TW202130262A - Electromagnetic wave shielding sheet and electromagnetic wave shielding wiring circuit board - Google Patents

Abstract

Provided are an electromagnetic wave shielding sheet having high cleaning resistance, circuit connection stability, excellent folding resistance, and good insulating properties; and an electromagnetic wave shielding wiring circuit board using the electromagnetic wave shielding sheet. The electromagnetic wave shielding sheet has a laminate comprising an adhesive layer, a metal layer, and a protective layer in this order, and in the surface of the metal layer in contact with the adhesive layer, the 60-degree specular gloss, as solved according to ISO 7668, is 0-500, and X represented by formula (1) is less than 1.0. Rz is the maximum height roughness of the metal layer solved according to JIS B0601, and T is the thickness of the protective layer. Formula (1) X = Rz/T.

Description

Electromagnetic wave shielding sheet and electromagnetic wave shielding wiring circuit board

The present invention relates to an electromagnetic wave shielding sheet and an electromagnetic wave shielding wiring circuit board. For example, it relates to an electromagnetic wave shielding sheet suitable for use in joining with a part of a part that emits electromagnetic waves and uses an electromagnetic wave shielding sheet The electromagnetic wave shielding wiring circuit board.

Wiring circuit boards (also called "wiring boards") such as printed wiring boards (also called "wiring boards") are built into various electronic devices represented by mobile terminals, personal computers (PC), servers, etc. . In order to prevent malfunctions caused by external magnetic fields or electric waves, and to reduce unnecessary radiation from electrical signals, electromagnetic wave shielding structures are provided on these wiring circuit boards.

With the high-speed transmission of transmission signals, electromagnetic wave shielding sheets are also required to have electromagnetic wave shielding properties against high-frequency noise (hereinafter, high-frequency shielding properties) and reduce transmission loss in the high-frequency range (hereinafter, sometimes referred to as transmission characteristics) . Patent Document 1 (International Publication No. 2013/077108) discloses a structure including a metal layer having a thickness of 0.5 μm to 12 μm and an anisotropic conductive adhesive layer in a laminated state. It is also described that according to this structure, electric field waves, magnetic field waves, and electromagnetic waves traveling from one side to the other side of the electromagnetic wave shielding sheet are well shielded, and transmission loss is reduced.

[The problem to be solved by the invention] In recent years, in electronic devices represented by mobile phones, with the high-speed transmission of transmission signals, the electromagnetic wave shielding sheet on the wiring circuit board built in them is also required to have high-frequency shielding properties. Therefore, it has been considered suitable to use a metal layer having a thickness of 0.5 μm to 12 μm as described in Patent Document 1 for the conductive layer of the electromagnetic wave shielding sheet. However, only by using a metal layer with a thickness of 0.5 μm to 12 μm, the electromagnetic wave shielding sheet cannot exhibit sufficient high-frequency shielding performance in the high-frequency band. In order to make the electromagnetic wave shielding sheet have more excellent high-frequency shielding performance, it is required to The metal layer is further designed.

In addition, in the mounting step of the electronic device, the electromagnetic wave shielding printed circuit board may be exposed to the cleaning step for the main purpose of removing dirt, garbage, and the like. In order to remove all dirt, garbage, etc. attached to the electromagnetic wave shielding wiring circuit board, a variety of water-based, oily, acidic, or alkaline chemicals are used in the cleaning step. At this time, there is a problem that the electromagnetic wave shielding layer has insufficient resistance to decomposition and solubility with respect to cleaning chemicals, and the electromagnetic wave shielding layer is damaged.

With the popularity of electronic devices such as smart phones and tablet terminals worldwide in recent years, reliability under a wide range of temperature and humidity conditions is required. The wiring circuit board including the electromagnetic wave shielding sheet of Patent Document 1 has the following problems when exposed to a high temperature and high humidity environment: water absorption due to the softening of the electromagnetic wave shielding sheet occurs, and the distance between the metal layer and the circuit becomes longer due to swelling Wait, the connection to the ground circuit is interrupted (hereinafter, circuit connection stability). In Patent Document 2 (Japanese Patent Laid-Open No. 2019-121731), the surface of the adhesive layer side in the shielding layer of the electromagnetic wave shielding film (equivalent to the electromagnetic wave shielding sheet) will be in accordance with the Japanese Industrial Standards (Japanese Industrial Standards). , JIS) B 0601:2013 The average length Rsm of the roughness curve elements is adjusted to a certain range, thereby making the grounding wiring and the shielding layer provided on the printed circuit board good grounding.

The thicker the metal layer of the electromagnetic wave shielding sheet, the higher the shielding performance, and on the other hand, the higher the rebound force. Therefore, when a shielding printed wiring board formed by attaching an electromagnetic wave shielding sheet to a printed wiring board is assembled into a frame, there are problems such as cracks in the bent portion, poor appearance, poor insulation, and noise leakage.

In addition, in order to prevent the connection between the shielding layer and the ground wiring, the electromagnetic wave shielding sheet generally includes an insulating protective layer on one side of the shielding layer. In the case where the insulation of the protective layer is not high enough, or when the steep unevenness of the shielding layer penetrates the protective layer due to hot pressing, the shielding layer may be generated when the protective layer of the electromagnetic wave shielding layer comes into contact with a member other than the ground wiring -Problems with electrical connections other than the grounding wiring closet.

The present invention was completed in view of the above background, and its object is to provide an electromagnetic wave shielding sheet having high cleaning resistance, circuit connection stability, excellent folding resistance, and good insulation, and an electromagnetic wave shielding sheet using the electromagnetic wave shielding sheet Wiring circuit board. [Technical means to solve the problem]

The inventors conducted active studies and found that the problems of the present invention can be solved in the following embodiments, thereby completing the present invention. That is, the electromagnetic wave shielding sheet of the present invention is characterized in that it has a laminated body including an adhesive layer, a metal layer, and a protective layer in this order. The 60° specular gloss determined by the International Organization for Standardization (ISO) 7668 is 0 to 500, and X represented by the formula (1) is less than 1.0. Formula 1) X=Rz/T (Rz is the maximum height roughness of the metal layer determined in accordance with JIS B0601, and T is the thickness of the protective layer.) The electromagnetic wave shielding printed circuit board of the present invention is characterized by including an electromagnetic wave shielding layer formed of the electromagnetic wave shielding sheet, a top coat, and a wiring board having signal wiring and an insulating base material. [Effects of the invention]

According to the present invention, it is possible to provide an electromagnetic wave shielding sheet having high cleaning resistance, circuit connection stability, excellent folding resistance, and good insulation, and using the electromagnetic wave shielding sheet The wiring circuit board.

Hereinafter, an example of an embodiment to which the present invention is applied will be described. In addition, the size or ratio of each member in the following figures is for convenience of description, and is not limited to this. In addition, in this specification, the description of "arbitrary number A to arbitrary number B" means that the number A is included as a lower limit and the number B is included as an upper limit in the above-mentioned range. In addition, the "sheet" in this specification includes not only the "sheet" defined in JIS, but also the "film". In addition, the numerical value specified in this specification is the value calculated|required by the method disclosed in embodiment or an Example.

＜Electromagnetic wave shielding sheet＞ The electromagnetic wave shielding sheet of the present invention has a laminate including at least an adhesive layer, a metal layer, and a protective layer in this order. FIG. 1 is a cross-sectional view illustrating the electromagnetic wave shielding sheet 10 of this embodiment. As shown in FIG. 1, the electromagnetic wave shielding sheet 10 has a laminated body including an adhesive layer 1, a metal layer 2 and a protective layer 3 in this order. The metal layer 2 is disposed between the adhesive layer 1 and the protective layer 3. That is, the electromagnetic wave shielding sheet of the present embodiment has a laminate including an adhesive layer, a metal layer, and a protective layer in this order, and the surface of the metal layer in contact with the adhesive layer is determined in accordance with ISO 7668. The 60° specular gloss is 0 to 500, and the maximum height roughness Rz calculated in accordance with JIS B0601 and the thickness T of the protective layer of the surface of the metal layer in contact with the adhesive layer is used. And X represented by formula (1) is less than 1.0, so it can exhibit high cleaning resistance, circuit connection stability, excellent folding resistance, good insulation, and the like. For the electromagnetic wave shielding sheet 10, for example, a surface on the adhesive layer 1 side and a printed circuit board (also referred to as a "wiring board") as an adherend are bonded to form an electromagnetic wave shielding layer, and an electromagnetic wave shielding printed circuit board is produced. That is, of the surface of the metal layer 2, the surface facing the signal wiring or the ground wiring in the printed circuit board is the surface in close contact with the adhesive layer 1.

"Metal Layer" The metal layer of the present invention has a function of imparting high-frequency shielding properties to the electromagnetic wave shielding sheet. The surface of the metal layer on the side in contact with the adhesive layer is characterized in that the 60° specular gloss determined in accordance with ISO 7668 is 0 to 500, and X represented by the formula (1) is less than 1.0. Formula 1) X=Rz/T (Rz is the maximum height roughness of the surface of the metal layer (metal layer in contact with the adhesive layer) determined in accordance with JIS B0601, and T is the thickness of the protective layer.) The details of the 60° specular gloss, Rz, and the effects obtained by controlling them will be described later.

