JPH09147946A - Connection member for circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit connection member, which is excellent in workability and reliability in connection, by specifying a plurality of resins, a hardener, conductive particles, and insulative particles as essential constituents. SOLUTION: Essential constituents for a connection member for a circuit are phenoxy resin such as bisphenol A type phenoxy resin whose mean molecular weight is approximately 10000-80000 desirably, an epoxy resin such as naphthalene epoxy resin, a latent hardener such as an imidazole hardener, conductive particles with a mean particle diameter of 2-18μ desirably such as particles in each of which a gold layer is arranged on the outside of a Ni layer arranged on the surface of a PS particle, and insulative particles, in each of which a mean particle diameter is 1μ or more desirably and is not more than the mean particle diameter of the conductive particle, such as titanium oxide particles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit connecting member suitable for connecting two electrodes, which is formed between electrodes of two circuit boards in a liquid crystal panel or the like.

[0002]

2. Description of the Related Art Along with bonding two circuit boards together,
As a circuit connecting member for obtaining electrical continuity between these electrodes, a styrene-based or polyester-based thermoplastic material,
A circuit connecting member composed of a thermosetting substance such as an epoxy type or a silicone type and conductive particles is generally known. When the ITO electrode of the liquid crystal panel and the TAB are connected using this circuit connecting member, usually, the circuit connecting member is first heated and pressed (temporarily connected) to the ITO electrode of the liquid crystal panel, and then the temporarily connected circuit connection. Heat and press the TAB on the member (main connection),
The liquid crystal panel and the TAB are bonded together, and these terminals are electrically connected by conductive particles. In this case, IT
After the circuit connecting member is temporarily connected on the O electrode, it is necessary to recognize the ITO electrode pattern and the TAB electrode pattern in order to perform alignment with the electrode pattern such as TAB. Normally, in the step of recognizing this pattern, as shown in FIG. 1, the ITO electrode 2 on the liquid crystal panel 1 to which the circuit connecting member a is temporarily connected is recognized by the coaxial light using the CCD camera 3. .

[0003]

As shown in FIG. 2,
Since the reflected light b from ITO has a higher intensity than the reflected light c from glass, the contrast between ITO and glass can be obtained when the circuit connecting member is not temporarily connected to the panel. However, when the circuit connecting member a is temporarily connected and is present on the panel, as shown in FIG. 3, reflection on the a-1 surface which is the surface of the conventional circuit connecting member a mainly made of epoxy resin is not reflected. Occurs. Since the conventional circuit connecting member a mainly made of epoxy resin has a high transmittance in the wavelength range of 400 to 900 nm, the reflected light e deteriorates the contrast between ITO and glass. Furthermore, since the surface of the circuit connecting member a-1 has irregularities, the transmitted light f-1 and f-2 of the reflected light e have a contrast due to the intensity difference. This causes a problem that the CCD camera erroneously recognizes this.

[0004]

Means for Solving the Problems The present invention includes the following (1) to
The present invention relates to a circuit connecting member including an adhesive component, which includes the component (4) as an essential component, and conductive particles. (1) Phenoxy resin (2) Epoxy resin (3) Latent curing agent (4) Conductive particles (5) Insulating particles

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The phenoxy resin used in the present invention will be described. The phenoxy resin has a molecular weight of 1000 determined by high performance liquid chromatography (HLC).
Corresponding to a high molecular weight epoxy resin of 0 or more, there are other types such as bisphenol A type, AD type, AF type, etc. as well as the epoxy resin. Since they have a similar structure to the epoxy resin, they have good compatibility and also have good adhesiveness. The larger the molecular weight, the more easily the film-forming property can be obtained, and the melt viscosity that affects the fluidity at the time of connection can be set in a wide range. The average molecular weight is 10,000 to 8,000
It is more preferably about 0 in terms of melt viscosity and compatibility with other resins. When these resins contain a polar group such as a hydroxyl group or a carboxyl group, the compatibility with the epoxy resin is improved, a film having a uniform appearance and characteristics can be obtained, and the reaction during curing is accelerated for a short time. It is also preferable from the viewpoint of obtaining curing. The compounding amount is 20 to 8 relative to the entire resin component from the viewpoint of film forming property and acceleration of curing reaction.
It is preferably 0% by weight. Further, styrene resin, acrylic resin or the like may be appropriately mixed in order to adjust the melt viscosity.

