JPH11329542A - Anisotropic conductive adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily, speedily mount each IC chip using an anisotropic conductive film with each optimal specification by providing patterns of the anisotropic conductive film where conductive particles are dispersed in an insulating adhesive at a plurality of places on a base film. SOLUTION: In an anisotropic conductive adhesive 10, three patterns 3p-a, 3p-b, 3p-c of anisotropic conductive films with different sizes and thicknesses are formed mutually separately on a base film 2. Type and viscosity of insulating adhesive constituting each pattern, and type, particle size, concentration of conductive particles can be also set. In addition, patterns of the anisotropic conductive films on the base film can be provided for places corresponding to mounting positions of IC tips of a board. By eliminating tacking ability of the anisotropic conductive films at a room temperature, the anisotropic conductive films are transcribed onto the board, and then a solder paste can be printed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of mounting a plurality of types of IC chips on a substrate by using an anisotropic conductive film. The present invention relates to a conductive adhesive.

[0002]

2. Description of the Related Art In recent years, as market needs for high functionality, light weight, thinness, and miniaturization of information terminal equipment have increased, bare chips have been directly mounted on printed wiring boards and other substrates. Various methods have been studied.

One of them is an anisotropic conductive film (ACF) formed by forming an anisotropic conductive adhesive in which conductive particles are dispersed in a thermosetting adhesive into a film, or an anisotropic conductive adhesive. There is a method using an anisotropic conductive paste (ACP) prepared in a liquid state. Of these, the product form of the anisotropic conductive film is usually
Like an anisotropic conductive adhesive 1 shown in FIG. 5, an anisotropic conductive film 3 is solidly laminated on a base film 2 and wound on a reel.

[0004]

However, when several types of IC chips having different shapes are mounted on the same substrate using the conventional anisotropic conductive adhesive 1 made of the anisotropic conductive film 3, anisotropic Regarding the thickness of the conductive film 3, the concentration of the conductive particles, and the like,
Anisotropic conductive film 3 with specifications suitable for each IC chip
Since the anisotropic conductive adhesive 1 must be prepared for each case, several types of anisotropic conductive adhesives 1 must be prepared as a result, and the tact time becomes longer. Furthermore, many expensive ACF sticking apparatuses are required, and the burden on capital investment increases.

On the other hand, when an IC chip is mounted on a substrate using an anisotropic conductive paste, the anisotropic conductive paste can be applied to a predetermined portion of the substrate to a predetermined thickness using a commercially available dispenser. Therefore, it is advantageous in terms of equipment as compared with the case where the above-described anisotropic conductive film is used.

[0006] However, since the anisotropic conductive paste is in a liquid state, there is a problem that conductive particles settle during a long storage period, and it is not easy to control the viscosity. In addition, deterioration of the working environment due to evaporation of the solvent also poses a problem. Furthermore, there is a problem that it is difficult to control the amount of application constantly.

[0007] Further, in the case of using either an anisotropic conductive film or an anisotropic conductive paste, when other chip parts are mounted on a substrate on which an IC chip is mounted,
After the transfer of the anisotropic conductive film to the substrate or the application of the anisotropic conductive paste, it becomes difficult to print the solder paste. Alternatively, an anisotropic conductive paste must be applied. However, the transfer of such an anisotropic conductive film or the application of an anisotropic conductive paste has become increasingly difficult with the recent tendency to reduce the mounting area.

[0008] The present invention solves the above-mentioned problems associated with the conventional anisotropic conductive film or anisotropic conductive paste.
When a plurality of types of IC chips are mounted on a substrate using an anisotropic conductive adhesive made of an anisotropic conductive film, each IC chip can be easily and simply made using an anisotropic conductive film having an optimum specification. To be able to implement in time, and furthermore IC
It is an object of the present invention to efficiently mount both an IC chip and other chip components when a chip component other than a chip is mounted on a substrate using a solder paste.

[0009]

Means for Solving the Problems In order to achieve the above object, the present invention provides an anisotropic conductive film having conductive particles dispersed in an insulating adhesive.
Provided is an anisotropic conductive adhesive, which is provided apart from each other at a plurality of locations. In particular, as the pattern of the anisotropic conductive film, an aspect in which a plurality of types of patterns having different shapes, sizes, or thicknesses are provided, the type or viscosity of the insulating adhesive, the type, the particle size, or the concentration of the conductive particles At least one is provided with a different pattern, and the pattern of the anisotropic conductive film is provided on the base film at a position corresponding to the mounting position of the IC chip on the substrate. I do.

Further, the present invention provides an embodiment in which the anisotropic conductive film does not have tackiness at room temperature.

