JP2000040542A - Anisotropic conductive film and electrode connection structure using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a film thickness required for compression bonding by preventing the degradation of the film thickness due to the influence of heat and pressure in transferring an anisotropic conductive film. SOLUTION: This anisotropic conductive film 1 is composed by mixing, in a binder resin 2, conductive particles 3 and insulating particles 4 each of which has a particle diameter larger than that of the conductive particles 3 and with which the elasticity lowering temperature is low. The particle diameter of each of the insulating particles 4 is around 0.7-1 time as much as the film thickness of the anisotropic conductive film 1. The glass transition point of the insulating particles 4 is smaller than that of the conductive particles 3. The film thickness not less than the particle diameter of each of the insulating particles 4 can be retained after transferring, and the film thickness required for compression bonding can be secured. In addition, the insulating particles 4 are easily flattened when compression-bonded, electrodes are electrically connected by the conductive particles 3. Additionally, the insulating particles 4 reside between electrodes adjacent to each other, so that a short circuit caused by the communication of the conductive particles 3 can be prevented. An electrode connection structure having high electrical connection reliability can also be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anisotropic conductive film for electrically connecting electrodes arranged opposite to each other and an electrode connection structure using the conductive film.

[0002]

2. Description of the Related Art Anisotropic conductive films are used, for example, to connect a liquid crystal driver and peripheral members in a liquid crystal display device, particularly to connect a liquid crystal panel to a liquid crystal driver LSI (integrated circuit), or to connect a wiring substrate to a liquid crystal driver. It is used for connection of a high-definition counter electrode, such as for connection to an LSI.

FIG. 4 shows a prior art anisotropic conductive film 21.
FIG. The anisotropic conductive film 21 is formed by mixing at least conductive particles 23 with a binder resin 22.
No. 59268 discloses that the binder resin 22 contains the conductive particles 2.
An anisotropic conductive film 21 comprising a mixture of the insulating particles 3 and insulating particles 24 is disclosed.

Japanese Patent Application Laid-Open No. Hei 5-174618 aims to prevent a short circuit between adjacent electrodes.
The conductive particles 23 are formed by coating a surface of a core made of resin fine particles such as an acrylic resin with a conductive film made of a metal such as gold, silver, copper, nickel and aluminum by plating or vapor deposition. The insulating particles 24 include the conductive particles 2
It is harder than 3, and is made of a spherical or cylindrical material made of glass, hard resin, or the like. Also, the insulating particles 24
Is smaller than the particle size of the conductive particles 23, for example, the particle size of the conductive particles 23 is about 5 to 15 μm, and the particle size of the insulating particles 24 is about 3 to 8 μm.

In Japanese Patent Application Laid-Open No. 6-59268, 100
It is an object of the present invention to improve the reliability of electrical connection between electrodes arranged oppositely at a fine terminal pitch of μm or less.
The thickness of the binder resin 22 is 15 to 30 μm. The conductive particles 23 are obtained by applying nickel-gold plating having a thickness of about 0.1 μm to the surface of polystyrene particles having a particle diameter of about 3 to 8 μm. The insulating particles 24 are particles made of the polystyrene particles, a phenolic resin, or a polystyrene butadiene polymer.

[0006] Japanese Patent Application Laid-Open No. Hei 5-347664 also discloses an anisotropic conductive film 21 obtained by mixing conductive particles 23 and insulating particles 24 in a binder resin 22.

[0007] All such anisotropic conductive films 21 are formed on a separator. On the other hand, the anisotropic conductive film 21 is placed on the electrode so that the electrode and the anisotropic conductive film 21 are in contact with each other.
Is formed, and heat and pressure are applied through the separator to separate the separator, whereby the anisotropic conductive film 21 is transferred onto the one electrode. Further, the other electrode is arranged on the anisotropic conductive film 21 in alignment with the one electrode, and the electrodes are electrically connected by pressure bonding.

[0008]

When the fluidity of the anisotropic conductive film 21 is increased by the heat and pressure applied during transfer and the film thickness is reduced, the adhesion is reduced due to insufficient filling of the binder resin 22. . Further, the number of conductive particles on the electrode is reduced. Therefore, the reliability of connection of the electrode after crimping is reduced. In order to prevent the reliability of electrode connection from decreasing,
It is preferable that the transfer of the anisotropic conductive film 21 be performed at as low temperature and pressure as possible. However, depending on the material and surface condition of the electrode to be adhered and its peripheral portion, transfer may be performed only at high temperature and high pressure, and in this case, the above-described connection reliability has a problem.

