KR20200049085A - Electromagnetic interference shielding film and flexible printed circuit board the same - Google Patents

Abstract

The present invention relates to an electromagnetic wave shielding film that can be used in electrical, electronic, and communication devices, and an electromagnetic wave shielding flexible printed circuit board including the same, wherein the electromagnetic wave shielding film includes: a copper foil layer; an insulating layer disposed on a first surface of the copper foil layer; and a conductive adhesive layer disposed on a second surface of the copper foil layer, wherein the copper foil layer has a ratio (Ra_1/Ra_2) of the average surface roughness (Ra_1) of the first surface to the average surface roughness (Ra_2) of the second surface is 3 to 7, the electromagnetic wave shielding rate at 1 GHz frequency according to an ASTM 4935-1 test method is 70 dB or more.

Description

ELECTROMAGNETIC INTERFERENCE SHIELDING FILM AND FLEXIBLE PRINTED CIRCUIT BOARD THE SAME

The present invention relates to an electromagnetic wave shielding film that can be used in electrical, electronic and communication equipment, and an electromagnetic wave shielding flexible printed circuit board including the same.

There is an increasing demand for miniaturization, flattening and high functionality of electronic devices. In order to meet these demands, complex electromagnetic noise is generated by implementing components in different frequency domains in the same electronic device, and it is becoming difficult to prepare a countermeasure against the complex electromagnetic noise. On the other hand, data transmission cables are also increasing in demand for thinning and emitting less electromagnetic noise. In the case of transmitting large amounts of data, errors in data due to interference of data due to electromagnetic noise and data are often lost.

In order to satisfy electromagnetic compatibility, it is necessary to reduce electromagnetic noise generated from various electric, electronic, and communication devices as much as possible, and to reduce electromagnetic sensitivity to external electromagnetic environments to enhance the electromagnetic resistance of the device itself. The most important characteristics required for electromagnetic compatibility products inserted into various electrical, electronic, and communication devices are that electromagnetic shielding and absorption must be large and that electromagnetic compatibility products must be small and thin in accordance with the trend of lighter and shorter devices.

As a countermeasure for solving the above-mentioned electromagnetic noise problem, an electromagnetic wave shielding film in which a conductive adhesive layer is laminated on an insulating layer is frequently used. In the conventional electromagnetic wave shielding film, a conductive adhesive layer contains a large amount of conductive filler in order to improve electromagnetic wave shielding properties. However, the synergistic effect of electromagnetic shielding compared to the content of the conductive filler used was not satisfactory. In particular, the conventional electromagnetic wave shielding film has a low electromagnetic wave shielding rate in a frequency band of 1 GHz or more, resulting in electromagnetic noise, and thus has a limitation in application to a mobile communication market requiring high-speed transmission technology.

An object of the present invention is to provide an electromagnetic wave shielding film having an excellent electromagnetic wave shielding rate in a high frequency band.

In addition, another object of the present invention is to provide a printed circuit board having excellent transmission quality in a high-speed transmission mode including the above-mentioned electromagnetic wave shielding film.

The present invention is a copper foil layer; An insulating layer disposed on the first surface of the copper foil layer; And a conductive adhesive layer disposed on the second surface of the copper foil layer, wherein the copper foil layer is the ratio of the average surface roughness (Ra ₁ ) of the first surface to the average surface roughness (Ra ₂ ) of the second surface (Ra) ₁ / Ra ₂ ) is 3 to 7, and provides an electromagnetic shielding film having an electromagnetic shielding rate of 70 dB or more at a frequency of 1 GHz according to the ASTM 4935-1 test method.

The electromagnetic wave shielding film may further include a protective film disposed on the insulating layer.

The electromagnetic shielding film may further include a release film disposed on the lower surface of the conductive adhesive layer.

In addition, the present invention is a substrate body including a circuit pattern of one or more layers; And it provides an electromagnetic wave shield type flexible printed circuit board comprising the above-described electromagnetic wave shielding film disposed on one or both sides of the substrate body.

The present invention is to arrange a copper foil layer between the insulating layer and the conductive adhesive layer, by adjusting the surface roughness ratio of both surfaces of the copper foil layer to a specific range, excellent in the frequency range of about 1 to 5 GHz as well as in the high frequency region of 5 GHz or more Not only can it have electromagnetic wave shielding properties, it has low step resistance even under constant temperature and humidity conditions, has excellent interlayer adhesion, flexibility, thermal stability, chemical resistance and abrasion resistance, and has a low resistance change rate. Therefore, the electromagnetic wave shielding film of the present invention can be applied to a flexible printed circuit board for high-speed transmission to minimize transmission quality degradation.

1 is a cross-sectional view schematically showing an electromagnetic wave shielding film according to a first embodiment of the present invention.
2 is a cross-sectional view schematically showing an electromagnetic wave shielding film according to a second embodiment of the present invention.
3 is a cross-sectional view schematically showing an electromagnetic wave shielding film according to a third embodiment of the present invention.
4 is a process cross-sectional view schematically showing a process of manufacturing an electromagnetic wave shielding film according to a first embodiment of the present invention.
5 to 6 are process cross-sectional views schematically showing a process for manufacturing an electromagnetic wave shielding film according to a second embodiment of the present invention.
7 to 8 are process cross-sectional views schematically showing a process for manufacturing an electromagnetic wave shielding film according to a third embodiment of the present invention.
Figure 9 shows a sample for measuring the step resistance to the electromagnetic wave shielding film of Examples 1 to 8 and Comparative Examples 1 to 3, (a) the circuit of the flexible circuit board coupon having a reinforcing plate for the electromagnetic wave shielding film open It is a sectional view showing a process of arranging in a region, and (b) is a plan view showing a flexible circuit board coupon to which an electromagnetic wave shielding film is attached.
10 shows a shape of a coupon manufactured to evaluate the electromagnetic wave shielding rate of the electromagnetic wave shielding film.

Hereinafter, the present invention will be described.

An electromagnetic shielding film is a film that shields electromagnetic noise between adjacent circuits to protect electronic components or electronic / communication devices such as flexible printed circuit boards from electromagnetic interference (EMI), for example, the best of flexible printed circuit boards. It is arranged on the outer shell (eg, over the coverlay). These electromagnetic wave shielding films require various physical properties, and require excellent electromagnetic wave shielding properties, flexibility, flame retardancy, thermal stability, chemical resistance, abrasion resistance and low resistance change. However, as the 5G mobile communication market has recently expanded, high-speed transmission technology is required, and accordingly, the use of high-speed transmission FPCBs used in USB cables, EDP cables, and the like is increasing. Therefore, the electromagnetic wave shielding film applied to the FPCB for high-speed transmission requires excellent electromagnetic wave shielding property in a high frequency region having a frequency of 1 GHz or more.

Thus, in the present invention, by arranging a copper foil layer between the insulating layer and the conductive adhesive layer, electromagnetic shielding in the frequency range of 1 GHz or more, for example, in the frequency range of 1 GHz to 5 GHz, compared to the conventional electromagnetic shielding film of the insulating layer and the conductive adhesive layer. The effect could be increased.

However, the interlayer adhesion was reduced due to heterogeneity between the insulating layer, the copper foil layer, and the conductive adhesive layer. In particular, when attaching the electromagnetic wave shielding film to the stepped portion between the coverlay and the ground pattern through a thermocompression process, interlayer peeling occurs at the interface between the copper foil layer and the insulating layer, as well as deteriorating the curvature, as well as the step resistance of the electromagnetic wave shielding film With this increase, the electromagnetic wave shielding property of the electromagnetic wave shielding film also decreased.

Therefore, in the present invention, the copper foil layer is disposed between the insulating layer and the conductive adhesive layer, but the surface of the copper foil layer contacting the conductive adhesive layer with the average surface roughness of the surface of the copper foil layer (hereinafter referred to as the 'first surface') contacting the insulating layer. It is adjusted higher than the average surface roughness of (hereinafter referred to as 'second surface'). At this time, the first surface of the copper foil increases the adhesive strength with the insulating layer, and the second surface is combined with the conductive adhesive layer with high adhesive strength, and the skin effect may be minimized on the second surface. As a result, the present invention not only has excellent interlayer adhesion and flexibility, but also can have excellent electromagnetic shielding properties in a frequency range of 1 GHz or more, such as 1 to 5 GHz, as well as in a high frequency region of more than 5 GHz. In addition, since the step resistance of the present invention is low even under constant temperature and humidity conditions, even when attached to the step portion of the FPCB in a constant temperature and humidity environment, excellent electromagnetic wave shielding properties can be exhibited. In addition, the electromagnetic wave shielding film of the present invention has excellent thermal stability, chemical resistance and abrasion resistance, and has a low resistance change rate.

<Electromagnetic shielding film>

1 to 3 are cross-sectional views schematically showing electromagnetic shielding films according to first to third embodiments of the present invention, respectively.

