JPS6391908A - Pressure-sensitive anisotropic conducting film body - Google Patents

Abstract

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

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a pressure-sensitive anisotropically conductive film body, particularly a fine-pitch film body,
Alternatively, since connections can be made between small areas, it is possible to connect rigid and/or flexible electronic circuit boards or
Pressure-sensitive anisotropic conductive material that is useful for connecting CDs, LEDs, FDPs, flat pack ICs, leadless electronic components, and circuit boards, and is used to connect electrode terminals by sandwiching and pressure-welding them between opposing electrode terminals. It concerns the sexual membranous body.

(Prior art) As for the pressure-sensitive anisotropic conductive film, for example, one is known in which conductive particles are dispersed in an elastic body, and the diameter and density of the conductive particles are changed between the surface layer and the inside of the elastic body. (Unexamined Japanese Patent Publication No. 1973-
139989, Japanese Patent Application Laid-Open No. 111597/1983), and a method of connecting by a single conductive powder present in the support layer of the layer (U.S. Pat. No. 3,634,
807) is also known.

However, although the former type is pressure-sensitive, as shown in FIG. 5, the layer thickness of the elastic film layer 21 is larger than the diameter of the conductive particles 22, and a circuit occurs due to the contact of the conductive particles 22 when pressed. Formation occurs not only in the film thickness direction but also in the lateral direction (the dashed line in the figure indicates conduction; the same applies hereinafter), which has the disadvantage of being broad and having poor resolution. As shown, since this connection is made through one layer of particles 23, the contact surface generally has undulations, and because the particle diameter is not uniform, miscontacts are likely to occur. In this case, it is difficult to provide particles corresponding to the positions of the electrodes, so there is a disadvantage that the cost is poor.

(Structure of the Invention) The present invention relates to a pressure-sensitive anisotropically conductive film body that solves the above-mentioned disadvantages, and this invention relates to a conductive powder body having a particle size of 172 or more of the film thickness of the elastic polymer body. At the same time as stacking multiple layers of anisotropically conductive films arranged in a single layer in a polymer elastic body, the particle size of the conductive powder particles arranged in the anisotropically conductive film in the outer layer is It is characterized in that the particle size is 1/2 or less of the particle size of the conductive powder particles arranged in the anisotropic conductive film of the center layer.

In other words, the present inventors have developed various structures for pressure-sensitive anisotropically conductive films that exhibit anisotropic conductivity only in the film thickness direction when suppressed, are capable of connecting fine pitches, and are also capable of connecting irregular surfaces. As a result of the study, we found that this anisotropic conductive film was arranged in such a way that the conductive powder particles were arranged in a single layer within the polymer elastic layer, and that the conductive powder particles used here had a particle size of this high. If a plurality of layers are laminated with a layer thickness of 172 or more than the molecular elastic layer, when pressed, it will conduct in the vertical direction, but will not conduct in the horizontal direction. The particle size of the conductive powder arranged in the outer anisotropic conductive film is determined by the anisotropic conductive film in the center layer. If the particle size is 1/2 or less of the particle size of the conductive particles arranged in The present invention was completed by discovering that the connection can be made reliably.

Next, the pressure-sensitive anisotropically conductive film body of the present invention will be explained based on the accompanying drawings. FIG. 1 is a longitudinal cross-sectional view of a pressure-sensitive anisotropic conductive film of the present invention, and FIG. 2 is a longitudinal cross-section of a pressure-sensitive anisotropic conductive film of the same type as shown in FIG. 1 sandwiched between circuit boards. side view,
Figure 3 is a longitudinal cross-sectional view of the one in Figure 2 when pressed;
FIG. 4 shows a perspective view of the pressure-sensitive anisotropic conductive film body of the present invention in a different embodiment from that shown in FIG. 1.

The pressure-sensitive anisotropically conductive film body of the present invention shown in FIG.
3 are laminated, and this polymer elastic film 1.2.
Conductive powder particles 4.5.6 each having a particle size of 1/2 or more of the membrane thickness are arranged in a single layer at intervals in each of the elastic polymer membranes 1.2 and 3. . It is said to be 1/2 or less of the particle size. This polymeric elastomer membrane may be of any known type, such as chloroprene, EPDM, urethane,
It may be selected from synthetic rubber such as silicone rubber, thermoplastic elastomer such as thermoplastic SBH, etc., but since it has low load characteristics, the hardness is preferably 10 to 70° according to JIS A. is 10-5
0' is often used, and this also contains conductive powder, which will be described later, but during pressure welding, fine racks are generated in the elastic body, and the surface of the conductive powder becomes this surface. The JIS
Tear strength measured by K-6301 method is 30kg/■
Hereinafter, it is preferably 10 kg/an or less. Further, the conductive particles arranged in one polymeric elastic film may be of known type, and therefore, A
u.

The material may be selected from metals such as Ag, Cu, Ni, Si, W, or alloys thereof, conductive ceramics such as MoSi2, WC, TiC, carbon, etc., but these may be in the form of particles or fibers. It can be something from the body. This conductive powder is added to the elastic polymer membrane to make the elastic polymer membrane anisotropically conductive, but to prevent lateral conductivity from occurring during pressure contact. It is necessary that the particles be arranged in a single layer and have a particle size that is 1/2 or more of the thickness of the elastic polymer membrane. In addition, the particle size of this conductive powder is in the range of several to 0.5 mm depending on the thickness of the aerated polymer elastic film and the pitch of the electrodes to be connected (required resolution). If it is a fibrous material, this particle diameter refers to the fiber diameter, and the length should generally be less than inn to prevent short circuit between adjacent electrodes. However, since it is preferable to use particles of the same size in each layer, the particle size distribution is preferably narrow.

