阅读说明：本技术 电磁屏蔽膜、线路板及电磁屏蔽膜的制备方法 (Electromagnetic shielding film, circuit board and preparation method of electromagnetic shielding film ) 是由 苏陟 于 2018-07-27 设计创作，主要内容包括：本发明实施例提供了一种电磁屏蔽膜、线路板及电磁屏蔽膜的制备方法,其中,电磁屏蔽膜包括依次层叠设置的第一屏蔽层、导电胶层、第二屏蔽层和胶膜层,第一屏蔽层上设有贯穿其上下表面的第一通孔,第二屏蔽层上设有贯穿其上下表面的第二通孔。通过使第一屏蔽层、导电胶层、第二屏蔽层和胶膜层依次层叠设置,使得在第一屏蔽层和第二屏蔽层的配合下,电磁屏蔽膜能够两次反射高频干扰信号,从而实现了极高的屏蔽效能,适用于超高频及高速化传输。(The embodiment of the invention provides an electromagnetic shielding film, a circuit board and a preparation method of the electromagnetic shielding film, wherein the electromagnetic shielding film comprises a first shielding layer, a conductive adhesive layer, a second shielding layer and an adhesive film layer which are sequentially stacked, a first through hole penetrating through the upper surface and the lower surface of the first shielding layer is formed in the first shielding layer, and a second through hole penetrating through the upper surface and the lower surface of the second shielding layer is formed in the second shielding layer. Through making first shielding layer, conductive adhesive layer, second shielding layer and glued membrane layer stack gradually the setting for under the cooperation of first shielding layer and second shielding layer, the electromagnetic shield membrane can reflect high frequency interference signal twice, thereby has realized high shielding efficiency, is applicable to hyperfrequency and high-speed transmission.)

1. The utility model provides an electromagnetic shielding film, its characterized in that is including the first shielding layer, conductive adhesive layer, second shielding layer and the rete that stacks gradually the setting, be equipped with the first through-hole that runs through its upper and lower surface on the first shielding layer, be equipped with the second through-hole that runs through its upper and lower surface on the second shielding layer.

2. The electro-magnetic shielding film of claim 1, wherein the second shielding layer comprises a first surface in contact with the adhesive film layer, and the first surface is a flat surface; the adhesive film layer comprises an adhesion layer containing conductive particles.

3. The electromagnetic shielding film of claim 1, wherein the second shielding layer comprises a first surface in contact with the adhesive film layer, the first surface is a flat surface, and convex conductive particles are further formed on the first surface, and the conductive particles extend into the adhesive film layer.

4. The electro-magnetic shielding film of claim 3, wherein the conductor particles have a height of 0.1 μm to 30 μm.

5. The electromagnetic shielding film of claim 3, wherein the adhesive layer comprises an adhesive layer containing conductive particles; or the like, or, alternatively,

the adhesive film layer comprises an adhesion layer without conductive particles.

6. The electro-magnetic shielding film of claim 1, wherein the second shielding layer comprises a first surface in contact with the adhesive film layer, the first surface being a contoured non-planar surface.

7. The electromagnetic shielding film according to claim 6, wherein the first surface is further formed with convex conductor particles; the height of the conductor particles is 0.1-30 μm.

8. The electromagnetic shielding film according to claim 7, wherein the first surface comprises a plurality of protrusions, and the conductive particles are distributed on the protrusions in a concentrated manner.

9. The electromagnetic shielding film of claim 6, wherein the adhesive layer comprises an adhesive layer containing conductive particles; or the like, or, alternatively,

the adhesive film layer comprises an adhesion layer without conductive particles.

10. The electromagnetic shielding film of any of claims 1-9, wherein the first shielding layer and the second shielding layer each comprise one or more of a metal shielding layer, a carbon nanotube shielding layer, a ferrite shielding layer, and a graphene shielding layer.

11. The electromagnetic shielding film according to claim 10, wherein the metallic shielding layer comprises a single metallic shielding layer and/or an alloy shielding layer; the single metal shielding layer is made of any one of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold, and the alloy shielding layer is made of any two or more of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold.

12. The electro-magnetic shielding film of any one of claims 1-9, wherein the first through-hole has a cross-sectional area of 0.1 μm²-1mm²(ii) a And/or the cross-sectional area of the second through hole is 0.1 mu m²-1mm²。

13. The electromagnetic shielding film according to any one of claims 1 to 9, wherein each 1cm is²The number of the first through holes in the first shielding layer is 10-1000; and/or, per 1cm²The number of the second through holes in the second shielding layer is 10-1000.

14. The electromagnetic shielding film according to any one of claims 1 to 9, further comprising a protective film layer disposed on a side of the first shielding layer away from the conductive adhesive layer.

15. A wiring board comprising a printed wiring board and the electromagnetic shielding film of any one of claims 1 to 14, wherein the electromagnetic shielding film is laminated with the printed wiring board through an adhesive film layer thereof.

16. 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 14, comprising the steps of:

s1, forming a first shielding layer; the first shielding layer is provided with a first through hole penetrating through the upper surface and the lower surface of the first shielding layer;

s2, forming a conductive adhesive layer on one side of the first shielding layer;

s3, forming a second shielding layer on one side, far away from the first shielding layer, of the conductive adhesive layer; the second shielding layer is provided with a second through hole penetrating through the upper surface and the lower surface of the second shielding layer;

and S4, forming an adhesive film layer on one side of the second shielding layer far away from the conductive adhesive layer.

17. The method for preparing an electromagnetic shielding film according to claim 16, wherein in step S4, the step of forming a film layer on the side of the second shielding layer away from the conductive adhesive layer includes:

coating an adhesive film layer on a release film, and then transferring the adhesive film layer to one side of the second shielding layer far away from the conductive adhesive layer in a pressing manner, so that the adhesive film layer is formed on one side of the second shielding layer far away from the conductive adhesive layer; or

And directly coating an adhesive film layer on one side of the second shielding layer, which is far away from the conductive adhesive layer, so that the adhesive film layer is formed on one side of the second shielding layer, which is far away from the conductive adhesive layer.