Also, there is provided an IC chip mounting method in which an anisotropic conductive film is transferred from the above-described anisotropic conductive adhesive to a connection portion of the IC chip on a substrate by a laminating method, and the IC chip is mounted thereon. provide.

In the anisotropic conductive adhesive of the present invention, since the patterns of the anisotropic conductive film are formed separately from each other on the base film, each pattern is formed in a predetermined shape, size and thickness. be able to. Also, the type, viscosity, type, particle size, concentration, etc. of the insulating adhesive constituting each pattern can be set as appropriate. Furthermore, the pattern of the anisotropic conductive film on the base film is
It can also be provided at a location corresponding to the mounting position of the chip. Therefore, despite the use of a single anisotropic conductive adhesive as one reel, each of several types of IC chips having different shapes can be efficiently used by using an anisotropic conductive film having an optimal specification. It can be mounted on a substrate.

Further, by removing the tackiness of the anisotropic conductive film at room temperature, after transferring the anisotropic conductive film to the substrate,
It becomes possible to print the solder paste. Therefore, when both an IC chip and other chip components are mounted on a substrate, a conventional solder paste is first printed on the substrate to mount other chip components, and then an anisotropic conductive film is mounted on the substrate. The process restriction that the IC chip has to be mounted by transferring the IC chip is eliminated. Therefore, it is possible to transfer an anisotropic conductive film to a substrate, print solder paste, then mount an IC chip, mount another chip component, and reflow to mount another component. It becomes possible.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The anisotropic conductive adhesive of the present invention will be described below in detail with reference to the drawings. In each figure,
The same reference numerals represent the same or equivalent components.

FIG. 1 is a plan view (FIG. 1A) and a cross-sectional view (FIG. 1B) of one embodiment of the anisotropic conductive adhesive of the present invention. As shown in the figure, as shown in FIG.
Has a layer structure in which a pattern 3p of an anisotropic conductive film is laminated on a base film 2, as in the conventional anisotropic conductive adhesive 1 shown in FIG.

Here, the base film 2 functions as a carrier tape of the anisotropic conductive film, and there is no particular limitation on the material and thickness of the base film 2 as long as the transfer of the anisotropic conductive film to the substrate is not hindered. Absent. For example, polytetrafluoroethylene, a PET film subjected to a release treatment, or the like can be used.

The pattern 3p of the anisotropic conductive film is formed of an anisotropic conductive film obtained by forming an anisotropic conductive adhesive in which conductive particles are dispersed in an insulating adhesive into a film shape. In one anisotropic conductive adhesive material 10, three types of anisotropic conductive film patterns 3p (3
p-a, 3p-b, and 3p-c) are provided on the base film 2 at a distance from each other. Thus, the pattern 3 of the anisotropic conductive film having different planar shapes, sizes and thicknesses
By providing p (3p-a, 3p-b, 3p-c) on a single anisotropic conductive adhesive 10, an anisotropic conductive film suitable for the IC chip to be mounted on the substrate is formed into one anisotropic conductive film. Conductive adhesive 1
0 can be appropriately selected. Therefore, the I
It is not necessary to prepare an anisotropic conductive adhesive reel for each anisotropic conductive film with specifications suitable for mounting C chips. It is not necessary to install for each adhesive.

The pattern 3p (3p-
The insulating adhesive and the conductive particles forming the a, 3p-b, and 3p-c) 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 viewpoint of reliability after mounting the IC chip, it is preferable to use a thermosetting adhesive such as an epoxy resin, a urethane resin, an acrylate resin, and a BT resin.
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.

In forming the anisotropic conductive film from the insulating adhesive, it is preferable that the obtained anisotropic conductive film has no tackiness at room temperature. here,
JIS Z 023 states that the anisotropic conductive film has no tackiness.
In the 7-ball tacking method, a state in which a 1/10 inch ball does not stop. Thus, after the anisotropic conductive film is transferred to the substrate for mounting the IC chip, it is possible to print a solder paste for mounting another chip component on the substrate. Therefore, the IC chip and other chip components can be efficiently mounted.

In order to form an anisotropic conductive film so that the anisotropic conductive film does not have tackiness at room temperature, a resin component is blended so as to be solid at room temperature and have a softening point of 50 ° C. Can be obtained by dissolving this in an organic solvent and finally drying the solvent.

On the other hand, as the conductive particles, for example, N
Various kinds of particles made of a good electrical conductor, such as metal powders made of i, Ag, Cu or alloys thereof, and spherical resin particles having a surface plated with metal can be used. Particles obtained by forming an insulating coating on such particles of a good electrical conductor can also be used. Further, the particle size of the conductive particles is preferably set to 0.2 to 20 μm.

