Screen printing mask manufacturing method

Abstract

To provide a manufacturing method of a screen printing mask which can inhibit increase of a price even if a printing pattern becomes finer.SOLUTION: First, a first resist 31 is formed at a base material 30. Next, mesh-like exposure is performed to the first resist 31 by using a glass dry plate 32 and exposure is performed according to the pattern by a direct writing machine. Next, the first resist 31 is developed to form a first plating layer 10. Then, a second resist 33 is formed so as to cover the first plating layer 10. Next, exposure is performed to the second resist 33 according to the pattern by the direct writing machine. Subsequently, after the second resist 33 is developed, the second plating layer 20 is formed and the second resist 33 is removed.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a method for making a screen printing mask. [Background technology]

[0002] A screen printing plate is described in Patent Document 1. The screen printing plate described in Patent Document 1 uses a stainless steel mesh. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6603837 Summary of the Invention [Problem to be solved by the invention]

[0004] The larger the mesh number of a stainless steel mesh, the smaller the mesh size. For finer printing patterns, a stainless steel mesh with a larger mesh number must be used. However, stainless steel mesh with a larger mesh number is expensive, which means the screen printing mask is also expensive.

[0005] The present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to provide a method for manufacturing a screen printing mask that can suppress an increase in price even when the printing pattern becomes finer. [Means for solving the problem]

[0006] The method for manufacturing a screen printing mask according to the present disclosure is a method for manufacturing a screen printing mask for printing a conductive paste in a specific pattern on a substrate. This manufacturing method includes the following steps: a first step of forming a layer of a first resist on a base material; a second step of performing a mesh-like exposure on the first resist using a glass dry plate after the first step; a third step of performing a pattern-based exposure on the first resist using a direct imaging machine after the first step; a fourth step of developing the first resist after the second and third steps; a fifth step of forming a first plating layer by plating the base material after the fourth step; a sixth step of forming a second resist to cover the first plating layer after the fifth step; a seventh step of performing a pattern-based exposure on the second resist using the direct imaging machine after the sixth step; an eighth step of developing the second resist after the seventh step; a ninth step of forming a second plating layer by plating the first plating layer after the eighth step; and a tenth step of removing the second resist after the ninth step. [Effects of the Invention]

[0007] The method for manufacturing a screen printing plate according to the present disclosure can prevent price increases even when the printing pattern becomes finer. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of a screen printing plate. [Figure 2] FIG. 2 is a diagram showing a cross section of the screen printing plate shown in FIG. [Figure 3] FIG. 3 is a view of the screen printing mask as seen from the direction A shown in FIG. 2. [Figure 4] FIG. 4 is a view showing a cross section BB of FIG. 3. [Figure 5] 3 is a flowchart showing an example of a method for manufacturing the screen printing mask according to the first embodiment. [Figure 6] 10A to 10C are diagrams for explaining a method for manufacturing a screen printing mask. [Figure 7] 10A to 10C are diagrams for explaining a method for manufacturing a screen printing mask. [Figure 8] 10A to 10C are diagrams for explaining a method for manufacturing a screen printing mask. [Figure 9] This is a view of the glass dry plate as seen from the direction C shown in FIG. 6(c). [Figure 10] FIG. 7(b) is a view of the first resist as seen from the direction E shown in FIG. 7(a). [Figure 11] 1 shows a micrograph of a screen printing mask actually manufactured by the method shown in the first embodiment. [Figure 12] 1 shows a micrograph of a screen printing mask actually manufactured by the method shown in the first embodiment. [Figure 13] 1 shows a micrograph of a screen printing mask actually manufactured by the method shown in the first embodiment. [Figure 14] 1 shows a micrograph of a screen printing mask actually manufactured by the method shown in the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] The following detailed description will be given with reference to the drawings. Duplicate descriptions will be simplified or omitted as appropriate. In each drawing, the same reference numerals indicate the same or corresponding parts.

[0010] Embodiment 1 FIG. 1 is a diagram showing an example of a screen printing plate 1. FIG. 2 is a diagram showing a cross section of the screen printing plate 1 shown in FIG. 1. The screen printing plate 1 comprises a screen printing mask 2, a gauze 3, and a frame 4. The screen printing mask 2 is attached to the frame 4 via the gauze 3. The gauze 3 is arranged around the screen printing mask 2. Tension is applied to the screen printing mask 2 by the gauze 3.

