JPH11130841A - Epoxy resin composition, adhesive, composition for circuit connection and film using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition excellent in storage stability and curable at relatively low temperatures, by including an epoxy resin, a specific polythiol and a potential curing accelerator. SOLUTION: This composition is obtained by including (A) an epoxy resin having an epoxy equivalent of, preferably, 43-1,000, (B) a polythiol (e.g. 1,3,5- trimercaptomethylbenzene) expressed by the formula (R is H or a 1-12C alkyl) and (C) a potentially curing accelerator (e.g. 2-methylimidazole) preferably having activity to accelerate the reaction among epoxy groups or the reaction of an epoxy group with a mercapto group at a reaction temperature of 100-130 deg.C and having no such activity at room temperature. Addition of (D) an electroconductive particles to the above composition produces a suitable resin composition for circuit connection, and addition of (E) polymer (s) (e.g. phenoxy resins) to the above composition makes film formation easy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an epoxy resin composition, an adhesive, a circuit connecting material, and a film using the same.

[0002]

2. Description of the Related Art As a thermosetting resin capable of realizing low-temperature rapid curing, a composition comprising an epoxy resin, a thiol-based curing agent, and a solid dispersion type amine adduct-based latent curing accelerator is known (for example, Japanese Patent Application Laid-Open No. HEI 9-163572). 6-219969). However, these compositions and adhesives composed of these compositions have poor storage stability.

[0003] Adhesives for adhering two circuit boards and providing electrical continuity between these electrodes include thermoplastic materials such as styrene and polyester, and thermosetting materials such as epoxy and silicone. The substance is known.

[0004] In this case, an adhesive is prepared by mixing conductive particles in an adhesive and obtaining electrical connection in the thickness direction of the adhesive by pressure (for example, Japanese Patent Application Laid-Open No. 55-104007). A device in which electrical connection is obtained by contact of fine irregularities on the electrode surface by pressurization at the time of connection (for example,
No. 62430).

[0005] Previously, these bonds were relatively hot (14
(0 ° C. to 200 ° C.) for a short time. However, if the connection can be performed at, for example, 100 ° C. or 130 ° C. by lowering the connection temperature, the displacement of the connection region due to the difference in the thermal expansion coefficient of the connection body is reduced,
Further, since the material to be connected can be switched to a cheaper material having low heat resistance, it is industrially very desirable.

In the conventional thermosetting adhesive, the connection is usually made at a high temperature of 170 ° C. or higher in order to carry out the curing reaction more reliably. Since the materials are different, the thermal expansion coefficients are different from each other, and it has been difficult to form a connection body having a narrow pitch.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to
Curing is possible at 0 to 130 ° C for several tens of seconds to several hours.
An object of the present invention is to provide an epoxy resin composition having good storage stability.

Another object of the present invention is to provide an adhesive which can be cured at 100 to 130 ° C. for several tens of seconds to several hours and has good storage stability.

Another object of the present invention is to achieve a high storage stability under the conditions of 100 to 130 ° C. for several tens of seconds to several hours, which are good in storage stability and can suppress expansion of the substrate due to heating. An object of the present invention is to provide a composition for circuit connection that enables reliable connection.

Another object of the present invention is to provide a film which can be cured at 100 to 130 ° C. for several tens of seconds to several hours, has good storage stability, and has excellent handleability.

[0011]

The present invention relates to (A) an epoxy resin, (B) a general formula (I)

[0012]

Embedded image (Wherein, three Rs are each independently hydrogen or a group having 1 to 12 carbon atoms)
Represents an alkyl group. )) And an epoxy resin composition comprising (C) a latent curing accelerator.

[0013] The present invention also relates to an adhesive comprising the epoxy resin composition.

[0014] The present invention also relates to a circuit connecting composition comprising the epoxy resin composition and conductive particles.

The present invention also relates to a film comprising the composition for circuit connection.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the epoxy resin (A) is not particularly limited as long as it has an epoxy group in a molecule, and a known resin can be used. Examples of the epoxy resin (A) include bisphenol type epoxy resins, bisphenol F type epoxy resins, bisphenol type epoxy resins such as bisphenol II / bisphenol F copolymer type epoxy resins, cresol novolak type epoxy resins, and phenol novolaks. Novolak epoxy resins such as epoxy resins, biphenyl glycidyl ether, triglycidyl isocyanurate, polyglycidyl methacrylate, and copolymers of glycidyl methacrylate with a vinyl monomer copolymerizable therewith. These are used alone or in combination of two or more. Among these, bisphenol-type epoxy resins are preferred, because grades having different molecular weights are widely available as compared with other various epoxy compounds, and adhesiveness, reactivity and the like can be arbitrarily set.

