CN111800997A - Electromagnetic wave shielding film - Google Patents

Abstract

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

Description

Electromagnetic wave shielding film

This application is a divisional application for an invention patent application with an application date of September 6, 2017, an application number of 201710796140.8, and the title of "electromagnetic wave shielding film".

technical field

The invention relates to an electromagnetic wave shielding film.

Background technique

In recent years, the performance requirements for high-speed transmission of large-capacity data such as smart phones and tablet-type information terminals have become higher and higher. High-frequency signals are required to transmit large-capacity data at high speed. However, using high-frequency signals will generate electromagnetic wave noise from the signal circuit on the printed wiring board, causing the surrounding machines to operate incorrectly. To prevent operating errors, the printed wiring board is shielded from electromagnetic waves.

In order to shield a printed wiring board, there has been a method of applying heat and pressure to an electromagnetic wave shielding film including an insulating layer and a shielding layer to a printed wiring board to obtain a shielded printed wiring board. (For example, Patent Document 1).

A protective film made of polyethylene terephthalate (PET) resin is attached to the surface of the insulating layer of the electromagnetic wave shielding film to protect the insulating layer from damage and 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 peeled off, the surface of the insulating layer is protected, and the shielded printed wiring board can be touched with bare hands.

prior art literature

Patent Literature

[Patent Document 1] Japanese Patent Laid-Open No. 2004-095566.

SUMMARY OF THE INVENTION

Invention subject

After the protective film is peeled off, if the bare hand touches the shielded printed wiring board, fingerprints may be attached to the insulating layer after the protective film is removed. Fingerprints will be discolored and the appearance will be damaged. There is a problem of low yield.

Fingerprints attached to the insulating layer have little effect on the electromagnetic wave shielding properties. Therefore, as long as the discoloration of the insulating layer due to the adhesion of fingerprints is prevented, the yield of the shielded printed wiring board can be prevented from being lowered. A method to prevent discoloration of the insulating layer caused by attached fingerprints may be to remove the fingerprints. Fingerprint removal generally uses lotions (washing agents) and solvents. If the object is the insulating layer of the electromagnetic wave shielding film, the detergent (washing agent) and solvent will affect the electrical characteristics of the shielded printed wiring board, so it cannot be used.

In the past, for electromagnetic wave shielding films, if the surface was rubbed by wiping off fingerprints with a non-woven fabric or the like, the surface state would change locally, and on the contrary, the discoloration would be more serious. In addition, vigorously rubbing the surface will cause the insulating layer to peel off from the shielding layer, resulting in damage to the electromagnetic wave shielding film.

The subject of the present invention is to provide an electromagnetic wave shielding film that is less likely to be discolored by wiping off fingerprints.

solution

The first aspect of the electromagnetic wave shielding film of the present invention includes an insulating layer and a conductive layer, and the three-dimensional (three-dimensional) arithmetic mean surface roughness Sa of the surface of the insulating layer is 0.8 μm or more.

In the first aspect of the electromagnetic wave shielding film, the 85° glossiness of the surface of the insulating layer is 20 or less. A second aspect of the electromagnetic wave shielding film of the present invention includes an insulating layer and a conductive layer, and the root-mean-square slope (square root slope) Sdq of the insulating layer surface is 0.8 or more and 85° glossiness is 10 or less.

A third aspect of the electromagnetic wave shielding film of the present invention includes an insulating layer and a conductive layer, and the surface skewness Ssk of the insulating layer is 0.1 or more and 85° glossiness is 10 or less.

In each aspect of the electromagnetic wave shielding film, the L* value of the insulating layer can be set to 25 or less.

Invention effect

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

Description of drawings

[FIG. 1] A cross-sectional view of an electromagnetic wave shielding film in an embodiment;

[Fig. 2] A cross-sectional view of the electromagnetic wave shielding film in the modification;

[Figure 3] A point plot of the relationship between the root mean square slope (square root mean square slope) of the insulating layer and gloss;

[FIG. 4] A dot plot of the relationship between the skewness of the insulating layer and the glossiness.

Detailed ways

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

(Electromagnetic wave shielding film)

FIG. 1 is a schematic schematic cross-sectional view of the electromagnetic wave shielding film in the present embodiment. As shown in FIG. 1 , the electromagnetic wave shielding film includes an insulating layer 110 and a shielding layer 120 that is a conductive layer. An adhesive layer 130 may be provided on the surface of the shielding layer 120 opposite to the insulating layer 110 as required. By providing the adhesive layer 130, the electromagnetic wave shielding film can be easily attached to the printed wiring board.

