JP3524321B2 - Method for manufacturing plate-like body having precision partition, plate-like body having precision partition, method for manufacturing substrate for plasma display device, and substrate for plasma display device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a plate-shaped body having a precision partition, a plate-shaped body having a precision partition, a substrate for a plasma display device used in a high-precision and inexpensive large-screen color display device and the like. And a substrate for a plasma display device.

[0002]

2. Description of the Related Art A plasma display device used in a thin large-screen color display device or the like is provided with facing electrodes in a space surrounded by partition walls called minute display cells, and discharge of rare gas or the like in the space. It has a structure in which possible gas is enclosed, and plasma is generated by discharge between the opposing electrodes,
The plasma causes the phosphor to emit light and is used as a light emitting element of the screen.

As shown in FIG. 12, a specific structure is such that a large number of partition walls 102 are formed on one surface of a back plate 101 to form cells 103 between the partition walls 102, and an electrode 104 is provided on the bottom surface of the cell 103. The one is a substrate 105. This board 1
05, the phosphor was applied to the inner wall surface 106 of the cell 103, while the front plate 108 having the electrodes 107 was mounted on the substrate 1.
The plasma display device is configured by joining the cells on the partition wall No. 05 and enclosing the gas in the cell 103. Although the electrodes 104 and 107 are actually arranged so as to be orthogonal to each other, they are arranged in parallel in FIG. 12 for the sake of explanation.

When manufacturing the substrate 105 for the plasma display device, a large number of electrodes 104 are formed on the back plate 101 in advance, and then the partition walls 106 are provided between the electrodes 104.
As a method of manufacturing the partition wall 106, a printing lamination method, an additive method, a sandblast method, and a photosensitive paste method are known. The printing lamination method uses the partition wall 102.
The partition wall 102 having a predetermined pattern is formed by printing on the back plate 101 by using a thick film printing method using a paste of a material forming the above. Since the thickness that can be formed by one printing is about 30 μm, printing is performed. Approximately 200μ while repeating drying
The partition wall 102, which requires a height of about m, is formed (see JP-A-2-213020).

Further, in the additive method, a photosensitive resin is applied on the back plate 101, and grooves are formed in the photosensitive resin with light,
A glass powder is embedded in the groove to form the partition wall 102. Furthermore, the sandblast method is used for the back plate 1
A glass layer having a predetermined thickness is formed on the entire surface of No. 01, a resist mask in the shape of the partition 102 is formed on the surface, and the glass layer other than the partition 102 is removed by sandblasting. (JP-A-4-259728
(See Japanese Patent Publication).

Further, the photosensitive paste method is a method in which a paste containing a photosensitive resin is applied on the back plate 101, masked and then irradiated with light to directly form the partition wall 102.

[0007]

However, in the above-mentioned printing and laminating method, the printing and drying steps have to be repeated many times to form the partition wall 102 having a predetermined height, and the number of steps is extremely large. In addition, the number of prints is increased, and moreover, it is necessary to print with high accuracy for each stack, so that the yield is very low. Further, the partition wall 102 is easily deformed due to misalignment during printing, and due to elongation of the printing plate, the dimensional accuracy of the display cell formed by the partition wall 102 is 100.
There was a maximum difference of about 0.35 mm in the measured values when measuring the size of 0 cell in 45 columns, which did not satisfy the demand for high definition.

Further, even in the additive method, the partition wall 102 is formed by using light, and the partition wall 1 is not always sufficiently accurate.
02 could not be formed. Further, even in the sandblasting method, since the sandblasting is performed after using the photoresist for forming the mask, the process is complicated,
Moreover, it was difficult to form the partition wall 102 with high accuracy. Further, when the abrasive used for the blasting process is collected and repeatedly used, the grinding force is deteriorated due to wear deterioration of the abrasive and changes with time, so that it is difficult to mass-produce it stably. On the other hand, if you use it without collecting the abrasive,
The cost of the abrasive has increased, and in this case too, mass production has been difficult.

Furthermore, the barrier ribs 102 are formed by using light even by the photosensitive paste method, and the barrier ribs 102 cannot always be formed with sufficient accuracy. In the plasma display device substrate 105, it is strongly demanded that the partition walls 102 be accurately and accurately arranged between the electrodes 104 on the back plate 101, but in any of the above manufacturing methods, the partition walls 102 have high precision and a fine pitch. It has been difficult to inexpensively manufacture the large-sized plasma display device substrate 105 by a simple process.

