CN111800997B

CN111800997B - Electromagnetic wave shielding film

Info

Publication number: CN111800997B
Application number: CN202010489211.1A
Authority: CN
Inventors: 石冈宗悟; 柳善治
Original assignee: Tatsuta Electric Wire and Cable Co Ltd
Current assignee: Tatsuta Electric Wire and Cable Co Ltd
Priority date: 2016-09-06
Filing date: 2017-09-06
Publication date: 2023-08-29
Anticipated expiration: 2037-09-06
Also published as: CN111818784A; CN107801366A; CN111800997A; JP2018041962A; KR20180027388A; KR102394462B1; CN111818784B; JP2021010032A; CN107801366B; KR102567422B1; JP7083880B2; JP6783205B2; KR20220058520A

Abstract

The application provides an electromagnetic wave shielding film which is not easy to change color due to wiping fingerprints. The electromagnetic wave shielding film comprises an insulating layer (110) and a conductive layer (120), wherein the three-dimensional (three-dimensional) arithmetic average surface roughness Sa of the surface of the insulating layer (110) is more than 0.8 mu m.

Description

Electromagnetic wave shielding film

The application is a divisional application of an application patent application with the name of electromagnetic wave shielding film with the application number of 201710796140.8 on the application date of 2017, 09 and 06.

Technical Field

The present application relates to an electromagnetic wave shielding film.

Background

In recent years, the performance requirements of smart phones, tablet type information terminals, and the like for high-speed transmission of large-capacity data are increasing. High frequency signals are required to transmit large volumes of data at high speeds. However, the use of high frequency signals causes electromagnetic wave noise in the signal circuits on the printed wiring board, resulting in malfunction of surrounding machines. The printed wiring board is shielded from electromagnetic waves in order to prevent operation errors.

In order to shield a printed wiring board, there is a method of attaching an electromagnetic wave shielding film including an insulating layer and a shielding layer to a printed wiring board under heat and pressure to obtain a shielded printed wiring board. (for example, patent document 1).

A protective film made of polyethylene terephthalate (PET) resin or the like is attached to the surface of the insulating layer of the electromagnetic wave shielding film in order to protect the insulating layer from being injured and from foreign matter. The protective film is peeled off after the electromagnetic wave shielding film is attached to the printed wiring board. Before the protective film is stripped, the surface of the insulating layer is protected, and the shielding printed wiring board can be contacted by hands.

Prior art literature

Patent literature

JP-A2004-095566 (patent document 1).

Disclosure of Invention

Object of the application

When the protective film is peeled off and the bare hands contact the shielding printed wiring board, fingerprints may be attached to the insulating layer after the protective film is removed. The fingerprint can be discolored and the appearance is impaired. There is a problem in that the yield is low.

The adhesion of the fingerprint to the insulating layer has little effect on the electromagnetic wave shielding characteristics. Therefore, the deterioration of the yield of the shield printed wiring board can be prevented by preventing the discoloration of the insulating layer due to the adhesion of the fingerprint. The method of preventing the discoloration of the insulating layer caused by the adhesion of the fingerprint may be to remove the fingerprint. Fingerprint removal generally uses lotions, solvents. The insulating layer of the electromagnetic wave shielding film is an object, and therefore, the lotion or solvent affects the electrical characteristics of the shielding printed wiring board, and cannot be used.

Conventionally, when a fingerprint is rubbed off with a nonwoven fabric or the like for an electromagnetic wave shielding film, the surface state locally changes, which in turn causes more serious discoloration. In addition, the high-force friction surface may cause the insulating layer to peel off from the shielding layer, resulting in breakage of the electromagnetic wave shielding film.

The application provides an electromagnetic wave shielding film which is not easy to change color due to fingerprint wiping.

Means for solving the problems

The 1 st technical scheme of the electromagnetic wave shielding film comprises an insulating layer and a conducting layer, wherein the three-dimensional arithmetic average surface roughness Sa of the surface of the insulating layer is more than 0.8 mu m.

In the electromagnetic wave shielding film according to claim 1, the 85 ° glossiness of the insulating layer surface is 20 or less. The 2 nd technical scheme of the electromagnetic wave shielding film comprises an insulating layer and a conducting layer, wherein the root mean square slope Sdq of the surface of the insulating layer is more than 0.8, and the 85 DEG glossiness is less than 10.

The 3 rd technical scheme of the electromagnetic wave shielding film comprises an insulating layer and a conducting layer, wherein the deflection Ssk of the surface of the insulating layer is more than 0.1, and the glossiness of the surface of the insulating layer is less than 10 degrees.

In each embodiment of the electromagnetic wave shielding film, the insulation layer L+ value can be set below 25.

Effects of the application

The electromagnetic wave shielding film of the application can prevent discoloration caused by wiping fingerprints.

Drawings

FIG. 1 is a cross-sectional view of an electromagnetic wave shielding film in an embodiment;

fig. 2 is a cross-sectional view of an electromagnetic wave shielding film in a modification;

FIG. 3 is a plot of root mean square slope versus gloss for an insulating layer;

fig. 4 is a plot of the bias versus gloss for an insulating layer.

Detailed Description

The electromagnetic wave shielding film of the present application will be specifically described below. The present application is not limited to the following embodiments, and can be appropriately modified and applied within a range not changing the gist of the present application.

(electromagnetic wave shielding film)

Fig. 1 is a schematic cross-sectional view of an electromagnetic wave shielding film according to the present embodiment. As shown in fig. 1, the electromagnetic wave shielding film includes: insulating layer 110, conductive layer, i.e., shielding layer 120. An adhesive layer 130 may be provided on the surface of the shielding layer 120 opposite to the insulating layer 110 as needed. The adhesive layer 130 is provided to easily attach the electromagnetic wave shielding film to the printed wiring board.

