JPH0799644B2 - Anisotropically conductive material for electrical connection - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anisotropically conductive material for electrical connection in which fine particles of a conductive material are coated with a coating material of an electrically insulating material to form so-called microcapsules so that arbitrary resolution can be obtained.

[0002]

2. Description of the Related Art As a conventional anisotropic conductive material for electrical connection,
For example, as shown in FIG. 4A, there is one in which 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. 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 pressed and heated by, 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 substrates 5 are extruded together. Connected by film 2, FIG.
As shown in (b), the two substrates are connected by the anisotropic conductive material.

However, in the conventional anisotropic conductive material,
Since it is difficult to uniformly disperse uniform conductive particles with a particle size on the order of several μm or less in the film, it is suitable for connecting high-resolution (10 / mm or more) multi-contact electrodes for the purpose of IC mounting. It could not be used (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 lines / mm, the electrode pitch is 25 μm. For this reason,
Although it is necessary to uniformly disperse uniform conductive particles having a particle size of several μm order or less in the film, according to the conventional technique,
As shown in FIG. 5A, there are problems such as pseudo collection as shown in FIG. 5, short circuit between adjacent electrodes due to mixing of large-sized particles as shown in FIG. 5B, and occurrence of an insulating state due to no particles as shown in FIG. I couldn't get credibility. In addition, since the conventional anisotropic conductive film is a sheet or tape,
Since complicated processes such as (cutting) → (temporary attachment) → (temporary adhesion) → (separator peeling) → (circuit alignment) → (main adhesion) are required, the connection will take longer and the yield will decrease. However, there is a problem that this leads to an increase in cost.

Further, as an anisotropic conductive material, there has been proposed one in which conductive particles are coated with a resin insoluble in an adhesive, as disclosed in Japanese Patent Application Laid-Open No. 62-40183, which was published after the application of the original application. ing. 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, the contents described in “Electronic Technology”, 1984, Vol. 26, No. 7, page 117, and “Nikkei Electronics”, July 16, 1984, page 102 are described. There are contents etc.

[0005]

[SUMMARY OF THE INVENTION The present invention has been made in view of the above, in order to obtain high resolution, fine particles of conductive material in the shell of electrically insulating polymeric material The present invention provides an anisotropic conductive material for electrical connection, which is wrapped to form microcapsules, which are closely arranged on a target surface to form a film, or processed into a film.

[0006]

[Means for Solving the Problems] To solve the above problems
In the present invention, as an anisotropic conductive material for electrical connection,
The surface of the particles is reduced in thickness by the action of pressure,
The electrically conductive particles are coated with an electrically insulating substance that can form a conducting portion.
Anisotropically conductive particles were used.

[0007]

[Action] As an electrically insulating substance that coats the conductive particles,
Effect of pressure on the surface of conductive particles Reduce the film thickness by
The conductive particles are covered with an electrically insulating substance that can form a conducting part.
Since covered anisotropic conductive particles are used, it is possible to
By applying pressure, the membrane pressure is reduced and the conductive particles become conductive.
Can be formed.

[0008]

The anisotropic conductive material for electrical connection according to the present invention will be described in detail below. FIG. 1 shows an embodiment of the present invention and is shown with the same reference numerals as FIG. 4, so duplicate description is omitted, but in this embodiment, fine particles of a conductive material are coated with an electrically insulating substance. An anisotropic conductive microcapsule layer is formed by screen-printing or spraying the anisotropic conductive microcapsule 10 encapsulated in a shell and microcapsulated on a substrate 5 provided with an electrode 4.
The other substrate provided with other electrodes facing each other is aligned and then pressed to form an anisotropic conductive material for connecting the electrodes.

