An anisotropic conductive film with tunable conductive particle orientation along the XYZ axes and its preparation method.

Abstract

This invention belongs to the field of anisotropic conductive adhesive technology, and relates to an anisotropic conductive adhesive film with adjustable conductive particle orientation along the XYZ axis and its preparation method. This invention discloses an anisotropic conductive adhesive film with adjustable conductive particle orientation along the XYZ axis, comprising a PET release film layer and a conductive adhesive layer with an embedded porous mesh pad layer; the porous mesh pad layer in the conductive adhesive layer has a grid structure, with grooves formed at the intersections of the grid structure, and conductive particles are contained within the grooves. This invention also discloses a preparation method for the anisotropic conductive adhesive film with adjustable conductive particle orientation along the XYZ axis, the preparation method comprising: vertically blowing conductive particles into the grooves of the porous mesh pad layer with an airflow; then laminating the PET release film and the porous mesh pad layer by roll forming; then coating the porous mesh pad layer with a conductive adhesive liquid; drying to form a film; and finally slitting and packaging the anisotropic conductive adhesive film.

Description

Technical Field

[0001] This invention belongs to the field of anisotropic conductive adhesive technology, and relates to an anisotropic conductive adhesive film with adjustable conductive particle orientation along the XYZ axes and its preparation method. Background Technology

[0002] In existing technologies, the conductive particles in anisotropic conductive films (ACF) are mostly randomly distributed within the adhesive layer. In some areas, the density of conductive particles is too high, which may cause short circuits between adjacent electrodes. In other areas, the density of conductive particles is too low, which may cause high circuit impedance, open circuits, and ultimately circuit failure. Therefore, ordinary anisotropic conductive films are not suitable for precision electrode products.

[0003] The anisotropic conductive adhesive film disclosed in the Chinese patent application (publication number: CN105969237A) includes a glass plate, a polyimide film, and a resin layer. The resin layer has several through-holes. A conductive liquid containing conductive particles is dropped into the holes, and after removing the solvent, an anisotropic conductive adhesive layer is obtained. Although this method can control the position of the conductive particles in the XY direction, the preparation process is complex, not environmentally friendly, and easily leads to the waste of conductive particles. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned problems in the prior art by proposing an anisotropic conductive film that achieves adjustable orientation of conductive particles along the XYZ axes through a porous mesh layer with a grid structure.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] An anisotropic conductive film with adjustable conductive particle orientation along the XYZ axis, the anisotropic conductive film comprising a PET release film layer and a conductive adhesive layer with embedded porous mesh pad layer.

[0007] The porous mesh pad in the conductive adhesive layer embedded with the porous mesh pad has a mesh structure, and grooves are provided at the intersections of the mesh structure, with conductive particles inside the grooves.

[0008] The present invention provides grooves at the intersections of the mesh structure of the porous mesh pad. When vertically blown, a small number of conductive particles are left in the grooves, while the excess conductive particles pass through the hollow parts of the mesh structure and are collected. By setting the position and depth of the grooves, the position of the conductive particles on the XYZ axes of the anisotropic conductive film can be controlled.

[0009] Preferably, the thickness of the conductive adhesive layer with embedded porous mesh pad is 10 to 100 micrometers.

[0010] Preferably, the thickness of the porous mesh pad is greater than the depth of the groove opening.

[0011] Further preferably, the thickness of the porous mesh layer is 10–50 micrometers, and the depth of the groove opening is 3–48 micrometers.

[0012] In this invention, the position and quantity of conductive particles are controlled by grooves, and the thickness of the porous mesh layer is set to be greater than the depth of the groove opening, so that the conductive particles do not directly contact the release film. This is beneficial to the stability of the particles in the colloid and avoids the conductive particles from being adhered to the release film's peeling surface during the use of ACF products, which would lead to product failure.

[0013] Preferably, the shape of the mesh is near rhombus or near square; the shape of the groove includes one or more of square, circular, and rhombus shapes, and the opening size is 3 to 20 micrometers.

[0014] More preferably, the area of ​​the grid is 2 to 100 times the area of ​​the groove opening.

[0015] Preferably, the conductive particles have a three-layer structure, consisting of a resin core, a nickel / gold plating layer, and an insulating plating layer from the inside out.

[0016] Further preferably, the diameter of the resin sphere core in the conductive particles is 1 to 20 micrometers, the thickness of the nickel / gold plating layer is 0.1 to 2 micrometers, and the thickness of the insulating plating layer is 0.05 to 0.5 micrometers.

