Shielded printed circuit board

Abstract

To provide a shielded printed wiring board in which adhesive layers of electromagnetic wave shielding films attached to one and the other surfaces of the printed wiring board are sufficiently adhered to each other. [Solution] A shielded printed wiring board (454) includes a printed wiring board (410) including a base film (411), a printed circuit (412), and a coverlay (413), a first insulating layer (422) arranged to cover one side of the printed wiring board, and a second insulating layer (432) arranged to cover the other side. A portion of the first insulating layer forms a first insulating layer extension (422a) located outside the edge of the printed wiring board, and a portion of the second insulating layer forms a second insulating layer extension (432a), with the first insulating layer extension and the second insulating layer extension facing each other. The areas between each insulating layer and the printed wiring board and where the insulating layer extensions face each other are filled with a conductive resin composition (463), and the thickness of the filled conductive resin composition is 1 / 30 to 9 / 10 times the thickness of the printed wiring board.

Description

Technical Field

[0001] The present invention relates to a shield printed wiring board.

Background Art

[0002] Flexible printed wiring boards are widely used in electronic devices such as mobile phones, video cameras, and notebook computers, where miniaturization and high functionality are rapidly progressing, in order to incorporate circuits into complex mechanisms. Furthermore, taking advantage of their excellent flexibility, they are also used for connecting movable parts such as printer heads to control parts. In these electronic devices, electromagnetic shielding measures are essential, and in the flexible printed wiring boards used within the device, flexible printed wiring boards with electromagnetic shielding measures (hereinafter, also referred to as "shield printed wiring boards") have come to be used.

[0003] Examples of shield printed wiring boards include printed wiring boards formed by sequentially providing a printed circuit and a coverlay on a base film, and those composed of an electromagnetic shielding film including an adhesive layer, a shielding layer laminated on the adhesive layer, and an insulating layer laminated on the shielding layer. The electromagnetic shielding film is laminated on the printed wiring board such that the adhesive layer contacts the printed wiring board, and the shield printed wiring board is obtained by adhering the adhesive layer to the printed wiring board.

[0004] Also, Patent Document 1 discloses a shield printed wiring board having shielding layers formed on both sides of a printed wiring board and a method for manufacturing the same.

Prior Art Documents

[0006] Patent Document 1 discloses a method for forming a shielding layer on both sides of a printed circuit board by laminating a conductive adhesive film (i.e., an electromagnetic wave shielding film) to both sides of the printed circuit board.

[0007] When manufacturing shielded printed circuit boards using this method, the electromagnetic shielding film on the front and the electromagnetic shielding film on the back are bonded together via the adhesive layer of each electromagnetic shielding film. In this process, a gap may occur between the adhesive layer of the front electromagnetic shielding film and the adhesive layer of the back electromagnetic shielding film. Shielded printed circuit boards are used to mount electronic components, and during the mounting of these components, the shielded printed circuit boards are heated.

[0008] When a shielded printed circuit board is heated, if there is a gap between the adhesive layer of the electromagnetic shielding film on the surface and the adhesive layer of the electromagnetic shielding film on the back, the air in the gap expands due to the heat. As a result, a problem sometimes occurs where the adhesive layers of the electromagnetic shielding film on the surface and the adhesive layers of the electromagnetic shielding film on the back separate.

[0009] The present invention has been made in view of the above problems, and the object of the present invention is to provide a method for manufacturing a shielded printed circuit board that can sufficiently adhere the printed circuit board, the adhesive layer of the electromagnetic wave shielding film attached to one side, and the adhesive layer of the electromagnetic wave shielding film attached to the other side. [Means for solving the problem]

[0010] In other words, the method for manufacturing a shielded printed circuit board according to the present invention is: A printed circuit board preparation step, comprising a base film, a printed circuit formed on the base film, and a coverlay covering the printed circuit, A first electromagnetic wave shielding film preparation step involves preparing a first electromagnetic wave shielding film in which a first protective film, a first insulating layer, and a first adhesive layer are arranged in that order, A second electromagnetic wave shielding film preparation step involves preparing a second electromagnetic wave shielding film in which a second protective film, a second insulating layer, and a second adhesive layer are arranged in that order, A first electromagnetic shielding film placement step is to place the first electromagnetic shielding film on the printed circuit board such that the first adhesive layer is in contact with one surface of the printed circuit board, and to position a portion of the first adhesive layer outside the edge of the printed circuit board to form a first extended edge, A second electromagnetic shielding film placement step, which involves placing the second electromagnetic shielding film on the printed circuit board such that the second adhesive layer is in contact with the other surface of the printed circuit board, and positioning a portion of the second adhesive layer outside the edge of the printed circuit board to form a second extended edge, A superimposing step is performed to manufacture a pre-press shielded printed circuit board by overlapping the first and second extension ends so that a gap is created between them, A temporary pressing step is performed in which the shield printed circuit board is pressurized and heated before temporary pressing so that the first adhesive layer and the second adhesive layer do not completely harden, and the shield printed circuit board is manufactured after temporary pressing. The protective film peeling step involves peeling off the first protective film and the second protective film from the shielded printed circuit board after the preliminary press to produce a shielded printed circuit board before the main press. The present invention is characterized by including a pressing step, in which the above-mentioned pre-press shielded printed circuit board is pressurized and heated to cure the first adhesive layer and the second adhesive layer, thereby forming a shielded printed circuit board.

[0011] In the manufacturing method of the shielded printed circuit board of the present invention, the first adhesive layer and the second adhesive layer are overlapped in the overlapping step such that a gap is created in a part between the first extended end and the second extended end. In the method for manufacturing a shielded printed circuit board of the present invention, the first adhesive layer and the second adhesive layer are cured in two stages by performing a preliminary pressing step and a main pressing step, as described later. Even if a gap occurs between the first and second extension ends during the overlapping process, these steps allow air to be removed from the gap, ensuring sufficient adhesion between the first and second adhesive layers. Furthermore, in this process, attempting to overlap the first and second adhesive layers to prevent the formation of such gaps would require applying high pressure and time, resulting in poor production efficiency.

[0012] In the method for manufacturing shielded printed circuit boards of the present invention, the first adhesive layer and the second adhesive layer are pressurized and heated during the temporary pressing process so that they do not completely harden. That is, the first adhesive layer and the second adhesive layer are kept in a semi-hardened state during the temporary pressing process. By allowing the first and second adhesive layers to partially harden, the positions of the first and second electromagnetic shielding films can be fixed. Therefore, in the protective film peeling process, the first protective film and the second protective film become easier to peel off. Furthermore, since pressure and heating are applied while the first and second protective films are in place, the pressure can be applied evenly. Furthermore, this pressing process makes it easier to remove air from the gap between the first adhesive layer and the second adhesive layer. In this specification, "semi-cured" also includes the B-stage state. Here, the B-stage state is an intermediate stage in which a material swells when it comes into contact with a certain liquid and softens when heated, but does not completely dissolve or melt, as defined in JIS K 6900-1994.

[0013] In the method for manufacturing a shielded printed circuit board of the present invention, the first protective film and the second protective film are peeled off in the protective film peeling step before the pressing step is performed. By peeling off the first protective film and the second protective film, it becomes difficult to absorb the pressure in this pressing process. Therefore, even if there is a gap in a part between the first adhesive layer and the second adhesive layer of the temporary press front shield printed wiring board, by performing this pressing process, air can be sufficiently exhausted from the gap. As a result, in the method for manufacturing a shield printed wiring board of the present invention, the printed wiring board, the first adhesive layer, and the second adhesive layer can be sufficiently adhered to each other.

[0014] That is, in the method for manufacturing a shield printed wiring board of the present invention, since the first adhesive layer and the second adhesive layer are cured in two stages, the printed wiring board, the first adhesive layer, and the second adhesive layer can be sufficiently adhered to each other.

[0015] In the method for manufacturing a shield printed wiring board of the present invention, in the first electromagnetic wave shield film preparation step and the second electromagnetic wave shield film preparation step, after the present pressing step, the total thickness of the first adhesive layer of the first extended end portion and the thickness of the second adhesive layer of the second extended end portion is desirably adjusted so as to be from 1 / 30 times the thickness of the printed wiring board to 1 time the thickness of the printed wiring board. By adjusting the thickness of the first adhesive layer and / or the second adhesive layer within the above range, it becomes easier to sufficiently adhere the first adhesive layer and the second adhesive layer to each other.

[0016] In the first electromagnetic wave shield film prepared in the first electromagnetic wave shield film preparation step in the method for manufacturing a shield printed wiring board of the present invention, a first shield layer may be formed between the first insulating layer and the first adhesive layer. Further, the first shield layer may be made of metal or may be made of a conductive resin composition for the first shield layer. With such a first shield layer, electromagnetic waves can be shielded.

[0017] In the method for manufacturing a shield printed wiring board of the present invention, in the first electromagnetic wave shield film prepared in the first electromagnetic wave shield film preparation step, the first adhesive layer includes a resin for the first adhesive layer and conductive particles for the first adhesive layer, and may have conductivity.

[0018] In the method for manufacturing a shield printed wiring board of the present invention, the first electromagnetic wave shield film prepared in the first electromagnetic wave shield film preparation step has the first insulating layer and the first adhesive layer in close contact with each other. The first adhesive layer includes a resin for the first adhesive layer and conductive particles for the first adhesive layer, and may have conductivity and an electromagnetic wave shielding function. In the first electromagnetic wave shield film having such a configuration, the first adhesive layer has both a function as an adhesive and an electromagnetic wave shielding function.

[0019] In the method for manufacturing a shield printed wiring board of the present invention, it is desirable that the weight ratio of the conductive particles for the first adhesive layer in the first adhesive layer is 3 to 90% by weight. When the weight ratio of the conductive particles for the first adhesive layer is less than 3% by weight, it becomes difficult for the shielding property to be sufficient. When the weight ratio of the conductive particles for the first adhesive layer exceeds 90% by weight, the adhesion between the first adhesive layer and the second adhesive layer tends to decrease. P

[0020] In the method for manufacturing a shield printed wiring board of the present invention, the printed circuit of the printed wiring board prepared in the printed wiring board preparation step includes a ground circuit, and a part of the ground circuit is exposed to the outside. In the present pressing step, pressure and heat may be applied so that the ground circuit and the first adhesive layer are electrically connected. When the printed wiring board has such a structure, the ground circuit and the first adhesive layer can be electrically connected.

[0021] In the method for manufacturing a shielded printed circuit board of the present invention, the second electromagnetic shielding film prepared in the second electromagnetic shielding film preparation step may have a second shielding layer formed between the second insulating layer and the second adhesive layer. Furthermore, the second shield layer may be made of metal, or it may be made of a conductive resin composition for the second shield layer. This second shielding layer can shield against electromagnetic waves.

[0022] In the method for manufacturing a shielded printed circuit board of the present invention, the second electromagnetic shielding film prepared in the second electromagnetic shielding film preparation step may contain a resin for the second adhesive layer and conductive particles for the second adhesive layer, and may be conductive.

[0023] In the method for manufacturing a shielded printed circuit board of the present invention, the second electromagnetic shielding film prepared in the second electromagnetic shielding film preparation step has the second insulating layer and the second adhesive layer in close contact, and the second adhesive layer may contain a resin for the second adhesive layer and conductive particles for the second adhesive layer, and may have conductivity and electromagnetic shielding functions. In a second electromagnetic shielding film with this configuration, the second adhesive layer will have both the function of an adhesive and the function of electromagnetic shielding.

[0024] In the method for manufacturing a shielded printed circuit board of the present invention, it is desirable that the weight percentage of conductive particles for the second adhesive layer in the second adhesive layer is 3 to 90% by weight. If the weight percentage of conductive particles in the second adhesive layer is less than 3% by weight, the shielding effect may not be sufficient. If the weight percentage of conductive particles for the second adhesive layer exceeds 90% by weight, the adhesion between the first adhesive layer and the second adhesive layer tends to decrease.

[0025] In the method for manufacturing a shielded printed circuit board of the present invention, the printed circuit of the printed circuit board prepared in the printed circuit board preparation step includes a ground circuit, a portion of the ground circuit is exposed to the outside, and in the pressing step, pressure and heat may be applied so that the ground circuit and the second adhesive layer are electrically connected. With a printed circuit board having this structure, the ground circuit and the second adhesive layer can be electrically connected.

[0026] In the method for manufacturing a shielded printed circuit board of the present invention, it is desirable that the first insulating layer is at least one selected from polyimide resin, polyamideimide resin, polyamide resin, polyetherimide resin, polyesterimide resin, polyethernitrile resin, polyethersulfone resin, polyphenylene sulfide resin, polyethylene terephthalate resin, polypropylene resin, crosslinked polyethylene resin, polyester resin, polybenzimidazole resin, polyimide resin, polyimideamide resin, polyetherimide resin, and polyphenylene sulfide resin. Furthermore, it is desirable that the second insulating layer is at least one selected from polyimide resins, polyamideimide resins, polyamide resins, polyetherimide resins, polyesterimide resins, polyethernitrile resins, polyethersulfone resins, polyphenylene sulfide resins, polyethylene terephthalate resins, polypropylene resins, crosslinked polyethylene resins, polyester resins, polybenzimidazole resins, polyimide resins, polyimideamide resins, polyetherimide resins, and polyphenylene sulfide resins. In the method for manufacturing a shielded printed circuit board according to the present invention, high pressure is applied to the first extended end and the second extended end during the preliminary pressing process and the main pressing process. If the first insulating layer and / or the second insulating layer are made of the above composition, the strength of the first insulating layer and / or the second insulating layer can be increased. Therefore, even if high pressure is applied to the first and second extension ends during the preliminary pressing process and the main pressing process, damage to the first and / or second insulating layers is less likely to occur.