Technical Field

The invention relates to the field of electronics, 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 circuit board is dominant in the flexible circuit board market, 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 the functions of communication equipment such as mobile phones, the internal components thereof are sharply and high frequency-accelerated, for example: the mobile phone functions are essential functions except for the original audio transmission function, furthermore, WLAN (Wireless Local Area network), GPS (Global Positioning System) and internet function are popular, and the integration of sensing components in the future makes the trend of rapid high-frequency and high-speed components more inevitable.

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, and then interference charges are guided into the circuit board stratum to realize shielding. However, the shielding effectiveness of the conventional shielding films is low due to factors such as the structure and characteristics of the shielding films themselves, and thus there is still a problem of electromagnetic interference in high-frequency and high-speed signal transmission.

Disclosure of Invention

The embodiment of the invention aims to provide an electromagnetic shielding film, a circuit board and a preparation method of the electromagnetic shielding film, which have higher shielding efficiency and are effectively applied to ultrahigh frequency and high-speed transmission.

In order to achieve the above object, an embodiment of the present invention provides an electromagnetic shielding film, which includes a first shielding layer, a conductive adhesive layer, a second shielding layer, and an adhesive layer, which are sequentially stacked, where the first shielding layer is provided with a first through hole penetrating through upper and lower surfaces of the first shielding layer, and the second shielding layer is provided with a second through hole penetrating through upper and lower surfaces of the second shielding layer.

As an improvement of the above scheme, the second shielding layer includes a first surface in contact with the adhesive film layer, and the first surface is a flat surface; the adhesive film layer comprises an adhesion layer containing conductive particles.

As an improvement of the above scheme, the second shielding layer includes a first surface in contact with the adhesive film layer, the first surface is a flat surface, and convex conductor particles are further formed on the first surface, and the conductor particles extend into the adhesive film layer.

As a modification of the above, the height of the conductor particles is 0.1 μm to 30 μm.

As an improvement of the above scheme, the adhesive film layer includes an adhesive layer containing conductive particles; or the adhesive film layer comprises an adhesion layer without conductive particles.

As an improvement of the above scheme, the second shielding layer includes a first surface in contact with the adhesive film layer, and the first surface is a wavy non-flat surface.

As a modification of the above, the first surface is further formed with convex conductor particles; the height of the conductor particles is 0.1-30 μm.

As an improvement of the above scheme, the first surface includes a plurality of protrusions, and the conductive particles are distributed on the protrusions in a concentrated manner.

As an improvement of the above scheme, the adhesive film layer includes an adhesive layer containing conductive particles; or the adhesive film layer comprises an adhesion layer without conductive particles.

As an improvement of the above scheme, the first shielding layer and the second shielding layer respectively include one or more of a metal shielding layer, a carbon nanotube shielding layer, a ferrite shielding layer, and a graphene shielding layer.

As a modification of the above, the metal shielding layer includes a single metal shielding layer and/or an alloy shielding layer; the single metal shielding layer is made of any one of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold, and the alloy shielding layer is made of any two or more of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold.

As a modification of the above, the first through-hole has a cross-sectional area of 0.1 μm²-1mm²(ii) a And/or the cross-sectional area of the second through hole is 0.1 mu m²-1mm²。

As an improvement of the above scheme, every 1cm²The number of the first through holes in the first shielding layer is 10-1000; and/or, per 1cm²The number of the second through holes in the second shielding layer is 10-1000.

As an improvement of the above scheme, the electromagnetic shielding film further comprises a protective film layer, and the protective film layer is arranged on one side, far away from the conductive adhesive layer, of the first shielding layer.

Compared with the prior art, the embodiment of the invention discloses an electromagnetic shielding film, wherein the first shielding layer and the second shielding layer are arranged at the same time, and the first shielding layer, the conductive adhesive layer, the second shielding layer and the adhesive film layer are sequentially stacked, so that the electromagnetic shielding film can reflect high-frequency interference signals twice, realizes extremely high shielding efficiency and is suitable for ultrahigh frequency and high-speed transmission; meanwhile, the conductive adhesive layer is arranged between the first shielding layer and the second shielding layer, so that the bending property of the electromagnetic shielding film is improved. In addition, through set up on the first shielding layer first through-hole is in simultaneously set up on the second shielding layer the second through-hole for under high temperature, volatile matter in the glued membrane layer can be followed first through-hole and second through-hole discharge have avoided effectively when high temperature volatile matter in the glued membrane layer is difficult to discharge and leads to the phenomenon of electromagnetic shielding membrane bubbling layering, thereby has avoided peeling off between the stratum of electromagnetic shielding membrane and circuit board, and then has ensured the good ground connection of electromagnetic shielding membrane, and will disturb electric charge and derive.

Meanwhile, due to the arrangement of the first through hole and the second through hole, in the laminating process, the conductive adhesive layer positioned between the first shielding layer and the second shielding layer extends into and is connected to the first through hole and the second through hole, and the adhesive film layer extends into and is connected to the second through hole, so that the first shielding layer, the conductive adhesive layer, the second shielding layer and the adhesive film layer are closely connected together, and the peeling strength of the electromagnetic shielding film is greatly improved.

The embodiment of the invention discloses a circuit board which comprises a printed circuit board and any one of the electromagnetic shielding films, wherein the electromagnetic shielding film is laminated with the printed circuit board through an adhesive film layer of the electromagnetic shielding film.

Compared with the prior art, the embodiment of the invention discloses a circuit board, which comprises a printed circuit board and any one of the electromagnetic shielding films, wherein the electromagnetic shielding film is laminated with the printed circuit board through an adhesive film layer of the electromagnetic shielding film, so that the circuit board can reflect high-frequency interference signals twice through the electromagnetic shielding film, extremely high shielding efficiency is realized, and the electromagnetic shielding film is suitable for ultrahigh frequency and high-speed transmission; meanwhile, the conductive adhesive layer is arranged between the first shielding layer and the second shielding layer, so that the bending property of the electromagnetic shielding film is improved. In addition, through set up on the first shielding layer first through-hole is in simultaneously set up on the second shielding layer the second through-hole for under high temperature, volatile matter in the glued membrane layer can be followed first through-hole and second through-hole discharge, avoided effectively when high temperature volatile matter in the glued membrane layer is difficult to discharge and leads to the phenomenon of shielding film foaming layering, thereby has avoided peeling off between the stratum of electromagnetic shielding film and circuit board, and then has ensured the good ground connection of electromagnetic shielding film, and derive the interference charge.

