JP2000011760A - Anisotropic conductive composition and manufacture of anisotropic conductive member using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate deficiency due to disconnection or a short circuit caused by the contact of conductive particles with one another even in the case of large gap dispersion or high-precision connection by uniformly diffusing the conductive particles and thermally fusible insulating particles in an insulating liquid adhesive. SOLUTION: Conductive particles are a metal particle such as Ni, Ag, Au or Pd, or a particle made by plating Au or the like on a plastic particle, and has a particle diameter of 3-10 μm. An epoxy resin, a polyester resin or the like is used for insulating particles. For the average particle diameter of the insulating particles in a diffused state, 25-150% of that of the conductive particles is suitable, and even if the conductive particles are included, they are deformed by fusing so that they do not hinder the gap adjusting capability of the conductive particles. An epoxy resin or an acrylic resin is included as an insulating adhesive. Even if there is gap dispersion around 2-7 μm in the height of bumps at the time of bonding, the insulating particles absorb it after fusing, so that the conduction of the conductive particles is not hindered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an anisotropic conductive adhesive composition and a method for producing an anisotropic conductive member using the same.

[0002]

2. Description of the Related Art An anisotropic conductive adhesive composition is usually used as an anisotropic conductive film (ACF) as a liquid crystal panel and a tape carrier package (TCP), a TCP and a printed wiring board (PWB), or a liquid crystal panel and a flip chip. (FC)
Are used for the electrical and mechanical joining of different kinds of electronic members at the same time. ACF is usually processed in a tape shape, and it has an easy-to-use surface.
Since the shaped tape is thermocompression-bonded onto an electrode pattern having irregularities, voids and adhesive defects are likely to occur, which may cause a problem at the time of solder reflow after mounting or cause a reduction in reliability.

Recently, an anisotropic conductive paste (ACP) in which conductive particles are uniformly dispersed in a liquid adhesive has also been developed. Since the ACP is in a liquid state, the above-mentioned problems of the ACF can be avoided. However, since the conductive particles are in a state of being dispersed in the liquid, there is a problem that the conductive particles settle during storage,
There is a problem that the conductive particles are fluidized by the heat and pressure at the time of connection and the particles are locally aggregated, and as a result, bonding defects such as disconnection and short-circuit are more likely to occur than in the case of the ACF.

As countermeasures against this, the specific gravity and particle size of the conductive particles are controlled, elastic insulating particles are used together, the viscosity of the dispersed binder resin is adjusted to prevent sedimentation, There is known a method of providing an insulating layer outside conductive particles to prevent a short circuit.

[0005]

However, as the connection becomes finer, disconnection and short-circuit due to uneven distribution of the conductive particles are liable to occur, and metal particles are added to the conductive particles to reduce the connection resistance. When used, there was a problem that the dispersibility of the conductive particles deteriorated during storage. Also, elastic insulating particles such as silicone and rubber have a high linear expansion force.
There has been a problem that the connection resistance at high temperature becomes unstable and the pressure at the time of connection cannot be efficiently applied to the conductive particles.

In the case of PWB, the step of the pad is 5 μm.
m, there is a large gap variation of up to 7 μm including the height variation of the bumps. On the other hand, with the recent increase in definition, conductive particles tend to be miniaturized, and it is difficult to use insulating particles that inhibit the gap adjusting ability of the conductive particles. Therefore, it has become difficult to prevent short-circuiting due to contact between the conductive particles during connection.

The present invention has an anisotropic conductive adhesive which has such a gap adjusting ability and does not cause a problem such as disconnection or short circuit due to contact between conductive particles even in a case of a high-definition connection even in a case of a high-definition connection. It is intended to provide a composition.

[0008]

In the anisotropic conductive composition of the present invention, conductive particles and heat-fusible insulating particles are uniformly dispersed in an insulating liquid adhesive.

The conductive particles are metal particles of Ni, Ag, Au, Pd, or the like, or plastic particles obtained by plating a metal surface with Au or the like, and have a particle diameter of 3 to 10 μm.

As the insulating particles, epoxy resins, polyester resins, ethylene-vinyl acetate copolymers, styrene-butadiene copolymers and their hydrides (SEB
S), an ethylene-acrylate copolymer, particularly an epoxy resin is preferably used. The insulating particles are produced by a known method such as a spray drying method or a submerged drying method. These particles are melted and deformed in the vicinity of the melting point of the resin by heating and pressing during bonding.

The average particle size of the insulating particles in the dispersed state is suitably 25 to 150% of the particle size of the conductive particles. Even if particles having a particle size larger than the conductive particles are included, they are melted and deformed. Therefore, the gap adjusting ability of the conductive particles is not hindered. Insulating particles also control the viscosity of the liquid, prevent sedimentation of conductive particles with a large specific gravity, maintain uniformity of dispersion, and prevent particles from forming aggregates. I have.

