JP2001276720A - Thick film forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thick film forming method easy to reduce film thickness even in the case of large area printing becoming large in plate making. SOLUTION: In a glass paste coating process, paste films 34 are applied and formed in the range corresponding to the printing region of one surface 12 in an intermittent shape following the shape of aperture parts in a coating area ratio corresponding to the opening ratio of the aperture parts but, by subjecting the paste films 34 to levelling treatment in a levelling process, the intermittent parts of the paste films are mutually connected by the edge sagging thereof and formed into the paste film 36 coating the printing range without leaving gaps. Therefore, the paste films 34 formed by coating have relatively large thickness corresponding to the total thickness of a screen at first but the thicknesses of them are averaged over the entire surface including uncoated parts in the printing range in the leveling treatment process and changed to thin film thickness to a degree such that the first thickness of paste is multiplied by the opening ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improvement in a method for forming a thick film using a screen printing method.

[0002]

2. Description of the Related Art A thick film type PDP (Plasma Display Panel) substrate having a thick film pattern of a conductor or an insulator and a plasma addressed liquid crystal panel (Plasma Addressed Liquid) are formed by printing a thick film material using screen printing. Cry
stal Panel) plasma switching substrate, VFD
It is known that a thick-film anode substrate of Vacuum Fluorescent Display or a thick-film wiring board is manufactured. In these thick-film substrates, there is a tendency that demands for larger print patterns and higher definition are increasing year by year. For example, PDP
HDT for substrates and plasma switching substrates
Large and high-resolution display devices such as V are desired, and in the case of thick film anode substrates and thick film wiring substrates of VFDs, it is necessary to increase the display density or wiring density and to increase the manufacturing efficiency by multi-cavity production. It is because it is desired.

A screen plate (hereinafter, referred to as "plate making") used for thick film screen printing as described above has a screen of a predetermined mesh stretched on one surface of a plate frame having a rectangular frame shape. The screen is provided with openings (print patterns) of a predetermined shape formed by patterning with a photosensitive resin (emulsion) or the like. When performing screen printing, a thick-film printing paste is placed on a screen of a plate making arranged at a predetermined fixed plate interval from a printing surface, and the screen is pressed down toward the printing surface. Then, by sliding the squeegee along a predetermined sliding direction, the thick film printing paste is extruded from the opening of the screen and printed on the printing surface.

[0004]

By the way, the thickness of the thick film formed by the above-described thick film screen printing method is generally equal to the total thickness of the screen including the thickness of the fixed photosensitive resin. It is about 1/3. Therefore, when increasing the film thickness, for example, increase the thickness of the photosensitive resin to be fixed,
Alternatively, printing is repeatedly performed using the same plate making to laminate a thick film printing paste. On the other hand, when the film thickness is reduced, for example, the amount of resin in the thick film printing paste is increased to reduce the residual ratio after firing, or to reduce the thickness of the screen.

However, if the amount of resin is increased in order to reduce the film thickness, there is a problem that the paste viscosity is increased and the separation from the printing plate is deteriorated. On the other hand, the thickness of the screen is determined, for example, by the wire diameter of the fibers constituting the mesh in a commonly used mesh screen. It is set according to. Therefore, in the case of small area printing where the plate making is small, a thin thick film can be easily formed by making the screen thin.However, for a large area printing, it is necessary to make the screen thicker as the plate making becomes larger. It was difficult to make it thin. As the plate making becomes larger, the tensile force acting on the screen increases due to the weight of the screen and the weight of the paste, and the tension to be applied to secure the plate separation increases. The screen must be made thicker in order to control the natural elongation.