[0017] More preferably, the resin core is one or more of polystyrene (PS), polyaniline (PANI), polymethyl methacrylate (PMMA), polyacrylamide (PMA), polyvinyl alcohol (PVA), and polycaprolactone (PCL); the raw material of the insulating coating is a polymer powder, including one or more of polystyrene (PS) and polymethyl methacrylate (PMMA).

[0018] In this invention, conductive particles with a three-layer structure of resin core, nickel / gold plating, and insulating plating are preferred. There are two purposes: (1) During the use of the end product, the interface gap in the Z direction will inevitably increase over time. Particles with resin core have a certain deformation capability, which can reduce the impact of the increased gap on reliability to a certain extent; (2) In high particle density products, there is a small probability of particle contact in the XY direction due to resin deformation. The presence of the insulating layer can prevent short circuits in the XY direction caused by this contact.

[0019] Preferably, the raw material of the porous mesh layer includes one or more of acrylic resin, epoxy resin, and polyurethane.

[0020] Preferably, the peel strength between the PET release film layer and the conductive adhesive layer with embedded porous mesh pad is 40-2000mN.

[0021] This invention also discloses a method for preparing anisotropic conductive film with adjustable conductive particle orientation along the XYZ axis. The preparation method includes: blowing conductive particles vertically into the grooves of a porous mesh layer by airflow; then laminating a PET release film and a porous mesh layer by roll pressing; then coating the porous mesh layer with conductive adhesive; drying to form a film; and finally slitting and packaging the anisotropic conductive film.

[0022] Preferably, during the vertical purging process, excess particles pass through the grid; 1 to 5 conductive particles are retained in each groove.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. In the anisotropic conductive film of the present invention, the porous mesh layer is a grid structure in which the conductive particles are adjustable in the XYZ axis. Grooves are provided at the intersections of the grid structure. The conductive particles are placed in the grooves with a certain depth to achieve the adjustable orientation of the conductive particles in the XYZ axis.

[0025] 2. The anisotropic conductive film of the present invention, in which the conductive particles are oriented in an adjustable direction along the XYZ axes, can precisely control the distribution of conductive particles and avoid short circuits or open circuits.

[0026] 3. The method for preparing anisotropic conductive film with adjustable conductive particles along the XYZ axis of the present invention adopts a one-time coating and molding method, which avoids the need for post-processing after product molding, improves the product qualification rate and reduces waste generation, making the production process more environmentally friendly and efficient. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the anisotropic conductive film with adjustable XYZ axis orientation of the conductive particles prepared according to the present invention.

[0028] Figure 2 This is a schematic diagram of the porous mesh layer in the anisotropic conductive film with adjustable XYZ axis conductive particles prepared in Embodiment 1 of the present invention.

[0029] 1. Release film layer; 2. Porous mesh pad layer; 3. Conductive adhesive layer with embedded porous mesh pad layer; 4. Hollow part of the mesh structure of porous mesh pad layer; 5. Groove. Detailed Implementation

[0030] The following are specific embodiments of the present invention, which further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0031] The raw materials used in this invention are conventional commercially available materials.

[0032] The anisotropic conductive film of the present invention, in which the conductive particles are adjustable in the XYZ axis, includes a PET release film layer 1 and a conductive adhesive layer 3 with an embedded porous mesh layer.

[0033] The porous mesh pad 2 in the conductive adhesive layer 3 embedded with the porous mesh pad has a mesh structure, and a groove 5 is provided at the intersection of the mesh structure. There are 1 to 5 conductive particles in the groove 5.

[0034] The thickness of the porous mesh layer 2 is 10-50 micrometers, and the opening depth of the groove 5 is 3-48 micrometers;

[0035] The shape of the grid is nearly rhomboid or nearly square; the shape of the groove 5 includes one or more of square, circular, and rhomboid shapes, and the opening size is 3 to 20 micrometers.

[0036] The thickness of the conductive adhesive layer 3 with embedded porous mesh pad is 10 to 100 micrometers;

[0037] The peel strength between the release film layer 1 and the conductive adhesive layer 3 with embedded porous mesh pad is 40-2000 mN.

[0038] The conductive particles have a three-layer structure, consisting of a resin core, a nickel / gold plating layer, and an insulating plating layer from the inside out.

[0039] The diameter of the resin sphere core in the conductive particles is 1 to 20 micrometers, the thickness of the nickel / gold plating layer is 0.1 to 2 micrometers, and the thickness of the insulating plating layer is 0.05 to 0.5 micrometers.

[0040] The resin core is one or more of polystyrene (PS), polyaniline (PANI), polymethyl methacrylate (PMMA), polyacrylamide (PMA), polyvinyl alcohol (PVA), and polycaprolactone (PCL); the raw material for the insulating coating is a polymer powder, including one or more of polystyrene (PS) and polymethyl methacrylate (PMMA).

