JPH09115335A - Anisotropic conductive adhesive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low temperature hardening type anisotropic conductive adhesive film having the excellent peeling strength and the excellent connection reliability, in which a high temperature hardening type of imidazole is used, by using two kinds of imidazole and amine together as a latent hardening agent as the material of an anisotropic conductive adhesive film. SOLUTION: In an anisotropic conductive adhesive film, which includes the thermosetting insulating adhesive agent, conductive grains and the latent hardening agent, the imidazole latent hardening agent and the amine subclinical hardening agent are used together as a latent hardening agent. The imidazole latent hardening agent at 7.5-27.5 parts by weight and the amine latent hardening agent at 25-55 parts by weight are desirably blended in relation to the thermosetting insulating adhesive agent at 100 parts by weight. The thermosetting insulating adhesive agent, which includes the flexible epoxy resin, is desirable.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an anisotropic conductive adhesive film for use in adhesive bonding between terminals and the like.

[0002]

2. Description of the Related Art An ITO terminal on a glass substrate of a liquid crystal panel, a flexible substrate or a TCP (Tape carrier package)
As one of the materials for adhering two circuit boards and electrically connecting the terminals between them, as in the case of connecting the terminals of a thermosetting insulating adhesive, conductive particles, and latent curing. A one-pack anisotropic conductive adhesive film formed by molding a mixture with an agent into a film has been widely used. In this case, the terminals are connected by sandwiching an anisotropic conductive adhesive film between the terminals and thermocompression bonding.

As a thermosetting insulating adhesive used in such an anisotropic conductive adhesive film, a high molecular weight epoxy which is solid at room temperature is taken into consideration in consideration of film forming property on the film, film strength and the like. A resin and, if necessary, an epoxy resin which is liquid at room temperature are used.

As the latent curing agent, an imidazole type latent curing agent having an action (curing) temperature of about 170 ° C. is generally used. By using the imidazole-based latent curing agent exhibiting such a curing temperature, the terminals can be reliably bonded and electrically connected. Moreover, the tact time during thermocompression bonding can be set to about several seconds, and good heat resistance can be imparted to the anisotropic conductive adhesive film.

[0005]

However, when the terminals are connected by an anisotropic conductive adhesive film having a thermocompression bonding temperature of 170 ° C. or higher, thermal stress applied to the liquid crystal panel and terminals which are densely wired and thinned. Is becoming non-negligible, and there is a concern that the connection accuracy will decrease and the number of connection failures will increase.

Further, it has been attempted to replace the glass substrate of the liquid crystal panel with a polyethylene terephthalate substrate or a polyether sulfone substrate having relatively low heat resistance but good flexibility. In this case, It is desired to perform the thermocompression bonding temperature of the anisotropic conductive adhesive film at a low temperature of about 130 ° C.

However, the anisotropic conductive adhesive film using an imidazole-based latent curing agent having an action (curing) temperature of about 170 ° C. has a very high curing rate when the thermocompression bonding temperature is set to about 130 ° C. Due to the delay, there is a problem that the peel strength of the anisotropic conductive adhesive film becomes very low at the same takt time as in the past, and the conduction reliability also becomes low. Therefore, it is conceivable to lengthen the takt time at the time of thermocompression bonding, but there arises a problem that it becomes necessary to set a takt time that greatly exceeds the time that can be allowed in industrial production.

For this reason, it is conceivable to use a known amine-based latent curing agent having an action (curing) temperature of about 130 ° C. instead of the imidazole-based latent curing agent, but the amine-based latent curing agent is used. Anisotropic conductive adhesive film using a curing agent does not have sufficient conduction reliability, and the glass transition point is generally lower than when using an imidazole-based latent curing agent, and the heat resistance of the film is not sufficient. There is. Therefore, the amine-based latent curing agent is considered to be unsuitable as a curing agent for a low temperature curing type anisotropic conductive adhesive film.

The present invention is intended to solve the problems of the prior art as described above, and cures a high temperature curing type imidazole-based latent curing agent capable of imparting excellent heat resistance to an anisotropic conductive adhesive film. It is an object of the present invention to provide a low temperature curable anisotropic conductive adhesive film which is excellent in peel strength and connection reliability while being used as an agent.

[0010]

Means for Solving the Problems In addition to a high temperature curable imidazole-based latent curing agent as a curing agent,
By combining with an amine-based latent curing agent, which is considered unsuitable as a curing agent for low-temperature curing of anisotropic conductive adhesive films, the imidazole-based latent curing agent can be used for curing reaction even at a curing temperature of about 130 ° C. Can contribute
The inventors have found that the peel strength can be improved while ensuring the conductive reliability of the anisotropic conductive adhesive film, and have completed the present invention.

