Metal mask and printing method

Abstract

To perform printing excellently by suppressing smearing in addition to suppressing the deterioration of the plate strength of a printing plate.SOLUTION: A metal mask includes a first mask layer having a pair of main surfaces and a plurality of openings penetrating through the pair of main surfaces, and a second mask layer in which a plurality of openings are formed and laminated on one main surface of the first mask layer, when viewing the first mask layer and the second mask layer from a lamination direction, the plurality of openings formed on the second mask layer do not overlap with the first opening at least partially overlapping with the opening formed in a first mask layer and the opening formed in the first mask layer, and contains the second opening overlapping with a region where the opening is not formed among one main surface of the first mask layer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a metal mask and a printing method. [Background technology]

[0002] Among screen printing methods in which a pattern is formed by discharging a paste using a printing plate, printing methods using a metal mask are known (see, for example, Patent Documents 1 to 3). Patent Document 1 describes a metal mask in which a plurality of flat posts are arranged over the entire surface. Patent Document 2 describes a metal mask in which a plurality of ribs are arranged on one side. Patent Document 3 describes a metal mask that has been subjected to an etching process. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-230223 A [Patent Document 2] Japanese Patent Application Publication No. 9-300573 [Patent Document 3] Japanese Patent Application Publication No. 11-321146 Summary of the Invention [Problem to be solved by the invention]

[0004] When printing using a metal mask, the pattern portion located in the direction of travel of the printing squeegee is likely to have poor release from the printing plate, which may lead to bleeding of the pattern. The occurrence of bleeding can be suppressed by using the metal masks described in Patent Documents 1 and 2. However, the metal masks described in Patent Documents 1 and 2 have multiple posts or multiple ribs arranged over the entire surface, which weakens the plate strength. The metal mask described in Patent Document 3 is etched, which makes it difficult to freely design the metal mask as with fine processing.

[0005] The present invention has been made to solve at least part of the above-mentioned problems, and aims to perform good printing with suppressed bleeding while suppressing a decrease in the plate strength of the printing plate. [Means for solving the problem]

[0006] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized in the following forms.

[0007] (1) According to one aspect of the present invention, there is provided a metal mask comprising: a first mask layer having a pair of main surfaces and a plurality of openings penetrating the pair of main surfaces; and a second mask layer having a plurality of openings formed therein and laminated on one main surface of the first mask layer, wherein, when viewed in a lamination direction of the first mask layer and the second mask layer, the plurality of openings formed in the second mask layer include a first opening at least partially overlapping with an opening formed in the first mask layer, and a second opening not overlapping with an opening formed in the first mask layer and overlapping with a region of the one main surface of the first mask layer where no openings are formed.

[0008] According to this configuration, a metal mask is formed by laminating a first mask layer and a second mask layer having openings of different shapes and positions. During printing, a pattern corresponding to a first opening that at least partially overlaps an opening formed in the first mask layer among a plurality of openings formed in the second mask layer is formed on the printing target. On the other hand, in a second opening that does not overlap an area of ​​an opening formed in the first mask layer among a plurality of openings formed in the second mask layer, the paste is not discharged onto the printing target, so that no pattern is formed. Unlike this configuration, the second mask layer in which the second opening does not exist adheres to the printing target in the area where the second opening does not exist during printing. In contrast, in this configuration, the second mask layer does not adhere to the printing target in the area of ​​the second opening during printing, so that the printing plate is easily released, and bleeding occurring in the pattern formed on the printing target is suppressed. The second opening may be formed in the second mask layer corresponding to an area where bleeding is likely to occur in the pattern, and it is not necessary to form the second opening more than necessary in other places. As a result, with this configuration, it is possible to perform good printing while suppressing the deterioration of the plate strength of the printing plate and suppressing the occurrence of bleeding on the printing subject.

[0009] (2) In the metal mask of the above embodiment, the first mask layer may have a pattern formation region in which the plurality of openings are formed in a predetermined pattern, and when viewed from the stacking direction, the first opening of the second mask layer may be formed at a position overlapping the pattern formation region of the first mask layer, and the second opening of the second mask layer may be formed so as to surround the outside of the pattern formation region of the first mask layer. According to this configuration, a predetermined pattern can be formed on the printing target by the first opening formed at a position overlapping with the pattern formation region. The region on the printing target where bleeding occurs is the vicinity of the paste ejected. Therefore, by forming the second opening so as to surround the outside of the pattern formation region, the paste ejected on the pattern formation region is prevented from bleeding into other regions.

[0010] (3) In the metal mask of the above embodiment, the first mask layer may have a first pattern formation region in which the plurality of openings are formed in a predetermined pattern, a second pattern formation region different from the first pattern formation region in which the plurality of openings are formed in a predetermined pattern, and a linear region formed between the first pattern formation region and the second pattern formation region, the linear region having no openings, and when viewed from the stacking direction, the second opening of the second mask layer may overlap the linear region of the first mask layer and be formed along the center line so as to include the center line of the linear region. According to this configuration, when viewed from the stacking direction, a linear region in which no pattern is formed on the printing target exists between the first pattern formation region and the second pattern formation region. The second opening is formed to include the center line of the linear region. That is, the second opening is formed in the center portion of the linear region along the center line. Therefore, since the second opening is not formed biased toward a position closer to either the first pattern formation region or the second pattern formation region during printing, the printing plate is easily released and bleeding occurring on the printing target is suppressed.

