JPH09199206A - Anisotropic conductive bonding film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anisotropic conductive bonding film which can collectively connect a plurality of connection means without deteriorating reliability of continuity. SOLUTION: In an anisotropic conductive bonding film 1 dispersing a conductive particle 3 in an insulation bonding agent resin 2, the conductive particle 3, having 7.0kgf/mm<2> of less compression strength at 10% compression displacement also a 10% or more recovery factor at compression displacement is used. As the conductive particle 3, for instance, with a resin particle 3a, composed of an aliphatic acrylate cross-linked unit, serving as a uncles, applying to its surface of metal plating 3b is used. In this way, even in the case of generating dispersion in a space between terminals caused by a difference of thickness between connection means of TAB film or the like, electrical connection between the terminals can be sufficiently performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anisotropic conductive adhesive film used for electrical connection between a liquid crystal display device (LCD) and a circuit board, for example.

[0002]

2. Description of the Related Art Conventionally, an anisotropic conductive adhesive film has been used as a means for connecting a liquid crystal display device to an integrated circuit board or the like. This anisotropic conductive adhesive film is used, for example, in flexible printed circuit boards (FPC) and T
AB (Tape Automated Bondin)
g) The terminals of the connecting means such as a film and the ITO (Indium Tin) formed on the glass substrate of the LCD panel.
It is used for bonding various terminals and for electrically connecting them, including the case of connecting the terminals of an oxide electrode.

Generally, an anisotropic conductive adhesive film is constructed by containing conductive particles in an insulating adhesive resin. In this case, an epoxy thermosetting resin is mainly used as the insulating adhesive resin, and the resin contains a coupling agent, a curing agent, and the like. Further, as the conductive particles,
For example, metal particles or resin particles plated, etc. are used. Conventionally, the connection between terminals by such an anisotropic conductive adhesive film is performed by disposing the anisotropic conductive adhesive film on the terminals of the substrate to be connected, and then TAB.
The connecting means such as a film is thermocompression-bonded one by one.

[0004]

By the way, in recent years, LC
Due to the necessity of improving the production efficiency of D and the like, a process of arranging a plurality of connecting means on a substrate and collectively thermocompressing them has been proposed. However, when a plurality of connecting means are collectively thermocompression bonded by using the conventional anisotropic conductive adhesive film, there is a problem in that conduction failure between terminals occurs. That is, in the conventional anisotropic conductive adhesive film, conductive particles that hardly deform when pressed, for example, metal particles, benzoguanamine, or divinylbenzene-based hard resin particles plated with metal are used. Therefore, due to the difference in the thickness of the connecting means such as each TAB film (for example, the base material, the pattern, the plating on the pattern, etc.), the spacing between the terminals varies (0.5
(about .mu.m) occurs, there is a problem that the conductive particles and the connection terminal do not come into sufficient contact with each other between the terminals having a wider distance, and the electrical connection between the terminals becomes insufficient. For such a problem, it is possible to use soft resin particles such as polystyrene plated with metal as the conductive particles, and to bring the terminals of the wider spacing closer by the deformation of the particles at the time of pressurization. However, when such particles are used, there is a problem in that the resin portion of the conductive particles undergoes plastic deformation after pressurization, so that the conduction resistance after aging increases.

The present invention has been made in order to solve the problems of the prior art as described above, and an anisotropic conductive adhesive film capable of collectively connecting a plurality of connecting means without impairing the conduction reliability. It is intended to provide.

[0006]

Means for Solving the Problems As a result of intensive studies for achieving the above object, the present inventors have found that in an anisotropic conductive adhesive film in which conductive particles are dispersed in an insulating adhesive, By making the compression strength of the particles at 10% compression displacement smaller than a predetermined value, and by making the recovery rate of the conductive particles at the compression displacement larger than a predetermined value,
It has been found that an anisotropic conductive adhesive film can be obtained in which a plurality of connecting means can be collectively connected without impairing conduction reliability.

The present invention has been completed based on such findings, and the invention according to claim 1 is an anisotropic conductive adhesive film in which conductive particles are dispersed in an insulating adhesive. The compressive strength of the particles at 10% compressive displacement is 7.0 kgf / mm ² or less.

In this case, it is more effective to set the compressive strength of the conductive particles at 10% compressive displacement to 5.0 kgf / mm ² or less.

