JPH0335779B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to connectors, particularly package type ICs and leadless chip carriers, which are made by dispersing and orienting metal fibers in a sheet member made of a non-conductive polymer material. This paper relates to improvements to anisotropically conductive connectors that are useful for electrical connections such as type ICs.

(Prior technology) Anisotropically conductive sheet-like composite materials are used for connections between circuits such as leadless ICs and hybrid circuits. A non-conductive polymer material and a conductive fiber material are mixed together to form a plasticized mixture, which is then flowed in a certain direction to be plastically deformed to form the conductive fibers into a continuous phase of the non-conductive polymer material. The conductive fiber material is oriented in a substantially constant direction, the polymer material is cured, and the cured product is sliced along a plane substantially perpendicular to the orientation direction of the conductive fiber material.
It is known that a sheet of non-conductive polymer material has a large number of conductive fibers dispersed and oriented in the thickness direction of the sheet so that some of the conductive fibers penetrate through the sheet. (See Publication No. 6083).

Therefore, various kinds of anisotropic conductive sheet materials can be made by appropriately selecting the non-conductive polymeric material mentioned above or the conductive fibrous material dispersed and oriented therein. , have been put into practical use, but since there are demands for low contact resistance (several + ohms), improved compression repeatability, and high current capacity, ICs using metal fibers as conductive fibrous materials are particularly popular. Connector, FPC
It is commonly used as a connection connector.

However, when using metal fibers, the fibers become short during the mixing and dispersion process.
As a result, the fiber length follows the Poisson distribution, especially the distribution obtained by the straight line of the Rosin-Rammler diagram, so we harden the polymeric material containing such metal fibers and bend it perpendicular to the orientation direction of the metal fibers. An anisotropic conductive sheet obtained by slicing on the plane of In some cases, the metal fibers are flush with the sheet, so the lengths of these metal fibers vary. Therefore, when this type of anisotropic conductive connector is used with pressure contact between electrodes, the pressure contact load is concentrated on the long metal fiber part, and the fiber is cut at the same height as the sheet surface that exists near the fiber. The metal fibers and the like that are attached cannot receive sufficient pressure contact force for electrical connection, and therefore there is a disadvantage that the conduction becomes uncertain or unstable in this part.

(Structure of the Invention) The present invention relates to an anisotropically conductive connector that solves the above-mentioned disadvantages, and is directed to an anisotropic conductive connector in which at least a portion of the metal fibers are contained in a sheet member made of a non-conductive polymer material. It is characterized by being arranged so as to penetrate through the member, and oriented so as to maintain a substantially constant direction at a substantially constant angle of 5° or more but less than 45° with respect to the perpendicular to the sheet surface. .

That is, the present inventors have conducted various studies on improving an anisotropically conductive connector in which metal fibers are oriented on a sheet member made of a non-conductive polymer material, and as a result, the inventors have found that when connecting the electrode body surfaces that are to be electrically connected, In a conventionally known anisotropic conductive connector in which metal fibers 2 are oriented perpendicularly to the thickness direction of a sheet member 1 made of a non-conductive polymer material as shown in FIG. 1, this is shown in FIG. As shown above, a metal foil conductor 4,
4', this metal fiber 2
Since the lengths of the connectors vary, the conduction becomes uncertain and unstable. However, as shown in Fig. 3, this anisotropically conductive connector is made of a sheet member 1 made of a non-conductive polymer material. A part of the metal fiber 2 penetrates through this sheet member, and it is tilted in a substantially constant direction by a substantially constant angle of 5° or more and less than 45° with respect to the perpendicular to the sheet surface. When an anisotropically conductive connector is oriented and is clamped between two printed wiring boards 3, 3' via metal foil conductors 4, 4' as shown in FIG. All the fibers fall in the same direction, and the pressure force acts on all the fibers, so even if there is some variation in the length of the metal fibers, there will be no partial contact failure, and the result will be stable. After discovering that electrical conductivity could be obtained, the present invention was completed by conducting research on the orientation method and angle of inclination of the metal fibers.

