TWI749612B - Electromagnetic interference shielding film comprising porous metal and methods thereof - Google Patents

Abstract

An electromagnetic interference shielding film comprising porous metal comprising an outer coating, an insulation layer formed on the outer coating, a porous metal layer having a porosity of 7% to 32% and a conductive adhesive layer. The outer coating is selected from one of white ink layer, gray ink layer and black ink layer. The insulation layer is selected from at least one of black polyimide layer and black ink layer. The porous metal layer is formed on the insulation layer, and making the insulation layer between the outer coating and the porous metal layer. The porous metal layer has pore size of 30 micrometer to 120 micrometer, tensile strength of equal to or more than 20 kg/mm² and elongation of equal to or more than 0.5%. The conductive adhesive layer is formed on the porous metal layer, and making the porous metal layer between the insulation and the conductive adhesive layer. The present invention further provides a preparation method thereof.

Description

Electromagnetic interference shielding film including porous metal and preparation method thereof

The present invention relates to the technical field of electromagnetic interference shielding films, and particularly relates to an electromagnetic interference shielding film including a porous metal layer.

Under the market demand of electronic and communication products becoming more multifunctional and complex, the structure of the circuit substrate needs to be lighter, thinner and shorter, and in terms of function, it needs to be powerful and high-speed signal transmission. As electronic signal transmission is more high-speed and dense, the line density is bound to increase, making the distance between the substrate lines closer, and the application frequency is going to be higher and wider, making the electromagnetic interference (EMI) situation more and more serious, so it must be effectively managed Electromagnetic Compatibility (EMC), so as to maintain the normal signal transmission of electronic products and improve reliability. The characteristics of being thin and flexible, making flexible printed circuit (FPC) play an important role in the development of the portable information and communication electronics industry.

Due to the trend of smaller electronic communication products, FPCs must carry more and more powerful functions. On the other hand, as portable electronic products move towards miniaturization, the demand for high-density FPC technology is also driven by the demand for powerful functions. And the situation of high frequency, high density, and thinning At present, shielding films for thin-film FPCs have been launched on the market, and they are widely used in small electronic products such as mobile phones, digital cameras, and digital cameras.

With the advent of the 5G era, terminal electronic products have higher and higher requirements for electromagnetic interference shielding, and the demand for electromagnetic interference shielding performance has become higher and higher, and the thickness of electromagnetic interference shielding films has become higher and higher. However, with The increase in thickness also shows its disadvantages. The solder heat resistance of the electromagnetic interference shielding film and the surface mount technology (SMT) process test are particularly obvious. For example, the large-area explosion board of the immersion tin test after the normal curing process, the large-area explosion board of the shielding film after the SMT process, or the on-resistance between the SMT process lines have a significant increase, and the shielding metal layer with higher thickness and When thinner insulating layers and conductive adhesive layers are used together, they can cause weather resistance problems. For example, the on-resistance under high-temperature and high-humidity environments or under cold and thermal shock test conditions has a significant increase and adhesion problems, which may even lead to shielding metals. Delamination.

In order to solve the above problems, the present invention provides an electromagnetic interference shielding film including porous metal, which includes: an outer coating layer selected from one of a white ink layer, a gray ink layer and a black ink layer, and the outer coating layer is The angle of 60° has a gloss of 0 to 60%; the insulating layer is selected from one of the black polyimide layer or the black ink layer, and the insulating layer is formed on the outer coating; with 7% A porous metal layer with a porosity of up to 32% is formed on the insulating layer so that the insulating layer is located between the outer coating and the porous metal layer. The porous metal layer has a pore size of 30 to 120 microns, and The tensile strength of the porous metal layer is greater than or equal to 20Mpa, and the elongation is greater than or equal to 0.5%; and the conductive adhesive layer is formed on the porous metal layer to make the porous metal layer porous. The metal layer is located between the insulating layer and the conductive adhesive layer, wherein the outer coating has a thickness of 2 to 5 microns, the insulating layer has a thickness of 3 to 25 microns, and the porous metal layer has a thickness of 2 to 5 microns. 15 microns, and the thickness of the conductive adhesive layer is 3 to 25 microns.

