HK40035233A - Electromagnetic wave shielding film - Google Patents

Description

Electromagnetic wave shielding film

The present application is a divisional application of an invention patent application having an application date of 09 month 06 of 2017 and an application number of 201710796140.8, entitled "electromagnetic wave shielding film".

Technical Field

The present invention relates to an electromagnetic wave shielding film.

Background

In recent years, smart phones, tablet information terminals, and the like have been increasingly required to have high-speed transmission performance of large-capacity data. High frequency signals are required to transmit large capacity data at high speed. However, when high frequency signals are used, electromagnetic wave noise is generated in the signal circuits on the printed wiring board, which causes the peripheral devices to operate erroneously. To prevent operational errors, the printed wiring board is shielded from electromagnetic waves.

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).

The electromagnetic wave shielding film has a protective film made of polyethylene terephthalate (PET) resin or the like attached to the surface of the insulating layer to protect the insulating layer from being damaged or affected by 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 printed wiring board is shielded from light hand contact.

Documents of the prior art

Patent document

[ patent document 1 ] Japanese patent application laid-open No. 2004-095566.

Disclosure of Invention

Object of the invention

When the protective film is peeled off and the shielded printed wiring board is touched with a hand, fingerprints may be attached to the insulating layer after the protective film is removed. The fingerprint-attached portion is discolored and the appearance is impaired. There is a problem that the yield is low.

The insulating layer has fingerprint adhesion and hardly affects electromagnetic wave shielding characteristics. Therefore, the yield of the shielded printed wiring board can be prevented from lowering by preventing the insulating layer from discoloring due to the adhesion of fingerprints. The method of preventing discoloration of the insulating layer due to the attachment of fingerprints may be to remove fingerprints. Generally, a detergent or a solvent is used for fingerprint removal. The object is an insulating layer of an electromagnetic wave shielding film, and a detergent or a solvent affects the electrical characteristics of the shielded printed wiring board, and thus cannot be used.

Conventionally, when an electromagnetic wave shielding film is rubbed on a surface by wiping a fingerprint with a nonwoven fabric or the like, the surface state changes locally, and the discoloration becomes more severe. Further, the surface is rubbed with a large force to peel the insulating layer from the shielding layer, resulting in breakage of the electromagnetic wave shielding film.

The present invention provides an electromagnetic wave shielding film which is not easy to discolor due to fingerprint wiping.

Means for solving the problem

The invention provides an electromagnetic wave shielding film according to claim 1, which comprises an insulating layer and a conductive layer, wherein the three-dimensional (cubic) arithmetic mean surface roughness Sa of the surface of the insulating layer is 0.8 μm or more.

In the electromagnetic wave shielding film of claim 1, the insulating layer has a surface gloss of 85 ° of 20 or less. The electromagnetic wave shielding film of the invention in the second technical solution comprises an insulating layer and a conductive layer, wherein the root-mean-square slope (two-dimensional vertical-average square root) Sdq of the surface of the insulating layer is more than 0.8 and the 85 DEG glossiness is less than 10.

The electromagnetic wave shielding film of claim 3 comprises an insulating layer and a conductive layer, and the insulating layer has an offset (スキューネス) Ssk of 0.1 or more and an 85 ° gloss of 10 or less.

In each embodiment of the electromagnetic wave shielding film, the insulating layer L < lambda > can be set to 25 or less.

Effects of the invention

The electromagnetic wave shielding film of the present invention 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 of the insulation layer (two times by average square root tilt) versus gloss;

fig. 4 is a plot of skewness (スキューネス) versus gloss for an insulating layer.

Detailed Description

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 a range not changing the gist of the present invention.

(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 contains: insulating layer 110, conductive layer, i.e., shield 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. By providing the adhesive layer 130, the electromagnetic wave shielding film can be easily attached to the printed wiring board.