[0011] (4) In the metal mask of the above aspect, when viewed from the stacking direction, 90% or more of the linear region in its width direction may overlap with the second opening. According to this configuration, 90% or more of the linear region in the width direction overlaps with the second opening. By overlapping a larger area of ​​the linear region with the second opening, the printing plate release is further improved and bleeding on the printed object is further suppressed.

[0012] (5) In the metal mask of the above form, when the region in which no openings are formed in the first mask layer is evenly divided into an upstream region and a downstream region along the squeegee direction during printing, when viewed from the stacking direction, the total area of ​​the region overlapped by the second openings of the second mask layer in the upstream region may be larger than the total area of ​​the region overlapped by the second openings of the second mask layer in the downstream region. According to this configuration, in the region where a pattern is not formed on the printing target when viewed from the stacking direction, the total area of ​​the region where the upstream region and the second opening overlap along the squeegee direction is greater than the total area of ​​the region where the downstream region and the second opening overlap. That is, the second opening is formed biased toward the upstream side along the squeegee direction in the region where a pattern is not formed. In the region where a pattern is formed, the plate release is delayed, and the paste that is the source of the pattern progresses to bleed. In particular, the place where bleed is likely to occur is the place where the first opening is squeegeeed to the region where no opening is formed in the squeegee traveling direction, that is, the upstream boundary in the region where a pattern is not formed. In this configuration, the second opening is formed biased toward the upstream side along the squeegee direction in the region where a pattern is not formed. As a result, the formation region of the second opening is reduced, the decrease in plate strength is suppressed, and the printing plate release is improved.

[0013] The present invention can be realized in various forms, for example, in the form of a metal mask, a printing plate, and a system including these, a printing method, and a system including these. [Brief description of the drawings]

[0014] [Figure 1] 1A to 1C are explanatory diagrams illustrating pattern formation on a substrate using a metal mask according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic top view of the metal mask as viewed from the stacking direction. [Diagram 3] FIG. 3 is an enlarged view of a region RG1 in FIG. [Figure 4] 1 is a flowchart of a printing method using a metal mask. [Diagram 5] FIG. 2 is a schematic top view of a metal mask according to a first modified example of the first embodiment. [Figure 6] FIG. 4 is a schematic top view of a metal mask according to a second modified example of the first embodiment. [Figure 7] FIG. 6 is a schematic top view of a portion of a metal mask according to a second embodiment. [Figure 8]FIG. 11 is a schematic top view of a portion of a metal mask according to a first modified example of the second embodiment. [Figure 9] FIG. 11 is a schematic top view of a portion of a metal mask according to a second modified example of the second embodiment. [Figure 10] FIG. 13 is a schematic top view of a portion of a metal mask according to a third modified example of the second embodiment. [Figure 11] FIG. 11 is a schematic top view of a metal mask according to a third embodiment. [Figure 12] FIG. 11 is a schematic cross-sectional view of a metal mask according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] First Embodiment FIG. 1 is an explanatory diagram of pattern formation on a substrate BD using a metal mask 1 according to one embodiment of the present invention. The metal mask 1 shown in FIG. 1 is used for forming circuits in electronic components, IC packages, sensor devices, semiconductor manufacturing equipment, and the like. FIG. 1 shows a schematic cross-sectional view of the metal mask 1 and substrate BD during pattern formation. During pattern formation, solder paste PS is poured in the squeegee direction by a squeegee SQ from a main surface 11, which is the upper surface of the metal mask 1 placed on the substrate BD. The solder paste dispensed into the openings 13, 23A of the metal mask 1 is formed as a pattern on the substrate BD.

[0016] The metal mask 1 shown in FIG. 1 includes a flat first mask layer 10 and a flat second mask layer 20 laminated on one main surface 12 of the first mask layer 10. The first mask layer 10 has a pair of main surfaces 11, 12 and a plurality of openings 13 penetrating the pair of main surfaces 11, 12. The second mask layer 20 has a pair of main surfaces 21, 22 and a plurality of openings 23 penetrating the pair of main surfaces 21, 22. The plurality of openings 23 are composed of a first opening 23A and a second opening 23B. When viewed from the lamination direction (Z-axis direction) of the first mask layer 10 and the second mask layer 20, the first opening 23A at least partially overlaps with the opening 13 formed in the first mask layer 10. On the other hand, the second opening 23B does not overlap the opening 13 formed in the first mask layer 10 when viewed from the stacking direction, but overlaps with a region of one main surface 12 of the first mask layer 10 where the opening 13 is not formed. Therefore, when forming the pattern shown in FIG. 2, a pattern is formed by pouring the solder paste PS by the squeegee SQ onto the substrate BD corresponding to the region of the first opening 23A of the second mask layer 20 when viewed from the stacking direction. On the other hand, no pattern is formed on the substrate BD corresponding to the region of the second opening 23B of the second mask layer 20. The orthogonal coordinate system CS shown in FIG. 1 is composed of a Y axis parallel to the squeegee direction, a Z axis parallel to the stacking direction, and an X axis perpendicular to the Y axis and the Z axis. The orthogonal coordinate system CS shown in FIG. 1 corresponds to the orthogonal coordinate system CS shown in FIG. 2 and subsequent figures.