In a specific embodiment, the black ink layer includes selected from epoxy resin, polyimide, acrylic resin, urethane resin, silicone rubber resin, parylene resin and double At least one resin in the group consisting of maleimide resins.

In a specific embodiment, the black ink layer includes a flame-retardant compound, and the flame-retardant compound is selected from the group consisting of halogen-containing compounds, phosphorus-based compounds, nitrogen-containing compounds, and boron-based compounds. At least one.

In a specific embodiment, the conductive adhesive layer is a single-layer conductive adhesive layer with conductive particles.

In a specific embodiment, the conductive adhesive layer includes an adhesive layer that does not contain conductive particles, and is located between the porous metal layer and the conductive adhesive layer.

In a specific embodiment, the conductive particles are at least one selected from the group consisting of copper, silver, nickel, tin, gold, palladium, aluminum, chromium, titanium, zinc, carbon and alloys thereof.

In a specific embodiment, the insulating layer has a thickness of 3 to 10 microns, the porous metal layer has a thickness of 3 to 8 microns, and the conductive adhesive layer has a thickness of 5 to 15 microns.

The present invention also provides a method for preparing an electromagnetic interference shielding film, which includes: forming an insulating layer on the surface of the porous metal layer; forming an outer coating on the surface of the insulating layer so that the insulating layer is located on the porous metal layer and the outer coating Between; pressing the first release layer on the outer coating so that the outer coating is located between the first release layer and the insulating layer; forming a conductive adhesive layer on the porous metal layer, The porous metal layer is located between the insulating layer and the conductive adhesive layer, and the second release layer is pressed on the conductive adhesive layer so that the conductive adhesive layer is located between the second release layer and the porous metal layer.

In a specific embodiment, the preparation method of the porous metal layer includes: forming an aluminum layer on a thin film; performing a release treatment on the surface of the aluminum layer; electroplating a metal layer on the surface of the released aluminum layer Above, wherein the method of electroplating is selected from one of sputtering, evaporation and water plating, and the metal layer is formed with holes by micro-etching treatment, and the inner layer of the metal layer has a plurality of through holes; and The thin film and the aluminum layer are peeled off, so that the metal layer is formed into a porous metal layer.

In a specific embodiment, the film is one of polyimide or ethylene terephthalate, and the metal layer is selected from copper, aluminum, lead, nickel, cobalt, tin, silver, At least one of the group consisting of iron and gold.

In one embodiment, the preparation method further includes forming an adhesive layer without conductive particles on the porous metal layer before forming the conductive adhesive layer, and then forming a conductive adhesive layer on the adhesive layer.

The electromagnetic interference shielding film including porous metal of the present invention has many advantages such as good electrical characteristics, good chemical resistance, high shielding performance, good bonding strength, low transmission loss, high transmission quality and high reliability.

The electromagnetic interference shielding film including porous metal of the present invention uses a porous metal layer to replace the metal layer used in the existing shielding film. The porous metal layer can reflect electromagnetic waves, so that it can reflect most of the radio frequency and microwave energy, and transmit The component is extremely small, thus effectively shielding the interference of electromagnetic wave radiation.

10, 20: electromagnetic interference shielding film

11, 21: outer coating

12, 22: Insulation layer

13, 23: porous metal layer

14: conductive adhesive layer

15, 25: the first release layer

16, 26: second release layer

24: Next layer

24’: Conductive adhesive layer

141, 241: conductive particles

The embodiments of the present invention will be described with reference to the drawings as an example:

Figure 1 is a schematic diagram of the structure of the electromagnetic interference shielding film including porous metal of the present invention; and

Figure 2 is a schematic diagram of another structure of the electromagnetic interference shielding film including porous metal of the present invention.