The electromagnetic wave shielding films 100A, 100B, and 100C according to the present invention have a structure in which the conductive adhesive layer 130, the copper foil layer 110, and the insulating layer 120 are sequentially stacked, but are in contact with the conductive adhesive layer 130. The ratio of the average surface roughness of the first surface 110a of the copper foil layer in contact with the insulating layer 120 to the average surface roughness of the second surface 100b of the copper foil layer 110 is adjusted to a specific range. If necessary, a protective film 140 disposed on the insulating layer 120 and / or a release film 150 disposed on the conductive adhesive layer 130 may be further included (see FIGS. 2 and 3). ).

Hereinafter, an electromagnetic wave shielding film 100A according to a first embodiment of the present invention will be described with reference to FIG. 1.

As shown in FIG. 1, the electromagnetic wave shielding film 100A according to the first embodiment includes a copper foil layer 110, an insulating layer 120 and a conductive adhesive layer 130 laminated on both sides thereof.

1) Copper foil layer

In the electromagnetic wave shielding film 100A according to the present invention, the copper foil layer 110 is disposed between the insulating layer 120 and the conductive adhesive layer 130 to exhibit an electromagnetic wave shielding effect.

At this time, the copper foil layer 110 has a first surface 110a, which is a surface in contact with the insulating layer 120, and a second surface 100b, which is a surface in contact with the conductive adhesive layer 130. However, as described above, in the present invention, the ratio Ra of the average surface roughness Ra ₁ of the first surface 110a of the copper foil layer to the average surface roughness Ra ₂ of the second surface 100b of the copper foil layer Ra ₁ / Ra ₂ ) is in the range of 3 to 7. If the average surface roughness ratio (Ra ₁ / Ra ₂ ) between both surfaces is less than 3, interfacial adhesion may be reduced due to low roughness. On the other hand, when the average surface roughness ratio (Ra ₁ / Ra ₂ ) between both surfaces exceeds 7, a skin effect flowing through the surface may be generated, and a shielding effect of electromagnetic interference may be reduced. Therefore, the copper foil layer 110 of the present invention has a first surface having a peel strength of about 1 to 3 kgf / cm for an insulating layer according to the IPC-TM-650 standard, and a peel strength of about 0.65 to 2 for a conductive adhesive layer. It has a second surface of kgf / cm, specifically about 1 to 2 kgf / cm.

The copper foil layer 110 of the present invention may be used without particular limitation as long as it is a copper foil formed through a copper foil forming method generally known in the art, such as a rolling method and an electrolytic method. At this time, the copper foil may be rust-prevented to prevent oxidative corrosion of the surface. However, when manufacturing the copper foil, the average roughness ratio between both surfaces is adjusted to have the above-described range.

The thickness of the copper foil layer 110 may be appropriately adjusted in consideration of the electromagnetic wave shielding power of the film, flexibility, adhesion, and interlayer adhesion. At this time, not only the thickness of the copper foil layer, but also the thickness of the conductive adhesive layer should be considered. Accordingly, in the present invention, the ratio (t ₁ + t ₂ / T) of the total thickness (t ₁ + t ₂ ) of the copper foil layer and the conductive adhesive layer to the thickness (T) of the electromagnetic wave shielding film is adjusted to a range of 0.65 to 0.85. . At this time, the ratio (t ₁ / t ₂ ) of the thickness t ₁ of the copper foil layer to the thickness t ₂ of the conductive adhesive layer is preferably 0.1 to 0.4.

The copper foil layer 110 may be a single layer or a plurality of layers of two or more layers. Here, when the copper foil layer 110 is a plurality of layers, the copper foil layer 110 and the conductive adhesive layer 120 are alternately arranged, and the lowermost portion of the film may have a structure that is a conductive adhesive layer. At this time, it is preferable that the total thickness of all copper foil layers and the total thickness of all conductive adhesive layers satisfy the above-described relationship.

2) Insulation layer

In the electromagnetic wave shielding film 100A according to the present invention, the insulating layer 120 is disposed on the first surface 110a of the copper foil layer 110, while imparting mechanical strength to the electromagnetic wave shielding film, bending properties of the film In addition, it plays a role in exerting thermal stability, chemical resistance, and scratch resistance.

The insulating layer 120 may be in the form of a coating layer or film, in a semi-cured (B-stage) state, or in a fully cured (C-stage) state, and preferably in a semi-cured (B-stage) state.

The insulating layer 120 is formed by curing or semi-curing a resin composition for forming an insulating layer containing a conventional thermosetting matrix resin and a curing agent, and includes a thermosetting resin.

Specifically, the insulating layer 120 may include one or more selected from the group consisting of polyimide resin, polyamide resin and polyamide-imide resin. In addition, the insulating layer may include at least one selected from the group consisting of polyimide-based resins, polyamide-based resins, and polyamide-imide resins, and other thermosetting resins commonly known in the art.

In one example, the insulating layer 120 may be a coating layer or film comprising a polyimide-based resin. Polyimide (PI) -based resin is a polymer material having an imide ring, and exhibits excellent flame retardancy, heat resistance, ductility, chemical resistance, abrasion resistance and weatherability based on the chemical stability of the imide ring, In addition, it exhibits low thermal expansion, low air permeability, and excellent electrical properties. Therefore, when the insulating layer 120 of the present invention contains a polyimide-based resin, due to the flame retardancy of the polyimide itself, it is possible to sufficiently secure the flame retardancy of the electromagnetic wave shielding film even if it does not contain a flame retardant. In addition, the surface hardness is increased compared to the epoxy or other resins, the scratch resistance is increased, the heat resistance is increased due to the high glass transition temperature, and a high flexural property can be secured compared to the epoxy resin.

The insulating layer 120 including the polyimide-based resin is a polyimide (PI) film or is formed by semi-curing or curing after applying a liquid composition comprising a polyimide and / or polyamic acid onto a base film in a liquid phase It may be a polyimide layer. In addition, the insulating layer 120 may be a coating layer or a film formed using a commercially available soluble polyimide (soluble PI).

Here, the polyimide film may have a self-supporting film to sheet shape. At this time, it may be a film formed using a commercially available polyimide (PI) film itself, or a commercially available soluble polyimide (soluble PI). Alternatively, the polyimide film may be prepared by condensing a diamine compound and a tetracarboxylic acid compound according to a method known in the art, and then applying and drying / curing such a reactant on a substrate. The polyimide film may be a surface treatment such as a matte treatment or corona treatment.

The resin composition forming the polyimide layer may include a polyimide-based first matrix resin, and may further include a second matrix resin such as a surfactant and an epoxy resin, if necessary. The polyimide-based first matrix resin is preferably a thermosetting polyimide, and non-limiting examples of polyimide-based matrix resins that can be used include polyimide, polyamide-imide, or composite resins thereof.

Here, the polyimide-based matrix resin may be prepared by imidizing a polyamic acid varnish obtained through an imidization reaction between a conventional aromatic dianhydride and an aromatic diamine (or aromatic diisocyanate) known in the art. For the purpose of imparting appropriate flexibility to the resin composition after curing, additives such as inorganic fillers and thermoplastic resins can be blended as necessary. Examples of such thermoplastic resins include phenoxy resins, polyvinyl acetal resins, polyethersulfones, and polysulfones. Any one of these thermoplastic resins may be used alone, or two or more of them may be used in combination.

In the present invention, when the insulating layer 120 is formed, when the above-described polyimide film, soluble polyimide or polyamic acid composition is used as the thermosetting matrix resin, conventional thermosetting resins known in the art, such as phosphorus (P) -containing thermosetting Resin and / or phosphorus (P) -free thermosetting resins can be used.

Non-limiting examples of thermosetting resins usable in the present invention include epoxy resins, polyurethane resins, phenol resins, vegetable oil-modified phenol resins, xylene resins, guanamine resins, diallylphthalate resins, vinyl ester resins, unsaturated polyester resins, It may be one or more selected from the group consisting of furan resin, polyimide resin, cyanate resin, maleimide resin and benzocyclobutene resin. Preferably, it is an epoxy resin, a phenol resin, or a vegetable oil modified phenol resin. Among these, epoxy resins are preferred because of their excellent reactivity and heat resistance. At this time, the thermosetting resin may be a phosphorus (P) -containing thermosetting resin, a phosphorus (P) -free thermosetting resin, or both.

The epoxy resin can be used without limitation a conventional epoxy resin known in the art, it is preferable that two or more epoxy groups are present in one molecule.

Non-limiting examples of the epoxy resin usable in the present invention, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, novolak type epoxy resin, alkylphenol novolak type epoxy resin, biphenyl type There are epoxy resins, aralkyl type epoxy resins, naphthol type epoxy resins, dicyclopentadiene type epoxy resins, etc., and these may be used alone or in combination of two or more.

More specific examples include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, naphthalene type epoxy resin, anthracene epoxy resin, biphenyl type epoxy resin, tetramethyl biphenyl type epoxy resin, and phenol novolac Type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, bisphenol S novolac type epoxy resin, biphenyl novolac type epoxy resin, naphthol novolac type epoxy resin, naphthol phenol coaxial novolac type epoxy resin , Naphthol corresol coaxial novolac type epoxy resin, aromatic hydrocarbon formaldehyde resin modified phenol resin type epoxy resin, triphenyl methane type epoxy resin, tetraphenylethane type epoxy resin, dicyclopentadiene phenol addition reaction epoxy resin, phenol aral Kill type epoxy resin, polyfunctional phenol resin, naphthol aralkyl type epoxy resin This, and these may be mixed alone or two or more kinds.