[0011] FIG. 3 is a view of the screen printing mask 2 as seen from direction A shown in FIG. 2. FIG. 4 is a view of the BB cross section of FIG. 3. The screen printing mask 2 is used to print a conductive paste in a specific pattern on a substrate. Hereinafter, this pattern will also be referred to as a printing pattern. The substrate includes an electronic circuit board. The conductive paste includes solder paste, silver paste, and copper paste. In FIG. 4, the substrate 5 is indicated by a two-dot chain line to show the state of the screen printing mask 2 when in use.

[0012] The screen printing mask 2 includes a first plating layer 10 and a second plating layer 20. The second plating layer 20 is formed by a plating method. The second plating layer 20 has openings 21 formed in accordance with the printing pattern. That is, when the screen printing mask 2 is used to print a conductive paste on a substrate, the openings 21 are arranged in accordance with the printing pattern.

[0013] The first plating layer 10 is formed by a plating method. The portion of the first plating layer 10 that is located inside the opening 21 is formed in a mesh shape. When a conductive paste is printed on a substrate using the screen printing mask 2, the conductive paste passes through the mesh-shaped portion of the first plating layer 10 and is supplied to the opening 21.

[0014] In the example shown in FIG. 3, the bars in the mesh-shaped portion intersect at 90 degrees. The intersection angle may be greater than or less than 90 degrees. In the example shown in FIG. 3, the bars in the mesh-shaped portion are inclined at 45 degrees with respect to the printing direction. The angle with respect to the printing direction may be greater than or less than 45 degrees. In the example shown in FIG. 3, the cross-sectional shape of the bars in the mesh-shaped portion is an inverted mushroom shape. The cross-sectional shape may be another shape.

[0015] Next, a method for manufacturing the screen printing mask 2 will be described with reference to Fig. 5 to Fig. 8. Fig. 5 is a flowchart showing an example of a method for manufacturing the screen printing mask 2 in the first embodiment. Figs. 6 to 8 are views for explaining the method for manufacturing the screen printing mask 2. Figs. 6 to 8 show a cross section corresponding to the BB cross section in Fig. 3.

[0016] First, in S101, a first step is performed in which a layer of first resist 31 is formed on a base material 30. Specifically, in the first step, a conductive base material 30 is first prepared as shown in FIG. 6(a). Next, as shown in FIG. 6(b), a layer of first resist 31 is formed on a surface 30a of the base material 30. The first resist 31 has a certain thickness. As an example, a positive resist is used as the first resist 31.

[0017] After the first step, in S102, a second step is performed in which mesh-pattern exposure is performed on the first resist 31. A glass dry plate 32 is used in the second step. Specifically, in the second step, as shown in FIG. 6(c), the glass dry plate 32 is placed on the first resist 31 so that the glass dry plate 32 faces the surface 31a of the first resist 31. The surface 31a faces in the same direction as the surface 30a.

[0018] FIG. 9 is a view of the glass dry plate 32 as viewed from the direction C shown in FIG. 6(c). FIG. 9 shows a portion of the glass dry plate 32. For example, the glass dry plate 32 is a plate-shaped glass material 32a on the surface of which light-opaque regions are formed in a specific pattern. Hereinafter, these regions will also be referred to as light-opaque regions 32b. As an example, the light-opaque regions 32b are formed by chrome plating.

[0019] In the example shown in FIG. 9, rectangular light-impermeable regions 32b are regularly arranged on the surface of glass material 32a so that light-transmitting regions are in a mesh pattern.

[0020] After the glass dry plate 32 is placed on the first resist 31, light is then irradiated from above the glass dry plate 32 toward the surface 31a of the first resist 31, as shown in FIG. 6(d). For the exposure in the second step, a parallel exposure machine, for example, is used. The light from the parallel exposure machine does not pass through the light-opaque region 32b. As a result, the light from the parallel exposure machine hits the first resist 31 in a mesh-like pattern. Once the exposure using the glass dry plate 32 is complete, the glass dry plate 32 is removed from above the first resist 31.