Insulating layer-

The insulating layer 110 is provided for protecting the shield layer. In the electromagnetic shielding film of the present embodiment, the three-dimensional (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, 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 is hardly discolored by wiping a fingerprint as referred to herein means that the surface of the fingerprint-attached portion is hardly distinguishable from the non-attached portion of the fingerprint by the naked eye after wiping with a wiping cloth (wiping cloth) 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 a peeling film described later. It is difficult to wipe attached fingerprints with Sa exceeding the above value.

The surface of the insulating layer 110 after wiping off the fingerprint was visually observed, and the degree of discoloration of the wiped fingerprint was evaluated organoleptically, whereby the qualitative evaluation was possible. But also by quantitative evaluation of the change in surface gloss. The quantitative evaluation method may be: the fingerprint was attached and erased again, and then the 85 ° gloss of the surface of the insulating layer 110 was measured. In this case, the gloss at 85 ℃ after the fingerprint is attached and erased is preferably 20 or less, more preferably 10 or less, and at this time, the trace of the fingerprint wiped off is hardly recognized by naked eyes. Other quantitative evaluation methods include: the difference between the glossiness of the surface of the insulating layer 110 after the adhesion and re-erasure of the fingerprint and the glossiness before the adhesion of the fingerprint was measured. That is, the smaller the difference between the glossiness of the surface of the insulating layer 110 after the adhesion and re-erasure of the fingerprint and the glossiness before the adhesion of the fingerprint, the smaller the degree of discoloration due to wiping of the fingerprint. Taking the gloss at 85 ° as an example, the difference in gloss between the gloss after the fingerprint is attached and erased and the gloss before the fingerprint is attached is preferably 4 or less, more preferably 3 or less, and in this case, the fingerprint non-attached portion and the fingerprint erased portion are hardly distinguished by the naked eye.

In the electromagnetic wave shielding film of the present embodiment, in order to prevent discoloration due to wiping of fingerprints, surface property parameters other than Sa on the surface of the insulating layer 110 may be set as follows. The root-mean-square-root slope (two times by taking the average square-root inclined) Sdq is preferably 0.8 or more, more preferably 0.95 or more. The fingerprint attachment portion reflects light more easily than the non-attachment portion, and the fingerprint attachment portion is conspicuous. The surface of the insulating layer 110 is colored black and the fingerprint attachment portion becomes more conspicuous as the L value is smaller. Here, if Sdq is somewhat large, the surface energy can appropriately scatter light, and reflection enhancement due to fingerprint adhesion can be prevented. In particular, when the L value is 25 or less, the effect of making the fingerprint adhering portion inconspicuous can be effectively achieved by increasing Sdq.

In order to facilitate the peeling of the peeling film described later from the insulating layer, Sdq is preferably 10 or less, more preferably 7.0 or less, and still 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, still more preferably 1.0 or more. In the Ssk, the convex and concave portions of the uneven surface are symmetrical with respect to the average surface, and the larger the Ssk, the less the convex portion component with respect to the average surface, and the relatively larger the portions other than the convex portions (the valley portion and the flat portion). Therefore, increasing the 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. The Ssk in the above range can provide an effect of easily peeling the insulating layer from a peeling film described later.

Further, the maximum peak height (mountain height さ) Sp is preferably 8.0 μm or more. The root mean square (square root by two times) 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 projected 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 1.1 ml/m²Above, 1.3 ml/m²The above is more preferable. The peak preferably has a solid volume Vmp of 0.07 ml/m²Above, 0.08 ml/m²More preferably, the concentration is 0.1 ml/m²The above is more preferable.

Sp is preferably 20 μm or less, more preferably 18 μm or less, and further preferably 15 μm or lessAnd more preferably. 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 10 ml/m²Preferably, 5.0 ml/m²More preferably, it is 3.0 ml/m²The following are more preferable. Vmp at 1.0 ml/m²Preferably, 0.5 ml/m²More preferably, 0.3 ml/m²The following are more preferable. Sp, Spk, Vvc, and Vmp each have the above numerical value range, and have an effect of easily peeling the insulating layer from the peeling film to be described later.