[0027] In the method for manufacturing shielded printed circuit boards of the present invention, the pressurizing and heating conditions in the preliminary pressing step are preferably 0.2 to 0.7 MPa, 100 to 150°C, and 1 to 10 seconds. When the pressurizing and heating conditions in the preliminary pressing process are within the above range, the first adhesive layer and the second adhesive layer can be suitably brought to a semi-cured state.

[0028] In the method for manufacturing shielded printed circuit boards of the present invention, the pressurizing and heating conditions in the pressing step described above are preferably 1 to 5 MPa, 150 to 190°C, and 60 s to 2 h. When the pressurizing and heating conditions in this pressing process are within the above range, air can be sufficiently removed from the gap between the first adhesive layer and the second adhesive layer, and the first and second adhesive layers can be sufficiently cured.

[0029] The shielded printed circuit board of the present invention comprises a base film, a printed circuit formed on the base film, and a coverlay covering the printed circuit; a first insulating layer disposed to cover one side of the printed circuit board; and a second insulating layer disposed to cover the other side of the printed circuit board, wherein a portion of the first insulating layer forms an extended edge of the first insulating layer located outside the edge of the printed circuit board, and a portion of the second insulating layer forms an extended edge of the second insulating layer located outside the edge of the printed circuit board. The extension end of the first insulating layer and the extension end of the second insulating layer face each other, and the space between the first insulating layer and one surface of the printed circuit board, the space between the second insulating layer and the other surface of the printed circuit board, and the region where the extension end of the first insulating layer and the extension end of the second insulating layer face each other are filled with a conductive resin composition, and the thickness of the conductive resin composition filled between the first insulating layer and the second insulating layer in the region where the extension end of the first insulating layer and the extension end of the second insulating layer face each other is 1 / 30 to 1 times the thickness of the printed circuit board.

[0030] The shielded printed circuit board of the present invention can be manufactured by the method for manufacturing the shielded printed circuit board of the present invention described above. In particular, in the shielded printed circuit board of the present invention, the thickness of the conductive resin composition filled between the first insulating layer and the second insulating layer in the region where the extension ends of the first insulating layer and the extension ends of the second insulating layer face each other is 1 / 30 to 1 times the thickness of the printed circuit board. Therefore, the region where the extension end of the first insulating layer and the extension end of the second insulating layer face each other is filled without any gaps with the conductive resin composition.

[0031] In the shielded printed circuit board of the present invention, it is desirable that a first shielding layer be formed between the first insulating layer and the conductive resin composition. Furthermore, it is desirable that a second shielding layer be formed between the second insulating layer and the conductive resin composition. The first shield layer may be made of metal or of a conductive resin composition for the first shield layer. The second shield layer may also be made of metal or of a conductive resin composition for the second shield layer. When the first shielding layer and the second shielding layer are formed in this manner, electromagnetic waves can be effectively shielded.

[0032] In the shielded printed circuit board of the present invention, the conductive resin composition is preferably an isotropic conductive resin composition. If the conductive resin composition is an isotropic conductive resin composition, electromagnetic noise radiated from the printed circuit board can be effectively blocked.

[0033] In the shielded printed circuit board of the present invention, the conductive resin composition comprises conductive particles and a resin, and the weight percentage of the conductive particles is preferably 3 to 90% by weight, and more preferably 39% to 80% by weight. If the weight percentage of conductive particles is less than 3% by weight, the shielding effect may not be sufficient. When the weight percentage of conductive particles exceeds 90% by weight, the adhesive strength of the conductive resin composition tends to decrease during manufacturing.

[0034] In the shielded printed circuit board of the present invention, the printed circuit of the printed circuit board includes a ground circuit, a portion of the ground circuit is exposed to the outside, and it is desirable that the ground circuit and the conductive resin composition are electrically connected. With a printed circuit board having such a structure, the ground circuit and the conductive resin composition can be electrically connected.

[0035] In the shielded printed circuit board of the present invention, the first insulating layer is preferably at least one selected from polyimide resin, polyamideimide resin, polyamide resin, polyetherimide resin, polyesterimide resin, polyethernitrile resin, polyethersulfone resin, polyphenylene sulfide resin, polyethylene terephthalate resin, polypropylene resin, crosslinked polyethylene resin, polyester resin, polybenzimidazole resin, polyimide resin, polyimideamide resin, polyetherimide resin, and polyphenylene sulfide resin. Furthermore, it is desirable that the second insulating layer is at least one selected from polyimide resins, polyamideimide resins, polyamide resins, polyetherimide resins, polyesterimide resins, polyethernitrile resins, polyethersulfone resins, polyphenylene sulfide resins, polyethylene terephthalate resins, polypropylene resins, crosslinked polyethylene resins, polyester resins, polybenzimidazole resins, polyimide resins, polyimideamide resins, polyetherimide resins, and polyphenylene sulfide resins. If the first insulating layer and / or the second insulating layer are made of the above composition, the strength of the first insulating layer and / or the second insulating layer can be increased. Therefore, damage to the first insulating layer and / or the second insulating layer becomes less likely. [Effects of the Invention]

[0036] In the method for manufacturing a shielded printed circuit board of the present invention, the first adhesive layer and the second adhesive layer are cured in two stages: a preliminary pressing step and a main pressing step. This ensures sufficient adhesion between the printed circuit board, the first adhesive layer, and the second adhesive layer, while also preventing gaps from forming between the first and second extended ends. [Brief explanation of the drawing]

[0037] [Figure 1]Figure 1 is a schematic process diagram showing an example of the printed circuit board preparation step in the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention. [Figure 2] Figure 2 is a schematic process diagram showing an example of the first electromagnetic wave shielding film preparation step in the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention. [Figure 3] Figure 3 is a schematic process diagram showing an example of the second electromagnetic wave shielding film preparation step in the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention. [Figure 4] Figure 4 is a schematic process diagram showing an example of the first electromagnetic wave shielding film placement step in the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention. [Figure 5] Figure 5 is a schematic process diagram showing an example of the second electromagnetic wave shielding film placement step in the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention. [Figure 6] Figure 6 is a schematic process diagram showing an example of the overlapping process in the manufacturing method of a shielded printed circuit board according to the first embodiment of the present invention. [Figure 7] Figure 7 is a schematic process diagram showing an example of a preliminary pressing step in the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention. [Figure 8] Figure 8 is a schematic process diagram showing an example of the protective film peeling step in the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention. [Figure 9A] Figure 9A is a schematic process diagram showing an example of the main pressing step in the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention. [Figure 9B] Figure 9B is a schematic process diagram showing an example of the main pressing step in the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention. [Figure 10] Figure 10 is a schematic process diagram showing an example of the printed circuit board preparation step in the method for manufacturing a shielded printed circuit board according to the second embodiment of the present invention. [Figure 11]Figure 11 is a schematic process diagram showing an example of the first electromagnetic wave shielding film preparation step in the method for manufacturing a shielded printed circuit board according to the second embodiment of the present invention. [Figure 12] Figure 12 is a schematic process diagram showing an example of the second electromagnetic wave shielding film preparation step in the method for manufacturing a shielded printed circuit board according to the second embodiment of the present invention. [Figure 13] Figure 13 is a schematic process diagram showing an example of the first electromagnetic wave shielding film placement step in the method for manufacturing a shielded printed circuit board according to the second embodiment of the present invention. [Figure 14] Figure 14 is a schematic process diagram showing an example of the second electromagnetic wave shielding film placement step in the method for manufacturing a shielded printed circuit board according to the second embodiment of the present invention. [Figure 15] Figure 15 is a schematic process diagram showing an example of the overlapping process in the manufacturing method of a shielded printed circuit board according to the second embodiment of the present invention. [Figure 16] Figure 16 is a schematic process diagram showing an example of a preliminary pressing step in a method for manufacturing a shielded printed circuit board according to a second embodiment of the present invention. [Figure 17] Figure 17 is a schematic process diagram showing an example of the protective film peeling step in the method for manufacturing a shielded printed circuit board according to the second embodiment of the present invention. [Figure 18A] Figure 18A is a schematic process diagram showing an example of the main pressing step in the method for manufacturing a shielded printed circuit board according to the second embodiment of the present invention. [Figure 18B] Figure 18B is a schematic process diagram showing an example of the main pressing step in the method for manufacturing a shielded printed circuit board according to the second embodiment of the present invention. [Figure 19] Figure 19 is a schematic process diagram showing an example of the printed circuit board preparation step in the method for manufacturing a shielded printed circuit board according to the third embodiment of the present invention. [Figure 20] Figure 20 is a schematic process diagram showing an example of the first electromagnetic wave shielding film preparation step in the method for manufacturing a shielded printed circuit board according to the third embodiment of the present invention. [Figure 21]Figure 21 is a schematic process diagram showing an example of the second electromagnetic wave shielding film preparation step in the method for manufacturing a shielded printed circuit board according to the third embodiment of the present invention. [Figure 22] Figure 22 is a schematic process diagram showing an example of the first electromagnetic wave shielding film placement step in the method for manufacturing a shielded printed circuit board according to the third embodiment of the present invention. [Figure 23] Figure 23 is a schematic process diagram showing an example of the second electromagnetic wave shielding film placement step in the method for manufacturing a shielded printed circuit board according to the third embodiment of the present invention. [Figure 24] Figure 24 is a schematic process diagram showing an example of the overlapping process in the manufacturing method of a shielded printed circuit board according to the third embodiment of the present invention. [Figure 25] Figure 25 is a schematic process diagram showing an example of a preliminary pressing step in a method for manufacturing a shielded printed circuit board according to a third embodiment of the present invention. [Figure 26] Figure 26 is a schematic process diagram showing an example of the protective film peeling step in the method for manufacturing a shielded printed circuit board according to the third embodiment of the present invention. [Figure 27A] Figure 27A is a schematic process diagram showing an example of the main pressing step in the manufacturing method of a shielded printed circuit board according to the third embodiment of the present invention. [Figure 27B] Figure 27B is a schematic process diagram showing an example of the main pressing step in the manufacturing method of a shielded printed circuit board according to the third embodiment of the present invention. [Figure 28] Figure 28 is a schematic process diagram showing an example of the printed circuit board preparation step in the method for manufacturing a shielded printed circuit board according to the fourth embodiment of the present invention. [Figure 29] Figure 29 is a schematic process diagram showing an example of the first electromagnetic wave shielding film preparation step in the method for manufacturing a shielded printed circuit board according to the fourth embodiment of the present invention. [Figure 30] Figure 30 is a schematic process diagram showing an example of the second electromagnetic wave shielding film preparation step in the method for manufacturing a shielded printed circuit board according to the fourth embodiment of the present invention. [Figure 31]Figure 31 is a schematic process diagram showing an example of the first electromagnetic wave shielding film placement step in the method for manufacturing a shielded printed circuit board according to the fourth embodiment of the present invention. [Figure 32] Figure 32 is a schematic process diagram showing an example of the second electromagnetic wave shielding film placement step in the method for manufacturing a shielded printed circuit board according to the fourth embodiment of the present invention. [Figure 33] Figure 33 is a schematic process diagram showing an example of the overlapping process in the manufacturing method of a shielded printed circuit board according to the fourth embodiment of the present invention. [Figure 34] Figure 34 is a schematic process diagram showing an example of a preliminary pressing step in a method for manufacturing a shielded printed circuit board according to the fourth embodiment of the present invention. [Figure 35] Figure 35 is a schematic process diagram showing an example of the protective film peeling step in the method for manufacturing a shielded printed circuit board according to the fourth embodiment of the present invention. [Figure 36A] Figure 36A is a schematic process diagram showing an example of the main pressing step in the method for manufacturing a shielded printed circuit board according to the fourth embodiment of the present invention. [Figure 36B] Figure 36B is a schematic process diagram showing an example of the main pressing step in the method for manufacturing a shielded printed circuit board according to the fourth embodiment of the present invention. [Figure 37] Figure 37 is a schematic cross-sectional view showing an example of a shielded printed circuit board according to a fifth embodiment of the present invention. [Modes for carrying out the invention]

[0038] The method for manufacturing a shielded printed circuit board according to the present invention will be described in detail below. However, the present invention is not limited to the following embodiments and can be modified and applied as appropriate without altering the gist of the invention.

[0039] (First Embodiment) A method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention, which is an example of a method for manufacturing a shielded printed circuit board according to the present invention, will be described with reference to the drawings.

[0040] Figure 1 is a schematic process diagram showing an example of the printed circuit board preparation step in the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention. Figure 2 is a schematic process diagram showing an example of the first electromagnetic wave shielding film preparation step in the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention. Figure 3 is a schematic process diagram showing an example of the second electromagnetic wave shielding film preparation step in the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention. Figure 4 is a schematic process diagram showing an example of the first electromagnetic wave shielding film placement step in the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention. Figure 5 is a schematic process diagram showing an example of the second electromagnetic wave shielding film placement step in the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention. Figure 6 is a schematic process diagram showing an example of the overlapping process in the manufacturing method of a shielded printed circuit board according to the first embodiment of the present invention. Figure 7 is a schematic process diagram showing an example of a preliminary pressing step in the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention. Figure 8 is a schematic process diagram showing an example of the protective film peeling step in the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention. Figures 9A and 9B are schematic process diagrams illustrating an example of the main pressing step in the manufacturing method of a shielded printed circuit board according to the first embodiment of the present invention.

