TW201735767A - Electromagnetic wave shield material for FPC - Google Patents

Abstract

The present invention provides an electromagnetic wave shield material for FPC that has excellent adherence strength between the substrate, and a conductive paste layer and a conductive adhesive layer, that has no partial delamination at the adhesive interface between the substrate and the conductive paste layer even if a bending operation is repeated, and for which deterioration over time of electromagnetic shielding performance is suppressed. In accordance with the present invention, an electromagnetic wave shield material for FPC 10 in which, on one surface of a support film 6, are laminated a substrate 1 comprising a thin-film resin film of a coated dielectric, an anchor coat layer 2, a conductive paste layer 3, and a conductive adhesive layer 4 in order, and a compound which is capable of being cured by penetrating is included in a part of the conductive adhesive layer 4, and in the anchor coat layer 2 and/or the conductive paste layer 3, is provided. The conductive adhesive layer 4 preferably includes an epoxy resin having a number average molecular weight of 1,500 or less.

Description

Electromagnetic shielding material for flexible printed circuit boards

The present invention relates to an electromagnetic shielding material for a flexible printed circuit board which is coated with a flexible printed circuit board (hereinafter referred to as "FPC") which is repeatedly subjected to a bending operation for shielding electromagnetic waves.

In a portable electronic device such as a mobile phone or a tablet terminal, electronic components are integrated on a printed circuit board in order to control the outer dimensions of the casing to be small and easy to carry. Further, in order to reduce the outer dimensions of the casing, the printed circuit board can be divided into a plurality of pieces, and a flexible FPC can be used for the connection wiring between the divided printed circuit boards, whereby the printed circuit can be made. The board folds or slides.

Further, in recent years, in order to prevent an electronic device from being erroneously operated by electromagnetic wave noise received from the outside or electromagnetic wave noise received between internal electronic components, an electromagnetic wave shielding material is used to coat an important electronic component or FPC. .

Conventionally, as the electromagnetic wave shielding material used for the purpose of shielding electromagnetic waves, a material in which an adhesive layer is provided on the surface of a metal foil such as a rolled copper foil or a soft aluminum foil is used. The shielding object is covered with an electromagnetic wave shielding material composed of such a metal foil (for example, refer to Patent Documents 1 and 2).

Specifically, in order to shield important electronic components from electromagnetic waves, a metal foil or a metal plate is used to form a closed box and cover it. Further, in order to shield the curved FPC wiring from electromagnetic waves, a material having an adhesive layer provided on one surface of the metal foil is used, and the adhesive layer is bonded to each other.

In recent years, as an electronic device that is carried around, mobile phones, tablet terminals, and the like have been rapidly popularized. In the case of a mobile phone, it is desirable to have the overall size as small as possible when stored in a pocket or the like without using it, and it is desirable to increase the overall size when using it. Therefore, there is a demand for miniaturization, thinning, and improvement of operability of mobile phones. As a method for solving these problems, the mobile phone adopts a frame structure of a folding opening and closing method and a sliding opening and closing method.

In addition, in the mobile phone, whether the folding opening/closing method or the sliding opening/closing system is used, the operation screen is frequently opened and closed (starting and stopping operations) in daily life, and the number of opening and closing of the operation screen is several tens of times/ It is carried out at a frequency of days or hundreds of times per day.

Then, the FPC used in the mobile phone and the electromagnetic wave shielding material for FPC that covers the electromagnetic wave mask covered by the FPC are repeatedly subjected to the bending operation at a frequency exceeding the common knowledge of the conventional portable electronic device. Therefore, the FPC electromagnetic wave shielding material that exhibits the electromagnetic wave shielding effect of the FPC is subjected to severe repeated stress. When the repetitive stress is not able to withstand, the substrate constituting the electromagnetic wave shielding material for FPC and the shielding material such as the metal foil are damaged by breakage or peeling, and the function as an electromagnetic wave shielding material for FPC may be degraded or eliminated.

For this reason, there has been an electromagnetic wave shielding material that is subjected to such repeated bending operations (for example, see Patent Document 3).

Rolled copper foil, soft as disclosed in the above Patent Documents 1 and 2 In the electromagnetic wave shielding material in which the adhesive layer is provided on the surface of the metal foil such as aluminum foil, when the number of bending operations is small and the use time is short, the mask performance is not trouble-free. However, when the use time is as long as 5 to 10 years and the number of bending operations is increased, there is a problem that the bending property is insufficient. Such a conventional electromagnetic wave shielding material does not have the excellent bending characteristics which are required to pass the bending test of 1 million times or more required for the electromagnetic wave shielding material for FPC which has been recently used for mobile phones.

Further, in the electromagnetic wave shielding material in which a conductive paste layer such as metal vapor deposition is provided on one surface of the flexible film and a conductive adhesive is laminated on the conductive paste layer, the coating can be coated. It is used on wires that are subjected to repeated bending operations. According to the embodiment of Patent Document 3, a coating film of a silver-containing conductive coating material having a thickness of 0.5 μm is provided on one surface of a polyester film having a thickness of 12 μm, and a conductive adhesive layer having a thickness of 30 μm is provided on the coating film. The conductive adhesive layer is obtained by heating and drying a conductive adhesive mixed with a polyester-based adhesive and nickel powder. In addition, it will be 10mm along the outer diameter When the outer circumference of the mandrel was bent at an angle of 180° and then returned to a straight line as a loop bending test, when the bending test was performed 500,000 times, it was confirmed that there was no damage.

However, in recent mobile phones, the thickness of the frame outer dimensions is reduced by 0.1 mm, and it is required to be as thin as possible. For an electromagnetic wave shielding material for FPC which can be used in such a thin casing and has bending property, for example, it is required to be subjected to a bending test of 1 million times or more without damage, wherein the bending test is to be 2 mm along the outer diameter. The outer circumference of the mandrel is bent at an angle of 180° and then restored to a straight line as a loop test of the loop. Compared with the prior art, there is a need for an electromagnetic wave shielding material for FPC that can overcome the bending test under severe conditions.

Further, in the electromagnetic wave shielding material according to the embodiment of the patent document 3, a coating film of a conductive coating material having a thickness of 0.5 μm and a conductive adhesive layer having a thickness of 30 μm are laminated on a resin film having a thickness of 12 μm, and the electromagnetic wave shielding material is provided. The total thickness exceeds 40 μm.