As the curing agent usable in the present invention, any curing agent commonly known in the art may be used without limitation, and may be appropriately selected and used according to the type of thermosetting resin such as an epoxy resin to be used. Non-limiting examples are phenol-based, anhydride-based, dicyanamide-based curing agents, and the like, and among them, phenol-based curing agents are preferable because they can further improve heat resistance and adhesion. Non-limiting examples of the phenol-based curing agent include phenol novolac, cresol novolac, bisphenol A novolac, naphthalene, etc. In this case, these may be used alone or in combination of two or more.

The insulating layer 120 according to the present invention may further include a conventional non-electrically conductive filler known in the art to effectively exhibit mechanical properties and low resistance changes of the final product.

The non-electrically conductive filler can be used by mixing organic fillers, inorganic fillers, or both, for example, natural silica, fused silica, amorphous silica, crystalline silica ) And the like; Boehmite, alumina, talc, spherical glass, calcium carbonate, magnesium carbonate, magnesia, clay, calcium silicate, titanium oxide, antimony, glass fiber, aluminum borate, barium titanate, strontium titanate, calcium titanate , Magnesium titanate, bismuth titanate, titanium oxide, barium zirconate, calcium zirconate, boron nitride, silicon nitride, talc, mica, and the like. These inorganic fillers may be used alone or in combination of two or more. Alternatively, carbon black, graphene, carbon nanotubes (CNT), or a mixture of one or more thereof may be used.

The content of the non-electrically conductive filler can be appropriately adjusted in consideration of the mechanical properties, low resistance change, and other properties of the above-described insulating layer, for example, about 3 to 30 parts by weight based on 100 parts by weight of the insulating layer, Preferably it may range from about 5 to 20 parts by weight.

In addition, the insulating layer 120 according to the present invention may further include a flame retardant. The flame retardant may be used without limitation as long as it is a flame retardant commonly known in the art, for example, organic phosphorus-based flame retardants, organic nitrogen-containing phosphorus compounds, nitrogen compounds, silicon-based flame retardants, metal hydroxides, and the like. Specific examples include triaryl / isopropyl phosphate, tris (3-hydroxypropyl) phosphine oxide, 1,3-phenylene-screw (jikisirenyl) phosphate, or 2,2-screw (p-hydroxy phenyl) Phenol condensates of propane-trichloro phosphine oxide polymerized products (polymerization degree 1 to 3), phosphate composite products, phosphorus-based compound such as aromatic condensed phosphorus ester, or ammonium polyphosphoric acid or ammonium polyphosphoric acid , Butyl acid phosphate, butoxyethyl acid phosphate, melamine phosphate, melamine, melamine / cyanurate, meram, merem, melon, and the like. These may be used alone or in combination of two or more.

The content of the flame retardant is not particularly limited, and can be appropriately adjusted within a conventional range known in the art.

In addition to the above-mentioned components, the resin composition for forming an insulating layer of the present invention is an organic solvent generally known in the art as necessary, or other thermosetting resin or thermoplastic resin not described above, as long as the inherent properties of the resin composition are not impaired. And various additives such as various polymers such as oligomers, solid rubber particles or ultraviolet absorbers, antioxidants, polymerization initiators, dyes, pigments, dispersants, thickeners, leveling agents, and the like.

The organic solvent usable in the present invention is not particularly limited, and for example, ketones such as acetone, methyl ethyl ketone, cyclohexanone, acetic acid, ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, carbitol acetate, and the like Esters, cellosolves, carbitols such as butyl carbitol, aromatic hydrocarbons such as toluene and xylene, dimethylformamide, dimethylacetamide, and N-methylpyrrolidone. These may be used alone or in combination of two or more.

Specific examples of the additives include organic fillers such as silicone-based powder, nylon powder, and fluororesin powder; Thickeners such as Orben and Benton; Polymer-based antifoaming agents or leveling agents such as silicone-based and fluorine-based resins; Adhesion imparting agents such as imidazole-based, thiazole-based, triazole-based, and silane-based coupling agents; Colorants such as phthalocyanine and carbon black, and the like, but are not limited thereto. These may be used alone or in combination of two or more.

According to an example, the insulating layer 120 uses one or more resins selected from the group consisting of polyimide-based resins, polyimide-based resins, and polyamide-imide resins, but may use non-electrically conductive fillers and additives as necessary. It may be formed of a resin composition for forming an insulating layer containing. At this time, the resin composition for forming the insulating layer is about 65 to 90% by weight based on the total amount of the resin composition (e.g., soluble polyimide resin), about 3 to 30% by weight of a non-electrically conductive filler, and about 2 To 5% by weight of a colorant.

According to another example, the insulating layer 120 is a polyimide-based resin, a polyimide-based resin and a polyamide-imide resin mixed with one or more first resins selected from the group consisting of an epoxy resin, but if necessary, non- It may be formed of a resin composition for forming an insulating layer containing an electrically conductive filler and additives. At this time, the resin composition for forming the insulating layer is about 60 to 80% by weight of the first resin (e.g., soluble polyimide resin), about 5 to 10% by weight of epoxy resin, about 3 to 30% based on the total amount of the resin composition. Weight percent non-electrically conductive filler, and about 2 to 5 weight percent colorant.

Here, the soluble polyimide resin can implement chemical resistance and flexibility, and the bisphenol novolac epoxy resin exhibits chemical resistance and rigidity effects. In addition, the non-electrically conductive filler can secure wear resistance and pencil hardness, and a colorant such as carbon black can implement a color desired by the user.

In the electromagnetic wave shielding film of the present invention, the thickness of the insulating layer can be appropriately adjusted in consideration of handling properties of the film, physical rigidity, thinning of the substrate, and the like. For example, it may be about 5 to 20 μm, specifically about 5 to 6 μm.

In addition, the insulating layer 120 may be a single layer or multiple layers. In this case, the single layer may be a layer made of one material or a layer made of a plurality of different materials. Further, the plurality of layers may be a structure of two or more layers in which two or more different materials are stacked by forming each layer. If the insulating layer according to the present invention is not a plurality of layers but a single layer containing a polyimide-based resin, flame retardancy, flexibility and chemical resistance can be secured based on the flame retardant properties of the polyimide itself. In addition, the non-electrically conductive filler may exhibit a friction resistance of 3,000 or more and a pencil hardness of 8 to 9H or more.

3) Conductive adhesive layer

In the electromagnetic wave shielding film according to the present invention, the conductive adhesive layer 130 is disposed on the second surface 110b of the copper foil layer 110, and exhibits an electromagnetic wave shielding effect including a conductive material, and at the same time, adhesive strength and flexibility And exerts interlayer adhesion. In particular, the conductive adhesive layer 130 also serves to secure the electromagnetic shielding film to the adherend. Therefore, the electromagnetic wave shielding film of the present invention is attached to the flexible printed circuit board (FPCB) by the conductive adhesive layer 130, thereby stably connecting to the electrical circuit of the printed circuit board, and electrical noise generated therein is emitted to the outside, or It is possible to effectively shield the noise generated from the outside from entering the printed circuit board.

The conductive adhesive layer 130 may be in the form of a coating layer or a film, in a semi-cured (B-stage) state, or in a fully cured (C-stage) state, and preferably in a semi-cured (B-stage) state.

The conductive adhesive layer 130 is formed by curing or semi-curing a composition for forming a conductive adhesive layer including a conventional thermosetting matrix resin and a conductive filler, and includes a thermosetting resin and a conductive filler.

Here, the conductive filler is uniformly dispersed in the thermosetting resin. Preferably, the conductive fillers are in contact with each other in the thermosetting resin to form an electrically connected network structure.

In the composition for forming a conductive adhesive layer of the present invention, the thermosetting matrix resin is not particularly limited as long as it is a conventional thermosetting resin known in the art. At this time, the thermosetting resin constituting the above-described insulating layer may be the same or different, and a thermosetting resin containing phosphorus (P) and / or non-containing may be used.

Non-limiting examples of thermosetting resins include polyimide resins, polyamide resins, polyamide-imide resins, epoxy resins, polyester resins, polyurethane resins, modified polyurethane resins, phenolic resins and vegetable oil modified There are phenol resin, xylene resin, guanamine resin, diallyl phthalate resin, vinyl ester resin, furan resin, cyanate resin, maleimide resin, benzocyclobutene resin, etc., which are used alone or in combination of two or more. Can be.

According to an example, the composition for forming a conductive adhesive layer may include (a) at least one selected from the group consisting of polyester resins, polyimide resins, polyamide resins, and polyamide-imide resins; And (b) one or more polyfunctional epoxy groups (eg, 2 to 4 epoxy groups) -containing epoxy resin.