[0041] <Preparation process for printed circuit boards> In this process, as shown in Figure 1, a printed circuit board 10 is prepared, which includes a base film 11, a printed circuit 12 formed on the base film 11, and a coverlay 13 that covers the printed circuit 12. In the printed circuit board 10, the printed circuit 12 includes a ground circuit 12a. Furthermore, the coverlay 13 has an opening 13a that exposes the ground circuit 12a.

[0042] (Base film and coverlay) The materials of the base film 11 and the coverlay 13 are not particularly limited, but it is preferable that they be made of engineering plastics. Examples of such engineering plastics include polyimide resins, polyamide-imide resins, polyamide resins, polyetherimide resins, polyesterimide resins, polyethernitrile resins, polyethersulfone resins, polyphenylene sulfide resins, polyethylene terephthalate resins, polypropylene resins, crosslinked polyethylene resins, polyester resins, polybenzimidazole resins, polyimide resins, polyimideamide resins, polyetherimide resins, and polyphenylene sulfide resins. Furthermore, 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 11 is preferably 10 to 40 μm, and the thickness of the coverlay 13 is preferably 10 to 30 μm.

[0043] The size of the opening 13a is not particularly limited, but is between 0.03 and 320 mm. 2 It is preferable that the size be 0.1-2.0 mm. 2 It is more desirable that this be the case. Furthermore, the shape of the opening 13a is not particularly limited and may be circular, elliptical, square, triangular, etc.

[0044] (Printed circuit board) The materials for the printed circuit 12 and the ground circuit 12a are not particularly limited, and known conductive materials can be used, such as copper foil or a cured conductive paste.

[0045] <First Electromagnetic Shielding Film Preparation Process> In this process, as shown in Figure 2, a first electromagnetic wave shielding film 20 is prepared by sequentially laminating a first protective film 21, a first insulating layer 22, a first shielding layer 24, and a first adhesive layer 23. The first electromagnetic shielding film 20 has a width wider than the width of the printed circuit board 10. The first adhesive layer 23 contains a resin for the first adhesive layer and conductive particles for the first adhesive layer, and is conductive.

[0046] (First protective film) The material of the first protective film 21 is not particularly limited, but may be plastic sheets such as polyethylene terephthalate, polyethylene naphthalate, polyvinyl fluoride, polyvinylidene fluoride, rigid polyvinyl chloride, polyvinylidene chloride, nylon, polyimide, polystyrene, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polycarbonate, polyacrylonitrile, polybutene, flexible polyvinyl chloride, polyvinylidene fluoride, polyethylene, polypropylene, polyurethane, ethylene vinyl acetate copolymer, polyvinyl acetate, etc., as well as paper such as glassine paper, fine paper, kraft paper, coated paper, etc., various nonwoven fabrics, synthetic paper, metal layers, or composite films combining these. The first protective film 21 may be a film that has been treated with a release agent on one or both sides. Methods for the release agent include applying a release agent to one or both sides of the film, or physically matting the film.

[0047] Furthermore, the thickness of the first protective film 21 is preferably 10 to 150 μm, more preferably 20 to 100 μm, and even more preferably 40 to 60 μm. If the thickness of the first protective film is less than 10 μm, the first protective film becomes more prone to tearing, making it difficult to peel off the first protective film in the protective film peeling process described later. If the thickness of the first protective film exceeds 150 μm, it becomes difficult to handle.

[0048] (First insulating layer) The material of the first insulating layer 22 is not particularly limited, but it is preferably at least one selected from the group consisting of polyimide resins, polyamideimide resins, polyamide resins, polyetherimide resins, polyesterimide resins, polyethernitrile resins, polyethersulfone resins, polyphenylene sulfide resins, polyethylene terephthalate resins, polypropylene resins, crosslinked polyethylene resins, polyester resins, polybenzimidazole resins, polyimide resins, polyimideamide resins, polyetherimide resins, and polyphenylene sulfide resins, and more preferably a polyimide resin.

[0049] Furthermore, the first insulating layer 22 may be composed of a single material or of two or more materials.

[0050] The first insulating layer 22 may optionally contain curing accelerators, tackifiers, antioxidants, pigments, dyes, plasticizers, UV absorbers, defoamers, leveling agents, fillers, flame retardants, viscosity modifiers, anti-blocking agents, etc.

[0051] The thickness of the first insulating layer 22 is not particularly limited and can be set as appropriate as needed, but it is preferably 1 to 15 μm, and more preferably 3 to 10 μm. If the thickness of the first insulating layer is less than 1 μm, the shielding film cannot follow the steps of the printed circuit board, making it difficult to remove air from the gaps during the subsequent pressing process. Also, because it is too thin, it becomes difficult to adequately protect the first shielding layer and the first adhesive layer. If the thickness of the first insulating layer exceeds 15 μm, the pressure tends to be dispersed more easily during the subsequent pressing process, making it difficult to remove air from the gaps. Furthermore, because it is too thick, the first insulating layer becomes less flexible and more prone to damage. Therefore, it becomes difficult to apply to components that require high bending resistance.

[0052] (First Shield Layer) The first shielding layer 24 is not particularly limited in its material as long as it can shield electromagnetic waves. For example, it may be made of a metal or a conductive resin composition for the first shielding layer.

[0053] When the first shield layer 24 is made of metal, examples of metals include gold, silver, copper, aluminum, nickel, tin, palladium, chromium, titanium, and zinc. Among these, copper is preferable. Copper is a suitable material for the first shield layer from the viewpoint of conductivity and cost-effectiveness.

[0054] The first shield layer 24 may be made of an alloy of the above-mentioned metals. Furthermore, the first shield layer 24 may be a metal foil, or a metal film formed by methods such as sputtering, electroless plating, or electroplating.

[0055] When the first shield layer 24 is made of metal, the thickness of the first shield layer is preferably 0.01 μm or more, more preferably 0.1 μm or more, and even more preferably 0.5 μm or more, from the viewpoint of ensuring sufficient shielding performance. Furthermore, from the viewpoint of thinning, it is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less.

[0056] If the first shield layer 24 is made of a conductive resin composition for the first shield layer, the first shield layer 24 may be composed of conductive particles and resin.

[0057] The conductive particles are not particularly limited, but may include metal nanoparticles, carbon nanotubes, carbon fibers, metal fibers, etc.

[0058] When the conductive particles are metal nanoparticles, the metal nanoparticles are not particularly limited, but may include silver powder, copper powder, nickel powder, solder powder, aluminum powder, silver-plated copper powder, polymer nanoparticles, glass beads, etc., coated with metal. Of these options, from an economic standpoint, copper powder or silver-coated copper powder, which are readily available at low cost, are preferable.

[0059] The average particle diameter of the conductive particles is not particularly limited, but is preferably between 0.5 and 15.0 μm. If the average particle diameter of the conductive particles is 0.5 μm or more, the conductivity of the conductive resin composition for the first shield layer will be good. If the average particle diameter of the conductive particles is 15.0 μm or less, the first shield layer 24 made of the conductive resin composition for the first shield layer can be made thinner.

[0060] The shape of the conductive particles is not particularly limited, but can be appropriately selected from spherical, flattened, flake-shaped, dendritic, rod-shaped, fibrous, and the like.

[0061] The amount of conductive particles included is not particularly limited, but it is preferably 15-90% by weight, and more preferably 15-60% by weight.

[0062] The resins are not particularly limited, but examples include thermoplastic resin compositions such as styrene-based resin compositions, vinyl acetate-based resin compositions, polyester-based resin compositions, polyethylene-based resin compositions, polypropylene-based resin compositions, imide-based resin compositions, amide-based resin compositions, and acrylic-based resin compositions, as well as thermosetting resin compositions such as phenol-based resin compositions, epoxy-based resin compositions, urethane-based resin compositions, melamine-based resin compositions, and alkyd-based resin compositions.

[0063] (First adhesive layer) The first adhesive layer 23 consists of a resin for the first adhesive layer and conductive particles for the first adhesive layer.

[0064] The resin for the first adhesive layer may be a thermosetting resin or a thermoplastic resin. Examples of thermosetting resins include phenolic resins, epoxy resins, urethane resins, melamine resins, polyamide resins, and alkyd resins. Examples of thermoplastic resins include styrene resins, vinyl acetate resins, polyester resins, polyethylene resins, polypropylene resins, imide resins, and acrylic resins. Furthermore, it is more desirable that the epoxy resin be an amide-modified epoxy resin. These resins are suitable as resins for constituting the first adhesive layer 23.

[0065] The conductive particles for the first adhesive layer are not particularly limited, but may include metal nanoparticles, carbon nanotubes, carbon fibers, metal fibers, etc.

[0066] When the conductive particles for the first adhesive layer are metal nanoparticles, the metal nanoparticles are not particularly limited, but may include silver powder, copper powder, nickel powder, solder powder, aluminum powder, silver-coated copper powder (copper powder plated with silver), polymer nanoparticles, glass beads, etc., coated with metal. Of these options, from an economic standpoint, copper powder or silver-coated copper powder, which are readily available at low cost, are preferable.

[0067] The average particle size of the conductive particles for the first adhesive layer is not particularly limited, but is preferably between 0.5 and 15.0 μm. If the average particle size of the conductive particles for the first adhesive layer is 0.5 μm or larger, the conductivity of the first adhesive layer will be good. If the average particle size of the conductive particles is 15.0 μm or smaller, the first adhesive layer can be made thinner.

[0068] The shape of the conductive particles for the first adhesive layer is not particularly limited, but can be appropriately selected from spherical, flattened, flake-shaped, dendritic, rod-shaped, fibrous, and the like.

[0069] The weight percentage of conductive particles for the first adhesive layer in the first adhesive layer is preferably 3 to 90% by weight, and more preferably 39 to 90% by weight. If the weight percentage of conductive particles in the first adhesive layer is less than 3% by weight, the shielding effect will be less likely to be sufficient. When the weight percentage of conductive particles for the first adhesive layer exceeds 90% by weight, the adhesion between the first adhesive layer and the second adhesive layer tends to decrease. Furthermore, if the weight percentage of conductive particles for the first adhesive layer is 39-90% by weight, the first adhesive layer will have isotropic conductivity.

[0070] The thickness of the first adhesive layer 23 is not particularly limited, but is preferably 1 to 50 μm, and more preferably 3 to 30 μm. If the thickness of the first adhesive layer is less than 1 μm, the amount of resin constituting the first adhesive layer is small, making it difficult to obtain sufficient adhesive performance. In addition, the first adhesive layer becomes more prone to damage. When the thickness of the first adhesive layer exceeds 50 μm, the entire structure becomes thicker, loses flexibility, and the area where the first and second extension ends face each other becomes prone to damage.

[0071] The first adhesive layer 23 is preferably an isotropic conductive resin composition. If the first adhesive layer 23 is an isotropically conductive resin composition, electromagnetic noise radiated from the printed circuit board can be effectively blocked.

[0072] As will be described later, the first adhesive layer 23 will be electrically connected to the ground circuit 12a. Furthermore, in the first electromagnetic wave shielding film 20, an anchor coat layer may be formed between the first insulating layer 22 and the first shielding layer 24. Materials for the anchor coat layer include urethane resin, acrylic resin, core-shell type composite resin with urethane resin as the shell and acrylic resin as the core, epoxy resin, imide resin, amide resin, melamine resin, phenol resin, urea-formaldehyde resin, blocked isocyanate obtained by reacting polyisocyanate with a blocking agent such as phenol, polyvinyl alcohol, and polyvinylpyrrolidone.

[0073] <Second electromagnetic wave shielding film preparation process> In this process, as shown in Figure 3, a second electromagnetic wave shielding film 30 is prepared by sequentially laminating a second protective film 31, a second insulating layer 32, a second shielding layer 34, and a second adhesive layer 33. The second electromagnetic shielding film 30 has a width wider than the width of the printed circuit board 10. The second adhesive layer 33 contains a resin for the second adhesive layer and conductive particles for the second adhesive layer, and is conductive. In the second electromagnetic wave shielding film 30, the desired configuration of the second protective film 31, the second insulating layer 32, the second shielding layer 34, and the second adhesive layer 33 (resin for the second adhesive layer and conductive particles for the second adhesive layer) is the same as the desired configuration of the first protective film 21, the first insulating layer 22, the first shielding layer 24, and the first adhesive layer 23 (resin for the first adhesive layer and conductive particles for the first adhesive layer) in the first electromagnetic wave shielding film 20.

[0074] <First electromagnetic wave shielding film placement process> In this process, as shown in Figure 4, the first electromagnetic shielding film 20 is placed on the printed circuit board 10 such that the first adhesive layer 23 is in contact with the surface of the printed circuit board 10 on the coverlay 13 side. In this case, both ends of the first adhesive layer 23 are positioned outside the edges of the printed circuit board 10 to form the first extended end portion 23a.