Insulating layer-

The insulating layer 110 is provided for protecting the shielding layer. In the electromagnetic shielding film of the present embodiment, the three-dimensional arithmetic average surface roughness Sa, which is a parameter indicating the surface properties of the insulating layer 110, is 0.8 μm or more, more preferably 1.0 μm or more. Sa is 0.8 μm or more, and the surface of the insulating layer is hardly discolored by wiping fingerprints. The surface which hardly changes color by wiping the fingerprint means that the surface is in a state that it is difficult for the naked eye to distinguish from the non-attached portion of the fingerprint after the attached portion of the fingerprint is wiped by a wiping cloth (wiping brush) or the like.

From the viewpoint of the actual removability of fingerprint components, sa is preferably 10 μm or less, more preferably 5 μm or less, and still more preferably 3 μm or less. If Sa is small to some extent, the insulating layer is easily peeled from the later-described peeling film. Sa exceeding the above value makes it more difficult to wipe the attached fingerprint.

The surface of the insulating layer 110 from which the fingerprint was wiped off was visually observed, and the degree of discoloration of the wiped fingerprint was evaluated by sensory evaluation, thereby enabling qualitative evaluation. It can also be quantitatively evaluated by the change in surface gloss. The quantitative evaluation method can be as follows: the fingerprint was attached and erased again, and then 85 ° gloss of the surface of the insulating layer 110 was measured. In this case, the 85 ° gloss after the fingerprint is attached and re-erased is preferably 20 or less, more preferably 10 or less, and the trace of the wiped fingerprint is hardly recognized by the naked eye. Other quantitative evaluation methods are: the difference between the gloss of the surface of the insulating layer 110 after the fingerprint was attached and erased and the gloss before the fingerprint was attached was measured. That is, the smaller the difference between the glossiness of the surface of the insulating layer 110 after the fingerprint is attached and erased and the glossiness before the fingerprint is attached, the smaller the degree of discoloration due to the wiping of the fingerprint. Taking 85 ° gloss as an example, for example, the difference in gloss after adhering and re-erasing the fingerprint is preferably 4 or less, more preferably 3 or less, compared with the gloss before adhering the fingerprint, and at this time, the fingerprint unattached portion and the fingerprint erased portion are difficult to be distinguished by the naked eye.

In the electromagnetic wave shielding film of the present embodiment, to prevent discoloration due to fingerprint wiping, surface property parameters other than Sa on the surface of the insulating layer 110 may be set as follows. The root mean square slope Sdq is preferably 0.8 or more, more preferably 0.95 or more. The fingerprint adhering part reflects light more easily than the unattached part, and the fingerprint adhering part is obvious. The surface tone of the insulating layer 110 is black and the fingerprint adhesion portion becomes more conspicuous as the L value is smaller. Here, if Sdq is somewhat large, the surface energy appropriately scatters light, and fingerprint adhesion can be prevented from causing reflection enhancement. In particular, when the L+ value is 25 or less, increasing Sdq can effectively achieve the effect that the attached portion of the fingerprint is inconspicuous.

In order to facilitate peeling of a later-described release film from an insulating layer, sdq is preferably 10 or less, more preferably 7.0 or less, and still more preferably 3.0 or less.

The deviation Ssk is preferably 0.1 or more, more preferably 0.5 or more, and still more preferably 1.0 or more. Regarding Ssk, the convex and concave portions of the uneven surface with respect to the average surface exhibit symmetry, and as Ssk increases, the convex component with respect to the average surface decreases, and the portions (the valleys and the flat portions) other than the convex relatively increase. Thus, increasing Ssk to some extent makes it easier to wipe the fingerprint.

Further, ssk is preferably 10 or less, more preferably 5.0 or less, and still more preferably 3.0 or less. Ssk in the above range can achieve an effect of easily peeling the insulating layer from the peeling film described later.

The maximum peak height Sp is preferably 8.0 μm or more. The root mean square deviation Sq is preferably 1.0 μm or more, more preferably 1.2 μm or more, and still more preferably 1.3 μm or more. The protruding peak height Spk is preferably 1.0 μm or more, more preferably 1.5 μm or more, and still more preferably 1.7 μm or more. The void volume Vvc of the central portion is preferably 1.1ml/m ² Above, 1.3ml/m ² The above is more preferable. The peak solid volume Vmp is preferably 0.07ml/m ² Above, 0.08ml/m ² The above is more preferably 0.1ml/m ² The above is more preferable.

Further, sp is preferably 20 μm or less, more preferably 18 μm or less, still more preferably 15 μm or less. Sq is preferably 10 μm or less, more preferably 5.0 μm or less, and still more preferably 3.0 μm or less. Spk is preferably 10 μm or less, more preferably 5.0 μm or less, and still more preferably 3.0 μm or less. Vvc at 10ml/m ² The following is preferable, 5.0ml/m ² The following is more preferable, 3.0ml/m ² The following is preferable. Vmp is 1.0ml/m ² The following is preferable, 0.5ml/m ² The following is more preferable, 0.3ml/m ² The following is preferable. Sp, spk, vvc, vmp each of the above numerical ranges has an effect of easily peeling an insulating layer from a peeling film described later.

