Ball-shaped member mounting mask and ball-shaped member mounting method

Abstract

To prevent a ball-shaped component from being left unmounted on a wiring board.SOLUTION: A ball-shaped member mounting mask 1 according to an embodiment includes a flat shielding portion 2 and an opening 3 that penetrates the shielding portion 2 and allows a ball-shaped member BM to be placed on a wiring board to pass through. An opening 3 is surrounded by a portion 31 of a wall surface surrounding the opening 3 that can come into contact with the ball-shaped member BM passing through the opening 3, and includes an insertion portion 4 that allows the ball-shaped member BM to pass through, and a plurality of extension portions 5 that are formed integrally with the insertion portion 4 so as to protrude outward from the periphery of the insertion portion 4 and penetrate the shielding portion 2, and the extension portions 5 are formed around the insertion portion 4 so as to restrict the ball-shaped members BM passing through the opening 3 from entering the interior of the extension portions 5.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a ball-shaped member mounting mask and a ball-shaped member mounting method. [Background technology]

[0002] Patent Document 1 discloses a ball alignment mask used to mount solder balls on electrodes of a printed wiring board. Solder balls supplied onto the ball alignment mask, which has multiple openings, are collected directly below the openings of a mounting cylinder positioned above the ball alignment mask by suctioning air. The solder balls then move over the ball alignment mask as the mounting cylinder moves horizontally, and are dropped onto connection pads on the printed wiring board through each opening in the ball alignment mask. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-74002 Summary of the Invention [Problem to be solved by the invention]

[0004] In the ball alignment mask disclosed in Patent Document 1, solder balls may not be able to enter each of the multiple openings. As a result, solder balls may not be introduced into some openings, resulting in connection pads on the printed wiring board with no solder balls. Connection pads with no solder balls may reduce the quality of the printed wiring board and cause problems such as poor connections between the printed wiring board and external components. [Means for solving the problem]

[0005] The ball-shaped member mounting mask of the present invention has a flat shielding portion and an opening that penetrates the shielding portion and allows a ball-shaped member to be placed on a wiring board to pass through. The opening is surrounded by a portion of a wall surface that surrounds the opening and that can come into contact with the ball-shaped member passing through the opening, and has an insertion portion that allows the ball-shaped member to pass through, and a plurality of extension portions that are integral with the insertion portion and protrude outward from the periphery of the insertion portion and penetrate the shielding portion, and the extension portions are provided around the insertion portion so as to restrict the ball-shaped member passing through the opening from entering the extension portion.

[0006] A method for mounting a ball-shaped member of the present invention includes preparing a mask having an opening and placing a ball-shaped member on a surface of a wiring board through the opening. The opening is surrounded by a portion of a wall surface surrounding the opening that can come into contact with the ball-shaped member passing through the opening, and has an insertion portion through which the ball-shaped member passes, and a plurality of extension portions that are integral with the insertion portion and protrude outward from the periphery of the insertion portion and penetrate a shielding portion of the mask, and the extension portions are provided around the insertion portion so as to restrict penetration of the ball-shaped member passing through the opening into the extension portion.

[0007] According to an embodiment of the present invention, it may be possible to prevent ball-shaped members, such as solder balls, from being left unmounted on a wiring board while maintaining the accuracy of the mounting position of the ball-shaped members, such as solder balls, mounted on the wiring board. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a plan view showing an example of the overall structure of a ball-shaped member mounted mask according to an embodiment of the present invention. [Figure 2] FIG. 4 is a plan view showing an example of an opening of the ball-shaped member mounting mask according to the embodiment. [Figure 3A] Cross-sectional view along line IIIA-IIIA in Figure 2. [Figure 3B] Cross-sectional view taken along line IIIB-IIIB in Figure 2. [Figure 4] 10 is a cross-sectional view showing a ball-shaped member located at the boundary between the shielding portion and the opening of the ball-shaped member mounted mask according to the embodiment. FIG. [Figure 5A] FIG. 10 is a plan view showing the ball-shaped members slightly entering the expanded portions of the openings of the mask equipped with the ball-shaped members according to the embodiment. [Figure 5B] FIG. 5B is a cross-sectional view taken along line VB-VB in FIG. 5A. [Figure 5C] FIG. 5B is a cross-sectional view taken along line VC-VC in FIG. 5A. [Figure 6A] FIG. 10 is a plan view showing a first modified example of the openings of the ball-shaped member mounted mask of the embodiment. [Figure 6B] FIG. 10 is a plan view showing a second modified example of the openings of the ball-shaped member mounted mask of the embodiment. [Figure 6C] FIG. 10 is a plan view showing a third modified example of the openings of the ball-shaped member mounted mask of the embodiment. [Figure 6D] FIG. 10 is a plan view showing a fourth modified example of the openings of the ball-shaped member mounted mask of the embodiment. [Figure 7A] 5A and 5B are cross-sectional views showing an example of a method for mounting the ball-shaped members according to the embodiment. [Figure 7B] 5A and 5B are cross-sectional views showing an example of a method for mounting the ball-shaped members according to the embodiment. [Figure 7C] 10A and 10B are plan views showing an example of a method for mounting the ball-shaped members according to the embodiment. [Figure 7D] 5A and 5B are cross-sectional views showing an example of a method for mounting the ball-shaped members according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] A ball-shaped member mounted mask according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 illustrates the overall structure of a ball-shaped member mounted mask 1, which is an example of a ball-shaped member mounted mask according to an embodiment. FIG. 2 illustrates a plan view of an example of an opening 3 included in the ball-shaped member mounted mask 1. FIG. 3A illustrates a cross section of the opening 3 taken along line IIIA-IIIA in FIG. 2, together with the ball-shaped member BM passing through the opening 3. FIG. 3B illustrates a cross section of the opening 3 taken along line IIIB-IIIB in FIG. 2, together with the ball-shaped member BM. Note that the ball-shaped member mounted mask 1 in FIG. 1 is merely an example of a ball-shaped member mounted mask according to an embodiment. The ball-shaped member mounted mask according to an embodiment may have any number of openings or any number of opening groups each consisting of a plurality of openings. The opening 3 illustrated in FIG. 2 is merely an example of an opening that may be included in the ball-shaped member mounted mask according to an embodiment. The ball-shaped member mounted mask according to an embodiment may have a variety of planar shapes, as shown in FIGS. 6A to 6D, which will be referred to later. That is, the configuration of the ball-shaped member mounted mask of the embodiment is not limited to the configuration of the ball-shaped member mounted mask 1 of Figure 1, and the planar shape of the opening of the ball-shaped member mounted mask of the embodiment is not limited to the planar shape of the opening 3 of Figure 2.

