Mask for arrangement

Abstract

The invention provides a mask for arrangement, which is applied to a substrate provided with a protruding wall such as a dam for underfilling, and prevents poor mounting of solder balls due to the fact that the upper end of the protruding wall abuts against the lower surface of a mask main body. This alignment mask is provided with a mask main body (10) in which a plurality of through-holes (12) are formed, and a protruding part (18) that is provided so as to protrude downward from the lower surface (15) of the mask main body (10) and supports the mask main body (10) in a posture separated from the upper surface (17) of a substrate (3). Furthermore, the mask is characterized in that the lower surface (15) of the mask main body (10) is recessed to form a recessed part (19), and the recessed part (19) receives the upper part of the protruding wall (7) protruding upwards from the upper surface (17) of the substrate (3).

Description

Technical Field

[0001] The present invention relates to a mask for arranging solder balls used in the production of solder bumps in a BGA (Ball Grid Array) manner. Background Art

[0002] Conventionally, as a method for forming solder bumps, a BGA (Ball Grid Array) method is known. In this BGA method, bumps are formed through a printing process of coating a flux on electrodes on a substrate such as a wafer, a flexible substrate, or a rigid substrate, an arranging process of arranging solder balls on the flux, and a heating process of heating and melting the solder balls. Moreover, in the above arranging process, as a method for arranging solder balls on the substrate, there is a sprinkling method (vibration method) using a mask. In this sprinkling method, an arranging mask (hereinafter, appropriately abbreviated as "mask") having positioning through-holes through which solder balls can be inserted corresponding to the arrangement pattern of the electrodes on the substrate is used, and the solder balls are mounted on the electrodes of the substrate. Specifically, on the basis of aligning the mask with the substrate in such a manner that the through-holes coincide with the electrodes, the solder balls supplied to the mask are swept using a squeegee, a brush, etc., and one solder ball is inserted into each through-hole. Then, by fixing the solder balls to the flux, the solder balls are temporarily fixed at predetermined positions on the substrate.

[0003] As a well-known example of such an arranging mask, for example, there is the arranging mask disclosed in Patent Document 1. In the mask described in Patent Document 1, a plurality of supporting protrusions are formed on the lower surface of a mask body having through-holes. During the solder ball arranging operation, by bringing the lower surface of the protrusions into contact with the upper surface of the substrate, the opposing interval between the mask body and the substrate can be ensured, thereby preventing the flux coated on the electrodes from adhering to the lower surface of the mask body. An arranging mask having the same structure is also disclosed in Patent Document 2 of the present patent applicant.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2006-287215

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 2008-263053 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] When mounting an electronic component on a substrate using solder bumps, in order to enhance the mechanical strength of the electronic component relative to the substrate, sometimes a liquid resin is coated between the two (the substrate and the electronic component) and cured to form a so-called "underfill". On the surface of the substrate thus formed with underfill, a dam composed of a protruding wall for preventing the liquid resin from flowing out of the coating area is provided in advance and protrudes. When the height dimension of the dam is smaller than the height dimension of the protruding portion, the lower end of the protruding portion can be brought into contact with the upper surface of the substrate, and the alignment mask can be stably placed on the substrate. On the other hand, when the height dimension of the dam is larger than the height dimension of the protruding portion, before the protruding portion comes into contact with the substrate, the upper end of the dam will first touch the lower surface of the mask body, and a gap will be generated between the protruding portion and the substrate. In this case, the opposing interval between the mask body and the substrate will be larger than the preset opposing interval, so the alignment mask cannot hold the solder balls on the inner surface of the through holes, and there may be mounting defects such as mounting the solder balls at positions deviated from the electrodes.

[0010] An object of the present invention is to prevent mounting defects of solder balls due to the upper end of a protruding wall coming into contact with the lower surface of a mask body in an alignment mask applicable to a substrate having a protruding wall such as a dam for underfill.

[0011] Method for solving the problem

[0012] The present invention is directed to an alignment mask that mounts solder balls 2 at predetermined positions on a substrate 3 by sprinkling the solder balls 2 into through holes 12 corresponding to a predetermined alignment pattern. The alignment mask includes a mask body 10 and protruding portions 18. The mask body 10 is formed with a plurality of through holes 12, and the protruding portions 18 protrude downward from the lower surface 15 of the mask body 10 to support the mask body 10 in a posture separated from the upper surface 17 of the substrate 3. And, it is characterized in that a recessed portion 19 is formed in a recessed manner on the lower surface 15 of the mask body 10, and the recessed portion 19 receives the upper part of a protruding wall 7 protruding upward from the upper surface 17 of the substrate 3.