Meanwhile, due to the arrangement of the first through hole and the second through hole, in the laminating process, the conductive adhesive layer positioned between the first shielding layer and the second shielding layer extends into and is connected to the first through hole and the second through hole, and the adhesive film layer extends into and is connected to the second through hole, so that the first shielding layer, the conductive adhesive layer, the second shielding layer and the adhesive film layer are closely connected together, and the peeling strength of the electromagnetic shielding film is greatly improved.

The embodiment of the invention also correspondingly provides a preparation method of the electromagnetic shielding film, which is suitable for preparing any one of the electromagnetic shielding films, and comprises the following steps:

s1, forming a first shielding layer; the first shielding layer is provided with a first through hole penetrating through the upper surface and the lower surface of the first shielding layer;

s2, forming a conductive adhesive layer on one side of the first shielding layer;

s3, forming a second shielding layer on one side, far away from the first shielding layer, of the conductive adhesive layer; the second shielding layer is provided with a second through hole penetrating through the upper surface and the lower surface of the second shielding layer;

and S4, forming an adhesive film layer on one side of the second shielding layer far away from the conductive adhesive layer.

As an improvement of the above scheme, in step S4, the forming a glue film layer on the side of the second shielding layer away from the conductive glue layer specifically includes:

coating an adhesive film layer on a release film, and then transferring the adhesive film layer to one side of the second shielding layer far away from the conductive adhesive layer in a pressing manner, so that the adhesive film layer is formed on one side of the second shielding layer far away from the conductive adhesive layer; or

And directly coating an adhesive film layer on one side of the second shielding layer, which is far away from the conductive adhesive layer, so that the adhesive film layer is formed on one side of the second shielding layer, which is far away from the conductive adhesive layer.

Compared with the prior art, the preparation method of the electromagnetic shielding film provided by the embodiment of the invention has the advantages that the first shielding layer is formed, and the conductive adhesive layer, the second shielding layer and the adhesive film layer are sequentially formed on one side of the first shielding layer, so that the electromagnetic shielding film can reflect high-frequency interference signals twice, the extremely high shielding effect is realized, and the electromagnetic shielding film is suitable for ultrahigh frequency and high-speed transmission; meanwhile, the conductive adhesive layer is arranged between the first shielding layer and the second shielding layer, so that the bending property of the electromagnetic shielding film is improved. In addition, through set up first through-hole on first shielding layer, set up the second through-hole on the second shielding layer simultaneously for under high temperature, volatile matter in the glued membrane layer can be followed first through-hole and second through-hole discharge have avoided effectively when high temperature volatile matter is difficult to discharge and lead to the phenomenon of shielding film foaming layering in the glued membrane layer, thereby has avoided peeling off between the stratum of electromagnetic shielding film and circuit board, and then has ensured the good ground connection of electromagnetic shielding film, and will disturb electric charge and derive.

Meanwhile, due to the arrangement of the first through hole and the second through hole, in the laminating process, the conductive adhesive layer positioned between the first shielding layer and the second shielding layer extends into and is connected to the first through hole and the second through hole, and the adhesive film layer extends into and is connected to the second through hole, so that the first shielding layer, the conductive adhesive layer, the second shielding layer and the adhesive film layer are closely connected together, and the peeling strength of the electromagnetic shielding film is greatly improved.

Drawings

Fig. 1 is a schematic view of an angle structure of an electromagnetic shielding film in embodiment 1 of the present invention;

fig. 2 is a schematic view of another angle structure of the electromagnetic shielding film in embodiment 1 of the present invention;

fig. 3 is a schematic structural view of an electromagnetic shielding film in embodiment 2 of the present invention;

fig. 4 is a schematic structural view of an electromagnetic shielding film in embodiment 3 of the present invention;

fig. 5 is a schematic structural view of an electromagnetic shielding film in embodiment 4 of the present invention;

fig. 6 is a schematic structural view of a wiring board in embodiment 5 of the present invention;

fig. 7 is a schematic flow chart of a method for manufacturing an electromagnetic shielding film in embodiment 6 of the present invention.

Wherein, 1, a first shielding layer; 11. a first through hole; 2. a conductive adhesive layer; 3. a second shielding layer; 31. a second through hole; 32. a conductive particle; 33. a first surface; 331. a convex portion; 332. a recess; 34. a second surface; 4. a glue film layer; 5. a protective film layer; 6. a printed wiring board.

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 derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Fig. 1 is a schematic view of an angle structure of the electromagnetic shielding film according to embodiment 1 of the present invention;

fig. 2 is a schematic structural view of another angle of the electromagnetic shielding film provided in embodiment 1 of the present invention;

referring to fig. 1 and 2, the electromagnetic shielding film includes a first shielding layer 1, a conductive adhesive layer 2, a second shielding layer 3 and an adhesive film layer 4, which are stacked in sequence, wherein a first through hole 11 penetrating through the upper and lower surfaces of the first shielding layer 1 is provided, and a second through hole 31 penetrating through the upper and lower surfaces of the second shielding layer 3 is provided.

In the embodiment of the invention, the first shielding layer 1 and the second shielding layer 3 are arranged at the same time, and the first shielding layer 1, the conductive adhesive layer 2, the second shielding layer 3 and the adhesive film layer 4 are sequentially stacked, so that the electromagnetic shielding film can reflect high-frequency interference signals twice, extremely high shielding efficiency is realized, and the electromagnetic shielding film is suitable for ultrahigh frequency and high-speed transmission. Meanwhile, the conductive adhesive layer 2 is arranged between the first shielding layer 1 and the second shielding layer 3, so that the bending property of the electromagnetic shielding film is improved; in addition, through set up on the first shielding layer 1 first through-hole 11 is in simultaneously set up on the second shielding layer 3 second through-hole 31 for at high temperature, volatile matter in the glued membrane layer 4 can be followed first through-hole 11 and second through-hole 31 are discharged, have avoided effectively when high temperature volatile matter in the glued membrane layer 4 is difficult to discharge and leads to the phenomenon of shielding film foaming layering, thereby has avoided peeling off between the stratum of electromagnetic shielding film and circuit board, and then has ensured the good ground connection of electromagnetic shielding film to derive the interference electric charge.