[0010] <Overall configuration of the ball-shaped member mounted mask according to the embodiment> As shown in FIG. 1, the ball-shaped member-mounted mask 1 of the embodiment includes a shielding portion 2 and a plurality of openings 3. The ball-shaped member-mounted mask of the embodiment will hereinafter also be referred to simply as a "ball mask." Accordingly, the ball-shaped member-mounted mask 1 will also be simply referred to as a "ball mask 1." The shielding portion 2 has a flat plate-like shape. In the example of FIG. 1, the ball mask 1 has a rectangular frame FB made of, for example, aluminum at its periphery. The periphery of the shielding portion 2 is fixed to the frame FB so that an appropriate tension is applied to the shielding portion 2. The ball mask 1 has a first surface 1A perpendicular to the thickness direction of the flat plate-shaped shielding portion 2 and a second surface 1B (see FIG. 3A) opposite the first surface 1A. The plurality of openings 3 penetrate the shielding portion 2 in the thickness direction of the shielding portion 2, i.e., in a direction substantially perpendicular to the first surface 1A and the second surface 1B.

[0011] The ball mask 1 in Fig. 1 has an opening group 3G consisting of a group of openings from among the plurality of openings 3. The ball mask 1 has a total of four opening groups 3G, arranged two by two vertically and two by two horizontally. By inserting a ball-shaped member BM (see Fig. 2) into each opening 3 in each opening group 3G, a plurality of ball-shaped members BM are mounted on four wiring boards (not shown). In other words, the ball mask 1 in Fig. 1 is used for an editing board in which four individual wiring boards are arranged two by two vertically and two by two horizontally.

[0012] The ball mask of the embodiment exemplified by ball mask 1 is formed of, for example, any metal. The metal constituting the ball mask of the embodiment is not particularly limited, and may be, for example, stainless steel, a copper alloy, or a nickel alloy. The ball mask of the embodiment can be formed by a general method for manufacturing a ball-shaped member mounting mask. For example, the ball mask of the embodiment can be manufactured by forming desired openings by etching the metal film or metal foil exemplified above. Alternatively, the ball mask of the embodiment may be formed by depositing a metal material to a predetermined thickness by plating, sputtering, or the like, while predetermined areas corresponding to openings 3, etc., are masked.

[0013] When the ball mask 1 is used, each opening 3 allows a ball-shaped member BM to pass through, which is to be placed on a wiring board (not shown). The ball-shaped member BM passes through the opening 3 and is mounted on a wiring board (not shown). The ball-shaped member mounted on a wiring board using the ball mask of the embodiment is made of, for example, solder, metal such as gold, nickel, or copper, or an alloy thereof. The ball-shaped member is primarily made of a conductive material, but may also be made of an insulating material with a conductive coating on its surface. Note that "ball-shaped" does not necessarily mean a perfectly spherical shape. "Ball-shaped" means a shape that allows an object placed on a horizontal plane to roll without slipping when the plane is tilted.

[0014] <Ball-shaped member movement restriction within opening> As shown in Figures 2, 3A, and 3B, the opening 3 has an insertion portion 4 through which the ball-shaped member BM passes and a plurality of extension portions 5 provided around the insertion portion 4. In Figure 2, the ball-shaped member BM is indicated by a dashed line. Each extension portion 5 is provided so as to protrude from the periphery of the insertion portion 4 to the outside of the insertion portion 4. Each extension portion 5 is formed integrally with the insertion portion 4 and penetrates the shielding portion 2 together with the insertion portion 4. The extension portions 5 make the area of ​​the opening 3 larger than the area of ​​the insertion portion 4 in a planar view. Therefore, the extension portions 5 make the volume of the opening 3 larger than the volume of the insertion portion 4. Note that "planar view" means that the object is viewed with a line of sight along the thickness direction of the ball mask of the embodiment.

[0015] In the example of FIG. 2, the opening 3 has six extension portions 5. Two of the six extension portions 5 face each other in the first direction X. Two of the remaining four extension portions 5 face each other in a second direction XP that forms an angle of 60 degrees with the first direction X, and the remaining two face each other in a third direction XM that forms an angle of 60 degrees with the second direction XP. In the example of FIG. 2, the six extension portions 5 are provided along the periphery of the insertion portion 4 at approximately regular intervals between each other in the circumferential direction C of the insertion portion 4.

