substrate and having a fluorescent film of displaying an image in response to irradiation of electrons emitted from the electron-emitting devices, and bonding the frame member and the first substrate to each other and the frame member and the second substrate to each other, wherein the manufacturing method is characterized in that: the bonding step further includes arranging an underlying layer on the frame member, arranging, on the underlying layer, a bonding material having a width equal to or smaller than a width of the underlying layer, facing a bonding face of the first substrate or the second substrate and a face of the frame member on which the bonding material has been arranged, to each other, and, after bringing the first substrate or the second substrate opposite to the face of the frame member on which the bonding material has been arranged into contact with the bonding material, bonding the first substrate or the second substrate opposite to the face of the frame member on which the bonding material has been arranged and the frame member to each other, by irradiating a laser beam to the bonding material through at least the underlying layer; the underlying layer includes a material which absorbs the laser beam easily as compared with the bonding material; and the laser beam is irradiated to a range which is equal to or larger than the width of the bonding material and less than the width of the underlying layer.
According to the present invention, it is possible to provide the image display apparatus manufacturing method, which can reduce damages to the base materials due to the laser beam, especially suppress occurrence of disconnection in the wirings, short circuiting, and break/crack, and achieve reliability and excellent airtightness.
Hereinafter, the embodiment of the present invention will be described. A manufacturing method according to the present invention can be used to manufacture an image display apparatus, in which, for example, a fluorescent film and an electron accelerating electrode are formed on a face plate of a vacuum envelope and an electron source is formed on a rear plate. Further, a laser bonding method according to the present invention can be widely applied to a case of manufacturing an airtight container by bonding plural base materials.
On the glass substrate 21 of the rear plate 22, numerous electron-emitting devices 27 for emitting electrons in response to an image signal are provided, and wirings (X-directional wirings 28 and Y-directional wirings 29) used for operating the respective electron-emitting devices 27 in response to the image signal are formed. On the glass substrate 33 of the face plate 32, fluorescent films 34, which display an image by a process that electrons emitted from the electron-emitting devices 27 are irradiated and the light is emitted, are provided. On the glass substrate 33, black stripes 35 are further provided. The fluorescent films 34 and the black stripes 35 are provided in such a manner that they are alternately arranged. On the fluorescent films 34, metal backs 36 composed of Al thin films are formed. The metal backs 36, which have the function as electrodes of attracting electrons, receive the potential supplied from a high voltage terminal Hv 20 provided at the envelope 10. On each of the metal backs 36, a non-evaporable getter 37 composed of a Ti thin film is formed.
Hereinafter, an example of embodiments of the present invention will be specifically described with reference to
(Process (1): Applying/Drying of Material of Underlying Layer 1)
At first, an underlying layer 1, of which an absorption rate of a laser beam is larger than that of a bonding material 2 to be applied later, is formed into the desired width and thickness by a screen printing method on a one-side surface of the support frame 26 along its peripheral length ((a) in
As to thickness and an absorption rate of the underlying layer 1, these factors are properly designed so as to attenuate to such the laser power of not influencing the wirings (X-directional wirings 28 and Y-directional wirings 29) when the laser beam is irradiated. Note that a dispenser method and an offset printing method other than the screen printing method are also effective as an applying method of the material of the underlying layer 1.
(Process (2): Applying/Drying of Bonding Material 2)
Thereafter, the bonding material 2 is formed into the desired width and thickness by the screen printing method on the underlying layer 1 similar to a case of forming the underlying layer 1 ((c) in
Conditions for bonding the materials of the underlying layer 1 and the bonding material 2, which are applicable to the image display apparatus manufactured by the method according to the present invention are as follows:
(1) heat resistance is given in the in-vacuum baking (high vacuum forming) process;
(2) airtightness is high, and high vacuum (vacuum leakage minimum, gas permeableness minimum) can be maintained (however, only at portions to which maintenance of vacuum is necessary);
(3) adhesiveness to the glass member is high;
(4) a low outgassing (high vacuum maintaining) characteristic is given; and
(5) a less warp of the image display apparatus after the bonding is secured, and safety is high.
As the material of the bonding material 2 of satisfying the above requirements, at least, glass frit obtained by burning out the organic binder or metal such as Al, Ti, Ni or the like or the alloy thereof can be enumerated.
Further, as the material of the underlying layer 1, such the material obtained by containing pigment, dye or the like, which can easily absorb the laser beam, into the glass frit serving as the material of the bonding material and then burning out the organic binder can be used. Alternatively, the metal or the alloy which can more absorb the laser beam than the bonding material 2 can be used.
As the material of the pigment, the dye or the like which can easily absorb the laser beam, for example, manganese oxide, carbon or the like can be enumerated.