The non-conductive polymer material as a matrix material constituting the anisotropically conductive connector of the present invention and the metal fibers oriented thereon may be of known materials. Therefore, the non-conductive polymeric substances include thermoplastic polymeric substances such as polyester, polyvinyl chloride, polymethyl methacrylate, polyolefin, polyamide, polycarbonate, polystyrene, unsaturated polyester, polyurethane, organopolysiloxane, Examples include thermosetting polymer substances such as phenol, urea, melamine, and guanamine, as well as rubber-like elastic bodies such as natural rubber and various synthetic rubbers, but these include reinforcing fillers, plasticizers, pigments, It is used in combination with dyes, hardeners, stabilizers, etc. Furthermore, since the connector of the present invention is based on the conductivity of this metal fiber, it is necessary to have an electrical resistivity of 10 ^-4 Ωcm or less, and this includes gold, copper, etc. Examples include metal fibers made from nickel, brass, phosphor bronze, aluminum, etc., which have a diameter of 10 to 50 μm and a length of 10 to 50 mm.
It is better to use the same.

The orientation of the metal fibers into a non-conductive polymer material can be achieved by mixing the metal fibers into a non-conductive polymer material, and then molding this mixture into a rod or sheet using an extrusion molding machine or an injection molding machine. During this molding, the metal fibers are often oriented in the flow path direction when passing through a plate or die at the exit of the molding machine. The blending amount of this metal fiber is 0.1 to 20% of the non-conductive polymer material.
The amount may be set to % by volume, preferably 0.5 to 10% by volume, and when oriented in this manner, the fiber length of the metal fibers follows a Poisson distribution, particularly a distribution obtained from a Rosin-Rammler diagram.

The anisotropically conductive connector of the present invention is produced by curing the thus obtained molded product in which the metal fibers are oriented, and then holding the molded product at an approximately constant angle of 5° or more and less than 45° with respect to the orientation of the metal fibers. It can be obtained by slicing it into sheets. The thickness of this sheet is required to be such that at least a portion of the metal fibers penetrate through this sheet member. Therefore, this should be in the range of 0.1 to 1 mm. In addition,
The angle with respect to the fiber orientation direction at the time of slicing may be determined according to the orientation angle of the metal fibers in the intended anisotropic conductive connector of the present invention, but if this angle is less than 5 degrees, the above-mentioned tilting effect will not occur. If the angle is 45° or more, the contact force will decrease significantly due to the elastic recovery force of the matrix made of non-conductive polymer material, and the reliability of the contact will be impaired. Although a range may be required, the preferred angle is between 10 and 20 degrees.

Next, examples of the present invention will be given, and parts in the examples indicate parts by weight.

Example: 100 parts of silicone rubber compound KE-171U [trade name manufactured by Shin-Etsu Chemical Co., Ltd.], 65 parts of copper alloy metal fibers cut into lengths of 30 mm with a diameter of 30 μm, and silicone rubber vulcanizing agent C-2 [Company product name]
2 parts were kneaded with a mixing roll, extruded into a round bar with a diameter of 5 mm using a rubber extruder, and heated and vulcanized in an oven at 170°C for 10 minutes, resulting in a molded product with metal fibers oriented in the extrusion direction. Obtained.

Next, this round bar was sliced into 0.2 mm thick pieces at right angles to the vertical direction and at angles of 5°, 20°, and 45° to make four types of anisotropic conductive sheets.
When these were held in pressure contact between electrodes and the amount of pressure contact and contact resistance were measured, the results shown in Figures 5 and 6 were obtained, and the one sliced at an inclination angle of 20° had the best characteristics. showed that.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of a conventionally known anisotropically conductive connector, Fig. 2 is a longitudinal cross-sectional view of the anisotropically conductive connector clamped between electrodes, and Fig. 3 is a longitudinal cross-sectional view of the anisotropically conductive connector of the present invention. , FIG. 4 is a vertical cross-sectional view of this connector clamped between electrodes, and FIGS. 5 and 6 are diagrams showing the relationship between the amount of compression and the contact resistance value of the anisotropically conductive connector in the example. .

Claims (1)

[Claims] 1 Metal fibers are arranged in a sheet member made of a non-conductive polymeric material so that at least a part of the metal fibers penetrates the sheet member, and the metal fibers are arranged at an angle of 5° or more and less than 45° with respect to the perpendicular to the sheet surface. A connector characterized by being oriented at a substantially constant angle and in a substantially constant direction.