[60°mirror gloss] The 60° specular gloss is a parameter standardized in ISO 7668, which represents the degree of gloss on the surface of the measured object. Specular gloss can be measured by irradiating light (incident light) on the surface of the object to be measured at a certain incident angle, detecting the reflected light (specular reflection light) at a certain angle with a detector, and digitizing it. The incident light irradiated to the surface of the object to be measured is reflected, transmitted, or absorbed when it reaches the surface of the object to be measured. In addition, there are specular reflection and diffuse reflection in reflection, and light reflected at the same angle (reflection angle) as the incident angle is specular reflection light and is the light detected in the specular gloss measurement. The 60° specular gloss is the value measured when the incident angle and reflection angle are 60°. When the surface of the measurement object is a metal layer, most of the incident light will be reflected. The ratio of the reflected light to specular reflection and diffuse reflection is determined by the roughness of the surface of the metal layer. Fig. 2(i) and Fig. 2(ii) show cross-sectional views of two types of measurement target surfaces with different roughnesses. As shown in (i) of FIG. 2, on the surface of the measurement target with low roughness, the proportion of specular reflection light is large, while diffuse reflection light decreases, and the value of specular gloss increases. On the other hand, as shown in (ii) of FIG. 2, the ratio of specular reflection light is small on the surface of the measurement target with a large degree of roughness. On the other hand, the diffuse reflection light increases, and the value of the specular gloss decreases. That is, the mirror gloss can be used as an index for estimating the roughness of the surface of the measurement object.

The inventors of the present invention have conducted diligent studies and found that by setting the 60° specular gloss of the metal layer to 0 to 500, the cleaning resistance of the electromagnetic wave shielding sheet and the stability of the circuit connection are improved as a result. The 60° specular gloss of the metal layer is 0 to 500, which means that the surface of the metal layer has sufficient roughness to form irregularities. The adhesive layer included on the surface of the metal layer in this state enters the unevenness of the surface of the metal layer with a high degree of roughness, so that the adhesion between the metal layer and the adhesive layer becomes firm. Therefore, even when the electromagnetic wave shielding sheet and the electromagnetic wave shielding printed circuit board are exposed to the cleaning chemical, the chemical does not flow into the interface between the metal layer and the adhesive layer, and the disadvantage of interlayer peeling can be suppressed. happen. In addition, since no chemicals flow between the metal layer and the adhesive layer, especially when the cleaning chemicals have acid or alkalinity, the discoloration and corrosion of the metal layer can be suppressed. As a result, the present invention particularly exhibits excellent cleaning resistance.

In addition, by setting the 60° specular gloss of the metal layer to 0 to 500, when the adhesive layer is laminated on the metal layer, a structure in which the convex portion of the metal layer penetrates the adhesive layer can be formed. The electromagnetic wave shielding printed circuit board produced by laminating the electromagnetic wave shielding sheet with the above structure on the printed circuit board can maintain the convexity of the metal layer even if the adhesive layer swells when exposed to a high temperature and high humidity environment. The contact of the grounding circuit can realize the stable circuit connection.

According to the above, the 60° specular gloss of the metal layer is preferably 0 to 300, more preferably 0 to 100, still more preferably 0 to 50, and particularly preferably 0 to 10.

In addition, with regard to the mechanism that brings about the effect of the invention, the mechanism described above is accompanied by inference, and the mechanism that exhibits the effect is not limited in any way.

[Rz of metal layer] The maximum height roughness Rz is a parameter stipulated by JIS B0601, which represents the distance from the highest point to the lowest point of the measurement surface.

In the electromagnetic wave shielding sheet of the present invention, the value X expressed by the formula (1) is formed by the maximum height roughness Rz (μm) of the surface of the metal layer in contact with the adhesive layer and the thickness T (μm) of the protective layer It is less than 1.0, more preferably less than 0.97. When X is less than 1.0, the insulation of the outermost layer of the electromagnetic wave shielding layer is improved. As shown in Figure 5(a), when X is 1.0 or more, the thickness T of the protective layer is smaller than the maximum height and roughness Rz of the metal layer, so the unevenness of the metal layer penetrates the protective layer, resulting in the metal layer and the ground wiring The parts other than that are turned on. On the other hand, as shown in Figure 5(b), when X is less than 1.0, the thickness T of the protective layer is greater than the maximum height roughness Rz of the metal layer, so the unevenness of the metal layer does not penetrate the protective layer, and electromagnetic waves The insulation of the outermost surface of the shielding layer is improved. Formula 1) X=Rz/T (Rz is the maximum height roughness of the metal layer determined in accordance with JIS B0601, and T is the thickness of the protective layer.)

Regarding the factor that X becomes 1.0 or more, for example, it is conceivable that the height of the unevenness of the surface of the metal layer contacting the protective layer is greater than the thickness of the protective layer; when the protective layer is formed by coating or the like, coating defects occur, and the In the case where a metal layer is formed on the protective layer by plating or the like, and the metal layer is formed along the shape of the defect, etc. For example, the coating defect may occur when a resin composition added with particles having an average particle diameter larger than the thickness of the protective layer is applied. An example where X becomes a factor of 1.0 or more is the case listed above.

[60° mirror gloss and Rz control method] The method of controlling the 60° specular gloss and Rz of the metal layer surface includes, for example, forming a protective layer with irregularities from a resin composition containing particles, and then forming a metal layer on the protective layer by plating or sputtering. Method; After spreading particles on a protective layer formed of a resin composition, a method of forming a metal layer by plating or sputtering; sandblasting, plasma irradiation, electron beam treatment, chemical liquids on the surface of the protective layer After processing or embossing to form unevenness, a method of forming a metal layer on the protective layer by plating or sputtering, etc.; a method of attaching roughened particles to the surface of a metal foil to form a roughened surface; using a Japanese patent The method of polishing a metal surface with a buff described in Bulletin No. 2017-13473; a method of polishing a metal surface with a cloth paper; and a metal layer formed on a carrier with desired unevenness by plating or other methods. A method of transferring the unevenness of a carrier material; a shotblast method in which an abrasive material is blown onto a metal surface with compressed air; a method of pressing a mold with desired unevenness against a metal foil to transfer the uneven shape. The method of controlling the 60° specular gloss and Rz of the metal layer surface is not limited to the exemplified method, and a conventionally known method can be applied.

[The thickness of the metal layer] The thickness of the metal layer is preferably 0.3 μm to 10 μm. The thickness of the metal layer is 0.3 μm to 10 μm, which can balance circuit connection stability and folding resistance. When the thickness of the metal layer is 0.3 μm or more, the metal layer is not easily broken when pressed in by the non-conductive particles in the protective layer during hot pressing, and the circuit connection stability is improved. The press-in effect of non-conductive particles will be described later. In addition, when the thickness of the metal layer is 10 μm or less, cracks are less likely to occur in the metal layer during bending, and the bending resistance is improved. The thickness of the metal layer is more preferably 0.5 μm to 5 μm.

[Composition of the metal layer] For the metal layer, for example, a metal foil, a metal vapor-deposited film, a metal-plated film, etc. can be used. The metal used in the metal foil is preferably, for example, a conductive metal such as aluminum, copper, silver, gold, and the like, and one type of metal or an alloy of multiple types of metals may be used. In terms of high-frequency shielding properties and cost, copper, silver, and aluminum are more preferable, and copper is still more preferable. For copper, for example, rolled copper foil or electrolytic copper foil is preferably used. As the metal used in the metal vapor-deposition film and the metal-plated film, for example, an alloy of one or more metals of conductive metals such as aluminum, copper, silver, and gold is preferably used, and copper and silver are more preferable. One or both surfaces of metal foil, metal vapor-deposited film, and metal-plated film can be coated with metal or organic matter such as rust inhibitor.

[Opening] The metal layer may have a plurality of openings. By having an opening, the reflow resistance is improved. By having an opening, when the electromagnetic wave shielding printed circuit board is reflowed, the volatile components contained in the polyimide film or cover layer adhesive of the printed circuit board can escape to the outside, thereby suppressing The appearance of poor appearance caused by the peeling of the interface between the cover layer adhesive and the electromagnetic wave shielding sheet.

The shape of the opening viewed from the surface of the metal layer can be formed into various shapes as necessary, such as a perfect circle, an ellipse, a quadrilateral, a polygon, a star, a trapezoid, a branch, and the like. From the viewpoint of manufacturing cost and ensuring the strength and toughness of the metal layer, the shape of the opening is preferably a perfect circle and an ellipse.

[Aperture ratio of metal layer] The aperture ratio of the metal layer is preferably in the range of 0.10% to 20%, and can be obtained by the following formula (2). Formula (2) (Aperture ratio [%])=(Area of opening per unit area)/(Area of opening per unit area+Area of non-opening per unit area)×100

By setting the aperture ratio to 0.10% or more, the volatile components during the reflow process can be sufficiently escaped, thereby suppressing the appearance of defects and the decrease in connection reliability caused by the interface peeling of the cover layer adhesive and the electromagnetic wave shielding sheet , Therefore preferred. On the other hand, by setting the aperture ratio to 20% or less, the amount of electromagnetic wave noise passing through the aperture can be reduced, and the shielding properties can be improved, which is preferable. The range of the aperture ratio that balances reflow resistance and high-frequency shielding properties at a high level is more preferably 0.30% to 15%, and still more preferably 0.50% to 6.5%.