[0017] FIG. 2 is a schematic top view of the metal mask 1 as viewed from the lamination direction. In FIG. 2, the area of ​​the pattern formed on the substrate BD is hatched. In other words, the hatched area is the area where the first opening 23A of the second mask layer 20 is formed. On the other hand, the non-hatched area is the area where the first opening 23A is not formed, and includes the areas RG1, RG2 where the second opening 23B is formed. In FIG. 2, the areas RG1, RG2 of the second opening 23B of the second mask layer 20 are shown surrounded by dashed lines. The schematic cross section shown in FIG. 1 corresponds to the AA cross section in FIG. 2.

[0018] FIG. 3 is an enlarged view of the region RG1 in FIG. 2. As shown in FIG. 3, when viewed from the stacking direction, the region RG1 of the second opening 23B of the second mask layer 20 is biased toward the upstream side in the squeegee direction among the regions where no pattern is formed on the substrate BD. In other words, when the region where the first opening 23A is not formed in the second mask layer 20 is evenly divided into an upstream region RG1u and a downstream region RG1d by a middle line OLr along the squeegee direction, the total area of ​​the upstream region RG1u where the second opening 23B overlaps in the region RG1 is larger than the total area of ​​the downstream region RG1d where the second opening 23B overlaps. Note that, unlike FIG. 2, hatching is applied in FIG. 3 to distinguish the upstream region RG1u from the downstream region RG1d among the regions where no pattern is formed.

[0019] 2 is disposed biased toward the upstream side in the squeegee direction among the regions on the substrate BD where no pattern is formed, similar to the region RG1. That is, when the region on the second mask layer 20 where the first openings 23A are not formed is evenly divided into an upstream region and a downstream region along the squeegee direction, the total area of ​​the regions overlapped by the second openings 23B in the upstream region is larger than the total area of ​​the regions overlapped by the second openings 23B in the downstream region.

[0020] Fig. 4 is a flowchart of a printing method using the metal mask 1. In the printing flow shown in Fig. 4, first, the metal mask 1 is prepared (step S1). Next, of the pair of main surfaces 21, 22 (Fig. 1) of the second mask layer 20 in the metal mask 1, the substrate BD is placed on one main surface 22 on which the first mask layer 10 is not laminated (step S2). Squeegeeing is performed in which the solder paste PS is discharged in the squeegee direction from the main surface 11, of the pair of main surfaces 11, 12 of the first mask layer 10, which does not face the second mask layer 20 (step S3), and the printing flow ends.

[0021] As described above, the metal mask 1 of this embodiment includes the first mask layer 10 and the second mask layer 20 laminated on the first mask layer 10. The first mask layer 10 has a pair of main surfaces 11, 12 and a plurality of openings 13 penetrating the pair of main surfaces 11, 12. The second mask layer 20 has a plurality of openings 23 penetrating the pair of main surfaces 21, 22. The plurality of openings 23 are composed of a first opening 23A and a second opening 23B. When viewed from the lamination direction of the first mask layer 10 and the second mask layer 20, the first opening 23A at least partially overlaps with the opening 13 formed in the first mask layer 10. On the other hand, when viewed from the lamination direction, the second opening 23B does not overlap with the opening 13 formed in the first mask layer 10, but overlaps with a region of one main surface 12 of the first mask layer 10 in which the opening 13 is not formed. In this embodiment, the metal mask 1 is formed by laminating the first mask layer 10 and the second mask layer 20, which have openings with different shapes and positions. During pattern formation, a pattern corresponding to the first opening 23A, which at least partially overlaps the opening 13 formed in the first mask layer 10, among the multiple openings 23 formed in the second mask layer 20, is formed on the substrate BD. On the other hand, in the second opening 23B, which does not overlap the region of the opening 13 formed in the first mask layer 10, among the multiple openings 23 formed in the second mask layer 20, the paste is not discharged, so that no pattern is formed on the substrate BD. Unlike this embodiment, the second mask layer, which does not have the second opening 23B, adheres to the substrate BD in the portion where the second opening 23B does not exist during pattern formation. In contrast, in this embodiment, the second mask layer does not adhere to the substrate BD in the region of the second opening 23B, so that the printing plate is easily released, and bleeding occurring in the pattern formed on the substrate BD is suppressed. In this embodiment, the second openings 23B need only be formed in the second mask layer 20 in areas where bleeding is likely to occur in the pattern, and need not be formed in other locations more than necessary. As a result, in this embodiment, deterioration in the plate strength of the metal mask 1 is suppressed, and good printing is performed with bleeding on the substrate BD suppressed.

[0022] In addition, in this embodiment, when the region in the second mask layer 20 where the first openings 23A are not formed is divided evenly into an upstream region RG1u and a downstream region RG1d along the squeegee direction, the total area of ​​the upstream region RG1u where the second openings 23B overlap is larger than the total area of ​​the downstream region RG1d where the second openings 23B overlap. In this embodiment, the second openings 23B formed in the second mask layer 20 are formed biased toward the upstream side along the squeegee direction in the region where the pattern is not formed on the substrate BD when viewed from the stacking direction. In the region where the pattern is formed on the substrate BD, the release of the plate is delayed, and the bleed of the solder paste PS progresses. In particular, the place where the bleed is likely to occur is the place where the first openings 23A are squeegeeed to the region where the openings are not formed, that is, the upstream boundary in the region where the pattern is not formed. In this embodiment, the second openings 23B are formed biased toward the upstream side along the squeegee direction in the region where the pattern is not formed. This reduces the area in which the second openings 23B are formed, suppressing a decrease in plate strength, and improves the printing plate release.