As described above, in order to make the outer frame size of the mobile phone as thin as possible, the total thickness of the electromagnetic wave shielding material for FPC is required to be as thin as 30 μm or less. In other words, compared with the conventional electromagnetic wave shielding material for FPC, a durable electromagnetic shielding material for FPC which has a thinner total thickness and can withstand a more severe bending test is required.

Further, in the conductive adhesive used for the electromagnetic wave shielding material for FPC, in order to make the adhesive layer conductive, it is necessary to add a large amount of conductive powder (metal fine particles or carbon fine particles), but this may cause the adhesive layer to The adhesion is reduced.

In addition, in the electromagnetic wave shielding material for FPC of a mobile phone, since the adhesive force between the base material and the conductive paste layer is weak, the height difference followability when it is attached to the uneven surface is broken, or it is repeated. In the bending operation, the partial adhesion interface between the substrate and the conductive paste layer is delaminated to cause the conductive paste layer to be broken at the peeling portion, and therefore, there is a problem that the electromagnetic wave mask performance is lowered with time.

In addition, the substrate itself must also have excellent bending characteristics that withstand repeated bending motions (e.g., 1 million bending tests) during the life of the electronic device.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Unexamined Publication No. SHO 56-084221

[Patent Document 2] Japanese Patent Laid-Open No. 61-222299

[Patent Document 3] Japanese Patent Laid-Open No. 7-122883

An object of the present invention is to provide an electromagnetic wave shielding material for FPC which is flexible, has a reduced thickness, and has a high degree of followability, and can prevent a decrease in electromagnetic wave mask performance even when a severe bending operation is repeated. The adhesion between the substrate and the conductive paste layer and the conductive adhesive layer is excellent, and even if the bending operation is repeated, the interlayer adhesion between the substrate and the conductive paste layer does not occur, and the electromagnetic wave mask performance is suppressed. The phenomenon of falling time.

In order to withstand a severe bending action and to have a height difference followability, a substrate composed of a heat resistant resin film is used in the present invention. The technical idea of the present invention is to sequentially laminate an anchor coat layer, a conductive paste layer and a conductive adhesive layer on a substrate composed of a thin film resin film of a coated dielectric, wherein the conductive layer The adhesive layer contains an epoxy resin having a number average molecular weight of 1,500 or less, thereby improving the adhesion between the substrate and the conductive paste layer and the conductive adhesive layer, ensuring the performance of the electromagnetic wave shielding material for FPC, and improving the bending. Performance and height difference followability.

Further, in the present invention, in consideration of flexibility and heat resistance, a film resin film coated with a dielectric is used as a substrate made of a heat resistant resin film, whereby FPC for removing the support film and the release film can be used. Total electromagnetic shielding material The thickness is as thin as 25 μm or less.

Further, in the present invention, in order to increase the adhesion between the polyimide film formed of the solvent-soluble polyimine as a substrate and the conductive paste layer, an increase is provided between the substrate and the conductive paste layer. Adhesive coating.

Therefore, in order to solve the above problems, the present invention provides an electromagnetic wave shielding material for FPC in which a substrate, a tackifying coating layer, a conductive paste layer, and a film of a film resin having a coated dielectric are sequentially laminated on one surface of a support film. The conductive adhesive layer is formed, and a part of the composition forming the conductive adhesive layer contains a component that can penetrate into the adhesion-promoting coating layer and/or the conductive paste layer and cure.

Further, preferably, the conductive adhesive layer contains an epoxy resin having a number average molecular weight of 1,500 or less, and at least a part of the epoxy resin penetrates into the interior of the adhesion-promoting coating layer and/or the conductive paste layer and is semi-cured. .

Further, it is preferable that the conductive adhesive layer contains a flame-retardant polyurethane resin and an epoxy resin having a number average molecular weight of 1,500 or less.

Further, it is preferred that the substrate has a polyimide film formed using a solvent-soluble polyimine and has a thickness of 1 to 9 μm.

Further, the tackifying coating layer is obtained by crosslinking a resin composition containing a polyester resin having an epoxy group, and the thickness of the tackifying coating layer is 0.05 to 1 μm.

Further, it is preferable that the adhesion-promoting coating further contains one or more black pigments selected from the group consisting of carbon black, graphite, nigrosine, cyanine black, titanium black, iron oxide black, chromium oxide, and manganese oxide. Or a light absorbing material composed of one or more colored pigments.

In addition, it is preferred that the conductive paste layer is at a temperature of 150 to 250 ° C. The conductive paste is calcined and has a thickness of 0.1 to 2 μm. The conductive paste contains silver nanoparticle having an average particle diameter of 1 to 120 nm and a binder resin composition.

In addition, it is preferred that the conductive paste layer has a volume resistivity of 1.5×10 ⁻⁵ Ω. Below cm.

Further, it is preferable that the release film which has been subjected to the release treatment is further bonded to the conductive adhesive layer.

Moreover, the present invention provides a mobile phone in which the electromagnetic wave shielding material for FPC described above is used as a member for electromagnetic wave shielding.

Moreover, the present invention provides an electronic device in which the electromagnetic wave shielding material for FPC described above is used as a member for electromagnetic wave shielding.

According to the electromagnetic wave shielding material for FPC of the present invention, the adhesion-promoting coating layer, the conductive paste layer, and the conductive adhesive layer are sequentially laminated on the substrate of the film resin film having the applied dielectric. Since the composition for forming the conductive adhesive layer contains an epoxy resin having a number average molecular weight of 1,500 or less, the adhesion between the substrate and the conductive paste layer and the conductive adhesive layer can be improved. In addition, since the conductive adhesive layer contains an epoxy resin having a number average molecular weight of 1,500 or less, and the epoxy resin can penetrate into the adhesion-promoting coating layer and/or the interior of the conductive paste layer and is semi-cured, it can be flexible. The circuit board is completely cured by heating and pressure-bonding treatment, whereby the adhesion between the substrate and the conductive paste layer and the conductive adhesive layer can be improved.

In addition, a film resin film (thickness of 1 to 9 μm), a tackifying coating layer, and a conductive paste layer using a polyimide film formed using a solvent-soluble polyimide, in the substrate and the conductive paste layer When the adhesion is improved, the thickness can be suppressed Electromagnetic wave mask performance.

Thereby, the total thickness of the FPC electromagnetic wave shielding material from which the support film and the release film are removed can be controlled to 25 μm or less, which contributes to the reduction in the total thickness of the mobile phone and the electronic device.

By incorporating a light absorbing material composed of one or more black pigments or colored pigments into the adhesion-promoting coating layer, specific coloring can be performed on one side of the mask film.

