JPH1197482A - Electrode connecting method and electrode connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce thermal influences, by a method wherein connection terminals of two circuit members are facing each other, and a film-like circuit connection material of which essential components are an optical curing resin, an optical start agent, a high polymer resin of a molecular weight of a specified value or more and conductive particles resides therebetween, and they are connected by heating, pressing and optical irradiation. SOLUTION: At least one of a pair of circuit members has an optical transmission, and a first connection terminal and a second connection terminal thereof are disposed counter to each other, and a film-like circuit connection material of which essential components are a thermosetting resin, an optical start agent, a high polymer resin of a molecular weight 10,000 or more and conductive particles resides therebetween, and the first connection terminal and the second connection terminal disposed counter to each other by heating, pressing and light irradiation are electrically connected to each other. Since curing of the film-like circuit connection material is performed mainly by light curing, the temperature is in the range of 80 to 140 deg.C. Accordingly, it is possible to enhance handling and unifomize a connection thickness, and to attain an excellent adhering face and favorable electric conductivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrode connection method and an electrode connection structure.

[0002]

2. Description of the Related Art A film-like circuit connecting material is made of an adhesive containing a predetermined amount of conductive particles such as metal particles.
This film-shaped circuit connecting material is provided between the electronic component and the electrodes or the circuit, and by applying pressure or heat and pressure, both electrodes are electrically connected and insulation between adjacent electrodes is provided. Then, the electronic component and the circuit are bonded and fixed. As an adhesive used for the film-like circuit connection material, a styrene-based or polyester-based thermoplastic material, or an epoxy-based or silicone-based thermosetting material is known. A curing agent is required to cure the adhesive containing these substances, and the curing agent is inactive at room temperature in order to enhance the storage stability of the film-like circuit connection material, and is at or above the activation temperature. Must have the potential to react only at Therefore, in order to cure the adhesive, it is necessary to apply heat and pressure for improving the fluidity of the resin component and accelerating the curing reaction. That is, the adhesive is melted and fluidized, the conductive particles are deformed to increase the contact area with the circuit, and temperature and pressure are required to increase the adhesion to the circuit member. And hardening components. In addition, as a circuit connection material having a form other than a film shape, a paste-like material using a photocurable resin is known, but these circuit connection materials connect circuit members by pressing or heating and pressing. And
Thereafter, the adhesive is cured by light irradiation.

[0003]

However, the influence of heat and pressure on the circuit member due to the heating and pressurizing during the curing of the resin exists regardless of the magnitude thereof, and especially the thermal effect is exerted on the circuit member itself. In addition to the effects of the above, the effects of connecting the circuit members are also large. That is, in the former case, for example, when connecting a circuit member such as a liquid crystal panel, there is a concern about the influence on the liquid crystal panel itself such as a polarizing plate, which requires a connection at a lower temperature than before or a connection in a shorter time than before. I have. In the latter case, when the connection is performed under the condition that the temperature at the time of heating and pressurizing is high, the two circuit members facing each other are different, and when the difference between the respective thermal expansion coefficients (α) is large, the circuit is misaligned. Is more likely to occur. This is more likely to occur as the pitch between adjacent circuits is reduced. The present invention has been made in view of such a situation. By using light irradiation together, it is possible to connect at a lower temperature than before, reduce the thermal effect on circuit members, and improve the reliability of the connection part after connection. It is intended to provide a method for connecting electrodes using a film-like circuit connection material, which is excellent in terms of quality, and which does not affect the quality of the conventional easy-to-handle property.

[0004]

SUMMARY OF THE INVENTION The present invention uses a film-like circuit connection material containing a photo-curing component to perform heating necessary for the melt flow of the connection material, and to connect the electrodes together with light irradiation. About the method.