The epoxy resin used in the present invention is a bisphenol type epoxy resin derived from epichlorohydrin and bisphenol A, F, AD, etc., an epoxy novolac resin derived from epichlorohydrin and phenol novolac or cresol novolac, and a skeleton containing a naphthalene ring. A naphthalene-based epoxy resin having carboxylic acid, glycidylamine, glycidyl ester, biphenyl, alicyclic, and the like, various epoxy compounds having two or more glycidyl groups in one molecule, or the like, or used in combination of two or more. Is possible. As these epoxy resins, it is preferable to use high-purity products in which impurity ions (Na ⁺ , Cl ^−, etc.) and hydrolyzable chlorine are reduced to 300 ppm or less in order to prevent electron migration.

As the latent curing agent, imidazole-based compounds,
There are hydrazide compounds, boron trifluoride-amine complexes, sulfonium salts, amine imides, diaminomaleonitriles, melamine and its derivatives, polyamine salts, dicyandiamide, and modified products thereof, and these may be used alone or as a mixture of two or more kinds. Can be used as These are anionic or cation-polymerizable catalyst type curing agents, and are preferable because they are easy to obtain fast curing property and require less consideration in chemical equivalent. As the curing agent, it is also possible to apply polyaddition type of polyamines, polymercaptans, polyphenols, acid anhydrides and the like, or to use in combination with the catalyst type curing agent.

Anionic polymerization type catalyst type curing agents include
Tertiary amines and imidazoles are mainly used.
Epoxy resins containing tertiary amines and imidazoles have a relatively long pot life because they cure at a moderate temperature of about 160 to 200 ° C. by heating for several tens of seconds to several hours.

As the cationic polymerization type catalyst type curing agent,
A photosensitive onium salt that cures a resin by irradiation with energy rays, such as an aromatic diazonium salt or an aromatic sulfonium salt, is mainly used. Aliphatic sulfonium salts and the like can be activated by heating in addition to energy ray irradiation to cure the epoxy resin. This type of curing agent is preferable because it has a feature of fast curing.

Microcapsules obtained by coating these curing agents with high molecular substances such as polyurethane and polyester, metal thin films such as Ni and Cu, and inorganic substances such as calcium silicate have a long pot life. It is preferable because it is possible.

In the adhesive composition obtained above, for example, fillers, softeners, accelerators, antioxidants, coloring agents, flame retardants, thixotropic agents, coupling agents, and the like, as ordinary additives, etc. A curing agent such as a phenol resin, a melamine resin, and an isocyanate may be contained.

As the conductive particles, Au, Ag, Ni,
There are metal particles such as Cu and solder, carbon, etc., and these and non-conductive glass, ceramics, plastics, etc. may be formed by coating the above conductive layers.
In the case of using plastic as the core or in the case of heat-melting metal particles,
Since it has a deformability by heating and pressurization, the contact area with the electrode at the time of connection is increased and the reliability is improved, which is preferable. The conductive particles are used properly in a wide range of 0.1 to 30% by volume with respect to 100% by volume of the adhesive component, depending on the application. To prevent short circuit of adjacent circuits due to excessive conductive particles, 0.1 to
It is more preferably 10% by volume.

Examples of the insulating particles include heat-deformable organic substances such as polystyrene and acrylic, silica, zinc oxide,
There are inorganic materials such as titanium oxide, and the surface may be surface-treated with organic silane or the like in order to improve the dispersibility in the adhesive composition. When the average particle diameter of the insulating particles is less than 0.1 μm, the light transmittance in the 400 to 900 nm region is high, and the effect of lowering the light transmittance of the circuit connecting member is small. Further, when the average particle size of the insulating particles is larger than the particle size of the conductive particles, it is difficult to obtain the connection by the conductive particles. The insulating particles are 0.1 to 100% by volume of the adhesive component.
It is properly used in order to adjust the light transmittance of the circuit connecting member in the range of 400 to 900 nm within 50% by volume to 50% or less. If it exceeds 10% by volume, it is difficult to obtain the connection by conductive particles, and if it is less than 0.1% by volume, it is 400 to 900.
There is little effect of reducing the light transmittance in the nm range. A particularly preferable blending amount is 0.5 to 5% by volume.