In addition, instead of Sa, a surface that is less likely to be discolored by wiping a fingerprint may be defined by other parameters. 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 protrusions based on the average surface and a high height of the protrusions is preferably used. Thus, it is possible to select: 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 select: 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 surface property measurement value in the invention is based on ISO 25178-6: 2010, the specific measurement method will be described in the examples.

In the insulating layer 110, the 60 ° gloss before fingerprint attachment 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 fingerprint is attached is set to the above value, appropriate light scattering occurs on the surface of the insulating layer 110, and the glossiness can be appropriately controlled. Thus, discoloration due to wiping of fingerprints can be further prevented.

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

The 60 ° gloss and 85 ° gloss in the present invention can be measured by the methods shown in the 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 by wiping fingerprints is less likely.

Further, Ssk is more than 0, preferably 0.1 or more, more preferably 0.5 or more, and 85 ° gloss is 10 or less, preferably 5 or less, more preferably 3 or less, so that discoloration by wiping fingerprints is less likely.

The method for obtaining the insulating layer 110 in the present invention is not particularly limited, and a known method can be used. For example, the following may be used: the surface of the release film having the uneven shape by the embossing (エンボス) is coated with a resin composition for forming the insulating layer 110 and dried, thereby transferring the uneven shape of the release film to the insulating layer 110. The following methods may be used: the insulating layer 110 having an uneven shape is formed by applying a resin composition containing uneven forming particles on the surface of the shield layer 120 and drying the resin composition. The following methods may be used: dry ice is blown onto the surface of the insulating layer 110. The following methods may be used: an active energy ray-curable (curable active エネルギー line) composition was applied to the surface of the shield layer 120, and then the cured composition layer was cured by pressing with a mold having an uneven shape, and then the mold was peeled off. Other known methods may also be used.

Among them, from the viewpoint of productivity, a method of obtaining the insulating layer 110 having an uneven shape by coating a resin composition containing the uneven forming particles and drying the coating is preferably employed. In this case, the particle for forming irregularities is not particularly limited, and for example, a resin fine particle or an inorganic fine particle can be used. As the resin fine particles, acrylic resin fine particles, polyacrylonitrile fine particles, polyurethane fine particles, polyamide fine particles, polyimide fine particles, etc. can be used. 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, and the like can be used. The resin fine particles and the inorganic fine particles may be used alone or in combination of two or more. The inorganic fine particles are preferable from the viewpoint of improving the scratch resistance of the insulating layer.

From the viewpoint of generating appropriate irregularities on the surface of the insulating layer 110 to obtain a certain surface texture, the 50% average particle diameter of the irregularity-forming particles is preferably 2 μm or more, more preferably 4 μm or more, and still 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, more preferably 20 μm or less.

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

A black colorant may be added to the insulating layer 110. The addition of the black colorant can reduce the L value of the insulating layer 110, thereby making it easier to identify the marks (characters, figures, etc.) printed on the surface of the insulating layer. 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. In the present invention, the L value can be measured in accordance with JIS Z8781-4 (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. The black pigment may be one or a combination of 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, or the like. The mixed pigment may be, for example, a red, green, blue, yellow, violet, cyan, magenta, or other pigment.

The particle diameter of the black coloring agent may be any particle diameter as long as the desired L.sup.m value can be achieved, but in view of dispersibility, reduction in L.sup.m value, etc., the average primary particle diameter (primary particle diameter) is preferably 20nm or more, preferably 100nm or less. The average primary particle diameter (primary particle diameter) of the black colorant can be determined from the average value of about 20 primary particles observed in an image magnified from 5 to 100 ten thousand times by a Transmission Electron Microscope (TEM).

The amount of the black colorant (colorant) added to the insulating layer 110 is preferably 0.5 mass% or more, more preferably 1 mass% or more, from the viewpoint of reducing the L value. The black colorant (coloring agent) may be added or not added as necessary.

Gloss also affects the visibility of printed content. The 60 ° gloss of the insulating layer 110 is preferably 3 or less, more preferably 2 or less, and still more preferably 1 or less from the viewpoint of visibility of printed contents. 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.

