JP2019125618A - Electromagnetic wave shield film - Google Patents

Abstract

To provide an electromagnetic wave shield film in which glossiness of an insulating protective layer is reduced and releasability of a release film is improved.SOLUTION: An electromagnetic wave shield film 101 includes: an insulating protective layer 112; a conductive adhesive layer 111; and a release film 115 provided via a release agent layer 114 on a surface of the insulating protective layer 112 opposite to the conductive adhesive layer 111. The insulating protective layer 112 has an 85° glossiness of less than 15. 85° glossiness on a surface at a side of the insulating protective layer of the release film 115 is less than 3. A thickness of the release agent layer 114 is less than 10 μm.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to an electromagnetic wave shielding film and a shielding wiring board.

  It has been studied to make the circuit pattern of the printed wiring board invisible from the outside. On the other hand, an electromagnetic wave shielding film for shielding electromagnetic noise is attached to the surface of the printed wiring board. A black-based coloring agent is added to the insulating protective layer of the electromagnetic wave shielding film for the purpose of improving the appearance and the visibility of printing (see, for example, Patent Document 1). By sticking the electromagnetic wave shielding film on the printed wiring board, it is possible to make the circuit pattern of the printed wiring board directly invisible.

JP, 2016-143751, A

  However, on the surface of the printed wiring board, there is a step due to the circuit pattern. Therefore, even if an electromagnetic wave shielding film whose insulating protective layer is blackened is attached to a printed wiring board for the purpose of improving the appearance and visibility of printing, a circuit pattern is formed on the surface of the electromagnetic wave shielding film due to light reflection and the like. It may come out and sufficient concealability may not be obtained. For this reason, the electromagnetic wave shielding film which improved concealability further is called for.

  As a method of reducing the reflection of light on the surface of the insulating protective layer, it is conceivable to form fine irregularities on the surface of the insulating protective layer. The insulation protective layer can be formed by applying a resin composition to the surface of the release film and drying it. In this case, since the irregularities on the surface of the release film are transferred to the surface of the insulating protective layer, the gloss of the insulating protective layer can be increased by forming the insulating protective layer using a release film having a small degree of gloss provided with the irregularities. It is expected to become smaller. However, when the glossiness of the release film is reduced, the release of the release film becomes difficult, which may lower the productivity or damage the surface of the insulating protective layer.

  An object of the present disclosure is to make it possible to realize an electromagnetic wave shielding film in which the releasability of a release film is improved while reducing the glossiness of the insulating protective layer.

  One aspect of the electromagnetic wave shielding film of the present disclosure is a peeling provided on a surface of the insulating protective layer, the conductive adhesive layer, and the surface of the insulating protective layer opposite to the conductive adhesive layer via a release agent layer. The insulating protective layer has an 85 ° gloss of less than 15, the 85 ° gloss of the surface on the insulating protective layer side of the release film of less than 3, and a thickness of the release agent layer of less than 10 μm It is.

  In one aspect of the electromagnetic wave shielding film, the insulating protective layer may contain a black colorant.

  One aspect of a shield wiring substrate of the present disclosure is a wiring substrate having a base layer, a circuit pattern provided on the base layer, and an insulating film adhered to the base layer so as to cover the circuit pattern; And the electromagnetic wave shielding film of the present disclosure from which the release film has been removed.

  According to the electromagnetic wave shielding film of the present disclosure, the glossiness of the insulating protective layer can be reduced, and the releasability of the release film can be improved.

It is sectional drawing which shows the electromagnetic wave shield film which concerns on one Embodiment. It is a sectional view showing a shield wiring board concerning one embodiment. It is a top view which shows the circuit pattern for concealability evaluation.