An anisotropic conductive adhesive can be prepared by mixing the above-mentioned insulating adhesive and conductive particles in a conventional manner, and the obtained anisotropic conductive adhesive is screen-printed or the like to form a base film. By printing a predetermined pattern on the substrate 2, the anisotropic conductive adhesive material 10 of the present invention in which the pattern 3p of the anisotropic conductive film is formed at a plurality of locations separately from each other can be obtained. Also, by performing overprinting in this printing step, the pattern 3p (3p-a,
3p-b, 3p-c) can be formed to a predetermined thickness.

Further, in the printing step on the base film 2, anisotropic conductive adhesives having different types and viscosities of insulating adhesives, types, particle sizes and concentrations of conductive particles are used. By forming a pattern of an anisotropic conductive film from the anisotropic conductive adhesive of
A pattern 3p of an anisotropic conductive film having different adhesion performance, electrical connection performance, and the like can be formed thereon.

When the pattern 3p of the anisotropic conductive film is formed on the base film 2, it is preferable that the arrangement of each pattern on the base film 2 correspond to the mounting position of the IC chip on the substrate. This makes it possible to transfer the pattern 3p of the anisotropic conductive film from the anisotropic conductive adhesive material to a predetermined portion of the substrate very efficiently and easily by using a laminator as described later.

Further, as shown in FIG. 2, an insulating adhesive layer 4 containing no conductive particles may be formed in a region on the base film 2 other than the pattern 3p.
This makes it possible to simultaneously form an adhesive layer that can be used for temporarily fixing components other than the IC chip.

As a method for mounting an IC chip using the anisotropic conductive adhesive of the present invention, a pattern of an anisotropic conductive film is transferred from the anisotropic conductive adhesive of the present invention to a substrate by a laminating method. It is preferable to mount an IC chip on the transfer portion by a conventional method. More specifically, for example, the anisotropic conductive adhesive has a pattern of the anisotropic conductive film on the substrate.
In the case where the anisotropic conductive adhesive 10 is formed corresponding to the mounting position of the C chip, as shown in FIG. The surface on the pattern 3p side of the anisotropic conductive film is aligned with the mounting surface of the substrate 30 and heated and pressed by the laminator 23. Next, the base film 2 is wound around a reel 21. Thus, the pattern 3p of the anisotropic conductive film can be transferred to a predetermined portion of the substrate 30 extremely easily. afterwards,
The IC chip is mounted on the transfer portion of the pattern 3p of the anisotropic conductive film, and the IC chip is mounted on the substrate 30 by heating and pressing. In this case, the thermocompression bonding conditions can be the same as those for mounting an IC chip using a conventional anisotropic conductive film.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments.

Examples 1 and 2 (1) Preparation of anisotropic conductive adhesive The components shown in Table 1 below were dissolved in diethylene glycol monomethyl ether acetate (conductive particles were dispersed) to form a paste. This is printed on a peeled PET film by a screen printing method and dried at 80 ° C. for 5 minutes to form an anisotropic conductive adhesive having a pattern of a 7 mm square, 40 μm thick anisotropic conductive film. Was formed.

[0030]

(Table 1) (Blending ratio: parts by weight) Ingredients Example 1 Example 2 Phenoxy resin (YP50, Toto Kasei Co., Ltd.) 50 45 Liquid epoxy resin dispersion type imidazole type curing agent 40 35 (Nohpa Cure 3941HP, Asahi Kasei Corporation) Ni-Au plated conductive particles 10 20 (Microval AU, Sekisui Chemical)

(2) Mounting of IC chip 6.3 mm square I having a projecting electrode of a peripheral array
The anisotropic conductive adhesive obtained in the above (1) is applied at 80 ° C. and 3 kgf / cm to the IC chip mounting area of the glass epoxy substrate having the wiring pattern prepared for mounting the C chip.
Heat and pressure were applied under the condition of cm ² · 5 sec, and then the base film was peeled off to transfer the pattern of the anisotropic conductive film onto the glass epoxy substrate.

The anisotropic conductive film transferred onto the glass epoxy substrate did not have tackiness at room temperature. To confirm this, a plate for solder paste printing was placed on an anisotropic conductive film transferred onto a glass epoxy substrate, and a squeegee was run under the conditions of a printing pressure of 2 kgf / cm ² . No transfer of the anisotropic conductive film or deformation of the pattern of the anisotropic conductive film was observed.

Thereafter, the IC chip is heated at 180 ° C. for 2 hours.
It was connected to the pattern of the anisotropic conductive film under the conditions of 0 sec and 4 kg (press thrust). As a result, the resistance value after connection is
Example 1 was 10 mΩ and Example 2 was 8 mΩ, and there was no abnormality.

Example 3 As shown in FIG. 4, five anisotropic conductive film patterns 3pa, 3pb, 3pc, 3pd and 3pe were formed on the base film 2 by screen printing. in this case,
As shown in Table 2, the composition of the pattern of each anisotropic conductive film was the same as in Example 1 or Example 2, and the area and thickness were as shown in the table.