According to another example, the composition for forming a conductive adhesive layer includes (a) a polyurethane-based resin (preferably, a polyester-based modified urethane resin); And (b) one or more polyfunctional epoxy groups (eg, 2 to 4 epoxy groups) -containing epoxy resin.

At this time, the polyester-based resin, polyimide-based resin, polyamide-based resin and polyamide-imide resin and polyester-modified urethane resin can improve the lamination properties with other substrate layers and secure the flexibility, and one The above polyfunctional epoxy group (eg, 2 to 4 epoxy groups) -containing epoxy resin is excellent in curability and reactivity with polyester-based resins, polyimide-based resins, polyamide-based resins, and polyamide-imide resins and polyurethanes. Also, excellent heat resistance can be imparted.

The composition for forming a conductive adhesive layer of the present invention may further include other conventional thermosetting resins or thermoplastic resins known in the art, in addition to the aforementioned polyester-based resins, polyurethane resins and epoxy resins. At this time, the thermoplastic resin may use a conventional resin known in the art, for example, one or more selected from the group consisting of polyester-based resin, polyamide-based resin, polycarbonate resin and modified polyphenylene oxide resin can be used. have.

The conductive filler usable in the present invention is not particularly limited as long as it is a conductive filler commonly known in the art, and non-limiting examples include silver (Ag), copper (Cu), nickel (Ni), aluminum (Al), and Ag coating. Cu, Ag coated with Ag, etc., these may be used alone or in combination of two or more. In addition, a polymer filler; And fillers or metal mixtures of metal plating such as resin balls or glass beads. In one example, the conductive filler may be a Cu filler coated with Ag. As another example, the conductive filler may be a Ni filler. As another example, the conductive filler may be a Ni filler coated with Ag.

The shape of the conductive filler is not particularly limited, and for example, there are spherical, flake, dendrite, conical, pyramid, and amorphous shapes. In addition, the average particle diameter (d50) of the conductive filler is not particularly limited, and may be, for example, about 0.1 to 50 μm, and specifically about 1 to 15 μm. At this time, the conductive adhesive layer may have high packing density and low specific resistance. The electromagnetic wave shielding film of the present invention has excellent electromagnetic wave shielding properties, and the contact resistance of the flexible printed circuit board (FPCB) with the ground (GND) may be reduced.

In the conductive adhesive layer 130, the content of the conductive filler is not particularly limited as long as it exhibits an electromagnetic wave shielding effect, for example, about 5 to 60% by weight, specifically about 8 to 35% by weight based on the total amount of the conductive adhesive layer. Can be. However, in the case of the present invention, since a copper foil layer exhibiting an electromagnetic wave shielding effect is included, even if a small amount of the conductive filler is used, the electromagnetic wave shielding characteristics are not reduced.

If necessary, the composition for forming a conductive adhesive layer of the present invention may further include a conventional curing agent known in the art in addition to the above-mentioned thermosetting resin and conductive filler, and these are appropriately selected according to the type of thermosetting resin to be used. Can be used. Non-limiting examples of curing agents include phenol-based, anhydride-based, and dicyanamide-based curing agents. For example, when the thermosetting resin is an epoxy resin, a polyamine-based curing agent, an acid anhydride-based curing agent, a boron trifluoride amine complex salt, an imidazole-based curing agent, an aromatic diamine-based curing agent, a carboxylic acid-based curing agent, a phenol resin, etc. can be used, and double In the phenolic curing agent is preferable because it can further improve the heat resistance and adhesion.

In addition, the conductive adhesive layer of the present invention, as long as it does not impair the inherent properties other than the above-described components, flame retardants generally known in the art as necessary, or other thermosetting resins or thermoplastic resins not described above, such as oligomers Various polymers, solid rubber particles or UV absorbers, antioxidants, polymerization initiators, dyes, pigments, dispersants, thickeners, leveling agents, coloring agents, and other additives may be further included.

On the other hand, the conductive adhesive layer of the present invention, the components constituting the conductive adhesive layer, for example, the thermosetting resin and the conductive filler are generally uniformly distributed, or may have different compositions based on the thickness direction thereof.

For example, the conductive adhesive layer includes a first conductive adhesive layer (upper layer) and a second conductive adhesive layer (lower layer) positioned on both surfaces based on the thickness direction; The first conductive adhesive layer, the intermediate layer, and the second conductive adhesive layer may have different shapes and / or sizes, and the composition of the first conductive filler and the second conductive filler may be different from each other. At this time, the first conductive adhesive layer and the second conductive adhesive layer may include a first conductive filler and a second conductive filler, respectively, and the first conductive filler and the second conductive filler may be mixed in the intermediate layer. Accordingly, the conductive adhesive layer of the present invention may have a gradient profile in which the packing density increases as it goes from the surface to the intermediate layer based on the thickness direction.

According to an example of the present invention, the conductive adhesive layer comprises: (a) at least one first resin selected from the group consisting of a polyester resin, a polyimide resin, a polyamide resin, and a polyamide-imide resin; (b) one or more polyfunctional epoxy groups (eg, 2 to 4 epoxy groups) -containing epoxy resin; And (c) may be formed of a resin composition for forming a conductive adhesive layer comprising a conductive filler. The electromagnetic wave shielding film of the present invention including such a conductive adhesive layer has a step resistance of about 3 when attached to a step portion of a flexible printed circuit board having a thickness of 0.2 mm under conditions of a temperature of 85 ° C., a humidity of 85% and 120 hours. Ω or less.

According to another example of the present invention, the conductive adhesive layer comprises: (a) at least one first resin selected from the group consisting of polyurethane-based resins (preferably, polyester-based modified urethane resins) and epoxy resins; (b) one or more polyfunctional epoxy groups (eg, 2 to 4 epoxy groups) -containing epoxy resin; And (c) may be formed of a resin composition for forming a conductive adhesive layer comprising a conductive filler.

The resin composition for forming the conductive adhesive layer of the present invention described above is about 65 to 85% by weight of the first resin, about 10 to 20% by weight of the polyfunctional epoxy group-containing epoxy resin, and about 5 to about 10% by weight based on the total amount of the resin composition. 25% by weight of a conductive filler.

The conductive adhesive layer 130 according to the present invention can secure a high adhesive strength with the coverlay of the flexible printed circuit board (FPCB). In one example, the peel strength for the coverlay in the C-stage (C-stage) according to the IPC-TM 650 standard may be about 1.0 kgf / cm or more, specifically about 1 to 3 kgf / cm. In addition, the conductive adhesive layer 130 may maintain low contact resistance with GND of the FPCB. In addition, the conductive adhesive layer has a specific resistance of 0.2 to 2.0 Ωcm at normal temperature (20 ± 5 ° C) in a stepped structure FPCB.

As such, the electromagnetic wave shielding film of the present invention may have an electromagnetic wave shielding rate at a frequency of 1 GHz according to ASTM 4935-1 standard of about 70 dB or more, and preferably about 75 to 90 dB. In addition, the electromagnetic wave shielding film of the present invention has a step resistance of about 5.5 MPa or less when attached to a step portion of a flexible printed circuit board having a thickness of 0.2 mm under conditions of a temperature of 85 ° C., a humidity of 85%, and 120 hours. It may preferably be less than or equal to about 3 kPa.

Hereinafter, the electromagnetic wave shielding film 100B according to the second embodiment of the present invention shown in FIG. 2 will be described.

2, the electromagnetic wave shielding film 100B according to the second embodiment includes a copper foil layer 110; An insulating layer 120 disposed on the first surface of the copper foil layer; A conductive adhesive layer 130 disposed on the second surface of the copper foil layer; And a protective film 140 disposed on the insulating layer. Here, in the copper foil layer, the ratio (Ra ₁ / Ra ₂ ) of the average surface roughness (Ra ₁ ) of the first surface 110a to the average surface roughness (Ra ₂ ) of the second surface 100b ranges from 3 to 7 .

In the electromagnetic wave shielding film 100B according to the second embodiment, descriptions of the copper foil layer, the insulating layer, and the conductive adhesive layer are the same as those described in the first embodiment, and thus are omitted.

In the electromagnetic wave shielding film 100B according to the second embodiment, the protective film 140 is a portion disposed on the upper surface of the insulating layer 120, and prevents the insulating layer 120 from being contaminated by external foreign substances, When the electromagnetic shielding film is attached to the flexible printed circuit board through a hot press process, it protects the surface of the film, especially the surface of the insulating layer. When the electromagnetic shielding film is applied to the printed circuit board, the protective film 140 may be removed and removed as necessary.

The protective film usable in the present invention is not particularly limited as long as it is a protective film commonly known in the art, for example, polyester films such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, polyethylene film, poly Propylene film, cellophane, diacetylcellulose film, triacetylcellulose film, acetylcellulose butyrate film, polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film , Polymethylpentene film, polysulfone film, polyetheretherketone film, polyethersulfone film, polyetherimide film, polyimide film, fluororesin film, polyamide film, acrylic resin film, norbornene resin film , Cycloolefin resin film, etc. It is not limited to this.

