JPH1174313A - Method for connecting electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable connection at a low temperature and reduce thermal influence to a circuit member, by interposing a film-like circuit connection material containing photo-setting components and conductive particles between opposite first and the second connection terminals, and by electrically connecting the first and second connection terminals with each other by application of heat and pressure and light irradiation. SOLUTION: First and second connection terminals are oppositely placed, and a film-like circuit connection material containing photo-setting components and conductive particles is interposed between them. Then, the first and the second connection terminals are electrically connected with each other by application of heat and pressure and light irradiation. The film-like circuit connection material is mainly photo-cured, adhesive is melted and made to flow by the application of heat and pressure, and resin components in the vicinity of a part where the connection terminals and the conductive particles are in contact are sufficiently eliminated so that the conductive particles are sufficiently pressure-bonded between the connection terminals. Thus, heating may be performed to a temperature where the adhesive can flow, and a connection temperature of a circuit member can be lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit member such as a liquid crystal panel in which at least one of the two members has a light transmitting property. The present invention relates to a method of connecting electrodes using heating and pressurizing and light irradiation simultaneously or separately using a film-like circuit connecting material containing a photocurable component in order to obtain good circuit repairability when a defect occurs.

[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.

In connection with these adhesives, if an electrical connection is poor or an electronic component or a circuit becomes defective after the connection, the adhesive is removed with a solvent or the like after peeling off between the circuits and the like. Non-defective products are connected by an adhesive. In this case, the adhesive on the microcircuit or the electrode can be quickly and easily removed using a general-purpose solvent (for example, acetone, methyl ethyl ketone, toluene, ligroin, tetrahydrofuran, alcohol, etc.) without adversely affecting a good portion in the peripheral portion. is important. When the adhesive is a thermosetting substance or the like, a so-called epoxy release agent composed of, for example, methylene chloride and an acid is often used as a solvent.

[0004]

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, when the connection is performed under the condition that the temperature at the time of heating and pressurization 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. The likelihood increases. With regard to circuit repair, conventionally used thermosetting adhesives have been repaired using so-called epoxy strippers composed of, for example, methylene chloride and acid, and general-purpose solvents as the solvent. In the latter case, repair is not possible depending on the adhesive,
Alternatively, the time required for repair may be long, and the workability is reduced. The present invention has been made in view of such a situation, and it is possible to connect at a lower temperature than before, reduce the thermal effect on circuit members, and have a high reliability of the connection portion, and furthermore, when a connection failure occurs. An object of the present invention is to provide an electrode connecting method using a film-like circuit connecting member, which can be easily repaired in a short time by a general-purpose solvent.

[0005]

According to the method for connecting electrodes 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 connection member. A second circuit member having a terminal, a first connection terminal and a second connection terminal are arranged to face each other, and between the first connection terminal and the second connection terminal arranged opposite to each other, light curing is performed. A film-like circuit connection material containing a component and conductive particles is interposed, and heat and pressure and light irradiation are performed to electrically connect the first connection terminal and the second connection terminal arranged opposite to each other. And As the film-like circuit connection material, a photocurable resin, a polymer resin having a molecular weight of 10,000 or more and conductive particles are used as essential components, and a coupling agent can be further contained. In the present invention, the film-like circuit connecting material is melted and flows by heating and pressurizing and light irradiation, and the primary connection is performed under such a condition that conduction between the circuit members by the conductive particles is ensured. Then, the light irradiation is interrupted, and after a lapse of a certain time by the conduction test, the electrodes are connected by performing sufficient curing again by light irradiation. In addition, the heating and pressurization causes the film-like circuit connection material to melt and flow, and the primary connection is performed under conditions that ensure conduction between circuit members due to the conductive particles. After a certain period of time, the electrodes are connected by performing sufficient curing by light irradiation. After the primary connection is made, the film is cooled to a temperature lower than the glass transition point of the film-like circuit connection material, and then the heating and pressurizing and the light irradiation can be interrupted. The heating and pressurization and the light irradiation can be started at the same time, or an interval of 1 to several seconds is provided between the heating and pressurization and the light irradiation, and the light irradiation can be performed after the start of the heating and pressurization. The method for connecting electrodes according to claim 4. The thickness of the circuit member having optical transparency is 1.
It is preferably 2 mm or less, and the compression elastic modulus of the conductive particles is preferably 1,000 to 10,000 MPa.