On the other hand, as the insulating adhesive, for example, one containing a thermosetting resin such as an epoxy resin or a phenoxy resin as a main component and containing a coupling agent, a curing agent or the like can be used.

According to a second aspect of the present invention, in addition to the first aspect of the invention, the recovery rate when the conductive particles are compressed and displaced is 1.
0% or more.

In this case, it is more effective if the recovery rate of the conductive particles at the time of compressive displacement is 13% or more.

Further, the invention according to claim 3 is the invention according to claim 1.
Alternatively, in the invention described in item 2, the conductive particles are formed by forming a metal thin film on a core containing a polymer as a main component.

Further, like the invention described in claim 4, in the invention described in claim 3, it is also effective to use an aliphatic acrylate crosslinked product as a nucleus.

In the case of the invention according to claim 1 having such a constitution, in the anisotropic conductive adhesive film in which conductive particles are dispersed in an insulating adhesive, the compressive strength at 10% compression displacement is 7.0 kgf / mm ^2. Since the following conductive particles are used, for example, when the spacing between terminals varies due to the difference in the thickness of the connecting means such as the TAB film (base material, pattern, plating, etc.). Also, the conductive particles are deformed and crushed to some extent, and as a result, the conductive particles and the connection terminals are sufficiently brought into contact with each other between the terminals having the wider spacing, and electrical connection between the terminals is sufficiently performed.

Further, in the case of the invention described in claim 2, in the invention described in claim 1, since the recovery rate of the conductive particles at the time of compressive displacement is 10% or more, the conductive particles are repulsive. Since no plastic deformation occurs, the conduction resistance of the conductive particles does not increase so much even after aging.

Further, as in the invention described in claim 3, in the invention described in claim 1 or 2, the use of conductive particles obtained by forming a metal thin film on a core containing a polymer as a main component, particularly, As in the invention according to claim 4, by using conductive particles whose core is an aliphatic acrylate cross-linked product, conductive particles having a compressive strength at 10% compression displacement of 7.0 kgf / mm ² or less, and compressed particles Conductive particles having a recovery rate of 10% or more when displaced are easily obtained.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view showing a preferred embodiment of the anisotropic conductive adhesive film according to the present invention. As shown in FIG. 1, the anisotropic conductive adhesive film 1 of the present invention is formed on, for example, a release film (not shown), and contains conductive particles 3 in a film-like insulating adhesive resin 2. In this case, the insulating adhesive resin 2
For example, a material containing an epoxy resin, a phenoxy resin, or the like as a main component and a coupling agent, a curing agent, or the like can be used. Further, the content of the conductive particles 3 is preferably about 3 to 5% by weight. In addition, as a method of containing the conductive particles 3 in the insulating adhesive resin 2,
A known method can be used.

On the other hand, the conductive particles 3 of the present invention are composed of, for example, resin particles 3a as cores and metal plating 3b on the surface thereof. In this case, as the resin forming the resin particles 3a, an aliphatic acrylate crosslinked product or the like can be used. Further, as the metal plating 3b, nickel-gold plating or the like can be used.

[0019]

EXAMPLES Examples of the anisotropic conductive adhesive film according to the present invention will be described in detail below together with comparative examples.

[Preparation of Sample] First, an insulating adhesive resin having a compounding ratio shown in Table 1 below, that is, a binder was prepared.

[0021]

[Table 1]

To 100 parts by weight of the above binder, 5 parts by weight of conductive particles described below were mixed, and a mixed solvent of toluene and ethyl acetate (weight ratio 1: 1) was added so that the solid content was 60% by weight, and the binder was added. Use as a paste. Further, this binder paste is coated on a polyethylene terephthalate (PET) film for peeling so as to have a thickness after drying of 25 μm to obtain an anisotropic conductive adhesive film. This anisotropic conductive adhesive film was cut into slits having a width of 2 mm to obtain samples of the following examples and comparative examples.

[Example 1] Nickel-gold plating was applied to 100 parts by weight of a binder as resin particles having a cross-linked aliphatic acrylate as a base material (Micropearl AU-7082LL manufactured by Sekisui Fine Chemical Co., Ltd.) as conductive particles. 5 parts by weight of the applied product (average particle size 8.2 μm) was dispersed. The nickel plating had a thickness of 1000 Å and the gold plating had a thickness of 300 Å.