As described above, according to the present invention, it is possible to provide an electromagnetic wave shielding material for FPC which is excellent in bending property and which is excellent in flexibility and which is thinner and which does not deteriorate even if the electromagnetic wave shielding performance is repeated.

1‧‧‧Substrate

2‧‧‧Anchor coat layer

3‧‧‧ Conductive paste layer

4‧‧‧ Conductive adhesive layer

6‧‧‧Support film

7‧‧‧Release film

10, 11‧‧‧FPC electromagnetic shielding materials

Fig. 1 is a schematic cross-sectional view showing an embodiment of an electromagnetic wave shielding material for FPC of the present invention.

Fig. 2 is a schematic cross-sectional view showing another embodiment of the electromagnetic wave shielding material for FPC of the present invention.

Preferred embodiments of the present invention will now be described.

In the FPC electromagnetic shielding material of the present invention, when it is bonded to an FPC or the like as an adherend, the outer surface thereof is a dielectric. Therefore, it is not necessary to bond the insulating film to the outer surface of the electromagnetic wave shielding material for FPC. Further, in order to improve the bending property against the bending operation, the total thickness of the electromagnetic wave shielding material for FPC of the present invention is thin.

In the electromagnetic wave shielding material 10 for FPC of the present invention shown in FIG. 1, The substrate 1 is a film-treated resin film of a coated dielectric (preferably a polyimide film having a thickness of 1 to 9 μm and using a solvent-soluble polyimine). The support film 6 is laminated on one surface of the substrate 1, and the adhesion-promoting coating 2 for improving the adhesion between the conductive paste layer 3 and the substrate 1 is sequentially laminated on the other surface of the substrate 1. Paste layer 3 and conductive adhesive layer 4. In the electromagnetic wave shielding material 11 for FPC according to another embodiment of the present invention shown in FIG. 2, a release film 7 is laminated on the conductive adhesive layer 4 in this order. The electromagnetic wave shielding material 11 for FPC can be used as an electromagnetic wave shielding material for FPC for removing the support film 6 and the release film 7.

(Substrate of film resin film having dielectric)

As the base material 1 of the electromagnetic wave shielding materials 10 and 11 for FPC of the present invention, a dielectric thin film resin film formed by coating on one surface of the support film 6 is used. In particular, a film resin film of a polyimide film formed using a solvent-soluble polyimine has high mechanical strength, heat resistance, insulation, and solvent resistance as characteristics of a polyimide resin, up to about 260 ° C. Temperature, its chemical properties are stable.

Examples of the polyimine are a thermosetting polyimine formed by heating a polycondensation reaction of polyamic acid, and a solvent-soluble polyimine soluble in a non-dehydration condensation type solvent.

As a method for producing a general polyimide film, a generally known method is to react a diamine with a carboxylic acid dianhydride in a polar solvent to synthesize a poly-proline which is a precursor of a quinone imine by heating. The polyaminic acid or a catalyst is used for dehydration cyclization to form the corresponding polyimine. However, in the ruthenium imidization step, the temperature of the heat treatment is preferably in the range of 200 ° C to 300 ° C. If the heating temperature is lower than the temperature, there is a possibility that the imidization is not carried out, which is less desirable. If When the heating temperature is higher than the above temperature, thermal decomposition of the compound may occur, which is less desirable.

In order to further improve the flexibility of the substrate, the electromagnetic wave shielding material for FPC of the present invention preferably uses an extremely thin polyimide film having a thickness of less than 10 μm.

Therefore, it is necessary to form a thin polyimide film on one surface of the support film 6 used as the strength reinforcing material. However, although the polyimide film itself has heat resistance to heat treatment at a heating temperature of 200 ° C to 250 ° C, as the support film 6, since a price and a heat resistant temperature performance are simultaneously considered, a general heat resistant resin is used. As the film, for example, a polyethylene terephthalate (PET) resin film is used, and therefore, a conventional method of forming a polyimine from polylysine which is a precursor of a quinone imine cannot be used.

For the solvent-soluble polyimine, it completes the oxime imidization of the polyimine and is soluble in the solvent. Therefore, after coating the coating solution dissolved in the solvent, the temperature is lower than 200 ° C. The solvent is volatilized, whereby film formation can be achieved. Therefore, the substrate 1 used for the electromagnetic wave shielding material for FPC of the present invention can be applied to a single surface of the support film 6 by applying a non-dehydration condensation type solvent-soluble polyimide film coating liquid to a temperature lower than 200 ° C. The film was dried at a heating temperature to obtain a film resin film of a polyimide film formed of a solvent-soluble polyimide. By this, an extremely thin polyimide film having a thickness of 1 to 9 μm can be laminated on one surface of the support film 6 made of a general-purpose heat resistant resin film. Since the support film 6 can be conveyed along the longitudinal direction of the support film 6, the substrate 1, the adhesion-promoting coating 2, the conductive paste layer 3, and the like are continuously formed thereon, so that roll-to-roll can also be used. Roll-to-roll) production method.

The non-dehydrated condensed solvent-soluble polyimine used in the present invention is not particularly limited, and a commercially available solvent-soluble polyimine coating liquid can be used. Specific examples of the solvent-soluble polyimine coating liquid which are commercially available include Solpit 6, 6-PI (Solpit Industries, Ltd.), Q-IP-0895D (Pi Technology Research Co., Ltd.), and PIQ (Hitachi Chemical Co., Ltd.). Industrial), SPI-200N (Nippon Steel Chemical), Rikacoat SN-20, Rikacoat PN-20 (New Japan Physical and Chemical), etc. The coating method of applying the solvent-soluble polyimine coating liquid onto the support film 6 is not particularly limited, and for example, a coating machine such as a die coater, a knife coater, or a lip coater can be used. Coating is carried out.

Preferably, the polyimide film used in the present invention has a thickness of 1 to 9 μm. When the thickness of the polyimide film is less than 0.8 μm, the film produced is inferior in mechanical strength, and thus it is technically difficult. In addition, when the thickness of the polyimide film exceeds 10 μm, it is difficult to obtain electromagnetic wave shielding materials 10 and 11 for FPC having excellent bending properties.

(support film)

The base material of the support film 6 used in the present invention may, for example, be a polyethylene terephthalate, a polybutylene terephthalate or a polyethylene naphthalate. Ester film; polyolefin film such as polypropylene or polyethylene.

When the base material of the support film 6 is, for example, a substrate such as polyethylene terephthalate having a certain degree of releasability, the support film 6 can be directly laminated without performing a peeling treatment. The base material 1 composed of the thin film resin film of the dielectric material to be coated may be subjected to a peeling treatment for making the base material 1 more easily peeled off on the surface of the support film 6.

