JP7822009B2 - Screen mask manufacturing method - Google Patents

Description

The present invention relates to a screen mask and a method for manufacturing a screen mask.

Screen printing is a printing method that uses a screen mask with a predetermined pattern of openings made of a resin composition on a mesh support material to form a desired printed object on the substrate. This screen printing method is used for a variety of printing processes, such as printing wiring, electrodes, and fluorescent materials, and is used in a variety of fields, including electronic components.

In recent years, the miniaturization and improved quality of electronic components has created a demand for higher precision screen masks.

For example, a screen mask comprises a mesh with holes that allow the coating material to pass through, and a mask film with pattern openings provided in the mesh. The pattern openings formed in the mask film have a shape that corresponds to, for example, the printing pattern, and a predetermined width. For example, after the emulsion that forms the mask film is applied to the mesh, the pattern openings are formed by an exposure process with a photomask placed over it.

JP 2013-169783 A

There is a demand for such screen masks and a method for manufacturing them that can improve printing accuracy.

A method for manufacturing a screen mask according to one embodiment includes a first layer forming step of forming a first emulsion layer by applying a first emulsion to a support material having holes that allow the coating material to pass therethrough; a first patterning step of exposing the first emulsion layer with a predetermined first exposure pattern; a second layer forming step of forming a second emulsion layer by applying a second emulsion to one side of the first emulsion layer in an overlapping manner; a second patterning step of exposing the first emulsion layer with a second exposure pattern that is different from the first exposure pattern after the first patterning step; and an etching process of removing uncured portions after the second patterning step, wherein the exposure is maskless exposure, the first exposure pattern is a pattern having uncured portions that form openings wider than the widths of the openings formed by the second exposure pattern, and the cured portions of the second exposure pattern are at least a part of the uncured portions in the first patterning step. and an area on the one side of at least a portion of the hardened portion in the first patterning step, and the second patterning step hardens an area including at least a portion of the first emulsion layer and at least a portion of the second emulsion layer from one side of the second emulsion layer, and the second patterning step hardens a portion of the unhardened portion of the first emulsion layer that is not hardened in the first patterning step that constitutes the inner wall of the opening and a portion of the second emulsion layer on one side of the hardened portion that has been hardened in the first patterning step that will become a protrusion at the edge of the opening, and the etching treatment removes the unhardened portions of the first emulsion and the second emulsion, thereby forming an opening in the first emulsion layer and the second emulsion layer, and forming a protrusion composed of a portion of the second emulsion layer at the edge of the opening on the surface on the one side.

In another embodiment of the method for manufacturing a screen mask, the second emulsion layer is softer than the first emulsion layer.

In another embodiment of the method for manufacturing a screen mask, the protrusions and the surface layer portions of the inner wall surfaces of the openings connected to the protrusions are made of the second emulsion layer.
In another embodiment of the method for manufacturing a screen mask, the opening is a linear slit opening that penetrates a mask film having the first emulsion layer and the second emulsion layer stacked on one side of the first emulsion layer in the thickness direction from the front side to the back side.

Embodiments of the present invention provide a screen mask and a method for manufacturing a screen mask that can improve printing accuracy.

FIG. 1 is an explanatory diagram of a screen printing apparatus according to a first embodiment. FIG. 2 is a perspective view of the screen mask according to the embodiment. FIG. FIG. 2 is an explanatory diagram showing a configuration of a part of the screen mask. 3A to 3C are explanatory views showing a method for manufacturing the screen mask. 10A and 10B are explanatory diagrams showing the shapes of pattern openings and printing shapes of the screen mask and Comparative Example 1. FIG. 2 is an explanatory diagram showing the relationship between the shape of the screen mask and the print shape. FIG. 2 is an explanatory diagram showing the relationship between the shape of the screen mask and the print shape. FIG. 10 is an explanatory diagram of a screen printing apparatus according to a second embodiment. FIG. 2 is an explanatory diagram showing a configuration of a part of the screen mask. 3A to 3C are explanatory views showing a method for manufacturing the screen mask. 3A and 3B are explanatory diagrams showing a printing method using the screen printing apparatus according to the embodiment. 10A and 10B are explanatory diagrams showing the shapes of pattern openings and printing shapes of the same screen mask and Comparative Example 2. FIG. 2 is an explanatory diagram showing the relationship between the shape of the screen mask and the print shape. 10A and 10B are explanatory diagrams showing the shape of a mask film of a screen mask according to another embodiment. 10A and 10B are explanatory diagrams showing the shape of a mask film of a screen mask according to another embodiment. 10A and 10B are explanatory diagrams showing the shape of a mask film of a screen mask according to another embodiment. 10A to 10C are explanatory diagrams showing the configuration and manufacturing method of a screen mask according to another embodiment.

[First embodiment]
A screen printing apparatus 10 and a screen mask 20 according to a first embodiment of the present invention will now be described with reference to Figures 1 to 8. Figure 1 is an explanatory diagram showing the screen printing apparatus 10 according to this embodiment. Figure 2 is a perspective view of the screen mask 20, and Figure 3 is a cross-sectional view thereof. Figure 4 is an explanatory diagram showing a portion of the configuration of the screen mask 20. Note that in each figure, the configuration is enlarged, reduced, or omitted as appropriate for ease of explanation. In the figures, arrows X, Y, and Z indicate three mutually orthogonal directions.