The following is a specific embodiment to illustrate the implementation of the present invention. Those familiar with the art can easily understand the advantages and effects of the present invention from the content disclosed in this specification.

It should be noted that the structure, ratio, size, etc. shown in the accompanying drawings in this manual are only used to match the content disclosed in the manual for the understanding and reading of those familiar with the art, and are not intended to limit the implementation of the present invention. Therefore, it does not have any technical significance. Any structural modification, proportional relationship change, or size adjustment, without affecting the effects and objectives that can be achieved by the present invention, should still fall within the scope of this The technical content disclosed by the invention can be covered. At the same time, references such as "一", "下" and "上" in this specification are only for ease of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments to their relative relationships are not Substantive changes to the technical content should also be regarded as the scope of the present invention can be implemented. In addition, all ranges and values herein are inclusive and combinable. Any value or point falling within the range described herein, for example, any integer can be used as the minimum or maximum value to derive the lower range and so on.

As shown in Figure 1, it shows a specific embodiment of the electromagnetic interference shielding film 10 including porous metal of the present invention, which includes: an outer coating 11, an insulating layer 12, and a porous metal layer 13. And the conductive adhesive layer 14. The insulating layer 12 is formed on the outer coating 11, the porous metal layer 13 is formed on the insulating layer 12, so that the insulating layer 12 is located between the outer coating 11 and the porous metal layer 13, and the The conductive adhesive layer 14 is formed on the porous metal layer 13 so that the porous metal layer 13 is located between the insulating layer 12 and the conductive adhesive layer 14.

In a specific embodiment, the outer coating 11 has a first release layer 15 on the other surface where the insulating layer 12 is formed, and the conductive adhesive layer 14 has a first release layer 15 on the other surface contacting the porous metal layer 13 The second release layer 16, and the first release layer 15 and the second release layer 16 are selected from one of a release film, a release paper, and a carrier film.

In a specific embodiment, the release film has a thickness of 25 microns to 100 microns, and the release film is selected from the group consisting of PET fluorine release film, PET silicone oil release film, PET matte light release film and At least one of the group consisting of PE release film. In another embodiment, the release paper has a thickness of 25 μm to 130 μm, and the release paper is PET coated paper. In another embodiment, the thickness of the carrier film is 25 to 100 microns, and the surface of the carrier film has an adhesive.

In a specific embodiment, the outer coating 11 is selected from one of a white ink layer, a gray ink layer, and a black ink layer. In another specific embodiment, the outer coating layer includes selected from epoxy resin, polyimide, acrylic resin, urethane resin, silicone rubber resin, parylene resin and At least one resin in the group consisting of bismaleimide resins.

In a specific implementation aspect, the outer coating 11 has a gloss of 0 to 60% at an angle of 60°. The outer coating 11 has good mechanical properties, is abrasion-resistant and aging, and has good chemical resistance. It is used as the electromagnetic interference shielding film 10 of the present invention including porous metal. Exposed face. In addition, by reducing the surface gloss of the outer coating 11 to achieve good scattering and extinction effects, light penetration can be effectively reduced, and the electromagnetic interference shielding film 10 including porous metal of the present invention can be protected.

The present invention uses the following three methods to make the outer coating have the aforementioned gloss. The first method is physical polishing, which is by increasing the thickness of the first release layer 15 attached to the outer coating 11 Surface roughness, so that the outer coating 11 has a gloss of 0 to 60% at an angle of 60°; the second method is wet coating frosting, which is to add silicon dioxide and titanium dioxide before the adhesive The inorganic powder is coated on the surface of the first release layer 15, and the surface is attached to the outer coating layer 11, so that the outer coating layer 11 has an angle of 60° with a measurement angle of 0 to 60% Gloss; and, the third method is to directly add inorganic additives to the outer coating 11, so that the outer coating 11 has a gloss of 0 to 60% at an angle of 60°, and the inorganic additives It includes at least one selected from the group consisting of titanium dioxide, silicon dioxide, aluminum oxide, aluminum hydroxide, and calcium carbonate.