In JP-A-5-174618 and JP-A-6-59268, the particle size of the insulating particles 24 is smaller than or equal to the particle size of the conductive particles 23. Therefore, when transferring at high temperature and high pressure depending on the material and surface condition of the electrode and its peripheral part, the thickness of the anisotropic conductive film 21 becomes thin, and the connection reliability decreases. Also, the anisotropic conductive film 21 disclosed in Japanese Patent Application Laid-Open No.
The object of the present invention is to prevent the destruction of conductive particles when an anisotropic conductive film is arranged between electrodes arranged to face each other and the electrodes are connected by pressure bonding.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce a decrease in film thickness due to the influence of heat and pressure during transfer of an anisotropic conductive film, secure a film thickness necessary for pressure bonding, and provide a high reliability for electrical connection of electrodes. And an electrode connection structure using the same.

[0011]

The present invention is characterized in that conductive particles and insulating particles having a particle size larger than the conductive particles and a temperature at which the elastic modulus is lowered are mixed in a binder resin. Is an anisotropic conductive film.

According to the present invention, the binder resin contains a mixture of conductive particles and insulating particles having a particle diameter larger than the conductive particles and having a lower elastic modulus lowering temperature than the conductive particles. A conductive film is formed. The thickness of the anisotropic conductive film is maintained to be equal to or larger than the diameter of the insulating particles even when heat and pressure are applied during transfer. Therefore, it is possible to prevent a decrease in the film thickness of the anisotropic conductive film and to secure a film thickness necessary for pressure bonding.

Further, the electrical connection of the electrodes using the anisotropic conductive film is performed by transferring the anisotropic conductive film onto one of the electrodes, arranging the other electrode, and crimping.
During crimping, the insulating particles are easily flattened without hindering the electrical connection of the electrodes by the conductive particles. Further, the insulating particles exist between the adjacent electrodes, thereby preventing a short circuit caused by the conductive particles communicating with each other.

Further, according to the present invention, the insulating particles preferably have a particle diameter of:
The thickness is selected to be about 0.7 to 1 times the thickness of the anisotropic conductive film.

According to the present invention, by setting the particle size of the insulating particles to about 0.7 to 1 times the thickness of the anisotropic conductive film,
The thickness of the anisotropic conductive film is reliably maintained at the time of transfer to be equal to or larger than the particle size of the insulating particles. Therefore, a decrease in the thickness of the anisotropic conductive film can be reliably prevented.

Further, the present invention is characterized in that the glass transition point of the insulating particles is smaller than the glass transition point of the conductive particles.

According to the present invention, by making the glass transition point of the insulating particles smaller than the glass transition point of the conductive particles, the insulating particles do not hinder the electrical connection of the electrodes by the conductive particles at the time of pressure bonding. Flatten easily.

Further, according to the present invention, one of the above-described anisotropic conductive films is interposed between a pair of electrodes arranged to face each other, and the pair of electrodes are electrically connected to each other. An electrode connection structure characterized in that:

According to the present invention, it is possible to provide an electrode connection structure with high electrical connection reliability.

[0020]

FIG. 1 is a sectional view showing an anisotropic conductive film 1 according to an embodiment of the present invention. The anisotropic conductive film 1 includes conductive particles 3 and insulating particles 4 in a binder resin 2.
And are mixed. The insulating particles 4 have a larger particle diameter than the conductive particles 3 and have a lower elastic modulus lowering temperature than the conductive particles 3.

In particular, the particle diameter of the insulating particles 4 is preferably selected to be about 0.7 to 1 times the thickness of the anisotropic conductive film 1. The temperature at which the modulus of elasticity decreases is, for example, the glass transition point Tg, and the glass transition point Tgi of the insulating particles 4 is
Is preferably smaller than the glass transition point Tgc.

As the binder resin, for example, an epoxy resin can be used. Further, as the conductive particles 3, those obtained by plating nickel-gold on plastic particles can be used. Further, as the insulating particles 4,
Plastic beads can be used. These components are formed by a known technique, for example, Japanese Patent Application Laid-Open No. 5-1746.
18, JP-A-6-59268, and JP-A-5-34764.

FIG. 2 is a sectional view showing a method and structure for connecting electrodes using the anisotropic conductive film 1. Anisotropic conductive film 1
Is formed on the separator 5. As shown in FIG. 2 (A), for example, on one electrode 6, the anisotropic conductive film 1
Is formed. Next, heat and pressure are applied via the separator 5 and the separator 5 is peeled off, whereby the anisotropic conductive film 1 is transferred onto the one electrode 6. Further, as shown in FIG. 2 (B), the other electrode 7 is arranged on the anisotropic conductive film 1 in alignment with the one electrode 6. Next, FIG.
As shown in (C), electrodes 6 and 7 are electrically connected to each other via conductive particles.