[0016] The insertion portion 4 through which the ball-shaped member BM passes has an overall cylindrical shape and therefore has a substantially circular shape in a plan view. As shown in FIG. 2 , the insertion portion 4 is a portion surrounded by portions of the wall surface surrounding the opening 3 that can come into contact with the ball-shaped member BM passing through the opening 3. In the example shown in FIG. 2 , portions 31 of the wall surface surrounding the opening 3 between adjacent extension portions 5 in the circumferential direction C of the opening 3 can come into contact with the ball-shaped member BM. The portions 31 are portions that restrict the movement of the ball-shaped member BM to the region outside the opening 3 by contacting the ball-shaped member BM, and are hereinafter also referred to as "restriction portions 31." In a plan view, a virtual line segment LS can be imagined connecting two adjacent restriction portions 31 along the outer periphery of the ball-shaped member BM passing through the opening 3. The region that overlaps in a plan view with the circle formed by connecting each restriction portion 31 and each virtual line segment LS in each opening 3 is the insertion portion 4 of the opening 3. Each imaginary line segment LS indicates a part of the outer edge of the insertion portion 4 that would be visible if the extension portion 5 were not provided. In other words, each imaginary line segment LS indicates a part of the outer edge of a conventional opening that does not have the extension portion 5 provided.

[0017] On the other hand, each expansion portion 5 is provided around the insertion portion 4 so as to restrict the ball-shaped member BM passing through the opening 3 from entering the interior of the expansion portion 5. That is, in a plan view, the linear distance between one end E1 and the other end E2 of each expansion portion 5 is smaller than the diameter of the ball-shaped member BM. In other words, the distance between the tangent line at the one end E1 side of the expansion portion 5 and the tangent line at the other end E2 side of the wall surface of the opening 3 facing the expansion portion 5 and the wall surface facing the insertion portion 4 is smaller than the diameter of the ball-shaped member BM. Therefore, the ball-shaped member BM is restricted from entering the interior of each expansion portion 5. That is, in a plan view, the movement of the ball-shaped member BM toward the expansion portion 5 side relative to the insertion portion 4 is restricted. The ball-shaped member BM is prevented from entering the expansion portion 5.

[0018] As shown in FIG. 3A, the width WH of the opening 3 in a cross section passing through the two opposing expansion portions 5 is made wider than the width WI of the insertion portion 4 by the expansion portions 5. Note that the two-dot chain line in FIG. 3A is an imaginary line segment LS that indicates part of the outer edge of the insertion portion 4 as would be visible if the expansion portions 5 were not provided, similar to the two-dot chain line in FIG. 2. The solid line inside the two imaginary line segments LS is the boundary line between the wall surface facing the expansion portions 5 and the wall surface facing the insertion portion 4, as shown at one end E1 in FIG. 2. Because the width is made wider by the expansion portions 5, the width WH of the opening 3 in a cross section passing through the two opposing expansion portions 5 shown in FIG. 3A is greater than the diameter of the ball-shaped member BM passing through the opening 3 and is also greater than the distance between the two imaginary line segments LS (the width WI of the insertion portion 4).

[0019] However, as shown in FIG. 3B, the movement of the ball-shaped member BM in the opposing direction of the two opposing limiting portions 31 is limited to movement within the insertion portion 4, i.e., movement within the range of the width WL of the opening 3 in the cross section shown in FIG. 3B. Furthermore, as is clear from FIG. 2, the movement of the ball-shaped member BM in the direction forming a 60-degree angle with the line IIIB-IIIB and the direction forming a 120-degree angle with the line IIIB-IIIB is also limited to movement within the insertion portion 4. Therefore, even in the cross section shown in FIG. 3A, the movement of the ball-shaped member BM is limited to movement between two imaginary line segments LS. Not limited to the cross sections shown in FIGS. 3A and 3B, the movement of the ball-shaped member BM in a direction along any line passing through the center of the opening 3 in a plan view (i.e., any radial direction R in the insertion portion 4) is limited to within the insertion portion 4. Therefore, the ball-shaped member BM can be mounted on the wiring board with high precision in terms of the mounting position.

[0020] The opening of the ball mask of the embodiment preferably has two opposing portions on its wall surface that restrict the movement of the ball-shaped member, such as the restricting portion 31 of the opening 3 in FIG. 2 . The two opposing restricting portions directly restrict the movement of the ball-shaped member along the direction in which the two restricting portions face each other within the insertion portion 4. As a result, the movement of the ball-shaped member in any direction is restricted within the insertion portion 4. In the example of FIG. 2 , multiple extension portions 5 are evenly arranged around the insertion portion 4, and therefore the restricting portions 31, which are the portions between each extension portion 5, are also evenly arranged around the insertion portion 4. However, in the ball mask of the embodiment, the multiple extension portions 5 may be arranged at uneven intervals between each other along the periphery of the insertion portion 4. Therefore, the restricting portions 31 may be arranged at uneven intervals along the periphery of the insertion portion 4.

[0021] 2, the insertion portion 4 has a planar shape that is approximately similar to the shape of the ball-shaped member BM in a plan view, i.e., the projected shape of the ball-shaped member BM. The insertion portion 4, which has a planar shape that is approximately similar to the projected shape of the ball-shaped member BM, can uniformly restrict the movement of the ball-shaped member BM in any direction within the opening 3.

[0022] <Ball-shaped member guidance effect by expansion part> 1 to 3B, the ball mask of the embodiment has a portion in the opening like the extension portion 5, which promotes the entry of the ball-shaped members supplied onto the ball mask into the opening, reducing the number of ball-shaped members not being loaded. The action of guiding the ball-shaped members BM into the opening 3 by the extension portion 5 of the ball mask 1 of the embodiment will be described with reference to FIG.

