JPH06260232A - Connecting structure of film connector - Google Patents

Abstract

PURPOSE:To form a connecting structure of film connector capable of easily electrically connecting a conductive line to an electrode to be connected with high reliability without using a conductive particle participating in anisotropic conductivity. CONSTITUTION:In a connecting structure of a film connector 1, a plurality of conductive lines 3 consisting of conductive paste are provided on an insulating flexible polymer film 2, and projections 4 integrated with the conductive lines 3 consisting of the conductive paste are provided on the surface of the conductive lines 3. An insulating adhesive layer 5 is further provided thereon. This is put on a board 6 having an electrode to be connected, and the projections 4 are brought into contact with the part of the electrode to be connected through the instulating adhesive layer 5 melted when this connector is heated and pressurized to provide an electric connection there.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film-like connector connection structure, particularly a liquid crystal display (LCD), electroluminescence (EL), light emitting diode (LE).
D), electrochromic display (ECD),
Used to connect between the contacted electrodes (connection terminals) of a display such as a plasma display (PDP) and the contacted electrodes (connection terminals) of a circuit board on which the driving part is mounted or various electric circuit boards. The present invention relates to a connection structure for a film connector.

[0002]

2. Description of the Related Art Conventionally, film-shaped connectors have been LC
It is used for connecting a display body such as D, EL, LED, ECD, PDP and the like to a hard printed wiring board (PCB) or a flexible printed board (FPC), or a connection between PCB and FPC. With this film-type connector, however, the desired circuit pattern is formed on the insulating flexible polymer film with conductive paste, and conductive particles are dispersed and mixed with an insulating adhesive on the anisotropic conductive film. With an adhesive layer (Japanese Patent Publication No. 55-38073, Japanese Patent Publication No. 58-56996)
(See Japanese Patent Laid-Open Publication No. 6-52), or a circuit pattern is formed with an electrically conductive paste in which electrically conductive particles are dispersed and mixed on an insulating flexible polymer film, and an insulating adhesive layer is provided on the circuit pattern.
No. 500828 and Japanese Patent Application Laid-Open No. 62-154746) are disclosed.

However, with respect to this, the number of circuits of various electric circuit boards used in the film-like connector has been increased with the recent enlargement, colorization and miniaturization of the display, and it is included in one film-like connector. The number of lines is about 100 to 700, on the contrary, the distance between the conductive lines of the circuit pattern is 0.07 to 0.15 mm, and the pitch is 0.15 to 0.30 mm.
Therefore, continuity stability of the contact portion is required more than ever before.

[0004]

In the above-mentioned conventionally known film-like connector, the electrodes such as LCD, PDP and substrate are connected to the conductive line of the film-like connector through the conductive particles existing in the insulating adhesive. This is a structure in which some of the conductive particles come into contact with the electrodes that are the adherends, and some of them also come into contact with the conductive paste of the film-like connector. The insulative adhesive in 1 fixes the bonding between the electrodes and the conductive particles and between the conductive paste and the conductive particles to maintain the electrical connection.

Although gold is preferably used on at least the surface of the conductive particles in terms of reduction of contact resistance and environmental resistance, the gold-plated surface is chemically very clean and therefore is insulated. Poor adhesion to conductive adhesives, etc., and the external connection of heat, humidity, mechanical vibration, etc., can easily change the maintained connection state, resulting in increased contact resistance and eventually poor conduction. Was occurring. Further, since the conventional connection structure has a basic structure in which the number of contact points is at two positions, that is, the connected electrode side and the conductive paste side, there is a disadvantage that the above problem is further accelerated.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a connection structure for a film-like connector which solves the above disadvantages and problems, and it comprises a plurality of insulating flexible polymer films made of a conductive paste. In the film-like connector for electrically connecting the conductive line and the electrode to be connected facing the conductive line, the conductive line is provided on the conductive paste, and the insulating adhesive layer is further provided on the conductive line. It is characterized in that a projection integrated with a conductive paste made of paste is provided, and the conductive line and the electrode to be connected are electrically connected by the projection through an insulating adhesive.