In the binder resin 2, conductive particles 3 and insulating particles 4 having a larger particle diameter than the conductive particles 3 and having a lower elastic modulus lower than the conductive particles 3 are formed. The film thickness of the anisotropic conductive film 1 is maintained to be equal to or larger than the particle size of the insulating particles 4 even when heat and pressure are applied during transfer. Therefore, it is possible to prevent a decrease in the film thickness of the anisotropic conductive film 1 and to secure a film thickness necessary for pressure bonding.

The electrodes 6 and 7 using the anisotropic conductive film 1
The electrical connection between them is performed by transferring the anisotropic conductive film 1 on one electrode 6, further arranging the other electrode 7 and crimping. At the time of pressure bonding, the insulating particles 4
The flattening can be easily performed without hindering the electrical connection between the electrodes 6 and 7 by the conductive particles 3. Furthermore, the insulating particles 4 also exist between the adjacent electrodes 6 and between the adjacent electrodes 7, thereby preventing a short circuit caused by the conductive particles 3 communicating with each other. Therefore, the reliability of the connection structure between the electrodes 6 and 7 can be improved.

By setting the particle size of the insulating particles 4 to about 0.7 to 1 times the thickness of the anisotropic conductive film 1, the film thickness of the Is surely maintained at a particle diameter of at least. Therefore, a decrease in the thickness of the anisotropic conductive film 1 can be reliably prevented.

Further, by making the glass transition point of the insulating particles 4 smaller than the glass transition point of the conductive particles 3, the insulating particles 4 do not hinder the electrical connection between the electrodes 6 and 7 by the conductive particles 3 at the time of pressing. Flatten easily without coming. Therefore, the reliability of the connection structure between the electrodes 6 and 7 can be improved.

The pair of electrodes 6 and 7 are electrically connected to each other with the anisotropic conductive film 1 described above interposed between the pair of electrodes 6 and 7 disposed opposite to each other. Thereby, a highly reliable connection structure of the electrodes 6 and 7 for electrical connection can be provided.

FIG. 3 shows an electrode 1 of a pair of substrate members 8 and 11 for a liquid crystal element using an anisotropic conductive film 1.
It is sectional drawing which shows the method and structure which electrically connect 0,13 mutually. FIG. 3A shows a state before crimping, and FIG.
(B) shows the state after crimping. One substrate member 8 is formed by forming an electrode 10 on a substrate 9 for a liquid crystal element. The carrier tape 11, which is the other substrate member 11,
For example, the electrode 13 is formed on a flexible substrate 12 having a liquid crystal driver LSI.

The temperature conditions for connecting the electrodes 10 and 13 are generally set to 100 ° C. or less during the transfer of the anisotropic conductive film 1 and set to 160 ° C. or more during the pressure bonding. Glass transition point Tg of conductive particles 3 and insulating particles 4
c and Tgi are both selected to be lower than the pressing temperature.
In addition, the glass transition point Tgi of the insulating particles 4 is selected to be lower than the glass transition point Tgc of the conductive particles 3. For example, the glass transition point Tgc of the conductive particles 3 was set to 155 ° C., and the glass transition point Tgi of the insulating particles 4 was set to 150 ° C.

Generally, the thickness of the anisotropic conductive film 1 is selected in the range of 15 μm to 40 μm, the particle size of the conductive particles 3 is selected in the range of 3 μm to 10 μm, and the particle size of the insulating particles 4 is selected. Is selected to be 0.7 to 1 times the thickness of the anisotropic conductive film 1. For example, the film thickness of the anisotropic conductive film 1 is 20 μm, the particle size of the conductive particles 3 is 5 μm, and the particle size of the insulating particles 4 is 1 μm.
Each was selected to 5 μm.

As shown in FIG. 3 (A), when the film is heated to 100 ° C. during the transfer of the anisotropic conductive film 1, the thickness of the anisotropic conductive film 1 after the transfer is insulative regardless of the characteristics of the binder resin 2. The particle 4 can be maintained at a particle diameter of 15 μm or more. Therefore, it is possible to prevent a decrease in the film thickness of the anisotropic conductive film 1 and to secure a film thickness necessary for pressure bonding.

