CN112351574B - Electromagnetic shielding film, circuit board and preparation method of electromagnetic shielding film - Google Patents

Electromagnetic shielding film, circuit board and preparation method of electromagnetic shielding film Download PDF

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Publication number
CN112351574B
CN112351574B CN201911393431.8A CN201911393431A CN112351574B CN 112351574 B CN112351574 B CN 112351574B CN 201911393431 A CN201911393431 A CN 201911393431A CN 112351574 B CN112351574 B CN 112351574B
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China
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insulating layer
layer
shielding film
electromagnetic wave
electromagnetic
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CN112351574A (en
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苏陟
高强
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Guangzhou Fangbang Electronics Co Ltd
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Guangzhou Fangbang Electronics Co Ltd
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0213—Electrical arrangements not otherwise provided for
    • H05K1/0216—Reduction of cross-talk, noise or electromagnetic interference
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar form; Layered products having particular features of form
    • B32B3/02—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar form; Layered products having particular features of form characterised by features of form at particular places, e.g. in edge regions
    • B32B3/08—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar form; Layered products having particular features of form characterised by features of form at particular places, e.g. in edge regions characterised by added members at particular parts
    • B32B3/085—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar form; Layered products having particular features of form characterised by features of form at particular places, e.g. in edge regions characterised by added members at particular parts spaced apart pieces on the surface of a layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar form; Layered products having particular features of form
    • B32B3/26—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar form; Layered products having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer
    • B32B3/266—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar form; Layered products having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer characterised by an apertured layer, the apertures going through the whole thickness of the layer, e.g. expanded metal, perforated layer, slit layer regular cells B32B3/12
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B33/00—Layered products characterised by particular properties or particular surface features, e.g. particular surface coatings; Layered products designed for particular purposes not covered by another single class
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
    • B32B37/02—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by a sequence of laminating steps, e.g. by adding new layers at consecutive laminating stations
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00—Screening of apparatus or components against electric or magnetic fields
    • H05K9/0073—Shielding materials
    • H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2264/00—Composition or properties of particles which form a particulate layer or are present as additives
    • B32B2264/02—Synthetic macromolecular particles
    • B32B2264/0207—Particles made of materials belonging to B32B25/00
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2264/00—Composition or properties of particles which form a particulate layer or are present as additives
    • B32B2264/02—Synthetic macromolecular particles
    • B32B2264/0214—Particles made of materials belonging to B32B27/00
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2264/00—Composition or properties of particles which form a particulate layer or are present as additives
    • B32B2264/10—Inorganic particles
    • B32B2264/105—Metal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2264/00—Composition or properties of particles which form a particulate layer or are present as additives
    • B32B2264/12—Mixture of at least two particles made of different materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/20—Properties of the layers or laminate having particular electrical or magnetic properties, e.g. piezoelectric
    • B32B2307/206—Insulating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/20—Properties of the layers or laminate having particular electrical or magnetic properties, e.g. piezoelectric
    • B32B2307/212—Electromagnetic interference shielding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2457/00—Electrical equipment
    • B32B2457/08—PCBs, i.e. printed circuit boards
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/07—Electric details
    • H05K2201/0707—Shielding
    • H05K2201/0715—Shielding provided by an outer layer of PCB

Abstract

The invention discloses an electromagnetic shielding film, a circuit board and a preparation method of the electromagnetic shielding film, wherein the electromagnetic shielding film comprises an insulating layer, a shielding layer and a glue film layer which are arranged in a stacked mode, and the shielding layer is arranged between the insulating layer and the glue film layer; and an electromagnetic wave absorption material is arranged in the insulating layer. According to the invention, the electromagnetic wave absorbing material is arranged in the insulating layer of the electromagnetic shielding film, so that the electromagnetic wave absorbing material in the insulating layer can absorb electromagnetic wave signals, thereby reducing or effectively avoiding the influence of the electromagnetic wave signals on the high-frequency transmission of the circuit board, and the electromagnetic shielding film can reduce the insertion loss of the circuit board when applied to the circuit board, so that the circuit board can be effectively applied to ultrahigh-frequency transmission.