[0023] <First Modification of First Embodiment> Fig. 5 is a schematic top view of a metal mask 1a of a first modified example of the first embodiment. The pattern formed on the substrate BD by the metal mask 1a shown in Fig. 5 is different from the pattern formed on the substrate BD by the metal mask 1 shown in Figs. 1 and 2. That is, the first mask layer and the second mask layer of the metal mask 1a each have openings formed therein that are different from the openings 13, 23 formed in the first mask layer 10 and the second mask layer 20 of the metal mask 1.

[0024] In FIG. 5, similar to FIG. 2, when viewed from the stacking direction, hatching is applied to the pattern formed on the substrate BD corresponding to the first opening 23Aa formed in the second mask layer. As shown in FIG. 5, the first opening 23Aa is formed inside a circle with a radius R1 from the center O and outside a circle with a radius R2 (>R1) from the center O in the plane direction orthogonal to the stacking direction of the second mask layer. On the other hand, the second opening 23Ba shown by the dashed line in FIG. 5 is formed in the region RG1a surrounded by the outside of an arc with a radius R3 (R1 < R3 < R2) from the center O, the inside of an arc with a radius R4 (R3 < R4 < R2) from the center O, and the intermediate line OLra in the plane direction of the second mask layer. The intermediate line OLra is a boundary line when the region where the first opening 23Aa is not formed in the second mask layer is equally divided into an upstream region and a downstream region along the squeegee direction. That is, when the region where the first opening 23Aa is not formed in the second mask layer is equally divided into an upstream region and a downstream region with the intermediate line OLra as a reference along the squeegee direction, the total area of the upstream region RG1a where the second opening 23Ba is formed is larger than the total area of the downstream region where the second opening 23Ba is not formed.

[0025] As described above, in the metal mask 1a of the first modification of the first embodiment shown in FIG. 5, the second opening 23Ba formed in the second mask layer is formed biased toward the upstream side along the squeegee direction among the regions where no pattern is formed on the substrate BD. In the substrate BD, the place where bleeding is likely to occur is the place where the squeegee is squeegeed from the first opening 23Aa to the region where the opening is not made with respect to the advancing direction of the squeegee, that is, the vicinity of the arc on the negative Y-axis side with a radius R2 in FIG. 5. In this first modification, the region RG1a where the second opening 23Ba is formed among the regions where no pattern is formed is formed biased toward the upstream side along the squeegee direction. Thereby, while reducing the formation region of the second opening 23Ba and suppressing the decrease in the plate strength, the separation of the printing plate becomes good.

[0026] <Second Modification of the First Embodiment> Fig. 6 is a schematic top view of a metal mask 1b according to a second modified example of the first embodiment. The metal mask 1b shown in Fig. 6 has a different second opening 23Bb formed in the second mask layer from the metal mask 1a shown in Fig. 5. Therefore, in the second modified example, only the second opening 23Bb will be described, and a description of the first opening 23Aa and the like, which have the same shape as the first modified example, will be omitted.

[0027] As shown in Fig. 6, when viewed from the stacking direction, the second openings 23Bb are formed in a region RGb in the second mask layer that is surrounded by an outer side of a radius R3 from the center O and an inner side of a radius R4 from the center O. The region RGb in which the second openings 23Bb are formed is a region in which the first openings 23Aa are not formed in the second mask layer, and the total area of ​​the upstream region along the squeegee direction and the total area of ​​the downstream region are the same, based on the midline OLra. In this way, the region RGb in which the second openings 23Bb are formed does not have to be arranged biased toward the upstream side along the squeegee direction.

[0028] <Second embodiment> FIG. 7 is a schematic top view of a portion of the metal mask 1c of the second embodiment. The pattern formed on the substrate BD by the metal mask 1c of the second embodiment is a pattern formation region RPT hatched in FIG. 7, which is different from the first embodiment. Note that FIG. 7 shows a portion of the metal mask 1c, and the metal mask 1c of the second embodiment as a whole has a plurality of pattern formation regions RPT as shown in FIG. 7 formed therein. The plurality of pattern formation regions RPT are the same region as the first opening 23Ac formed in the second mask layer of the second embodiment when viewed from the stacking direction. One pattern formation region RPT shown in FIG. 7 is an inner region of a rectangle having a center of gravity G and a length Lx0 parallel to the XY axis and a length Ly0 parallel to the X axis. In the second embodiment, the region in which the opening 13c is formed in the first mask layer is a position that overlaps with the pattern formation region RPT in which the first opening 23Ac is formed in the second mask layer, that is, the same region, when viewed from the stacking direction.