As shown in FIG. 3B, when the anisotropic conductive film 1 is heated to 200 ° C. during compression bonding, the anisotropic conductive film 1 having a sufficient thickness is And between the substrates 9 and 12. Thereby, the one substrate member 8 and the carrier tape 11 are provided with high adhesion.
And can be connected. Further, since the insulating particles 4 filled between the electrodes 10 and 13 are easily deformed, the electrodes 10 and 13 can be reliably electrically connected to each other via the conductive particles 3. Furthermore, since the insulating particles 4 exist between the adjacent electrodes 10 and between the electrodes 13, the communication of the conductive particles 3 can be prevented, and the occurrence of a short circuit can be prevented.
In this manner, an electrode connection structure with high electrical connection reliability can be provided.

According to the present embodiment, it is possible to prevent the transfer failure in the mounting process of the anisotropic conductive film 1 and to improve the reliability of the electrode connection. In the prior art, transfer was performed at low temperature and low pressure in order to ensure connection reliability. Therefore, the anisotropic conductive film could not be reliably transferred to the adherend, resulting in transfer failure and time-consuming transfer. On the other hand, according to the anisotropic conductive film 1 of the present embodiment, transfer at high temperature and high pressure is possible, transfer failure can be prevented, and transfer can be performed in a short time. Further, even when the balance between the temperature and the pressure of the transfer heating means is lost, the anisotropic conductive film 1
It is possible to prevent the occurrence of connection failure due to the thin film thickness of the semiconductor device. Further, as the properties of the binder resin used for the anisotropic conductive film 1, there is no need to limit initial adhesiveness and fluidity at about 100 ° C., and the degree of freedom in selection is increased. Accordingly, it is possible to realize the anisotropic conductive film 1 having characteristics such as low-temperature curing and high-speed curing.

The anisotropic conductive film of the present invention is not limited to the connection between the liquid crystal substrate member 8 and the carrier tape 11 described with reference to FIG. The connection, the connection between the liquid crystal substrate member and the bare chip, the connection between the bare chip and the printed wiring board, and the connection between the printed wiring board and the carrier tape are also included in the scope of the present invention. The same effect as described can be obtained.

[0036]

As described above, according to the present invention, conductive particles and insulating particles having a larger particle diameter than the conductive particles and a lowering temperature of the elastic modulus than the conductive particles are contained in the binder resin. Since the anisotropic conductive film is formed as a mixture, the film thickness can be maintained to be equal to or larger than the diameter of the insulating particles after the transfer, and the film thickness required for pressure bonding can be secured. In addition, the insulating particles are easily flattened during crimping, and the electrodes are electrically connected by the conductive particles. Further, since the insulating particles exist between the adjacent electrodes, it is possible to prevent a short circuit caused by the communication of the conductive particles.

Further, according to the present invention, the particle diameter of the insulating particles is set to about 0.7 to 1 times the film thickness of the anisotropic conductive film. Thus, the thickness of the anisotropic conductive film can be reliably prevented from being reduced.

According to the present invention, the glass transition point of the insulating particles is made smaller than that of the conductive particles.
The insulating particles are easily flattened at the time of pressure bonding, the electrodes are reliably electrically connected by the conductive particles, and the reliability of the electrode connection structure is improved.

Further, according to the present invention, it is possible to provide an electrode connection structure with high electrical connection reliability.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view showing a method and a structure of electrode connection using an anisotropic conductive film 1;

FIG. 3 is a cross-sectional view showing a method and a structure for electrically connecting electrodes 10 and 13 of a pair of substrate members 8 and 11 for a liquid crystal element using an anisotropic conductive film 1, respectively.

FIG. 4 is a cross-sectional view showing a conventional anisotropic conductive film 21.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anisotropic conductive film 2 Binder resin 3 Conductive particle 4 Insulating particle 6,7,10,13 Electrode 8 Substrate member 9,12 Substrate 11 Carrier tape

Continued on the front page F term (reference) 5E319 AC02 BB16 CC12 5E344 AA04 AA21 BB02 BB13 CC23 CD04 CD31 DD06 DD08 DD10 EE06

Claims (4)

[Claims] 1. An anisotropic conductive film comprising a binder resin and a mixture of conductive particles and insulating particles having a larger particle diameter than the conductive particles and a lower temperature at which the elastic modulus is lowered. 2. The anisotropic conductive film according to claim 1, wherein the particle size of said insulating particles is selected to be about 0.7 to 1 times the thickness of said anisotropic conductive film. 3. The anisotropic conductive film according to claim 1, wherein the glass transition point of the insulating particles is smaller than the glass transition point of the conductive particles. 4. A pair of said electrodes are electrically connected to each other with an anisotropic conductive film according to claim 1 interposed between a pair of electrodes arranged to face each other. An electrode connection structure, characterized in that: