JPS62188184A - Adhesive compound with anisotropic conductivity and adhesivefilm for circuit connection and connection of circuits usingthose materials - 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 an adhesive composition used for connecting circuits, an adhesive film made of this composition, and a method for connecting circuits using this material.

(Prior art and problems) Conventionally, connection terminals have been used at fine pitches, such as connection of integrated circuits to wiring boards, connection of display terminals to wiring boards, connection of electrical circuits to IJ-boards, etc. As a connection method when they are lined up in a row, methods using connecting members such as soldering and conductive adhesive are widely used. However, in these methods, it is necessary to form the connecting member only in the conductive circuit part, so the density is high.

Connecting microcircuits, which are becoming increasingly high-definition, has been difficult.

Recently, connection members for circuit connections have been studied, and have already been published in Japanese Patent Laid-Open No. 51-20941 and Japanese Patent Laid-open No. 51-21.
Publication No. 192 1% Publication No. 55-104'007 No. 1, etc., have been proposed, but the basic idea of all of these is anisotropic conductivity that includes conductive materials such as metal particles between opposing circuits. By providing a connecting member layer and providing pressure or heating/pressing means, electrical protection between one circuit and insulation between adjacent circuits is provided, and opposing circuits are bonded and fixed. This method uses anisotropic conductive connection material pressure.

However, in these methods, conduction between circuits is mainly obtained by contact between multiple conductive materials, often metal particles, and because metal particles are rigid, there is no connection between particles or between particles. The contact area between the circuits or the reliability of the conduction is insufficient, rather than the amount of light.

Although it is the same as the above-mentioned conduction concept, for the purpose of improving initial connection reliability or reducing cost, particles are used in which a conductive particle or an insulating particle is used as a core material and a conductive layer is formed on the surface of the core material.

Attempts to obtain anisotropic conductive connections were also made, for example, in JP-A-51.
As seen in JP-A-155958, JP-A-56-122193, JP-A-58-111202, etc., when metal particles, alumina, glass, etc. are used as the core material, the core material is rigid as described above. Therefore, the reliability of conduction is unsatisfactory because the contact area between particles or between particles and circuits is not the same as that of light, and there is knowledge that plastic is used as a core material. (1) The requirements of the invention were not clear, and even after additional testing by the inventor, it was not possible to obtain a circuit connection body with good long-term reliability.

That is, although it is possible to obtain anisotropic conductivity during circuit connection in the above-mentioned prior art, practical characteristics such as reliability of the connection portion are not considered.

As will be described later, the results of follow-up tests of these conventional techniques are shown in Comparative Examples 1 and 2 in Table 1, or if satisfactory characteristics could not be obtained.

Furthermore, with the aim of improving connection reliability, for example, as seen in JP-A-60-140790, good connections are achieved by melting gold g4E1 elements dispersed in an insulating adhesive between circuits. However, since the metal particles are heat-fusible, this method has the drawback that the reliability during connection is unsatisfactory due to the short distance between the connecting strips and the connection. In other words, a good connection can be obtained near the melting point of the metal, but above the melting point, the metal particles melt and easily flow and deform, similar to conventional soldering. It has the disadvantage of not being able to adapt to fine circuit pitches (called leakage), and because the metal does not melt below its melting point, rigid metal particles only exist between the circuits as described above. Even if it is possible to obtain initial conductivity, long-term connection reliability, particularly in, for example, a thermal shock test, is unsatisfactory. In addition, it is difficult to control the melting state near the melting point due to thermal conductivity, and even if a good circuit connection is obtained, there is a large difference in thermal expansion between the adhesive and the metal particles. It had the drawback of low thermal shock resistance as described above. In addition, these hot bath meltable metals have extremely high surface tension for transparent conductive glass electrodes, etc., which are often used in display applications such as liquid crystals, so they do not wet the circuit surface, making it difficult to obtain a good connection. I couldn't do it.

The present inventors have previously proposed an extremely good conductive adhesive sheet and connection member for circuit connection.

The present invention was achieved as a result of extensive research into means and methods that further improve the above-mentioned drawbacks and enable highly reliable connections during and after connection.

(Means for Solving the Problems) That is, the present invention provides an adhesive composition for circuit connection comprising an insulating adhesive component and conductive particles, in which almost all of the polymer core material is used as the conductive particles. Conductive particles having an average particle size α5 to 300 μm and a particle size ratio α05 to 1.0 in the form of one particle, whose surfaces are compounded by a conductive metal thin layer, are added to the adhesive component in a solid common ratio [11 to 300 μm]. An adhesive for circuit connection that contains 15% by volume and is crosslinked and cured such that the ratio of the thermal expansion coefficient of the polymer core material to the adhesive is [15 to 15] and the ratio of the elastic modulus is 1.2 to cL01. A composition, an adhesive film for circuit connection having a thickness of 1 to 600 μm and a total light transmittance of 40% or more as one form of use of this composition, and long-term connection reliability using this composition and film. Concerning excellent circuit connection methods.

The structure of the composition and film according to the present invention will be explained in detail below with reference to the drawings.

Figures 1 and 2 are schematic cross-sectional views showing the conductive particles used in the present invention, and Figures 1 and 2 are diagrams showing how the surface 1ili of the polymer core material 1 is coated with the metal 2. This is a schematic diagram in the case where the polymer core material 1 has a hollow part 3 in the second factor.