The epoxy equivalent of the epoxy resin (A) used in the present invention is preferably from 43 to 1,000, and more preferably from 50 to 800.
Is more preferable, and 73 to 600 is particularly preferable. If the epoxy equivalent is less than 43 or more than 1,000, the adhesive strength tends to decrease when connecting electrodes described later. These (A) epoxy resins have impurity ions (Na ⁺ ,
Cl ^-, etc.) or a hydrolyzable chlorine using a high purity product was reduced to 300ppm or less, preferably in order to prevent electron migration.

In the present invention, the polythiol (B) has the general formula (I)

[0019]

Embedded image (Wherein, three Rs are each independently hydrogen or a group having 1 to 12 carbon atoms)
Represents an alkyl group. There is no particular limitation as long as it is a compound represented by the formula (1), but considering the availability of raw materials and the ease of synthesis, 1,3,5-trimercaptomethylbenzene, 1,3,5-trimercaptomethyl- 2,4,6
-Trimethylbenzene is preferred.

The value obtained by dividing the molecular weight of the polythiol (B) used in the present invention by the number of functional groups (SH equivalent) is preferably from 72 to 240, more preferably from 72 to 156, and even more preferably from 72 to 114.
Is particularly preferred. When the SH equivalent is less than 72 or more than 240, the adhesive strength tends to decrease when connecting electrodes described later.

The amount of (B) polythiol used is 0.5 / 1 based on (A) epoxy resin, (B) total amount of mercapto groups of polythiol / (A) total amount of epoxy resin epoxy groups (equivalent ratio). It is preferable that the ratio be 0.5 to 1.5 / 0.5, and 0.8 / 1.2 to 1.2 /
More preferably, the ratio is 0.8. When this ratio is less than 0.5 / 1.5 and 1.5 / 0.
If it exceeds 5, a large amount of unreacted epoxy groups and mercapto groups will remain in the connector after the curing reaction, and the adhesive strength tends to decrease. In addition, the boiling point is preferably 150 ° C. or higher because (B) the polythiol evaporates due to the heating at the time of connection, and the reaction equivalent of the epoxy group of the (A) epoxy resin cannot be maintained. The form of the polythiol (B) is preferably liquid because it has higher operability than solid in consideration of the miscibility with other components, but is not limited to liquid.

The latent curing accelerator (C) used in the present invention preferably has an activity of accelerating the reaction between epoxy groups or an epoxy group and a mercapto group at a reaction temperature of 100 to 130 ° C., and has an activity at room temperature. Can be used without particular limitation as long as it does not show, for example, alkylimidazole compounds such as 2-methylimidazole, 2-ethylimidazole, 2-propylimidazole, arylimidazole compounds such as phenylimidazole and naphthylimidazole, 2 -Aminoethylimidazole,
Aminoalkylimidazole compounds such as 2-aminopropylimidazole, adipic dihydrazide, eicosan diacid dihydrazide, 7,11-octadecadien-
Hydrazide compounds such as 1,18-dicarbohydrazide, 1,3-bis (hydrazinocarboethyl) -5-isopropylhydantoin, polyamine, dicyandiamide,
Tertiary phosphines, quaternary ammonium salts, quaternary phosphonium salts and the like. These are used alone or in combination of two or more. These (C) latent curing accelerators are polymer substances such as polyurethane and polyester, metal thin films such as Ni and Cu, and microcapsules coated with inorganic substances such as calcium silicate. It may be made into an adduct by reacting with an epoxy resin, and such an adduct is preferable in view of extending the pot life.

With these (C) latent curing accelerators,
(B) The activity of the polythiol is catalytically enhanced, a fast curing property is obtained, the necessary adhesive strength can be obtained even when the heating temperature for curing is lowered, and the thermal expansion of the connected material It is possible to minimize the displacement of the conductive portion.

(C) The amount of the latent curing accelerator used is
(A) 0.01 to 100 parts by weight of epoxy resin
The amount is preferably 200 parts by weight, more preferably 0.1 to 100 parts by weight, and particularly preferably 0.5 to 50 parts by weight. If this amount is less than 0.01 part by weight, the effect of accelerating curing tends to be insufficient.
If it exceeds 0 parts by weight, the compatibility tends to decrease.