[0075] <Second electromagnetic wave shielding film placement process> In this process, as shown in Figure 5, the second electromagnetic shielding film 30 is placed on the printed circuit board 10 such that the second adhesive layer 33 is in contact with the base film 11 side of the printed circuit board 10. In this case, both ends of the second adhesive layer 33 are positioned outside the edges of the printed circuit board 10 to form the second extended end portion 33a.

[0076] <Overlay process> In this process, as shown in Figure 6, the first adhesive layer 23 and the second adhesive layer 33 are overlapped so that a gap 40 is created between the first extended end 23a of the first adhesive layer 23 located at both ends of the first electromagnetic wave shielding film 20 and the second extended end 33a of the second adhesive layer 33 located at both ends of the second electromagnetic wave shielding film 30, thereby producing a pre-press shielded printed circuit board 51.

[0077] In the method for manufacturing a shielded printed circuit board of the present invention, the first adhesive layer 23 and the second adhesive layer 33 are cured in two stages by performing a preliminary pressing step and a main pressing step, as described later. Even if a gap 40 is created between the first extension 23a and the second extension 33a during the overlapping process, these steps allow air to be removed from the gap 40, and the first adhesive layer 23 and the second adhesive layer 33 can be sufficiently bonded together. Furthermore, if one attempts to overlap the first and second adhesive layers in a way that prevents such gaps from forming during the overlapping process, it becomes necessary to apply high pressure and time during the overlapping process, resulting in poor production efficiency.

[0078] <Preliminary pressing process> In this process, as shown in Figure 7, the shield printed circuit board 51 before temporary pressing is pressurized and heated from the first protective film 21 side and the second protective film 31 side so that the first adhesive layer 23 and the second adhesive layer 33 do not completely harden, and the shield printed circuit board 52 after temporary pressing is manufactured.

[0079] In the preliminary pressing process, the first adhesive layer 23 and the second adhesive layer 33 are pressurized and heated so that they do not completely harden. In other words, in the preliminary pressing process, the first adhesive layer 23 and the second adhesive layer 33 are kept in a semi-hardened state. By allowing the first adhesive layer 23 and the second adhesive layer 33 to partially harden, the positions of the first electromagnetic wave shielding film 20 and the second electromagnetic wave shielding film 30 can be fixed. Therefore, in the protective film peeling process described later, the first protective film 21 and the second protective film 31 become easier to peel off. Furthermore, since the first protective film 21 and the second protective film 31 are in place when pressurized and heated, the pressure can be applied evenly. Furthermore, in the pressing process described later, it becomes easier to remove air from the gap 40 between the first adhesive layer 23 and the second adhesive layer 33.

[0080] The following are examples of pressurizing and heating conditions in the preliminary pressing process. In other words, the pressure is preferably 0.2 to 0.7 MPa, and more preferably 0.3 to 0.6 MPa. The temperature should preferably be between 100 and 150°C, and more preferably between 110 and 130°C. The duration should ideally be between 1 and 10 seconds, and more ideally between 3 and 7 seconds. When the pressurizing and heating conditions in the temporary pressing process are within the above range, the first adhesive layer 23 and the second adhesive layer 33 can be suitably brought to a semi-cured state.

[0081] <Protective film removal process> In this process, as shown in Figure 8, the first protective film 21 and the second protective film 31 are peeled off from the shielded printed circuit board 52 after preliminary pressing to produce the shielded printed circuit board 53 before the main pressing.

[0082] <Main Pressing Process> In this process, as shown in Figure 9A, the pre-press shield printed circuit board 53 is pressurized and heated from the first insulating layer 22 side and the second insulating layer 32 side to cure the first adhesive layer 23 and the second adhesive layer 33. At this time, air escapes from the gap 40 between the first adhesive layer 23 and the second adhesive layer 33, and the first adhesive layer 23 fills the opening 13a and comes into contact with the ground circuit 12a.

[0083] If the pressing process is performed without peeling off the first protective film 21 and the second protective film 31 during the protective film peeling process, the pressure will be absorbed, making it difficult to remove air from the gap 40 between the first adhesive layer 23 and the second adhesive layer 33. However, in the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention, the pressing process is performed after peeling off the first protective film 21 and the second protective film 31. As a result, the pressure during the pressing process is not easily absorbed. Therefore, even if there is a gap 40 in part between the first adhesive layer 23 and the second adhesive layer 33, the air can be sufficiently removed from that gap 40 by performing the pressing process. As a result, the printed circuit board 10, the first adhesive layer 23, and the second adhesive layer 33 can be sufficiently adhered to each other.

[0084] The following are examples of pressurizing and heating conditions for this pressing process. In other words, the pressure is preferably 1-5 MPa, and more preferably 2-4 MPa. The temperature is preferably between 150°C and 190°C, more preferably between 160°C and 190°C, and even more preferably between 165°C and 180°C. The duration should preferably be between 60 seconds and 2 hours, more preferably between 120 seconds and 1 hour, and even more preferably between 180 seconds and 0.5 hours. When the pressurizing and heating conditions in this pressing process are within the above range, air can be sufficiently removed from the gap 40 between the first adhesive layer 23 and the second adhesive layer 33, and the first adhesive layer 23 and the second adhesive layer 33 can be sufficiently cured.

[0085] In the manufacturing method of a shielded printed circuit board according to the first embodiment of the present invention, in the first electromagnetic wave shielding film preparation step and the second electromagnetic wave shielding film preparation step, it is desirable to adjust the thickness of the first adhesive layer and the second adhesive layer so that the sum of the thickness of the first adhesive layer at the first extended end and the thickness of the second adhesive layer at the second extended end after the pressing step is 1 / 30 to 1 times the thickness of the printed circuit board, more preferably to adjust the thickness of the first adhesive layer and the second adhesive layer so that it is 1 / 20 to 9 / 10 times the thickness, and even more preferably to adjust the thickness of the first adhesive layer and the second adhesive layer so that it is 1 / 15 to 9 / 10 times the thickness. By adjusting the thickness of the first adhesive layer and / or the second adhesive layer within the above range, it becomes easier to ensure sufficient adhesion between the first adhesive layer and the second adhesive layer. If, after this pressing process, the sum of the thickness of the first adhesive layer at the first extension end and the thickness of the second adhesive layer at the second extension end is less than 1 / 30th the thickness of the printed circuit board, a gap is likely to form between the first adhesive layer and the second adhesive layer. If, after this pressing process, the sum of the thickness of the first adhesive layer at the first extension end and the thickness of the second adhesive layer at the second extension end exceeds 1 times the thickness of the printed circuit board, the shielded printed circuit board becomes thicker, which is undesirable from the viewpoint of making the shielded printed circuit board thinner.

[0086] Through the above process, a shielded printed circuit board 54 can be manufactured as shown in Figure 9B. The shielded printed circuit board 54 shown in Figure 9B consists of a printed circuit board 10, a first electromagnetic wave shielding section 20a placed on top of the printed circuit board 10, and a second electromagnetic wave shielding section 30a placed below the printed circuit board 10. The first electromagnetic wave shielding portion 20a is formed by the hardening of the adhesive layer of the first electromagnetic wave shielding film, and the second electromagnetic wave shielding portion 30a is formed by the hardening of the adhesive layer of the second electromagnetic wave shielding film.

[0087] The printed circuit board 10 comprises a base film 11, a printed circuit 12 including a ground circuit 12a formed on the base film 11, and a coverlay 13 covering the printed circuit 12, the coverlay 13 having an opening 13a that exposes the ground circuit 12a.

[0088] The first electromagnetic wave shielding section 20a is formed by sequentially laminating a first insulating layer 22, a first shielding layer 24, and a first adhesive layer 23. The first adhesive layer 23 is positioned in contact with the coverlay 13. Furthermore, the first adhesive layer 23 fills the opening 13a of the coverlay 13, and the first adhesive layer 23 is in contact with the ground circuit 12a.

[0089] The second electromagnetic wave shielding section 30a is formed by sequentially laminating a second insulating layer 32, a second shielding layer 34, and a second adhesive layer 33. The second adhesive layer 33 is positioned so as to be in contact with the base film 11.

[0090] Furthermore, in the shielded printed circuit board 54, the width of the first electromagnetic wave shielding portion 20a is wider than the width of the printed circuit board 10, and both ends of the first adhesive layer 23 of the first electromagnetic wave shielding portion 20a are located further out than both ends of the printed circuit board 10, forming the first extended end portion 23a. Furthermore, in the shielded printed circuit board 54, the width of the second electromagnetic wave shielding portion 30a is wider than the width of the printed circuit board 10, and both ends of the second electromagnetic wave shielding portion 30a are located further out than both ends of the printed circuit board 10, forming the second extended end portion 33a. Furthermore, the first adhesive layer 23 located at the first extension end 23a and the second adhesive layer 33 located at the second extension end 33a are bonded together. In shielded printed circuit boards, the first adhesive layer located at the first extension end and the second adhesive layer located at the second extension end are so integrated that their boundaries are indistinguishable. However, in Figure 9B, the first adhesive layer 23 located at the first extension end 23a and the second adhesive layer 33 located at the second extension end 33a are shown as separate regions for convenience.

[0091] (Second Embodiment) Next, a method for manufacturing a shielded printed circuit board according to a second embodiment of the present invention, which is an example of the method for manufacturing a shielded printed circuit board according to the present invention, will be described.

[0092] Figure 10 is a schematic process diagram showing an example of the printed circuit board preparation step in the method for manufacturing a shielded printed circuit board according to the second embodiment of the present invention. Figure 11 is a schematic process diagram showing an example of the first electromagnetic wave shielding film preparation step in the method for manufacturing a shielded printed circuit board according to the second embodiment of the present invention. Figure 12 is a schematic process diagram showing an example of the second electromagnetic wave shielding film preparation step in the method for manufacturing a shielded printed circuit board according to the second embodiment of the present invention. Figure 13 is a schematic process diagram showing an example of the first electromagnetic wave shielding film placement step in the method for manufacturing a shielded printed circuit board according to the second embodiment of the present invention. Figure 14 is a schematic process diagram showing an example of the second electromagnetic wave shielding film placement step in the method for manufacturing a shielded printed circuit board according to the second embodiment of the present invention. Figure 15 is a schematic process diagram showing an example of the overlapping process in the manufacturing method of a shielded printed circuit board according to the second embodiment of the present invention. Figure 16 is a schematic process diagram showing an example of a preliminary pressing step in a method for manufacturing a shielded printed circuit board according to a second embodiment of the present invention. Figure 17 is a schematic process diagram showing an example of the protective film peeling step in the method for manufacturing a shielded printed circuit board according to the second embodiment of the present invention. Figures 18A and 18B are schematic process diagrams illustrating an example of the main pressing step in the method for manufacturing a shielded printed circuit board according to the second embodiment of the present invention.

[0093] <Preparation process for printed circuit boards> In this process, as shown in Figure 10, a printed circuit board 110 is prepared, which includes a base film 111, a printed circuit 112 formed on the base film 111, and a coverlay 113 that covers the printed circuit 112. In the printed circuit board 110, the printed circuit 112 includes a ground circuit 112a. Furthermore, the coverlay 113 has an opening 13a that exposes the ground circuit 112a.

[0094] The preferred materials for the base film 111, printed circuit 112, and coverlay 113 of the printed circuit board 110 prepared in this process are the same as the preferred materials for the base film 11, printed circuit 12, and coverlay 13 in the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention.

[0095] <First Electromagnetic Shielding Film Preparation Process> In this process, as shown in Figure 11, a first electromagnetic wave shielding film 120 is prepared by sequentially laminating a first protective film 121, a first insulating layer 122, and a first adhesive layer 123. Furthermore, the first electromagnetic wave shielding film 120 has a width wider than the width of the printed circuit board 110.

[0096] The preferred materials for the first protective film 121 and the first insulating layer 122 are the same as the preferred materials for the first protective film 21 and the first insulating layer 22 in the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention.

[0097] Furthermore, the first adhesive layer 123 contains a resin for the first adhesive layer and conductive particles for the first adhesive layer, and has conductive and electromagnetic shielding functions. In other words, the first adhesive layer 123 has both the function of an adhesive and the function of an electromagnetic shield.

[0098] The resin for the first adhesive layer may be a thermosetting resin or a thermoplastic resin. Examples of thermosetting resins include phenolic resins, epoxy resins, urethane resins, melamine resins, polyamide resins, and alkyd resins. Examples of thermoplastic resins include styrene resins, vinyl acetate resins, polyester resins, polyethylene resins, polypropylene resins, imide resins, and acrylic resins. Furthermore, it is more desirable that the epoxy resin be an amide-modified epoxy resin. These resins are suitable as resins for constituting the first adhesive layer 123.

[0099] The conductive particles for the first adhesive layer are not particularly limited, but may include metal nanoparticles, carbon nanotubes, carbon fibers, metal fibers, etc.

[0100] When the conductive particles for the first adhesive layer are metal nanoparticles, the metal nanoparticles are not particularly limited, but may include silver powder, copper powder, nickel powder, solder powder, aluminum powder, silver-coated copper powder (copper powder plated with silver), polymer nanoparticles, glass beads, etc., coated with metal. Of these options, from an economic standpoint, copper powder or silver-coated copper powder, which are readily available at low cost, are preferable.

[0101] The average particle size of the conductive particles for the first adhesive layer is not particularly limited, but is preferably between 0.5 and 15.0 μm. If the average particle size of the conductive particles for the first adhesive layer is 0.5 μm or larger, the conductivity of the first adhesive layer will be good. If the average particle size of the conductive particles is 15.0 μm or smaller, the first adhesive layer can be made thinner.

