Anisotropic conductive adhesive film containing double adhesive layers

Abstract

The utility model discloses an anisotropic conductive adhesive film containing double adhesive layers. Wherein conductive particles of which the average particle size is not less than 3 microns are dispersed in the conductive adhesive layer, electrically insulating filling particles of which the average particle size is not more than 0.5 microns are dispersed in the protective adhesive layer, and the protective film is attached to the opposite side surfaces of the conductive adhesive layer and the protective adhesive layer. In the manufacturing process of the electronic product, the filling particles can be dispersed around the conductive particles, so that the lateral conduction risk is reduced. The anisotropic conductive adhesive film is simple in structure, convenient to manufacture and suitable for small pin spacing.

Description

TECHNICAL FIELD

[0001] The utility model belongs to conductive glue for circuit substrate dress connection, specifically relates to the anisotropic conductive glue film of multilayer structure. BACKGROUND

[0002] Anisotropic Conductive Film, abbreviated as ACF film, is used for electronic product process that cannot be soldered, especially for the dress connection of flexible circuit board. In finished products, part of the conductive particles of the ACF film is "captured" to longitudinally conduct the IC pin and the circuit substrate contact; the remaining conductive particles are located in the cured insulating matrix, which has the risk of transverse conduction.

[0003] The multilayer structure of the ACF film can reduce the risk of transverse conduction. For example, 1) the conductive particle layer uses semi-cured resin, and the protective glue layer uses uncured resin; 2) the conductive particle density of different glue layers is gradiently changed in the stacking direction; 3) the conductive particle layer, the low-temperature hot melt resin layer, the curing layer and the monomer coating layer are sequentially stacked; 4) larger conductive particles are arranged in a single layer array. SUMMARY

[0004] The technical problem to be solved by the utility model is how to improve the multilayer structure of the anisotropic conductive glue film to improve the process applicability.

[0005] In this specification, the anisotropic conductive glue film can be simply referred to as ACF film.

[0006] The utility model discloses a kind of anisotropic conductive glue films containing double glue layers. The anisotropic conductive glue film includes:

[0007] One conductive glue layer, with the conductive particle of average particle size not less than 3 microns being dispersed;

[0008] One protective glue layer, with the filling particle of average particle size not greater than 0.5 microns being dispersed, is attached with the conductive glue layer;And

[0009] At least one protective film is attached on the opposite side of the conductive glue layer and the protective glue layer.

[0010] In some embodiments of the present application, the glue application thickness of the conductive glue layer can be selected to be not less than 10 microns, and the glue application thickness of the protective glue layer can be selected to be not greater than 10 microns.

[0011] In some embodiments of the present application, the anisotropic conductive glue film is subjected to whole-surface pre-pressing treatment, so that the conductive glue layer and the protective glue layer are partially mixed. Further, the anisotropic conductive glue film is configured as a flat slice of a predetermined size, or is wound on a reel.

[0012] The technical scheme is implemented, and the following beneficial effects can be achieved.

[0013] The utility model discloses an anisotropic conductive adhesive film containing double adhesive layers. The conductive adhesive layer is dispersed with conductive particles with an average particle size of no less than 3 microns, and the protective adhesive layer is dispersed with filling particles with an average particle size of no more than 0.5 microns and electrically insulated. The protective film is attached to the opposite sides of the conductive adhesive layer and the protective adhesive layer. In the electronic product processing, the filling particles can be dispersed around the conductive particles to reduce the risk of horizontal conduction. The anisotropic conductive adhesive film is simple in structure, easy to manufacture and suitable for small pin pitch. BRIEF DESCRIPTION OF DRAWINGS

[0014] The following drawings should be used in conjunction with the detailed description section.

[0015] Figure 1 is the structure and process schematic diagram of the roll ACF film in example one.

[0016] Figure 2 is the structure and process schematic diagram of the slice ACF film in example two.

[0017] The reference numerals in the drawings represent:

[0018] 10 - conductive adhesive layer, 11 - conductive particle, 20 - protective adhesive layer, 21 - filling particle, 30 - protective film, 81 - roll, 100 - first semi-finished product, 100' - second semi-finished product, 200 - roll ACF film, 300 - slice ACF film. DETAILED DESCRIPTION

[0019] The embodiments will be described below in conjunction with the drawings.

