Electromagnetic shielding film material capable of rapidly releasing adhesion as well as preparation method and application of electromagnetic shielding film material

Abstract

The invention provides an electromagnetic shielding film material capable of quickly releasing adhesion as well as a preparation method and application thereof, and the electromagnetic shielding film material comprises the following components in percentage by mass: 8-30% of thermal adhesive resin, 60-80% of conductive particles and 5-20% of thermal expansion microspheres. The electromagnetic shielding film material solves the problems in the prior art that the electromagnetic shielding film material is difficult to effectively separate from a device, long in debonding time, easy to remain and easy to damage the device due to high bonding force of thermal bonding resin.

Description

Technical Field

[0001] The invention belongs to the technical field of electromagnetic shielding materials, and in particular relates to a fast-debonding electromagnetic shielding film material and a preparation method and application thereof. Background Art

[0002] In recent years, electronic devices have been developing towards miniaturization, lightness, and multifunctionality. The electromagnetic interference problem in electronic products has become increasingly serious. Electromagnetic shielding materials are needed to restrain electromagnetic waves and ensure the normal operation of electronic products. Conformal shielding technology can integrate the electromagnetic shielding layer on the device. The thickness of the electromagnetic shielding layer is usually only tens of microns. It effectively reduces the thickness of electronic products while reducing the weight of electronic products. It is one of the most advanced electromagnetic shielding technologies.

[0003] Existing conformal shielding technology is mainly implemented by sputtering, spraying, chemical plating and other methods. Due to the strong bonding between conformal shielding materials and the carrier (chip or PCB board and its components), it is difficult to achieve non-destructive repair of chips or electronic components. At present, conformal shielding materials can be removed by the following four methods: 1. External stimulation method: Introducing specific components (such as reversible covalent bonds, shape memory components, photosensitive components, catechol, etc.) into the resin matrix. When the external environment of the material is changed (such as temperature, light, electricity, magnetism, etc.), the bonding force between the material and the substrate is weakened, or the material is deformed and separated from the substrate, achieving the debonding of the electromagnetic shielding material. 2. Chemical corrosion method: Use chemical reagents (such as sulfuric acid, acetone, toluene, etc.) to change the chemical environment around the material, so that the functional groups on the surface of the material react, soften the material or dissolve the material, and achieve the debonding of the electromagnetic shielding material. 3. Mechanical grinding method: Use grinding tools (such as sandpaper, grinding wheel or emery cloth, etc.) to grind off the electromagnetic shielding film, or use sharp tools (such as scrapers, scrapers or pliers, etc.) to scrape off the electromagnetic shielding film. 4. Laser method: Use the ablation effect of laser to remove the electromagnetic shielding film. However, chemical corrosion method, mechanical grinding method and laser method will damage the device, and the device needs to be shielded in a complex way, and the processing time is long.

[0004] A common defect of the prior art is that after the electromagnetic shielding film material containing a resin with thermal adhesive properties is deposited on the device, it is difficult to effectively separate the electromagnetic shielding film material from the device due to the high adhesion of the resin. There are generally problems such as difficulty in cleaning, the electromagnetic shielding film material is easily left on the device, the debonding time is long, and the device may even be damaged.

[0005] Therefore, developing an electromagnetic shielding film material that can be quickly debonded, does not remain on the surface of the device and has good electromagnetic shielding performance is a technical problem that needs to be urgently solved in this field. Summary of the invention

[0006] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a kind of electromagnetic shielding film material with rapid de-adhesion, its preparation method and application. The electromagnetic shielding film material solves the problems in the existing technology that due to the high adhesion force of the thermo-bonding resin, it is difficult to effectively separate the electromagnetic shielding film material from the device, the de-adhesion time is long, and the electromagnetic shielding film material is easily left on the surface of the device and is likely to damage the device.

[0007] To achieve this purpose, the present invention adopts the following technical solutions:

[0008] In the first aspect, the present invention provides a kind of electromagnetic shielding film material with rapid de-adhesion. Calculated by mass percentage, the electromagnetic shielding film material includes 8-30% of thermo-bonding resin, 60-80% of conductive particles and 5-20% of thermally expandable microspheres.

