Ground connection lead-out film

Abstract

The present disclosure provides a ground connection lead-out film in which peeling between a metal layer and an adhesive layer is difficult to occur, and in which gas is difficult to be accumulated between the metal layer and the adhesive layer upon heating, or a ground connection lead-out film capable of forming the same. A ground connection lead-out film 1 includes a metal layer 2, and an adhesive layer 3 provided on one face 2b of the metal layer 2. The metal layer 2 is formed with an opening portion 21 that penetrates in a thickness direction T, and the opening portion 21 has a cross section that includes a first wide side D1 and a second wide side D2 in a cross section in the thickness direction T, the first wide side D1 extending in a face extension direction H and being relatively wide, and the second wide side D2 extending in the face extension direction H and being relatively narrow with respect to the first wide side D1. The adhesive layer 3 is laminated on the metal layer 2 face on the second wide side D2 side with respect to the first wide side D1. A portion of the adhesive layer 3 is capable of or has invaded the opening portion 21, and in a state in which a portion of the adhesive layer 3 has invaded the opening portion 21, the second wide side D2 is buried in the adhesive layer in the opening portion 21.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a ground connection lead-out film. BACKGROUND

[0002] Printed wiring boards are widely used in electronic devices such as mobile phones, video cameras, and notebook personal computers to incorporate circuits into mechanisms. They are also used to connect a movable portion such as a print head and a control portion. In these electronic devices, electromagnetic wave shielding measures are necessary, and even printed wiring boards used within the devices use shielded printed wiring boards that implement electromagnetic wave shielding measures.

[0003] The above-described shielded printed wiring board, for example, has a structure in which an electromagnetic wave shielding film in which an adhesive layer, a metal thin film, and an insulating layer are sequentially stacked is placed on a base film including a printed circuit and the adhesive layer of the electromagnetic wave shielding film is closely adhered thereto, and then the adhesive layer is joined to the base film by heating and pressing (thermocompression bonding).

[0004] Further, for the purpose of releasing electromagnetic waves that have intruded into a shielded printed wiring board or have been generated therein to the outside, a ground connection lead-out film is sometimes used. The ground connection lead-out film is known to be composed of a metal layer that is a conductive substrate and an adhesive layer for attaching to an arbitrary site in a shielded printed wiring board (for example, refer to Patent Documents 1 and 2).

[0005] PRIOR ART DOCUMENTS

[0006] PATENT DOCUMENTS

[0007] Patent Document 1: Japanese Patent Laid-Open No. 2016-122687;

[0008] Patent Document 2: Japanese Patent Laid-Open No. 2003-86907. SUMMARY

[0009] PROBLEMS TO BE SOLVED BY THE INVENTION

[0010] However, in the conventional ground connection lead-out film, if the interlayer close adhesion force of the metal layer and the adhesive layer is weak, there is a problem that peeling is easily generated between the metal layer and the adhesive layer. Also, when the ground connection lead-out film is thermocompression bonded to attach it to a shielded printed wiring board, a printed wiring board, or when heated in a reflow soldering process, an organic solvent remaining in the adhesive layer volatilizes and generates gas, and the gas cannot pass through the metal layer, so there is a problem that it accumulates between the metal layer and the adhesive layer. If rapid heating is performed in a solder reflow process, due to the gas accumulated between the metal layer and the adhesive layer, there is a case where bubbling occurs, or the close adhesion between the metal layer and the adhesive layer is destroyed.

[0011] A method of preventing bubbling caused by generated gas is known in which a metal layer having a plurality of opening portions is used. However, if the opening portions are provided, the boundary area between the metal layer and the adhesive layer decreases, and peeling between the layers is more likely to occur.

[0012] Therefore, the present disclosure aims to provide a grounding connection lead-out film in which peeling between a metal layer and an adhesive layer is less likely to occur, and in which gas is less likely to be trapped between the metal layer and the adhesive layer when heated, or a grounding connection lead-out film capable of forming the film.

[0013] Technical means for solving the technical problem

[0014] The inventors of the present disclosure diligently discussed in order to achieve the above-mentioned object, and as a result, found that in a grounding connection lead-out film, by making the shape of an opening portion provided in a metal layer, and the stacking method of the metal layer and an adhesive layer, a specific shape or method, peeling between the metal layer and the adhesive layer is less likely to occur, and gas is less likely to be trapped between the metal layer and the adhesive layer when heated. The present disclosure was completed based on this finding.

[0015] That is, the present disclosure provides a grounding connection lead-out film including a metal layer, an adhesive layer provided on one face of the metal layer,

[0016] An opening portion through the metal layer in the thickness direction is formed in the metal layer,

[0017] The opening portion has a cross section including a first wide side and a second wide side in a cross section in the thickness direction, the first wide side extending in a face extension direction and being relatively wide, and the second wide side extending in the face extension direction and being relatively narrow with respect to the first wide side,

[0018] The adhesive layer is stacked on the metal layer face on the second wide side side with respect to the first wide side,

[0019] A portion of the adhesive layer is capable of or has invaded the opening portion,

[0020] In a state in which a portion of the adhesive layer has invaded the opening portion, the second wide side is buried in the adhesive layer that has invaded the opening portion.

