TWI875199B - A porous metallic conductive paste film and a preparation method thereof - Google Patents

Abstract

The present invention discloses a porous metallic conductive paste film, comprising a first adhesive layer, a super-thin porous metal layer and a second adhesive layer, wherein the super-thin porous metal layer is placed between the first adhesive layer and the second adhesive layer. The present invention also discloses a method for preparing the porous metallic conductive paste film.

Description

A porous metal conductive film and its preparation method

This disclosure is related to the technical field of conductive adhesive for printed circuit boards, and in particular to a porous metal conductive adhesive film, which is used in FPC and is bonded with steel sheets or PI-type reinforcing plates to form a reinforced component.

The development trend of electronic and communication products requires circuit board components to be thin, short and highly integrated. The increasingly wide transmission signal frequency band leads to increasingly serious electromagnetic interference. At the same time, considering the safety of electronic circuit components, the reliability of circuit component grounding in electronic products and the freedom of circuit board design are also higher than before. The conductive glue products commonly used in the market will have defects such as filling the grounding aperture too full with conductive glue, affecting the design and installation of other components, or insufficient filling resulting in gaps in the connection part during reflow soldering, resulting in board explosion.

In addition, most of the conductive adhesive products currently circulating in the market directly disperse the conductive particles in the adhesive. The adhesive layer is generally thicker. If the curing is insufficient and the pressing conditions are uneven, it will cause uneven powder distribution when the product is attached to the printed circuit board, thereby affecting the conductive performance and other problems.

At present, there are also some new technologies and patents that mention that a thin metal layer can be buried in a conductive adhesive layer to improve the conductivity of conductive adhesive products and reduce the powder content to reduce costs. Theoretically, this is completely true, but in the actual production process, due to the poor flexibility of the metal itself, the hole filling of the product after pressing cannot achieve the expected effect, and may even be worse. At the same time, due to its poor air permeability, the metal layer has the potential to explode during SMT processing in the FPC process.

Therefore, there is still an urgent need in this field for a conductive adhesive product that can provide improved conductivity and safety, as well as reduced signal interference.

One of the purposes of the present disclosure is to provide a porous metal conductive adhesive film, comprising a first adhesive layer with a thickness of 20 to 40 μm; an ultra-thin porous metal layer with a thickness of 2 to 15 μm and a plurality of through holes formed on the first adhesive layer; and a second adhesive layer with a thickness of 20 to 40 μm formed on the ultra-thin porous metal layer, so that the ultra-thin porous metal layer is sandwiched between the first adhesive layer and the second adhesive layer, and the total thickness of the conductive adhesive film is 40 to 100 μm, wherein the ultra-thin porous metal layer is a porous metal silver-plated copper foil or a porous metal gold-plated copper foil, and the through hole density of the plurality of through holes is 10,000 to 15,000 per cm ² and each having a through hole diameter of 1 to 100 μm.

In one specific embodiment of the present disclosure, the first adhesive layer and the second adhesive layer are both thermosetting adhesive layers containing metal conductive particles and adhesive resin, and the weight ratio of the metal conductive particles to the adhesive resin is 0.25 to 4.

In one specific embodiment of the present disclosure, the metal conductive particles are selected from at least two of the group consisting of dendrite-shaped metal powders, needle-shaped metal powders, flake-shaped metal powders and spherical metal powders; and the metal conductive particles are single metal conductive particles and/or alloy conductive particles.

In one specific embodiment of the present disclosure, the single metal conductive particles are selected from at least one of the group consisting of gold particles, silver particles, copper particles, nickel particles and graphite; and the alloy conductive particles are selected from at least one of the group consisting of silver-plated copper particles, silver-plated nickel particles, gold-plated copper particles, gold-plated nickel particles and graphene-copper alloy.

In one specific embodiment of the present disclosure, the adhesive resin is selected from one or more of the following resins: epoxy resin, acrylic resin, urethane resin, silicone rubber resin, polyparacycloxylene resin, dimaleimide resin, phenolic resin, melamine resin and polyimide resin.