Preferably, the insulating layer 110 satisfies 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 insulating properties, and examples thereof include a thermoplastic resin composition, a thermosetting resin composition, and an active energy ray-curable (active エネルギー -curable) composition.

The thermoplastic resin composition is not particularly limited, and may be 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, or the like. The thermosetting resin composition is not particularly limited, and 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. The active energy ray-curable composition (the curable composition under the living line エネルギー) is not particularly limited, and for example, a polymerizable compound having at least 2 (meth) acryloyloxy groups in the molecule thereof can be used. The above composition can be used singly or in combination of 2 or more.

Further, the insulating layer 110 may contain, in addition to the above microparticles and colorants, a curing accelerator (hardening accelerator), a tackifier, an antioxidant, a pigment, a dye, a plasticizer, an ultraviolet absorber, a defoamer, a leveler (レベリング), a filler, a flame retardant, a viscosity modifier (viscosity adjuster), an anti-blocking agent (ブロッキング preventer), and the like, as necessary.

The thickness of the insulating layer 110 is not particularly limited, and may be appropriately set as needed, and is preferably 1 μm or more, and more preferably 4 μm or more, from the viewpoint of sufficiently protecting the shield layer. In addition, from the viewpoint of ensuring the bendability of the electromagnetic wave-shielding film, it is preferably 20 μm or less, and 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, and zinc, or a metal containing two or more of these metals. The material and thickness of the metal layer may be appropriately selected depending on the desired electromagnetic wave shielding effect and repeated bending/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 viewpoint of productivity, bendability, etc., it is preferably 8 μm or less. The metal layer may be formed by: electroplating, electroless plating (e.g., electroless deposition メッキ), sputtering, electron beam evaporation (e.g., electron beam ビーム evaporation), vacuum evaporation, CVD, and metal organic deposition. The metal layer may be formed of a metal foil, metal nanoparticles, scale-like metal particles, or the like.

Adhesive layer

The electromagnetic wave shielding film of the present embodiment may include an adhesive layer 130 on the side of the shielding layer 120 opposite to the insulating layer 110. The adhesive layer 130 may be made of a resin composition having adhesive property. The adhesive resin composition is not particularly limited, and a thermosetting 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 phenol resin composition, an epoxy resin composition, a polyurethane resin composition, a melamine resin composition, or an alkyd resin composition may be used. These may be used singly or in combination of two or more.

The adhesive layer 130 may be provided to have an isotropic conductive or an anisotropic conductive layer as needed. The adhesive layer 130 may be an isotropic or anisotropic conductive layer by adding conductive fine particles to an 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 copper powder may be silver-coated copper powder obtained by plating copper powder with silver, or metal-coated fine particles obtained by coating metal such as polymer fine particles or glass beads. Among these, copper powder or silver-coated copper powder, which is inexpensive, is preferable from the viewpoint of economy.

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

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 view of obtaining good adhesion. Further, it is preferably 20 μm or less from the viewpoint of controlling the thickness of the electromagnetic wave shielding film.

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 electromagnetic wave shielding film may include the insulating layer 110 and the isotropic conductive adhesive layer 140 as shown in fig. 2.

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 those of the adhesive layer 130. The isotropic conductive adhesive layer 140 functions as a shielding layer.

Method for producing a shielding film

The electromagnetic wave shielding film of the present embodiment can be produced by a known production method. An example thereof will be described below.

First, the adhesive layer 130 having conductivity is formed on the support film whose surface is subjected to the release treatment. Specifically, an adhesive layer composition solution containing a material for forming the adhesive layer 130 is applied to 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 method can be employed: a method of bonding a metal foil having a predetermined thickness to the adhesive layer 130, and 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 employed: 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 it.

Then, the support film is peeled off to obtain the 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.