In FIG. 1, the conductive particles 4, 5.6 arranged in the polymer elastic membrane are made smaller in size from the center layer to the outer layer. Since the particle size of the conductive powder 6 is set to be 1/2 or less of the particle size of the conductive powder 4 arranged in the center layer 1, the pressure-sensitive anisotropic conductive film of the present invention It is said to have high reliability and maintain anisotropy, but since the conductive particles arranged in this outermost layer of polymeric elastic film are exposed to the atmosphere, plating treatment is required. It is preferable to use a chemically stable material made of carbon particles or fibers.

The pressure-sensitive anisotropic conductive film shown in FIG.
As shown in the figure, it is put into practical use by sandwiching the printed circuit board 7°8 between two flexible boards 9 and 1o, but when pressed from above as shown in Fig. The circuit board 7.8 comes into contact with the conductive powder 5 arranged in the anisotropic conductive film in the outer layer, and the conductive powder 5 contacts the conductive powder 4 in the center layer. Therefore, this circuit board 7.8 becomes conductive.

Note that FIG. 4 shows another embodiment of the pressure-sensitive anisotropically conductive film body of the present invention shown in FIG. However, this outermost part 3 is arranged in a constant manner in the longitudinal direction of the electrodes connecting the conductive fibers 11, and this is because the contact with the electrodes is made through the fiber strands. This has the effect of increasing the contact area and increasing the reliability of the connection.

Next, examples of the present invention will be given.

Example 1 Spherical nickel powder with a particle size of 90 to 125 μm and an average particle size of 100 tim and WC powder with a particle size of 25 to 35 μm and an average particle size of 30 μm were respectively mixed into room temperature curable silicone rubber. KE-45RTV CM Etsu Kagaku Kogyo [trade name] was arranged in a single layer with a volume ratio of 30% and 50%, and coated with a roll coater to a film thickness of 13077 m and 40
After curing the former film, the latter film was laminated on both sides of this film and cured to produce a pressure-sensitive anisotropically conductive film with a total thickness of 200 pm.

Next, this was sandwiched between a circuit board with electrodes 0.2 mm wide and 0.3 m long, and a load of 300 g/a+ was applied from above, and this showed an average conduction resistance of 0.16 Ω. The insulation resistance between adjacent electrodes, where the electrode amount ratio was 0.3 no, was 1013Ω or more.

Example 2 On both sides of the anisotropically conductive film body in which nickel powder with a film thickness of 130 μs obtained in Example 1 was arranged, a diameter of 10 and a length of 500 μs was formed.
Film thickness: 15 μm with carbon fibers arranged in a certain direction
A pressure-sensitive anisotropically conductive film body with a total thickness of 160 mm was prepared by laminating an anisotropically conductive film using a silicone adhesive and KEIOIRTV (trade name: Shinbin Chemical Industry Co., Ltd. FM12) published by the publisher.

Next, this was sandwiched between glass electrodes having the same pattern as a rigid circuit board having electrodes with a width of 0.6 mm and a length of 2 m at a pitch of 1.2 nn, and 500 g/c was applied from above.
When a load of d was applied, this product showed an average conduction resistance of 0.09Ω.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of the pressure-sensitive anisotropically conductive film body of the present invention, and FIG.
The figure is a vertical cross-sectional view of the thing held between the circuit boards, Figure 3 is a vertical cross-section of the thing in Figure 2 when it is suppressed, and Figure 4 is the vertical cross-section of the thing in Figure 1.
This is a perspective view of a pressure-sensitive anisotropic conductive film body of the present invention in a different embodiment from that shown in the figure, and FIGS. 5 and 6 are views of a known pressure-sensitive anisotropic conductive film body. It shows a longitudinal cross-sectional view. 1.2.3... Polymer elastic film 4.5.6... Conductive powder 7.8... Printed circuit board 9.10.
...Flexible substrate 11 ...... Conductive fiber 21 ...
......Elastic film layer 22.23... Conductive particle patent applicant Shin-Etsu Polymer Co., Ltd. Figure 1 Figure 2

Claims (1)

[Scope of Claims] 1. An anisotropic conductive film formed by arranging conductive powder particles having a particle size of 1/2 or more of the film thickness of an elastic polymer material in a single layer in an elastic polymer material. The particle size of the conductive powder arranged in the anisotropic conductive film in the outer layer is the same as that of the conductive powder dispersed in the anisotropic conductive film in the center layer. A pressure-sensitive anisotropic conductive film body characterized in that the particle size is 1/2 or less of the particle size of 2. The pressure-sensitive anisotropic conductive film according to claim 1, wherein the outermost polymeric elastic layer has a JIS hardness of 50 or less and a tear strength of 30 kg/cm or less. 3. The pressure-sensitive anisotropically conductive film body according to claim 1, wherein the conductive powder contained in the outermost polymer elastic film layer is made of ceramic or carbon.