In one specific embodiment of the present disclosure, the metal conductive particles are a mixture of the spherical metal powder, the needle-shaped metal powder and the flaky metal powder, wherein the weight ratio of the spherical metal powder to the needle-shaped metal powder is 0.2 to 5, and the weight ratio of the needle-shaped metal powder to the flaky metal powder is 0.25 to 4.

In one specific embodiment of the present disclosure, a release layer or a carrier layer is formed on one side of each of the first adhesive layer and the second adhesive layer.

In one specific embodiment of the present disclosure, the thickness of the release layer is 25 to 100 μm, and the release film of the release layer is selected from at least one of PET fluoroplastic release film, PET silicone oil-containing release film, PET matte release film and PE release film.

The present disclosure further provides a method for preparing the aforementioned porous metal conductive adhesive film, comprising: forming a first adhesive layer and a second adhesive layer on the release surfaces of a first release layer and a second release layer, respectively; laminating the first adhesive layer and the second adhesive layer to two opposite surfaces of an ultra-thin porous metal layer, respectively, so that the ultra-thin porous metal layer is sandwiched between the first adhesive layer and the second adhesive layer; curing the first adhesive layer and the second adhesive layer to obtain the porous metal conductive adhesive film; and rolling up the porous metal conductive adhesive film.

In one embodiment of the present disclosure, the formation of the first adhesive layer and the second adhesive layer includes screening and mixing at least two metal conductive particles of different shapes; mixing the metal conductive particles with an adhesive resin to obtain a mixture; and coating the mixture on the first release layer and the second release layer, respectively.

Yet another object of the present disclosure is to provide a method for preparing the aforementioned porous metal conductive adhesive film, comprising: forming a first adhesive layer on the release surface of the release layer; laminating the first adhesive layer on one surface of the ultra-thin porous metal layer; coating the other surface of the ultra-thin porous metal layer with a mixture of metal conductive particles and adhesive resin to form a second adhesive layer; curing the first adhesive layer and the second adhesive layer to obtain the porous metal conductive adhesive film; and rolling up the porous metal conductive adhesive film.

In one specific embodiment of the present disclosure, a striping operation is performed after the porous metal conductive adhesive film is rolled up.

The beneficial effects of this disclosure include at least the following:

1. The porous metal conductive adhesive film used in this disclosure can be applied to FPC, and can be combined with steel sheets or PI-type reinforcement plates to form a reinforced component, and effectively prevent the installation part from being deformed due to bending and other reasons, and can ensure the product's good hole filling performance, can play the role of direct grounding and shielding external signal interference, and has good shielding performance;

2. The ultra-thin porous metal layer in the porous metal conductive adhesive film disclosed herein is beneficial for the conductive metal particles added to the two adhesive layers to connect the upper and lower conductive adhesive layers through the holes due to its porous structure. At the same time, due to its good air permeability, it will not explode during SMT processing in the downstream process of FPC, which can effectively solve the explosion problem encountered by the conductive adhesive and buried metal layer conductive adhesive currently circulating in the market;

3. The ultra-thin porous metal layer disclosed herein is based on various metals. The metal substrate may include but is not limited to electroplated metal layers, such as porous metal silver-plated copper foil and porous metal gold-plated copper foil, etc., which have good stability and weather resistance. These characteristics prevent it from deforming due to excessive hardness when the FPC is subjected to heat pressing, resulting in poor material performance. At the same time, the adhesive layer and the conductive particles therein are deformed and flowed due to the hot pressing of the adhesive resin material to achieve isotropic conduction, which can effectively avoid the defects of poor conduction effect of traditional conductive glue and conductive glue with non-porous thin metal layer added;

4. The porous metal layer in the porous metal conductive film disclosed herein can also be treated by electroplating. For example, Cu is more active than Au and Ag, so the porous metal layer can be made of porous silver-plated copper foil and porous gold-plated copper foil, which can effectively solve the disadvantage that Cu is easily oxidized at high temperatures, greatly improve the bonding strength of the product without affecting the conductive performance of the product, and reduce the material cost at the same time.