According to the electrode connection method of the present invention, at least one of the two circuit members has optical transparency, that is, a first circuit member having a first connection terminal and a second circuit member having a second connection terminal. The circuit member, the first connection terminal and the second connection terminal are arranged to face each other, between the first connection terminal and the second connection terminal arranged opposite to each other, the photocurable component and the conductive particles By interposing a film-like circuit connection material to be contained, by using both heating and pressurization and light irradiation, the first connection terminal and the second connection terminal arranged opposite to each other are electrically connected, The composition component of the film-like circuit connection material is a photocurable resin and has a molecular weight of 10,000.
It is characterized in that the above-mentioned polymer resin and conductive particles are essential components. In addition, the film-like circuit connection material melts and flows by heating and pressing and light irradiation,
After the primary connection is performed under the condition that the conduction between the circuit members by the conductive particles is ensured, the heating and pressurization and the light irradiation are interrupted, and after a certain period of time such as a continuity test, sufficient light irradiation alone is sufficient. It is characterized by performing curing.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, as a circuit member, a chip component such as a semiconductor chip, a resistor chip and a capacitor chip, a substrate such as a printed board, a liquid crystal panel and the like are used. These circuit members are usually provided with a large number of connection terminals (in some cases, a single terminal may be provided), and at least one of the circuit members having optical transparency is provided on the circuit members. At least one part of the connection terminals is opposed to each other, an adhesive is interposed between the opposed connection terminals, and heated and pressed and irradiated with light to electrically connect the opposed connection terminals to form a connection body. At this time, the thickness of the light-transmitting circuit member is 1.2 mm.
The following are preferable in terms of light transmission. In addition, by making the form of the circuit connection material containing the photocurable resin into a film form, the handleability is superior to that of the conventional paste-like circuit connection material, and the connection thickness can be made uniform. It is advantageous. 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.

In the method according to the first aspect, the first connection terminal and the second connection terminal are arranged to face each other, and a film-like circuit connection material containing a photocurable component and conductive particles is interposed therebetween. The first connection terminal and the second connection terminal arranged opposite to each other are electrically connected by heating and 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. And 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 80-1
Within the range of 40 ° 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. In addition, when heating and pressurization and light irradiation are performed simultaneously, it is necessary to adjust melt fluidity and 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 and the resin Is performed sufficiently, so that heating and pressurization and light irradiation can be performed at the same time (claim 7). In the case of a light irradiation device using a light source having a large amount of light, an interval of one to several seconds is provided between the heating and pressurizing step and the light irradiation step in order to give priority to the flow of the resin. Irradiation can also be performed (claim 8). 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.

According to a second aspect of the present invention, a photocurable film-like circuit connection material is formed by using a photocurable resin, a polymer resin having a molecular weight of 10,000 or more and conductive particles as essential components. It is possible to provide. This is because most polymer resins having a molecular weight of 10,000 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.

[0010] Using a photo-curable resin, a polymer resin having a molecular weight of 10,000 or more, and a film-like circuit connection material containing conductive particles as essential components, the film-like circuit connection material is melted by heating and pressing and light irradiation. After the primary connection is made under the condition that the conduction between the circuit members by the flowing and the conductive particles is ensured, the heating and pressurization and the light irradiation are interrupted, and after a certain time elapses by the continuity test, the light irradiation is performed again. The method according to claim 4, wherein the film-like circuit connecting material is melted and flows by only the heating and pressurizing, and the conduction between the circuit members by the conductive particles is ensured only by the heating and pressurizing. The method according to claim 4, wherein after the primary connection is performed under the conditions, the heating and pressurizing are interrupted, and after a certain period of time such as a conduction test or the like, sufficient curing is performed only by light irradiation. It is important that the conductive particles are sufficiently deformed and that the state is maintained even after the completion of the heating and pressurizing. Therefore, the minimum necessary heating and pressurizing and light irradiation to ensure conduction are performed. Should be performed. At this time, the heating and pressurizing conditions are as follows.
g or more, or a condition that can be heated 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, but is preferably from 80 to 140. It is preferably within the range of ° C. The pressure varies depending on the type of the circuit member. However, it is preferable that the pressure does not adversely affect the circuit member and that the conductive particles can be deformed. Conduct a continuity test at the time of the primary connection.If the initial resistance is not high and continuity cannot be secured, the circuit members will be peeled off and the circuit will be repaired, but the curing of the adhesive will still proceed sufficiently Therefore, the adhesive can be removed with a general-purpose solvent in a very short time. Conversely, if conduction is ensured, the uncured adhesive may be sufficiently cured by light irradiation.