Description

Electromagnetic shielding film, circuit board and preparation method of electromagnetic shielding film
Technical Field
The invention relates to the technical field of shielding films, in particular to an electromagnetic shielding film, a circuit board and a preparation method of the electromagnetic shielding film.
Background
With the rapid development of the electronic industry, electronic products are further miniaturized, light-weighted and densely assembled, and the development of flexible circuit boards is greatly promoted, so that the integration of element devices and wire connection is realized. The flexible circuit board can be widely applied to industries such as mobile phones, liquid crystal display, communication, aerospace and the like.
Under the push of the international market, the functional flexible printed circuit board is dominant in the flexible printed circuit board market, and an important index for evaluating the performance of the functional flexible printed circuit board is Electromagnetic Shielding ((EMI Shielding for short), along with the integration of functions of electronic devices such as mobile phones and the like, the rapid high-frequency and high-speed of internal components thereof.
At present, a shielding film commonly used for an existing circuit board comprises a shielding layer and a conductive adhesive layer, wherein the shielding layer is connected with a circuit board stratum through the conductive adhesive layer, so that interference charges are guided into the circuit board stratum, and shielding is achieved. However, during high-frequency transmission, eddy current loss is generated by the conductive particles in the conductive adhesive layer, so that the insertion loss of the circuit board is increased, and the integrity of signal transmission is affected.
Disclosure of Invention
The invention aims to provide an electromagnetic shielding film which is applied to a circuit board, can reduce the insertion loss of the circuit board and enables the circuit board to be effectively applied to ultrahigh frequency transmission.
The electromagnetic shielding film provided by the embodiment of the invention comprises an insulating layer, a shielding layer and a film layer which are arranged in a stacked manner, wherein the shielding layer is arranged between the insulating layer and the film layer; and an electromagnetic wave absorption material is arranged in the insulating layer.
Compared with the prior art, according to the electromagnetic shielding film provided by the embodiment of the invention, the electromagnetic wave absorbing material is arranged in the insulating layer of the electromagnetic shielding film, so that the electromagnetic wave absorbing material in the insulating layer can absorb electromagnetic wave signals (including the electromagnetic wave signals generated during high-frequency transmission of the circuit board), and the influence of the electromagnetic wave signals on the high-frequency transmission of the circuit board can be reduced or effectively avoided, so that the electromagnetic shielding film is applied to the circuit board, the insertion loss of the circuit board can be reduced, and the circuit board can be effectively applied to ultrahigh-frequency transmission.
As an improvement of the above scheme, a plurality of through holes are formed in the insulating layer, each through hole penetrates through two opposite surfaces of the insulating layer, and the electromagnetic wave absorbing material is arranged in each through hole.
As an improvement of the above, the two opposite surfaces are an upper surface and a lower surface of the insulating layer.
As an improvement of the scheme, the through hole is a round hole, a square hole, a polygonal hole or a special-shaped hole.
As an improvement of the above, the through holes are uniformly or non-uniformly distributed on the insulating layer.
In a modification of the above, a total open area of the plurality of through holes occupies 25 to 65% of an area of any one of the surfaces of the insulating layer.
As an improvement of the scheme, the mass of the insulating layer after the through hole is formed is 15-80% of the mass of the insulating layer before the through hole is formed.
As an improvement of the above scheme, a cavity is arranged in the insulating layer, and the electromagnetic wave absorbing material is arranged in the cavity.
As an improvement of the above scheme, the number of the cavities is multiple, and the multiple cavities are uniformly or non-uniformly distributed in the insulating layer.
As an improvement of the above, the electromagnetic wave absorbing material is in the form of particles.
As an improvement of the above aspect, the electromagnetic wave absorbing material has conductivity, and a part or all of the electromagnetic wave absorbing material is conductively connected to the shielding layer; wherein the electromagnetic wave absorbing material has a conductivity weaker than that of the shielding layer.
As an improvement of the above scheme, the electromagnetic wave absorbing material is a conductive metal, a conductive sponge, a conductive plastic or a conductive rubber.
As an improvement of the scheme, the thickness of the insulating layer or the shielding layer is 2-8 microns.
Another objective of the present invention is to provide a circuit board, which includes a circuit board body and the electromagnetic shielding film according to any one of the above aspects, wherein the electromagnetic shielding film is disposed on the circuit board body, and the shielding layer of the electromagnetic shielding film is connected to the ground layer in the circuit board body.