As shown in FIG. 1, the screen printing device 10 includes a screen mask 20, a holding member 12 that holds the print medium Ba facing the front surface (one side) 20a, which is the printing surface side of the screen mask 20, a squeegee 13 that is configured to be movable while abutting the back surface (other side) 20b, which is the opposite side to the printing surface side of the screen mask 20, a moving unit that moves the squeegee 13, and a support unit that supports the screen mask 20 facing the print medium Ba.

The screen printing device 10 forms various printing materials in a predetermined pattern on the surface of the printing medium Ba. For example, it is used in the manufacture of chip components (capacitors, chip resistors, inductors, thermistors, etc.), touch panels, liquid crystal display (LCD) substrate seals, LTCC (Low Temperature Co-fired ceramics) substrates, solar cell electrodes, and other electronic components.

As shown in Figures 1 and 2, the screen mask 20 comprises a frame 21, a mesh 22 serving as a support material stretched over the frame 21, and a mask film 23 formed on the mesh 22. The side of the screen mask 20 that faces the surface of the printing medium Ba during printing is referred to as the front surface 20a, and the opposite side, to which the coating material Pe is supplied, is referred to as the back surface 20b.

The frame 21 has two pairs of parallel sides and is configured in a frame shape with, for example, a rectangular opening of a desired size. The frame 21 supports the outer edge of the mesh 22, and the mesh 22 is stretched across the opening. In this embodiment, as an example, the Y-direction dimension of the opening of the frame 21 is 275 mm, and the X-direction dimension is 275 mm.

The frame 21 also functions as a frame for holding a predetermined amount of coating material Pe on the back side of the mask membrane 23. The frame 21 and mesh 22 are joined at the joints with, for example, a synthetic rubber or cyanoacrylate adhesive.

The mesh 22 is a woven fabric formed by weaving warp threads 22a and weft threads 22b, and has numerous holes 22c that allow the coating material Pe to pass through. The warp threads 22a and weft threads 22b are, for example, metal wires such as stainless steel, or fibers made of resin such as polyester. The warp threads 22a and weft threads 22b each extend obliquely with respect to, for example, the direction of movement of the squeegee 13 (first direction).

A mask film 23 with a predetermined pattern opening 23a is formed on this mesh 22. In other words, the mesh 22 holds the mask film 23 in the opening portion of the frame 21.

The mask film 23 is a layer made of a photocurable resin composition, such as PVA, PVAc, silicone resin, acrylic resin, or epoxy resin. For example, as shown in Figure 5, the mask film 23 has a two-layer structure consisting of a base layer 23b and a cover layer 23c. As an example, the cover layer 23c is made of a material that is more flexible than the base layer 23b.

The thickness of the mask film 23 is, for example, 10 μm to 100 μm.

The mask film 23 is formed on the mesh 22 and placed in the opening of the frame 21. A predetermined pattern opening 23a for printing is formed in the mask film 23 by exposure.

The minimum opening width of the pattern opening 23a, i.e., the width dimension of the opening at the narrowest part of the pattern opening 23a, is 30 μm or less. Here, as an example, the dimensions at the surface of the mask film 23, i.e., the surface 20a facing the printing medium Ba, are used as the reference.

The pattern openings 23a are line-shaped pattern holes. The pattern openings 23a form slits that penetrate the mask film 23 in the thickness direction (depth direction) and have a pattern corresponding to the printing pattern.

A protrusion 23d that protrudes toward the printing surface is formed on the edge (periphery) of the pattern opening 23a on the printing surface side. As shown in Figure 5, the protrusion 23d and the surface layer of the inner wall surface of the pattern opening 23a connected to the protrusion 23d of the mask film 23 are composed of a cover layer 23c.

As shown in FIG. 4, the protrusion 23d is set to satisfy all of the following formulas: 2 μm≦ΔTb≦2/3T (Formula 1)
10μm≦Wc≦100μm (Formula 2)
Tm≦T−ΔTb (Formula 3)
Here, T is the total thickness (including the thickness of the mesh and emulsion), ΔTb is the step thickness from the printing surface, Wc is the width of the step on one side of the pattern opening 23a, and Tm is the thickness of the mesh.

The mask film 23 forms a printed area where the photosensitive resin is not present in the pattern openings 23a and where the coating material Pe can pass through the holes in the mesh 22 from the back surface to the front surface. Areas of the mask film 23 other than the pattern openings 23a, where the holes in the mesh 22 are blocked with photosensitive resin, form non-printed areas that do not allow the ink used as the coating material Pe to pass through.

The mesh 22 on which the mask film 23 is formed is configured to be elastically deformable, for example, so that it bends and deforms when pressed by the squeegee 13 and returns to its original shape when the pressing force is released. With the coating material Pe held in the pattern openings 23a of the mask film 23, the mask film 23 moves toward and away from the printing medium Ba due to the elastic deformation of the mesh 22, thereby transferring the coating material Pe from the pattern openings 23a to the printing medium Ba.

The squeegee 13 is made of, for example, urethane rubber, silicone rubber, synthetic rubber, metal, plastic, or other material, and is formed, for example, in the shape of a thin plate. For example, the squeegee 13 is chamfered to reduce the thickness of its tip. The squeegee 13 is configured to be movable relative to the frame 21. For example, the squeegee 13 is configured to have a length that spans the entire length of the mask membrane 23 area in a direction perpendicular to the direction of movement. When the tip portion 13a of the squeegee 13 abuts against the back surface 20b of the screen mask 20 and is pressed against the front surface, it moves in the direction of movement along arrow A in Figure 1, pressing against the entire surface of the mask membrane 23 and forcing the coating material Pe to the front surface from the pattern openings 23a where it has been pre-filled.