In addition, other parameters may be used to define the surface that is not likely to be discolored by wiping the fingerprint, instead of Sa. For example, in order to obtain a surface which is less likely to be discolored by wiping a fingerprint, a surface having a small proportion of the convex portions with respect to the average surface and a high convex portion height is preferably used. Thus, the following options are available: sp is 7.0 μm or more, preferably 8.0 μm or more and Ssk is 0 or more, preferably 0.1 or more. Furthermore, it is possible to select: sp is 7.0 μm or more, preferably 8.0 μm or more and Sdq is 0.8 or more, preferably 0.9 or more. Furthermore, it is possible to select: sq is 1.0 μm or more, and Ssk is 0 or more, preferably 0.1 or more. Furthermore, it is possible to select: sq is 1.0 μm or more, preferably 1.2 μm or more, and Sdq is 0.8 or more, preferably 0.9 or more. Furthermore, it is possible to select: spk is 1.0 μm or more and Ssk is 0 or more, preferably 0.1 or more. Furthermore, it is possible to select: spk is 1.0 μm or more, preferably 1.5 μm or more, and Sdq is 0.8 or more, preferably 0.9 or more.

Furthermore, it is possible to choose: sp is 20 μm or less, preferably 18 μm or less, and Ssk is 10 or less, preferably 5 or less. Furthermore, it is possible to select: sp is 20 μm or less, preferably 18 μm or less, and Sdq is 10 or less, preferably 3.0 or less. Furthermore, it is possible to select: sq is 10 μm or less, preferably 5 μm or less, and Ssk is 10 or less, preferably 5.0 or less. Furthermore, it is possible to select: sq is 10 μm or less, preferably 5.0 μm or less, and Sdq is 10 or less, preferably 3.0 or less. Furthermore, it is possible to select: spk is 10 μm or less, preferably 5.0 μm or less, and Ssk is 10 or less, preferably 5.0 or less. Furthermore, it is possible to select: spk is 10 μm or less, preferably 5.0 μm or less, and Sdq is 10 or less, preferably 3.0 or less. Setting the above numerical range can achieve the effect of easily peeling the insulating layer from the peeling film.

The measured values of the surface properties in the present application are based on ISO 25178-6:2010, a specific measurement method will be described in examples.

In the insulating layer 110, the 60 ° gloss before the attachment of the fingerprint is preferably 3 or less, more preferably 2 or less, and still more preferably 1 or less. The 85 ° gloss is preferably 20 or less, more preferably 15 or less, still more preferably 10 or less, further preferably 5 or less, further preferably 3 or less.

When the glossiness before the attachment of the fingerprint is set to the above value, the surface of the insulating layer 110 is appropriately scattered, and the glossiness can be appropriately controlled. This further prevents discoloration of the fingerprint by wiping.

Further, the insulating layer 110 has a 60 ° glossiness of preferably 3 or less, more preferably 2 or less, more preferably 1 or less, and a 85 ° glossiness of preferably 20 or less, more preferably 15 or less, more preferably 10 or less, more preferably 5 or less, more preferably 3 or less before the attachment of the fingerprint, so that a surface which is extremely less likely to be discolored by wiping the fingerprint can be obtained.

The 60 ° gloss and 85 ° gloss in the present application can be measured by the methods shown in examples.

Further, sdq is 0.8 or more preferably 0.9 or more and 85 ° gloss is 10 or less, preferably 5 or less, more preferably 3 or less, so that discoloration due to wiping of fingerprints is not likely.

Further, ssk is more than 0, preferably 0.1 or more, more preferably 0.5 or more, and 85 ° glossiness is 10 or less, preferably 5 or less, more preferably 3 or less, so that discoloration due to wiping of the fingerprint is not liable to occur.

The method for obtaining the insulating layer 110 in the present application is not particularly limited, and a known method can be used. For example, the following can be mentioned: the resin composition for forming the insulating layer 110 is coated on the surface of the release film having the concave-convex shape due to the embossing process, and dried, thereby transferring the concave-convex shape of the release film to the insulating layer 110. The following method may be used: the resin composition containing the particles for forming the irregularities is coated on the surface of the shielding layer 120 and dried to form the insulating layer 110 having the irregularities. The following method may be used: and dry ice is blown to the surface of the insulating layer 110. The following method may be used: after the active energy ray-curable composition is applied to the surface of the shielding layer 120, the surface is pressed with a mold having a concave-convex shape, the curable composition layer is cured, and then the mold is peeled off. Other known methods may also be used.

Among them, from the viewpoint of productivity, a method of coating a resin composition containing particles for forming irregularities and drying to obtain the insulating layer 110 having the irregularities is preferable. In this case, the particles for forming irregularities are not particularly limited, and for example, resin fine particles or inorganic fine particles can be used. The resin particles may be acrylic resin particles, polyacrylonitrile particles, polyurethane particles, polyamide particles, polyimide particles, or the like. The inorganic fine particles may be calcium carbonate fine particles, calcium silicate fine particles, clay, kaolin, talc, silica fine particles, glass fine particles, diatomaceous earth, mica powder, alumina fine particles, magnesium oxide fine particles, zinc oxide fine particles, barium sulfate fine particles, aluminum sulfate fine particles, calcium sulfate fine particles, magnesium sulfate fine particles, or the like. The resin fine particles and the inorganic fine particles may be used alone or in combination of several kinds. Inorganic fine particles are preferable from the viewpoint of improving the scratch resistance of the insulating layer.

From the viewpoint of producing appropriate irregularities on the surface of the insulating layer 110 to obtain a certain surface property, the particles for forming irregularities preferably have an average particle diameter of 50% of 2 μm or more, more preferably 4 μm or more, and still more preferably 10 μm or more. Further, from the viewpoint of preventing whitening of the insulating layer, the 50% average particle diameter is preferably 30 μm or less, more preferably 20 μm or less.

The amount of particles for forming irregularities in the insulating layer 110 is preferably 3 mass% or more, more preferably 5 mass% or more, from the viewpoint of obtaining a certain surface property. Further, from the viewpoint of preventing whitening of the insulating layer, it is preferably 30% by mass or less, more preferably 20% by mass or less, and still more preferably 17% by mass or less.

