JP2883511B2 - Thermocompression connection member - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display (LC).
D), connection between connection terminals of a display such as electroluminescence (EL), light emitting diode (LED), electrochromic display (ECD), and plasma display and a circuit board on which a driving part is mounted, or between various electric circuit boards The present invention relates to a thermocompression-bondable connecting member used for performing

[0002]

2. Description of the Related Art Conventionally, thermocompression bonding members are LCD, E,
It is used for connection between a display such as L, LED, ECD, plasma display and the like and a rigid printed wiring board (PCB), a flexible printed circuit board (FPC) or the like, or a connection between the PCB and FPC. The thermocompression-bondable connection member is formed by screen-printing a conductive paste in a desired pattern 22 on an insulating flexible base material 21 as shown in FIG. Anisotropic conductive adhesive layer 24 and insulating resist layer 25 in which 23 is dispersed in an insulating adhesive
Is known (Japanese Patent Publication No. 55-38073, 58
-56996 publications). However, with the recent miniaturization and precision of electric and electronic devices, the pitch of connection terminals required for thermocompression-bondable connection members has been reduced to the order of 0.3 mm or 0.2 mm. In the type in which the conductive fine particles are dispersed in an insulating adhesive, the conductive fine particles are apt to be short-circuited by the conductive fine particles. Are formed to form a conductive line, and then an insulating adhesive layer is provided on the conductive line.
62-154746, etc.).

[0003] However, the conductive fine particles used here can easily deform the insulating flexible base material, the conductive lines and the insulating adhesive layer, and change the flow due to heating and pressurization during thermocompression bonding. Unable to follow, subject to the residual stress of the insulating flexible base material, conductive line and insulating adhesive under various environments that are placed after connection, it moves microscopically, poor conduction, high resistance value etc. Cause a significant effect on the reliability of the electrical connection. In order to avoid these problems, conductive fine particles having a core of a low-hardness insulating plastic elastic body and plated with a noble metal on the surface thereof have also been proposed.
Due to the difference in hardness between the noble metal and the insulating plastic elastic body during heating and pressurization during thermocompression bonding, micro cracks are generated on the surface, and the surface of the insulating plastic elastic body to which the electrolyte and ions are attached during plating is exposed However, there is also a fear that electrolytic corrosion occurs due to the electrolyte and ions. In addition, the use of precious metals increases the production cost and hinders mass production. Therefore, the present inventor has previously made the connection by directly contacting the connection terminals by mixing the conductive paste with the insulating fine particles without separately using the conductive particles in the electrical connection between the various connection terminals and the conductive lines. A thermocompression-bondable connecting member is proposed. As a result, an inexpensive thermocompression-bondable connection member having excellent electrical connection reliability can be obtained. However, although this thermocompression-bondable connection member greatly improves the reliability of electrical connection, it did not place importance on the screen printability of the conductive line. And the problem that the yield was extremely reduced occurred.

That is, the conductive lines of this thermocompression bonding member are provided by screen-printing a conductive paste obtained by adding a conductivity-imparting agent to an organic binder solution and further dispersing insulating fine particles. In normal screen printing, the conductive paste is cut immediately after printing by a wire having a wire diameter of about 10 to 30 μm constituting a screen plate and an intersection formed by these wires, and then filled into a screen opening, and filled in a screen opening. Then, they are connected alternately to form a desired conductive line. Thereafter, the screen separates, but at that time, a slip speed occurs between the screen mask and the conductive paste that form the screen opening,
Since the viscosity of the conductive paste in the portion in contact with the mask decreases, when the screen is separated, so-called sagging, which is wider by 30 to 50 μm than the width of the screen opening in the width direction of the conductive line, tends to occur. To prevent this, various measures have been taken to increase the viscosity and skewness of the conductive paste and increase the viscosity immediately after printing to suppress the flow.However, increasing the skewness is limited by the restrictions on the material of the conductive paste. In addition, if the viscosity of the conductive paste is increased, the conductive lines are likely to be blurred, and the conductive lines may be disconnected.
There is also a limit to this. Basically, a relatively low-viscosity conductive paste is used in consideration of printability, and the width of the screen opening is corrected to be at least about 30 to 50 μm in advance to provide a desired conductive line width. Had been taken.

