Anisotropic conductive adhesive film and manufacturing method thereof

Abstract

The invention relates to a novel anisotropic conductive adhesive film and a manufacturing method thereof, the conductive adhesive film comprises a first carrier film layer, a conductive adhesive layer, a conductive cloth layer and a second carrier film layer, the conductive adhesive layer comprises a first conductive adhesive layer and a second conductive adhesive layer, the second conductive adhesive layer is formed on the upper surface of the second carrier film layer, and the conductive cloth layer is formed on the upper surface of the second carrier film layer. The conductive cloth layer is formed on the upper surface of the second conductive adhesive layer, and the first conductive adhesive layer is formed on the upper surface of the conductive cloth layer; the first carrier film layer is formed on the upper surface of the first conductive adhesive layer; the conductive adhesive layer is composed of a base material layer and a material layer, the base material layer is formed by weaving carbon fibers, and the material layer is composed of nanowires, metal conductive particles and adhesive resin. The novel multilayer anisotropic conductive film not only has low resistivity and good conductivity, but also has excellent cohesiveness after application.

Description

Technical Field

[0001] This invention belongs to the field of conductive adhesive film technology, and more specifically, relates to an anisotropic conductive adhesive film. Background Technology

[0002] Typically, anisotropic conductive film (ACF) combines unidirectional conductivity with adhesive bonding, and is currently used in thermosetting bonding machines for microcircuit connections in COG (chip-on-glass), TCP (tape carrier package) / COF (chip-on-film), and FPC (flexible printed circuit). However, with the recent trend towards miniaturization, thinning, and flexibility in electronic products (such as mobile phones, tablets, and wearable devices), more and more LCD displays and touchscreens are using optical films or ultra-thin glass as microcircuit substrates. Anisotropic conductive film utilizes conductive particles to connect the electrodes between the IC chip and the substrate, creating conductivity while preventing short circuits between adjacent electrodes. This achieves conductivity only in the z-axis direction, solving the problem of connecting fine wires that traditional connectors could not handle.

[0003] Among them, polyimide copper foil substrates are mostly used for flexible printed circuit boards (PCBs), and they are generally divided into single-sided or double-sided boards. The application of polyimide copper foil substrates is usually limited by the composition and thickness of the polyimide material. Wiring materials for small electronic products mostly use flexible printed circuit boards with high design freedom and good flexibility. While developing towards high speed and high flexibility, there are corresponding requirements for thickness and workability. This places higher demands on the conductive film of flexible printed circuit boards, requiring not only good conductivity and electromagnetic wave shielding, but also good flexibility, bending resistance, and toughness. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a novel anisotropic conductive film, which has low resistivity, excellent conductivity, strong adhesion, and superior connectivity.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] This invention provides a novel anisotropic conductive adhesive film, comprising a first carrier film layer, a conductive adhesive layer, a conductive cloth layer, and a second carrier film layer. The conductive adhesive layer includes a first conductive adhesive layer and a second conductive adhesive layer, the second conductive adhesive layer being formed on the upper surface of the second carrier film layer, the conductive cloth layer being formed on the upper surface of the second conductive adhesive layer, the first conductive adhesive layer being formed on the upper surface of the conductive cloth layer, and the first carrier film layer being formed on the upper surface of the first conductive adhesive layer. The conductive adhesive layer consists of a substrate layer and a material layer filled within the substrate layer. The substrate layer is woven from carbon fibers, and the material layer is composed of nanowires, conductive metal particles, and an adhesive resin.

[0007] Furthermore, the nanowire is a nickel alloy, and the diameter of the nanowire is 80-100 nanometers;

[0008] Furthermore, the metal conductive particles are polymer microsphere composite conductive particles formed by depositing one or more conductive metal layers of Au, Ag, Cu, Ni, Pt, and Pd on the surface of polymer microspheres;

[0009] Furthermore, the aforementioned polymer microspheres are one or more of polystyrene microspheres, polyacrylate microspheres, polyethylene microspheres, polypropylene microspheres, polyester microspheres, and modified resin microspheres;

[0010] Furthermore, the particle size of the above-mentioned polymer microsphere composite conductive particles is 3-10 μm;

[0011] The adhesive comprises a mixture of epoxy acrylate, butyl acrylate, tripropylene glycol diacrylate, initiator 1173, and cationic photoinitiator;

[0012] Furthermore, the epoxy acrylate accounts for 50-70 parts by weight of the entire adhesive formulation;

[0013] Furthermore, the butyl acrylate and tripropylene glycol diacrylate account for 10-40 parts by weight of the entire adhesive formulation;

[0014] Furthermore, the mixture of initiator 1173 and cationic photoinitiator accounts for 3-5 parts by weight of the entire adhesive formulation;

[0015] Furthermore, the mixture ratio of the initiator 1173 and the cationic photoinitiator is preferably 1:1;

[0016] Furthermore, the cationic photoinitiator is preferably an iodonium salt or a thiodonium salt compound;

[0017] Furthermore, there are no particular restrictions on the other components mentioned above, and they can be selected appropriately according to the purpose. Examples include plasticizers, coupling agents, polymerization inhibitors, and fillers.