[0041] The raw materials of the porous mesh layer 2 include one or more of acrylic resin, epoxy resin, and polyurethane.

[0042] The coating liquid is one or more of the following: acrylic system, polyurethane system, epoxy system, and acrylic system.

[0043] Example 1

[0044] In this embodiment, the thickness of the anisotropic conductive adhesive film with adjustable XYZ axis conductive particles is 110 micrometers, wherein the thickness of release film layer 1 is 75 micrometers, the thickness of porous mesh layer 2 is 15 micrometers, and the thickness of conductive adhesive layer 3 with embedded porous mesh layer is 35 micrometers; the structure of the conductive particles from the inside out is as follows: a resin sphere core (polystyrene) with a diameter of 2 micrometers, a nickel / gold plating layer with a thickness of 0.5 micrometers, and an insulating plating layer (polymethyl methacrylate) with a thickness of 0.1 micrometers; the peel strength between release film layer 1 and conductive adhesive layer 3 with embedded porous mesh layer is 1800mN.

[0045] porous mesh mat:

[0046] A porous mesh mat is manufactured using a mold, and the material is acrylic resin. The groove 5 is square in shape, with an opening size of 5*5 micrometers and a depth of 10 micrometers. The mesh is also square in shape, with a size of 30*30 micrometers. See the schematic diagram. Figure 1 .

[0047] Anisotropic conductive film with adjustable conductive particle orientation along the XYZ axes:

[0048] With the side of the porous mesh pad containing the grooves 5 facing upwards, conductive particles are blown vertically into the grooves 5 of the porous mesh pad using an airflow, ensuring that each groove 5 contains one conductive particle. Excess conductive particles pass through the hollow spaces 4 of the porous mesh pad's mesh structure. This is then applied to the surface of the PET release film layer 1, and under the pressure of rollers, a monolithic structure is formed. Next, a coating liquid is applied to the PET release film layer 1 carrying the porous mesh pad layer 2, and after drying, an anisotropic conductive film is formed; finally, it is cut and packaged.

[0049] The performance of the anisotropic conductive film with adjustable XYZ axis conductive particles was tested, and the conductivity defect rate was 0.01%.

[0050] Example 2

[0051] In this embodiment, the thickness of the anisotropic conductive adhesive film with adjustable XYZ axis conductive particles is 110 micrometers, of which the thickness of release film layer 1 is 75 micrometers, the thickness of porous mesh layer 2 is 10 micrometers, and the thickness of conductive adhesive layer is 35 micrometers. The structure of the conductive particles from the inside out consists of a resin sphere core (polyaniline) with a diameter of 4 micrometers, a nickel / gold plating layer with a thickness of 0.7 micrometers, and an insulating plating layer (polystyrene) with a thickness of 0.2 micrometers. The peel strength between release film layer 1 and conductive adhesive layer 3 with embedded porous mesh layer is 1900mN.

[0052] porous mesh mat:

[0053] The porous mesh is made by molding. The material is a mixture of acrylic resin and polyurethane resin in a mass ratio of 1:1. The groove 5 is circular in shape with an opening diameter of 6 micrometers and a depth of 7 micrometers. The mesh is square in shape with a size of 30*30 micrometers.

[0054] With the side of the porous mesh pad containing grooves 5 facing upwards, conductive particles are blown vertically into the grooves 5 of the porous mesh pad using an airflow, ensuring that each groove 5 contains two conductive particles. Excess conductive particles pass through the hollow spaces 4 of the porous mesh pad layer's mesh structure. This is then applied to the surface of a PET release film, and under roller pressure, a monolithic structure is formed. Next, a coating liquid is applied to the PET release film layer 1 carrying the porous mesh pad layer 2, and after drying, an anisotropic conductive adhesive is formed. Finally, the material is cut and packaged.

[0055] The performance of the anisotropic conductive film with adjustable XYZ axis conductive particles was tested, and the conductivity defect rate was 0.01%.

[0056] Example 3

[0057] In this embodiment, the thickness of the anisotropic conductive adhesive film with adjustable XYZ axis conductive particles is 155 micrometers, of which the thickness of release film layer 1 is 75 micrometers, the thickness of porous mesh layer 2 is 40 micrometers, and the thickness of conductive adhesive layer is 80 micrometers. The structure of the conductive particles from the inside out consists of a resin sphere core (polyvinyl alcohol) with a diameter of 1.5 micrometers, a nickel / gold plating layer with a thickness of 0.7 micrometers, and an insulating plating layer (polymethyl methacrylate) with a thickness of 0.2 micrometers. The peel strength between release film layer 1 and conductive adhesive layer 3 with embedded porous mesh layer is 1600mN.