Therefore, for example, in a large PDP substrate of about 40 inches (40 inches diagonal) or more, 5 to 10
(μm) to form a relatively thin thick film.
(μm) or more. For example, in a three-electrode AC type thick film type PDP,
A dielectric film having a relatively large area pattern (that is, a “solid” pattern) that covers substantially the entire surface of the front plate on which the discharge electrodes are formed without any gap is provided. It is desired that the thickness of such a dielectric film be reduced to about 10 (μm) or less so that high discharge characteristics can be obtained in a range where a withstand voltage can be ensured.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method of forming a thick film which can easily reduce the film thickness even in large-area printing in which plate making is large. Is to provide.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the gist of the present invention is to provide a method of forming a thick film that covers a predetermined area of a printing surface without gaps by using thick film screen printing. (A) applying a thick film printing paste to the printing surface by using a screen plate having an opening provided so as to be intermittent in a cross section in a predetermined direction in an opening area corresponding to the predetermined range of the screen; Printing process, and (b)
By performing a leveling process on the thick-film printing paste applied through the opening in the predetermined area of the printing surface, the thick-film printing paste intermittently following the shape of the opening is used by using the edge dripping. And a leveling step of forming a coating film having a substantially uniform thickness by covering the predetermined range from the thick-film printing paste without gaps.

[0009]

In this way, in the printing process, the thick film printing paste is applied in an intermittent shape following the shape of the opening within a predetermined range for forming the thick film on the surface to be printed. The thick film printing paste is subjected to a leveling process in a leveling step, so that the interrupted portions are connected to each other by the edge dripping, and a predetermined range is covered without a gap, and a coating film having a substantially uniform thickness is generated. Therefore, the thickness of the applied thick film printing paste is initially a relatively large thickness according to the thickness of the screen,
During the leveling process, the thickness of the entire surface including the uncoated portion within the predetermined range is averaged, and the opening of the opening region is determined by the initial paste thickness according to the degree of intermittent opening. It changes to a thin film thickness multiplied by the ratio. Therefore, by appropriately setting the intermittent shape of the opening in the one direction, a thin thick film can be easily formed even in the case of large-area printing in which it is difficult to reduce the screen thickness.

[0010]

In another preferred embodiment of the present invention, the printing step uses a screen plate provided so that the openings are substantially uniformly distributed in the opening area. With this configuration, the thick-film printing paste is applied in a substantially uniform distribution within the predetermined range, so that it is easier to make the thickness uniform by the leveling process. In addition, as an aspect in which the openings are substantially uniformly distributed in the opening region, for example, strip-shaped (slit-shaped) openings having substantially uniform width dimensions are arranged at substantially uniform center intervals in the width direction. Examples thereof include those in which dot-shaped openings having a substantially uniform area are arranged at substantially equal intervals, those in which dot-shaped non-openings having a substantially uniform area are arranged at substantially equal intervals, and the like.

Preferably, the leveling step comprises:
The thick film printing paste is allowed to stand while being heated at a predetermined temperature, preferably about 5 to 6 (° C.) higher than room temperature. In this case, the resin component contained in the thick-film printing paste is softened by heating, so that the fluidity thereof is enhanced. Therefore, it is possible to perform leveling to a more uniform film thickness in a shorter time. .

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a perspective view for explaining a main structure of a front panel 10 for a PDP manufactured by applying an embodiment of a method for forming a thick film according to the present invention. In the figure, a front plate 10 constitutes a front plate of an AC type PDP having a so-called three-electrode structure having a large display surface of about 40 inches, for example, soda lime glass having translucency. And the like. On one surface 12 of the front plate 10 which is to be located in the discharge space of the PDP, a plurality of discharge electrodes 14 extending in one direction are parallel to each other and two are set as a set according to the definition of display. They are arranged with a fixed center interval. The discharge electrode 14 is made of, for example, a thick-film conductive material such as thick-film silver. In addition to this, a transparent electrode formed by a thin-film process is usually provided in addition to this.
It is omitted in the figure.