A black colorant may be added to the insulating layer 110. The L+ value of the insulating layer 110 can be reduced by adding black coloring agent, so that marks (characters, figures and the like) printed on the surface of the insulating layer can be easily identified. When the mark printed on the insulating layer 110 is white, the L value is preferably 25 or less, more preferably 20 or less, and still more preferably 18 or less. The L value in the present application can be measured according to JIS Z8781-4 (2013).

The black colorant may be a black pigment or a mixed pigment in which several pigments are blackened by subtractive color mixing, or the like. For example, one or a combination of carbon black, ketjen black, carbon Nanotubes (CNT), perylene black, titanium black, iron black, aniline black, and the like can be used as the black pigment. The mixed pigment may be used in combination with, for example, pigments of red, green, blue, yellow, violet, cyan, magenta, and the like.

The particle size of the black colorant is not limited as long as the desired L+ value can be obtained, but in view of dispersibility, reduction in L+ value, and the like, the average primary particle size is preferably 20nm or more, and preferably 100nm or less. The average primary particle diameter of the black colorant can be obtained from an average value of about 20 primary particles observed in an image magnified 5 to 100 tens of thousands of times by a Transmission Electron Microscope (TEM).

From the viewpoint of reducing the L+ value, the addition amount of the black coloring agent to the insulating layer 110 is preferably 0.5 mass% or more, more preferably 1 mass% or more. The black colorant may or may not be added as desired.

Gloss also affects the visibility of the printed content. From the viewpoint of visibility of the printed content, the 60 ° glossiness of the insulating layer 110 is preferably 3 or less, more preferably 2 or less, and still more preferably 1 or less. Further, the 85 ° gloss is preferably 20 or less, more preferably 15 or less, more preferably 10 or less, more preferably 5 or less, more preferably 3 or less.

The insulating layer 110 preferably satisfies a certain mechanical strength, chemical resistance, and heat resistance in addition to the required insulation properties.

The resin material constituting the insulating layer is not particularly limited as long as it has sufficient insulation properties, and for example, a thermoplastic resin composition, a thermosetting resin composition, an active energy ray-curable composition, and the like can be used.

The thermoplastic resin composition is not particularly limited, and a styrene resin composition, a vinyl acetate resin composition, a polyester resin composition, a polyethylene resin composition, a polypropylene resin composition, an imide resin composition, an acrylic resin composition, and the like can be used. The thermosetting resin composition is not particularly limited, and phenol resin compositions, epoxy resin compositions, polyurethane resin compositions, melamine resin compositions, alkyd resin compositions and the like can be used. The active energy ray-curable composition is not particularly limited, and for example, a polymerizable compound having at least 2 (meth) acryloyloxy groups in the molecule can be used. The above-mentioned compositions may be used singly or in combination of 2 or more.

The insulating layer 110 may contain, in addition to the fine particles and the colorant, a curing accelerator, a thickener, an antioxidant, a pigment, a dye, a plasticizer, an ultraviolet absorber, a defoaming agent, a leveling agent, a filler, a flame retardant, a viscosity regulator, an antiblocking agent, and the like, as necessary.

The thickness of the insulating layer 110 is not particularly limited, and may be appropriately set as needed, but is preferably 1 μm or more, more preferably 4 μm or more, from the viewpoint of sufficiently protecting the shielding layer. Further, from the viewpoint of securing the bendability of the electromagnetic wave shielding film, it is preferably 20 μm or less, more preferably 10 μm or less.

Shielding layer-

The shielding layer 120 of the present embodiment may be a metal layer. The shielding layer 120 may be a metal layer made of any one of nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, zinc, or a metal containing two or more of them. The material and thickness of the metal layer may be appropriately selected according to the desired electromagnetic wave shielding effect and repeated bending and sliding resistance. The thickness of the metal layer is preferably 0.1 μm or more from the viewpoint of obtaining a sufficient electromagnetic wave shielding effect. From the viewpoints of productivity, bendability, etc., it is preferably 8 μm or less. The metal layer may be formed by: electroplating, electroless plating, sputtering, electron beam evaporation, vacuum evaporation, CVD, organometallic, and the like. The metal layer may be composed of a metal foil, metal nanoparticles, scaly metal particles, or the like.

Adhesive layer

The electromagnetic wave shielding film of the present embodiment may contain the adhesive layer 130 on the opposite side of the shielding layer 120 from the insulating layer 110. The adhesive layer 130 may be made of a resin composition having adhesive properties. The adhesive resin composition is not particularly limited, and a thermoplastic resin composition such as a styrene resin composition, a vinyl acetate resin composition, a polyester resin composition, a polyethylene resin composition, a polypropylene resin composition, an imide resin composition, an amide resin composition, an acrylic resin composition, a thermosetting resin composition such as a phenol resin composition, an epoxy resin composition, a polyurethane resin composition, a melamine resin composition, an alkyd resin composition, and the like can be used. These may be used singly or in combination.

The adhesive layer 130 may be provided to have an isotropic conductive or anisotropic conductive layer as needed. In order to form the adhesive layer 130 into an isotropic or anisotropic conductive layer, conductive fine particles may be added to the adhesive resin composition.

The conductive fine particles are not particularly limited, and metal fine particles, carbon nanotubes, carbon fibers, metal fibers, and the like can be used. For example, fine metal particles such as silver powder, copper powder, nickel powder, solder powder, and aluminum powder can be used. The metal-coated particles may be formed by coating a copper powder with a metal such as silver-coated copper powder, polymer particles, or glass beads obtained by silver plating copper powder. Among them, low-priced copper powder or silver-coated copper powder is preferable from the viewpoint of economy.