[0009] Thermally expandable microspheres are a kind of material formed by wrapping a volatile liquid reagent with a thermoplastic shell. When heated, the shell softens, and the volatile liquid reagent inside the shell vaporizes and expands, and the volume can increase by 40-80 times. In the present invention, by introducing thermally expandable microspheres and using the foaming and expanding characteristics of thermally expandable microspheres at high temperature, the de-adhesion characteristics can be given to the electromagnetic shielding material, realizing the rapid de-adhesion of the electromagnetic shielding film material on the substrate. This de-adhesion process not only does not damage the substrate, but also there is almost no residue of the electromagnetic shielding film material on the substrate; the conductive particles can endow the electromagnetic shielding film material with good electromagnetic shielding performance. Moreover, the thermally expandable microspheres can form an isolation structure with the conductive particles in the resin matrix, which is beneficial to further improving the electromagnetic shielding performance of the electromagnetic shielding material; through the compounding of specific contents of thermally expandable microspheres and conductive particles, the electromagnetic shielding film material can not only rapidly de-adhere, with almost no residue on the basic surface and no damage to the device, but also improve the electromagnetic shielding performance of the electromagnetic shielding material.

[0010] In the present invention, 8-30% of thermo-bonding resin can be, for example, 8.4%, 8.8%, 9%, 9.5%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, etc.

[0011] In the present invention, when the content of the thermo-bonding resin is within the above range, it can ensure the good bonding performance of the electromagnetic shielding material while taking into account the rapid de-adhesion performance.

[0012] In the present invention, 60-80% of conductive particles can be, for example, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, etc.

[0013] In the present invention, the thermally expandable microspheres are 5-20%, for example, they can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, etc.

[0014] In the present invention, when the contents of the thermally expandable microspheres and the conductive particles are within the above ranges, the electromagnetic shielding film material takes into account good de-adhesion performance and electromagnetic shielding performance, while ensuring the mechanical properties of the electromagnetic shielding film material; when the content of the conductive particles is too low, the electromagnetic shielding performance of the material is poor; when the content is too high, the adhesion of the material to the substrate is insufficient, affecting reliability; when the content of the thermally expandable microspheres is too low, the de-adhesion ability of the material on the substrate is poor; when the content is too high, the mechanical properties of the electromagnetic shielding film material are insufficient.

[0015] Preferably, the thermally adhesive resin includes any one or a combination of at least two of epoxy resin, polymethyl methacrylate resin, polyurethane resin, phenolic resin, phenoxy resin, ethylene-vinyl acetate copolymer resin, acrylic resin or polyamide resin.

[0016] In the present invention, the electromagnetic shielding film material can be added with a certain content of curing agent according to actual needs. For example, when the thermally adhesive resin is selected from epoxy resin, the electromagnetic shielding film material needs to be added with a curing agent; the mass of the curing agent is 15-35% of the thermally adhesive resin, and the types of the curing agent include but are not limited to diethyl toluene diamine.

[0017] Preferably, the conductive particles include any one or a combination of at least two of flaky conductive particles, spherical conductive particles, dendritic conductive particles.

[0018] In the present invention, flaky conductive particles are more preferably used, which is beneficial to the balance of the mechanical properties and electromagnetic shielding performance of the electromagnetic shielding film material.

[0019] The sheet diameter of the flaky conductive particles is 1-20 μm, for example, it can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm or the range between any two of the above.

[0020] The particle size of the spherical conductive particles is 1 to 20 μm, for example, it can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm or the range between any two of the above; the particle size of the dendritic conductive particles is 10 to 20 μm, for example, it can be 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm or the range between any two of the above.

[0021] In the present invention, conductive particles with a size of 5 to 12 μm are more preferably used, which is beneficial to the balance of the mechanical properties and electromagnetic shielding properties of the electromagnetic shielding film material.

[0022] Preferably, the conductive particles include any one or more of gold powder, silver powder, copper powder, silver-coated copper powder, nickel powder, iron powder, aluminum powder, carbon black, graphite or MXene powder.

[0023] Preferably, the initial particle size of the thermally expandable microspheres is 5 to 70 μm, for example, it can be 5 μm, 6 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 22 μm, 25 μm, 28 μm, 30 μm, 32 μm, 35 μm, 38 μm, 40 μm, 42 μm, 45 μm, 48 μm, 50 μm, 52 μm, 55 μm, 58 μm, 60 μm, 62 μm, 65 μm, 68 μm, 70 μm or the range value between any two of the above; more preferably, the initial particle size is 5 to 25 μm.