[0005] According to the electrode connecting method of the present invention, at least one of the two circuit members has a light transmitting property, that is, a first circuit member having a first connection terminal and a second circuit member having a second connection terminal. A circuit member, a first connection terminal and a second connection terminal are arranged to face each other, and a photocurable resin, a photoinitiator is provided between the first connection terminal and the second connection terminal arranged opposite to each other. By interposing a film-like circuit connection material containing a polymer resin having a molecular weight of 10,000 or more and conductive particles as essential components, using a combination of heating and pressing for a certain time and light irradiation for a certain time, The first connection terminal and the second connection terminal are electrically connected to each other. Further, an interval of one to several seconds is provided after the start of heating and pressurizing for a certain time, and light irradiation is started for a certain time after the elapse of the predetermined interval. Is performed for a while after the completion of the heating and pressurizing step. In the present invention, as a circuit member, a semiconductor chip, a resistor chip,
Chip components such as capacitor chips, substrates such as printed boards, liquid crystal panels and the like are used. These circuit members usually have a large number of connection terminals (in some cases, a single connection terminal may be used).
At least one set of the circuit members, at least one of which has optical transparency, is provided, and at least one part of the connection terminals provided on the circuit members is opposed to each other, and an adhesive is provided between the opposed connection terminals. , And the connection terminals facing each other are heated and pressurized and irradiated with light to electrically connect them to form a connection body. At this time, the thickness of the light-transmitting circuit member is preferably 1.2 mm or less in terms of light-transmitting properties.

[0006] Further, by making the circuit connection material containing a photocurable resin into a film form, the handleability is excellent and the connection thickness can be made uniform as compared with the conventional paste circuit connection material. It is advantageous in the point and the like. Furthermore, in order to enhance the adhesiveness with the circuit member, when heating is performed to such an extent that the curing reaction hardly progresses and the resin flows, the connection material is heated to conduct the connection between the connection terminal, the conductive particles, and the connection terminal. After ensuring the above, it is possible to increase the melt viscosity of the connection material again by introducing a cooling step, whereby the pressure-contact state of the conductive particles by only heating and cooling can be maintained and the resin can be fixed. This is not possible with paste-like circuit connection materials.

According to the first aspect of the present invention, the first connection terminal and the second connection terminal are opposed to each other, and a photocurable resin, a photoinitiator, and a polymer resin having a molecular weight of 10,000 or more are interposed therebetween. And a film-like circuit connection material containing conductive particles as an essential component, and the first connection terminal and the second connection terminal arranged opposite to each other are electrically connected by heating, pressurizing and light irradiation. Since the curing of the film-like circuit connection material is mainly performed by photo-curing, the role of the heating and pressurizing step is to melt and flow the adhesive and sufficiently remove the resin component around the portion where the connection terminals and the conductive particles come into contact. To eliminate
This can be considered to sufficiently press the conductive particles between the connection terminals. For this reason, heating may be performed to a temperature higher than the Tg of the adhesive or to a temperature at which the flow of the adhesive necessary for sufficient deformation of the conductive particles can be obtained. The temperature depends on the type of the polymer resin as the film forming material. , Approximately in the range of 80 to 140 ° C. This is lower than the heating temperature of 150 to 190 ° C. required for connection of a film-like circuit connection material using a conventional thermosetting resin as a curing component. Therefore, the connection temperature of the circuit member can be reduced by the above method.

A photocurable resin having a molecular weight of 10,000
By using the above-mentioned polymer resin and conductive particles as essential components, a photocurable film-like circuit connection material can be provided. It has a molecular weight of 10,
Most of the polymer resins having a molecular weight of 000 or more are solid at room temperature and have high film forming ability. By mixing this polymer resin and photo-curable resin, it is possible to improve the handleability and uniform the connection thickness, which were disadvantages of conventional circuit connection materials using photo-curable resin. It is.

Further, when heating and pressurizing and light irradiation are performed simultaneously, it is necessary to adjust the melt fluidity and the light irradiation ability in order to sufficiently contact the conductive particles by the flow of the adhesive. The light irradiation ability here depends on the light source of the light irradiation device used, and in the case of a light irradiation device using a light source with a small amount of light, the curing speed of the adhesive becomes slow,
During that time, the resin flows sufficiently, so that heating and pressurization and light irradiation can be performed at the same time. In the case of a light irradiation device using a light source having a large amount of light, in order to give priority to the flow of the resin, one to one light irradiation is performed between the heating and pressing step and the light irradiation step.
Light irradiation can be performed after an interval of several seconds and heating and pressurization is started. In this case, since the light irradiation is performed with a delay, after the resin flows and the conduction of the connection terminals by the conductive particles is ensured, the amount of light may be increased to rapidly cure the resin in a short time.

Claims 2, 3, and 4 all relate to a method of terminating each step in the case where the heating and pressing step and the light irradiating step are used together. The adhesive resin is sufficiently cured by light irradiation while the conductive particles are melted and flown and the conductive particles are sufficiently pressed between the circuit members, and various properties such as adhesive strength, initial resistance, connection reliability, etc. If no influence is exerted on the heating and pressurizing step, the heating and pressurizing step and the light irradiation step can be completed at the same time (claim 4). If it is necessary to lower the connection temperature of the circuit components, it is necessary to shorten the heating and pressurizing time as well as the connecting temperature of the heating and pressurizing time itself. May be required. However, when shortening the connection time in this way, if the heating and pressurizing step and the light irradiation step are completed at the same time, the light energy required to react the adhesive resin is reduced if the light irradiation ability is the same, The reaction rate of the adhesive is reduced, and there is a concern that the above-described various properties may be reduced. The means for solving this is the method according to claim 2, wherein in order to reduce the thermal effect on the circuit member, the adhesive resin melts and flows during the heating and pressurizing time, and the conductive particles are removed from the circuit member. This is performed under such conditions as to make sufficient pressure contact. The light irradiation is used in combination during that time, and is performed under conditions such that the above state is maintained, and curing of the adhesive resin is started. Even if the curing of the adhesive resin by light irradiation is insufficient, the heating and pressurizing step may be terminated as long as the above pressed state is maintained, and only the light irradiation is continued, and the adhesive resin is completely cured. Let it. In the method of claim 3, since only the heating is completed in the state where the connection body is pressurized, the heating and pressurizing step is started while maintaining the state where no further heating is performed on the connection body. Will be fixed in position. Therefore, the light irradiation can be continuously performed until the adhesive resin is completely cured, without fear of the possibility of displacement of the light irradiation of the connection body.

Claim 5 relates to the sequence of performing the heating and pressurizing for a certain period of time and the light irradiation for a certain period of time. It is most ideal to start and end the light irradiation at the same time, considering the required time.However, in order to ensure better connection reliability, it is necessary to set the time between the heating and pressing step and the light irradiation step. An optimal method is to provide an appropriate interval to ensure sufficient time for the adhesive resin to flow sufficiently. Ideally, the interval is set to the time from the start of heating and pressurization until the flow of the adhesive resin is almost completely completed, and more preferably 1 to several seconds. The term “several seconds” varies depending on the melt viscosity of the adhesive resin, but is preferably 2 to 5 seconds.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The film-like circuit connecting material used in the present invention comprises an adhesive component obtained by mixing a solid polymer resin for imparting a film-forming property to a photocurable resin, and conductive particles. In addition, by making the connection material into a film shape, it is possible to improve the handleability when connecting the circuit member.

The photocurable resin for use in the present invention includes photopolymerizable oligomers such as epoxy acrylate oligomer, urethane acrylate oligomer, polyether acrylate oligomer, polyester acrylate oligomer, trimethylolpropane triacrylate, polyethylene glycol diacrylate, and polyalkylene. There are photopolymerizable resins represented by acrylates such as photopolymerizable polyfunctional acrylate monomers such as glycol diacrylate and pentaerythritol acrylate, and methacrylates similar to these, and if necessary, these resins. May be used alone or as a mixture. However, in order to suppress the curing shrinkage of the cured adhesive and to impart flexibility, it is preferable to blend a urethane acrylate oligomer. There. Further, since the above-mentioned photopolymerizable oligomer has a high viscosity, it is preferable to mix a low-viscosity monomer such as a photopolymerizable polyfunctional acrylate monomer for viscosity adjustment.

These photocurable resins are polymerized and cured using a photoinitiator. Examples of the photoinitiator used in the present invention include benzoin ethers such as benzoin ethyl ether and isopropyl benzoin ether, benzyl ketals such as benzyl and hydroxycyclohexyl phenyl ketone, ketones such as benzophenone and acetophenone and derivatives thereof, thioxanthones and biimidazoles. Sensitizers such as amines, sulfur compounds, and phosphorus compounds may be added to these photoinitiators as needed at any ratio. At this time, it is necessary to select an optimal photoinitiator according to the wavelength of the light source used, the desired curing characteristics, and the like. Further, these photocurable resins and polyethylene, ethyl acetate, thermoplastic resins such as polypropylene, and polyethersulfone having high heat resistance, polyetherimide, thermosetting resins such as polyimide resins and epoxy resins, or A phenoxy resin, an elastomer or the like can be used as a mixture.

When the adherend is an inorganic substance, a silane coupling agent can be mixed with the adhesive resin to enhance the adhesive strength with the adherend. Examples of the silane coupling agent include vinyltrichlorosilane, vinyltriethoxysilane, vinyl-tris- (β-methoxyethoxy) silane,
γ-methacryloxypropyltrimethoxysilane, γ-
Glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, isopropyltriethoxysilane isocyanate, etc. It is more preferable to use γ-methacryloxypropyltrimethoxysilane to increase the value.

As the light used for curing, generally used ultraviolet rays can be used, and can be generated by a mercury lamp, a metal halide lamp, an electrodeless lamp or the like. In addition, when a radical reaction is used as the curing reaction, oxygen acts as a reaction inhibitor, so that the amount of oxygen in the atmosphere of light irradiation affects the curing of the photocurable resin.
Since this greatly depends on the type and concentration of the photocurable resin, photoinitiator, sensitizer, and the like, it is necessary to study in detail for each compounding system.

As the conductive particles, Au, Ag, Ni,
There are metal particles such as Cu, solder and the like, carbon and the like, and those obtained by forming the above-described conductive layer on these materials and non-conductive glass, ceramic, plastic or the like by coating or the like may be used. In the case of using plastic as a nucleus or hot-melt metal particles, they are deformable by heating and pressing, so that the contact area with the electrode at the time of connection increases and reliability is improved, which is preferable.
The conductive particles are used in an amount of 0.1 to 100 parts by volume of the adhesive component.
It is used properly depending on the application in a wide range of 1 to 30 parts by volume. In order to prevent a short circuit or the like in an adjacent circuit due to excessive conductive particles, the volume is more preferably 0.2 to 15 parts by volume. At this time, the average particle size of the conductive particles depends on the amount added, but is preferably 1 to 15 μm. In addition, the compression elastic modulus of the conductive particles, when heating and pressurizing and light irradiation is interrupted, to suppress the restoration of particles due to the elasticity of the adhesive,
It is preferable to be in the range of 1,000 to 10,000 MPa.

[0018]

The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. Example 1 40 g of a phenoxy resin (trade name: PKHA, manufactured by Union Carbide Co., Ltd.) was mixed with toluene (boiling point: 11
0.6 ° C, SP value 8.90) / ethyl acetate (boiling point 77.
1 g, SP value 9.10) = 60/50/50 mixed solvent 60 g
Into a solution having a solid content of 40%. The photocurable resin is an epoxy acrylate oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name NK Oligo EA-1020) and an acrylate monomer (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name NK Ester A-TMM-3L), It was used at a weight ratio of 3/1. The photoinitiator used was benzophenone, and 4,4′-bisdiethylaminobenzophenone was used as a sensitizer (trade name: EAB, manufactured by Hodogaya Chemical Industry Co., Ltd.).
Was used so that photoinitiator / sensitizer = 5/1. On the surface of the particles having polystyrene as a core, a thickness of 0.
A nickel layer of 2 μm is provided, and outside the nickel layer,
A gold layer having a thickness of 0.02 μm was provided, and conductive particles having an average particle size of 5 μm and a specific gravity of 2.5 were produced. Phenoxy resin 50, photocurable resin 50, photoinitiator 5, sensitizer 1 in solid weight ratio
Then, 3% by volume of the conductive particles are mixed and dispersed, applied to a 80 μm-thick fluororesin film using a coating device, and dried at 70 ° C. for 10 minutes with hot air to reduce the thickness of the adhesive layer. A film-like circuit connection material of 20 μm was obtained. Using the film-like circuit connection material obtained by the above method, a line width of 50 μm, a pitch of 100 μm, and a thickness of 1
Flexible circuit board (FPC) with 500 8 μm copper circuits and 0.2 μm indium oxide (ITO)
(Thickness 1.1 mm, surface resistance 2)
0 Ω / □) at 130 ° C., 2 MPa as shown in FIG. 1 using an ultraviolet irradiation combined thermocompression bonding apparatus (heating method: constant heat type, manufactured by Toray Engineering Co., Ltd.).
For 20 seconds and UV irradiation from the ITO glass side were simultaneously performed to connect over a width of 2 mm, and after a lapse of time, the pressure was released to produce a connected body. The amount of ultraviolet light (hereinafter referred to as ultraviolet irradiation amount) irradiated to the adhesive is 2.0 J / cm ^2.
And At this time, after bonding the adhesive surface of the film-like circuit connection material on the ITO glass in advance,
Temporarily connect by heating and pressing at 0.5 MPa for 5 seconds,
The fluororesin film was peeled off and connected to another FPC as an adherend.

