JP2009001628A5 - - Google Patents

Description

Anisotropic conductive adhesive

The present invention relates to an anisotropic conductive adhesive, and more particularly to an anisotropic conductive adhesive suitable for mounting a bumped IC chip having a wide width between electrodes.

In recent years, with the increasing market demand for higher functionality, lighter weight, thinner and smaller size, mainly for information terminal equipment, various methods for mounting bare chips directly on printed wiring boards and other substrates have been studied. Has been.

One of them is the anisotropic conductive film (ACF) in which an anisotropic conductive adhesive in which conductive particles are dispersed in a thermosetting adhesive is formed into a film, or an anisotropic conductive film prepared in a liquid form. There is a method using an electrically conductive paste (ACP). Of these, the product form of the film-like anisotropic conductive adhesive is usually the base film 2 like the anisotropic conductive adhesive 1 shown in FIGS. 4 (a) and 4 (b).
The anisotropic conductive film 4 is laminated on the top and wound around a reel. Here, FIG. 4A is a plan view of a conventional anisotropic conductive adhesive, and FIG. 4B is a cross-sectional view taken along line AA.

5A and 5B are cross-sectional views showing a mounted state of an IC chip using the anisotropic conductive adhesive 1 described above. The anisotropic conductive film 4 contains conductive particles in an insulating resin (not shown). Bumps 22 are formed on the IC chip 20, and electrodes 32 are formed on the glass substrate 30.
When mounting the IC chip, the anisotropic conductive film 4 is attached to the electrode 32 on the glass substrate 30 as shown in FIG. At this time, the bumps 22 of the IC chip 20 are aligned and temporarily fixed so as to correspond to the electrodes 32 on the glass substrate 30. Thereafter, thermocompression bonding is performed, and the IC chip 20 is mounted on the glass substrate 30 (FIG. 5B).
When the thermocompression bonding is performed, the resin of the anisotropic conductive film 4 flows in the direction indicated by the arrow in FIG. 5A, a part of the resin fills the inside of the IC chip 20, and the IC chip 20 is bonded to the glass substrate 30. . At this time, the resin between the bump 22 and the electrode 32 is excluded, and the conductive particles in the anisotropic conductive film 4 are captured between the bump 22 and the electrode 32. Thereby, conduction is ensured between the bump 22 and the electrode 32.

However, as shown in FIG. 5A, in the conventional anisotropic conductive film 4, the resin flow direction is limited to the outside of the IC chip 20 when thermocompression bonding is performed. For this reason, particularly in a system having a high reaction rate (curing rate) such as an onium salt-epoxy curing system, the curing proceeds without sufficiently removing the resin interposed between the bump 22 and the electrode 32. As a result, a phenomenon that the conductive particles in the anisotropic conductive film 4 cannot be captured well between the bumps 22 and the electrodes 32 occurs particularly when an IC chip having a wide width between the electrodes is mounted. For this reason, there is a problem in that sufficient conduction reliability between the bumps 22 and the electrodes 32 cannot be obtained after thermocompression bonding (FIG. 5B).

An object of this invention is to provide the anisotropic conductive adhesive with high conduction | electrical_connection reliability between the electrodes to connect.

According to the present invention, the following anisotropic conductive adhesive is provided.
1. A base film and an anisotropic conductive film in which conductive particles are dispersed in an insulating adhesive are laminated on the base film, and the anisotropic conductive film is formed with a space extending in the longitudinal direction. One way conductive adhesive.
2. An anisotropic conductive adhesive in which the space extends in the longitudinal direction at substantially the center in the width direction of the anisotropic conductive film.
3. An anisotropic conductive adhesive in which the space is one space extending in the longitudinal direction.
4). An anisotropic conductive adhesive for connecting IC chips with bumps.

ADVANTAGE OF THE INVENTION According to this invention, the anisotropic conductive adhesive with high conduction | electrical_connection reliability between the electrodes to connect can be provided.

(A) is a top view of one Embodiment of the anisotropic conductive adhesive of this invention, (b) is sectional drawing along line AA. (A) is sectional drawing when an IC chip is temporarily fixed using the anisotropic conductive adhesive of this invention, (b) is sectional drawing after crimping | bonding an IC chip. (A) is sectional drawing of the anisotropic conductive film which cut | disconnected the film | membrane in the manufacturing method of the anisotropic conductive adhesive of this invention, (b) is the anisotropic conductive film which removed the center part of the film | membrane. It is sectional drawing. (A) is a top view of the conventional anisotropic conductive adhesive, (b) is sectional drawing along line AA. (A) is sectional drawing when an IC chip is temporarily fixed using the conventional anisotropic conductive adhesive, (b) is sectional drawing after crimping an IC chip.

Hereinafter, the anisotropic conductive adhesive of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals represent the same or equivalent components.
Fig.1 (a) is a top view which shows one Embodiment of the anisotropic conductive adhesive of this invention, FIG.1 (b) is FIG.
It is sectional drawing along line AA of a).

In the anisotropic conductive adhesive 10, an anisotropic conductive film 14 is laminated on a base film 12.
One space 16 continuously extends in the center of the width of the anisotropic conductive film 14. The space 16 extends along the longitudinal direction substantially at the center of the width of the anisotropic conductive film.