[0024] In the present invention, if the particle size of the thermally expandable microspheres is too small, the debonding effect of the electromagnetic shielding film material on the substrate is poor and complete peeling cannot be achieved; if the particle size is too large, the mechanical properties (tensility, strength, adhesion) and film-forming properties of the electromagnetic shielding film material are poor, the adhesion force on the substrate is weak, and the surface roughness of the material is high.

[0025] Preferably, the initial expansion temperature of the thermally expandable microspheres is 100 to 220 °C, for example, it can be 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, 210 °C, 220 °C, etc.; more preferably, the initial expansion temperature is 130 to 200 °C.

[0026] In the present invention, the initial expansion temperature of the thermally expandable microspheres is relatively low, and the heat generated by the device itself can cause the thermally expandable microspheres to expand, affecting the normal use of electronic products. In addition, it will also affect the film-forming process of the material because the preparation process of the material involves a heating process; if the initial expansion temperature is relatively high, the debonding temperature will also be higher, and too high a temperature will cause the device to be desoldered from the main board and even damage the device.

[0027] In the present invention, the thermally expandable microspheres have a core-shell structure; the shell material includes a thermoplastic material of acrylic acid type; the core material includes a liquid hydrocarbon. Exemplarily, the thermally expandable microspheres include, but are not limited to, Nouryon 920DU20, 920DU40, 920DU80, 950DU80, etc.

[0028] Preferably, the conductive particles and the thermally expandable microspheres in the electromagnetic shielding film material are randomly distributed, and / or the conductive particles are coated on the surface of the thermally expandable microspheres.

[0029] Preferably, the mass ratio of the conductive particles to the thermally expandable microspheres is (3.5 - 15):1, where the specific values in (1 - 8) can be, for example, 3.8, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, etc.

[0030] In the present invention, when the mass ratio of the thermally expandable microspheres to the conductive particles is within the above range, it is more beneficial for the electromagnetic shielding film material to balance the debonding performance and the electromagnetic shielding performance.

[0031] In a second aspect, the present invention provides a method for preparing the electromagnetic shielding film material with rapid debonding according to the first aspect, and the preparation method includes the following steps:

[0032] Mix a thermally adhesive resin, conductive particles, and thermally expandable microspheres to obtain a mixture; shape the mixture to obtain the electromagnetic shielding film material.

[0033] Preferably, the mixing method includes solution mixing or melt mixing.

[0034] Preferably, the solution mixing method includes: mixing a thermally adhesive resin with a solvent to obtain a thermally adhesive resin solution; then mixing the thermally adhesive resin solution with conductive particles and thermally expandable microspheres to obtain a mixture.

[0035] In the present invention, the solvent includes at least one of N,N-dimethylformamide, acetone, methyl ethyl ketone, cyclohexanone, dibutyl phthalate, ethyl acetate, toluene, and xylene.

[0036] Preferably, the melt mixing method includes: heating the thermally adhesive resin to melt, and then adding conductive particles and thermally expandable microspheres thereto for mixing to obtain a mixture.

[0037] In the present invention, the temperature of the heating and melting is 120 to 180 °C, and for example, it can be 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, etc.

[0038] In the present invention, in the preparation method, the conductive particles and the thermally expandable microspheres can be mixed with the thermally adhesive resin solution or the melted thermally adhesive resin by a mechanical physical mixing method, and in the obtained electromagnetic shielding film material, the conductive particles and the thermally expandable microspheres are randomly distributed; and / or, the conductive particles can also be deposited on the surface of the thermally expandable microspheres by electroless plating, that is, the conductive particles are formed on the surface of the thermally expandable microspheres in an in-situ synthesis manner to obtain metallized thermally expandable microspheres, and then the metallized thermally expandable microspheres are mixed with the thermally adhesive resin solution or the melted thermally adhesive resin, and in the obtained electromagnetic shielding film material, the conductive particles are coated on the surface of the thermally expandable microspheres.

[0039] Preferably, the forming method includes coating forming and / or casting forming.

[0040] Specifically, the electromagnetic shielding film material provided by the present invention is prepared by at least one of the following methods (A)-(D):

[0041] (A) Dissolve the thermally adhesive resin in a solvent to obtain a thermally adhesive resin solution, then add the conductive particles and the thermally expandable microspheres to the thermally adhesive resin solution, and perform mechanical stirring, and obtain the electromagnetic shielding film material through a coating process.

[0042] (B) Heat and melt the thermally adhesive resin, then add the conductive particles and the thermally expandable microspheres to the thermally adhesive resin, and obtain the electromagnetic shielding film material through a casting process.