However, as the connection pitch becomes finer in recent years, the width of the screen opening becomes narrower, the ratio of the correction becomes relatively large, the ratio of the area divided by the screen material also becomes large, Since the paste has poor screen passage properties, not only is it difficult to obtain electrically connected conductive lines, but also the pitch that can be handled by screen printing has been limited.
Therefore, among the configurations of the above-mentioned conventional thermocompression-bondable connection members, in the case where conductive fine particles or insulating fine particles are dispersed and blended in a conductive paste, the screen mesh is clogged by the conductive fine particles or insulating fine particles. As compared with the conductive paste in which fine particles were not dispersed and mixed, the screen passing property was reduced, and the correction of the opening was more fatal, the printability was poor, and the critical pitch was further reduced. Also, when the viscosity of the conductive paste is reduced to improve the screen printability, the surface of the insulating fine particles used for the thermocompression-bondable connecting member can easily repel the conductive paste, and as shown in FIG. Since the conductive lines 32 on the conductive base material 31 cannot cover the surface of the insulating fine particles 33, the insulating fine particles 33 are exposed and electrical connection cannot be made. Furthermore, with the recent miniaturization of the connection terminal pitch, the width of the conductive line has also become narrower, and in the prior art, the width of the conductive line is reduced as shown in FIG.
4A, a sufficient conductive line 43 is fixed around the insulating fine particles 42 on the insulating flexible base material 41. However, as shown in FIG. Insulating fine particles 42 in the conductive line 43 can be insulated under various environments after heating, pressurizing, or connecting during thermocompression bonding. It is easily detached or peeled from the flexible base material 41, and stable electrical connection cannot be obtained.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the screen printability and the connection stability of the conventional thermocompression bonding member. To provide an inexpensive thermocompression connection member having excellent electrical connection reliability without detachment and separation of insulating fine particles even in thermocompression connection members having fine connection terminals. Is to provide a thermocompression bonding member by screen printing with a pitch of 0.10 to 0.20 mm, which has not been industrially compatible conventionally.

[0007]

Means for Solving the Problems As a result of diligent studies, the present inventors have formed fine conductive lines with a conductive paste having poor screen printability in which insulating fine particles are dispersed and mixed, and ensured the surface of the insulating fine particles. Covered with conductive paste,
In addition, in order to firmly fix the insulating fine particles, attention is paid to the relationship between the amount of the solvent component contained in the conductive paste and the viscosity, and the time-dependent behavior of the conductive paste extruded from the screen opening. The leveling and viscosity of the conductive paste is achieved by simultaneously removing the solvent from the conductive paste within one second, at the same time that the conductive paste is provided on the printing material (provided with the solvent absorbing layer on the insulating base material). To form a conductive line having a line width approximately the same as the width of the screen opening, securely cover the surface of the insulating fine particles by thickening the conductive paste, and furthermore, the solvent absorbing layer and the insulating fine particles To obtain a thermocompression-bondable connection member that has clear and fine conductive lines by performing physical and chemical fixing between them and has excellent electrical connection stability. Successful are those were.

[0008] The thermocompression bonding member of the present invention is provided with a solvent absorbing layer for absorbing the solvent component in the conductive paste on one or both surfaces of the insulating flexible base material, and then forming a t / t on the solvent absorbing layer. 3
≦ r (where t is the thickness of the conductive line, r is the insulating fine particles
The particle size of the child, set a conductive line formed by the particle size of the insulating fine particles mixed with conductive paste represented by each represents) only, the connection terminal portion of at least the conductive lines to the formation of the insulating adhesive layer In particular, the conductive line is formed by r ≦ L (where r is an insulating fine particle
The particle size, L is the length of one side of the screen openings, but which is preferably being formed by screen printing of a conductive paste obtained by mixing the particle size of the insulating fine particles represented by each represents) is there. This thermocompression bonding member is shown in FIG.
In the drawing, reference numeral 1 denotes an insulating flexible base material, 2 denotes a solvent absorbing layer for absorbing a solvent component in a conductive paste provided on one or both surfaces thereof, and 3 denotes a solvent absorbing layer.
The conductive lines 5 formed by the conductive paste mixed with the insulating fine particles 4 having the above-mentioned particle size are insulating insulating layers formed on the connection terminal portions of the conductive lines 3. In the present invention, the insulating property indicates a volume resistivity of 10 ⁵ Ωcm or more,
Conductivity means that it is 10 ² Ω · cm or less.