On the discharge electrode 14, a dielectric layer 16 made of a low softening point glass such as borosilicate glass is provided in a "solid shape" so as to cover almost the entire surface 12 except for the peripheral portion of the surface 12 without any gap. Further, a protective film 18 made of MgO or the like is provided thereon to cover substantially the entire surface of the dielectric layer 16. The dielectric layer 16 is formed by using a thick film screen printing method.
Is about 10 (μm), which is relatively small for a large PDP substrate of about 40 inches. In the present embodiment, the dielectric layer 16 corresponds to a thick film in the claims, and a predetermined range on one surface 12, which is a printing surface, is set to substantially the entire surface.

The above-described dielectric layer 16 is formed, for example, according to the process shown in FIG. First, in a glass paste application step S1, one surface 12 of the front plate 10 provided with the discharge electrodes 14 in advance in a step (not shown).
A thick film insulating paste 22 containing a glass powder having a low softening point, which is a component of the dielectric layer 16, is applied thereon by a thick film screen printing method. In this application step S1, for example, as shown in FIG. 3, the screen plate 20 is arranged at a height slightly above the one surface 12 and an appropriate amount of the thick film insulating paste 22 is placed thereon, and the squeegee 24 This is performed by extruding the thick-film insulating paste 22 onto the one surface 12 while sending the thick-film insulating paste 22 in the S direction by sliding along one direction indicated by the arrow. The above thick film insulating paste 22
Is composed of, for example, low softening point glass such as borosilicate glass, fillers such as alumina and titania, and pigments such as chromium oxide, and has a viscosity of about 20 to 200 (Pas). It is.

FIG. 4 is a view for explaining the structure of a main part of the plate making 20 described above. In the figure, the plate making 20 includes, for example, a rectangular plate frame 26 whose opposite sides are surrounded by four sides parallel to each other,
A screen 28 is attached to the plate frame 26 at the peripheral edge thereof with an adhesive or the like. The plate frame 26 is made of a lightweight metal material such as aluminum or a light alloy, and has a frame size of, for example, about 1000 to 2000 (mm). On the other hand, the screen 28 is a mesh (net) in which fine wires made of metal such as stainless steel are woven as warps and wefts, for example, about 325 mesh (# 325) is used. The screen 28 is adhered to the plate frame 26 in a state where a tension equivalent to about 0.8 to 0.85 (mm) is applied by a value measured using, for example, an STG-75G type tension gauge manufactured by Toprotec Co., Ltd. ing.

On the entire surface of the screen 28, for example,
A photosensitive resin 30 having a thickness of about 10 to 200 (μm) is fixed. Therefore, the photosensitive resin 3 of the screen 28
The total thickness including 0 is, for example, about 50 to 500 (μm).
The photosensitive resin 30 has its mechanical strength increased by the progress of polymerization by light exposure, and functions as a resist layer that does not transmit the thick film insulating paste 22 during printing. However, the transmission region A of the thick film insulating paste 22 in which the plurality of openings 32 are formed by removing the photosensitive resin 30 in a predetermined pattern after exposure, that is, the printing region Provided. In FIG. 4, the photosensitive resin 30 is fixed in a range indicated by hatching, and a white area indicates the photosensitive resin 3.
0 is the removed portion.

The printing area A is, for example, 500 to 1400 (m
m) × 300-800 (mm), and the plurality of openings 32 formed therein are formed in parallel belt-like patterns extending along the squeezing direction S shown in FIG. is there. Each of the openings 32 has, for example, w = 300 to 500.
It has a width dimension of about (μm) and a length that extends over substantially the entire length of the print area A, and is provided at a substantially uniform center interval with a mutual interval of, for example, d = 50 (μm). Therefore, a plurality of openings 32 are provided in the print area A with a substantially uniform distribution so as to be intermittent in a cross section in a direction perpendicular to the scanning direction S. The ratio of the opening 32 to the entire area of the region A) is about 50 to 80 (%). In the present embodiment, the opening area referred to in the claims corresponds to the printing area A described above.