That is, the present inventor has conducted various studies in order to develop a connection structure for a film-like connector having a stable contact resistance. As a result, an organic polymer binder and conductive particles are formed on an insulating flexible polymer film. In a conventionally known film-like connector in which a plurality of conductive lines are provided by a dispersed conductive paste, and an insulating adhesive layer is further provided on the conductive line, the same kind, preferably on the conductive line made from the conductive paste, Is a conductive paste made of the same material and is provided with a protrusion, and an insulating adhesive layer is provided on it. When this film connector is heated and pressed during use, the insulating adhesive melts and flows. Therefore, it has been found that this conductive line and the electrode part to be connected are electrically connected by the protrusion through the insulating adhesive layer. It has been confirmed that even if there are no conductive particles involved in anisotropic conductivity, it is possible to easily electrically connect this conductive line to the connected electrode with a small number of contact points and low contact resistance. And completed the present invention. This will be described in more detail below.

[0008]

The present invention relates to a connection structure for a film-like connector, which has a plurality of conductive lines made of a conductive paste provided on an insulating flexible polymer film as described above, and has an insulating adhesive on the conductive lines. In a film-shaped connector provided with an agent layer, a projection integrated with a conductive line made of a conductive paste is previously provided on the surface of the conductive line, and the conductive line and the connected electrode are formed by this projection through the insulating adhesive layer. It is characterized by being electrically connected, according to this, it becomes unnecessary to add conductive particles involved in the conventionally known anisotropic conductivity,
This has the advantage that the number of contact points is small and the electrical connection between the conductive line and the electrode to be connected can be easily performed with low contact resistance.

The film connector used in the present invention is, for example, the one shown in FIG. FIG. 1 is an enlarged vertical cross-sectional view of a film-like connector used in the present invention. The film-like connector 1 comprises a conductive flexible polymer film 2 and a plurality of conductive lines 3 made of a conductive paste.
And a projection (including the concept of a short projection, the same applies hereinafter) 4 integrated with the conductive line 3 by the conductive paste on the conductive line 3, and an insulating adhesive layer on the projection 4. 5, which is an enlarged vertical cross-sectional view of another example of the film-like connector used in the present invention, as shown in FIG. First, the insulating particle fixing adhesive layer 8 containing the insulating particles 7 may be provided, and the conductive lines 3, the protrusions 4, and the insulating adhesive layer 5 may be provided on the surface by the same method as described above. The film connector 1 is used by mounting it on a substrate 6 having electrodes to be connected.

Examples of the insulating flexible polymer film forming the film-like connector 1 include polyimide, polyethylene terephthalate, polycarbonate,
Polyphenylene sulfide, polybutylene terephthalate, polyethylene naphthalate, poly-1,4-cyclohexane dimethyl terephthalate, polyarylate,
Examples include those with a thickness of 5 to 50 μm, which are made of liquid crystal polymer, but these require a small dimensional change during holding and handling of the connector in order to connect multiple high-precision electrode groups. However, the thickness of the electrode of the connected body is about 100 μm, and it is necessary to follow the irregularities between the electrodes, so that the thickness is preferably 10 to 25 μm.

The conductive paste used here is a dispersion of conductive particles in an organic polymer binder. The organic polymer binder may be a vinyl chloride resin, a vinyl acetate resin or a copolymer thereof. Acrylic resin, thermoplastic polyester, thermoplastic polyurethane,
Polybutadiene, polyimide resin, epoxy resin, alkyd resin, phenolic resin, etc. are exemplified, but these give isocyanates, amines, acid anhydrides, etc. as necessary to impart resistance to external force such as heat and vibration. It may be cured by using the above-mentioned curing agent.

The conductive particles include gold, silver, copper,
Examples include metal particles such as nickel and palladium, carbon particles, graphite particles, carbon short fibers, or those particles whose surfaces or insulating plastic particles have a metal coating, which have a particle size of 5 μm or less. It is good to say However, this shape is not particularly limited, and may be any of granular, scale-like, plate-like, dendritic, and irregular shapes, but the smaller the particle size, the larger the surface area, so the printing condition is controlled. In order to do so, it is preferable to select the type and particle size in consideration of viscosity and thixotropy. The organic polymer binder described above
The amount added with respect to 100 parts by volume may be 10 to 70 parts by volume from the viewpoint of the resistance value and economical efficiency of the obtained conductive paste.