-Insulation-

The insulating layer 110 is provided to protect the shielding layer. In the electromagnetic shielding film of the present embodiment, the three-dimensional (three-dimensional) arithmetic mean surface roughness Sa, which is a parameter representing the surface properties of the insulating layer 110 , is 0.8 μm or more, more preferably 1.0 μm or more. When Sa is 0.8 μm or more, the surface of the insulating layer can hardly be discolored by wiping fingerprints. The surface that is hardly discolored by wiping fingerprints here refers to a state in which the fingerprint-attached part is wiping with a wiping cloth or the like, and the surface is difficult to distinguish from the fingerprint-unattached part.

From the viewpoint of the actual removability of fingerprint components, Sa is preferably 10 μm or less, more preferably 5 μm or less, and more preferably 3 μm or less. When Sa is small to a certain extent, there is an effect that the insulating layer can be easily peeled off from the peeling film described later. If Sa exceeds the above-mentioned value, it becomes difficult to wipe off the attached fingerprints.

The surface of the insulating layer 110 after wiping off the fingerprints is observed with the naked eye, and the degree of discoloration of the fingerprints after being wiped off can be evaluated by sensory evaluation, thereby making a qualitative evaluation. It can also be evaluated quantitatively by changes in surface gloss. The quantitative evaluation method may be as follows: after the fingerprints are attached and wiped off, the 85° glossiness of the surface of the insulating layer 110 is measured. At this time, the 85° gloss after the fingerprints are attached and wiped should preferably be 20 or less, more preferably 10 or less, and the traces of wiping fingerprints are difficult to be recognized by the naked eye. Another quantitative evaluation method includes measuring the difference between the glossiness of the surface of the insulating layer 110 after the fingerprints are attached and then wiped off and the glossiness before the fingerprints are attached. That is, the smaller the difference between the glossiness of the surface of the insulating layer 110 after the fingerprints are attached and then wiped off and the glossiness before the fingerprints are attached, the smaller the degree of discoloration of the fingerprints by wiping. Taking 85° gloss as an example, for example, the gloss difference between the gloss after attaching the fingerprint and the gloss before attaching the fingerprint should be 4 or less, and 3 or less is better. At this time, the part where the fingerprint is not attached and the fingerprint is The erased portion is difficult to discern with the naked eye.

Regarding the electromagnetic wave shielding film of the present embodiment, in order to prevent discoloration due to wiping off fingerprints, surface property parameters other than Sa on the surface of the insulating layer 110 may be set as follows. The root mean square slope (square mean square root slope) Sdq is preferably above 0.8, more preferably above 0.95. The attached part of the fingerprint is more likely to reflect light than the unattached part, and the attached part of the fingerprint is very conspicuous. The color tone of the surface of the insulating layer 110 is black, and the smaller the L* value is, the more conspicuous the attached portion of the fingerprint is. Here, when Sdq is large to some extent, the surface can properly scatter light, and it is possible to prevent the enhancement of reflection due to the adhesion of fingerprints. In particular, when the L* value is below 25, increasing Sdq can effectively achieve the effect of inconspicuous fingerprint attachment.

Further, in order to facilitate the peeling of the release film to be described later from the insulating layer, Sdq is preferably 10 or less, more preferably 7.0 or less, and more preferably 3.0 or less.

The skewness (スキューネス) Ssk is preferably 0.1 or more, more preferably 0.5 or more, and more preferably 1.0 or more. Regarding Ssk, the convex and concave parts of the uneven surface are symmetrical based on the average surface. The larger the Ssk, the less the convex part based on the average surface. The parts other than the convex parts (valley parts and flat parts) are relatively increased. . Therefore, increasing Ssk to a certain extent makes it easier to wipe fingerprints.

Further, Ssk is preferably 10 or less, more preferably 5.0 or less, and more preferably 3.0 or less. When Ssk is within the above-mentioned range, the effect that the insulating layer can be easily peeled off from the peeling film described later can be obtained.

In addition, the maximum peak height (mountain height) Sp is preferably 8.0 μm or more. The root mean square (square root mean square root) deviation Sq is preferably 1.0 μm or more, more preferably 1.2 μm or more, and 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 more preferably 1.7 μm or more. The void volume Vvc of the central portion is preferably 1.1 ml/m ² or more, more preferably 1.3 ml/m ² or more. The physical volume Vmp of the peak is preferably 0.07 ml/m ² or more, more preferably 0.08 ml/m ² or more, and more preferably 0.1 ml/m ² or more.

Further, Sp is preferably 20 μm or less, more preferably 18 μm or less, and more preferably 15 μm or less. Sq is preferably 10 μm or less, more preferably 5.0 μm or less, and more preferably 3.0 μm or less. Spk is preferably 10 μm or less, more preferably 5.0 μm or less, and more preferably 3.0 μm or less. Vvc is preferably 10ml/m ² or less, more preferably 5.0ml/m ² or less, and more preferably 3.0ml/m ² or less. Vmp is preferably 1.0 ml/m ² or less, more preferably 0.5 ml/m ² or less, and more preferably 0.3 ml/m ² or less. When Sp, Spk, Vvc, and Vmp are within the above numerical ranges, respectively, there is an effect that the insulating layer can be easily peeled off from the peeling film described later.