[0023] 4 shows an enlarged cross section of the opening 3 in FIG. 2 taken along line IIIA-IIIA near the extension portion 5, along with the ball-shaped member BM whose center is located at the boundary between the extension portion 5 and the shielding portion 2. When the ball-shaped member BM is mounted on a wiring board (not shown) using the ball mask 1, the center of gravity of the ball-shaped member BM is located on the opening 3 side, i.e., inside the opening 3, in a plan view, simply by positioning the ball-shaped member BM slightly closer to the opening 3 than the position shown in FIG. 4. Therefore, the ball-shaped member BM can roll into the opening 3 by the action of gravity and fall onto the wiring board simply by being positioned slightly closer to the opening 3 than the position shown in FIG.

[0024] In contrast, if we imagine the boundary between the openings and the shielding portion in a conventional ball mask that does not have an extension portion 5 in each opening in Fig. 4, that boundary exists at the position of the imaginary line segment LS indicated by the two-dot chain line, as in Figs. 2 to 3B. Therefore, when loading a ball-shaped member BM using a conventional ball mask, the ball-shaped member BM cannot roll into the opening 3 unless it is positioned closer to the opening 3 than the position of the imaginary ball-shaped member BMI, whose center is located on the imaginary line segment LS. In openings into which the ball-shaped member BM does not roll, the ball-shaped member will not be loaded.

[0025] Compared to such conventional ball masks, in the ball mask 1 of the embodiment having the extension portion 5 in the opening 3, as described above, the area in which the ball-shaped member BM can enter the opening 3 by itself is enlarged around the periphery of the opening 3. Therefore, it is presumed that the entry of the ball-shaped member BM into the opening 3 is promoted, and it is possible to prevent the ball-shaped member from not being loaded.

[0026] In addition, the ball mask 1 of the embodiment has not only the extension portion 5 but also the limiting portion 31 (see FIG. 2) on the wall surface of the opening 3. Therefore, as described above, the ball-shaped members BM can be mounted on the wiring board with high precision at the intended mounting position. That is, it is presumed that the ball mask of the embodiment can prevent ball-shaped members from not being mounted on the wiring board while maintaining the precision of the mounting position of the ball-shaped members.

[0027] In particular, as the wiring of wiring boards on which ball-shaped members are mounted becomes finer and the electrodes of electronic components mounted on wiring boards become more multipolar and have narrower pitches, it is desirable to be able to properly mount small-diameter ball-shaped members on wiring boards. However, it is thought that even a slight deviation from the opening of a small-diameter ball-shaped member can prevent it from fitting into the opening. Furthermore, when a small-diameter ball-shaped member is pushed toward an opening on a ball mask with a squeegee or the like, it is expected that the squeegee or the like will pass over the small-diameter ball-shaped member, resulting in the small-diameter ball-shaped member only reaching the outer edge of the opening. Therefore, as the diameter of ball-shaped members becomes smaller, the rate of unmounted ball-shaped members is expected to increase. In addition, as the diameter of ball-shaped members becomes smaller, even a slight deviation in the mounting position of the ball-shaped member is more likely to cause problems such as poor connection.

[0028] In response to this trend, the ball mask 1 of the embodiment can prevent ball-shaped members BM from being left unmounted while maintaining the accuracy of the mounting position of the ball-shaped members BM, and is therefore considered to be particularly useful for mounting small-diameter ball-shaped members. It is presumed that this can contribute to promoting the reduction of the diameter of ball-shaped members. From the perspective of the usefulness of the ball mask of the embodiment for small-diameter ball-shaped members, the diameter of the ball-shaped members mounted using the ball mask of the embodiment may be, for example, 30 μm or more and less than 150 μm.

[0029] <Size of insertion part and expansion part> 2 to 3B, the sizes of the insertion portion 4 and the expansion portion 5 will be described. The diameter of the insertion portion 4, which allows a small-diameter ball-shaped member BM to pass through, i.e., the width WL of the opening 3 in a cross section passing through the center of the insertion portion 4 and the two opposing limiting portions 31, is, for example, 35 μm or more and 180 μm or less. If the insertion portion 4 has such a diameter, it is believed that a minute ball-shaped member can be mounted on a wiring board with high positional accuracy. Furthermore, the diameter of the insertion portion 4 is, for example, approximately 5 to 30 μm larger than the diameter of the ball-shaped member BM. By providing an insertion portion 4 of such a size, it may be possible to achieve a high accuracy of ±15 μm or less in the mounting position of the ball-shaped member BM.

[0030] In a plan view, the sum of the areas (total area) of the multiple extension portions 5 in each opening 3 is, for example, 10% or more and 50% or less of the area of ​​the insertion portion 4. Therefore, in each opening 3, the sum of the volumes of the multiple extension portions 5 may be 10% or more and 50% or less of the volume of the insertion portion 4. By providing extension portions 5 of such a size, the desired effect of preventing ball-shaped members from being left unmounted may be achieved without making the opening 3 extremely large in a plan view.

[0031] In a plan view, the sum of the lengths of the multiple extension portions 5 (the lengths of the imaginary line segments LS in FIG. 2 ) along the circumferential direction C of the insertion portion 4 at the boundaries between the insertion portion 4 and each extension portion 5 is, for example, 50% or more and 95% or less of the entire circumferential length of the insertion portion 4. In other words, the multiple extension portions 5 may be provided in a portion that occupies 50% or more and 95% or less of the entire circumferential length of the insertion portion 4 in a plan view. By providing such extension portions 5, it may be possible to guide the ball-shaped member BM located within a desired range in the circumferential direction C of the insertion portion 4 into the opening 3 while providing the number and size of limiting portions 31 required to obtain the desired mounting position accuracy.