Compared with the prior art, the circuit board provided by the embodiment of the invention can reduce the insertion loss of the circuit board by applying the electromagnetic shielding film, so that the circuit board can be effectively applied to ultrahigh frequency transmission.
Another object of the present invention is to provide a method for preparing an electromagnetic shielding film, which is suitable for preparing the electromagnetic shielding film according to any one of the above aspects, comprising the steps of:
manufacturing and forming an insulating layer;
arranging an electromagnetic wave absorption material in the insulating layer;
forming a shielding layer on one side of the insulating layer;
and forming a film adhesive layer on one surface of the shielding layer far away from the insulating layer.
Compared with the prior art, according to the preparation method of the electromagnetic shielding film provided by the embodiment of the invention, the electromagnetic wave absorbing material is arranged in the insulating layer of the electromagnetic shielding film, so that the electromagnetic wave absorbing material in the insulating layer can absorb electromagnetic wave signals (including the electromagnetic wave signals generated during high-frequency transmission of the circuit board), and the influence of the electromagnetic wave signals on the high-frequency transmission of the circuit board can be reduced or effectively avoided, so that the electromagnetic shielding film is applied to the circuit board, the insertion loss of the circuit board can be reduced, and the circuit board can be effectively applied to ultrahigh-frequency transmission.
As an improvement of the above solution, the disposing an electromagnetic wave absorbing material in the insulating layer includes:
forming a through hole in the insulating layer; the through hole penetrates through two opposite surfaces of the insulating layer;
arranging an electromagnetic wave absorption material in the through hole;
or, comprising:
and forming a cavity in the insulating layer, and arranging an electromagnetic wave absorption material in the cavity.
Drawings
Fig. 1 is a schematic structural view of an electromagnetic shielding film according to an embodiment of the present invention;
fig. 2 is a schematic structural view of another electromagnetic shielding film according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a circuit board according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of another circuit board according to an embodiment of the present invention;
wherein, 1, an insulating layer; 11. a through hole; 12. a cavity; 2. a shielding layer; 3. an electromagnetic wave absorbing material; 4. a glue film layer; 5. the circuit board body.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection of the present invention.
Referring to fig. 1 and fig. 2, an electromagnetic shielding film according to an embodiment of the present invention includes an insulating layer 1, a shielding layer 2, and a glue film layer 4, which are stacked, where the shielding layer 2 is disposed between the insulating layer 1 and the glue film layer 4; an electromagnetic wave absorbing material 3 is arranged in the insulating layer 1.
It should be noted that, when the electromagnetic shielding film is applied to a circuit board, the electromagnetic shielding film may be laminated with the circuit board through the adhesive film layer 4. When the electromagnetic shielding film is arranged on the circuit board, the shielding layer 2 can be in contact with or connected with the ground layer of the circuit board so as to lead out interference charges accumulated in the electromagnetic shielding film. In addition, the electromagnetic wave absorbing material 3 has a function of absorbing electromagnetic waves, which is capable of absorbing electromagnetic wave energy projected to its surface and converting the electromagnetic waves into heat energy or other forms of energy by means of dielectric loss or the like.
In the embodiment of the invention, the electromagnetic wave absorbing material 3 is arranged in the insulating layer 1 of the electromagnetic shielding film, so that the electromagnetic wave absorbing material 3 in the insulating layer 1 can absorb electromagnetic wave signals (including electromagnetic wave signals generated during high-frequency transmission of the circuit board), thereby reducing or effectively avoiding the influence of the electromagnetic wave signals on the high-frequency transmission of the circuit board, and thus, the electromagnetic shielding film can reduce the insertion loss of the circuit board when applied to the circuit board, and the circuit board can be effectively applied to ultrahigh-frequency transmission.
In this embodiment, as an example of one way of disposing the electromagnetic wave absorbing material 3 in the insulating layer 1, referring to fig. 1, a plurality of through holes 11 are disposed on the insulating layer 1, each through hole 11 penetrates through two opposite surfaces of the insulating layer 1, and the electromagnetic wave absorbing material 3 is disposed in each through hole 11.
In the present embodiment, by forming the through hole 11 in the insulating layer 1 and providing (optionally filling) the electromagnetic wave absorbing material 3 therein, the electromagnetic wave absorbing material 3 can be fixed in the insulating layer 1, and the electromagnetic wave absorbing material 3 can effectively absorb the electromagnetic wave signal reaching the insulating layer 1.
In addition, the thickness of the electromagnetic shielding film in the prior art is generally in the range of 7-8um, and due to the certain thickness and the low air permeability, a plate explosion phenomenon (for example, a circuit board is at a high temperature) that the electromagnetic shielding film and the circuit board cannot be completely attached, such as bulging, can easily occur between the electromagnetic shielding film and the circuit board, especially, the circuit board is generally provided with a window, and the position of the window corresponds to the grounding circuit of the circuit board (that is, the window is an opening formed in a covering film layer on the surface of the circuit board, and the opening can expose the grounding circuit of the circuit board), so that when the electromagnetic shielding film is arranged on the circuit board, the phenomenon that the electromagnetic shielding film is more easily bulged or even cracked due to the bulging can occur at the position where the window is attached. In this embodiment, the insulating layer 1 may have a certain air permeability, so that the electromagnetic shielding film may have a better air permeability, so that the electromagnetic shielding film provided with the electromagnetic wave absorbing material 3 may further avoid the electromagnetic shielding film from bulging or even cracking while effectively absorbing the electromagnetic wave signal.
Exemplarily, referring to fig. 1, the through hole 11 penetrates through two opposite surfaces of the insulating layer 1, which are an upper surface and a lower surface of the insulating layer 1. When the electromagnetic shielding film is arranged on the circuit board, the insulating layer 1, the shielding layer 2 and the adhesive film layer 4 are sequentially arranged on the surface of the circuit board from top to bottom, and the insulating layer 1 is provided with the through holes 11 penetrating through the upper surface and the lower surface of the insulating layer 1, so that the insulating layer 1 has better air permeability for the circuit board, the electromagnetic shielding film also has better air permeability, and the phenomena of bulging, even cracking and the like of the electromagnetic shielding film can be effectively avoided.
The through hole 11 is, for example, a circular hole, a square hole, a polygonal hole, a special-shaped hole, or the like, and is not particularly limited herein.
Illustratively, the plurality of through holes 11 are uniformly or non-uniformly distributed on the insulating layer 1.
Illustratively, the total open area of the plurality of through holes 11 occupies 25-65% of the area of any one of the surfaces of the shielding layer 2, which enables the insulating layer 1 to have better air permeability and better absorption of electromagnetic wave signals. Further, the insulating layer 1 can also be made to realize a certain function of electromagnetic wave shielding.
For example, the number of openings of the through hole 11 may be represented as: the mass of the insulating layer 1 after the through hole 11 is formed is 15-80% of the mass of the insulating layer 1 before the through hole 11 is formed. This enables the insulating layer 1 to have good air permeability and to better absorb electromagnetic wave signals.
Illustratively, the electromagnetic wave absorbing material 3 is in a granular shape, which enables the through hole 11 to have good air permeability, and at the same time, the through hole 11 can be conveniently filled, so that the insulating layer 1 has a certain electromagnetic wave signal absorption performance.
In the above embodiment, as another way of disposing the electromagnetic wave absorption material 3 in the insulating layer 1, for example, referring to fig. 2, a cavity 12 is disposed in the insulating layer 1, and the electromagnetic wave absorption material 3 is disposed in the cavity 12. This enables the electromagnetic wave absorbing material 3 to be fixed in the insulating layer 1, and the electromagnetic wave absorbing material 3 can effectively absorb the electromagnetic wave signal that reaches the insulating layer 1.
It is understood that the cavity 12 may be closed, or may be semi-open, and the like, and is not limited thereto. When the cavity 12 is closed, the electromagnetic wave absorbing material 3 can be stably fixed in the shielding layer 2, and is not easy to fall off. When the electromagnetic wave absorbing material 3 is a semi-open type, the air permeability of the insulating layer 1 can be improved. It should be noted that, no matter whether the cavity 12 is closed or semi-open, the air permeability is better than that of the insulating layer 1 without the cavity 12, so that the phenomena of the electromagnetic shielding film bulging, even cracking and the like can be effectively avoided.
Illustratively, the number of the cavities 12 is plural, and the plural cavities 12 are uniformly or non-uniformly distributed in the shielding layer 2.