The adhesive composition of the present invention is particularly useful as a one-pack type adhesive, particularly as a film adhesive for adhering a liquid crystal panel. In this case, for example, the adhesive composition obtained above is liquefied as a dispersion liquid or the like in the case of a solvent or an emulsion and formed on a releasable base material such as release paper, or the above composition is added to a base material such as a nonwoven fabric. The solution may be impregnated to form on a releasable substrate, dried at the activation temperature of the curing agent or lower, and the solvent or dispersion may be removed. At this time, the solvent used is preferably a mixed solvent of an aromatic hydrocarbon type and an oxygen containing type because it improves the solubility of the material. Here, the SP value of the oxygen-containing solvent is preferably in the range of 8.1 to 10.7 from the viewpoint of protection of the latent curing agent, and acetic acid esters are more preferable. The boiling point of the solvent may be 150 ° C. or lower. When the boiling point exceeds 150 ° C., a high temperature is required for drying, and since the temperature is close to the activation temperature of the latent curing agent, the potential is reduced. At a low temperature, the workability during drying is reduced. Therefore, the boiling point is 60-15
0 degreeC is preferable and 70-130 degreeC is more preferable.

The connection of electrodes using the connecting material obtained in the present invention will be described. In this method, a circuit connecting member is formed between opposing electrodes on a substrate, and the electrodes are connected by heating and pressing to obtain contact between the two electrodes and adhesion between the substrates. As a substrate on which electrodes are formed, inorganic materials such as semiconductors, glass, and ceramics, organic materials such as polyimide and polycarbonate, and combinations of these composite materials such as glass / epoxy can be used.

According to the present invention, a circuit connecting member having the same connectivity as the conventional one and improved workability during temporary connection before the main connection can be obtained.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. Example 1 From bisphenol A and epichlorohydrin, bisphenol A type phenoxy resin (average molecular weight 30,000) 6
0 g was prepared by a general method, and this was mixed in a weight ratio of toluene (boiling point 110.6 ° C., SP value 8.90) / ethyl acetate (boiling point 77.1 ° C., SP value 9.10) = 50/50. It was dissolved in a solvent to obtain a solution having a solid content of 40%. Naphthalene-based epoxy resin (naphthalene diol-based epoxy resin, manufactured by Dainippon Ink and Chemicals, Inc., trade name HP-4
032, epoxy equivalent 149, hydrolyzable chlorine 130p
pm) 20 g in a weight ratio of toluene / ethyl acetate = 50 /
It was dissolved in 50 mixed solvents to obtain a solution having a solid content of 80%. Styrenic resin (styrene-maleic anhydride copolymer resin, Sekisui Plastics Co., Ltd., trade name Dailark #
20 g (250, heat distortion temperature 112 ° C.) was dissolved in toluene to obtain a solution having a solid content of 40%. The latent curing agent is Novacure 3941 HPS (having an imidazole modified product as a core, and the surface of which is coated with polyurethane, an average particle size of 5
A masterbatch type curing agent obtained by dispersing a microcapsule type curing agent of μm in a liquid bisphenol F type epoxy resin, an activation temperature of 125 ° C., a product name of Asahi Chemical Industry Co., Ltd.) was used. On the surface of the polystyrene core particles,
A nickel layer having a thickness of 0.2 μm was provided, and a gold layer having a thickness of 0.02 μm was provided on the outer side of the nickel layer to prepare conductive particles having an average particle size of 5 μm and a specific gravity of 2.5. TM-1 (titanium oxide, average particle size 0.4μ as insulating particles
m, a product name manufactured by Fuji Titanium Co., Ltd.). The resin component 100 and the latent curing agent 100 are mixed in a solid weight ratio, and further 3% by volume of conductive particles and 0.5% by volume of insulating particles are mixed and dispersed to form a fluororesin film having a thickness of 80 μm. It was applied using a coating device and dried with hot air at 75 ° C. for 10 minutes to obtain a circuit connecting member having an adhesive layer thickness of 18 μm.

Example 2 Instead of the latent curing agent by a microcapsule type curing agent, p
50% by weight ethyl acetate solution of acetoxyphenylbenzylsulfonium salt (manufactured by Sanshin Chemical Industry Co., Ltd., trade name San-Aid SI-60L), and blended so that the solid weight ratio becomes 5 with respect to 100 resin components In the same manner as in Example 1, a circuit connecting member was obtained.

Example 3 A circuit connecting member was obtained in the same manner as in Example 1 except that the conductive particles were replaced with nickel particles having an average particle size of 2 μm and an aggregate particle size of 10 μm.

Example 4 A circuit connecting member was obtained in the same manner as in Example 1 except that the conductive particles were replaced with an average particle size of 10 μm.

Example 5 A circuit connection was made in the same manner as in Example 1 except that the insulating particles were replaced by average particle diameter of 0.25 μm (CR-EL, titanium oxide, trade name of Ishihara Sangyo Co., Ltd.). The member was obtained.