The support unit supports the frame 21 parallel to the print medium Ba at a predetermined distance. The movement unit moves the squeegee 13 in a predetermined direction at a predetermined speed.

Next, a method for manufacturing the screen mask 20 according to this embodiment will be described with reference to FIG. 5. FIG. 5 is an explanatory diagram showing the method for manufacturing the screen mask 20. The method for manufacturing the screen mask 20 includes a first layer forming process, a first patterning process, a second layer forming process, a seasoning process, a second patterning process, and an etching process.

The first emulsion is, for example, a photocurable resin, such as a liquid containing polyvinyl alcohol (PVA), polyvinyl acetate (PVAc), silicone resin, acrylic resin, epoxy resin, etc.

In the first layer formation process, the first emulsion Pm1 is applied to a support material with holes that allow the coating material to pass through, forming the first emulsion layer. Specifically, first, the mesh 22 is attached to the frame 21 so that it is approximately flat, and then, as shown in ST1, the first emulsion Pm1 is applied to the mesh 22, forming a flat base layer 23b on the mesh 22. Because the thickness varies depending on the number of applications, multiple applications may be required. Furthermore, the film thickness may be measured after drying, and additional applications may be made if necessary. In this embodiment, the thickness of the emulsion Pm1 is set so that the emulsion thickness of the first emulsion layer is approximately 5 to 20 μm after drying.

Next, a first patterning process is performed, in which the first emulsion layer is exposed to a predetermined first exposure pattern. For example, as shown in ST2, the first maskless exposure process is performed using a maskless exposure machine that does not use a photomask. Specifically, the surface side of the base layer 23b is placed in the predetermined exposure pattern area facing a light source such as an ultraviolet lamp or ultraviolet LED, and light is irradiated from the light source to illuminate the emulsion surface. The first exposed portions of the base layer 23b that are exposed by the first exposure process become first emulsion hardened portions (first photo-crosslinked portions) Pa1 that harden with ultraviolet light. Meanwhile, the first unexposed portions of the base layer 23b that are the portions excluding the first exposed portions become unhardened portions Pb1 where the emulsion does not harden. The first unhardened portions Pb1 (first unexposed portions) constitute first removal targets that will be removed in a later process to form the base opening.

Here, the first exposure pattern is a pattern that forms a base opening that is wider than the pattern width of the second exposure pattern, taking into account misalignment with the second pattern that will be layered in a later process. The base layer 23b is patterned in this way, and is later removed in an etching process to form the first removal target portion that will form the base opening.

Next, as shown in ST3, a coating process is performed in which the second emulsion Pm2 is applied onto the base layer 23b, forming a cover layer 23c from the second emulsion Pm2 on the printing surface side of the base layer 23b. Since the thickness varies depending on the number of applications, multiple applications may be required. Additionally, the film thickness may be measured after drying, and additional applications may be required if necessary. In this embodiment, the thickness of the emulsion Pm2 is set so that the milk thickness of the cover layer 23c after drying is approximately 2 to 50 μm. The frame is then left to stand for approximately three hours under the conditions required for maskless exposure processing, thereby carrying out a seasoning process to bring the frame temperature to the same level as during the first maskless exposure processing.

Next, a second patterning process is performed, in which the emulsion Pm2 is exposed to a second exposure pattern different from the first exposure pattern. That is, as shown in ST4, a second maskless exposure process is performed using a maskless exposure machine that does not use a photomask. Specifically, in a predetermined second exposure pattern area, the surface side of emulsion Pm2 is placed facing a light source such as an ultraviolet lamp or ultraviolet LED, and light is irradiated from the light source to illuminate the surface of emulsion Pm2. Through the second exposure process, the ultraviolet-irradiated portions of emulsion Pm2 corresponding to the exposure pattern area are cured by the ultraviolet light. That is, the second-exposed portions of cover layer 23c that are exposed by the second exposure process form second-emulsion-cured portions (second-photocrosslinked portions) Pa2 that are cured by the ultraviolet light. A portion of second-emulsion-cured portions Pa2 constitutes protrusions 23d, and another portion constitutes the inner walls of pattern openings 23a. Meanwhile, the second-unexposed portions of cover layer 23c, excluding the second-exposed portions, become second-uncured portions Pb2, in which the emulsion does not harden. The second uncured portion Pb2 includes a second removal target portion that will be removed in a later process to form the pattern opening 23a, which includes the base opening.

Both the first and second exposure processes involve irradiating light from the printing surface side. The second exposure process involves exposing from the same direction as the first exposure process, but with a pattern that targets a narrower area than the first exposure process, thereby hardening a predetermined range. In the second patterning process, an area including at least a portion of the first emulsion layer and at least a portion of the second emulsion layer is exposed by exposing with a second exposure pattern that is different from the first exposure pattern. That is, among the first non-exposed areas of the first emulsion layer that were not hardened in the first exposure process, the areas that form the inner walls of the pattern openings 23a and the part of the second emulsion layer that is on one side of the first exposed areas that were hardened in the first exposure process and that forms the protrusions 23d on the edges of the pattern openings 23a are hardened by the second exposure process.