[0043] (C) Deposit the conductive particles on the surface of the thermally expandable microspheres by electroless plating to obtain metallized thermally expandable microspheres. At the same time, dissolve the thermally adhesive resin in a solvent to obtain a thermally adhesive resin solution, then add the metallized thermally expandable microspheres to the thermally adhesive resin solution, and perform mechanical stirring, and obtain the electromagnetic shielding film material through a coating process.

[0044] (D) Deposit the conductive particles on the surface of the thermally expandable microspheres by electroless plating to obtain metallized thermally expandable microspheres. At the same time, heat and melt the thermally adhesive resin, then add the metallized thermally expandable microspheres to the thermally adhesive resin, and obtain the electromagnetic shielding film material through a casting process.

[0045] In the third aspect, the present invention provides an electronic device, and the electronic device includes a substrate and the electromagnetic shielding film material with rapid de-adhesion described in the first aspect provided on the surface of the substrate.

[0046] In the present invention, the electromagnetic shielding film material is fixed on the substrate by means of thermal adhesion. After the electromagnetic shielding film material is completely cured, it is heated at a certain temperature (30 - 60 °C higher than the initial expansion temperature of the thermally expandable microspheres), so that the thermally expandable microspheres inside the electromagnetic shielding film material are heated and expanded, with an increased volume and becoming fluffy, and separated from the substrate to achieve de-adhesion.

[0047] The numerical ranges described in the present invention not only include the above-listed point values, but also any point values between the above numerical ranges that are not listed. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the range.

[0048] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0049] The electromagnetic shielding film material with rapid de-adhesion provided by the present invention, through the compounding of thermally expandable microspheres with a specific content and conductive particles, can effectively peel off the electromagnetic shielding film with thermal bonding characteristics on the device. The processing conditions for the entire de-bonding process are mild, the de-bonding time is short, there is no damage to the device, and there is almost no residue of the electromagnetic shielding film material on the device surface. Moreover, it can also improve the electromagnetic shielding performance of the electromagnetic shielding material. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a schematic diagram of the preparation method and de-adhesion process of the electromagnetic shielding film material provided in Embodiment 1 of the present invention;

[0051] Figure 2 It is an effect diagram of the de-adhesion process of the electromagnetic shielding film material provided in Embodiment 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0052] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

[0053] Embodiment 1

[0054] This embodiment provides an electromagnetic shielding film material. In terms of mass percentage, the electromagnetic shielding film material includes 20% polyurethane resin (BASF AH660), 70% flaky silver powder (flake diameter is 3 - 5 μm, Kunming Norman), and 10% thermally expandable microspheres (initial particle size is 5 - 9 μm, initial expansion temperature is 130 °C, manufacturer's brand is Nouryon 920DU20).

[0055] This embodiment provides a preparation method for the electromagnetic shielding film material, which specifically includes the following steps:

[0056] Dissolve the polyurethane resin in a solvent (the solvent is N,N-dimethylformamide) to obtain a polyurethane resin solution (mass concentration is 25%); then add flaky silver powder and thermally expandable microspheres to the polyurethane resin solution, and carry out mechanical stirring and coating molding to obtain the electromagnetic shielding film material.

[0057] Example 2

[0058] This example provides an electromagnetic shielding film material. By mass percentage, the electromagnetic shielding film material includes 20% ethylene-vinyl acetate copolymer resin (BASF EVAV5110J), 70% flaky silver powder (flake diameter is 3 - 5 μm, Kunming Norman), and 10% thermally expandable microspheres (initial particle size is 18 - 24 μm, initial expansion temperature is 140 °C, manufacturer's grade is Nouryon 950DU80).

[0059] This example provides a preparation method of an electromagnetic shielding film material, which specifically includes the following steps:

[0060] Heat and melt the ethylene-vinyl acetate copolymer resin at 120 °C, then add flaky silver powder and thermally expandable microspheres to it, and carry out casting molding to obtain the electromagnetic shielding film material.

[0061] Example 3

[0062] This example provides an electromagnetic shielding film material. By mass percentage, the electromagnetic shielding film material includes 20% polyurethane resin (BASF AH660), 55% flaky silver powder (flake diameter is 3 - 5 μm, Kunming Norman), and 25% thermally expandable microspheres with silver plating on the surface (particle size is 5 - 9 μm, silver content is 60 wt%, initial expansion temperature is 130 °C, manufacturer's grade is Nouryon 920DU20), and the total mass of conductive particles is 70%.