[0102] The shape of the conductive particles for the first adhesive layer is not particularly limited, but can be appropriately selected from spherical, flattened, flake-shaped, dendritic, rod-shaped, fibrous, and the like.

[0103] The weight percentage of conductive particles for the first adhesive layer in the first adhesive layer is preferably 3 to 90% by weight, and more preferably 39 to 90% by weight. If the weight percentage of conductive particles in the first adhesive layer is less than 3% by weight, the shielding effect will be less likely to be sufficient. When the weight percentage of conductive particles for the first adhesive layer exceeds 90% by weight, the adhesion between the first adhesive layer and the second adhesive layer tends to decrease. Furthermore, if the weight percentage of conductive particles for the first adhesive layer is 39-90% by weight, the first adhesive layer will have isotropic conductivity.

[0104] The thickness of the first adhesive layer 123 is not particularly limited, but is preferably 1 to 50 μm, and more preferably 3 to 30 μm. If the thickness of the first adhesive layer is less than 1 μm, the amount of resin constituting the first adhesive layer is small, making it difficult to obtain sufficient adhesive performance. Furthermore, it becomes more prone to breakage. When the thickness of the first adhesive layer exceeds 50 μm, the overall thickness increases, and flexibility is easily lost.

[0105] <Second electromagnetic wave shielding film preparation process> In this process, as shown in Figure 12, a second electromagnetic wave shielding film 130 is prepared by sequentially laminating a second protective film 131, a second insulating layer 132, and a second adhesive layer 133. Furthermore, the second electromagnetic wave shielding film 130 has a width wider than the width of the printed circuit board 110.

[0106] The preferred materials for the second protective film 131 and the second insulating layer 132 are the same as the preferred materials for the second protective film 31 and the second insulating layer 32 in the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention.

[0107] Furthermore, the second adhesive layer 133 contains a resin for the second adhesive layer and conductive particles for the second adhesive layer, and has both conductivity and electromagnetic shielding functions. In other words, the second adhesive layer 133 has both the function of an adhesive and the function of electromagnetic shielding. Furthermore, the preferred materials for the resin and conductive particles for the second adhesive layer constituting the second adhesive layer 133 are the same as the preferred materials for the resin and conductive particles for the first adhesive layer constituting the first adhesive layer 123.

[0108] <First electromagnetic wave shielding film placement process> In this process, as shown in Figure 13, the first electromagnetic shielding film 120 is placed on the printed circuit board 110 such that the first adhesive layer 123 is in contact with the surface of the printed circuit board 110 on the coverlay 113 side. In this case, both ends of the first adhesive layer 123 are positioned outside the edges of the printed circuit board 110 to form the first extended end portion 123a.

[0109] <Second electromagnetic wave shielding film placement process> In this process, as shown in Figure 14, the second electromagnetic shielding film 130 is placed on the printed circuit board 110 such that the second adhesive layer 133 is in contact with the base film 111 side of the printed circuit board 110. In this case, both ends of the second adhesive layer 133 are positioned outside the edges of the printed circuit board 110 to form the second extended end portion 133a.

[0110] <Overlay process> In this process, as shown in Figure 15, the first adhesive layer 123 and the second adhesive layer 133 are overlapped such that a gap 140 is created between the first extended end 123a of the first adhesive layer 123 located at both ends of the first electromagnetic wave shielding film 120 and the second extended end 133a of the second adhesive layer 133 located at both ends of the second electromagnetic wave shielding film 130, thereby producing a pre-press shielded printed circuit board 151.

[0111] In the method for manufacturing a shielded printed circuit board of the present invention, the first adhesive layer 123 and the second adhesive layer 133 are cured in two stages by performing a preliminary pressing step and a main pressing step, as described later. Even if a gap 140 is created between the first extension end 123a and the second extension end 133a during the overlapping process, these steps allow air to be removed from the gap 140, and the first adhesive layer 123 and the second adhesive layer 133 to be sufficiently bonded together. Furthermore, if one attempts to overlap the first and second adhesive layers in a way that prevents such gaps from forming during the overlapping process, it becomes necessary to apply high pressure and time during the overlapping process, resulting in poor production efficiency.

[0112] <Preliminary pressing process> In this process, as shown in Figure 16, the shield printed circuit board 151 before temporary pressing is pressurized and heated from the first protective film 121 side and the second protective film 131 side so that the first adhesive layer 123 and the second adhesive layer 133 do not completely harden, and the shield printed circuit board 152 after temporary pressing is manufactured.

[0113] In the preliminary pressing process, the first adhesive layer 123 and the second adhesive layer 133 are pressurized and heated so that they do not completely harden. In other words, in the preliminary pressing process, the first adhesive layer 123 and the second adhesive layer 133 are left in a semi-hardened state. By allowing the first adhesive layer 123 and the second adhesive layer 133 to partially harden, the positions of the first electromagnetic wave shielding film 120 and the second electromagnetic wave shielding film 130 can be fixed. Therefore, in the protective film peeling process described later, the first protective film 121 and the second protective film 131 become easier to peel off. Furthermore, since the first protective film 121 and the second protective film 131 are in place when pressurized and heated, the pressure can be applied evenly. Furthermore, in the pressing process described later, it becomes easier to remove air from the gap 140 between the first adhesive layer 123 and the second adhesive layer 133.

[0114] The desirable pressurizing and heating conditions in the temporary pressing process are the same as the desirable pressurizing and heating conditions in the temporary pressing process of the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention.

[0115] <Protective film removal process> In this process, as shown in Figure 17, the first protective film 121 and the second protective film 131 are peeled off from the shielded printed circuit board 152 after pre-pressing to produce the shielded printed circuit board 153 before the main press.

[0116] <Main Pressing Process> In this process, as shown in Figure 18A, the pre-press shield printed circuit board 153 is pressurized and heated from the first insulating layer 122 side and the second insulating layer 132 side to cure the first adhesive layer 123 and the second adhesive layer 133. At this time, air escapes from the gap 40 between the first adhesive layer 123 and the second adhesive layer 133, and the first adhesive layer 123 fills the opening 113a and comes into contact with the ground circuit 112a.

[0117] If the pressing process is performed without peeling off the first protective film 121 and the second protective film 131 during the protective film peeling process, the pressure will be absorbed, making it difficult to remove air from the gap 140 between the first adhesive layer 123 and the second adhesive layer 133. However, in the method for manufacturing a shielded printed circuit board according to the second embodiment of the present invention, the pressing process is performed after peeling off the first protective film 121 and the second protective film 131. Therefore, the pressure during this pressing process is less likely to be absorbed. Consequently, even if there is a gap 140 in part between the first adhesive layer 123 and the second adhesive layer 133, the air can be sufficiently removed from that gap 140 by performing this pressing process. As a result, the printed circuit board 110, the first adhesive layer 123, and the second adhesive layer 133 can be sufficiently adhered to each other.

[0118] The desirable pressurizing and heating conditions in this pressing process are the same as the desirable pressurizing and heating conditions in the preliminary pressing process of the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention.

[0119] Furthermore, in the manufacturing method of the shielded printed circuit board according to the second embodiment of the present invention, in the first electromagnetic wave shielding film preparation step and the second electromagnetic wave shielding film preparation step, it is desirable to adjust the thickness of the first adhesive layer and the second adhesive layer so that the sum of the thickness of the first adhesive layer at the first extended end and the thickness of the second adhesive layer at the second extended end after the pressing step is 1 / 30 to 1 times the thickness of the printed circuit board, more preferably to adjust the thickness of the first adhesive layer and the second adhesive layer so that it is 1 / 20 to 9 / 10 times the thickness, and even more preferably to adjust the thickness of the first adhesive layer and the second adhesive layer so that it is 1 / 15 to 9 / 10 times the thickness. By adjusting the thickness of the first adhesive layer and / or the second adhesive layer within the above range, it becomes easier to ensure sufficient adhesion between the first adhesive layer and the second adhesive layer. If, after this pressing process, the sum of the thickness of the first adhesive layer at the first extension end and the thickness of the second adhesive layer at the second extension end is less than 1 / 30th the thickness of the printed circuit board, a gap is likely to form between the first adhesive layer and the second adhesive layer. If, after this pressing process, the sum of the thickness of the first adhesive layer at the first extension end and the thickness of the second adhesive layer at the second extension end exceeds 1x the thickness of the printed circuit board, the shielded printed circuit board becomes too thick, limiting its applications.

[0120] After the above steps, a shielded printed circuit board 154 can be manufactured as shown in Figure 18B. The shielded printed circuit board 154 shown in Figure 18B consists of a printed circuit board 110, a first electromagnetic wave shielding section 120a positioned on top of the printed circuit board 110, and a second electromagnetic wave shielding section 130a positioned below the printed circuit board 110. The first electromagnetic wave shielding portion 120a is a portion formed by the hardening of the adhesive layer of the first electromagnetic wave shielding film, and the second electromagnetic wave shielding portion 130a is a portion formed by the hardening of the adhesive layer of the second electromagnetic wave shielding film.

[0121] The printed circuit board 110 comprises a base film 111, a printed circuit 112 including a ground circuit 112a formed on the base film 111, and a coverlay 113 covering the printed circuit 112, the coverlay 113 having an opening 113a that exposes the ground circuit 112a.

[0122] The first electromagnetic wave shielding section 120a is formed by sequentially laminating a first insulating layer 122 and a first adhesive layer 123. The first adhesive layer 123 is positioned in contact with the coverlay 113. Furthermore, the first adhesive layer 123 fills the opening 113a of the coverlay 113, and the first adhesive layer 123 is in contact with the ground circuit 112a.

[0123] The second electromagnetic wave shielding section 130a is formed by sequentially laminating a second insulating layer 132 and a second adhesive layer 133. The second adhesive layer 133 is positioned in contact with the base film 111.

[0124] Furthermore, in the shielded printed circuit board 154, the width of the first electromagnetic wave shielding portion 120a is wider than the width of the printed circuit board 110, and both ends of the first adhesive layer 123 of the first electromagnetic wave shielding portion 120a are located further out than both ends of the printed circuit board 110, forming the first extended end portion 123a. Furthermore, in the shielded printed circuit board 154, the width of the second electromagnetic wave shielding portion 130a is wider than the width of the printed circuit board 110, and both ends of the second electromagnetic wave shielding portion 130a are located further out than both ends of the printed circuit board 110, forming the second extended end portion 133a. Furthermore, the first adhesive layer 123 located at the first extension end 123a and the second adhesive layer 133 located at the second extension end 133a are bonded together. In shielded printed circuit boards, the first adhesive layer located at the first extension end and the second adhesive layer located at the second extension end are so integrated that their boundaries are indistinguishable. However, in Figure 18B, the first adhesive layer 123 located at the first extension end 123a and the second adhesive layer 133 located at the second extension end 133a are shown as separate regions for convenience.

[0125] (Third embodiment) Next, a method for manufacturing a shielded printed circuit board according to a third embodiment of the present invention, which is an example of the method for manufacturing a shielded printed circuit board according to the present invention, will be described.

[0126] Figure 19 is a schematic process diagram showing an example of the printed circuit board preparation step in the method for manufacturing a shielded printed circuit board according to the third embodiment of the present invention. Figure 20 is a schematic process diagram showing an example of the first electromagnetic wave shielding film preparation step in the method for manufacturing a shielded printed circuit board according to the third embodiment of the present invention. Figure 21 is a schematic process diagram showing an example of the second electromagnetic wave shielding film preparation step in the method for manufacturing a shielded printed circuit board according to the third embodiment of the present invention. Figure 22 is a schematic process diagram showing an example of the first electromagnetic wave shielding film placement step in the method for manufacturing a shielded printed circuit board according to the third embodiment of the present invention. Figure 23 is a schematic process diagram showing an example of the second electromagnetic wave shielding film placement step in the method for manufacturing a shielded printed circuit board according to the third embodiment of the present invention. Figure 24 is a schematic process diagram showing an example of the overlapping process in the manufacturing method of a shielded printed circuit board according to the third embodiment of the present invention. Figure 25 is a schematic process diagram showing an example of a preliminary pressing step in a method for manufacturing a shielded printed circuit board according to a third embodiment of the present invention. Figure 26 is a schematic process diagram showing an example of the protective film peeling step in the method for manufacturing a shielded printed circuit board according to the third embodiment of the present invention. Figures 27A and 27B are schematic process diagrams illustrating an example of the main pressing step in the manufacturing method of a shielded printed circuit board according to the third embodiment of the present invention.

[0127] <Preparation process for printed circuit boards> In this process, as shown in Figure 19, a printed circuit board 210 is prepared, which consists of a base film 211, a printed circuit 212 formed on one side of the base film 211, a coverlay 213 covering the printed circuit 212, a printed circuit 214 formed on the other side of the base film 211, and a coverlay 215 covering the printed circuit 214.

[0128] In the printed circuit board 210, the printed circuit 212 includes a ground circuit 212a. Furthermore, the coverlay 213 has an opening 213a that exposes the ground circuit 212a. In the printed circuit board 210, the printed circuit 214 includes a ground circuit 214a. Furthermore, the coverlay 215 has an opening 215a that exposes the ground circuit 214a.