2A is a cross-sectional view when the IC chip 20 is temporarily fixed to the glass substrate 30 using the anisotropic conductive adhesive 10, and FIG. FIG.
The space 16 is vacant according to the width between the bumps 22 to be connected. Therefore, as shown in FIG. 2A, when the IC chip 20 is temporarily fixed, a gap (portion where no resin is present) exists immediately below the IC chip 20. Due to the presence of the voids, the anisotropic conductive film 14 is formed during thermocompression bonding.
As shown in FIG. 2A, the flow of the resin occurs not only on the outside of the IC chip 20, but also on the inside, so that the resin of the anisotropic conductive film 14 is quickly filled inside the IC chip 20, and the IC Adhesion between the chip 20 and the substrate 30 is ensured.
Further, since the direction of flow increases, the anisotropic conductive film 1 between the bump 22 and the electrode 32 is provided.
4 resin can be efficiently excluded. Thereby, interference due to the flow of the resin of the anisotropic anisotropic conductive film 14 is suppressed, and the conductive particles of the anisotropic conductive film 14 are easily captured between the bumps 22 and the electrodes 32. Therefore, the conduction reliability between the bump 22 and the electrode 32 is improved.
As described above, the anisotropic conductive adhesive of the present invention has good resin rejection of the anisotropic conductive film to be excluded at the time of thermocompression bonding. Accordingly, the present invention is particularly effective for the conduction reliability of an IC having a wide width between bumps and a high-definition IC having a dense bump.

Here, the base film 12 functions as a carrier tape for the anisotropic conductive film 14, and there is no particular limitation on the forming material, thickness, and the like as long as the anisotropic conductive film 14 is not transferred to the substrate. For example, polytetrafluoroethylene, a polyethylene terephthalate (PET) film subjected to a peeling treatment, or the like can be used.

The anisotropic conductive film 14 is obtained by dispersing conductive particles in an insulating adhesive, but the insulating adhesive and the conductive particles themselves can be the same as known anisotropic conductive films. .
For example, various thermosetting adhesives and thermoplastic adhesives can be used as the insulating adhesive. From the point of reliability after IC chip mounting, epoxy resin, urethane resin,
It is preferable to use a thermosetting adhesive such as an acrylate resin or a BT resin resin. In addition, when preparing an insulating adhesive from these resin components, a single type of resin component may be used, or a plurality of types may be mixed and used.

On the other hand, as the conductive particles, for example, various kinds of particles made of a good electrical conductor such as metal powder made of Ni, Ag, Cu or an alloy thereof, or the like, and the surface of spherical resin particles plated with metal are used. Can do. It is also possible to use particles in which an insulating film is formed on such particles made of a good electrical conductor. Moreover, it is preferable that the particle size of electroconductive particle shall be 0.2-20 micrometers.
The composition for anisotropic conductive films can be prepared by mixing the above insulating adhesive and conductive particles according to a conventional method.

Next, the manufacturing method of the anisotropic conductive adhesive of this invention is demonstrated.
For example, after forming the anisotropic conductive film composition on the base film 12, only the anisotropic conductive film 14 is cut in a half-cut manner as shown in FIG. By removing the winding, a space 16 continuously extending along the longitudinal direction is formed as shown in FIG.
Further, the anisotropic conductive adhesive of the present invention can be obtained by printing the composition in a predetermined pattern on the base film by screen printing or the like.

In addition, although the anisotropic conductive adhesive 10 of this embodiment is provided with one continuous space 16, a plurality of the anisotropic conductive adhesives 10 may be arranged in parallel according to the position and number of electrodes / bumps to be connected. In the present embodiment, the space 16 is substantially at the center of the width of the anisotropic conductive film 14, but the space 16 may be brought to either end.

The anisotropic conductive adhesive of the present invention is suitably used as an adhesive for mounting electronic components such as bumped IC chips on a substrate, but is not limited to this application.

Example An anisotropic conductive adhesive AC-8624AY (3 μm particles, 48K pieces) has 0 in the center in the width direction.
. In order to make a space of 5 mm, the anisotropic conductive film was cut with two cutters in the longitudinal direction, and the central anisotropic conductive film was wound off with an adhesive roll.
Using the anisotropic conductive adhesive subjected to the above-described treatment, a COG process evaluation element (TEG,
Chip size: 1.7 mm × 17.2 mm × 0.5 mmt, bump size: 50 μm ×
50 μm) was mounted on a glass substrate.
Next, the number of captured conductive particles between the bumps and the electrodes (the number of bumps 111) after pressure bonding was measured using an electron microscope, and the average number of captured particles was evaluated from the number of captured conductive particles in each bump.
As a result, the average number of captured particles was 29.5.

Comparative Example The anisotropic conductive adhesive AC-8624AY was used as it was, and the TEG was mounted on a glass substrate in the same manner as in the example.
Next, the average number of trapped conductive particles was evaluated in the same manner as in the examples.
As a result, the average number of captured particles was 26.8.

From the above, the anisotropic conductive adhesive of this example was able to improve the number of captured conductive particles under the bump.

  The anisotropic conductive adhesive of the present invention can be widely used as an anisotropic conductive adhesive for electric and electronic use.

DESCRIPTION OF SYMBOLS 10 Anisotropic conductive adhesive 12 Base film 14 Anisotropic conductive film 16 Space 20 IC chip 22 Bump 30 Glass substrate 32 Electrode

Claims (4)

A base film,
On the base film, formed by laminating the anisotropic conductive film formed by dispersing conductive particles in an insulating adhesive,
An anisotropic conductive adhesive, wherein a space extending in a longitudinal direction is formed in the anisotropic conductive film . 2. The anisotropic conductive adhesive according to claim 1, wherein the space extends in the longitudinal direction at substantially the center in the width direction of the anisotropic conductive film. The anisotropic conductive adhesive according to claim 1 or 2, wherein the space is one space extending in a longitudinal direction. The anisotropic conductive adhesive according to any one of claims 1 to 3, which is used for connecting an IC chip with bumps.