The method according to claim 5, wherein after the primary connection is made, the film-like circuit connection material is cooled to Tg or less, and then the heating and pressurizing and the light irradiation are interrupted. In order to cool the heating / pressing head of the thermocompression bonding device just before the pressure is released, whether the adhesive is completely uncured,
Even when the curing reaction hardly progresses, the cooling step lowers the temperature of the adhesive to Tg or lower, and the melt viscosity also rises again. Therefore, the restoration of the conductive particles when the pressure is released is suppressed, and the connection thickness is reduced. Since it is kept, conduction can be ensured. Conversely, when the adhesive is in the same state, when the cooling step is not performed, the adhesive temperature is equal to or higher than Tg and the melt viscosity is low, so that the connection thickness increases upon release of pressure, and the circuit Many air bubbles are generated in between, causing a decrease in adhesiveness. In addition, since the conductive particles are restored by the increase in the connection thickness and the contact area with the circuit is reduced, the initial resistance is significantly increased, and conduction cannot be secured.

The film-like circuit connecting material used in the present invention comprises an adhesive component obtained by mixing a photocurable resin with a solid polymer resin for imparting a film-forming property, and conductive particles. Is formed into a film-like shape, thereby improving the handleability when connecting circuit members.

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.

As the light used for curing, generally used ultraviolet light can be used, and it 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 0.1% with respect to 100 volumes of the adhesive component.
Depending on the application, it is used properly in a wide range of -30% by volume. In order to prevent a short circuit or the like in an adjacent circuit due to excessive conductive particles, the content is more preferably 0.2 to 15% by volume. At this time, the average particle size of the conductive particles depends on the amount added, but is 1
It is more preferable that the thickness be 15 μm. In addition, the compression elastic modulus of the conductive particles, when heating and pressurizing and light irradiation is interrupted,
In order to suppress the restoration of particles due to the elasticity of the adhesive, 10
It is preferable to be in the range of 00 to 10000 MPa.

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, propylisoethoxytriethoxysilane and the like are available, but γ-methacryloxypropyltrimethoxysilane is more preferably used to enhance the reactivity with the photocurable resin.

[0018]

【Example】

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 rays irradiated on the adhesive (hereinafter referred to as ultraviolet irradiation amount) is 1.3 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 Using the film-like circuit connection material obtained in Example 1, 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 /
□) at 130 ° C. as shown in FIG. 2 using a pulse heat type thermocompression bonding device (manufactured by Nippon Avionics Co., Ltd.).
After heating and pressurizing at 2 MPa for 20 seconds and connecting over a width of 2 mm, the pressure was released after cooling the heating head to about 50 ° C. by air, and the connection was terminated. At this time,
After bonding the adhesive surface of the film-like circuit connection material 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 to remove the other coating. It was connected to the FPC that was the wearing body.
As shown in FIG. 3, ITO was applied to the connection body obtained by the above method using an ultraviolet irradiation device (manufactured by Ushio Inc.).
Ultraviolet rays were irradiated from the glass side to produce a connector. At this time, the amount of ultraviolet irradiation was 1.3 J / cm ² .

Example 3 Using the film-like circuit connecting material obtained in Example 1, 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. The amount of UV irradiation is 1.
3 mJ / 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. After the connection according to the above method, a continuity test such as initial connection resistance is performed, and after the test, heating and pressurization at 130 ° C. and 2 MPa for 10 seconds and ultraviolet irradiation at a dose of 1.3 J / cm ² are simultaneously performed using the same device. After a lapse of time, the pressure was released to produce a connected body. After the connection according to the above method, a continuity test such as initial connection resistance is performed, and after the test, heating and pressurization at 130 ° C. and 2 MPa for 10 seconds and ultraviolet irradiation at a dose of 1.3 J / cm ² are simultaneously performed using the same device. After a lapse of time, the pressure was released to produce a connected body.

Example 4 Using the film-like circuit connection material obtained in Example 1, 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.) 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 amount is 1.3
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. After the connection according to the above method, as a result of conducting a continuity test such as initial connection resistance, it was confirmed that the continuity was defective.
Using the same apparatus as in Example 1, heating and pressurization at 130 ° C. and 2 MPa for 20 seconds and UV irradiation at a dose of 1.3 J / cm ² were simultaneously performed, and after a lapse of time, the pressure was released to produce a connected body. .

Example 5 Using the film-like circuit connecting material obtained in Example 1, 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.) 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. At the time of connection for 10 seconds in FIG.
Irradiation of ultraviolet light for 2 seconds was started, and after 10 seconds of heating and pressurizing, the two steps were simultaneously completed.