[0129] The preferred materials for the base film 211, printed circuit 212 and printed circuit 214, ground circuit 212a and ground circuit 214a, and coverlay 213 and coverlay 215 are the same materials as the base film 11, printed circuit 12, ground circuit 12a and coverlay 13 in the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention.

[0130] <First Electromagnetic Shielding Film Preparation Process> In this process, as shown in Figure 20, a first electromagnetic wave shielding film 220 is prepared by sequentially laminating a first protective film 221, a first insulating layer 222, a first shielding layer 224, and a first adhesive layer 223. Furthermore, the first electromagnetic shielding film 220 has a width wider than the width of the printed circuit board 210, and the first adhesive layer 223 is conductive.

[0131] The preferred materials for the first protective film 221, the first insulating layer 222, the first shielding layer 224, and the first adhesive layer 223 are the same as the preferred materials for the first protective film 21, the first insulating layer 22, the first shielding layer 24, and the first adhesive layer 23 in the manufacturing method of the shielded printed circuit board according to the first embodiment of the present invention.

[0132] <Second electromagnetic wave shielding film preparation process> In this process, as shown in Figure 21, a second electromagnetic wave shielding film 230 is prepared by sequentially laminating a second protective film 231, a second insulating layer 232, a second shielding layer 234, and a second adhesive layer 233. Furthermore, the second electromagnetic shielding film 230 has a width wider than the width of the printed circuit board 210, and the second adhesive layer 233 is conductive.

[0133] The preferred materials for the second protective film 231, the second insulating layer 232, the second shielding layer 234, and the second adhesive layer 233 are the same as the preferred materials for the second protective film 31, the second insulating layer 32, the second shielding layer 34, and the second adhesive layer 33 in the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention.

[0134] <First electromagnetic wave shielding film placement process> In this process, as shown in Figure 22, the first electromagnetic shielding film 220 is placed on the printed circuit board 210 such that the first adhesive layer 223 is in contact with the surface of the printed circuit board 210 on the coverlay 213 side. In this case, both ends of the first adhesive layer 223 are positioned outside the edges of the printed circuit board 210 to form the first extended end portion 223a.

[0135] <Second electromagnetic wave shielding film placement process> In this process, as shown in Figure 23, the second electromagnetic shielding film 230 is placed on the printed circuit board 210 such that the second adhesive layer 233 is in contact with the surface of the printed circuit board 210 that is on the coverlay 215 side. In this case, both ends of the second adhesive layer 233 are positioned outside the edges of the printed circuit board 210 to form the second extended end portion 233a.

[0136] <Overlay process> In this process, as shown in Figure 24, the first adhesive layer 223 and the second adhesive layer 233 are overlapped such that a gap 240 is created between the first extended end 223a of the first adhesive layer 223 located at both ends of the first electromagnetic wave shielding film 220 and the second extended end 33a of the second adhesive layer 233 located at both ends of the second electromagnetic wave shielding film 230, thereby producing a pre-press shielded printed circuit board 251.

[0137] In the method for manufacturing a shielded printed circuit board of the present invention, the first adhesive layer 223 and the second adhesive layer 233 are cured in two stages by performing a preliminary pressing step and a main pressing step, as described later. Even if a gap 240 is created between the first extension end 223a and the second extension end 233a during the overlapping process, these steps allow air to be removed from the gap 240, and the first adhesive layer 223 and the second adhesive layer 233 to be sufficiently bonded together. Furthermore, if one attempts to overlap the first and second adhesive layers in a way that prevents such gaps from forming during the overlapping process, it becomes necessary to apply high pressure and time during the overlapping process, resulting in poor production efficiency.

[0138] <Preliminary pressing process> In this process, as shown in Figure 25, the shield printed circuit board 251 before temporary pressing is pressurized and heated from the first protective film 221 side and the second protective film 231 side so that the first adhesive layer 223 and the second adhesive layer 233 do not completely harden, and the shield printed circuit board 252 after temporary pressing is manufactured.

[0139] In the preliminary pressing process, the first adhesive layer 223 and the second adhesive layer 233 are pressurized and heated so that they do not completely harden. In other words, in the preliminary pressing process, the first adhesive layer 223 and the second adhesive layer 233 are left in a semi-hardened state. By allowing the first adhesive layer 223 and the second adhesive layer 233 to partially harden, the positions of the first electromagnetic wave shielding film 220 and the second electromagnetic wave shielding film 230 can be fixed. Therefore, in the protective film peeling process described later, the first protective film 221 and the second protective film 231 become easier to peel off. Furthermore, since the first protective film 221 and the second protective film 231 are in place when pressurized and heated, the pressure can be applied evenly. Furthermore, in the pressing process described later, it becomes easier to remove air from the gap 240 between the first adhesive layer 223 and the second adhesive layer 233.

[0140] The desirable pressurizing and heating conditions in the temporary pressing process are the same as the desirable pressurizing and heating conditions in the temporary pressing process of the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention.

[0141] <Protective film removal process> In this process, as shown in Figure 26, the first protective film 221 and the second protective film 231 are peeled off from the shielded printed circuit board 252 after pre-pressing to produce the shielded printed circuit board 253 before the main press.

[0142] <Main Pressing Process> In this process, as shown in Figure 27A, the pre-press shield printed circuit board 253 is pressurized and heated from the first insulating layer 222 side and the second insulating layer 232 side to cure the first adhesive layer 223 and the second adhesive layer 233. At this time, air escapes from the gap 240 between the first adhesive layer 223 and the second adhesive layer 233, and the first adhesive layer 223 fills the opening 213a and comes into contact with the ground circuit 212a. The second adhesive layer 233 fills the opening 215a and comes into contact with the ground circuit 214a.

[0143] If the pressing process is performed without peeling off the first protective film 221 and the second protective film 231 during the protective film peeling process, the pressure will be absorbed, making it difficult to remove air from the gap 240 between the first adhesive layer 223 and the second adhesive layer 233. However, in the method for manufacturing a shielded printed circuit board according to the second embodiment of the present invention, the pressing process is performed after peeling off the first protective film 221 and the second protective film 231. Therefore, the pressure during this pressing process is less likely to be absorbed. Consequently, even if there is a gap 240 in part between the first adhesive layer 223 and the second adhesive layer 233, this pressing process makes it easier to remove air from that gap 40. As a result, the printed circuit board 210, the first adhesive layer 223, and the second adhesive layer 233 can be sufficiently adhered to each other.

[0144] The desirable pressurizing and heating conditions in this pressing process are the same as the desirable pressurizing and heating conditions in the preliminary pressing process of the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention.

[0145] In the manufacturing method of a shielded printed circuit board according to the third embodiment of the present invention, in the first electromagnetic wave shielding film preparation step and the second electromagnetic wave shielding film preparation step, it is desirable to adjust the thickness of the first adhesive layer and the second adhesive layer so that the sum of the thickness of the first adhesive layer at the first extended end and the thickness of the second adhesive layer at the second extended end after this pressing step is 1 / 30 to 1 times the thickness of the printed circuit board, more preferably to adjust the thickness of the first adhesive layer and the second adhesive layer so that it is 1 / 20 to 9 / 10 times the thickness, and even more preferably to adjust the thickness of the first adhesive layer and the second adhesive layer so that it is 1 / 15 to 9 / 10 times the thickness. By adjusting the thickness of the first adhesive layer and / or the second adhesive layer within the above range, it becomes easier to ensure sufficient adhesion between the first adhesive layer and the second adhesive layer. If, after this pressing process, the sum of the thickness of the first adhesive layer at the first extension end and the thickness of the second adhesive layer at the second extension end is less than 1 / 30th the thickness of the printed circuit board, a gap is likely to form between the first adhesive layer and the second adhesive layer. If, after this pressing process, the sum of the thickness of the first adhesive layer at the first extension end and the thickness of the second adhesive layer at the second extension end exceeds 1x the thickness of the printed circuit board, the shielded printed circuit board becomes too thick, limiting its applications.

[0146] After the above steps, a shielded printed circuit board 254 can be manufactured as shown in Figure 27B. The shielded printed circuit board 254 shown in Figure 27B consists of a printed circuit board 210, a first electromagnetic wave shielding section 220a positioned on top of the printed circuit board 210, and a second electromagnetic wave shielding section 230a positioned below the printed circuit board 210. The first electromagnetic wave shielding portion 220a is formed by the hardening of the adhesive layer of the first electromagnetic wave shielding film, and the second electromagnetic wave shielding portion 230a is formed by the hardening of the adhesive layer of the second electromagnetic wave shielding film.

[0147] The printed circuit board 210 consists of a base film 211, a printed circuit 212 formed on one side of the base film 211, a coverlay 213 covering the printed circuit 212, a printed circuit 214 formed on the other side of the base film, and a coverlay 215 covering the printed circuit 214. Furthermore, printed circuit 212 includes a ground circuit 212a, and printed circuit 214 includes a ground circuit 214a. Furthermore, the coverlay 213 has an opening 213a that exposes the ground circuit 212a, and the coverlay 215 has an opening 215a that exposes the ground member 214a.

[0148] The first electromagnetic wave shielding section 220a is formed by sequentially laminating a first insulating layer 222, a first shielding layer 224, and a first adhesive layer 223. The first adhesive layer 223 is positioned in contact with the coverlay 213. Furthermore, the first adhesive layer 223 fills the opening 213a of the coverlay 213, and the first adhesive layer 223 is in contact with the ground circuit 212a.

[0149] The second electromagnetic wave shielding section 230a is formed by sequentially laminating a second insulating layer 232, a second shielding layer 234, and a second adhesive layer 233. The second adhesive layer 233 is positioned in contact with the coverlay 215. Furthermore, the second adhesive layer 233 fills the opening 215a of the coverlay 215, and the second adhesive layer 233 is in contact with the ground circuit 214a.

[0150] Furthermore, in the shielded printed circuit board 254, the width of the first electromagnetic wave shielding portion 220a is wider than the width of the printed circuit board 210, and both ends of the first adhesive layer 223 of the first electromagnetic wave shielding portion 220a are located further out than both ends of the printed circuit board 210, forming the first extended end portion 223a. Furthermore, in the shielded printed circuit board 254, the width of the second electromagnetic wave shielding portion 230a is wider than the width of the printed circuit board 210, and both ends of the second electromagnetic wave shielding portion 230a are located further out than both ends of the printed circuit board 210, forming the second extended end portion 233a. Furthermore, the first adhesive layer 223 located at the first extension end 223a and the second adhesive layer 233 located at the second extension end 233a are bonded together. In shielded printed circuit boards, the first adhesive layer located at the first extension end and the second adhesive layer located at the second extension end are so integrated that their boundaries are indistinguishable. However, in Figure 27B, the first adhesive layer 223 located at the first extension end 223a and the second adhesive layer 233 located at the second extension end 233a are shown as separate regions for convenience.

[0151] (Fourth Embodiment) Next, a method for manufacturing a shielded printed circuit board according to a fourth embodiment of the present invention, which is an example of the method for manufacturing a shielded printed circuit board according to the present invention, will be described.

[0152] Figure 28 is a schematic process diagram showing an example of the printed circuit board preparation step in the method for manufacturing a shielded printed circuit board according to the fourth embodiment of the present invention. Figure 29 is a schematic process diagram showing an example of the first electromagnetic wave shielding film preparation step in the method for manufacturing a shielded printed circuit board according to the fourth embodiment of the present invention. Figure 30 is a schematic process diagram showing an example of the second electromagnetic wave shielding film preparation step in the method for manufacturing a shielded printed circuit board according to the fourth embodiment of the present invention. Figure 31 is a schematic process diagram showing an example of the first electromagnetic wave shielding film placement step in the method for manufacturing a shielded printed circuit board according to the fourth embodiment of the present invention. Figure 32 is a schematic process diagram showing an example of the second electromagnetic wave shielding film placement step in the method for manufacturing a shielded printed circuit board according to the fourth embodiment of the present invention. Figure 33 is a schematic process diagram showing an example of the overlapping process in the manufacturing method of a shielded printed circuit board according to the fourth embodiment of the present invention. Figure 34 is a schematic process diagram showing an example of a preliminary pressing step in a method for manufacturing a shielded printed circuit board according to the fourth embodiment of the present invention. Figure 35 is a schematic process diagram showing an example of the protective film peeling step in the method for manufacturing a shielded printed circuit board according to the fourth embodiment of the present invention. Figures 36A and 36B are schematic process diagrams illustrating an example of the main pressing step in the method for manufacturing a shielded printed circuit board according to the fourth embodiment of the present invention.

[0153] <Preparation process for printed circuit boards> In this process, as shown in Figure 28, a printed circuit board 310 is prepared, comprising a base film 311, a printed circuit 312 formed on the base film 311, and a coverlay 313 covering the printed circuit 312. In the printed circuit board 310, the printed circuit 312 includes a ground circuit 312a. Furthermore, the printed circuit board 310 has through-holes 316 that penetrate the base film 311 and the coverlay 313, and the ground circuit 312a is exposed through the through-holes 316.

[0154] <First Electromagnetic Shielding Film Preparation Process> In this process, as shown in Figure 29, a first electromagnetic wave shielding film 320 is prepared by sequentially laminating a first protective film 321, a first insulating layer 322, a first shielding layer 324, and a first adhesive layer 323. Furthermore, the first electromagnetic shielding film 320 has a width wider than the width of the printed circuit board 310, and the first adhesive layer 323 is conductive.

