JPS628407A - Manufacture of anisotropic conducting sheet-like product - 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 [Field of Industrial Application] The present invention relates to a method for manufacturing an anisotropically conductive sheet-like article that is conductive in the thickness direction of the sheet and insulating in the horizontal direction of the sheet.

[Conventional technology]

2. Description of the Related Art Soldering wires has been used for a long time to conductively connect the circuit pattern of one electronic component to the circuit pattern of another electronic component. Soldering can be said to be an excellent connection method in that it is relatively easy to make highly reliable conductive connections, but it is not necessarily suitable for conductive connections of circuit patterns that have become more complex and smaller than those used in recent electronic components. It is difficult to say that it is a perfect method. For example, electronic components such as liquid crystal display devices have a 1fi thin circuit pattern and an extremely large number of connection terminals.Additionally, there are problems with heat resistance, so conductive connections cannot be made by soldering. There is.

As a connection method to solve the above problems, conductive connections between block circuit patterns are made using an anisotropic conductive sheet or molded body that is conductive in the thickness direction of the sheet and insulating in the horizontal direction of the sheet. There are several known ways to do this. For example, (1) an anisotropic conductive sheet in which conductive linear objects are oriented and dispersed in an insulating resin sheet so as to be substantially parallel to the thickness direction of the sheet (e.g., 65
892, 53-53796, 54-57697, and Japanese Utility Model Application No. 54-63200).

(2) An anisotropically conductive molded body (for example, Japanese Patent Laid-Open No. 50-2080
．． Publications such as 50-94495 and 5l-87787Q).

This method uses methods such as

[Problem that the invention seeks to solve]

The conventionally known anisotropically conductive sheets or molded bodies exemplified in (1) and (2) above are advantageously used for conductive connections between block circuit patterns that are complicated, miniaturized, and have a large number of connection terminals. However, the production of these sheets or molded bodies requires special equipment or many processes, which poses a problem in that economical production is difficult.

That is, the anisotropic conductive sheet of type (1) requires the conductive linear objects to be oriented and dispersed in the insulating sheet, and therefore requires special manufacturing equipment. Also,
The anisotropically conductive molded body of type (2) is produced by preparing an insulating rubber sheet and a conductive rubber sheet separately, laminating these sheets into one, vulcanizing the obtained laminate, and then slicing it. It requires many complicated processes.

The present invention was developed in consideration of the above points, and is an anisotropically conductive sheet material that exhibits good conductivity in the thickness direction of the sheet and reliable insulation in the horizontal direction of the sheet. The purpose is to provide a manufacturing method that can economically produce 1 q without requiring special equipment or processes.

(Means for Solving the Problem) In order to achieve the above object, the method for producing an anisotropically conductive sheet according to the present invention is to screen print a liquid mixture containing a non-conductive polymer substance and conductive particles. The electroconductive particles contained in the liquid mixture are characterized in that their particle diameter is equal to or greater than the thickness of the sheet to be printed.

[For production]

According to the present invention, an anisotropically conductive sheet material can be manufactured by an extremely simple method of simply screen printing a liquid mixture containing a non-conductive polymer substance and conductive particles, and with a small number of steps. The anisotropically conductive sheet material obtained by the present invention is obtained by dispersing conductive particles having a particle diameter equal to or larger than the thickness of the sheet in a sheet of a non-conductive polymer material. , so that when the sheet-like material is used as a conductive connection component for a circuit pattern, the conductive particles are properly sandwiched between the connection terminals of the circuit pattern, thereby ensuring good stability in the thickness direction of the sheet. A good conductive connection is ensured. On the other hand, the conductive particles in the sheet are dispersed in a regular array at positions corresponding to the mesh of the screen by screen printing during sheet formation.
Contact between the conductive particles can be prevented, thereby ensuring reliable insulation in the horizontal direction of the sheet, and highly reliable anisotropic conductive connection can be achieved.

〔Example〕

Non-conductive polymeric substances that can be used in the present invention include various known polymeric materials, such as polyvinyl chloride, polyacrylate, polyolefin, polyamide, polystyrene, polyvinyl acetate, and polyester. , thermoplastic resins such as polycarbonate, thermosetting resins such as unsaturated polyester, polyurethane, phenolic resin, epoxy resin, silicone resin, fluororesin, and silicone rubber, fluororubber, acrylic rubber,
Covered with various synthetic rubbers such as chloroprene rubber and butadiene rubber, or natural rubber. Among these polymeric materials, various synthetic rubbers or natural rubbers can be preferably used because they yield anisotropically conductive sheets with excellent flexibility and pliability, and polyesters, polyamides, polyethylene, polyacetic acid It is particularly preferable to use a polymeric material having hot-melt adhesive properties such as vinyl, since this enables electrical connection between circuit patterns as well as mechanical bonding at the same time.

When the above-mentioned polymeric material is liquid, it can be directly mixed with conductive particles to form a liquid mixture for screen printing, but when it is solid or highly viscous,
It can be used after being dissolved, dispersed, diluted, etc. with an appropriate solvent.