Then, as an etching process, at least one side of the mask film is washed away with water or a solvent. This process forms a pattern opening 23a that penetrates from the front side to the back side in the thickness direction, washing away the unhardened portions Pb1 and Pb2 of the emulsions Pm1 and Pm2, and also forms a protrusion 23d that forms a step at the edge of the pattern opening 23a.

Next, a method for producing a printed product by a screen printing method using the screen printing apparatus 10 according to this embodiment will be described with reference to FIG. 1. First, the front side of the screen mask 20 is placed facing the surface of the printing medium Ba held by the holding member 12.

Then, as shown by the two-dot chain line in Figure 1, a highly viscous paste-like coating material Pe is supplied from the back side of the screen mask 20, i.e., the side opposite the printing medium Ba, and the coating material Pe is filled into the pattern openings 23a.

Next, the squeegee 13 is placed on the back surface 20b of the screen mask 20, i.e., the surface opposite the printing surface. At this time, for example, the squeegee 13 is placed at a predetermined angle relative to the front surface of the printing medium Ba. The squeegee 13 is then moved at a predetermined speed while pressing the mesh 22 and the back surface of the mask film 23 toward the printing medium Ba with a predetermined printing pressure. The squeegee 13 presses against the mask film 23 over the entire back surface of the mask film 23. The pressure of the squeegee 13 deforms the mask film 23 so that the pressed portion is displaced toward the front surface and comes into contact with the printing medium Ba. The coating material Pe that the squeegee 13 has passed through is pushed out toward the printing medium Ba through the pattern openings 23a.

After the squeegee 13 has passed, the mask film 23 and mesh 22 deform and return to their original shape, separating from the print medium Ba. Some of the coating material Pe is transferred and remains on the print medium Ba, printing a pattern on the print medium Ba and completing the print. At this time, a portion of the back side of the coating material Pe remains on the mask film 23 side. The coating material Pe can be made of various materials, including metal and resin, and a variety of materials are used depending on the type of object to be printed, such as electronic components or displays.

The screen mask 20, screen printing apparatus 10, and screen printing method configured as described above enable high-precision printing.

Figure 6 is an explanatory diagram showing the shape of the pattern openings and the printing shape for the screen mask 20 and a comparative screen mask 20A. As a comparative example, the screen mask 20A shown does not have protrusions 23d and has a flat surface on the printing side (P side).

As shown in Figure 6, the screen mask 20, which has protrusions 23d on the edges of the openings on the printing surface side, can reduce bleeding of the printed shape compared to the configuration of Comparative Example 1, enabling highly accurate printing.

Furthermore, according to the above embodiment, the screen mask 20 is configured to satisfy 2 μm≦ΔTb≦2/3T (Equation 1), thereby ensuring the desired printing pressure at the edge using a simple manufacturing method.

For example, as shown in Figure 7, if 2 μm > ΔTb, the height of the protrusions 23d will be insufficient to achieve the desired printing pressure, and the bleeding reduction effect will not be achieved. On the other hand, if ΔTb > 2/3T, the strength will be insufficient, and durability during printing will decrease.

Furthermore, by configuring the screen mask 20 to satisfy the relationship 10 μm≦Wc≦100 μm (Equation 2), the mask film is less likely to be damaged and the desired printing pressure can be ensured at the edges. That is, as shown in Figure 8, when 10 μm > Wc, the protrusions 23d on the printing surface are easily damaged, while when Wc > 100 μm, the pressure applied to the protrusions 23d is relatively small and the required printing pressure cannot be obtained.

Furthermore, according to this embodiment, both the first exposure process and the second exposure process are exposure processes in which light is irradiated from the printing surface side, and by varying conditions such as the exposure amount and exposure time, it is possible to easily form pattern openings having protrusions 23d.

Second Embodiment
A screen printing apparatus 10 and a screen mask 120 according to a second embodiment of the present invention will be described below with reference to Fig. 1 and Figs. 9 to 11. Fig. 9 is an explanatory diagram of the screen printing apparatus according to this embodiment, and Fig. 10 is an explanatory diagram showing the configuration of a portion of the screen mask 120. Fig. 11 is an explanatory diagram showing a method for manufacturing the screen mask 120. Note that the screen mask 120 according to this embodiment does not have protrusions 23d, and has steps on the inner walls of the pattern openings 23a. Other configurations are similar to those of the screen mask 20 according to the first embodiment, so a description of the common parts will be omitted.

As shown in FIG. 9, the screen printing device 10 includes a screen mask 120, a holding member 12 that holds the printing medium Ba facing the front surface (one side) 20a, which is the printing surface side of the screen mask 120, a squeegee 13 that is configured to be movable while abutting the back surface (other side) 20b, which is the opposite side to the printing surface side of the screen mask 120, a moving unit that moves the squeegee 13, and a support unit that supports the screen mask 120 facing the printing medium Ba.

As shown in FIG. 9, the screen mask 120 comprises a frame 21, a mesh 22 serving as a support material stretched over the frame 21, and a mask film 123 formed on the mesh 22. The side of the screen mask 120 that faces the surface of the printing medium Ba during printing is called the front surface 120a, and the opposite side, to which the coating material Pe is supplied, is called the back surface 120b.

The mask film 123 is a layer made of a photocurable resin composition, such as PVA, PVAc, silicone resin, acrylic resin, or epoxy resin.

The thickness of the mask film 123 is, for example, 10 μm to 100 μm.

The mask film 123 is formed on the mesh 22 and placed in the opening of the frame 21. A predetermined pattern opening 123a for printing is formed in the mask film 123 by exposure.

