JP3092118B2 - Conductive particle transfer type anisotropic conductive film and electrical connection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for electrically connecting terminals between two circuit boards. More specifically, the present invention reliably and easily connects terminals between two circuit boards without causing a short circuit between the terminals even when a large number of terminals to be connected to the circuit boards are formed at a fine pitch. electrical connection method to be able to connect, and relates to a conductive particle transfer type anisotropic conductive Fi <br/> Le beam for use in such electrical connection.

[0002]

2. Description of the Related Art As a method for electrically connecting terminals between two circuit boards, such as when a liquid crystal panel is connected to a TAB, a method using an anisotropic conductive adhesive has conventionally been used. Are known. In this method, an anisotropic conductive adhesive is used in which conductive particles such as metal particles such as solder particles and nickel particles and gold-plated resin particles are dispersed in a thermosetting or thermoplastic adhesive. Then, such an anisotropic conductive adhesive is interposed between the two circuit boards,
By applying heat and pressure, an electrical connection between two opposing terminals can be obtained (Japanese Patent Laid-Open No. 51-114439).

[0003] As a bonding material similar to such an anisotropic conductive adhesive, conductive particles are placed in a sheet-like insulating base material made of a thermoplastic resin, in contact with one surface of the base material or one side of the base material. Some are buried so as to be exposed from the surface. As a method of using the bonding material, first, the terminal surface of the first circuit board and the conductive particles of the bonding material are heated and welded. Next, the second circuit board is heated and pressurized on the heat-welded joining material to melt the sheet-like insulating base material of the joining material,
The two circuit boards are joined together, and the conductive particles welded to the terminals of the first circuit board are joined to the terminals of the second circuit board (JP-A-64-14886).

As a method of connecting an IC chip to a TAB, a transfer bump method is known in which a gold pillar is formed on a bump-forming substrate by plating, this is aligned with the TAB, transferred, and connected. I have.

Further, a method is also known in which a conductive adhesive is placed only on a pattern to be connected to a circuit board by printing, dipping, or the like.

[0006]

However, in the conventional method using the anisotropic conductive adhesive, the anisotropic conductive adhesive is applied to the entire surface of the bonding area including the terminals to be connected between the two circuit boards. Since they are interposed, the conductive particles exist not only between the terminals to be connected but also between other adjacent terminals. For this reason, there has been a problem that short-circuiting is likely to occur when the terminal pitch is fine. For such a problem, it is considered to reduce the amount of the conductive particles in the anisotropic conductive adhesive. However, if the amount of the conductive particles is reduced, there is a gap between the terminals to be connected. There is a problem that conduction reliability is reduced because the number of conductive particles is reduced.

In addition, the transfer bump method requires a step of forming a gold pillar by plating and a step of aligning the same with TAB, so that there is a problem that the number of steps is large and workability is poor.

Furthermore, in the method of placing the conductive adhesive only on the pattern to be connected to the circuit board by printing, dipping, or the like, there is a problem that it is difficult to apply the conductive adhesive only on a predetermined pattern. . In addition, since the bonding between the two circuit boards is performed only by bonding between the terminal patterns, there is a problem that the bonding strength and reliability are reduced.

An object of the present invention is to solve the above-mentioned problems of the prior art. When a large number of terminals to be connected to two circuit boards are formed on the circuit board at a fine pitch. However, it is an object of the present invention to enable reliable and easy connection so that high conduction reliability can be obtained without causing a short circuit.

[0010]

In order to achieve the above-mentioned object, the present invention provides a method in which one layer of conductive particles is held by a binder layer formed on a film, and the conductive particles are separated from the binder layer. Protruding conductive particle transfer type
In an anisotropic conductive film, the binder layer and the
Conductive particles held in the resin binder
Is dispersed in a binder layer having a thickness of conductive particles.
By coating on the film so that the particle size is
The present invention provides a conductive particle transfer type anisotropic conductive film, characterized in that the film is provided.

The conductive particle transfer type anisotropic conductive film
As an electrical connection method of the present invention in which the terminal of the first circuit board and a terminal of the second circuit board are electrically connected using Lum, conductive particles of the terminal surface and the upper predicate of the first circuit board Transfer type
The surface on which the conductive particles of the anisotropic conductive film are held
Overlapping, thermocompression bonding both, peeling to only the conductive particles are transferred to the first circuit board of the terminal, then the terminal surfaces of the first circuit board is transferred to the conductive particles and the second circuit board The present invention provides an electrical connection method characterized in that the terminal surface is heated and press-bonded with an adhesive via an adhesive.