When the conductive paste is prepared, the above-mentioned organic polymer binder may be dissolved in a solvent in advance. As the solvent, ester-based, ketone-based, ether ester-based, ether-based, alcohol-based, carbonized Hydrogen-based, for example, ethyl acetate, isobutyl acetate, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, butyl cellosolve acetate, methyl carbitol acetate,
Ethyl carbitol acetate, dibutyl carbitol acetate,
n-butyl ether, n-butyl phenyl ether, isobutyl alcohol, cyclohexanol, toluene,
Examples thereof include xylene, petroleum spirit, petroleum naphtha, etc., but usually ester-based, ketone-based, ether-based ones, and if necessary, a curing accelerator,
A leveling agent, a dispersion stabilizer, an antifoaming agent, a thixotropic agent, etc. may be added.

The conductive lines can be formed by this conductive paste by printing the liquid conductive paste by screen printing or gravure printing, or by applying a known method such as roll coating, bar coating or spray coating. Generally, screen printing may be performed so that a desired circuit pattern can be easily formed. In order to provide a projection integrated with this conductive line on this conductive line by a conductive paste, once a desired circuit is provided, it is printed again with a screen plate having a plurality of openings of, for example, 50 μmφ at a position required for connection. Method, viscosity and thixotropy. When using a conductive paste for screen printing, the fact that the mesh of the screen plate remains due to lack of fluidity makes use of this after forming the circuit pattern, before drying. It may be carried out by a method in which a roll, a flat plate, or a net having an adhesive property is brought into contact with the roll, and then the roll is quickly peeled off to fluff.

In this case, however, when highly precise alignment and control of the height of the protrusions are required due to the small pitch between the patterns of the conductive lines, as described above with reference to FIG. An organic polymer binder, etc., in which insulating particles of uniform size such as polyimide resin, polyester resin, polyurethane resin, polyamide resin, phenol resin, epoxy resin, etc. are dispersed and mixed, is applied in advance on the insulating polymer film. The conductive line may be provided after the projection of the insulating particles is provided.

The insulating adhesive applied to the conductive line to form the film-like connector is not particularly limited, as long as it exhibits adhesive activity when heated and pressed. Thermoplastic, thermosetting, UV
Although it may be any of curable, EB curable, anaerobic curable, and moisture curable reaction curable, it is a non-adhesive solid state before connection work and pressure concentrated on the protrusions during connection. It is necessary for the protrusions to flow rapidly for about 2 to 20 seconds so that the protrusions come into contact with the connected portion.
The viscosity at the time of connection is required to be about 10 ³ to 10 ⁵ poise.

This thermoplastic material has the advantage that it can be bonded by heating at a relatively low temperature for a short time, has a long pot life, and the reaction curable material has a large bonding strength and excellent heat resistance. May be appropriately selected according to the purpose of use, and examples thereof include polyamide type, polyester type, ionomer type, EVA, EAA, EMA, EEA.
Examples thereof include polyolefin type, various synthetic rubbers, thermoplastic elastomer type, and their modified products and composites.

Further, as the thermosetting material, synthetic rubbers such as epoxy resin type, urethane type, acrylic type, silicone type, chloroprene type, nitrile type, etc., or a mixture thereof or a thermoplastic and thermosetting substance Examples of the mixture are those in which and are IPNized, but in any case, these are curing agents, vulcanizing agents, crosslinking control agents, deterioration inhibitors, heat resistance additives, heat conduction improvers, tackifiers, and adhesion promoters. Agents, lubricants, softeners, colorants and the like may be added.

The insulating adhesive may be provided on the conductive line by applying a liquid adhesive by screen printing, gravure printing, roll coating, bar coating, spray coating or the like. If necessary, this adhesive may be dissolved with an ester-based, ketone-based, ether-ester-based, ether-based, alcohol-based, or hydrocarbon-based solvent as in the case of preparing the conductive paste. Although the thickness varies depending on the viscosity and pressure at the time of connection, it is generally 5 to 35 μm, preferably 10 to 20 μm, from the viewpoint of contact property and adhesive strength of the projection with the connection portion.

The connection structure of the film-like connector of the present invention is such that the above-mentioned film-like connector is placed on a substrate having electrodes to be connected, and this is hot-pressed to pass through the insulating adhesive layer by the projections formed on the conductive lines. It is only necessary to bring this protrusion into contact with the electrical part to be connected and electrically connect it, and this facilitates the electrical connection without the presence of conductive particles involved in anisotropic conductivity. The advantage is given that it can be done.