The minimum opening width of the pattern opening 123a, i.e., the width dimension of the opening at the narrowest part of the pattern opening 123a, is 30 μm or less. Here, as an example, the dimensions at the surface of the mask film 123, i.e., the surface 20a facing the printing medium Ba, are used as the reference.

The pattern openings 123a are linear pattern holes. The pattern openings 123a form slits that penetrate the mask film 123 in the depth direction and have a pattern corresponding to the printing pattern.

The pattern opening 123a is configured so that the opening edge on the supply side, opposite the printing surface, is wider than the opening edge on the printing surface side, which is one side in the direction of discharging the coating material. Furthermore, the inner wall surface of the pattern opening 123a is configured asymmetrically, with the opening edge wider on one side in the first direction, which is the direction of squeegee movement, than on the other side. The printing surface side of the pattern opening 123a is configured flat. In other words, no protrusions 23d are formed.

As an example, the inner wall of the pattern opening 123a has a protruding guide portion 123e that protrudes into the opening midway in the depth direction, on the rear side in the direction of squeegee movement. This guide portion 123e forms a step 123f in the side wall of the pattern opening 123a. The pattern opening 123a has a wide portion on the squeegee side and a narrow portion on the printing surface side, which are connected via an inflection portion created by the step 123f. The wide portion and narrow portion are continuous, forming a slit that penetrates the mask film 23 in the depth direction in a pattern corresponding to the printing pattern.

The shape of the pattern opening 123a is as shown in FIG.
ΔW≦ΔT≦2/3T (Formula 4)
The configuration satisfies ΔW=(Wb−Wa)≦40 μm (Equation 5).
Here, T is the total thickness (including the thickness of the mesh and emulsion), ΔT is the step thickness from the printing surface, and ΔW is the step width on one side of the pattern opening 123a. Wb is the width dimension of the large width portion, and Wa is the width dimension of the small width portion. The other configurations are the same as those of the first embodiment.

Next, a method for manufacturing the screen mask 120 according to this embodiment will be described with reference to FIG. 11. FIG. 11 is an explanatory diagram showing the method for manufacturing the screen mask 120. The method for manufacturing the screen mask 120 includes a layer formation process, a first patterning process, a second patterning process, and an etching process.

In the layer formation process, an emulsion layer is formed by applying an emulsion to a support material with pores that allow the coating material to pass through. The emulsion is, for example, a photocurable resin, such as a liquid containing polyvinyl alcohol (PVA), polyvinyl acetate (PVAc), silicone resin, acrylic resin, or epoxy resin.

First, the mesh 22 is attached to the frame 21 so that it is approximately flat, and then, as shown in ST1, a coating process is performed in which emulsion Pm1 is applied onto the mesh 22.

Next, a first patterning process is performed, in which the emulsion layer is exposed to a predetermined first exposure pattern. For example, as shown in ST12, the first maskless exposure process is performed using a maskless exposure machine that does not use a photomask. Specifically, in the predetermined exposure pattern area, the front side of the emulsion layer is placed facing a light source such as an ultraviolet lamp or ultraviolet LED, and light is irradiated from the light source to illuminate the surface of the emulsion. The first exposure process hardens the ultraviolet-irradiated portions of the emulsion corresponding to the exposure pattern area. The first exposed portions, which are the portions exposed by the first exposure process, form first emulsion hardened portions (first photo-crosslinked portions) Pa1 that harden with ultraviolet light. The first unexposed portions, which are the portions excluding the first exposed portions, become first unhardened portions Pb1 in which the emulsion does not harden. The first unhardened portions Pb1 constitute first removal targets that form part of the back side of the pattern opening 123a when removed in a later process.

Next, as shown in ST13, a second maskless exposure process is performed using a maskless exposure machine that does not use a photomask. Specifically, in a predetermined second exposure pattern area, the front side of the emulsion Pm1 is placed facing an illumination source such as an ultraviolet lamp or ultraviolet LED, and light is irradiated from the illumination source to illuminate the surface of the emulsion Pm1. By the second exposure process, the portions of the emulsion Pm1 that are irradiated with ultraviolet light corresponding to the portions of the exposure pattern area are cured by the ultraviolet light.
The second exposed portion, which is the portion exposed by the second exposure process, forms a second emulsion hardened portion (second photo-crosslinked portion) Pa2 that is hardened by ultraviolet light. The second unexposed portion, which is the portion excluding the second exposed portion, becomes a second unhardened portion Pb2 where the emulsion does not harden. The second unhardened portion Pb2 will be removed in a later process to form a second removal target portion that forms part of the printing surface side of the pattern opening 123a.

Both the first and second exposure processes involve irradiating light from the printing surface side, and the second exposure process involves exposing from the same direction as the first exposure process, using a pattern that targets a wider area than the first exposure process, and with an output that has a deeper exposure depth, thereby hardening a specified range.

Then, in an etching process, the uncured portions Pb1 and Pb2 of the emulsion Pm1 are washed away with water or a solvent. This process forms a pattern opening 123a in the emulsion Pm1 that penetrates from the front side to the back side in the thickness direction and has a guide portion 123e.

Next, a method for producing a printed product by a screen printing method using the screen printing apparatus 10 according to this embodiment will be described with reference to Figure 12. First, the front side of the screen mask 20 is placed facing the surface of the printing medium Ba held by the holding member 12.