The epoxy resin composition of the present invention is suitably used as an adhesive between circuit boards.

The epoxy resin composition of the present invention further comprises:
(E) Addition of polymers facilitates film formation. (E) As polymers, there are phenoxy resin, polyvinyl chloride, polyurethane, polyester, styrene butadiene rubber and the like, and the addition of phenoxy resin is more preferable. Phenoxy resins used as necessary include
Bisphenol II type phenoxy resin and bisphenol F
General-purpose phenoxy resins such as a phenoxy resin of the type, bisphenol Α, and a phenoxy resin copolymerized with bisphenol F. Such a phenoxy resin is similar in structure to an epoxy resin and therefore has good compatibility and good adhesion. The larger the molecular weight, the more easily the film-forming property can be obtained, and the melt viscosity which affects the fluidity at the time of connection can be set in a wide range. (E) The phenoxy resin has a weight average molecular weight of 10,000 to 150,000, of which 10,000 to 80,000 is preferable. If this value is less than 10,000, the film-forming properties tend to be poor, and if it exceeds 80,000, the compatibility with other components tends to be poor. (E)
When using a phenoxy resin, it is preferable to use 20 to 320 parts by weight based on 100 parts by weight of the epoxy resin. When this amount is less than 20 parts by weight or more than 320 parts by weight, the film-forming property tends to decrease.

The epoxy resin composition of the present invention can be suitably used as a resin composition for circuit connection by blending (D) conductive particles with the epoxy resin composition.

The conductive particles (D) used in the resin composition for circuit connection of the present invention include Au, Ag, Ni, Cu,
Examples thereof include metal particles such as solder, carbon particles, and the like. In addition, non-conductive glass, ceramics, plastics such as polystyrene, or the like may be used as a core, and the core may be coated with the metal or carbon.

(D) In the case where the conductive particles are plastic cores and the cores are coated with the above-mentioned metal or carbon, or hot-melt metal particles, they have deformability due to heating and pressing. This is preferable because the area is increased and the reliability is improved.

The average particle size of the conductive particles (D) is preferably 2 to 18 μm from the viewpoint of dispersibility and conductivity. The amount of (D) the conductive particles used is 0.1 to 0.1 with respect to the total amount of (A) epoxy resin, (B) polythiol, (C) latent curing accelerator and (E) phenoxy resin used as required. Preferably, it is 30% by volume,
More preferably, it is 10% by volume. This value is 0.
If it is less than 1% by volume, the conductivity tends to be poor, and if it exceeds 30% by volume, a short circuit tends to occur. In addition,
The volume% is determined based on the volume of each component before curing at 23 ° C., but the volume of each component can be converted from weight to volume using specific gravity. In addition, put the component in a suitable solvent (water, alcohol, etc.) that does not dissolve or swell the component in a graduated cylinder, etc. You can also ask.

In the resin composition for circuit connection of the present invention, additives such as an adhesion improver such as a coupling agent and a leveling agent may be appropriately added.

The composition for circuit connection according to the present invention comprises
It is useful for bonding a C chip to a substrate and connecting electric circuits to each other. In this case, for example, a solution prepared by adding a solvent or the like as necessary to the circuit connection composition is applied to a release substrate such as a fluororesin film or release paper, or a substrate such as a nonwoven fabric is impregnated with the solution. Then, the film is placed on a peelable substrate, dried at a temperature lower than the activation temperature of the curing accelerator, and a solvent or the like is removed to form a film, which can be used in the form of the film. Use in the form of a film is more convenient in terms of handling properties and the like.

The solvent is not particularly limited and may be a known solvent. A mixed solvent of an aromatic hydrocarbon-based solvent such as toluene and an oxygen-containing solvent including acetic esters such as ethyl acetate can be used. Is preferred in terms of solubility. Here, the SP value of the oxygen-containing solvent is preferably in the range of 8.1 to 10.7 from the viewpoint of protecting the latent curing accelerator (C).

The boiling point of the solvent is preferably 150 ° C. or lower, more preferably 60 to 90 ° C., and particularly preferably 70 to 80 ° C. If the boiling point exceeds 150 ° C., a high temperature is required for drying and the activation temperature is close to the activation temperature of the latent curing accelerator, so that the potential tends to decrease. At a low temperature, the workability during drying tends to decrease.