Therefore, the coating step S is shown in FIGS.
The paste film 34 formed by applying the thick film insulating paste 22 through the opening 32 by using the above-described plate making 20 is a printing In accordance with the shape of the opening 32 in A, the opening 32 has substantially the same width dimension as that of the opening 32, and is intermittently arranged in a direction perpendicular to the squeezing direction S with a similar mutual interval and arranged in parallel to each other. The thickness (height from one surface 12) of the paste film 34 is 15 to 170.
(μm). That is, the paste film 34 is formed with a thickness of about １ ／ of the entire thickness of the screen 28.

Returning to FIG. 2, in the leveling step S2, the leveling process of the paste film 34 applied and formed as described above is performed. This leveling process is performed, for example, immediately after the application step S1 is completed.
Room temperature or heating while the fluidity of 4 hardly decreases
Preferably, it is allowed to stand still for about 1 to 20 minutes while heating to a temperature about 5 to 6 (° C.) higher than room temperature. For example,
In the process of flowing from the printing line to the drying line, it is allowed to stand at room temperature, or is kept at room temperature or under heating while retaining a certain amount in a storage magazine or carrier. This allows
Immediately after the application, the paste films 34 formed intermittently (that is, independently in the form of islands) following the shape of the opening 32 are adjacent to each other by being edged and spreading in the width direction thereof. To form a paste film 36 having a uniform thickness and covering the entire printing area without any gap. FIG. 5B shows this state. At this time, since the thickness of the paste film 36 is averaged in the process of being generated from the paste film 34, the thickness is reduced at a rate corresponding to the non-application area within the printing range. Therefore, despite the fact that the entire thickness of the screen 28 is set to a relatively large value as described above, the thickness of the paste film 36 is a value obtained by multiplying the thickness of the paste film 34 immediately after application by the aperture ratio, that is, , A small value obtained by multiplying a value of about ３ of the total thickness of the screen 28 by the aperture ratio. In this embodiment, the paste film 36 corresponds to a coating film.

In the subsequent drying step S3, the paste film 36 which is continuously formed without gaps and has a uniform thickness is formed.
Is dried at a temperature of several tens to one hundred and several tens (° C.) to remove the solvent in the paste. The film thickness after drying is, for example, 10 (μ
m). Then, in the firing step S4, by performing a heat treatment at a predetermined firing temperature according to the type of the glass component in the paste film 36, the organic component in the paste is removed, and the glass component is melted. The dielectric layer 16 is formed by curing during the process.

In short, according to the present embodiment, in the glass paste application step S1, the printing area A
The thick film insulating paste 22 is applied in an intermittent shape following the shape of the opening 32 in a range corresponding to the opening ratio in a range corresponding to the opening ratio, and the thick film insulating paste 22 is subjected to the leveling step S2. , The intermittent portions are connected to each other by the edge dripping, and the printing area is covered without any gap, and a paste film 36 having a substantially uniform thickness is generated. for that reason,
The thickness of the paste film 34 formed by coating is initially a relatively large thickness corresponding to the entire thickness of the screen 28,
In the course of the leveling process, the thickness is averaged over the entire surface including the uncoated portion within the printing range, and changes to a thin film thickness such that the initial paste thickness is multiplied by the aperture ratio. Therefore, by providing the opening 32 in an intermittent shape with a low opening ratio as described above, even when it is difficult to reduce the screen thickness due to a large printing area as in the present embodiment, it is easy to perform. It is possible to form a thin dielectric layer 16.

Further, according to the present embodiment, the printing step S1
Is performed using the screen plate 20 provided so that the openings 32 are distributed substantially uniformly in the printing area A. Therefore, since the thick film insulating paste 22 is applied with a substantially uniform distribution in the printing range, it is easier to make the film thickness uniform by the leveling process.

In this embodiment, since the leveling step S2 is performed at room temperature or under heating in the process of flowing from the printing line to the drying line, the leveling step S2 is preferably performed uniformly without increasing the number of steps. A thick film having a thickness is obtained. In particular, when heating is involved, the thickness of the thick film insulating paste 22 applied with a substantially uniform distribution in the printing region A is quickly uniformed with the softening of the resin component. The film thickness can be more easily obtained.