The present invention has been made in view of the above problems, and an object thereof is to manufacture a substrate for a plasma display device in a single molding step with a high yield and to obtain a smooth surface without deformation. A substrate for a plasma display device capable of obtaining a highly accurate partition wall having a predetermined height, easily realizing a large screen of 40 inches or more, and achieving a high definition of a display cell pitch of less than 0.25 mm, and a substrate thereof. It is to provide a manufacturing method.

[0011]

In view of the above-mentioned circumstances, the present invention forms a precise partition wall, so that the grain size is 0.2-10.
μm ceramic powder or glass powder and polyvinyl chloride
Alcohol, polyvinyl butyral, acrylic
A mixture of at least one binder of grease, styrene resin, and urethane resin is applied to a back plate made of ceramics or glass, and the application surface is applied on the surface of a roll having a plurality of circumferential grooves. By rotating while applying pressure to form partition walls on the back plate , a space between the partition walls of a screen of 40 inches or more can be formed .
A method of manufacturing a substrate for a plasma display device , in which the cell pitch was less than 0.25 mm .

Further, according to the present invention, in order to reliably arrange the electrodes between the partition walls of the substrate, a mixture of ceramic powder or glass powder and a binder is applied to a back plate made of ceramics or glass, and the applied mixture is applied. Plasma display in which electrode paste is applied on top of the rolls, the rolls are engraved with multiple grooves, and the rolls are rotated while pressurizing the coating surface to form partition walls on the back plate and electrodes are arranged between the partition walls. A method for manufacturing a device substrate is used.

Further, according to the present invention, in order to reliably dispose the black material at the tip of the partition wall of the substrate, a mixture of ceramic powder or glass powder and a binder is applied to a back plate made of ceramics or glass and applied. A black material is further coated on the mixture, and the partition is formed on the back plate by rotating while applying pressure to the coating surface on the surface of the roll having a plurality of grooves engraved, and the black material is arranged at the tip of the partition. The method for producing a substrate for a plasma display device as described above was employed.

Furthermore, according to the present invention, a mixture of ceramic powder or glass powder and a binder is applied to a back plate made of ceramics or glass in order to surely separate the partition from the roll after processing, A mold release agent is further applied on the applied mixture, and the roll is engraved with a plurality of circumferential grooves to rotate while applying the pressure on the coated surface to form a partition wall on the back plate, and a mold release agent at the partition wall tip. Was arranged, and the partition walls were released from the roll after processing, and the plasma display device substrate was manufactured.

Further, according to the present invention, in order to improve the smoothness of the substrate, a butyral resin is applied to a back plate made of ceramics or glass, and a mixture of ceramic powder or glass powder and a binder is applied on the butyral resin. Apply and rotate while applying pressure to the surface of the roll with multiple grooves engraved to form partition walls on the back plate, and apply butyral resin to smooth the back plate and the adhesion between the back plate and the partition walls. The method of manufacturing a substrate for a plasma display device is improved. Furthermore, according to the present invention, a substrate for a plasma display device is manufactured by the above-described method for manufacturing a substrate for a plasma display device.

Further, according to the present invention, a plasma display device is formed between the partition walls using the above-mentioned substrate for plasma display device.
The bottom surface of the cell is equipped with an electrode, and the phosphor is
Apply and cover the top of the partition with a front plate equipped with electrodes
It was a plasma display device .

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. As shown in FIG. 1, a substrate 1 for a plasma display device is provided with a plurality of partition walls 3 made of ceramics or glass on one surface of a back plate 2 made of ceramics or glass, and cells 4 are formed between the partition walls 3. .

Then, an electrode 5 is provided on the bottom surface of the cell 4, and after the phosphor is applied to the inner wall surface 6 of the cell 4, the front plate 108 provided with the electrode 107 as shown in FIG. A plasma display device can be constructed by covering the upper end of the cell and enclosing the gas in the cell 4. Then, by discharging between the electrodes 5 and 107, the inner wall surface 6 of the cell 4 is
It is possible to emit light from the phosphor coated on. In practice, the electrodes 5 and 107 are arranged so as to be orthogonal to each other. Further, although not shown, the electrode 107 may be of a three-electrode type composed of a pair of electrodes. In this case, a sustain discharge is generated between the pair of electrodes 107, and the electrodes 5 on the back plate 2
It becomes a surface discharge type controlled by.