[0013] In the placement posture where the protruding portion 18 is in contact with the upper surface 17 of the substrate 3, a surplus gap G is formed between the outer surface of the protruding wall 7 invading the recessed portion 19 and the bottom surface 20 and the peripheral surface 21 of the recessed portion 19.

[0014] When the depth dimension of the recessed portion 19 is defined as D and the thickness dimension of the mask body 10 is defined as T, the depth dimension D of the recessed portion 19 is preferably set to 80% or less of the thickness dimension T of the mask body 10.

[0015] When the height dimension of the protrusion 18 is defined as H1, the thickness dimension of the mask main body 10 is defined as T, and the sum of the height dimension H1 and the thickness dimension T is defined as the total mask dimension H3, the height dimension H1 of the protrusion 18 is preferably set to 50% or more and 70% or less of the total mask dimension H3.

[0016] On the upper surface 14 of the mask main body 10, a bulging portion 45 for thickening the mask main body 10 is formed in a protruding shape corresponding to the recessed portion 19.

[0017] Advantages of the Invention

[0018] As in the alignment mask of the present invention, when a recessed portion 19 is formed in a concave shape on the lower surface of the mask main body 10, and the upper portion of the protruding wall 7 protruding upward from the upper surface 17 of the substrate 3 is received in the recessed portion 19, even for a substrate 3 in which the height dimension H2 of the protruding wall 7 exceeds the height dimension H1 of the protrusion 18, by receiving the protruding wall 7 in the recessed portion 19, it is possible to prevent the lower surface 15 of the mask main body 10 from coming into contact with the upper end of the protruding wall 7, that is, to prevent the mask main body 10 from hitting the protruding wall 7 first and being received. As described above, according to the mask 1 of the present invention, the front end of the protrusion 18 can be reliably brought into contact with the upper surface 17 of the substrate 3, so that the alignment operation of the solder balls 2 can be performed while maintaining the opposing interval between the lower surface 15 of the mask main body 10 and the upper surface 17 of the substrate 3 at a preset distance. In addition, according to the present invention, it is possible to prevent poor mounting of the solder balls 2 due to the upper end of the protruding wall 7 coming into contact with the lower surface of the mask main body 10. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a longitudinal sectional view showing a main part of the alignment mask according to the first embodiment of the present invention.

[0020] Figure 2 is a perspective view showing the whole of the alignment mask.

[0021] Figure 3 Among them, (a) to (d) are longitudinal sectional views showing a method of manufacturing a screen printing mask according to the first embodiment of the present invention.

[0022] Figure 4 Among them, (a) to (d) are longitudinal sectional views showing a method of manufacturing a screen printing mask according to the first embodiment of the present invention.

[0023] Figure 5 Among them, (a) to (d) are longitudinal sectional views showing a method of manufacturing a screen printing mask according to the first embodiment of the present invention.

[0024] Figure 6 is a longitudinal sectional view showing a main part of the alignment mask according to the second embodiment of the present invention.

[0025] Explanation of Reference Numerals

[0026] 1: Alignment mask, 2: Solder ball, 3: Substrate, 7: Protruding wall (dam), 10: Mask body, 12: Through hole, 15: Lower surface of the mask body, 17: Upper surface of the substrate, 18: Protrusion, 19: Depression, 45: Bulging portion, D: Depth dimension of the depression, G: Clearance, H1: Height dimension of the protrusion, H3: Total mask size, T: Thickness dimension of the mask body. Detailed Description of the Invention

[0027] (First Embodiment)

[0028] Figures 1 to 5 This shows a first embodiment of the alignment mask of the present invention. It should be noted that the up and down directions correspond to the thickness direction of the alignment mask, and the dimensions such as thickness in each figure do not represent the actual situation but are schematically shown. This alignment mask (hereinafter simply referred to as the mask) 1 is used in the alignment operation of the solder balls 2 in the production of solder bumps in the BGA method.