The aperture ratio can be measured, for example, by using a laser microscope and a scanning electron microscope (scanning electron microscope, SEM) to vertically magnify an image of 500 to 2000 times from the surface of the metal layer. , Binarize the opening portion and the non-aperture portion, and use the number of pixels of the binarized color per unit area as the respective areas.

[Method for manufacturing metal layer with opening] The method of manufacturing the metal layer with openings can be a conventionally known method, and it can be applied to a method of forming a patterned resist layer on a metal foil and etching the metal foil to form an opening (i); bottoming with a predetermined pattern A method of screen printing of an anchor agent and metal plating only on the printed surface of the primer agent (ii); and the manufacturing method (iii) described in JP 2015-63730 A, etc. That is, pattern printing of water-soluble or solvent-soluble ink is performed on the support, a metal vapor-deposited film is formed on the surface, and the pattern is removed. A mold release layer is formed on the surface and electrolytic plating is performed to obtain a metal layer with a carrier material and an opening. Among these methods, the method (i) can precisely control the shape of the opening, so Preferred. However, it is not limited to the aforementioned (i) to (iii), and other methods may be used as long as the shape of the opening can be controlled.

"Adhesive Layer" The adhesive layer has the function of bonding the electromagnetic wave shielding sheet and the printed circuit board when the electromagnetic wave shielding sheet is laminated on the printed circuit board to manufacture the electromagnetic wave shielding printed circuit board.

The adhesive layer can be formed using a resin composition. The resin composition contains a binder resin. As the binder resin, any one of a thermoplastic resin, a thermosetting resin, and a curing agent can be used. Any one of a non-conductive adhesive layer and a conductive adhesive layer can be used for the adhesive layer, and the conductive adhesive layer exhibits conductivity by containing a conductive filler or the like.

In addition, as the conductive adhesive layer, either an isotropic conductive adhesive layer or an anisotropic conductive adhesive layer can be used. The isotropic conductive adhesive layer has conductivity in the vertical and horizontal directions when the electromagnetic wave shielding sheet is placed horizontally. In addition, the anisotropic conductive adhesive layer has conductivity only in the vertical direction when the electromagnetic wave shielding sheet is placed horizontally. The conductive adhesive layer may be either isotropic conductivity or anisotropic conductivity. In the case of anisotropic conductivity, the cost can be reduced, which is preferable.

[Thermoplastic resin] Examples of thermoplastic resins include polyolefin resins, vinyl resins, styrene-acrylic resins, diene resins, terpene resins, petroleum resins, cellulose resins, polyamide resins, and polyurethane resins. Acid ester resin, polyester resin, polycarbonate resin, polyimide resin, liquid crystal polymer, fluororesin, etc. Although not particularly limited, from the viewpoint of transmission loss, materials with low dielectric constant and low dielectric loss tangent are preferable, and from the viewpoint of characteristic impedance, materials with low dielectric constant are preferable, such as liquid crystal polymerization. Materials or fluorine-based resins, etc. The thermoplastic resin can be used alone or in combination of two or more kinds.

[Thermosetting resin] The thermosetting resin is a resin having a plurality of functional groups capable of reacting with a curing agent. Examples of functional groups include hydroxyl groups, phenolic hydroxyl groups, acid anhydride groups, methoxymethyl groups, carboxyl groups, amino groups, epoxy groups, oxetanyl groups, oxazoline groups, oxazinyl groups, aziridinyl groups, Thiol group, isocyanate group, blocked isocyanate group, blocked carboxyl group, silanol group, etc. Examples of thermosetting resins include acrylic resins, maleic acid resins, polybutadiene-based resins, polyester resins, polyurethane resins, polyurethane urea resins, epoxy resins, and oxygen. Cyclobutane resin, phenoxy resin, polyimide resin, polyimide resin, polyimide resin, phenolic resin, alkyd resin, amino resin, polylactic acid resin, oxazoline resin, Known resins such as benzoxazine resin, silicone resin, and fluororesin. The thermosetting resin can be used singly or in combination of two or more kinds.

Among them, in terms of cleaning resistance, polyurethane resins, polyurethane urea resins, polyester resins, epoxy resins, phenoxy resins, polyimide resins, Polyamide resin, polyamide imide resin.

[hardener] The curing agent has a plurality of functional groups that can react with the functional groups of the thermosetting resin. Examples of the curing agent include known compounds such as epoxy compounds, acid anhydride group-containing compounds, isocyanate compounds, aziridine compounds, amine compounds, phenol compounds, and organometallic compounds. The hardener can be used alone or in combination of two or more kinds.

It is preferable to contain 1 part by weight to 50 parts by weight of various curing agents with respect to 100 parts by weight of the thermosetting resin. With a curing dose of 1 part by weight or more, a strong cross-linked structure is formed on the adhesive layer, which can inhibit the dissolution and swelling of the adhesive layer when exposed to cleaning agents or when exposed to high temperature and high humidity. The stability of the circuit connection is improved. On the other hand, when the curing amount is 50 parts by weight or less, excessive curing of the adhesive layer can be suppressed, and cracks generated during bending can be suppressed. It is more preferable to contain 3 to 40 parts by weight of various curing agents with respect to 100 parts by weight of the thermosetting resin, and it is still more preferable to contain 3 to 30 parts by weight.

The thermoplastic resin and the thermosetting resin can be used alone or in a mixture of both.

[Conductive filler] The conductive filler has a function of imparting conductivity to the adhesive layer. Among the conductive fillers, as the raw material, for example, conductive metals such as gold, platinum, silver, copper, and nickel, and their alloys, and conductive polymer particles are preferred. In terms of price and conductivity, silver is more preferred. . In addition, from the viewpoint of cost reduction, it is also preferable to use metal or resin instead of fine particles of a single raw material as a core body and composite fine particles having a coating layer that coats the surface of the core body. Here, the core body is preferably appropriately selected from inexpensive nickel, silicon dioxide, copper, alloys thereof, and resins. The coating layer is preferably a conductive metal or a conductive polymer. Examples of conductive metals include gold, platinum, silver, nickel, manganese, and indium, and alloys thereof. In addition, the conductive polymer includes polyaniline, polyacetylene, and the like. Among them, in terms of price and conductivity, silver is preferred.

Regarding the shape of the conductive filler, as long as the desired conductivity can be obtained, the shape is not limited. Specifically, for example, a spherical shape, a flake shape, a leaf shape, a dendritic shape, a plate shape, a needle shape, a rod shape, and a grape shape are preferable. In addition, two kinds of conductive fillers of different shapes may be mixed. The conductive filler can be used alone or in combination of two or more kinds.

The average particle diameter of the conductive filler is the D ₅₀ average particle diameter, and from the viewpoint of sufficiently ensuring conductivity, it is preferably 2 μm or more, more preferably 5 μm or more, and even more preferably 7 μm or more. On the other hand, from the viewpoint of compatibility of the thickness of the adhesive layer, it is preferably 30 μm or less, more preferably 20 μm or less, and still more preferably 15 μm or less. The _{average particle diameter of D 50} can be determined by a laser diffraction/scattering particle size distribution measuring device or the like.

The content of the conductive filler in the adhesive layer is preferably 35% by weight to 90% by weight, more preferably 39% by weight to 70% by weight, and still more preferably 40% by weight to 65% by weight. By setting it as 35% by weight or more, the connection between the adhesive layer and the ground wiring becomes good, and therefore the high-frequency shielding properties and the reliability of the cooling and heating cycle are improved. On the other hand, by setting it to 90% by weight or less, reflow resistance and transmission characteristics are improved.

For the purpose of improving desired physical properties or imparting functions, the resin composition may be additionally formulated with silane coupling agents, rust inhibitors, reducing agents, antioxidants, pigments, dyes, adhesive imparting resins, plasticizers, ultraviolet absorbers, and disinfectants. A foaming agent, a leveling regulator, a filler, a flame retardant, etc. are used as optional components.

The resin composition can be obtained by mixing and stirring the materials described so far. For stirring, for example, a known stirring device such as a dispermat or a homogenizer can be used.

A known method can be used for the preparation of the adhesive layer. For example, a method of forming an adhesive layer by applying a resin composition on a peelable sheet and drying, or by extruding the resin composition into a sheet shape using an extrusion molding machine such as a T-die.

For the coating method, for example, gravure coating method, kiss coating method, die coating method, lip coating method, chipped wheel coating method, doctor blade method, roll coating method, knife coating method, spray coating method, bar coating method, spin coating method, etc. can be used. Well-known coating methods such as coating method and dip coating method. At the time of coating, it is preferable to perform a drying step. For the drying step, for example, a known drying device such as a hot air dryer and an infrared heater can be used.

The thickness of the adhesive layer is not particularly limited, but is preferably smaller than the Rz of the surface of the metal layer. Since the thickness of the adhesive layer is smaller than the Rz of the surface of the metal layer, when the electromagnetic wave shielding sheet is adhered to the printed wiring board, the tip of the unevenness of the metal layer is likely to come into contact with the ground wiring. Among them, when the thickness of the adhesive layer is 1 μm to 20 μm, it is particularly preferable because it can achieve both film properties and adhesion to the substrate, and connection (contact) to the ground wiring.

