JP2007250459A - Electroluminescent display and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the rupture of a sealing resin, when bonding a support substrate and a sealing substrate in an electroluminescent (EL) display. <P>SOLUTION: The support substrate 100 in which an EL element 101 is arranged, and the sealing substrate 200 in which a recess (pocket section 201) is formed are bonded via the sealing resin 150. A desiccating agent layer 210 is formed at the bottom of the pocket section 201 so that it opposes the EL element 101. When the volume of the pocket section 201 is set to V1 (=L1×L2×H1) and that of the desiccating agent 210 is set to V2 (=M1×M2×H2), the pocket section 201 and the desiccating agent layer 210 are formed so that a relationship of 0<V2/V1≤0.8 is established. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electroluminescence display device and a manufacturing method thereof, and more particularly to a sealing structure of an electroluminescence display device and a manufacturing method thereof.

  In recent years, an EL display device using an electroluminescence (hereinafter referred to as “EL”) element has attracted attention as a display device that replaces a CRT or LCD.

  Since this EL element is sensitive to moisture, an EL display device has a structure in which a lid is covered with a metal cap or a glass cap coated with a desiccant. FIG. 8 is a cross-sectional view showing the structure of such a conventional EL display device.

  As shown in FIG. 8, the support substrate 70 has a display area in which a number of EL elements 71 are formed on the surface thereof. The support substrate 70 is bonded to a cap sealing substrate 80 via a seal resin 75 (adhesive) made of epoxy resin or the like. In the sealing substrate 80, a recess 81 (hereinafter referred to as a pocket portion 81) is formed by etching in a region corresponding to the display region, and moisture such as moisture is absorbed on the inner surface of the pocket portion 81. The desiccant layer 82 is applied. Here, the reason why the pocket portion 81 is provided is that the space between the desiccant layer 82 and the EL element 71 is secured, and the desiccant layer 82 contacts the EL element 71 and damages the EL element 71. It is for preventing.

Next, with reference to FIG. 9, the process of bonding the support substrate 70 and the sealing substrate 80 is demonstrated. FIG. 9 is a cross-sectional view immediately before the support substrate 70 and the sealing substrate 80 are bonded together, and FIG. 8 is a subsequent cross-sectional view. As shown in FIG. 9, when the support substrate 70 and the sealing substrate 80 are bonded together, first, a predetermined amount of the sealing resin 75 is provided along the contact surface on the sealing substrate 80 side (or the support substrate 70 side) ( For example, the height is about 50 μm). Next, the support substrate 70 and the sealing substrate 80 are bonded together by pressing pressure, and then the sealing resin 75 is heat-cured to complete the EL display device as shown in FIG. By this bonding, the sealing resin 75 is compressed and finally has a height of about 10 μm.
JP 2003-317936 A

  As described above, when the support substrate 70 and the sealing substrate 80 are attached to each other, the height of the sealing resin 75 is necessarily reduced, so that a space formed between the support substrate 70 and the sealing substrate 80 (hereinafter referred to as “the sealing resin 80”). , Referred to as internal space). Along with this, the pressure in the internal space changes (rises). Accordingly, there has been a problem that a part of the sealing resin 75 is ruptured by the rising pressure during the bonding process. Then, there is a problem that moisture permeates into the internal space excessively from the ruptured portion and the operating characteristics of the EL display device deteriorate.

  The present invention has been made in view of the above-mentioned problems, and provides an EL display device sealing structure that mainly prevents the sealing resin from being ruptured. The main features are as follows. That is, the EL display device according to the present invention includes a support substrate having an electroluminescence element on a surface thereof, a recess formed on a surface facing the electroluminescence element, and bonded to the support substrate via an adhesive. When a stop substrate and a desiccant layer formed on the inner surface of the recess are provided, the volume of the recess is V1, and the volume of the desiccant layer is V2, 0 <V2 / V1 ≦ 0.8 The relationship is established.

  In the EL display device according to the present invention, the desiccant is formed inside the electroluminescent element, and a horizontal distance between an end of the electroluminescent element and an end of the desiccant layer is 3 cm or less. It is characterized by.