Example 2 A flexible circuit board (FPC) having 500 copper circuits having a line width of 50 μm, a pitch of 100 μm, and a thickness of 18 μm was prepared by using the film-like circuit connection material of Example 1;
A glass (thickness: 1.1 mm, surface resistance: 20 Ω / □) on which a thin layer of indium oxide (ITO) having a thickness of 2 μm is formed is combined with an ultraviolet irradiation combined thermocompression bonding apparatus (heating method: constant heat type, manufactured by Toray Engineering Co., Ltd.) As shown in FIG. 1, heating and pressurizing at 130 ° C. and 2 MPa for 5 seconds and ultraviolet irradiation from the ITO glass side are simultaneously performed to connect over a width of 2 mm, and after a lapse of time, the pressure is released to produce a connected body. did. At this time, after bonding the adhesive surface of the film-like circuit connection material on the ITO glass in advance,
Temporarily connected by heating and pressing at 70 ° C and 0.5 MPa for 5 seconds,
Thereafter, the fluororesin film was peeled off and connected to another FPC as an adherend. In addition, at the time of connection for 5 seconds in FIG.
UV irradiation was started for a second. After 5 seconds from the start of the heating and pressurizing, the heating and pressurizing step was completed, and the connected body was irradiated with ultraviolet rays for 15 seconds. At this time, the total amount of ultraviolet irradiation, that is, the sum of the amount of irradiation performed during heating and pressurization and the amount of irradiation continuously performed was 3.6 J / cm ² .

Example 3 A flexible circuit board (FPC) having 500 copper circuits having a line width of 50 μm, a pitch of 100 μm, and a thickness of 18 μm was prepared using the film-like circuit connecting material of Example 1, and
A glass (thickness: 1.1 mm, surface resistance: 20 Ω / □) on which a thin layer of indium oxide (ITO) having a thickness of 2 μm is formed is combined with an ultraviolet irradiation combined thermocompression bonding apparatus (heating method: constant heat type, manufactured by Toray Engineering Co., Ltd.) As shown in FIG. 1, heating and pressurizing at 130 ° C. and 2 MPa for 5 seconds and ultraviolet irradiation from the ITO glass side are simultaneously performed to connect over a width of 2 mm, and after a lapse of time, the pressure is released to produce a connected body. did. At this time, after bonding the adhesive surface of the film-like circuit connection material on the ITO glass in advance,
Temporarily connected by heating and pressing at 70 ° C and 0.5 MPa for 5 seconds,
Thereafter, the fluororesin film was peeled off and connected to another FPC as an adherend. In addition, at the time of connection for 5 seconds in FIG.
UV irradiation was started for a second. After 5 seconds from the start of heating and pressurization, only the heating step was completed, and the connection was continuously irradiated with ultraviolet rays for 15 seconds with pressure applied. At this time, the total amount of ultraviolet irradiation, that is, the sum of the amount of irradiation performed during heating and pressurization and the amount of irradiation continuously performed is 3.6 J / cm.
^{And 2} .

EXAMPLE 4 A flexible circuit board (FPC) having 500 copper circuits having a line width of 50 μm, a pitch of 100 μm, and a thickness of 18 μm using the film-like circuit connecting material of Example 1 was prepared.
A glass (thickness: 1.1 mm, surface resistance: 20 Ω / □) on which a thin layer of indium oxide (ITO) having a thickness of 2 μm has been formed is combined with an ultraviolet irradiation-type thermocompression bonding apparatus (heating method: constant heat type, manufactured by Toray Engineering Co., Ltd.) As shown in FIG. 1, heating and pressing at 130 ° C. and 2 MPa for 10 seconds and ultraviolet irradiation from the ITO glass side were simultaneously performed to connect over a width of 2 mm, and after a lapse of time, the pressure was released.
A connection body was produced. The amount of ultraviolet irradiation was 1.6 J / cm ² . At this time, after the adhesive surface of the film-like circuit connection material is pasted on the ITO glass in advance, the temperature is set to 70 ° C. and 0.1 mm.
Temporarily connect by heating and pressurizing at 5 MPa for 5 seconds, and then peel off the fluororesin film and FP which is the other adherend
Connected to C. In addition, at the time of connection for 10 seconds in FIG. 1, ultraviolet irradiation was started for 8 seconds after 2 seconds had elapsed after only heating and pressurization was started, and two steps were simultaneously completed 10 seconds after heating and pressurization.