Next, another embodiment of the present invention will be described. In the following embodiments, portions common to the above-described embodiments are denoted by the same reference numerals, and description thereof is omitted.

FIG. 6 is a plan view illustrating the configuration of a main part of a screen plate 38 used in another embodiment. In the printing area A of the screen 28, for example, a diameter of 50 to 150 (μm)
A plurality of openings 40 having a substantially circular shape are provided so as to be substantially uniformly distributed over the entire surface. That is, the opening 40 is provided in an intermittent shape in any direction along the surface direction of the screen 28. In this embodiment, the aperture ratio in the print area A is, for example, about 20 to 50 (%).

When screen printing is performed on the front plate 10 as shown in FIG. 3 using the above-described plate making 38, the thick film insulating paste is placed at a position corresponding to the opening 40 on one surface 12 thereof. 22 is applied, and the paste film 34 is formed in a dot shape. Then, by performing the leveling step S2 in the same manner as in the above-described embodiment, the plurality of paste films 34 formed independently from each other are spread around and continuous with the adjacent ones, and the printing surface (one surface 12) is formed. 2) A thin paste film 36 having a uniform thickness is formed over the entire area corresponding to the upper print area A. That is, the opening 40 formed in the printing area A is not limited to a band-like one like the opening 32, and a similar effect can be obtained even if it is a dot (dot) -like one.

FIG. 7 is a view for explaining a main structure of a screen plate 42 according to still another embodiment. In the present embodiment, the opening 4 having a rectangular outer peripheral portion contour in the printing area A is used.
4, and a plurality of non-transmissive portions 46 are provided by leaving the photosensitive resin 30 in the form of dots (dots) in the opening 44 thereof. Non-transmissive part 46
Has a substantially circular shape with a diameter of, for example, about 50 to 150 (μm), and is substantially uniformly distributed in the print area A, and the aperture ratio in the print area A is 20 to 50 (%). It is about.
That is, in this embodiment, the opening 44 is provided so as to be intermittent in a cross section passing through the non-transmissive portion 46, but only one opening 44 is provided in the print area A. The entire opening 44 is located in the printing area A and is formed to have a slightly smaller size.

When the thick film insulating paste 22 is applied to the front plate 10 using the plate making 42 as described above, a perforated paste film 34 is formed. Then, when the leveling process is performed in the leveling step S2, the portion of the paste film 34 that forms the periphery of the hole flows toward the inside of the hole by edging and fills it, and the peripheral portion is A paste film 36 that spreads outward and has a uniform thickness over the entire printing area A is generated. The opening 44 is provided on the inner peripheral side of the print area A because the paste film 34 flows and spreads as described above, and then the paste film 36 is formed just in the area corresponding to the print area A. That's why. Thus, the paste film 3 that is entirely continuous from the beginning
Also in the case where the openings 44 are designed in a pattern such that the openings 4 are formed, the opening ratio is set to an appropriate value, so that the opening 44 is appropriately thin similarly to the case where the paste film 34 is formed in an island shape. The paste film 36 is formed, and the thin dielectric layer 16 can be formed.

While one embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be implemented in other embodiments.

For example, in an embodiment, the present invention
Although the case where the present invention is applied to the formation of the dielectric layer 16 of the type PDP has been described, the present invention is not limited to the case where a thick film anode substrate or a thick film The same applies to the case where a dielectric film or a conductor film is formed on a circuit board, an ozonizer substrate, or the like. Further, even if printing is performed on a relatively small area, by applying the present invention, the thickness of the screen 28 can be designed to be relatively thick, so that the plate making 20 having high durability can be configured.