Then, as shown in FIG. 12, a highly viscous paste-like coating material Pe is supplied from the back side of the screen mask 20, i.e., the side opposite the printing medium Ba, and the coating material Pe is filled into the pattern openings 23a.

Next, the squeegee 13 is placed on the back surface 20b of the screen mask 20, i.e., the surface opposite the printing surface. At this time, for example, the squeegee 13 is placed at a predetermined angle relative to the front surface of the printing medium Ba. The squeegee 13 is then moved at a predetermined speed while pressing the mesh 22 and the back surface of the mask film 23 toward the printing medium Ba with a predetermined printing pressure. The squeegee 13 presses against the mask film 23 over the entire back surface of the mask film 23. The pressure of the squeegee 13 deforms the mask film 23 so that the pressed portion is displaced toward the front surface and comes into contact with the printing medium Ba. The coating material Pe that the squeegee 13 has passed through is pushed out toward the printing medium Ba through the pattern openings 23a.

After the squeegee 13 has passed, the mask film 23 and mesh 22 deform and return to their original shape, separating from the print medium Ba. Some of the coating material Pe is transferred and remains on the print medium Ba, printing a pattern on the print medium Ba and completing the print. At this time, a portion of the back side of the coating material Pe remains on the mask film 23 side. The coating material Pe can be made of various materials, including metal and resin, and a variety of materials are used depending on the type of object to be printed, such as electronic components or displays.

With the screen mask 120, screen printing apparatus 10, and screen printing method configured as described above, the pattern openings 123a are configured so that their rearward portions are larger toward the supply side than their forward portions in the direction of squeegee movement. As shown in FIG. 12, when the squeegee 13 is moved to supply the coating material, the coating material is guided from the supply side toward the printing surface, ensuring sufficient discharge pressure and enabling high-precision printing. For example, FIG. 13 is an explanatory diagram showing the shapes of the screen mask 120 according to this embodiment and a screen mask 120A according to Comparative Example 2, and the effect of the discharge pressure. Comparative Example 2 shows a symmetrical screen mask 120A with guide portions on both the front and rear sides in the direction of squeegee movement.

As shown in Figure 13, the screen mask 120 according to this embodiment can prevent pressure from dispersing and escaping in the direction of squeegee movement, and can ensure discharge pressure in the discharge direction, compared to the configuration of screen mask 120A (Comparative Example 2), which has guide sections formed on the side walls on both the front and rear of the opening in the direction of squeegee movement that are wider on the supply side than on the discharge side. This ensures the discharge volume and discharge pressure, enabling high-precision printing.

Furthermore, the screen mask 120 according to the above embodiment satisfies the following formula: ΔW≦ΔT≦2/3T (Formula 4)
By satisfying the above, deformation at the edge can be prevented and a desired printing pressure can be ensured.

That is, for example, as shown in Figure 14, if ΔW > ΔT, the mask membrane 23 is likely to deform and the print shape is likely to be distorted. On the other hand, if ΔT > 2/3T, the effect of increasing the ejection pressure is not sufficiently achieved.

Furthermore, according to this embodiment, both the first exposure process and the second exposure process are exposure processes in which light is irradiated from the printing surface side, and by varying conditions such as the exposure amount and exposure time, it is possible to easily form pattern openings 123a having protruding guide portions 123e.

The present invention is not limited to the above-described embodiments, and components can be modified and embodied in practice without departing from the spirit of the invention.

For example, in the first embodiment described above, the pattern openings 23a have a constant opening width, but this is not limited to this. For example, in another embodiment, the pattern openings 23a may be tapered so that the width on the printing surface side is narrower, as in the screen mask 220 shown in Figure 15.

In another embodiment, the screen mask may have a step so that the printing surface side is narrower, as in the screen mask 320 shown in Figure 16.

In yet another embodiment, as shown in Figure 16, the screen mask 420 may have an asymmetrical step shape with a narrower step on the printing surface side, on the rear side in the direction of squeegee movement. Alternatively, the mask may have an inclined surface rather than a step. For example, only the rear side in the direction of squeegee movement may have an inclined surface with a narrower printing surface, or if both sides are inclined surfaces, the rear side in the direction of squeegee movement may have an inclined surface with a larger inclination angle than the front side in the direction of movement.

Furthermore, in the second embodiment, a configuration having one step 123f is exemplified, but the number of steps is not limited to one. For example, as another embodiment, a configuration having two or more steps may be used as shown in Figure 17. In this case, it is preferable to satisfy Equations 6, 7, 8, 9, and 10.
ΔW≦ΔT≦2/3T (Formula 6)
ΔW = (Wb - Wa) ≦ 40 μm (Equation 7)
ΔW _n <ΔW (Formula 8)
ΔW _n ≦ΔT _n ≦2/3T (Formula 9)
ΔW _n <ΔW (Formula 10)
Here, T is the total thickness (including the thickness of the mesh and emulsion), ΔT is the step thickness from the printing surface, and ΔW is the step width on one side of the pattern opening 523a. Also, n may be plural.

Furthermore, while the above embodiment illustrates a configuration in which protrusions are only partially formed, this is not limiting. For example, as another embodiment, a method for manufacturing a screen mask 620 shown in FIG. 18 includes a first layer formation process, a first patterning process, a second layer formation process, a seasoning process, a second patterning process, and an etching process.

In the first layer formation process, a first emulsion Pm1 is applied to a support material having holes that allow the coating material to pass through, to form a first emulsion layer (ST21).