The polymer core material 1 of the present invention has the structure shown in FIG. 1 or 2, used alone or in combination.

Here, the core material can have various configurations, such as a completely filled body, a hollow body whose interior is made of gas, or a foam body having air bubbles inside.

The shape of the polymeric core material 1 is typically spherical, but it may also have protrusions or irregularities on its surface, and can also be used as agglomerated particles in which core material particles are aggregated.

The polymer core material may be plastics, rubbers, or natural polymers, and may be a composite mixture or copolymer of these materials, with these as the main component, and crosslinking agents, curing agents, and other additives as necessary. using an agent. Examples of these polymers include polyethylene and polypropylene.

polystyrene, acrylonitrile-styrene copolymer,
Acrylonitrile-butadiene-styrene copolymer, polycarbonate, various acrylates such as polymethyl methacrylate, polyvinyl plaal, holvinyl formal, polyimide, poly1mide, polyester, polyvinyl chloride, polyvinylidene chloride, fluorine a+ fat.

Polyphenylene oxide, polyphenylene nalphide, polymethylpentene, urea resin.

Examples include melamine resin, benzoguanamine resin, phenol resin, formalin resin, xylene resin, furan resin, diallyl ditalate resin, epoxy resin, polyisocyanate resin, phenoxy resin, and silicone resin, and these may be modified as appropriate.

In the case of thermosetting materials, the degree of curing is not critical as long as it does not interfere with mixing with adhesive components.

Whether a single strain or a combination of two or more of these strains can be used is determined by taking into account the following points.

(It must be possible to soften or deform at a pressure of 10 kg/- or less at the temperature during recircuit connection, that is, between room temperature and 400°C.

(2) The coefficient of thermal expansion near normal temperature is 2"OX 10-'
〜2

(3) The elastic modulus is approximately equal to or higher than the value of the adhesive component.

(4) Good adhesion to the metal coating layer.

The reason why it can be softened or deformed by applying pressure and heating during connection is that it is necessary to increase the contact area between conductive particles or between conductive particles and the circuit when one circuit is connected. It is also possible to use a pressure-sensitive connection using a so-called pressure-sensitive adhesive and a heat-sensitive connection using heating up to 400°C. If the temperature exceeds 400° C., there is a risk of thermal damage to the circuit board, so the method of the present invention cannot be applied. Further, in the case of pasting at room temperature, heat resistance may be a problem in mounting the circuit, so it is more preferable that the polymer core material is softened or deformable at 100 to 250°C.

The pressure should be adjusted so as not to adversely affect the circuit parts that need to be connected.
Low pressure is desirable if possible, and usually 100 kg/aIP or less is often used for this type of circuit connection.

This can also be applied mutatis mutandis to the present invention.

It is necessary to specify the coefficient of thermal expansion of the polymer core material from the viewpoint of adhesion to the coating metal during thermal changes.

Above the upper limit of 20 x 10-'('/'C)! I
Because the amount of tension and contraction in P1 is too large, metal covering 61/@l
This is undesirable as it tends to cause cracking and peeling.

The reason why the modulus of elasticity is approximately equal to or higher than that of the adhesive component is necessary in order to obtain an appropriate connection state under pressure or heating and pressure during connection of one circuit.

This point will be discussed further later.

Regarding the adhesion between the metal coating layer and the polymer core material, in addition to paying attention to the polarity of the polymer core material and the above-mentioned coefficient of thermal expansion.

Surface activation methods such as plasma or corona treatment for polymer core materials, or various coupling agents.

Adhesion can be improved by applying surface treatment means such as a chelating agent and a polarizing agent as necessary. When the adhesion is improved, the coating layer can be prevented from falling off, and good electrical conductivity and insulation properties can be obtained.

Various metals can be used as the metal 2 used for wandering.

Metal oxide 1 alloy etc. are used, and are selected in consideration of the following.

(1) Must be a good conductor of electricity, preferably with a specific resistance of 100 x 10-'Ω-CHI or less, more preferably 10 x 1 (1'''6 Ω-cm or less).

(2) Thermal expansion coefficient near normal temperature is 1.0 x 10"5 ~
4.0x10-'('light).

Note that for the resistivity and coefficient of thermal expansion mentioned here, values published in various documents can be used, such as the revised 6th edition of the Mechanical Engineering Handbook published by the Japan Society of Mechanical Engineers.

The physical properties of metals described in 5-1 to 5-5 may be referred to. Examples of bonding elements that satisfy the condition of <13121 are Zn, AJ, and Sb.

U, Cd, Ga, Ca, Au, Ag, Co
, Sn, Se.

Fe, Cu, Th, Pb, Ni, Pd, B
e, Mg, Mn, etc., and these can be used alone or in combination, and other elements or compounds can also be added for special purposes, such as improving hardness or surface tension.

Methods for forming the metal 2 on the surface of the polymer core material 1 include physicochemical methods such as the vapor N method, sputtering method, ion blating method, and plating method, and methods for forming the metal 2 on the surface of the polymer core material 1. Metal powder is dispersed in a monomer and adsorbed onto the surface of polymer particles after one polymerization, the metal is chemically bonded to a core material having a functional group, or the metal is adsorbed using a fruit surfactant or a coupling agent. Method ability 1, such as chemical methods, can be adopted.