  Further, the desiccant layer is formed by being divided into a matrix. Furthermore, the desiccant layer is made of a sheet-like desiccant. Furthermore, the change from the pressure in the space between the support substrate and the sealing substrate before bonding through the adhesive to the pressure in the space after bonding through the adhesive is 1. 0.0 times or more and less than 2.0 times.

In addition, a method for manufacturing an EL display device according to the present invention includes preparing a support substrate having an electroluminescence element on the surface and a sealing substrate having a recess formed on the surface, and a desiccant layer on the inner surface of the recess. And the step of bonding the support substrate and the sealing substrate with an adhesive so that the electroluminescent element and the recess face each other, and the volume of the recess is V1. The desiccant is formed so that the relationship of 0 <V2 / V1 ≦ 0.8 is satisfied when the volume of the desiccant layer is V2, and the inside of the electroluminescent device is characterized in that The desiccant is formed, and the electroluminescent element and the horizontal distance between the end of the electroluminescent element and the end of the desiccant layer are 3 cm or less. A desiccant layer is formed.

  Furthermore, the desiccant layer is formed by being divided into a matrix. The desiccant layer is made of a sheet-like desiccant.

  Further, the step of forming a desiccant layer in the recess includes adsorbing and fixing the surfaces of a plurality of sheet-like desiccants having an adhesive applied to the back surface with a head, and then pressing the head and pressing the recess and the It consists of the process of bonding together the back surface of a sheet type desiccant.

  Further, the step of bonding the support substrate and the sealing substrate through an adhesive includes the space after bonding from the pressure of the space between the support substrate and the sealing substrate before bonding. It is characterized in that it is performed so that the change to the pressure becomes 1.0 times or more and less than 2.0 times.

  According to the present invention, the pressure change in the internal space generated when the supporting substrate on which the EL element is formed and the sealing substrate for sealing the EL element can be suppressed can be kept low. The problem of rupture can be solved.

  Further, when the distance between the end portion of the EL element and the end portion of the desiccant is set to a certain value or less, it is possible to provide an EL display device having a high moisture resistance effect while preventing the sealing resin from bursting.

  Furthermore, when the desiccant layer is divided and formed in a matrix, the entrainment of gas on the bonding surface of each desiccant layer is reduced, so that the occurrence of defects in the desiccant layer can be prevented. In addition, the workability of the step of arranging the desiccant is improved, and the manufacturing cost can be kept low.

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

  FIG. 1 is a plan view showing an EL display device according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line A-A ′ in FIG. 1.

  A support substrate 100 made of glass or the like has a display region in which a large number of EL elements 101 are formed on the main surface. The thickness of the support substrate 100 is about 0.7 mm, for example. In the display area, a plurality of pixels are arranged in a matrix, and an EL element 101 is arranged for each pixel. The detailed structure of the EL element will be described later.

  The sealing substrate 200 made of glass or the like is a substrate for covering the support substrate 100 and has a thickness of about 0.7 mm, for example. In the sealing substrate 200, a recess 201 (hereinafter referred to as a pocket portion 201) is formed in advance in an area facing the display area by etching or the like. The depth (height) H1 of the pocket part 201 is, for example, about 0.3 mm. Here, when the horizontal length of the pocket portion 210 is L1 and the vertical length is L2, the volume of the pocket portion 201 is Vp (= L1 × L2 × H1).

  A desiccant layer 210 for absorbing moisture such as moisture is formed on the bottom of the pocket portion 201 so as to face the EL element 101. The desiccant layer 210 is cured by, for example, powdered calcium oxide, barium oxide, or the like, and a resin dissolved in a solvent as an adhesive, applied to the bottom of the pocket portion 201, and further subjected to UV irradiation or heat treatment. I'm allowed.

  In order to increase the surface area, the desiccant layer 210 can be applied, for example, in a spiral shape. The shape of the desiccant layer 210 is arbitrary, but in this embodiment, as an example, the plane is formed in a square shape. For example, if the height H1 of the pocket part 201 is about 0.3 mm, the height H2 of the desiccant layer 210 is about 0.2 to 0.25 mm. When the horizontal length of the desiccant layer 210 is M1 and the vertical length is M2, the volume of the desiccant layer 210 is Vd (= M1 × M2 × H2). Note that the desiccant layer 210 is formed on the bottom of the pocket portion 201 because a wide interval between the desiccant layer 210 and the EL element 101 is secured, and the desiccant layer 210 contacts the EL element 101 to form the EL element 101. This is to prevent damage.