[0155] The preferred materials for the first protective film 321, the first insulating layer 322, the first shielding layer 324, and the first adhesive layer 323 are the same as the preferred materials for the first protective film 21, the first insulating layer 22, the first shielding layer 24, and the first adhesive layer 23 in the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention.

[0156] <Second electromagnetic wave shielding film preparation process> In this process, as shown in Figure 30, a second electromagnetic wave shielding film 330 is prepared by sequentially laminating a second protective film 331, a second insulating layer 332, a second shielding layer 334, and a second adhesive layer 333. Furthermore, the second electromagnetic shielding film 330 has a width wider than the printed circuit board 310, and the second adhesive layer 333 is conductive.

[0157] The preferred materials for the second protective film 331, the second insulating layer 332, the second shielding layer 334, and the second adhesive layer 333 are the same as the preferred materials for the second protective film 31, the second insulating layer 32, the second shielding layer 34, and the second adhesive layer 33 in the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention.

[0158] <First electromagnetic wave shielding film placement process> In this process, as shown in Figure 31, the first electromagnetic shielding film 320 is placed on the printed circuit board 310 such that the first adhesive layer 323 faces the coverlay 313 side of the printed circuit board 310. In this case, both ends of the first adhesive layer 323 are positioned outside the edges of the printed circuit board 310 to form the first extended end portion 323a.

[0159] <Second electromagnetic wave shielding film placement process> In this process, as shown in Figure 32, the second electromagnetic shielding film 330 is placed on the printed circuit board 310 such that the second adhesive layer 333 is in contact with the base film 311 side of the printed circuit board 310. In this case, both ends of the second adhesive layer 333 are positioned outside the edges of the printed circuit board 310 to form the second extended end portion 333a.

[0160] <Overlay process> In this process, as shown in Figure 33, the first adhesive layer 323 and the second adhesive layer 333 are overlapped such that a gap 340 is created between the first extended end 323a of the first adhesive layer 323 located at both ends of the first electromagnetic wave shielding film 320 and the second extended end 333a of the second adhesive layer 333 located at both ends of the second electromagnetic wave shielding film 330. Furthermore, the first adhesive layer 323 and the second adhesive layer 333 are overlapped so that a gap 340 is created between the first adhesive layer 323 of the first electromagnetic wave shielding film 320, which is placed in the through hole 316, and the second adhesive layer 333 of the second electromagnetic wave shielding film 330. In this way, a pre-press shielded printed circuit board 351 is manufactured.

[0161] In the method for manufacturing a shielded printed circuit board of the present invention, the first adhesive layer 323 and the second adhesive layer 333 are cured in two stages by performing a preliminary pressing step and a main pressing step, as described later. Even if gaps 340 occur between the first extension end 323a and the second extension end 333a or in the through hole 316 during the overlapping process, these processes allow air to be removed from the gaps 340, enabling sufficient adhesion between the first adhesive layer 323 and the second adhesive layer 333. Furthermore, if one attempts to overlap the first and second adhesive layers in a way that prevents such gaps from forming during the overlapping process, it becomes necessary to apply high pressure and time during the overlapping process, resulting in poor production efficiency.

[0162] <Preliminary pressing process> In this process, as shown in Figure 34, the shield printed circuit board 351 before temporary pressing is pressurized and heated from the first protective film 321 side and the second protective film 331 side so that the first adhesive layer 323 and the second adhesive layer 333 do not completely harden, and the shield printed circuit board 352 after temporary pressing is manufactured.

[0163] In the preliminary pressing process, the first adhesive layer 323 and the second adhesive layer 333 are pressurized and heated so that they do not completely harden. In other words, in the preliminary pressing process, the first adhesive layer 323 and the second adhesive layer 333 are left in a semi-hardened state. By allowing the first adhesive layer 323 and the second adhesive layer 333 to partially harden, the positions of the first electromagnetic wave shielding film 320 and the second electromagnetic wave shielding film 330 can be fixed. Therefore, in the protective film peeling process described later, the first protective film 321 and the second protective film 331 become easier to peel off. Furthermore, since the first protective film 321 and the second protective film 331 are in place when pressurized and heated, the pressure can be applied evenly. Furthermore, in the pressing process described later, it becomes easier to remove air from the gap 340 between the first adhesive layer 323 and the second adhesive layer 333.

[0164] <Protective film removal process> In this process, as shown in Figure 35, the first protective film 321 and the second protective film 331 are peeled off from the shielded printed circuit board 352 after pre-pressing to produce the shielded printed circuit board 353 before the main press.

[0165] <Main Pressing Process> In this process, as shown in Figure 36A, the pre-press shield printed circuit board 353 is pressurized and heated from the first insulating layer 322 side and the second insulating layer 332 side to cure the first adhesive layer 323 and the second adhesive layer 333. At this time, air escapes from the gap 340 between the first adhesive layer 323 and the second adhesive layer 333, and the first adhesive layer 323 and the second adhesive layer 333 fill the through hole 316. Furthermore, the first adhesive layer 323 will be in contact with the ground circuit 312a. Furthermore, the first adhesive layer 323 and the second adhesive layer 333 will be in contact at the through hole 316.

[0166] If the pressing process is performed without peeling off the first protective film 321 and the second protective film 331 during the protective film peeling process, the pressure will be absorbed, making it difficult to remove air from the gap 340 between the first adhesive layer 323 and the second adhesive layer 333. However, in the method for manufacturing a shielded printed circuit board according to the second embodiment of the present invention, the pressing process is performed after peeling off the first protective film 321 and the second protective film 331. Therefore, the pressure during this pressing process is less likely to be absorbed. Consequently, even if there is a gap 340 in part between the first adhesive layer 323 and the second adhesive layer 333, the air can be sufficiently removed from that gap 40 by performing this pressing process. As a result, the printed circuit board 310, the first adhesive layer 323, and the second adhesive layer 333 can be sufficiently adhered to each other.

[0167] The desirable pressurizing and heating conditions in this pressing process are the same as the desirable pressurizing and heating conditions in the preliminary pressing process of the method for manufacturing a shielded printed circuit board according to the first embodiment of the present invention.

[0168] Furthermore, in the manufacturing method of the shielded printed circuit board according to the fourth embodiment of the present invention, in the first electromagnetic wave shielding film preparation step and the second electromagnetic wave shielding film preparation step, it is desirable to adjust the thickness of the first adhesive layer and the second adhesive layer so that the sum of the thickness of the first adhesive layer at the first extended end and the thickness of the second adhesive layer at the second extended end after the pressing step is 1 / 30 to 1 times the thickness of the printed circuit board, more preferably to adjust the thickness of the first adhesive layer and the second adhesive layer so that it is 1 / 20 to 9 / 10 times the thickness, and even more preferably to adjust the thickness of the first adhesive layer and the second adhesive layer so that it is 1 / 15 to 9 / 10 times the thickness. By adjusting the thickness of the first adhesive layer and / or the second adhesive layer within the above range, it becomes easier to ensure sufficient adhesion between the first adhesive layer and the second adhesive layer. If, after this pressing process, the sum of the thickness of the first adhesive layer at the first extension end and the thickness of the second adhesive layer at the second extension end is less than 1 / 30th the thickness of the printed circuit board, a gap is likely to form between the first adhesive layer and the second adhesive layer. If, after this pressing process, the sum of the thickness of the first adhesive layer at the first extension end and the thickness of the second adhesive layer at the second extension end exceeds 1x the thickness of the printed circuit board, the shielded printed circuit board becomes too thick, limiting its applications.

[0169] After the above steps, a shielded printed circuit board 354 can be manufactured as shown in Figure 36B. The shielded printed circuit board 354 shown in Figure 36B consists of a printed circuit board 310, a first electromagnetic wave shielding section 320a positioned on top of the printed circuit board 310, and a second electromagnetic wave shielding section 330a positioned below the printed circuit board 310. Furthermore, the first electromagnetic wave shielding portion 320a is a portion formed by the hardening of the adhesive layer of the first electromagnetic wave shielding film, and the second electromagnetic wave shielding portion 330a is a portion formed by the hardening of the adhesive layer of the second electromagnetic wave shielding film.

[0170] The printed wiring board 310 includes a base film 311, a printed circuit 312 including a ground circuit 312a formed on the base film 311, and a coverlay 313 covering the printed circuit 312. In addition, through holes 316 penetrating the base film 311 and the coverlay 313 are formed in the printed wiring board 310, and the ground circuit 312a is exposed from the through holes 316.

[0171] The first electromagnetic wave shielding portion 320a is formed by laminating a first insulating layer 322 and a first adhesive layer 323 in this order. The first adhesive layer 323 is disposed so as to contact the coverlay 313. In addition, the first adhesive layer 323 fills the through holes 316, and the first adhesive layer 323 and the ground circuit 312a are in contact with each other.

[0172] The second electromagnetic wave shielding portion 330a is formed by laminating a second insulating layer 332 and a second adhesive layer 333 in this order. The second adhesive layer 333 is disposed so as to contact the base film 311. In addition, the second adhesive layer 333 fills the through holes 316, and the first adhesive layer 323 and the second adhesive layer 333 are in contact with each other.

[0173] Furthermore, in the shielded printed wiring board 354, the width of the first electromagnetic wave shielding portion 320a is wider than the width of the printed wiring board 310, and both ends of the first adhesive layer 323 of the first electromagnetic wave shielding portion 320a are located outside both ends of the printed wiring board 310 to form first extended portions 323a. In addition, in the shielded printed wiring board 354, the width of the second electromagnetic wave shielding portion 330a is wider than the width of the printed wiring board 310, and both ends of the second electromagnetic wave shielding portion 330a are located outside both ends of the printed wiring board 310 to form second extended portions 333a.​​​In shielded printed circuit boards, the first adhesive layer located at the first extension end and the second adhesive layer located at the second extension end are so integrated that their boundaries are indistinguishable. However, in Figure 36B, the first adhesive layer 323 located at the first extension end 323a and the second adhesive layer 333 located at the second extension end 333a are shown as separate regions for convenience.

[0174] (Fifth embodiment) Next, a shielded printed circuit board according to a fifth embodiment, which is an example of the shielded printed circuit board of the present invention, will be described.

[0175] Figure 37 is a schematic cross-sectional view showing an example of a shielded printed circuit board according to a fifth embodiment of the present invention. The shielded printed circuit board 454 shown in Figure 37 comprises a printed circuit board 410 having a base film 411, a printed circuit 412 formed on the base film 411, and a coverlay 413 covering the printed circuit 412, a first insulating layer 422 disposed to cover one side of the printed circuit board 410, and a second insulating layer 432 disposed to cover the other side of the printed circuit board 410.

[0176] A portion of the first insulating layer 422 forms a first insulating layer extension 422a located outside the edge of the printed circuit board 410, and a portion of the second insulating layer 432 forms a second insulating layer extension 432a located outside the edge of the printed circuit board 410. Furthermore, the first insulating layer extension end 422a and the second insulating layer extension end 432a are facing each other.

[0177] The space between the first insulating layer 422 and one surface of the printed circuit board 410, the space between the second insulating layer 432 and the other surface of the printed circuit board 410, and the region where the extension end 422a of the first insulating layer and the extension end 432a of the second insulating layer face each other are filled with conductive resin composition 463.

[0178] Furthermore, the thickness T1 of the conductive resin composition 463 filled between the first insulating layer 422 and the second insulating layer 432 in the region where the extension ends 422a of the first insulating layer and 432a of the second insulating layer face each other is between 1 / 30 and 1x the thickness T2 of the printed circuit board 410. The thickness T1 of the conductive resin composition 463 is preferably 1 / 20 to 9 / 10 times the thickness T2 of the printed circuit board 410, and more preferably 1 / 15 to 9 / 10 times. During the manufacturing of the shielded printed circuit board 454, by adjusting the amount of conductive resin composition 463 so that the thickness of the conductive resin composition 463 filled between the first insulating layer 422 and the second insulating layer 432 in the region where the first insulating layer extension end 432a and the second insulating layer extension end 422a face each other, the space between the first insulating layer 422 and the second insulating layer 432 in the region where the first insulating layer extension end 432a and the second insulating layer extension end 422a face each other can be filled with conductive resin composition 463 without any gaps.

[0179] In the shielded printed circuit board 454, the printed circuit 412 of the printed circuit board 410 includes a ground circuit 412a, a portion of which is exposed through an opening in the coverlay 413, and the ground circuit 412a is electrically connected to the conductive resin composition 463. With the printed circuit board 454 having such a structure, the ground circuit 412a and the conductive resin composition 463 can be electrically connected.

[0180] In the shielded printed circuit board 454, the materials of the first insulating layer 422 and the second insulating layer 432 are not particularly limited, but it is desirable that they be composed of a thermoplastic resin composition, a thermosetting resin composition, an active energy ray curable composition, etc.

[0181] The thermoplastic resin composition mentioned above is not particularly limited, but examples include styrene-based resin compositions, vinyl acetate-based resin compositions, polyester-based resin compositions, polyethylene-based resin compositions, polypropylene-based resin compositions, imide-based resin compositions, and acrylic-based resin compositions. Among these, an imide-based resin composition is preferred, and a polyimide resin composition is even more preferred.

[0182] The above thermosetting resin composition is not particularly limited, but examples include epoxy resin compositions, urethane resin compositions, urethane urea resin compositions, styrene resin compositions, phenolic resin compositions, melamine resin compositions, acrylic resin compositions, and alkyd resin compositions.