  As shown in FIG. 1, the electromagnetic wave shielding film 101 of the present embodiment is separated on the surface of the conductive adhesive layer 111, the insulating protective layer 112, and the surface of the insulating protective layer 112 opposite to the conductive adhesive layer 111. A release film 115 provided via a mold layer 114 is provided. The insulating protective layer 112 has an 85 ° glossiness of less than 15, the 85 ° glossiness of the surface on the insulating protective layer 112 side of the release film 115 is less than 3, and the thickness of the release agent layer 114 is less than 10 μm. It is.

  In FIG. 1, the conductive shield layer 113 is provided between the conductive adhesive layer 111 and the insulating protective layer 112. However, in the case where the conductive adhesive layer 111 functions as a shield, the shield layer 113 is provided. Can be provided.

  The electromagnetic wave shielding film 101 of the present embodiment can be bonded to the printed wiring board 102 as shown in FIG. 2 to form a shielding wiring board. The printed wiring board 102 includes, for example, a circuit pattern 122 provided on the surface of the base layer 121 and the base layer 121, and an insulating film 124 adhered to the base layer 121 via the adhesive layer 123 so as to cover the circuit pattern 122. have.

  If the insulating protection layer 112 is colored and made opaque, the circuit pattern 122 can not be viewed directly. However, unevenness is formed on the surface of the insulating protection layer 112 by the circuit pattern 122. The general circuit pattern 122 is formed of a copper line, and its height is several micrometers to several tens of micrometers. Since the difference in height between the portion where the line exists and the portion where it does not exist is reduced by embedding the adhesive layer 123 and the conductive adhesive layer 111, the height of the unevenness generated on the surface of the insulating protective layer 112 Is several micrometers. However, even with such a slight unevenness, the presence of the unevenness can be visually recognized on the glossy surface which is likely to reflect light, and the circuit pattern 122 can not be concealed.

  The present inventors have found that the concealability of the circuit pattern can be greatly improved by setting the 85 ° glossiness of the insulating protective layer 112 to less than 15, preferably less than 13, and more preferably less than 10. The 85 ° gloss of the insulating protective layer 112 can be measured by a method in accordance with JIS Z 8741.

  The insulating and protective layer 112 can be formed by applying a resin composition for insulating and protective layer on the surface of the release film 115 to form a sheet. In this case, the unevenness of the release film surface 115 is transferred to the surface of the insulating protection layer 112. Therefore, it is expected that the insulating protective layer 112 having a small degree of glossiness can be obtained by forming the insulating protective layer 112 using a release film 117 having a large surface roughness, that is, a small degree of glossiness. However, when the glossiness of the release film 115 is reduced, the adhesion between the release film 115 and the insulating protective layer 112 is increased, and a large force is required when the release film 115 is released. When the force required for peeling is increased, not only the productivity is lowered, but also the insulating protective layer 112 may be broken to cause defects. Since the peeling film 115 peels after adhering the electromagnetic wave shielding film 101 to the printed wiring board 102, if the peeling film 115 can not be peeled off neatly, the final product becomes a defective product.

  When the release agent layer 114 provided on the surface of the release film 115 is thickened, the release of the release film 115 is facilitated. However, in this case, since the unevenness existing on the surface of the release film 115 is filled with the release agent, the surface of the insulating and protective layer 112 becomes smooth and the glossiness is increased.

  As examined by the present inventors, a release agent having a thickness of 0.1 μm or more, preferably 0.4 μm or more and less than 10 μm, preferably less than 4 μm on the surface of the release film 115 having an 85 ° gloss of less than 3 When the layer 114 was provided, it was found that the 85 ° gloss of the formed insulating protective layer 112 can be made less than 15 and the peelability of the release film 115 can be made good. The 85 ° glossiness and releasability of the release film 115 can be measured by the method described in the examples.

  The material of the release film 115 is not particularly limited as long as the glossiness satisfies a predetermined value. For example, a film of polyolefin type, polyester type, polyimide type, or polyphenylene sulfide type can be used. The thickness of the release film is not particularly limited, but is preferably 25 μm or more and 100 μm or less from the viewpoint of peelability.

