Electromagnetic wave shielding film

Abstract

The present invention provides an electromagnetic wave shield film that can reduce transmission loss. This electromagnetic wave shield film is characterized by comprising a protection layer, a shield layer that is layered on the protection layer, and an adhesive layer that is layered on the shield layer, a plurality of conductive bumps being formed on the shield layer on the adhesive layer side, the conductive bumps being arranged such that, when the shield layer is seen in plan view from the adhesive layer side, the conductive bumps are positioned at the vertices of two or more types of tessellated polygons and such that, when line segments are drawn to connect each of the conductive bumps to the nearest conductive bump, and a straight line is drawn along one of the line segments, the straight line has a portion that does not overlap the other line segments.

Description

[Technical field]

[0001] The present invention relates to an electromagnetic wave shielding film. [Background technology]

[0002] Printed wiring boards, such as flexible printed wiring boards, are widely used to incorporate circuits into complex mechanisms in electronic devices such as mobile phones, video cameras, and laptops, which are rapidly becoming smaller and more functional. Furthermore, taking advantage of their excellent flexibility, they are also used to connect movable parts such as printer heads to control units. Electromagnetic shielding is essential for these electronic devices, and printed wiring boards used within the devices that have been given electromagnetic shielding measures, such as attaching an electromagnetic shielding film (hereinafter also referred to as "shielded printed wiring boards"), are now being used.

[0003] In general, an electromagnetic wave shielding film is composed of an outermost protective layer, a shielding layer for shielding electromagnetic waves, and an adhesive layer for attaching the film to a printed wiring board. When manufacturing a shielded printed wiring board, the electromagnetic wave shielding film is attached to the printed wiring board so that the adhesive layer of the electromagnetic wave shielding film is in contact with the printed wiring board.

[0004] In addition, the ground circuit of the printed wiring board is electrically connected to an external ground such as a housing, and sometimes the ground circuit of the printed wiring board and the external ground are electrically connected via an electromagnetic wave shielding film attached to the printed wiring board.

[0005] Generally, electromagnetic wave shielding films are not designed to suit individual printed wiring boards, and electromagnetic wave shielding films are required to have the function of shielding electromagnetic waves from any printed wiring board. This is because there are an infinite number of shapes and wiring configurations for printed wiring boards, and it is not realistic in terms of cost-effectiveness to design an electromagnetic shielding film that is optimally suited to each individual printed wiring board.

[0006] For example, Patent Document 1 discloses an electromagnetic wave shielding film that can meet such requirements, which comprises a protective layer, a shielding layer laminated on the protective layer, and an adhesive layer laminated on the shielding layer, and a conductive bump is formed on the adhesive layer side of the shielding layer, and the volume of the conductive bump is 30,000 to 400,000 μm. 3 The electromagnetic wave shielding film is characterized in that In Patent Document 1, in order to sufficiently reduce the connection resistance between the ground circuit and the shielding layer of the printed wiring board, a conductive bump is formed on the shielding layer of the electromagnetic wave shielding film, and the conductive bump is brought into contact with the ground circuit of the printed wiring board. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2020 / 090727 Summary of the Invention [Problem to be solved by the invention]

[0008] When a shielded printed wiring board is produced using the electromagnetic wave shielding film described in Patent Document 1, the transmission loss in the shielded printed wiring board may become large.

[0009] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide an electromagnetic wave shielding film capable of reducing transmission loss. [Means for solving the problem]

[0010] The inventors discovered that in the electromagnetic wave shielding film of Patent Document 1, when the electromagnetic wave shielding film is viewed in a plane, if the conductive bumps are arranged at equal intervals in a straight line, transmission loss may be large, and they arrived at the present invention.

[0011] That is, the electromagnetic wave shielding film of the present invention comprises a protective layer, a shielding layer laminated on the protective layer, and an adhesive layer laminated on the shielding layer, and a plurality of conductive bumps are formed on the adhesive layer side of the shielding layer, and when the shielding layer is viewed in a plane from the adhesive layer side, the conductive bumps are arranged so as to be located at the vertices of each of two or more types of polygons that are filled into a plane, and the conductive bumps are arranged so that, for each of the plurality of conductive bumps, a line segment is drawn connecting each of the conductive bumps to the nearest conductive bump that is located closest to the conductive bump, and a straight line passing through one of the line segments is drawn, and the straight line has a portion that does not overlap with the other line segments.

[0012] The conductive bumps being arranged in this manner means that when the shielding layer is viewed in a plan view from the adhesive layer side, adjacent conductive bumps are not arranged at equal intervals in a straight line.

[0013] The electromagnetic wave shielding film of the present invention is disposed on a printed wiring board. First, the reason why transmission loss increases when an electromagnetic shielding film having conductive bumps arranged at equal intervals in a straight line is used for a printed wiring board will be described. Generally, a signal circuit separate from the ground circuit is placed near the ground circuit of a printed wiring board. When an electromagnetic shielding film is placed on a printed wiring board, the conductive bumps of the electromagnetic shielding film may be located on such a signal circuit, which may result in a parasitic circuit and increase transmission loss. In particular, if the conductive bumps are arranged at equal intervals on a straight line, and the direction in which the conductive bumps are arranged coincides with the direction in which the signal circuits are formed, the number of conductive bumps located above the signal circuits increases, resulting in a large number of parasitic circuits and large transmission loss. Furthermore, when there are multiple signal circuits, the number of parasitic circuits generated between the signal circuits and the conductive bumps may differ from one signal circuit to another, which further increases the transmission loss.

[0014] However, in the electromagnetic wave shielding film of the present invention, the conductive bumps are not arranged at equal intervals in a straight line, so that the occurrence of parasitic circuits due to the conductive bumps being located above the signal circuits of the printed wiring board can be suppressed, and as a result, transmission loss can be reduced.

[0015] One method that can be considered to prevent a large number of conductive bumps from being placed on the signal circuit is to randomly arrange the conductive bumps, but randomly arranging the conductive bumps tends to result in portions where the contact between the conductive bumps and the ground circuit is insufficient. In the electromagnetic wave shielding film of the present invention, the conductive bumps are arranged so as to be located at the vertices of each of two or more polygons that are packed into a plane, i.e., in the electromagnetic wave shielding film of the present invention, the conductive bumps are arranged in a regular zigzag pattern. When the conductive bumps are arranged in a regular zigzag pattern, the conductive bumps can be reliably contacted with the ground circuit. As a result, the connection stability between the shielding layer of the electromagnetic wave shielding film and the ground circuit of the printed wiring board can be increased.