[0029] The second opening 23Bc formed in the second mask layer of the second embodiment is a region RGc that is outside one smaller rectangle BX1 and inside the other rectangle BX2 of two rectangles BX1 and BX2 that are different in size and do not overlap each other when viewed from the stacking direction. As shown in Fig. 7, the shape of one rectangle BX1 forming the region RGc is a rectangle with a center of gravity G and a length Lx1 (>Lx0) parallel to the X axis and a length Ly1 (>Ly0) parallel to the Y axis. The shape of the other rectangle BX2 is a rectangle larger than the rectangle BX1, with a center of gravity G, and a length Lx2 (>Lx1) parallel to the X axis and a length Ly2 (>Ly1) parallel to the Y axis. Therefore, in the second embodiment, the second opening 23Bc formed in the second mask layer is formed so as to surround the outside of the pattern formation region RPT, which is the area of ​​the opening 13c in the first mask layer, and the pattern formation region RPT, which is the area of ​​the first opening 23Ac in the second mask layer, when viewed from the stacking direction.

[0030] As described above, a plurality of pattern formation regions RPT are formed as the openings 13c in the first mask layer of the second embodiment. When viewed from the stacking direction, the first openings 23Ac formed in the second mask layer are formed at the same positions overlapping the openings 13c of the first mask layer. On the other hand, the second openings 23Bc formed in the second mask layer are formed so as to surround the pattern formation region RPT. Therefore, in the second embodiment, a pattern can be formed on the substrate BD by the first openings 23Ac formed at positions overlapping the pattern formation region RPT. The region on the substrate BD where bleeding occurs is the vicinity of the solder paste discharged. Therefore, by forming the second openings 23Bc so as to surround the outside of the pattern formation region RPT, the solder paste discharged in the pattern formation region RPT is prevented from bleeding into other regions.

[0031] <First Modification of Second Embodiment> FIG. 8 is a schematic top view of a part of a metal mask 1d of a first modified example of the second embodiment. In the metal mask 1d shown in FIG. 8, the second opening 23Bd formed in the second mask layer is different from the metal mask 1c of the second embodiment shown in FIG. 7. Specifically, the second opening 23Bd of the first modified example is composed of a plurality of rectangles ΔBX spaced apart from each other in the region RGc of FIG. 7 when viewed from the stacking direction. As shown in FIG. 8, the plurality of rectangles ΔBX are arranged side by side along the X-axis and the Y-axis so as to surround the pattern formation region RPT. Therefore, the second opening 23Bd formed in the metal mask 1d of the first modified example is a region obtained by subtracting the region in which the openings that separate adjacent rectangles ΔBX are not formed from the region RGc of the metal mask 1c of the second embodiment. 7, each shape of the rectangle ΔBX is a rectangle having a length ΔLx (=(Lx2-Lx1) / 2) parallel to the X axis and a length ΔLy (=(Ly2-Ly1) / 2) parallel to the Y axis. In this manner, the shape of the second opening 23Bd surrounding the pattern formation region RPT can be changed.

[0032] <Second Modification of Second Embodiment> 9 is a schematic top view of a portion of a metal mask 1e of a second modified example of the second embodiment. In the metal mask 1e shown in FIG. 9, when viewed from the stacking direction, no openings are formed in the region corresponding to the multiple rectangles ΔBX in the second mask layer of the first modified example shown in FIG. 8. Instead, in the second mask layer of the metal mask 1e, when viewed from the stacking direction, a region RGe in which a second opening 23Be is formed is formed in a region that is outside the rectangle BX3 and inside the rectangle BX4, minus the multiple rectangles ΔBX. In FIG. 9, the multiple rectangles ΔBX in which no openings are formed are represented by hatching that is finer than the hatching applied to the pattern formation region RPT.

[0033] As shown in FIG. 9, the shape of rectangle BX3 is a rectangle with its centroid at G, having a length Lx3 parallel to the X-axis (Lx0 < Lx3 < Lx1) and a length Ly3 parallel to the Y-axis (Ly0 < Ly3 < Ly1). Rectangle BX3 is smaller than rectangle BX1 shown in FIG. 7. As shown in FIG. 9, the shape of rectangle BX4, which is larger than rectangle BX3, is a rectangle with its centroid at G, having a length Lx4 (>Lx2) parallel to the X-axis and a length Ly4 (>Ly2) parallel to the Y-axis. Rectangle BX4 is larger than rectangle BX2 shown in FIG. 7. Thus, the shape of the second opening 23Be surrounding the pattern formation region RPT is deformable.

[0034] <Third Modification of the Second Embodiment> FIG. 10 is a schematic top view of a part of the metal mask 1f of the third modification of the second embodiment. In the metal mask 1f shown in FIG. 9, when viewed from the stacking direction, the rectangle BX4 of the second modification shown in FIG. 9 has changed to a larger rectangle BX4f. Further, in the metal mask 1f of the third modification in FIG. 10, as rectangle BX4f becomes larger, the number of rectangles ΔBX formed as openings outside rectangle BX3 and inside rectangle BX4f has increased. In FIG. 10, as in FIG. 9, hatches finer than the hatches applied to the pattern formation region RPT are shown to be applied within a plurality of rectangles ΔBX where no openings are formed.