The 50% average particle diameter of the conductive particles is not particularly limited, but is preferably 0.5 μm or more in view of obtaining good conductivity. In addition, from the viewpoint of controlling the thickness of the conductive adhesive layer, 15 μm or less is preferable.

The shape of the conductive particles is not particularly limited, and spherical, flat, scaly, dendritic, and the like can be appropriately selected.

The thickness of the adhesive layer 130 can be adjusted as needed, and is preferably 0.5 μm or more in order to obtain good adhesion. In addition, from the viewpoint of controlling the thickness of the electromagnetic wave shielding film, it is preferably 20 μm or less.

The electromagnetic wave shielding film has been described above as having the insulating layer 110, the shielding layer 120, and the adhesive layer 130, but the structure shown in fig. 2, that is, the insulating layer 110 and the isotropic conductive adhesive layer 140 may be used.

The insulating layer 110 may have the same structure as the electromagnetic wave shielding film of fig. 1. The isotropic conductive adhesive layer 140 may be composed of an adhesive resin composition and conductive fine particles similar to the adhesive layer 130. The isotropic conductive adhesive layer 140 functions as a shielding layer.

Method for producing shielding films

The electromagnetic wave shielding film of the present embodiment can be manufactured by a known manufacturing method. An example of this is described below.

First, an adhesive layer 130 having conductivity is formed on a support film whose surface has been subjected to a release treatment. Specifically, an adhesive layer composition solution containing a material for constituting the adhesive layer 130 is applied to the surface of the support film, and dried to form the adhesive layer 130.

Then, a shielding layer 120 is formed on the surface of the adhesive layer 130. Specifically, the following method can be adopted: a method of bonding a metal foil having a predetermined thickness to the adhesive layer 130, a method of forming a metal layer on the surface of the adhesive layer 130 by vapor deposition, metal plating, or the like.

Then, an insulating layer 110 is formed on the surface of the shielding layer 120. Specifically, the following method can be adopted: a method of applying an insulating layer composition solution containing a material for constituting the insulating layer 110 to the surface of the shielding layer 120 and drying.

Then, the support film is peeled off to obtain an electromagnetic wave shielding film.

The adhesive layer 130 may be used as the isotropic conductive adhesive layer 140 and the insulating layer 110 may be formed on the surface of the isotropic conductive adhesive layer 140.

In order to maintain the surface texture of the surface of the insulating layer 110 in a constant state, the surface of the insulating layer 110 may be subjected to a treatment such as sandblasting.

The above examples are made from the adhesive layer 130 side, or may be made sequentially from the insulating layer 110 side. The following manner can be adopted at this time: the surface property of the insulating layer 110 is set to a constant state by transferring the minute pattern onto the surface of the insulating layer 110 using the support film having the minute pattern.

Examples

The present application is described in detail below by way of examples. The following examples are merely illustrative and are not intended to limit the present application.

< manufacture of electromagnetic wave shielding film >

Preparation of the adhesive layer

100 parts by mass of bisphenol A epoxy resin (Mitsubishi chemical production, jER 1256), 0.1 part by mass of hardener (Mitsubishi chemical production, ST 14) and 25 parts by mass of dendritic silver-coated copper powder (average particle diameter 13 μm) were added to toluene to obtain a solid content of 20% by mass, and the mixture was stirred and mixed to prepare a conductive adhesive layer composition. The obtained adhesive layer composition was coated on a PET film having its surface release-treated, and the adhesive layer was formed on the surface of the support film by heat drying.

Fabrication of the shielding layer

A rolled copper foil having a thickness of 2 μm was bonded to the surface of the obtained adhesive layer.

Fabrication of an insulating layer

An insulating layer composition was prepared by using 100 parts by mass of bisphenol A type epoxy resin (Mitsubishi chemical production, jER 1256), 0.1 part by mass of (Mitsubishi chemical production, ST 14) as a hardener, 15 parts by mass of CARBON particles (TOKAI CARBON production, TOKABLACK#8300/F) as a black colorant, and a certain amount of particles for forming irregularities so that the solid content was 20% by mass, with respect to toluene. The composition was coated on the obtained shielding layer, and the electromagnetic wave shielding film was obtained by heating and drying.

< method for evaluating characteristics >)

[ measurement of surface Property of insulating layer ]

After measuring any 5 places on the surface of the insulating layer of the electromagnetic wave shielding film by using a confocal microscope (20 times of an objective lens, OPTELICS HYBRID, manufactured by Lasertec Co.), the surface tilt was corrected by using a data analysis software (LMey 7), according to ISO 25178-6:2010, the surface properties are measured, and the arithmetic average value is obtained. The cut-off wavelength of the S filter was 0.0025mm and the cut-off wavelength of the L filter was 0.8mm.

[ measurement of L+ value ]

L+ values were measured by an integrating sphere spectrophotometer (X-Rite, ci64, tungsten light source). And the a and b values are measured.

[ evaluation of discoloration by fingerprint ]

The surface of the rubber stopper with the diameter of 2.5cm is roughened by # 240 sand paper. Then, 5. Mu.L of a manual contamination solution (JIS C9606: manufactured by Ivory corporation) was dropped onto the surface of the PET film, and the roughened surface of the rubber stopper was pressed against the manual contamination solution (500 g for 10 seconds). Then, the rubber plug to which the artificial contamination liquid was attached was pressed against the surface of the insulating layer (500 g for 10 seconds) to attach the artificial contamination liquid. Then, the nonwoven fabric (WYPALX 70, manufactured by Kelvin, nippon PAPER CRECIA) was cut to an angle of about 3cm, placed on an artificial contaminated liquid, and reciprocated 20 times under a load of 500g (single pass distance=10 cm), thereby wiping. The 85 gloss difference was obtained by subtracting the 85 gloss value before the artificial staining solution was adhered from the 85 gloss value after wiping. The 60 ° gloss and 85 ° gloss were measured by a BYK Gardner seed micro-gloss meter (portable gloss meter).