As the insulating flexible substrate 1 used in the thermocompression bonding member of the present invention, for example, polyimide, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polycarbonate, polyphenylene sulfide, poly-1,4- For example, a heat-resistant polymer film having a thickness of 10 to 50 μm selected from cyclohexane dimethylene terephthalate, polyarylate, liquid crystal polymer and the like is used.

As the solvent absorbing layer 2 applied to the insulating flexible substrate, a conductive paste to be described later is passed through a screen opening to be printed (a solvent absorbing layer is provided on the insulating flexible substrate. ), The conductive paste must have the ability to absorb its solvent components, preferably instantaneously, before flowing, so that organic solvents having similar solubility parameters to the various solvents used in the preparation of the conductive paste. It is desirable to be a molecular substance, for example, a vinyl chloride resin, a vinyl acetate resin, a copolymer thereof, a styrene resin, an acrylic resin, a thermoplastic polyester, a thermoplastic polyurethane, a polybutadiene, a polyvinyl alcohol,
Polyvinyl butyral, polycarbonate resin, polyamide resin, phenolic resin, unsaturated polyester resin,
Synthetic rubbers such as isoprene rubber, butadiene rubber, butyl rubber, styrene butadiene rubber, butadiene acrylonitrile rubber, and thermoplastic elastomers such as styrene, polyester, and urethane are appropriately selected and used. These organic polymer substances may be any of thermoplastic and thermosetting materials, but they have the properties required for adhesion to an insulating flexible base material and thermocompression bonding members. sex,
Heat resistance of about 100-150 ° C during curing and drying of the conductive paste, it does not deform and dissolve due to heat absorbed and does not cause deformation, cracks, loosening, etc. due to absorbed solvent. Among them, vinyl chloride / vinyl acetate copolymers, acrylic resins, thermoplastic polyesters, thermoplastic polyurethanes, and epoxy resins are preferred among the above because they have good solvent properties. In addition, if necessary, isocyanates, amines, acid anhydrides, aldehydes, and the like, which are curing agents for crosslinking the above-mentioned polymer substance, may be added. A known curing accelerator such as a tertiary amine compound or an organometallic compound may be added, but it is desirable to avoid substances that promote migration of the conductive paste.

[0011] In addition to the affinity of the solvent component in the conductive paste with the above-described polymer substance, the solvent is to separate the cohesive force acting between the polymer substances and penetrate the polymer substance. However, the above-mentioned polymer substances are highly amorphous and have a molecular weight of 2,000 to 30,000, particularly 5,000 to 30,0.
It is preferably 00. In addition, from the viewpoint of improving the apparent heat resistance and suppressing the surface tackiness at the time of screen printing, a reinforcing filler such as dry silica, wet silica, silicate, and activated calcium carbonate is used in an amount of 0.1 to 100 parts by weight of the polymer substance.
It is desirable to add 10 parts by weight, thereby promoting separation of the plate and preventing the conductive paste from bleeding or dripping. Furthermore, heat resistance can be increased by three-dimensional crosslinking, but the molecular weight between crosslinking points is 2,000 or more, especially
It is desirable that the molecular weight is 20,000 or more for the above-mentioned reason. Therefore, as the high molecular substance, thermoplastic polyester and thermoplastic polyurethane are most preferable. These polymer substances are used after being dissolved in a general-purpose solvent similar to the solvent used for the insulating adhesive described later. If the thickness of the solvent absorbing layer is 0.5 μm or less, its solvent absorbing ability is insufficient,
100 μm
Since the above may cause a problem in terms of the flexibility required for the thermocompression bonding member, the thickness is 0.5 to
It is preferably 100 μm, particularly preferably 2 to 50 μm.