The electromagnetic wave absorbing material 3 may be provided in the insulating layer 1 in another manner, for example: are directly dispersed in the shielding layer 2.
In the above embodiment, the electromagnetic wave absorbing material 3 is exemplarily in the form of particles, which can facilitate the electromagnetic wave absorbing material 3 to be disposed in the shielding layer 2. The granular electromagnetic wave absorbing material 3 may be in the shape of a sphere, a cluster, an ice, a stalactite, a tree, or the like, but is not particularly limited thereto. Of course, the electromagnetic wave absorbing material 3 may be in the form of a layer, a net, or the like (i.e., the shielding layer 2 is provided with a layer of the electromagnetic wave absorbing material 3, or is in the form of a net, and the electromagnetic wave absorbing structure is not limited in particular herein).
In the above embodiment, optionally, the electromagnetic wave absorbing material 3 has conductivity, and part or all of the electromagnetic wave absorbing material 3 is conductively connected to the shielding layer 2. Wherein, the conductivity of the electromagnetic wave absorption material 3 may be weaker than that of the shielding layer 2. Wherein, by disposing the electromagnetic wave absorbing material 3 with conductivity in the electromagnetic shielding film, on the one hand, the electromagnetic wave absorbing material 3 has the function of absorbing electromagnetic waves, which can absorb the electromagnetic waves reaching the insulating layer 1, so as to further ensure the normal operation of the circuit board; on the other hand, the electromagnetic wave absorbing material 3 also has a conductive function, and when the electromagnetic wave absorbing material 3 arranged in the insulating layer 1 is electrically connected with the shielding layer 2 (for example, by arranging a lead, or the electromagnetic wave absorbing material 3 in the insulating layer 1 in the through hole 11 or in the cavity 12 is partially exposed to contact with the shielding layer 2), it can cooperate with the shielding layer 2 to rapidly lead out the interference charges, so that the electromagnetic shielding film has a good shielding effect.
In the above embodiments, the electromagnetic wave absorbing material 3 is, for example, a conductive metal, a conductive sponge, a conductive plastic, a conductive rubber, or the like, and is not particularly limited herein.
In the above embodiment, the electromagnetic wave absorbing material 3 may also be composed of an adhesive and a wave absorbing medium. The wave-absorbing medium is composed of any one of a carbon-series wave-absorbing material, an iron-series wave-absorbing material, a ceramic-series wave-absorbing material and a composite wave-absorbing material. It should be noted that the carbon-based wave-absorbing material includes, but is not limited to, graphene, graphite, carbon black, carbon fiber, and carbon nanotube; the iron-based wave absorbing material comprises but is not limited to ferrite, a magnetic iron nano material, fe-based alloy micro powder and an iron-based amorphous material; the ceramic-series wave-absorbing material comprises but is not limited to silicon carbide; the composite wave-absorbing material comprises but is not limited to a composite material formed by blending reduced graphene oxide/tin dioxide nano composite wave-absorbing material, manganese zinc ferrite/polypyrrole composite material, three-dimensional silver-graphene hybrid foam/epoxy resin composite material, rG0/Fe304@ Si02 composite material, soft magnetic powder and high molecular plastic. In addition, the wave-absorbing medium can also be a conductive polymer, a chiral material, a plasma material, a porous hollow iron nanosphere, a self-skinning polyurethane lightweight material, a hollow sandwich microsphere metal sulfide and the like.
Illustratively, the electromagnetic wave absorbing material 3 has a conductivity of one tenth to one half of that of the shielding layer 2.
In the above embodiments, the thickness of the shielding layer 2 or the insulating layer 1 is, for example, 2 to 8 μm. That is, the thickness of the shielding layer 2 or the insulating layer 1 may be relatively thick (the thickness of the conventional whole electromagnetic shielding film is generally 7 to 8 μm, and the thickness of the shielding layer 2 is generally relatively thin), so that the electromagnetic shielding performance of the shielding layer 2 can be improved. It should be noted that, when the shielding layer 2 is provided with the through hole 11 or the cavity 12, etc. to have air permeability, the shielding layer 2 is thicker, which not only improves the electromagnetic shielding performance of the shielding layer 2, but also avoids the electromagnetic shielding film from bulging or even breaking. In addition, if the shielding layer 2 is provided to be thick, the electromagnetic wave absorbing material 3 can be provided in the shielding layer 2 to be larger, and the electromagnetic wave absorbing performance of the shielding layer 2 can be improved.
