JPH06231819A - Circuit connecting method - Google Patents

Abstract

PURPOSE:To prevent electrostatic destruction so as to perform uniform connection, by inserting the rubber cushion material, having volume resistivity smaller than that of a circuit substrate, between a heating die and a circuit, when circuits are connected to each other via a anisotropic conductive film. CONSTITUTION:An electrode 4 on a glass substrate 7 to which an anisotropic conductive film 6 is temporarily pressure-fitted, and an electrode 4 on a TAB circuit substrate 3, are arranged in an opposing condition to each other on a surface plate 9. Rubber-like cushion material 2 having volume resistivity smaller than that of the substrate 3 and heat conductivity larger than that of the substrate 3, is plated on the upper side of the substrate 3; and a heating die 1 is pushedly pressed thereto by a pressurizing means 10. Consequently, connection is performed without influence on the substrates 3 and 7 due to static electricity generated in the substrate 3 and the die 1. Because of the large heat conductivity of the cushion material 2, the temperature of the die 1 can be set at a low value and the deformation of the die 1 can be reduced. Consequently, the electrostatic destruction of an electronic member can be prevented to uniformly connect circuits to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of connecting circuit boards which are opposed to each other with an anisotropic conductive film.

[0002]

2. Description of the Related Art In recent years, an anisotropic conductive film has been placed between electrodes of an LCD and TAB or FPC as a connecting material for fine electrodes of a liquid crystal display module (hereinafter referred to as LCD) to connect a plurality of electrodes together. There are many ways to do it. In this case, as a method of collectively connecting, a heating die in which an electric heater is mounted in the die and a method of pressurizing while heating the connecting portion with infrared rays are generally used. Typical examples of these configurations are shown in FIGS. FIG. 2 is a method which is usually called direct pressing, and its structure is as follows: LCD panel, anisotropic conductive film, TAB on a surface plate.
Alternatively, it has a form in which a substrate such as an FPC is placed. By pressing this electrode part with a heating mold, etc., the LCD
The panel and electrodes such as TAB or FPC are connected to each other. FIG. 1 shows a structure in which a cushion material such as silicone rubber is further added to the structure of direct pressing.

[0003]

However, in the case of the direct pressing of FIG. 2 described above, the displacement between the TAB or FPC electrode circuit and the electrode of the LCD panel is small, but the electrode length is long or a large number of electrodes are provided. TAB or FPC
When trying to connect the electrode circuit to the LCD panel at one time, the thickness of the anisotropic conductive film cannot be made uniform after connecting because of the thickness variation of TAB, FPC and LCD panel, and stable connection reliability. Was not obtained. Further, in the case of FIG. 1, pressure is uniformly applied by inserting a cushion material such as silicone rubber on the TAB or FPC electrode substrate, so that the thickness of the anisotropic conductive film after connection can be made uniform. done. Cushion hardening of the cushion material is because the TAB or FPC electrode substrate is thin and highly flexible. Since the LCD panel is thick and hard, the cushion effect cannot be obtained.

However, silicone rubber generally has a large volume resistivity. Moreover, since most of the composition is a rubber component, the thermal conductivity is generally small. If such a material is inserted between them, static electricity will be generated when removing the cushion material after the connection with the anisotropic conductive film is completed,
There is a high probability that the elements of the LCD panel and the ICs of the TAB will be electrostatically destroyed. Moreover, since the thermal conductivity is low, the temperature of the heating die must be set higher than necessary to reach the target temperature. When the temperature of the heating die becomes high, the die is deformed by heat, and uniform heating and pressing cannot be performed. The present invention provides a method for connecting circuits that are homogeneous without causing electrostatic damage to electronic members due to static electricity when connecting circuit boards.

[0005]

Means for Solving the Problems That is, the present invention provides a circuit connecting method for connecting connecting terminals of circuit boards facing each other through an anisotropic conductive film by means of a thermocompression bonding machine. The present invention relates to a circuit connecting method, wherein thermocompression bonding is performed by placing a rubber cushion material having a resistivity lower than a volume resistivity of the circuit board and a thermal conductivity higher than that of the circuit board.