[0020] In this specification, one embodiment, some embodiments and other embodiments are used to distinguish different embodiments, and do not mean all embodiments; the drawings are schematic diagrams and not proportional diagrams; the directions / positions of top, bottom, center, edge, inside, outside, far, near, long, wide, vertical, horizontal, upper, lower, front, back, left, right, etc. are based on the observation angle of the drawings and cannot be understood as the components / devices being located at a specific position or facing a specific direction; the first, second, third, etc. sequence words are used to distinguish the components / devices with the same function / name and do not have the sequence meaning.

[0021] Unless otherwise specified, the parts in the embodiments are mass parts.

[0022] Example one

[0023] The roll ACF film 200 is disclosed.

[0024] Please refer to Figure 1The roll ACF film 200 is an anisotropic conductive adhesive film with double adhesive layers, which is prepared by winding the first semi-finished product 100 on the roll 81.

[0025] The first semi-finished product 100 is a long belt with a three-layer structure. Specifically, the conductive adhesive layer 10 and the protective adhesive layer 20 are sequentially applied on the protective film 30 which is unwound and expanded, thereby preparing the first semi-finished product 100. In the first semi-finished product 100, the conductive adhesive layer 10 and the protective adhesive layer 20 are adhered to each other (hereinafter referred to as double adhesive layers), and the protective film 30 is attached to the opposite side surfaces of the conductive adhesive layer 10 and the protective adhesive layer 20.

[0026] The protective film 30 is configured as a PE film or a PET film, and has a thickness of 25-50 microns. The protective film 30 is a carrier of the double adhesive layers, and protects the double adhesive layers during manufacturing, transportation and storage. The protective film 30 itself has no adhesion, and needs to be removed in advance during the manufacturing process of electronic products.

[0027] The conductive adhesive layer 10 has the conductive particles 11 uniformly dispersed in the interior thereof, and the protective adhesive layer 20 has the electrically insulating filler particles 21 uniformly dispersed in the interior thereof.

[0028] The conductive adhesive layer 10 has a thickness of not less than 10 microns, preferably 10-20 microns, and more preferably 15 microns. Correspondingly, the protective adhesive layer 20 has a thickness of not more than 10 microns, preferably 5-10 microns, and more preferably 7.5 microns.

[0029] The conductive particles 11 are made of nickel powder, or are made of polystyrene microspheres plated with nickel / gold / Pd, and have an average particle size of not less than 3 microns, preferably 3-10 microns, and more preferably 6 microns. Correspondingly, the filler particles 21 are made of nano-particles of silicon dioxide, aluminum oxide, zirconium oxide, magnesium oxide, aluminum nitride, boron nitride or silicon carbide, and have an average particle size of not more than 0.5 microns, preferably 50-250 nm, and more preferably 150 nm.

[0030] The conductive adhesive layer 10 and the protective adhesive layer 20 are both mixtures containing uncured polymers (or monomers), and can mix with each other under application conditions, so that the filler particles can be dispersed around the conductive particles. However, the conductive particles are not easy to migrate due to their large particle size, and can maintain a distribution state which is easy to be captured.

[0031] When the first semi-finished product 100 is wound by the roll 81, the double adhesive layers are subjected to pressure on the entire surface, so that the double adhesive layers of the roll ACF film 200 are partially mixed. Figure 1 In the double adhesive layers, the conductive adhesive layer 10' and the protective adhesive layer 20' are shown to indicate that the double adhesive layers are not completely mixed, and there is no obvious interface between the two; a part of the filler particles migrate to the vicinity of the conductive particles, which are marked as 21' in Figure 1 ; and the conductive particles surrounded by the filler particles are marked as 11' in Figure 1 .

[0032] The roll ACF film 200 is unwound at the beginning of use, the electronic device is bonded at the unwound part, the unwound part is cut, the protective film of the cut part is peeled off, and the electronic device with the double adhesive layer is pasted on the designated position of the circuit board. The double adhesive layer is heated to mix, longitudinally conduct and solidify. The filling particles will be further dispersed and uniform in the double adhesive layer, thereby reducing the risk of transverse conduction of the conductive particles 11'.

[0033] The filling particles 21 of silicon dioxide, aluminum oxide or magnesium oxide can improve the heat resistance of the solidified insulating matrix.