As the metal which can be used for the underlying layer 1, In, Sn, Al, Cu, Au, Ag, Ti, Fe, Cr or the like can be enumerated. At least one kind of metal which can easier absorb the laser beam than the metal to be used for the bonding material 2 can be properly selected from among those metals. More specifically, when Al is used for the bonding material 2, Ti, Fe or the like can be used for the underlying layer 1. When Ti is used for the bonding material 2, Cr or the like can be used for the underlying layer 1. When Ni is used for the bonding material 2, Cr or the like can be used for the underlying layer 1.
The glass frit obtained by burning out at least the organic binder is used for the materials of the bonding material 2 and the underlying layer 1, thereby reducing generation of air bubbles from the bonding material 2 and the underlying layer 1 in performing the bonding process, and the excellent airtightness can be obtained. When the metal is used for the materials of the bonding material 2 and the underlying layer 1, since the air bubbles are not generated in performing the bonding process, the excellent airtightness can be similarly obtained.
When the glass frit obtained by containing the pigment, the dye or the like, which can easily absorb the laser beam, into the glass frit of the bonding material 2 and burning out the organic binder is used for the material of the underlying layer 1, the thermal expansion coefficients and the melting temperature of the underlying layer 1 and the bonding material 2 almost become the same level. Consequently, the stress at a bonding section is reduced, and a bonding process more excellent in the airtightness with very little break/crack can be performed.
In the present embodiment, the glass frit of containing the organic binder is used for the materials of the underlying layer 1 and the bonding material, and the material which can easily absorb the laser beam is contained in the underlying layer 1.
(Process (3): Baking of Underlying Layer 1 and Bonding Material 2)
Next, in order to burn out the organic substances contained in the glass frit of the underlying layer 1 and the bonding material 2, the heating and baking processes are performed at 350° C. or more and 600° C. or less ((d) in
(Process (1′): Applying/Drying of Material of Underlying Layer 1′)
An underlying layer 1′, of which an absorption rate of the laser beam is larger than that of a bonding material 2′ to be applied later, is formed into the desired width and thickness by a screen printing method on a surface opposite to the support frame 26 of the face plate 32 along its peripheral length ((A) in
(Process (2′): Applying/Drying of Bonding Material 2′)
Thereafter, the bonding material 2′ is formed into the desired width and thickness by the screen printing method on the underlying layer 1′ similar to a case of forming the underlying layer 1′ ((C) in
(Process (3′): Baking of Underlying Layer 1′ and Bonding Material 2′)
Next, in order to burn out the organic substances contained in the underlying layer 1′ and the bonding material 2′, the heating and baking processes are performed at 350° C. or more and 600° C. or less ((D) in
(Process (4): Alignment of Rear Plate 22 and Support Frame 26)
Next, the support frame 26 and a bonding surface of the rear plate 22 are set to be faced so that a surface, on which the bonding material 2 was formed, on the rear plate 22 contacts with a predetermined position, and the alignment is performed ((e) in
(Process (5): Bonding of Rear Plate 22 and Support Frame 26)
A local heating process is performed by irradiating the laser beam to the bonding material 2 through the underlying layer 1 while applying the pressure from a side of the support frame 26. According to this process, the bonding material 2 is melted and hardened, and the rear plate 22 is bonded with the support frame 26 ((f) in
(Process (6): Arrangement of Spacer 8, Alignment of Face Plate 32 and Support Frame 26)
Next, a spacer 8 is arranged on the wirings (X-directional wirings 28 and Y-directional wirings 29) of the rear plate 22. Thereafter, alignment of the rear plate 22 and the face plate 32 is performed so that the bonding material 2′, which was formed on the face plate 32, contacts with the other surface of the support frame 26, which was bonded with the rear plate 22, at a predetermined position ((g) in
(Process (7): Bonding of Face Plate 32 and Support Frame 26)
A local heating process is performed by irradiating the laser beam to the bonding material 2′ through the underlying layer 1′ while applying the pressure from a side of the face plate 32. According to this process, the bonding material 2′ is melted and hardened, and the face plate 32 is bonded with the support frame 26 ((h) in
Herewith, airtightness is continuously ensured and the damage to the wirings (X-directional wirings 28 and Y-directional wirings 29) of the rear plate 22 is reduced, and a safely and tightly fixed envelope 10, which suppresses the disconnection of wirings or the short-circuiting and has high reliability with very little break/crack, can be obtained.