[0032] In a plan view, the length L of the longest part of the expansion portion 5 in the radial direction R of the insertion portion 4 may be, for example, 10% or more and 50% or less of the radius of the insertion portion 4. By providing such an expansion portion 5, it may be possible to guide the ball-shaped member BM located within a desired range in the radial direction R of the insertion portion 4 into the opening 3 without making the opening 3 extremely large in a plan view.

[0033] <Extension section shape> The expansion portion 5 of the opening 3 illustrated in FIG. 2 has the shape of a portion of a circle in a plan view. The expansion portion 5 in FIG. 2 can also be said to have the shape of the remaining portion of the circle after it has been partially incorporated into the insertion portion 4. Therefore, the expansion portion 5 in FIG. 2 has an outer edge that curves outward from the opening 3. The width WE of the expansion portion 5 increases the closer it is to the center of the insertion portion 4. The width WE of the expansion portion 5 is the length of the expansion portion 5 in a direction perpendicular to an imaginary line connecting the center of the expansion portion 5 and the center of the insertion portion 4 in the circumferential direction C of the insertion portion 4. It is believed that an expansion portion 5 having a width WE that increases toward the insertion portion 4 is beneficial in guiding the ball-shaped member BM into the opening 3. The reason for this will be explained with reference to FIGS. 5A to 5C.

[0034] Fig. 5A shows a plan view of a ball-shaped member BM, whose center (center of gravity G) is located within the insertion portion 4 of the opening 3 shown in Fig. 2, together with the opening 3. Fig. 5B is an enlarged view of a cross section taken along line VB-VB in Fig. 5A, and Fig. 5C is an enlarged view of a cross section taken along line VC-VC in Fig. 5A. Note that both Fig. 5B and Fig. 5C are cross sections passing through the center of gravity G of the ball-shaped member BM.

[0035] As shown in Fig. 5B, the ball-shaped member BM is in contact with the shielding portion 2 of the ball mask 1 at point P1 and is supported by the shielding portion 2 at point P1. However, as is clear from Figs. 5B and 5C, the surface directly below the center of gravity G of the ball-shaped member BM, which is located closer to the center of the insertion portion 4 than point P1, is not in contact with the shielding portion 2.

[0036] That is, as shown in FIG. 5B , the ball-shaped member BM is supported by the shielding portion 2 at point P1, but is not supported by the shielding portion 2 at the center of gravity G. Therefore, the ball-shaped member BM can roll toward the inside of the insertion portion 4, using point P1 as a fulcrum. This rollable state of the ball-shaped member BM continues while the ball-shaped member BM rolls on the extension portion 5, so the ball-shaped member BM can eventually roll down into the insertion portion 4, i.e., into the opening 3. Therefore, if the opening 3 has the extension portion 5 with a width WE that increases toward the insertion portion 4, the ball-shaped member BM will be supported by the shielding portion 2 on the extension portion 5 side of the center of gravity G, making it easier to guide the ball-shaped member BM into the opening 3.

[0037] Furthermore, from the viewpoint of smooth rolling of the ball-shaped members BM on the extension portion 5, it is preferable that the shielding portion 2 surrounding the extension portion 5 and the ball-shaped members BM have contact over a small area, since this reduces friction. Therefore, it is preferable that the wall surfaces 21 (see FIG. 5C) of the shielding portion 2 surrounding the extension portion 5, which face each other in the direction of the width WE of the extension portion 5, are not inclined as indicated by the two-dot chain line T1, which is inclined toward the inside of the opening 3 as it moves away from the first surface 1A of the ball mask 1. In other words, it may be preferable that the wall surfaces 21 of the shielding portion 2 are parallel to the thickness direction of the ball mask 1. Alternatively, the wall surfaces 21 of the shielding portion 2 may be inclined toward the outside of the opening 3 as it moves away from the first surface 1A, as indicated by the two-dot chain line T2 in FIG. 5C. In other words, the extension portion 5 (see FIG. 5A) may have an inverted tapered shape in the cross section shown in FIG. 5C.

[0038] The opening 3 may have a tapered shape at the limiting portion 31 (see FIG. 5A) on the wall surface of the opening 3 such that the opening area of ​​the opening 3 decreases with increasing distance from the first surface 1A. Such a tapered shape is thought to make it easier for the ball-shaped member BM passing over the limiting portion 31 to enter the opening 3.

[0039] In the example of Fig. 2, the extension portion 5 has a shape of a part of a circle. However, in the ball mask of the embodiment, the extension portion 5 is not limited to a circle, and may have a shape of a part of an ellipse, or a shape of a part of a polygon having any number of vertices, as shown in Figs. 5C and 5D, which will be referred to below.

[0040] <Modification of the extension part> 6A to 6D show first to fourth modified examples of the opening 3 of the ball mask 1 of FIG. 2. The opening 3a of the first modified example shown in FIG. 6A has only two extension portions 5 arranged opposite each other in the X direction. It is believed that ball-shaped members BM located slightly outside the insertion portion 4, at least in the X direction, can be guided into the opening 3a. Therefore, compared to using a conventional ball-shaped member mounting mask without a portion such as the extension portion 5, failure to mount ball-shaped members can be reduced. Furthermore, the movement of the ball-shaped members passing through the opening 3a is limited to movement within the insertion portion 4 in at least two orthogonal directions, such as the X1 and Y1 directions. Therefore, even in the ball mask of the embodiment having the opening 3a, it is believed that failure to mount ball-shaped members on the wiring board can be reduced compared to conventional methods while maintaining the accuracy of the mounting position of the ball-shaped members.