100: Conductive film

101: First adhesive layer

102: Ultra-thin porous metal layer

103: Second adhesive layer

104: Abstraction

The implementation method of the present disclosure is described through exemplary reference drawings:

Figure 1 is a schematic diagram of the structure of the porous metal conductive film disclosed herein.

The following is a specific and concrete example to illustrate the implementation of the present disclosure. People familiar with this art can easily understand the advantages and effects of the present disclosure from the content disclosed in this manual.

It should be understood that the structures, proportions, sizes, etc. shown in the attached drawings of this manual are only used to match the contents disclosed in the manual for people familiar with this technology to understand and read, and are not used to limit the restrictive conditions for the implementation of this disclosure, so they have no substantial technical significance. Any modification of the structure, change of the proportion relationship, or adjustment of the size should still fall within the scope of the technical content disclosed in this disclosure without affecting the effects and purposes that can be produced by this disclosure. At the same time, the references such as "one", "first" and "second" in this manual are only for the convenience of description, and are not used to limit the scope of the implementation of this disclosure. The changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of this disclosure without substantially changing the technical content.

When "includes", "comprising" or "having" a specific element in this article, unless otherwise stated, it may also include other elements, components, structures, regions, parts, devices, systems, steps or connection relationships, rather than excluding such other elements.

The numerical ranges described herein are inclusive and combinable. Any numerical value falling within the numerical range herein can be used as the maximum value or minimum value to derive the sub-range. For example, the numerical range of "20μm to 40μm" should be understood to include any sub-range between a minimum value of 20μm and a maximum value of 40μm, such as: 20μm to 35μm, 25μm to 40μm, and 25μm to 35μm. In addition, if a numerical value falls within the ranges described herein (such as between the maximum value and the minimum value), it should be considered to be included in the scope of the present disclosure.

The "through hole" mentioned in this article refers to a through hole that penetrates the ultra-thin porous metal layer and/or two opposite surfaces.

As shown in FIG. 1 , the present disclosure provides a porous metal conductive adhesive film 100, which includes a first adhesive layer 101, an ultra-thin porous metal layer 102, and a second adhesive layer 103, wherein the ultra-thin porous metal layer 102 is sandwiched between the first adhesive layer 101 and the second adhesive layer 103. Furthermore, one side of the first adhesive layer 101 and the second adhesive layer 103 may each be formed with (or not formed with) a release layer 104.

Here, as shown in FIG. 1 , the present disclosure also provides a method for preparing a porous metal conductive adhesive film 100, which includes screening at least two metal conductive particles of different shapes and mixing them evenly; mixing the metal conductive particles with an adhesive resin to obtain a mixture; and coating the mixture on the release surfaces of a first release layer 104 and a second release layer 104 to form a first adhesive layer 101 and a second adhesive layer 103 for standby use. Next, the other side of the first adhesive layer 101 opposite to the first release layer 104 is laminated to one side of the ultra-thin porous metal layer 102; the other side of the ultra-thin porous metal layer 102 is laminated to the other side of the second adhesive layer 103 opposite to the second release layer 104, and then the first adhesive layer 101 and the second adhesive layer 103 are cured to obtain the porous metal conductive adhesive film 100, and the porous metal conductive adhesive film 100 is rolled up. In a specific implementation, a striping operation is further included.

In a specific embodiment, the release layer 104 is formed on only one side of the first adhesive layer 101. Therefore, the present disclosure further provides a method for preparing a porous metal conductive adhesive film 100, which includes: screening at least two metal conductive particles of different shapes and mixing them uniformly; mixing the metal conductive particles with an adhesive resin to obtain a mixture; applying the mixture to the release layer 104; 04 to form a first adhesive layer 101; the other side of the first adhesive layer 101 opposite to the release layer 104 is bonded to one side of the ultra-thin porous metal layer 102; the mixture is applied on the other side of the ultra-thin porous metal layer 102 to form a second adhesive layer 103; and curing, winding and slitting are performed to provide the porous metal conductive adhesive film 100.