The insulating adhesive includes an epoxy resin or an acrylic resin, and the acrylic resin is a difunctional base resin of a bifunctional or trifunctional or higher polyfunctional (meth) acrylate compound and a dilution of a monofunctional (meth) acrylate compound. A composition comprising an agent, a thermal polymerization initiator and a thermal polymerization catalyst is used. As the base resin, an epoxy acrylate resin obtained by modifying an epoxy resin, a urethane acrylate resin obtained by modifying a polyol or a polyester polyol with urethane acrylate, and the like are known, and an epoxy acrylate resin is suitable from the viewpoint of adhesiveness and durability. The thermal polymerization initiator and the thermal polymerization catalyst are used in various combinations according to the curing conditions. As the thermal polymerization initiator, organic peroxides such as cumene hydroperoxide and t-butyl peroxyhexanoate, and as the thermal polymerization catalyst,
Transition metal complexes such as iron, cobalt, and copper are used.

In the present invention, when the above-mentioned acrylic resin is used as the insulating adhesive, when it is necessary to repair the IC after mounting, the IC chip is easily peeled off from the substrate by heating the IC chip at about 250 ° C. Therefore, there is an advantage that the substrate can be recycled because the IC can be mounted again. On the other hand, in the case of a conventional thermosetting ACF insulating adhesive, an epoxy resin is used, and the durability such as heat resistance and moisture resistance is excellent, but repair is difficult, and recycling of the substrate is difficult. Can not.

The anisotropically conductive composition of the present invention is kneaded, and a composition in which conductive particles and insulating particles are uniformly dispersed is applied to an electrical joint, and the joint is thermally compressed to anisotropically. When a conductive member is manufactured, the conductive particles and the insulating particles are uniformly arranged at the joining point at the particle diameter level, and in the pressure direction, conduction between the electronic components is obtained only through the conductive particles. In the direction, the insulating particles are melted and exhibit insulating properties, so that the conductive particles do not fluidize and move or aggregate at the time of joining. Further, the insulating particles are cured at a heating temperature after the electrical bonding, and are converted into a cured resin, thereby preventing a decrease in reliability due to stress.

In addition, even if there is a gap variation of about 2 to 7 μm in the height of the bump at the time of bonding, the insulating particles are melted and the gap variation is absorbed, so that conduction of the conductive particles is not hindered. .

[0016]

EXAMPLES The composition of the anisotropic conductive composition of the present invention used in the following examples is as follows.

As the conductive particles (1), 6 parts by weight of Micropearl AU-2065 (manufactured by Sekisui Fine Chemical) was used. Au-plated divinylbenzene-styrene crosslinked copolymer beads with an average particle size of 6.5 μm

As the insulating particles (2), 10 parts by weight of epoxy resin particles produced by the following in-liquid drying method were used. 30 parts by weight of Epicron No. 1050 (epoxy equivalent: 480; manufactured by Dainippon Ink), 30 parts by weight of Epicron No. 850S (epoxy equivalent: 185; manufactured by Dainippon Ink) and cresol novolak resin PS-6865 (phenol number: 122; A resin solution was prepared by dissolving 14 parts by weight of Gunei Chemical Industry in 200 ml of toluene: methylethylketone (50:50). Separately, 15 parts by weight of polyvinyl alcohol No. 500 (manufactured by Wako Pure Chemical) as a protective colloid in 300 ml of water, Nonion NS-230 (manufactured by NOF Corporation)
1.5 parts by weight were dissolved to prepare an emulsifying medium. This emulsifying medium was heated to 45 ° C. and 8,000 with a homogenizer.
While stirring by rotation, the above resin solution was added little by little at 45 ° C., and after the addition was completed, stirring was continued for 15 minutes to complete emulsification and dispersion. The emulsified dispersion was placed in a vacuum desolvation apparatus, and the solvent in the emulsified dispersion was completely removed at 50 ° C. under reduced pressure. Thereafter, 11 parts by weight of anhydrous piperazine was added to 500 ml of water.
Add the amine curing liquid dissolved in
For 5 hours, and the epoxy resin was semi-cured (50 to 60% in epoxy equivalent) to complete the particle formation. The obtained particles had a particle size distribution of 1 to 20 μm, and this was subjected to classification treatment with water to adjust the particle size distribution to 3 to 10 μm, thereby obtaining insulating particles of the present invention. The characteristics of the insulating particles are as follows. Average particle size: 6.1 μm, particle size distribution: between 3 and 10 μm Melting point: 110 ° C. (TMA method; measured under a measurement load of 10 g) Reactivity: Completely cured within 150 ° C. × 1 hour.

