JP2000123888A - Connecting method of lead wire to film base board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To electrically and mechanically connect a lead wire to a conductive layer without using a reinforcing plate by connecting the flat part arranged in the tip part of the lead wire to the conductive layer of a film base board forming the conductive layer on an insulating film by using an anisotropic conductive film. SOLUTION: In a film base board 1, a conductive layer 1b forming a circuit pattern of a metallic thin plate composed of copper or a copper alloy is arranged on a flexible insulating film 1a, and land 1c is arranged in the end part of the conductive layer 1b. A lead wire 2a of an electronic part 2 has on the tip the flat part 2b crushed by press working. An anisotropic conductive film 4 taken out according to a shape of the land 1c is placed on the land 1c, the flat part 2b of the lead wire 2a is superposed on it, and the anisotropic conductive film 4 is pressurized from both sides to be joined by heating. The flat part 2b may be formed by bending/crushing the tip part of the lead wire 2a in a U-shape. Thus, the contact area increases to increase electric current capacity and mechanical strength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for connecting leads such as electronic parts to a film substrate constituting an electric circuit.

[0002]

2. Description of the Related Art A conventional method for connecting lead wires of electronic components (eg, diodes, resistors, capacitors, etc.) to a film substrate will be described with reference to FIG. In FIG.
The film substrate 1 is formed by forming a conductive layer 1b made of a metal thin plate forming a circuit pattern of a predetermined shape on an insulating film 1a made of a flexible insulating plastic film such as PET (polyethylene terephthalate).
A through hole 1d is provided for connecting a lead wire. When the electronic component 2 is mounted on the film substrate 1, the mechanical holding force may be insufficient depending on the mounted electronic component 2 with the film substrate 1 alone. In this case, the reinforcing plate 3 is provided. The reinforcing plate 3 is made of, for example, an insulating plate such as bakelite, and is firmly attached to the back side of the insulating film 1a. Furthermore, the electronic component 2 has a wire-like lead wire 2a having a circular cross section for connection at both ends. Then, the leading end portion of the lead wire 2a is inserted into the through hole 1d of the land 1c of the film substrate 1 (where the conductive layer 1b is partially widened in order to perform solder connection), and the lead wire 2a is soldered. Is joined to the land 1c to make electrical connection.

[0003]

However, the conventional method of connecting the lead wire 2a of the electronic component 2 to the film substrate 1 has the following problems. That is, the mounting of the electronic component 2 on the film substrate 1 may require the reinforcing plate 3. In this case, the cost is increased by the cost of attaching the reinforcing plate 3 to the film substrate 1. Further, the place where the film substrate 1 is installed may be limited by the reinforcing plate 3 such that the thickness of the film substrate 1 is increased as a whole or the flexibility of the film substrate 1 is impaired. There was also a defect.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and comprises a flat portion provided at the tip of a lead wire, and the flat portion is formed by forming a conductive layer on an insulating film. A method for connecting a lead wire to a film substrate, comprising connecting to the conductive layer of the film substrate using an anisotropic conductive film.

[0005] Here, the anisotropic conductive film is formed by dispersing a large number of conductive fine particles such as a metal in a thermosetting adhesive and forming it into a film, and is supplied in a semi-cured state. By heating the anisotropic conductive film between two parallel flat plates while applying pressure, the two flat plates can be electrically and mechanically connected. In the connected state, the in-plane conductivity of the anisotropic conductive film is lower than that in the thickness direction, and the anisotropic conductive film has anisotropy in conductivity.

Therefore, according to the present invention, a flat portion is provided at the tip of a lead wire, and the flat portion is formed on the conductive layer of a film substrate formed by forming a conductive layer on an insulating film. When the conductive layer is connected by using the conductive layer, the lead wire can be electrically and mechanically connected to the conductive layer regardless of whether the conductive layer is formed of a thin metal plate or formed by printing a conductive paint. In this case, a conventional reinforcing plate for reinforcing the film substrate is not required.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a perspective explanatory view of one embodiment of a method for connecting a lead wire to a film substrate according to the present invention. In FIG. 1, the same parts as those described with reference to FIG. 3 are indicated by the same reference numerals. In FIG. 1, a film substrate 1 is provided with a conductive layer 1b for forming a circuit pattern by a thin metal plate made of copper or a copper alloy on a flexible insulating film 1a. A land 1c is provided. The lead wire 2a of the electronic component 2 has a flat portion 2b crushed by pressing at the tip. Then, the anisotropic conductive film 4 cut out according to the shape of the land 1c is placed on the land 1c,
The flat portion 2b of the lead wire 2a is superimposed thereon, and the anisotropic conductive film 4 is pressed and heated from both sides, and the flat portion 2b is
Join and connect to

[0010] The present invention is not limited to the above-described embodiment. As shown in FIG. 2, as shown in FIG. 2, the flat portion 2 b may be formed by bending the tip portion of the lead wire 2 a and then performing pressing to crush it. By doing so, the bonding area between the anisotropic conductive film 4 and the flat portion 2b increases, and the current capacity and mechanical strength can be increased. Therefore, the installation location is not limited because the cost is increased, the thickness of the film substrate 1 is increased as a whole, and the flexibility is impaired.

As described above, in the present embodiment, it is not necessary to attach a reinforcing plate to the film substrate 1 unlike the related art. The conductive layer 1b is not limited to a thin metal plate, and may be formed by printing a conductive paint such as a silver paste.

[0010]

As described above, according to the present invention, there is an excellent effect that a lead wire can be electrically and mechanically connected to a conductive layer of a film substrate without using a reinforcing plate.

[Brief description of the drawings]

FIG. 1 is a perspective explanatory view of one embodiment of a method for connecting a lead wire to a film substrate according to the present invention.

FIG. 2 is an explanatory perspective view of another embodiment.

FIG. 3 is a perspective view illustrating a conventional method of connecting a lead wire to a film substrate.

[Explanation of symbols]

 Reference Signs List 1 film substrate 1a insulating film 1b conductive layer 1c land 1d through hole 2 electronic component 2a lead wire 2b flat portion 3 reinforcing plate 4 anisotropic conductive film

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[Procedure amendment]

[Submission date] November 19, 1998 (1998.11.
19)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG.

FIG. 2

FIG. 3

Claims (1)

[Claims] 1. A flat portion is provided at a leading end portion of a lead wire, and the flat portion is connected to the conductive layer of a film substrate formed by forming a conductive layer on an insulating film using an anisotropic conductive film. A method for connecting a lead wire to a film substrate.