Example 1

The particles for forming irregularities to be added to the insulating layer were silica particles having an average particle diameter of 7. Mu.m, and the amount of the particles was 40 parts by mass. The obtained electromagnetic wave shielding film had an insulating layer surface of Sa of 1.02 μm, sdq of 1.26, ssk of 2.22. The 60 DEG glossiness before the artificial staining solution is attached is 1.1, and the 60 DEG glossiness after the fingerprint wiping is 5.2. The 85 DEG glossiness before artificial staining solution adhesion is 1.5, the 85 DEG glossiness after fingerprint wiping is 1.9, and the 85 DEG glossiness difference is 0.4. The L+ value is 21.3.

Example 2

An electromagnetic wave shielding film was obtained in the same manner as in example 1, except that the amount of the particles for forming irregularities was 50 parts by mass. The obtained electromagnetic wave shielding film had an insulating layer surface of Sa of 1.18 μm, sdq of 1.26, ssk of 2.21. The 60 degree gloss before attachment of the artificial staining solution was 0.5, and the 60 degree gloss after fingerprint wiping was 6.7. The 85 DEG glossiness before the artificial staining solution is attached is 1.8, the 85 DEG glossiness after the fingerprint wiping is 2.4, and the 85 DEG glossiness difference is 0.6. The L+ value is 20.1.

Example 3

An electromagnetic wave shielding film was obtained in the same manner as in example 1, except that the amount of the particles for forming irregularities was 35 parts by mass. The obtained electromagnetic wave shielding film had an insulating layer surface of Sa of 1.31 μm, sdq of 0.95, ssk of 1.47. The 60 DEG glossiness before the artificial staining solution is attached is 0.5, and the 60 DEG glossiness after the fingerprint wiping is 1.8. The 85 DEG glossiness before the artificial staining solution is attached is 1.7, the 85 DEG glossiness after the fingerprint wiping is 2.5, and the 85 DEG glossiness difference is 0.8. The L+ value is 20.1.

Example 4

An electromagnetic wave shielding film was obtained in the same manner as in example 1, except that silica particles having an average particle diameter of 9 μm were used as the particles for forming irregularities, and the amount of the silica particles used was 40 parts by mass. The obtained electromagnetic wave shielding film had an insulating layer surface of Sa of 0.92 μm, sdq of 1.38, ssk of 3.10. The 60 DEG glossiness before artificial staining solution adhesion is 2.1, and the 60 DEG glossiness after fingerprint wiping is 6.1. The 85 DEG glossiness before the artificial staining solution is attached is 2.1, the 85 DEG glossiness after the fingerprint wiping is 2.6, and the 85 DEG glossiness difference is 0.5. The L+ value is 23.5.

Example 5

An electromagnetic wave shielding film was obtained in the same manner as in example 4, except that the amount of the particles for forming irregularities was 50 parts by mass. The obtained electromagnetic wave shielding film had a Sa of 0.92 μm, a Sdq of 1.02, and a Ssk of 2.53 on the insulating layer surface. The 60 degree gloss before attachment of the artificial staining solution was 1.5, and the 60 degree gloss after fingerprint wiping was 4.9. The 85 DEG glossiness before the artificial staining solution is attached is 1.7, the 85 DEG glossiness after the fingerprint wiping is 3.2, and the 85 DEG glossiness difference is 1.5. The L+ value is 24.3.

Example 6

An electromagnetic wave shielding film was obtained in the same manner as in example 1, except that silica particles having an average particle diameter of 5 μm were used as the particles for forming the irregularities, and the amount of the silica particles was 70 parts by mass. The obtained electromagnetic wave shielding film had an insulating layer surface of Sa of 1.05 μm, sdq of 0.92, ssk of 0.80. The 60 degree gloss before attachment of the artificial staining solution was 0.5, and the 60 degree gloss after fingerprint wiping was 2.4. The 85 DEG glossiness before artificial staining solution adhesion is 4.6, the 85 DEG glossiness after fingerprint wiping is 6.3, and the 85 DEG glossiness difference is 1.7. The L+ value is 23.6.

Example 7

An electromagnetic wave shielding film was obtained in the same manner as in example 1, except that 60 parts by mass of silica particles having an average particle diameter of 7 μm was used as the particles for forming irregularities. The obtained electromagnetic wave shielding film had an insulating layer surface of Sa of 1.11 μm, sdq of 1.12, ssk of 1.46. The 60 degree gloss before attachment of the artificial staining solution was 0.4, and the 60 degree gloss after fingerprint wiping was 1.9. The 85 DEG glossiness before the artificial staining solution is attached is 3.8, the 85 DEG glossiness after the fingerprint wiping is 6.5, and the 85 DEG glossiness difference is 2.7. The L+ value is 21.9.

Comparative example 1

An electromagnetic wave-shielding film was obtained in the same manner as in example 1 except that silica particles having an average particle diameter of 2 μm were used as the particles for forming irregularities and the amount used was 60 parts by mass. The obtained electromagnetic wave shielding film had an insulating layer surface of Sa of 0.57 μm, sdq of 0.80, ssk of 0.07. The 60 DEG glossiness before artificial staining solution adhesion is 0.8, and the 60 DEG glossiness after fingerprint wiping is 2.2. The 85 DEG glossiness before artificial staining solution adhesion is 16.8, the 85 DEG glossiness after fingerprint wiping is 26.7, and the 85 DEG glossiness difference is 9.9. The L+ value is 24.4.