Further, when the base film used as the above-mentioned support film 6 does not have releasability In this case, a release agent such as an amine-based alkyd resin or a ruthenium resin is applied, followed by heat drying to carry out a release treatment. Since the electromagnetic wave shielding materials 10 and 11 for FPC of the present invention are bonded to the FPC, it is preferable to use no enamel resin in the above-mentioned release agent. The reason for this is that if a ruthenium resin is used as the release agent, a part of the ruthenium resin migrates to the surface of the substrate 1 which is in contact with the surface of the support film 6, and further, the inside of the substrate is irradiated by the FPC. The possibility of the material 1 moving toward the conductive adhesive layer 4. Therefore, there is a possibility that the resin which has moved to the surface of the above-mentioned conductive adhesive layer 4 weakens the adhesive force of the conductive adhesive layer 4. The thickness of the support film 6 used in the present invention is excluded from the total thickness of the FPC electromagnetic wave shielding material 11 when it is bonded to the FPC, and therefore the thickness of the support film 6 is not particularly limited. Limit, but usually about 12~150μm.

(adhesive coating)

The adhesion-promoting coating layer 2 used in the electromagnetic wave shielding materials 10 and 11 for FPC of the present invention is for improving the film of the polyimide film formed of the solvent-soluble polyimine as the substrate 1 and the conductive paste film 3 Set between the adhesions.

For the adhesion-promoting coating layer 2, since the conductive paste layer 3 applied thereon is formed by a heating calcination step of the applied conductive paste, the adhesion-promoting coating layer 2 must use a resin excellent in heat resistance.

Further, the adhesion-promoting coating layer 2 must have excellent adhesion to the dielectric thin film resin mold (for example, a polyimide film formed using solvent-soluble polyimide) which is the substrate 1 and the conductive paste layer 3.

The resin used in the adhesion-promoting coating layer 2 preferably contains an acrylic resin, a polyurethane resin, a polyester resin, a cellulose resin, and a ring. One or more resins selected from the group consisting of an oxygen resin and a polyamide resin.

The adhesive resin composition as the tackifying coating layer 2 is particularly preferably an adhesive resin composition obtained by crosslinking a polyester resin composition having an epoxy group, or as a curing agent. An adhesive resin composition obtained by mixing an epoxy resin into a polyurethane resin. Therefore, the adhesion-promoting coating layer 2 has a harder property than the substrate 1 composed of a polyimide film formed by laminating a solvent-soluble polyimide. The polyester-based resin composition having an epoxy group is not particularly limited, and for example, an epoxy resin having two or more epoxy groups in one molecule (an uncured resin thereof) and two or more carboxyl groups in one molecule may be used. The reaction of a polyvalent carboxylic acid or the like is obtained. In the crosslinking reaction of the epoxy resin composition having an epoxy group, a crosslinking agent for an epoxy resin which reacts with an epoxy group can be used.

Further, the adhesion-promoting coating layer 2 may contain one or more kinds of black pigments selected from the group consisting of carbon black, graphite, aniline black, cyanine black, titanium black, iron oxide black, chromium oxide, and manganese oxide, or more than one type. A light absorbing material composed of a colored pigment (colored pigment). It is preferred to incorporate a black pigment such as carbon black into these light absorbing materials. It is preferable that the adhesion-promoting coating layer 2 contains 0.1 to 30% by weight of a light absorbing material composed of a black pigment or a coloring pigment. The average particle diameter of the primary particles of the black pigment or the colored pigment observed by SEM is preferably about 0.02 to 0.1 μm.

In addition, as the black pigment, a pigment obtained by immersing the cerium oxide particles or the like in a black coloring material and forming only the surface layer portion to be black may be used, and a pigment which is formed of a black colored resin or the like and which is entirely black may be used. In addition, black pigments may contain gray, dark brown, or dark green, similar to black, in addition to pure black. Colored particles can be used as long as they are dark colors that are difficult to reflect light.

The thickness of the adhesion-promoting coating layer 2 is preferably about 0.05 to 1 μm, and the film thickness of this level can obtain a sufficient adhesive force of the conductive paste layer 3. When the thickness of the adhesion-promoting coating layer 2 is 0.05 μm or less, the fine particles of the light absorbing material may be exposed to lower the adhesion between the substrate 1 and the conductive paste layer 3. Further, even if the thickness of the adhesion-promoting coating layer 2 exceeds 1 μm, there is no effect on the increase in the adhesion of the substrate 1 or the conductive paste layer 3 composed of the polyimide film formed using the solvent-soluble polyimine, and thus the viscosity is increased. The thickness of the coating layer 2 exceeding 1 μm means an increase in cost and thus is less desirable.

(conductive paste layer)

In the conductive paste layer 3 of the present invention, a conductive paste in which a conductive filler is mixed into a resin composition as a binder is used. The conductive paste preferably contains one or more kinds of fillers selected from the group consisting of conductive metal particles, carbon nanotubes, and carbon nanofibers, and a binder resin composition. As the conductive metal particles, metal fine powders such as copper, silver, nickel, and aluminum can be used. However, from the viewpoint of high conductivity and low cost, it is preferable to use fine powder of copper or silver or nano particles (copper nanoparticles). , silver nanoparticles, etc.). Further, a carbon nanotube or a carbon nanofiber which is a conductive carbon nanoparticle can also be used.

Preferably, the volume resistivity of the conductive paste layer 3 after calcination is 1.5×10 ^-5 Ω. Below cm. Further, it is preferable that the surface resistivity of the conductive paste layer 3 after firing is 0.2 Ω/□ or less.

In order to control the calcination temperature of the conductive paste to a low temperature in the range of 150 to 250 ° C, it is preferred that the average particle diameter of the metal fine particles is in the range of 1 to 120 nm, more preferably in the range of 1 to 100 nm.

In the conductive paste layer 3 of the electromagnetic wave shielding materials 10 and 11 for FPC of the present invention, by containing the above-described metal fine particles, not only the thin film formation but also thermal adhesion between the fine particles can be achieved, so that the electrical conductivity can be simultaneously improved. In the conductive paste used in the present invention, for example, metal fine particles having an average particle diameter of 1 to 120 nm are uniformly dispersed in a solvent. Therefore, it is preferable to cover the surface of the metal fine particles with an organic molecular layer to improve the dispersion property in a solvent. Finally, in the heating and calcining step of the conductive paste, the surfaces of the metal fine particles are brought into contact with each other, whereby the conductivity of the conductive paste layer 3 can be obtained.