[0035]

[Table 2] Pattern composition Area Thickness 3pa Example 2 12 × 12 mm 60 μm 3 pb Example 1 12 × 12 mm 40 μm 3pc Example 2 8 × 8 mm 70 μm 3pd Example 2 8 × 8 mm 60 μm 3pe Example 1 8 × 8 mm 40 μm

The patterns 3pa and 3p of each anisotropic conductive film
b, 3pc, 3pd, and 3pe are transferred to the substrate on which the wiring pattern for connecting the IC chip is formed at the corresponding position of each pattern.
A test IC chip having the following specifications was connected under the same connection conditions as in Example 1.

As a result, the resistance after connection is 8 to 15 mΩ.
Was stable.

[0038]

[Table 3] Specification of IC pattern IC chip 3pa 10mm square protrusion electrode φ40μm height 40μm stat bump 3pb 10mm square protrusion electrode φ100μm height 20μm plating bump 3pc 6.3mm square protrusion electrode φ40μm height 50μm stat bump 3pd 6.3mm square protrusion electrode φ40μm height 40μm stat Bump 3pe 6.3mm square projection electrode φ100μm height 20μm plating bump

[0039]

According to the present invention, several kinds of I having different shapes are provided.
When the C chip is mounted on the same substrate, anisotropic conductive film having specifications suitable for each IC chip can be transferred from the single anisotropic conductive adhesive to the substrate, so that the tact time of mounting is reduced. Can be shortened. Especially,
By making the pattern of the anisotropic conductive film on the base film correspond to the mounting position of the IC chip on the substrate, it is possible to transfer the pattern of the anisotropic conductive film to the substrate very simply and collectively. Therefore, it is not necessary to prepare a plurality of reels for each anisotropic conductive film corresponding to the size of the IC chip to be mounted, and an expensive ACF is attached to transfer the anisotropic conductive film to the substrate. It is not necessary to prepare a plurality of devices.

Further, according to the anisotropic conductive adhesive of the present invention, in which the tackiness of the anisotropic conductive film at room temperature is eliminated, the pattern of the anisotropic conductive film is transferred to the substrate. Since solder paste for mounting other chip components can be applied by screen printing,
The IC chip and other chip components can be efficiently and compactly mounted.

[Brief description of the drawings]

FIG. 1 is a plan view (FIG. 1 (a)) and a cross-sectional view (FIG. 1 (b)) of an anisotropic conductive adhesive of the present invention.

FIG. 2 is a cross-sectional view of an anisotropic conductive adhesive according to another embodiment of the present invention.

FIG. 3 is an explanatory view of a method for transferring a pattern of an anisotropic conductive film from an anisotropic conductive adhesive to a substrate.

FIG. 4 is a plan view of the anisotropic conductive adhesive of the present invention.

FIG. 5 is a sectional view of a conventional adhesive made of an anisotropic conductive film.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conventional anisotropic conductive adhesive material 2 Base film 3 Anisotropic conductive film 3p Pattern of anisotropic conductive film 3p-a, 3p-b, 3p-c Pattern of anisotropic conductive film 3pa, 3pb, 3pc, 3pd, 3pe 4 Insulating adhesive layer 10 Anisotropic conductive adhesive of the present invention 20 Reel 21 Reel 23 Laminator 30 Substrate

Claims (7)

[Claims] 1. A pattern of an anisotropic conductive film, in which conductive particles are dispersed in an insulating adhesive, is formed on a base film.
An anisotropic conductive adhesive, which is provided at a plurality of locations so as to be separated from each other. 2. The anisotropic conductive adhesive according to claim 1, wherein a plurality of patterns of anisotropic conductive films having different shapes, sizes or thicknesses are provided on the base film. 3. The base film is provided with a plurality of anisotropic conductive film patterns different in at least one of the kind or viscosity of the insulating adhesive, the kind, the particle size or the concentration of the conductive particles. 3. The anisotropic conductive adhesive according to 1 or 2. 4. The anisotropic conductive film according to claim 1, wherein the pattern of the anisotropic conductive film is provided on the base film at a position corresponding to the mounting position of the IC chip on the substrate. Adhesive. 5. The adhesive according to claim 1, wherein the anisotropic conductive film has no tack at room temperature. 6. The anisotropic conductive adhesive according to claim 1, wherein an insulating adhesive layer containing no conductive particles is provided on the base film. 7. An anisotropic conductive adhesive according to claim 1 is transferred to a connection portion of the IC chip on a substrate by a laminating method from the anisotropic conductive adhesive according to claim 1, and the IC chip is transferred thereto. IC chip mounting method.