[0021] In the ground connection lead-out film described above, the metal layer is formed with an opening portion that penetrates in the thickness direction, whereby when gas is generated in the adhesive layer at the time of heating, the gas can pass through the metal layer via the opening portion, so it is difficult for gas to be trapped between the metal layer and the adhesive layer. Also, the opening portion has a first wide side that is relatively wide and a second wide side that is relatively narrow, and the adhesive layer is laminated to the metal layer on the side of the metal layer on which the second wide side that is relatively narrow is present, with reference to the first wide side. In addition, in the first state, a portion of the adhesive layer can intrude into the opening portion. The transition to the second state is performed, for example, by performing a heating and pressurization process from the first state. In the second state, a portion of the adhesive layer has intruded into the opening portion, and the second wide side that is relatively narrow in width is buried in the adhesive layer that has intruded into the opening portion. In the second state of the ground connection lead-out film, even when a force is applied in a direction in which the metal layer and the adhesive layer are to be peeled from each other, the adhesive in the opening portion is caught by the portion of the metal layer that includes the second wide side, so the adhesive in the opening portion and the adhesive outside the opening portion that is integral with the adhesive in the opening portion are difficult to peel from the metal layer, and thus the adhesive layer is difficult to peel from the metal layer.

[0022] Effects of Invention

[0023] The ground connection lead-out film according to an embodiment of the present disclosure can achieve the effects of making it difficult for peeling to occur between the metal layer and the adhesive layer, and making it difficult for gas to be trapped between the metal layer and the adhesive layer at the time of heating. Also, the ground connection lead-out film according to another embodiment of the present disclosure can form a ground connection lead-out film that achieves the effects described above. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 (a) an appearance view and (b) an enlarged view of a-a' section that is a thickness direction section of the first state of the ground connection lead-out film according to the present disclosure;

[0025] Figure 2 (a) an appearance view and (b) an enlarged view of b-b' section that is a thickness direction section of the second state of the ground connection lead-out film according to the present disclosure;

[0026] Figure 3 (a) an appearance view and (b) an enlarged view of b-b' section that is a thickness direction section of the second state of the ground connection lead-out film according to the present disclosure; Figure 1 (a) an appearance view and (b) an enlarged view of b-b' section that is a thickness direction section of the second state of the ground connection lead-out film according to the present disclosure;

[0027] Figure 4 (a) an appearance view and (b) an enlarged view of b-b' section that is a thickness direction section of the second state of the ground connection lead-out film according to the present disclosure; Figure 1 (a) an appearance view and (b) an enlarged view of b-b' section that is a thickness direction section of the second state of the ground connection lead-out film according to the present disclosure;

[0028] Figure 5 (a) an appearance view and (b) an enlarged view of b-b' section that is a thickness direction section of the second state of the ground connection lead-out film according to the present disclosure; Figure 1 ​​​​​A cross-sectional view of another embodiment of the shielded printed circuit board with the grounding connection lead-out membrane shown. Detailed Implementation

[0029] [Grounding connection lead-out membrane]

[0030] In this specification, "grounding connection lead-out film" refers to a film that can electrically connect the grounding circuit of a printed circuit board (PCB) to an external grounding potential at any location on the PCB, or a film that can connect the shielding layer of an electromagnetic wave shielding film to a grounding potential located outside the shielded PCB. Specifically, the film that can electrically connect the grounding circuit of a PCB to an external grounding potential can be listed as: a film that can connect the grounding part of the PCB to a grounding potential located outside the shielded PCB at any location within a shielded PCB with an electromagnetic wave shielding film laminated on it, or within a PCB with a conductive reinforcing plate laminated on it.

[0031] One embodiment of the above-mentioned grounding connection lead-out membrane is as follows: Figure 1 and Figure 2 As shown. Figure 1 (a) is an external view of a first embodiment of the grounding connection lead-out membrane of this disclosure. Figure 1 (b) is an enlarged view of section a-a', which is a section in the thickness direction. The grounding connection lead-out membrane 1 includes a metal layer 2 and an adhesive layer 3 laminated on one side 2b of the metal layer 2. The adhesive layer 3 may be laminated on only one side of the metal layer 2 or on both sides.

[0032] like Figure 1 As shown in (a) and (b), a plurality of openings 21 extending through the metal layer 2 in the thickness direction T are formed in the metal layer 2. Figure 1 As shown in (b), the shape of the cross-section in the thickness direction T of the opening 21 is a conical shape that extends away from the adhesive layer 3. This conical shape includes a first wide side D1 extending in the surface extension direction H and being relatively wide, and a second wide side D2 extending in the surface extension direction H and being relatively narrow. In the metal layer 2, the first wide side D1 is located on the metal surface (exposed metal surface) 2a opposite to the adhesive layer 3, and the second wide side D2 is located on the metal surface (adhesive layer lamination surface) 2b on the side of the adhesive layer 3. In the first configuration, a portion of the adhesive layer 3 does not penetrate into the opening 21, but a portion of the adhesive layer 3 can penetrate into the opening 21.