In a specific embodiment, the insulating layer 12 is one of a black polyimide layer or a black ink layer. The black polyimide layer has low water absorption and can still achieve excellent reliability under high temperature and high humidity environments.

In a specific embodiment, the porous metal layer 13 has a porosity of 7% to 32%, such as 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%. %, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31% or 32%. The tensile strength of the porous metal layer 13 is greater than or equal to 20Mpa; the elongation of the porous metal layer 13 is greater than or equal to 0.5%, such as greater than 0.5%, 1%, 2%, 3%, 4%, 5% , 6%, 7%, 8%, 9% or 10%; the porous metal layer 13 has a pore size of 30 microns to 120 microns, such as 30, 40, 50, 60, 70, 80, 90, 100, 110 or 120 microns. In another embodiment, the porous metal layer 13 has a porosity of 15% to 30%. In another embodiment, the elongation rate of the porous metal layer 13 is greater than or equal to 5%.

In a specific embodiment, the thickness of the electromagnetic interference shielding film 10 including porous metal of the present invention is 10 micrometers to 70 micrometers, for example, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 , 20, 21, 22, 23, 24, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70 microns. Alternatively, the thickness of the electromagnetic interference shielding film 10 including porous metal of the present invention is 13 micrometers to 38 micrometers. In another embodiment, the thickness of the outer coating 11 is 2 to 5 microns, for example, 2, 3, 4, 5 microns; the thickness of the insulating layer 12 is 3 to 25 microns, for example, 3 , 4, 5, 6, 7, 8, 9, 10, 15, 20, 25 microns; the porous metal layer 13 has a thickness of 2 to 15 microns, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15 micrometers; the thickness of the conductive adhesive layer 14 is 3 micrometers to 25 micrometers, for example, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25 micrometers. Alternatively, the thickness of the outer coating 11 is 2 to 5 microns, the thickness of the insulating layer 12 is 3 to 10 microns, the thickness of the porous metal layer 13 is 3 to 8 microns, and the thickness of the conductive adhesive layer 14 The thickness is 5 to 15 microns.

In a specific embodiment, the black ink layer includes selected from epoxy resin, polyimide, acrylic resin, urethane resin, silicone rubber resin, parylene resin and double At least one resin in the group consisting of maleimide resins.

In a specific embodiment, the black ink layer includes a flame-retardant compound, and the flame-retardant compound is selected from the group consisting of halogen-containing compounds, phosphorus-based compounds, nitrogen-containing compounds, and boron-based compounds. At least one.

In a specific embodiment, the conductive adhesive layer 14 is a single-layer conductive adhesive layer with conductive particles 141.

In a specific embodiment, the conductive particles are at least one selected from the group consisting of copper, silver, nickel, tin, gold, palladium, aluminum, chromium, titanium, zinc, carbon and alloys thereof. In another embodiment, the alloy is selected from at least one of the group consisting of nickel-gold alloy, gold-silver alloy, copper-silver alloy, nickel-silver alloy, and copper-nickel-gold alloy.

In a specific implementation aspect, the content of the conductive particles accounts for 20% to 60% of the conductive adhesive layer.

The present invention further provides a method for preparing the electromagnetic interference shielding film 10 including porous metal, which includes forming an insulating layer 12 on the surface of the porous metal layer 13; forming an overcoat layer 11 on the surface of the insulating layer 12 to make the insulating layer 12 Located between the porous metal layer 13 and the outer coating 11; pressing the first release layer 15 on the outer coating 11 so that the outer coating 11 is located between the first release layer 15 and the insulating layer; Forming a conductive adhesive layer on the porous metal layer 13 so that the porous metal layer is located between the insulating layer and the conductive adhesive layer; and pressing the second release layer 16 on the conductive adhesive layer 14 to make the conductive adhesive layer 14 is located between the second release layer 16 and the porous metal layer 13.