The thickness of the coating layer may be 0.001 to 5 μm, preferably α05 to 1 μm, but this thickness should fall within 115 to 1000 of the particle size of the conductive particles. The reason why there is a limit on the thickness is that if the thickness is too thin, the conductivity will decrease, and as the thickness increases, the difference in thermal expansion and contraction between the polymer core material and the adhesive component will increase, making it difficult to follow temperature changes. This is because there will be less.

Further, since metal is a thin layer against deformation, it has the ability to follow the era name, but it is more preferable to use a malleable material with a high elongation rate, for example.

Conventionally, glass spheres (beads) were used as such conductive particles.
Alternatively, a glass hollow sphere (balloon) may be coated with a thin layer of Ag or the like, but these cannot undergo saccharification and deformation when heated and pressurized, and are therefore unsuitable for carrying out the present invention.

゛The conductive particles obtained above have an average particle size of 0.5 to
The ratio of the maximum diameter to the minimum diameter of 300 μm 1 particle is a, 0
It shall be 5 to 1.0. If the particle size is 0.5t1m or less, a large amount of conductive particles is required, and as a result, the number of packed particles increases, resulting in poor adhesion to the circuit.
Particles larger than μm are undesirable because they are large and cause conduction (leakage) between adjacent circuits (spacens), making them unsuitable for connecting microcircuits. It is necessary to select conductive particles with a maximum particle size smaller than the space of the circuit, and considering the safety factor, it is recommended to use conductive particles with a maximum particle size of 1/2 to 1/4 of the space width. I like it.

As described above, the shape of the conductive particles is such that the ratio of the maximum diameter to the minimum diameter is about a05 to 1.0.

Outside this range, the particles become too flaky, making it unsuitable for simultaneously achieving the four-way conductivity between circuits and the insulation between adjacent circuits, which are the objectives of the present invention, and the adhesion to the circuits also tends to decrease. becomes stronger.

As an example that satisfies this range, a bispherical shape is representative, but there is no particular limitation as long as the groove satisfies the above conditions. In addition, there may be protrusions or irregularities on the particle surface (,
Further, the particles are not limited to single particles, but may be particles made of aggregates.

The particle size shall be the overall average particle size.

A convenient method for measuring the shape and diameter of particles is using a scanning electron microscope. The average particle size shall be determined by the following formula.

D=Σnd/Σn Here, n indicates the number of particles having a particle size of d.

When the conductive particles are spherical, it is easy to obtain contact with each other or between the particles and the circuit surface by heating and pressurizing during 1 MI, and it is easy to obtain high conductivity.

The conductive particles may exist in a single layer in the thickness direction of the connection member, or may have a structure in which a plurality of conductive particles are arranged or aggregated.

The conductive particles in the adhesive preferably account for 1 to 15% by volume a. If α is less than 1% by volume, satisfactory conductivity cannot be obtained, and if it is more than 15% by volume, the insulation with adjacent circuits decreases and the transparency of the adhesive film cannot be obtained. For the above reasons, a more preferable saturation amount is 05 to 10% by volume.

The adhesive used in the present invention can basically be of a composition used for ordinary adhesive sheets exhibiting insulation properties, and has a thermal expansion coefficient of 5X 10-' at room temperature.
(1/C) Selected from the following: The composition used for normal removable sheets is a polymer that provides cohesive force, and other tackifiers and tackifiers used as necessary.

It consists of a crosslinking agent, an anti-aging agent, a dispersing agent, etc.

These polymers include ethylene-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, polyethylene, ethylene-propylene copolymer, ethylene-acrylic acid copolymer, and ethylene-acrylic acid ester copolymer. , ethylene-acrylate copolymer, acrylic ester rubber, polyisobutylene, atactic polypropylene, polyvinyl butyral, acrylonitrile-butadiene copolymer, styrene-butadiene block copolymer, styrene-isoprene block copolymer, Polybutadiene, ethylene cellulose, phenoxy, polyester.

Epoxy, polyamide, polyurethane, natural rubber, silicone rubber, synthetic rubbers such as polychloroprene, polyvinyl ether, and the like can be used alone or in combination of 28 or more.

Tackifiers include dicyclopentadiene resin, rosin, modified rosin, terpene resin, xylene resin, terpene-phenol resin, alkylphenol resin, coumaron-indene resin, etc., and these can be used alone or in combination as necessary. Used in combination with the above. Typical adhesive y4 modifiers include various plasticizers including dioctyl phthalate.

Crosslinking agents are used when necessary to increase the cohesive strength of polymers, and are polyfunctional substances that react with the functional groups of polymers, such as polyinocyanates, melamine resins, urea resins, phenolic resins, amines, and acids. Examples include anhydrides, peroxides, etc., and benzophenone, benzoquinone, etc. may also be used as a sensitizer in the case of photocuring.

Anti-aging agents are polymer binders heat and oxygen.

Used when necessary to increase stability against light, etc., such as stabilizers such as metal soaps, antioxidants such as alkylphenols, and ultraviolet absorbers such as benzo2-enone and benzotriazole types. etc., which may be used alone or in combination in lengths of 2m or more, if necessary.

A dispersant may be used to improve the dispersibility of conductive particles. Examples of this include surfactants, which can be used in combination of 1m or 2 or more of nonionic, cationic, rionic, and amphoteric surfactants.