"The protective layer" The protective layer is located on the surface of the electromagnetic wave shielding printed circuit board including the electromagnetic wave shielding sheet and the printed circuit board, and has the function of preventing the metal layer and the adhesive layer from contacting the cleaning chemicals when cleaning the electromagnetic wave shielding printed circuit board, or through The function of covering the metal layer to block the electrical connection between the metal layer and the external conductor.

The protective layer can be formed using a resin composition. The resin composition contains a binder resin. As the binder resin, any one of a thermoplastic resin, a thermosetting resin, and a curing agent can be used.

The weight average molecular weight of the binder resin is preferably 10,000 or more. When the weight average molecular weight of the binder resin is 10,000 or more, the decomposition or dissolution of the coating film when exposed to cleaning chemicals can be suppressed, and the cleaning resistance can be improved. The weight average molecular weight of the binder resin is more preferably 30,000 or more, and still more preferably 50,000 or more. In addition, from the viewpoint of improving compatibility and dispersibility with other components contained in the protective layer, the weight average molecular weight of the binder resin is preferably 500,000 or less.

[Thermoplastic resin] Examples of thermoplastic resins include polyolefin resins, vinyl resins, styrene-acrylic resins, diene resins, terpene resins, petroleum resins, cellulose resins, polyamide resins, and polyurethane resins. Acid ester resin, polyester resin, polycarbonate resin, polyimide resin, liquid crystal polymer, fluororesin, etc. Although not particularly limited, from the viewpoint of transmission loss, a material with a low dielectric constant and a low dielectric loss tangent is preferable, and from a viewpoint of characteristic impedance, a material with a low dielectric constant is preferable. As suitable examples, liquid crystal polymers, fluorine-based resins, and the like can be cited. The thermoplastic resin can be used alone or in combination of two or more kinds.

[Thermosetting resin] The thermosetting resin is a resin having a plurality of functional groups capable of reacting with a curing agent. Examples of functional groups include hydroxyl groups, phenolic hydroxyl groups, methoxymethyl groups, carboxyl groups, amino groups, epoxy groups, oxetanyl groups, oxazoline groups, oxazinyl groups, aziridinyl groups, and thiol groups. , Isocyanate groups, blocked isocyanate groups, blocked carboxyl groups, silanol groups, etc. Examples of thermosetting resins include acrylic resins, maleic acid resins, polybutadiene resins, polyester resins, polyurethane resins, polyurethane urea resins, epoxy resins, and oxygen. Cyclobutane resin, phenoxy resin, polyimide resin, polyimide resin, polyimide resin, phenolic resin, alkyd resin, amino resin, polylactic acid resin, oxazoline resin, Known resins such as benzoxazine resin, silicone resin, and fluororesin. The thermosetting resin can be used singly or in combination of two or more kinds.

Among them, in terms of reflow resistance, polyurethane resins, polyurethane urea resins, polyester resins, epoxy resins, phenoxy resins, and polyimide resins are preferred. , Polyamide resin, polyamide imide resin.

[hardener] The curing agent has a plurality of functional groups that can react with the functional groups of the thermosetting resin. Examples of the curing agent include known compounds such as epoxy compounds, acid anhydride group-containing compounds, isocyanate compounds, aziridine compounds, amine compounds, phenol compounds, and organometallic compounds. The hardener can be used alone or in combination of two or more kinds.

It is preferable to contain 1 part by weight to 50 parts by weight of various curing agents with respect to 100 parts by weight of the thermosetting resin, more preferably 3 parts by weight to 40 parts by weight, and still more preferably 3 parts by weight to 30 parts by weight.

The thermoplastic resin and the thermosetting resin can be used alone or in a mixture of both.

[Non-conductive particles] The protective layer preferably contains non-conductive particles. The non-conductive particles have the function of improving the insulation of the protective layer and assisting the grounding of the metal layer and the ground wiring by pressing into the metal layer during hot pressing.

When bonding the electromagnetic wave shielding sheet to a printed wiring board and other wiring boards, hot pressing is mainly used. During the hot pressing, as shown in Figure 3, the electromagnetic wave shielding sheet 10 (refer to Figure 1) and the printed wiring board are thermally pressed from above and below The plate 13 is pressed and receives pressure. At this time, the non-conductive particles 4 contained in the protective layer 3 receive pressure from the hot press and transfer the pressure to the metal layer 2. As a result, the metal layer 2 is pressed into the adhesive layer 1 side, and finally comes into contact with the ground wiring 5. The electrical connection between the metal layer 2 and the ground wiring 5 is realized by the above action, and the electromagnetic wave shielding layer 12 can exhibit excellent high-frequency shielding properties.

Examples of the non-conductive particles include non-conductive ceramics, pigments, dyes, etc., and ceramics are preferred in terms of high hardness and capable of transmitting the pressure received during hot pressing to the metal layer without relaxing.

Among the non-conductive particles, non-conductive particles having a volume resistivity of 1.0×10 ¹⁰ Ω·cm or more are preferable. When the non-conductive particles have a volume resistivity of 1.0×10 ¹⁰ Ω·cm or more, the insulation of the protective layer can be further improved. The volume resistivity of the substance contained in the non-conductive particles is more preferably 1.0×10 ¹² Ω·cm or more, and still more preferably 1.0×10 ¹⁴ Ω·cm or more. Examples of substances with a volume resistivity of 1.0×10 ¹⁰ Ω·cm or more include aluminum oxide (alumina), zirconium dioxide (zirconia), silicon dioxide (silica), boron carbide, aluminum nitride, and nitride Ceramics such as boron, magnesia (magnesia), and titanium oxide. Among them, the more preferable material is zirconium dioxide (ZrO ₂ ; volume resistivity 1.0×10 ¹² Ω·cm), and the more preferable material is silicon dioxide (SiO ₂ ; Volume resistivity 1.0×10 ¹⁴ Ω·cm). The volume resistivity of the substance contained in the non-conductive particles can be measured in accordance with JIS C2141.

As long as the non-conductive particles can realize the pressing mechanism into the metal layer, particles of any shape can be used, and the particles are preferably massive, indefinite, substantially spherical, spherical, or true spherical. The non-conductive particles may be porous or have pores in the inside as long as they can realize the pressing mechanism into the metal layer.

The protective layer preferably contains 3% to 80% by weight of non-conductive particles. When the amount of non-conductive particles contained in the protective layer is 3% by weight or more, the insulation is improved, and when the amount is 80% by weight or less, the film formability is improved. The non-conductive particles contained in the protective layer are more preferably 5% by weight to 60% by weight, and particularly preferably 15% by weight to 40% by weight. In terms of the insulation of the protective layer, ^{the content of non-conductive particles having a volume resistivity of 1.0×10 10} Ω·cm or more is preferably 85% by weight to 100% by weight in 100% by weight of non-conductive particles.

The average particle size of the non-conductive particles is not particularly limited as long as the 60° specular gloss on the surface of the metal layer and the X calculated by formula (1) become the desired values, but the range of 1 μm to 50 μm can be It is preferable to achieve the balance of circuit connection stability, folding endurance, and insulation. It is more preferably 4 μm to 20 μm, and still more preferably 6 μm to 14 μm. Further, the average particle diameter described herein is the average particle diameter D _50. The average particle size can be determined by a laser diffraction/scattering particle size distribution measuring device or the like.

The ratio (average particle diameter/thickness) of the average particle diameter (μm) of the non-conductive particles to the thickness (μm) of the protective layer (average particle diameter/thickness) is preferably in the range of 1/4 to 1.5/1. If the ratio of the average particle diameter of the non-conductive particles to the thickness of the protective layer is in the range of 1/4 to 1.5/1, the circuit connection stability, folding resistance, and insulation are improved. When (average particle diameter/thickness) is 1.5/1 or less, non-conductive particles fly out of the protective layer to generate voids, and plating is formed through the voids, thereby suppressing the formation of a metal layer penetrating the protective layer. Improved insulation. On the other hand, when the (average particle diameter/thickness) is 1/4 or more, the effect of pressing the non-conductive particles into the metal layer during hot pressing is enhanced, the connection with the ground wiring is improved, and the circuit connection stability is improved, which is preferable.

The resin composition can be optionally formulated with silane coupling agent, rust inhibitor, reducing agent, antioxidant, adhesion imparting resin, plasticizer, ultraviolet absorber, defoamer, leveling regulator, filler, flame retardant, etc. Element. In addition, pigments other than non-conductive particles may be added for the purpose of coloring the protective layer and improving designability within a range that does not hinder the function as the protective layer. Examples of such pigments include carbon black, graphite, carbon nanotubes, and graphene. Carbon black, graphite, carbon nanotubes, graphene, etc. are preferably added in the range of the addition amount in which a good evaluation of "practical" or higher can be obtained in the insulation evaluation described later.

The resin composition can be obtained by mixing and stirring the materials described so far. For stirring, for example, a known stirring device such as a dispermat or a homogenizer can be used.

A known method can be used for the production of the protective layer. For example, a method of forming a protective layer by applying a resin composition on a peelable sheet and drying, or by extruding the resin composition into a sheet shape using an extrusion molding machine such as a T-die.

For the coating method, for example, gravure coating method, kiss coating method, die coating method, lip coating method, chipped wheel coating method, doctor blade method, roll coating method, knife coating method, spray coating method, bar coating method, spin coating method, etc. can be used. Well-known coating methods such as coating method and dip coating method. At the time of coating, it is preferable to perform a drying step. For the drying step, for example, a known drying device such as a hot air dryer and an infrared heater can be used.