Comparative example 2

An electromagnetic wave shielding film was obtained in the same manner as in comparative example 1, except that the amount of the particles for forming irregularities was 65 parts by mass. The obtained electromagnetic wave shielding film had an insulating layer surface of Sa of 0.66 μm, sdq of 0.90 and Ssk of-0.22. The 60 DEG glossiness before artificial staining solution adhesion is 0.5, and the 60 DEG glossiness after fingerprint wiping is 3.9. The 85 DEG glossiness before artificial staining solution adhesion is 15.9, the 85 DEG glossiness after fingerprint wiping is 30.4, and the 85 DEG glossiness difference is 14.5. The L+ value is 21.9.

Comparative example 3

An insulating layer composition free of particles for forming irregularities was prepared. The insulating layer was obtained by applying the insulating layer to the surface of the support film and allowing the support film to dry and harden. The support film was a release-treated PET film having a surface with irregularities (sa=0.60 μm, sdq=0.61) due to embossing, and a thickness of 20 μm. Next, an insulating layer was laminated on the shielding layer fabricated in the same manner as in example 1, and then the support film was peeled off to obtain an electromagnetic wave shielding film. The obtained electromagnetic wave shielding film had an insulating layer surface of Sa of 0.58 μm, sdq of 0.65 and Ssk of-0.78. The 60 DEG glossiness before artificial staining solution adhesion is 4.2, and the 60 DEG glossiness after fingerprint wiping is 9.1. The 85 DEG glossiness before artificial staining solution adhesion is 34.0, the 85 DEG glossiness after fingerprint wiping is 42.8, and the 85 DEG glossiness difference is 8.8. The L+ value is 25.3.

Comparative example 4

An electromagnetic wave shielding film was obtained in the same manner as in comparative example 3, except that a film having a surface with irregularities (sa=0.6 μm, sdq=0.47 μm) using silica fine particles was used as a support film. The obtained electromagnetic wave shielding film had an insulating layer surface of Sa of 0.59 μm, sdq of 0.49, ssk of-0.85. The 60 DEG glossiness before artificial staining solution adhesion is 7.6, and the 60 DEG glossiness after fingerprint wiping is 13.3. The 85 DEG glossiness before artificial staining solution adhesion is 38.7, the 85 DEG glossiness after fingerprint wiping is 48.0, and the 85 DEG glossiness difference is 9.3. The L+ value is 28.2.

Comparative example 5

An electromagnetic wave shielding film was obtained in the same manner as in comparative example 3, except that a film having a surface with a concave-convex shape (sa=0.47 μm, sdq=0.59 μm) by sand cushion processing was used as a support film. The obtained electromagnetic wave shielding film had an insulating layer surface of Sa of 0.45 μm, sdq of 0.58, ssk of-0.25. The 60 DEG glossiness before artificial staining solution adhesion is 5.4, and the 60 DEG glossiness after fingerprint wiping is 11.9. The 85 DEG glossiness before artificial staining solution adhesion is 26.1, the 85 DEG glossiness after fingerprint wiping is 51.0, and the 85 DEG glossiness difference is 24.9. The L+ value is 27.2.

Comparative example 6

An electromagnetic wave shielding film was obtained in the same manner as in comparative example 3, except that a film having a surface with a concave-convex shape (sa=0.45 μm, sdq=0.56 μm) by sand cushion processing was used as a support film. The obtained electromagnetic wave shielding film had an insulating layer surface of Sa of 0.45 μm, sdq of 0.54, ssk of-0.60. The 60 DEG glossiness before artificial staining solution adhesion is 9.2, and the 60 DEG glossiness after fingerprint wiping is 16.6. The 85 DEG glossiness before artificial staining solution adhesion is 30.4, the 85 DEG glossiness after fingerprint wiping is 54.7, and the 85 DEG glossiness difference is 24.3. The L+ value is 27.2.

Comparative example 7

An electromagnetic wave shielding film was obtained in the same manner as in comparative example 3, except that a film having a surface with a concave-convex shape (sa=0.51 μm, sdq=0.55 μm) by sand cushion processing was used as a support film. The obtained electromagnetic wave shielding film had an insulating layer surface of Sa of 0.49 μm, sdq of 0.55, ssk of-0.37. The 60 DEG glossiness before artificial staining solution adhesion is 8.6, and the 60 DEG glossiness after fingerprint wiping is 16.7. The 85 DEG glossiness before artificial staining solution adhesion is 21.6, the 85 DEG glossiness after fingerprint wiping is 56.7, and the 85 DEG glossiness difference is 35.1. The L+ value is 27.2.

Comparative example 8

An electromagnetic wave shielding film was obtained in the same manner as in comparative example 3, except that a film in which silica fine particles were used so that the surface had a concave-convex shape (sa=0.43 μm, sdq=0.40 μm) was used as the support film. The obtained electromagnetic wave shielding film had an insulating layer surface of Sa of 0.42 μm, sdq of 0.38 μm, ssk of-1.19. The 60 degree gloss before attachment of the artificial staining solution was 11.7, and the 60 degree gloss after fingerprint wiping was 17.9. The 85 DEG glossiness before artificial staining solution adhesion is 52.4, the 85 DEG glossiness after fingerprint wiping is 58.9, and the 85 DEG glossiness difference is 6.5. The L+ value is 27.9.