Next, a method of manufacturing the substrate 1 will be described.
First, FIG. 2 shows an overview of the whole. The electrodes 5 are formed on one surface of the back plate 2 made of ceramics or glass shown in FIG. 3 by screen printing at predetermined intervals. As shown in FIG.
A paste 11 of a mixture of ceramic or glass powder and a binder is applied on the back plate 2 having the electrodes 5.

Next, as shown in FIG. 5, after the drying, the partition wall 3
The partition wall 3 is formed on the back plate 2 by bringing the surface of the roll 13 having the circumferential groove 12 having a predetermined width and depth corresponding to the above into contact with the application surface of the paste 11 and rotating while applying pressure. . That is, when the roll 13 is brought into contact with and pressed, the paste 11 enters the circumferential groove 12 of the roll 13 and is pressed and solidified to form the partition wall 3.

The pressure applied to the roll 13 is, for example, the roll 13
Contact length with the paste 11 in the axial direction of 7k per 1cm
When the contact length is 100 cm, the weight becomes 700 kg. After that, if the partition walls 3 are cured by heat treatment or the like, the substrate 1
Can be obtained. As described above, according to the present invention, since it suffices to rotate the roll 13 while contacting and pressing the roll 13, it is possible to easily form the partition wall 3 with high precision by manufacturing the roll 13 with high precision in advance. Therefore, even a large-sized substrate 1 can be easily manufactured.

The above-described manufacturing method of the present invention can be applied not only to a substrate for a plasma display device but also to a precision partition wall in various members such as an ink jet printer head and a member for optical communication. Here, as the ceramic powder of the paste 11 forming the partition walls 3, alumina (A
l ₂ O ₃ ), zirconia (ZrO ₂ ) and other oxide ceramics, silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), silicon carbide (SiC) and other non-oxide ceramics, or apatite (Ca ₅ (PO ₄ ) ₃
Any of (F, Cl, OH)) can be used, and various sintering aids can be added to these ceramic powders in desired amounts.

[0023] As the sintering aid, the alumina powder silica (SiO _2), calcia (CaO), yttria (Y ₂ O ₃₎ and magnesia (MgO) or the like, the zirconia powder yttria (Y ₂ O ₃ ) and cerium (C
e), dysprosium (Dy), ytterbium (Y
b) and other rare earth element oxides, silicon nitride powders such as yttria (Y ₂ O ₃ ) and alumina (Al ₂ O ₃ ), and aluminum nitride powders such as group 3a element oxides of the periodic table ( RE ₂ O ₃ ), etc., and boron (B), carbon (C), etc. can be added in desired amounts to the silicon carbide powder.

As the glass powder forming the partition wall 3,
Various glasses containing silicate as a main component and containing one or more of lead (Pb), sulfur (S), selenium (Se), alum and the like can be used. Further, if the partition wall 3 is formed of glass and ceramics is added as a filler, the strength and optical characteristics can be improved. For example, white ceramics such as alumina, zirconia, titania, and zinc oxide are used for the purpose of improving the light reflectivity and the brightness of the panel. Dark-colored ceramics such as nickel, copper oxide, and chromium oxide are appropriately added depending on the purpose.

The ceramic or glass powder having a particle size of several tens of microns to submicrons can be suitably used, specifically, 0.2 to 10 μm, preferably about 0.2 to 5 μm. Things are good. Furthermore, examples of organic additives added to these ceramic or glass powders include polyvinyl alcohol, polyvinyl butyral, acrylic resins, styrene resins, urethane resins and the like.

Further, the solvent added to the paste 11 of the mixture is not particularly limited as long as it is compatible with the organic additives, and examples thereof include aromatic substances such as toluene, xylene, benzene and phthalic acid ester. Group solvents, higher alcohols such as hexanol, octanol, decanol and oxyalcohol, or esters such as acetic acid ester and glyceride can be used.

