JPS6251111A - Anisotropically conducting film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (,) Industrial Application Field The present invention relates to an anisotropic conductive film used for electrically and mechanically bonding the electrode portion of a flexible circuit board and the electrode portion of a liquid crystal display element. It is related to.

(b) Conventional technology In recent years, electronic devices have become thinner and smaller, and the electrical connections between each element are made by forming a large number of electrodes with clip-shaped terminals and using these terminals. There is a transition from so-called mechanical connectors, which are used to connect wires, to methods that use anisotropically conductive films that have three functions: conductivity, insulation, and adhesiveness.

By the way, as a conventional anisotropic conductive film, one in which a conductive member is simply dispersed or arranged in an adhesive (an electrically insulating member) is known.

(C) Problems to be Solved by the Invention However, when connecting this anisotropically conductive film to a flexible circuit board, etc., the adhesive (electrical insulating member) is removed by heating the film and heating it with a pressure press. It is necessary to melt them and join them together. At this time, the flow of the adhesive (electrical insulating material) causes the conductors to move, and as a result, the conductors come close to each other or come into contact with each other, causing the objects to be joined to each other. In some cases, the electrical insulation between the electrodes deteriorated. To avoid this problem, extremely precise heating and pressure pressing must be used, and appropriate pressing conditions (
(temperature, time, pressure, etc.) is narrow, and the connection between each terminal requires considerable care or costs.
Furthermore, when a large number of connections are made during mass production, conduction failures and connection failures may be mixed in, resulting in a problem of poor reliability.

(d) Means for Solving the Problem The present inventor proposed that the conductive member is partitioned by an electrically insulating member and is electrically independent, and that when connecting an anisotropic conductive film and a printed wiring board etc. It is a highly reliable material that allows reliable electrical connection without causing the conductive material to flow and impairing the insulation properties of the electrode, or without requiring special equipment or technology to connect the film and the printed wiring board. We have been conducting extensive research on electrically conductive films.

As a result, they discovered that the electrically insulating member that partitions the conductive member has a special structure to provide the two functions of adhesiveness and insulation, thereby completing the present invention.

That is, the present invention provides an anisotropic conductive film in which a conductive member is partitioned by an electrically insulating member and is electrically independent, the electrically insulating member comprising a hot melt adhesive layer, an insulating layer, and a hot melt adhesive. It is characterized in that it is composed of three layers of adhesive layers, and the insulating layer is composed of a polymeric material whose pour point is higher than the bonding temperature of the hot melt adhesive layer.

The present invention will be explained in detail below.

The most significant feature of the present invention is that the electrically insulating member that partitions the conductive member is constructed into a three-layered body consisting of a hot melt adhesive layer, an insulating layer, and a hot melt adhesive layer.

Further, the conductive member used in the present invention is not particularly limited as long as it has a volume resistivity of 10 3 Ω-ell or less and can be formed into a film. Specifically, for example, a thermosetting material or is a thermoplastic synthetic resin, metal powder or metal fiber such as gold, silver, sawdust, aluminum, zinc, tin, iron, lead, nickel or cobalt, or alloy powder or fiber whose main component is these metals, Furthermore, it refers to films formed by mixing conductive materials such as carbon powder and fibers, the above-mentioned metal nets and fabrics, and even films (foils), among which, in particular, polyethylene resins, polyurethane resins, etc. A thermoplastic resin mixed with the above conductive member is preferred because it has excellent cutting workability and exhibits adhesive properties when heated.

Further, if the volume resistivity of the conductive member exceeds 10'Ω-cIl, the contact resistance when used as a connector becomes high, which is not preferable because it may be impractical.

In addition, the hot melt adhesive layer used in the present invention includes:
Examples include adhesive layers formed of ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate 13 polymer, ethylene-acrylic acid copolymer, ionomer resin, adhesive polyolefin, and the like.

The insulating layer is a layer formed of an electrically insulating polymer material such as rubber or synthetic resin whose pour point exceeds the bonding temperature of the hot-melt adhesive layer used.

The above pour point can be measured by the method of JIS K 7210.

The above-mentioned rubbers include natural rubber, and rubbers such as polybutadiene rubber, nitrile-butadiene rubber, styrene-butadiene rubber, and the like.

The synthetic resins include both thermoplastic resins and thermosetting resins, such as polyolefins, polyethylene terephthalate, polyacrylonitrile, polymethacrylonitrile, polyurethane layers, polyvinyl chloride, silicone resins, polyester resins, Examples include acrylic resin, polyamide resin, polycarbonate resin, polyacetal resin, acrylic copolymer, polystyrene resin, ABS resin, epoxy resin, unsaturated polyester resin, phenol resin, urea resin, melamine resin, and guanamine resin.