[0018] Furthermore, the present invention also provides a method for manufacturing the novel anisotropic conductive film, which is carried out according to the following steps:

[0019] Step 1: Weave carbon fibers into a substrate layer;

[0020] Step 2: Add the nickel alloy nanowires, metal conductive particles, butyl acrylate, and tripropylene glycol diacrylate to a three-roll mixer according to the weight proportions. The three-roll mixer rotates at 50-60 rpm for 10-20 minutes, and then stands for 0.5-0.8 hours to mix it evenly, to obtain mixture A.

[0021] Step 3: Add the mixture of epoxy acrylate, initiator 1173 and cationic photoinitiator to a three-roll mixer according to the weight ratio and mix it with the mixture A obtained in Step 2. The three-roll mixer rotates at 120-150 rpm for 40-60 minutes to make it evenly mixed. Then let it stand for 12-24 hours to obtain mixture B.

[0022] Step 4: The mixture B obtained in Step 2 is coated onto the substrate layer, and cured using a high-pressure mercury lamp to obtain the first conductive adhesive layer and the second conductive adhesive layer;

[0023] Step 5: Attach a conductive cloth layer to the surface of one of the first and second conductive adhesive layers obtained in step 4, and then press it with the other layer at a pressing temperature of 200-250℃ to obtain the novel anisotropic conductive film.

[0024] Furthermore, the anisotropic conductive film obtained by the manufacturing method and formula described in this invention exhibits excellent connectivity and good application stability. Detailed Implementation

[0025] The specific embodiments of the present invention will be described in further detail below with reference to the examples. These examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0026] Example: A novel anisotropic conductive adhesive film includes a first carrier film layer, a conductive adhesive layer, a conductive cloth layer, and a second carrier film layer. The conductive adhesive layer includes a first conductive adhesive layer and a second conductive adhesive layer. The second conductive adhesive layer is formed on the upper surface of the second carrier film layer. The conductive cloth layer is formed on the upper surface of the second conductive adhesive layer. The first conductive adhesive layer is formed on the upper surface of the conductive cloth layer. The first carrier film layer is formed on the upper surface of the first conductive adhesive layer.

[0027] The conductive adhesive layer consists of a substrate layer and a material layer filled in the substrate layer. The substrate layer is woven from carbon fibers, and the material layer consists of nanowires, conductive metal particles, and adhesive resin.

[0028] The nanowires, conductive metal particles, and adhesive resin fill the mesh of the substrate layer and cover the upper and lower surfaces of the substrate layer.

[0029] The formulations for Examples 1 to 6 are shown in Table 1 below:

[0030] Table 1

[0031]

[0032]

[0033] The method for preparing the novel anisotropic conductive film described in Examples 1 to 6 is carried out according to the following steps:

[0034] Step 1: Weave carbon fibers into a substrate layer;

[0035] Step 2: Add the nickel alloy nanowires, metal conductive particles, butyl acrylate, and tripropylene glycol diacrylate to a three-roll mixer according to the weight proportions. The three-roll mixer rotates at 60 rpm for 15 minutes, and then stands for 0.5 hours to mix it evenly, to obtain mixture A.

[0036] Step 3: Add the mixture of epoxy acrylate, initiator 1173 and cationic photoinitiator to a three-roll mixer according to the weight ratio and mix it with the mixture A obtained in step 2. The three-roll mixer rotates at 120 rpm for 60 minutes to make it evenly mixed. Then let it stand for 12 hours to obtain mixture B.

[0037] Step 4: The mixture B obtained in Step 2 is coated onto the substrate layer, and cured using a high-pressure mercury lamp to obtain the first conductive adhesive layer and the second conductive adhesive layer;

[0038] Step 5: Attach a conductive cloth layer to the surface of one of the first and second conductive adhesive layers obtained in step 4, and then press it with the other layer at a pressing temperature of 200°C to obtain the novel anisotropic conductive film.

[0039] <On-resistance>

[0040] The initial on-resistance (Ω) of the joint is determined by the following method: the resistance (Ω) between the terminals of the joint is measured using a digital multimeter (model: F87-V, Fluke, USA). Specifically, the resistance is measured by the 4-terminal method when a current of 1mA flows through it.