[0016] In the electromagnetic wave shielding film of the present invention, the polygon may be of two types, a rhombus and a regular hexagon, and the length of one side of the rhombus may be equal to the length of one side of the regular hexagon.

[0017] In the electromagnetic wave shielding film of the present invention, the polygon may be one of two types, an equilateral triangle and a square, and the length of one side of the equilateral triangle may be equal to the length of one side of the square.

[0018] In the electromagnetic wave shielding film of the present invention, the polygon may be one of two types, an equilateral triangle and a regular hexagon, and the length of one side of the equilateral triangle may be equal to the length of one side of the regular hexagon.

[0019] In the electromagnetic wave shielding film of the present invention, the polygon may be one of three types: an equilateral triangle, a square, and a regular hexagon, and the length of one side of the equilateral triangle, the length of one side of the square, and the length of one side of the regular hexagon may be equal.

[0020] In the electromagnetic wave shielding film of the present invention, the polygon may be one of two types, an equilateral triangle and a regular dodecagon, and the length of one side of the equilateral triangle may be equal to the length of one side of the regular dodecagon.

[0021] In the electromagnetic wave shielding film of the present invention, the polygon may be one of two types, a square and a regular octagon, and the length of one side of the square may be equal to the length of one side of the regular octagon.

[0022] In the electromagnetic wave shielding film of the present invention, the polygon may be one of three types: a square, a regular hexagon, and a regular dodecagon, and the length of one side of the square, the length of one side of the regular hexagon, and the length of one side of the regular dodecagon may be equal.

[0023] When the polygon has these shapes, adjacent conductive bumps are not arranged at equal intervals on a straight line when the shielding layer of the electromagnetic shielding film of the present invention is viewed in plan from the adhesive layer side, and therefore transmission loss can be reduced when the electromagnetic shielding film of the present invention is used in a printed wiring board.

[0024] Furthermore, when the polygon has these shapes, the conductive bumps are arranged in a regular zigzag pattern when the shielding layer of the electromagnetic wave shielding film of the present invention is viewed in plan from the adhesive layer side. Generally, from the standpoint of work efficiency, an electromagnetic wave shielding film is rarely placed on a printed wiring board while taking into consideration the relationship between the arrangement direction of the conductive bumps on the electromagnetic wave shielding film and the direction in which the ground circuit on the printed wiring board is formed. Therefore, when the conductive bumps are arranged only in a straight line, when the electromagnetic wave shielding film is placed on a printed wiring board, the direction in which the ground circuit of the printed wiring board is formed may coincide with the direction in which the conductive bumps are arranged. In this case, if the conductive bumps are positioned so that they come into contact with the ground circuit, there is no problem with the stability of the electrical connection between the shielding layer of the electromagnetic shielding film and the ground circuit of the printed wiring board. However, if the conductive bumps are positioned so that they do not come into contact with the ground circuit, none of the conductive bumps arranged on that straight line will be able to come into contact with the ground circuit. As a result, the shielding layer of the electromagnetic shielding film and the ground circuit of the printed wiring board will not be able to be electrically connected via the conductive bumps arranged on that straight line. On the other hand, when the conductive bumps are arranged in a regular zigzag pattern as in the electromagnetic shielding film of the present invention, even if one conductive bump is arranged in a position where it cannot contact the ground member, the other conductive bumps are more likely to be able to contact the ground member, thereby reducing the possibility that the shielding layer of the electromagnetic shielding film and the ground circuit of the printed wiring board will not be able to be electrically connected by the conductive bumps. Therefore, in the manufactured shielded printed wiring board, the connection stability between the shielding layer of the electromagnetic wave shielding film and the ground circuit of the printed wiring board can be increased.

[0025] The electromagnetic wave shielding film of the present invention comprises a protective layer, a shielding layer laminated on the protective layer, and an adhesive layer laminated on the shielding layer, and a plurality of conductive bumps are formed on the adhesive layer side of the shielding layer, and the plurality of conductive bumps include a first conductive bump and a second conductive bump located closest to the first conductive bump, and when the shielding layer is viewed in a plan view from the adhesive layer side and a straight line a is drawn passing through the first conductive bump and the second conductive bump, other conductive bumps are arranged on the straight line a outside the first conductive bump and the second conductive bump, and when any two of the conductive bumps arranged on the straight line a are selected, the distance between the selected two conductive bumps is the longest when D1 is the distance between the selected two conductive bumps and D2 is the distance from the first conductive bump to the second conductive bump, the number of the conductive bumps arranged on the straight line a is less than D1 / D2+1.

[0026] The conductive bumps being arranged in this manner means that when the shielding layer is viewed in a plan view from the adhesive layer side, adjacent conductive bumps are not arranged at equal intervals in a straight line.

[0027] In the electromagnetic wave shielding film of the present invention, the conductive bumps are not arranged at equal intervals in a straight line, so that the occurrence of a parasitic circuit due to the conductive bumps being located above the signal circuit of the printed wiring board can be suppressed, and as a result, transmission loss can be reduced. Effect of the Invention

[0028] The electromagnetic wave shielding film of the present invention is placed on a printed wiring board on which a ground circuit is formed, so that the conductive bumps of the electromagnetic wave shielding film of the present invention come into contact with the ground circuit of the printed wiring board. In the electromagnetic wave shielding film of the present invention, adjacent conductive bumps are not arranged at equal intervals in a straight line, which prevents a parasitic circuit from occurring due to a conductive bump being located above a signal circuit of a printed wiring board, thereby reducing transmission loss. [Brief description of the drawings]

