JPS60212979A - Method of obtaining conductive adhesion between electrodes - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of obtaining conductive adhesion between electrodes in electronic devices.

Conventionally, in electronic devices, the main constituent materials for circuit patterns have been insulating materials or PCBs, and the main wiring materials have been wires and harnesses. In addition, methods such as soldering, wire bonding, and wire bonding have been used to connect these devices.

However, in recent years, ceramics have been used as circuit construction materials.
With the adoption of new materials such as metal plates and FPC, and rapid progress toward smaller size, lighter weight, and higher density, it has become difficult to fully achieve these original purposes with conventional connection methods.

For example, when adhering electrode groups between printed circuit boards or attaching display panel electrodes to a printed circuit board, conventional soldering methods increase the pattern density of the electrode groups, or the gap between the display panel electrodes and the printed circuit board is too large. Because it is too narrow, for example, when soldering, a problem arises in that the solder is bridged to areas other than those where it is necessary.

Furthermore, when using a connector, the pattern density of the electrode group differs depending on the individual electronic components, so a dedicated connector with a unique electrode pitch is required.

The present invention connects the electrodes using an adhesive that has three functions of adhesiveness, conductivity, and insulation at the same time and has directionality in conductivity and insulation. This solves the above-mentioned problems.

That is, the present invention is made by uniformly mixing and dispersing conductive fine powder in a spherical shape or a similar shape in an insulating medium having adhesive properties, and exhibits conductivity in the direction of pressure when applied during adhesion. However, the present invention provides a method for obtaining conductive adhesion between the electrodes by pressurizing and adhering the electrodes using an adhesive that exhibits insulating properties in the direction of the plane perpendicular to the pressing direction. be.

The adhesive used in the present invention has the three functions of adhesiveness, conductivity, and insulation at the same time as described above, and also has directionality in conductivity and insulation, and exhibits conductivity. It is composed of conductive fine powder to provide adhesive properties and an insulating medium to provide adhesive and insulating properties.

The adhesive used in the present invention may be made by uniformly mixing and dispersing the conductive fine powder in the insulating medium, or may have electrical properties in an unpressurized state depending on the content of the conductive fine powder. The difference is that

In other words, if the content of conductive fine powder in the insulating medium is small, the adhesive exhibits insulating properties in the unpressurized state, but when applied between the electrodes and pressurized, the adhesive exhibits insulating properties perpendicular to the direction of application. However, the distance between the conductive fine powders in the pressurizing direction becomes closer, and the number of contacts between the conductive fine powders increases. Conductivity is developed.

Furthermore, if the content of conductive fine powder in the insulating medium is large, the adhesive exhibits conductivity in the unpressurized state, but when applied between electrodes and pressurized, the adhesive exhibits conductivity in the direction of pressure. Although the conductivity is maintained, the distance between the conductive fine powders in the direction of the plane perpendicular to the pressing direction increases, and the number of contacts between the conductive fine powders decreases, so that the distance between the conductive fine powders in the direction perpendicular to the pressing direction increases Insulating properties are developed in the direction of the intersecting planes.

The adhesive used in the present invention has the above-mentioned electrical properties, or if the content of conductive fine powder is small, that is, if the content is small, the adhesive has an adhesive property and an insulating medium has conductive properties. When the content is approximately 10% by weight or less based on the total weight of the fine powder, it exhibits insulating properties not only in an unpressurized state but also in a pressurized state (with respect to the pressurizing direction); In other words, when the content is approximately 90w/i1% or more, it exhibits conductivity not only in an unpressurized state but also in a pressurized state (with respect to the direction of the plane perpendicular to the pressurizing direction j). This is not preferable because it becomes impossible to exhibit conductivity and directional anisotropy of insulation, and adhesiveness also decreases.

The conductive fine powder used in the adhesive of the present invention includes gold,
Conventional conductive metals such as silver, copper, and nickel, conductive oxides such as conductive carbon, tin oxide, and indium oxide, and known conductive fine powders such as titanium carbide and titanium nitride can be used, but their shapes are A spherical shape or a shape similar to a spherical shape, that is, a spherical shape or a polyhedral shape is preferable, and convexities may be present. If the shape is not spherical or similar, ie, needle-like, plate-like, etc., the directional anisotropy of conductivity and insulation as described above cannot be obtained, and therefore it cannot be used in the present invention.

Adhesives of the present invention I The insulating media used include acrylic, epoxy, urethane, phenol, cyanoacrylate, plastisol, chloroprene, nitrile rubber, etc. adhesives that have adhesive and insulating properties. Although components commonly used as adhesives can be used, it is desirable that the adhesive has no fluidity during bonding, and therefore an insulating medium used in adhesives generally referred to as pressure-sensitive adhesives is preferred.

In the method of the present invention, electrodes are bonded under pressure using an adhesive obtained by uniformly mixing and dispersing the conductive fine powder as described above in the insulating medium. The agent must be able to exhibit the above-mentioned directional anisotropy of conductivity and insulation after pressure bonding, and must be approximately 1 (u
P/25- or more is preferable.

