JPH0660712A - Anisotropically conductive material for electrical connection - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an anisotropic conductive material for electrical connection, which can obtain high resolution by preventing short circuit between anisotropic conductive particles. An anisotropic conductive particle is used, in which the surface of the conductive particle 11 is coated with an electrically insulating substance 10 capable of forming a conductive part in the conductive particle by reducing the film pressure by the action of pressure. Anisotropic conductive material for electrical connection.

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.

[0003]

However, in the conventional anisotropic 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 difficult to disperse the IC. High resolution for mounting etc. (10 / mm
Above) could not be used to connect multi-contact electrodes
(By the way, the limit is 5 lines / mm (line space = 100 μm) in the prior art). For example, 20
electrode pitch is 25 μm to obtain resolution of / mm
Becomes Therefore, 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 prior art, a pseudo-collection as shown in FIG.
As described above, problems such as short-circuiting between adjacent electrodes due to mixing of large-diameter particles and generation of an insulating state due to the absence of particles as shown in c occur, and sufficient reliability cannot be obtained. Moreover, since the conventional anisotropic conductive film is in the form of a sheet or tape, (cutting) → (temporary attachment) → (temporary adhesion)
→ (Separator peeling) → (Circuit alignment) → (Main adhesion)
Since it requires a complicated process such as
There is a problem that the yield is reduced and the cost is increased.

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 an epoxy resin and aminoethylpiperazine and curing it, then crushing it with a crusher into particles, dispersing them in an adhesive, 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]

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, It is intended to provide an anisotropic conductive material for electrical connection, which is formed by closely disposing these on a target surface to form a film or is processed into a film.

[0006]

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 pressured or heated and pressure-bonded to form an anisotropic conductive material for connecting the electrodes to each other.

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. Further, 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 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), Organic-inorganic compounds of thermoplastic polymers such as porsulfone, polyurethane, fluorinated resins (PTFE, PCTFE, polyvinylidene fluoride), fibrin-based resins (ethyl cellulose, cellulose acetate, cellulose propionate, cellulose propionate, cellulose nitrate, etc.) Can be used.

In encapsulating the core substance 11 with the coating substance 12 and microencapsulating it, 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, 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," Sankyo Publishing.

The coating substance 12 encapsulating and encapsulating the core substance 11 not only functions as an insulating substance, but is formed on the substrate 5 by reducing the film thickness of the surface of the core substance 11 which is coated by pressure. 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 the connection of substrates as an example. The anisotropic conductive microcapsules 10 as shown in FIG. 2 prepared by the above-described manufacturing method were used, and the particle size was 5 ± 0.2 μm and the film thickness was 0.8 ± 0.
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, after aligning the upper electrode substrate 5 (or a flexible connector, an IC electrode pad, etc.), the electrodes between the two substrates are connected by pressurizing or thermocompression bonding as shown in FIG. 1 (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. Next, an example in which anisotropic conductive connection is made by applying pressure will be described. The difference from the above-mentioned embodiment is that as the electrically insulating substance for covering the conductive particles, a material that can reduce the membrane pressure by applying pressure without heat to form a conductive part in the conductive particles is used. In point. Among the above-mentioned materials, the electrically insulating material having such a property can be mentioned. If an anisotropic conductive material for electrical connection is constructed using anisotropically conductive particles that are coated with conductive particles and microencapsulated with this material, ensure electrical connection of electronic components that must be heated. You can

[0012]

As described above, according to the anisotropic conductive material for electrical connection of the present invention, it is possible to reduce the film thickness of conductive fine particles by the action of heat and pressure to form conductive parts in the conductive fine particles. Since the conductive particles are coated with an insulating material, that is, the conductive particles are wrapped with an electrically insulating material to form microcapsules, the electrically insulating material always exists on the side surface of the conductive particles. A short circuit does not occur even if the functional particles aggregate, 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] 1. An anisotropic conductive particle coated with an electrically insulating material capable of forming a conductive portion on the surface of the conductive particle by reducing the film thickness by the action of pressure is used. Anisotropically conductive material for electrical connection.