[0063] This example provides a preparation method of the electromagnetic shielding film material, which specifically includes the following steps:

[0064] Dissolve the polyurethane resin in a solvent (the solvent is N,N-dimethylformamide) to obtain a polyurethane resin solution (mass concentration is 25%); deposit silver particles on the surface of the thermally expandable microspheres by electroless plating to obtain silver-plated thermally expandable microspheres; then add the silver-plated thermally expandable microspheres and flaky silver powder to the polyurethane resin solution, the total content of silver in the silver-plated thermally expandable microspheres and the content of flaky silver powder is 70%, and carry out mechanical stirring and coating molding to obtain the electromagnetic shielding film material.

[0065] Example 4

[0066] This embodiment provides an electromagnetic shielding film material. In terms of mass percentage, the electromagnetic shielding film material includes 20% ethylene-vinyl acetate copolymer resin (BASF EVAV5110J), 30% flaky silver powder (flake diameter is 3 - 5 μm, Kunming Norman), and 50% thermally expandable microspheres with silver plating on the surface (particle size is 18 - 24 μm, nickel content is 80 wt%, initial expansion temperature is 140 °C, manufacturer's brand is Nouryon 950DU80). The total mass of the conductive particles is 70%.

[0067] This embodiment provides a preparation method for the electromagnetic shielding film material, which specifically includes the following steps:

[0068] Deposit silver particles on the surface of the thermally expandable microspheres by electroless plating to obtain silver-plated thermally expandable microspheres; heat and melt the ethylene-vinyl acetate copolymer resin at 120 °C, then add the silver-plated thermally expandable microspheres and flaky silver powder to it. The total content of silver in the silver-plated thermally expandable microspheres and the content of flaky silver powder is 70%. Perform casting molding to obtain the electromagnetic shielding film material.

[0069] Example 5

[0070] This embodiment provides an electromagnetic shielding film material. In terms of mass percentage, the electromagnetic shielding film material includes 6.4% epoxy resin (Nanya Plastics NPEL-128 curing agent), 1.6% curing agent (diethyltoluenediamine, Jiangsu Victoray), 2% phenoxy resin (Huntsman PKHH), 70% flaky silver powder (flake diameter is 3 - 5 μm, Kunming Norman), and 20% thermally expandable microspheres (particle size is 5 - 9 μm, initial expansion temperature is 130 °C, manufacturer's brand is Nouryon 920DU20).

[0071] This embodiment provides a preparation method for the electromagnetic shielding film material, which specifically includes the following steps:

[0072] Dissolve the epoxy resin and phenoxy resin in a solvent (the solvent is acetone) to obtain a thermally adhesive resin solution (mass concentration is 25%); then add the flaky silver powder and thermally expandable microspheres to the thermally adhesive resin solution and perform mechanical stirring, and then perform coating molding to obtain the electromagnetic shielding film material.

[0073] Example 6

[0074] This embodiment provides an electromagnetic shielding film material, and the only difference from Example 1 is that the flaky silver powder is replaced with an equal mass of copper-coated silver powder (particle size is 10 - 15 μm, Guangzhou Beijun), and other components, dosages, and preparation methods are the same as those in Example 1.

[0075] Example 7

[0076] This embodiment provides an electromagnetic shielding film material, which is only different from that of Embodiment 1 in that the starting expansion temperature of the thermally expandable microspheres is 125 °C, the average particle size is 10-16 μm, and it is Nouryon 920DU40.

[0077] Example 8

[0078] This embodiment provides an electromagnetic shielding film material. In terms of mass percentage, the electromagnetic shielding film material includes 15% polyurethane resin (BASF AH660), 70% flaky silver powder (flake diameter is 3-5 μm, Kunming Norman), and 15% thermally expandable microspheres (particle size is 5-9 μm, starting expansion temperature is 130 °C, manufacturer's brand is Nouryon 920DU20).

[0079] This embodiment provides a preparation method of the electromagnetic shielding film material, and the specific steps are the same as those of Embodiment 1.

[0080] Example 9

[0081] This embodiment provides an electromagnetic shielding film material. In terms of mass percentage, the electromagnetic shielding film material includes 20% polyurethane resin (BASF AH660), 75% flaky silver powder (flake diameter is 3-5 μm, Kunming Norman), and 5% thermally expandable microspheres (particle size is 5-9 μm, starting expansion temperature is 130 °C, manufacturer's brand is Nouryon 920DU20).