In addition, other parameters can also be used to specify the surface that is not easily discolored by wiping fingerprints instead of Sa. For example, in order to obtain a surface that is not easily discolored by wiping fingerprints, it is preferable to use a surface with a small proportion of convex parts and a high convex part height based on the average surface. Therefore, it can be selected that Sp is 7.0 μm or more, preferably 8.0 μm or more, and Ssk is 0 or more, preferably 0.1 or more. In addition, it is possible to select that 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. In addition, it is possible to select that Sq is 1.0 μm or more, and Ssk is 0 or more, preferably 0.1 or more. In addition, it is possible to select that 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. In addition, it is possible to select that Spk is 1.0 μm or more and Ssk is 0 or more, preferably 0.1 or more. In addition, it is possible to select that 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.

In addition, it is possible to select that Sp is 20 μm or less, preferably 18 μm or less, and Ssk is 10 or less, preferably 5 or less. In addition, it can be selected that Sp is 20 μm or less, preferably 18 μm or less, and Sdq is 10 or less, preferably 3.0 or less. In addition, it can be selected that Sq is 10 μm or less, preferably 5 μm or less, and Ssk is 10 or less, preferably 5.0 or less. In addition, it is possible to select that Sq is 10 μm or less, preferably 5.0 μm or less, and Sdq is 10 or less, preferably 3.0 or less. In addition, it is possible to select that Spk is 10 μm or less, preferably 5.0 μm or less, and Ssk is 10 or less, preferably 5.0 or less. In addition, it is possible to select that Spk is 10 μm or less, preferably 5.0 μm or less, and Sdq is 10 or less, preferably 3.0 or less. Setting within the above-mentioned numerical range can achieve the effect that the insulating layer can be easily peeled from the release film.

In the present invention, the measured value of the surface properties is measured based on ISO 25178-6:2010, and the specific measurement method will be described in the examples.

In the insulating layer 110 , the glossiness at 60° before the fingerprint is attached is preferably 3 or less, more preferably 2 or less, and more preferably 1 or less. Further, the 85° gloss is preferably 20 or less, more preferably 15 or less, still more preferably 10 or less, still more preferably 5 or less, and still more preferably 3 or less.

When the glossiness before fingerprint adhesion is set to the above-mentioned value, moderate light scattering occurs on the surface of the insulating layer 110 , and the glossiness can be appropriately controlled. This can further prevent discoloration of fingerprints due to wiping.

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

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

Furthermore, Sdq is 0.8 or more, preferably 0.9 or more, and the 85° glossiness is 10 or less, preferably 5 or less, and more preferably 3 or less, so that discoloration by wiping fingerprints is less likely to occur.

In addition, 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, and more preferably 3 or less, so that it is not easy to discolor by wiping fingerprints.

In the present invention, the method for obtaining the insulating layer 110 is not particularly limited, and a known method can be used. For example, a resin composition for forming the insulating layer 110 may be applied to the surface of a release film having a concavo-convex shape due to an embossing process, and then dried to transfer the concavo-convex shape of the release film to the insulating layer. 110. The insulating layer 110 having a concavo-convex shape can be formed by applying a resin composition containing concavo-convex-forming particles on the surface of the shielding layer 120 and drying it. The following methods can be used: blowing dry ice on the surface of the insulating layer 110 or the like. The following method can be used: apply an active energy ray-curable (active energy ray-curable) composition on the surface of the shielding layer 120, press it with a mold having a concave-convex shape, harden the layer of the curable composition, and then peel off the mold. Other known methods can also be used.

Among them, from the viewpoint of productivity, a method of applying a resin composition containing unevenness-forming particles and drying to obtain the insulating layer 110 having a unevenness shape is preferably employed. In this case, the unevenness-forming particles are not particularly limited, and for example, resin fine particles or inorganic fine particles can be used. The resin microparticles may be acrylic resin microparticles, polyacrylonitrile microparticles, polyurethane microparticles, polyamide microparticles, polyimide microparticles, or the like. As the inorganic fine particles, calcium carbonate fine particles, calcium silicate fine particles, clay, kaolin, talc, silica fine particles, glass fine particles, diatomaceous earth, mica powder (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, etc. The above-mentioned resin fine particles and inorganic fine particles may be used alone or in combination of several. Inorganic fine particles are preferred from the viewpoint of improving the scratch resistance of the insulating layer.