[0041] The opening 3b of the second modified example shown in FIG. 6B has a total of four extension portions 5 that face each other in the X direction and the Y direction perpendicular to the X direction. In the opening 3b of the second modified example, adjacent extension portions 5 are in contact with each other at the outer edges of the insertion portion 4. Therefore, in a plan view, the only portions (restriction portions 31) of the wall surface surrounding the opening 3b of the second modified example that can come into contact with a ball-shaped member passing through the opening 3b are the four contact points where adjacent extension portions 5 are in contact with each other. The insertion portion 4 of the opening 3b is a region surrounded by the four point-like restriction portions 31 and the imaginary line segment LS. Two of the four restriction portions 31 face each other in the X1 direction, and the remaining two of the four restriction portions 31 face each other in the Y1 direction perpendicular to the X1 direction.

[0042] Therefore, the movement of the ball-shaped member passing through the opening 3b is limited to movement within the insertion portion 4 in both the X1 and Y1 directions. It is believed that the extension portion 5 provided around substantially the entire circumference of the insertion portion 4 can guide the ball-shaped member BM located slightly outside the insertion portion 4 at any position in the circumferential direction C of the insertion portion 4 into the opening 3b. Therefore, even in the ball mask of the embodiment having the opening 3b, it is believed that it is possible to maintain the accuracy of the ball-shaped member mounting position while reducing the number of ball-shaped members not being mounted on the wiring board compared to conventional methods. In the ball mask of the embodiment, as in the opening 3b of the second modified example, adjacent extension portions may come into contact with each other, resulting in extension portions being provided around substantially the entire circumference of the opening.

[0043] The opening 3c of the third modified example shown in FIG. 6C has a total of four extension portions 5 facing each other in the X and Y directions, similar to the opening 3b of the second modified example shown in FIG. 6B. The extension portion 5 of the opening 3c has a vertex PP in plan view and two linear sides S1 and S2 that form a predetermined angle with each other at the vertex PP and extend to the outer edge of the insertion portion 4. That is, the extension portion 5 of the opening 3c has the shape of a part of a polygon in plan view. Therefore, it can be said that the extension portion 5 of the opening 3c has the shape of, for example, the remaining part of a triangle after it has been partially incorporated into the insertion portion 4. The width WE of the extension portion 5 of the opening 3c also increases the closer it is to the center of the insertion portion 4.

[0044] In the opening 3c, too, the movement of the ball-shaped member passing through the opening 3c is restricted to movement within the insertion portion 4 in at least two orthogonal directions, such as the X1 direction and the Y1 direction. As with the opening 3 in Fig. 2, it is believed that the four extension portions 5 can guide a ball-shaped member positioned slightly outside the insertion portion 4 at least in the X direction and the Y direction into the opening 3c. Therefore, even in the ball mask of the embodiment having the opening 3c, it is believed that it is possible to maintain the accuracy of the mounting position of the ball-shaped member and reduce the number of ball-shaped members not being mounted on the wiring board compared to conventional methods.

[0045] The opening 3d of the fourth modified example shown in Fig. 6D has a total of four extension portions 5 that face each other in the X and Y directions, similar to the opening 3b of the second modified example shown in Fig. 6B. The extension portions 5 of the opening 3d have two vertices PP1 and PP2 in a plan view, and an outer edge S3 that bends at a substantially right angle at the vertices PP1 and PP2 and extends to the outer edge of the insertion portion 4. That is, the extension portions 5 of the opening 3d have a polygonal shape, particularly a partial rectangle shape, in a plan view. Therefore, it can be said that the extension portions 5 of the opening 3d have the shape of the remaining portion after, for example, a rectangle has been partially incorporated into the insertion portion 4.

[0046] The width WE of the extension 5 of the opening 3d is substantially constant regardless of the distance from the center of the insertion portion 4 and does not expand or contract. Therefore, the extension 5 of the opening 3d does not induce the rolling of the ball-shaped member. However, once the ball-shaped member reaches the extension 5, the inertia generated by the ball-shaped member falling from the shielding portion 2 to the extension 5 may cause the ball-shaped member to continue moving toward the insertion portion 4. Therefore, even in the ball mask of the embodiment having the opening 3d, it may be possible to promote the entry of the ball-shaped member into the opening 3d. Furthermore, the movement of the ball-shaped member passing through the opening 3d is limited to movement within the insertion portion 4 in at least two orthogonal directions, such as the X1 direction and the Y1 direction. Therefore, even in the ball mask of the embodiment having the opening 3d, it is believed that the occurrence of ball-shaped members not being mounted on the wiring board can be reduced compared to conventional methods while maintaining the accuracy of the mounting position of the ball-shaped member.

[0047] <Method of mounting ball-shaped components on a wiring board> Next, a ball-shaped member mounting method according to an embodiment of the present invention will be described with reference to FIGS. 7A to 7D. Hereinafter, the ball-shaped member mounting method according to the embodiment will also be simply referred to as the "ball mounting method according to the embodiment." In the ball mounting method according to the embodiment, as shown in FIG. 7A, a ball-shaped member mounting mask 11 (hereinafter also referred to as the "ball mask 11") having a shielding portion 2 and an opening 3 is prepared. The ball-shaped member mounting mask 11 shown in FIGS. 7A to 7D may be the ball-shaped member mounting mask 1 (ball mask 1) according to the embodiment described with reference to FIGS. 1 to 6D.