[Example 2] Nickel-gold plating was applied to 100 parts by weight of a binder, as conductive particles, resin particles based on a crosslinked aliphatic acrylate (manufactured by Sekisui Fine Chemical Co., Ltd., trade name Micropearl AU-2081M). 5 parts by weight of the applied product (average particle size 8.1 μm) was dispersed.

[Example 3] Nickel-gold plating was applied to 100 parts by weight of a binder, as conductive particles, resin particles based on a crosslinked aliphatic acrylate (manufactured by Sekisui Fine Chemical Co., Ltd., trade name Micropearl AU-2075L). 5 parts by weight of the applied product (average particle size 7.5 μm) was dispersed.

Comparative Example 1 100 parts by weight of a binder was coated with nickel-gold plating as conductive particles on resin particles based on divinylbenzene (trade name Micropearl AU-205 manufactured by Sekisui Fine Chemical Co., Ltd.). 5 parts by weight of (average particle size 5.0 μm) were dispersed.

[Comparative Example 2] Resin particles (manufactured by Sanno Co., Ltd.) based on 5% cross-linked polystyrene as conductive particles were plated with nickel-gold with respect to 100 parts by weight of binder (average particle diameter). 5 parts by weight of 8.0 μm) was dispersed.

Next, using the above-mentioned sample, the glass substrate and the TAB film were pressure-bonded by the following method. In this case, the thickness of the TAB film is 75μ.
A copper foil having a thickness of 35 μm, on which tin-plated patterns were formed at a pitch of 100 μm, was used on a base material made of polyimide of m. On the other hand, as a glass substrate,
An electrode having ITO formed on the entire surface and having a surface resistance of 10Ω / □ was used.

FIG. 2 is an explanatory view showing a pressure bonding method between the TAB film and the glass substrate. As shown in FIG. 2, the anisotropic conductive adhesive film 1 is formed in a slender shape on one long glass substrate 4, and the TAB film 5 (5a-5) is formed thereon.
5) e) are arranged in a horizontal line, and as shown in FIGS.
Thermocompression bonding was performed on the AB film 5 by the pressure bonding head 6. In this case, the width d of each TAB film 5a to 5e
Is 30 to 40 mm, and the TAB films 5a and 5 on both ends are
The distance D between the ends of e was 230 mm. The pressure bonding was carried out under the conditions of a temperature of 180 ° C., a pressure of 30 kgf / cm ² and 17 seconds.

Then, the continuity reliability of each of the samples thus prepared was measured. Table 2 shows the results. Further, under the same conditions, the TAB films 5 were thermocompression-bonded to the glass substrates 4 one by one, and the conduction reliability of each sample was measured. Table 2 shows the results.

[0031]

[Table 2]

Here, the conduction reliability is ◯ when the initial resistance value between the patterns is less than 20Ω, and x when the initial resistance value is 20Ω or more.
And On the other hand, regarding the conduction reliability after aging,
Measure the resistance value between the patterns after aging for 1000 hours under the condition of temperature of 85 ° C and relative humidity of 85%. ○ If resistance increase is less than 3 times the initial resistance value ○ ○, 3 times or more
And

As the physical properties of the conductive particles of each sample, 10% compressive strength and recovery rate were measured. Table 2 shows the results.

[Method of Measuring 10% Compressive Strength] First, conductive particles as spacers are scattered on a steel plate having a smooth surface, and one conductive particle is selected from them. Next, using a powder compression tester (MCTM200 manufactured by Shimadzu Corporation), the conductive particles are compressed with a smooth end surface of a diamond cylinder having a diameter of 50 μm. At this time, the compression load is electrically detected as an electromagnetic force, and the compression displacement is electrically detected as a displacement by the operating transformer. As a result, as shown in FIG. 3, the relationship between the compressive displacement of the conductive particles and the load is obtained. Then, the load value and the compressive displacement at 10% compressive deformation of the conductive particles are obtained respectively from FIG. 3, and the relationship between these values and the 10% compressive strength and compressive strain shown in FIG. 4 is obtained from the equation (1). However, the compressive strain is a value obtained by dividing the compressive displacement by the average particle diameter of the conductive particles and expressing it as a percentage.

