JPH0618082B2 - Anisotropically conductive material for electrical connection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to an electrical connection in which fine particles of a conductive material are coated with a coating material of an electrically insulating material, so-called microencapsulation, and arbitrary resolution is obtained. For anisotropic conductive material.

[Conventional technology]

As a conventional anisotropic conductive material for electrical connection, for example, as shown in FIG. 4 (a), conductive fine particles 1 such as metal or low melting point solder are dispersed in a dispersion medium made of an insulating material 2 to form a film. There is one formed in a shape.

As shown in the figure, when the two substrates 5 to which the electrodes 4 having a predetermined pattern are adhered are connected to each other, the anisotropic conductive material described above is sandwiched between the substrates 5 having the electrodes 4 inside, When the whole is pressurized and heated with, the insulating film is melted and extruded from between the opposing electrodes 4, and the electrodes 4 are electrically connected by the conductive fine particles 1 and the substrate 5
The two substrates are connected to each other by the extruded insulating film 2, and the two substrates are connected to each other by the anisotropic conductive material as shown in FIG. 4 (b).

[Problems to be solved by the invention]

However, in the conventional anisotropically conductive material, it is difficult to uniformly disperse the uniform conductive particles having a particle size of several μm order or less in the film, and therefore, it is possible to achieve high resolution (for example, IC mounting). It could not be used for connecting multi-contact electrodes of 10 lines / mm or more) (by the way, the limit is 5 lines / mm (line space = 100 μm) in the prior art).

For example, to obtain a resolution of 20 electrodes / mm, the electrode pitch is 25 μm. For this reason, it is necessary to uniformly disperse uniform conductive particles having a particle size on the order of several μm or less in the film. According to the conventional technique, agglomeration as shown in FIG. Due to the mixing of particles of small diameter, problems such as short circuit between adjacent electrodes and generation of an insulating state due to the absence of particles as shown in C are generated, and sufficient reliability cannot be obtained.

In addition, since the conventional anisotropic conductive film is in the form of a sheet or tape, (cut) → (temporary attachment) → (temporary adhesion) →
Since complicated steps such as (separator peeling) → (circuit alignment) → (main bonding) are required, there is a problem that the connection is lengthened, the yield is reduced, and the cost is increased.

Further, as the anisotropic conductive material, there has been proposed a material in which conductive particles are coated with a resin insoluble in an adhesive as disclosed in Japanese Patent Application Laid-Open No. 62-40183 published after the present application.

This anisotropic conductive material is prepared by mixing solder metal particles with a compounding resin consisting of epoxy resin and aminoethylpiperazine and curing it, then crushing it with a crusher into particles, dispersing them in an adhesive, and connecting sheets. Then, the connection sheet is placed so as to overlap the electrodes, and the coating is broken by the pressure bonding force to secure the electrical connection.

As for the anisotropic conductive material, "Electronic Technology" 19
1984, Vol. 26, No. 7, page 117, "Nikkei Electronics" July 16, 1984, page 102, etc.

Further, in JP-A-62-35410, an anisotropic conductive material for electrical connection using a chop in which conductive fibers are coated with a coating resin, and the conductive fibers have a predetermined diameter. , And that the anisotropically conductive fiber is formed into a film while applying a shearing force.

However, since this technology uses conductive fibers, when conductive fiber orientation is not taken into consideration, conductive fibers may be placed between adjacent electrodes. Therefore, there is a possibility that electrical continuity may occur, which necessitates a treatment for orienting the conductive fibers.

[Means and Actions for Solving Problems]

The present invention has been made in view of the above, and in order to obtain high resolution, fine particles of a conductive material are encapsulated in a shell made of an electrically insulating polymer material to form microcapsules, and these are targeted. Placed closely on the surface to form a film,
Alternatively, the invention provides an anisotropic conductive material for electrical connection, which is processed into a film shape.

〔Example〕

Hereinafter, the anisotropic conductive material for electrical connection according to the present invention will be described in detail.