In addition, the protective film 140 of the present invention may be a protective film for the FPCB process. In this case, the protective film 140 may be easily peeled off and removed after the electromagnetic wave shielding film is attached to the flexible printed circuit board. The peel force of the protective film is not particularly limited, and may be, for example, in the range of about 30 to 100 gf / inch.

The thickness of the protective film is not particularly limited, and may be, for example, about 20 to 80 μm, and specifically 40 to 60 μm.

Hereinafter, the electromagnetic wave shielding film 100C according to the third embodiment of the present invention shown in FIG. 3 will be described.

3, the electromagnetic shielding film 100C according to the third embodiment includes a copper foil layer 110; An insulating layer 120 disposed on the first surface of the copper foil layer; A conductive adhesive layer 130 disposed on the second surface of the copper foil layer; A protective film 140 disposed on the insulating layer; And a release film 150 disposed on the conductive adhesive layer 130. Here, in the copper foil layer, the ratio (Ra ₁ / Ra ₂ ) of the average surface roughness (Ra ₁ ) of the first surface 110a to the average surface roughness (Ra ₂ ) of the second surface 100b ranges from 3 to 7 . However, in the electromagnetic wave shielding film 100C, the protective film 140 may be omitted.

In the electromagnetic wave shielding film 100C according to the third embodiment, the description of the copper foil layer, the insulating layer, and the conductive adhesive layer is the same as described in the first embodiment, and the description of the protective film is the same as described in the second embodiment Because it is, it is omitted.

In the electromagnetic wave shielding film 100C according to the third embodiment, the release film 150 is a portion disposed on the conductive adhesive layer 130 to prevent the conductive adhesive layer from being contaminated from foreign substances in the external environment, The electromagnetic shielding film is peeled off before being applied to the flexible printed circuit board through a hot press (hot press) process.

The release film 150 may be used without limitation as long as it can be peeled as a plastic film commonly known in the art, and a release film can also be used.

Non-limiting examples of plastic films that can be used include polyester films such as polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate, polyethylene films, polypropylene films, cellophane, diacetylcellulose films, and triacetylcellulose films. , Acetyl cellulose butyrate film, polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, polymethylpentene film, polysulfone film, polyether And turketone films, polyethersulfone films, polyetherimide films, polyimide films, fluororesin films, polyamide films, acrylic resin films, norbornene-based resin films, and cycloolefin resin films. The plastic film may be transparent or translucent, or may be colored or uncolored. According to an example, the release film 150 may be polyethylene terephthalate (PET). According to another example, the release film 150 may be polyimide (PI).

A release layer may be disposed on the plastic film. The release layer has a function of easily separating the release film so that the conductive adhesive layer remains intact when separated from the contacting layer, such as the conductive adhesive layer. Here, the release layer may be a generally used film type release material.

The components of the release agent used in the release layer are not particularly limited, and conventional release agent components known in the art can be used. Non-limiting examples thereof include epoxy-based mold release agents, mold release agents made of fluorine resins, silicone mold release agents, alkyd resin mold release agents, water-soluble polymers, and the like. In addition, a powdery filler, for example, silicon, silica, or the like, may be included as a component of the release layer, if necessary. At this time, the powder filler in the form of fine particles may use two types of powder filler, and the average particle size thereof may be appropriately selected in consideration of the surface roughness to be formed.

The thickness of this release layer can be appropriately adjusted within the conventional range known in the art.

In the present invention, the thickness of the release film 150 is not particularly limited, and can be adjusted within a conventional range known in the art, for example, may be about 50 to 140 μm, specifically about 65 to 100 μm, , More specifically, about 65 to 80 μm.

The method for forming the release layer is not particularly limited, and a known method such as heat pressing, heat roll lamination, extrusion lamination, application of a coating liquid, drying, or the like can be employed.

The electromagnetic wave shielding films 100A, 100B, and 100C according to the first to third embodiments of the present invention can be manufactured by various methods. However, in the present invention, in manufacturing an electromagnetic wave shielding film, a conductive adhesive layer, a copper foil layer and an insulating layer, and optionally a protective film and a release film are sequentially stacked, but the copper foil layer adjusted so that the average surface roughness of both surfaces is different from each other Use

In one example, the method of manufacturing the electromagnetic wave shielding film 100A according to the first embodiment comprises the steps of laminating (bonding) a copper foil layer on a carrier copper foil to form a peelable double layer copper foil; Forming a 1A laminate by laminating an insulating layer on the upper surface of the copper foil layer of the separable double-layer copper foil; Forming a 2A laminate by detaching the carrier copper foil from the 1A laminate; And laminating a conductive adhesive layer on the lower surface of the copper foil layer of the 2A laminate, the copper foil layer being in contact with the insulating layer for an average surface roughness (Ra ₂ ) of a second surface in contact with the carrier copper foil. The ratio (Ra ₁ / Ra ₂ ) of the average surface roughness Ra _{1 of the} surface 110a is 3 to 7.

As another example, a method of manufacturing the electromagnetic wave shielding film 100B according to the second embodiment includes the steps of laminating (bonding) a copper foil layer on a carrier copper foil to form a peelable double layer copper foil; Forming an 1B laminate by laminating an insulating layer on the upper surface of the copper foil layer of the separable double-layer copper foil; Forming a 2B laminate by laminating a protective film on the top surface of the insulating layer of the 1B laminate; Forming a 3B stack by detaching the carrier copper foil from the 2B stack; And laminating a conductive adhesive layer on the lower surface of the copper foil layer of the 3B laminate, the copper foil layer being in contact with the insulating layer for an average surface roughness (Ra ₂ ) of a second surface in contact with the carrier copper foil. The ratio (Ra ₁ / Ra ₂ ) of the average surface roughness Ra _{1 of the} surface 110a is 3 to 7.

As another example, the method of manufacturing the electromagnetic wave shielding film 100C according to the third embodiment includes the steps of laminating a copper foil layer on a carrier copper foil to form a peelable double layer copper foil; Forming an 1C layered body by laminating an insulating layer on the upper surface of the copper foil layer of the separable double-layer copper foil; Forming a 2C laminate by depositing a protective film on the top surface of the insulating layer of the 1C laminate; Forming a 3C stack by detaching the carrier copper foil from the 2C stack; Forming a 4C laminate by laminating a conductive adhesive layer on a release film; And stacking a 4C laminate on the lower surface of the copper foil layer of the 3C laminate, and stacking the conductive adhesive layer of the 4C laminate to contact the copper foil layer, wherein the copper foil layer is in contact with the carrier copper foil. the average surface roughness of the ratio of average surface roughness (Ra ₁₎ of the first surface (110a) which is in contact with the insulating layer to the ₍₂ Ra) of the surface (Ra ₁ / Ra ₂₎ is 3 to 7.

However, it is not limited only by the above manufacturing method, and the steps of each process may be modified or selectively mixed as necessary.

4 is a process cross-sectional view schematically showing a process of manufacturing the electromagnetic wave shielding film 100A according to the first embodiment of the present invention.

Hereinafter, each step of manufacturing the electromagnetic wave shielding film 100A according to the first embodiment of the present invention will be described with reference to FIG. 4.

(a) Step of forming a detachable (peelable) double layer copper foil ('S110 step')

A copper foil 110 is stacked on a carrier copper foil 11 to form a peelable double layer copper foil 10A (see FIG. 3 (a)).

In a peelable double layer copper foil, the carrier copper foil and the copper foil layer each have a metal thin film shape composed of a copper material.

Here, the carrier copper foil 11 protects the relatively thin copper foil layer, and serves to physically support the copper foil layer. The carrier copper foil 11 can then be easily separated from the copper foil layer.

The copper foil layer 110 is a part that shields electromagnetic waves from the electromagnetic wave shielding film. However, in the present invention, the copper foil layers 110 having different surface roughnesses are used. In particular, in the present invention, in order to easily remove the carrier copper foil 11, as well as to increase the interlayer adhesion with the insulating layer, the copper foil layer 110 contacting the carrier copper foil 11, that is, then contacting the conductive adhesive layer 130 The roughness of the surface of the surface ('second surface') 110b is smaller than that of the other surface ('first surface') 110a of the copper foil layer 110, that is, smoothly adjusted. At this time, the average surface roughness (Ra ₂ ) of the second surface is not particularly limited, and may be, for example, about 0.1 to 0.5 μm. In one example, the copper foil layer 11 has an average surface roughness of the first surface 110a contacting the insulating layer 120 with respect to the average surface roughness (Ra ₂ ) of the second surface 110b contacting the carrier copper foil 11 ( Ra ₁ ) ratio (Ra ₁ / Ra ₂ ) It can be used that is adjusted to 3 to 7. In another example, the copper foil layer 11 is the ratio of the average surface roughness (Ra ₁ ) of the first surface 110a to the average surface roughness (Ra ₂ ) of the second surface 110b in contact with the carrier copper foil 11 ( As Ra ₁ / Ra ₂ ) is adjusted to 3 to 7, the average surface roughness (Ra ₂ ) of the second surface may be about 0.1 to 0.5 μm.