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

The above examples are made from the adhesive layer 130 side, and may be made in order from the insulating layer 110 side. The following may be used at this time: the surface properties of the insulating layer 110 are set to be constant by transferring the minute pattern to the surface of the insulating layer 110 using the support film with the minute pattern.

Examples

The present invention will be described in detail below with reference to examples. The following examples are given by way of illustration only and are not intended to limit the present invention.

< production of electromagnetic wave shielding film >

Preparation of the adhesive layer

100 parts by mass of a bisphenol A epoxy resin (Mitsubishi chemical, jER 1256), 0.1 part by mass of a curing agent (Mitsubishi chemical, ST 14), and 25 parts by mass of dendritic silver-coated copper powder (average particle diameter: 13 μm) were added to toluene so that the solid content became 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 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 the shielding layer

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

Production of insulating layers

An insulating layer composition was prepared by using 100 parts by mass of a bisphenol a type epoxy resin (mitsubishi chemical production, jER 1256), 0.1 part by mass of a hardener (mitsubishi chemical production, ST 14), 15 parts by mass of carbon particles (tokacarbon production, tokaback # 8300/F) as a black colorant (colorant), and a predetermined amount of particles for forming irregularities, such that the solid content was 20 mass%, for toluene. The composition is coated on the obtained shielding layer, and is heated and dried to obtain the electromagnetic wave shielding film.

< method for evaluating characteristics >

[ measurement of surface Properties of insulating layer ]

After measuring any 5 positions on the surface of the insulating layer of the electromagnetic wave shielding film with a confocal microscope (20 times objective lens, opterliccs HYBRID, manufactured by Lasertec corporation), the surface tilt correction (tilt き correction) was performed by data analysis software (LMeye 7), and the measurement was carried out in accordance with ISO 25178-6: 2010 the surface properties were measured and the arithmetic mean thereof was obtained. The cut-off wavelength of the S filter was 0.0025 mm, and the cut-off wavelength of the L filter was 0.8 mm.

[ measurement of L value ]

L is measured by integrating sphere spectrophotometer (divided sphere spectrophotometer ) (Ci 64, manufactured by X-Rite Co., Ltd., tungsten light source). And measuring the a and b values.

[ evaluation of discoloration due to fingerprints ]