[0029] In Figure 2 , the symbol 3 represents the substrate (workpiece) on which the solder balls 2 of the mask 1 are mounted. This substrate 3 is, for example, a substrate in which a plurality of semiconductor chips 5 are mounted on a base 4 of a glass epoxy substrate, wired by wire bonding, and then transfer molded and sealed. On the upper surface of the substrate 3, electrodes 6 as input / output terminals are formed in a predetermined pattern so as to surround the semiconductor chips 5. Further, on the upper surface of the substrate 3, a dam (protruding wall) 7 is formed so as to protrude upward so as to surround the semiconductor chips 5 and the electrodes 6. The dam 7 is composed of a four-sided frame-shaped protrusion formed simultaneously with the production of the substrate 3, and is used to block the flow of the liquid resin (liquid resin for forming underfill) applied between the substrate 3 and the electronic component so that it does not flow excessively when forming the underfill. The underfill is provided to improve the bonding strength between the substrate 3 and the electronic component mounted on the substrate 3 using solder bumps. On the electrodes 6, a flux 8 for temporarily fixing and adhering to hold the solder balls 2 is applied in the printing process before the alignment operation of the solder balls 2. The dam 7 can also block the movement of the flux and solder (paste, balls, peeled bumps, etc.). The shape of the dam 7 can also be a lattice shape, an L shape, or a pair of longitudinal beams (cross bars) shape.

[0030] As Figure 2As shown, the mask 1 is composed of a mask body 10 and a frame 11 joined in a manner surrounding the mask body 10. The mask body 10 is formed by electroforming using copper, nickel, nickel alloys such as nickel-cobalt, or other electrodeposited metals as raw materials. The frame 11 is composed of a four-sided frame, and its outer peripheral shape is the same as that of the mask body 10. The metal constituting the frame 11 is preferably a metal (low thermal expansion material) with a lower coefficient of thermal expansion than the metal constituting the mask body 10, such as 42 alloy, invar alloy material, SUS430, etc., as the raw material. On the disk surface of the mask body 10 surrounded by the frame 11, a plurality of pattern regions 13 are formed corresponding to each semiconductor chip 5. The pattern region 13 has a plurality of independent through-holes 12 for inserting solder balls 2. The frame 11 serves both as a holding member for holding the mask body 10 and as a reinforcing member for strengthening the mask body 10.

[0031] As Figure 1 shown, each through-hole 12 is composed of a linear circular hole that penetrates the mask body 10 in the vertical direction (thickness direction) and has openings on the upper and lower surfaces 14 and 15, and is formed at a position corresponding to the arrangement pattern of the electrodes 6 of each semiconductor chip 5 in the substrate 3. The solder ball 2 is a sphere with a diameter d of 100 μm or less. In order to receive and hold the solder ball 2 by the inner surface 16 of the hole, the opening diameter of each through-hole 12 has a size slightly larger than the diameter d of the solder ball 2.

[0032] During the arrangement operation of the solder balls 2, the mask 1 is placed on the substrate 3. At this time, in order to support the mask body 10 in a posture floating away from the upper surface 17 of the substrate 3, a protrusion 18 is provided on the lower surface 15 of the mask body 10. Specifically, as Figure 1 shown, on the lower surface 15 side of the mask body 10, that is, on the opposing surface side facing the substrate 3, a plurality of protrusions 18 for ensuring the opposing interval with the substrate 3 are integrally formed with the mask body 10 in a downward protruding manner. Each protrusion 18 is formed in a cylindrical shape with a height dimension H1 approximately the same as or slightly smaller than half (radius) of the diameter d of the solder ball 2. The protrusions 18 are not limited to being formed independently, and can also be provided in a lattice frame shape surrounding the pattern region 13. It should be noted that the protrusions 18 are integrally formed with the mask body 10, but a separately formed member can also be integrally joined with the mask body 10. The shape of the protrusions 18 is not limited to a columnar shape, and can also be a rib shape.

[0033] In the height dimension H2 of the dam 7 (refer to Figure 1)When it is formed to be larger than the height dimension H1 of the protrusion 18, at the portion of the mask 1 placed on the substrate 3 corresponding to the dam 7, before the lower end of the protrusion 18 contacts the upper surface of the substrate 3, the lower surface 15 of the mask body 10 will contact the upper end of the dam 7. Thus, the mask body 10 is received by the dam 7. In this way, when the mask body 10 is partially received by the dam 7, the lower end of the protrusion 18 does not contact the upper surface 17 of the substrate 3. Therefore, the opposing interval between the lower surface 15 of the mask body 10 and the upper surface 17 of the substrate 3 will be greater than the preset distance. In this way, if the distance of the opposing interval becomes larger, during the arrangement operation of the solder balls 2, the solder balls 2 cannot be held on the inner surface 16 of the through hole 12, and the solder balls 2 may be mounted at positions deviated from the arrangement positions of the electrodes 6. Therefore, in the mask 1 of the present embodiment, a structure is provided for avoiding the contact between the mask body 10 and the dam 7 during the arrangement operation of the solder balls 2.