A conductive line 3 is formed in the solvent absorbing layer 2 by a conductive paste mixed with insulating fine particles 4. The conductive agent used in the conductive paste is a spherical shape having an outer diameter of 0.1 to 10 μm. Ag, Ag-plated Cu, Cu, Au, Ni, Pd, alloys thereof, such as granular, flake-like, plate-like, tree-like, dice-like, spongy, resin powder plated with one or more of these, Examples thereof include one using one or more of carbon black such as furnace black and channel black and graphite powder, and are dispersed and compounded in a ratio of 10 to 90% by weight with respect to an organic binder described later. For the insulating organic binder in which the conductivity imparting agent is dispersed, a resin composition such as a thermoplastic resin and a thermosetting resin is used. For this purpose, it is preferable to use a thermosetting resin. If necessary, a curing accelerator, a leveling agent, a dispersion stabilizer, an antifoaming agent, a thixotropic agent and the like may be appropriately added thereto.

As the insulating fine particles 4, various shapes such as spherical, granular, scale-like, tree-like, plate-like, dice-like, and spongy-like shapes are appropriately selected. In order to obtain a positive connection, a shape in which the conductive line contacts the opposing connection terminal at multiple points, for example,
More preferably, it is spongy or dendritic. The insulating fine particles may have a porous surface so as not to break through the conductive paste film at the time of forming the conductive line and at the time of thermocompression bonding, and the porous surface may thicken the conductive paste by the solvent absorbing layer. With the development, the organic binder component in the conductive paste is easily physicochemically adsorbed, so that very high adhesion can be obtained. Even more desirably, the difference between the SP value of the surface and that of the organic binder in the conductive paste should be within 2 or less, particularly 1 or less. As a result, chemical and molecular bonding strength and similarity can be obtained, the wettability between the surface of the insulating fine particles and the organic binder can be improved, and high adhesion can be obtained. Further, as described later, by providing a functional group that causes a chemical reaction with the surface of the solvent absorbing layer on the surface of the insulating fine particles, the insulating fine particles are firmly fixed to the solvent absorbing layer, and are used during thermocompression bonding or in an environment. In this method, the electrical connection reliability of the thermocompression bonding member can be improved without causing detachment and peeling, but the functional group is further firmly fixed by being chemically bonded to the organic binder of the conductive paste. May be obtained.

However, it cannot be used if the insulating fine particles are easily dissolved in the organic solvent in the conductive paste, and it is not preferable that the insulating fine particles easily absorb the organic solvent to cause expansion. Furthermore, the insulating fine particles are 80
Desirably, it has a heat resistance that does not easily melt at the time of thermocompression bonding at a temperature of ~ 200 ° C.
C. or higher, preferably 120.degree. C. or higher. From these required characteristics, it is desirable that the insulating fine particles be made of a resin, which can be controlled in shape and elasticity by a polymerization method and the like, and that the surface is made porous and a chemical reaction with the solvent absorbing layer is performed. This is because it is possible to add a functional group that causes the above, or to adjust the SP value of the surface by a known surface modification technique such as selection of the material of the insulating fine particles or introduction of an organic polar group. Resins satisfying such required properties include resins such as polystyrene, polyimide, polyacryl, polyester, polyurethane, polyamide, phenol, epoxy, polyolefin, and polyvinyl resins, and copolymers thereof. And synthetic rubbers of these elastomer resins, isoprene-based, butadiene-based, and the like. Among them, solvent resistance, elastic modulus, moldability, oil absorption, adhesion, etc. Acrylic resin is superior.

In the case where conductive lines are formed by dispersing and mixing such insulating fine particles in a conductive paste, screen printing is used to obtain a thickness sufficient to bury the insulating fine particles in one printing. Optimum, the insulating particles embedded and fixed in the conductive line formed by this,
To obtain a stable connection state, the conductive lines of the connection terminal portion of the area of 1 mm ² per number of particles 20 or more, particularly 50
What is necessary is just to make it more than pieces. If the number of particles is less than 20, the presence of particles is likely to be reduced when thermocompression bonding is performed, and sometimes there is no particle at the thermocompression bonding portion, so that a stable connection state is obtained especially in the case of a low pitch. You need to be careful. If the number of particles is excessively large, when the particles are provided by screen printing, plate clogging is likely to occur due to the particles, and the volume resistivity of the conductive paste may decrease, so that a stable resistance value may not be obtained. Therefore, it is desirable that the number of the insulating fine particles dispersed and mixed in the conductive paste is 2 to 50 parts by volume.