[0029] [Figure 1A] FIG. 1A is a cross-sectional view that illustrates an example of an electromagnetic wave shielding film according to a first embodiment of the present invention. [Figure 1B] FIG. 1B is a plan view that illustrates a schematic arrangement of conductive bumps when the shielding layer of the electromagnetic wave shielding film illustrated in FIG. 1A is viewed from the adhesive layer side. [Figure 1C] FIG. 1C is a plan view illustrating that the arrangement of conductive bumps in the electromagnetic shielding film shown in FIGS. 1A and 1B is a feature of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view that illustrates an example of a shielded printed wiring board in which the electromagnetic wave shielding film according to the first embodiment of the present invention is used. [Diagram 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. [Figure 4] FIG. 4 is a plan view showing an example of a positional relationship between conductive bumps and a ground circuit in a shielded printed wiring board having an electromagnetic shielding film in which conductive bumps are arranged at equal intervals on a straight line. [Figure 5A] FIG. 5A is a plan view that illustrates an example of an arrangement of conductive bumps when the shielding layer of the electromagnetic wave shielding film according to the first embodiment of the present invention is viewed in plan from the adhesive layer side. [Figure 5B] FIG. 5B is a plan view that illustrates an example of an arrangement of conductive bumps when the shielding layer of the electromagnetic wave shielding film according to the first embodiment of the present invention is viewed from the adhesive layer side. [Figure 5C] FIG. 5C is a plan view that illustrates an example of an arrangement of conductive bumps when the shielding layer of the electromagnetic wave shielding film according to the first embodiment of the present invention is viewed in plan from the adhesive layer side. [Figure 5D] FIG. 5D is a plan view that typically shows one example of an arrangement of conductive bumps when the shielding layer of the electromagnetic wave shielding film according to the first embodiment of the present invention is viewed from the adhesive layer side. [Figure 5E] FIG. 5E is a plan view that illustrates an example of an arrangement of conductive bumps when the shielding layer of the electromagnetic wave shielding film according to the first embodiment of the present invention is viewed from the adhesive layer side. [Figure 5F] FIG. 5F is a plan view that typically shows one example of an arrangement of conductive bumps when the shielding layer of the electromagnetic wave shielding film according to the first embodiment of the present invention is viewed from the adhesive layer side. [Figure 6A] FIG. 6A is a cross-sectional view that illustrates an example of an electromagnetic wave shielding film according to a second embodiment of the present invention. [Figure 6B] FIG. 6B is a plan view that illustrates an example of an arrangement of conductive bumps when the shielding layer of the electromagnetic wave shielding film according to the second embodiment of the present invention is viewed from the adhesive layer side. [Figure 7] FIG. 7 is a plan view showing a schematic arrangement of conductive bumps of an electromagnetic wave shielding film in which the conductive bumps are arranged at equal intervals on a straight line. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] The electromagnetic wave shielding film of the present invention will be specifically described below. However, the present invention is not limited to the following embodiments, and can be appropriately modified and applied within the scope of the present invention.

[0031] (First embodiment) The electromagnetic wave shielding film according to the first embodiment of the present invention comprises a protective layer, a shielding layer laminated on the protective layer, and an adhesive layer laminated on the shielding layer, and a plurality of conductive bumps are formed on the adhesive layer side of the shielding layer, and when the shielding layer is viewed in a plane from the adhesive layer side, the conductive bumps are arranged so as to be located at the vertices of each of two or more types of polygons that are filled into a plane, and the conductive bumps are arranged so that, for each of the plurality of conductive bumps, a line segment is drawn connecting each of the conductive bumps to the nearest conductive bump that is located closest to the conductive bump, and a straight line passing through one of the line segments is drawn, and the straight line has a portion that does not overlap with the other line segments. As long as the electromagnetic wave shielding film according to the first embodiment of the present invention has the above characteristics, it may have any other characteristics as long as the effects of the invention are achieved.

[0032] Hereinafter, an example of the electromagnetic wave shielding film according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 1A is a cross-sectional view that illustrates an example of an electromagnetic wave shielding film according to a first embodiment of the present invention.

[0033] As shown in FIG. 1A, an electromagnetic wave shielding film 10 includes a protective layer 11, a shielding layer 12 laminated on the protective layer 11, and an adhesive layer 13 laminated on the shielding layer 12. The protective layer 11, the shielding layer 12 and the adhesive layer 13 are laminated in this order. In addition, a plurality of conductive bumps 14 are formed on the adhesive layer 13 side of the shield layer 12 .

[0034] The arrangement of the conductive bumps 14 on the electromagnetic wave shielding film 10 will be described. FIG. 1B is a plan view that illustrates a schematic arrangement of conductive bumps when the shielding layer of the electromagnetic wave shielding film illustrated in FIG. 1A is viewed from the adhesive layer side.

[0035] 1B, in the electromagnetic wave shielding film 10, the conductive bumps 14 are arranged so as to be located at the vertices of each equilateral triangle 51a and each square 52a formed by a plane tessellation of the equilateral triangles 51a and the squares 52a. The length of one side of the equilateral triangle 51a is equal to the length of one side of the square 52a. In FIG. 1B, for ease of explanation, the equilateral triangle indicated by the symbol 51a and the square indicated by the symbol 52a are exaggerated; however, in the electromagnetic wave shielding film 10, the exaggerated equilateral triangle 51a and square 52a have no structural or functional differences from other equilateral triangles and squares.

[0036] In the electromagnetic wave shielding film 10, for each conductive bump 14, a line segment is drawn connecting the conductive bump 14 with the nearest conductive bump 14, and the conductive bumps 14 are arranged so that when a straight line passing through one of the line segments is drawn, the straight line has a portion that does not overlap with the other line segments.

[0037] Such an arrangement of the conductive bumps 14 will be specifically described with reference to the drawings. FIG. 1C is a plan view illustrating that the arrangement of conductive bumps in the electromagnetic shielding film shown in FIGS. 1A and 1B is a feature of the present invention.

[0038] As shown in FIG. 1C, first, line segments connecting each conductive bump 14 to the nearest conductive bump 14 (line segments shown as solid lines connecting conductive bumps 14 in FIG. 1C) are drawn. In the electromagnetic wave shielding film 10, when a straight line is drawn passing through one line segment, so long as the straight line has a portion that does not overlap with other line segments, the respective line segments may be located separately on the straight line, or some of the line segments may be located continuously on the straight line.

[0039] First, a case where each line segment is separated and located on a straight line will be described. 1C, attention is focused on conductive bumps 14a and 14b among conductive bumps 14. Conductive bump 14a is the closest conductive bump to conductive bump 14b. Conductive bump 14a and conductive bump 14b are connected by line segment A1. When a straight line a1 passing through the line segment A1 is drawn, there is a portion on the straight line a1 where the distance between the conductive bumps 14 is not the shortest (the line segment indicated by the symbol B1 in FIG. 1C). In other words, the straight line a1 has a portion that does not overlap with the line segment connecting each conductive bump to the nearest conductive bump located at the closest position. Furthermore, on the straight line a1, the line segments connecting each conductive bump to the nearest conductive bump at the closest position are not continuous but are separated.

[0040] Next, a case where some line segments are continuously positioned on a straight line will be described. In FIG. 1C, attention is focused on conductive bumps 14c, 14d, and 14e among conductive bumps 14. Conductive bump 14c is the closest conductive bump to conductive bump 14d, which is the closest conductive bump to conductive bump 14e. Conductive bumps 14c and 14d are connected by a line segment A2, and conductive bumps 14d and 14e are connected by a line segment A3. Conductive bump 14c, conductive bump 14d and conductive bump 14e are arranged in a straight line. When a straight line a2 is drawn passing through conductive bumps 14c, 14d, and 14e, there are locations (the line segment indicated by symbol B2 in FIG. 1C) where the distance between conductive bumps 14 is not the shortest. That is, in straight line a2, some line segments (i.e., line segments A2 and A3) continuously overlap. However, straight line a2 has a portion that does not overlap with the line segment connecting each conductive bump to the nearest conductive bump located at the closest position.