In a specific embodiment, the total thickness of the conductive adhesive film 100 is 40 to 100 μm, preferably 40 to 80 μm, 50 to 80 μm or 50 to 70 μm, for example, about 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 or 100 μm. Since the ultra-thin porous metal layer has a hole-like structure, after the first and second adhesive layers are formed on its two sides respectively, the adhesives on the two sides will penetrate into the holes of the ultra-thin porous metal layer, so the actual total thickness of the final product (i.e., the conductive adhesive film) may be less than the sum of the thickness of the ultra-thin porous metal layer and the first and second adhesive layers.

In a specific implementation, the thickness of the first adhesive layer 101 and the second adhesive layer 103 is 20 to 40 μm, for example, about 20, 25, 30, 35, or 40 μm. If the adhesive layer is too thin, the masking effect is not good. If the adhesive layer is too thick, it does not meet the thinning requirements and the coating processability requirements are higher, which indirectly increases the production cost.

In a specific embodiment, the thickness of the ultra-thin porous metal layer 102 is 2 to 15 μm, for example, about 2, 4, 6, 8, 10, 12, 14 or 15 μm. If the ultra-thin porous metal layer is too thick, the metal particles in the adhesive layer on both sides will not be able to contact each other, and the upper and lower contact will be poor; if it is too thin, it will be unfavorable for production and increase production costs.

In a specific implementation, the ultra-thin porous metal layer 102 in the porous metal conductive film disclosed herein can be based on various metals, and the metal substrate can include but is not limited to electroplated metal layers. Examples of ultra-thin porous metal layers used in the present disclosure include copper foil, silver-plated copper foil, and gold-plated copper foil, etc., preferably copper foil and/or silver-plated copper foil. Such ultra-thin porous metal layers have good stability and weather resistance, can improve product reliability and masking performance, and will not deform due to excessive hardness when subjected to heat pressure in the FPC process, resulting in poor material performance.

In one embodiment, the through-hole density of the plurality of through-holes in the ultra-thin porous metal layer 102 is 10,000 to 15,000 per cm ² , such as about 10,000, 11,000, 12,000, 13,000, 14,000 or 15,000 per cm ² . In one embodiment, the through-hole diameter of the ultra-thin porous metal layer 102 is 1 to 100 μm, such as about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90 or 100 μm. The through holes on the ultra-thin porous metal layer provide multi-dimensional channels for the two adhesive layers and the conductive particles therein to reduce the diffusion distance of ions and electrons. An isotropic conductive glue is formed through three conductive glue conduction mechanisms, namely, conductive channel, tunnel effect and field emission. This can effectively avoid the defects of poor conduction effect of traditional conductive glue and conductive glue with added non-porous thin metal layer, and can improve product reliability and masking performance.

In a specific implementation, the first adhesive layer 101 and the second adhesive layer 103 are both thermosetting adhesive layers containing metal conductive particles and adhesive resin. Preferably, the weight ratio of the metal conductive particles to the adhesive resin is 0.25 to 4, such as 0.25, 0.33, 0.5, 0.54, 1, 1.22, 1.49, 2, 2.33, 3 or 4. When the ratio is lower than 0.25, the conductivity is poor, and more adhesive will cause problems such as sticking during downstream operations; and when the ratio is higher than 4, due to the higher proportion of conductive particle powder, the requirements for powder dispersion technology are also higher, and both adhesion and bonding strength will be affected.

In a specific embodiment, based on the total weight of the adhesive layer, the weight ratio of the metal conductive particles is 20 to 80%, such as 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, or 80%, preferably 35 to 55%. Too much metal conductive particles will result in excessive powder and uneven dispersion; too little may cause poor conduction effect. In addition, if the proportion of adhesive resin is too small, the viscosity is too low, which is not conducive to online production; too much will produce products with strong viscosity, and the relative reduction of metal powder content will lead to poor conductivity.

In a specific embodiment, based on the total weight of the adhesive layer, the weight ratio of the adhesive resin is 20 to 80% (calculated by solid content), such as 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, or 80%. If the content is too low, the viscosity is too low, which is not conducive to online production. If the content is too high, the product produced will have strong viscosity, and the relative reduction of the metal powder content will lead to poor conductivity.