From the viewpoint of generating moderate irregularities on the surface of the insulating layer 110 to obtain certain surface properties, the particles for forming irregularities preferably have a 50% average particle diameter of 2 μm or more, more preferably 4 μm or more, and more preferably 10 μm or more. In addition, from the viewpoint of preventing whitening (whitening) of the insulating layer, the 50% average particle diameter is preferably 30 μm or less, and more preferably 20 μm or less.

From the viewpoint of obtaining certain surface properties, the addition amount of the unevenness-forming particles in the insulating layer 110 is preferably 3 mass % or more, and more preferably 5 mass % or more. In addition, 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 more preferably 17% by mass or less.

A black colorant (colorant) may be added to the insulating layer 110 . By adding a black colorant (colorant), the L* value of the insulating layer 110 can be reduced, so that the marks (text, graphics, etc.) printed on the surface of the insulating layer are easier to identify. 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 more preferably 18 or less. In the present invention, the L* value can be measured according to JIS Z 8781-4 (2013).

The black colorant (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, black pigments can be used carbon black, ketjen black (ケッチェンブラック), carbon nanotube (CNT), perylene black (ペリレンブラック), titanium black (チタンブラック), iron black, aniline black, etc. one or a combination . Mixed pigments, for example, red, green, blue, yellow, violet, cyan, magenta and other pigments can be mixed and used.

The particle size of the black colorant (colorant) may be as long as the desired L* value can be achieved, but in consideration of dispersibility, reduction in the L* value, etc., the average primary particle size (primary particle size) is preferably 20 nm or more, preferably 100nm or less. The average primary particle size (primary particle size) of the black colorant (colorant) can be observed from a transmission electron microscope (TEM) image with a magnification of 50,000 times to 1,000,000 times. About 20 primary particles can be observed. Average value is obtained.

From the viewpoint of reducing the L* value, the addition amount of the black colorant (colorant) in the insulating layer 110 is preferably 0.5% by mass or more, more preferably 1% by mass or more. A black colorant (colorant) may or may not be added as required.

Gloss also affects the visibility of printed content. From the viewpoint of the visibility of the printed content, the 60° glossiness of the insulating layer 110 is preferably 3 or less, more preferably 2 or less, and 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, and more preferably 3 or less.

Preferably, the insulating layer 110 satisfies certain mechanical strength, chemical resistance and heat resistance in addition to the required insulating properties.

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

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

Further, the insulating layer 110 may contain a curing accelerator (hardening accelerator), a tackifier, an antioxidant, a pigment, a dye, a plasticizer, an ultraviolet absorber, a defoamer, a Leveling agent, filler, flame retardant, viscosity modifier (viscosity modifier), anti-blocking agent, etc.

The thickness of the insulating layer 110 is not particularly limited, and can be appropriately set as necessary, but from the viewpoint of sufficiently protecting the shield layer, it is preferably 1 μm or more, and more preferably 4 μm or more. In addition, from the viewpoint of securing the flexibility of the electromagnetic wave shielding film, it is preferably 20 μm or less, and more preferably 10 μm or less.

-Shield-

The shielding layer 120 of this 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, and zinc, or a metal layer containing two or more of them. The material and thickness of the metal layer may be appropriately selected according to the required electromagnetic wave shielding effect and repeated bending and sliding resistance. From the viewpoint of obtaining a sufficient electromagnetic wave shielding effect, the thickness of the metal layer is preferably 0.1 μm or more. From the viewpoints of productivity, flexibility, and the like, it is preferably 8 μm or less. The metal layer can be formed by the following methods: electroplating, electroless plating, sputtering, electron beam evaporation, vacuum evaporation, CVD, organic metal method, and the like. In addition, the metal layer may also be composed of metal foil, metal nanoparticles, scaly metal particles, and the like.

-Adhesive layer-

The electromagnetic wave shielding film of this embodiment may contain the adhesive layer 130 on the side opposite to the insulating layer 110 of the shielding layer 120 . The adhesive layer 130 may be made of an adhesive resin composition. The adhesive resin composition is not particularly limited, and styrene-based resin compositions, vinyl acetate-based resin compositions, polyester-based resin compositions, polyethylene-based resin compositions, polypropylene-based resin compositions, and imide-based resin compositions can be used. Thermoplastic resin compositions such as resin compositions, amide resin compositions, acrylic resin compositions, phenol resin compositions, epoxy resin compositions, polyurethane resin compositions, melamine resin compositions, alkyd resin compositions Thermosetting resin compositions such as resin compositions and the like. The above-mentioned substances may be used alone or in combination of two or more.

The adhesive layer 130 may be provided to have an isotropic conductivity or an anisotropic conductivity layer as required. In order to make the adhesive layer 130 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, metal fine particles such as silver powder, copper powder, nickel powder, solder powder, and aluminum powder can be used. Silver-coated copper powder obtained by silver-plating copper powder, polymer microparticles, glass microbeads, etc., are also metal-coated microparticles formed by coating with metal. Among them, low-priced copper powder or silver-coated copper powder is preferable from the viewpoint of economical efficiency.