In addition, when bonding, apply the adhesive to one or both of the electrodes that are the adherend material to a uniform thickness using an applicator or other suitable method. After the volatile components are evaporated by heating (approximately 60° C.), pressure bonding is performed.

As explained above, when the method of the present invention is adopted for bonding between electrodes, it is possible to extremely easily and efficiently obtain conduction and insulation between electrodes in electronic devices that are becoming smaller, lighter, and more dense. .

The present invention will be explained below based on the implementation side.

The composition of the adhesive used is shown in Table 1 below (values are based on weight).

Table 1 Adhesive Composition (6) Diluent: Toluene/Acetone - 1/1 Ratio (Weight) Each composition of Samples A1 to 6 shown in Table 1 was placed in a 250 cc glass container using Glass Peas (Toshiba Made by Balo Teini, 08503M) Put it together with 120 ri,
The mixture was dispersed for 1 hour using an agitator mill (manufactured by Red Devil Co., Ltd.), and uniform dispersion of even the primary particles was confirmed using an optical microscope, and then each sample was prepared.

Example 1 FIG. 1 shows the ITO glass plate used in this example. In FIG. 1, 1 is a glass substrate, and 2 is an indium oxide thin film. This ITO glass plate has a=25si,
It was made as follows: b=4si%c=8m1d=1m.

The thickness of the indium oxide thin film 2 is 0.2 mm, and the resistance value is 1.
00n points vs. points/cllI. The thickness of the glass substrate was 1.5 mm.

10 mg from one end of the ITO glass plate shown in Figure 1 (second
The adhesive 3 of the sample A1
After drying at 60°C for 3 minutes to volatilize the solvent and leaving it for 20 minutes at room temperature, another identical ITO glass plate was coated on one end with the indium oxide thin film facing the other, as shown in Figure 2. A measurement sample was made by pasting together only 10 pieces.

The above measurement sample was pressurized with various pressures and forces using a press machine (manufactured by Koji Seisakusho, a simple test press machine), and was applied between the electrodes in the circuit direction (between points A and B in Figure 3) and between the circuits (between points A and B in Figure 3). The resistance value between points A and C in FIG. 3 was measured. Table 2 shows the results.
Shown below. For resistance measurement, a digital multimeter R-8840 manufactured by Takeda Riken Co., Ltd. is used for the measurement range 101 to 10@n, and a super insulation resistance/micro current meter TR-13601 manufactured by Takeda Riken Co., Ltd. is used for the measurement range 106 to l Qll fl. It was used.

Further, the resistance value 0 was similarly measured using each of the adhesives of Samples A2 to A6. The results are also shown in Table 2.

In A1 and Boil 4, the circuit resistance value showed a rapid increase at a pressing force of 10 [p/2.5d, and insulation properties were developed, resulting in anisotropic conductivity.

In addition, for A2 and Flat 5, the resistance in the circuit direction was in the order of 10 and was insulating until the pressure was 5Kp/2.5d, but it was 101! A rapid decrease in resistance value is observed from p/2.5aj, and conductivity is developed, resulting in anisotropic conductivity.

On the other hand, in Boiled 3 and Boiled 6 which used flaky conductive fine powder, the change in resistance value due to the change in pressing force was small and anisotropic conductivity was not expressed.

Example 2 Instead of the I'l'O glass plate used in Example 1, a copper circuit epoxy glass plate with the same configuration (copper circuit thickness 35mm, resistance value 0.01n points/cm) Example 1
A similar test was conducted and the results shown in Table 3 were obtained.

Table 3 Test results for printed circuit boards A2 and flat 5 have a pressing force of 1, similar to the ITO glass plate.
From 011$'/2.5cII, the resistance value in the circuit direction suddenly decreases and becomes conductive, becoming anisotropically conductive.

[Brief explanation of the drawing]

Figure 1 is a perspective view of an ITO glass substrate, and Figure 2 is an ITO glass substrate.
It is a side view showing a state in which TO glass substrates are bonded,
FIG. 3 is a perspective view showing the ITO glass substrate after pressure bonding. 1 is a glass substrate, 2 is an indium oxide thin film, and 3 is an adhesive. Patent applicant Shinto Paint Co., Ltd. Figure 2 Figure 3

Claims (1)

[Claims] 1. Conductive fine powder in a spherical or similar shape is uniformly mixed and dispersed in an adhesive insulating medium,
Pressure bonding between the electrodes using an adhesive that exhibits conductivity in the direction of pressure due to the pressure applied during bonding, but insulating properties in the direction perpendicular to the direction of pressure. A method for obtaining conductive adhesion between the electrodes, characterized in that: 2 The adhesive is made by uniformly mixing and dispersing spherical or similar conductive fine powder into an insulating medium that has adhesive properties. 2. A method for obtaining conduction and insulation between electrodes according to claim 1, wherein the adhesive exhibits electrical conductivity only in the direction of application of pressure. 3 An adhesive made by uniformly mixing and dispersing spherical or similar conductive fine powder in an insulating medium that has adhesive properties. 2. The method of obtaining electrical conduction and insulation between electrodes according to claim 1, wherein the adhesive exhibits insulation properties only in the direction of a plane perpendicular to the direction of application of the adhesive.