Above all, the above-mentioned phthalic acid ester, oxyalcohol and the like can be preferably used, and in addition, two or more kinds of the above-mentioned solvents can be used together in order to slowly volatilize the solvent. In addition, the content of the solvent is required to be 0.1 parts by weight or more based on 100 parts by weight of the ceramic or glass powder in order to maintain the shape retention of the formed body from the viewpoint of formability. Since it is desirable to lower the viscosity of the mixture of the ceramic or glass powder and the organic additive, it is more preferably 35 parts by weight or less, and 1 to 15 parts by weight in consideration of shrinkage during drying and firing. Is most desirable.

The material of the roll 13 in the present invention is not particularly limited. For example, metal, resin, rubber or the like can be used, and if necessary, surface treatment such as surface coating for improving releasability and preventing abrasion. You may go. Further, the groove formed on the roll 13 is not limited to the circumferential groove, and may be a groove parallel to the axial direction of the roll 13. Also, the back plate 2
Is an unfired green sheet or a sintered body, and its material is not particularly limited, but it is desirable that the coefficient of thermal expansion be close to that of the material of the partition wall 3 such as various ceramic green sheets, various glass substrates, and porcelain substrates. . As the glass substrate, relatively inexpensive glass such as soda lime glass or a material in which an inorganic filler is dispersed to improve its strain point can be used.

In order to improve the dispersibility of the ceramic or glass powder in the paste 11 of the mixture, for example, a surfactant such as polyethylene glycol ether, alkyl sulfonate, polycarboxylate or alkylammonium salt is added. The content may be 0.05 to 5 parts by weight with respect to 100 parts by weight of the ceramic or glass powder from the viewpoint of improving dispersibility and thermal decomposability.

Further, a curing catalyst called a curing reaction accelerator or a polymerization initiator can be added to the binder in the paste 11 of the mixture. As the curing catalyst, it is possible to use an organic peroxide or an azo compound,
For example, ketone peroxide, diacyl peroxide, peroxyketal, peroxyester, hydroperoxide, peroxycarbonate, t-butylperoxy-2-ethylhexanoate, bis (4-
Examples thereof include organic peroxides such as t-butylcyclohexyl) peroxydicarbonate and dicumyl peroxide, and azo compounds such as azobisisobutyronitrile.

Next, another embodiment will be described. In FIG. 6, a paste 11 of a mixture of ceramic or glass powder and a binder is applied on the back plate 2.
Electrode paste 14 on top of paste 11 of the applied mixture
Has been applied. Circumferential groove 1 similar to the method described above
When a roll 13 having a plurality of 2 is abutted and rotated while being pressurized, partition walls 3 are formed, and an electrode paste 14 is accurately placed between the partition walls 3 as shown in FIG. 5. When the electrode paste 14 at the tip of the partition wall 3 is unnecessary, it may be deleted.

In the above, an example in which the electrodes 5 are accurately arranged between the partition walls 3 has been described, but in order to improve the adhesiveness between the rear plate 2 and the front plate 108 and to provide image contrast, When a black material is to be provided at the tip of the partition wall 3, as shown in FIG.
A black material 15 is further applied onto the above. Then, as in the method described above, as shown in FIG. 9, a roll 13 having a plurality of circumferential grooves 12 is rotated while abutting against the black material 15 to form the partition wall 3 on the back plate 2. However, the black material 15 can be accurately provided on the tip of the partition wall 3. As the above-mentioned black material, for example, black glass is used.

Further, in order to surely release the partition wall 3 after molding with the roll 13, as shown in FIG. 10, a release agent 16 is applied on the paste 11 of the mixture adhered to the upper surface of the back plate 2. Should be applied beforehand. Further, the surface of the back plate 2 made of ceramics or glass has irregularities of about ± 10 μm, but the butyral resin 17 is applied so that the surface of the back plate 2 becomes flat as shown in FIG.
The partition 3 can also be formed there. Even if there is some unevenness on the surface of the back plate 2, the butyral resin 17 is applied so that the roll 13 can be smoothly rotated, and the partition wall 3 can be accurately formed on the back plate 2.

