Conductive adhesive tape and electronic equipment

Abstract

The conductive adhesive tape comprises a conductive base film layer, a first adhesive layer, a second adhesive layer and a release layer, the first adhesive layer and the second adhesive layer are formed on the two sides of the conductive base film layer, the conductive base film layer is prepared from, by weight, 50%-65% of SEBS rubber, 5%-10% of C9 resin, 1%-2% of anti-aging agent and the balance conductive filler, and the melt index of the SEBS rubber at 200 DEG C / 5 kg is smaller than or equal to 3 g / 10 min. According to the scheme, the composition is simple, optimization and improvement of the vertical impedance and the anti-aging characteristic are achieved by optimizing the composition design of the conductive base film layer, the application requirements of electronic products are met, and the composite film can be suitable for the heating environment under long-term application of the electronic products.

Description

Technical Field

[0001] The present invention belongs to the technical field of tapes, and particularly relates to a conductive tape and an electronic device. Background Art

[0002] Conductive tapes are mainly used for EMI / RFI shielding, conduction, and static electricity release, and are widely used in electronic products such as mobile phones and laptops; they are mostly used in combination with conductive fabrics, conductive foams, conductive copper, aluminum foils, etc. As electronic products become thinner and thinner, the conductive materials used in electronic products are also getting thinner, the required impedance value is getting lower, and the bonding area is getting smaller.

[0003] For the bonding of conductive foam, the minimum required width on the market is about 1 mm at present. This requires cutting the tape into finished products with the same width for bonding. Since the conductive adhesive is a substrate-free adhesive and the adhesive film lacks sufficient support, when cutting small-sized tapes, it is easy to encounter problems such as sticking to the knife or pulling the glue due to the glue overflowing to the side during unwinding, affecting normal use. If the glue is made very hard, the problems of sticking to the knife and glue overflow can be solved, but the foam belongs to a porous structure with an uneven plane, and a very hard glue cannot stick to the foam. Therefore, there are few conductive adhesives on the market that can meet the requirements of small-area bonding of conductive foam. Moreover, when bonding in a small area, due to the small adhesive surface area and few conductive paths, the general resistance is very high, and it is difficult to meet the low-heat requirement.

[0004] Therefore, in view of the above technical problems, it is necessary to provide a conductive tape and an electronic device.

[0005] The information disclosed in this background art section is only intended to enhance the overall understanding of the present invention and should not be regarded as an admission or any form of implication that this information constitutes prior art already known to those of ordinary skill in the art. Summary of the Invention

[0006] The purpose of the present invention is to provide a conductive tape and an electronic device.

[0007] In order to achieve the above purpose, the technical solution provided by a specific embodiment of the present invention is as follows:

[0008] A conductive tape, comprising a conductive base film layer, a first adhesive layer and a second adhesive layer formed on both sides of the conductive base film layer, and a release layer. The raw materials of the conductive base film layer include, by wt%: 50% - 65% of SEBS rubber, 5% - 10% of C9 resin, 1% - 2% of antioxidant, and the balance of conductive filler, wherein the melt index of SEBS rubber, 200°C / 5 kg: ≤ 3 g / 10 min.

[0009] In one or more embodiments of the present invention, the weight ratio of styrene / rubber in the raw materials of SEBS rubber is 1 / 3 - 2 / 3. Preferably, the rubber is an ethylene-butene copolymer.

[0010] In one or more embodiments of the present invention, the diblock content in SEBS rubber is not more than 5 wt%.

[0011] In one or more embodiments of the present invention, the anti-aging agent is selected from zinc dibutyldithiocarbamate and 2,6-di-tert-butyl-p-cresol.

[0012] In one or more embodiments of the present invention, the conductive filler is selected from: spherical conductive filler, dendritic conductive filler, fibrous conductive filler. The conductive filler is surface-treated with a silane coupling agent (such as KH-550, addition amount 0.5%).

[0013] Preferably, the 30-35 μm spherical filler accounts for 5% - 8% of the total amount of raw materials by wt%. It penetrates and breaks through the thickness limit of the adhesive layer.

[0014] Preferably, the 15-20 μm dendritic filler accounts for 15% - 20% of the total amount of raw materials by wt%. A three-dimensional conductive framework is established. The dendritic filler can be graphite microfibers, etc.

[0015] Preferably, the 10-18 μm fibrous filler accounts for 9.5% - 19% of the total amount of raw materials by wt%. Vertical and horizontal conductive channels are formed. The fibrous filler can be copper whiskers.

[0016] In one or more embodiments of the present invention, the spherical conductive filler is selected from nickel powder, silver powder, copper powder, nickel-coated graphite conductive powder, silver-coated aluminum conductive powder, silver-coated copper conductive powder, silver-coated nickel conductive powder.

[0017] In one or more embodiments of the present invention, the diameter of the spherical conductive filler is greater than the total thickness of the conductive base film layer, the first adhesive layer and the second adhesive layer.