  The material of the release agent layer 114 is not particularly limited as long as it has a predetermined thickness, and, for example, melamine resin, polyolefin resin, epoxy resin, alkyd resin, fluorine resin, acrylic resin, paraffin, etc. Resin, urea resin, etc. can be used. For the thickness of the release agent layer, thickness adjustment methods of various coating methods can be applied. For example, in the case of a direct gravure method, control is performed by adjusting the number of plate lines and plate depth and adjusting the solid content of the coating agent. it can. The thickness of the release agent layer can be measured by the method shown in the examples.

  The insulating and protective layer 112 can be formed of a thermoplastic resin, a thermosetting resin, an active energy ray curable resin, or the like. The thermoplastic resin is not particularly limited, but a styrene resin, a vinyl acetate resin, a polyester resin, a polyethylene resin, a polypropylene resin, an imide resin, an acrylic resin or the like can be used. The thermosetting resin is not particularly limited, but a phenol resin, an epoxy resin, a urethane resin having an isocyanate group at an end, a urea resin having an isocyanate group at an end, and a urethane urea resin having an isocyanate group at an end And melamine resins or alkyd resins can be used. The active energy ray-curable resin is not particularly limited, and, for example, a polymerizable compound having at least two (meth) acryloyloxy groups in the molecule can be used. These resins may be used alone or in combination of two or more.

  The insulating protective layer 112 preferably contains a black colorant from the viewpoint of reducing the degree of gloss. The black-based colorant can be a black pigment, or a mixed pigment or the like obtained by subjecting a plurality of pigments to a color reduction mixing. The black pigment can be, for example, carbon black, ketjen black, carbon nanotube (CNT), perylene black, titanium black, iron black, aniline black or the like, or a combination thereof. The mixed pigment can be used by mixing pigments such as red, green, blue, yellow, purple, cyan and magenta. The amount of addition of the black colorant is preferably 0.5% by mass or more, and more preferably 1% by mass or more, with respect to 100 parts by mass of the resin, from the viewpoint of reducing the gloss.

  In the insulating protective layer 112, if necessary, a curing accelerator, a tackifier, an antioxidant, a plasticizer, an ultraviolet absorber, an antifoamer, a leveling agent, a filler, a flame retardant, a viscosity modifier, and At least one such as an antiblocking agent may be included.

  The thickness of the insulating protective layer 112 is not particularly limited and can be set as appropriate, but is 1 μm or more, preferably 4 μm or more, and 20 μm or less, preferably 10 μm or less, more preferably 5 μm or less It can be done. By setting the thickness of the insulating protective layer 112 to 1 μm or more, the conductive adhesive layer 111 and the shield layer 113 can be sufficiently protected. By setting the thickness of the insulating protection layer 112 to 20 μm or less, the flexibility of the electromagnetic wave shield film 101 can be secured, and it becomes easy to apply the electromagnetic wave shield film 101 to a member that requires flexibility. .

  When the shield layer 113 is provided, the shield layer 113 can be formed of a metal foil, a vapor deposition film, a conductive filler, or the like.

  The metal foil is not particularly limited, and can be a foil made of an alloy containing any of nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, zinc and the like, or two or more.

  The deposited film is not particularly limited, and can be formed by depositing nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, zinc and the like. For deposition, electrolytic plating, electroless plating, sputtering, electron beam evaporation, vacuum evaporation, chemical vapor deposition (CVD), metal organic deposition (MOCVD), or the like can be used.

  When the shield layer 113 is formed of a conductive filler, the shield layer 113 can be formed by applying a solvent containing the conductive filler on the surface of the insulating protective layer 112 and drying. As the conductive filler, metal fillers, metal-coated resin fillers, carbon fillers and mixtures thereof can be used. As the metal filler, copper powder, silver powder, nickel powder, silver-coated copper powder, gold-coated copper powder, silver-coated nickel powder, gold-coated nickel powder, etc. can be used. These metal powders can be prepared by an electrolysis method, an atomization method, or a reduction method. The shape of the metal powder may, for example, be spherical, flake, fibrous, dendritic or the like.