Example 5 The conductive particles of the film-like circuit connecting material used in Examples 1 to 4 were converted to nickel particles having an average particle size of 5 μm (trade name DSP3101, specific gravity 8.5, manufactured by Daido Special Co., Ltd.). Except having changed, the connection body was produced like Example 2. FIG.

Example 6 The photocurable resin of the film-like circuit connecting material used in Examples 1 to 4 was a urethane acrylate oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name: NK Oligo UA-512).
A connector was produced in the same manner as in Example 2, except that the acrylate monomer (A-TMM-3L) was used instead.

Comparative Example 1 Using the film-like circuit connecting materials used in Examples 1 to 4, the line width was 50 μm, the pitch was 100 μm, and the thickness was 18 μm.
circuit board (FP) having 500 copper circuits
C) and glass having a thin layer of indium oxide (ITO) of 0.2 μm (thickness: 1.1 mm, surface resistance: 20Ω /
□) and a constant heat type thermocompression bonding machine (made by our company)
The connection was made by heating and pressing at 130 ° C. and 2 MPa for 20 seconds, and the connection was made over a width of 2 mm. After a lapse of time, the pressure was released, and the connection was completed. At this time, after bonding the adhesive surface of the film-like circuit connection material on the ITO glass in advance,
Temporarily connected by heating and pressing at 70 ° C and 0.5 MPa for 5 seconds,
Thereafter, the fluororesin film was peeled off and connected to another FPC as an adherend. The connected body obtained by the above method was irradiated with ultraviolet rays from the ITO glass side as shown in FIG. At this time, the amount of ultraviolet irradiation was 2.0 J / cm ² .

Comparative Example 2 Using the film-like circuit connecting materials used in Examples 1-4, a line width of 50 μm, a pitch of 100 μm, and a thickness of 18 μm
circuit board (FP) having 500 copper circuits
C) and glass having a thin layer of indium oxide (ITO) of 0.2 μm (thickness: 1.1 mm, surface resistance: 20Ω /
□) using an ultraviolet irradiation combined thermocompression bonding apparatus (heating method: constant heat type, manufactured by Toray Engineering Co., Ltd.) at 130 ° C. and 2 MPa as shown in FIG.
The connection was made over a width of 2 mm by simultaneously performing heating and pressurization for 0 second and ultraviolet irradiation from the ITO glass side, and after a lapse of time, the pressure was released to produce a connected body. UV irradiation dose is 5.
It was set to 0 J / cm ² . At this time, after the adhesive surface of the film-like circuit connection material is pasted on the ITO glass in advance, it is temporarily connected by heating and pressing at 70 ° C. and 0.5 MPa for 5 seconds, and then the fluororesin film is peeled off. One of the adherends, the FPC, was connected.

Comparative Example 3 Using the film-like circuit connecting materials used in Examples 1 to 4, the line width was 50 μm, the pitch was 100 μm, and the thickness was 18 μm.
circuit board (FP) having 500 copper circuits
C) and glass having a thin layer of indium oxide (ITO) of 0.2 μm (thickness: 1.1 mm, surface resistance: 20Ω /
□) using an ultraviolet irradiation combined thermocompression bonding apparatus (heating method: constant heat type, manufactured by Toray Engineering Co., Ltd.) as shown in FIG.
The connection was made over a width of 2 mm by simultaneously applying heat and pressure for 2 seconds and irradiating ultraviolet rays from the ITO glass side, and after a lapse of time, the pressure was released to produce a connected body. UV irradiation dose is 0.6
J / cm ² . At this time, after bonding the adhesive surface of the film-like circuit connection material on the ITO glass in advance,
Temporarily connected by heating and pressing at 70 ° C and 0.5 MPa for 5 seconds,
Thereafter, the fluororesin film was peeled off and connected to another FPC as an adherend. In addition, at the time of connection for 5 seconds in FIG.
UV irradiation was started for a second. Five seconds after the start of heating and pressurization, only the heating step was completed.