Further, a sealing resin 150 made of an epoxy resin or the like is applied as an adhesive to the contact surface between the support substrate 100 and the sealing substrate 200. Note that when the support substrate 100 and the sealing substrate 200 are bonded to each other, the internal space between the support substrate 100 and the sealing substrate 200 is bonded to each other in a chamber having an inert gas atmosphere such as N ₂ gas. Is filled with an inert gas.

  As described above, the EL element 101 formed on the support substrate 100 is protected from external moisture by the sealing substrate 200.

  In the present embodiment, the pocket portion 201 and the desiccant layer 210 are disposed so as to maintain a relationship of 0 <Vd / Vp ≦ 0.8 between the volume Vp of the pocket portion 201 and the volume Vd of the desiccant layer 210. is doing. Thereby, the volume change ratio with respect to the entire internal space when the support substrate 100 and the sealing substrate 200 are bonded together can be reduced. The small volume change rate also means that the pressure change rate in the internal space is small.

  Specifically, for example, if Vd / Vp = 0.9 in the past, the seal resin is 50 μm in height when applied, and 10 μm in height due to the pressing force when the support substrate and the sealing substrate are bonded together. The pressure in the internal space that was initially about 0.7 atm is nearly doubled (about 1.4 atm) at the time of bonding. On the other hand, if, for example, Vd / Vp = 0.8 as in this embodiment and the change in the height of the sealing resin is the same as described above, the pressure in the internal space is initially about 0.7 atm. Is about 1.05 atm at the time of bonding. That is, the pressure change can be suppressed to about 1.5 times by setting Vd / Vp to 0.8. Of course, it is possible to further reduce the pressure change in the internal space by making Vd / Vp smaller than 0.8.

  As described above, in this embodiment, since the increase in pressure in the internal space when the support substrate 100 and the sealing substrate 200 are bonded to each other is smaller than the conventional case, the problem of bursting of the seal resin 150 is reduced. .

  In the present embodiment, as shown in FIGS. 1 and 2, a desiccant layer 210 is formed inside the EL element 101, and a horizontal distance N between the end of the desiccant layer 210 and the end of the EL element 101. The desiccant layer 210 and the EL element 101 are disposed so that the thickness is 3 cm or less. As will be described later, since the outside of the organic EL element 101 is usually covered with the cathode layer (see FIG. 7), the horizontal distance N between the end of the desiccant layer 210 and the end of the cathode layer is 3 cm or less. It can also be said that they are arranged as follows. As a result, the sealing resin 150 can be prevented from rupturing, and at the same time, even a small amount of moisture that has entered through the sealing resin 150 or the like can be effectively absorbed and removed before reaching the end of the EL element 101. Thus, the moisture resistance of the entire EL element 101 can be improved.

  Note that the end of the desiccant layer 210 may be formed outside the EL element 101 as long as the range satisfies the relationship of 0 <Vd / Vp ≦ 0.8.

  Next, an EL display device according to a second embodiment of the present invention will be described. FIG. 3 is a plan view showing an EL display device according to the second embodiment of the present invention, and FIG. 4 is a sectional view taken along line BB ′ in FIG. In FIG. 3, the same components as those in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof is omitted or simplified.

  In the first embodiment, the desiccant layer 210 is formed in a single region, but in the present embodiment, the desiccant layer 220 is divided into a matrix.

  The pocket portion 201 and the desiccant layer 220 are arranged so as to maintain a relationship of 0 <Vm / Vp ≦ 0.8 between the volume Vp of the pocket portion 201 and the total volume Vm of the plurality of desiccant layers 220. When the desiccant layer 220 is formed inside the EL element 101, the horizontal distance N from the end of each desiccant layer 220 to the end of the EL element 101 is 3 cm or less. The arrangement is the same as in the first embodiment.

