JPH0547428A - Anisotropic conductive film and connecting method for electronic parts using the same - Google Patents

Abstract

PURPOSE:To provide an anisotropic conductive film and a method for connecting electronic parts using the same by breaking a natural oxide film formed on an electrode to be connected so as to securely connect both electrodes of the electronic parts to each other with ease. CONSTITUTION:Conductor portions 3 each having a projecting electrode structure are formed in through hole portions of a porous insulating film 2. Gold (Au) is used for the conductor portion 3 as an oxidation resistant metal 4 which is difficult to be oxidized, and includes alumina (Al2O3) therein as a highly hard particle 5. The obtained anisotropic conductive film is interposed between electronic pats, followed by press-fitting. With application of an ultrasonic wave, a natural oxide film formed on an aluminum electrode is broken, thus causing alloy junction on a new surface between both the electrode metals, for securely connection.

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 having a conductive portion formed in a hole of a porous insulating film and having conductivity only in the vertical direction of the insulating film, and a method of connecting electronic parts using the anisotropic conductive film. Regarding

[0002]

2. Description of the Related Art A conventional anisotropic conductive film has been used in which conductive particles such as metal are dispersed in an insulating resin such as a polymer adhesive. Recently, a porous insulating film has been used. A hole having a conductive portion formed in the hole has been developed. In this type of anisotropic conductive film, for example, a conductive portion is formed of an elastic body as described in JP-A-2-239578,
In addition, the protruding electrode (bump) structure protruding from the insulating film is used to improve the reliability of connection against thermal stress and the like.

[0003]

However, in such a conventional anisotropic conductive film, an electronic component connected by the anisotropic conductive film, such as an electrode of a semiconductor chip, is usually made of aluminum or the like. Although metal is used, its electrode surface is connected to air to form a natural oxide film with a thickness of several nm.
Therefore, there has been a problem that the natural oxide film acts as an insulator on the joint surface between the conductive portion of the anisotropic conductive film and the electrode of the semiconductor chip, which causes a connection failure.

Further, in the anisotropic conductive film having the protruding electrodes formed thereon, the natural oxide film can be broken by simply performing pressure contact with the electrode of the semiconductor chip covered with the natural oxide film. However, there is a problem that the reliability of electrical connection is low. Therefore, according to the present invention, even if a natural oxide film is formed on the surfaces of the electrodes to be connected by the anisotropic conductive film, the natural oxidation of the surface is broken when joining with the anisotropic conductive film to ensure a reliable electrical conductivity. An object is to provide an anisotropic conductive film that can be connected and a method for connecting electronic components using the anisotropic conductive film.

[0005]

The invention according to claim 1 is
In an anisotropic conductive film in which a conductive part is formed in a hole of a porous insulating film having a large number of through holes, the conductive part has a hardness higher than that of an electrode material to be connected in an oxidation resistant metal that is hard to oxidize. It is characterized by containing fine particles of hardness and having a protruding electrode structure.

According to a second aspect of the invention, the porous insulating film is an aluminum anodic oxide film. A third aspect of the present invention is that between the electronic components is the first aspect.
It is characterized in that both the electronic components are electrically connected by sandwiching the described anisotropic conductive film and applying an ultrasonic wave.

[0007]

According to the first aspect of the invention, the conductive portion formed in the hole of the porous insulating film has a protruding electrode structure, and the oxidation resistant metal is used as the material of the conductive portion itself. Therefore, the surface of the conductive portion is not covered with the oxide film, and good connection can be achieved. Further, the oxidation resistant metal contains fine particles harder than the electrode material to be connected.
For example, for aluminum electrodes, alumina (Al
Fine particles such as ₂ O ₃ ) are used. Thereby, when the aluminum electrode and the conductive portion of the anisotropic conductive film are connected, the fine particles break the natural oxide film generated on the surface of the electrode,
Highly reliable electrical connection is possible.

According to the second aspect of the invention, since the aluminum anodic oxide film is used as the porous insulating film of the anisotropic conductive film, fine through holes are formed. In addition to being able to deal with it, it has good thermal conductivity and therefore has good reliability against thermal stress. According to the invention of claim 3, the anisotropic conductive film of the invention of claim 1 is interposed between electronic components to connect the electronic components while applying ultrasonic waves. By doing so, the natural oxide film formed on the aluminum electrode is destroyed by the high hardness fine particles such as alumina (Al ₂ O ₃ ) contained in the conductive portion, and the new surfaces of the metal to be connected come into contact with each other, and The alloy connection is made by diffusion.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. 1 is a diagram showing an embodiment of an anisotropic conductive film according to the invention described in claim 1, (a) is an overall configuration diagram,
(B) is an internal configuration diagram of the conductive portion. First, the configuration will be described.

As shown in FIG. 1A, in the anisotropic conductive film 1 of this embodiment, the conductive portion 3 is formed in the pores of the porous insulating film 2 in a protruding electrode structure. Therefore, it has conductivity only in the vertical direction with the porous insulating film 2 interposed therebetween. In addition, as shown in FIG. 1B, the conductive portion 3 of the present embodiment.
In this configuration, for example, gold (Au), nickel (Ni), or the like can be used as the oxidation resistant metal 4 that is difficult to oxidize. The oxidation-resistant metal 4 contains fine particles 5 of high hardness. Here, alumina (Al ₂ O ₃ ) or silicon carbide (SiC) having a particle size of 0.5 to 20 μm is used. You can

The conductive portion 3 thus constructed can be formed, for example, under the following conditions. That is, the oxidation-resistant metal 4 such as gold or nickel and the high-hardness fine particles 5 such as alumina or silicon carbide are subjected to composite electrodeposition to form a composite electrode shown in FIG.
It is formed in the pores of the porous insulating film 2 of (a).
The protruding electrode (pump) structure of the conductive portion 3 can be formed by applying a resist in a pattern on the surface of the porous insulating film 2 and then performing electrodeposition treatment. In addition,
The resist is removed after the electrodeposition process.

More specifically, for example, in the case of forming the conductive portion 3 in which the fine particles of alumina are contained in nickel, pH = 0.5 to 3.0 obtained by appropriately mixing nickel sulfate, magnesium sulfate and formic acid at 20 to 80 ° C. In the electrolytic solution, the concentration of alumina in the solution is set to 10 to 100 〓 / m ³ and the current density is set to 5 to 100 A / dm ² , and the electrodeposition treatment is performed. As a result, it is possible to form, in the pores of the porous insulating film 2, a conductive portion containing nickel fine particles having a particle diameter of 0.5 to 3.0 μm in nickel.

In addition to the above electrodeposition treatment, a paste of gold or silver containing 5 to 50% of alumina is enclosed in the pores of the porous insulating film 2 and then cured to form a conductive portion. You can also Next, the operation will be described. Figure 2 shows the LSI
4 is a connection state diagram of an electronic component in which the chip 6 and the wiring board 7 are electrically connected via the anisotropic conductive film 1. FIG. As shown in FIG. 2, the conductive portion 3 configured as described above is connected to L
Electrodes 8a and 8b of SI chip 6 and electrodes 9 of wiring board 7
It is sandwiched between a and 9b and crimped to connect.

Further, FIG. 3A shows the conductive portion 3 and the electrode 9b.
FIG. 4 is an enlarged view of an interface portion during the pressure bonding. As shown in FIG. 3A, since the aluminum native oxide film 10 is interposed between the electrode 9b and the conductive portion 3, the connection is poor as it is. Therefore, in this embodiment, ultrasonic waves are applied to the wiring board 7 side shown in FIG. FIG. 3B is a state diagram in which ultrasonic waves are applied from the state of FIG. 3A, and the high hardness fine particles 5 vibrate in the oxidation resistant metal 4 to scrape and destroy the natural oxide film 10 on the aluminum electrode. .. Therefore, as shown by A in the figure, the destroyed natural oxide film 10 comes into contact with the aluminum electrode 9b and the conductive portion 3 mainly composed of gold on the new surface of both metals, and further the mutual diffusion occurs. Causes gold and aluminum to be alloy-bonded. Therefore, even if the surface of the electrode is covered with the natural oxide film or the like, the electrical connection between the electronic components can be surely made.