When a solvent is used, the amount of the solvent used is preferably such that the solid content of the solution is 10 to 90% by weight.

Hereinafter, an example of the circuit connection composition of the present invention and an example of electrode connection using a film using the composition will be described.

The layer of the composition for circuit connection is provided between the electrodes facing each other on the substrate, and by applying heat and pressure, the contact between the two electrodes and the adhesion between the substrates are obtained, whereby the electrodes can be connected. As the substrate on which the electrodes are formed, inorganic substrates such as semiconductors, glass, and ceramics, organic substrates such as polyimide and polycarbonate, inorganic-organic composite substrates such as glass / epoxy, and combinations of these can be applied. . By using the composition for circuit connection of the present invention and a film using the same, it is possible to connect materials having significantly different coefficients of thermal expansion, which has been difficult in the past, and thus it can be applied to connection of a wide range of materials.

Since the composition for circuit connection of the present invention and a film using the same can be connected at a relatively low temperature, the thermal stress at the time of connection is small, and the reliability after connecting a fine circuit can be remarkably improved. Since a large margin can be taken, the efficiency of circuit connection work is improved, and the yield is also improved.

[0039]

The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 Bisphenol type liquid epoxy resin (Bisphenol II)
Type epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd., trade name Epicoat 828, epoxy equivalent 184) 50 g,
It was dissolved in a mixed solvent of toluene / ethyl acetate = 50/50 by weight to obtain a solution having a solid content of 40% by weight.

23 g of polythiol (1,3,5-trimercaptomethyl-2,4,6-trimethylbenzene, SH equivalent: 86) used was synthesized as follows. 1,
3,5-Trisbromomethyl-2,4,6-trimethylbenzene is reacted with thiourea to convert the bromomethyl group to a methyl thyuronium salt, which is then hydrolyzed with an aqueous sodium hydroxide solution to give a methyl thiuronium salt. Is converted to a mercaptomethyl group to give 1,3,5-trimercaptomethyl-
2,4-6-trimethylbenzene was obtained.

The latent curing accelerator is Novacure HX394
1HP (a masterbatch-type curing accelerator obtained by dispersing a microcapsule-type curing accelerator having an average particle diameter of 5 μm, whose surface is coated with polyurethane, having a modified imidazole nucleus as a core, in a liquid bisphenol F-type epoxy resin, Asahi Kasei (Trade name, manufactured by Kogyo Co., Ltd.).

50 g of a bisphenol III, F copolymerized phenoxy resin (average molecular weight 20,000) synthesized from bisphenol II, bisphenol F (1/1 molar ratio) and epichlorohydrin was added to toluene (boiling point 110.6).
° C, SP value 8.90) / ethyl acetate (boiling point 77.1 ° C,
(SP value 9.10) = 50/50 (weight ratio) to obtain a solution having a solid content of 40% by weight.

A nickel layer having a thickness of 0.2 μm was provided on the surface of particles having polystyrene as a core, and a gold layer having a thickness of 0.02 μm was provided outside the nickel layer.
m, conductive particles having a specific gravity of 2.0 were prepared.

Resin component 123 (bisphenol-type liquid epoxy resin 50 added to bisphenol Α, F
Copolymerized phenoxy resin 50: polythiol 23), blended to become latent curing accelerator 20, further dispersed and dispersed 3% by volume of conductive particles, using a coating device on a 80 μm thick fluororesin film. 70 ° C, 10
A 25 μm-thick composition layer for circuit connection was formed by hot air drying for one minute.

The composition layer for circuit connection formed on the fluororesin film (hereinafter referred to as a circuit connection member)
It had sufficient flexibility at room temperature, hardly changed its properties even when left at 40 ° C. for 240 hours, and showed good storage stability.

Example 2 Polythiol was converted to 1,3,5-trimercaptomethyl-
1,3,5 instead of 2,4,6-trimethylbenzene
-Trimercaptomethylbenzene (SH equivalent 72) 19
g, and a connection member for a circuit was obtained in the same manner as in Example 1, except that the resin solid content was 119 g. In addition,
1,3,5-trimercaptomethylbenzene is obtained by reducing trimesic acid with lithium aluminum hydroxide to convert a carboxyl group to a methylol group, and further reacting with thionyl chloride to convert a methylol group to a chloromethyl group. The chloromethyl group was converted to a methyl thyuronium salt by reacting with thiourea, and further hydrolyzed with an aqueous sodium hydroxide solution to convert the methyl thyuronium salt to a mercaptomethyl group.