Meanwhile, due to the arrangement of the first through hole 11 and the second through hole 31, in the process of pressing, the part of the conductive adhesive layer 2 located between the first shielding layer 1 and the second shielding layer 3 extends into and is connected to the first through hole 11 and the second through hole 31, and the part of the adhesive layer 4 extends into and is connected to the second through hole 31, so that the first shielding layer 1, the conductive adhesive layer 2, the second shielding layer 3 and the adhesive layer 4 are tightly connected together, and the peeling strength of the electromagnetic shielding film is greatly improved.

In the embodiment of the present invention, the second shielding layer 3 includes a first surface 33 in contact with the adhesive film layer 4, and the first surface 33 is a flat surface; the adhesive layer 4 includes an adhesive layer containing conductive particles. When the first surface 33 is a flat surface, the adhesive layer 2 includes an adhesion layer containing conductive particles, so that the adhesive layer 2 has an adhesion effect to tightly adhere the wiring board and the electromagnetic shielding film, and the adhesive layer 2 also has a conductive function, which is matched with the first shielding layer 1, the conductive adhesive layer 2 and the second shielding layer 3 to rapidly introduce interference electrons into the ground layer of the wiring 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 addition, the second shielding layer 3 further includes a second surface 34 opposite to the first surface 33, and the second surface 34 is in contact with the conductive adhesive layer 2. The second surface 34 may be any surface shape, such as a flat surface as shown in FIG. 1, an uneven surface with undulations, or other rough surface. The drawings of the present invention only illustrate the second surface 34 as a flat surface, and any other shape of the second surface 34 is within the scope of the present invention.

In the embodiment of the present invention, the first shielding layer 1 includes a third surface and a fourth surface that are oppositely disposed, and the third surface is in contact with the conductive adhesive layer; the fourth surface is in contact with the protective film layer. The third surface and the fourth surface may be surfaces of any shape, for example, flat surfaces as shown in fig. 1, uneven surfaces with an undulated shape, or other rough surfaces; in addition, the third surface and the fourth surface may be regular surfaces or irregular surfaces. The drawings of the present invention are only illustrated by the third surface and the fourth surface being flat surfaces, and any other shapes are within the scope of the present invention.

In the embodiment of the present invention, it is preferable that the cross-sectional area of the first through-hole 11 is 0.1 μm²-1 mm; and/or the cross-sectional area of the second through-hole 31 is 0.1 μm²-1 mm. By making the area of the first through-hole 11 preferably 0.1 μm²-1mm²The cross-sectional area of the second through-hole 31 is preferably set to 0.1 μm²1mm to ensure that, at high temperature, the volatiles of the adhesive film layer 4 can escape through the first and second through holes 11, 31 which are large enough to avoid being trapped inAnd volatile matters in the adhesive film layer are difficult to discharge at high temperature, so that the shielding film is foamed and layered, and good grounding of the electromagnetic shielding film is ensured, so that interference charges can be led out.

Further, preferably, in the present embodiment, every 1cm²The number of the first through holes 11 in the first shielding layer 1 is 10-1000; and/or, per 1cm²The number of the second through holes 31 in the second shielding layer 3 is 10 to 1000. By mixing each 1cm²The number of the first through holes 11 in the first shielding layer 1 is set to 10-1000, and each 1cm²The number of the second through holes 31 in the second shielding layer 3 is set to be 10-1000, so that the volatile matters in the adhesive film layer 4 can be discharged through enough first through holes 11 and second through holes 31 at high temperature, the phenomenon that the shielding film is foamed and layered due to the fact that the volatile matters in the adhesive film layer are difficult to discharge at high temperature is further avoided, good grounding of the electromagnetic shielding film is further ensured, and the interference charges can be further led out.

In the embodiment of the present invention, the first through holes 11 may be regularly or irregularly distributed on the first shielding layer 1; wherein, the first through holes 11 are regularly distributed on the first shielding layer 1, which means that the shapes of the first through holes 11 are the same and are uniformly distributed on the first shielding layer 1; the first through holes 11 are irregularly distributed on the first shielding layer 1, which means that the shapes of the first through holes 11 are different and are irregularly distributed on the first shielding layer 1. Preferably, the first through holes 11 have the same shape, and the first through holes 11 are uniformly distributed on the first shielding layer 1. In addition, the first through hole 11 may be a circular through hole, and may also be a through hole of any other shape, and the drawings of the present invention only illustrate that the first through hole 11 is a circular through hole, but the first through hole 11 of any other shape is within the scope of the present invention.

In the embodiment of the present invention, the second through holes 31 may be regularly or irregularly distributed on the second shielding layer 3; wherein, the second through holes 31 are regularly distributed on the second shielding layer 3, which means that the shapes of the second through holes 31 are the same and are uniformly distributed on the second shielding layer 3; the second through holes 31 are irregularly distributed on the second shielding layer 3, which means that the shapes of the second through holes 31 are different and are irregularly distributed on the second shielding layer 3. Preferably, the shape of each second through hole 11 is the same, and each second through hole 31 is uniformly distributed on the second shielding layer 3. In addition, the second through hole 31 may be a circular through hole, and may also be a through hole of any other shape, and the drawings of the present invention only illustrate that the second through hole 31 is a circular through hole, but the second through hole 31 of any other shape is within the protection scope of the present invention.