(Process (8): Vacuum Exhaust/Baking/Sealing of Exhaust Hole 7)
In order to increase the degree of vacuum of an internal space of the envelope 10, a vacuum exhausting process is performed while performing a baking process at a predetermined temperature. More specifically, the envelope is located inside a vacuum chamber (not illustrated), and the degree of vacuum inside the chamber is decreased to a level of 10−3 Pa while vacuum exhausting the inside of the envelope 10 from the exhaust hole 7, and whole of the envelope 10 is heated to make the non-evaporable getter 37 activate. Additionally, the exhaust hole 7 is sealed up by a sealing material 6 and a sealing cover 5 to manufacture the image display apparatus 11. A cross section of the obtained image display apparatus 11 has, for example, such the constitution as illustrated in
In the above-mentioned embodiment, although a method according to the present invention is applied to both the bonding of the rear plate 22 and the support frame 26 and the bonding of the face plate 32 and the support frame 26, a method of the present invention may be applied only to either one. For example, a unit obtained by previously bonding the face plate 32 with the support frame 26 is used, and a method of the present invention may be applied to the bonding of the rear plate 22 and the support frame 26. In this case, a cross section of the image display apparatus to be obtained has, for example, such the constitution as illustrated in
Hereinafter, the present invention will be described in detail by quoting concrete examples.
An image display apparatus according to the present example has the same constitution as that of the image display apparatus 11 which is schematically illustrated in
As to the rear plate 22 of the image display apparatus 11 according to the present example, plural (240 rows×720 columns) surface conduction electron-emitting devices 27 are electrically connected to the X-directional wirings 28 and the Y-directional wirings 29 on the glass substrate 21 to be wired into a passive matrix form. As to the face plate 32, the fluorescent films 34 composed of stripe-like phosphors (R, B and B) (not illustrated) and the black stripes 35 are alternately laid out on the glass substrate 33. After forming the metal back 36 composed of an Al thin film to have thickness of 0.1 μm by a sputtering method on the fluorescent film 34, a Ti film was formed to have thickness of 0.1 μm by an electron beam vacuum vapor deposition method as the non-evaporable getter 37.
Hereinafter, the image display apparatus manufacturing method according to this example will be described by referring to the attached drawings.
(Process (1))
The 3.0 WT % pigment consisted of manganese oxide was blended in terpineol, “Elvacite 2043™” (available from DuPont) and Bi-based lead-free glass frit of BAS115 base (available from ASAHI GLASS CO., LTD.: the thermal expansion coefficient α=79×10−7/° C.) serving as the base material of the underlying layer 1, whereby the paste was confected. After this paste was formed to have width of 2 mm and thickness of 10 μm along the peripheral length on the support frame 26 by the screen printing method, the drying process was performed at 120° C., and the underlying layer 1 was formed ((b) in
(Process (2))
Next, the paste obtained by the procedure that the 0.5 WT % pigment consisted of manganese oxide was blended in terpineol, “Elvacite 2043™” and Bi-based lead-free glass frit of BAS115 base (available from ASAHI GLASS CO., LTD.: the thermal expansion coefficient α=79×10−7/° C.) serving as the base material of the bonding material 2, was confected. As to this paste, since the blended amount of the manganese oxide serving as the pigment is less than that in the paste used as the material of the underlying layer 1, the laser beam is not easily absorbed. This paste was applied on the dried underlying layer 1 to have width of 1 mm and thickness of 10 μm by the screen printing method similar to a case of the process (1), and the bonding material 2 was formed ((c) in
(Process (3))
Then, the heating and baking processes were performed at 480° C. in order to burn out the organic substances in the underlying layer 1 and the bonding material 2 ((d) in
(Process (1′))
The paste obtained by the procedure that the 3.0 WT % pigment consisted of manganese oxide was blended in terpineol, “Elvacite 2043™” and Bi-based lead-free glass frit of BAS115 base (available from ASAHI GLASS CO., LTD.: the thermal expansion coefficient α=79×10−7/° C.) serving as the base material of the underlying layer 1′, was confected. After this paste was formed to have width of 2 mm and thickness of 10 μm along the surface on the face plate 32 opposite to the support frame 26 by the screen printing method, the drying process was performed at 120° C., whereby the underlying layer 1′ was formed ((B) in
(Process (2′))
Next, the paste obtained by the procedure that the 0.5 WT % pigment consisted of manganese oxide was blended in terpineol, “Elvacite 2043™” and Bi-based lead-free glass frit of BAS115 base (available from ASAHI GLASS CO., LTD.: the thermal expansion coefficient α=79×10−7/° C.) serving as the base material of the bonding material 2′, was confected. This paste was formed to have width of 1 mm and thickness of 10 μm on the dried underlying layer 1′ by the screen printing method similar to the case of the process (1′). According to this procedure, the bonding material 2′ was formed ((C) in
(Process (3′))
Then, the heating and baking processes were performed at 480° C. in order to burn out the organic substances in the underlying layer 1′ and the bonding material 2′ ((D) in
