JPS61264604A - Anisotropic conductive sheet - 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 Field of Application) The present invention relates to a so-called anisotropic conductive sheet that has conductivity only in the thickness direction of the sheet. The present invention relates to an anisotropic conductive sheet that can be adapted to any mating pattern spacing by selecting the spacing and fine metal powder. In recent years, with the miniaturization of electronic components and circuits, anisotropically conductive sheets are widely used in electronic watches, cameras, calculators, etc. as materials for interconnecting circuit elements housed in limited spaces. It is being

(Prior art) Conventional conductive materials include (a) ■plastic connectors. This is a product in which conductive rubber-like elastic bodies and insulating rubber-like elastic bodies made of insulating rubber-like elastic bodies containing an 8I conductive substance are laminated alternately and in multiple layers, and sliced thinly in the lamination direction. In addition, (b) an anisotropic conductive sheet sliced in the same way as (a) using paint for the conductive layer and insulating layer to reduce the pitch, and (c) conductive polymer materials such as metal particles and graphite. Pressure-sensitive anisotropic conductive materials in which particles are mixed and dispersed are known.

(Problems to be Solved by the Invention) However, the conductive rubber-like elastic body in (a) contains a large amount of conductive substance in order to lower the resistance, and therefore has high hardness and poor rubber elasticity. Again (a).

(0) When mounting both of them, an equally large pressure load is required to clamp them between connected objects, for example,
In addition, the connected objects must be strong enough to withstand the above load. (B).

In (c), the sheet has conductivity in the thickness direction when pressurized, but the sheet also has the disadvantage of easily losing insulation in the horizontal direction, and cannot be used as an interconnector for connecting extremely small proximity circuits. There was a vacancy.

(Means for Solving the Problems) The present invention is a new and improved anisotropically conductive material that overcomes the drawbacks of such conventional anisotropically conductive materials, and is suitable for large-sized connectors for automobiles and instruments. In addition, the present invention provides an anisotropically conductive sheet suitable for making electronic parts thinner and lighter. The product of the present invention has the following configuration. This is characterized by conductive metal particles embedded in the voids of an insulating film and coated with an insulating resin on both sides of the sheet in the thickness direction. However, since the embedded metal particles are exposed and come into direct contact with the adherend, the sheet has conductivity only in the thickness direction. Therefore, even if the conductor pattern on the adherend is small, a stable electrical connection can be maintained only in the thickness direction of the sheet 1~, and furthermore, because the number of metal particles embedded in the insulating film per unit area is constant. , the actual contact area of each pattern on the adherend is uniform. It is desirable that the size of the metal particles to be buried be equal to or larger than the thickness of the insulating film.
Although it is preferable to bury only one, there will be no problem if two or more are buried.

(Example) Hereinafter, the product of the present invention will be explained in detail with reference to the accompanying drawings. 1 to 3 illustrate examples of the present invention, with FIG. 2 being a front view and FIG. 3 being a cross-sectional view. After overlapping the insulating resin 3 held by the protective sheet 4 on one side of the insulating film 2, the metal particles 1 are embedded in the voids of the insulating film 2. Thereafter, the insulating resin 3- held by the protective sheet 4- is superimposed on the insulating film 2 and integrated. Here, the insulating resins 3゛, 3゜ held on the protective sheets 4, 4' are adhesives or adhesives such as various synthetic resins 2, synthetic rubber, etc. It can be formed by a coating method such as a printing method, a brushing method, a roll coating method, a spray method, etc. On the other hand, it is also possible to directly coat and integrate the insulating film 2.

Furthermore, it is also possible to embed the metal particles 1 in the voids of the insulating film 2 only in the part that contacts the conductive part of the adherend according to the shape of the pattern of the conductive part of the adherend. It is also possible to create a gap in advance in the film 2 only in the portion that contacts the conductive portion of the adherend, and then embed the metal particles 1 therein.

The metal particles 1 are preferably spherical with a particle size of about 20 to 150μ, and the material is a single metal such as gold, silver, copper, aluminum, chromium, etc.
Alternatively, solder, alloys such as stainless steel, two single metal alloys, or plastics coated with a highly conductive metal such as silver may also be used. The insulating film 2 is made of synthetic resin such as polyester, has a thickness of approximately 10 to 150 μm, and is formed using a processing method using light energy such as laser processing to have a diameter of the film at the position where the metal particles 1 are most closely packed. Create a cylindrical void with a size equal to or greater than the thickness of the

When using the anisotropic conductive sheet of the present invention, peel off the protective sheet 4 on one side, apply the insulating resin 3 to the wiring board 5 which is one adherend, peel off the protective sheet 4- on the opposite side, A wiring board 5', which is another adherend, is fixed by applying it to the insulating resin 3', and the conductive connection part is set at 10 to 15 g f /
By pressure welding or thermal pressure welding at approximately cd, the conductors 6 and 6' of the wiring boards 5 and 5' are electrically connected through the metal particles 1 as shown in FIGS. 4 and 5.

<Effects of the Invention> As explained above, the sheet of the present invention has metal particles with a size equal to or larger than the thickness of the film embedded in the voids of the insulating film, and an insulating film held on both sides of the film by protective sheets. It is characterized by having conductivity only in the thickness direction of the sheet through the metal particles by pressure welding or thermo-pressure welding. Furthermore, the effects of this sheet will be described.

(1) Since the metal particles are embedded in the voids at the closest packing position, the contact area of the metal particles in each pattern of the conductive part of the adherend is uniform, making it possible to maintain a constant contact electrical resistance per adhesive area. can.

(2) Spherical metal particles are deformed by pressure welding or thermocompression welding, and the contact area with the adherend becomes large, so that the contact electrical resistance becomes an extremely small value.

(3) The insulating resin that sandwiches the insulating film from both sides moves magnetically due to pressure welding or thermocompression welding, and in the areas where the metal particles and the adherend do not come into contact, the insulating resin adheres to the adherend. Alternatively, if it is bonded to an adherend by thermo-compression welding, a stable conductive state can be maintained without applying any pressure-welding load.

(4) The metal particles in the insulating film are buried in the voids at the closest packing position, and the electrical contact resistance per adhesive area is constant, so there is no need for precise positioning during mounting, improving mounting workability. can be significantly increased.

[Brief explanation of the drawing]

FIGS. 1 to 3 show an embodiment of the Tatsumi lightning conducting sea 1 according to the present invention, in which FIG. 1 is a partial perspective sectional view, FIG. 2 is a front view of main parts, FIG. 3 is a sectional view of the main part. FIGS. 4 and 5 are sectional views of main parts of the horizontal conductive sheet of the present invention in a state in which it is pressed into contact with objects to be connected. 1... Metal particles 2... Insulating film 3.3'... Insulating resin 4.4'... Protective sheet 5.5'... Wiring board 6.6'... Conductor

Claims (2)

[Claims] (1) An anisotropically conductive sheet characterized by having a structure in which fine powder metal is embedded in the voids of an insulating film, and both ends of the sheet in the thickness direction are coated with an insulating resin. (2) An anisotropic conductive sheet according to claim 1, characterized in that the fine metal powder is made into spherical shapes.