[0021] After the second step, in S103, a third step is performed in which the first resist 31 is exposed to light according to the printing pattern. A direct imaging machine is used in the third step. Region D shown in FIG. 6(e) is the region corresponding to the printing pattern. In the example shown in this embodiment, a positive resist is used as the first resist 31, so in the third step, light from the direct imaging machine is applied to regions other than region D. Note that, during exposure in the third step, it is acceptable if some of the light from the direct imaging machine enters inside region D.

[0022] After the third step, a fourth step, S104, is performed in which the first resist 31 is developed. As a result, as shown in FIG. 7(a), only the first resist 31 corresponding to the portion of the first plating layer 10 to be formed in a mesh shape remains on the base material 30. FIG. 10 is a view of the first resist 31 as seen from direction E shown in FIG. 7(a). FIG. 10 shows the state of the first resist 31 when the fourth step is completed.

[0023] After the fourth step, a fifth step, S105, is performed to form the first plating layer 10. In the fifth step, plating is performed on the surface 30a of the base material 30 by a plating method. Preferably, electroforming is used as the plating method. As a result, the first plating layer 10 is formed on the surface 30a, as shown in FIG. 7(b). FIG. 7(b) shows a preferred example in which the first plating layer 10 having a thickness greater than the thickness of the first resist 31 is formed on the surface 30a of the base material 30 in the fifth step. That is, when the thickness of the plating on the base material 30 exceeds the thickness of the first resist 31, the plating also grows horizontally from the portion exceeding the thickness of the first resist 31. As a result, the cross-sectional shape of the mesh-like portion of the first plating layer 10 becomes mushroom-shaped with an R-shaped tip.

[0024] After the fifth step, in S106, a sixth step of forming a second resist 33 is performed. Specifically, in the sixth step, as shown in FIG. 7(c), the second resist 33 is formed so as to cover the first plating layer 10. As an example, a negative dry film resist is used as the second resist 33. In this case, the second resist 33 is formed with a constant thickness on the surface 10a of the first plating layer 10. The surface 10a is a surface facing in the same direction as the surface 30a. A positive dry film resist may also be used as the second resist 33.

[0025] As described above, the thickness of the first plating layer 10 does not match the thickness of the first resist 31. Therefore, when the fifth step is completed, unevenness is formed on the surface of what exists on the base material 30. If this unevenness makes it impossible to use a negative or positive dry film resist as the second resist 33, a negative liquid resist may be used as the second resist 33. As another example, a positive liquid resist may be used as the second resist 33.

[0026] After the sixth step, in S107, a seventh step is performed in which the second resist 33 is exposed to light according to the printing pattern. In the seventh step, a direct imaging machine is used. If a negative resist is used as the second resist 33, in the seventh step, light from the direct imaging machine is applied to an area D as shown in FIG. 7(d).

[0027] 7, an eighth step is performed in S108, in which the second resist 33 is developed. As a result, as shown in FIG. 8(a), the second resist 33 remains so as to cover the mesh-shaped portion of the first plating layer 10. In the example shown in FIG. 8(a), the first resist 31 is also covered with the second resist 33.

[0028] After the eighth step, in S109, a ninth step is performed to form the second plating layer 20. In the ninth step, plating is performed on the surface 10a of the first plating layer 10 by a plating method. In the ninth step, electroforming is preferably used as the plating method. As a result, the second plating layer 20 is formed on the surface 10a, as shown in FIG. 8(b). FIG. 8(b) shows a preferred example in which the thickness of the second plating layer 20 does not exceed the thickness of the second resist 33 in the ninth step.

[0029] After the ninth step, in S110, a tenth step is performed in which the first resist 31 and the second resist 33 are removed. As shown in FIG. 8(c), the portions from which the second resist 33 has been removed become openings 21 in the second plating layer 20.

[0030] Finally, the first plating layer 10 is separated from the base material 30. This allows the screen printing mask 2 to be obtained as shown in Figures 3 and 4. The screen printing mask 2 is then attached to a frame 4 via a gauze 3, thereby completing the screen printing plate 1.

[0031] 11 to 14 show micrographs of a screen printing mask 2 actually produced by the method shown in embodiment 1. Fig. 11 is a photograph of the screen printing mask 2 viewed from the first plating layer 10 side. Figs. 12 to 14 are photographs of the screen printing mask 2 viewed obliquely from the second plating layer 20 side. Figs. 12 to 14 each show a different printing pattern.