S ₁₀ (10% compressive strength) = 2.8 P / πd ² (kgf / mm ² ) ... Formula (1) P: Load at 10% compressive displacement (kgf) d: Particle size of conductive particles (Mm)

The compression speed was a constant load speed compression method, and the load was increased at a rate of 0.27 gram weight per second (grf). The maximum test load was 10 grf and the measurement temperature was 20 ° C.

[Definition of Recovery Rate and Measuring Method] 10% mentioned above
Only by expressing the hardness of the conductive particles by the compressive strength, the material mechanical properties of the conductive particles which are fine particles cannot be completely defined. Another important property is the recovery rate after compressive deformation. By using this recovery rate, it is possible to quantitatively and uniquely express the elasticity or elastoplasticity of the conductive particles.

First, as in the case of 10% compressive strength, each conductive particle which is a spacer is sprinkled on a steel plate having a smooth surface, and one conductive particle is selected from them. next,
Using a powder compression tester (model Shimadzu MCTM200), the conductive particles are compressed with a smooth end surface of a diamond column having a diameter of 50 μm. At this time, the compression load is electrically detected as an electromagnetic force, and the compression displacement is electrically detected as a displacement by the operating transformer. Then, as shown in FIG. 5, after the conductive particles are compressed to the reversal load value (curve a in the figure), the load is decreased on the contrary (curve b in the figure), and the relationship between the load and the compression displacement. To measure. However, the end point in unloading is not the zero load value but the origin load value of 0.1 g. Then, the recovery rate is defined as a ratio of the displacement L ₁ to the point of reversal and the displacement difference L ₂ from the point of reversal to the point where the origin load value is taken, expressed as a percentage, as shown in equation (2). To do.

R (recovery rate) = (L ₂ / L ₁ ) × 100 (%) Equation (2)

In this case, the reversal load value is 1.
0 grf, origin load value is 0.1 grf, compression speed under load and unload is 0.27 grf / sec, measurement temperature is 20 ° C.
And

[Evaluation Results] As shown in Table 2, Example 1
The anisotropic conductive adhesive films Nos. 1 to 3 had good initial conductivity and showed little increase in resistance even after aging. Further, even when one TAB film 5 was pressure-bonded, no particular problem occurred.

FIG. 6 is a principle diagram showing the operation of Examples 1 to 3 of the present invention, and shows a state in which thermocompression bonding is performed by the pressure bonding head 6. As shown in FIG. 6, the conductive particles 3
In the anisotropic conductive adhesive films 1 of Examples 1 to 3 using the aliphatic acrylate cross-linked body as the base material of No. 3, the conductive particles 3 have a 10% compressive strength of 3.22 to 4.70 (kgf / mm ² ). Since it is smaller than the conventional one, the difference in the thickness of each TAB film 5a to 5c (base material, pattern, plating, etc.)
Variation in the spacing between terminals due to (maximum about 2 μm)
Even if the TAB film 5 is generated, the conductive particles 3 are deformed and are crushed to some extent, and as a result, the TAB film 5 having a wider space is formed.
The conductive particles 3 sufficiently come into contact with the connection terminal (not shown) of b, and the electric connection between the terminals is sufficiently made. In addition, in Examples 1 to 3, the recovery rate of the conductive particles 3 is as large as 13.7 to 49.2 (%), and the particles have a high resilience and do not cause plastic deformation. Resistance does not rise so much.

As shown in Table 2, in the anisotropic conductive adhesive film of Comparative Example 1 in which divinylbenzene was used as the base material of the conductive particles, when the TAB film 5 was collectively pressure-bonded, the initial space between the patterns was increased. The conductivity was poor, and the conductivity resistance after aging also increased.

FIG. 7 is a principle diagram showing the operation in Comparative Example 1, and shows a state in which thermocompression bonding is performed by the pressure bonding head 6. In the case of the anisotropic conductive adhesive film of Comparative Example 1, the 10% compressive strength of the conductive particles 11 is 8.88 (kgf / m
m ² ), the TAB film 5b having a larger distance is separated from the TAB film 5b having a larger distance when the distance between the terminals varies due to the difference in the thickness of the TAB films 5a to 5c as shown in FIG. The conductive particles 11 and the connection terminals (not shown) do not sufficiently contact each other between the connection terminals, and the electrical connection between the terminals becomes insufficient. As a result, an insulating binder is present between the conductive particles 11 and the connection terminal, so that the conduction resistance increases at the initial stage and after aging.