In the embodiment of the present invention, the thickness of the first shielding layer 1 is 0.1 μm to 45 μm; and/or the thickness of the second shielding layer 3 is 0.1-45 μm. It can be understood that, in order to ensure that the first shielding layer 1 and the second shielding layer 3 have good electrical conductivity, the first shielding layer 1 and the second shielding layer 2 each include one or more of a metal shielding layer, a carbon nanotube shielding layer, a ferrite shielding layer, and a graphene shielding layer. In addition, the metal shielding layer comprises a single metal shielding layer and/or an alloy shielding layer; the single metal shielding layer is made of any one of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold, and the alloy shielding layer is made of any two or more of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold.

In the embodiment of the present invention, it should be noted that, in the drawings of the present embodiment, both the first shielding layer 1 and the second shielding layer 3 may have a single-layer structure, or may have a multi-layer structure. In addition, the first shielding layer 1 and the second shielding layer 2 of the present embodiment can be provided in a grid shape, a foaming shape, etc. according to the requirements of actual production and application.

In the embodiment of the present invention, the thickness of the adhesive film layer 4 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, the outer surface of the adhesive film layer 4 may be a flat surface without undulation, or may be a non-flat surface with gentle undulation.

In the embodiment of the present invention, in order to protect the first shielding layer 1, in this embodiment, the electromagnetic shielding film further includes a protection film layer 5, and the protection film layer 5 is disposed on a side of the first shielding layer 1 away from the conductive adhesive layer 2. The protective film layer 5 plays a role in protection, so that the first shielding layer 1 is prevented from being scratched and damaged in the using process, and the high shielding effectiveness of the first shielding layer 1 is maintained. The protective film layer 5 comprises a PPS film layer, a PEN film layer, a polyester film layer, a polyimide film layer, a film layer formed after epoxy resin ink is cured, a film layer formed after polyurethane ink is cured, a film layer formed after modified acrylic resin is cured or a film layer formed after polyimide resin is cured.

In the embodiment of the present invention, it should be noted that the electromagnetic shielding film may be a repetitive multilayer structure; specifically, the first shielding layer 1, the conductive adhesive layer 2 and the second shielding layer 3 which are sequentially stacked are used as the electromagnetic shielding film body, the electromagnetic shielding film can be a plurality of sequentially stacked electromagnetic shielding film bodies, and is multiple, one side of the whole formed by the electromagnetic shielding film body is provided with the adhesive film layer 4, the other side is provided with the protective film layer 5.

Fig. 3 is a schematic structural view of the electromagnetic shielding film according to embodiment 2 of the present invention;

as shown in fig. 3, the difference between the electromagnetic shielding film in this embodiment and embodiment 1 is that the second shielding layer 3 includes a first surface 33 contacting with the adhesive film layer 4, the first surface 33 is a flat surface, and convex conductor particles 32 are further formed on the first surface 33, and the conductor particles 32 protrude into the adhesive film layer 4. When the first surface 33 of the second shielding layer 3, which is in contact with the adhesive film layer 4, is a flat surface, the conductor particles 32 are further formed on the first surface 33, and the conductor particles 32 extend into the adhesive film layer 4, so that the adhesive film layer 4 can be pierced through by the conductor particles 32 in the pressing process, and interference charges are ensured to be normally led out under the cooperation of the first shielding layer 1, the conductive adhesive layer 2 and the second shielding layer 3, so as to ensure that the electromagnetic shielding film has extremely high shielding effectiveness; in addition, the electromagnetic shielding film effectively avoids charge accumulation to generate eddy current loss, thereby reducing the insertion loss in the use process and being suitable for ultrahigh frequency and high-speed transmission.

In a specific implementation, as shown in fig. 3, the second shielding layer 3 may be formed first, and then the conductive particles 32 may be formed on the first surface 33 of the second shielding layer 3 through another process. Of course, the second shield layer 3 and the conductor particles 32 may be an integral structure formed by a one-time molding process.

In the embodiment of the present invention, the conductor particles 32 may be spaced from the outer surface of the adhesive film layer 4, and may also contact with the outer surface of the adhesive film layer 4 or extend out of the outer surface of the adhesive film layer 4.

In the embodiment of the present invention, in order to further ensure that the second shielding layer 3 can smoothly penetrate the adhesive film layer 4, the height of the conductor particles 32 is preferably 0.1 μm to 30 μm.

In an embodiment of the present invention, the conductor particles 32 include one or more of metal particles, carbon nanotube particles, and ferrite particles. Further, the metal particles include single metal particles and/or alloy particles; the single metal particles are made of any one of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold, and the alloy particles are made of any two or more of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold. The conductive particles 32 may be the same as or different from the material of the second shielding layer 3.

In the embodiment of the present invention, it should be noted that the shape of the conductor particles 32 shown in fig. 3 is only an example, and the conductor particles 32 may also be in other shapes such as cluster, ice, stalactite, and dendritic shapes due to differences in process means and parameters. The conductive particles 32 in the present invention are not limited to the shapes shown in the drawings and described above, and any conductive particles having piercing and conductive functions are within the scope of the present invention.

In the embodiment of the present invention, one of the structures of the adhesive film layer 4 is specifically represented as follows: the adhesive layer 4 includes an adhesive layer containing conductive particles. The adhesive film layer 4 has an adhesive function by including an adhesive layer containing conductive particles, so that the wiring board and the electromagnetic shielding film are tightly adhered, and the adhesive film layer 4 also has a conductive function, and is matched with the first shielding layer 1, the conductive adhesive layer 2 and the second shielding layer 3 to rapidly guide interference electrons into a ground layer of the wiring 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 embodiment of the present invention, another structure of the adhesive film layer 4 is specifically 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 making the adhesive film layer 4 include an adhesive layer containing no conductive particles, so that the wiring board and the electromagnetic shielding film are tightly adhered, and meanwhile, because the adhesive film layer 4 contains no conductive particles, the insertion loss of the wiring board in the use process is reduced, the shielding efficiency is improved, and the bending property of the wiring board is improved.