[0035] As shown in FIG. 10, the shape of rectangle BX4f is a rectangle with its centroid at G, having a length Lx4f (>Lx4) parallel to the X-axis and a length Ly4f (>Ly4) parallel to the Y-axis when viewed from the stacking direction. A plurality of rectangles ΔBX arranged outside rectangle BX3 and inside rectangle BX4f are more numerous than those shown in FIG. 9 and are arranged side by side along each of the X-axis and the Y-axis. Therefore, in the second mask layer of the metal mask 1f, when viewed from the stacking direction, a region RGf in which the second opening 23Bf is formed is formed in a region obtained by subtracting a plurality of rectangles ΔBX from a region that is outside rectangle BX3 and inside rectangle BX4f. Thus, the shape of the second opening 23Bf surrounding the pattern formation region RPT is deformable.

[0036] <Third embodiment> FIG. 11 is a schematic top view of the metal mask 1g of the third embodiment. FIG. 12 is a schematic cross-sectional view of the metal mask 1g of the third embodiment. In the metal mask 1g of the third embodiment, as shown in FIG. 12, the opening 13g of the first mask layer 10g forming the pattern is partially overlapped with the first opening 23Ag of the second mask layer 20g. Therefore, as shown by hatching in FIG. 11, when viewed from the stacking direction, a pattern is formed on the substrate BD that overlaps the first pattern formation region RPT1 and the second pattern formation region RPT2 different from the first pattern formation region RPT1. As shown in FIG. 11, between the first pattern formation region RPT1 and the second pattern formation region RPT2, when viewed from the stacking direction, a region where a pattern is not formed on the substrate BD is formed along the center line OLg of the broken line. A second opening 23Bg is formed in a part of the second mask layer 20g that overlaps this region where a pattern is not formed.

[0037] Fig. 12 shows an enlarged cross-sectional view of a region AR in Fig. 11. As shown in Fig. 12, when viewed from the stacking direction, a first opening 23Ag is formed in the second mask layer 20g in a region where the first pattern formation region RPT1 and the second pattern formation region RPT2 are to be formed on the substrate BD.

[0038] In the second mask layer 20g, as shown in FIGS. 11 and 12, a broken line-shaped region RBL in which no pattern is formed and having a width of length LnPT centered on a center line OLg is formed between the first opening 23Ag overlapping the first pattern formation region RPT1 and the first opening 23Ag overlapping the second pattern formation region RPT2. When viewed from the stacking direction, the second opening 23Bg of the second mask layer 20g overlaps with a part of the broken line-shaped region RBL and is formed along the center line OLg so as to include the center line OLg of the broken line-shaped region RBL. The second opening 23Bg is formed with a width of length L23B along the center line OLg. The center line of the second opening 23Bg overlaps with the center line OLg of the broken line-shaped region RBL. The width L23B of the second opening 23Bg centered on the center line OLg is 90% of the width LnPT of the broken line-shaped region RBL. In other words, when viewed from the stacking direction, 90% of the broken line region RBL overlaps with the second opening 23Bg in its width direction.

[0039] As described above, in the third embodiment, a broken line-shaped region RBL in which no pattern is formed and which has a width of length LnPT centered on the center line OLg is formed between the first pattern-forming region RPT1 and the second pattern-forming region RPT2. The second opening 23Bg of the second mask layer 20g is formed along the center line OLg so as to overlap with the broken line-shaped region RBL when viewed from the stacking direction and include the center line OLg of the broken line-shaped region RBL. In the third embodiment, the second opening 23Bg is formed in the center part along the center line OLg in the broken line-shaped region RBL. Therefore, when a pattern is formed on the substrate BD, the second opening 23Bg is not formed biasedly in a position close to either the first pattern-forming region RPT1 or the second pattern-forming region RPT2, so that the printing plate separation of the metal mask 1g from the substrate BD is improved, and bleeding occurring on the substrate BD is suppressed.

[0040] 12, when viewed from the stacking direction, 90% of the broken line region RBL in the width direction overlaps with the second opening 23Bg. That is, 90% of the broken line region RBL in the width direction overlaps with the second opening 23Bg. By overlapping a larger area of ​​the broken line region RBL with the second opening 23Bg, the printing plate separation of the metal mask 1g from the substrate BD is further improved, and bleeding that occurs on the substrate BD is further suppressed.

[0041] <Modifications of the embodiment> The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit and scope of the invention. For example, the following modifications are also possible.

[0042] The metal masks of the first to third embodiments are merely examples and may be modified as long as they include a first opening 23A that partially overlaps with the opening 13 formed in the first mask layer 10 and a second opening 23B that does not overlap with the opening 13 of the first mask layer 10. In the metal mask 1 of the first embodiment, as shown in FIG. 3, when the region in the second mask layer 20 in which the first opening 23A is not formed is equally divided into an upstream region RG1u and a downstream region RG1d when viewed from the stacking direction, the total area of ​​the upstream region RG1u is larger than the total area of ​​the downstream region RG1d. However, the total area of ​​the upstream region RG1u may be equal to or smaller than the total area of ​​the downstream region RG1d.