Example 6 Insulating particles having a mean particle size of 0.25 μm and a surface-treated product (C
A connection member for a circuit was obtained in the same manner as in Example 1 except that R-80, titanium oxide, and trade name of Ishihara Sangyo Co., Ltd. were used.

Example 7 A circuit connecting member was obtained in the same manner as in Example 1 except that the compounding amount of the insulating particles was changed to 15% by volume.

Comparative Example 1 A circuit connecting member was obtained in the same manner as in Example 1 without mixing the insulating particles.

Comparative Example 2 A circuit connecting member was obtained in the same manner as in Example 1 except that the insulating particles had an average particle size of 0.05 μm.

Comparative Example 3 A circuit connecting member was obtained in the same manner as in Example 1 except that the compounding amount of the insulating particles was changed to 0.05% by volume.

(Circuit Connection) Using the circuit connecting member described above, the line width is 50 μm, the pitch is 100 μm, and the thickness is 18.
Flexible circuit board with 500 μm copper circuits (F
PCs) were heated and pressed at 170 ° C. and 3 MPa for 20 seconds and connected over a width of 2 mm. At this time, one FP in advance
After pasting the adhesive surface of the circuit connecting member on C, 80
Temporary connection was performed by heating and pressurizing at 0.5 ° C. and 0.5 MPa for 5 seconds, after which the fluororesin film was peeled off and connected to the other FPC. In addition, the above-mentioned FPC and indium oxide (IT
2 mm wide by heating and pressing glass (surface resistance 20 Ω / □) with a thin layer of O) at 160 ° C. and 3 MPa for 20 seconds.
Connected over. At this time, a temporary connection was made to the ITO glass in the same manner as described above.

(Measurement of Connection Resistance) After connecting the circuits, the resistance values between the adjacent circuits of the FPC including the above-mentioned connection parts are set to 8
It was held in a thermo-hygrostat at 5 ° C. and 85% RH for 500 hours and then measured with a multimeter. The resistance value was represented by an average (x + 3σ) of 150 points of resistance between adjacent circuits.

(Pattern recognition) I with a pitch of 100 μm
On the glass on which the TO pattern was formed, a circuit connecting member having a thickness of 18 μm was heated and pressed at 80 ° C. and 0.5 MPa for 5 seconds for temporary connection, and the image was recognized from the glass side through a CCD camera using coaxial light. In the image, the case where the ITO pattern was clearly recognizable was evaluated as “◯”, the case where it could only be recognized indefinitely was evaluated as “Δ”, and the case where it could not be recognized was evaluated as “x”.

(Measurement of transmittance) 18 μm thick on glass
The circuit connecting member of No. 2 was heated and pressed at 80 ° C. and 0.5 MPa for 5 seconds to be temporarily connected, and the light transmittance in the wavelength range of 400 to 900 nm was measured by a double beam spectrophotometer (Hitachi, Model 2).
00-10). The results are shown in Table 1.

[0031]

[Table 1]

[0032]

As described above in detail, according to the present invention, it becomes possible to provide a circuit connecting member having excellent connection reliability and workability.

[Brief description of the drawings]

FIG. 1 is a side sectional view for explaining the concept of pattern recognition.

FIG. 2 is a side sectional view showing a state of alignment.

FIG. 3 is a side sectional view showing a state of light rays at the time of alignment.

[Explanation of symbols]

 1 LCD panel 2 ITO pattern 3 CCD camera

Claims (8)

[Claims] 1. A circuit connecting member comprising the following components (1) to (4) as essential components: (1) phenoxy resin (2) epoxy resin (3) latent curing agent (4) conductivity Particles (5) Insulating particles 2. The circuit connecting member according to claim 1, wherein the conductive particles have an average particle diameter of 2 to 18 μm. 3. The adhesive composition 100 containing conductive particles.
It is 0.1-10 volume% with respect to a volume, The connection member for circuits of Claim 1 or 2 characterized by the above-mentioned. 4. The circuit connecting member according to claim 1, wherein the insulating particles have an average particle size of 0.1 μm or more and the conductive particles have an average particle size of less than or equal to 0.1 μm. . 5. The adhesive composition 100 having a content of insulating particles.
It is 0.1-10 volume% with respect to a volume, The circuit connection member in any one of Claim 1 thru | or 4 characterized by the above-mentioned. 6. The circuit connecting member according to claim 1, wherein the insulating particles are metal oxides. 7. The circuit connecting member according to claim 1, wherein the connecting member has a film shape. 8. A transmittance of 5 in a wavelength range of 400 to 900 nm.
It is 0% or less, The circuit connection member in any one of Claim 1 thru | or 7 characterized by the above-mentioned.