The screen material used for screen printing is a plain weave of an iron alloy such as stainless steel having a wire diameter of 10 to 40 μm.
A twilled or electroformed plate formed in a grid shape by nickel plating or the like, which is stretched over a rigid frame, is generally used.To form a precise pattern, the opening of an acrylic mask material, It is preferable to make the wire material thin so that the opening almost equal to the shape of the desired pattern is not closed at the intersection of the wire material and the wire material, and the gauze thickness Ts is inevitably reduced. The ratio of the aperture ratio φ to Ts is desirably 0.8 or more, and more desirably 1.5 or more. For this purpose, it is preferable to increase the strength of the wire rod and reduce the wire diameter without reducing the strength of the gauze and plate.
φ is desirably 35% or more, preferably 60% or more. As another screen material, a screen called a metal mask in which a thin nickel foil or the like is electrolytically laminated on a metal mesh such as stainless steel and a pattern is formed by etching may be used, but when performing printing at a low pitch, From the viewpoint of dimensional stability, it is preferable to use a material whose strength is not easily deformed by squeezing at the time of printing, and sufficient attention is required for printing.

The particle size r of the insulating fine particles dispersed and mixed in the conductive paste to be screen printed is determined by the line width T of the pattern.
It is determined by the relationship between c, the thickness t, and the length L of one side of the lattice-shaped opening of the printing plate. That is, if r is too small with respect to t, it is difficult to form the protruding portion and the connection stability is deteriorated, so that r ≧ (１ ／) t, preferably r ≧ t
When r is larger than Tc and L, it becomes physically difficult to form a pattern and a plate jam occurs at the time of printing. Therefore, r <Tc, r <L, preferably r <
(1/2) Tc is preferred. Usually, the thickness t of the conductive line is about 5 to 30 μm, and the length L of one side of the lattice-shaped opening of the printing plate differs depending on the screen mesh.
When forming fine conductive lines with a pitch of 0.4 mm or less, a plate of 250 mesh or more and up to about 500 mesh is often used, and L at this time is about 25 μm to 70 μm. The diameter r is optimally appropriately selected from the range of 5 to 70 μm, preferably 20 to 50 μm.

In order to firmly fix the desired pattern formed on the insulating flexible base material using these conductive paste and insulating fine particles to the opposing connection terminal, it is necessary to provide the insulating adhesive layer 5. There is. The insulating adhesive layer may be thermoplastic or thermosetting as long as it exhibits adhesiveness by heating, but thermoplastics are bonded at a relatively low temperature for a short time, Pot life is long,
Since thermosetting materials have high adhesive strength and excellent heat resistance, they may be appropriately selected according to the purpose of use. The main constituents of this insulating adhesive are ethylene-vinyl acetate copolymer, carboxyl-modified ethylene-
Vinyl acetate copolymer, ethylene-acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-isobutyl acrylate copolymer, polyamide, polyester, polymethyl methacrylate, polyvinyl ether, polyvinyl butyral, polyurethane, styrene-butylene-styrene (SBS) copolymer, carboxyl-modified SBS copolymer, styrene-isoprene-styrene (SIS) copolymer, styrene-ethylene-butylene-styrene (SEBS) copolymer, maleic acid-modified SE
BS copolymer, polybutadiene rubber, chloroprene rubber (CR), carboxyl-modified CR, styrene-butadiene rubber, isobutylene-isoprene copolymer, acrylonitrile-butadiene rubber (NBR), carboxyl-modified NBR, epoxy resin, silicone rubber (SR) It is obtained by one kind or a combination of two or more kinds selected from the above.

