JPH0732052B2 - Film connector and manufacturing method thereof - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention makes it difficult to electrically connect, for example, a liquid crystal display panel and a drive module, or to solder an electric component having high-density terminal leads. The present invention relates to a film connector capable of connecting various parts and a manufacturing method thereof.

2. Description of the Related Art In recent years, high-density mounting of electric circuit parts has progressed, and finer patterns and smaller parts have been made.
Further, as a display device, a display device made of liquid crystal has been remarkably developed, and accordingly, various electric connection methods with peripheral modules have been studied.

Conventionally, there are some known methods for electrically connecting corresponding electrodes on a plurality of circuit boards, which will be described below.

First, as one method, corresponding electrodes are formed in the same shape and face each other, and the elastic connector is sandwiched and pressed to obtain an electrical connection.

A second method is a method in which a thermoplastic conductive ink and an insulating ink are alternately printed and formed in a stripe shape on an insulating film to connect them. Next, a third method is a method of obtaining an electrical connection by using an anisotropic conductive adhesive containing powder or fibrous conductive filler.

Problems to be Solved by the Invention In such a conventional method, in the case of the first method, uniform pressurization is always required, and it is difficult to perform alignment in the fine pitch electrode and displacement occurs due to distortion. It has the drawback of occurring. The second method involves many printing steps,
Since there is a limit to fine pattern printing, it has a drawback that it is difficult to manufacture a narrow pitch pattern. The third method has a drawback that a flexible printed circuit board must be used to pull out the leads.

In addition to this, there is a method of using a metal conductive powder such as a silver paste, but there is a problem in reliability due to a short circuit due to migration.

The present invention eliminates such problems, and an object of the present invention is to provide a film connector and a manufacturing method thereof, which can reliably perform electrical connection even between high density terminal leads and improve reliability. It is what

Means for Solving the Problems In order to solve this problem, the present invention provides a first metal having corrosion resistance and oxidation resistance, which is formed in a predetermined pattern on one main surface of an insulating film having flexibility. A film, a second metal film having good conductivity formed on the first metal film, a third metal film having corrosion resistance and oxidation resistance formed on the second metal film, and the third metal film A fourth isotropic conductive film formed on the metal film and having a semicircular cross section made of carbon powder and synthetic resin, and one of the insulating films so as to cover the fourth isotropic conductive film. A structure characterized in that a fifth anisotropic conductive film made of synthetic resin and carbon powder formed on the main surface and having less carbon powder than the fourth isotropic conductive material and having a larger particle size than the fourth isotropic conductive material are provided. Film connector. Further, a first metal film having corrosion resistance / oxidation resistance, a second metal film having good conductivity, and a third metal film having corrosion resistance / oxidation resistance on the entire main surface of the insulating film having flexibility. And the step of forming a fourth isotropic conductive film made of carbon powder and a synthetic resin in an arbitrary pattern such as a semicircular cross section by printing. Using the isotropic conductive film as a resist to remove the first, second and third metal films by etching.
A film connector comprising a step of forming a fifth anisotropic conductive film, which is made of carbon powder and synthetic resin and has a smaller carbon powder than the fourth conductivity and a larger particle size, on the entire surface of the pattern. The manufacturing method is as follows.

Here, a metal having corrosion resistance and oxidation resistance, such as nickel, shows good results in the first metal film, but platinum, rhodium, palladium, etc. are disadvantageous in terms of cost, but oxidation resistance is high. It is advantageous to use in this respect. As the first metal film, silver, aluminum, tin, or zinc can be used in addition to the above, and the above alloys may be used. The use of a copper-nickel alloy is preferable in terms of oxidation resistance like nickel. The result is obtained. Also,
The second metal film is made of copper for the purpose of improving conductivity.
Or the alloy is good. The third metal film has the same purpose as the first metal film and is used for protecting the second metal film. Further, the fourth isotropic conductive film can be used as an etching resist, and is formed as an auxiliary conductive film for the purpose of forming an arbitrary pattern and improving the connection accuracy as a connector. The fourth conductive film protects the underlying metal film as described above, and assures conductivity when a crack occurs in the metal film, it is necessary to use an isotropic conductive film. . In addition, the fifth anisotropic conductive film is required to be adhered to the adherend, have conductivity in the thickness direction, and have insulation properties in the lateral direction.
Therefore, the amount of carbon powder needs to be smaller than that of the fourth conductive film. Further, it is effective in the conduction in the thickness direction to make the particle size of the carbon powder larger than that of the carbon powder used for the fourth conductive film. This is because when the pressure is applied, if it is small with the flow of the synthetic resin, it will flow and will not contribute to conductivity.