The above adhesive component has a thermal W elongation ratio of adhesive component/polymer core material of 15 to 15, and a ratio of elastic modulus of adhesive component/polymer core material of 1. 2 to α01.Here, the coefficient of thermal expansion means the tensile modulus of elasticity close to the l!ilJ expansion coefficient of 1 expansion and the single modulus of elasticity near normal temperature.

The above range is necessary from the viewpoint of connection reliability and long-term reliability of the circuit connection portion. Outside the specified range of thermal expansion coefficient,
This is not preferable because the difference in thermal expansion and contraction between the polymer core material and the adhesive component becomes large, and the conductive particles follow the expansion of the circuit due to the thermal expansion of the adhesive, resulting in poor contact between the conductive particles and the circuit. For the same reason, the preferred range is α6 to α9. The reason why the ratio of the elastic modulus of the polymer core material is approximately equal to or higher than that of the adhesive component is necessary for improving reliability during circuit connection.If this ratio is less than α01, the elasticity of the polymer core material is too high. Therefore, when connecting the circuit, the conductive particles tend to have insufficient point contact with each other and with the circuit, resulting in unsatisfactory conductivity. Since deformation and flow are likely to occur, insulation between adjacent circuits is lost (leakage), making it impossible to adapt to minute circuits and reducing the connection conditions. -For these reasons, the preferred range is 1.0 to α02.

The method for producing the adhesive composition according to the present invention includes dissolving the adhesive composition consisting of a polymer and other additives used as necessary in a solvent, dispersing it in a suspension state in a medium, or heating it. After melting to a liquid state, conductive particles are mixed using a conventional dispersion method such as a ball mill or stirring device.
A conductive particle mixed adhesive composition is obtained.

When using a solvent, it is possible to use a solvent because conductive particles with a metal layer formed on a polymer core material are hardly soluble in solvents, but it is possible to use a solvent to dissolve the adhesive. It is further preferable to select a solvent that does not dissolve the molecular core material. A good way to do this is, for example, to emulsify the adhesive and disperse the conductive particles in an aqueous medium.

The above-mentioned conductive particle mixed adhesive composition may be used to form an adhesive layer directly on one or both of the circuits requiring connection by using means such as screen printing or a roll coater, or may be used in the form of a film. It can also be used as a continuous long body. In order to obtain an adhesive film as a continuous elongated body, a connecting member layer may be formed by the above method on a separator made of paper, plastic film, etc., which has been subjected to a peeling treatment as necessary, and then continuously rolled up. If the adhesive layer has no tackiness, it is possible to roll the adhesive layer without using a separator, and it is also possible to use a core material such as a non-woven fabric to reinforce the adhesive.

In the above manufacturing method, when the adhesive composition contains a solvent or a dispersion medium, the volume shrinkage phenomenon in the thickness direction when the solvent dries is used to obtain an adhesive film in which the conductive particles are arranged more densely in the thickness direction. Moreover, in hot-melt coating without a solvent, environmental pollution caused by solvents during production can be prevented.

The thickness of the adhesive film is relatively determined by taking into account the particle size of the conductive particles and the temporal characteristics of the connecting member, but it is 1 to 3.
A thickness of 00 μm is preferred.

If it is less than 1 μm, sufficient fjIyIl properties cannot be obtained, and 30
If the diameter is 0 μm or more, it is not practical because a large amount of conductive particles must be mixed in order to obtain sufficient conductivity. For this reason, a more preferable thickness is 555-100a.

The adhesive film thus obtained has considerable transparency. If the adhesive film is transparent, it will be easier to manage the inventory during manufacturing and will have a good appearance. In addition, it is also possible to adopt a structure in which the adherend can be seen through the contact layer of display elements.

A method for connecting a circuit using the obtained adhesive film is, for example, by temporarily attaching the adhesive film to the circuit and peeling off the separator if there is a separator, or by applying an adhesive composition onto the circuit. - If necessary, after removing the solvent from the fabric, other circuits to be connected may be attached to that surface using a hot press or a heating roll.

The third direction and the diagram @4 schematically show the state in which the circuits are connected by the method described above. As the adhesive 4 softens and flows due to heat and pressure, the conductive particles 8 also soften and deform, and come into contact with each other. Therefore, conductive adhesion between both circuits 5 and 6 becomes possible.

Figure 3 is an example where there are multiple or more layers of conductive particles 8 in circuits 5 and 6. Gold IJ4/11 on the surface of the particles contact each other to form a 4m path, resulting in high conductivity. .

When applying heat and pressure during connection, since the corrugated metal is thin, it can optically follow the deformation of the polymer core material, and even if it cannot follow the deformation and defects such as cracks occur on the metal skin. 2
The conductive path can be maintained by contact with circuits or other particles.

To obtain the optimal connection state, the thickness t between the circuits after connection is determined by the thickness t of the adhesive composition (film) before connection.
It is necessary to set T=α02 to 095. At this time, if the conductive particles have a particle size before connection and exist in the form of a single particle in the thickness direction, the particle size after connection is d, and the ratio d/D can be calculated as follows. can.

[If the ratio is lower than LO2, the conductive particles will be destroyed and the metal flakes will easily fall off.If this ratio is higher than 195, sufficient surface contact with the circuit or conductive particles cannot be obtained, so it should be satisfied. Since connection reliability cannot be obtained, this method is unsuitable for implementing the present invention.