In addition, the protective layer can also use a film formed by molding insulating resins such as polyester, polycarbonate, polyimide, polyimide, polyamide, polyphenylene sulfide, and polyether ether ketone.

The thickness of the protective layer is preferably 2 μm to 20 μm. When the thickness of the protective layer is 2 μm to 20 μm, dissolution of the protective layer after exposure to cleaning chemicals or peeling from the metal layer can be suppressed.

In addition to the adhesive layer, the metal layer and the protective layer, the electromagnetic wave shielding sheet may also include other functional layers. The other functional layer is a layer having functions such as hard coat properties, water vapor barrier properties, oxygen barrier properties, thermal conductivity, low dielectric constant, high dielectric constant, or heat resistance.

The electromagnetic wave shielding sheet of the present invention can be used for various applications that need to shield electromagnetic waves. For example, it goes without saying that flexible printed wiring boards can also be used for rigid printed wiring boards, chip on 60° mirror gloss lm (COF), tape automated bonding (TAB), flexible connectors , LCD display, touch screen, etc. In addition, it can also be used as an electromagnetic wave blocking member for building materials such as housings of personal computers, walls and windows of building materials, vehicles, ships, and airplanes.

In the electromagnetic wave shielding sheet of the present invention, when a thermoplastic resin is used for the adhesive resin in the adhesive layer, the thermoplastic resin contained is present in a solid state, and the thermoplastic resin is melted by hot pressing with the wiring circuit board. And solidified again after cooling, and the desired bonding strength can be obtained.

In the electromagnetic wave shielding sheet of the present invention, when a thermosetting resin is used for the adhesive resin in the adhesive layer, the thermosetting resin and curing agent contained therein are present in an uncured state (stage B), and the The hot pressing of the printed circuit board is hardened (C stage), and the desired bonding strength can be obtained. In addition, the uncured state includes a semi-cured state in which a part of the hardener is hardened.

In addition, in order to prevent the adhesion of foreign matter, the electromagnetic wave shielding sheet is usually stored in a state where the peelable sheet is attached to the adhesive layer and the protective layer.

The peelable sheet is a sheet obtained by subjecting a base material such as paper or plastic to a known peeling treatment.

＜Electromagnetic wave shielding wiring circuit board＞ The electromagnetic wave shielding wiring circuit board includes an electromagnetic wave shielding layer formed of the electromagnetic wave shielding sheet of the present invention, a top coat, and a wiring circuit board (wiring board) including signal wiring and an insulating base material. The wired circuit board includes a circuit pattern having signal wiring and ground wiring on the surface of the insulating base material. A surface coating is formed on the wiring circuit board to insulate and protect the signal wiring and the ground wiring, and at least a part of the ground wiring has a through hole. Furthermore, after arranging the adhesive layer of the electromagnetic wave shielding sheet on the top coat, the electromagnetic wave shielding sheet is thermally pressed so that the adhesive layer flows into the through hole and is bonded to the ground wiring. This can produce electromagnetic wave shielding wiring circuit boards.

An example of the electromagnetic wave shielding printed circuit board of the present invention will be described with reference to FIG. 4. The electromagnetic wave shielding layer 12 has a structure including an adhesive layer 1, a metal layer 2, and a protective layer 3.

The top coat 8 is an insulating material that covers the signal wiring 6 of the printed circuit board 20 to protect it from the external environment. The top coat layer is preferably a polyimide film with a thermosetting adhesive, a thermosetting or ultraviolet curing type solder resist, or a photosensitive cover film. For fine processing, a photosensitive cover film is more preferable. In addition, the top coat layer 8 usually uses a known resin having heat resistance and flexibility, such as polyimide. The thickness of the top coat is usually about 10 μm to 100 μm.

The circuit pattern includes a ground wiring 5 that is grounded, and a signal wiring 6 that transmits electrical signals to electronic components. Both are usually formed by etching copper foil. The thickness of the circuit pattern is usually about 1 μm to 50 μm.

The insulating substrate 9 is a support for the circuit pattern, and is preferably a bendable plastic such as polyester, polycarbonate, polyimide, polyphenylene sulfide, liquid crystal polymer, and more preferably liquid crystal polymer and polyamide. amine. Among them, considering the use of a wiring circuit board for transmitting high-frequency signals, a liquid crystal polymer having a low relative permittivity and a low dielectric loss tangent is more preferable. When the wiring circuit board is a rigid wiring board, the constituent material of the insulating base material is preferably glass epoxy. By including the insulating base material 9 like these, the wiring circuit board 20 obtains high heat resistance.

The hot pressing of the electromagnetic wave shielding sheet 10 (see FIG. 1) and the printed circuit board 20 is usually performed under the conditions of a temperature of about 150°C to 190°C, a pressure of about 1 MPa to 3 MPa, and a time of about 1 minute to 60 minutes. By hot pressing, the adhesive layer 1 and the top coating layer 8 are in close contact. By hot pressing, the thermosetting resin reacts and hardens to become the electromagnetic wave shielding layer 12. In addition, in order to promote hardening, post-curing may be performed at 150°C to 190°C for 30 minutes to 90 minutes after hot pressing.

The opening area of the through hole 11 is preferably 0.8 mm ² or less, and preferably 0.008 mm ² or more. By setting it as this range, the area of the ground wiring 5 can be narrowed, and the miniaturization of wiring boards, such as a printed wiring board, can be achieved. The shape of the through hole is not particularly limited, and any of circles, squares, rectangles, triangles, and irregular shapes can be used according to the application.

In terms of more effectively suppressing the leakage of electromagnetic waves, it is preferable that the electromagnetic wave shielding layers 12 are laminated on both sides of the printed circuit board 20. In addition, the electromagnetic wave shielding layer 12 in the electromagnetic wave shielding printed circuit board 7 can also be used as a grounding circuit in addition to shielding electromagnetic waves. With this structure, a part of the ground circuit is omitted, and the area of the printed circuit board 20 can be reduced, thereby achieving cost reduction. As a result, the electromagnetic wave shielding printed circuit board can be assembled in a narrow area in the housing.

In addition, the signal wiring is not particularly limited, and it can be used in either a single ended (single ended) circuit including one signal wiring or a differential circuit including two signal wirings, but a differential circuit is more preferable. On the other hand, when there are restrictions on the circuit pattern area of the printed circuit board and it is difficult to form a ground circuit in parallel, the ground circuit may not be provided in the lateral direction of the signal circuit, and the electromagnetic wave shielding layer may be used as the ground circuit to make it thinner. There is a grounded printed wiring board structure in the direction.

The electromagnetic wave shielding printed circuit board of the present invention can be mounted on, for example, a liquid crystal display, a touch screen, etc., and can also be mounted on and used in electronic devices such as notebook computers, mobile phones, smartphones, and tablet terminals. [Example]

Hereinafter, the present invention will be explained in more detail through examples, but the present invention is not limited to the following examples. In addition, "parts" in the examples means "parts by weight", and "%" means "% by weight".

In addition, the acid value of the resin, the weight average molecular weight (Mw), the glass transition temperature (Tg), and the average particle size of the conductive filler and non-conductive particles are measured by the following methods.

"Determination of acid value of binder resin" The acid value is measured in accordance with JIS K0070. Accurately measure about 1 g of the sample in a stoppered Erlenmeyer flask, add 100 mL of tetrahydrofuran/ethanol (volume ratio: tetrahydrofuran/ethanol=2/1) mixture to dissolve. A phenolphthalein test solution was added as an indicator, and titration was performed with a 0.1 N alcoholic potassium hydroxide solution, and the time when the indicator remained light red for 30 seconds was set as the end point. The acid value (unit: mgKOH/g) is obtained by the following formula. Acid value (mgKOH/g)=(5.611×a×F)/S Among them, S: the amount of sample taken (g) a: The consumption of 0.1 N alcoholic potassium hydroxide solution (mL) F: The titer of 0.1 N alcoholic potassium hydroxide solution

"Determination of the weight average molecular weight (Mw) of the binder resin" The weight average molecular weight (Mw) was measured using a gel permeation chromatograph (GPC) "HPC-8020" manufactured by Tosoh Co., Ltd. GPC is a liquid chromatograph that uses the difference in molecular size to separate and quantify substances dissolved in a solvent (THF; tetrahydrofuran). The measurement in the present invention is to connect two "LF-604" (manufactured by Showa Denko Co., Ltd.; GPC column for rapid analysis; 6 mm inner diameter (ID) × 150 mm size) in series to be used as a tube The column was performed under the conditions of a flow rate of 0.6 mL/min and a column temperature of 40°C. The weight average molecular weight (Mw) was determined by polystyrene conversion.

"Glass Transition Temperature (Tg) of Adhesive Resin" The Tg is measured by differential scanning calorimetry ("DSC-1" manufactured by Mettler Toledo).

"Measurement of the average particle size of conductive fillers and non-conductive particles" The average particle size of D ₅₀ is measured by the laser diffraction/scattering particle size distribution analyzer LS13320 (manufactured by Beckman Coulter), and passed The tornado dry powder sample module measures the conductive fillers and non-conductive particles to obtain the value, and is the particle size at which the cumulative value of the cumulative particle size distribution is 50%. In addition, the refractive index is set to 1.6.