(Process (4))
The alignment of the support frame 26 and the rear plate 22 was performed to bring the bonding material 2 into contact with the rear plate 22 having the exhaust hole 7 at a predetermined position ((e) in
(Process (5))
Then the local heating process was performed to the bonding material 2 by irradiating the semiconductor laser beam, of which the wavelength is 980 nm, the output power is 130 W and the effective diameter (irradiation diameter) is 1 mm, through the underlying layer 1 while scanning the semiconductor laser at a speed of 300 mm/S, while applying the pressure from the side of the support frame 26. At this time, the semiconductor laser beam was irradiated to a range equal to or larger than the width of the bonding material 2 and less than the width of the underlying layer 1. According to this process, the bonding material 2 was melted and hardened, and the rear plate 22 was bonded with the support frame 26 ((f) in
(Process (6))
Next, a spacer 8 was arranged on the X-directional wirings 28 and the Y-directional wirings 29 of the rear plate 22 by a conventional method. In addition, the rear plate 22 and the face plate 32 was located after performing the alignment in such a way that the bonding material 2′ formed on the face plate 32 was made to be contacted with the other surface of the support frame 26 bonded with the rear plate 22 ((g) in
(Process (7))
Then a local heating process was performed to the bonding material 2′ by irradiating the semiconductor laser beam, of which the wavelength is 980 nm, the output power is 130 W and the effective diameter (irradiation diameter) is 1 mm, through the underlying layer 1′ while scanning the semiconductor laser at a speed of 300 mm/S, while applying the pressure from the side of the face plate 32. The semiconductor laser beam was irradiated to a range equal to or larger than the width of the bonding material 2′ and less than the width of the underlying layer 1′. According to this process, the bonding material 2′ was melted and hardened, and the face plate 32 was bonded with the support frame 26 ((h) in
(Process (8))
Next, the envelope 10 was located inside a vacuum chamber (not illustrated), and the whole of the envelope 10 was heated up to 350° C. with a state that the degree of vacuum inside the chamber was set at a level of 10−3 Pa, while vacuum exhausting the inside of the envelope 10 from the exhaust hole 7, and the non-evaporable getter 37 was activated. Thereafter, the exhaust hole 7 was sealed up by the sealing material 6 consisted of In (Indium) and the sealing cover 5 consisted of a glass substrate, and the image display apparatus 11 was manufactured ((i) in
In the present invention, the underlying layer 1(1′) was composed of the material more easily absorbs the laser beam than that of the bonding material 2(2′). In addition, in the processes (1) and (2) (processes (1′) and (2′)), it is arranged in such a way that the width of the underlying layer 1(1′) becomes larger than that of the bonding material 2(2′). Additionally, the semiconductor laser beam was irradiated to a range equal to or larger than the width of the bonding material 2(2′) and less than the width of the underlying layer 1(1′) through the underlying layer 1(1′). Herewith, the power of laser beam to be irradiated was absorbed in the underlying layer 1(1′), and the damage to the wirings (X-directional wirings 28 and Y-directional wirings 29) of the rear plate 22 could be reduced. According to the above constitution, the image display apparatus, which suppressed the disconnection of wirings or generation of the short-circuiting, having the high reliability, and excellent in the airtightness with very little break/crack to be safely and tightly fixed, could be obtained.
In this example, the image display apparatus was manufactured by the same method as that in the example 1 except that the support frame 26 and the face plate 32 in the example 1 were previously bonded with by the glass frit, which was in a low level of absorbability of the laser beam, and the processes (1′) to (3′) were omitted. The cross section diagram of the bonding section is illustrated in
In this example, as the underlying layer 1(1′), a layer obtained by depositing Ti, of which thickness is 10 nm and width is 2 mm, by a sputtering method was used in the processes (1) and (1′). In the processes (2) and (2′), as the bonding material 2(2′), a sheet of aluminum foil, of which thickness is 10 μm and width is 1 mm, was used. And, the image display apparatus was manufactured by the same method as that in the example 1 except that the thermal baking process in the processes (3) and (3′) was omitted.
In this example, since metals were respectively used for the underlying layer 1(1′) and the bonding material 2(2′), the gas, which was emitted when the whole of the envelope 10 was heated up to 350° C. while performing the vacuum exhausting process in the process (8) and the non-evaporable getter 37 was activated, was more reduced, and the image display apparatus excellent in airtightness could be obtained.
In the examples 1 to 3, it was described by use of examples that the non-evaporable getter 37 was located on the face plate 32. However, this getter 37 may be arranged on the wirings of the rear plate 22.
While the present invention has been described with reference to the exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2009-211712, filed on Sep. 14, 2009, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-211712 | Sep 2009 | JP | national |