[0041] From the above, it can be said that in the electromagnetic wave shielding film 10, when a line segment is drawn connecting each conductive bump 14 to the nearest conductive bump 14, and a straight line passing through one of those line segments is drawn, the conductive bumps 14 are arranged so that there is a portion of the straight line that does not overlap with the other line segments.

[0042] The fact that the conductive bumps 14 are arranged in this manner means that when the shield layer 12 is viewed in a plan view from the adhesive layer 13 side, adjacent conductive bumps 14 are not arranged at equal intervals in a straight line, but are arranged in a regular zigzag pattern.

[0043] The electromagnetic wave shielding film 10 exerts its effect when it is disposed on a printed wiring board and becomes a part of the components of the shielded printed wiring board. Therefore, a shielded printed wiring board equipped with the electromagnetic wave shielding film 10 will be described.

[0044] FIG. 2 is a cross-sectional view that illustrates an example of a shielded printed wiring board in which the electromagnetic wave shielding film according to the first embodiment of the present invention is used. As shown in FIG. 2, the shielded printed wiring board 1 includes as its components a printed wiring board 20 comprising a base film 21, a printed circuit 22 including a plurality of ground circuits 22a formed on the base film 21, and a coverlay 23 covering the printed circuit 22, with the coverlay 23 having openings 23a formed therein to expose the ground circuits 22a, and an electromagnetic wave shielding film 10 arranged on the printed wiring board 20.

[0045] In the shielded printed wiring board 1 , the conductive bumps 14 of the electromagnetic wave shielding film 10 penetrate the adhesive layer 13 and are in contact with the ground circuit 22 a of the printed wiring board 20 .

[0046] Here, the reason why transmission loss increases when an electromagnetic shielding film having conductive bumps arranged at equal intervals in a straight line is used for a printed wiring board will be explained. Generally, a signal circuit separate from the ground circuit is placed near the ground circuit of a printed wiring board. When an electromagnetic shielding film is placed on a printed wiring board, the conductive bumps of the electromagnetic shielding film may be located on such a signal circuit, which may result in a parasitic circuit and increase transmission loss. In particular, if the conductive bumps are arranged at equal intervals on a straight line, and the direction in which the conductive bumps are arranged coincides with the direction in which the signal circuits are formed, the number of conductive bumps located above the signal circuits increases, resulting in a large number of parasitic circuits and large transmission loss. Furthermore, when there are multiple signal circuits, the number of parasitic circuits generated between the signal circuits and the conductive bumps may differ from one signal circuit to another, which further increases the transmission loss.

[0047] However, in the electromagnetic wave shielding film 10, the conductive bumps 14 are not arranged at equal intervals in a straight line, so that the conductive bumps 14 located above the signal circuit of the printed wiring board 20 can be prevented from creating a parasitic circuit, thereby reducing transmission loss.

[0048] Next, the positional relationship between the conductive bumps 14 and the ground circuit 22a will be described. Fig. 3 is a cross-sectional view taken along line AA in Fig. 2. For ease of explanation, Fig. 3 shows only one ground circuit 22a. As shown in FIG. 3, the ground circuit 22a is formed in a straight line. 3, when the conductive bumps 14 of the electromagnetic shielding film 10 are arranged in a regular zigzag pattern, the conductive bumps 14 can be reliably brought into contact with the ground circuit 22a. In other words, even if the conductive bump 14g is arranged in a position where it cannot be in contact with the ground circuit 22a, the conductive bump 14f can be in contact with the ground circuit 22a. Therefore, in shielded printed wiring board 1, the connection stability between shield layer 12 of electromagnetic wave shielding film 10 and ground circuit 22a of printed wiring board 20 can be increased.

[0049] The following describes problems that arise due to the positional relationship between the conductive bumps and the ground circuit when the conductive bumps are arranged at equal intervals on a straight line in an electromagnetic wave shielding film. FIG. 4 is a plan view showing an example of a positional relationship between conductive bumps and a ground circuit in a shielded printed wiring board having an electromagnetic shielding film in which conductive bumps are arranged at equal intervals on a straight line.

[0050] As shown in Fig. 4, if conductive bumps 14' are arranged only on a straight line, when the direction in which ground circuit 22a is formed coincides with the arrangement direction of conductive bumps 14', and conductive bumps 14' are positioned so as not to come into contact with ground circuit 22a, none of conductive bumps 14' arranged on that straight line will be able to come into contact with ground circuit 22a. This is particularly likely to occur when ground circuit 22a is narrow. As a result, the shielding layer of the electromagnetic shielding film and ground circuit 22a of the printed wiring board will not be able to be electrically connected via conductive bumps 14' arranged on that straight line.

[0051] However, in the case of shielded printed wiring board 1 using electromagnetic wave shielding film 10 as described above, such a problem is unlikely to occur.

[0052] Next, preferred embodiments of each component of the electromagnetic wave shielding film 10 will be described.

[0053] (protective layer) The material of the protective layer 11 is not particularly limited, but it is preferable that the protective layer 11 is made of a thermoplastic resin composition, a thermosetting resin composition, an active energy ray curable composition, or the like.

[0054] Examples of the thermoplastic resin composition include, but are not limited to, a styrene-based resin composition, a vinyl acetate-based resin composition, a polyester-based resin composition, a polyethylene-based resin composition, a polypropylene-based resin composition, an imide-based resin composition, and an acrylic-based resin composition.

[0055] The thermosetting resin composition is not particularly limited, but may be at least one resin composition selected from the group consisting of an epoxy-based resin composition, a urethane-based resin composition, a urethane urea-based resin composition, a styrene-based resin composition, a phenol-based resin composition, a melamine-based resin composition, an acrylic-based resin composition, and an alkyd-based resin composition.

[0056] The active energy ray-curable composition is not particularly limited, but examples thereof include polymerizable compounds having at least two (meth)acryloyloxy groups in the molecule.

[0057] The protective layer 11 may be made of a single material, or may be made of two or more materials.

[0058] The protective layer 11 may contain, as necessary, a curing accelerator, a tackifier, an antioxidant, a pigment, a dye, a plasticizer, an ultraviolet absorber, an antifoaming agent, a leveling agent, a filler, a flame retardant, a viscosity adjuster, an antiblocking agent, and the like.