In a specific embodiment, the adhesive resin is selected from one or more of the following resins: epoxy resin, acrylic resin, urethane resin, silicone rubber resin, polyparacycloxylene resin, dimaleimide resin, phenolic resin, melamine resin and polyimide resin; preferably, the adhesive resin is an acrylic resin.

In a specific embodiment, the metal conductive particles in the porous metal conductive film disclosed herein are at least two of dendritic metal powder, needle-shaped metal powder, flake-shaped metal powder and spherical metal powder. Preferably, the metal conductive particles are a mixture of dendritic metal powder, needle-shaped metal powder and flake-shaped metal powder.

When the metal conductive particles in the porous metal conductive adhesive film disclosed herein are a mixture of two or more metal powders of different forms, the metal powders can be mixed in any suitable proportion. For example, when the metal conductive particles are a mixture of spherical metal powder, needle-shaped metal powder and flaky metal powder, the weight ratio of the spherical metal powder to the needle-shaped metal powder is 0.2 to 5, and the weight ratio of the needle-shaped metal powder to the flaky metal powder is 0.25 to 4. Too high or too low a ratio will reduce the conductivity of the conductive adhesive. In the adhesive layer containing the metal conductive particles, the conductive particles of various forms will deform and flow due to the heat pressing of the adhesive resin, and then form a conductive circuit with the grounding aperture on the flexible board. Because the conductive particles contained in it have different shapes, after a period of high-temperature aging, the resin can be completely cross-linked and solidified to maintain good electrical and mechanical properties, so that the grounding impedance value of the obtained soft board is reduced. At the same time, the adhesive layer containing metal conductive particles and metal parts such as steel sheets or PI-type reinforcement plates can form a reinforcement element and be attached to the printed circuit board. Because it has good grounding stability, it can effectively shield external electromagnetic interference.

In a specific implementation, the metal conductive particles of different shapes need to be screened by a screener and then mixed evenly for use, wherein the median of the metal particle size distribution is 2 to 22 μm, preferably 8 to 20 μm. Too small a particle size will result in poor effect of filling the conductive hole in the printed circuit substrate, while too large a particle size will increase the difficulty of coating production, which is not conducive to production.

In a specific embodiment, the metal conductive particles are at least one of single metal conductive particles and alloy conductive particles. Examples of the single metal conductive particles include but are not limited to at least one of gold particles, silver particles, copper particles, nickel particles and graphite; examples of the alloy conductive particles include but are not limited to at least one of silver-plated copper particles, silver-plated nickel particles, gold-plated copper particles, gold-plated nickel particles and graphene-copper alloy. The aforementioned metal particles have excellent oxidation resistance and conductivity. Therefore, the conductive adhesive film using the metal particles disclosed in the present invention is convenient for product storage and transportation, and will not affect the physical properties of the product, making the product more stable and reliable.

The first adhesive layer 101 and the second adhesive layer 103 may each have (or not have) a release layer 104 or a carrier layer formed on one side. In a specific implementation, the first adhesive layer 101 and the second adhesive layer 103 disclosed herein both have a release layer 104 formed on one side. In a specific implementation, only one side of the first adhesive layer 101 has a release layer 104 formed on it.

In a specific embodiment, the thickness of the release layer 104 is 25 to 100 μm, for example, 25, 35, 45, 55, 65, 75, 85, 95 or 100 μm. And the release film of the release layer is selected from at least one of PET fluoroplastic release film, PET silicone oil-containing release film, PET matte release film and PE release film.

In a specific implementation, the release layer 104 can be double-sided or single-sided release; preferably double-sided release. In a specific implementation, the release layer 104 is pure white, milky white or transparent. When CNC automation equipment is used to engrave lines and infrared sensing is used, white has no problem of reflected light, and precise positioning and processing operations can be performed quickly. In addition, when manual operations are performed, white has an identification function to prevent human tearing. Therefore, the release layer 104 is preferably pure white or milky white. In a specific implementation, the release layer is a white double-sided PET release film.