Comparative Example 4 A phenoxy resin, which is a compounded resin of the film-like circuit connection material used in Examples 1 to 6 and Comparative Examples 1 to 3, and a liquid epoxy resin containing a microcapsule-type latent curing agent were solidified. The phenoxy resin 50 and the liquid epoxy resin 50 were blended in a weight ratio, and the conductive particles used in Example 1 were further blended and dispersed by 3% by volume, and applied to a 80 μm-thick fluororesin film using a coating apparatus. And 70 ° C, 1
By hot-air drying for 0 minutes, a film-like circuit connection material having an adhesive layer thickness of 20 μm was obtained. A flexible circuit board (FPC) having 500 copper circuits having a line width of 50 μm, a pitch of 100 μm, and a thickness of 18 μm, and a thin layer of indium oxide (ITO) having a thickness of 0.2 μm, using the film-like circuit connection material obtained by the above method. The glass (having a thickness of 1.1 mm and a surface resistance of 20 Ω / square) formed at 130 ° C. and 2M using a constant heat type thermocompression bonding apparatus (manufactured by our company).
Heat and pressurize for 20 seconds at Pa and connect over 2 mm width,
After a lapse of time, the pressure was released, and the connection was terminated. At this time, after the adhesive surface of the film-like circuit connection material is pasted on the ITO glass in advance, it is temporarily connected by heating and pressing at 70 ° C. and 0.5 MPa for 5 seconds, and then the fluororesin film is peeled off. One of the adherends, the FPC, was connected.

Comparative Example 5 The photo-curable resin was an epoxy acrylate oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name: NK Oligo EA-10)
20) and an acrylate monomer (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name: NK ester A-TMM-3L)
A benzophenone was used as a photoinitiator, and 4,4'-bisdiethylaminobenzophenone (trade name: EAB, manufactured by Hodogaya Chemical Industry Co., Ltd.) was used as a sensitizer. The sensitizer was mixed and used so as to be 5/1. A nickel layer having a thickness of 0.2 μm is provided on the surface of the particles having polystyrene as a core, and a gold layer having a thickness of 0.02 μm is provided outside the nickel layer. Particles were prepared. Using these, the photocurable resin 100, the photoinitiator 5, and the sensitizer 1 were blended so as to be a solid weight ratio, and the conductive particles were further blended and dispersed by 3% by volume to obtain a paste-like circuit connecting material. . A line width of 50 μm, a pitch of 100 μm, and a thickness of 18 were obtained using the paste-like circuit connection material obtained by the above method.
Flexible circuit board (F) with 500 μm copper circuits
PC) and glass (thickness: 1.1 mm, surface resistance: 20Ω) on which a thin layer of 0.2 μm indium oxide (ITO) was formed.
/ □) using a pulse-heat-type thermocompression bonding machine (manufactured by Nippon Avionics Co., Ltd.) to connect by heating and pressing at 130 ° C. and 2 MPa for 20 seconds over a width of 2 mm. Ended. At this time, an appropriate amount of a paste-like circuit connection material was applied on the ITO glass in advance, and connected to the FPC as the other adherend. The connected body obtained by the above method was irradiated with ultraviolet rays from the ITO glass side as shown in FIG. 2 using an ultraviolet irradiation device (conveyor moving type, manufactured by Ushio Inc.) to produce a connected body. At this time, the amount of ultraviolet irradiation was 2.0 J / cm ² .

The joints obtained in Examples 1 to 6 and Comparative Examples 1 to 5 were evaluated for initial resistance, adhesiveness, and circuit repairability. Regarding the initial resistance, after the circuit members were connected, the resistance value between adjacent circuits of the FPC including the above-mentioned connection portions was measured with a multimeter. The measurement current was 1 mA, and the resistance value was represented by an average (x + 3σ) of 150 points of resistance between adjacent circuits.
Regarding the adhesion to FPC and ITO glass, the adhesion was measured and evaluated by a 90-degree peeling method according to JIS-Z0237. The measuring device was Tensilon UTM-4 manufactured by Toyo Baldwin Co., Ltd. (peeling speed 50 mm / m
in, 25 ° C.).

The results are shown in Table 1 of FIG. 3 for all Examples and Comparative Examples. In Example 1, in which the heating and pressurizing and the ultraviolet irradiation were simultaneously started and completed, both the initial resistance and the adhesive force showed good values. In the case of Example 2,
The time required for heating and pressurizing is extremely short, 5 seconds, and only 3 seconds of UV irradiation is performed. However, after the completion of heating and pressing, 15 seconds of UV irradiation is performed to accelerate the curing reaction of the adhesive resin. Therefore, as compared with the first embodiment, it is possible to further suppress the thermal influence on the circuit member, and to obtain good initial connection characteristics. In addition, since the start of light irradiation was delayed by 2 seconds in order to give priority to ensuring the flow and conduction of the resin, better results were obtained in connection resistance than in Example 1. Example 3 is similar to Example 2, but since the pressurized state is maintained, it is possible to perform continuous 15-second ultraviolet irradiation with the circuit member fixed. In this respect, it is considered to be more advantageous than Example 2. In Example 4, heating and pressurizing for 10 seconds and irradiation of ultraviolet light for 8 seconds were performed at intervals of 2 seconds longer than those in Examples 2 and 3, and the ultraviolet light was 1.6 J / cm ^2, which is close to Example 1. Because of the amount of irradiation, a connector having good connection characteristics was obtained. Further, in Examples 5 and 6 in which the conductive particles and the photocurable resin were changed, a good connection state was obtained.