[0034] Specifically, as Figure 1 shown, in order to avoid the contact between the mask body 10 and the dam 7 when the mask 1 is placed on the substrate 3, a recessed portion 19 for receiving the upper part of the dam 7 is formed in a recessed shape on the lower surface 15 of the mask body 10 corresponding to the dam 7. The recessed portion 19 is composed of a four-sided frame-shaped groove that is open on the lower surface 15 side of the mask body 10 and has an opening shape that is one circle larger than the dam 7. The shape of the groove cross-section of the recessed portion 19 is rectangular. The depth dimension D of the recessed portion 19 is preferably set to a dimension such that when the dam 7 invades the recessed portion 19, the bottom surface (upper surface) 20 of the recessed portion 19 does not contact the upper end surface of the dam 7. In the present embodiment, the depth dimension D of the recessed portion 19 is set to a dimension that does not contact the dam 7. Thus, a surplus gap G is formed between the outer surface of the dam 7 invading the recessed portion 19 and the bottom surface 20 and the peripheral surface 21 (the inner surface of the recessed portion 19) of the recessed portion 19.

[0035] The above-mentioned surplus gap G is not necessary, and it may also be a form in which the recessed portion 19 is fitted with the dam 7. In this case, it can contribute to the improvement of the positioning accuracy of the mask 1 with respect to the substrate 3 and the improvement of the placement stability. The shape of the groove cross-section of the recessed portion 19 is not limited to a rectangle, and it may also be a trapezoid, a polygon, or a semi-circle. The groove constituting the recessed portion 19 may also be in a form in which at least a part of the bottom surface 20 communicates with the upper surface 14 of the mask body 10. In this case, the opening diameter of the communicating portion is smaller than the diameter d of the solder ball 2. The recessed portion 19 can also be used as an avoidance portion for the objects to be placed (for example, semiconductor chips 5, bumps, etc.) placed on the substrate 3.

[0036] The recessed portion 19 preferably has a depth dimension D of the recessed portion 19 formed to be 80% or less of the thickness dimension T of the mask body 10. This is because if the depth dimension D of the recessed portion 19 exceeds 80% of the thickness dimension T of the mask body 10, the strength of the portion corresponding to the recessed portion 19 is insufficient, and the durability of the mask body 10 may be reduced. More preferably, the depth dimension D of the recessed portion 19 is set to be 5% or more and 80% or less of the thickness dimension T of the mask body 10. In the present embodiment, the depth dimension D of the recessed portion 19 is set to 60% of the thickness dimension T of the mask body 10.

[0037] In addition, for the protruding portion 18, the height dimension H1 of the protruding portion 18 is preferably set to be 50% or more and 70% or less of the total mask dimension H3, which is the sum of the thickness dimension T of the mask body 10 and the height dimension H1 of the protruding portion 18 (refer to Figure 1 ). This is because if the height dimension H1 of the protruding portion 18 is less than 50% of the total mask dimension H3, the possibility that the flux 8 applied to the electrode 6 adheres to the lower surface 15 of the mask body 10 increases. If the height dimension H1 of the protruding portion 18 exceeds 70% of the total mask dimension H3, the load acting on the protruding portion 18 when the mask 1 is placed on the substrate 3 becomes large, and the durability of the mask 1 is reduced. In the present embodiment, the height dimension H1 of the protruding portion 18 is set to 55% of the total mask dimension H3. The total mask dimension H3 of the alignment mask is set to be about 30 to 120 μm.

[0038] For the alignment operation of the solder balls 2, first, after aligning the mask 1 with respect to the substrate 3, the mask 1 is placed on the substrate 3. At this time, by receiving the dam 7 in the recessed portion 19, contact with the lower surface 15 of the mask body 10 is avoided, and the lower end of the protruding portion 18 comes into contact with the upper surface 17 of the substrate 3. According to the above, the mask 1 can be stably placed on the substrate 3 in a state where an appropriate opposing interval is formed between the lower surface 15 of the mask body 10 and the upper surface 17 of the substrate 3.

[0039] Next, a plurality of solder balls 2 are supplied onto the mask 1, and the solder balls 2 are dispersed on the mask 1 using a squeegee brush, and the solder balls 2 are individually inserted into the through holes 12. Since the height dimension H1 of the protruding portion 18 is set to be slightly smaller than half (radius) of the diameter d of the solder ball 2, the central portion in the vertical direction of the spherical circumferential surface having the largest horizontal diameter of the solder ball 2 inserted into the through hole 12 is received by the inner surface 16 of the hole of the through hole 12, so that it is positioned with respect to the electrode 6. The solder balls 2 inserted into the through holes 12 are temporarily fixed and adhered to the flux 8. Finally, by lifting the mask 1 vertically from the substrate 3 and removing it, the solder balls 2 are mounted on the electrodes 6, and the alignment operation is completed.

[0040] Figures 3 to 5 An example of the manufacturing method of the mask 1 of the present embodiment is shown. First, asFigure 3 As shown in (a) of Figure 3 , a first photoresist layer 27 is formed on the surface of a conductive master mold 26 made of, for example, stainless steel or brass, and a first pattern film 28 having a light-transmitting hole 28a corresponding to the protrusion 18 is bonded to the first photoresist layer 27. The first photoresist layer 27 is formed by laminating one or several negative photosensitive dry film resists to a predetermined height and thermocompression bonding. Next, ultraviolet light is irradiated onto the first photoresist layer 27 with an ultraviolet lamp 29 for exposure. After performing development and drying processes, the unexposed portions are dissolved and removed, thereby forming a first pattern resist 30 composed of linear first resist bodies 30a corresponding to the protrusions 18 as shown in

[0041] Next, the master mold 26 is placed in an electroforming bath (plating bath) built under predetermined conditions. As shown in Figure 3 , within the height range of the first resist bodies 30a, an electrodeposited metal such as nickel alloy is electroformed (plated) on the surface of the master mold 26 not covered by the first resist bodies 30a. After that, the first pattern resist 30 is dissolved and removed, thereby forming a first electroformed layer 31 as shown in Figure 3 . The formation height of the first electroformed layer 31 is consistent with the height dimension H1 of the protrusion 18. It should be noted that the first pattern resist 30 can also directly enter the next process without being removed. In this case, the first pattern resist 30 and the second pattern resist 34 (described later) can be dissolved and removed together.

[0042] Next, as shown in Figure 4 , a second photoresist layer 32 is formed on the surface of the master mold 26 not covered by the first electroformed layer 31 and on the surface of the first electroformed layer 31, and a second pattern film 33 having a light-transmitting hole 33a corresponding to the recess 19 is bonded to the second photoresist layer 32. The second photoresist layer 32 is formed by the same method as the previous first photoresist layer 27. Next, ultraviolet light is irradiated onto the second photoresist layer 32 with the ultraviolet lamp 29 for exposure. After performing development and drying processes, the unexposed portions are dissolved and removed, thereby forming a second pattern resist 34 composed of second resist bodies 34a having linear holes corresponding to the recesses 19 as shown in Figure 4 .

[0043] Next, the master mold 26 is placed in an electroforming bath (plating bath) built under predetermined conditions. As shown in Figure 4As shown in (c), within the height range of the second resist 34a, electro-deposited metals such as nickel alloy are electroformed (plated) on the surface of the first electroformed layer 31 that is not covered by the second resist 34a. After that, the second pattern resist 34 is dissolved and removed, thereby forming on the first electroformed layer 31 Figure 4 a second electroformed layer 35 as shown in (d). The formation height of the second electroformed layer 35 is consistent with the depth dimension D of the recess 19. It should be noted that in the above, the second electroformed layer 35 (metal) is formed as a structure corresponding to the recess 19, but this metal can also be replaced with resin (resist).