[0082] This embodiment provides a preparation method of the electromagnetic shielding film material, and the specific steps are the same as those of Embodiment 1.

[0083] Example 10

[0084] This embodiment provides an electromagnetic shielding film material. In terms of mass percentage, the electromagnetic shielding film material includes 15% polyurethane resin (BASF AH660), 75% flaky silver powder (flake diameter is 3-5 μm, Kunming Norman), and 10% thermally expandable microspheres (particle size is 5-9 μm, starting expansion temperature is 130 °C, manufacturer's brand is Nouryon 920DU20).

[0085] This embodiment provides a preparation method of the electromagnetic shielding film material, and the specific steps are the same as those of Embodiment 1.

[0086] Comparative Example 1

[0087] This comparative example provides an electromagnetic shielding film material, which is only different from that of Embodiment 1 in that the mass percentage of the polyurethane is 28%, the mass percentage of the thermally expandable microspheres is 2%, and the other components, dosages and preparation methods are the same as those of Embodiment 1.

[0088] Comparative Example 2

[0089] This comparative example provides an electromagnetic shielding film material, which is only different from that of Example 1 in that the mass percentage content of the polyurethane is 5%, the mass percentage content of the thermally expandable microspheres is 25%, and the other components, dosages and preparation methods are the same as those of Example 1.

[0090] Comparative Example 3

[0091] This comparative example provides an electromagnetic shielding film material, which is only different from that of Example 1 in that the mass percentage content of the polyurethane is 20%, the mass percentage content of the conductive particles is 80%, there are no thermally expandable microspheres, and the preparation method is the same as that of Example 1.

[0092] Comparative Example 4

[0093] This comparative example provides an electromagnetic shielding film material, which is only different from that of Example 1 in that the thermally expandable microspheres are replaced with an equal mass of ultraviolet curable (UV) glue (Yuntong AVENTK-6011), and the preparation method is the same as that of Example 1.

[0094] Performance Test

[0095] (1) Debonding performance: The electromagnetic shielding film materials provided in Examples 1 to 10 and Comparative Examples 1 to 4 were hot-pressed (hot-pressing temperature was 80 °C) on the main board and cured. After the electromagnetic shielding film was completely cured, it was placed at a certain temperature (the temperature was 40 °C higher than the starting expansion temperature of the corresponding thermally expandable microspheres) for high-temperature expansion. During this process, the electromagnetic shielding film material expanded due to heat and separated from the main board. Finally, after cleaning (cleaning with a brush and an air gun), a main board without residues of the electromagnetic shielding film was obtained; the time when the electromagnetic shielding film material separated from the main board was recorded as the debonding time; and whether there was any residue of the electromagnetic shielding film material on the surface of the cleaned main board was observed.

[0096] Among them, the preparation method and the schematic diagram of the debonding process of the electromagnetic shielding film material provided in Example 1 are as Figure 1 shown.

[0097] The effect of the debonding process of the electromagnetic shielding film material provided in Example 1 is as Figure 2 shown; it can be Figure 2 seen that there is no residue of the electromagnetic shielding film material on the surface of the cleaned main board, and the electromagnetic shielding film material provided by the present invention can be effectively separated from the substrate.

[0098] (2) Electromagnetic shielding effectiveness: The electromagnetic shielding film material was cut into samples with a length and width of 10 cm each, and the electromagnetic shielding effectiveness of the material was tested using a shielding effectiveness tester (Beijing Dingrong DR-S02) and a network vector analyzer (Keysight Technologies N5227B). The test frequency range was 0.03 - 3 GHz.

[0099] The specific test results are shown in Table 1.

[0100] Table 1

[0101] Film thickness (μm) Debonding time (s) Presence or absence of residue Electromagnetic shielding effectiveness (dB) Example 1 70 75 None 89 Example 2 78 116 None 90 Example 3 82 77 None 80 Example 4 84 117 None 83 Example 5 74 80 None 91 Example 6 73 74 None 84 Example 7 74 92 None 91 Example 8 74 75 None 91 Example 9 72 73 None 92 Example 10 75 74 None 93 Comparative Example 1 68 72 Yes 60 Comparative Example 2 77 74 None 92 Comparative Example 3 76 No reaction Yes 85 Comparative Example 4 66 No reaction Yes 57

[0102] As can be seen from Table 1, in Examples 1 to 10, the de-bonding of the electromagnetic shielding film material on the main board can be achieved, and the electromagnetic shielding effectiveness is maintained above 80 dB, that is, more than 99.999999% of the electromagnetic waves can be shielded; there is no film material residue on the surface of the main board after de-bonding.