On the other hand, in the case of Comparative Example 1, which is a connection method without a cooling step, the adhesive strength is substantially the same as that of Examples 1 to 4 because the adhesive is sufficiently cured by the irradiation of ultraviolet rays. As shown in the figure, since the adhesive is not fixed due to the absence of the cooling step, the deformation of the conductive particles is not maintained, and the contact area with the circuit member is reduced, so that the initial resistance is significantly increased. Further, with respect to the first embodiment,
In Comparative Example 2, in which heating and pressurization and ultraviolet irradiation were simultaneously performed under the condition of a light irradiation amount of 5.0 J / cm ² , the curing reaction of the adhesive proceeded faster than the flow of the resin. Was not sufficiently contacted, resulting in poor conduction. In the case of Comparative Example 3, the curing of the adhesive resin was performed only by irradiation with ultraviolet light for 3 seconds, and the irradiation amount was only 0.6 J / cm ² , resulting in insufficient reaction. Therefore, the initial resistance was good. However, the initial adhesive strength was not good. In Comparative Example 4 using an adhesive mainly containing a thermosetting resin, 130
Under the connection conditions of 20 ° C. and 2 MPa for 20 seconds, the reaction rate of the adhesive was low, so that sufficient curing could not be obtained, the adhesive strength was considerably low, and the initial resistance was high. In the case of Comparative Example 5,
Since it does not contain a polymer resin that imparts film formability, it is disadvantageous in terms of handleability over a film-like material.

[0032]

According to the present invention, a light-curable resin and a film-like circuit connection material containing conductive particles as essential components are interposed in an adhesive, and light irradiation is performed simultaneously with or after heating and pressing. Therefore, the temperature required for connection can be lower than before, and excellent adhesive strength and good electrical conduction can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a connection method using a film-like circuit connection material of the present invention.

FIG. 2 is a cross-sectional view illustrating a connection method using the film-like circuit connection material of the present invention.

FIG. 3 is a table showing values of an initial resistance and an adhesive force in Examples and Comparative Examples.

[Explanation of symbols]

1: ITO glass, 2: conductive particles, 3: FPC circuit,
4 ... FPC base material, 5 ... adhesive, 6 ... light source, 7 ... light, 8 ...
Base, 9 ... Heating / pressing head,

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasushi Goto 48 Wadai, Tsukuba, Ibaraki Pref. Tsukuba Development Laboratory, Hitachi Chemical Co., Ltd.

Claims (7)

[Claims] At least one of the two circuit members has a light transmitting property, that is, a first circuit member having a first connection terminal and a second circuit member having a second connection terminal.
A first connection terminal and a second connection terminal are disposed to face each other, and a photocurable resin, a photoinitiator, and a molecular weight of 10, By interposing a film-like circuit connection material containing 000 or more polymer resin and conductive particles as essential components, and using a combination of heating and pressing for a certain period of time and light irradiation for a certain period of time, the first connection arranged opposite to each other is performed. A method for connecting electrodes, wherein a terminal and a second connection terminal are electrically connected. 2. The method for connecting electrodes according to claim 1, wherein the light irradiation is continued after the heating and pressurization is completed. 3. The method for connecting electrodes according to claim 1, wherein after the heating and pressurizing is completed, the light irradiation is continuously performed in a state where the two circuit members to be connected are pressurized. 4. The method for connecting electrodes according to claim 1, wherein the heating and pressurizing and the light irradiation are ended at the same time. 5. The electrode connection method according to claim 1, wherein an interval of one to several seconds is provided after the start of heating and pressurizing for a predetermined time, and light irradiation is started for a predetermined time after a predetermined interval. 6. The method for connecting electrodes according to claim 1, wherein the film-like circuit connecting material is an anisotropic conductive adhesive. 7. An electrode connection structure obtained by the electrode connection method according to claim 1, wherein the first circuit member and the second circuit member are electrically connected.