Next, the materials used in the examples are shown below. "Materials" ･Binder resin 1: Acid value 5 mgKOH/g, weight average molecular weight 70,000, Tg of -5°C polyurethane urea resin (manufactured by TOYO CHEM) ･Epoxy compound : "JER828" (bisphenol A epoxy resin epoxy equivalent = 189 g/eq) manufactured by Mitsubishi Chemical Corporation･aziridine compound: "Chemitite PZ-33" manufactured by Japan Catalyst Corporation･non-conductive Particle 1: Sunsphere H-121 (D ₅₀ average particle size: 12.0 μm, SiO ₂ ; volume resistivity 1.0×10 ¹⁴ Ω·cm content rate is 99%. AGC Si-Tech) Manufactured by the company) ･Non-conductive particles 2: Sunsphere NP-100 (D ₅₀ average particle size: 8.0 μm, SiO ₂ ; volume resistivity 1.0×10 ¹⁴ Ω·cm with a content rate of 99%. AGC silicon technology (Manufactured by AGC Si-Tech) ･Non-conductive particles 3: Sunsphere H-51 (D ₅₀ average particle size: 5.0 μm, SiO ₂ ; volume resistivity 1.0×10 ¹⁴ Ω·cm content rate 99%. AGC Si-Tech company manufacture) ･Non-conductive particles 4: Sunsphere H-31 (D ₅₀ average particle size: 3.0 μm, SiO ₂ ; volume resistivity 1.0×10 ¹⁴ Ω ·The content of cm is 99%. AGC Si-Tech (manufactured by AGC Si-Tech) ･Non-conductive particles 5: Sunsphere H-201 (D ₅₀ average particle size: 15.0 μm, SiO ₂ ; volume resistance The content rate of 1.0×10 ¹⁴ Ω·cm is 99%. AGC Si-Tech (manufactured by AGC Si-Tech)) ･Non-conductive particles 6: Zirconia beads NZ10SP (D ₅₀ average particle size: 12.0 μm, ZrO ₂ ; volume resistivity 1.0×10 ¹² Ω·cm with a content rate of 88%. Niimi Sangyo Co., Ltd. ･Non-conductive particle 7: GC #1000 (D ₅₀ average particle size: 11.9 μm, SiC ；Volume resistivity 1.0×10 ⁶ Ω·cm The content rate is 92%. Fujimi Incorporated Co., Ltd. (manufactured by Fujimi Incorporated) ･Conductive filler: composite fine particles (corresponding to 100 parts by weight of copper as the core body, coated with 10 parts by weight of silver dendritic fine particles, D ₅₀ average particle size: 11.0 μm manufactured by Fukuda Metal Foil & Powder Industry Co., Ltd.) ･Copper foil with carrier material A1: 2.5 μm thick with copper carrier Body of electrolytic copper foil. Through the etching process, openings of 30 μmϕ were formed so that the aperture ratio became 6.5%.

<Production of Adhesive Layer 1> In terms of solid content, 1 100 parts of binder resin, 20 parts of epoxy compound, and 0.5 part of aziridine compound are put into a container, and the mixed solvent (toluene: isopropanol) is added so that the concentration of non-volatile content becomes 40%. =2:1 (weight ratio)), and stirred with a disperser for 10 minutes to obtain a resin composition.

Using a bar coater, the resin composition was applied to the peelable sheet so that the dry thickness became 6.0 μm, and dried in an electric oven at 100° C. for 2 minutes, thereby obtaining the adhesive layer 1.

<Production of Adhesive Layer 2-Adhesive Layer 6> The addition amount of the epoxy compound was changed as shown in Table 1, and the same method as that of the adhesive layer 1 was carried out except that the adhesive layer 2 to the adhesive layer 6 were obtained.

<Production of Adhesive Layer 7> In terms of solid content, 1 100 parts of binder resin, 80 parts of conductive filler, 20 parts of epoxy compound, and 0.5 part of aziridine compound are put into a container, and the mixed solvent is added so that the concentration of non-volatile content becomes 40% (Toluene: Isopropanol=2:1 (weight ratio)), and stirred with a disperser for 10 minutes to obtain a resin composition.

Using a bar coater, the resin composition was applied to the peelable sheet so that the dry thickness became 6 μm, and dried in an electric oven at 100° C. for 2 minutes, thereby obtaining an adhesive layer 7.

[Example 1] In terms of solid content, 1 100 parts of a binder resin, 30 parts of an epoxy compound, 7.5 parts of an aziridine compound, and 1 31.4 parts of non-conductive particles were added, and stirred with a disperser for 10 minutes, thereby obtaining a resin composition 1. Using a bar coater, the obtained resin composition 1 was applied to a peelable sheet (thickness 50 μm) so that the dry thickness became 11 μm, and dried in an electric oven at 100° C. for 2 minutes to form the protective layer 1.

Next, a copper plating layer (2.5 μm) as a metal layer was formed on the surface of the obtained "peelable sheet/protective layer 1" where the protective layer 1 was exposed. The copper plating layer was formed by an electroplating method, the electrolyte used was copper sulfate, and the current was applied at 25°C for 7 minutes.

The adhesive layer 1 is bonded to the formed metal layer to obtain an electromagnetic wave shielding sheet including "peelable sheet/protective layer 1/metal layer (plating layer)/adhesive layer 1/peelable sheet". The bonding of the metal layer and the adhesive layer 1 was performed by a thermal laminator at a temperature of 90°C and a pressure of 3 kgf/cm ^2.

[Example 2 to Example 19, Example 23 to Example 27, and Comparative Example 1 to Comparative Example 2] Except for changing the types of adhesive layer, metal layer, and protective layer as shown in Table 1 and Table 2, the same procedure as in Example 1 was carried out to obtain Examples 2 to 19, and Example 23, respectively. -The electromagnetic wave shielding sheet of Example 27 and Comparative Example 1 to Comparative Example 2. When the 60° specular gloss of the metal layer surface after the copper plating layer is formed is different from the target value, the 60° specular gloss is adjusted by appropriately polishing the surface or roughening the surface.

[Example 20] Using a bar coater, the resin composition 1 obtained by the same method as in Example 1 was applied to the copper foil A1 with a carrier material so that the dry thickness became 11 μm, and it was performed in an electric oven at 100°C for 2 minutes The protective layer 11 is formed by drying, and a peelable sheet is bonded to the protective layer 11.

Next, the carrier material of the copper foil A1 with carrier material was peeled off, the copper foil surface was polished, and the 60° specular gloss of the copper foil surface was adjusted to the value shown in Table 2 to obtain a metal layer. The adhesive layer 1 is bonded to the polished metal layer, thereby obtaining an electromagnetic wave shielding sheet including "peelable sheet/protective layer 1/metal layer (copper foil)/adhesive layer 1/peelable sheet". The bonding of the metal layer and the adhesive layer 1 was performed by a thermal laminator at a temperature of 90°C and a pressure of 3 kgf/cm ^2.

[Example 21] The surface of the "peelable sheet/protective layer 1" obtained by the same method as in Example 1 on which the protective layer 1 was exposed was subjected to a copper sputtering treatment to form a metal layer.

The adhesive layer 1 is bonded to the formed metal layer to obtain an electromagnetic wave shielding sheet including "releasable sheet/protective layer 1/metal layer (sputtering layer)/adhesive layer 1/releasable sheet". The bonding of the metal layer and the adhesive layer 1 was performed by a thermal laminator at a temperature of 90°C and a pressure of 3 kgf/cm ^2.

[Example 22] The surface of the "peelable sheet/protective layer 1" obtained by the same method as in Example 1 on which the protective layer 1 was exposed was subjected to a copper vapor deposition process to form a metal layer.

The adhesive layer 1 is bonded to the formed metal layer to obtain an electromagnetic wave shielding sheet including "peelable sheet/protective layer 1/metal layer (evaporated layer)/adhesive layer 1/peelable sheet". The bonding of the metal layer and the adhesive layer 1 was performed by a thermal laminator at a temperature of 90°C and a pressure of 3 kgf/cm ^2.

Regarding the obtained electromagnetic wave shielding sheet, the thickness of each layer and the 60° specular gloss of the metal layer were measured by the following method.

"Measurement of the thickness of each layer" The thickness of the adhesive layer, metal layer, and protective layer of the electromagnetic wave shielding sheet is measured by the following method. The peelable sheet on the adhesive layer side of the electromagnetic wave shielding sheet is peeled off, and the exposed adhesive layer is separated from the polyimide film ("Kapton 200EN" manufactured by Toray Dupont Co., Ltd. ) Laminating, hot pressing at 2 MPa and 170°C for 30 minutes. After cutting it into a size of 5 mm in width and 5 mm in length, 0.05 g of epoxy resin (Petropoxy 154, manufactured by Maruto Co., Ltd.) was dropped onto the glass slide. And bonding the electromagnetic wave shielding sheet to obtain a laminated body of the structure of the glass slide/electromagnetic wave shielding sheet/polyimide film. For the obtained laminate, a cross section polisher (manufactured by JEOL Ltd., SM-09010) was cut from the polyimide film side by ion beam irradiation to obtain a hot-pressed electromagnetic wave shielding sheet The measurement sample.

The cross section of the obtained measurement sample was observed using a laser microscope (manufactured by KEYENCE, VK-X100), and the thickness of each layer was measured based on the observed enlarged image. The magnification is set from 500 times to 2000 times. Regarding the thickness T of the protective layer, the distance of a perpendicular line passing through a point of the protective layer closest to the adhesive layer starting from the outermost surface of the protective layer of the electromagnetic wave shielding sheet in the enlarged image is set to T.