  In the present embodiment, the thickness of the shield layer 113 may be appropriately selected according to the required electromagnetic shielding effect and repeated bending / sliding resistance, but in the case of a metal foil, it is 12 μm from the viewpoint of securing breaking elongation. It is preferable to set it as the following.

  In the present embodiment, the conductive adhesive layer 111 contains at least one of a thermoplastic resin, a thermosetting resin, an active energy ray curable resin, and the like, and a conductive filler.

  When the conductive adhesive layer 111 contains a thermoplastic resin, for example, a styrene resin, a vinyl acetate resin, a polyester resin, a polyethylene resin, a polypropylene resin, an imide resin, and an acrylic resin as a thermoplastic resin It can be used. These resins may be used alone or in combination of two or more.

  When the conductive adhesive layer 111 contains a thermosetting resin, for example, a phenolic resin, an epoxy resin, a urethane resin, a melamine resin, a polyamide resin, an alkyd resin, etc. can be used as the thermosetting resin. . The active energy ray-curable resin is not particularly limited, but, for example, a polymerizable compound having at least two (meth) acryloyloxy groups in the molecule can be used. These resins may be used alone or in combination of two or more.

  The thermosetting resin includes, for example, a first resin component having a reactive first functional group, and a second resin component that reacts with the first functional group. The first functional group can be, for example, an epoxy group, an amido group, or a hydroxyl group. The second functional group may be selected according to the first functional group. For example, when the first functional group is an epoxy group, it may be a hydroxyl group, a carboxyl group, an epoxy group, an amino group or the like. Specifically, for example, when the first resin component is an epoxy resin, an epoxy group modified polyester resin, an epoxy group modified polyamide resin, an epoxy group modified acrylic resin, an epoxy group modified polyurethane polyurea resin, and a carboxyl group as the second resin component. A group modified polyester resin, a carboxyl group modified polyamide resin, a carboxyl group modified acrylic resin, a carboxyl group modified polyurethane polyurea resin, and a urethane modified polyester resin can be used. Among these, carboxyl group modified polyester resin, carboxyl group modified polyamide resin, carboxyl group modified polyurethane polyurea resin, and urethane modified polyester resin are preferable. When the first resin component is a hydroxyl group, an epoxy group modified polyester resin, an epoxy group modified polyamide resin, an epoxy group modified acrylic resin, an epoxy group modified polyurethane polyurea resin, a carboxyl group modified polyester resin as the second resin component, A carboxyl group modified polyamide resin, a carboxyl group modified acrylic resin, a carboxyl group modified polyurethane polyurea resin, a urethane modified polyester resin, etc. can be used. Among these, carboxyl group modified polyester resin, carboxyl group modified polyamide resin, carboxyl group modified polyurethane polyurea resin, and urethane modified polyester resin are preferable.

  The thermosetting resin may contain a curing agent that accelerates the thermosetting reaction. When the thermosetting resin has the first functional group and the second functional group, the curing agent can be appropriately selected according to the types of the first functional group and the second functional group. When the first functional group is an epoxy group and the second functional group is a hydroxyl group, an imidazole-based curing agent, a phenol-based curing agent, a cationic curing agent, or the like can be used. One of these may be used alone, or two or more may be used in combination. In addition, as an optional component, an antifoamer, an antioxidant, a viscosity modifier, a diluent, an antisettling agent, a leveling agent, a coupling agent, a coloring agent, a flame retardant and the like may be contained.