That is, the present invention relates to a thermosetting insulating adhesive,
An anisotropic conductive adhesive film containing conductive particles and a latent curing agent, wherein the latent curing agent contains an imidazole-based latent curing agent and an amine-based latent curing agent Provide a film.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

In the anisotropic conductive adhesive film of the present invention, an imidazole-based latent curing agent and an amine-based latent curing agent are used together as a latent curing agent.

Here, as the imidazole-based latent curing agent, a conventionally known imidazole-based latent curing agent can be used, but among them, a microencapsulated imidazole-based latent curing agent is preferably used. it can. As such a microencapsulated imidazole-based latent curing agent, imidazole-based latent curing agent which is microencapsulated by adducting imidazole with urea or an isocyanate compound, and further blocking its surface with an isocyanate compound, and particularly imidazole. An imidazole-based latent curing agent that is microencapsulated by adducting the above with an epoxy compound and blocking the surface thereof with an isocyanate compound can be preferably mentioned. Specifically, Novacure HX3941
HP, Novacure HX3921HP, Novacure HX3
721, Novacure HX3722, Novacure HX37
48, Novacure HX3088, Novacure HX374
1, Novacure HX3742, Novacure HX3613
(All manufactured by Asahi Kasei Co., Ltd.) and the like.

As the amine-based latent curing agent, a conventionally known amine-based latent curing agent can be used, and a polyamine-based latent curing agent (for example, H-4070) can be used.
S, H-3731S, etc., manufactured by ACR), tertiary amine-based latent curing agent (H3849S, etc., manufactured by ACR), alkylurea-based latent curing agent (eg, H-3366S, etc., AC
R company) can be used.

The amount of the imidazole-based latent curing agent used is
If the amount of the imidazole-based latent curing agent is too small, the heat resistance decreases and the conduction reliability deteriorates. If the amount is too large, the peel strength after heating and pressurizing decreases and the storage stability deteriorates. With respect to 100 parts by weight, preferably 7.5-2
7.5 parts by weight, more preferably 10 to 25 parts by weight. Also, if the amount of the amine-based latent curing agent used is too small, the peel strength after heating and pressing will be reduced, and the conduction reliability will be poor, and if it is too large, the storage stability will be poor. It is preferably 25 to 55 relative to 100 parts by weight of the agent.
By weight, more preferably 25 to 45 parts by weight.

The content of the latent curing agent, which is a combination of the imidazole-based latent curing agent and the amine-based latent curing agent, in the anisotropic conductive adhesive film is generally 20 to 7.
It is used in an amount of 0% by weight, preferably 20 to 50% by weight.

As the thermosetting insulating adhesive used in the present invention, an epoxy resin which is solid at room temperature can be used as in the case of the conventional anisotropic conductive film. If necessary, a liquid epoxy resin at room temperature can be used together. Such an epoxy resin that is solid at room temperature has an epoxy equivalent (g / ep) of 1000 to 500.
No. 0 BPA (bisphenol A) type epoxy resin can be preferably used, specifically, EP1010.
(3000-5000g / ep), EP1009 (2400
~ 3300 g / ep), EP1007 (1750-2200)
g / ep) (all manufactured by Yuka Shell Epoxy Co., Ltd.) and the like can be used. Further, as the epoxy resin which is liquid at room temperature, BPA type epoxy resin having an epoxy equivalent (g / ep) of 180 to 200 can be preferably used, and specifically, EP828 (190 g / ep) or the like is used. be able to.

The mixing ratio of the liquid epoxy resin to the solid epoxy resin at room temperature can be appropriately determined according to the performance required for the anisotropic conductive adhesive film.

When the flexibility of the film made of the solid or liquid epoxy resin as described above is further improved, and thereby the peel strength of the anisotropic conductive adhesive film is further improved, those It is particularly preferable to use a flexible epoxy resin in combination with the epoxy resin. In this case, when the content of the flexible epoxy resin in the thermosetting insulating adhesive is too small, the effect of adding the flexible epoxy resin cannot be sufficiently obtained, and when it is too large, the heat resistance is low. Therefore, the amount is preferably 5 to 35% by weight, more preferably 5 to 25% by weight.

As such a flexible epoxy resin,
Epoxy equivalents (g / ep) of 300 to 700 BPA type side chain type epoxy resin can be preferably used, specifically, EP4000 (310 to 340 g / ep), EP400.
5 (475-575 g / ep) (all manufactured by Asahi Denka Co., Ltd.), R
80 (320 g / ep), R1307 (630 g / ep) (all manufactured by ACR) and the like can be preferably used.
Among them, R80 BPA side chain type epoxy resin having the chemical structure of formula (1) can be preferably used.