The carrier copper foil 11 and the copper foil layer 110 are attached (bonded) through molecular bonding. Here, the molecular conjugation is a non-adhesive form of bonding made by metal ion bonding. Therefore, when the carrier copper foil 11 is detached, physical damage does not occur in the copper foil layer 110.

 The thickness of the carrier copper foil 11 is preferably larger than the thickness of the copper foil layer 110 in order to protect the copper foil layer. For example, when the thickness of the copper foil layer is about 1 to 5 μm, the thickness of the carrier copper foil is not particularly limited if it is larger than the size of the second copper foil, and may be, for example, about 3 to 18 times larger than the thickness of the copper foil layer.

In the present invention, the detachable double-layer copper foil or the carrier copper foil and copper foil layer included therein may use copper foil formed by an existing continuous in-line process. In this case, the coating process line can be interlocked with the copper foil manufacturing line to produce continuously.

(b) Lamination of insulating layer ('S120')

By stacking the insulating layer 120 on the upper surface 110a of the copper foil layer 110 of the separable double-layer copper foil 10A obtained in step S110, the carrier copper foil 11, the copper foil layer 110, and the insulating layer 120 are sequentially A 1A stack 20A having a stacked structure is formed (see FIG. 4 (b)).

In the present invention, the insulating layer 120 may be in a semi-cured (B-stage) state or a fully cured (C-stage) state, and preferably in a semi-cured (B-stage) state.

The insulating layer 120 is stacked on the upper surface 110a of the copper foil layer 110 of the separable double-layer copper foil 10A through various methods.

For example, by coating the composition for forming an insulating layer on the copper foil layer 110 of the separable double layer copper foil 10A and drying the insulating layer to form an insulating layer, the insulating layer can be laminated on the copper foil layer. Alternatively, the insulating layer may be laminated on the copper foil layer by applying a composition for forming an insulating layer to a separate base film and drying it to form an insulating layer, and then bonding the formed insulating layer with a separable double layer copper foil. In this case, the base film can then be removed. However, the base film is not removed, it may be included in the electromagnetic shielding film as a film to protect the insulating layer.

In the present invention, the composition for forming an insulating layer includes conventional thermosetting resins and curing agents known in the art. In one example, the composition for forming the insulating layer is at least one selected from the group consisting of polyimide resin, polyamide resin, polyamide-imide resin and polyamic acid solution; And a curing agent, and may optionally further include a thermosetting resin and / or a non-electrically conductive filler. Description of the composition for forming the insulating layer is omitted because it is the same as described in the insulating layer of the electromagnetic wave shielding film according to the first embodiment.

As the base film usable in the present invention, conventional plastic films known in the art can be used without limitation, for example, polyethylene films such as polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate, polyethylene. Film, polypropylene film, cellophane, diacetylcellulose film, triacetylcellulose film, acetylcellulose butyrate film, polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, Polycarbonate film, polymethylpentene film, polysulfone film, polyetheretherketone film, polyethersulfone film, polyetherimide film, polyimide film, fluororesin film, polyamide film, acrylic resin film, Novo Nene-based resin film, cycloolefin resin film, etc. .

The method for applying the composition for forming the insulating layer to the separable double layer copper foil or a separate base film in this step is not particularly limited, for example, a roll coater, bar coater, commer coater, blade coater, lip coater, rod coater, squeeze coater, reverse Coaters, transfer coater roll coaters, gravure coaters, spray coaters, and the like.

The drying temperature and time in this step are not particularly limited, and for example, a composition for forming an insulating layer may be applied to the copper foil layer 110 of the separable double-layer copper foil 10, and dried at about 50 to 130 ° C. for 1 to 30 minutes. have.

(c) Desorption step of carrier copper foil ('step S130')

The carrier copper foil 11 is detached from the 1A stack 20A obtained in step S120 to form a 2A stack 30A (see FIG. 4 (c)). The 2A layered product 30A obtained in this step has a structure in which the copper foil layer 110 and the insulating layer 120 are stacked.

As described in step S110, the carrier copper foil 11 and the copper foil layer 110 are bonded through molecular bonding with metal ions. However, as described in step S110, the copper foil layer 110 has a roughness of the second surface 110b smaller than that of the first surface 110a, and preferably the second surface is smooth. Therefore, the carrier copper foil 11 can be easily removed from the first stacked body 20, and physical damage is not applied to the copper foil layer 110 at this time.

(d) step of laminating the conductive adhesive layer ('step S140')

By laminating the conductive adhesive layer 130 on the lower surface 110b of the copper foil layer 110 of the 2A laminate 30A obtained in step S130, the electromagnetic wave shielding film 100A of the present invention can be obtained (FIG. ) Reference).

In the present invention, the conductive adhesive layer 130 may be in a semi-cured (B-stage) state or a fully cured (C-stage) state, and preferably in a semi-cured (B-stage) state.

The conductive adhesive layer 130 is stacked on the lower surface 110b of the copper foil layer 110 of the third laminate 30 through various methods.

For example, the conductive adhesive layer 130 may be laminated on the lower surface of the copper foil layer 110 by applying and drying the composition for forming the conductive adhesive layer on the lower surface 110b of the copper foil layer 110 of the 2A laminate 30A. have. Alternatively, a conductive adhesive layer forming composition is applied to a separate base film (not shown) and dried to form the conductive adhesive layer 130, and then the formed conductive adhesive layer 130 is coated with a copper foil layer of the 2A laminate 30A ( 110) By bonding (attaching or pressing) to the lower surface, the conductive adhesive layer 130 can be laminated on the lower surface of the copper foil layer 110. Thereafter, the base film can be removed. However, the base film may be removed when the electromagnetic wave shielding film is applied to the printed circuit board. In this case, the base film may be a release film.

The description of the composition for forming a conductive adhesive layer used in this step is the same as described in the conductive adhesive layer of the electromagnetic wave shielding film according to the first embodiment, and the description of the base film is the same as described in step S120, and thus is omitted.

The method of applying the composition for forming a conductive adhesive layer to the 2A laminate or a separate base film in this step is not particularly limited, for example, a roll coater, bar coater, commer coater, blade coater, lip coater, rod coater, squeeze coater, Reverse coaters, transfer coater roll coaters, gravure coaters, spray coaters, and the like.

In this step, the drying temperature and time are not particularly limited, for example, a composition for forming an insulating layer is applied to the lower surface 110b of the copper foil layer 110 of the 2A laminate 30A, and is 1 to about 50 to 130 ° C. Allow to dry for 30 minutes.

5 to 6 are process cross-sectional views schematically showing a process of manufacturing an electromagnetic wave shielding film 100B according to a second embodiment of the present invention.

The manufacturing method of the electromagnetic wave shielding film 100B according to the second embodiment includes the steps of laminating a copper foil layer 110 on a carrier copper foil 11 to form a peelable double layer copper foil 10B (S210); Forming a first B stack 20B by stacking an insulating layer 120 on the top surface 110a of the copper foil layer 110 of the separable double-layer copper foil 10B (S220); Forming a 2B laminate 30B by laminating a protective film on the top surface of the insulating layer 120 (S230); The carrier copper foil 11 is detached from the 2B laminate 30B, and the 3B laminate 40B (a structure in which the copper foil layer 110, the insulating layer 120, and the protective film 140 are sequentially stacked) is formed. Forming step (S240); And stacking a conductive adhesive layer 130 on the lower surface of the copper foil layer 110 of the 3B stack 40B (S250).

Hereinafter, each step of manufacturing the electromagnetic wave shielding film 100B according to the second embodiment of the present invention will be described with reference to FIGS. 5 to 6. However, step S210, step S220, step S240 and step S250 are the same as described in steps S110 to S140, respectively, and descriptions of these steps are omitted.

As shown in (c) of FIG. 5, in step S230, the protective film 140 is laminated on the insulating layer 120 of the first B stack 20B formed in step S220 to form the second B stack 30B. To form.

In this step, the protective film 140 is attached to the insulating layer 120 by an adhesive or adhesive. The pressure-sensitive adhesive and adhesive are not particularly limited as long as they are known in the art.

Since the description of the protective film 140 is the same as that described in the second embodiment, it is omitted.

7 to 8 are process cross-sectional views schematically showing a process of manufacturing an electromagnetic wave shielding film 100C according to a third embodiment of the present invention.

The manufacturing method of the electromagnetic wave shielding film 100B according to the third embodiment comprises the steps of laminating a copper foil layer 110 on a carrier copper foil 11 to form a peelable double layer copper foil 10C (S310); Forming a 1C stacked body 20C by laminating an insulating layer 120 on the top surface 110a of the copper foil layer 110 of the separable double-layer copper foil 10C (S320); Forming a 2C layered body 30C by laminating a protective film 140 on the upper surface of the insulating layer 120 (S330); Detaching the carrier copper foil 11 from the 2C stack 30C to form a 3C stack 40C (S340); Forming a 4C stacked body 50C by laminating the conductive adhesive layer 130 on the release film 150 (S350); And a 4C stacked body 50C is stacked on the lower surface 110b of the copper foil layer 110 of the 3C stacked body 40C, but the conductive adhesive layer 130 of the 4C stacked body 50C is the copper foil layer 110. It includes a step (S360) of stacking so as to contact the lower surface (110b) of the.