In the heating calcination of the conductive paste, for example, heating at a temperature of 150 to 250 ° C causes the organic molecular layer covering the surface of the metal fine particles to be detached and evaporated to be removed. Therefore, it is preferred to set the calcination temperature to organic molecules. The boiling point range of the layer.

As described above, although the polyimide film itself as the substrate 1 has heat resistance to heat treatment at a temperature of 200 to 250 ° C, the heat resistance of the support film 6 is inferior, and thus the support film 6 is used. Preferably, the calcination temperature is set to a lower temperature.

The baking temperature of the conductive paste is preferably 150 to 180 ° C, whereby appearance defects due to thermal deterioration of the support film 6 can be suppressed.

In the conductive paste, as the binder resin composition to be used in combination with the conductive filler, a thermoplastic resin such as a polyester resin, a (meth)acrylic resin, a polyethylene resin, a polystyrene resin or a polyamide resin is preferably used. . Further, a thermosetting resin such as an epoxy resin, an amine resin, a polyimide resin, or a (meth)acrylic resin may be used. For the conductive paste, a conductive metal microparticle, a carbon nanotube, a carbon nanofiber or the like is mixed in these adhesive compositions. The electric filler is then added with an organic solvent such as an alcohol or an ether as needed to adjust the viscosity.

The viscosity adjustment can be carried out according to the amount of addition (mixing ratio) of the organic solvent. The thickness after calcining the conductive paste 3 is preferably about 0.1 to 2 μm. More preferably, it is about 0.3 to 1 μm. If the thickness after calcining the conductive paste 3 is less than 0.1 μm, it is difficult to obtain high electromagnetic wave masking performance. On the other hand, if the thickness after the baking of the conductive paste layer 3 is more than 2 μm, it is difficult to control the total thickness of the electromagnetic wave shielding material 11 for FPC after removing the support film 6 and the release film 7 to 25 μm or less.

(conductive adhesive layer)

The conductive adhesive layer laminated on the conductive paste layer 3 of the electromagnetic wave shielding materials 10 and 11 for FPC of the present invention is not particularly limited, and an acrylic adhesive, a polyurethane adhesive, or an epoxy adhesive can be used. A thermosetting adhesive imparting flame retardancy, such as a solvent, a rubber-based adhesive, an anthrone-based adhesive, and an epoxy having a number average molecular weight of 1,500 or less which penetrates into the tackifying coating and/or the conductive paste layer and can be cured. In the resin component of the resin, one or more conductive materials selected from the group consisting of conductive fine particles, quaternary ammonium salt, and the like, and a conductive material such as a conductive polymer, and conductive conductive adhesive are mixed. Floor.

If the conductive adhesive layer is not an adhesive layer having pressure-sensitive adhesiveness at normal temperature but an adhesive layer which is heated and pressurized, the adhesive force for repeated bending is not easily lowered, which is preferable.

The flame-retardant resin (flame-retardant thermosetting adhesive) to be blended in the conductive adhesive layer 4 is not particularly limited, and a conventionally known flame-retardant resin can be applied. It is preferred to use a flame retardant resin having a high acid value so as to have a slight The epoxy resin having a number average molecular weight of 1,500 or less of the component in which the layer of the void penetrates and solidifies is likely to be crosslinked. The acid value of the flame retardant resin is preferably 5 or more, more preferably 10 or more. When the acid value of the flame-retardant resin is less than the above lower limit value, for example, less than 5, sufficient heat resistance may not be obtained.

a component which is infiltrated into a layer having a fine void and is cured in the conductive adhesive layer 4 (permeating the resin composition inside the adhesion-promoting coating layer 2 and/or the conductive paste layer 3 composed of the above-mentioned conductive paste), An epoxy resin having a number average molecular weight of 1,500 or less is preferred. Examples of such an epoxy resin include a bisphenol A epoxy resin, a bisphenol F epoxy resin, and a novolac epoxy resin. Among them, a bisphenol A type epoxy resin is preferred. In the bisphenol A type epoxy resin, commercially available products of the liquid bisphenol A type epoxy resin include, for example, jER828EL, jER834 (Mitsubishi Chemical Co., Ltd.), EPIECLON 840, and EPICLON 850 (DIC). )), YD-127, YD-128 (Nippon Steel & Sumitomo Chemical Co., Ltd.), etc., but there are no special restrictions. In addition, as a commercial item of the solid bisphenol A type resin, for example, jER1001, jER1002 (Mitsubishi Chemical Co., Ltd.), YDF-2001 (Nippon Steel & Metal Chemical Co., Ltd.), EPICLON 1050 (DIC) ))), but there are no special restrictions.

In addition, the blending ratio of the flame-retardant resin in the conductive adhesive layer resin depends on the concentration of the flame-retardant component. For example, in the flame-retardant resin into which the phosphorus-based flame retardant is introduced, it is preferable that the phosphorus concentration accounts for the resin. The total amount of the components is 1.0% by weight or more. If the concentration of phosphorus in the total amount of the resin component is less than 1.0% by weight, sufficient flame retardancy may not be obtained. Further, in the resin of the conductive adhesive layer, it is preferable that the concentration of the epoxy resin having a number average molecular weight of 1,500 or less accounts for the total amount of the resin component contained in the conductive adhesive layer (when the curing agent is combined with the resin and polymerized) Further, the total amount of the resin component also includes 15% by weight or more of the curing amount, and particularly preferably 20% by weight or more. If the concentration of the epoxy resin having a number average molecular weight of 1,500 or less in the resin of the conductive adhesive layer is less than the above lower limit value, for example, less than 15% by weight, it penetrates into a layer having minute voids such as a tackifying coating layer or a conductive paste layer. The amount is not sufficient, so it is difficult to obtain an effect of increasing the adhesion. In addition, the upper limit of the concentration of the epoxy resin having a number average molecular weight of 1,500 or less in the resin of the conductive adhesive layer is not particularly limited, and may be, for example, about 30% by weight, about 40% by weight, or about 50% by weight, etc., but In order to secure the flame retardancy, it is preferred to adjust the amount of the component to be infiltrated and cured to an appropriate amount, or to use a flame-retardant, infiltrated and cured component such as a flame-retardant epoxy resin.