  In the EL display device configured as described above, the sealing resin 150 can be prevented from being ruptured as in the first embodiment, and the individual desiccant layers 220 can be formed without unevenness. There is an advantage of preventing the occurrence of defects in the agent layer. In addition, there is a merit that the workability of the step of arranging the desiccant is improved and the manufacturing cost can be kept low. These points will be described with reference to FIG.

  FIG. 5 is a diagram illustrating a process of forming the desiccant layer 220 on the sealing substrate 200. As a method for applying the desiccant layer 220, an injection method using a dispenser is generally employed. In this embodiment, sheet-like desiccants 220 a and 220 b are formed on the sealing substrate 200 using the head 230. Yes.

  The sheet-like desiccants 220a and 220b contain calcium oxide, barium oxide, or the like inside, and an adhesive layer is applied in advance to the back surface thereof. First, as shown in FIG. 5A, one sheet-like desiccant layer 220b is adsorbed and fixed by suction by the head 230, and a desired portion on the pocket (recessed portion) 201 as shown in FIG. 5B. After moving to the position, it is affixed on the sealing substrate 200 with a pressing force by the head 230. By performing the above steps mechanically continuously, the desiccant layer 220 divided into a matrix shape is completed.

  In this embodiment, since the desiccant layer is divided into a matrix, the area of the bonding surface of each desiccant layer is naturally reduced. As a result, gas is less likely to be caught on the adhesive surface during pasting, so that each desiccant layer can be formed evenly and defects (for example, damage to the EL element due to contact between the desiccant layer and the EL element) ) Is reduced. In addition, since it is sufficient to always use the head 230 having a constant size, even if the size of the EL element 101 or the sealing substrate 200 is changed, the head replacement step due to this is not necessary. Therefore, the cost for the head can be kept low, the process can be simplified, and the production speed can be improved. Furthermore, since the desiccant layer is divided into a matrix, the surface area of the desiccant layer is increased and moisture absorption is facilitated.

  Note that the end of the desiccant layer 220 may be formed outside the EL element 101 as long as the relationship satisfying the relationship of 0 <Vd / Vp ≦ 0.8 is satisfied as in the first embodiment. It is.

  Next, a configuration example of a display pixel of an EL display device applied in common to the first and second embodiments will be described. In addition, although there exist what consists of an organic EL element and what consists of an inorganic EL element in an EL display apparatus, below, the EL display apparatus which consists of an organic EL element is demonstrated as an example.

  FIG. 6 is a plan view showing the vicinity of the display pixel of the EL display device, FIG. 7A shows a cross-sectional view taken along the line CC in FIG. 6, and FIG. 7B shows D in FIG. A cross-sectional view along the line -D is shown.

  As shown in FIG. 6, display pixels 115 are formed in a region surrounded by the gate signal lines 51 and the drain signal lines 52, and are arranged in a matrix.

  The display pixel 115 includes an organic EL element 60 that is a self-luminous element, a switching TFT 30 that controls the timing of supplying current to the organic EL element 60, and a driving TFT 40 that supplies current to the organic EL element 60. A storage capacitor is arranged. The organic EL element 60 includes an anode 61 as a first electrode, a light emitting element layer made of a light emitting material, and a cathode 65 as a second electrode.

  That is, a switching TFT 30 is provided in the vicinity of the intersection of both signal lines 51 and 52, and the source 33s of the switching TFT 30 also serves as a capacitor electrode 55 that forms a capacitance with the storage capacitor electrode line 54 and is driven. Is connected to the gate electrode 41 of the driving TFT 40, the source 43 s of the driving TFT 40 is connected to the anode 61 of the organic EL element 60, and the drain 43 d is connected to the driving power supply line 53 that is a current source supplied to the organic EL element 60. It is connected.

  A storage capacitor electrode line 54 is arranged in parallel with the gate signal line 51. The storage capacitor electrode line 54 is made of chromium or the like, and forms a capacitance by accumulating electric charges between the capacitor electrode 55 connected to the source 33 s of the switching TFT 30 via the gate insulating film 12. This storage capacitor is provided to hold a voltage applied to the gate electrode 41 of the driving TFT 40.