[0044] Next, as Figure 5 shown in (a), a third photoresist layer 36 is formed on the surface of the master mold 26 that is not covered by the first electroformed layer 31 and on the surfaces of the two electroformed layers 31 and 35. A third pattern film 37 having a light-transmitting hole 37a corresponding to the outer shape of the through hole 12 and the mask main body 10 is bonded to the third photoresist layer 36. The third photoresist layer 36 is formed by the same method as the previous first photoresist layer 27. Next, ultraviolet light is irradiated by the ultraviolet lamp 29 to expose the third photoresist layer 36. After performing the processes of development and drying, the unexposed portion is dissolved and removed, thereby forming on the first electroformed layer 31 Figure 5 a third pattern resist 38 composed of linear third resists 38a corresponding to the through hole 12 and the mask main body 10 as shown in (b). It should be noted that the third resist 38a for forming a hole corresponding to the outer shape of the mask main body 10 is not shown.

[0045] Next, after performing a peeling treatment or a covering plating on the surface of the master mold 26 that is not covered by the first electroformed layer 31 and on the surfaces of the two electroformed layers 31 and 35, the master mold 26 is placed in an electroforming bath (plating bath) built under predetermined conditions. Within the height range of the third resist 38a, electro-deposited metals such as nickel alloy are electroformed (plated) on the surface of the master mold 26 that is not covered by the first electroformed layer 31 and on the surfaces of the two electroformed layers 31 and 35. A third electroformed layer 39 is formed on the upper surfaces of the master mold 26, the first electroformed layer 31, and the second electroformed layer 35. Furthermore, after forming the third electroformed layer 39, a polishing treatment is performed on the upper surfaces of the third electroformed layer 39 and the third resist 38a. As Figure 5 shown in (c), the upper surface of the third electroformed layer 39 is finished to be flat. Next, by peeling the third electroformed layer 39 from the master mold 26 and the two electroformed layers 31 and 35, Figure 5A mask body 10 as shown in (d) thereof, which has a protrusion 18 protruding from the lower surface 15 and a recess 19 formed in a concave shape, and a through-hole 12 formed in a penetrating shape on the disk surface. The formation thickness of the third electroformed layer 39 formed on the upper surface of the first electroformed layer 31 is consistent with the thickness dimension T of the mask body 10. Finally, by integrally fixing the frame 11 to the upper surface 14 of the mask body 10, a mask 1 as shown in Figure 2 can be obtained. It should be noted that after forming the third electroformed layer 39, a polishing process can be performed on its upper surface as needed to improve the flatness of the upper surface 14 of the mask body 10.

[0046] (Second Embodiment)

[0047] Figure 6 This shows a second embodiment of the alignment mask of the present invention. In this embodiment, a bulging portion 45 for realizing local thickening of the mask body 10 is provided on the upper surface 14 of the mask body 10, which is different from the previous first embodiment. The bulging portion 45 is formed to protrude toward the upper surface 14 side of the mask body 10 corresponding to the recess 19. By providing the bulging portion 45 on the upper surface 14 of the mask body 10, the thickness from the bottom surface 20 of the recess 19 to the upper surface 14 of the mask body 10 can be increased, and a reduction in the structural strength of the mask body 10 due to the formation of the recess 19 can be suppressed. In addition, even for the mask body 10 formed with the recess 19, by providing the bulging portion 45, its thickness can be uniformly formed over the entire mask body 10.

[0048] The mask 1 of this embodiment is manufactured through substantially the same processes as the manufacturing method of the previous first embodiment (refer to Figures 3 to 5 ), the difference being that no polishing process is performed after forming the third electroformed layer 39. Since electroforming (plating) has a uniform growth amount in its thickness direction, a step difference will occur between the portion corresponding to the first electroformed layer 31 and the portion corresponding to the second electroformed layer 35, and a bulge that becomes the bulging portion 45 is formed on the upper surface of the third electroformed layer 39. It should be noted that as needed, during the electroforming (plating) of the third electroformed layer 39, by controlling the current density of the portion corresponding to the second electroformed layer 35 to be increased while performing electroforming (plating), the portion corresponding to the second electroformed layer 35 can be formed thicker than other portions. The rest is the same as the first embodiment, so the same reference numerals are assigned to the same components and their descriptions are omitted.

[0049] In the mask 1 of each of the above-described embodiments, a recessed portion 19 for receiving the upper portion of the dam 7 is formed in a recessed shape on the lower surface 15 of the mask body 10. Therefore, even for a substrate 3 in which the height dimension H2 of the dam 7 exceeds the height dimension H1 of the protrusion 18, by receiving the dam 7 in the recessed portion 19, it is possible to prevent the lower surface 15 of the mask body 10 from coming into contact with the upper end of the dam 7. That is, it is possible to prevent the mask body 10 from first hitting the dam 7 and being received. As described above, according to this mask 1, the front end of the protrusion 18 can be reliably brought into contact with the upper surface 17 of the substrate 3. Therefore, while maintaining the opposing interval between the lower surface 15 of the mask body 10 and the upper surface 17 of the substrate 3 at a preset distance, the arrangement operation of the solder balls 2 can be performed. In addition, according to this mask 1, it is possible to prevent defective mounting of the solder balls 2 due to the upper end of the dam 7 coming into contact with the lower surface 15 of the mask body 10.