[0021]

EXAMPLES Next, examples of the present invention will be given. Example 1 On a polyethylene terephthalate film having a thickness of 25 μm, 65 parts by volume of silver powder having an average particle size of 3 μm as conductive particles was added to 100 parts by volume of a solid polyurethane adhesive composed of polyester polyol as an organic polymer binder. 320 by screen printing method using the conductive paste
After setting the parallel circuit pattern (conductive line) of this book at a pitch of 0.3 mm, 20 protrusions (height 12 μm, diameter) on the conductive line that becomes the connection part with the same type of thermosetting conductive paste.
40 μm conical shape) was formed, and then a polyester-based thermoplastic adhesive was applied to this with a knife coater to a thickness of 25 μm and dried to form a film-like connector.

Next, the film-shaped connector was placed on a printed circuit board made of a copper foil having a thickness of 45 μm and having the same pitch and plated with gold, and the surface of the printed circuit board was heated with a silicone rubber having a thickness of 1.0 mm. 140 ° C using a godet, 30kg / c
When heating and pressurizing to m ² for 10 seconds, the polyester thermoplastic adhesive melted and the protrusions contacted the connected electrodes on the printed circuit board to electrically connect them, and the circuit resistance averaged 22.3Ω. / Line, the standard deviation was 0.831Ω, which was very stable, and no damage such as cracks on the protrusions due to the flow of the adhesive was confirmed.

Example 2 A polyethylene terephthalate film having a thickness of 25 μm was coated with a thermosetting polyurethane adhesive having a viscosity of 30 poise, and polyamide insulating particles having a diameter of 30 to 35 μm were added thereto. 40 μm in thickness, and the solvent is volatilized by heating to be hardened. Then, the conductive line paste used in Example 1 is used to form a conductive line similar to that in Example 1 and a height on the conductive line. Is 14-23 μm
And a metal oxide vulcanizing adhesive composed of a mixture of the synthetic rubber having a carboxyl group in the side chain and the polyester adhesive on the protrusion.
A film-like connector was made by screen printing so as to have a thickness of 15 μm.

Then, the pitch used in Example 1 was 0.22 mm.
Insert this film-like connector between the printed circuit board and the transparent glass substrate with a surface resistance of 20Ω / □ at 150 ℃ and 40kg / c.
Heat and pressurize for 20 seconds under the condition of m ² and test the test piece at 70 ℃ for 2 seconds.
After aging for a period of time, it was placed in a temperature cycle test tank at -40 to 100 ° C and the change in resistance value in the environment was examined. As a result, the resistance change rate at high temperature after aging was 11% at maximum. It was stable.

[0025]

As described above, the present invention relates to a film-type connector connection structure, in which a plurality of conductive lines made of a conductive paste are provided on an insulating flexible polymer film, and further on that. In a film-like connector provided with an insulating adhesive layer for electrically connecting a connected electrode facing the conductive line, a projection integrated with the conductive line made of a conductive paste is provided on the surface of the conductive line. The conductive line and the electrode to be connected are electrically connected by the projection through an insulating adhesive. According to this, the projection is passed through the insulating adhesive melted at the time of heating and pressing. Since the electrode and the electrode to be connected are electrically connected, the presence of conductive particles involved in conventionally known anisotropic conductivity is unnecessary, the number of connection points is small, and the contact resistance is low. These electrical connections can be made, and the connection site is not easily moved by external stress such as heat, humidity, mechanical vibration, etc., so this connectivity can be maintained with high reliability, and therefore small This provides an advantage that connections between various electric circuit boards having a pattern pitch can be easily made.

[Brief description of drawings]

FIG. 1 is an enlarged vertical sectional view of a film-like connector used in the present invention.

FIG. 2 is an enlarged vertical cross-sectional view of another film-like connector used in the present invention.

[Explanation of Codes] 1 ... Film connector, 2 ... Insulating flexible polymer film, 3 ... Conductive line, 4 ... Projection, 5 ... Insulating adhesive layer, 6 ... Substrate, 7 ... Insulating particles,
8 ... Adhesive for fixing insulating particles.

Claims (1)

[Claims] 1. A connected electrode facing a conductive line, comprising a plurality of conductive lines made of a conductive paste provided on an insulating flexible polymer film, and an insulating adhesive layer provided on the conductive line. In the film-like connector for electrically connecting the conductive lines, a projection integrated with the conductive line made of a conductive paste is provided on the surface of the conductive line, and the conductive line and the connected electrode are electrically connected by the projection through the insulating adhesive layer. A structure for connecting a film-like connector, which is characterized by being connected to.