In the embodiment, the aperture ratio is 20 to 8
An opening 32 is formed in the screen 20 so as to be about 0 (%),
Although the case where 40, 44, etc. are provided has been described, the aperture ratio is appropriately set according to the coating thickness determined by the thickness of the screen 20 used, the viscosity of the paste, and the like, and the required film thickness. You.

In the embodiment, the case where the openings 32 and the like are provided with a substantially uniform distribution has been described, but the distribution is appropriately determined according to the fluidity and viscosity of the thick film printing paste. And finally a paste film 3 having a uniform thickness.
6, the uniformity of the distribution of the openings 32 is not required.

Further, in the embodiment, the case where the present invention is applied to the plate making 20 or the like using the screen 28 made of stainless steel mesh has been described. However, the case where a screen made of resin mesh or a metal screen is used. The present invention can be similarly applied to this.

In the embodiment, when the dielectric layer 16 is formed on almost the entire surface 12 corresponding to the print area A without any gap, that is, the "predetermined range" in the claims is one. The case where the present invention is applied to the case of forming a so-called "solid thick film" is described. However, when the "predetermined range" is provided at a plurality of locations in the print area A, The present invention is similarly applied to a case where a thick film pattern is formed. In short, the present invention is similarly applied to the case where a plurality of mutually independent thick film patterns are formed on one surface 12 as long as the thick film is formed thinner than the value determined by the thickness of the screen 28. Is done.

In the embodiment, the case where the openings 32 and the like have a band shape or a circular shape has been described. However, the openings 32 and the like are formed so as to have an aperture ratio necessary for obtaining a desired film thickness. Any shape may be used as long as it is intermittent in a cross section along one direction in the opening region corresponding to the thick film pattern to be formed. For example,
A rectangular opening may be arranged in a point shape,
The shape may be a shape having an outline combining various curves, or may be a shape continuous in a spiral.

Although not specifically exemplified, the present invention can be embodied in variously modified forms without departing from the gist thereof.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a configuration of a main part of a front panel of a PDP having a dielectric layer formed by applying the present invention.

FIG. 2 is a process chart illustrating a method for forming a dielectric layer in FIG. 1;

FIG. 3 is a view for explaining a glass paste application step in FIG. 2;

FIG. 4 is a diagram illustrating a configuration of a screen plate used in the coating step of FIG.

5 (a) is a diagram showing a state immediately after the thick film paste is applied in the application step of FIG. 2, and FIG. 5 (b) is a view showing a state after the leveling step of FIG. 2 is performed.

FIG. 6 is a diagram illustrating a configuration of a screen plate used in another embodiment of the present invention.

FIG. 7 is a diagram illustrating a configuration of a screen plate used in still another embodiment of the present invention.

[Explanation of symbols]

 12: One surface (printed surface) 34: Paste film (after coating) 36: Paste film (after leveling)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) // B41M 1/12 B41M 1/12 5C058 F term (reference) 2H113 AA01 AA02 AA03 AA06 BA10 BB09 BC00 BC12 CA17 DA04 FA36 FA48 2H114 AB09 AB15 AB16 AB17 BA02 DA80 EA02 EA04 4D075 AC45 DA06 DB13 DC21 5C027 AA06 5C040 GD09 JA02 JA04 JA12 JA32 KB19 LA17 MA24 MA25 5C058 AA03 AA06 AA11 BA35

Claims (1)

[Claims] 1. A method for forming a thick film that covers a predetermined area without gaps on a surface to be printed using thick film screen printing, wherein a cross section in a predetermined one direction is formed in an opening area corresponding to the predetermined area of the screen. A printing step of applying a thick-film printing paste to the printing surface by using a screen plate provided with an opening so as to be intermittent, and a thick film applied through the opening within the predetermined range of the printing surface. By performing a leveling process on the printing paste, the thick-film printing paste intermittently following the shape of the opening is connected to each other by using the edges, and the predetermined range is completely covered from the thick-film printing paste. And a leveling step of generating a coating film having a substantially uniform thickness.