Example 6 The conductive particles of the film-like circuit connecting material used in Example 1 were replaced with nickel particles having an average particle diameter of 5 μm (trade name DSP3101, specific gravity 8.5, manufactured by Daido Special Co., Ltd.). Other than that produced the connection body like Example 1. FIG.

Example 7 The photocurable resin of the film-like circuit connecting material used in Example 1 was a urethane acrylate oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name: NK Oligo UA-512) and an acrylate monomer (A- A connection body was produced in the same manner as in Example 1 except that TMM-3L) was used instead.

Comparative Example 1 Using the film-like circuit connecting material used in Example 1,
Flexible circuit board (FPC) having 500 copper circuits with a line width of 50 μm, a pitch of 100 μm, and a thickness of 18 μm
And glass on which a thin layer of indium oxide (ITO) of 0.2 μm is formed (thickness: 1.1 mm, surface resistance: 20Ω / □)
Is heated and pressed at 130 ° C. and 2 MPa for 20 seconds using a constant heat type thermocompression bonding device (manufactured by our company) to obtain a width of 2 m.
m, and after a lapse of time, the pressure was released, and the connection was terminated. At this time, beforehand on the ITO glass,
After attaching the adhesive surface of the film-like circuit connection material, 70
Temporary connection was performed by heating and pressing at 0.5 ° C. and 0.5 MPa for 5 seconds, and then 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. 3 using the ultraviolet irradiation apparatus used in Example 2 to produce a connected body. At this time, the irradiation amount of ultraviolet light was 1.3 J / cm ^2.
And

Comparative Example 2 Using the film-like circuit connecting material used in Example 1,
Flexible circuit board (FPC) having 500 copper circuits with a line width of 50 μm, a pitch of 100 μm, and a thickness of 18 μm
And glass on which a thin layer of indium oxide (ITO) of 0.2 μm is formed (thickness: 1.1 mm, surface resistance: 20Ω / □)
As shown in FIG. 1, heat and pressure were applied at 130 ° C. and 2 MPa for 10 seconds using a thermocompression bonding apparatus combined with ultraviolet irradiation (heating method: constant heat type, manufactured by Toray Engineering Co., Ltd.), and pressure was applied from the ITO glass side. Ultraviolet irradiation was performed at the same time to connect over a width of 2 mm, and after a lapse of time, the pressure was released to produce a connected body. UV irradiation dose is 5.0J /
cm ² . At this time, beforehand on the ITO glass,
After attaching the adhesive surface of the film-like circuit connection material, 70
Temporary connection was performed by heating and pressing at 0.5 ° C. and 0.5 MPa for 5 seconds, and then the fluororesin film was peeled off and connected to another FPC as an adherend.

Comparative Example 3 A phenoxy resin, which is a compounded resin of the film-like circuit connecting material used in Examples 1 to 6 and Comparative Examples 1 and 2, 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 4 A photocurable 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 using an ultraviolet irradiation device (manufactured by Ushio Inc.) to produce a connected body as shown in FIG. At this time, the amount of ultraviolet irradiation was 1.3 J / cm ² .

The connection bodies obtained in Examples 1 to 7 and Comparative Examples 1 to 4 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.). Regarding the circuit repairability, the FPC at the connection portion was peeled off from the ITO glass,
The adhesive remaining on the TO glass and having a fixed area (20 × 2 mm) was wiped off with a cotton swab impregnated with acetone, and evaluated by the time required to finish.