As the insulating adhesive (3), 90 parts by weight having the following composition was used. Cresol novolak resin @ 30 parts by weight (phenol value: 122; manufactured by Gunei Chemical Industry) Epoxy resin A @ 90 parts by weight (Epiclone No. 850S: No. 830S = 50:50;
Epoxy resin B @ 10 parts by weight (Epiclon No. 520; manufactured by Dainippon Ink) Hardening accelerator (Ajinomoto) @ 8 parts by weight (Amicure PN-23) This adhesive is gelled for 15 seconds at 180 ° C. (hot plate method).
Met.

Example 1 As shown in FIG. 1, an anisotropic conductive composition of the above composition was used to uniformly knead a chip-on-glass (GOG) connection between a liquid crystal panel (4) and an IC chip (5). The product was defoamed under reduced pressure, and was applied onto circuit terminals of a liquid crystal panel using a syringe or the like. The liquid crystal panel after application was preheated at 80 ° C. for 10 minutes, and then the liquid crystal panel and the IC chip were pressed at 170 ° C. at a pressure of 10 kg per chip for 60 seconds. If necessary, it was kept in an oven and completely cured. Although the height of the bump of the IC chip had a gap variation of about 2 μm, the bump and the substrate came into close contact with each other via the conductive particles due to the melting of the insulating particles at the time of pressure bonding, and the gap variation was absorbed. Tests were performed at all points, and all of them were less than the standard conduction resistance of 200Ω (including wiring resistance). In addition, the insulation resistance was tested at 192 points, all of which were at or above the standard insulation resistance of 10 ⁸ Ω, showing good conductivity and insulation. In addition, as a result of observing the conductive particles on the bump through the liquid crystal panel, it was confirmed that there were 20 or more conductive particles per bump, and the object of the present invention was achieved.

Embodiment 2 As shown in FIG. 2, PWB and IC of a glass epoxy substrate are used.
In bonding the chips, the level difference between the Cu / Au plated electrodes is about 5 μm, and there is a maximum gap variation between the electrodes of 7 μm including the variation in bump height. The anisotropic conductive composition having the above composition is used for connecting a printed circuit board on which a copper wiring or the like is formed and an IC chip,
Crimping was performed at 170 ° C. for 10 kg / chip for 60 seconds.
If necessary, it was kept in an oven and completely cured. The conduction resistance was tested at 384 points, all of which were less than the standard conduction resistance of 5Ω (including the wiring resistance). Further, the insulation resistance was tested at 192 points, and all of them were more than the standard insulation resistance of 10 ⁸ Ω. The function of absorbing the gap variation was not hindered by the conductive particles sinking or deforming into the electrodes and bumps.

[Brief description of the drawings]

FIG. 1 shows an example 1 using the anisotropic conductive composition of the present invention.
Shows a state in which the liquid crystal substrate and the IC chip are joined by the method described above.

FIG. 2 shows the results of Example 2 using the anisotropic conductive composition of the present invention.
Shows a state in which a printed wiring board (PWB) and an IC chip are joined by the method (1).

[Explanation of symbols]

 1: conductive particles 2: insulating particles 3: insulating adhesive 4: liquid crystal panel or PWB 5: IC chip 6: bump 7: ITO electrode or copper / gold plated electrode

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01B 13/00 501 H01B 13/00 501P H01R 11/01 H01R 11/01 AHF term (Reference) 4J040 CA082 DA052 DA062 DB052 DE032 DF041 DF042 DM012 EC001 EC002 EC321 ED002 FA131 FA261 FA291 HA066 HB41 HD41 JA01 JB10 KA03 KA07 KA09 KA12 KA14 KA24 KA32 LA03 LA09 NA17 NA20 PA30 PA33 5G301 DA03 DA05 DA10 DA11 DA42 DA42

Claims (5)

[Claims] 1. An anisotropic conductive composition in which conductive particles and thermally fusible insulating particles are uniformly dispersed in an insulating liquid adhesive. 2. The composition according to claim 1, wherein the conductive particles are metal particles or plastic particles metal-plated. 3. The insulating particles are further thermosetting,
The composition of claim 1. 4. The composition according to claim 1, wherein the insulating liquid adhesive contains an acrylic resin. 5. An adhesive composition according to claim 1, which is supplied to the electrical joint to thermally compress the joint to obtain electrical continuity between the electronic components via conductive particles in the pressure direction. A method for producing an anisotropic conductive member, wherein conductive particles are melted and exhibit insulating properties in other directions.