Rosin, as a tackifier,
Rosin derivatives, terpene resins, terpene-phenol copolymers, petroleum resins, cumarone-indene resins, styrene resins, isoprene resins, alkylphenol resins,
One or more kinds of phenol resins and the like are appropriately added. Also, a reactive auxiliary agent, a phenol resin as a crosslinking agent, polyols, isocyanates, melamine resin,
Urea resins, urotropins, amines, acid anhydrides, peroxides, metal oxides, organic acid metal salts such as chromium trifluoroacetate, alkoxides such as titanium, zirconia and aluminum, and organic metal compounds such as dibutyltin oxide , 2,2-diethoxyacetophenone, benzyl and the like, and sensitizers such as amines, phosphorus compounds, chlorine compounds and the like are appropriately selected and used as needed. Further, a curing agent, a vulcanizing agent, a control agent, a deterioration inhibitor, a heat-resistant additive, a heat conduction improver, a softener, a coloring agent, various coupling agents, a metal deactivator, and the like may be appropriately added to these. . Solvents that dissolve these include ester-based, ketone-based,
Ether ester type, chlorine type, ether type, alcohol type, hydrocarbon type and the like, for example, methyl acetate, ethyl acetate, isopropyl acetate, isobutyl acetate, butyl acetate,
Amyl acetate, methyl ethyl ketone, methyl isobutyl ketone, methyl isoamyl ketone, methyl amyl ketone,
Ethyl amyl ketone, isobutyl ketone, methoxymethyl pentanone, cyclohexanone, diacetone alcohol, methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, methoxybutyl acetate, methyl carbitol acetate, ethyl carbitol, dibutyl carbitol acetate, trichloroethane, Trichloroethylene, n-butyl ether, diisoamyl ether, n-
Butylphenyl ether, propylene oxide, furfural, isopropyl alcohol, isobutyl alcohol, amyl alcohol, cyclohexanol, benzene, toluene, xylene, isopropylbenzene, petroleum spirit, petroleum naphtha, etc. Is frequently used.

Further, as described above, the solvent absorbing layer is firmly fixed to the insulating fine particles in the conductive line to prevent the insulating fine particles from separating and peeling, and to enhance the stability of the electrical connection. The layer surface and the surface of the insulating fine particles preferably have two types of functional groups. Examples of these functional groups include unsaturated hydrocarbon groups such as vinyl groups, fluorinated carbon groups, and halogen groups. Sulfur oxide group, carboxyl group, organic acid anhydride group, ester group, hydroxyl group, methylol group, hydrogen sulfide group, cyano group, isocyanate group, amino group, epoxy group, silanol group, nitrile group, mercapto group, sulfone group, chlorosulfone And a diazo group. These functional groups may be present in the molecules of the organic polymer substance forming the solvent absorbing layer or the insulating fine particles, or a compound having these functional groups may be used as the organic material forming the solvent absorbing layer or the insulating fine particles. It may be used by blending with a polymer substance. The surface of the solvent absorbing layer or the surface of the insulating fine particles may be treated with a compound having such a functional group to impart a functional group. Among the combinations of these two types of functional groups, one has an isocyanate group, one has a carboxyl group, and the other has a long pot life in the thermocompression-bondable connecting member manufacturing process and a reaction by a conductive paste drying process. Most preferably, it has an active hydrogen group such as a hydroxyl group, a methylol group, an amino group or a silanol group. In any case, a curing accelerator may be appropriately present on the surfaces of the solvent absorbing layer and the insulating fine particles. In addition, the surface of the solvent absorbing layer may have minute pinholes of about 0.5 to 5 μm, which are engaged with the insulating fine particles and serve to physically fix the fine particles. Strengthen the bond between the solvent absorbing layer and the insulating fine particles.

In order to manufacture the thermocompression-bondable connecting member of the present invention using the above-mentioned members, roll coating, bar coating, knife coating, spray coating, dip coating, etc., are performed on the insulating flexible substrate 1. Coating method, screen printing, printing method such as gravure printing, etc., the solvent absorbing layer 2 is provided by a conventionally known method, and a conductive paste obtained by dispersing and blending insulating fine particles thereon is coated with a desired conductive line width. After forming a desired pattern by screen printing using the screen plate having the equivalent opening width, at least the insulating adhesive layer at the connection terminal portion of the pattern, a conventionally known method, that is, roll coating, Bar coating, knife coating, spray coating, screen printing,
It is performed by providing by gravure printing or the like.