The 50% average particle diameter of the electroconductive particles is not particularly limited, but is preferably 0.5 μm or more from the viewpoint of obtaining good electroconductivity. Further, from the viewpoint of controlling the thickness of the conductive adhesive layer, it is preferably 15 μm or less.

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

The thickness of the adhesive layer 130 can be adjusted as needed, but is preferably 0.5 μm or more from the viewpoint of obtaining good adhesiveness. 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 including the insulating layer 110, the shielding layer 120, and the adhesive layer 130 has been described above, but the structure shown in FIG.

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

-Manufacturing method of shielding film-

The electromagnetic wave shielding film of this embodiment can be manufactured by a well-known manufacturing method. One example will be described below.

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

Then, the shielding layer 120 is formed on the surface of the adhesive layer 130 . Specifically, the following methods can be used: a method of bonding a metal foil with a predetermined thickness to the adhesive layer 130 in advance, and a method of forming a metal layer on the surface of the adhesive layer 130 by vapor deposition or metal plating.

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

Then, the electromagnetic wave shielding film can be obtained by peeling off the support film.

The adhesive layer 130 may also 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 make the surface properties of the surface of the insulating layer 110 into a constant state, the surface of the insulating layer 110 may also be subjected to a treatment such as sandblasting.

In the above example, the production is started from the adhesive layer 130 side, but it may be produced sequentially from the insulating layer 110 side. In this case, the following method may be adopted: the micropattern is transferred to the surface of the insulating layer 110 using a support film with a micropattern, thereby making the surface properties of the insulating layer 110 a constant state.

Example

The present invention will be described in detail below by means of examples. The following examples are only illustrative and do not limit the present invention.

<Production of electromagnetic wave shielding film>

- Production of Adhesive Layer -

100 parts by mass of bisphenol A epoxy resin (manufactured by Mitsubishi Chemical, jER1256), 0.1 part by mass of hardener (manufactured by Mitsubishi Chemical, ST14), and dendritic silver-coated copper powder (average particle size) were added to toluene. 13 μm) 25 parts by mass, the solid content was 20 mass %, and the mixture was stirred and mixed to prepare a conductive adhesive layer composition. The obtained adhesive layer composition was coated on the PET film whose surface was subjected to release treatment, and an adhesive layer was formed on the surface of the support film by heating and drying.

- Production of shielding layer -

Rolled copper foil with a thickness of 2 μm was bonded to the surface of the obtained adhesive layer.

- Production of insulating layer -

For toluene, 100 parts by mass of bisphenol A epoxy resin (manufactured by Mitsubishi Chemical, jER1256), 0.1 part by mass (manufactured by Mitsubishi Chemical, ST14) as a hardener, and carbon particles as a black colorant (colorant) (Tokai Carbon (TOKAICARBON), TOKABLACK #8300/F) 15 parts by mass, and a certain amount of particles for forming certain irregularities, so that the solid content is 20 mass %, to prepare an insulating layer composition. This composition was applied on the obtained shielding layer, and heated and dried to obtain an electromagnetic wave shielding film.

<Characteristic evaluation method>

[Measurement of Surface Properties of Insulating Layer]

After measuring 5 arbitrary points on the surface of the insulating layer of the electromagnetic wave shielding film with a confocal microscope (produced by Lasertec, OPTELICS HYBRID, objective lens 20 times), the surface inclination correction (tilt correction) is performed by the data analysis software (LMeye7), according to ISO 25178-6 : In 2010, the surface properties were measured, and the arithmetic mean value was obtained. The cutoff wavelength of the S filter is 0.0025mm, and the cutoff wavelength of the L filter is 0.8mm.

[Measurement of L* value]

The L* value was measured with an integrating sphere spectrophotometer (integrating sphere spectrophotometer) (manufactured by X-Rite, Ci64, tungsten light source). And measured a* value, b* value.

[Evaluation of discoloration due to fingerprints]

The surface of the rubber plug with a diameter of 2.5cm is roughened with #240 sandpaper. Then, 5 μL of artificial contamination solution (JISC9606: manufactured by Isehisa) was dropped on the surface of the PET film, and the roughened surface of the rubber stopper was pressed against the artificial contamination solution (500 g load-bearing, 10 seconds). Then, press the rubber plug attached to the artificial contamination liquid on the surface of the insulating layer (500g load-bearing, 10 seconds) to make the artificial contamination liquid adhere. Then, cut out about 3cm angle from non-woven fabric (NIPPON PAPER CRECIA, WYPALLX70), put it on the artificial pollution solution, and reciprocate 20 times under 500g load (one-way distance = 10cm) , and wipe it accordingly. The value obtained by subtracting the 85° gloss value after wiping from the 85° gloss value before the attachment of the artificial contamination liquid is 85° poor gloss. The 60° gloss and the 85° gloss were measured by BYK Gardner Micro Gloss Meter (ガードナー・マイクロ-グロス) (portable gloss meter).