[0032] In the example shown in this embodiment, the first plating layer 10 having a mesh-like portion is formed by plating. Unlike conventional methods, it is not necessary to use a stainless steel mesh for the screen printing mask. Therefore, even if the printing pattern becomes finer, the price of the screen printing mask 2 can be prevented from increasing.

[0033] In the example shown in this embodiment, the first resist 31 for creating the mesh-like portion is formed by exposure using a glass dry plate 32. Exposure using a glass dry plate 32 is extremely accurate. For this reason, by employing exposure using a glass dry plate 32, it is possible to easily create, for example, a mesh portion equivalent to 1000 mesh in the first plating layer 10.

[0034] Generally, glass dry plates are expensive. However, in the example shown in this embodiment, a mesh-shaped exposure is performed using a glass dry plate 32, and exposure according to the printing pattern is performed using a direct imaging machine. Therefore, even if the printing pattern is different, the screen printing mask 2 can be produced using the same glass dry plate 32 as long as the mesh shape is the same. For example, by preparing glass dry plates 32 equivalent to 650 mesh, glass dry plates 32 equivalent to 840 mesh, and glass dry plates 32 equivalent to 1000 mesh, various screen printing masks 2 can be produced. Therefore, in the example shown in this embodiment, the unit cost of the screen printing mask 2 can be reduced.

[0035] For example, to draw a mesh portion equivalent to 500 to 840 meshes using a direct drawing machine, a drawing accuracy of 3 μm or less is required. A direct drawing machine for ordinary printed circuit boards cannot achieve this level of drawing accuracy. While a high-precision direct drawing machine could achieve this level of drawing accuracy, the direct drawing machine would be extremely expensive. In the example shown in this embodiment, there is no need to use such an expensive direct drawing machine.

[0036] In this embodiment, an example in which the third step is performed after the second step has been described. The second and third steps may be performed after the first step and before the fourth step. For example, the second step may be performed after the third step.

[0037] In the present embodiment, an example has been described in which the first resist 31 is removed together with the second resist 33 in the tenth step. The first resist 31 may be removed after the fifth step and before the sixth step. [Explanation of symbols]

[0038] 1 screen printing plate, 2 screen printing mask, 3 gauze, 4 frame, 5 substrate, 10 first plating layer, 10a surface, 20 second plating layer, 21 opening, 30 base material, 30a surface, 31 first resist, 31a surface, 32 glass dry plate, 32a glass material, 32b light-opaque area, 33 second resist

Claims

1. 1. A method for manufacturing a screen printing mask for printing a conductive paste in a specific pattern on a substrate, comprising: A first step of forming a layer of a first resist on a base material; a second step of performing a mesh-shaped exposure on the first resist using a glass dry plate after the first step; a third step of exposing the first resist to light according to the pattern using a direct drawing machine after the first step; a fourth step of developing the first resist after the second step and the third step; a fifth step of forming a first plating layer by plating the base material after the fourth step; a sixth step of forming a second resist so as to cover the first plating layer after the fifth step; a seventh step of exposing the second resist to light according to the pattern using a direct drawing machine after the sixth step; an eighth step of developing the second resist after the seventh step; a ninth step of forming a second plating layer by plating the first plating layer after the eighth step; a tenth step of removing the second resist after the ninth step; A method for manufacturing a screen printing mask comprising:

2. In the first step, a positive resist is used as the first resist, 2. The method for producing a screen printing mask according to claim 1, wherein in the third step, light from the direct drawing machine is applied to an area other than an area corresponding to the pattern.

3. 3. The method for manufacturing a screen printing mask according to claim 1, wherein the third step is carried out after the second step.

4. 3. The method for producing a screen printing mask according to claim 1, wherein in the fifth step, the first plating layer is formed on the base material so as to have a thickness greater than a thickness of the first resist.

5. 3. The method for producing a screen printing mask according to claim 1, wherein in the tenth step, the first resist is removed together with the second resist.

6. 3. The method for producing a screen printing mask according to claim 1, wherein in the sixth step, a negative dry film resist is used as the second resist.

7. 3. The method for producing a screen printing mask according to claim 1, wherein in the sixth step, a positive or negative liquid resist is used as the second resist.

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