[0048] Therefore, as shown in FIG. 2 , the opening 3 of the ball mask 11 used in the ball mounting method of the embodiment has an insertion portion 4 that allows the ball-shaped member BM to pass through, and a plurality of extension portions 5 provided around the insertion portion 4. Each extension portion 5 is provided so as to protrude from the periphery of the insertion portion 4 to the outside of the insertion portion 4. Each extension portion 5 is formed integrally with the insertion portion 4 and penetrates the shielding portion 2 together with the insertion portion 4. The insertion portion 4 is surrounded by a portion (restriction portion 31) of the wall surface surrounding the opening 3 that can come into contact with the ball-shaped member BM passing through the opening 3. Each extension portion 5 is provided around the insertion portion 4 so as to restrict the ball-shaped member BM passing through the opening 3 from entering the interior of the extension portion 5.

[0049] As explained for the ball mask of the embodiment, the ball mask 11 can be formed by a general method for manufacturing a ball-shaped member mounting mask. That is, the ball mask 11 can be formed by forming openings 3 by etching in a metal film or metal foil made of stainless steel, copper alloy, nickel alloy, or the like. Alternatively, the ball mask 11 may be formed by depositing a metal material such as copper to a predetermined thickness by plating or sputtering, etc., with predetermined regions corresponding to the openings 3, etc., masked.

[0050] As shown in FIG. 7A, a wiring board PWB is prepared on which ball-shaped members are to be mounted. The wiring board PWB shown in FIG. 7A includes an insulating layer I made of an insulating resin such as epoxy resin, and connection pads MP made of a metal such as copper on the insulating layer I. The wiring board PWB on which ball-shaped members are to be mounted by the ball mounting method of the embodiment may not be a single-sided board as shown in FIG. 7A, but may be a double-sided board or a multilayer board with any number of layers. The wiring board PWB may be a build-up wiring board having a core substrate, or may be a build-up wiring board without a core substrate. The wiring board PWB is prepared by any common wiring board manufacturing method. Flux is preferably applied to the wiring board PWB.

[0051] The ball mask 11 is positioned on the wiring board PWB so that each opening 3 of the ball mask 11 is positioned over each connection pad MP of the wiring board PWB. For example, predetermined features of the wiring board PWB and predetermined features of the ball mask 11 are recognized by an imaging device such as a camera, and after alignment is performed so that these features overlap, the ball mask 11 is placed on the wiring board PWB.

[0052] As shown in FIG. 7B , a desired number of ball-shaped members BM are provided on the surface of the shielding portion 2 of the ball mask 11. For example, the ball-shaped members BM are made of a conductive material such as solder, a metal such as gold, nickel, or copper, or an alloy thereof, or are made of an insulating material having a conductive coating on its surface. Then, the ball-shaped members BM are placed on the surface of the wiring board PWB, specifically, on the surfaces of the connection pads MP, through the openings 3. In the example of FIG. 7B , the multiple ball-shaped members BM provided on the surface of the ball mask 11 are moved over the surface of the ball mask 11 by a squeegee SK. Then, the ball-shaped members BM that reach each opening 3 enter the opening 3 and are placed at appropriate positions on the connection pads MP of the wiring board PWB through the openings 3.

[0053] As shown in Fig. 7C, the opening 3 has a plurality of extensions 5, so that the ball-shaped member BM located near the edge of the opening 3 can be guided into the opening 3 without remaining there. Note that Fig. 7C is an enlarged plan view of one opening 3 of the ball mask 11 in Fig. 7B together with the ball-shaped member BM.

[0054] In the ball mounting method of the embodiment using the ball mask 11 having the extension portion 5, when placing the ball-shaped member BM on the wiring board PWB, it is preferable to move the ball-shaped member BM on the surface of the shielding portion 2 of the ball mask 11 toward the insertion portion 4 so that it passes over the extension portion 5. That is, it may be preferable to move the ball-shaped member BM along the direction in which the two extension portions 5 face each other (the −X direction, XM direction, or −XP direction in the example of FIG. 7C ). By moving the ball-shaped member BM in this manner, even if the squeegee SK passes over the ball-shaped member BM before it reaches the insertion portion 4, it may be possible to guide the ball-shaped member BM into the opening 3 via the extension portion 5.

[0055] In the ball mounting method of the embodiment, the ball-shaped member BM located near the outer edge of the opening 3 is introduced into the opening 3 while a portion of the member is allowed to sink into the extension portion 5, as shown in Figures 5B and 5C referenced above. In this way, the ball mounting method of the embodiment may include, in placing the ball-shaped member BM on the wiring board PWB, introducing the ball-shaped member BM into the opening 3 while a portion of the ball-shaped member BM located on the periphery of the opening 3 is allowed to sink into the extension portion 5. By effectively utilizing the action of the extension portion 5, the ball-shaped member BM can be mounted with a low rate of unmounted members.

[0056] By moving the squeegee SK from one side of the ball mask 11 to the opposite side, the ball-shaped members BM preferably enter all of the openings 3. Then, the ball mask 11 is removed from above the wiring board PWB. After that, a heating process such as a reflow process is performed, for example. The ball-shaped members BM are melted and then solidified, thereby forming, for example, connection bumps on the connection pads MP.