In order to ensure that the shielding layer 2 has good conductivity, the shielding layer 2 includes one or more of a metal shielding layer 2, a carbon nanotube shielding layer 2, a ferrite shielding layer 2, and a graphene shielding layer 2. Wherein the metal shielding layer 2 comprises a single metal shielding layer 2 and/or an alloy shielding layer 2; the single metal shielding layer 2 is made of any one of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold, and the alloy shielding layer 2 is made of any two or more of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold.
In addition, the shielding layer 2 in the drawings of the present embodiment may have a single-layer structure or a multi-layer structure. In addition, the shielding layer 2 of the present embodiment can be arranged in a grid shape, a foaming shape, etc. according to the requirements of actual production and application.
In addition, in order to further improve the electromagnetic wave absorption performance of the electromagnetic shielding film, the electromagnetic wave absorbing material 3 described above may be provided in the shielding layer 2. In addition, in order to improve the air permeability of the electromagnetic shielding film, the shielding layer 2 and the adhesive film layer 4 may be provided with a certain air permeability, for example, a hole is formed in the shielding layer 2 and the adhesive film layer 4, or a cavity 12 is provided.
In the above embodiment, for example, one of the structures of the adhesive film layer 4 is represented by: the adhesive layer 4 includes an adhesive layer containing conductive particles. The adhesive film layer 4 has an adhesive effect by making the adhesive film layer 4 include an adhesive layer containing conductive particles, so that the circuit board and the electromagnetic shielding film are tightly adhered, and the adhesive film layer 4 also has a conductive function, so that interfering electrons in the shielding layer 2 can be quickly introduced into the ground layer of the circuit board. The conductive particles can be mutually separated conductive particles or aggregated large-particle conductive particles; when the conductive particles are mutually separated, the area of electrical contact can be further increased, and the uniformity of the electrical contact is improved; and when the conductive particles are large agglomerated conductive particles, the piercing strength can be increased.
In the above embodiment, another structure of the adhesive film layer 4 is represented as follows: the adhesive layer 4 includes an adhesive layer containing no conductive particles. The adhesive film layer 4 has an adhesive effect by enabling the adhesive film layer 4 to include an adhesive layer without containing conductive particles, so that the circuit board and the electromagnetic shielding film are tightly adhered, and meanwhile, because the adhesive film layer 4 includes an adhesive layer without containing conductive particles, the insertion loss of the circuit board in the using process is reduced, the shielding efficiency is improved, and meanwhile, the bending property of the circuit board is improved. It should be understood that, when the glue film layer 4 does not have a conductive property, the connection manner of the shielding layer 2 and the circuit board ground layer may also be a connection manner through a wire or a conductor or other connection manners, which are not limited in this respect.
In addition, the thickness of the adhesive film layer 4 in this embodiment is 1 μm to 80 μm. The material used for the glue film layer 4 is selected from the following materials: modified epoxy resins, acrylic resins, modified rubbers, and modified thermoplastic polyimides. In addition, it should be noted that the outer surface of the adhesive film layer 4 may be a flat surface or a non-flat surface, which is not limited in this embodiment.
Referring to fig. 3 and 4, another embodiment of the present invention provides a circuit board, which includes a circuit board body 5 and the electromagnetic shielding film according to any of the above embodiments, wherein the electromagnetic shielding film is disposed on the circuit board body 5, and the shielding layer 2 of the electromagnetic shielding film is connected to a ground layer in the circuit board body 5. The adhesive film layer 4 is located between the circuit board body 5 and the shielding layer 2, and more specifically, the adhesive film layer 4 may be attached to the surface of the circuit board body 5.
In this embodiment, the type of the circuit board body 5 may be set according to actual use conditions; preferably, the circuit board body 5 in this embodiment is one of a flexible single-sided circuit board, a flexible double-sided circuit board, a flexible multilayer board, and a rigid-flex printed circuit board.