As shown in FIG. 7, the EL display device includes a switching TFT 30, a driving TFT 40, and an organic EL element 60 in this order on a substrate 10 made of glass, synthetic resin, or the like, or a substrate 10 such as a semiconductor substrate. It is formed by stacking. However, when a conductive substrate and a semiconductor substrate are used as the substrate 10, an insulating film such as SiO ₂ or SiN is formed on the substrate 10, and then the switching TFT 30, the driving TFT 40, and the organic EL element 60 are formed. Form. Both TFTs have a so-called top gate structure in which the gate electrode is above the active layer via the gate insulating film.

First, the switching TFT 30 will be described. As shown in FIG. 7A, an amorphous silicon film (hereinafter referred to as “a-Si film”) is formed on an insulating substrate 10 made of quartz glass, non-alkali glass or the like by a CVD method or the like. The a-Si film is irradiated with laser light to be melted and recrystallized to form a polycrystalline silicon film (hereinafter referred to as “p-Si film”), which is used as the active layer 33. On top of this, a single layer or a laminate of SiO ₂ film and SiN film is formed as the gate insulating film 32. In addition, a gate signal line 51 also serving as a gate electrode 31 made of a refractory metal such as Cr or Mo and a drain signal line 52 made of Al are provided, which is a drive power supply for the EL element and a drive power supply made of Al. A line 53 is arranged.

An interlayer insulating film 15 in which an SiO ₂ film, an SiN film, and an SiO ₂ film are stacked in this order is formed on the entire surface of the gate insulating film 32 and the active layer 33, and a contact provided corresponding to the drain 33d. A drain electrode 36 in which a metal such as Al is filled in the hole is provided, and a planarization insulating film 17 made of an organic resin and flattening the surface is formed on the entire surface.

Next, the driving TFT 40 will be described. As shown in FIG. 7B, on the insulating substrate 10 made of quartz glass, non-alkali glass or the like, the active layer 43 formed by polycrystallizing the a-Si film by irradiating a laser beam, the gate insulating film 12. , And a gate electrode 41 made of a refractory metal such as Cr or Mo is formed in this order. The active layer 43 is provided with a channel 43c, and a source 43s and a drain 43d on both sides of the channel 43c. Then, an interlayer insulating film 15 in which an SiO ₂ film, an SiN film, and an SiO ₂ film are stacked in this order is formed on the entire surface of the gate insulating film 12 and the active layer 43, and Al is formed in the contact hole provided corresponding to the drain 43d. A drive power supply line 53 filled with metal such as is connected to the drive power supply is disposed. Further, a flattening insulating film 17 made of, for example, an organic resin and flattening the surface is provided over the entire surface. Then, a contact hole is formed at a position corresponding to the source 43s of the planarization insulating film 17, and the transparent electrode made of ITO that is in contact with the source 43s through this contact hole, that is, the anode 61 of the organic EL element 60 is planarized. It is provided on the insulating film 17. The anode 61 is separately formed in an island shape for each display pixel.

  The organic EL element 60 includes an anode 61 made of a transparent electrode such as ITO (Indium Tin Oxide), a first hole transport layer made of MTDATA (4,4-bis (3-methylphenylphenylamino) biphenyl), a TPD (4,4, A hole transport layer 62 composed of a second hole transport layer composed of 4-tris (3-methylphenylphenylamino) triphenylanine), and a light emitting layer 63 composed of Bebq2 (10-benzo [h] quinolinol-beryllium complex) containing a quinacridone derivative. , And an electron transport layer 64 made of Bebq 2 and a cathode 65 made of a magnesium-indium alloy or aluminum, or an aluminum alloy.

  Note that a second planarization insulating film 66 is further formed on the planarization insulating film 17. The end portion of the anode 61 is covered with the second planarization insulating film 66, and the light emitting region on the anode 61 has a structure in which the second planarization insulating film 66 is removed.

  In the organic EL element 60, holes injected from the anode 61 and electrons injected from the cathode 65 are recombined inside the light emitting layer, and excitons are generated by exciting organic molecules forming the light emitting layer. Light is emitted from the light emitting layer in the process of radiation deactivation of the excitons, and the light is emitted from the transparent anode 61 to the outside through the transparent insulating substrate to emit light.