"Measurement of 60° Mirror Gloss" The 60° specular gloss of the metal layer of the electromagnetic wave shielding sheet was measured by the following method. The peelable sheet on the adhesive layer side of the electromagnetic wave shielding sheet was peeled off, and the exposed adhesive layer was rinsed with acetone to expose the metal layer. The adhesive layer was removed, and the surface of the exposed metal layer was measured with a glossmeter (manufactured by BYK, Micro-Tri-Gloss). As shown in FIG. 2(i) and FIG. 2(ii), the incident angle was set to 60° with respect to the perpendicular to the substrate, and the measured value at the measurement angle of 60° was set to 60° specular gloss.

"Determination of Rz" The maximum height roughness Rz of the metal layer of the electromagnetic wave shielding sheet is measured by the following method. The peelable sheet on the adhesive layer side of the electromagnetic wave shielding sheet was peeled off, and the exposed adhesive layer was rinsed with acetone to expose the metal layer. The adhesive layer was removed, and a laser microscope (manufactured by KEYENCE, VK-X100) was used to obtain measurement data (objective lens magnification: 50 times) on the surface of the exposed metal layer. Input the acquired measurement data into analysis software (analysis application "VK-H1XA", manufactured by KEYENCE), and perform line roughness measurement (cut-off conditions: λs: 2.5 μm, λc: 0.8 mm). The measuring range is 0.25 mm). In one measurement field of view, measurement is performed on 5 areas, and the measurement field is changed to perform the same measurement on 5 fields of view. The average value of the measurement data of a total of 25 regions is defined as the maximum height roughness Rz of the metal layer. In addition, regarding the metal layer having an opening on the surface, the opening is excluded from the measurement range when the line roughness measurement is performed.

Regarding the obtained electromagnetic wave shielding sheet, cleaning resistance, circuit connection stability, folding resistance, and insulation were evaluated by the following methods.

＜Cleaning resistance＞ Peel off the peelable sheet on the adhesive layer side of an electromagnetic wave shielding sheet with a width of 40 mm and a length of 40 mm. Under the conditions of 170°C, 2.0 MPa, and 30 minutes, the exposed adhesive layer is connected to a width of 50 mm. , 50 mm long polyimide film ("Kapton 500H" manufactured by Toray Dupont) is crimped and thermally cured to obtain a sample. On the protective layer side of the electromagnetic wave shielding sheet of the obtained sample, 100 checkers with 1 mm intervals were made using a cross cut guide in accordance with JISK5400. Then, immerse for 20 minutes in the solvent-based cleaning fluid "Zestoron FA+" (manufactured by Zestoron), using an ultrasonic cleaner "UT-205HS" (manufactured by Sharp) , Set the output power to 100%, after 2 minutes of ultrasonic treatment, take out the sample, wash it with distilled water, and then dry it. The cleaning solution was changed to "10% by weight aqueous hydrochloric acid solution", "10% by weight sodium hydroxide aqueous solution", "PINE ALPHA ST-100S (manufactured by Arakawa Chemical Co., Ltd.)", and the newly prepared ones were marked with a checkerboard The test piece is subjected to ultrasonic-cleaning treatment. The adhesive tape was strongly press-bonded to the checkerboard part of each test piece, and the end of the tape was peeled off at an angle of 45°. Based on the number of the peeled checkerboard and the state of the checkerboard, the judgment was made according to the following criteria. ◎: Regarding any test piece, the number of checkerboards peeled off is less than five. Extremely good. ○: In any one or all test pieces, the number of checkerboards where peeling occurred is 5 or more and less than 15, and test pieces that do not meet the above conditions are referred to as ◎. good. △: In any one or all of the test pieces, the number of checkerboards to be peeled off is 15 or more and less than 35, and the test piece that does not meet the above conditions is the above-mentioned ⊚ or ◯. Can be practical. ×: In any test piece, the number of checkerboards peeled off is 35 or more. Not practical.

<Circuit connection stability> The circuit connection stability is evaluated by measuring the connection resistance value through a small opening through hole. The specific method of evaluation is shown below. As the sample 25, an electromagnetic wave shielding sheet was prepared in a size of 20 mm in width and 50 mm in length. 6(1) and 6(4) are shown in the plan view for explanation. The peelable sheet is peeled off from the sample 25, and the exposed adhesive is removed under the conditions of 170°C, 2 MPa, and 30 minutes. The adhesive layer 25b is crimped to a separately produced flexible printed wiring board (a 25 μm thick polyimide film 21 is formed with a copper foil circuit 22A and a copper foil circuit 22B with a thickness of 18 μm that are not electrically connected to each other. The copper foil circuit 22A is laminated with a wiring board with an adhesive polyimide covering layer 23 with a thickness of 37.5 μm and a circular through hole 24 with a diameter of 1.1 mm (through hole area of 1.0 mm ^{2 ), so that} The adhesive layer 25b and the protective layer 25a of the electromagnetic wave shielding sheet were cured, thereby obtaining a sample. Next, the peelable sheet on the side of the protective layer 25a of the sample was removed, and the BSP probe of "Loresta GP" manufactured by Mitsubishi Chemical Analytech was used to measure the value of (4) in FIG. 6 The initial connection resistance value between 22A-22B shown in the plan view. In addition, (2) of FIG. 6 is a cross-sectional view of D-D′ of (1) of FIG. 6, and (3) of FIG. 6 is a cross-sectional view of CC′ of (1) of FIG. 6. Similarly, (5) of FIG. 6 is a cross-sectional view of D-D' of (4) of FIG. 6 and (6) of (6) is a cross-sectional view of CC' of (4) of FIG. 6. Put the sample into a high-temperature and high-humidity device ("PHP-2J", manufactured by Espec), and expose the sample for 500 hours under exposure conditions of temperature: 85°C and relative humidity: 85%. After that, the connection resistance value of the sample was measured in the same manner as in the initial stage. The evaluation criteria of circuit connection stability are as follows. ◎: (Connection resistance value after exposure)/(Initial connection resistance value) is less than 1.5. Extremely good. ○: (Connection resistance value after exposure)/(Initial connection resistance value) is 1.5 or more and less than 3.0. good. △: (Connection resistance value after exposure)/(Initial connection resistance value) is 3.0 or more and less than 5.0. Can be practical. ×: (Connection resistance value after exposure)/(Initial connection resistance value) is 5.0 or more. Not practical.

＜Folding resistance＞ Peel off the peelable sheet of the adhesive layer of the electromagnetic wave shielding sheet with a width of 20 mm and a length of 100 mm. Under the conditions of 150°C, 2.0 MPa, and 30 minutes, the exposed adhesive layer is A 100 mm long polyimide film (“Kapton 500H” manufactured by Toray Dupont Co., Ltd.) was crimped and thermally cured to obtain a sample. The obtained sample was bent 180 degrees so that the electromagnetic wave shielding sheet became the outer side, and a 1000 g weight was placed on the bent portion for 10 seconds. After that, the bent portion was restored to its original flat state and loaded again. Set a weight of 1000 g for 10 seconds and set this as the number of bends once. Use the microscope "VHX-900" manufactured by KEYENCE (stock) to observe whether there are cracks in the electromagnetic wave shielding sheet, and evaluate the number of times that the electromagnetic wave shielding sheet can be bent without cracks. Count the number of times of bending until cracks occurred in the bending part to which a load of 1000 g was applied. The evaluation criteria are as follows. ◎: 10 times or more. Very good. ○: 7 times or more and less than 10 times. Good. △: 2 times or more and less than 7 times. Can be practical. ×: Less than 2 times. Not practical.

<Insulation> Peel off the peelable sheet on the adhesive layer side of an electromagnetic wave shielding sheet with a width of 50 mm and a length of 100 mm, and remove the exposed adhesive layer at 170°C, 2.0 MPa, and 30 minutes. A polyimide film ("Kapton 300H" manufactured by Toray Dupont Co., Ltd.) with a width of 70 mm and a length of 120 mm was crimped and thermally cured to obtain a test piece. The surface resistance value of the protective layer of the test piece was measured using a ring probe URS "Hiresta UP MCP-HT800" manufactured by Mitsubishi Chemical Analytech. The evaluation criteria are as follows. ◎: 1.0×10 ⁹ Ω/□ or more. Extremely good. ○: 1.0×10 ⁷ Ω/□ or more and less than 1.0×10 ⁹ Ω/□. good. △: 1.0×10 ⁵ Ω/□ or more and less than 1.0×10 ⁷ Ω/□. Can be practical. ×: Less than 1.0×10 ⁵ Ω/□. Not practical.

[Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Example 11 Example 12 Example 13 Example 14 Example 15 Adhesive layer type Adhesive layer 1 Adhesive layer 1 Adhesive layer 1 Adhesive layer 1 Adhesive layer 2 Adhesive layer 3 Adhesive layer 4 Adhesive layer 5 Adhesive layer 6 Adhesive layer 1 Adhesive layer 1 Adhesive layer 1 Adhesive layer 1 Adhesive layer 1 Adhesive layer 1 Adhesive resin [parts by weight] Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 Epoxy compound [parts by weight] 20 20 20 20 0.5 2 35 45 60 20 20 20 20 20 20 Aziridine compound [parts by weight] 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Conductive filler [parts by weight] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Conductive filler content [wt%] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Thickness [μm] 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 Metal layer type Plating layer Plating layer Plating layer Plating layer Plating layer Plating layer Plating layer Plating layer Plating layer Plating layer Plating layer Plating layer Plating layer Plating layer Plating layer 60° mirror gloss 5 48 290 485 5 5 5 5 5 5 5 5 5 37 269 Thickness [μm] 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Maximum height roughness Rz [μm] 10.5 10.5 10.5 10.5 10.5 10.5 10.5 10.5 10.5 10.5 10.5 10.5 10.5 7.0 3.0 Opening area [μm ² ] - - - - - - - - - - - - - - - Number of openings [a] - - - - - - - - - - - - - - - Opening rate [%] - - - - - - - - - - - - - - - The protective layer type Protective layer 1 Protective layer 1 Protective layer 1 Protective layer 1 Protective layer 1 Protective layer 1 Protective layer 1 Protective layer 1 Protective layer 1 Protective layer 2 Protective layer 3 Protective layer 4 Protective layer 5 Protective layer 6 Protective layer 7 Adhesive resin [parts by weight] Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 Epoxy compound [parts by weight] 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 Aziridine compound [parts by weight] 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 Types of non-conductive particles Non-conductive particles 1 Non-conductive particles 1 Non-conductive particles 1 Non-conductive particles 1 Non-conductive particles 1 Non-conductive particles 1 Non-conductive particles 1 Non-conductive particles 1 Non-conductive particles 1 - Non-conductive particles 1 Non-conductive particles 1 Non-conductive particles 1 Non-conductive particles 2 Non-conductive particles 3 Non-conductive particles [parts by weight] 31.4 31.4 31.4 31.4 31.4 31.4 31.35 31.4 31.4 0.0 5.5 13.8 59.0 31.4 31.4 Non-conductive particle content rate [wt%] 18.6 18.6 18.6 18.6 18.6 18.6 18.6 18.6 18.6 0.0 3.8 9.1 30.0 18.6 18.6 Thickness [μm] 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 X=Rz/T 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.64 0.27 Evaluation Cleaning resistance ◎ ◎ ○ △ △ ○ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ○ Circuit connection stability ◎ ◎ ◎ ◎ △ ○ ◎ ◎ ◎ △ ○ ◎ ◎ ◎ ○ Folding resistance ◎ ◎ ◎ ◎ ◎ ◎ ◎ ○ △ ◎ ◎ ◎ ◎ ◎ ◎ Insulation ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ △ ○ ◎ ◎ ◎ ◎

[Table 2] Example 16 Example 17 Example 18 Example 19 Example 20 Example 21 Example 22 Example 23 Example 24 Example 25 Example 26 Example 27 Comparative example 1 Comparative example 2 Adhesive layer type Adhesive layer 1 Adhesive layer 1 Adhesive layer 1 Adhesive layer 7 Adhesive layer 1 Adhesive layer 1 Adhesive layer 1 Adhesive layer 1 Adhesive layer 1 Adhesive layer 1 Adhesive layer 1 Adhesive layer 1 Adhesive layer 1 Adhesive layer 1 Adhesive resin [parts by weight] Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 100 100 100 100 100 100 100 100 100 100 100 100 100 100 Epoxy compound [parts by weight] 20 20 20 20 20 20 20 20 20 20 20 20 20 20 Aziridine compound [parts by weight] 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Conductive filler [parts by weight] 0 0 0 80 0 0 0 0 0 0 0 0 0 0 Conductive filler content [wt%] 0 0 0 40 0 0 0 0 0 0 0 0 0 0 Thickness [μm] 6 6 6 6 6 6 6 6 6 6 6 6 6 6 Metal layer type Plating layer Plating layer Plating layer Plating layer Copper foil Sputtered layer Evaporated layer Plating layer Plating layer Plating layer Plating layer Plating layer Plating layer Plating layer 60° mirror gloss 472 5 5 5 5 5 5 5 5 5 5 5 612 5 Thickness [μm] 2.5 2.5 2.5 2.5 2.5 2.5 2.5 0.1 0.3 0.5 7.0 11.0 2.5 2.5 Maximum height roughness Rz [μm] 1.5 10.5 10.5 10.5 10.5 10.5 10.5 10.5 10.5 10.5 10.5 10.5 10.5 15.0 Opening area [μm ² ] - - - - 314 - - - - - - - - - Number of openings [a] - - - - 20700 - - - - - - - - - Opening rate [%] - - - - 6.5% - - - - - - - - - The protective layer type Protective layer 8 Protective layer 9 Protective layer 10 Protective layer 1 Protective layer 11 Protective layer 1 Protective layer 1 Protective layer 1 Protective layer 1 Protective layer 1 Protective layer 1 Protective layer 1 Protective layer 1 Protective layer 12 Adhesive resin [parts by weight] Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 Adhesive resin 1 100 100 100 100 100 100 100 100 100 100 100 100 100 100 Epoxy compound [parts by weight] 30 30 30 30 30 30 30 30 30 30 30 30 30 30 Aziridine compound [parts by weight] 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 Types of non-conductive particles Non-conductive particles 4 Non-conductive particles 6 Non-conductive particles 7 Non-conductive particles 1 Non-conductive particles 1 Non-conductive particles 1 Non-conductive particles 1 Non-conductive particles 1 Non-conductive particles 1 Non-conductive particles 1 Non-conductive particles 1 Non-conductive particles 1 Non-conductive particles 1 Non-conductive particles 5 Non-conductive particles [parts by weight] 18.6 18.6 18.6 18.6 18.6 18.6 18.6 18.6 18.6 18.6 18.6 18.6 18.6 18.6 Non-conductive particle content rate [wt%] 31.4 31.4 31.4 31.4 31.4 31.4 31.4 31.4 31.4 31.4 31.4 31.4 31.4 31.4 Thickness [μm] 11 11 11 11 11 11 11 11 11 11 11 11 11 11 X=Rz/T 0.14 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 1.36 Evaluation Cleaning resistance △ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ X ◎ Circuit connection stability △ ◎ ◎ ◎ ◎ ◎ ◎ △ ○ ◎ ◎ ◎ ◎ ◎ Folding resistance ◎ ◎ ◎ ◎ ◎ ◎ ◎ △ ○ ◎ ○ △ ◎ △ Insulation ◎ ○ △ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ X

1: Adhesive layer 2: metal layer 3: protective layer 4: Non-conductive particles 5: Ground wiring 6: Signal wiring 7: Electromagnetic wave shielding wiring circuit board 8: Top coat 9: Insulating base material 10: Electromagnetic wave shielding sheet 11: Through hole 12: Electromagnetic wave shielding layer 13: Hot pressing plate 14: Peelable film 20: Wiring circuit board 21: Polyimide film 22A, 22B: copper foil circuit 23: Polyimide coating with adhesive 24: round through hole 25: Electromagnetic wave shielding layer 25a: protective layer 25b: Adhesive layer Rz: Maximum height roughness T: thickness

FIG. 1 is a cross-sectional view illustrating the electromagnetic wave shielding sheet of this embodiment. 2(i) and 2(ii) are diagrams illustrating a comparison of the ratio of specular reflection light/diffuse reflection light on surfaces with different roughnesses. FIG. 3 is a partially enlarged schematic cross-sectional view of a cut portion showing an example of the manufacturing procedure of the electromagnetic wave shielding printed circuit board according to the description of the pressing effect of the non-conductive particles. 4 is a schematic cross-sectional view of a cut portion showing an example of the electromagnetic wave shielding printed circuit board of the present embodiment. 5(a) and 5(b) are two types of cross-sectional views in which the relationship between the thickness T of the protective layer and the maximum height roughness Rz of the metal layer is different. Figures 6(1) and 6(4) are schematic plan views of the circuit connection stability evaluation. Figures 6(2), 6(3), 6(5), 6(6) ) Is a cross-sectional view of its cut section.

1: Adhesive layer

2: metal layer

3: protective layer

10: Electromagnetic wave shielding sheet

Claims (5)

An electromagnetic wave shielding sheet, characterized in that it has a laminate including an adhesive layer, a metal layer, and a protective layer in this order, On the surface of the metal layer in contact with the adhesive layer, the 60° specular gloss calculated in accordance with International Organization for Standardization 7668 is 0 to 500, and X represented by the formula (1) is less than 1.0, Formula 1) X=Rz/T (Rz is the maximum height roughness of the metal layer calculated according to Japanese Industrial Standard B0601, and T is the thickness of the protective layer). The electromagnetic wave shielding sheet according to claim 1, wherein the thickness of the metal layer is 0.3 μm to 10 μm. The electromagnetic wave shielding sheet according to claim 1 or 2, wherein the protective layer contains ^{non-conductive particles having a volume resistivity of 1.0×10 10} Ω·cm or more. The electromagnetic wave shielding sheet according to claim 1 or 2, wherein the protective layer contains a binder resin having a weight average molecular weight of 10,000 or more. An electromagnetic wave shielding wiring circuit board, which is characterized by comprising an electromagnetic wave shielding layer formed by the electromagnetic wave shielding sheet according to any one of claims 1 to 4, a top coating, and a substrate with signal wiring and insulating properties. Material wiring board.

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