Hereinafter, each step of manufacturing the electromagnetic wave shielding film 100C according to the third embodiment of the present invention will be described with reference to FIGS. 7 to 8. However, since steps S310 to S340 are the same as described in steps S210 to S240, respectively, descriptions of these steps are omitted.

As shown in FIG. 8 (e), in step S350, the conductive adhesive layer 130 is laminated on the release film 150 to form a 4C stack 50C. At this time, the conductive adhesive layer 130 may be formed by applying a composition for forming a conductive adhesive layer on the release film 150 and drying it, but is not limited thereto. This step has no temporal and sequential relationship with steps S310 to S340.

The description of the release film used in this step is the same as that described in the electromagnetic wave shielding film of the third embodiment, and the description of the composition for forming the conductive adhesive layer is the same as that described in the electromagnetic wave shielding film of the first embodiment, and thus is omitted.

As shown in (f) of FIG. 8, in the step S360, the 4C stack 50C formed in the step S350 is placed on the lower surface 110b of the copper foil layer 110 of the 3C stack 40C formed in the step S340. Stack. At this time, the adhesive layer 130 of the 4C laminate 50C is laminated so as to contact the lower surface 110b of the copper foil layer 110. Thereby, the electromagnetic wave shielding film 100C according to the third embodiment of the present invention is formed.

<Printed circuit board>

In addition, the present invention provides a printed circuit board, preferably a flexible printed circuit board (FPCB) comprising the aforementioned electromagnetic wave shielding film (100A, 100B, 100C). In the present invention, by bonding the electromagnetic wave shielding film to the flexible printed circuit board body as described above, it is excellent in electromagnetic wave shielding even in various frequency regions, such as a high frequency region of 1 GHz or more. Therefore, the flexible printed circuit board of the present invention can be used in electronic / communication devices such as USB cables, EDP cables, etc., which are high-speed transmission modes, to improve transmission quality.

In one example, the printed circuit board may include a substrate body including a circuit pattern of one or more layers; And an electromagnetic wave shielding film disposed on one or both surfaces of the substrate body.

The substrate body usable in the present invention is a printed circuit board body including a circuit pattern of one or more layers, and may preferably be a flexible printed circuit board body. At this time, a coverlay is stacked on the circuit pattern of one or more layers. For example, the flexible printed circuit board body may be a flexible copper foil laminate (FCCL) with a coverlay attached. For example, the flexible printed circuit board main body may have a form in which one or more circuit patterns and a coverlay are sequentially stacked on polyimide (PI). In the present invention, the printed circuit board refers to a printed circuit board stacked in a single layer or two to three or more layers by a plated-through hole method or a build-up method, and may have a single-sided type or a double-sided type.

In the present invention, the above-mentioned electromagnetic wave shielding films 100A, 100B, and 100C can be used after being laminated on a cover body of a substrate body, preferably a flexible printed circuit board (FPCB) body, including a circuit pattern of one or more layers. have. At this time, the conductive adhesive layer 130 of the electromagnetic wave shielding films 100A, 100B, and 100C is bonded to the upper coverlay of the flexible printed circuit board body. However, when the electromagnetic wave shielding film 100C includes a release film, after removing the release film, the electromagnetic wave shielding film is bonded to the printed circuit board.

In one example, the electromagnetic wave shielding type flexible printed circuit board is laminated with an electromagnetic wave shielding film over the coverlay of the flexible printed circuit board body, and then laminated so that the conductive adhesive layer is in contact with the top of the coverlay, and then thermally compressed.

The thermocompression conditions are not particularly limited, and for example, after laminating a flexible printed circuit board body and an electromagnetic wave shielding film, a temperature of about 140 to 170 ° C., a pressure of 30 to 60 kgf / cm ² , and a condition of 50 to 60 minutes. It can be heat-pressed under.

Hereinafter, the present invention will be specifically described through Examples, but the following Examples and Experimental Examples are merely illustrative of one form of the present invention, and the scope of the present invention is not limited by the following Examples and Experimental Examples. .

[ Example  1: Preparation of electromagnetic wave shielding film]

1-1. Insulation layer  Preparation of coating solution for formation

Polyamide-imide (Toyobo, VYLOMAX ^® HR-16NN) 98.5 wt% and carbon black filler (Columbian Chemicals) 1.5 wt% were mixed and dispersed to prepare a coating solution for forming an insulating layer.

1-2. Preparation of coating solution for forming conductive adhesive layer

Polyimide resin (Arakawa Chemical, PIAD-100H) 80% by weight, acicular conductive filler (Mitsui, ACBY-2F, average particle diameter: 2.5 μm) 14% by weight, and a polyfunctional epoxy resin (Mitsubishi Gas Chemical, TETRAD- as a curing agent) X) 6 wt% was mixed and dispersed using a Planetary Mixer to prepare a coating solution for forming a conductive adhesive layer.

1-3. Preparation of electromagnetic shielding film

Attach (bond) an electrolytic copper foil (thickness: 2 µm, average surface roughness (Rz): 2.0 µm, average surface roughness (Ra): 0.3 µm) of the second surface) to the carrier copper foil (thickness: 18 µm) To prepare a peelable (peelable) double layer copper foil. Then, on the first surface of the electrolytic copper foil, a coating liquid for forming an insulating layer prepared in Example 1-1 was comma coated, and then dried at 150 ° C. for 4 minutes to form an insulating layer (thickness: 7 ± 1 Μm). Subsequently, a polyethylene terephthalate film (AMP, MM-25210W, thickness: 50 μm) having an adhesive layer (thickness: 10 μm) was bonded onto the insulating layer, and then the carrier copper foil was detached and removed from the separated double layer copper foil. . Meanwhile, the coating solution for forming the conductive adhesive layer prepared in Example 1-2 was gravure coated on one surface of a release film (Taeul Film, SR-75LN, thickness: 75 μm), and then dried at 120 ° C. for 5 minutes. Then, a semi-cured conductive adhesive layer (thickness: 16 µm) was formed. Thereafter, the conductive adhesive layer formed on the release film and the electrolytic copper foil were placed in contact with each other, and then pressed under a pressure condition of 130 ° C. and a pressure of 10 kgf / cm 2 to produce an electromagnetic wave shielding film.

[Example 2]

In Example 1-2, a polyamide-imide resin solution (Toyobo, SP3000) was used instead of the polyimide resin (Arakawa Chemical, PIAD-100H) used when forming the coating solution for forming the conductive adhesive layer. An electromagnetic wave shielding film was manufactured in the same manner as in step 1.

[Example 3]

In Example 1-2, except for using an epoxy resin (Doosan, DC-200 varnish) instead of the polyimide resin (Arakawa Chemical, PIAD-100H) used when forming the coating solution for forming the conductive adhesive layer, Example 1 and An electromagnetic wave shielding film was prepared by performing the same procedure.

[Example 4]

In Example 1-2, except for using a polyester resin (Toyobo, BX-39SS) instead of the polyimide resin (Arakawa Chemical, PIAD-100H) used when forming the coating solution for forming the conductive adhesive layer, Example 1 and An electromagnetic wave shielding film was prepared by performing the same procedure.

[Example 5]

In Example 1-1, except for using polyamic acid (Doosan, DSFlex PI varnish) instead of the polyamide-imide resin solution (Toyobo, VYLOMAX ^® HR-16NN) used when forming the coating solution for forming the insulating layer. An electromagnetic wave shielding film was manufactured in the same manner as in Example 1.

[Example 6]

In Example 1-1, polyamic acid (Doosan, DSFlex PI varnish) was used instead of the polyamide-imide resin solution (Toyobo, VYLOMAX ^® HR-16NN) used in forming the coating solution for forming the insulating layer. The same as in Example 1, except that a polyamide-imide resin solution (Toyobo, SP3000) was used instead of the polyimide resin (Arakawa Chemical, PIAD-100H) used when forming the coating solution for forming the conductive adhesive layer in 1-2. It was carried out to prepare an electromagnetic wave shielding film.

[Example 7]

In Example 1-1, polyamic acid (Doosan, DSFlex PI varnish) was used instead of the polyamide-imide resin solution (Toyobo, VYLOMAX ^® HR-16NN) used in forming the coating solution for forming the insulating layer. Performed in the same manner as in Example 1, except that an epoxy resin (Doosan, DC-200 varnish) was used instead of the polyimide resin (Arakawa Chemical, PIAD-100H) used when forming the coating solution for forming the conductive adhesive layer in 1-2. By doing so, an electromagnetic shielding film was prepared.

[Comparative Example 1]

1-1. Preparation of coating solution for forming insulating layer

Polyamide-imide (Toyobo, VYLOMAX ^® HR-16NN) 98.5% by weight and carbon black filler (Columbian Chemicals) 1.5% by weight were mixed and dispersed to prepare a coating solution for forming an insulating layer.