(Example 1)

Silica particles with an average particle diameter of 7 μm were used as the unevenness-forming particles added to the insulating layer, and the amount used was 40 parts by mass. Sa on the surface of the insulating layer of the electromagnetic wave shielding film obtained was 1.02 μm, Sdq was 1.26, and Ssk was 2.22. The 60° gloss before the artificial contamination solution was attached was 1.1, and the 60° gloss after the fingerprint was wiped was 5.2. The 85° glossiness before the artificial contamination solution is attached is 1.5, the 85° glossiness after fingerprint wiping is 1.9, and the 85° glossiness difference is 0.4. The L* value was 21.3.

(Example 2)

An electromagnetic wave shielding film was obtained in the same manner as in Example 1, except that the used amount of the unevenness-forming particles was 50 parts by mass. The surface of the insulating layer of the electromagnetic wave shielding film obtained had Sa of 1.18 μm, Sdq of 1.26, and Ssk of 2.21. The 60° gloss before the artificial contamination solution was attached was 0.5, and the 60° gloss after the fingerprint was wiped was 6.7. The 85° gloss before the artificial contamination solution is attached is 1.8, the 85° gloss after the fingerprint is wiped is 2.4, and the 85° gloss difference is 0.6. The L* value was 20.1.

(Example 3)

An electromagnetic wave shielding film was obtained in the same manner as in Example 1, except that the used amount of the unevenness-forming particles was 35 parts by mass. The surface of the insulating layer of the obtained electromagnetic wave shielding film had Sa of 1.31 μm, Sdq of 0.95, and Ssk of 1.47. The 60° gloss before the artificial contamination solution was attached was 0.5, and the 60° gloss after the fingerprint was wiped was 1.8. The 85° gloss before the artificial contamination solution is attached is 1.7, the 85° gloss after fingerprint wiping is 2.5, and the 85° gloss 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 and the used amount was 40 parts by mass. Sa on the surface of the insulating layer of the electromagnetic wave shielding film obtained was 0.92 μm, Sdq was 1.38, and Ssk was 3.10. The 60° gloss before the artificial contamination solution is attached is 2.1, and the 60° gloss after the fingerprint is wiped is 6.1. The 85° gloss before the artificial contamination solution is attached is 2.1, the 85° gloss after the fingerprint is wiped is 2.6, and the 85° gloss difference is 0.5. The L* value was 23.5.

(Example 5)

An electromagnetic wave shielding film was obtained in the same manner as in Example 4, except that the used amount of the unevenness-forming particles was 50 parts by mass. Sa on the surface of the insulating layer of the electromagnetic wave shielding film obtained was 0.92 μm, Sdq was 1.02, and Ssk was 2.53. The 60° gloss before the artificial contamination solution was attached was 1.5, and the 60° gloss after the fingerprint was wiped was 4.9. The 85° gloss before the artificial contamination solution is attached is 1.7, the 85° gloss after the fingerprint is wiped is 3.2, and the 85° gloss 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 and the used amount was 70 parts by mass. The surface of the insulating layer of the obtained electromagnetic wave shielding film had Sa of 1.05 μm, Sdq of 0.92, and Ssk of 0.80. The 60° gloss before the artificial contamination solution was attached was 0.5, and the 60° gloss after the fingerprint was wiped was 2.4. The 85° gloss before the artificial contamination solution is attached is 4.6, the 85° gloss after the fingerprint is wiped is 6.3, and the 85° gloss 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 silica particles having an average particle diameter of 7 μm were used and the used amount was 60 parts by mass. The surface of the insulating layer of the obtained electromagnetic wave shielding film had Sa of 1.11 μm, Sdq of 1.12, and Ssk of 1.46. The 60° gloss before the artificial contamination solution was attached was 0.4, and the 60° gloss after the fingerprint was wiped was 1.9. The 85° gloss before the artificial contamination solution is attached is 3.8, the 85° gloss after the fingerprint is wiped is 6.5, and the 85° gloss difference is 2.7. The L* value was 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 concavities and convexities, and the usage amount was 60 parts by mass. Sa of the insulating layer surface of the obtained electromagnetic wave shielding film was 0.57 μm, Sdq was 0.80, and Ssk was 0.07. The 60° gloss before the artificial contamination solution was attached was 0.8, and the 60° gloss after the fingerprint was wiped was 2.2. The 85° glossiness before the artificial contamination solution is attached is 16.8, the 85° glossiness after fingerprint wiping is 26.7, and the 85° glossiness difference is 9.9. The L* value was 24.4.