  The conductive filler is not particularly limited, and, for example, metal fillers, metal-coated resin fillers, carbon fillers and mixtures thereof can be used. Examples of the metal filler include copper powder, silver powder, nickel powder, silver-coated copper powder, gold-coated copper powder, silver-coated nickel powder, and gold-coated nickel powder. These metal powders can be produced by an electrolysis method, an atomization method, a reduction method or the like. Among them, silver powder, silver-coated copper powder and copper powder are preferable.

  The conductive filler preferably has an average particle diameter of 1 μm or more, more preferably 3 μm or more, preferably 50 μm or less, more preferably 40 μm or less, from the viewpoint of contact between the fillers. The shape of the conductive filler is not particularly limited, and may be spherical, flake-like, dendritic or fibrous.

  The content of the conductive filler can be appropriately selected according to the application, but it is preferably 5% by mass or more, more preferably 10% by mass or more, preferably 95% by mass or less, in the total solid content. It is 90 mass% or less. From the viewpoint of embeddability, it is preferably 70% by mass or less, more preferably 60% by mass or less. Moreover, when realizing anisotropic conductivity, it is preferably 40% by mass or less, more preferably 35% by mass or less.

  The thickness of the conductive adhesive layer 111 is preferably 1 μm to 50 μm from the viewpoint of embeddability.

  Hereinafter, the electromagnetic wave shielding film of the present disclosure will be described in more detail using examples. The following examples are illustrative and are not intended to limit the present invention.

<Preparation of electromagnetic wave shield film>
A release agent was applied using a wire bar on the surface on the insulating layer side of a release film made of polyethylene terephthalate (PET) having a predetermined glossiness to form a release agent layer of a predetermined thickness. The thickness of the release agent layer was measured by an optical interference type film thickness meter (manufactured by K-MAC, ST-2000-DLXn). The composition for the insulating protective layer is applied using a wire bar on the side of the release film on which the release agent layer is formed, on which the release agent layer is formed, and dried by heating to a thickness of 5 μm A protective layer was formed. Next, an Ag vapor deposition film of 0.1 μm was formed as a shield layer on the insulating protective layer. After applying the composition for a conductive adhesive layer with a wire bar on the shield layer, drying was performed at 100 ° C. for 3 minutes to form a conductive adhesive layer having a thickness of 15 μm.

  As a release agent, an alkyd resin type was used. The insulating protective layer had a two-layer structure of a hard coat layer of polyester-based transparent resin having a thickness of 2 μm and a soft coat layer of a carbon black-containing epoxy-based black resin having a thickness of 3 μm. In the composition for a conductive adhesive layer, conductive particles of silver-coated copper powder are used for a phosphorus-based flame retardant-containing epoxy resin.

<Production of shield wiring board>
The obtained electromagnetic wave shielding film and the printed wiring board were bonded using a press at a temperature of 170 ° C., a time of 3 minutes, and a pressure of 2 to 3 MPa to produce a shielded wiring board.

  As the printed wiring board, one in which a circuit pattern 122 as shown in FIG. 3 was formed on a base layer 121 made of a polyimide film was used. The circuit pattern 122 was formed of a copper foil having a line width of 0.1 mm and a height of 12 μm. An adhesive layer having a thickness of 25 μm and a cover lay (insulating film) made of a polyimide film having a thickness of 12.5 μm were provided on the base layer 121 so as to cover the circuit pattern.

<Evaluation of peelability>
After adhering the electromagnetic wave shielding film to the printed wiring board, the peeling film on the surface is peeled off at a sample width of 10 mm, a peeling angle of 170 °, and a peeling speed of 1000 mm / min using a peel strength tester (PFT50S manufactured by Palmec Co., Ltd.) Was evaluated. When the peeling film peels without breaking the material during peeling, the peeling property is good, and when the peeling film breaks when peeling, the peeling property is bad.

<Measurement of glossiness>
The 85 ° gloss was measured according to JIS Z 8741 using a portable gloss meter (BYK Gardner Micro-Gloss, Toyo Seiki Seisakusho).