1-2. Preparation of coating solution for forming conductive adhesive layer

Modified polyurethane resin (Nanochemical, NPE-2200), acicular conductive filler [Mitsui, ACY-2F, average particle diameter: 2.5 µm] 93% by weight, and a bifunctional epoxy resin as a curing agent (Kukdo Chemical, YD-011) , And bisphenol A-type epoxy resin (Nanox Chemical, NH-E220) 4% by weight was mixed and dispersed using a Planetary Mixer to prepare a coating solution for forming a conductive adhesive layer.

1-3. Preparation of electromagnetic shielding film

On one side of the PET film, a coating solution for forming an insulating layer prepared in Example 1-1 was comma coated, and then dried at 150 ° C. for 4 minutes to form an insulating layer (thickness: 7 ± 1 μm). On the other hand, the coating solution for forming a conductive adhesive layer prepared in Example 1-2, a gravure coating (gravure coating) on one surface of a release film (Taefilm, SR-75-80, thickness: 75 ㎛), and then at 120 ℃ 5 It was dried for minutes to form a semi-cured conductive adhesive layer (thickness: 18 μm). Thereafter, the conductive adhesive layer formed on the release film and the insulating layer formed on the PET film were placed in contact with each other, and then pressed under a heating and pressing process at 90 ° C and 10 kgf / cm to prepare an electromagnetic wave shielding film.

[Comparative Example 2]

In Comparative Example 1-1, except for using polyamic acid (Doosan, DSFlex PI varnish) instead of the polyamide-imide resin solution (Toyobo, VYLOMAX ^® HR-16NN) used when forming the coating solution for forming the insulating layer, An electromagnetic wave shielding film was prepared in the same manner as in Comparative Example 1.

[Comparative Example 3]

In Comparative Example 1-1, polyamic acid (Doosan, DSFlex PI varnish) was used instead of the polyamide-imide resin solution (Toyobo, VYLOMAX ^® HR-16NN) used when forming the coating solution for forming the insulating layer, and Comparative Example 1- The same as in Comparative Example 1, except that in step 2, a polyimide resin (Arakawa Chemical, PIAD-100H) was used instead of the modified polyurethane resin (Nanochemical, NPE-2200) used when forming the coating solution for forming the conductive adhesive layer. It was carried out to prepare an electromagnetic wave shielding film.

[Evaluation Example 1: Evaluation of electromagnetic wave shielding film]

For the electromagnetic wave shielding films prepared in Examples 1 to 7 and Comparative Examples 1 to 3, respectively, the following physical property evaluations were performed, and the results are shown in Table 1 below.

1) Peel Strength

The electromagnetic wave shielding film from which the release film (thickness: 75 µm) was removed after first contacting the coverlay film (thickness 27 µm) from which the release paper had been removed on one side of the 0.3T FR4 substrate plate with a sizing machine at a temperature of 110 ° C After attaching the coverlay film to the conductive adhesive layer surface of the adhesive, and cured the conductive adhesive layer by pressing at a pressure of 35 kgf / ㎠ for 60 minutes at a temperature of 170 ℃, remove the protective film from the electromagnetic shielding film, here A polyimide reinforcement plate (thickness: 3 mm) was placed on the sample, and then pressed at a pressure of 35 kgf / cm 2 at 170 ° C. for 60 minutes to prepare a sample. The prepared sample was cut to a width of 1 cm in a compressed state to measure peel strength (kgf / cm) according to the IPC-TM 650 standard.

2) Step resistance

After the electromagnetic wave shielding film was cut to 1.5 cm × 11 cm, the release film (thickness: 75 μm) was removed. Thereafter, a circuit open area of a flexible circuit board coupon having a 0.3T step thickness reinforced plate shown in FIG. 9 is disposed on the conductive adhesive layer surface of the electromagnetic wave shielding film, and then pre-bonded with a high-temperature heating plate equipment. To obtain a laminate. After confirming the pre-bonding state of the laminate, after compressing the laminate at a pressure of 35 kgf / cm 2 for 60 minutes at a temperature of 170 ° C. in a hot press facility, after curing the conductive adhesive layer in the laminate, the After the protective film was manually removed from the laminate, the adhesion state of the insulating layer was confirmed. Thereafter, the terminal area was connected to a current voltage resistance meter (Asahi Digitel tester equipment) to check the resistance value. The step resistance was measured under normal temperature (about 20 ° C) conditions and constant temperature and humidity conditions (temperature of 85 ° C, humidity of 85%, 120 hours).

3) Electromagnetic shielding rate

After removing the release film of the electromagnetic wave shielding film, the conductive adhesive layer of the electromagnetic wave shielding film is placed on a PI film (SKC Kolon, thickness 0: 25 µm), and then pressed for 60 minutes at a temperature of 140 ° C. under a pressure of 35 kgf per unit area. The process was performed to completely cure the insulating layer and the conductive adhesive layer. Thereafter, the electromagnetic wave shielding film was manufactured as a coupon having a predetermined shape as shown in FIG. 10 to measure the electromagnetic wave shielding rate (dB) for a 1 GHz frequency according to the ASTM 4935-1 test method. At this time, the tester was used Agilent 8719C Network Analyzer.

Peel strength (kgf / cm) Step resistance (Ω) Electromagnetic wave shielding rate (dB) Copper foil-insulation layer Copper foil-adhesive layer Adhesive layer-coverlay Adhesive layer-circuit wiring Room temperature Constant temperature and humidity 1 GHz Example One 1.72 1.32 1.12 0.63 1.5 2.6 79 2 1.64 0.78 1.45 0.72 1.0 3.0 81 3 1.65 0.62 0.91 0.67 3.4 5.4 77 4 1.78 1.52 1.54 1.53 0.2 0.5 80 5 2.14 1.29 1.02 0.58 2.1 3.3 78 6 2.20 0.82 1.55 0.81 1.9 1.9 79 7 2.11 0.68 0.87 0.77 NG NG 80 Comparative example One - - 1.63 0.92 NG NG 30 2 - - 1.73 0.85 NG NG 40 3 - - 1.21 0.47 NG NG 20

100A, 100B, 100C: electromagnetic wave shielding film,
110: copper foil layer, 110a: first surface,
110b: second surface, 120: insulating layer,
130: conductive adhesive layer, 140: protective film,
150: release film, 10A, 10B, 10C: separable double-layer copper foil,
20A, 20B, 20C: first laminate, 30A, 30B, 30C: second laminate,
40B, 40C: third laminate, 50C: fourth laminate

Claims (11)

Copper foil layer;
An insulating layer disposed on the first surface of the copper foil layer; And
Conductive adhesive layer disposed on the second surface of the copper foil layer
Including,
In the copper foil layer, the ratio (Ra ₁ / Ra ₂ ) of the average surface roughness (Ra ₁ ) of the first surface to the average surface roughness (Ra ₂ ) of the second surface is 3 to 7,
Electromagnetic shielding film having an electromagnetic shielding rate of 70 dB or more at a frequency of 1 GHz according to the ASTM 4935-1 test method. According to claim 1,
An electromagnetic wave shielding film further comprising a protective film disposed on the insulating layer. According to claim 1,
An electromagnetic wave shielding film having a step resistance of 5.5 MPa or less when attached to a printed circuit board having a step portion under a temperature of 85 ° C, a humidity of 85% and a condition of 120 hours. According to claim 1,
The copper foil layer has a first surface having a peel strength of 1 to 3 kgf / cm for an insulating layer according to the IPC-TM-650 standard, and a second surface having a peel strength of 1 to 2 kgf / cm for a conductive adhesive layer. , Electromagnetic shielding film. According to claim 1,
The ratio [(t ₁ + t ₂ ) / T] of the total thickness (t ₁ + t ₂ ) of the copper foil layer and the conductive adhesive layer to the thickness (T) of the electromagnetic wave shielding film is 0.65 to 0.85. The method of claim 5,
The ratio (t ₁ / t ₂ ) of the thickness t ₁ of the copper foil layer to the thickness t ₂ of the conductive adhesive layer is 0.1 to 0.4. According to claim 1,
The conductive adhesive layer is an electromagnetic wave shielding film having a peel strength for the coverlay of 1.0 kgf / cm to 3.0 kgf / cm in a C-stage state according to the IPC-TM-650 standard. According to claim 1,
The conductive adhesive layer is an electromagnetic wave shielding film comprising a thermosetting resin and a conductive filler. The method of claim 8,
The content of the conductive filler is 8 to 35% by weight based on the total amount of the conductive adhesive layer electromagnetic shielding film. According to claim 1,
An electromagnetic wave shielding film further comprising a release film disposed on the lower surface of the conductive adhesive layer. A substrate including a circuit pattern of one or more layers; And
The electromagnetic wave shielding film according to any one of claims 1 to 10 disposed on one or both surfaces of the substrate.
Electromagnetic wave shielding type flexible printed circuit board comprising a.

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