[0058] porous mesh mat:

[0059] The porous mesh is made by molding, and the material is epoxy resin. The groove 5 is rhomboid in shape, with the side length of the opening and the shorter diagonal being 4 micrometers, and the depths being 10, 20, and 30 micrometers respectively. The three sizes of groove 5 are randomly distributed. The mesh is rhomboid in shape, with the side length of the opening and the shorter diagonal being 30 micrometers.

[0060] With the side of the porous mesh pad containing the grooves 5 facing upwards, conductive particles are blown vertically into the grooves 5 of the porous mesh pad using an airflow, ensuring that each groove 5 contains one conductive particle. Excess conductive particles pass through the hollow spaces 4 of the porous mesh pad's mesh structure. This is then applied to the surface of the PET release film layer 1, and under the pressure of rollers, a monolithic structure is formed. Next, a coating liquid is applied to the PET release film layer 1 carrying the porous mesh pad layer 2, and after drying, an anisotropic conductive adhesive is formed. Finally, the material is cut and packaged.

[0061] The performance of the anisotropic conductive film with adjustable XYZ axis conductive particles was tested, and the conductivity defect rate was 0.01%.

[0062] Example 4

[0063] In this embodiment, the thickness of the anisotropic conductive adhesive film with adjustable XYZ axis conductive particles is 95 micrometers, of which the thickness of release film layer 1 is 75 micrometers, the thickness of porous mesh layer 2 is 10 micrometers, and the thickness of conductive adhesive layer is 20 micrometers. The structure of the conductive particles from the inside out consists of a resin sphere core (polystyrene) with a diameter of 2 micrometers, a nickel / gold plating layer with a thickness of 0.5 micrometers, and an insulating plating layer (polymethyl methacrylate) with a thickness of 0.1 micrometers. The peel strength between release film layer 1 and conductive adhesive layer 3 with embedded porous mesh layer is 1800mN.

[0064] porous mesh mat:

[0065] The porous mesh is made by molding, and the material is acrylic resin; the groove 5 is square in shape, with an opening size of 5*5 micrometers and a depth of 5 micrometers; the mesh is also square in shape, with a size of 30*30 micrometers.

[0066] Anisotropic conductive film with adjustable conductive particle orientation along the XYZ axes:

[0067] With the side of the porous mesh pad containing the grooves 5 facing upwards, conductive particles are blown vertically into the grooves 5 using an airflow, ensuring that each groove 5 contains one conductive particle. This is then applied to the surface of the PET release film layer 1, and formed into a single structure under roller pressure. Next, a coating liquid is applied to the PET release film layer 1 carrying the porous mesh pad layer 2, and after drying, an anisotropic conductive adhesive is formed; finally, it is cut and packaged.

[0068] The performance of the anisotropic conductive film with adjustable XYZ axis conductive particles was tested, and the conductivity failure rate was 0.02%.

[0069] Example 5

[0070] Compared with Example 1, the difference is that conductive particles are blown into the grooves 5 of the porous mesh pad by an airflow at an angle of 45 degrees. Some grooves 5 have no conductive particles, while some grooves 5 have 3 to 7 conductive particles.

[0071] The prepared anisotropic conductive film was subjected to performance testing, and the conductivity failure rate was 0.06%.

[0072] Example 6

[0073] The difference from Example 1 is that the conductive particles are conductive gold spheres.

[0074] The prepared anisotropic conductive film was subjected to performance testing, and the conductivity failure rate was 0.05%.

[0075] Comparative Example 1

[0076] Compared with Example 1, the difference is that the anisotropic conductive adhesive film in this comparative example does not have a porous mesh layer 2. The conductive particles are directly mixed with the coating liquid and then coated on the surface of the release film layer 1. The content of conductive particles is the same as in Example 1.

[0077] The prepared anisotropic conductive film was subjected to performance testing, and the conductivity failure rate was 0.12%.

[0078] Comparative Example 2

[0079] Compared with Example 1, the difference is that the porous mesh layer 2 in the anisotropic conductive film of this comparative example is an acrylic resin layer with perforated surface. Some grooves 5 have no conductive particles, while some grooves 5 have 3 to 10 conductive particles. Moreover, the excess conductive particles are difficult to collect during the purging process, resulting in some waste.

[0080] The prepared anisotropic conductive film was subjected to performance testing, and the conductivity failure rate was 0.08%.