[0033] In this specification, "conical shape" refers to a shape in which the width continuously expands in one direction in a cross-sectional shape, or in a three-dimensional shape, the cross-sectional shape continuously expands in one direction, and is not limited to those in which the increase in expansion is constant. For example... Figure 1(b) The sides of the conical shape shown can also be curved. In addition, the cross-sectional shape of the opening 21 containing the first wide side D1 and the second wide side D2 is not limited to a conical shape. For example, shapes containing a conical shape such as a funnel shape and shapes containing a convex shape can be listed.

[0034] As a first-type grounding connection lead-out membrane 1, for example, by applying heat and pressure, the adhesive layer 3 flows and penetrates into the opening 21. Then, the adhesive layer 3 cures to a degree sufficient to hold the second wide side D2, forming an adhesive layer 3', which is then applied to... Figure 2 The grounding connection lead-out membrane 1' of the second form shown transitions. That is, the adhesive layer 3 preferably has the property of being fluid by heating and / or pressurizing, and the property of curing after flowing (specifically, the adhesive layer 3 is cured to the extent that it can sufficiently hold the second wide edge D2).

[0035] Figure 2 (a) is an external view of a second embodiment of the grounding connection lead-out membrane of this disclosure. Figure 2 (b) is an enlarged view of the b-b' section, which is a section in the thickness direction. For example... Figure 2 As shown in (a) and (b), in the grounding connection lead-out membrane 1', a portion of the adhesive constituting the adhesive layer 3' penetrates into each of the openings 21 of the metal layer 2. In the thickness direction T section, the interface of the adhesive layer 3' within the opening 21 is located on the adhesive layer 3' side (adhesive layer lamination surface 2b side) relative to the relatively wider first width side D1, and on the opposite side (metal layer exposed surface 2a side) relative to the relatively narrower second width side D2. That is, with the second width side D2 as a reference, the interface of the adhesive layer 3' within the opening 21 is located on the first width side D1 side (metal layer exposed surface 2a side, ...). Figure 2 (b) on the upper side), within the opening 21, the second wide side D2 is buried in the adhesive layer 3'.

[0036] In the second configuration, the grounding connection lead-out membrane 1' forms an opening 21 in the metal layer 2 that extends through the thickness direction T. Thus, when gas is generated in the adhesive layer 3' during heating, the gas can pass through the metal layer 2 via the opening 21, making it difficult for gas to accumulate between the metal layer 2 and the adhesive layer 3'.

[0037] Furthermore, in the second configuration, the second wide edge D2 is embedded in the adhesive layer 3' within the opening 21. Therefore, even when force is applied in the direction where the metal layer 2 and the adhesive layer 3' are to be peeled off, the adhesive within the opening 21 becomes stuck in the protrusion containing the second wide edge D2. Consequently, the adhesive within the opening 21 and the adhesive outside the opening 21, which is integrally formed with the adhesive within the opening 21, are difficult to peel off from the metal layer 2. Therefore, the adhesive layer 3' is difficult to peel off from the metal layer 2. Additionally, the interface of the adhesive layer 3' exists within the opening 21, and the adhesive layer 3 does not flow out from the exposed surface 2a of the metal layer. Therefore, when connecting the metal layer 2 to the housing of an electronic component, the resin component constituting the adhesive layer 3' does not obstruct contact between the housing and the metal layer 2. Furthermore, the interface of the adhesive layer 3' can also be exposed from the exposed surface 2a of the metal layer and cover a portion of the surface of the metal layer 2.

[0038] The interface of the adhesive layer 3' within the opening 21 is located between the first wide side D1 and the second wide side D2 in the thickness direction T of the metal layer 2. When the exposed surface 2a of the metal layer has a wider, tapered end and the interface of the adhesive layer 3' is located between the first wide side D1 and the second wide side D2, when solder is formed on the opening 21, the gap between the periphery of the solder bottom surface and the edge of the opening is small, making it difficult for voids to exist, and the wettability of the solder to the surface of the adhesive layer 3' is improved. From the viewpoint of being able to obtain a larger amount of adhesive within the opening 21 and to make the adhesive more fully adhered, the interface of the adhesive layer 3' within the opening 21 can also be located on the first wide side D1.