For the above reasons, the more preferable range of /r is 0.10 to a
It is 90.

As an easy way to get this optimal connection.

If a spacer made of a rigid body with a desired thickness is inserted between the circuits during the connection operation, or spacer particles smaller than the conductive particles and equal to the thickness between the circuits after the desired connection are mixed into the adhesive composition or adhesive film. 1. Since the conductive particles of the present invention can be deformed inadvertently, a desired thickness can be easily obtained.

(Function) ゛In the dynamic pressure of the adhesive composition according to the present invention, the metal bonded to the polymer core material comes into contact with each other or with the conductive circuit part due to pressure applied during connection or heating and pressure. to form a conductive path.

At this time, since the polymer core material can be softened or deformed during the connection operation by applying pressure or heating and pressurizing, it deforms appropriately so as to press against the circuit surface or between the conductive particles, increasing (maintaining) the contact area. It is possible to obtain good conductivity and reliability.On the other hand, particles in the insulated circuit part.

Since no pressure is applied to the particles between the circuits, by selecting the particle size and saturation amount of the conductive particles, insulation from adjacent circuits can be maintained to a certain level.

Since the softening deformation range of the flattened molecular core material can be arbitrarily set by selecting or combining the thermal characteristics of the material, it is possible to set a wide range of conditions during connection. For example, when the core material is an amorphous polymer that does not have a constant melting point, or when a crosslinked product with a wide rubbery region is used, t\
! Its softening flow range (from glassy to rubbery to liquid range)
It is possible to have a wide range of conditions for circuit connection (temperature, pressure for 1 hour), and the reliability during connection is significantly improved, as well as the connection workability is also good.

Furthermore, the degree of softening and deformation of the polymer core material can be set as desired depending on the connection conditions.

It is possible to manage the connection status. For example, even if the particle sizes of the conductive particles at the connection part do not match, by controlling the connection conditions as shown in Figure 4, the large conductive particles 8 can be crimped to the size of the small conductive particles 8' or larger. ``C connection is possible, and conductive particles can effectively contribute to conduction.On the other hand, in the case of conventional metal particles, the fifth
As shown in the figure, the large conductive particles 9 act in a Svener-like manner, and the other small particles 9' do not contribute to conduction, resulting in a decrease in the conduction point image and poor connection reliability.

The conductive particles that are moderately pressed between the circuits have a polymer core material with a thermal expansion coefficient similar to that of the adhesive component, so they have a high ability to follow changes in temperature after connection, and have excellent cold shock resistance. Excellent long-term connection reliability.

This situation will be explained using the connection schematic diagram in FIG.

When a temperature change is applied to the circuit connection part of the present invention, the circuit 5.6 threshold is reached due to thermal expansion and contraction in the y-axis direction due to the adhesive 4 having a relatively large coefficient of thermal expansion compared to the materials of the circuits 5 and 6. However, since the polymer core material and the adhesive 4 have similar coefficients of thermal expansion, and the metal 2 is thinner than light, the thickness direction of the circuits 5 and 6 It is possible to sufficiently follow the deformation, and the conductive connection of one circuit can be maintained well.

At this time, the adhesive 4 tries to thermally expand and contract in the X-axis direction, but its elastic modulus is relatively sufficiently small compared to the metal circuit, and deformation is substantially suppressed. is easily relieved.

(Example) The present invention will be explained in more detail below using examples.

Examples 1 to 9 and Comparative Example-1 (11!a Preparation of adhesive composition) Spherical particles of polystyrene resin whose surfaces were plated with Au and which had different particle sizes and coated layer thicknesses were mixed with a styrene-butadiene block. A polymer (Ml2.6) of 100 parts, 40 parts of a terpene tackifier with a softening point of 120°C, and 200 parts of toluene are mixed in an adhesive bath solution with varying amounts, and this mixture is subjected to ultrasonic dispersion. 90(2) Preparation of film This adhesive composition was coated with a bar coater to obtain an adhesive composition containing conductive particles.

It was coated on a separator (silicone-treated polyester film) and dried at 100° C. for 5 to 30 minutes depending on the thickness to remove the solvent and form an adhesive film.

(3) Evaluation line width α1ava, pitch Q, 21+1111. Total circuit width 100111111 with circuit thickness 35μm
Flexible circuit board (FPC) with N1 width 5 connections.

Place the above adhesive film cut into 100 length pieces on the lid.
Temporary attachment was carried out by heating and pressurizing at 20° C. and 10 kg/al′ for 5 seconds to obtain an FPC with a connecting member.

After that, the separator was peeled off, another FPC with the same pitch was placed on the separator peeled surface, and the FPC circuit was aligned using a microscope.
The circuit was connected by heating and pressurizing with aII+ for 20 seconds.

The evaluation results are shown in Table 1. In each of the Examples, the adhesive sheet had transparency.

The alignment of the circuit was easy with the help of transmitted light.

The properties are shown in Table 1. The connectors obtained in each example exhibited good conduction resistance and insulation from adjacent circuits, and the characteristics were good even after the reliability test.

In Comparative Example 1, the amount of conductive particles filled was as high as 20% by volume, or the circuit alignment was easy, and leakage occurred after the circuit was connected.