The surface of a rubber plug having a diameter of 2.5 cm was roughened with # 240 sandpaper. Then, 5. mu.L of an artificial contaminated solution (JISC 9606: Ujiu Kagaku Co., Ltd.) was dropped onto the surface of the PET film, and the roughened surface of the rubber plug was pressed against the artificial contaminated solution (500 g of load-bearing, 10 seconds). Then, the rubber plug to which the contaminated solution was adhered was pressed against the surface of the insulating layer (500 g weight bearing, 10 seconds) to adhere the contaminated solution. Then, the nonwoven fabric (WYPALLX 70, produced by Nippon PAPER CRECIA, Koshikeke, Japan) was cut into a size of about 3cm, placed on an artificial staining solution, and passed 20 times (one-way distance: 10 cm) under a load of 500g, thereby wiping the fabric. The value obtained by subtracting the 85 ° gloss value before the adhesion of the artificial stain from the 85 ° gloss value after wiping was 85 ° gloss difference. The 60 ° gloss and 85 ° gloss were measured by a BYK Gardner seeded micro gloss meter (ガードナー seeded マイクロ - グロス) (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 μm, and the amount used was 40 parts by mass. The surface of the insulating layer of the obtained electromagnetic wave-shielding film had Sa of 1.02. mu.m, Sdq of 1.26, and Ssk of 2.22. The 60 ° gloss before the adhesion of the artificially contaminated liquid was 1.1 and the 60 ° gloss after the fingerprint wiping was 5.2. The 85 ° gloss before the adhesion of the artificial staining solution was 1.5, the 85 ° gloss after the fingerprint wiping was 1.9, and the 85 ° gloss difference was 0.4. L < lambda > 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 surface of the insulating layer of the obtained electromagnetic wave-shielding film had a Sa of 1.18. mu.m, a Sdq of 1.26, and a Ssk of 2.21. The 60 ° gloss before the adhesion of the artificially contaminated liquid was 0.5 and the 60 ° gloss after the fingerprint wiping was 6.7. The 85 ° gloss before the adhesion of the artificial contaminated liquid was 1.8, the 85 ° gloss after the fingerprint wiping was 2.4, and the difference in 85 ° gloss was 0.6. L < lambda > 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 surface of the insulating layer of the obtained electromagnetic wave-shielding film had a Sa of 1.31. mu.m, a Sdq of 0.95, and a Ssk of 1.47. The 60 ° gloss before the adhesion of the artificially contaminated liquid was 0.5 and the 60 ° gloss after the fingerprint wiping was 1.8. The 85 ° gloss before the adhesion of the artificial contaminated liquid was 1.7, the 85 ° gloss after the fingerprint wiping was 2.5, and the difference in 85 ° gloss was 0.8. L < lambda > 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 unevenness-forming particles, and the amount used was 40 parts by mass. The surface of the insulating layer of the obtained electromagnetic wave-shielding film had Sa of 0.92. mu.m, Sdq of 1.38, and Ssk of 3.10. The 60 ℃ gloss before the adhesion of the artificially contaminated liquid was 2.1 and the 60 ℃ gloss after the fingerprint wiping was 6.1. The 85 ° gloss before the adhesion of the artificial contaminated liquid was 2.1, the 85 ° gloss after the fingerprint wiping was 2.6, and the difference in 85 ° gloss was 0.5. L < lambda > 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 surface of the insulating layer of the obtained electromagnetic wave-shielding film had Sa of 0.92. mu.m, Sdq of 1.02 and Ssk of 2.53. The 60 ° gloss before the adhesion of the artificially contaminated liquid was 1.5 and the 60 ° gloss after the fingerprint wiping was 4.9. The 85 ° gloss before the adhesion of the artificial contaminated liquid was 1.7, the 85 ° gloss after the fingerprint wiping was 3.2, and the 85 ° gloss difference was 1.5. L < lambda > 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 size of 5 μm were used as the unevenness-forming particles, and the amount of the silica particles used was 70 parts by mass. The surface of the insulating layer of the obtained electromagnetic wave-shielding film had a Sa of 1.05 μm, a Sdq of 0.92, and a Ssk of 0.80. The 60 ° gloss before the adhesion of the artificially contaminated liquid was 0.5 and the 60 ° gloss after the fingerprint wiping was 2.4. The 85 ° gloss before the adhesion of the artificial contaminated liquid was 4.6, the 85 ° gloss after the fingerprint wiping was 6.3, and the 85 ° gloss difference was 1.7. L < lambda > 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 as the unevenness-forming particles, and the amount used was 60 parts by mass. The surface of the insulating layer of the obtained electromagnetic wave-shielding film had a Sa of 1.11 μm, a Sdq of 1.12, and a Ssk of 1.46. The 60 ° gloss before the adhesion of the artificially contaminated liquid was 0.4 and the 60 ° gloss after the fingerprint wiping was 1.9. The 85 ° gloss before the adhesion of the artificial contaminated liquid was 3.8, the 85 ° gloss after the fingerprint wiping was 6.5, and the 85 ° gloss difference was 2.7. L < lambda > 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 size of 2 μm were used as the uneven-forming particles and the amount used was 60 parts by mass. The Sa of the surface of the insulating layer 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 adhesion of the artificially contaminated liquid was 0.8, and the 60 ° gloss after the fingerprint wiping was 2.2. The 85 ° gloss before the adhesion of the artificial staining solution was 16.8, the 85 ° gloss after the fingerprint wiping was 26.7, and the 85 ° gloss difference was 9.9. L < lambda > 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 uneven-forming particles was 65 parts by mass. The Sa of the surface of the insulating layer of the obtained electromagnetic wave-shielding film was 0.66. mu.m, Sdq was 0.90, and Ssk was-0.22. The 60 ° gloss before the adhesion of the artificially contaminated liquid was 0.5, and the 60 ° gloss after the fingerprint wiping was 3.9. The 85 ° gloss before the adhesion of the artificial staining solution was 15.9, the 85 ° gloss after the fingerprint wiping was 30.4, and the 85 ° gloss difference was 14.5. L < lambda > value is 21.9.