The conductive member and the electrically insulating member, that is, the three-layer structure of the hot melt adhesive layer, the insulating layer, and the hot melt adhesive layer, are preferably made of materials that can adhere to each other. If they do not have adhesive properties to each other, they may be joined via a suitable adhesive layer.

Next, the anisotropically conductive film of the present invention can be manufactured, for example, by the method described below.

First, step A is performed in which an electrically insulating member is laminated on one or both sides of a conductive member to form a laminated film.

In the laminated film obtained by this step A, even if the conductive member and the electrically insulating member are integrally bonded to each other,
Alternatively, they may not be joined together.

Further, the insulating member has a three-layer sandwich structure including an insulating layer and hot-melt adhesive layers provided on both sides of the insulating layer.

As the conductive member, hot melt adhesive layer, or insulating layer, those described above are used.

This step A includes, for example, (a) dissolving a hot melt adhesive in a solvent to make a paint, applying this paint to both sides of the insulating layer and drying it, thereby forming an electrically insulating member; Method of overlapping conductive members, (b) above (
(a) A method of bonding and integrating both members stacked together by heat fusion or adhesive using method (c) Forming a hot-melt adhesive layer on both sides of the insulating layer, thereby forming an electrically insulating member. (d) A hot melt adhesive layer is provided on both sides of the conductive member, while a hot melt adhesive layer is provided on one side of the insulating layer. Form a melt adhesive layer.

This is done by a method of joining the two in such a way that the hot melt adhesive layers do not overlap each other.

Step B is carried out in which a plurality of the laminated films obtained in the above step A are laminated and integrated so that the conductive members and the electrically insulating members alternate to form a rectangular parallelepiped-shaped laminate.

Here, to laminate and integrate a conductive member and an electrically insulating member means to bond the two members by heating, pressurizing, etc. so that they do not separate.In this case, both of these members If the material does not have adhesive properties, in other words, if it cannot be bonded under pressure due to the nature of the material, it is possible to apply various adhesives between these parts or to interpose an adhesive film to make these parts compatible. They may be joined to each other.

Step C is carried out in which the rectangular parallelepiped carcass obtained in Step B is cut in the direction of lamination of the laminated film constituting it to produce a striped film.

In this case, if the hot melt adhesive layer is sticky and cannot be cut at room temperature, the laminate may be cooled to an appropriate temperature and then cut, or the laminate may be cut while being cooled.

A step is carried out in which the striped film obtained in the above step C and the electrically insulating member are laminated and integrated in multiple layers so as to be alternate, thereby obtaining a rectangular parallelepiped-shaped anisotropically conductive film material.

As this electrically insulating member, the same electrically insulating member as used in step A above can be employed.

In addition, in this step, integrating the m layers refers to the above step B.
It has the same meaning as the lamination integration in .

Finally, Step E is performed in which the anisotropically conductive film material obtained in the above steps is cut into a film shape along the lamination direction.

The desired anisotropically conductive film can be obtained through the above steps.

(e) Effect The anisotropically conductive film of the present invention has the above structure, in which the conductive members are each independent, and the pour point of the insulating layer in the electrically insulating member is the bonding temperature of the hot melt adhesive on the member. Because it is set higher, when connecting this anisotropic conductive film and a circuit terminal, the insulating layer does not flow even if the film is heated to the bonding temperature and pressurized, and as a result, the conductive member They do not come into contact with each other, and therefore the film has the effect of reliably maintaining its insulating properties in the surface direction and conductivity in its thickness direction. Further, since the electrically insulating member of the anisotropically conductive film of the present invention has adhesive properties, it has the effect of ensuring reliable bonding with circuit terminals.

(f) Examples Hereinafter, the present invention will be explained in detail based on Examples, but the present invention is not limited thereto.

(B) Structural example of the anisotropically conductive film of the present invention In FIGS. The conductive member 2 penetrates the electrically insulating member 3 in the thickness direction, and is partitioned by the electrically insulating member 3 to be electrically independent.

Further, the electrical insulating member 3 has a hot melt adhesive layer 4a.
It is constructed into a three-layer sandwich groove structure consisting of the insulating NJ5 and the hot melt adhesive layer 4b. Therefore, the electrically insulating member 3 made of the hot melt adhesive fl 4 a, the insulating layer 5, and the hot melt adhesive layer 4b is interposed between the adjacent conductive members 2.2.

The insulating layer 5 is made of a polymer material whose pour point is higher than the bonding temperature of the hot melt adhesive layers 4a and 4b.

(b) Production example of anisotropically conductive film of the present invention 230 parts by weight of nickel powder with an average particle size of 10μ16 is added to 100 parts by weight of polyurethane resin and mixed, and the mixture is formed into a film using a calendar molding machine. Thus, a conductive member 2 having a volume resistivity of 10 −2 Ω-cm and a thickness of 50 μm is manufactured.