1 is a plan view illustrating an EL display device according to a first embodiment of the present invention. 1 is a cross-sectional view illustrating an EL display device according to a first embodiment of the present invention. It is a top view explaining the EL display device concerning a 2nd embodiment of the present invention. It is sectional drawing explaining the EL display apparatus which concerns on the 2nd Embodiment of this invention. It is sectional drawing explaining the EL display apparatus which concerns on the 2nd Embodiment of this invention. FIG. 11 is a plan view illustrating a pixel of an EL display device. It is a cross-sectional view illustrating a pixel of an EL display device. It is sectional drawing explaining the EL display apparatus which concerns on a prior art example. It is sectional drawing explaining the EL display apparatus which concerns on a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Substrate 12 Gate insulating film 15 Interlayer insulating film 17 Flattening insulating film 30 Switching TFT 31 Gate electrode 32 Gate insulating film
33s source 33 active layer 40 driving TFT 41 gate 43 active layer 43c channel 43d drain 43s source 51 gate signal line 52 drain signal line 53 drive power supply line
54 holding capacitor electrode line 55 capacitive electrode 60 organic EL element 61 anode 62 light emitting element layer 63 light emitting layer 64 electron transport layer 65 cathode 66 planarizing insulating film 100 support substrate 101 EL element 115 pixel 150 sealing resin 200 sealing substrate 201 recess ( Pocket part)
210 Desiccant Layer 220 Desiccant Layer 220a, 220b Desiccant Layer 230 Head

Claims (11)

A support substrate having an electroluminescence element on its surface;
A sealing substrate in which a concave portion is formed on a surface facing the electroluminescence element, and is bonded to the support substrate via an adhesive,
A desiccant layer formed on the inner surface of the recess,
The volume of the recess is V1,
When the volume of the desiccant layer is V2,
An electroluminescence display device, wherein the relationship of 0 <V2 / V1 ≦ 0.8 is established. 2. The electro according to claim 1, wherein the desiccant is formed inside the electroluminescent element, and a horizontal distance between an end of the electroluminescent element and an end of the desiccant layer is 3 cm or less. Luminescence display device. The electroluminescent display device according to claim 1, wherein the desiccant layer is divided into a matrix. The electroluminescent display device according to any one of claims 1 to 3, wherein the desiccant layer is made of a sheet-like desiccant. The change from the pressure in the space between the support substrate and the sealing substrate before bonding through the adhesive to the pressure in the space after bonding through the adhesive is 1.0 times. The electroluminescence display device according to claim 1, wherein the electroluminescence display device is less than 2.0 times. A support substrate having an electroluminescence element on its surface;
Prepare a sealing substrate with a recess formed on the surface,
Forming a desiccant layer on the inner surface of the recess;
Bonding the support substrate and the sealing substrate through an adhesive so that the electroluminescent element and the concave portion face each other,
The volume of the recess is V1,
When the volume of the desiccant layer is V2,
The desiccant is formed so that the relationship of 0 <V2 / V1 ≦ 0.8 is satisfied. A method for manufacturing an electroluminescent display device, comprising: The desiccant is formed inside the electroluminescent element, and the electroluminescent element and the desiccant layer are formed such that a horizontal distance between an end of the electroluminescent element and an end of the desiccant layer is 3 cm or less. The method of manufacturing an electroluminescence display device according to claim 6, wherein: The method for manufacturing an electroluminescent display device according to claim 6, wherein the desiccant layer is formed by being divided into a matrix. 9. The method for manufacturing an electroluminescent display device according to claim 6, wherein the desiccant layer is made of a sheet-like desiccant. The step of forming a desiccant layer in the recess is as follows:
Adsorbing and fixing the surface of a plurality of sheet-shaped desiccants with adhesive applied on the back,
The method for manufacturing an electroluminescent display device according to claim 6, further comprising a step of bonding the concave portion and the back surface of the sheet-type desiccant with a pressing force of the head. . The step of bonding the support substrate and the sealing substrate through an adhesive includes the pressure of the space after bonding from the pressure of the space between the support substrate and the sealing substrate before bonding. The method for manufacturing an electroluminescent display device according to claim 6, wherein the change is made to 1.0 times or more and less than 2.0 times.

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