[0022]

Embedded image (In the formula, n and m are the number of repetitions of the propylene oxide unit.)

The conductive particles used in the present invention can be appropriately selected and used from the materials conventionally used in anisotropic conductive adhesive films, for example, solder particles, nickel particles and the like. The metal particles described above, composite particles such as styrene resin particles having a gold-plated coating formed on the surface thereof, and the like can be used, and the particle size can be appropriately determined.

In the anisotropic conductive adhesive film of the present invention, if necessary, known additives, such as isocyanate cross-linking agents and epoxysilane compounds, which are compounded in conventional anisotropic conductive adhesive films, are added. A thermosetting insulating resin such as a coupling agent, an epoxy-modified silicone resin, or a phenoxy resin can be added.

The anisotropic conductive adhesive film of the present invention can be manufactured by a conventional method. For example, a thermosetting insulating adhesive, a latent curing agent, conductive particles, and optionally other additives are uniformly dispersed in a solvent such as toluene or ethyl acetate, and the dispersion is used as a release substrate (for example, It can be produced by applying a film on a (polyester sheet) and drying.

As described above, in the anisotropic conductive adhesive film of the present invention, an imidazole-based latent curing agent and an amine-based latent curing agent are used together as a latent curing agent. Therefore, the imidazole-based latent curing agent can contribute to the curing reaction even at a curing temperature of about 130 ° C., and the peel strength can be improved while ensuring the conductive reliability of the anisotropic conductive adhesive film. Also, by using a flexible epoxy resin as a part of the thermosetting insulating adhesive,
It is possible to further improve the peel strength.

[0027]

The present invention will be described below in more detail with reference to examples.

Examples 1 to 12 and Comparative Examples 1 to 2 Thermosetting insulating adhesive components and latent curing agents shown in Tables 1 and 2 were mixed with a toluene / ethyl acetate mixed solvent (1/1).
(Weight ratio)) to a solid content of 60% by weight, and conductive particles were added to the solution and mixed uniformly to prepare a composition for forming an anisotropic conductive adhesive film.

The composition for forming an anisotropic conductive adhesive film thus obtained was coated on a release film made of polyethylene terephthalate so as to have a dry thickness of 20 μm, and the composition was heated at 60 ° C. for 5 minutes.
An anisotropic conductive adhesive film was produced by drying for minutes.

[0030]

[Table 1] Blending amount (parts by weight) Example component 1 2 3 4 5 6 7 Thermosetting insulating adhesive component Room temperature solid epoxy resin * 1 50 ← ← ← ← 40 30 50 50 Room temperature liquid epoxy resin * 2 20- − − − − − Flexible epoxy resin * 3 − − − − − − − Flexible epoxy resin * 4 20 30 20 10 10 ← ← 20 Latent curing agent Imidazole based latent curing agent * 5 15 30 45 60 75 90 45 Amine-based latent curing agent * 6 40 ← ← ← ← ← 20 Conductive particles * 7 10 ← ← ← ← ← ←

[0031]

[Table 2] Blending amount (parts by weight) Example Comparative Example Component 8 9 10 11 12 12 1 2 Thermosetting insulating adhesive component Room temperature solid epoxy resin * 1 50 ← ← ← ← ← 60 40 Room temperature liquid epoxy resin * 2 − − − − 20 − − Flexible epoxy resin * 3 − − − 20 − − − Flexible epoxy resin * 4 20 ← ← − − − 20 Latent curing agent Imidazol type latent curing agent * 5 45 ← ← ← ← 60 ← Amine latent curing agent * 6 30 50 50 60 40 40 − − Conductive particles * 7 10 ← ← ← ← ← ← ← (Table 1 and Table 2 Note) Room temperature solid epoxy resin * 1; EP1009 (2400-3300g) / ep), Yuka Shell Epoxy Co., Ltd. room temperature liquid epoxy resin * 2; EP828 (190g / ep), Yuka Shell Epoxy Company flexible epoxy resin * 3; R80 (320g / ep), ACR Company flexible epoxy resin * 4; R1307 (630g / ep), ACR Imidazole latent curing agent * 5; HX3941P (hardener component / epoxy component = 1/2 weight ratio), Asahi Kasei Amine latent curing agent * 6; H4070S, ACR conductive particles * 7; 5% crosslinked polystyrene ( Ni / Au plating, 8 μm)

(Evaluation) The anisotropic conductive adhesive film obtained was tested and evaluated for peel strength (gf / cm), conduction reliability and storage stability as shown below.