(Comparative Example 2)

An electromagnetic wave shielding film was obtained in the same manner as in Comparative Example 1, except that the used amount of the unevenness-forming particles was 65 parts by mass. Sa on the surface of the insulating layer of the obtained electromagnetic wave shielding film was 0.66 μm, Sdq was 0.90, and Ssk was −0.22. The 60° gloss before the artificial contamination solution was attached was 0.5, and the 60° gloss after the fingerprint was wiped was 3.9. The 85° glossiness before the artificial contamination solution is attached is 15.9, the 85° glossiness after fingerprint wiping is 30.4, and the 85° glossiness difference is 14.5. The L* value was 21.9.

(Comparative Example 3)

An insulating layer composition containing no unevenness-forming particles was prepared. This was apply|coated to the surface of a support body film, it was made to dry and harden, and the insulating layer was obtained. The support film was a release-treated PET film having a thickness of 20 μm and having a concavo-convex shape (Sa=0.60 μm, Sdq=0.61) on the surface by embossing. Next, after bonding the insulating layer to the shielding layer produced in the same manner as in Example 1, the support film was peeled off to obtain an electromagnetic wave shielding film. Sa on the surface of the insulating layer of the obtained electromagnetic wave shielding film was 0.58 μm, Sdq was 0.65, and Ssk was −0.78. The 60° gloss before the artificial contamination solution was attached was 4.2, and the 60° gloss after the fingerprint was wiped was 9.1. The 85° gloss before the artificial contamination solution is attached is 34.0, the 85° gloss after fingerprint wiping is 42.8, and the 85° gloss difference is 8.8. The L* value was 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 an uneven surface (Sa=0.6 μm, Sdq=0.47 μm) using silica fine particles was used as a support film. Sa of the insulating layer surface of the obtained electromagnetic wave shielding film was 0.59 micrometer, Sdq was 0.49, and Ssk was -0.85. The 60° gloss before the artificial contamination solution was attached was 7.6, and the 60° gloss after the fingerprint was wiped was 13.3. The 85° glossiness before the artificial contamination solution was attached was 38.7, the 85° glossiness after fingerprint wiping was 48.0, and the 85° glossiness difference was 9.3. The L* value was 28.2.

(Comparative Example 5)

Electromagnetic wave shielding was obtained in the same manner as in Comparative Example 3, except that a film having an uneven surface (Sa = 0.47 μm, Sdq = 0.59 μm) by sanding was used as a support film membrane. Sa on the surface of the insulating layer of the obtained electromagnetic wave shielding film was 0.45 μm, Sdq was 0.58, and Ssk was −0.25. The 60° gloss before the artificial contamination solution was attached was 5.4, and the 60° gloss after the fingerprint was wiped was 11.9. The 85° glossiness before the artificial contamination solution was attached was 26.1, the 85° glossiness after fingerprint wiping was 51.0, and the 85° glossiness difference was 24.9. The L* value was 27.2.

(Comparative Example 6)

Electromagnetic wave shielding was obtained in the same manner as in Comparative Example 3, except that a film having an uneven surface (Sa = 0.45 μm, Sdq = 0.56 μm) by sanding was used as a support film membrane. Sa of the insulating layer surface of the obtained electromagnetic wave shielding film was 0.45 micrometer, Sdq was 0.54, and Ssk was -0.60. The 60° gloss before the artificial contamination solution was attached was 9.2, and the 60° gloss after the fingerprint was wiped was 16.6. The 85° glossiness before the artificial contamination solution is attached is 30.4, the 85° glossiness after fingerprint wiping is 54.7, and the 85° glossiness difference is 24.3. The L* value was 27.2.

(Comparative Example 7)