[0018] In one or more embodiments of the present invention, the diameter of the spherical conductive filler is 5-30 μm larger than the total thickness. This range of thickness helps to ensure the electrical conductivity and thermal stability, as demonstrated in the study of transparent conductive films.

[0019] In one or more embodiments of the present invention, the diameter of the dendritic conductive filler and / or the fibrous conductive filler is less than 20 μm.

[0020] In one or more embodiments of the present invention, the electronic device includes electronic components and a conductive tape for pasting the electronic components.

[0021] Compared with the prior art, the conductive tape and the electronic device of the present invention have a simple composition. By optimizing the composition design of the conductive base film layer, the vertical impedance and the anti-aging characteristics are optimized and improved, meeting the application requirements of electronic products and being able to withstand the heating environment during the long-term application of electronic products. Detailed implementation mode

[0022] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0023] The conductive tape of the present invention includes an adhesive layer, a conductive base film layer, and an adhesive layer, and a release paper / membrane layer on at least one side, and its total thickness ≥ 60 μm; the conductive base film layer is composed of the following mass ratio: SEBS rubber 50% - 65%, C9 resin 5% - 10%, antioxidant 1% - 2%, and the balance is conductive filler; the high strength and high hardness of SEBS rubber provide the supporting effect of the base film layer, its tensile strength is greater than 25 MPa (ASTM D412), the styrene / rubber weight ratio is between 1 / 3 and 4 / 6, the diblock content is less than 5%, and the melt index (MFR, 200 °C / 5 kg) ≤ 3; the resin makes the base film layer have a certain viscosity and promotes the combination of the base film layer and the surface adhesive layer. The antioxidant is 1% - 2%, and the antioxidant is one or a combination of two of zinc dibutyldithiocarbamate or 2,6-di-tert-butyl-p-cresol, which prevents the performance from deteriorating after the rubber ages for a long time; the conductive filler includes spherical conductive filler, dendritic conductive filler, and fibrous conductive filler. The weight ratios of the three forms in the base film layer are: spherical conductive filler 5% - 8%, dendritic conductive filler 15% - 20%, and fibrous conductive filler 9.5% - 19%. The conductive material can be one or several of nickel powder, silver powder, copper powder, nickel-coated graphite conductive powder, silver-coated aluminum conductive powder, silver-coated copper conductive powder, and silver-coated nickel conductive powder. The diameters of the dendritic conductive filler and the fibrous conductive filler are less than 20 μm, and the diameter of the spherical conductive filler is greater than 5 - 30 μm of the total thickness of the conductive tape. The three forms of conductive filler are evenly distributed in the base film layer and can contact each other to form a conductive path, enabling the base film layer to have omnidirectional conductivity. Because the thickness of the spherical conductive filler exceeds the total thickness of the adhesive layer, it can connect the conductive foam and the other backing material through the surface adhesive layer during bonding, and can form a new conductive channel with other forms of conductive filler in the base film layer. The impedance is much lower than that of using only spherical conductive filler. According to the ASTM D257 method, the vertical impedance can be less than 0.05 mΩ / (1 mm * 10 mm).

[0024] The first / second adhesive layer is a polyacrylate adhesive or a rubber-based pressure-sensitive adhesive, and the two sides can be the same or different. The dry adhesive thickness of the conductive foam surface connection is ≥20μm. When the dry adhesive thickness of the 25μm PET film is 25μm, its viscosity is greater than 1.4kg / 25mm, and the initial adhesion force is ≥20#; it has good adhesion to foam materials.

[0025] The release paper / membrane layer is for better fixing the adhesive, and its aging release force of the adhesive surface is 30 - 150g / 25mm.

[0026] Example 1

[0027] The conductive tape of this example includes a first adhesive layer (polyacrylate adhesive, thickness 20μm), a conductive base film layer, a second adhesive layer (polyacrylate adhesive, thickness 20μm), and a release layer with a thickness of 12μm arranged in sequence. Among them:

[0028] The thickness of the conductive base film layer is controlled at 18μm. The raw materials of the conductive base film layer include, wt%: SEBS rubber (diblock content 5wt%) 50%, C9 resin 5%, antioxidant 1%, and conductive filler (the ratio is shown in Table 1) for the rest. The tensile strength of the base film layer is ≥27MPa (tested by ASTM D412).

[0029] Table 1 Matching scheme of conductive fillers

[0030]

[0031] The conductive base film layer adopts a three-stage mixing process:

[0032] First, mix SEBS rubber, C9 resin, and antioxidant, and mix them in a Banbury mixer at 120°C for 15min. Then add the conductive filler in sequence, and the addition order is: fibrous filler, dendritic filler, spherical filler. After continuing to mix for 30min, provide a twin-screw extruder and extrude and pelletize at an outlet temperature of 160 - 180°C. Finally, calender and form at 100°C with a four-roll calender.

[0033] The difference between Comparative Example 1 and Example 1 is only that: dendritic conductive filler and fibrous conductive filler are not added.

[0034] The difference between Comparative Example 2 and Example 1 is only that: spherical conductive filler is not added.