Peel strength test 0.2 mm pitch TAB (Upilex 75 μm,
Copper foil 35μm / tin plating) and 10Ω on glass substrate
/ □ sandwiching an anisotropic conductive adhesive film between the ITO solid electrode, and thermocompression bonding under the condition that ^{130 ℃ / 5kgf / cm 2/} 20 sec. And, TAB 90 degrees from the glass substrate
Was peeled off at a speed of 50 mm / min, the force required for peeling was measured, and the peel strength was evaluated according to the following criteria. Table 3 shows the results.

Peel Strength Evaluation Standard Rank State ◎: Peeling force of 500 gf / cm or more ○: Peeling force of 300 gf / cm or more and 500 gf / cm or less ×: Peeling force of less than 300 gf / cm

Continuity reliability test Similar to the peel strength test, the anisotropic conductive adhesive film was used for thermocompression bonding between the TAB and the ITO solid electrode on the glass substrate, immediately after thermocompression bonding (initial) and at 85 ° C / 85% RH
/ 1000 hours after aging, the resistance value between the TAB and the ITO solid electrode was measured, and the conduction reliability was evaluated according to the following evaluation criteria. Table 3 shows the results.

Continuity reliability evaluation standard rank State ◎: When the initial resistance value is 20Ω or less and the resistance value after aging is less than twice the initial resistance value ◯: The initial resistance value is 20Ω or less and the resistance after aging When the value is 2 times or more and less than 3 times the initial resistance value Δ: When the initial resistance value is 20Ω or less and the resistance value after aging is 3 times or more and less than 5 times the initial resistance value ×: The initial resistance value is 20Ω or more or resistance after aging is 5 times or more than the initial value

Storage stability test Peel strength was measured when the above-mentioned peel strength test and continuity reliability test were conducted after leaving the anisotropic conductive adhesive film before curing (unused) in an atmosphere of 40 ° C. The test and the continuity reliability test results were evaluated for the standing period for which the result was ⊚ or ◯, and evaluated according to the following evaluation criteria. Table 3 shows the results.

Storage stability evaluation standard rank state ⊚: When the standing period for which the evaluation results of the peel strength test and the continuity reliability test are ◎ or ○ exceeds 3 weeks ○: The peel strength test and the continuity reliability test If the evaluation period is ◎ or ○ for more than 2 weeks. ×: If the peel strength test and continuity reliability test are ◎ or ○ for less than 1 week.

[0039]

[Table 3]

As is clear from Table 3, as compared with the anisotropic conductive adhesive film of Comparative Example 1 in which neither the amine-based latent curing agent nor the flexible epoxy resin was used, the flexible epoxy resin was not used but the amine-based adhesive film was used. The anisotropic conductive adhesive film of Example 12, in which the latent curing agent was used in addition to the imidazole-based latent curing agent, had improved peel strength while maintaining good conduction reliability and storage stability.

The anisotropic conductive adhesive films of Examples 1 to 11 in which a flexible epoxy resin was further used in the anisotropic conductive adhesive film of Example 12 were further improved in peel strength.

Incidentally, the anisotropic conductive adhesive film of Comparative Example 2 using the flexible epoxy resin without using the amine-based latent curing agent had insufficient peel strength as before.

[0043]

EFFECTS OF THE INVENTION The anisotropic conductive adhesive film of the present invention uses a high temperature curing type imidazole-based latent curing agent capable of imparting excellent heat resistance to the anisotropic conductive adhesive film as a curing agent. Even when it is cured at a low temperature, excellent peel strength and connection reliability can be realized.

Claims (5)

[Claims] 1. An anisotropic conductive adhesive film containing a thermosetting insulating adhesive, conductive particles and a latent curing agent, wherein the latent curing agent is an imidazole-based latent curing agent and an amine-based latent curing agent. An anisotropic conductive adhesive film containing. 2. A thermosetting insulating adhesive containing 100 parts by weight of an imidazole-based latent curing agent in an amount of 7.5 to 27.5 parts by weight and an amine-based latent curing agent in an amount of 25 to 55 parts by weight. Item 2. The anisotropic conductive adhesive film according to item 1. 3. The anisotropic conductive adhesive film according to claim 1, wherein the thermosetting insulating adhesive contains a flexible epoxy resin. 4. The anisotropic conductive adhesive film according to claim 3, wherein the content of the flexible epoxy resin in the thermosetting insulating adhesive is 5 to 35% by weight. 5. The flexible epoxy resin is bisphenol A.
The anisotropic conductive adhesive film according to claim 3, which is a side chain type epoxy resin.