Action With this configuration, the film connector of the present invention is roughly divided into a film having a pattern and an anisotropic conductive adhesive, and their function ensures electrical connection even between high-density terminal leads. Therefore, it is possible to obtain a film connector with improved reliability.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

First, FIG. 2 shows a cross section of a film in which three layers of a metal film to be a base of a pattern are formed. In FIG. 2, reference numeral 1 denotes an insulating film having flexibility, here 38
A polyethylene terephthalate (PET) film of μm was used, but in addition, polyether sulfone (PES),
Films such as polyimide (PI) can also be used. On one main surface of the insulating film 1, nickel is used as a first metal film (2) having corrosion resistance and oxidation resistance,
Copper is used as the second metal film 3 having electroconductivity, and nickel is used as the third metal film 4 also serving as an oxidation preventive material, each having a thickness of 350Å
The thickness of 2000 Å and 350 Å were sequentially formed by sputtering. These first, second and third metal films 2, 3 and 4 are formed by EB in addition to sputtering.
It can be formed by means such as (electron beam irradiation) and plating. Then, a phenol resin (100 parts by weight) as a thermosetting resin was used as a base on the third metal film 4, and carbon powder [[carbon black (acetylene black) 60 parts by weight, average particle size as an electrically conductive filler was used. 0.05
μm and graphite 40 parts by weight [Nippon Graphite Co., Ltd., CSP40
Parts by weight, average particle size of 5 μm]]] was used for silk screen printing on an arbitrary pattern (manufactured by Three Bond Co., Ltd.), and heat-cured at 130 ° C. for 30 minutes. The cross section is shown in FIG. 3, and 5 is the fourth made of conductive paste.
Is an isotropic conductive film. The film thickness of this isotropic conductive film 5 is
It is about 10 μm, and its cross section forms a semicircular semi-cylindrical shape as shown in the figure. Next, using the isotropic conductive film 5 as a resist, the underlying metal films 2, 3 and 4 were etched to obtain a pattern as shown in FIG. On the other hand, as shown in FIG. 5, a polyester [Vylon GK-130 manufactured by Toyobo Co., Ltd.] is used as the thermoplastic resin 6, and an anisotropic conductive adhesive 8 [containing carbon powder 7 as a conductive filler 8 [ Three-bond Co., Ltd.] was adhered to the release paper 9 to prepare. Here, as the carbon powder 7,
100 parts by weight of a phenol resin [Matsushita Electric Works, Ltd., J-1000] and 100 parts by weight of acetylene black [produced by Denki Kagaku Co., Ltd.] were baked and solidified, and 5 parts by weight of a pulverized product (average particle size 20 μm) was used. . Then, as shown in FIG. 1, the anisotropic conductive adhesive 8 was laminated on the surface of the pattern with a laminator at a roll temperature of 80 ° C. and a film speed of 2 m / min to a thickness of 30 μm to prepare a film connector 10. First
In the figure, 8a is a fifth anisotropic conductive film made of the above anisotropic conductive adhesive 8 formed by this lamination.

As a connection test of this film connector, the width of each wire is 325 μm, the distance between the wires is 325 μm, and a total of 650 μm pitch, 200 lines are arranged at equal intervals.
And a glass plate on which a 1.1 mm thick transparent conductive film (ITO) with a surface resistance of 10 Ω / □ was vapor-deposited and etched at the same pitch as above, and on a film connector on which a pattern was formed at the same pitch. After applying tackiness to the part to be fixed in advance with a thermocompression bonding machine at 110 ° C, 30 kg / cm ² , 0.5 sec, remove the release paper, and then remove the release paper from the electrode on the glass epoxy substrate and one end of the film connector. After aligning the position with the electrode, lightly pressing it with your finger and temporarily fixing it,
Main compression bonding was performed at 30 ° C, 30 kg / cm ² , and 30 seconds. This state is shown in FIG. 6, where 11 is a glass epoxy substrate and 12 is a metal electrode. Next, tackiness was similarly imparted to the electrode on the other end of the film connector, and the electrode was temporarily fixed to the ITO glass plate, and then similarly pressure-bonded at 160 ° C., 30 kg / cm ² and 45 seconds. This state is the 7th
As shown in the figure, 13 is a glass plate and 14 is an ITO electrode.