A component (for example, a curable component such as an epoxy resin having a number average molecular weight of 1,500 or less) which is adhered to the conductive adhesive layer 4 and penetrated into a layer having minute voids, and the conductive adhesive layer 4 is used. After being laminated on the adhesion-promoting coating layer 2 or the conductive paste layer 3, it penetrates into the inside of these layers (at least into the interior of the conductive paste layer 3, preferably further penetrates into the interior of the adhesion-promoting coating layer 2). This is because the conductive paste layer 3 has minute voids as compared with the dense metal deposited layer. It is preferable that the component which permeates and solidifies to the layer having the minute voids of the conductive adhesive layer 4 coated on the conductive paste layer 3 penetrates into the inside of the adhesion-promoting coating layer 2 and the conductive paste layer 3, and then solidifies it. . The component contained in the conductive adhesive layer 4 that penetrates and solidifies into the layer having the minute voids may be semi-cured or cured before being bonded to the adherend such as FPC, or may be subjected to lamination. Cured. For example, it may be cured in a heating step such as hot pressing. The molecular weight of the epoxy resin which is infiltrated into the layer having fine voids and is cured may be a high molecular weight of 10,000 or more.

The conductive fine particles to be incorporated in the conductive adhesive layer 4 are not particularly limited, and conventionally known conductive fine particles can be used. For example, carbon black or metal fine particles made of a metal such as silver, nickel, copper or aluminum, and composite metal fine particles coated with other metals on the surface of these metal fine particles may be mentioned, and one or both of the above may be appropriately selected and used. the above.

Further, in the above-mentioned conductive adhesive, in order to obtain excellent conductivity, a large amount of conductive material is contained so that the conductive material particles are in contact with each other, and the particles and the conductive paste layer and the adherend are adhered. Good contact between the FPCs will result in a decrease in adhesion. On the other hand, if the content of the conductive material is reduced in order to improve the adhesion, there is a problem that the contact between the conductive material and the conductive paste layer and the FPC as the adherend becomes insufficient, and the conductivity is lowered. Therefore, the amount of the conductive fine particles is usually 0.5 to 150 parts by weight, more preferably 25 to 75 parts by weight, per 100 parts by weight of the adhesive (solid content).

In addition, as the conductive adhesive constituting the conductive adhesive layer 4 of the present invention, an anisotropic conductive adhesive containing conductive fine particles is preferable, and a known conductive adhesive can be used. For example, it is not particularly limited as in the above-mentioned conductive adhesive, and it is possible to use a resist which is imparted to an acrylic adhesive, a polyurethane adhesive, an epoxy adhesive, a rubber adhesive, an anthrone adhesive, or the like. a flammable thermosetting adhesive, and a resin component composed of an epoxy resin having a number average molecular weight of 1,500 or less which penetrates into the tackifying coating layer or the conductive paste layer and is cured, and is selected from the group consisting of conductive fine particles or a 4-grade ammonium salt. A conductive adhesive having one or more conductive materials in a conductive material group such as a compound or a conductive polymer to have conductivity.

In addition, as the conductive fine particles used for the anisotropic conductive adhesive, for example, metal fine particles of gold, silver, zinc, tin, or solder, or a combination of two or more kinds thereof may be used. Further, as the conductive fine particles, resin particles plated with metal can be used. The shape of the conductive fine particles is preferably a shape in which the fine particles are connected in a linear shape or a needle shape. In such a shape, when the FPC is subjected to heat and pressure treatment by the crimping member, the conductive fine particles can enter the conductor wiring of the FPC with a lower pressure applied.

The connection resistance value between the anisotropic conductive adhesive and the FPC is preferably 5 Ω/cm or less, more preferably 1 Ω/cm or less.

The adhesive force of the conductive adhesive is not particularly limited, but the measurement method is based on the test method described in Method A of 8.7.1 of JIS C 6471. The adhesive force on the surface of the adherend is preferably in the range of 5 to 30 N/cm under the conditions of peeling at a peeling angle of 90° and a peeling speed of 50 mm/min. If the adhesion is less than 5 N/cm, for example, the electromagnetic wave shielding material attached to the FPC may be peeled or lifted.

The heating and pressure bonding conditions of the FPC are not particularly limited. For example, it is preferably subjected to a hot press treatment for 60 minutes under the conditions of a temperature of 160 ° C and a pressing force of 4.5 MPa.

(release film)

Examples of the substrate of the release film 7 include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polypropylene or poly A polyolefin film such as ethylene. After the release agent such as an amino alkyd resin or a ruthenium resin is applied onto the base film, the release treatment is performed by heating and drying. Since the electromagnetic wave shielding materials 10 and 11 for FPC of the present invention are attached to the FPC, It is preferred that no ruthenium resin is used in the release agent. The reason for this is that if a ruthenium resin is used as a release agent, there is a problem in that a part of the enamel resin is moved to the surface of the conductive adhesive layer 4 which is in contact with the surface of the release film 7, and electromagnetic waves are further used by FPC. The inside of the masking material 11 moves from the conductive adhesive layer 4 to the substrate 1. Further, the resin which has moved to the surface of the conductive adhesive layer 4 may weaken the adhesion of the conductive adhesive layer 4. Since the thickness of the release film 7 used in the present invention is excluded from the total thickness of the electromagnetic wave shielding material 11 for FPC when it is used for bonding FPC, it is not particularly limited, and is usually 12 to 150 μm.

The electromagnetic wave shielding materials 10 and 11 for FPC of the present invention are excellent in the followability to the level difference when they are bonded to the uneven surface, and can be used in an FPC which is repeatedly subjected to the bending operation, and is suitably shielded from electromagnetic waves for FPC excellent in bending performance. material. Further, the electromagnetic wave shielding material for FPC of the present invention can be used as a member for electromagnetic wave shielding on a mobile phone or an electronic device.

[Examples]

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to the following examples.

(Example 1)

A polyethylene terephthalate (PET) film having a thickness of 50 μm which was subjected to a release treatment on one side was used as the support film 6. On the release-treated surface of the support film 6, the solvent-soluble polyimide coating liquid was cast-coated so as to have a thickness of 4 μm after drying, and dried to form a thin film resin film laminated with a dielectric. Substrate 1. On the substrate 1 to be formed, the coating liquid for forming the adhesion-promoting coating layer 2 is applied so as to have a thickness of 0.3 μm after drying, thereby laminating the adhesion-promoting coating layer 2, wherein the coating layer 2 is used. The coating liquid on which the adhesion-promoting coating layer 2 is formed is a mixture of carbon black as a black pigment of a light absorbing material and a polyester resin composition having a heat-resistant temperature of 260 to 280 °C. A conductive paste prepared by mixing silver particles having a primary average particle diameter of about 50 nm as a conductive filler on the adhesion-promoting coating layer 2, and applying the coating after drying to a thickness of 0.3 μm, at 150 ° C The drying and calcination treatment were carried out under temperature conditions to form a conductive paste layer 3. The volume resistivity of the conductive paste layer 3 after drying is measured to be 1.5 × 10 ^-5 Ω. Below cm.