This circuit connecting member had properties equivalent to those of the circuit connecting member of the first embodiment.

Comparative Example 1 Polythiol was converted to 1,3,5-trimercaptomethyl-
Adeka hardener EH310, polyethylene glycol α, ω-bis (2-hydroxy-3-mercaptopropyl) ether (polythiol ether resin, Asahi Denka Kogyo KK, SH equivalent weight 190, instead of 2,4,6-trimethylbenzene) A connection member for a circuit was obtained in the same manner as in Example 1 except that the connection member was made 50 g and the total resin solid content was made 150 g.

(Circuit Connection) Using the circuit connecting members obtained in Examples 1 and 2 and Comparative Example 1, 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 120 ° C, 2MP
a and heated and pressurized for 20 seconds to connect over a width of 2 mm.
At this time, after the circuit connection composition layer (adhesive surface) of the circuit connection member is previously attached to one FPC,
Temporarily connected 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 the other FPC.

Further, the above-mentioned FPC and indium oxide (I
Glass with TO) thin film (surface resistance 20Ω / □)
Is heated and pressurized at 120 ° C. and 2 MPa for 10 seconds to have a width of 2 m.
m. At this time, a temporary connection was made on the ITO glass in the same manner as described above.

The circuit connection members obtained in Examples 1 and 2 and Comparative Example 1 were stored in a refrigerator for 30 days, and the circuits were similarly connected.

(Measurement of connection resistance) After the connection of the circuit, the resistance value between the adjacent circuits of the FPC including the connection portion is set to an initial value of 85%.
After the sample was kept in a high-temperature and high-humidity bath at 85 ° C. and 85% RH for 500 hours, the measurement was performed with a multimeter. The resistance value was shown as an average (X + 3σ) of 150 points of resistance between adjacent circuits.

(Adhesive Strength of Connected Body) The adhesive strength between the adhesive used for the FPC and each composition layer for circuit connection (adhesive surface) was measured by a 90-degree peeling method according to JIS-Z0237. And evaluated. The measuring device was Tensilon UTM-4 manufactured by Toyo Baldwin Co., Ltd. (peeling speed 50 mm / mi).
n, 25 ° C.).

Table 1 shows the measurement results of the adhesive strength and the connection resistance of the connection body. The circuit connection members obtained in Examples 1 and 2 showed good short-time connectivity at 120 ° C. even after 30 days,
The adhesive strength also reached a sufficient strength. In addition, the initial connection resistance of the connection body was low, and the resistance after the high-temperature and high-humidity test increased only slightly, indicating that the connection body had high durability.

On the other hand, in Comparative Example 1, the adhesive strength of the connecting member with the circuit connecting member after being left for 30 days was significantly reduced, and the connecting member was not satisfactory.

[0057]

[Table 1]

[0058]

According to the present invention, an epoxy resin composition which can be cured at 100 to 130 ° C. for several tens of seconds to several hours and has good storage stability was obtained.

According to the present invention, an adhesive which can be cured at 100 to 130 ° C. for several tens of seconds to several hours and has good storage stability was obtained.

According to the present invention, a composition for circuit connection which enables highly reliable connection can be obtained by curing at 100 to 130 ° C. for several tens of seconds to several hours under curing conditions capable of suppressing expansion of the substrate due to heating. Was done.

According to the present invention, a film for circuit connection having the above characteristics and further excellent in handleability was obtained.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Mitsugu Fujinawa 48, Wadai, Tsukuba, Ibaraki Prefecture Within Tsukuba Development Laboratory, Hitachi Chemical Co., Ltd. Nagoya Fukushima, Inventor Nagoya Fukushima, 1150 Goshomiya, Oaza, Shimodate, Ibaraki Pref. Hitachi, Ltd. (72) Inventor Yukiko Muramatsu 4-3-1-1, Higashicho, Hitachi City, Ibaraki Pref.

Claims (4)

[Claims] (A) an epoxy resin, (B) a general formula (I) (Wherein, three Rs are each independently hydrogen or a group having 1 to 12 carbon atoms)
Represents an alkyl group. An epoxy resin composition comprising the polythiol represented by ()) and (C) a latent curing accelerator. 2. An adhesive comprising the epoxy resin composition according to claim 1. 3. A circuit connection composition comprising the epoxy resin composition according to claim 1 and conductive particles. 4. A film comprising the composition for circuit connection according to claim 3.