[0059] The thickness of the protective layer 11 is not particularly limited and can be appropriately set as necessary, but is preferably 1 to 15 μm, and more preferably 3 to 10 μm. If the thickness of the protective layer is less than 1 μm, it is too thin and it becomes difficult to adequately protect the shielding layer and the adhesive layer. If the thickness of the protective layer exceeds 15 μm, the protective layer is too thick and is difficult to bend, and the protective layer itself is easily damaged, making it difficult to apply to members that require resistance to bending.

[0060] (Shield layer) The material of the shield layer 12 is not particularly limited as long as it can shield electromagnetic waves, and may be made of, for example, a metal or a conductive resin.

[0061] When the shield layer 12 is made of a metal, examples of the metal include gold, silver, copper, aluminum, nickel, tin, palladium, chromium, titanium, zinc, etc. Among these, copper is preferable. Copper is a suitable material for the shield layer from the viewpoints of electrical conductivity and economy.

[0062] The shield layer 12 may be made of an alloy of the above metals. Moreover, the shield layer 12 may be a metal foil, or a metal film formed by a method such as sputtering, electroless plating, or electrolytic plating.

[0063] When the shield layer 12 is made of a conductive resin, the shield layer 12 may be composed of conductive particles and a resin.

[0064] The conductive particles are not particularly limited, but may be metal fine particles, carbon nanotubes, carbon fibers, metal fibers, or the like.

[0065] When the conductive particles are metal microparticles, the metal microparticles may be, but are not limited to, silver powder, copper powder, nickel powder, solder powder, aluminum powder, silver-coated copper powder obtained by silver plating copper powder, polymer microparticles, glass beads, or the like, coated with metal, and the like. Among these, from the viewpoint of economy, copper powder or silver-coated copper powder, which is inexpensively available, is preferable.

[0066] Average particle diameter of conductive particles D 50 is not particularly limited, but is preferably 0.5 to 15.0 μm. When the average particle size of the conductive particles is 0.5 μm or more, the conductivity of the conductive resin is good. When the average particle size of the conductive particles is 15.0 μm or less, the conductive resin can be made thin.

[0067] The shape of the conductive particles is not particularly limited, but can be appropriately selected from spherical, flat, scale-like, dendritic, rod-like, fibrous, and the like.

[0068] The blending amount of the conductive particles is not particularly limited, but is preferably 15 to 80 mass %, and more preferably 15 to 60 mass %.

[0069] Examples of the resin include, but are not limited to, thermoplastic resin compositions such as a styrene-based resin composition, a vinyl acetate-based resin composition, a polyester-based resin composition, a polyethylene-based resin composition, a polypropylene-based resin composition, an imide-based resin composition, an amide-based resin composition, and an acrylic-based resin composition; and thermosetting resin compositions such as a phenol-based resin composition, an epoxy-based resin composition, a urethane-based resin composition, a melamine-based resin composition, and an alkyd-based resin composition.

[0070] (Conductive bump) The conductive bumps 14 penetrate the adhesive layer 13 and come into contact with the ground circuit 22a. The shape of the conductive bump 14 is not particularly limited, and may be a columnar shape such as a cylinder, a triangular prism, or a square prism, or may be a pyramidal shape such as a cone, a triangular pyramid, or a square pyramid. Among these, the pyramidal shape is preferred. When conductive bump 14 has a cone-like shape, conductive bump 14 can easily penetrate adhesive layer 13 and can easily come into contact with ground circuit 22a.

[0071] The volume of each conductive bump 14 is 30,000 to 400,000 μm 3 It is preferable that the thickness is 50,000 to 400,000 μm. 3 It is more preferable that: When the volume of each conductive bump 14 is within the above range, the conductive bump 14 can be in firm contact with the ground circuit 22a. The volume of each conductive bump is 30,000 μm 3 If it is less than this, it becomes difficult for the conductive bumps to come into contact with the ground circuit, and the connection resistance between the ground circuit and the shield layer is likely to increase. The volume of each conductive bump is 400,000 μm 3 If the thickness exceeds this value, the proportion of the conductive bumps in the adhesive layer will increase. This tends to increase the relative dielectric constant and the dielectric loss tangent in the entire area where the adhesive layer is present, which tends to deteriorate the transmission characteristics.

[0072] It is preferable that the heights of the multiple conductive bumps 14 (heights indicated by the symbol "H" in FIG. 1A) are approximately the same. When the conductive bumps 14 have approximately the same height, the conductive bumps 14 penetrate the adhesive layer 13 evenly and are more likely to come into contact with the ground circuit 22a.

[0073] The height of the conductive bump 14 is preferably 1 to 50 μm, and more preferably 5 to 30 μm.

[0074] The shape, height, and volume of the conductive bumps can be analyzed using data analysis software (LMeye7) after measuring any five points on the surface of the shield layer on which the conductive bumps are formed using a confocal microscope (Lasertec, OPTELICS HYBRID, 20x objective lens).The binarization parameter is height, and the Kittler method can be used as the automatic threshold algorithm.

[0075] The conductive bump 14 is preferably made of a resin composition and a conductive filler. That is, the conductive bumps 14 may be made of a conductive paste. By using the conductive paste, the conductive bumps 14 can be easily formed in any desired shape at any desired position. The conductive bumps 14 may also be formed by screen printing. When conductive bumps 14 are formed by screen printing using a conductive paste, conductive bumps 14 can be easily and efficiently formed in any desired shape at any desired position.

[0076] When the conductive bump 14 is composed of a resin composition and a conductive filler, the resin composition is not particularly limited, but examples of the resin composition that can be used include thermoplastic resin compositions such as a styrene-based resin composition, a vinyl acetate-based resin composition, a polyester-based resin composition, a polyethylene-based resin composition, a polypropylene-based resin composition, an imide-based resin composition, an amide-based resin composition, and an acrylic-based resin composition, and thermosetting resin compositions such as a phenol-based resin composition, an epoxy-based resin composition, a urethane-based resin composition, a melamine-based resin composition, and an alkyd-based resin composition. The resin composition may consist of one of these materials alone or a combination of two or more of them.

[0077] When the conductive bump 14 is made of a resin composition and a conductive filler, the conductive filler is not particularly limited, but may be metal fine particles, carbon nanotubes, carbon fibers, metal fibers, or the like.

[0078] When the conductive filler is a metal microparticle, the metal microparticle may be, but is not limited to, silver powder, copper powder, nickel powder, solder powder, aluminum powder, silver-coated copper powder obtained by silver plating copper powder, or microparticles obtained by coating polymer microparticles or glass beads with metal. Among these, from the viewpoint of economy, copper powder or silver-coated copper powder, which is inexpensively available, is preferable.