Separately, the following substance was added to a 40% solution (A-1) of 250 parts by weight of the flame-retardant polyurethane resin, and then diluted with methyl ethyl ketone and toluene, stirred and kneaded to obtain a conductive adhesive. Solution solution. The additive is: 15 parts by weight of a 70% solution (B-1) of a curing agent; 60 parts by weight of an epoxy resin (C-1) having a number average molecular weight of 1,500 or less; and 19.5 parts by weight of a curing agent (D-1) ); solid in 40% solution (A-1) of flame retardant polyurethane resin, 70% solution (B-1) of curing agent, epoxy resin (C-1) and curing agent (D-1) The total amount of components (that is, the total amount of the resin component) is 10% by weight of molten cerium oxide having an average particle diameter of 16 nm; and 50% by weight of the total amount of solid components including molten cerium oxide. Copper (SILVER-COATED COPPER). The obtained conductive adhesive solution was applied onto the conductive paste layer 3 so that the thickness after drying measured by a dial gauge was 12 μm, and then heat-dried at a temperature of 130 ° C for 3 minutes to make it half. After curing, the electromagnetic wave shielding material for FPC of Example 1 was obtained.

(Examples 2 to 4)

In addition to changing the number average molecular weight of 1500 or less, as shown in Table 1 An electromagnetic wave shielding material for FPC was obtained in the same manner as in Example 1 except for the lipid.

(Examples 5 to 7)

An electromagnetic shielding material for FPC was obtained in the same manner as in Example 1 except that the amount of the epoxy resin having a number average molecular weight of 1,500 or less was changed as shown in Table 1.

(Comparative examples 1 to 2)

An electromagnetic wave shielding material for FPC was obtained by the same method as in Example 1 except that an epoxy resin having a number average molecular weight of 1,500 or more was used instead of the epoxy resin having a number average molecular weight of 1,500 or less and blended as shown in Table 2. .

(Comparative Example 3)

An electromagnetic wave shielding material for FPC was obtained in the same manner as in Example 1 except that the (C-1) epoxy resin was not blended.

(Comparative Example 4)

An electromagnetic wave shielding material for FPC was obtained in the same manner as in Example 1 except that the amount of the epoxy resin having a number average molecular weight of 1,500 or less was changed to that shown in Table 2.

(measurement method of adhesion)

The conductive adhesive layer 4 side of the FPC electromagnetic wave shielding material was superposed on the polyimine film (Toray DuPont Co., Ltd., product number: 200H) having a thickness of 50 μm, and the temperature was 160 ° C at a temperature of 160 ° C. The hot press treatment was carried out for 60 minutes under the conditions of a pressure of 4.5 MPa, and then the support film 6 was peeled off and cut into 50 mm × 120 mm. A commercially available adhesive sheet and a polyimide film having a thickness of 12.5 μm were laminated in this order so as to face the substrate 1 of the cut film (Toray Dupont) Division, product number: 50H), and subjected to hot pressing treatment at a temperature of 160 ° C and a pressure of 4.5 MPa for 60 minutes, thereby obtaining a test piece. Then, according to Method A (90° direction tearing) of 8.1.1 of JIS-C-6471 (Copper-clad laminate test method for flexible printed wiring boards), the polyimine film side having a thickness of 50 μm is fixed at Supporting the mold, and peeling the adhesion-promoting coating 2, the substrate 1, the adhesive sheet, and the polyimide film having a thickness of 12.5 μm as a whole, thereby measuring the adhesion between the adhesion-promoting coating 2 and the conductive paste layer 3. Adhesion.

(Evaluation method of flame retardancy)

The conductive adhesive layer 4 side of the electromagnetic wave shielding material for FPC was placed so as to face the polyimide film (Dolly DuPont Co., Ltd., product number: 50H) having a thickness of 12.5 μm, and the temperature was 160 ° C. The hot press treatment was carried out for 60 minutes under the conditions of a pressure of 4.5 MPa, and then the support film 6 was peeled off and cut into 50 mm × 200 mm to obtain a test piece.

According to the film material vertical burning test (ASTM D4804), the combustion behavior of the obtained test piece was measured to determine the flame retardancy.

(test results)

The adhesion test of the conductive paste layers was carried out for Examples 1 to 7 and Comparative Examples 1 to 4 by the above test methods, and the obtained test results are shown in Tables 1 and 2. The abbreviations in Tables 1 to 2 indicate the following.

‧ 40% solution of flame retardant polyurethane resin (A-1): 40% solution of flame retardant polyurethane resin with phosphorus content of 2.4% by weight, number average molecular weight of 15000, and acid value of 32 KOHmg/g

‧ Curing agent 70% solution (B-1): Produced by Toyobo Co., Ltd., trade name "HY-30" (curing agent for flame retardant polyurethane resin)

‧Epoxy resin (C-1): Produced by Mitsubishi Chemical Corporation, trade name "jER828EL" (epoxy equivalent weight 189g / equivalent, number average molecular weight is about 370)

‧Epoxy Resin (C-2): Produced by Mitsubishi Chemical Corporation, trade name "jER834" (epoxy equivalent weight 250g/eq, number average molecular weight approximately 470)

‧Epoxy resin (C-3): Produced by Mitsubishi Chemical Corporation, trade name "jER1001" (epoxy equivalent weight 475g / equivalent, number average molecular weight is about 900)

‧Epoxy resin (C-4): Produced by Mitsubishi Chemical Corporation, trade name "jER1002" (epoxy equivalent weight 642g / equivalent, number average molecular weight is about 1200)

‧Epoxy Resin (C-5): Produced by Mitsubishi Chemical Corporation, trade name "jER1004" (epoxy equivalent weight: 950g / equivalent, number average molecular weight is about 1650)

‧Epoxy resin (C-6): Produced by Mitsubishi Chemical Corporation, trade name "jER1007" (epoxy equivalent weight is 1975g / equivalent, number average molecular weight is about 2900)

‧ Curing agent (D-1): Produced by Japan Wakayama Seiki Co., Ltd. under the trade name "Seikakyua S" (curing agent for epoxy resin with amine equivalent of 62.1: 4,4'-diamino 2 Phenylhydrazine

Further, in Tables 1 and 2, as described in Example 1, the values indicated in the columns (A-1), (B-1), (C-1) to (C-6), and (D-1) are It is a part by weight of each component. (-) means that the component is not contained.