The results are shown in Table 1 of FIG. 4 for all Examples and Comparative Examples. In Example 1 in which the heating and pressurizing and the ultraviolet irradiation were performed simultaneously, both the initial resistance and the adhesive strength showed good values. In Example 2 in which heating and pressurization and ultraviolet irradiation were performed simultaneously using separate devices and the connection was sufficiently cooled before the pressure was released, the increase in connection thickness was suppressed, resulting in low connection resistance. ing. Also, in the case of Example 3 in which the connection time is shorter than those in Example 1 and Example 2 of 10 seconds, the restoration of the conductive particles is suppressed because the curing reaction of the adhesive is relatively progressing. Although there was no problem with regard to the connection resistance, as a result of irradiation with ultraviolet rays for further accelerating the curing reaction, a good value was also exhibited for the adhesive strength. In the case of Example 4, since heating and pressurization and ultraviolet irradiation were performed for only 3 seconds, the deformation and curing reaction of the conductive particles were insufficient, and the initial resistance was increased. Then, when the circuit was repaired by removing the FPC, the repair could be performed in a very short time because the adhesive was not cured. This makes it possible to quickly reconnect the circuit. Furthermore, in the case of Example 5 in which the amount of ultraviolet irradiation was increased to 5.0 J / cm ² , the start of light irradiation was delayed by 2 seconds in order to give priority to ensuring the flow and conduction of the resin, resulting in good connection characteristics. Was. In Examples 6 and 7 in which the conductive particles and the photocurable resin were changed, a good connection state was also obtained. On the other hand, in the case of Comparative Example 1, which is a connection method not provided with a cooling step, the adhesive force shows substantially the same value as in Examples 1 to 4 because the adhesive is sufficiently cured by ultraviolet irradiation. However, since the adhesive is not fixed because there is no 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. In Comparative Example 2 in which heating and pressurization and UV irradiation were simultaneously performed under the condition of a light irradiation amount of 5.0 J / cm ² , the curing reaction of the adhesive progressed faster than the flow of the resin. As a result, the conductive particles did not sufficiently contact the circuit member, resulting in poor conduction. Furthermore, in Comparative Example 3 in which an adhesive containing a thermosetting resin as a main component was used, the reaction rate of the adhesive was low under the connection conditions of 130 ° C., 2 MPa, and 20 seconds, so that sufficient curing could not be obtained. However, the adhesive strength was considerably reduced and the initial resistance was also increased. Comparative Example 4 does not contain a polymer resin that imparts film forming properties, and thus has a higher primary conductivity than Example 2 in which conduction is ensured when a film-like circuit connection material is used. It is inferior in securing conduction in the cooling process at the time of connection, and is more disadvantageous in terms of handleability than the film-like material.

[0031]

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. By connecting circuit members, the temperature required for connection can be lower than before, and after heating and pressurizing, the connecting body is cooled just before the pressure is released, thus restoring the conductive particles and increasing the connection thickness. It is possible to obtain excellent adhesive strength and good electrical conduction. Further, when a connection failure occurs at the time of initial connection, the curing reaction of the resin has not progressed so much, so that the circuit can be easily repaired with a general-purpose solvent.

[Brief description of the drawings]

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

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

FIG. 3 is a cross-sectional view illustrating a connection method (comparative example) using a film-like circuit connection material.

FIG. 4 is a table showing evaluation results of initial resistance, adhesiveness, and circuit repairability of the connection bodies obtained in Examples 1 to 7 and Comparative Examples 1 to 4.

[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, 10 ... Air inlet for cooling

Claims (10)

[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 connection terminal and a second connection terminal are arranged to face each other, and a film-shaped circuit connection material containing a photocurable component and conductive particles between the first connection terminal and the second connection terminal arranged opposite to each other. And heating and pressurizing and irradiating light to electrically connect the first connection terminal and the second connection terminal arranged opposite to each other. 2. The method for connecting electrodes according to claim 1, wherein the film-like circuit connection material comprises a photocurable resin, a polymer resin having a molecular weight of 10,000 or more, and conductive particles as essential components. 3. The method for connecting electrodes according to claim 1, wherein the film-like circuit connection material contains a coupling agent. 4. A film-like circuit connecting material is melted and flows by heating and pressurizing and light irradiation, and a primary connection is made under such a condition that conduction between circuit members by conductive particles is ensured. The electrode connection method according to any one of claims 1 to 3, wherein the pressure and light irradiation are interrupted, and after a lapse of a predetermined time by a conduction test, sufficient curing is performed again by light irradiation. 5. The primary connection is performed under such a condition that the film-like circuit connecting material melts and flows by the heating and pressurization, and the conduction between the circuit members by the conductive particles is ensured, and then the heating and pressurizing is interrupted. 4. A sufficient curing is performed by light irradiation after a lapse of a predetermined time by a continuity test.
The electrode connection method described in each item. 6. The method for connecting electrodes according to claim 4, wherein after the primary connection is performed, cooling is performed to a temperature equal to or lower than the glass transition point of the film-like circuit connection material, and then heating and pressurization and light irradiation are interrupted. 7. The method for connecting electrodes according to claim 4, wherein heating and pressurizing and light irradiation are started simultaneously. 8. The electrode connection method according to claim 4, wherein an interval of one to several seconds is provided between the heating and pressurizing and the light irradiation, and the light irradiation is performed after the start of the heating and pressurizing. 9. A light transmitting circuit member having a thickness of 1.
The electrode connection method according to any one of claims 1 to 8, wherein the distance is 2 mm or less. 10. The conductive particles have a compression modulus of 1000 to 1000.
The electrode connection method according to any one of claims 1 to 8, wherein the pressure is 10,000 MPa.