[0022]

According to the thermocompression bonding member of the present invention, printing of a conductive paste having poor screen printability, in which insulating fine particles are dispersed and mixed in a conductive paste, is performed on an insulating flexible base material by a solvent absorbing layer. By using this method, we succeeded in suppressing sagging and bleeding of the conductive paste, which was a drawback of the conventional technology, and succeeded in reducing the viscosity of the conductive paste by increasing the width of the screen opening, thus facilitating printing and improving productivity. , Increase the yield,
Furthermore, 0.1 to 0.2 m, which was not industrially possible in the past
A thermocompression-bondable connection member having connection terminals of m pitches is provided. Further, the surface of the insulating fine particles is surely covered with the conductive line due to a sudden increase in viscosity immediately after the screen printing of the conductive paste, and the electrical connection after the thermocompression bonding is ensured. Further, the presence of the solvent absorbing layer also plays a role of firmly fixing the insulating fine particles. In other words, their surfaces are chemically bonded or physically fixed, and the insulating fine particles do not separate or peel off when the thermocompression bonding member is thermocompressed or in various environments after the connection, so that the electrical connection can be performed safely without separation. The connection is made. This is especially true when the connection terminal pitch is fine.
That is, it is effective when the number of conductive lines for fixing the insulating fine particles is small around the insulating particles.

[0023]

Next, the present invention will be described with reference to examples. 1) Production of conductive pastes A to C. As organic binder, molecular weight 20,000 to 25,000, hydroxyl value 6.0 KOHmg / g, acid value 1.0 KOHmg / g, solubility parameter
A mixture of a 9.2-fold saturated copolymerized polyester resin, a bimert of hexamethylene diisocyanate equivalent to 1.2 times the active hydrogen point of the polyester resin, and 0.01 part by weight of ethylenediamine as a catalyst was used.
３3 μm Ag powder as a conductivity-imparting agent, a leveling agent,
Dispersion stabilizers, defoamers, thixotropic agents each 1 part by weight were added and dissolved in carbitol ethyl acetate Torr, and dispersed mixture, compressive strength at 10% deformation is 2.6 kgf / mm ² porous nylon resin elastic Fine particles (average particle size about 30μm, spongy), same
Acrylic resin elastic fine particles of 3.4 kgf / mm ² (average particle diameter of about 30 μm, spherical) and 3.4 kgf / mm ² of acrylic resin elastic fine particles having a carboxyl group on the surface (average particle diameter of about 30 μm, spherical) Three kinds of conductive pastes A to C were produced by adding 40 parts by volume respectively. 2) Production of insulating adhesive solution For 100 parts by weight of carboxyl-modified NBR, 40 parts by weight of an alkylphenol-based tackifier, a deterioration inhibitor, a heat-resistant additive, and an amine-based silane coupling agent were added in an amount of 1 part by weight. It was dissolved in a mixed solvent of petroleum naphtha: butyl carbitol = 1: 1 to prepare a 35% by weight insulating adhesive solution.

3) Preparation of Solvent Absorbing Layer Solution Molecular weight 20,000 to 25,000 synthesized from terephthalic acid, isophthalic acid, sebacic acid, ethylene glycol and neopentyl glycol as raw materials, glass transition point 45 ° C., hydroxyl value
6.0KOHmg / g, acid value 1.0KOHmg / g, solubility parameter 9.2
100 parts by weight of a saturated copolymerized polyester resin was dissolved in toluene, and this was added to the active hydrogen point of the polyester resin.
10 parts by weight of a blocked isocyanate compound having a solid content of 85% and an isocyanate content of 12% by weight synthesized by blocking a 2.0-fold equivalent of hexamethylene diisocyanate bimeret trimer with methyl ethyl ketoxime, and uniformly dissolving and mixing, followed by curing. 0.1 parts by weight of triethylenediamine was added as an accelerator and mixed uniformly. 4) Production of thermocompression-bondable connecting member Next, the solvent absorption layer solution produced in the above 3) was dried on an insulating substrate made of a PET film having a thickness of 25 μm using a kiss coater to a coating thickness of 2 μm. The conductive pastes A, B, and C produced in the above 1) were applied on the entire surface so that the screen wire diameter: 16 μm and the gauze thickness: 35 μm
m, length L of one side of opening of gauze: 63 μm, aperture ratio: 65%,
Line pattern opening width: 0.2mm pitch conductive lines are formed using a reinforced stainless screen plate of 0.1mm, then dried and cured in an oven at 130 ° C for 5 hours, and then the whole surface is insulated by the above 2) The adhesive is applied with a bar coater so as to have a thickness of 15 μm after the solvent is removed, and dried, to form an insulating adhesive layer, cut into a desired size, and heat-bonded according to the present invention. A connection member was obtained.