[0035] Table 2 Test data

[0036]

[0037] Example 2

[0038] The conductive tape of this embodiment includes a first adhesive layer (with a thickness of 25 μm), a conductive base film layer, a second adhesive layer (with a thickness of 25 μm), and a release layer with a thickness of 12 μm, which are arranged in sequence. Among them:

[0039] The thickness of the conductive base film layer is controlled at 15 μm. The raw materials of the conductive base film layer include, by wt%: 57% of SEBS rubber (the diblock content is 4 wt%), 7% of C9 resin, 1.5% of antioxidant, and the balance is conductive filler (the ratio is shown in Table 3). The tensile strength of the base film layer meets the ASTM D412 standard, and the test results show that its tensile strength ≥ 27 MPa.

[0040] Table 3 Matching scheme of conductive filler

[0041]

[0042]

[0043] The conductive base film layer adopts a three-stage mixing process:

[0044] First, mix SEBS rubber, C9 resin, and antioxidant, and mix them in a Banbury mixer at 120 °C for 15 min. Then add the conductive filler in sequence. The addition order is: fibrous filler, dendritic filler, spherical filler. After continuing to mix for 30 min, provide a twin-screw extruder and extrude and pelletize at an outlet temperature of 160 - 180 °C. Finally, calender and form at 100 °C with a four-roll calender.

[0045] The difference between Comparative Example 3 and Example 2 is only that: dendritic conductive filler and fibrous conductive filler are not added.

[0046] The difference between Comparative Example 4 and Example 2 is only that: spherical conductive filler is not added.

[0047] Table 4 Test data

[0048]

[0049] Example 3

[0050] The conductive tape of this embodiment includes a first adhesive layer (with a thickness of 30 μm), a conductive base film layer, a second adhesive layer (with a thickness of 30 μm), and a release layer with a thickness of 12 μm, which are arranged in sequence. Among them:

[0051] The thickness of the conductive base film layer is controlled at 21 μm. The raw materials of the conductive base film layer include, by wt%: 65% of SEBS rubber (the diblock content is 3 wt%), 10% of C9 resin, 2% of antioxidant, and the balance is conductive filler (the ratio is shown in Table 5). The tensile strength of the base film layer meets the ASTM D412 standard, and the test results show that its tensile strength ≥ 27 MPa.

[0052] Table 5 Matching Scheme of Conductive Filler

[0053]

[0054] The conductive base film layer adopts a three - stage mixing process:

[0055] First, mix SEBS rubber, C9 resin, and antioxidant, and mix them in a kneader at 120°C for 15 min. Then, add the conductive fillers in sequence. The adding order is: fibrous filler, dendritic filler, spherical filler. After continuing to mix for 30 min, provide a twin - screw extruder and extrude and pelletize at an outlet temperature of 160 - 180°C. Finally, calender and form at 100°C with a four - roll calender.

[0056] The difference between Comparative Example 5 and Example 3 is only that: dendritic conductive filler is not added.

[0057] The difference between Comparative Example 6 and Example 3 is only that: spherical conductive filler is not added.

[0058] Table 6 Test Data

[0059]

[0060] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above - mentioned exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non - restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention.

[0061] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A conductive tape comprising a conductive base film layer, a first adhesive layer and a second adhesive layer formed on both sides of the conductive base film layer, and a release layer, characterized in that: The raw materials of the conductive base film layer include, by weight: 50% to 65% of SEBS rubber, 5% to 10% of C9 resin, 1% to 2% of antioxidant, and the balance of conductive filler, wherein the melting index of the SEBS rubber is 200°C / 5kg: ≤3g / 10min.

2. The conductive tape according to claim 1, characterized in that: The weight ratio of styrene to rubber in the raw materials of the SEBS rubber is 1 / 3-2 / 3.

3. The conductive tape according to claim 2, characterized in that: The diblock content in the SEBS rubber is not more than 5wt%.

4. The conductive tape according to claim 1, characterized in that: The antioxidant is selected from zinc dibutylcarbamate and 2,6-di-tert-butyl-p-cresol.

5. The conductive tape according to claim 1, characterized in that: The conductive filler is selected from: spherical conductive filler, dendritic conductive filler, and fibrous conductive filler.

6. The conductive tape according to claim 5, characterized in that: The spherical conductive filler is selected from nickel powder, silver powder, copper powder, nickel-coated graphite conductive powder, silver-coated aluminum conductive powder, silver-coated copper conductive powder, and silver-coated nickel conductive powder.

7. The conductive tape according to claim 6, characterized in that: The diameter of the spherical conductive filler is greater than the total thickness of the conductive base film layer, the first adhesive layer and the second adhesive layer.

8. The conductive tape according to claim 7, characterized in that: The diameter of the spherical conductive filler is 5-30 μm larger than the total thickness.

9. The conductive tape according to claim 5, characterized in that: The diameter of the dendritic conductive filler and / or fibrous conductive filler is less than 20 μm.

10. An electronic device comprising an electronic component and the conductive tape according to any one of claims 1 to 9 for bonding the electronic component.

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