Then, when heated, butyral resin 17
Even if there exists, the partition wall 3 moves until it comes into contact with the back plate 2 and comes into contact with the back plate 2 and is joined thereto. Bonding of the back plate 2 and the front plate 108 thus formed can be performed without any problem. Example 1 As the roll 13, a metal roll having a diameter of 50 mm and a length of 200 mm was engraved with 900 circumferential grooves having a groove width of 50 μm and a groove depth of 200 μm at a pitch of 220 μm. On the other hand, a glass plate made of soda lime having a size of 200 × 250 mm was prepared as the back plate 2.

As the paste 11, low melting point lead glass powder to which alumina and titania were added was kneaded with a binder to form a paste, which was applied onto a glass plate by a doctor blade method. The roll was pressed from above the coating film at a pressure of 7 kg / cm, the roll was rotated, and the glass plate was sent to form partition walls. The obtained molded body was fired at 550 to 600 ° C.

By the above operation, width 40 μm, height 15
A substrate for a plasma display device having a partition wall of 0 μm was obtained. Example 2 Similar to Example 1, a roll having a circumferential groove and a glass plate coated with paste were prepared. On the paste coating surface,
A conductive paste containing Ag as a main component was applied as the electrode paste 14 and dried at 80 ° C. Roll 7kg / c
It was pressurized with m and rotated to form a partition wall on the glass plate.

The obtained molded body was fired at 550 to 600 ° C. By the above operation, width 40μm, height 150μm
Thus, a substrate for a plasma display device having the partition walls was obtained. At this time, the space between the partition walls was filled with a conductive paste and functioned as an electrode. Example 3 Similar to Example 1, a roll having a circumferential groove was prepared.
As the paste, a white paste containing titania and a black paste containing nickel oxide as the black material 15 were prepared.

A white paste was applied on a glass plate material, dried, and then a black paste was overlaid and applied. A partition was formed using a roll at a pressure of 7 kg / cm. By firing the obtained molded body at 550 to 600 ° C., a substrate for a plasma display device having a black partition wall tip was obtained.

Example 4 Butyral resin in the form of a solution with a volatile solvent was applied to the surface of a glass plate and dried. When the partition wall was formed by the same method as in Example 1, the variation in the partition wall height due to the variation in the thickness of the glass plate material was ± 10 μm.
In this example, it was ± 3 μm.

[0040]

As described above, the present invention has a particle size of 0.2.
Ceramic powder or glass powder of 10 μm and po
Livinyl alcohol, Polyvinyl butyral, Ac
At least one of rill resin, styrene resin, urethane resin
A mixture of species of the binder, was applied to the back plate made of ceramic or glass, by forming the partition walls on the back plate is rotated while pressing the coated surface on the surface of a plurality of rolls engraved circumferential groove , 40 inch screen or more
Since this is a method of manufacturing a substrate for a plasma display device in which the cell pitch between walls is less than 0.25 mm , a precise method of manufacturing partition walls can be provided inexpensively and reliably.

In the present invention, a mixture of ceramic powder or glass powder and a binder is applied to a back plate made of ceramics or glass, and an electrode paste is further applied onto the applied mixture to form a plurality of grooves. It is a method of manufacturing a substrate for a plasma display device in which partition walls are formed on the back plate by rotating while applying pressure on the surface of the roll engraved with the coating surface. The electrodes can be reliably arranged in between.

Further, according to the present invention, a mixture of ceramic powder or glass powder and a binder is applied to a back plate made of ceramics or glass, and a black material is further applied onto the applied mixture to form a plurality of materials. Since it is a manufacturing method of a substrate for a plasma display device in which a partition is formed on the back plate by rotating while applying a pressure on the surface of the roll in which grooves are engraved, and a black material is arranged at the tip of the partition,
The black material can be reliably placed on the tip of the partition wall of the substrate.

Furthermore, in the present invention, a mixture of ceramic powder or glass powder and a binder is applied to a back plate made of ceramics or glass, and a release agent is further applied onto the applied mixture. , The surface of the roll having a plurality of circumferential grooves engraved is rotated while pressing the coating surface to form a partition wall on the back plate, and a mold release agent is arranged at the tip of the partition wall.
Since this is a method of manufacturing a substrate for a plasma display device in which the partition wall is released from the processed roll, the partition wall can be reliably released from the processed roll.