Next, a first patterning process is performed, in which the first emulsion layer is exposed to a predetermined first exposure pattern. For example, as shown in ST22, the first maskless exposure process is performed using a maskless exposure machine that does not use a photomask. Specifically, the surface side of the base layer 623b is placed in the predetermined exposure pattern area facing a light source such as an ultraviolet lamp or ultraviolet LED, and light is irradiated from the light source to illuminate the emulsion surface. The first exposed portions of the base layer 623b that are exposed by the first exposure process become first emulsion hardened portions (first photo-crosslinked portions) Pa1 that harden with ultraviolet light. Meanwhile, the first unexposed portions of the base layer 623b that are not the first exposed portions become unhardened portions Pb1 where the emulsion does not harden. The first unhardened portions Pb1 (first unexposed portions) constitute first removal targets that will be removed in a later process to form the base opening.

Here, unlike the first exposure pattern and the second exposure pattern, in this embodiment the second exposure area overlaps with a portion of the first exposure area.

Next, as shown in ST23, a coating process is performed in which the second emulsion Pm2 is applied onto the base layer 623b, thereby forming a cover layer 623c from the second emulsion Pm2 on the printing surface side of the base layer 623b. Then, a seasoning process is performed in which the frame temperature is brought to the same level as during the first maskless exposure process by leaving it to stand for approximately three hours under the conditions required for the maskless exposure process.

Next, a second patterning process is performed, in which the emulsion Pm2 is exposed to a second exposure pattern different from the first exposure pattern. That is, as shown in ST24, a second maskless exposure process is performed using a maskless exposure machine that does not use a photomask. Specifically, in a predetermined second exposure pattern area, the surface side of emulsion Pm2 is placed facing a light source such as an ultraviolet lamp or ultraviolet LED, and light is irradiated from the light source to illuminate the surface of emulsion Pm2. Through the second exposure process, the portions of emulsion Pm2 irradiated with ultraviolet light corresponding to the exposure pattern area are cured by the ultraviolet light. That is, the second exposed portions of cover layer 23c that are exposed by the second exposure process form second emulsion cured portions (second photo-crosslinked portions) Pa2 that are cured by the ultraviolet light. A portion of second emulsion cured portion Pa2 forms protrusion portion 623d, and another portion forms the inner wall of pattern opening 23a. Meanwhile, the second unexposed portions of cover layer 23c excluding the second exposed portions become second uncured portions Pb2, in which the emulsion does not harden. The second uncured portion Pb2 includes a second removal target portion that will be removed in a later process to form the pattern opening 23a, which includes the base opening.

Both the first and second exposure processes involve irradiating light from the printing surface side. The second exposure process hardens a predetermined area by exposing from the same direction as the first exposure process. In the second patterning process, an area including at least a portion of the first emulsion layer and at least a portion of the second emulsion layer is exposed by exposing with a second exposure pattern different from the first exposure pattern. That is, among the first non-exposed portions of the first emulsion layer that were not hardened in the first exposure process, the second exposure process hardens the portions that form the inner walls of the pattern openings 623a and the portions of the second emulsion layer that are on one side of the first exposed portions that were hardened in the first exposure process and form the protrusions 623d on the edges of the pattern openings 623a. Note that in this embodiment, portions of the first exposed portions do not overlap with the second exposed portions, and there are portions on the surface side of the base layer 623b where the cover layer 623c is not formed.

Then, as shown in ST25, an etching process is performed in which at least one side of the mask film is washed away with water or a solvent. This process forms a pattern opening 623a that penetrates from the front side to the back side in the thickness direction, washing away the uncured portions Pb1 and Pb2 of the emulsions Pm1 and Pm2, and the portion where the first exposed portion and the second exposed portion overlap becomes a protrusion 623d, forming a step on the surface.

As an example, the screen mask 620 shown in Figure 18 has pattern openings 23a formed therein, and a step formed on one surface. That is, on one surface, a convex portion that becomes protrusion 623d protruding to one side is formed in the second exposed portion of the second exposure process, and a recess 623g is formed in the portion where cover layer 623c is not formed, corresponding to the second non-exposed portion. The recess 623g serves as a relief portion that retreats to the side opposite the ejection direction, and makes it possible to avoid interference with foreign matter or protrusions, for example, if there are foreign matter, protrusions, or steps such as alignment marks on the side of the member facing the screen mask 620, such as the printing medium, during printing.

This screen mask and method for manufacturing the screen mask make it possible to form steps with convex or concave portions in any desired location with high precision. For example, if there are foreign objects, protrusions, or steps such as alignment marks on the opposing surface of the screen mask, it is possible to form concave portions in those areas with high precision as escape areas that retreat to the opposite side of the ejection direction, or to form convex portions with high precision on the edges of the openings, thereby ensuring the necessary printing pressure in the required areas. Therefore, a screen mask 620 with high printing precision can be provided.

In each of the above embodiments, when the first emulsion and the second emulsion are used, the first emulsion and the second emulsion may be made of different materials or may be made of the same material.
In the above embodiment, the mesh 22 is attached to the frame 21 with the adhesive 24, and the mask film 23 is formed over the entire opening of the frame 21. However, the present invention is not limited to this. For example, a so-called combination type mesh may be used, and the mask film 23 may be formed only over a portion of the central part of the mesh 22.