Examples 10 to 15 Same as Examples 1 to 9, but the type of conductive particles was changed. That is, epoxy spherical particles were used as the polymer core material, and in Examples 10 and 11, Cu M with a thickness of α2 μm was used.
On top of that, a Ni layer with a thickness of (L) of 2 μm was provided to form a metal composite layer.

In Examples 12 and 13, the a layer has a thickness α2III
It was set as the Au layer of II. The adhesive components and the evaluation score were the same as in Examples 1-9. Are the evaluation results shown in Table 1?
Each of the examples had good initial and post-reliability evaluation characteristics.

In the films of Examples 10 to 11, it was confirmed that the conductive particles formed in a chain in the thickness direction.

This phenomenon is thought to be due to preferential contraction of the adhesive component force 1 in the film thickness direction during the solvent drying process during film production, and the anisotropic conduction 1! This is a preferable form for conductive materials, and this phenomenon is likely to occur when the conductive particle diameter is relatively small compared to the film thickness.

Comparative Examples 2 to 4 Films were created and evaluated in the same manner as in Example 12, but the types of conductive particles were changed. That is, A as a conductive particle
U-coated 1-tomized Ni spheres, Ag-coated glass spheres, and /Sunda particles with a melting point of 150°C were used, respectively.

These results are shown in Table 1. In all ILs, the initial resistance was good, or continuity failure (open) occurred during the reliability test.

When the cross section of the circuit connection portion in Comparative Examples 1 to 3 was observed using a scanning electron microscope, no deformation of the conductive particles was observed, and the conductive particles were in point contact with the circuit.

L month, 11 To Example 14 16 Nitrile butadiene rubber (acrylonitrile j 155%
Spherical particles with a Mooney viscosity of 78) are coated with Al by vapor deposition.
'rt particles were obtained.

These conductive particles are used in acrylic adhesives with different curing systems as shown in Table 2 (5% acrylic acid as a functional group).
Contains, Tg=-40℃, viscosity 1000cps/20% toluene solution, mixed and dispersed in 25℃, and temporarily attached to FPC at room temperature.

It was pressed between two rolls at 25° C. and 5 kg/ar for 2 seconds on a transparent conductive glass having a circuit pitch of the same pitch as the FPC and having a thickness of 05 mm. After that, post-curing as shown in Table 2 was carried out, and the same evaluations as in Examples 1 to 9 were carried out.The results are shown in Table 3.

In Examples 14 to 16 of Table 2, pressure-sensitive adhesive was used as the main component of the adhesive, so it was possible to connect circuits at room temperature, and since pressure-sensitive connections between rolls were possible, connections could be made in a short time. It was possible to do so.

In the reliability test of Example 14, the increase in resistance value was relatively large, but within a practical range.

In Examples 15 and 16, heat resistance was imparted by crosslinking and curing the connection part with heat or ultraviolet rays, and Example 1
The increase in resistance value after the 4JC comparison test was small.

The reason why the resistance values in Examples 14 to 16 are higher than those in Examples 1 to 13 is that they include the circuit resistance of the transparent conductive glass.

Further, in Example 16, ultraviolet rays were irradiated from the glass circuit side.

Examples 17-19 and Comparative Example 5 In order to change the physical property values of the polymer core material and H8 adhesive component, different combinations of materials were studied.

The material combinations and planning results are shown in Table 3.

The polymer core material is coated with Ag with a thickness of α2 μm by plating. Powdered polyimide was used as the polymer core material.

Maku polyester is a thermoplastic polyester (molecular weight approximately 2
o, oac + rgy °C), and NBR is Example 14~
It is the same material as No. 16. The acrylic rubber used as the adhesive component was the same material as in Examples 14 to 16, and the polyester was the thermoplastic polyester used for the polymer core material.

In the IC of Example 19, an FPC (Cu thickness 55 am) with a pitch of 14 mm (α2 mm in the circuit) and transparent conductive glass were used.

These evaluations were conducted in the same manner as Examples 14 to 16, but
In Examples 18 to 19 and Comparative Example-5, in order to obtain MNN acid component adhesion, the temperature was 170°C-20kg/aIP-
Raise the temperature for 20 seconds and connect.

The results are shown in Table 3, and each example had good characteristics. In Example 19, since the polymer core material and the adhesive component were made of the same material, the followability during thermal expansion and contraction was particularly good, and particularly excellent characteristics were exhibited in the reliability test.

Comparative Example 5 is a combination in which the polymer core material has a high coefficient of thermal expansion and a low modulus of elasticity compared to the adhesive component. Leakage occurred due to high liquidity.

Examples 20 to 21 Conductive particles having an average particle size of 300 μm (maximum particle size of 550 μm)
The adhesive composition and 2 ilms of S
changed the law.

That is, epoxy particles were used as the polymer core material, Ni was formed by electroless plating, and Zhaojiu polyester was used as the adhesive component in Example-18.

In Example 20, the adhesive composition was heated to 190° C. and cast between heated rolls to form a film by hot melt coating, which was then temporarily pasted onto an FPC.

In Example 21, as in Examples 1 to 9, an adhesive composition dissolved in a solvent (in this case, a 30% solution of methyl ether ketone) was applied directly to the FPC by silk screen printing on the circuit surface of the FPO. was dried to obtain an FPC with an adhesive composition.

In Examples 20 to 21, the pitch was 1.27 mm.
(0.655ff1ml in circuit, circuit thickness 55 am
An FPC (Cu foil) was used. Connect transparent conductive glass with the same pitch as this FPC (170℃-50kg/aIF
-20 seconds) are shown in Table 3.