In addition, in the specific implementation, when the circuit board is applied to an electronic device, a free grounding film may be disposed, one surface of the free grounding film is electrically connected to a housing of the electronic device, and the other surface of the free grounding film is electrically connected to the electromagnetic shielding film, so that the interference charges accumulated in the electromagnetic shielding film are conducted out.
In this embodiment, the electromagnetic wave absorbing material 3 is disposed in the insulating layer 1 of the electromagnetic shielding film, so that the electromagnetic wave absorbing material 3 in the insulating layer 1 can absorb electromagnetic wave signals (including electromagnetic wave signals generated during high-frequency transmission of the circuit board), and thus the influence of the electromagnetic wave signals on the high-frequency transmission of the circuit board can be reduced or effectively avoided.
Another embodiment of the present invention provides a method for preparing an electromagnetic shielding film, which is suitable for preparing the electromagnetic shielding film according to any one of the above schemes, including the steps of:
s1, manufacturing and forming an insulating layer 1;
s2, arranging an electromagnetic wave absorption material 3 in the insulating layer 1;
s3, forming a shielding layer 2 on one surface of the insulating layer 1;
and S4, forming a glue film layer 4 on one surface, far away from the insulating layer 1, of the shielding layer 2.
In this embodiment, the electromagnetic wave absorbing material 3 is disposed in the insulating layer 1 of the electromagnetic shielding film, so that the electromagnetic wave absorbing material 3 in the insulating layer 1 can absorb electromagnetic wave signals (including electromagnetic wave signals generated during high-frequency transmission of the circuit board), and thus the influence of the electromagnetic wave signals on the high-frequency transmission of the circuit board can be reduced or effectively avoided.
In this embodiment, as an example, the step S2 includes:
s20, forming a through hole 11 in the insulating layer 1; the through hole 11 penetrates through two opposite surfaces of the insulating layer 1;
and S21, arranging the electromagnetic wave absorption material 3 in the through hole 11.
The electromagnetic wave absorbing material 3 is disposed in the through hole 11, and may be in the form of: the electromagnetic wave absorbing material 3 is placed in the through hole 11, and then the opening of the through hole 11 is sealed.
In the present embodiment, as another example, the step S2 includes:
s20', forming a cavity 12 in the insulating layer 1, and disposing an electromagnetic wave absorbing material 3 in the cavity 12.
The cavity 12 may be formed in the insulating layer 1 in the following manner: and forming a groove on the insulating layer 1, then placing an electromagnetic wave absorption material 3 in the groove, and finally covering a sealing layer on the shielding layer 2 to seal the groove to form the final insulating layer 1 with the cavity 12. Or may also be: directly opening a cavity 12 on the insulating layer 1 and leaving a cavity opening on the shielding layer 2, then placing an electromagnetic wave absorbing material 3 into the cavity 12 through the cavity opening, and finally sealing the cavity opening.
It should be noted that, the shielding layer 2 may be formed by chemical plating, PVD, CVD, evaporation plating, sputtering plating, electroplating, or a combination thereof.
In the above embodiment, for example, the step S4 includes:
forming an adhesive film layer 4 on a release film, and then pressing and transferring the adhesive film layer 4 to the one surface of the shielding layer 2; or the like, or, alternatively,
directly coating an adhesive film on the one surface of the shielding layer 2, thereby forming the adhesive film layer 4 on the one surface of the shielding layer 2.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and substitutions can be made without departing from the technical principle of the present invention, and these modifications and substitutions should also be regarded as the protection scope of the present invention.

Claims (13)

1. The electromagnetic shielding film is characterized by comprising an insulating layer, a shielding layer and an adhesive film layer which are arranged in a stacked mode, wherein the shielding layer is arranged between the insulating layer and the adhesive film layer; the shielding layer is connected with the circuit board stratum; an electromagnetic wave absorption material is arranged in the insulating layer; a cavity is arranged in the insulating layer, the electromagnetic wave absorbing material is arranged in the cavity, or a plurality of through holes are arranged on the insulating layer, each through hole penetrates through two opposite surfaces of the insulating layer, and the electromagnetic wave absorbing material is arranged in each through hole; the electromagnetic wave absorption material has conductivity, and part or all of the electromagnetic wave absorption material is in conductive connection with the shielding layer; wherein the electromagnetic wave absorbing material has a conductivity weaker than that of the shielding layer.