FIG. 4 is a constitutional view when an aluminum anodic oxide film is used as the porous insulating film of the anisotropic conductive film. As shown in FIG. 1 above, the hole pattern may be formed so as to correspond to the electrode, but as shown in FIG. 4, the hole pattern of the porous insulating film 2 of the anisotropic conductive film 1 is larger than that of the electrode. The aluminum anodic oxide film 12 having a much smaller pitch and area can be used. The aluminum anodic oxide film 12 forms fine pores on its surface by anodizing aluminum in a solution of sulfuric acid, phosphoric acid or the like. Then, this porous alumina (Al ₂ O ₃ ) is separated from the aluminum substrate to form an aluminum anodic oxide film 12 as shown in FIG. In this embodiment, as shown in FIG. 4, the shape is such that the thickness a is 10 to
The diameter is 100 μm, the hole diameter b is 0.01 to 0.3 μm, and the hole pitch c is about 0.03 to 1 μm. The aluminum anodic oxide film 12 in the present embodiment is not limited to this shape.

The conductive portion 3 can be formed in all the holes, but here, as shown in FIG. 4, it is formed in a part of the holes corresponding to the positions of the electrodes to be connected. It is a thing. Therefore, when the conductive portion 3 is formed on a part of the aluminum anodic oxide film 12, a resist is selectively applied to the surface of the aluminum anodic oxide film 12 by a photo process to form an opening accurately at a desired position. .. Then, by performing the same electrodeposition process as that described above on the opening, the conductive portion 3 of the protruding electrode structure can be formed at the position shown by the alternate long and short dash line in FIG.

As described above, when the aluminum anodic oxide film 12 is used as the porous insulating film 2, the conductive portion 3 having a desired pitch and area at a desired position is formed by a photo process.
Since it is possible to form the electrodes, it is possible to easily cope with the electrode connection between the electronic components having the fine pattern, and it is possible to make a reliable connection.

[0018]

According to the first aspect of the invention, since the conductive portion of the anisotropic conductive film has a protruding electrode structure and contains fine particles harder than the electrodes to be connected in the oxidation resistant metal, The natural oxide film on the electrode surface is easily broken, and highly reliable electrical connection can be performed. Further, since it is not necessary to form the protruding electrode on the side of the electronic component such as the semiconductor chip or the wiring board, the yield of the electronic component can be improved and the cost can be reduced.

According to the second aspect of the invention, since the anisotropic conductive film is formed by using the aluminum anodic oxide film having fine through holes as the porous insulating film, it is also possible to connect electrodes with a fine pitch. It is possible to deal with it, and due to good thermal conductivity, high reliability against thermal stress can be obtained. According to the third aspect of the invention, the anisotropic conductive film using the conductive portion having the structure of the first aspect is interposed between the electronic components, and ultrasonic waves are applied to bond the components. Highly reliable connection. Further, since the connection can be performed at a low temperature, the thermal stress on the electronic components and the like is small, and the reliability of the connection can be further improved.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of an anisotropic conductive film according to the invention of claim 1, wherein (a) is an overall configuration diagram,
(B) is an internal configuration diagram of the conductive portion.

FIG. 2 is a connection state diagram for connecting electronic components to each other with an anisotropic conductive film of the present invention interposed therebetween.

3A and 3B are enlarged views showing a state of a contact interface between a conductive portion and an electrode, wherein FIG. 3A is a view at the time of pressure bonding, and FIG. 3B is a view at the time of applying an ultrasonic wave.

FIG. 4 is a diagram showing an embodiment of an anisotropic conductive film according to the invention of claim 2;

[Explanation of reference numerals] 1 anisotropic conductive film 2 porous insulating film 3 conductive part 4 oxidation resistant metal 5 high hardness fine particles 6 LSI chip 7 wiring board 8a, 8b electrodes 9a, 9b electrode 12 aluminum anodic oxide film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiaki Iwabuchi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (3)

[Claims] 1. An anisotropic conductive film in which a conductive part is formed in a hole of a porous insulating film having a large number of through holes, wherein the conductive part is formed of an electrode material to be connected in an oxidation resistant metal that is hard to oxidize. An anisotropic conductive film containing high-hardness fine particles having a high hardness and having a protruding electrode structure. 2. The anisotropic conductive film according to claim 1, wherein the porous insulating film is an aluminum anodic oxide film. 3. A method of connecting electronic components, wherein the anisotropic conductive film according to claim 1 is sandwiched between electronic components and ultrasonic waves are applied to electrically connect the electronic components. ..