[0039] Figure 1 (b) or Figure 2 (b) shows a section T in the thickness direction, which is a circular section passing through the center and diameter of the opening 21 as viewed from the upper side of the metal layer 2. This is achieved by making the section passing through the center of the opening 21... Figure 1 (b) or Figure 2 The cross-section shown in (b) (i.e., the cross-section containing the first wide side D1 and the second wide side D2) allows the adhesive within the opening 21 to be fully held in place in the second configuration. Particularly preferred is a cross-section passing through the center of the opening 21 in all thickness directions T. Figure 1 (b) or Figure 2 The cross section shown in (b) is also possible. A cross section that does not pass through the center can also be... Figure 1 (b) or Figure 2 The cross-section shown in (b), particularly preferably the cross-section T in all thickness directions of the through portion of the opening 21, is as follows: Figure 1 (b) or Figure 2 (b) shows the cross section.

[0040] The cross-section of the opening 21 in the extending direction H is a tapered shape that continuously increases in size from the adhesive layer lamination surface 2b to the exposed metal layer surface 2a. By making it in this shape, the adhesive in the opening 21 can be more fully retained. In addition, the opening with the first wide side D1 and the second wide side D2 in the thickness direction T cross-section is easy to manufacture.

[0041] From the viewpoint that the adhesive in the opening 21 can be more fully held in place, it is preferable that the length difference between the first wide side D1 and the second wide side D2 in the cross section in the thickness direction T is greater than the thickness of the metal layer 2.

[0042] The preferred configurations of the grounding connection lead-out membranes 1 and 1', the metal layer 2, and the adhesive layers 3 and 3' are described in detail below. In this specification, the grounding connection lead-out membranes 1 and 1' are sometimes collectively referred to as "the grounding connection lead-out membrane group 1", and the adhesive layers 3 and 3' are collectively referred to as "the adhesive layers group 3".

[0043] (Metal layer)

[0044] A plurality of openings 21 are formed in the metal layer 2. Regarding the shape of the openings 21, their shape in the surface extension direction H (i.e.,...) Figure 1 The shape (viewed from the top side) can be circular, but also elliptical, racetrack-shaped, polygonal (e.g., triangle, quadrilateral, pentagon, hexagon, octagon, etc.), star-shaped, etc. Among these, a circular shape is preferred due to the ease of forming the opening. Furthermore, the plurality of openings 21 can all be the same shape, or they can be two or more different shapes.

[0045] The array pattern of the openings 21 is not particularly limited; for example, it can be a grid pattern, a Z-shape, a honeycomb structure, etc. In addition, the openings 21 can be arranged regularly or randomly.

[0046] The opening area of ​​the opening 21 (the area of ​​each opening) is not particularly limited, but the maximum area in the surface extension direction H is preferably 100 to 75000 μm. 2 More preferably, it is 500–35000 μm. 2 More preferably 1000–20000 μm 2 If the area of ​​the above opening is 100 μm 2 The above configuration results in even better gas permeability. If the opening area is 75000 μm... 2 The following grounding connection leads out with even better performance.

[0047] The opening ratio of the opening 21 is not particularly limited, but is preferably 0.5% to 40%, more preferably 2.0% to 30%, and even more preferably 4.0% to 25%. If the opening ratio is 0.5% or more, the gas permeability is better. If the opening ratio is 40% or less, the grounding connection lead-out performance is better.

[0048] The metal constituting the metal layer 2 can be, for example, gold, silver, copper, aluminum, nickel, tin, palladium, chromium, titanium, zinc, or alloys of the above metals. From the viewpoint of superior performance in grounding connection, copper or silver layers are preferred; from an economic point of view, copper is preferred.

[0049] The metal layer 2 can be a single layer or multiple layers (e.g., a layer with metal plating). However, when it is multiple layers, the opening 21 is provided in the same position so as to penetrate multiple metal layers 2.

[0050] The thickness of the metal layer 2 is preferably 0.5 to 12 μm, more preferably 1 to 6 μm. If the thickness is 0.5 μm or more, it includes an opening and has better grounding connection lead-out performance. If the thickness is 12 μm or less, it can ensure conformability to uneven substrates and allows for the design of smaller products including the grounding connection lead-out film.

[0051] (Adhesive layer)

[0052] The adhesive layer group 3 serves, for example, to provide adhesion for bonding the grounding connection lead-out film group 1 to the shielded printed circuit board. The adhesive layer group 3 can be a single layer or multiple layers. The adhesive layer group 3 preferably contains an adhesive component. Only one adhesive component can be used, or two or more can be used.

[0053] The adhesive components mentioned above can include thermoplastic resins, thermosetting resins, and active energy radiation-cured compounds. Examples of thermoplastic resins include polystyrene resins, vinyl acetate resins, polyester resins, polyolefin resins (such as polyethylene resins, polypropylene resin compositions, etc.), polyimide resins, and acrylic resins. Only one type of thermoplastic resin may be used, or two or more types may be used.

[0054] The thermosetting resins mentioned above can include both thermosetting resins and resins obtained by curing the aforementioned thermosetting resins. Examples of thermosetting resins include phenolic resins, epoxy resins, polyurethane resins, melamine resins, and alkyd resins. Only one type of thermosetting resin may be used, or two or more types may be used.