[0050] In the mounting posture in which the protrusion 18 is in contact with the upper surface 17 of the substrate 3, a surplus gap G is formed between the outer surface of the dam 7 that enters the recessed portion 19 and the bottom surface 20 and the peripheral surface 21 of the recessed portion 19. Therefore, it is possible to suppress contact between the bottom surface 20 and the peripheral surface 21 of the recessed portion 19 and the outer surface of the dam 7, and the front end of the protrusion 18 can be more reliably brought into contact with the upper surface 17 of the substrate 3.

[0051] The depth dimension D of the recessed portion 19 is preferably set to 80% or less of the thickness dimension T of the mask body 10. Thereby, it is possible to suppress a decrease in the durability of the mask body 10 caused by insufficient strength of the portion of the mask body 10 corresponding to the recessed portion 19.

[0052] The height dimension H1 of the protrusion 18 is preferably set to 50% or more of the total mask dimension H3. Thereby, it is possible to prevent the flux 8 from adhering to the lower surface 15 of the mask body 10 and the inner surface of the through hole 12. In addition. The height dimension H1 of the protrusion 18 is preferably set to 70% or less of the total mask dimension H3. Thereby, it is possible to suppress a decrease in the durability of the mask 1 caused by an increase in the load acting on the protrusion 18.

[0053] According to the mask 1 in which a bulging portion 45 is formed on the upper surface 14 of the mask body 10 corresponding to the recessed portion 19, it is possible to prevent the thickness dimension T of the mask body 10 from being locally formed into a thin wall. Therefore, it is possible to suppress a decrease in the structural strength of the mask body 10 caused by the formation of the recessed portion 19.

[0054] The alignment mask according to the present invention can be applied to Goal 9 (Building the infrastructure for industry and innovation) and Goal 12 (Responsible consumption and production) of the Sustainable Development Goals (SDGs) advocated by the United Nations. In addition, the structure of the alignment mask according to the present invention can also be applied to various metal masks such as a solder ball adsorption mask, a screen printing mask, or an evaporation mask.

Claims

1. An arrangement mask for placing solder balls, which is an arrangement mask for placing solder balls (2) at predetermined positions on a substrate (3) by sprinkling solder balls (2) into through holes (12) corresponding to a predetermined arrangement pattern, and is characterized in that the arrangement mask includes a mask body (10) and a protrusion (18). The mask body (10) is formed with a plurality of through holes (12). The protrusion (18) protrudes downward from the lower surface (15) of the mask body (10) to support the mask body (10) in a posture separated from the upper surface (17) of the substrate (3). A recess (19) is formed by recessing the lower surface (15) of the mask body (10), and the upper part of a protruding wall (7) protruding upward from the upper surface (17) of the substrate (3) is received in the recess (19).

2. The arrangement mask according to claim 1, wherein in a placement posture where the protrusion (18) abuts against the upper surface (17) of the substrate (3), a surplus gap (G) is formed between the outer surface of the protruding wall (7) invading the recess (19) and the bottom surface (20) and the peripheral surface (21) of the recess (19).

3. The arrangement mask according to claim 1, wherein when the depth dimension of the recess (19) is defined as D and the thickness dimension of the mask body (10) is defined as T, the depth dimension D of the recess (19) is set to 80% or less of the thickness dimension T of the mask body (10).

4. The arrangement mask according to claim 1, wherein when the height dimension of the protrusion (18) is defined as H1, the thickness dimension of the mask body (10) is defined as T, and the sum of the height dimension H1 and the thickness dimension T is defined as the total mask size H3, the height dimension H1 of the protrusion (18) is set to 50% or more and 70% or less of the total mask size H3.

5. The arrangement mask according to claim 1, wherein on the upper surface (14) of the mask body (10), a bulging portion (45) for thickening the mask body (10) is formed in a protruding shape corresponding to the recess (19).

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