2. The electromagnetic shielding film of claim 1, wherein said two opposing surfaces are an upper surface and a lower surface of said insulating layer.
3. The electro-magnetic shielding film of claim 1, wherein the through-hole is a circular hole, a square hole, a polygonal hole, or a shaped hole.
4. The electro-magnetic shielding film of claim 1, wherein the plurality of through holes are uniformly or non-uniformly distributed on the insulating layer.
5. The electromagnetic shielding film according to claim 4, wherein the total open area of said plurality of through holes is 25-65% of the area of any one of said surfaces of said insulating layer.
6. The electromagnetic shielding film according to claim 4, wherein the mass of the insulating layer after the opening of the through-hole is 15 to 80% of the mass of the insulating layer before the opening of the through-hole.
7. The electromagnetic shielding film according to claim 1, wherein the number of the cavities is plural, and the plural cavities are uniformly or non-uniformly distributed in the insulating layer.
8. The electromagnetic shielding film according to claim 1, wherein the electromagnetic wave absorbing material is in a granular form.
9. The electro-magnetic shielding film of claim 1, wherein the electro-magnetic wave absorbing material is a conductive metal, a conductive sponge, a conductive plastic, or a conductive rubber.
10. The electro-magnetic shielding film of claim 1, wherein the thickness of the insulating layer or the shielding layer is 2-8 microns.
11. A wiring board comprising a wiring board body and the electromagnetic shielding film according to any one of claims 1 to 10, wherein the electromagnetic shielding film is provided on the wiring board body, and the shielding layer of the electromagnetic shielding film is connected to a ground layer in the wiring board body.
12. A method for preparing an electro-magnetic shielding film, which is suitable for preparing the electro-magnetic shielding film of any one of claims 1 to 10, comprising the steps of:
manufacturing and forming an insulating layer;
arranging an electromagnetic wave absorption material in the insulating layer;
forming a shielding layer on one side of the insulating layer;
and forming a film adhesive layer on one surface of the shielding layer far away from the insulating layer.
13. The method for preparing an electro-magnetic shielding film according to claim 12, wherein the disposing of the electro-magnetic wave absorption material in the insulating layer comprises:
forming a through hole in the insulating layer; the through hole penetrates through two opposite surfaces of the insulating layer;
arranging an electromagnetic wave absorption material in the through hole;
or, comprising:
and forming a cavity in the insulating layer, and arranging an electromagnetic wave absorption material in the cavity.
CN201911393431.8A 2019-12-30 2019-12-30 Electromagnetic shielding film, circuit board and preparation method of electromagnetic shielding film Active CN112351574B (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20160148487A (en) * 2015-05-18 2016-12-26 주식회사 이녹스 Excellent interlayer adhesive graphite sheet for composite sheet with EMI shield and heat radiation, Composite sheet with EMI shield and heat radiation containing the same and Manufacturing method thereof
CN207885101U (en) * 2017-09-15 2018-09-18 中山国安火炬科技发展有限公司 A kind of electromagnetic shielding film
CN108990403A (en) * 2018-08-13 2018-12-11 北京梦之墨科技有限公司 A kind of electromagnetic armouring structure
CN109937618A (en) * 2016-11-04 2019-06-25 麦克赛尔控股株式会社 Electro-magnetic wave absorption piece
CN212163811U (en) * 2019-12-30 2020-12-15 广州方邦电子股份有限公司 Electromagnetic shielding film and circuit board

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20160148487A (en) * 2015-05-18 2016-12-26 주식회사 이녹스 Excellent interlayer adhesive graphite sheet for composite sheet with EMI shield and heat radiation, Composite sheet with EMI shield and heat radiation containing the same and Manufacturing method thereof
CN109937618A (en) * 2016-11-04 2019-06-25 麦克赛尔控股株式会社 Electro-magnetic wave absorption piece
CN207885101U (en) * 2017-09-15 2018-09-18 中山国安火炬科技发展有限公司 A kind of electromagnetic shielding film
CN108990403A (en) * 2018-08-13 2018-12-11 北京梦之墨科技有限公司 A kind of electromagnetic armouring structure
CN212163811U (en) * 2019-12-30 2020-12-15 广州方邦电子股份有限公司 Electromagnetic shielding film and circuit board

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