[0057] The movement of the ball-shaped members BM shown in Fig. 7B on the surface of the ball mask 11 may also be performed by the method shown in Fig. 7D. In the example of Fig. 7D, a cylindrical body CL having an air intake port OA is placed above a plurality of ball-shaped members BM supplied on the surface of the ball mask 11. The ball-shaped members BM surrounded by the cylindrical body CL are gathered near directly below the air intake port OA by suction from the air intake port OA. In this state, the cylindrical body CL is moved above the ball mask 11 from one side of the ball mask 11 to the opposite side.

[0058] As the cylindrical body CL moves, the plurality of ball-shaped members BM gathered directly below the air intake OA also move from one side of the ball mask 11 to the opposite side. Then, the ball-shaped members BM that reach the openings 3 that do not yet contain a ball-shaped member BM enter the openings 3 one by one. By moving the cylindrical body CL from one side of the ball mask 11 to the opposite side, the ball-shaped members BM are preferably introduced into all of the openings 3. In the ball mounting method of the embodiment, the placement of the ball-shaped members BM on the surface of the wiring board PWB through the openings 3 may be performed by the method shown in FIG. 7D.

[0059] In the ball mounting method of the embodiment, the ball-shaped members BM are mounted on the wiring board PWB using the ball mask 11, which is the ball mask 1 of the embodiment shown in Fig. 2 etc., so that the ball-shaped members BM can be mounted on the wiring board PWB with high accuracy. Also, the ball-shaped members BM located near the edge of the opening 3 can sometimes be guided into the opening 3 without remaining there. Therefore, as described for the ball mask of the embodiment, the ball mounting method of the embodiment is thought to be able to prevent the ball-shaped members BM from not being mounted on the wiring board PWB while maintaining the accuracy of the mounting position of the ball-shaped members BM on the wiring board PWB.

[0060] The ball-shaped member mounting mask of the embodiment is not limited to those having the structures illustrated in the drawings and the structures, shapes, and materials illustrated in this specification. For example, the shielding portion of the ball-shaped member mounting mask of the embodiment does not have to be connected to a frame as shown in FIG. 1. Furthermore, the ball-shaped member mounting mask of the embodiment does not have to include multiple opening groups for an editing substrate including multiple individual substrates. The extension portion of the opening of the ball-shaped member mounting mask of the embodiment may have a shape other than the shapes illustrated in FIG. 2 and FIGS. 6A to 6D.

[0061] The ball-shaped member mounting method of the embodiment is not limited to the method described with reference to the drawings. For example, the ball-shaped members may be moved on the ball-shaped member mounting mask by a method other than the method shown in Figures 7B and 7D. The ball-shaped member mounting method of the embodiment may include any additional steps in addition to the steps described above, or some of the steps described above may be omitted. [Explanation of symbols]

[0062] 1, 11 Ball-shaped component mounted mask (ball mask) 2 Shielding part 3, 3a~3d opening 31 Restriction portion (portion that can come into contact with the ball-shaped member) 4 Insertion part 5 Extension BM ball-shaped member C circumferential direction PWB wiring board R radial direction

Claims

1. a flat shielding portion; an opening that penetrates the shielding portion and allows a ball-shaped member to pass through that is disposed on a wiring board; A ball-shaped member mounted mask having The opening is an insertion portion that is surrounded by a portion of a wall surface surrounding the opening that can come into contact with the ball-shaped member passing through the opening, and that allows the ball-shaped member to pass through; a plurality of extension portions that are integrally formed with the insertion portion so as to protrude outward from a periphery of the insertion portion and that penetrate the shielding portion; and The expansion portion is provided around the insertion portion so as to restrict the ball-shaped member passing through the opening from entering the interior of the expansion portion.

2. 2. The mask having ball-shaped members according to claim 1, wherein the diameter of the insertion portion is 35 μm or more and 180 μm or less.

3. 2. The mask having ball-shaped members according to claim 1, wherein the insertion portion has a planar shape that is approximately similar to a projected shape of the ball-shaped members.

4. 2. The mask having ball-shaped members according to claim 1, wherein a total area of ​​the plurality of extension portions is 10% to 50% of an area of ​​the insertion portion in a plan view.

5. 2. The mask with ball-shaped members according to claim 1, wherein the plurality of extension portions are provided in a portion that occupies 50% to 95% of the entire perimeter of the insertion portion in a plan view.

6. 2. The mask equipped with ball-shaped members according to claim 1, wherein, in a plan view, the length of the longest part of the extension portion in the radial direction of the insertion portion is 10% to 50% of the radius of the insertion portion.

7. providing a mask having an opening; placing a ball-shaped member on the surface of the wiring substrate through the opening. A method for mounting ball-shaped members on a wiring substrate, comprising: The opening is an insertion portion that is surrounded by a portion of a wall surface surrounding the opening that can come into contact with the ball-shaped member passing through the opening, and that allows the ball-shaped member to pass through; a plurality of extension portions that are integrally formed with the insertion portion so as to protrude outward from the periphery of the insertion portion and that penetrate the shielding portion of the mask; and The expansion portion is provided around the insertion portion so as to restrict the ball-shaped member passing through the opening from entering the interior of the expansion portion.

8. A method for mounting a ball-shaped member according to claim 7, wherein placing the ball-shaped member includes introducing the ball-shaped member into the opening while causing a portion of the ball-shaped member located on the periphery of the opening to sink into the extension portion.

9. A method for mounting a ball-shaped member according to claim 7, wherein placing the ball-shaped member includes moving the ball-shaped member on the surface of the mask toward the insertion portion so as to pass over the extension portion.

Images