In the embodiment of the present invention, it should be noted that the electromagnetic shielding film may be a repetitive multilayer structure; specifically, a first shielding layer 1, a conductive adhesive layer 2 and a second shielding layer 3 which are sequentially stacked are taken as an electromagnetic shielding film body, the electromagnetic shielding film can be composed of a plurality of sequentially stacked electromagnetic shielding film bodies, one end of a whole formed by the plurality of electromagnetic shielding film bodies is provided with the adhesive film layer 4, and the other end is provided with the protective film layer 5; the first surface 33 of the second shielding layer 3 contacting the adhesive film layer 4 is a flat surface, and convex conductor particles 32 are further formed on the first surface 33, and the conductor particles 32 extend into the adhesive film layer 4. In addition, other structures and working principles of the electromagnetic shielding film of this embodiment are the same as those of embodiment 1, and are not further described herein.

Fig. 4 is a schematic structural view of the electromagnetic shielding film according to embodiment 3 of the present invention;

as shown in fig. 4, the difference between the electromagnetic shielding film in this embodiment and embodiment 1 is that the second shielding layer 3 includes a first surface 33 in contact with the adhesive film layer 4, and the first surface 33 is an undulating non-flat surface. When the first surface 33 of the second shielding layer 3 contacting the adhesive film layer 4 is an uneven surface, the uneven surface of the second shielding layer 3 can ensure that the second shielding layer 3 smoothly pierces through the adhesive film layer 4 in the pressing process, and further ensure that interference charges are normally led out under the cooperation of the first shielding layer 1, the conductive adhesive layer 2 and the second shielding layer 3, so as to ensure that the electromagnetic shielding film has extremely high shielding effectiveness; in addition, the electromagnetic shielding film effectively avoids charge accumulation to generate eddy current loss, so that the insertion loss in the use process is reduced, and the electromagnetic shielding film is suitable for ultrahigh frequency transmission.

In the embodiment of the present invention, the first surface 33 is a non-flat surface, wherein the non-flat surface is a regular non-flat surface or an irregular non-flat surface. Specifically, when the uneven surface is a regular uneven surface, the uneven surface is a structure with periodic fluctuation, and the amplitude of the fluctuation and the interval of the fluctuation on the uneven surface are the same; when the non-flat surface is an irregular non-flat surface, the non-flat surface is a structure with non-periodic fluctuation, and the amplitude of the fluctuation and the interval of the fluctuation on the non-flat surface are different.

In the embodiment of the present invention, one of the structures of the adhesive film layer 4 is specifically represented as follows: the adhesive layer 4 includes an adhesive layer containing conductive particles. The adhesive film layer 4 has an adhesive function by including an adhesive layer containing conductive particles, so that the wiring board and the electromagnetic shielding film are tightly adhered, and the adhesive film layer 4 also has a conductive function, and is matched with the first shielding layer 1, the conductive adhesive layer 2 and the second shielding layer 3 to rapidly guide interference electrons into a ground layer of the wiring 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 embodiment of the present invention, another structure of the adhesive film layer 4 is specifically 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 making the adhesive film layer 4 include an adhesive layer containing no conductive particles, so that the wiring board and the electromagnetic shielding film are tightly adhered, and meanwhile, because the adhesive film layer 4 contains no conductive particles, the insertion loss of the wiring board in the use process is reduced, the shielding efficiency is improved, and the bending property of the wiring board is improved.

In the embodiment of the present invention, it should be noted that the electromagnetic shielding film may be a repetitive multilayer structure; specifically, a first shielding layer 1, a conductive adhesive layer 2 and a second shielding layer 3 which are sequentially stacked are taken as an electromagnetic shielding film body, the electromagnetic shielding film can be composed of a plurality of sequentially stacked electromagnetic shielding film bodies, one end of a whole formed by the plurality of electromagnetic shielding film bodies is provided with the adhesive film layer 4, and the other end is provided with the protective film layer 5; the first surface 33 of the second shielding layer 3 in contact with the adhesive film layer 4 is an undulating, non-flat surface. In addition, other structures and working principles of the electromagnetic shielding film of this embodiment are the same as those of embodiment 1, and are not further described herein.

Fig. 5 is a schematic structural view of an electromagnetic shielding film provided in embodiment 4 of the present invention;

as shown in fig. 5, the difference between the electromagnetic shielding film in this embodiment and embodiment 1 is that the second shielding layer 3 includes a first surface 33 in contact with the adhesive film layer 4, the first surface 33 is an undulating non-flat surface, and the first surface 33 is further formed with convex conductor particles 32. When the first surface 33 of the second shielding layer 3 contacting the adhesive film layer 4 is a non-flat surface, the conductor particles 32 are further formed on the first surface 33, so that the conductor particles 32 can ensure that the second shielding layer 3 smoothly pierces through the adhesive film layer 4 in the pressing process, and further ensure that interference charges are normally led out under the cooperation of the first shielding layer 1, the conductive adhesive layer 2 and the second shielding layer 3, so as to ensure that the electromagnetic shielding film has extremely high shielding effectiveness; in addition, the electromagnetic shielding film effectively avoids charge accumulation to generate eddy current loss, thereby reducing the insertion loss in the use process and being suitable for ultrahigh frequency and high-speed transmission.

In a specific implementation, as shown in fig. 5, the second shielding layer 3 may be formed first, and then the conductive particles 32 may be formed on the first surface 33 of the second shielding layer 3 through another process. Of course, the second shield layer 3 and the conductor particles 32 may be an integral structure formed by a one-time molding process.

In the embodiment of the present invention, the first surface 33 is a non-flat surface, wherein the non-flat surface is a regular non-flat surface or an irregular non-flat surface. Specifically, when the uneven surface is a regular uneven surface, the uneven surface is a structure with periodic fluctuation, and the amplitude of the fluctuation and the interval of the fluctuation on the uneven surface are the same; when the non-flat surface is an irregular non-flat surface, the non-flat surface is a structure with non-periodic fluctuation, and the amplitude of the fluctuation and the interval of the fluctuation on the non-flat surface are different.

In the embodiment of the present invention, the first surface includes a plurality of protrusions 331 and recesses 332, and the conductive particles 32 are preferably distributed on the protrusions 331 in a concentrated manner, so that the second shielding layer 3 can more easily pierce through the adhesive film layer 4 during the pressing process, thereby achieving reliable connection inside the circuit board.