Comparative example 3

An insulating layer composition containing no particles for forming irregularities was prepared. The resultant was coated on the surface of a support film and dried to be hardened to obtain an insulating layer. The support film was a PET film having a surface with irregularities (Sa 0.60 μm and Sdq 0.61) formed by embossing (エンボス) and a thickness of 20 μm and subjected to a release treatment. Next, after an insulating layer was laminated on 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. The Sa of the surface of the insulating layer of the obtained electromagnetic wave-shielding film was 0.58. mu.m, Sdq was 0.65, and Ssk was-0.78. The 60 ° gloss before the adhesion of the artificially contaminated liquid was 4.2, and the 60 ° gloss after the fingerprint wiping was 9.1. The 85 ° gloss before the adhesion of the artificial staining solution was 34.0, the 85 ° gloss after the fingerprint wiping was 42.8, and the 85 ° gloss difference was 8.8. L < lambda > 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 irregularities (Sa 0.6 μm and Sdq 0.47 μm) on the surface thereof was used as the support film, using silica fine particles. The Sa of the surface of the insulating layer of the obtained electromagnetic wave-shielding film was 0.59. mu.m, Sdq was 0.49, and Ssk was-0.85. The 60 ° gloss before the adhesion of the artificially contaminated liquid was 7.6, and the 60 ° gloss after the fingerprint wiping was 13.3. The 85 ° gloss before the adhesion of the artificial staining solution was 38.7, the 85 ° gloss after the fingerprint wiping was 48.0, and the 85 ° gloss difference was 9.3. The Lx 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 irregularities (Sa 0.47 μm and Sdq 0.59 μm) on the surface thereof by processing with a sand cushion layer (サンドマット) was used as the support film. The Sa of the surface of the insulating layer of the obtained electromagnetic wave-shielding film was 0.45. mu.m, Sdq was 0.58, and Ssk was-0.25. The 60 ° gloss before the adhesion of the artificially contaminated liquid was 5.4, and the 60 ° gloss after the fingerprint wiping was 11.9. The 85 ° gloss before the adhesion of the artificial staining solution was 26.1, the 85 ° gloss after the fingerprint wiping was 51.0, and the 85 ° gloss difference was 24.9. L < lambda > 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 irregularities (Sa 0.45 μm and Sdq 0.56 μm) on the surface thereof by processing with a sand cushion layer (サンドマット) was used as the support film. The Sa of the surface of the insulating layer of the obtained electromagnetic wave-shielding film was 0.45. mu.m, Sdq was 0.54, and Ssk was-0.60. The 60 ° gloss before the adhesion of the artificially contaminated liquid was 9.2, and the 60 ° gloss after the fingerprint wiping was 16.6. The 85 ° gloss before the adhesion of the artificial staining solution was 30.4, the 85 ° gloss after the fingerprint wiping was 54.7, and the 85 ° gloss difference was 24.3. L < lambda > 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 irregularities (Sa 0.51 μm and Sdq 0.55 μm) on the surface thereof by processing with a sand cushion layer (サンドマット) was used as the support film. The Sa of 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 adhesion of the artificially contaminated liquid was 8.6, and the 60 ° gloss after the fingerprint wiping was 16.7. The 85 ° gloss before the adhesion of the artificial staining solution was 21.6, the 85 ° gloss after the fingerprint wiping was 56.7, and the 85 ° gloss difference was 35.1. L < lambda > 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 having irregularities (Sa 0.43 μm and Sdq 0.40 μm) on the surface thereof was used as the support film, using silica fine particles. The Sa of the surface of the insulating layer of the obtained electromagnetic wave-shielding film was 0.42. mu.m, Sdq was 0.38. mu.m, and Ssk was-1.19. The 60 ° gloss before the adhesion of the artificially contaminated liquid was 11.7, and the 60 ° gloss after the fingerprint wiping was 17.9. The 85 ° gloss before the adhesion of the artificial staining solution was 52.4, the 85 ° gloss after the