In addition, the components illustrated in the above embodiments may be deleted, or the shape, structure, material, etc. of each component may be changed. Various inventions can be created by appropriately combining the multiple components disclosed in the above embodiments. By adjusting the dimensional ratio of the material, the difference in the lengthwise and widthwise elongation can be reduced, thereby improving printing accuracy.
The following is a description equivalent to the invention described in the claims of the original application of this application. (1)
a first layer forming step of forming a first emulsion layer by applying a first emulsion to a support material having holes that allow the coating material to pass through;
a first patterning step of exposing the first emulsion layer with a predetermined first exposure pattern;
a second layer forming step of overcoating a second emulsion on the first emulsion layer to form a second emulsion layer;
a second patterning step of exposing the substrate with a second exposure pattern different from the first exposure pattern;
and forming an opening in the first emulsion layer and the second emulsion layer by etching, and forming a step on one surface.
(2)
The second patterning step includes exposing an area including at least a part of the first emulsion layer and at least a part of the second emulsion layer from one side of the second emulsion layer, and
The method for manufacturing a screen mask described in (1), wherein the exposed portion of the second exposure pattern includes at least a portion of the non-exposed portion in the first patterning process and an area on one side of at least a portion of the exposed portion in the first patterning process.
(3)
The method for manufacturing a screen mask according to (1), wherein the etching process forms an opening in the first emulsion layer and the second emulsion layer, and also forms a step on the surface on one side of the edge portion of the opening.
(4)
The method for manufacturing a screen mask according to any one of (1) to (3), wherein the exposure is maskless exposure.
(5)
The method for manufacturing a screen mask according to any one of (1) to (4), wherein the second emulsion layer is softer than the first emulsion layer.
(6)
a support material having holes that allow the coating material to pass through;
a mask film formed on the support material, the mask film having a step portion or inclined surface in which the opening edge on the supply side opposite the printing surface is wider than the opening edge on the printing surface side, which is one side in the discharge direction of the coating material, and the mask film having a protrusion at the opening edge on the printing surface side that protrudes toward the printing surface side.
(7)
a support material having holes that allow the coating material to pass through;
a mask membrane that is provided on the support material and has a pattern opening formed therein, the pattern opening having a wider opening edge on the supply side opposite the printing surface, which is one side in the direction of dispensing the coating material, than on the printing surface side, and the inner wall surface of the pattern opening is asymmetrically configured such that the opening edge is wider on one side in a predetermined first direction than on the other side.
(8)
The screen mask according to (7), wherein the mask film is expanded toward the supply side at a rear end in the moving direction of the squeegee more than at a front end.
(9)
The screen mask according to (7) or (8), wherein the inner walls of the pattern openings of the mask film have inclined surfaces.
(10)
The screen mask according to (7) or (8), wherein the inner wall of the pattern opening of the mask film has a step at a midpoint.

10...screen printing apparatus, 12...holding member, 13...squeegee, 13a...tip portion, 20, 20A, 120, 220, 320, 420...screen mask, 20a...surface, 20b...back surface, 21...frame, 22...mesh, 22a...warp thread, 22b...weft thread, 22c...hole portion, 23...mask film, 23a...pattern opening, 23b...base layer, 23c...cover layer, 23d...protrusion portion, 24...adhesive, 120b...back surface, 123...mask film, 123a...pattern opening, 123e...guide portion, 123f...step, Pa1...first emulsion hardened portion, Pa2...second emulsion hardened portion, Pb1...first unhardened portion, Pb2...second unhardened portion, Pm1...first emulsion, Pm2...second emulsion.

Claims (4)

a first layer forming step of forming a first emulsion layer by applying a first emulsion to a support material having holes that allow the coating material to pass through;
a first patterning step of exposing the first emulsion layer with a predetermined first exposure pattern;
a second layer forming step of overcoating a second emulsion on one side of the first emulsion layer to form a second emulsion layer;
a second patterning step of exposing the substrate with a second exposure pattern different from the first exposure pattern, performed after the first patterning step;
an etching process for removing an uncured portion after the second patterning process;
the exposure is a maskless exposure,
the first exposure pattern is a pattern having an uncured portion that forms an opening wider than the width of the opening formed by the second exposure pattern,
the cured portion of the second exposure pattern includes at least a portion of the uncured portion in the first patterning step and an area on the one side of at least a portion of the cured portion in the first patterning step;
the second patterning step hardens a region including at least a part of the first emulsion layer and at least a part of the second emulsion layer from one side of the second emulsion layer, and the second patterning step hardens a portion of the unhardened portion of the first emulsion layer that is not hardened in the first patterning step, which constitutes an inner wall of the opening, and a portion of the second emulsion layer on one side of the hardened portion that is hardened in the first patterning step, which will become a protrusion at the edge of the opening;
in the etching treatment, unhardened portions of the first emulsion and the second emulsion are removed to form openings in the first emulsion layer and the second emulsion layer;
forming a protrusion formed of a part of the second emulsion layer on the edge of the opening on the surface on one side;
A method for manufacturing a screen mask. The method for manufacturing a screen mask according to claim 1, wherein the second emulsion layer is softer than the first emulsion layer. The method for manufacturing a screen mask according to claim 1, wherein the protrusions and the surface layer of the inner wall surface of the opening connected to the protrusions are composed of the second emulsion layer. 2. The method for manufacturing a screen mask according to claim 1, wherein the opening is a linear slit opening that penetrates a mask film comprising the first emulsion layer and the second emulsion layer stacked on one side of the first emulsion layer from one side to the other in the thickness direction.