[0079] Average particle diameter of conductive filler D 50 Although there are no particular limitations, it is preferably 0.5 to 15.0 μm.

[0080] The shape of the conductive filler is not particularly limited, but can be appropriately selected from spherical, flat, scale-like, dendritic, rod-like, fibrous, and the like.

[0081] When the conductive bump 14 is made of a resin composition and a conductive filler, the weight percentage of the conductive filler is preferably 30 to 99%, and more preferably 50 to 99%.

[0082] Moreover, the conductive bumps 14 may be made of a metal formed by plating, vapor deposition or the like. In this case, the conductive bumps are preferably made of copper, silver, tin, gold, palladium, aluminum, chromium, titanium, zinc, or an alloy containing one or more of these. Conventional plating and vapor deposition methods can be used.

[0083] (adhesive layer) As described above, the electromagnetic wave shielding film 10 is adhered to the printed wiring board 20 by the adhesive layer 13 .

[0084] In the electromagnetic wave shielding film 10, the surface of the adhesive layer 13 opposite to the surface in contact with the shielding layer 12 is preferably flat. If this surface is flat, then the conductive bumps 14 will penetrate the adhesive layer 13 evenly. Therefore, the conductive bumps 14 come into even contact with the ground circuits 22a.

[0085] In the electromagnetic wave shielding film 10, the thickness of the adhesive layer 13 is preferably from 5 to 30 μm, and more preferably from 8 to 20 μm. If the thickness of the adhesive layer is less than 5 μm, the amount of resin constituting the adhesive layer is small, making it difficult to obtain sufficient adhesive performance, and the adhesive layer is also prone to breakage. If the thickness of the adhesive layer exceeds 30 μm, the whole board becomes too thick and tends to lose flexibility, and it becomes difficult for the conductive bumps to penetrate the adhesive layer.

[0086] In the electromagnetic wave shielding film 10, the resin constituting the adhesive layer 13 preferably has a relative dielectric constant of 1-5, and more preferably 2-4, at a frequency of 1 GHz and 23°C. Furthermore, the dielectric loss tangent of the resin constituting the adhesive layer 13 at a frequency of 1 GHz and 23° C. is preferably 0.0001 to 0.03, and more preferably 0.001 to 0.002. Within such a range, the transmission characteristics of the shielded printed wiring board 1 produced using the electromagnetic wave shielding film 10 can be improved.

[0087] In the electromagnetic wave shielding film 10, the adhesive layer 13 may be a conductive adhesive layer or an insulating adhesive layer. From the viewpoint of reducing the relative dielectric constant and dielectric tangent, however, it is preferable that the adhesive layer 13 be an insulating adhesive layer. As described above, the electromagnetic wave shielding film 10 is adhered to the printed wiring board 20 by the adhesive layer 13 . When the adhesive layer 13 is an insulating adhesive layer, the adhesive layer 13 does not contain a conductive material such as a conductive filler, and therefore the relative dielectric constant and the dielectric loss tangent are sufficiently small. In this case, the shielded printed wiring board 1 produced using the electromagnetic shielding film 10 has good transmission characteristics.

[0088] In addition, when the adhesive layer 13 has conductivity, the adhesive layer 13 contains a conductive material such as a conductive filler. When the adhesive layer 13 contains a large amount of such a conductive material, the relative dielectric constant and the dielectric loss tangent of the entire adhesive layer 13 tend to be high. On the other hand, in order to improve the transmission characteristics of the shielded printed wiring board 1 to be manufactured, it is preferable that the relative dielectric constant and dielectric loss tangent of the entire adhesive layer 13 are low. Therefore, even if the adhesive layer 13 contains a conductive substance, the content is preferably small so that the adhesive layer 13 as a whole has a low relative dielectric constant and a low dielectric loss tangent.

[0089] The adhesive layer 13 may be made of a thermosetting resin composition or a thermoplastic resin composition.

[0090] Examples of the thermosetting resin composition include a phenol-based resin composition, an epoxy-based resin composition, a urethane-based resin composition, a melamine-based resin composition, a polyamide-based resin composition, and an alkyd-based resin composition. Examples of the thermoplastic resin composition include a styrene-based resin composition, a vinyl acetate-based resin composition, a polyester-based resin composition, a polyethylene-based resin composition, a polypropylene-based resin composition, an imide-based resin composition, and an acrylic-based resin composition. The epoxy resin composition is more preferably an amide-modified epoxy resin composition. These resin compositions are suitable as the resin that constitutes the adhesive layer. The adhesive layer may be made of one of these materials alone or a combination of two or more of them.

[0091] Next, preferred embodiments of each component of the printed wiring board 20 will be described.

[0092] (Base film and coverlay) The materials of the base film 21 and the coverlay 23 are not particularly limited, but are preferably made of engineering plastics. Examples of such engineering plastics include resins such as polyethylene terephthalate, polypropylene, cross-linked polyethylene, polyester, polybenzimidazole, polyimide, polyimideamide, polyetherimide, and polyphenylene sulfide. Among these engineering plastics, polyphenylene sulfide film is preferable when flame retardancy is required, and polyimide film is preferable when heat resistance is required. The thickness of the base film 21 is preferably 10 to 40 μm, and the thickness of the coverlay 23 is preferably 10 to 30 μm.

[0093] The size of the opening 23a is not particularly limited, but is preferably 0.1 mm 2 It is preferable that the thickness is 0.3 mm or more. 2 More preferably, it is equal to or greater than this. Furthermore, the shape of the opening 23a is not particularly limited, and may be a circle, an ellipse, a rectangle, a triangle, or the like.

[0094] (Printed Circuits) The material of the printed circuit 22 and the ground circuit 22a is not particularly limited, and may be copper foil, a hardened conductive paste, or the like.

[0095] Next, another arrangement of the conductive bumps in the electromagnetic wave shielding film according to the first embodiment of the present invention will be described. As described above, in the electromagnetic wave shielding film 10, the conductive bumps 14 are arranged so as to be located at the vertices of each of the equilateral triangles 51a and each of the squares 52a that are formed by tessellating the plane with the equilateral triangles 51a and the squares 52a. However, in the electromagnetic wave shielding film according to the first embodiment of the present invention, the conductive bumps may be arranged, for example, as shown in the following Figs. 5A to 5F. 5A to 5F are plan views each showing a schematic example of an arrangement of conductive bumps when the shielding layer of the electromagnetic wave shielding film according to the first embodiment of the present invention is viewed in plan from the adhesive layer side. In Figures 5A to 5F, some polygons are exaggerated for ease of explanation, but in the electromagnetic wave shielding film of the present invention, there are no structural or functional differences between the exaggerated polygons and other polygons.