As shown in Table 2, in the case of the anisotropic conductive adhesive film of Comparative Example 2 in which 5% cross-linked polystyrene was used as the base material of the conductive particles, the initial conduction resistance was good, but after aging. Regarding the conduction resistance of, the resistance value between the patterns was increased not only when the pressure was applied collectively, but also when one TAB film 5 was pressure-bonded.

FIG. 8 is a principle view showing the operation in Comparative Example 2 of the present invention. As shown in FIG. 8, in the case of the anisotropic conductive adhesive film of Comparative Example 2, the 10% compressive strength of the conductive particles was as small as 2.22 (kgf / mm ² ), and the initial conduction resistance was good, The recovery rate is so soft that it cannot be measured, and the conductive particles 12 undergo plastic deformation, which increases the conduction resistance after aging. That is, when the conductive particles 12 are plastically deformed, the force for returning to the original state does not work and remains deformed, and heat and humidity are applied by aging to expand and contract, so that the contact portion between the conductive particles 12 and the pattern contacts. Becomes unstable and conduction resistance increases. On the other hand, as described above, in the case of the present invention, such a phenomenon can be avoided.

[0047]

As described above, according to the first aspect of the present invention, in the anisotropic conductive adhesive film in which the conductive particles are dispersed in the insulating adhesive, the compressive strength at 10% compression displacement is 7%. By using conductive particles having a weight of 0.0 kgf / mm ² or less, for example, even if the distance between the terminals varies due to the difference in the thickness of the connecting means such as the TAB film, the electrical characteristics between the terminals can be reduced. Various connections can be sufficiently performed, and as a result, it becomes possible to collectively connect a plurality of connecting means without impairing the conduction reliability.

Further, as in the invention described in claim 2, in the invention described in claim 1, the recovery rate at the time of compressive displacement is 10%.
By using the above conductive particles, it is possible to obtain an anisotropic conductive adhesive film having excellent conductive reliability of the conductive particles even after aging.

Further, as in the invention described in claim 3, in the invention described in claim 1 or 2, the use of conductive particles obtained by forming a metal thin film on a core containing a polymer as a main component, particularly, As in the invention according to claim 4, by using conductive particles whose core is an aliphatic acrylate cross-linked product, conductive particles having a compressive strength at 10% compression displacement of 7.0 kgf / mm ² or less, and compressed particles Conductive particles having a recovery rate upon displacement of 10% or more can be easily obtained, and as a result, the anisotropic conductive adhesive film according to the present invention can be easily produced.

[Brief description of drawings]

FIG. 1 is a sectional view showing a preferred embodiment of an anisotropic conductive adhesive film according to the present invention.

FIG. 2 is an explanatory diagram showing a pressure bonding method between a TAB film and a glass substrate.

FIG. 3 is a graph showing the relationship between the compressive displacement of conductive particles and the load.

FIG. 4 is a graph showing the relationship between the compressive strain of conductive particles and 10% compressive strength.

FIG. 5 is a graph for explaining the recovery rate of conductive particles.

FIG. 6 is a principle diagram showing an operation of Examples 1 to 3 of the present invention.

7 is a principle diagram showing an operation of Comparative Example 1. FIG.

FIG. 8 is a principle diagram showing an operation of Comparative Example 2.

[Explanation of symbols]

 1 Anisotropic Conductive Adhesive Film 2 Insulating Adhesive Resin 3 Conductive Particles 3a Resin Particles 3b Metal Plating 4 Glass Substrate 5 TAB Film 6 Crimping Head

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H01B 1/20 H01B 1/20 D 5/16 5/16 H01L 21/60 311 H01L 21/60 311W H01R 43/00 H01R 43/00 H

Claims (4)

[Claims] 1. An anisotropic conductive adhesive film in which conductive particles are dispersed in an insulating adhesive, wherein 1 of the conductive particles is used.
An anisotropic conductive adhesive film having a compressive strength at 0% compression displacement of 7.0 kgf / mm ² or less. 2. The anisotropic conductive adhesive film according to claim 1, wherein the recovery rate of the conductive particles upon compression displacement is 10% or more. 3. The conductive particles are formed by forming a metal thin film on a core containing a polymer as a main component.
The anisotropic conductive adhesive film described. 4. The anisotropic conductive adhesive film according to claim 3, wherein the core is a cross-linked aliphatic acrylate.