In a specific embodiment, the preparation method of the porous metal layer includes: forming an aluminum layer on a thin film; performing a release treatment on the surface of the aluminum layer; electroplating a metal layer on the surface of the released aluminum layer Above, wherein the method of electroplating is selected from one of sputtering, evaporation and water plating, and the metal layer is formed with holes by micro-etching treatment, and the inner layer of the metal layer has a plurality of through holes; and The thin film and the aluminum layer are peeled off, so that the metal layer is formed into a porous metal layer.

In a specific embodiment, the film is one of polyimide or ethylene terephthalate, and the metal layer is selected from copper, aluminum, lead, nickel, cobalt, tin, silver, At least one of the group consisting of iron and gold. Alternatively, the metal layer is copper.

In a specific implementation aspect, the micro-etching treatment is a chemical etching treatment using a micro-etching solution, and the micro-etching solution includes an inorganic acid, a micro-etching agent, and a solution such as water. In another embodiment, the inorganic acid is one of sulfuric acid or hydrogen chloride, and the microetching agent is selected from the group consisting of hydrogen peroxide, sodium persulfate, ammonium persulfate, and chlorate. One. In another embodiment, the combination of the inorganic acid and the microetching agent (indicated by the inorganic acid-microetching agent) is selected from the group consisting of sulfuric acid-hydrogen peroxide, sulfuric acid-sodium persulfate, sulfuric acid-ammonium persulfate and hydrogen chloride -One of the group consisting of chlorates.

In a specific embodiment, the microetching solution further includes additives, such as stabilizers and accelerators.

Due to the strong oxidizing properties of the above-mentioned microetching agent in an acid environment, a redox reaction is generated on the metal layer to form holes in the metal layer, and the inner layer of the metal layer has a plurality of through holes. In addition, the microetching process forms oxide on the surface of the metal layer, and after the oxide reacts with inorganic acids such as sulfuric acid and hydrogen chloride, the metal layer can be roughened and the surface cleaned.

In one embodiment, both the surface and the inner layer of the metal layer subjected to the microetching treatment have holes, and the inner layer of the metal layer has a plurality of through holes. In another embodiment, the plurality of through holes are formed in a local area of the metal layer to increase the heat dissipation of the metal layer and prevent the metal layer from bursting during subsequent applications.

As shown in Fig. 2, it shows a specific implementation aspect of the electromagnetic interference shielding film 20 including porous metal of the present invention. Its components are similar to the specific implementation aspect shown in Fig. 1. Therefore, the following is only for the first aspect. The differences between Figure 2 and Figure 1 are described. In the electromagnetic interference shielding film 20 including porous metal shown in Figure 2, the conductive adhesive layer is a double-layer conductive adhesive layer composed of an adhesive layer 24 without conductive particles and a conductive adhesive layer 24' with conductive particles 241 Composition, wherein the adhesive layer 24 is located between the porous metal layer 23 and the conductive adhesive layer 24'.

Specifically, the stacking structure of the electromagnetic interference shielding film 20 including porous metal shown in FIG. 2 is: the first release layer 25, the outer coating 21, the insulating layer 22, the porous metal layer 23, and the adhesive layer 24. , The conductive adhesive layer 24' and the second release layer 26.

In the aspect of the electromagnetic interference shielding film 20 including porous metal shown in FIG. 2, the preparation method is similar to the specific implementation aspect shown in FIG. 1. Only the differences between FIG. 2 and FIG. 1 will be described below. . Before forming the conductive adhesive layer, an adhesive layer 24 without conductive particles is formed on the porous metal layer 23, and then a conductive adhesive layer 24' with conductive particles 241 is formed on the adhesive layer 24.