[0055] Examples of epoxy resins mentioned above include bisphenol type epoxy resins, spirocyclic type epoxy resins, naphthalene type epoxy resins, biphenyl type epoxy resins, terpene type epoxy resins, glycidyl ether type epoxy resins, glycidyl amine type epoxy resins, and (linear) phenolic type epoxy resins.

[0056] Examples of bisphenol-type epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, and tetrabromobisphenol A type epoxy resin. Examples of glycidyl ether-type epoxy resins include tris(glycidyl etheroxyphenyl)methane and tetra(glycidyl etheroxyphenyl)ethane. Examples of glycidylamine-type epoxy resins include tetraglycidyl diaminodiphenylmethane. Examples of (linear) phenolic-type epoxy resins include cresol (linear) phenolic-type epoxy resin, phenol (linear) phenolic-type epoxy resin, α-naphthol (linear) phenolic-type epoxy resin, and brominated phenol (linear) phenolic-type epoxy resin.

[0057] The aforementioned active energy ray-curable compounds can include both compounds that can be cured by irradiation with active energy rays (active energy ray-curable compounds) and compounds obtained by curing the aforementioned active energy ray-curable compounds. There are no particular limitations on the active energy ray-curable compounds; for example, polymeric compounds containing one or more (preferably two or more) free radical reactive groups (e.g., ((meth)acryloyl) groups) in their molecules can be listed. Only one of the aforementioned active energy ray-curable compounds may be used, or two or more may be used.

[0058] Preferably, the adhesive component is a thermosetting resin. When the grounding connection lead-out membrane 1 is placed on the printed circuit board, shielded printed circuit board, or other objects to be bonded, the adhesive component can be cured by applying pressure and heat, resulting in good adhesion of the bonded portion. For example, when the adhesive component in the adhesive layer 3 is a thermosetting resin, the adhesive component in the adhesive layer 3' is a thermosetting resin obtained by curing the aforementioned thermosetting resin.

[0059] When the adhesive composition includes a thermosetting resin, a curing agent for promoting the thermosetting reaction may be included as a component of the adhesive composition. The curing agent can be appropriately selected according to the type of thermosetting resin. Only one type of curing agent may be used, or two or more types may be used.

[0060] The adhesive layer group 3 can be conductive. When conductive, the grounding connection performance is improved. When conductive, the adhesive layer group 3 preferably includes conductive particles. Only one type of conductive particle can be used, or two or more types can be used.

[0061] Examples of conductive particles include metal particles, metal-coated resin particles, metal fibers, carbon-based fillers, and carbon nanotubes.

[0062] Examples of metals constituting the metal particles and the coating portion of the metal-coated resin particles include gold, silver, copper, nickel, zinc, indium, tin, lead, bismuth, and alloys of two or more of the above. Only one of the metals may be used, or two or more may be used.

[0063] Specifically, the aforementioned metal particles can include, for example, copper particles, silver particles, nickel particles, silver-plated copper particles, indium particles, tin particles, lead particles, bismuth particles, gold-plated copper particles, silver-plated nickel particles, gold-plated nickel particles, indium-plated copper particles, tin-plated copper particles, lead-plated copper particles, bismuth-plated copper particles, indium-plated nickel particles, tin-plated nickel particles, bismuth-plated nickel particles, and silver-plated alloy particles. The aforementioned silver-plated alloy particles can include, for example, silver-plated copper alloy particles made by coating copper-containing alloy particles (e.g., copper alloy particles composed of an alloy of copper, nickel, and zinc) with silver. These metal particles can be produced by electrolysis, atomization, reduction, or other methods.

[0064] Among these, silver particles, silver-coated copper particles, and silver-coated copper alloy particles are preferred. From the viewpoints of superior conductivity, inhibition of oxidation and condensation of metal particles, and reduction of metal particle cost, silver-coated copper particles and silver-coated copper alloy particles are particularly preferred.

[0065] Specifically, the aforementioned metal-coated resin particles can include silver-coated resin particles, gold-coated resin particles, indium-coated resin particles, tin-coated resin particles, lead-coated resin particles, bismuth-coated resin particles, etc.

[0066] The shapes of the aforementioned conductive particles can be listed as spherical, flake-like (scale-like), dendritic, fibrous, amorphous (polyhedral), etc.

[0067] The median diameter (D50) of the aforementioned conductive particles is preferably 1 to 50 μm, more preferably 3 to 40 μm. If the median diameter is 1 μm or more, the conductive particles have good dispersibility, can suppress agglomeration, and are difficult to oxidize. If the average particle size is 50 μm or less, the conductivity is good.

[0068] When the adhesive layer group 3 is conductive, it can be made into a layer with isotropic conductivity or anisotropic conductivity as needed.

[0069] When the adhesive layer 3 group is conductive, the content ratio of conductive particles is not particularly limited, but is preferably 2 to 95% by mass relative to 100% of the total adhesive layer, more preferably 5 to 80% by mass, and even more preferably 10 to 70% by mass. If the above content ratio is 2% by mass or more, the conductivity is better. If the above content ratio is 95% by mass or less, it can sufficiently contain adhesive components, resulting in better tight adhesion to the bonded objects.