FIG. 1 shows an embodiment of the present invention, and the same parts as those in FIG. 4 are indicated by the same reference numerals, so that the duplicated description will be omitted. Anisotropic conductive microcapsule layer is formed by screen-printing or spraying the anisotropic conductive microcapsule 10 which is encapsulated in an insulating material and encapsulated in a microcapsule onto a substrate 5 provided with electrodes 4. Then, the other substrate provided with the other electrodes facing each other is aligned and then pressed or heated and pressure-bonded to form an anisotropic conductive material for connecting the electrodes to each other.

Here, as shown in FIG. 2, the anisotropic conductive microcapsule 10 is composed of a core substance 11 and a single-layer or multiple coating substances 12 that coat the core substance 11.

As the core substance 11, gold, platinum, silver, copper, iron, nickel,
Metals and metal compounds such as aluminum and chromium (IT
O, solder, etc.), conductive inorganic materials such as conductive carbon and conductive inorganic compounds, conductive organic compounds such as organic metal compounds, and the like can be used. The coating substance 12 is an electrically insulating polymer material. Phenolic resin,
Yuria resin, melamine resin, allyl resin, furan resin,
Thermosetting polymer such as polyester, epoxy resin, silicone resin, polyimide resin, polyurethane, Teflon resin, polyethylene, polypropylene, polybutylene,
Polymethylmethacrylate, polystyrene, ocrylonitrile-styrene resin, styrene-butadiene resin, acrylonitrile-styrene-butadiene resin, vinyl resin, polyamide resin, polyester resin, polycarbonate, polyacetal, ionomer resin, polyether sulfone, poly (phenyl) Oxide), poly (phenylene sulfide), polysulfone, polyurethane, thermoplastic resin such as fluororesin (PTFE, PCTFE, polyvinylidene fluoride), fibrin-based resin (ethyl cellulose, cellulose acetate, cellulose propionate, nitric acid) Organic-inorganic compounds such as cellulose) can be used.

In encapsulating the core substance 11 with such a coating substance 12 to form microcapsules, a chemical production method (for example, an interfacial polymerization method, an in situ polymerization method, a liquid hardening coating method, etc.) or a physical / mechanical production method (for example, , Spray drying method, air suspension coating method, vacuum deposition coating method, electrostatic coalescence method,
Melt dispersion cooling method, inorganic encapsulation method, etc.) or physicochemical manufacturing method (eg, coacervation method, interfacial precipitation method, etc.). Note that there are many publications on microcapsules, such as Tamotsu Kondo and Masumi Koishi, "Microcapsules" published by Sankyo Publishing.

The coating substance 12 that wraps the core substance 11 and encapsulates it into microcapsules not only functions as an insulating substance, but is also melted by heating and formed on the substrate 5 by reducing the film pressure applied to the surface of the core substance 11 by pressing. It has a function of adhering between the electrodes 4 that are in contact with each other. Insulation, adhesion, and slip by multiplying the film substance 12 (by adjusting the slip between anisotropic conductive microcapsules excessively, a single layer is easily formed when applied to the lower substrate) It is possible to improve reliability by dividing the function into, for example.

Next, formation of the anisotropically conductive material will be described with reference to FIGS. 1 (a) and 1 (b) by taking a substrate connection as an example.

An anisotropic conductive microcapsule 10 as shown in FIG.
m (value calculated from the requirement of 20 lines / mm resolution), and apply this to a predetermined portion of the lower electrode substrate 5 by screen printing or spraying (shown in FIG. 1 (a))
To do. Then, after aligning the upper electrode substrate 5 (or flexible connector, IC electrode pad, etc.), the electrodes between the two substrates are firstly pressed by pressing or thermocompression bonding these.
Connect as shown in Figure (b).

As shown in FIG. 1 (b), if the anisotropic conductive material according to the present invention is used for electrical connection, the anisotropic conductive material 1 having a uniform particle size is obtained.
0 exists uniformly on the substrate 5, and a molten insulating material exists between the conductive materials, so that an insulating layer is always formed between the conductive fine particles, and an electrical short circuit phenomenon does not occur. . Therefore, the conventional inconvenience as shown in FIG. 5 does not occur. Therefore, both reliability and resolution can be improved. Incidentally, the resolving power can be obtained as an arbitrary value by adjusting the particle diameter of the core substance 11 and the film thickness of the film 12.