Based on the above structure, since the first surface 33 of the second shielding layer 3 is a wavy non-flat surface, the glue film layer 4 will extrude the glue on the conductive particles 32 on the convex portions 331 of the first surface 33 into the concave portions 332 of the first surface 21 during the pressing process, thereby avoiding the phenomenon of board explosion due to small glue capacity; meanwhile, the conductor particles 32 with a certain height are formed on the fluctuant non-flat surface, so that the second shielding layer 3 can be ensured to smoothly pierce the adhesive film layer 4 in the pressing process, and the practicability is high.

In the embodiment of the present invention, in order to further ensure that the second shielding layer 3 can smoothly penetrate the adhesive film layer 4, the height of the conductor particles 32 is preferably 0.1 μm to 30 μm.

Preferably, the undulation degree of the first surface 33 (i.e., the distance between the highest point and the lowest point of the first surface) is 0.1 μm to 30 μm, and setting the undulation degree of the first surface 33 within the above range can enhance the piercing function of the second shielding layer 3, ensuring that the interference charges can be conducted out.

Preferably, the thickness of the adhesive film layer 4 and the sum of the undulation degree of the first surface 33 and the height of the conductor particles 32 satisfy a proportional relationship of 0.5-2, so as to ensure sufficient piercing strength and glue containing amount, which is embodied as follows: on the one hand, the thickness of the adhesive film layer 4 is prevented from being too small relative to the sum of the degree of undulation of the first surface 33 and the height of the conductor particles 32, so that the adhesive capacity is insufficient and the plate bursting phenomenon is caused, and on the other hand, the thickness of the adhesive film layer 4 is prevented from being too small relative to the sum of the degree of undulation of the first surface 33 and the height of the conductor particles 32, so that the piercing strength is insufficient.

In the embodiment of the present invention, the conductor particles 32 may be spaced from the outer surface of the adhesive film layer 4, and may also contact with the outer surface of the adhesive film layer 4 or extend out of the outer surface of the adhesive film layer 4.

In an embodiment of the present invention, the conductor particles 32 include one or more of metal particles, carbon nanotube particles, and ferrite particles. Further, the metal particles include single metal particles and/or alloy particles; the single metal particles are made of any one of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold, and the alloy particles are made of any two or more of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold. The conductive particles 32 may be the same as or different from the material of the second shielding layer 3.

In the embodiment of the present invention, it should be noted that the shape of the conductor particles 32 as shown in fig. 5 is only an example, and the conductor particles 32 may also be in other shapes such as cluster, ice, stalactite, and dendritic shapes due to differences in process means and parameters. The conductive particles 32 in the present invention are not limited to the shapes shown in the drawings and described above, and any conductive particles having piercing and conductive functions are within the scope of the present invention.

In the embodiment of the present invention, one of the structures of the adhesive film layer 4 is specifically represented as follows: the adhesive layer 4 includes an adhesive layer containing conductive particles. The adhesive film layer 4 has an adhesive function by including an adhesive layer containing conductive particles, so that the wiring board and the electromagnetic shielding film are tightly adhered, and the adhesive film layer 4 also has a conductive function, and is matched with the first shielding layer 1, the conductive adhesive layer 2 and the second shielding layer 3 to rapidly guide interference electrons into a ground layer of the wiring 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 embodiment of the present invention, another structure of the adhesive film layer 4 is specifically 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 making the adhesive film layer 4 include an adhesive layer containing no conductive particles, so that the wiring board and the electromagnetic shielding film are tightly adhered, and meanwhile, because the adhesive film layer 4 contains no conductive particles, the insertion loss of the wiring board in the use process is reduced, the shielding efficiency is improved, and meanwhile, the bending property of the wiring board is improved.

In the embodiment of the present invention, it should be noted that the electromagnetic shielding film may be a repetitive multilayer structure; specifically, a first shielding layer 1, a conductive adhesive layer 2 and a second shielding layer 3 which are sequentially stacked are taken as an electromagnetic shielding film body, the electromagnetic shielding film can be composed of a plurality of sequentially stacked electromagnetic shielding film bodies, one side of a whole formed by the plurality of electromagnetic shielding film bodies is provided with the adhesive film layer 4, and the other side is provided with the protective film layer 5; the first surface 33 of the second shielding layer 3 contacting the adhesive film layer 4 is an uneven surface, and the first surface 33 is further formed with convex conductor particles 32. In addition, other structures and working principles of the electromagnetic shielding film of this embodiment are the same as those of embodiment 1, and are not further described herein.

Fig. 6 is a schematic structural diagram of a circuit board provided in embodiment 5 of the present invention;

as shown in fig. 6, an embodiment of the present invention further provides a circuit board correspondingly, including a printed circuit board 6 and the electromagnetic shielding film described in embodiment 1, where the electromagnetic shielding film is laminated with the printed circuit board 6 through an adhesive film layer 4 of the electromagnetic shielding film.

In this embodiment, reference may be made to the description of embodiment 1 above for implementation of the electromagnetic shielding film, and details are not repeated here.

Preferably, the printed circuit board 6 is one of a flexible single-sided board, a flexible double-sided board, a flexible multilayer board, and a rigid-flex printed board.

In the embodiment of the invention, with the structure, after the electromagnetic shielding film is laminated with the printed circuit board 6 through the adhesive film layer 4, the circuit board can reflect high-frequency interference signals twice through the electromagnetic shielding film, so that extremely high shielding efficiency is realized, and the electromagnetic shielding film is suitable for ultrahigh frequency and high-speed transmission; meanwhile, the conductive adhesive layer 2 is arranged between the first shielding layer 1 and the second shielding layer 3 of the electromagnetic shielding film, so that the bending property of the electromagnetic shielding film is increased. In addition, through set up on the first shielding layer 1 first through-hole 11 is in simultaneously set up on the second shielding layer 3 second through-hole 31 makes under high temperature, volatile matter in the glued membrane layer can be followed first through-hole 11 and second through-hole 31 are discharged, have avoided effectively when high temperature volatile matter is difficult to discharge and lead to the phenomenon of electromagnetic shielding membrane bubbling layering in the glued membrane layer 4 to peel off between the stratum of electromagnetic shielding membrane and circuit board has been avoided, and then has ensured the good ground connection of electromagnetic shielding membrane, and will disturb electric charge and derive.