On the other hand, a 19-μm-thick adhesive polyester film (product name: Atmer VE300; manufactured by Mitsui Petrochemical Co., Ltd.), which is the hot melt adhesive 134a and 4b, and a 12-μm-thick polyester film (product name: Lumirror; Prepare the polyester film (manufactured by Toshisha),
The adhesive polyester film (
Hot melt adhesive layers 4a, 4b) are provided to form the electrically insulating member 3.

The conductive member 2 and the electrically insulating member 3 are stacked alternately to form a laminated film 10. In step A), the conductive member 2 and the electrically insulating member 3 are alternately stacked on 1000 sheets of the laminated film 10. A rectangular parallelepiped-shaped m carcass 11 is obtained by stacking the layers as shown and integrating them by heating and pressurizing them (
See Figure 2, step B).

Next, the laminate 11 is assembled with fa/'! The striped film 12 is formed by cutting the film 10 in the stacking direction (along the E-I line) (see Figure PtS3, Step C). In addition, it is also possible to cut along the roller line if desired. Further, this striped film can be used as it is as an anisotropically conductive film. A rectangular parallelepiped-shaped anisotropically conductive film material 1' is formed by alternately stacking 500 sheets of each of the striped films 12 and the insulating member 3 (see the fjSA diagram, step D).

Finally, this anisotropically conductive film material 1' is cut into a film shape in the stacking direction (along the harbor line) (Step E).

In this way, the anisotropic conductive film 1 of the present invention is obtained.

Comparative Example As a comparative example, a commercially available anisotropic conductive film was used, which was formed by mixing carbon powder into a hot melt adhesive and rolling the mixture.

The above-mentioned anisotropic conductive film of the present invention has an electrode width of 0°2 mm.
As a result of measuring the insulation between each electrode by sandwiching it between the electrodes and a flexible circuit board with an electrode gap of 0.2+am, heating and applying pressure, the lowest conditions for obtaining conductivity and adhesion in the thickness direction were found to be at a temperature of 120 ℃, pressure 2 kg/0 m2, pressurization time 1
0 seconds (resistance in the thickness direction in this case 0.5Ω),
In addition, even under the press conditions of temperature iao ℃, pressure 20 kg/cL 112, and pressurizing time 100 seconds, the above insulation property was sufficiently maintained, that is, no flow of the conductive member occurred [in this case, between the electrodes (0.2 mm ), that is, the resistance in the plane direction was more than 1 million MΩ].

On the other hand, when the anisotropic conductive film of the comparative example was subjected to the same test as above, the temperature was 160°C and the pressure was 5k.
Under the press conditions of g/c 11+2 and pressurization time of 20 seconds, no insulation was obtained; in other words, flow of the conductive member occurred.

From the above results, the anisotropically conductive film of the present invention secures adhesiveness and conductivity in the thickness direction even at low temperatures and low pressures compared to comparative examples, and also maintains insulation properties even when pressed at high temperatures and high pressures for long periods of time. It was recognized that this could be achieved.

(g) Effects of the invention In the anisotropic conductive film of the present invention, the conductive members are partitioned by electrically insulating members and are electrically independent, and the pour point of the insulating layer in the electrically insulating member is The bonding temperature is set higher than the bonding temperature of the hot melt adhesive layer in the electrical insulating member, and when connecting electrode groups facing each other through this film, there is no need to tighten the pressing conditions, thus achieving high precision. In addition to eliminating the need for a press machine, it is possible to minimize the occurrence of problems such as loss of electrical continuity between the two electrically connected electrodes or poor contact, and as a result, the electrical connection between the two electrode groups can be minimized. This has the effect of increasing the reliability of the system.

[Brief explanation of the drawing]

Fig. fjS1 is a perspective view of an anisotropic conductive film showing an embodiment of the present invention, Fig. 2 is a perspective view of a laminate formed by laminating and integrating conductive members and electrically insulating members alternately, and Fig. 3 is a perspective view of the laminate formed by laminating and integrating conductive members and electrically insulating members. FIG. 4 is a perspective view of a striped film formed by cutting the laminate in the lamination direction, and FIG. 4 is a perspective view of an anisotropically conductive film material formed by alternately laminating and integrating a cotton-like film and an electrically insulating member. . 1... Anisotropic conductive film 2... Conductive member 3... Electrical insulating members 4a, 4 b... Hot melt adhesive layer 5... Insulating layer 1... - Breast:! I<a film 3-... 4IIJt flood Mk 臂廟4a, 4b--d-v to/ruto, mA*r. 5.-1 Taku A & Layer 11i! ff e-kai

Claims (1)

[Claims] An anisotropic conductive film in which a conductive member is partitioned by an electrically insulating member and is electrically independent, the electrically insulating member comprising three layers: a hot melt adhesive layer, an insulating layer, and a hot melt adhesive layer. 1. An anisotropically conductive film, characterized in that the insulating layer is formed of a polymeric material whose pour point is higher than the bonding temperature of the hot melt adhesive layer.