In addition, the above-mentioned polymeric material may contain various known fillers, pigments, dyes, extenders, plasticizers, curing agents, flame retardants, dispersants, thickeners, stabilizers, reinforcing materials, etc., as necessary. Additives can also be added.

Conductive particles that can be used in the present invention include (a) AQ, Cu, Ni, Fe, AI, AU, pb, 3
conductive metal particles such as n or alloys thereof; (b) A on the surface of particles of various thermoplastic resins, thermosetting resins, synthetic or natural rubbers, or glass;
(C) A binder such as various thermoplastic resins, thermosetting resins, synthetic or natural rubber, etc. and conductive fine powder (e.g. AQ
conductive particles formed from a mixture with powders of SFe, Cu, AI, Ni, ALJ, or alloys thereof, and carbon black, graphite powders, etc.).

In the present invention, it is important that the particle diameter of the conductive particles is equal to or greater than the thickness of the sheet of non-conductive polymer material formed by screen printing. The size of the circuit pattern pitch,
Alternatively, the distance is determined by considering dielectric strength voltage, etc., but it is preferably 1 to 5 times the thickness of the sheet, and 1.
2 to 2 times is particularly preferred. By using conductive particles with a relatively large particle size in this manner, the particles are exposed and dispersed on both sides of the sheet, and the exposed portions of the particles properly contact the surfaces of the connection terminals of the circuit pattern. This ensures good conductive connection in the thickness direction.

Note that the particle shape of the conductive particles does not necessarily have to be spherical, and may be a Nobuko regular shape.

Among the conductive particles exemplified above, (b) and (C
) type conductive particles (excluding conductive particles with a metal coating layer formed on the surface of the glass particles) are easier to deform under pressure than type (a), and form circuit patterns. It can be preferably used because it maintains good contact with the connecting terminal.

Among them, in particular, conductive particles of the type (b) in which a metal layer is coated on the surface of synthetic rubber or natural rubber particles;
Alternatively, conductive particles of type (C) formed from a mixture of synthetic rubber or natural rubber binder and conductive fine powder can be flexibly deformed and can provide better contact with the connection terminals of the circuit pattern. This is preferable because it allows

In the present invention, the anisotropically conductive sheet material is formed by forming a liquid mixture consisting of the above-mentioned non-conductive polymeric substance and conductive particles, and if necessary, adding a solvent or other additives. screen printed and cured using an appropriate method (e.g., air drying, heat drying,
9M curing, active energy ray curing, etc.).

Although there are no particular limitations on the screen printing method that can be used in the present invention, in order to obtain a sheet-like material with preferable anisotropic conductive properties, it is necessary to increase the mesh size of the screen printing plate used for the screen printing. It is preferable that the diameter of the conductive particles is equal to or larger than the particle diameter of the conductive particles in the liquid mixture. If the size of the mesh is smaller than the particle diameter of the conductive particles,
As a matter of course, the conductive particles do not pass through the mesh of the screen printing plate, resulting in a sheet-like material in which no conductive particles are present, rendering it useless as a conductive connection.

In the present invention, it is particularly preferable that the mesh size of the screen printing plate is equal to or larger than the particle diameter of the conductive particles, and less than twice as large, and by using such a screen printing plate, The formed sheet-like material is in a dispersed state in which conductive particles are present one at a time in a position corresponding to the mesh of the screen, and the distance between the conductive particles is at least the thickness of the thread that forms the screen. This ensures the horizontal insulation of the sheet material.

In the anisotropically conductive sheet material of the present invention, the conductive particles are not necessarily dispersed so that one particle is always present at a position corresponding to every mesh of the screen printing plate; may exist in Generally, the amount of conductive particles used to obtain good conductivity in the thickness direction of the sheet and reliable insulation in the horizontal direction of the sheet is 1 to 30% by volume in the conductive sheet. It is preferable that the amount is 5% to 15% by volume, and most preferably 5% to 15% by volume. If the content is less than 1% by volume, when used as an anisotropically conductive connection component, there is a risk that no conductive particles will exist between the connection terminals of opposing circuit patterns, and no conduction will occur.

Further, in the above screen printing, the viscosity of the liquid mixture containing the non-conductive polymer substance and conductive particles is 3.
It is preferable to set it as the range of 00-500 poise (25 degreeC). When the viscosity is lower than 300 poise, the fluidity of the liquid mixture increases, and the coating film after screen printing tends to flow.
The arrangement of the conductive particles may be disrupted and the horizontal insulation properties of the sheet may not be maintained.On the other hand, if the viscosity is higher than 500 voices, the mesh of the screen printing plate may appear on the surface of the resulting anisotropic conductive sheet. Problems may occur, such as residual particles, making it impossible to obtain a smooth sheet and reducing sheet strength.

