Anisotropic conductive film based on ink-jet printing and preparation method thereof

Abstract

The invention is suitable for the technical field of anisotropic conductive film manufacturing, and provides an anisotropic conductive film based on ink-jet printing and a preparation method thereof, and the method comprises the following steps: S1, preparing conductive ink which comprises conductive particles, a binder and a solvent; s2, printing the conductive ink to the surface of a base material through ink-jet printing equipment according to a preset pattern and a preset interval to form a conductive particle array; s3, carrying out curing treatment on the conductive particle array; and S4, laminating and covering a bonding layer on the cured conductive particle array to obtain the anisotropic conductive film, according to the invention, a conductive film manufacturing process with low cost, digitization and strong controllability can be realized, the electrical property stability and the connection repeatability of a product are improved, and the requirements of micro-spacing electronic packaging, high-definition display devices and the like on high-precision particle arrangement are met.

Description

Technical Field

[0001] This invention relates to the field of anisotropic conductive film manufacturing technology, specifically an anisotropic conductive film based on inkjet printing and its preparation method. Background Technology

[0002] Anisotropic conductive films are adhesive materials that can simultaneously achieve electrical connections and mechanical bonding between microelectronic components, and are widely used in display panels, semiconductor packaging and other fields.

[0003] In existing technologies, conductive particles are generally randomly dispersed in the adhesive layer through coating or mixing. This method has the following drawbacks: Uneven particle spacing leads to poor contact. Large resistance fluctuations lead to poor connection reliability. It is difficult to adapt to the requirements of high resolution and micro-pitch connection.

[0004] Therefore, in view of the above situation, there is an urgent need to provide an anisotropic conductive film based on inkjet printing and its preparation method to overcome the shortcomings in current practical applications. Summary of the Invention

[0005] The purpose of this invention is to provide an anisotropic conductive film based on inkjet printing and its preparation method, effectively solving the problems in the background art.

[0006] This invention is achieved by a method for preparing anisotropic conductive films based on inkjet printing, the method comprising the following steps: S1: Prepare conductive ink, wherein the conductive ink comprises conductive particles, binder and solvent; S2: The conductive ink is printed onto the surface of a substrate in a predetermined pattern and spacing using an inkjet printer to form a conductive particle array; S3: The conductive particle array is solidified; S4: An adhesive layer is laminated onto the cured conductive particle array to obtain the anisotropic conductive film.

[0007] As a further aspect of the present invention: in step S3, the curing process includes: Preliminary curing and complete curing; The initial curing process involves mild heat treatment to evaporate the solvent and initially shape the ink droplets. The complete curing process allows the adhesive to fully cross-link, forming a stable conductive particle adhesion layer.

[0008] As a further aspect of the present invention: the initial curing temperature is 50°C to 80°C, and the time is 30 seconds to 5 minutes; The complete curing method is either thermosetting or UV curing.

[0009] As a further aspect of the present invention: when the complete curing is heat curing, the curing temperature is 100°C to 150°C and the time is 10 minutes to 60 minutes; When the complete curing is achieved through UV light curing, a UV-LED light source with a wavelength of 365nm or 385nm is used, and the irradiation energy is 500mJ / cm². 2 Up to 2000mJ / cm 2 .

[0010] As a further aspect of the present invention, the preliminary curing is carried out in an inert gas atmosphere or a vacuum environment.

[0011] As a further aspect of the present invention: the conductive particles are polymer particles coated with silver, gold or nickel, with a particle spacing of 3–100 μm.

[0012] As a further aspect of the present invention, the adhesive is a UV-curable resin or a thermosetting resin.

[0013] As a further aspect of the present invention: the UV-curable resin or thermosetting resin is an epoxy resin or an acrylic resin.

[0014] As a further aspect of the present invention, the solvent is methyl ethyl ketone or ethylene glycol ether solvent.

[0015] The present invention also provides an anisotropic conductive film based on inkjet printing, which is prepared by the above-described preparation method.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: Compared with traditional disordered dispersion methods, this invention can achieve higher particle positioning accuracy; It enables selective connection between micro-pitch circuits; Inkjet printing enables digital manufacturing and is suitable for small-batch production of multiple varieties. Simplify manufacturing processes, improve process flexibility, and shorten production cycles. Detailed Implementation

[0017] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] The present invention will be further explained below with reference to specific embodiments.