Electromagnetic wave shielding was obtained in the same manner as in Comparative Example 3, except that a film having a concavo-convex shape (Sa=0.51 μm, Sdq=0.55 μm) on the surface by sanding was used as a support film membrane. Sa on the surface of the insulating layer of the obtained electromagnetic wave shielding film was 0.49 μm, Sdq was 0.55, and Ssk was −0.37. The 60° gloss before the artificial contamination solution was attached was 8.6, and the 60° gloss after the fingerprint was wiped was 16.7. The 85° glossiness before the artificial contamination solution is attached is 21.6, the 85° glossiness after fingerprint wiping is 56.7, and the 85° glossiness difference is 35.1. The L* value was 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 having an uneven surface (Sa=0.43 μm, Sdq=0.40 μm) using silica fine particles was used as a support film. Sa on the surface of the insulating layer of the obtained electromagnetic wave shielding film was 0.42 μm, Sdq was 0.38 μm, and Ssk was −1.19. The 60° gloss before the artificial contamination solution was attached was 11.7, and the 60° gloss after the fingerprint was wiped was 17.9. The 85° glossiness before the artificial contamination solution is attached is 52.4, the 85° glossiness after fingerprint wiping is 58.9, and the 85° glossiness difference is 6.5. The L* value was 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 usage amount was 40 parts by mass. Sa of the insulating layer surface of the obtained electromagnetic wave shielding film was 0.49 μm, Sdq was 0.74, and Ssk was −0.77. The 60° gloss before the artificial contamination solution was attached was 1.0, and the 60° gloss after the fingerprint was wiped was 19.8. The 85° glossiness before the artificial contamination solution is attached is 33.2, the 85° glossiness after fingerprint wiping is 61.0, and the 85° glossiness difference is 27.8. The L* value was 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 having an uneven surface (Sa=0.36 μm, Sdq=0.36 μm) using silica fine particles was used as a support film. Sa on the surface of the insulating layer of the obtained electromagnetic wave shielding film was 0.35 μm, Sdq was 0.36, and Ssk was −0.31. The 60° gloss before the artificial contamination solution was attached was 6.9, and the 60° gloss after the fingerprint was wiped was 12.1. The 85° gloss before the artificial contamination solution is attached is 58.6, the 85° gloss after fingerprint wiping is 63.0, and the 85° gloss difference is 4.4. The L* value was 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 an uneven surface (Sa=0.46 μm, Sdq=0.65 μm) using silica fine particles was used as a support film. Sa of the insulating layer surface of the obtained electromagnetic wave shielding film was 0.43 micrometer, Sdq was 0.62, and Ssk was -0.40. The 60° gloss before the artificial contamination solution was attached was 2.4, and the 60° gloss after the fingerprint was wiped was 16.6. The 85° glossiness before the artificial contamination solution is attached is 42.6, the 85° glossiness after fingerprint wiping is 71.8, and the 85° glossiness difference is 29.2. The L* value was 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 having an uneven surface (Sa=0.31 μm, Sdq=0.58 μm) using silica fine particles was used as a support film. Sa on the surface of the insulating layer of the obtained electromagnetic wave shielding film was 0.34 μm, Sdq was 0.55, and Ssk was −0.48. The 60° gloss before the artificial contamination solution was attached was 4.3, and the 60° gloss after the fingerprint was wiped was 30.2. The 85° glossiness before the artificial contamination solution is attached is 64.2, the 85° glossiness after fingerprint wiping is 80.6, and the 85° glossiness difference is 16.4. The L* value was 24.4.

(Comparative Example 13)

The surface of the support film was prepared in the same manner as in Comparative Example 3, except that a PET film having an uneven surface (Sa = 1.5 μm, Sdq = 4.89 μm) by embossing was used as the support film. Apply the insulating layer and let it dry and harden. Next, the insulating layer was bonded to the shield layer produced in the same manner as in Example 1. Next, when the support film was to be peeled off, the support film and the insulating layer were firmly attached, and the interface between the insulating layer and the shielding layer was partially damaged. Sa on the surface of the insulating layer where interface damage was not observed was 1.3 μm, Sdq was 3.6, and Ssk was −1.60. In addition, since interface breakage occurred in this comparative example, glossiness and L* value were not measured.

Table 1 shows the evaluation of the surface properties and discoloration of the electromagnetic wave shielding films of the respective Examples and Comparative Examples. The values of Sp, Sq, Spk, Vvc, Vmp, a* and b* are also shown in Table 1.

【Table 1】

Figure 3 shows the relationship between Sdq and 85° gloss. At least when Sdq is more than 0.8 and the gloss at 85° is less than 10, the gloss difference is less than 4, and it is not easy to cause discoloration due to wiping of fingerprints.

Figure 4 shows the relationship between Ssk and 85° gloss. At least when the Ssk is 0.1 or more and the 85° gloss is 10 or less, the gloss difference is 4 or less, and it is difficult to cause discoloration due to wiping of fingerprints.

practicality

The electromagnetic wave shielding film of the present invention is less likely to be discolored by wiping off fingerprints, and is useful as an electromagnetic wave shielding film of a printed wiring board or the like.

Symbol Description

110 Insulation layer

120 shield

130 Adhesive layer

140 Isotropic conductive adhesive layer

Claims (5)

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

wherein a maximum peak height Sp of the surface of the insulating layer is 8.0 [ mu ] m or more and 20 [ mu ] m or less.

2. 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.

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

wherein the height Spk of the protruding peak part on the surface of the insulating layer is more than 1.0 μm and less than 10 μm.

4. The electromagnetic wave shielding film according to claim 1, characterized in that:

the insulating layer has a surface gloss of not more than 20 at 85 DEG before fingerprint adhesion.

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

the insulating layer has an L value of 25 or less.

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