According to the test results of the adhesion shown in Tables 1 and 2, it can be seen that the fit The number average molecular weight of the epoxy resin in the conductive adhesive layer has a great influence on the adhesion of the adhesion-promoting coating of the electromagnetic wave shielding material for FPC and the conductive paste layer.

In Examples 1 to 7, an epoxy resin having a number average molecular weight of 1,500 or less was blended. In this case, the effect of enhancing the adhesion was remarkable as compared with Comparative Example 3 in which the epoxy resin was not blended.

In Comparative Example 1 and Comparative Example 2, since the epoxy resin having a large number average molecular weight and having difficulty in penetrating into the tackifying coating layer and/or the inside of the conductive paste layer was blended, the effect of enhancing the adhesion was low.

Further, when the same epoxy resin (C-1) was used for comparison, in Examples 1, 5, 6, and 7, a sufficient adhesion-enhancing effect was obtained, but the amount of the epoxy resin was small. In Comparative Example 4, the amount of the epoxy resin penetrating into the tackifying coating layer and/or the inside of the conductive paste layer was small, and the effect of enhancing the adhesion was insufficient.

From these test results, it is known that an electromagnetic wave shielding material for FPC having a good adhesion between the layers is required to be on a substrate of a film resin film having a dielectric (for example, a polyfluorene formed by using a solvent-soluble polyimine). A substrate made of an imide film having a thickness of 1 to 9 μm is formed by sequentially laminating a tackifying coating layer, a conductive paste layer, and a conductive adhesive layer, and a part of the conductive adhesive layer must penetrate into the conductive layer. The interior of the paste layer (more preferably, it penetrates into the interior of the tackifying coating) and is cured. Therefore, it is preferred that the conductive adhesive layer contains an epoxy resin having a number average molecular weight of 1,500 or less.

In the electromagnetic wave shielding material for FPC which is commercially available in Japan, a metal thin film subjected to vapor deposition treatment is used as a conductive layer. However, since the metal thin film after vapor deposition is a dense film, it is difficult to obtain conductivity. The adhesive component of the adhesive layer penetrates, so that it is impossible to infiltrate the inside of the metal film by the adhesive component. The effect of enhancing the adhesion between layers due to curing.

On the other hand, in the electromagnetic wave shielding material for FPC of the present invention, a thin film resin film of a dielectric (for example, a thickness of 1 to 9 μm obtained by casting a solvent-soluble polyimide pigment coating solution by thin coating) The ruthenium imine film is used as a substrate, and a tackifier coating layer, a conductive paste layer, and a conductive adhesive layer are sequentially laminated on the substrate, and in order to improve adhesion to the adhesion-promoting coating layer and the conductive paste layer, An epoxy resin having a number average molecular weight of 1,500 or less is blended in the conductive adhesive layer. Therefore, according to the present invention, it is possible to obtain an excellent adhesion between the layers, and even if the bending operation is repeated, the interlayer peeling does not occur at the partial adhesion interface between the substrate and the conductive paste layer, and the electromagnetic wave mask performance is suppressed from decreasing over time. FPC uses electromagnetic wave shielding materials.

[Industry Utilization]

The electromagnetic wave shielding material for FPC of the present invention can be used as an electromagnetic wave shielding member in various electronic devices such as mobile phones, notebook computers, portable terminals, and tablet terminals.

1‧‧‧Substrate

2‧‧‧Adhesive coating

3‧‧‧ Conductive paste layer

4‧‧‧ Conductive adhesive layer

6‧‧‧Support film

10‧‧‧Electromagnetic wave shielding material for flexible printed circuit boards

Claims (10)

An electromagnetic wave shielding material for FPC in which a base material of a film resin film having a coated dielectric, a tackifying coating layer, a conductive paste layer, and a conductive adhesive layer are sequentially laminated on one surface of a support film, and The conductive adhesive layer contains a flame-retardant polyurethane resin and an epoxy resin having a number average molecular weight of 1,500 or less, and the concentration of the epoxy resin having a number average molecular weight of 1,500 or less in the conductive adhesive layer accounts for the conductive adhesive layer. The total amount of the resin component contained is 15% by weight or more and 50% by weight or less. The test method described in Method A of 8.1.1 of JIS C 6471 is used as a measuring method, and the peeling angle is 90° peeling off and the peeling speed is 50 mm/ The adhesion of the conductive adhesive to the surface of the polyimide film of the adherend was measured in the range of 5 to 30 N/cm. The electromagnetic wave shielding material for FPC according to the first aspect of the invention, wherein at least a part of the epoxy resin penetrates into the interior of the adhesion-promoting coating layer and/or the conductive paste layer and is semi-cured. The electromagnetic wave shielding material for FPC according to claim 1 or 2, wherein the substrate has a polyimide film formed using a solvent-soluble polyimine and has a thickness of 1 to 9 μm. An electromagnetic wave shielding material for FPC according to claim 1 or 2, wherein the adhesion-promoting coating layer is obtained by crosslinking a resin composition containing a polyester resin having an epoxy group, the adhesion-promoting coating layer The thickness is 0.05~1μm. For example, the electromagnetic wave shielding material for FPC of the first or second application of the patent scope is The adhesion-promoting coating further contains one or more black pigments selected from the group consisting of carbon black, graphite, nigrosine, cyanine black, titanium black, iron oxide black, chromium oxide, and manganese oxide, or a The above light absorbing material composed of a colored pigment. The electromagnetic wave shielding material for FPC according to claim 1 or 2, wherein the conductive paste layer is a conductive paste containing a silver nanoparticle having an average particle diameter of 1 to 120 nm and a binder resin composition at 150 It is calcined at a temperature of ~250 ° C and has a thickness of 0.1 to 2 μm. For example, the electromagnetic wave shielding material for FPC of claim 1 or 2, wherein the conductive paste layer has a volume resistivity of 1.5×10 ^-5 Ω. Below cm. The electromagnetic wave shielding material for FPC according to the first or second aspect of the patent application, wherein the release adhesive film is bonded to the conductive adhesive layer. A mobile phone using the electromagnetic wave shielding material for FPC according to any one of claims 1 to 8 as a member for electromagnetic wave shielding. An electronic device using the electromagnetic wave shielding material for FPC according to any one of claims 1 to 8 as a member for electromagnetic wave shielding.