[0081] In summary, the porous mesh layer in the anisotropic conductive film with adjustable XYZ axis conductive particles of the present invention has a mesh structure, and grooves 5 are provided at the intersection of the mesh structure. The conductive particles are placed in the grooves 5 of a certain depth to achieve adjustable XYZ axis conductive particles.

[0082] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. Anisotropic conductive paste film in which the direction of electrically conductive particles is adjustable in XYZ axes, characterized by, The conductive particle direction-adjustable anisotropic conductive adhesive film in XYZ axis comprises a PET release film layer and a conductive adhesive layer with a porous mesh pad layer embedded therein; The conductive adhesive layer with the porous mesh pad layer embedded therein has a thickness of 10-100 microns; The porous mesh pad layer in the conductive adhesive layer with the porous mesh pad layer embedded therein has a grid structure, and recesses are arranged at the intersection points of the grid structure, and the recesses contain conductive particles; The thickness of the porous mesh pad layer is 10-50 microns, the depth of the recess opening is 3-48 microns, and the opening size is 3-20 microns; the thickness of the porous mesh pad layer is greater than the depth of the recess opening; The conductive particle has a three-layer structure, and from inside to outside, it comprises a resin ball core, a nickel / gold plating layer, and an insulating plating layer; the diameter of the resin ball core is 1-20 microns, the thickness of the nickel / gold plating layer is 0.1-2 microns, and the thickness of the insulating plating layer is 0.05-0.5 microns; The preparation method of the conductive particle direction-adjustable anisotropic conductive adhesive film in XYZ axis comprises the following steps: placing the porous mesh pad with recesses on one side upward, blowing the conductive particles into the recesses of the porous mesh pad layer through airflow vertical blowing, and in the process of airflow vertical blowing, the excess particles pass through the grid of the porous mesh pad layer; 1-5 conductive particles are reserved in each recess; Then, the PET release film and the porous mesh pad layer are compounded by rolling, and then the conductive adhesive liquid is coated on the porous mesh pad layer, and after drying into a film, the anisotropic conductive adhesive film is cut and packaged.

2. The electrically conductive particle in XYZ axis direction-adjustable anisotropic conductive adhesive film according to claim 1, characterized by, The shape of the grid is nearly rhombic or nearly square; the shape of the recess includes one or more of square, circular, and rhombic; and the area of the grid is 2-100 times the opening area of the recess.

3. The electrically conductive particle in the XYZ axis direction-adjustable anisotropic conductive adhesive film according to claim 1, characterized by, The raw material of the porous mesh pad layer includes one or more of acrylic resin, epoxy resin, and polyurethane.

4. The electrically conductive particle in the XYZ axis direction-adjustable anisotropic conductive adhesive film according to claim 1, characterized by, The peel strength between the PET release film layer and the conductive adhesive layer with the porous mesh pad layer embedded therein is 40-2000 mN.

5. The electrically conductive particle in the XYZ axis direction-adjustable anisotropic conductive adhesive film according to claim 1, characterized by, The thickness of the conductive particle direction-adjustable anisotropic conductive adhesive film in XYZ axis is 110 microns, wherein the thickness of the release film layer is 75 microns, the thickness of the porous mesh pad layer is 15 microns, and the thickness of the conductive adhesive layer with the porous mesh pad layer embedded therein is 35 microns; and the structure of the conductive particle from inside to outside is a polystyrene resin ball core with a diameter of 2 microns, a nickel / gold plating layer with a thickness of 0.5 microns, and a polymethyl methacrylate insulating plating layer with a thickness of 0.1 microns; The peel strength between the release film layer and the conductive adhesive layer with the porous mesh pad layer embedded therein is 1800 mN; The porous mesh pad is prepared by a mold, and the material is acrylic resin; the shape of the recess is square, the opening size is 5*5 microns, and the depth is 10 microns; and the shape of the grid is also square, and the size is 30*30 microns; The conductive particle direction-adjustable anisotropic conductive adhesive film in XYZ axis has a conductive failure rate of 0.01%.

6. A method for producing anisotropic conductive adhesive film having directionally adjustable anisotropy in XYZ axes using the electrically conductive particles according to claim 1, characterized by, The preparation method comprises the following steps: placing the porous mesh pad with the recessed side facing upward, blowing the conductive particles into the recesses of the porous mesh layer through airflow vertical blowing, and the excess particles passing through the mesh of the porous mesh layer during the airflow vertical blowing; retaining 1-5 conductive particles in each recess; then rolling the PET release film and the porous mesh layer to be compounded, coating the conductive glue solution on the porous mesh layer, drying the film, and then cutting and packaging the anisotropic conductive adhesive film.

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