Here, as shown in FIG. 2, the anisotropic conductive microcapsule 10 is composed of a core substance 11 and a single-layer or multi-layer coating substance 12 covering 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 substances such as conductive carbon and inorganic compounds, and conductive organic compounds such as organic metal compounds can be used. In addition, as the coating substance 12, heat of an electrically insulating polymer material such as phenol resin, urea resin, melamine resin, allyl resin, furan resin, polyester, epoxy resin, silicone resin, polyimide resin, polyurethane, or Teflon resin is used. Curable polymer,
Polyethylene, polypropylene, polybutylene, polymethylmethacrylate, polystyrene, acrylonitrile-
Styrene resins, styrene - butadiene et down resin, acrylonitrile - styrene - butadiene et emissions resins, vinyl resins, polyamide resins, polyester resins, polycarbonate, polyacetal, ionomer resins, polyether sulfone-one, poly (phenyl oxide), poly (Pueni Lensfide), porsulfone, polyurethane, thermoplastic resin such as fluororesin (PTFE, PCTFE, polyvinylidene fluoride), fibrin resin (ethyl cellulose, cellulose acetate, cellulose propionate, cellulose propionate, cellulose nitrate, etc.) Organic-inorganic compounds can be used.

In encapsulating the core substance 11 with the 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 method is used. Manufacturing method (for example,
Spray drying method, air suspension coating method, vacuum deposition coating method, electrostatic coalescence method, melting 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 which encloses the core substance 11 and encapsulates it in microcapsule not only functions as an insulating substance, but is formed on the substrate 5 by reducing the film thickness coated on the surface of the core substance 11 by pressurization. It has a function of adhering between the electrodes 4. Multiple layers of the coating substance 12 for insulation, adhesion, and slipping (by adjusting the slippage between anisotropic conductive microcapsules appropriately, a single layer can be 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), taking substrate connection as an example. The anisotropic conductive microcapsules 10 as shown in FIG.
05 μm (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 (see FIG. 1).
(Shown in (a)). Then the upper electrode substrate 5 (or a flexible connector, IC electrode pads, etc.) After eye combined, Figure 1 an electrode between the thus two to these pressure board
Connect as shown in (b).

As shown in FIG. 1B, if the anisotropic conductive material according to the present invention is used for electrical connection, the anisotropic conductive material 10 having a uniform grain size is uniformly present on the substrate 5, and Since the conductive material is covered with the insulating material, the insulating layer is always formed between the conductive fine particles, and the 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. The resolution can be set to an arbitrary value by adjusting the particle diameter of the core substance 11 and the film thickness of the coating film 12. Conventionally, when forming an anisotropic conductive film, the insulating film material and the conductive particles are directly kneaded and then formed into a sheet or shaped. Similarly, in the present invention, as shown in FIG. 3, conductive particles are microencapsulated to form anisotropic conductive microcapsules 10, and the anisotropic conductive microcapsules are formed into a sheet or tape by a roller 15 (or a heat roller or the like). A conductive film can be manufactured .

[0014]

As described in the foregoing, according to the anisotropic conductive material for electrical connection of the present invention, electrical insulation capable of forming a conductive portion conductive particles by subtracting the film thickness by the action of the pressure to the conductive fine particles Since the conductive particles are coated with a conductive substance, that is, the conductive particles are wrapped with an electrically insulating substance to form microcapsules, the electrically insulating substance always exists on the side surface of the conductive particles. Even if particles agglomerate, short circuit does not occur, and high resolution can be obtained.
Furthermore, since the electrically insulating substance that coats the conductive particles moves in the arrangement direction of the anisotropically conductive material by pressure and the film thickness is reduced, it is possible to reliably obtain the conductivity in the connection direction. Moreover, since the material of the conductive particles is not selected, ohmic connection can be performed according to any electrode material.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view of micronized conductive particles according to the present invention.

FIG. 3 is an explanatory view for manufacturing an anisotropic conductive film according to the present invention.

FIG. 4 is an explanatory view of connection of electrodes using a conventional anisotropic conductive material.

FIG. 5 is an explanatory view showing the occurrence of a connection trouble caused by a conventional material.

[Explanation of symbols]

4 electrodes, 5 substrate, 10 anisotropically conductive microcapsules, 11 core substance, 12 coating substance.

Claims (1)

[Claims] The surface of claim 1 conductive particles, and wherein the use of anisotropic conductive particles coated with electrically insulating material by subtracting the film thickness can form a conductive portion on the conductive particles by the action of the pressure Anisotropic conductive material for electrical connection.