It can be seen that both Examples 20 and 21 have good characteristics. In Example 20, no solvent was used, so the working environment was favorable.

In Example 21, since it was applied directly onto the circuit, there was no need for a temporary pasting operation when connecting the circuit.

-! Either it was impossible to measure the total light transmittance of only the adhesive composition layer, or it had the same transparency as Example-21 after temporary attachment to the FPC, and alignment of one circuit was easy. .

Table 4 summarizes the relationship between the material combinations of the polymer core material and adhesive component used in the above Examples and Comparative Examples and the physical property values (thermal expansion coefficient and elastic modulus) of each material. According to Table 4, the ratio of the coefficient of thermal expansion of the polymer core material to the adhesive component is α66.
As described above, those having an α of 95 and an elastic modulus ratio of 102 to 1.2 showed good results.

Below - White Example 22 25 A circuit similar to Example 14 using the film obtained in Example 11 (FPC/transparent conductive glass).

We examined the effects of connection conditions on the combination of pitch α21111+). The results are shown in Table 5, and the temperature was 15.
0 to 180℃, pressure 5 kg/cm to 50 kg/-
, good results were obtained under a wide range of connection conditions, ranging from 5 seconds to 50 seconds. At this time, the ratio of the adhesive film thickness before and after connection was ClO2--Q, 50.

In Examples 22 to 25, several conductive particles were connected in the film thickness direction between the connecting circuits, deformed and compressed, and came into contact with the circuits.

In the case of Example 24, the thickness between the connected circuits was compressed to 3 μm, which is equal to the average particle diameter of the conductive particles, and both the number of contact points with the n circuit and the area of θ increased significantly. In the case of No. 25, the single particle was further deformed and compressed into light, increasing the contact area with the circuit.

In each example, it was possible to obtain good initial characteristics in both conduction resistance and insulation resistance, and good circuit connection with almost no increase in resistance after the reliability test.

Examples 26-32 Using the film obtained in Example-12,! i! Example-2
With a combination of circuits (FPC/transparent conductive glass) similar to 2 to 25, mll5I! We looked at the effects of time conditions.

The results are shown in Table 5. As in Examples 22-25, it was possible to obtain a highly reliable connection in a wide connection strip.

In Examples 26 to 52, when the film thickness and the conductive particle diameter were equal, the film was deformed in a single particle form during one circuit.90 The ratio of change in thickness was α30 to α90.

Comparative Examples-6 to 12 Using the film obtained in Comparative Example-4, 52 to Example 26
Similar evaluations were conducted and the results are shown in Table 5.

If the temperature at the time of connection is lower than the melting point of the solder particles (150℃), the reliability in the thermal shock test will be low. A leak occurred. If the connection is at 150°C, which is the same as the melting point of the powder particles, the reliability is low if the pressure is low or for 1 hour, and leaks may occur if the pressure is too low.Optimal violence conditions appears to be within a very narrow range.

Below is the first part above the margin. 5. The measurement conditions for the evaluation in Table 5 are shown below.

(1) Continuity resistance is measured by using a multimeter to measure the resistance between opposing wires of two connected circuits (connection area 0.1nIII
+×5mff1). 103Ω or more was left open.

(2) Insulation resistance is the resistance between adjacent circuits of two connected circuits - measured with an image ohmmeter.

I Q"Ω or less is a leak.

(3) Reliability is determined by measuring the initial resistance after 100 cycles of thermal shock at 140°C for 30 minutes and 100°C for 30 minutes by connecting 92 circuits using adhesive films, etc. Evaluation was made by comparing with 9. Thermal shock test.

It is the most severe reliability evaluation method that estimates long-term life from short-term evaluation, and is the most important test method for practical tests.

(4) Total light transmittance was measured using a Nippon Denshoku Kogyo Digital Turbidity Meter ND1 (-20D) in accordance with JIS K-6714.

(5) Measurement of coefficient of thermal expansion and modulus of elasticity A sample of a sheet approximately 300 μm thick was prepared by hot pressing or, in the case of a thermally reactive system, by a solvent removal method. Using this sample, the thermal expansion coefficient was determined using the Shinku Riko Shifi Thermomechanical Testing Machine TMA-130.
By 0.

In addition, the elastic modulus and t were measured using Tensilon UTM-1 manufactured by Toyo Bold Twin@ in accordance with ASTM D882-64TK.

(Effects of the Invention) As detailed above, in the adhesive composition and adhesive film for circuit connection according to the present invention, and in the nine connection force method using the same, the surface of the polymer core material has a conductive metal. By using conductive particles formed in a thin layer, the conductive particles deform appropriately so as to press against the circuit surface or each other when the circuit is connected, so the contact area can be kept large, resulting in excellent conductivity. performance and good reliability. On the other hand, in the isolated circuit section.

Particles between the circuits are traps because no pressure is applied to them.

Insulation from adjacent circuits is maintained by light beams, so it can be applied to connect microcircuits.

Furthermore, since the softening deformation range of the polymer core material is optically wider than that of metals which exhibit a constant melting point, it is possible to have a wider range of conditions during the bonding process, which improves the reliability during the bonding process.