[0006]

According to the present invention, when the rubber-like cushion material 2 having a small volume resistivity is sandwiched between the heating mold 1 and the circuit board 3 as shown in FIG. The static electricity generated by the operation of the mold 1 can be connected without affecting the circuit board 3 and the glass substrate 7. At this time, since the cushioning material 2 has a high thermal conductivity, the temperature of the heating die can be set low, the deformation of the heating die is small, the cushion effect effectively acts on the entire circuit, and uniform pressure can be applied. . Hereinafter, a detailed description will be given using examples.

[0007]

EXAMPLE The present invention will be described below with reference to FIG. 1 by way of an example. FIG. 1 is a sectional view showing an embodiment of the present invention. As the circuit board 3, a 75 μm thick polyimide-based TAB having a copper circuit with a pitch of 0.20 mm and a thickness of 1.1 mm
With an ITO glass substrate with a surface resistance of 50Ω / sq,
Anisotropically conductive film (Anisolum _R AC manufactured by Hitachi Chemical Co., Ltd.)
-6073-22), a thermocompression bonding machine (AC-S300C manufactured by Hitachi Chemical Co., Ltd.) having a heating die of a constant heating system.
Now, a case where both circuits are connected will be described as an example. The heating and pressurization was performed from the TAB side. Anisotropic conductive film 6 in advance
Then, the electrode 4 on the glass substrate 7 which has been temporarily pressure-bonded and the electrode 4 of the TAB 3 are placed on the surface plate 9 in a state of being faced to each other. Then TAB
The cushion material 2 is inserted above 3. In this case, the cushion material 2 may have a size equal to or larger than the electrode 4,
The thickness is preferably the minimum thickness at which the cushion effect acts. Next, the heating mold is applied to the electrode 4 by applying a pressure of 10.
Lower from above and press. The heating and pressing conditions are standard conditions for the anisotropic conductive film, that is, 170 ° C.-20
−kgf / cm ² It took -20 seconds. As the anisotropic conductive film 6, a UV-curable or thermosetting adhesive, carbon, A
g, Ni or other metal particles dispersed therein, or conductive plastic particles in which a thin metal layer is provided on the surface of a polymer core, and the surface of the conductive plastic particles is covered with an insulating resin. Some of them are dispersed, and in this case, a so-called anisotropic conductive adhesive that exhibits insulation in the surface direction after connection is suitable. In addition, as the heating method, other methods such as a method in which a pulse current is applied to a coil incorporated in a pressure mold to heat the coil, an infrared heating method, or the like may be used. Table 1 shows the volume resistivity of the cushion material used and the failure rate of the TAB3 IC. As the cushion materials A, B and C, an antistatic type heat radiation sheet manufactured by Denki Kagaku Kogyo Co., Ltd. was used.

[0008]

[Table 1] * 1 Volume resistivity measurement method is based on JIS K6301. * 2 Physical properties of Teflon film (used as a cover film) * 3 Test TAB number n = 100 As shown in Table 1, the smaller the volume resistivity of the cushion material, the smaller the failure rate of IC. In particular, since the cushion material A has a small volume resistivity, the failure rate of the IC was 0%. Also, good results were obtained in the reliability test after connection.

[0009]

As described above, by inserting a rubber-like cushion material having a volume resistivity smaller than the volume resistivity of the circuit board between the heating die and the circuit, the generation of static electricity is reduced and It has become possible to connect homogeneous circuits without causing electrostatic breakdown of members.

[Brief description of drawings]

FIG. 1 is a configuration diagram according to the present invention in the case of circuit connection via an anisotropic conductive film.

FIG. 2 is a configuration diagram showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating die 2 Cushion material 3 Circuit board 4 Electrode 5 IC 6 Anisotropic conductive film 7 Glass substrate 8 Protective film 9 Surface plate 10 Pressing means

Claims (2)

[Claims] 1. A circuit connecting method for connecting connecting terminals of circuit boards facing each other through an anisotropic conductive film by a thermocompression bonding machine, wherein one circuit board has a volume resistivity of the circuit board. A method for connecting a circuit, characterized in that thermocompression bonding is performed with a structure in which a rubber-like cushion material having a thermal conductivity lower than that of the circuit board and a thermal conductivity higher than that of the circuit board is placed. 2. A circuit board facing each other is a TAB (Tape Autom).
ated Bonding), or FPC substrate and ITO (Indium
2. A circuit connecting method according to claim 1, wherein a rubber-like cushion material is placed on a TAB or FPC board, which is a combination of tin oxide (Oxide) electrode glass boards.