Meanwhile, due to the arrangement of the first through hole 11 and the second through hole 31, in the process of pressing, the part of the conductive adhesive layer 2 located between the first shielding layer 1 and the second shielding layer 3 extends into and is connected to the first through hole 11 and the second through hole 31, and the part of the adhesive layer 4 extends into and is connected to the second through hole 31, so that the first shielding layer 1, the conductive adhesive layer 2, the second shielding layer 3 and the adhesive layer 4 are tightly connected together, and the peeling strength of the electromagnetic shielding film is greatly improved. In addition, it should be noted that, in the circuit board of this embodiment, the electromagnetic shielding film of embodiment 1 adopted in the structure of the circuit board may be replaced with the electromagnetic shielding film of any one of embodiments 2 to 4, which is not described herein again.

Referring to fig. 7, a schematic flow chart of a method for preparing an electromagnetic shielding film according to embodiment 6 of the present invention is provided;

as shown in fig. 7, the method is suitable for preparing the electromagnetic shielding film according to embodiment 1, and includes the steps of:

s1, forming a first shielding layer; the first shielding layer is provided with a first through hole penetrating through the upper surface and the lower surface of the first shielding layer;

wherein the first shield layer is formed in step S1 by:

forming a protective film layer on a carrier film, the first shielding layer being formed on one side of the protective film layer; or the like, or, alternatively,

the method comprises the steps of forming a peelable layer on a carrier film, forming the first shielding layer on the surface of the peelable layer, and peeling off the carrier film layer after forming a protective film layer on the side of the first shielding layer away from the peelable layer.

In the embodiment of the present invention, the first through-hole is formed to have a cross-sectional area of 0.1 μm²-1mm²(ii) a Every 1cm²The first mentionedThe number of the first through holes in the two shielding layers is 10-1000.

S2, forming a conductive adhesive layer on one side of the first shielding layer;

s3, forming a second shielding layer on one side, far away from the first shielding layer, of the conductive adhesive layer; the second shielding layer is provided with a second through hole penetrating through the upper surface and the lower surface of the second shielding layer;

in the embodiment of the present invention, the cross-sectional area of the second through-hole is formed to be 0.1 μm²-1mm²(ii) a Every 1cm²The number of the second through holes in the second shielding layer is 10-1000.

And S4, forming an adhesive film layer on one side of the second shielding layer far away from the conductive adhesive layer.

Specifically, a glue film layer is coated on a release film, and then the glue film layer is transferred to one side, away from the conductive glue layer, of the second shielding layer in a pressing mode, so that the glue film layer is formed on one side, away from the conductive glue layer, of the second shielding layer; or

And directly coating an adhesive film layer on one side of the second shielding layer, which is far away from the conductive adhesive layer, so that the adhesive film layer is formed on one side of the second shielding layer, which is far away from the conductive adhesive layer.

In another preferred embodiment suitable for preparing the electro-magnetic shielding film of embodiment 2, before step S4, the method further comprises the steps of:

forming conductor particles on the first surface of the second shielding layer through one or more processes of physical roughening, chemical plating, physical vapor deposition, chemical vapor deposition, evaporation plating, sputtering plating, electroplating and mixed plating; the first surface is a surface of the second shielding layer, which is in contact with the adhesive film layer, and the first surface is a flat surface.

In another preferred embodiment suitable for preparing the electro-magnetic shielding film of embodiment 4, before step S4, the method further comprises the steps of:

forming conductor particles on the first surface of the second shielding layer through one or more processes of physical roughening, chemical plating, physical vapor deposition, chemical vapor deposition, evaporation plating, sputtering plating, electroplating and mixed plating; the first surface is a surface of the second shielding layer, which is in contact with the adhesive film layer, and the first surface is a non-flat surface.

To sum up, the embodiment of the invention provides an electromagnetic shielding film, a circuit board and a preparation method of the electromagnetic shielding film, wherein the electromagnetic shielding film comprises a first shielding layer 1, a conductive adhesive layer 2, a second shielding layer 3 and an adhesive film layer 4 which are sequentially stacked, a first through hole 11 penetrating through the upper surface and the lower surface of the first shielding layer 1 is arranged on the first shielding layer, and a second through hole 31 penetrating through the upper surface and the lower surface of the second shielding layer 3 is arranged on the second shielding layer. The first shielding layer 1 and the second shielding layer 3 are arranged at the same time, and the first shielding layer 1, the conductive adhesive layer 2, the second shielding layer 3 and the adhesive film layer 4 are sequentially stacked, so that the electromagnetic shielding film can reflect high-frequency interference signals twice, extremely high shielding efficiency is realized, and the electromagnetic shielding film is suitable for ultrahigh frequency and high-speed transmission; meanwhile, the conductive adhesive layer 2 is arranged between the first shielding layer 1 and the second shielding layer 3, so that the bending property of the electromagnetic shielding film is improved; in addition, through set up first through-hole 11 on first shielding layer 1, set up second through-hole 31 on second shielding layer 3 simultaneously for under the high temperature, volatile matter in the glued membrane layer 4 can be followed first through-hole 11 and second through-hole 31 are discharged, have avoided effectively when the high temperature volatile matter is difficult to discharge and lead to the phenomenon of electromagnetic shielding membrane bubbling layering in the glued membrane layer 4, thereby has avoided peeling off between the stratum of electromagnetic shielding membrane and circuit board, and then has ensured the good ground connection of electromagnetic shielding membrane, and will disturb electric charge and derive.

In addition, due to the arrangement of the first through hole 11 and the second through hole 31, in the process of pressing, the part of the conductive adhesive layer 2 located between the first shielding layer 1 and the second shielding layer 3 extends into and is connected to the first through hole 11 and the second through hole 31, and the part of the adhesive layer 4 extends into and is connected to the second through hole 31, so that the first shielding layer 1, the conductive adhesive layer 2, the second shielding layer 3 and the adhesive layer 4 are tightly connected together, and the peeling strength of the electromagnetic shielding film is greatly improved.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.