In the present invention, a butyral resin is applied to a back plate made of ceramics or glass, a mixture of ceramic powder or glass powder and a binder is applied on the butyral resin, and a plurality of grooves are formed. For plasma display device in which partition walls are formed on the back plate by rotating the coated surface while applying pressure to the back plate, and the smoothness of the back plate and the adhesion between the back plate and the partition walls are improved by the coated butyral resin. Since it is a method of manufacturing a substrate, the smoothness of the substrate can be improved. Further, since the present invention is manufactured by the above method for manufacturing a plasma display device substrate, a dense and inexpensive plasma display device substrate can be provided.

The present invention also provides the above plasma display device.
Electrodes on the bottom surface of the cell formed between the partitions
Equipped with a phosphor on the inner wall surface of the cell and equipped with an electrode
Plasma display device in which a front plate covers the upper end of the partition wall
And

[Brief description of drawings]

FIG. 1 is a perspective view of a substrate for a plasma display device according to the present invention.

FIG. 2 is a perspective view showing an outline of a manufacturing method of the present invention.

FIG. 3 is a vertical cross-sectional view showing a state in which electrodes are attached to one surface of a back plate according to the present invention by printing.

FIG. 4 is a vertical cross-sectional view showing a state in which the paste of the mixture is attached to the back plate.

FIG. 5 is a vertical cross-sectional view showing a state where a partition wall is formed on a back plate by a roll.

FIG. 6 is a vertical cross-sectional view of a back plate with an electrode paste applied.

FIG. 7 is a vertical cross-sectional view of a state in which a partition wall is formed on the back plate by a roll on the surface in the state shown in FIG.

FIG. 8 is a vertical cross-sectional view showing a state where a black material is applied to the back plate.

9 is a vertical cross-sectional view showing a state in which partition walls are formed on the back plate by rolls on the surface in the state shown in FIG.

FIG. 10 is a vertical cross-sectional view showing a state where a release agent is attached to the back plate.

FIG. 11 is a vertical cross-sectional view showing a state in which a butyral resin is applied to the surface of an uneven back plate to form a smooth surface.

FIG. 12 is a vertical cross-sectional view showing an outline of a conventional plasma display device.

[Explanation of symbols]

1 ... Substrate 2 ... Back plate 3 ... Partition 4 ... cell 5 ... Electrode 6 ... Inner wall 11 ... Mix paste 12 ... Circumferential groove 13 ... roll 14 ... Electrode paste 15 ... Black material 16 ... Release agent 17 ... Butyral resin

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenichi Yoneyama 1-4 Yamashita-cho, Kokubun-shi, Kagoshima Kyocera Co., Ltd. Research Institute (72) Inventor, Masahiko Nishioka 1-4 Yamashita-cho, Kokubun-shi, Kagoshima Kyocera stock-type Company Research Institute (56) Reference JP-A-10-199401 (JP, A) JP-A-10-188793 (JP, A) JP-A-9-283017 (JP, A) JP-A-9-69335 (JP , A) JP-A-9-12336 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01J 9/02 H01J 11/02

Claims (3)

(57) [Claims] 1. A mixture of ceramic powder or glass powder and a binder is applied to a back plate made of ceramics or glass, and an electrode paste is further applied on the applied mixture to form a plurality of grooves. A method of manufacturing a substrate for a plasma display device, wherein a partition surface is formed on a back plate by rotating a roll surface while applying pressure to the coating surface, and electrodes are arranged between the partition walls. 2. A mixture of ceramic powder or glass powder and a binder is applied to a back plate made of ceramics or glass, and a black material is further applied on the applied mixture to form a plurality of grooves. Form the partition on the back plate by rotating while applying pressure to the coated surface on the surface of the roll,
A method for manufacturing a substrate for a plasma display device, in which a black material is arranged at the tip of a partition. 3. A surface of a roll in which a butyral resin is applied to a back plate made of ceramics or glass, a mixture of ceramic powder or glass powder and a binder is applied to the butyral resin, and a plurality of grooves are engraved. A method for manufacturing a substrate for a plasma display device in which a partition wall is formed by rotating the coating surface while applying pressure with a back plate, and the smoothness of the back plate and the adhesion between the back plate and the partition wall are improved by the applied butyral resin. .