fingerprint wiping was 58.9, and the 85 ° gloss difference was 6.5. L < lambda > 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 size of 5 μm were used as the particles to be added to the insulating layer and the amount of the silica particles used was 40 parts by mass. The Sa of the surface of the insulating layer 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 adhesion of the artificially contaminated liquid was 1.0, and the 60 ° gloss after the fingerprint wiping was 19.8. The 85 ° gloss before the adhesion of the artificial staining solution was 33.2, the 85 ° gloss after the fingerprint wiping was 61.0, and the 85 ° gloss difference was 27.8. L < lambda > 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 having irregularities (Sa 0.36 μm and Sdq 0.36 μm) on the surface thereof was used as the support film, using silica fine particles. The Sa of the surface of the insulating layer of the obtained electromagnetic wave-shielding film was 0.35. mu.m, Sdq was 0.36, and Ssk was-0.31. The 60 ° gloss before the adhesion of the artificially contaminated liquid was 6.9, and the 60 ° gloss after the fingerprint wiping was 12.1. The 85 ° gloss before the adhesion of the artificial staining solution was 58.6, the 85 ° gloss after the fingerprint wiping was 63.0, and the 85 ° gloss difference was 4.4. L < lambda > 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 irregularities (Sa 0.46 μm and Sdq 0.65 μm) on the surface thereof was used as the support film, using silica fine particles. The Sa of the surface of the insulating layer of the obtained electromagnetic wave-shielding film was 0.43. mu.m, Sdq was 0.62, and Ssk was-0.40. The 60 ° gloss before the adhesion of the artificially contaminated liquid was 2.4, and the 60 ° gloss after the fingerprint wiping was 16.6. The 85 ° gloss before the adhesion of the artificial staining solution was 42.6, the 85 ° gloss after the fingerprint wiping was 71.8, and the 85 ° gloss difference was 29.2. The Lx 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 having irregularities (Sa 0.31 μm and Sdq 0.58 μm) on the surface thereof was used as the support film, using silica fine particles. The Sa of the surface of the insulating layer of the obtained electromagnetic wave-shielding film was 0.34. mu.m, Sdq was 0.55, and Ssk was-0.48. The 60 ° gloss before the adhesion of the artificially contaminated liquid was 4.3, and the 60 ° gloss after the fingerprint wiping was 30.2. The 85 ° gloss before the adhesion of the artificial staining solution was 64.2, the 85 ° gloss after the fingerprint wiping was 80.6, and the 85 ° gloss difference was 16.4. L < lambda > value is 24.4.

Comparative example 13

An insulating layer was applied to the surface of the support film and dried and hardened in the same manner as in comparative example 3, except that a PET film having irregularities (Sa 1.5 μm and Sdq 4.89 μm) on the surface thereof by embossing (エンボス) was used as the support film. Next, an insulating layer was bonded to the shield layer produced in the same manner as in example 1. When the support film is to be peeled off, the support film and the insulating layer are firmly adhered to each other, and the insulating layer/shield layer interface is partially broken. The Sa of the surface of the insulating layer where no interfacial damage was observed was 1.3 μm, Sdq was 3.6, and Ssk was-1.60. In addition, since the comparative example had interface breakage, the gloss and L.sup.m value were not measured.

Table 1 shows the surface properties and the evaluation of discoloration of the electromagnetic wave shielding films of the examples and comparative examples. Also shown in Table 1 are values of Sp, Sq, Spk, Vvc, Vmp, a, and b.

[ 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 gloss difference is 4 or less, and discoloration due to wiping of fingerprints is less likely to occur.

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

Practicality of use

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

Description of the symbols

110 insulating layer

120 shield layer

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.