In addition, since the polymer core material GK7II agent component and black component coefficient are similar, the thermal expansion of the adhesive increases the distance between the connected circuits (even if the thermal expansion of the conductive particles causes the contact between the particles and the circuit to It is well maintained and has excellent long-term connection reliability.

Furthermore, it is possible to manage the connection status using a relatively simple method such as thickness measurement, and since the adhesive film is transparent, it is possible to align the fine circuits with the help of transmitted light. It has the advantage of being easy to perform. In addition, the conductive particles are extremely useful from the standpoint of resource conservation, as they utilize metal properties.

[Brief explanation of drawings]

Figures 1 and 2 are schematic cross-sectional views of conductive particles according to the present invention, rpJs diagrams and Figure 4 are schematic cross-sectional views showing a state in which a circuit is connected using the adhesive film according to the present invention. A schematic cross-sectional view of a circuit connection using conventional conductive particles,
FIG. 6 is a schematic cross-sectional view of a circuit connection part using conductive particles according to the present invention. Explanation of symbols 1 Polymer core material 2 Gold plate 3 Hollow part 4 Adhesive 5 Circuit 6 Circuit 7! e Edge pouring substrate 8 Conductive particles 9 Conductive! !
tJ2 children (conventional) Procedural amendment (voluntary) Showa 6118/23

Claims (1)

[Claims] 1. In an adhesive composition for circuit connection comprising an insulating adhesive component and conductive particles, the conductive particles satisfying the following conditions (a) and (b) are added in an amount of 0. An adhesive composition for circuit connection, characterized in that the adhesive composition contains 1 to 15% by volume. (a) The conductive particles are made of a polymer material as a core material and have an aspect ratio of 0.05 to 1.0 and 0.5 to 3, with almost the entire surface covered with a conductive metal thin layer.
(b) the ratio of the coefficient of thermal expansion of the core material to the adhesive component is 0;
．． 5 to 15, and the ratio of elastic modulus is 1.2 to 0.01
To be. 2. The adhesive composition for circuit connection according to claim 1, wherein the core material has plastic deformability when applied with pressure or heat and pressure. 3. Claim 1 or 2, wherein the core material has a coefficient of thermal expansion of 20 x 10^-^6 (l/°C).
The adhesive composition for circuit connection described in Section 3. 4. The thickness of the metal thin layer formed on the surface of the core material is 0.01~
The adhesive composition for circuit connection according to any one of claims 1 to 3, which has a particle size of 5 μm, which is 1/5 to 1/1000 of the particle size of the conductive particles. 5. The adhesive composition for circuit connection according to claim 1, wherein the adhesive component has heat-sensitive pasting properties. 6. The adhesive composition for circuit connection according to claim 1, wherein the adhesive component has pressure-sensitive pasting properties. 7. The adhesive composition for circuit connection according to claim 1, 5, or 6, wherein the adhesive component is a thermosetting type and/or a photocuring type. 8. An adhesive film for circuit connection consisting of an insulating adhesive component and conductive particles must contain 0.1 to 15% by volume of conductive particles that satisfy the following conditions (a) and (b): Adhesive film for circuit connections featuring: (a) The conductive particles are made of a polymer material as a core material and have an aspect ratio of 0.05 to 1.0 and a surface ratio of 0.5 to 3.
(b) the ratio of the coefficient of thermal expansion of the core material to the adhesive component is 0;
．． 5 to 15, and the ratio of elastic modulus is 1.2 to 0.01
To be. 9. The adhesive film for circuit connection according to claim 8, wherein the core material has plastic deformability when applied with pressure or heat and pressure. 10. The coefficient of thermal expansion of the core material is 20 x 10^-^5 ~ 2 x 10
The adhesive film for circuit connection according to claim 8 or 9, which has a value of ^-^5 (l/°C). 11. The thickness of the metal thin layer formed on the surface of the core material is 0.01
The adhesive film for circuit connection according to any one of claims 8 to 10, wherein the adhesive film has a particle size of 1/5 to 1/1000 of the particle size of the conductive particles. 12. The adhesive film for circuit connection according to claim 8, wherein the adhesive component has heat-sensitive adhesion properties. 13. The adhesive film for circuit connection according to claim 8, wherein the adhesive component has pressure-sensitive adhesion properties. 14. Claim 8, 12 or 13, wherein the adhesive component is thermosetting and/or photocuring.
Adhesive film for circuit connection as described in section. 15. The adhesive film for circuit connection according to claim 8 or any one of claims 12 to 14, wherein the film has a thickness of 1 to 300 μm. 16. Total light transmittance according to JIS K-61714 is 4
The adhesive film for circuit connection according to claim 8 or 12 to 15, which has a content of 0% or more. 17. Conductive particles in which almost the entire surface of a polymer core material having plastic deformability is covered with a conductive metal thin layer by applying pressure or heat and pressure are placed in a thermosetting and/or photocuring adhesive. An adhesive composition or adhesive film prepared by dispersing 0.1 to 15 volumes of the adhesive composition or adhesive film is interposed between opposing electrode circuits, and the thickness of the adhesive layer between the circuits is 0.02 to 0.0 of the initial thickness.
A method for connecting circuits, characterized in that electrical connections and mechanical connections between circuits are made by applying pressure or heating and pressurizing to a range of 95%. 18. The method for connecting a circuit according to claim 17, wherein the circuit connection portion is crosslinked and cured by heating and/or light irradiation during connection and/or after connection.