Further, FIG. 8 shows a state in which the metal electrode 16 on the polyimide film 15 and the film connector 10 are connected.

It was confirmed that the connection resistance did not change under various environments when the film connector 10 and the object to be connected shown in FIGS.

Effects of the Invention The film connector of the present invention is configured as described above, and can be roughly classified into a film having a pattern formed thereon and an anisotropic conductive adhesive. In the conventional flexible printed circuit board, the surface of the copper foil pattern is flat, and when the anisotropic conductive adhesive is sandwiched and heat-pressed, the resin does not flow sufficiently,
Although there is a drawback that an insulating film is formed to cause a poor connection, in the pattern of the film connector of the present invention, the conductive paste forming the fourth isotropic conductive film at the top is anisotropic during thermocompression bonding. The conductive conductive adhesive is pushed away to connect with the counter electrode and the surface of the paste itself is porous,
The fine protrusions are crushed to form a surface connection. Further, the carbon filler in the anisotropic conductive adhesive is sandwiched between the paste and the electrode of the object to be connected, so that the carbon filler bites slightly into the paste side. As a result, the initial connection is sufficiently maintained.
Then, in connection with the object to be connected, as shown in FIGS. 6 to 8, the resin of the anisotropic conductive adhesive flows between the adjacent electrodes to fill the gap and firmly fix the film distorted by pressure. To do. Therefore, even in the environmental test period, the pulling force of the adhesive and the restoring force of the film constantly press between the connected electrodes to stabilize the contact resistance.

Further, the anisotropic conductive adhesive formed on the pattern has both the effect of protecting the pattern and the effect of insulating the surface. For example,
It has the effect of relieving the strong bending of the pattern, and even if the metal film rusts and partially floats or cracks occur in the conductive paste, the coated anisotropic conductive adhesive layer does not affect the pattern body or insulation. It has the effect of pressing against the film strongly and preventing pattern breakage. Further, it also has an effect of protecting the metal pattern from moisture, which greatly contributes to reliability.

As described above, the film connector of the present invention has various characteristics, and can be used for electrical connection between a liquid crystal display panel and a drive module whose demand is rapidly increasing, and electric parts having high-density terminal leads with high reliability. They can be connected, and their industrial potential is great.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the film connector according to the present invention, and FIG. 2 is a view for explaining a method of manufacturing the film connector according to the present invention, in which first, second, and third metal films are formed on an insulating film. Sectional view showing the formed state, FIG. 3 is a sectional view showing a state in which a conductive paste is printed on the metal film in FIG. 2, and FIG. 4 is a state in which the pattern shown in FIG. 3 is also etched. 5 is a sectional view showing an anisotropic conductive adhesive coated on a release paper, and FIGS. 6 to 8 are sectional views after pressure bonding of a film connector according to the present invention and an object to be connected. It is sectional drawing which shows each connection state. 1 ... Insulating film, 2 ... First metal film, 3 ... Second metal film, 4 ... Third metal film, 5 ... Fourth isotropic conductive film, 6 ... Synthesis Resin, 7 ... Carbon powder, 8 ... Anisotropic conductive adhesive, 8a ... Fifth anisotropic conductive film, 10 ... Film connector.

Claims (2)

[Claims] 1. A first metal film having corrosion resistance and oxidation resistance, which is formed in a predetermined pattern on one main surface of an insulating film having flexibility, and good conductivity formed on the first metal film. And a third metal film having corrosion resistance and oxidation resistance formed on the second metal film and carbon powder and synthetic resin formed on the third metal film. A fourth isotropic conductive film having a semicircular cross section, and
No. 5, which is formed on one main surface of the insulating film so as to cover the isotropic conductive film and has a smaller carbon powder and a larger particle size than the fourth isotropic conductive film, and which is made of a synthetic resin. And an anisotropic conductive film. 2. An insulating film having flexibility is provided with a first metal film having corrosion resistance / oxidation resistance, a second metal film having good conductivity, and corrosion resistance / oxidation resistance on the entire main surface of the insulating film. A step of sequentially forming a third metal film that has, a step of printing a fourth isotropic conductive film made of carbon powder and a synthetic resin in an arbitrary pattern such as a semicircular cross section, A step of etching away the first, second, and third metal films using the fourth isotropic conductive film as a resist;
A film connector comprising a step of forming a fourth anisotropic conductive film, which is made of carbon powder and synthetic resin and has a smaller carbon powder and a larger particle size than the fourth conductivity, on the entire surface of the pattern. Manufacturing method.