[0043] In the metal mask 1c of the second embodiment, as shown in FIG. 7, the second opening 23Bc is formed in the second mask layer so as to surround the outside of the pattern formation region RPT where the pattern is formed on the substrate BD when viewed from the stacking direction. However, the second opening 23Bc does not have to be formed in the second mask layer so as to surround the outside of the pattern formation region RPT. For example, the second opening 23Bc may be formed in a part of the second mask layer on the upstream side along the squeegee direction when viewed from the stacking direction, among the outside of the pattern formation region RPT. In the second embodiment, the opening 13c formed in the first mask layer and the first opening 23Ac formed in the second mask layer are the same area when viewed from the stacking direction, but they may be different. For example, as in the first embodiment shown in FIG. 1, the first opening 23A of the second mask layer 20 may have a larger area than the first opening 23A of the first mask layer 10 when viewed from the stacking direction. On the other hand, in other embodiments, the first opening formed in the second mask layer, which partially overlaps with the opening of the first mask layer, may have a smaller area than the first opening of the first mask layer when viewed from the stacking direction. The thickness of the first mask layer and the thickness of the second mask layer along the stacking direction can also be changed. As in the first embodiment shown in FIG. 1, the thickness of the second mask layer 20 may be greater than the thickness of the first mask layer 10. The thickness of the second mask layer may be equal to or less than the thickness of the first mask layer.

[0044] In the metal mask 1g of the third embodiment, as shown in FIG. 12, the broken line region RBL formed between the first pattern formation region RPT1 and the second pattern formation region RPT2 overlaps with the second opening 23Bg by 90% in its width direction when viewed from the stacking direction. However, the broken line region RBL may overlap with the second opening 23Bg by more than 90% in its width direction when viewed from the stacking direction, or may overlap with the second opening 23Bg by less than 90%. In particular, it is preferable that the broken line region RBL overlaps with the second opening 23Bg by 90% or more in its width direction. The second opening 23Bg of the second mask layer 20g is formed along the center line OLg so as to include the center line OLg of the broken line region RBL when viewed from the stacking direction. However, the second opening 23Bg may be formed not to include the center line OLg. For example, the second opening 23Bg may be formed in the second mask layer 20g upstream of the center line OLg along the squeegee direction in a region where the center line OLg extends parallel to the X-axis, without overlapping the center line OLg when viewed from the stacking direction. In the third embodiment, the linear region where no pattern is formed is a broken line region RBL, but the linear region may be a curved region. In addition, the region formed along the linear center line may have a different widthwise length depending on the position along the center line.

[0045] In the first to third embodiments, for example, as shown in FIG. 2, the squeegee direction is shown aligned with the metal mask 1, but the squeegee direction during paste formation can be estimated from the metal mask 1. When forming a pattern, the location where the solder paste PS is likely to bleed due to delay in plate separation is the location where the solder paste PS is squeegeeed from the first opening 23A to the non-opening area in the squeegee advance direction. Therefore, when looking at the metal mask 1, the squeegee direction can be estimated from the position of the second opening 23B in the area where the first opening 23A is not formed and where no pattern is formed in the second mask layer 20. Specifically, when the second opening 23B is biased in a specific direction (Y-axis negative direction in FIG. 2) in the area where the first opening 23A is not formed, the direction opposite to the biased direction can be estimated as the squeegee direction.

[0046] Although the present aspect has been described above based on the embodiment and modified examples, the above-mentioned embodiment of the aspect is intended to facilitate understanding of the present aspect and does not limit the present aspect. The present aspect may be modified or improved without departing from the spirit and scope of the claims, and equivalents are included in the present aspect. Furthermore, if a technical feature is not described as essential in this specification, it may be deleted as appropriate.

[0047] The present invention can also be realized in the following forms. [Application example 1] A metal mask, a first mask layer having a pair of main surfaces and a plurality of openings penetrating the pair of main surfaces; a second mask layer having a plurality of openings formed therein and laminated on one main surface of the first mask layer; Equipped with When viewed from a stacking direction of the first mask layer and the second mask layer, the plurality of openings formed in the second mask layer are a first opening at least partially overlapping with an opening formed in the first mask layer; a second opening that does not overlap the opening formed in the first mask layer and overlaps a region of the one main surface of the first mask layer where no opening is formed; Contains A metal mask characterized by: [Application example 2] The metal mask according to Application Example 1, the first mask layer has a pattern formation region in which the plurality of openings are formed in a predetermined pattern; When viewed from the stacking direction, the first opening of the second mask layer is formed at a position overlapping the pattern formation region of the first mask layer; the second opening of the second mask layer is formed so as to surround the outside of the pattern formation region of the first mask layer; A metal mask characterized by: [Application example 3] The metal mask according to Application Example 1 or Application Example 2, The first mask layer is a first pattern formation region in which the plurality of openings are formed in a predetermined pattern; a second pattern formation region different from the first pattern formation region in which the plurality of openings are formed in a predetermined pattern; a linear region formed between the first pattern formation region and the second pattern formation region, the linear region having no openings; It has When viewed from the stacking direction, the second opening of the second mask layer overlaps with the linear region of the first mask layer and is formed along the center line of the linear region so as to include the center line of the linear region. A metal mask characterized by: [Application example 4] The metal mask according to any one of Application Examples 1 to 3, When viewed from the stacking direction, 90% or more of the linear region overlaps with the second opening in its width direction. A metal mask characterized by: [Application example 5] The metal mask according to any one of Application Examples 1 to 4, when a region in which no openings are formed in the first mask layer is evenly divided into an upstream region and a downstream region along a squeegee direction during printing, when viewed from the stacking direction, a total area of ​​the region overlapped by the second openings of the second mask layer in the upstream region is larger than a total area of ​​the region overlapped by the second openings of the second mask layer in the downstream region. A metal mask characterized by: [Application Example 6] 1. A printing method comprising: A step of preparing a metal mask including: a first mask layer having a pair of main surfaces and a plurality of openings penetrating the pair of main surfaces; and a second mask layer having a plurality of openings formed therein and laminated on one of the main surfaces of the first mask layer; placing a substrate on one of a pair of main surfaces of the second mask layer on which the first mask layer is not laminated; pushing out ink from the other main surface of the first mask layer along a squeegee direction; Equipped with When viewed from a stacking direction of the first mask layer and the second mask layer, the plurality of openings formed in the second mask layer are a first opening at least partially overlapping with an opening formed in the first mask layer; a second opening that does not overlap the opening formed in the first mask layer and overlaps a region of the one main surface of the first mask layer where no opening is formed; Including, when a region in which no openings are formed in the first mask layer is evenly divided into an upstream region and a downstream region along the squeegee direction, a total area of ​​the region overlapped by the second openings of the second mask layer in the upstream region is larger than a total area of ​​the region overlapped by the second openings of the second mask layer in the downstream region when viewed from the stacking direction. A printing method comprising: [Explanation of symbols]