[0070] To the extent that the purpose and effects of this disclosure are not impaired, adhesive layer group 3 may contain other components besides those described above. Examples of these other components include those commonly found in adhesive layers. Examples of these other components include curing accelerators, plasticizers, flame retardants, defoamers, viscosity modifiers, antioxidants, diluents, anti-settling agents, fillers, colorants, leveling agents, coupling agents, UV absorbers, tackifying resins, and anti-blocking agents. Only one of these other components may be used, or two or more may be used.

[0071] The thickness of the adhesive layer 3 group is preferably 3 to 20 μm, more preferably 5 to 15 μm. If the thickness is 3 μm or more, the bonding force to the bonded objects is better. If the thickness is 20 μm or less, the cost can be controlled, and the product including the grounding connection lead-out membrane can be designed to be smaller. The thickness of the adhesive layer 3' in cases where the adhesive layer 3 flows and penetrates into the opening 21 is the thickness of the adhesive layer in the non-penetrated area.

[0072] right Figure 1 and Figure 2 The manufacturing method of the grounding connection lead-out membrane group 1 shown will be described. Figure 1 In the manufacturing process of the grounding connection lead-out membrane 1 shown, the adhesive layer 3 is first formed, for example, as follows: the adhesive layer 3 is formed by coating (applying) an adhesive composition onto a temporary substrate such as a release film or a metal layer 2, and, as needed, is desolvated and / or partially cured.

[0073] In addition to the components contained in adhesive layer 3, the adhesive composition described above also includes a solvent. Examples of solvents include toluene, acetone, methyl ethyl ketone, methanol, ethanol, propanol, and dimethylformamide. The concentration of the solid components in the adhesive composition is appropriately set according to the thickness of the adhesive layer to be formed.

[0074] The above-mentioned adhesive composition can be coated using well-known coating methods. For example, a gravure roller coater, a reverse roller coater, an oiling roller coater, a lip coater, an immersion roller coater, a doctor blade coater, a knife coater, a sprayer, a comma coater, a direct coater, a slot coater, and other coating machines can be used.

[0075] When an adhesive layer 3 is formed on a temporary substrate, a metal layer 2 with pre-formed openings 21 is then deposited onto the surface of the adhesive layer 3 formed on the temporary substrate. The openings 21 can be formed by well-known and commonly used methods such as punching or laser irradiation on the metal plate (or metal layer). Alternatively, when the metal plate is made of an etchable material such as copper, a resist pattern for forming the openings 21 can be applied to the surface of the metal plate, and the openings 21 can be formed by etching. Alternatively, a conductive paste, which functions as a plating catalyst, can be printed onto the surface of the metal plate. In this printing process, the openings 21 can be formed by printing in a predetermined pattern. When printing the paste that functions as a plating catalyst, after printing the paste and forming the openings 21, a metal film can be formed by chemical plating or electroplating, thereby forming the metal layer 2. Alternatively, conductive paste or paste that functions as a plating catalyst can be printed onto the surface of the adhesive layer 3 formed on the temporary substrate to form the desired pattern, and then a metal film can be formed by chemical plating or electroplating, thereby forming the metal layer 2.

[0076] Then, the film on which the metal layer 2 is laminated on the adhesive layer 3 is subjected to heating and pressure treatment (hot pressing), thereby allowing a portion of the adhesive constituting the adhesive layer 3 to penetrate into the opening 21 of the metal layer 2. Alternatively, the adhesive layer 3 of the ground connection lead-out film 1 is bonded to the printed circuit board as an attachment surface, and then hot pressing is performed. This allows the ground connection lead-out film 1 to be bonded to the printed circuit board. For example, the adhesive layer 3' can also be formed through this hot pressing, while a portion of the adhesive constituting the adhesive layer 3' penetrates into the opening 21, thus creating the ground connection lead-out film 1'. The temperature during the hot pressing is preferably 100–200°C, more preferably 120–190°C, and even more preferably 140–180°C. The pressure, based on the specific pressure on the printed circuit board, is preferably 0.5–10 MPa, more preferably 1–8 MPa, and even more preferably 2–6 MPa. The time is preferably 1 minute or more, more preferably 2 minutes or more, and even more preferably 3 minutes or more. In this way, grounding connection lead-out membrane 1 can be manufactured.

[0077] As described above, the grounding connection lead-out film of this disclosure can be used to release electromagnetic waves that intrude into or are generated within a printed circuit board or shielded printed circuit board to the outside. Hereinafter, an example is given of applying the grounding connection lead-out film 1 to a shielded printed circuit board. Figures 3-5 In the illustration, the opening 21 formed in the metal layer 2 is omitted.