  The glossiness of the release film was measured with respect to the surface on the insulating layer protective layer side in the release film before applying the release agent.

  The glossiness of the insulating protective layer was measured after the electromagnetic wave shielding film was adhered to the printed wiring board and the peeling film was peeled off.

<Evaluation of concealability>
The shield wiring board bonded with the electromagnetic wave shielding film was placed on a flat table surface, and it was evaluated whether the circuit pattern could be viewed from the electromagnetic wave shielding film side under an environment where the illuminance of the surface of the shield wiring board was 800-1000 lux. . The viewing angle was in the range of 0 to 180 degrees with respect to the electromagnetic shielding film surface. The case where the circuit pattern can not be visually recognized is regarded as good in the concealability (○), and the case where the circuit pattern can be visually recognized is regarded as poor in the concealability (x).

Example 1
As a release film, a PET film having a thickness of 50 μm and an 85 ° gloss of 2.3 was used. A release agent layer having a thickness of 0.7 μm was formed on the side of the release film on the side of the insulating protective layer. The releasability of the release film was good. The 85 ° glossiness of the insulating protective layer after peeling off the release film was 9.2. In addition, the concealability was good.

(Example 2)
As a release film, a PET film having a thickness of 50 μm and an 85 ° gloss of 2.3 was used. A release agent layer having a thickness of 3.0 μm was formed on the surface of the release film on the insulating protective layer side. The releasability of the release film was good. The 85 ° glossiness of the insulating protective layer after peeling off the release film was 9.6. In addition, the concealability was good.

(Comparative example 1)
As a release film, a PET film having a thickness of 50 μm and an 85 ° glossiness of 19.3 was used. A release agent layer having a thickness of 0.4 μm was formed on the side of the release film on the insulating protective layer side. The releasability of the release film was good. The 85 ° glossiness of the insulating protective layer after peeling the peeling film was 35.4. Also, the concealability was poor.

(Comparative example 2)
As a release film, a PET film having a thickness of 50 μm and an 85 ° gloss of 2.3 was used. A release agent layer having a thickness of 10.0 μm was formed on the surface of the release film on the insulating protective layer side. The releasability of the release film was poor. The 85 ° glossiness of the insulating protective layer after peeling off the release film was 15.5. Also, the concealability was poor.

(Comparative example 3)
As a release film, a PET film having a thickness of 50 μm and an 85 ° gloss of 2.3 was used. A release agent layer having a thickness of 0.05 μm was formed on the surface of the release film on the insulating protective layer side. The releasability of the release film was poor.

  Table 1 collectively shows each embodiment and comparative example.

  The electromagnetic wave shielding film of the present disclosure has a small degree of gloss of the insulating protective layer and can easily peel the peeling film, and is useful as an electromagnetic wave shielding film or the like.

DESCRIPTION OF SYMBOLS 101 Electromagnetic wave shield film 102 Printed wiring board 111 Conductive adhesive layer 112 Insulation protective layer 113 Shield layer 114 Release agent layer 115 Peeling film 121 Base layer 122 Circuit pattern 123 Adhesive layer 124 Insulating film

Claims (3)

An insulating protective layer,
Conductive adhesive layer,
A release film provided via a release agent layer on the surface of the insulating protective layer opposite to the conductive adhesive layer,
The insulating protective layer has an 85 ° gloss of less than 15;
85 degree glossiness in the surface at the side of the said insulating protective layer of the said peeling film is less than 3,
The electromagnetic shielding film, wherein the thickness of the release agent layer is less than 10 μm.   The electromagnetic wave shielding film according to claim 1, wherein the insulating protection layer contains a black colorant. A wiring substrate having a base layer, a circuit pattern provided on the base layer, and an insulating film adhered to the base layer so as to cover the circuit pattern;
The electromagnetic wave shielding film according to claim 1 or 2 adhered on the insulating film and the peeling film removed.

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