[0019] This invention provides a method for preparing anisotropic conductive films based on inkjet printing, the method comprising the following steps: S1: Prepare conductive ink, wherein the conductive ink comprises conductive particles, binder and solvent; S2: The conductive ink is printed onto the surface of a substrate in a predetermined pattern and spacing using an inkjet printer to form a conductive particle array; S3: The conductive particle array is solidified; The curing process includes: Preliminary curing and complete curing; The initial curing process involves gentle heat treatment to evaporate the solvent and initially shape the ink droplets, preventing particle drift. The complete curing process allows the adhesive to fully cross-link, forming a stable conductive particle adhesion layer. The initial curing temperature is 50°C to 80°C, and the time is 30 seconds to 5 minutes; The complete curing method is either thermal curing or UV curing; When the complete curing is heat curing, the curing temperature is 100°C to 150°C and the time is 10 minutes to 60 minutes; When the complete curing is achieved through UV light curing, a UV-LED light source with a wavelength of 365nm or 385nm is used, and the irradiation energy is 500mJ / cm². 2 Up to 2000mJ / cm 2 ; The initial curing is carried out in an inert gas atmosphere or vacuum environment to suppress the rapid evaporation of solvent that could lead to abnormal ink droplet morphology. S4: An adhesive layer is laminated onto the cured conductive particle array to obtain the anisotropic conductive film.

[0020] In this embodiment, the conductive particles are polymer particles coated with silver, gold or nickel, such as gold-plated polymer spheres, nickel particles, silver-coated spheres, etc., with a particle spacing of 3–100 μm. Adhesive: UV-curable or thermosetting resin (such as epoxy resin, acrylic resin, etc.); Solvent: Inkjet-compatible solvents with good dispersibility (methyl ethyl ketone, such as ethylene glycol ethers); Inkjet printing process: Using inkjet printing equipment, ink droplets containing conductive particles are printed on the surface of a substrate in a specified pattern and spacing; Control the diameter and spacing of the printed dots (e.g., below 20μm); After printing, UV or thermal curing is performed.

[0021] Lamination and encapsulation steps: Lamination is performed with the upper adhesive film (NCF layer) or protective film to complete the preparation of ACF.

[0022] This invention also provides an anisotropic conductive film based on inkjet printing, which is prepared by the above-described method.

[0023] The present invention provides a method for manufacturing anisotropic conductive films by precisely arranging conductive particles at designated positions using inkjet printing technology. This method achieves a low-cost, digital, and highly controllable conductive film manufacturing process, improves the electrical performance stability and connection repeatability of products, and meets the requirements of micro-pitch electronic packaging, high-definition display devices, and other applications for high-precision particle arrangement.

[0024] Example 1: 1. Use silver-coated polymer spheres with an average diameter of 5μm, and mix them with epoxy resin adhesive; 2. Adjust the viscosity to 10–15 cP and use a piezoelectric inkjet head (PIJ) for printing; 3. Arrange dotted patterns on the NCF membrane at the desired spacing (less than 50 μm); 4. Thermosetting; 5. NCF lamination.

[0025] Test results: Average contact resistance: 0.35Ω; Defect rate: less than 0.2%; Particle positioning deviation: within ±3μm.

[0026] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing anisotropic conductive films based on inkjet printing, characterized in that, The method includes the following steps: S1: Prepare conductive ink, wherein the conductive ink comprises conductive particles, binder and solvent; S2: The conductive ink is printed onto the surface of a substrate in a predetermined pattern and spacing using an inkjet printer to form a conductive particle array; S3: The conductive particle array is solidified; S4: An adhesive layer is laminated onto the cured conductive particle array to obtain the anisotropic conductive film.

2. The method for preparing anisotropic conductive film based on inkjet printing according to claim 1, characterized in that, In step S3, the curing process includes: Preliminary curing and complete curing; The initial curing process involves mild heat treatment to evaporate the solvent and initially shape the ink droplets. The complete curing process allows the adhesive to fully cross-link, forming a stable conductive particle adhesion layer.

3. The method for preparing anisotropic conductive film based on inkjet printing according to claim 2, characterized in that, The initial curing temperature is 50°C to 80°C, and the time is 30 seconds to 5 minutes; The complete curing method is either thermosetting or UV curing.

4. The method for preparing anisotropic conductive film based on inkjet printing according to claim 3, characterized in that, When the complete curing is heat curing, the curing temperature is 100°C to 150°C and the time is 10 minutes to 60 minutes; When the complete curing is achieved through UV light curing, a UV-LED light source with a wavelength of 365nm or 385nm is used, and the irradiation energy is 500mJ / cm². 2 Up to 2000mJ / cm 2 .

5. The method for preparing anisotropic conductive film based on inkjet printing according to claim 2, characterized in that, The initial curing is carried out in an inert gas atmosphere or in a vacuum environment.

6. The method for preparing anisotropic conductive film based on inkjet printing according to claim 1, characterized in that, The conductive particles are polymer particles coated with silver, gold or nickel, with a particle spacing of 3–100 μm.

7. The method for preparing anisotropic conductive film based on inkjet printing according to claim 1, characterized in that, The adhesive is a UV-curable resin or a thermosetting resin.

8. The method for preparing anisotropic conductive film based on inkjet printing according to claim 7, characterized in that, The UV-curable resin or thermosetting resin is epoxy resin or acrylic resin.

9. The method for preparing anisotropic conductive film based on inkjet printing according to claim 1, characterized in that, The solvent is methyl ethyl ketone or ethylene glycol ether solvent.

10. An anisotropic conductive film based on inkjet printing, characterized in that, It is prepared by the preparation method according to any one of claims 1-9.