In this embodiment, the outer coating 21 has a first release layer 25 on the other surface where the insulating layer 22 is formed, and the conductive adhesive layer 24' has a first release layer 25 on the other surface contacting the adhesive layer 24. Two release layer 26.

The following examples and comparative examples illustrate the performance of the porous metal electromagnetic interference shielding film of the present invention.

Table 1 shows the test results of the thickness of each layer, the porosity of the porous metal layer, the tensile strength and elongation, the resistance value, the peeling strength, and the shielding properties of Examples 1 to 8 and Comparative Example 1. Examples 1 to 8 are the porous metal electromagnetic interference shielding films of the present invention. In Examples 1 to 8, guide The electrical adhesive layer is a single conductive adhesive layer containing conductive particles, and the content of the conductive particles accounts for 20% to 60% of the conductive adhesive layer, and the composition of the outer coating and the insulating layer is epoxy resin, Curing agent, carbon black, titanium dioxide, rubber, dispersant and defoamer. In addition, the electromagnetic interference shielding film of Example 8 further has an adhesive layer structure between the porous metal layer and the conductive adhesive layer. Comparative Example 1 is a conventional shielding film, the metal layer of which is generally a metal layer that has not been subjected to microetching treatment, and the shielding film of Comparative Example 1 does not have the structure of an outer coating.

The composition of the microetching solution used in the porous metal layer of Examples 1 to 8 is sulfuric acid, hydrogen peroxide, potassium dichromate, water, stabilizer and accelerator. Based on the total weight of the microetching solution, the content of sulfuric acid is 8 weight. %, the content of hydrogen peroxide is 5% by weight, and the content of potassium dichromate is 1 to 3% by weight.

Table 1: The thickness of each layer and various properties of Examples 1 to 8 and Comparative Example 1

The thickness in Table 1 is measured with a micrometer; gloss is measured with a gloss meter at an angle of 60°; resistance is measured with a micro-ohm meter; peel strength is measured with a universal tensile testing machine; The measurement method of tensile strength and elongation is based on IPC-TM650 2.4.19.

Table 2 shows the performance test results of the on-resistance of the shielding film after the SMT process. Examples 7 and 8 are the electromagnetic interference shielding film including the porous metal layer of the present invention. Among them, the conductive adhesive layer of Example 7 is a single layer For the conductive adhesive layer, Example 8 is a double-layer conductive adhesive layer.

Table 2: Performance test results of Examples 7, 8 and Comparative Example 1

The resistance value in Table 2 is measured in accordance with JIS C5016 1994-7.1; the peel strength is measured in accordance with IPC-TM650 2.4.9; -40°C to 40°C/100hrs represents the test method of thermal cycle, the method is in order: a) Reduce from 25°C to -40°C within 0.5 hours; b) Maintain at -40°C for 1 hour and 15 minutes; c) Increase from -40°C to 40°C within 0.5 hours; d) Maintain at 40°C for 1 hour 15 minutes; e) Decrease from 40°C to 25°C within 0.5 hour, and circulate 25 times according to the above steps, for a total of 100 hours.

From the test results in Table 1 and Table 2, it can be seen that the electromagnetic interference shielding film including the porous metal layer of the present invention has better electromagnetic interference shielding performance, SMT process simulation test, on-resistance and weather resistance after SMT process. Shielding film.

The above-mentioned embodiments are merely illustrative and are not used to limit the present invention. Anyone who is familiar with this technique can modify and change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the rights of the present invention is defined by the scope of the patent application attached to the present invention. As long as it does not affect the effect and implementation purpose of the present invention, it should be covered in the technical content of this disclosure.