Any value can be obtained.

Further, since the softened coating material covers the periphery of the conductive portion of the conductive particles, when the conductive particles are metal, oxidation, corrosion, and migration are prevented, so that conductivity can be stably obtained for a long period of time.

Furthermore, since the present invention uses anisotropically conductive particles,
Insulation between adjacent electrodes can be surely obtained as compared with the one using the conductive fiber disclosed in the above publication.

Conventionally, when forming an anisotropic conductive film, an insulating film material and conductive particles are directly kneaded and then shaped into a sheet or tape. Similarly, also in the present invention, as shown in FIG. 3, conductive particles are microencapsulated to form anisotropic conductive microcapsules 10, which are formed into a sheet or tape by a roller 15 (or a heat roller or the like). A directional conductive film can be manufactured.

〔The invention's effect〕

As described above, according to the anisotropic conductive material for electrical connection of the present invention, the conductive fine particles are coated with an electrically insulating substance capable of forming a conductive portion in the conductive fine particles by reducing the film thickness by the action of heat and pressure. Therefore, that is, since the conductive particles are wrapped with an electrically insulating substance to be microencapsulated, there is always an electrically insulating substance on the side surface of the electrically conductive particles,
Even if anisotropically conductive particles aggregate between adjacent electrodes, short circuit does not occur, and high resolution can be obtained. further,
The electrically insulating substance that coats the conductive particles is melted and softened by the action of heat, and further moved by pressure to move in the array direction of the anisotropically conductive material to reduce the film thickness, ensuring the conductivity in the connecting direction. Obtainable. Moreover, since the material of the conductive particles is not selected, ohmic connection can be performed according to any electrode material.

Further, in the above-mentioned prior art, since the coating resin is destroyed by pressure and pressure, not only the destruction of the opposing electrodes but also the undesired lateral destruction is caused, which causes a short circuit in the lateral direction. While there is a risk of increasing
The present invention does not utilize destruction of the coating due to pressurization, but melts and softens the electrically insulating substance by the action of heat, and further moves the electrically insulative substance in the arrangement direction of the anisotropically conductive material by the pressure. Since the film thickness is reduced by this, the dielectric strength of the portion where the film pressure is reduced becomes extremely low, and sufficient electrical conduction can be obtained, so it is possible to reliably obtain conductivity between the opposing electrodes. In addition to being able to do so, it has an extremely excellent effect that the electric insulation in the lateral direction is surely secured.

[Brief description of drawings]

1 (a) and 1 (b) are sectional views showing an embodiment of the present invention, and FIG.
FIG. 1 is a sectional view of micronized conductive particles according to the present invention,
FIG. 3 is a production explanatory view of the anisotropic conductive film in the present invention,
4 (a) and 4 (b) are explanatory views of connection of electrodes using a conventional anisotropically conductive material, and FIG. 5 is an explanatory view showing occurrence of connection troubles due to conventional materials. Explanation of symbols 4 ... Electrode, 5 ... Substrate 10 ... Anisotropic conductive microcapsule 11 ... Core material, 12 ... Coating material

Claims (4)

[Claims] 1. Use of anisotropically conductive particles in which the surface of the electrically conductive particles is coated with an electrically insulating substance capable of forming a conducting part in the electrically conductive particles by reducing the film thickness by the action of heat and pressure. Characteristic anisotropic conductive material for electrical connection. 2. The anisotropic conductive material for electrical connection according to claim 1, wherein the anisotropic conductive particles have a predetermined particle size. 3. The anisotropic conductive material for electrical connection according to claim 1 or 2, which comprises using the anisotropic conductive particles in close contact with each other. 4. The method according to claim 1, wherein the anisotropically conductive particles are formed into a film and used.
An anisotropic conductive material for electrical connection according to the item.