[0041] <Adhesion>

[0042] The prepared anisotropic conductive film was aged at room temperature for 24 hours. Then, 100 small squares were formed by making one horizontal and one vertical cut using a cross-cutting tool. Next, the film was brushed five times diagonally with a brush. 3M 600 tape was then applied to the cuts and peeled off. The condition of the square areas was observed using a magnifying glass. The degree of coating adhesion to the substrate was assessed by evaluating the integrity of the coating within the squares. The more intact the coating within the squares, the stronger the adhesion.

[0043] The evaluation criteria are as follows:

[0044] A: The edges of the cut are completely smooth, and there is no peeling at the edges of the grid.

[0045] B: There is peeling at the intersection of the cuts.

[0046] The results obtained above are recorded in Table 2:

[0047] Table 2

[0048] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 On resistance 1.0 1.0 1.0 1.0 1.0 1.0 Adhesion A A A A A A

[0049] The novel anisotropic conductive film provided by this invention has excellent conductivity, strong adhesion, and excellent connectivity.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An anisotropic conductive adhesive film, comprising a first carrier film layer, a conductive adhesive layer, a conductive cloth layer, and a second carrier film layer, wherein the conductive adhesive layer comprises a first conductive adhesive layer and a second conductive adhesive layer, the second conductive adhesive layer being formed on the upper surface of the second carrier film layer, the conductive cloth layer being formed on the upper surface of the second conductive adhesive layer, the first conductive adhesive layer being formed on the upper surface of the conductive cloth layer, and the first carrier film layer being formed on the upper surface of the first conductive adhesive layer. The conductive adhesive layer comprises a substrate layer and a material layer filling the substrate layer. The substrate layer is woven from carbon fibers, and the material layer comprises nanowires, conductive metal particles, and an adhesive resin. The nanowires are nickel alloys with a diameter of 80-100 nanometers. The conductive metal particles are polymer microsphere composite conductive particles formed by depositing one or more conductive metal layers selected from Au, Ag, Cu, Ni, Pt, and Pd on the surface of polymer microspheres.

2. The anisotropic conductive adhesive film according to claim 1, characterized in that... The metal conductive particle polymer microspheres are one or more of polystyrene microspheres, polyacrylate microspheres, polyethylene microspheres, polypropylene microspheres, polyester microspheres, and modified resin microspheres, or a mixture thereof.

3. The anisotropic conductive film according to claim 1 or 2, characterized in that... The particle size of the polymer microsphere composite conductive particles is 3-10 μm.

4. The anisotropic conductive film according to claim 1, characterized in that... The adhesive comprises a mixture of epoxy acrylate, butyl acrylate, tripropylene glycol diacrylate, initiator 1173, and cationic photoinitiator.

5. The anisotropic conductive film according to claim 4, characterized in that... The epoxy acrylate accounts for 50-70 parts by weight of the entire adhesive formulation.

6. The anisotropic conductive film according to claim 4, characterized in that... The butyl acrylate and tripropylene glycol diacrylate comprise 10-40 parts by weight of the total adhesive formulation.

7. The anisotropic conductive film according to claim 4, characterized in that... The mixture of initiator 1173 and cationic photoinitiator accounts for 3-5 parts by weight of the entire adhesive formulation.

8. The anisotropic conductive film according to claim 4 or 7, characterized in that... The preferred ratio of the mixture of initiator 1173 and cationic photoinitiator is 1:

1.

9. The anisotropic conductive film according to claim 4, characterized in that... The cationic photoinitiator is an iodonium salt or a thiodonium salt compound.

10. A method for manufacturing the novel anisotropic conductive film, comprising the following steps: Step 1: Weave carbon fibers into a substrate layer; Step 2: Add the nickel alloy nanowires, metal conductive particles, butyl acrylate, and tripropylene glycol diacrylate to a three-roll mixer according to the weight proportions. The three-roll mixer rotates at 50-60 rpm for 10-20 minutes, and then stands for 0.5-0.8 hours to mix it evenly, to obtain mixture A. Step 3: Add the mixture of epoxy acrylate, initiator 1173 and cationic photoinitiator to a three-roll mixer according to the weight ratio and mix it with the mixture A obtained in Step 2. The three-roll mixer rotates at 120-150 rpm for 40-60 minutes to make it evenly mixed. Then let it stand for 12-24 hours to obtain mixture B. Step 4: The mixture B obtained in Step 2 is coated onto the substrate layer, and cured using a high-pressure mercury lamp to obtain the first conductive adhesive layer and the second conductive adhesive layer; Step 5: Attach a conductive cloth layer to the surface of one of the first and second conductive adhesive layers obtained in step 4, and then press it with the other layer at a pressing temperature of 200-250℃ to obtain the novel anisotropic conductive film.

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