[0096] As shown in FIG. 5A, there are two types of polygons that fill the plane: rhombus 151A and regular hexagon 152A, and the length of one side of rhombus 151A may be equal to the length of one side of regular hexagon 152A. Moreover, conductive bumps 114A are arranged so as to be located at the vertices of diamond 151A and regular hexagon 152A.

[0097] As shown in FIG. 5B, there are two types of polygons that fill the plane: an equilateral triangle 151B and a regular hexagon 152B. The length of one side of the equilateral triangle 151B may be equal to the length of one side of the regular hexagon 152B. Conductive bumps 114B are arranged so as to be located at the vertices of equilateral triangle 151B and equilateral hexagon 152B.

[0098] As shown in FIG. 5C, there are three types of polygons that fill the plane: an equilateral triangle 151C, a square 152C, and a regular hexagon 153C. The length of one side of the equilateral triangle 151C, the length of one side of the square 152C, and the length of one side of the regular hexagon 153C may be equal. Conductive bumps 114C are arranged so as to be located at the vertices of equilateral triangle 151C, square 152C, and regular hexagon 153C.

[0099] As shown in FIG. 5D, there are two types of polygons that fill the plane: an equilateral triangle 151D and a regular dodecagon 152D, and the length of one side of the equilateral triangle 151D may be equal to the length of one side of the regular dodecagon 152D. Conductive bumps 114D are arranged so as to be located at the vertices of equilateral triangle 151D and regular dodecagon 152D.

[0100] As shown in FIG. 5E, there are two types of polygons that fill the plane: a square 151E and a regular octagon 152E, and the length of one side of the square 151E may be equal to the length of one side of the regular octagon 152E. Conductive bumps 114E are arranged so as to be located at the vertices of square 151E and regular octagon 152E.

[0101] As shown in FIG. 5F, there are three types of polygons that fill the plane: a square 151F, a regular hexagon 152F, and a regular dodecagon 153F. The length of one side of the square 151F, the length of one side of the regular hexagon 152F, and the length of one side of the regular dodecagon 153F may be equal. Conductive bumps 114F are arranged so as to be located at the vertices of a square 151F, a regular hexagon 152F, and a regular dodecagon 153F.

[0102] When an electromagnetic wave shielding film having conductive bumps 114A-114F arranged as described above is arranged on a printed wiring board, it is possible to prevent the conductive bumps from being located above the signal circuit of the printed wiring board, thereby reducing transmission loss.

[0103] The conductive bumps described so far are arranged so as to be located at the vertices of two or more types of regular polygons that are filled into a plane. However, in the electromagnetic wave shielding film according to the first embodiment of the present invention, the arrangement of the conductive bumps is not limited to the above arrangement, so long as the conductive bumps are arranged so that they are located at the vertices of each of the polygons formed by filling a plane with two or more types of polygons, and, for each of the conductive bumps, a line segment is drawn connecting each conductive bump to the nearest conductive bump, and a straight line is drawn passing through one of those line segments, so that the straight line has a portion that does not overlap with the other line segments. The polygon to be filled may be a convex polygon other than a regular polygon, or a non-convex polygon.

[0104] Second embodiment Next, an electromagnetic wave shielding film according to a second embodiment of the present invention will be described. A second embodiment of the electromagnetic wave shielding film of the present invention includes a protective layer, a shielding layer laminated on the protective layer, and an adhesive layer laminated on the shielding layer, and a plurality of conductive bumps are formed on the adhesive layer side of the shielding layer, the plurality of conductive bumps include a first conductive bump and a second conductive bump closest to the first conductive bump, and when the shielding layer is viewed in a plan view from the adhesive layer side, other conductive bumps are arranged on a straight line a connecting the first conductive bump and the second conductive bump, and, regarding the conductive bumps arranged on the straight line a, the distance between the farthest conductive bumps is defined as D1 and the distance from the first conductive bump to the second conductive bump is defined as D2, and the number of the conductive bumps arranged on the straight line a is less than D1 / D2+1. As long as the electromagnetic wave shielding film according to the second embodiment of the present invention has such characteristics, it may have any other characteristics as long as the effects of the invention are achieved. More specifically, "the distance between the conductive bumps arranged on the straight line a is the farthest distance D1" means the following distance. First, determine the position of the intersection point where the straight line a intersects with the end of the shield layer. Select a conductive bump located on the straight line a and closest to one of the intersection points, and a conductive bump located on the straight line a and closest to the other intersection point. The distance between these conductive bumps is distance D1.

[0105] FIG. 6A is a cross-sectional view that illustrates an example of an electromagnetic wave shielding film according to a second embodiment of the present invention.

[0106] As shown in FIG. 6A, electromagnetic wave shielding film 210 includes protective layer 211, shielding layer 212 laminated on protective layer 211, and adhesive layer 213 laminated on shielding layer 212. Furthermore, a plurality of conductive bumps 214 are formed on the adhesive layer 213 side of the shield layer 212 .

[0107] The arrangement of the conductive bumps 214 on the electromagnetic wave shielding film 210 will be described. FIG. 6B is a plan view that illustrates a schematic arrangement of conductive bumps when the shielding layer of the electromagnetic wave shielding film illustrated in FIG. 6A is viewed from the adhesive layer side.

[0108] As shown in FIG. 6B, conductive bump 214 includes a first conductive bump 214a1 and a second conductive bump 214a2 located closest to first conductive bump 214a1. Furthermore, when a straight line a3 is drawn passing through the first conductive bump 214a1 and the second conductive bump 214a2, the other conductive bumps 214b1, 214b2, 214b3, 214b4, and 214b5 are arranged on the straight line a3 outside the first conductive bump 214a1 and the second conductive bump 214a2. The arrangement order of the conductive bumps is the conductive bump 214b1, the conductive bump 214b2, the first conductive bump 214a1, the second conductive bump 214a2, the conductive bump 214b3, the conductive bump 214b4, and the conductive bump 214b5. Although FIG. 6B illustrates only the conductive bumps arranged on the straight line a3 for the sake of convenience, the electromagnetic wave shielding film 210 may have conductive bumps formed on places other than the straight line a3.

[0109] Furthermore, when any two conductive bumps 214 are selected from the conductive bumps 214 arranged on the straight line a3, if the longest distance between the two selected conductive bumps 214 (the distance from conductive bump 214b1 to conductive bump 214b5 in FIG. 6B) is taken as D1 and the distance from the first conductive bump 214a1 to the second conductive bump 214a2 is taken as D2, then the number of conductive bumps 214 arranged on the straight line a3 is less than D1 / D2+1. The electromagnetic wave shielding film having such a characteristic means that the conductive bumps 214 are not arranged at equal intervals on the straight line a3.