10: EMI shielding film

11: Outer coating

12: Insulation layer

13: Porous metal layer

14: conductive adhesive layer

15: The first release layer

16: The second release layer

141: Conductive particles

Claims (11)

An electromagnetic interference shielding film including porous metal, which includes: The outer coating is one selected from the white ink layer, the gray ink layer and the black ink layer, and the outer coating has a gloss of 0 to 60% at an angle of 60°; The insulating layer is selected from one of a black polyimide layer or a black ink layer, and the insulating layer is formed on the outer coating; A porous metal layer with a porosity of 7% to 32% is formed on the insulating layer so that the insulating layer is located between the outer coating and the porous metal layer. The porous metal layer has a thickness of 30 to 120 microns Pore size, and the tensile strength of the porous metal layer is greater than or equal to 20Mpa, and the elongation is greater than or equal to 0.5%; and The conductive adhesive layer is formed on the porous metal layer so that the porous metal layer is located between the insulating layer and the conductive adhesive layer, Wherein, the thickness of the outer coating is 2 μm to 5 μm, the thickness of the insulating layer is 3 μm to 25 μm, the thickness of the porous metal layer is 2 μm to 15 μm, and the thickness of the conductive adhesive layer is 3 μm To 25 microns. The electromagnetic interference shielding film described in item 1 of the scope of patent application, wherein the black ink layer contains selected from epoxy resin, polyimide, acrylic resin, urethane resin, and silicone rubber resin , At least one resin in the group consisting of parylene resin and bismaleimide resin. The electromagnetic interference shielding film described in item 2 of the scope of patent application, wherein the black ink layer includes a flame-retardant compound, and the flame-retardant compound is selected from halogen-containing compounds, phosphorus-based compounds, and nitrogen-containing compounds And at least one of the group consisting of boron-based compounds. According to the electromagnetic interference shielding film described in item 1 of the scope of patent application, the conductive adhesive layer is a single-layer conductive adhesive layer with conductive particles. The electromagnetic interference shielding film described in item 4 of the scope of patent application includes an adhesive layer without conductive particles, which is located between the porous metal layer and the conductive adhesive layer. The electromagnetic interference shielding film described in item 4 or 5 of the scope of patent application, wherein the conductive particles are selected from copper, silver, nickel, tin, gold, palladium, aluminum, chromium, titanium, zinc, carbon and alloys thereof At least one of the groups. The electromagnetic interference shielding film described in the first item of the scope of patent application, wherein the thickness of the insulating layer is 3 to 10 microns, the thickness of the porous metal layer is 3 to 8 microns, and the thickness of the conductive adhesive layer is 5 microns to 15 microns. A preparation method of electromagnetic interference shielding film includes: Forming an insulating layer on the surface of the porous metal layer; Forming an outer coating on the surface of the insulating layer so that the insulating layer is located between the porous metal layer and the outer coating; Pressing the first release layer on the outer coating so that the outer coating is located between the first release layer and the insulating layer; Forming a conductive adhesive layer on the porous metal layer so that the porous metal layer is located between the insulating layer and the conductive adhesive layer; and The second release layer is pressed on the conductive adhesive layer so that the conductive adhesive layer is located between the second release layer and the porous metal layer. The preparation method of the electromagnetic interference shielding film as described in item 8 of the scope of patent application, wherein the preparation method of the porous metal layer includes: Forming an aluminum layer on a thin film; Release the surface of the aluminum layer; Electroplating a metal layer on the surface of the release-treated aluminum layer, wherein the method of electroplating is selected from one of sputtering, evaporation and water plating, and the metal layer is formed with holes by micro-etching treatment, And the inner layer of the metal layer has at least one through hole; and The film and the aluminum layer are peeled off, so that the metal layer is formed into a porous metal layer. The method for preparing an electromagnetic interference shielding film according to item 9 of the scope of patent application, wherein the film is polyimide or ethylene terephthalate, and the metal layer is selected from copper, aluminum, and lead At least one of the group consisting of, nickel, cobalt, tin, silver, iron and gold. The preparation method as described in item 8 of the scope of the patent application includes forming an adhesive layer without conductive particles on the porous metal layer before forming the conductive adhesive layer, and then forming the conductive adhesive layer on the adhesive layer .

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