5) Manufacture of Comparative Sample On a flexible insulating substrate made of a PET film having a thickness of 25 μm, the conductive pastes A, B, and C manufactured in the above 1) were screen wire diameter: 16 μm, thickness : 35 μm, length of one side of opening L: 63 μm, opening ratio: 65%, taking into account sagging, use a reinforced stainless screen plate with a line pattern opening width: 0.05 mm to form a 0.2 mm pitch pattern However, the printability of the conductive paste was poor and printing was impossible. Therefore, when a 0.3 mm pitch conductive line was formed on the same reinforced stainless screen with the line pattern opening width set to 0.1 mm, the conductive lines B and C were broken by the insulating fine particles of acrylic resin. Did not break through. Next, the insulating adhesive prepared in 2) above was applied to the entire surface to a thickness of 15 μm after the solvent was removed.
m, and then applied with a bar coater and dried to form an insulating adhesive layer and cut into desired dimensions to obtain a thermocompression-bondable connection member of a comparative example. The thus obtained thermocompression-bondable connection member was thermocompression-bonded to a connection terminal of a transparent conductive oxide film substrate (ITO) having a sheet resistivity of 30Ω at 140 ° C., 30 kg / cm ² for 12 seconds, and subjected to an impact test (120 ° C., 30 And -40 ° C, 30 minutes alternately.), The change in resistance between both connection terminals, and the time left in an environment of 85 ° C and 95% RH. The relationship with the change in the resistance value between the two connection terminals was measured, and the results are shown in Tables 1 and 2, respectively.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

According to the thermocompression bonding member of the present invention, a thermocompression bonding member having fine connection terminals can be easily obtained by using a conventional screen printing method, and a fine electric or electronic circuit or the like can be obtained. Even for connection terminals, the protruding portions are reliable without the insulating fine particles in the conductive lines breaking through the conductive line coating during printing, and without detaching or peeling off by heating and pressing operations. Can be connected to the opposite connection terminal, and the reliability of electrical conduction can be improved even under severe conditions such as outdoors in summer, in a car, and in hot water.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of a thermocompression bonding member of the present invention.

FIG. 2 is a longitudinal sectional view showing one embodiment of a conventional thermocompression bonding member.

FIG. 3 is an explanatory view showing a state in which a conductive paste containing insulating fine particles is screen-printed on a conventional insulating flexible base material.

FIGS. 4A and 4B are explanatory views showing a fixed state of insulating fine particles in a conventional thermocompression-bondable connecting member, wherein FIGS.

[Explanation of symbols]

1 ... insulating flexible base material 2 ... solvent absorption layer 3 ...
Conductive line, 4 ... insulating fine particles, 5 ... insulating adhesive layer.

Claims (2)

(57) [Claims] 1. The method according to claim 1, wherein one or both surfaces of the insulating flexible substrate are
Provide a solvent absorption layer to absorb the solvent component in the conductive paste
After that, t / 3 ≦ r (where t is the conductive line
And r is the particle size of the insulating fine particles, respectively.
Only set a conductive line formed by the particle size of the insulating fine particles mixed with conductive paste shown thermocompression bonding connection member, characterized in that the formation of the connection terminal portion of at least the conductive lines insulating adhesive layer. Wherein said conductive lines, r ≦ L (here r is absolutely
And L is a length of one side of the screen opening , and L is a length of one side of the screen opening. Thermocompression bonding member.