[0078] [Shielded Printed Circuit Board]

[0079] like Figure 3As shown, the shielded printed circuit board 5a, as the first form of the shielded printed circuit board, includes: a printed circuit board 6, a shielding laminate 7 formed by an electromagnetic wave shielding film, and a grounding connection lead-out film 1' located between the printed circuit board 6 and the shielding laminate 7.

[0080] The printed circuit board 6 includes: a base component 61, a circuit pattern 62 partially disposed on the surface of the base component 61, an insulating protective layer (cover film) 63 covering the circuit pattern 62 and providing insulation protection, and an adhesive layer 64 covering the circuit pattern 62 and bonding the circuit pattern 62, the base component 61, and the insulating protective layer 63. The circuit pattern 62 includes a plurality of signal circuits 62a and a ground circuit 62b. For the purpose of ensuring conductivity with the conductive adhesive layer 71 of the shielding laminate 7, through-holes are formed in the adhesive layer 64 and the insulating protective layer 63 on the ground circuit 62b.

[0081] In the shielding laminate 7, a conductive adhesive layer 71 and an insulating layer 72 are stacked and disposed on the printed circuit board 6 via the conductive adhesive layer 71. The shielding laminate 7 can be formed by thermoforming after the electromagnetic wave shielding film is attached to the printed circuit board 6. Through the above-mentioned thermoforming, the conductive adhesive layer in the electromagnetic wave shielding film flows and fills the through-holes provided in the grounding circuit 62b due to heating and pressurization, allowing the grounding circuit 62b and the conductive adhesive layer 71 to conduct.

[0082] In the shielded printed circuit board 5a, a portion of the ground connection lead-out film 1' is disposed between the printed circuit board 6 and the shielding laminate 7. The conductive adhesive layer 71 of the shielding laminate 7 and the metal layer 2 of the ground connection lead-out film 1' are bonded and electrically connected. Another portion of the ground connection lead-out film 1' is placed on the printed circuit board 6 on one side and exposed on the other. This exposed area functions as an external conductive layer, electrically connected to an external grounding component. Thus, the grounding circuit 62b of the printed circuit board 6 and the grounding potential located outside the shielded printed circuit board 5a can be connected. The ground connection lead-out film 1 is bonded to the printed circuit board 6 with the adhesive layer 3 as the bonding surface, and then the ground connection lead-out film 1' can be formed by thermoforming. Through the thermoforming, the adhesive layer 3 flows and fills the through-holes in the grounding circuit 62b due to heating and pressure. When the adhesive layer 3 is conductive, the grounding circuit 62b and the adhesive layer 3' can be made conductive.

[0083] As Figure 3 The modified example of the shielded printed circuit board 5a shown includes a printed circuit board 6, a conductive reinforcing member, and a grounding connection lead-out film 1' located inside the conductive adhesive layer of the conductive reinforcing member, but does not include an electromagnetic wave shielding layer. (Refer to...) Figure 3The structure of the printed circuit board described above is explained. The conductive reinforcing member includes a conductive substrate and a conductive adhesive layer disposed on one side of the conductive substrate. The conductive adhesive layer of the conductive reinforcing member is attached to a grounding circuit 62b on the printed circuit board 6, and a portion of the conductive adhesive layer fills a through-hole in the grounding circuit 62b. A portion of the grounding connection lead-out film 1' is configured to be located inside the conductive adhesive layer of the conductive reinforcing member and between the conductive substrate and the printed circuit board 6, and the conductive adhesive layer of the conductive reinforcing member is electrically connected to the metal layer 2 of the grounding connection lead-out film 1'. Regarding another portion of the grounding connection lead-out film 1', one side is mounted on the printed circuit board 6, and a portion of the other side is exposed. The exposed area functions as an external conductive layer, and is electrically connected to an external grounding member in the exposed portion. Therefore, the conductive adhesive layer in the conductive reinforcing member and the metal layer 2 of the ground connection lead-out film 1' can connect the ground circuit 62b of the printed circuit board 6 to the external ground potential.

[0084] Figure 4 The diagram illustrates other embodiments of a shielded printed circuit board that utilizes a grounding connection lead-out membrane. For example... Figure 4 As shown, the shielded printed circuit board 5b, as a second type of shielded printed circuit board, includes: a printed circuit board 6, a shielding laminate 7 disposed on the printed circuit board 6, and a grounding connection lead-out film 1' disposed on the shielding laminate 7. The adhesive layer 3' of the grounding connection lead-out film 1' contains conductive particles 31, which penetrate the insulating layer 72 of the shielding laminate 7 and are in contact with the conductive adhesive layer 71. The conductive particles 31 are also in contact with the metal layer 2. With the above structure, the shielding laminate 7 and the grounding connection lead-out film 1' are connected via the conductive particles 31, and the metal layer 2 functions as an external conductive layer, with its surface electrically connected to an external grounding component. Thus, the grounding circuit 62b of the printed circuit board 6 and the grounding potential located outside the shielded printed circuit board 5b can be connected. The grounding connection lead-out film 1' can be formed as follows: with the adhesive layer 3 as the bonding surface, the grounding connection lead-out film 1 is attached to the electromagnetic wave shielding laminate 7 in the shielded printed circuit board, and then conductive particles 31 penetrate the insulating layer 72 through heat pressing, thereby bonding the adhesive layer 3 to the shielding laminate 7. The shielded printed circuit board before the grounding connection lead-out film 1' is provided can be manufactured in the same manner as described in the manufacturing method of the shielded printed circuit board 5a.