In a specific implementation, the release layer 104 can be a release paper, as long as the release paper is well bonded to the product adhesive layer and is easy to peel off, and will not fall off during transportation.

The conductive adhesive film disclosed herein has a thinner ultra-thin porous metal layer and a larger specific surface area, so that after the adhesive layer is processed by the downstream pressing process, the metal particles in the ultra-thin porous metal layer will fill the holes in the ultra-thin porous metal layer without affecting the morphology and conduction effect of the ultra-thin porous metal layer, thereby greatly enhancing the overall conduction effect of the material. Compared with the existing conductive adhesive, the conductive particle content in the conductive adhesive layer can be effectively reduced to achieve the same conduction effect.

Therefore, as demonstrated in the following examples, the present disclosure provides a highly conductive porous metal conductive adhesive film comprising metal powders of various forms and porous metal layers, which has good electrical properties, good bonding strength, good solderability, good reliability, good flame resistance, etc., and has better conduction effect and bonding strength than general conductive adhesives. The conductive adhesive film disclosed in the present disclosure is easy to produce, has broad market application prospects, and can be combined with a PI type reinforcement plate to achieve the functions of reinforcement, grounding and shielding, avoiding the defect that traditional conductive adhesives can only be combined with steel sheets.

Embodiment

In order to compare the difference in properties between the conductive film disclosed herein and conventional conductive films, the following porous metal conductive films of Examples 1 to 6 and the general product structure conductive films of Comparative Examples 1 and 2 were prepared according to the aforementioned preparation method, wherein the metal foil material used in each of the Examples and Comparative Examples is copper foil; each porous metal layer has a through hole with a diameter of less than 20 microns and a porosity of 25±2%; metal particles of different shapes are mixed in equal proportions, and the median number of the particle size is 8 to 20 μm. Next, the conductivity analysis test of the porous metal conductive adhesive film disclosed in this disclosure and the conductive adhesive films of Comparative Examples 1 and 2 after peeling off the release films on both sides was performed: the conductivity analysis test was performed using a Gaoqiao tester (product model: UNI-T, UT620B), and the nickel-plated steel sheet and FPC were dummy-mounted on the upper and lower sides of the adhesive layer, respectively, and then pressed and cured, and the conductivity resistance data of the samples were tested before and after reflow soldering. The measured conductivity results are recorded in Table 1.

Similarly, after peeling off the release films on both sides, the peeling force analysis test was performed on the conductive adhesive films of Examples 1 to 6 of the present disclosure and the conductive adhesive films of Comparative Examples 1 and 2: The peeling force analysis test was performed using a universal tensile tester (Shimadzu, product model: AGS-X), and nickel-plated steel sheets and single-sided CCL were attached to the upper and lower sides of the adhesive layer, respectively, and then pressed and cured and taken out to test the Peel value. The measured Peel value, solder heat resistance and conductivity results are recorded in Table 1.

Table 1

Peel strength test method: IPC-TM-650 2.4.9;

Solder heat resistance test method: IPC-TM-650 2.4.13.

The resin contained in the first and second adhesive layers used in Examples 1 to 5 is an acrylic resin.

As can be seen from the above table, the new porous metal conductive adhesive film disclosed herein has good conductivity, solder heat resistance and good bonding strength compared to general products.

The above embodiments are only illustrative and not intended to limit the present disclosure. Anyone familiar with this technology may modify and change the above embodiments without violating the spirit and scope of the present disclosure. Therefore, the scope of protection of the present disclosure is defined by the scope of the patent application attached to the present disclosure. As long as it does not affect the effect and implementation purpose of the present disclosure, it should be covered by the disclosed technical content.