The anisotropically conductive sheet material of the present invention obtained as described above can be formed into any shape suitable for the shape of the conductive connection portion, such as a ribbon shape, a tape shape, a donut shape, a disk shape, a polygonal shape, an irregular shape, etc. It can be cut or punched into shapes and used as anisotropically conductive connecting parts. Alternatively, if screen printing is performed using a screen printing plate that can be printed into any desired shape, the desired shape can be directly manufactured without requiring post-processing such as cutting or punching.

Hereinafter, the present invention will be roughly described in detail based on specific examples.

Example 1 Silicone resin solution (manufactured by Toshiba Silicone Co., Ltd., TSR-11
7> Mix and disperse solder powder with a particle size of approximately 100 μm in an amount that is 10% by volume based on the silicone resin to form a liquid mixture (viscosity at 25°C measured with a B-type viscometer, approximately 4°C). Poise) was adjusted.

The liquid mixture obtained above was dried and cured onto a support film (polyester film) surface-treated with a silicone mold release agent using a screen printing plate with a 150 mesh (opening 124 μm) woven with 45 μmφ nylon thread. The subsequent sheet thickness (thickness of the part excluding conductive particles) is 80 μm
An anisotropically conductive sheet was prepared by screen printing and drying and curing for 30 minutes at 150''C.

The dispersion state of the conductive particles in the obtained anisotropically conductive sheet material was uniform, and the sheet material was
When cut into a size of 0 and used for conductive connection of a circuit pattern, the resistance value in the thickness direction of the sheet (between opposing terminals) was 1.
It showed excellent conductivity of ~2Ω, the insulation between horizontally adjacent connection terminals (between adjacent terminals) was extremely high (resistance value of 1000MΩ or more), and it showed excellent anisotropic conductivity. .

Example 2 Electroless N was applied to the surface of nylon beads with a particle size of 100 μm.
Metal layer-coated conductive particles were prepared by performing i-plating and then electroless AQ plating (Ni plating layer thickness: approximately 0.1 μm, AQ plating layer thickness: 0.1 μm).
.

An anisotropically conductive sheet material was prepared in the same manner as in Example 1, except that the N1-AQ coated nylon beads described above were used in place of the solder powder in Example 1, and conductive connections of circuit patterns were made. The conductivity between opposing terminals was 2Ω, and the insulation between adjacent terminals was 1000MΩ or more, indicating excellent anisotropic conductivity.

Example 3 85 parts by weight of ABS resin and 15 parts by weight of conductive carbon powder were melt-kneaded and then pulverized to produce conductive particles with a particle size of about 100 μm.

An anisotropically conductive sheet material was prepared in the same manner as in Example 1, except that the above carbon-ABS conductive particles were used in place of the solder powder in Example 1, and conductive connections of circuit patterns were made. The conductivity between opposing terminals was 100Ω, and the insulation between adjacent terminals was 1000MΩ or more, indicating excellent anisotropic conductivity.

Example 4 Silicone rubber (manufactured by Toshiba Silicon Co., Ltd., TSE221-34
) A mixture of 60 weight ω parts and 40 weight parts of A (7 powder) with a particle size of 5 μm was pressurized at 170°C for 10 minutes, and then molded at 200°C.
The sheet-like conductive rubber obtained by vulcanization for 4 hours was crushed and sieved to produce conductive particles having a particle diameter of about 100 μm.

The conductive particles obtained above were used in place of the solder powder of Example 1, and an anisotropically conductive sheet material was produced in the same manner.

The obtained anisotropic conductive sheet has excellent flexibility, and the conductive particles are also flexible and easily deformable, so they are sandwiched between the terminals of a circuit pattern and conductive connections are made under pressure. When this was carried out, the conductive particles were deformed and formed good contact with the terminal surface of the circuit pattern, exhibiting extremely excellent conductivity of 1 to 2 Ω.

〔Effect of the invention〕

The method for manufacturing an anisotropically conductive sheet of the present invention requires only screen printing of a liquid mixture containing conductive particles having a particle size equal to or larger than the thickness of the sheet to be formed, and a special Since there is no need to use any method or device, it has the advantage that it can be provided easily. In addition, the anisotropically conductive sheet material obtained by the present invention can ensure reliable conductivity in the thickness direction of the sheet and reliable insulation in the horizontal direction of the sheet, so it can be used in various electronic components. It can be advantageously used as a conductive connecting part.

Claims (3)

[Claims] (1) A liquid mixture containing a non-conductive polymer substance and conductive particles is printed into a sheet by screen printing, and the conductive particles contained in the liquid mixture have a particle size of A method for producing an anisotropically conductive sheet material, characterized in that the thickness is equal to or greater than the thickness of the sheet to be printed. (2) The manufacturing method according to claim 1, wherein the conductive particles are pressure-deformable resin particles whose surfaces are coated with a metal layer. (3) The manufacturing method according to claim 1, wherein the conductive particles are formed of a mixture of a pressure-deformable resin and a conductive substance.