[0103] From Examples 1-4 and 7, it can be seen that using specific types of thermally expandable microspheres is beneficial to further shorten the de-bonding time and improve the de-adhesion effect.

[0104] In Comparative Example 1, the content of the thermally expandable microspheres is only 2%. After heat treatment, there are a large number of residues on the main board, which are difficult to completely remove and affect the use. And in Comparative Example 1, although the de-bonding of the electromagnetic shielding film material can be achieved, the adhesion of the material itself on the main board is very weak, affecting the reliability of the material on the device and making it difficult to be used in actual electronic products.

[0105] In Comparative Example 2, the content of the thermally expandable microspheres is too high. Although it has good de-adhesion performance and electromagnetic shielding performance; the obtained film material has poor mechanical properties, poor stretchability and low strength.

[0106] In Comparative Example 3, since the material does not contain thermally expandable microspheres, the material has no reaction to heat treatment and cannot achieve de-bonding on the main board.

[0107] In Comparative Example 4, since the UV glue needs light treatment to achieve de-bonding, and the conductive particles will block the propagation of light, the material cannot achieve de-bonding on the main board either, and it will also cause the deterioration of the electromagnetic shielding performance.

[0108] The specific embodiments described above further elaborate on the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A fast debonding electromagnetic shielding film material, characterized in that: Calculated by mass percentage, the electromagnetic shielding film material comprises 8-30% of thermal adhesive resin, 60-80% of conductive particles and 5-20% of thermal expansion microspheres.

2. The electromagnetic shielding film material according to claim 1, characterized in that: The thermal adhesive resin includes any one of epoxy resin, polymethyl methacrylate resin, polyurethane resin, phenolic resin, phenoxy resin, ethylene-vinyl acetate copolymer resin, acrylic resin or polyamide resin, or a combination of at least two of them.

3. The electromagnetic shielding film material according to claim 1 or 2, characterized in that: The conductive particles include any one or more of flake conductive particles, spherical conductive particles, and dendrite conductive particles, and a combination of at least two of the above; Preferably, the conductive particles include any one or more of gold powder, silver powder, copper powder, silver-coated copper powder, nickel powder, iron powder, aluminum powder, carbon black, graphite or MXene powder.

4. The electromagnetic shielding film material according to any one of claims 1 to 3, characterized in that: The initial particle size of the heat-expandable microspheres is 5 to 70 μm, and more preferably 5 to 25 μm.

5. The electromagnetic shielding film material according to any one of claims 1 to 4, characterized in that: The initial expansion temperature of the heat-expandable microspheres is 100-220°C; more preferably, the initial expansion temperature is 130-200°C.

6. The electromagnetic shielding film material according to any one of claims 1 to 5, characterized in that: The conductive particles and the heat-expandable microspheres in the electromagnetic shielding film material are randomly distributed, and / or the conductive particles are coated on the surface of the heat-expandable microspheres; Preferably, the mass ratio of the conductive particles to the heat-expandable microspheres is (3.5-15):

1.

7. A method for preparing a fast debonding electromagnetic shielding film material according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: The heat adhesive resin, the conductive particles and the heat expandable microspheres are mixed to obtain a mixture; and the mixture is molded to obtain the electromagnetic shielding film material.

8. The preparation method according to claim 7, characterized in that: The mixing method includes solution mixing or melt mixing; Preferably, the solution mixing method comprises: mixing a thermal adhesive resin with a solvent to obtain a thermal adhesive resin solution; then mixing the thermal adhesive resin solution with conductive particles and heat-expandable microspheres to obtain a mixture; Preferably, the melt mixing method comprises: heating and melting the heat adhesive resin, and then adding the conductive particles and the heat expandable microspheres thereto and mixing them to obtain a mixture.

9. The preparation method according to claim 7 or 8, characterized in that: The molding method includes coating molding and / or casting molding.

10. An electronic device, characterized in that: The electronic device comprises a substrate and the rapid debonding electromagnetic shielding film material according to any one of claims 1 to 6 arranged on the surface of the substrate.

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