Comparative example 9

An electromagnetic wave shielding film was obtained in the same manner as in example 1 except that silica particles having an average particle diameter of 5 μm were used as particles to be added to the insulating layer, and the amount to be used was 40 parts by mass. The obtained electromagnetic wave shielding film had an insulating layer surface of Sa of 0.49 μm, sdq of 0.74 and Ssk of-0.77. The 60 DEG glossiness before artificial staining solution adhesion is 1.0, and the 60 DEG glossiness after fingerprint wiping is 19.8. The 85 DEG glossiness before artificial staining solution adhesion is 33.2, the 85 DEG glossiness after fingerprint wiping is 61.0, and the 85 DEG glossiness difference is 27.8. The L+ value is 22.0.

Comparative example 10

An electromagnetic wave shielding film was obtained in the same manner as in comparative example 3, except that a film in which silica fine particles were used so that the surface had a concave-convex shape (sa=0.36 μm, sdq=0.36 μm) was used as the support film. The obtained electromagnetic wave shielding film had an insulating layer surface of Sa of 0.35 μm, sdq of 0.36, ssk of-0.31. The 60 DEG glossiness before artificial staining solution adhesion is 6.9, and the 60 DEG glossiness after fingerprint wiping is 12.1. The 85 DEG glossiness before artificial staining solution adhesion is 58.6, the 85 DEG glossiness after fingerprint wiping is 63.0, and the 85 DEG glossiness difference is 4.4. The L+ value is 26.3.

Comparative example 11

An electromagnetic wave shielding film was obtained in the same manner as in comparative example 3, except that a film having a surface with irregularities (sa=0.46 μm, sdq=0.65 μm) using silica fine particles was used as a support film. The obtained electromagnetic wave shielding film had an insulating layer surface of Sa of 0.43 μm, sdq of 0.62, ssk of-0.40. The 60 DEG glossiness before artificial staining solution adhesion is 2.4, and the 60 DEG glossiness after fingerprint wiping is 16.6. The 85 DEG glossiness before artificial staining solution adhesion is 42.6, the 85 DEG glossiness after fingerprint wiping is 71.8, and the 85 DEG glossiness difference is 29.2. The L+ value is 28.2.

Comparative example 12

An electromagnetic wave shielding film was obtained in the same manner as in comparative example 3, except that a film in which silica fine particles were used so that the surface had a concave-convex shape (sa=0.31 μm, sdq=0.58 μm) was used as the support film. The obtained electromagnetic wave shielding film had an insulating layer surface of Sa of 0.34 μm, sdq of 0.55, ssk of-0.48. The 60 DEG glossiness before artificial staining solution adhesion is 4.3, and the 60 DEG glossiness after fingerprint wiping is 30.2. The 85 DEG glossiness before artificial staining solution adhesion is 64.2, the 85 DEG glossiness after fingerprint wiping is 80.6, and the 85 DEG glossiness difference is 16.4. The L+ value is 24.4.

Comparative example 13

An insulating layer was coated on the surface of the support film and dried and cured in the same manner as in comparative example 3, except that a PET film having a surface with irregularities (sa=1.5 μm, sdq=4.89 μm) by embossing was used as the support film. Next, an insulating layer was bonded to the shield layer fabricated in the same manner as in example 1. Then, when the support film is peeled off, the support film and the insulating layer firmly adhere to each other, and the interface between the insulating layer and the shielding layer is broken at a part. The surface of the insulating layer on which no interface breakage was observed had Sa of 1.3 μm, sdq of 3.6 and Ssk of-1.60. In addition, in this comparative example, the interface was broken, and the gloss and L.times.value were not measured.

Table 1 shows the evaluation of the surface properties and discoloration of the electromagnetic wave shielding films of the examples and comparative examples. The values Sp, sq, spk, vvc, vmp, a and b are also shown in Table 1.

[ Table 1 ]

Fig. 3 shows the relationship between Sdq and 85 ° gloss. At least when Sdq is 0.8 or more and 85 ° gloss is 10 or less, the difference in gloss is 4 or less, and discoloration due to wiping of fingerprints is not likely to occur.

Fig. 4 shows the relationship between Ssk and 85 ° gloss. At least when Ssk is 0.1 or more and the 85 DEG gloss is 10 or less, the difference in gloss is 4 or less, and discoloration due to wiping of fingerprints is not liable to occur.

Practicality of use

The electromagnetic wave shielding film of the present application is less likely to be discolored by wiping fingerprints, and is useful as an electromagnetic wave shielding film for printed wiring boards and the like.

Symbol description

110. Insulating layer

120. Shielding layer

130. Adhesive layer

140. Isotropically conductive adhesive layer

Claims

1. An electromagnetic wave shielding film comprises an insulating layer and a shielding layer;

wherein the maximum peak height Sp of the surface of the insulating layer is 8.0 μm or more and 20 μm or less, and the degree of deviation Ssk of the surface of the insulating layer is 0 or more and 10 or less,

the maximum peak height Sp and the skewness Ssk are measured based on ISO 25178-6:2010.

2. The electromagnetic wave shielding film according to claim 1, wherein:

the 85 DEG glossiness of the surface of the insulating layer before the attachment of the fingerprint is below 20.

3. An electromagnetic wave shielding film comprises an insulating layer and a shielding layer;

wherein the root mean square deviation Sq of the surface of the insulating layer is 1.0 μm or more and 10 μm or less, and the deviation Ssk of the surface of the insulating layer is 0 or more and 10 or less,

the root mean square deviation Sq and the deviation Ssk are measured based on ISO 25178-6:2010.

4. An electromagnetic wave shielding film comprises an insulating layer and a shielding layer;

wherein the height Spk of the protruding peak of the insulating layer surface is 1.0 μm or more and 10 μm or less, and the deflection Ssk of the insulating layer surface is 0 or more and 10 or less,

the protruding peak height Spk and the bias Ssk are measured based on ISO 25178-6:2010.

5. The electromagnetic wave shielding film according to any one of claims 1 to 4, wherein:

the L-value of the insulating layer is below 25.