[0034] The specific composition of the double adhesive layer can be adjusted based on the existing ACF adhesive film. The following scheme has certain universality. The conductive adhesive layer 10 includes 15-30 parts of acrylic resin, 15-30 parts of epoxy resin, 20-40 parts of nitrile rubber, 5-10 parts of conductive particles and appropriate additives, including 2-5 parts of coupling agent, 1-3 parts of curing agent, 5-10 parts of tackifying resin and 1-3 parts of initiator. The protective adhesive layer 20 includes 0-20 parts of acrylic resin, 0-40 parts of epoxy resin, 0-30 parts of polyurethane, 10-20 parts of pressure-sensitive adhesive, 5-10 parts of flame retardant, 10-20 parts of filling particles and appropriate additives, including 2-5 parts of coupling agent, 1-3 parts of curing agent, 5-10 parts of tackifying resin and 1-3 parts of initiator. The above-mentioned flame retardant is one or more of aluminum diethylphosphinate (ADP), antimony trioxide, magnesium hydroxide, aluminum hydroxide, alkyl phosphate, dicyclopentadiene, borate, triazine and its derivatives, and trichlorobromomethane.

[0035] Example Two

[0036] A sliced ACF film 300 is disclosed.

[0037] Please refer to Figure 2 The sliced ACF film 300 is based on the above-mentioned roll ACF film 200 and improved as follows.

[0038] The sliced ACF film 300 is prepared from the second semi-finished product 100' by full-surface pre-pressing treatment.

[0039] The first semi-finished product 100 is a four-layer structure of a predetermined size. Specifically, on a flat piece of protective film 30, the conductive adhesive layer 10 and the protective adhesive layer 20 are applied in sequence, and then another piece of protective film 30 is covered, thereby preparing the second semi-finished product 100'. In the second semi-finished product 100', the conductive adhesive layer 10 and the protective adhesive layer 20 are attached to each other (hereinafter referred to as a double adhesive layer), and the protective film 30 is attached to both opposite sides of the conductive adhesive layer 10 and the protective adhesive layer 20.

[0040] In the pre-pressing process, the double adhesive layers of the second semi-finished product 100' are partially mixed under the pressure applied on the whole surface.

[0041] The other aspects of the sliced ACF film 300 are basically the same as those of the roll ACF film 200, which are described in Embodiment 1.

[0042] The second semi-finished product 100' described above can be directly used in the electronic product manufacturing process.

[0043] In other embodiments, the conductive particle concentration can be increased under the premise that the double adhesive layers can be effectively mixed, so that the conductive adhesive layer has a thickness less than 10 microns but thicker than the protective adhesive layer, so as not to affect the directional conduction effect.

[0044] The above embodiments, application examples and technical analysis are intended to introduce the technical concept and characteristics of the present application, so that those skilled in the art can implement the technical solution of the present application, and do not constitute any limitation on the protection scope of the present application. Simple modifications and equivalent transformations of the above embodiments are within the protection scope of the present application.

Claims

1. An anisotropic conductive film having a double adhesive layer, characterized by It comprises: a conductive adhesive layer, which is dispersed with conductive particles with an average particle size not less than 3 microns; a protective adhesive layer, which is in contact with the conductive adhesive layer and is dispersed with electrically insulating filler particles with an average particle size not greater than 0.5 microns; and at least one protective film, which is in contact with the opposite sides of the conductive adhesive layer and the protective adhesive layer.

2. The anisotropic conductive adhesive film according to claim 1, wherein: the conductive adhesive layer has an adhesive thickness not less than 10 microns; and the protective adhesive layer has an adhesive thickness not greater than 10 microns.

3. The anisotropic conductive adhesive film according to claim 2, wherein: the conductive adhesive layer has an adhesive thickness of 10-20 microns, the protective adhesive layer has an adhesive thickness of 5-10 microns, the conductive particles have an average particle size of 3-10 microns, and the filler particles have an average particle size of 50-250 nm.

4. The anisotropic conductive adhesive film according to claim 3, wherein: the conductive adhesive layer has an adhesive thickness of 15 microns, the protective adhesive layer has an adhesive thickness of 7.5 microns, the conductive particles have an average particle size of 6 microns, and the filler particles have an average particle size of 150 nm.

5. The anisotropic conductive adhesive film according to claim 1, wherein: it is subjected to whole-surface pre-pressing treatment to make the conductive adhesive layer and the protective adhesive layer partially mixed. It comprises:

6. The anisotropic conductive paste film according to claim 5, wherein two protective films, which are in contact with the two opposite sides of the conductive adhesive layer and the protective adhesive layer, respectively; and it is configured as a predetermined size of a tiled sheet.

7. The anisotropic conductive adhesive film according to claim 5, wherein: it is wound on a reel. ​

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