[0183] The above-mentioned active energy ray curable composition is not particularly limited, but examples include polymerizable compounds having at least two (meth)acryloyloxy groups in the molecule.

[0184] The first insulating layer 422 and the second insulating layer 432 may be composed of a single material or of two or more materials.

[0185] The first insulating layer 422 and the second insulating layer 432 may optionally contain curing accelerators, tackifiers, antioxidants, pigments, dyes, plasticizers, ultraviolet absorbers, defoamers, leveling agents, fillers, flame retardants, viscosity modifiers, anti-blocking agents, and the like.

[0186] The thicknesses of the first insulating layer 422 and the second insulating layer 432 are not particularly limited and can be set as appropriate as needed, but are preferably 1 to 15 μm, and more preferably 3 to 10 μm.

[0187] As shown in Figure 37, in the shielded printed circuit board 454, a first shield layer 424 is formed between the first insulating layer 422 and the conductive resin composition 463. In addition, a second shield layer 434 is formed between the second insulating layer 432 and the conductive resin composition 463. The first shield layer 424 may be made of metal, or it may be made of a conductive resin composition for the first shield layer. Further, the second shield layer 434 may be made of metal or may be made of a conductive resin composition for the second shield layer. When the first shield layer 424 and the second shield layer 434 are formed in this way, electromagnetic waves can be suitably shielded.

[0188] When the first shield layer is made of metal, examples of the metal include gold, silver, copper, aluminum, nickel, tin, palladium, chromium, titanium, zinc, and the like. When the second shield layer is made of metal, examples of the metal include gold, silver, copper, aluminum, nickel, tin, palladium, chromium, titanium, zinc, and the like. Among these, copper is desirable. Copper is a suitable material for the first shield layer from the viewpoints of conductivity and economy.

[0189] The first shield layer 424 and the second shield layer 434 may be made of an alloy of the above metals. They may also be metal foils or metal films formed by methods such as sputtering, electroless plating, electrolytic plating, etc.

[0190] When the first shield layer 424 is made of a conductive resin composition for the first shield layer, the first shield layer 424 may be composed of conductive particles and a resin. When the second shield layer 434 is made of a conductive resin composition for the second shield layer, the second shield layer 434 may be composed of conductive particles and a resin.

[0191] The conductive particles constituting the first shield layer 424 and the second shield layer 434 are not particularly limited, and may be, for example, metal fine particles, carbon nanotubes, carbon fibers, metal fibers, and the like.

[0192] When the conductive particles constituting the first shield layer 424 and the second shield layer 434 are metal nanoparticles, the metal nanoparticles are not particularly limited, but may include silver powder, copper powder, nickel powder, solder powder, aluminum powder, silver-coated copper powder obtained by silver plating on copper powder, polymer nanoparticles, glass beads, etc., coated with metal. Of these options, from an economic standpoint, copper powder or silver-coated copper powder, which are readily available at low cost, are preferable.

[0193] The average particle diameter of the conductive particles constituting the first shield layer 424 and the second shield layer 434 is not particularly limited, but is preferably 0.5 to 15.0 μm. Good conductivity is achieved when the average particle diameter of the conductive particles is 0.5 μm or more. If the average particle diameter of the conductive particles is 15.0 μm or less, the first shield layer 424 and the second shield layer 434 can be made thinner.

[0194] The shape of the conductive particles constituting the first shield layer 424 and the second shield layer 434 is not particularly limited, but can be appropriately selected from spherical, flattened, flake-shaped, dendritic, rod-shaped, fibrous, and the like.

[0195] The proportion of conductive particles constituting the first shield layer 424 and the second shield layer 434 is not particularly limited, but is preferably 15 to 90% by weight, and more preferably 15 to 60% by weight.

[0196] The resins constituting the first shield layer 424 and the second shield layer 434 are not particularly limited, but examples include thermoplastic resin compositions such as styrene resin compositions, vinyl acetate resin compositions, polyester resin compositions, polyethylene resin compositions, polypropylene resin compositions, imide resin compositions, amide resin compositions, and acrylic resin compositions, as well as thermosetting resin compositions such as phenol resin compositions, epoxy resin compositions, urethane resin compositions, melamine resin compositions, and alkyd resin compositions.

[0197] The conductive resin composition 463 in the shielded printed circuit board 454 consists of a resin and conductive particles.

[0198] The resin constituting the conductive resin composition 463 may be a thermosetting resin or a thermoplastic resin. Examples of thermosetting resins include phenolic resins, epoxy resins, urethane resins, melamine resins, polyamide resins, and alkyd resins. Examples of thermoplastic resins include styrene resins, vinyl acetate resins, polyester resins, polyethylene resins, polypropylene resins, imide resins, and acrylic resins. Furthermore, it is more desirable that the epoxy resin be an amide-modified epoxy resin.

[0199] The conductive particles constituting the conductive resin composition 463 are not particularly limited, but may include metal nanoparticles, carbon nanotubes, carbon fibers, metal fibers, etc.

[0200] When the conductive particles constituting the conductive resin composition 463 are metal nanoparticles, the metal nanoparticles are not particularly limited, but may include silver powder, copper powder, nickel powder, solder powder, aluminum powder, silver-coated copper powder obtained by silver plating on copper powder, polymer nanoparticles, glass beads, etc., coated with metal. Of these options, from an economic standpoint, copper powder or silver-coated copper powder, which are readily available at low cost, are preferable.

[0201] The average particle diameter of the conductive particles constituting the conductive resin composition 463 is not particularly limited, but is preferably 0.5 to 15.0 μm. If the average particle diameter of the conductive particles is 0.5 μm or more, the conductivity is good. If the average particle diameter of the conductive particles is 15.0 μm or less, the conductive resin composition can be made thinner.

[0202] The shape of the conductive particles constituting the conductive resin composition 463 is not particularly limited, but can be appropriately selected from spherical, flattened, flake-shaped, dendritic, rod-shaped, fibrous, and the like.

[0203] The weight percentage of conductive particles in conductive resin composition 463 is preferably 3 to 90% by weight, and more preferably 39 to 90% by weight. If the weight percentage of conductive particles is less than 3% by weight, the shielding performance may not be sufficient. If the weight percentage of conductive particles exceeds 90% by weight, the adhesive strength of the conductive resin composition tends to decrease during manufacturing. Furthermore, if the weight percentage of conductive particles is 39-90% by weight, the conductive resin composition 463 will have isotropic conductivity.

[0204] The conductive resin composition 463 is preferably an isotropic conductive resin composition. If the conductive resin composition 463 is an isotropic conductive resin composition, electromagnetic noise radiated from the printed circuit board 410 can be effectively blocked.

[0205] Such a shielded printed circuit board 454 can be manufactured by the method for manufacturing a shielded printed circuit board according to the present invention.

[0206] (Other embodiments) In the manufacturing method of the shielded printed circuit board according to the first to fourth embodiments of the present invention described above, the first electromagnetic wave shielding film and the second electromagnetic wave shielding film were arranged such that both ends of the first electromagnetic wave shielding film and both ends of the second electromagnetic wave shielding film were located outside the ends of the printed circuit board. However, in the method for manufacturing a shielded printed circuit board according to the present invention, the first electromagnetic shielding film and the second electromagnetic shielding film may be arranged such that only one end of the first electromagnetic shielding film and one end of the second electromagnetic shielding film are located outside one end of the printed circuit board. Alternatively, the first electromagnetic shielding film and the second electromagnetic shielding film may be arranged such that only a portion of one end of the first electromagnetic shielding film and a portion of one end of the second electromagnetic shielding film are located outside the edge of the printed circuit board.

[0207] In the methods for manufacturing shielded printed circuit boards according to the first, third, and fourth embodiments of the present invention described above, the first adhesive layer and the second adhesive layer were electrically conductive. However, in the method for manufacturing a shielded printed circuit board according to the present invention, the first adhesive layer and the second adhesive layer do not need to be conductive. That is, the first adhesive layer and the second adhesive layer may be formed from an insulating resin composition. In this case, an electromagnetic shielding effect can be obtained by electrically connecting the shielding layer to an external ground or the like.

[0208] In the shielded printed circuit board according to the fifth embodiment of the present invention described above, a first shield layer is formed between the first insulating layer and the conductive resin composition, and a second shield layer is formed between the second insulating layer and the conductive resin composition. However, in the shielded printed circuit board of the present invention, the first shield layer and the second shield layer do not necessarily have to be formed. In this case, the conductive resin composition will exhibit an electromagnetic wave shielding effect. [Explanation of symbols]

[0209] 10, 110, 210, 310, 410 Printed Circuit Boards 11, 111, 211, 311, 411 base film 12, 112, 212, 214, 312, 412 printed circuit boards 12a, 112a, 212a, 214a, 312a, 412a Ground Circuit 13, 113, 213, 215, 313, 413 Coverlay 13a, 113a, 213a, 215a opening 20, 120, 220, 320 1st Electromagnetic Shielding Film 20a, 120a, 220a, 320a First electromagnetic wave shielding section 21, 121, 221, 321 First protective film 22, 122, 222, 322, 422 First insulating layer 23, 123, 223, 323 First adhesive layer 23a, 123a, 223a, 323a 1st extension end 24, 224, 324, 424 First Shield Layer 30, 130, 230, 330 Second Electromagnetic Shielding Film 30a, 320a, 320a, 320a Second electromagnetic wave shielding section 31, 131, 231, 331 Second protective film 32, 132, 232, 332, 432 Second insulating layer 33, 133, 233, 333 Second adhesive layer 33a, 133a, 233a, 333a 2nd extension end 34, 234, 334, 434 Second Shield Layer 40, 140, 240, 340 gap 51, 151, 251, 351 Pre-press Shielded Printed Wiring Boards 52, 152, 252, 352 Shielded printed circuit board after temporary pressing 53, 153, 253, 353 Pre-press Shielded Printed Circuit Boards 54, 154, 254, 354, 454 Shielded Printed Circuit Boards 316 Through hole 422a End portion of the first insulating layer 432a Second insulation layer extension 463 Conductive resin composition

Claims

1. A printed circuit board comprising a base film, a printed circuit formed on the base film, and a coverlay covering the printed circuit, A first insulating layer is arranged to cover one side of the printed circuit board, It has a second insulating layer that is arranged to cover the other side of the printed circuit board, A portion of the first insulating layer forms an extended portion of the first insulating layer located outside the edge of the printed circuit board. A portion of the second insulating layer forms an extended portion of the second insulating layer located outside the edge of the printed circuit board. The first insulating layer extension end and the second insulating layer extension end face each other, The space between the first insulating layer and one surface of the printed circuit board, the space between the second insulating layer and the other surface of the printed circuit board, and the region where the extension end of the first insulating layer and the extension end of the second insulating layer face each other are filled without gaps with a conductive resin composition. A shielded printed circuit board characterized in that the thickness of the conductive resin composition filled between the first insulating layer and the second insulating layer in the region where the extension end of the first insulating layer and the extension end of the second insulating layer face each other is 1 / 30 to 9 / 10 times the thickness of the printed circuit board.

2. The shielded printed circuit board according to claim 1, wherein a first shield layer is formed between the first insulating layer and the conductive resin composition.

3. The shielded printed circuit board according to claim 2, wherein the first shield layer is made of metal.

4. The shielded printed circuit board according to claim 2, wherein the first shield layer is made of a conductive resin composition for the first shield layer.

5. A shielded printed circuit board according to any one of claims 1 to 4, wherein a second shield layer is formed between the second insulating layer and the conductive resin composition.

6. The shielded printed circuit board according to claim 5, wherein the second shield layer is made of metal.

7. The shielded printed circuit board according to claim 5, wherein the second shield layer is made of a conductive resin composition for the second shield layer.

8. The shielded printed circuit board according to any one of claims 1 to 7, wherein the conductive resin composition is an isotropic conductive resin composition.

9. The conductive resin composition comprises conductive particles and a resin. The shielded printed circuit board according to any one of claims 1 to 8, wherein the weight percentage of the conductive particles is 3 to 90% by weight.

10. The printed circuit of the printed wiring board includes a ground circuit, and a portion of the ground circuit is exposed to the outside. The shielded printed circuit board according to any one of claims 1 to 9, wherein the ground circuit and the conductive resin composition are electrically connected.

11. The shielded printed circuit board according to any one of claims 1 to 10, wherein the first insulating layer is at least one selected from polyimide resin, polyamideimide resin, polyamide resin, polyetherimide resin, polyesterimide resin, polyethernitrile resin, polyethersulfone resin, polyphenylene sulfide resin, polyethylene terephthalate resin, polypropylene resin, crosslinked polyethylene resin, polyester resin, polybenzimidazole resin, polyimide resin, polyimideamide resin, polyetherimide resin, and polyphenylene sulfide resin.

12. The shielded printed circuit board according to any one of claims 1 to 11, wherein the second insulating layer is at least one selected from polyimide resin, polyamideimide resin, polyamide resin, polyetherimide resin, polyesterimide resin, polyethernitrile resin, polyethersulfone resin, polyphenylene sulfide resin, polyethylene terephthalate resin, polypropylene resin, crosslinked polyethylene resin, polyester resin, polybenzimidazole resin, polyimide resin, polyimideamide resin, polyetherimide resin, and polyphenylene sulfide resin.

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