[0048] 1, 1a, 1b, 1c, 1d, 1e, 1f, 1g...Metal mask 10…First mask layer 11, 12...Main surfaces of first mask layer 13, 13c...Openings in the first mask layer 20,20g…Second mask layer 21, 22...Main surfaces of second mask layer 23A, 23Aa, 23Ac, 23Ag…1st opening 23B, 23Ba, 23Bb, 23Bc, 23Bd, 23Be, 23Bf, 23Bg…Second opening BD…Substrate O…center OLg…center line OLr,OLra…Intermediate line PS: solder paste RBL: Polygonal area RG1, RG2, RG1a, RGb, RGc, RGe, RGf…area RG1d…downstream area RG1u…upstream area RPT: Pattern formation region RPT1: First pattern formation region RPT2: Second pattern formation area

Claims

1. A metal mask, a first mask layer having a pair of main surfaces and a plurality of openings penetrating the pair of main surfaces; a second mask layer having a plurality of openings formed therein and laminated on one main surface of the first mask layer; Equipped with When viewed from a stacking direction of the first mask layer and the second mask layer, the plurality of openings formed in the second mask layer are a first opening at least partially overlapping with an opening formed in the first mask layer; a second opening that does not overlap the opening formed in the first mask layer and overlaps a region of the one main surface of the first mask layer where no opening is formed; Contains A metal mask characterized by:

2. 2. The metal mask according to claim 1, the first mask layer has a pattern formation region in which the plurality of openings are formed in a predetermined pattern; When viewed from the stacking direction, the first opening of the second mask layer is formed at a position overlapping the pattern formation region of the first mask layer; the second opening of the second mask layer is formed so as to surround the outside of the pattern formation region of the first mask layer; A metal mask characterized by:

3. 2. The metal mask according to claim 1, The first mask layer is a first pattern formation region in which the plurality of openings are formed in a predetermined pattern; a second pattern formation region different from the first pattern formation region in which the plurality of openings are formed in a predetermined pattern; a linear region formed between the first pattern formation region and the second pattern formation region, the linear region having no openings; It has When viewed from the stacking direction, the second opening of the second mask layer overlaps with the linear region of the first mask layer and is formed along the center line of the linear region so as to include the center line of the linear region. A metal mask characterized by:

4. The metal mask according to claim 3, When viewed from the stacking direction, 90% or more of the linear region overlaps with the second opening in the width direction. A metal mask characterized by:

5. 2. The metal mask according to claim 1, when a region in which no openings are formed in the first mask layer is evenly divided into an upstream region and a downstream region along a squeegee direction during printing, a total area of ​​the region overlapped by the second openings of the second mask layer in the upstream region is larger than a total area of ​​the region overlapped by the second openings of the second mask layer in the downstream region when viewed from the stacking direction. A metal mask characterized by:

6. 1. A printing method comprising: A step of preparing a metal mask including: a first mask layer having a pair of main surfaces and a plurality of openings penetrating the pair of main surfaces; and a second mask layer having a plurality of openings formed therein and laminated on one of the main surfaces of the first mask layer; placing a substrate on one of a pair of main surfaces of the second mask layer on which the first mask layer is not laminated; pushing out ink from the other main surface of the first mask layer along a squeegee direction; Equipped with When viewed from a stacking direction of the first mask layer and the second mask layer, the plurality of openings formed in the second mask layer are a first opening at least partially overlapping with an opening formed in the first mask layer; a second opening that does not overlap the opening formed in the first mask layer and overlaps a region of the one main surface of the first mask layer where no opening is formed; Including, when a region in which no openings are formed in the first mask layer is evenly divided into an upstream region and a downstream region along the squeegee direction, a total area of ​​the region overlapped by the second openings of the second mask layer in the upstream region is larger than a total area of ​​the region overlapped by the second openings of the second mask layer in the downstream region when viewed from the stacking direction. A printing method comprising:

Images