100: Conductive film

101: First adhesive layer

102: Ultra-thin porous metal layer

103: Second adhesive layer

104: Abstraction

Claims (11)

A porous metal conductive adhesive film comprises: a first adhesive layer with a thickness of 20 to 40 μm; an ultra-thin porous metal layer with a thickness of 2 to 15 μm and a plurality of through holes formed on the first adhesive layer; and a second adhesive layer with a thickness of 20 to 40 μm formed on the ultra-thin porous metal layer, so that the ultra-thin porous metal layer is sandwiched between the first adhesive layer and the second adhesive layer, and the total thickness of the conductive adhesive film is 40 to 100 μm, wherein the ultra-thin porous metal layer is a porous metal silver-plated copper foil or a porous metal gold-plated copper foil, and the through hole density of the plurality of through holes is 10,000 to 15,000 per cm ² and each having a through hole diameter of 1 to 100 μm, and wherein the first adhesive layer and the second adhesive layer are both thermosetting adhesive layers containing metal conductive particles and adhesive resin, and the weight ratio of the metal conductive particles to the adhesive resin is 1 to 4. The porous metal conductive film as described in claim 1, wherein the metal conductive particles are selected from at least two of the group consisting of dendrite-shaped metal powder, needle-shaped metal powder, flake-shaped metal powder and spherical metal powder; and the metal conductive particles are single metal conductive particles and/or alloy conductive particles. The porous metal conductive film as described in claim 2, wherein the single metal conductive particles are at least one selected from the group consisting of gold particles, silver particles, copper particles, nickel particles and graphite; and the alloy conductive particles are at least one selected from the group consisting of silver-plated copper particles, silver-plated nickel particles, gold-plated copper particles, gold-plated nickel particles and graphene-copper alloy. The porous metal conductive adhesive film as described in claim 1, wherein the adhesive resin is selected from one or more of the following resins: epoxy resin, acrylic resin, urethane resin, silicone rubber resin, polyparaxylene resin, dimaleimide resin, phenolic resin, melamine resin and polyimide resin. The porous metal conductive adhesive film as described in claim 2, wherein the metal conductive particles are a mixture of the spherical metal powder, the needle-shaped metal powder and the flaky metal powder, wherein the weight ratio of the spherical metal powder to the needle-shaped metal powder is 0.2 to 5, and the weight ratio of the needle-shaped metal powder to the flaky metal powder is 0.25 to 4. The porous metal conductive adhesive film as described in claim 1, wherein a release layer or a carrier layer is formed on one side of the first adhesive layer and the second adhesive layer. The porous metal conductive adhesive film as described in claim 6, wherein the thickness of the release layer is 25 to 100 μm, and the release layer is selected from at least one of PET fluoroplastic release film, PET silicone oil-containing release film, PET matte release film and PE release film. A method for preparing a porous metal conductive adhesive film as described in any one of claims 1 to 7, comprising: forming a first adhesive layer and a second adhesive layer on the release surfaces of a first release layer and a second release layer, respectively; laminating the first adhesive layer and the second adhesive layer to two opposite surfaces of an ultra-thin porous metal layer, respectively, so that the ultra-thin porous metal layer is sandwiched between the first adhesive layer and the second adhesive layer; curing the first adhesive layer and the second adhesive layer to obtain the porous metal conductive adhesive film; and rolling up the porous metal conductive adhesive film. The method of claim 8, wherein the formation of the first adhesive layer and the second adhesive layer includes screening and mixing at least two metal conductive particles of different shapes; mixing the metal conductive particles with an adhesive resin to obtain a mixture; and coating the mixture on the first release layer and the second release layer, respectively. A method for preparing a porous metal conductive adhesive film as described in any one of claims 1 to 7, comprising: forming a first adhesive layer on the release surface of a release layer; laminating the first adhesive layer on one surface of the ultra-thin porous metal layer; applying a mixture containing metal conductive particles and an adhesive resin on the other surface of the ultra-thin porous metal layer to form a second adhesive layer; curing the first adhesive layer and the second adhesive layer to obtain the porous metal conductive adhesive film; and rolling up the porous metal conductive adhesive film. The method of claim 10, wherein the formation of the first adhesive layer includes screening and mixing at least two metal conductive particles of different shapes; mixing the metal conductive particles with an adhesive resin to obtain a mixture; and coating the mixture on a release layer.

Images