[0110] This point will be explained in more detail with reference to the drawings. FIG. 7 is a plan view showing a schematic arrangement of conductive bumps of an electromagnetic wave shielding film in which the conductive bumps are arranged at equal intervals on a straight line.

[0111] As shown in FIG. 7, a total of seven conductive bumps, ie, conductive bump 214c1 to conductive bump 214c7, are arranged in order at equal intervals on a line b. When any two of these conductive bumps are selected, the distance between the selected conductive bumps is the longest when conductive bump 214c1 and conductive bump 214c7 are selected. Therefore, if the distance from conductive bump 214c1 to conductive bump 214c7 is D3, and the distance between each conductive bump is D4, then the following equation holds: D4×(total number of conductive bumps−1)=D4×6=D3. This formula can be rearranged to D3 / D4=6 (total number of conductive bumps - 1), which can be rearranged further to D3 / D4+1=total number of conductive bumps. In other words, this formula holds true when the conductive bumps are arranged at equal intervals on a straight line.

[0112] On the other hand, as shown in FIG. 6B, when the conductive bumps 214 are not arranged at equal intervals on the straight line a3, even if the distance D2 between the conductive bumps 14 that is the minimum on the straight line a3 is multiplied by (the total number of conductive bumps - 1), it is less than the distance D1. Expressing this as an equation, D2 × (the total number of conductive bumps - 1) < D1. Transforming this equation gives (the total number of conductive bumps - 1) < D1 / D2, and further transforming this equation gives the total number of conductive bumps < D1 / D2 + 1. That is, if the number of the conductive bumps 214 is less than D1 / D2 + 1, it can be said that the conductive bumps 214 are not arranged at equal intervals on the straight line.

[0113] Since the electromagnetic shielding film 210 has such an arrangement of conductive bumps (that is, since the conductive bumps 214 are not arranged at equal intervals on the straight line), when the electromagnetic shielding film 210 is arranged on the printed wiring board, it is possible to suppress the occurrence of a parasitic circuit due to the conductive bumps 214 being located on the signal circuit of the printed wiring board. As a result, the transmission loss can be reduced.

[0114] Regarding other than the above arrangement of the conductive bumps, the preferable materials of the protective layer 211, the shield layer 212, the adhesive layer 213, and the conductive bumps 214 that constitute the electromagnetic shielding film 210 according to the second embodiment of the present invention are the same as the preferable materials of the protective layer 11, the shield layer 12, the adhesive layer 13, and the conductive bumps 14 that constitute the electromagnetic shielding film 10 according to the first embodiment of the present invention.

Explanation of Reference Numerals

[0115] 1 Shielded printed wiring board 10, 210 Electromagnetic shielding film 11, 211 Protective layer 12, 212 Shield layer 13, 213 Adhesive layer 14, 14a, 14b, 14c, 14d, 14e, 14f, 14g, 114A, 114B, 114C, 114D, 114E, 114F, 214 Conductive bumps 20 Printed wiring board 21 Base film 22 Printed Circuits 22a Ground Circuit 23 Coverlay 23a opening 214a1 first conductive bump 214a2 second conductive bump 214b1, 214b2, 214b3, 214b4, 214b4 and other conductive bumps 14', 214c1, 214c2, 214c3, 214c4, 214c5, 214c6, 214c7 Conductive bumps arranged at equal intervals on a straight line

Claims

1. A protective layer; a shielding layer laminated on the protective layer; an adhesive layer laminated on the shielding layer, a plurality of conductive bumps are formed on the adhesive layer side of the shield layer, When the shielding layer is viewed from the adhesive layer side, The conductive bumps are arranged so as to be located at vertices of each of two or more polygons that are filled into a plane, and an electromagnetic wave shielding film characterized in that, for each of the plurality of conductive bumps, a line segment is drawn connecting each of the conductive bumps to a nearest conductive bump located closest to the respective bump, and a straight line passing through one of the line segments is drawn, and there is an area on the straight line where the conductive bumps are not arranged at equal intervals.

2. 2 . The electromagnetic wave shielding film according to claim 1 , wherein the polygons are of two types, an equilateral triangle and a square, and a length of one side of the equilateral triangle is equal to a length of one side of the square.

3. 2 . The electromagnetic wave shielding film according to claim 1 , wherein the polygons are of two types, a rhombus and a regular hexagon, and the length of one side of the rhombus is equal to the length of one side of the regular hexagon.

4. 2 . The electromagnetic wave shielding film according to claim 1 , wherein the polygons are of two types, an equilateral triangle and a regular hexagon, and a length of one side of the equilateral triangle is equal to a length of one side of the regular hexagon.

5. 2. The electromagnetic wave shielding film according to claim 1, wherein the polygons are of three types: an equilateral triangle, a square, and a regular hexagon, and the length of one side of the equilateral triangle, the length of one side of the square, and the length of one side of the regular hexagon are equal.

6. 2 . The electromagnetic wave shielding film according to claim 1 , wherein the polygons are of two types, an equilateral triangle and a regular dodecagon, and a length of one side of the equilateral triangle is equal to a length of one side of the regular dodecagon.

7. 2 . The electromagnetic wave shielding film according to claim 1 , wherein the polygons are of two types, a square and a regular octagon, and the length of one side of the square is equal to the length of one side of the regular octagon.

8. 2. The electromagnetic wave shielding film according to claim 1, wherein the polygons are of three types: a square, a regular hexagon, and a regular dodecagon, and the length of one side of the square, the length of one side of the regular hexagon, and the length of one side of the regular dodecagon are equal.

9. A protective layer; a shielding layer laminated on the protective layer; an adhesive layer laminated on the shielding layer, a plurality of conductive bumps are formed on the adhesive layer side of the shield layer, When the shielding layer is viewed from the adhesive layer side, the conductive bumps are arranged to be located at vertices of two or more polygons that are filled into a plane, the plurality of conductive bumps includes a first conductive bump and a second conductive bump located closest to the first conductive bump; when the shielding layer is viewed in a plan view from the adhesive layer side, and a straight line a is drawn passing through the first conductive bump and the second conductive bump, another conductive bump is disposed on the straight line a outside the first conductive bump and the second conductive bump, When any two of the conductive bumps are selected from the conductive bumps arranged on the straight line a, the distance between the selected two conductive bumps is the longest, and the distance between the selected two conductive bumps is defined as D. １ and the distance from the first conductive bump to the second conductive bump is D ２ Then, the number of the conductive bumps arranged on the straight line a is D １ / D ２ +1 or less.

Images