[0085] Figure 5 The diagram illustrates another embodiment of a shielded printed circuit board using a grounding connection lead-out film. For example... Figure 5As shown, the shielded printed circuit board 5c, as a third type of shielded printed circuit board, includes: a printed circuit board 6', a shielding laminate 8 disposed on the printed circuit board 6', and a grounding connection lead-out film 1' disposed on the shielding laminate 8. In the printed circuit board 6', the circuit pattern 62 is composed of a plurality of signal circuits 62a, does not contain a grounding circuit 62b, and does not form through holes, but is otherwise the same as the printed circuit board 6. Figure 5 The circuit diagram 62 is illustrated in a form that does not include the grounding circuit 62b, but it may also include the grounding circuit 62b.

[0086] In the shielding laminate 8, a non-conductive adhesive layer 81, an electromagnetic wave shielding layer 82 made of conductor, and an insulating layer 83 are sequentially stacked and disposed on the printed circuit board 6' through the adhesive layer 81. The shielding laminate 8 can be formed by attaching the electromagnetic wave shielding film to the printed circuit board 6' and then performing heat bonding as needed.

[0087] The adhesive layer 3' of the grounding connection lead-out film 1' contains conductive particles 31. The conductive particles 31 penetrate the insulating layer 83 of the shielding laminate 8 and contact the electromagnetic wave shielding layer 82. The conductive particles 31 also contact the metal layer 2. With the above structure, the electromagnetic wave shielding layer 82 and the grounding connection lead-out film 1' are connected via the conductive particles 31. The metal layer 2 functions as an external conductive layer, and its surface is electrically connected to an external grounding component. Thus, the electromagnetic wave shielding layer 82 of the shielding laminate 8 and the grounding potential located outside the shielded printed circuit board 5c can be connected, and the electromagnetic wave shielding layer 82 performs its electromagnetic wave shielding function. The grounding connection lead-out film 1' can be formed as follows: with the adhesive layer 3 as the bonding surface, the grounding connection lead-out film 1 is adhered to the electromagnetic wave shielding laminate 8 in the shielded printed circuit board, and then the conductive particles 31 penetrate the insulating layer 83 and the adhesive layer 3 is bonded to the shielding laminate 8 by thermoforming. The shielded printed circuit board before the grounding connection lead-out membrane 1' can be manufactured in the same way as described in the method for manufacturing the shielded printed circuit board 5a.

[0088] 1, 1' Grounding connection lead-out membrane

[0089] 2 Metal layer

[0090] 2a Exposed surface of metal layer

[0091] 2b Adhesive layer stacking

[0092] 21. Opening

[0093] 3,3' Adhesive layer

[0094] D1 First wide side

[0095] D2 Second Wide Side

Claims

1. A grounding connection lead-out membrane, characterized in that: The grounding connection lead-out membrane includes a metal layer and an adhesive layer disposed on one side of the metal layer. An opening penetrating the metal layer in the thickness direction is formed in the metal layer. The opening has a cross-section in the thickness direction containing a first wide side and a second wide side. The first wide side and the second wide side extend in the surface extension direction, and the second wide side is narrower than the first wide side. With the first wide side as a reference, the adhesive layer is laminated on the metal layer on the side of the second wide side. A portion of the adhesive layer is capable of penetrating or has penetrated into the opening. With a portion of the adhesive layer already penetrating the opening, the second wide edge is buried within the adhesive layer that has penetrated the opening. The first wide side is located on the metal layer opposite to the adhesive layer.

2. The grounding connection lead-out membrane according to claim 1, characterized in that: The opening, in the thickness direction section, has a tapered shape including the first wide side and the second wide side and extending in a direction away from the adhesive layer.

3. The grounding connection lead-out membrane according to claim 1, characterized in that: The second wide side is located on the metal layer on the side of the adhesive layer.

4. The grounding connection lead-out membrane according to claim 1, characterized in that: The thickness-direction cross section is a tapered shape that includes the first wide side and the second wide side and extends in a direction away from the adhesive layer.

5. The grounding connection lead-out membrane according to claim 1, characterized in that: The opening includes a tapered shape that extends in a direction away from the adhesive layer.

6. The grounding connection lead-out membrane according to claim 1, characterized in that: The length difference between the first wide side and the second wide side is greater than the thickness of the metal layer.

7. The grounding connection lead-out membrane according to any one of claims 1 to 6, characterized in that: The grounding connection lead-out membrane has a plurality of openings, and the opening ratio of the openings is 0.5 to 40%.

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