Hereinafter, the electrical connection method of the present invention will be specifically described with reference to the drawings. In the drawings, the same reference numerals represent the same or equivalent components.

FIG. 1 and FIG. 2 are process explanatory diagrams of the electrical connection method of the present invention, respectively. FIG. 1 (a) and FIG. 2 (a) both show conductive particle transfer used in the method of the present invention.
It is sectional drawing of an example of a type | mold anisotropic conductive film. As shown in the figure, the conductive particle transfer type anisotropic conductive film 1 of the present invention
Is a film in which one layer of conductive particles 3 is held on a film 2. By holding one layer of the conductive particles in this way, it is possible to uniformly fuse the conductive particles to the terminals of the circuit board when the transfer film is first pressure-bonded to the circuit board as described later.

This conductive particle transfer type anisotropic conductive film 1
For example, the conductive particles 3 may be dispersed in a resin binder liquid, and the binder liquid may be applied on the film 2 so that the thickness of the binder layer 4 is equal to or less than the particle diameter of the conductive particles 3. . As a result, as shown in FIG.
The conductive particle transfer type anisotropic conductive film 1 in a form in which the conductive particles 3 of the layer are held so as to protrude above the film 2 by the binder layer 4 can be obtained.

The film 2 used for the conductive particle transfer type anisotropic conductive film 1 is preferably a heat-resistant film.
For example, a polyimide film, Teflon, or the like can be used.

As the conductive particles 3 used in the conductive particle transfer type anisotropic conductive film 1, various particles having a metal surface can be used, but depending on the material of the terminal of the circuit board to be connected. It is preferable to select. For example, as shown in FIG.
When a gold plating layer or a nickel plating layer 5b is formed thereon, or when the terminal is treated with glycoat, the conductive particles are solder particles, tin particles, indium particles, other alloy particles thereof, or solder plating. ,
Use particles plated with tin or indium. When the terminals of the circuit board are made of aluminum, gold particles or gold-plated particles are used. further,
As shown in FIG. 2B, when a solder plating layer or a tin plating layer 5c is formed on the terminals 5a of the circuit board 5, the conductive particles 3 may be solderable metal particles or metal plating. Use particles.

The shape of the conductive particles 3 is spherical, acicular,
Various types such as columnar, plate-like and irregular shapes can be used, but it is preferable to use spherical ones. Also, as the particle size,
It is preferable to use one having a size of 0.5 to 50 μm, and it is preferable that the particle size distribution is as uniform as possible.

In the electrical connection method of the present invention, first, the conductive particle transfer type anisotropic conductive film 1 as described above is used.
To create a circuit board for electrical connection using. That is,
As shown in FIG. 1B or FIG. 2B, the terminal 5a to be connected to the first circuit board 5 is connected to the conductive particle transfer type.
Superimposed and surface conductive particles 3 of the anisotropic conductive film 1 is held, thermocompression bonding of both (primary bonding). The heating and pressurizing conditions for the first pressure bonding may be appropriately set according to the type of the terminal 5a and the conductive particles 3 of the circuit board 5 so that the terminal 5a and the conductive particles 3 are fused. For example, as shown in FIG.
against a, conductive holding the solder particles as the conductive particles 3
When the particle transfer type anisotropic conductive film 1 is first pressure-bonded, the conductive particles 3 made of solder particles may be melted so that the terminal 5a and the conductive particles 3 are fused.
As shown in (b), when the conductive particle transfer type anisotropic conductive film 1 is first pressure-bonded to the solder-plated terminal 5a, the solder layer 5c on the terminal 5a melts. The terminal 5a and the conductive particles 3 may be fused together.

After the first pressure bonding, FIG.
(C), the first circuit board 5 and the conductive particles
The transfer type anisotropic conductive film 1 is separated from each other, and only the conductive particles 3 are transferred onto the terminals 5a of the first circuit board 5,
The circuit board 6 for electrical connection in which the conductive particles 3 exist only on the terminal 5a is obtained.

Next, as shown in FIG. 1 (d) or FIG. 2 (d), the circuit board 6 for electrical connection in which the conductive particles 3 are present only on the terminal 5a and the second circuit board 7 are placed with their terminals 5a and 7a on the inside, an adhesive film 8 is placed as an adhesive between them, and they are superimposed and heat-pressed (finally pressed). As a result, the first circuit board 5 and the second
The circuit board 7 is bonded with a strong adhesive strength because the entire surface thereof is adhered with an adhesive film. Moreover, since the conductive particles 3 are present only in the terminals 5a of the first circuit board 5, the terminals 5a of the first circuit board 5 and the terminals 7a of the second circuit board 7 may not be short-circuited. The connection is ensured without causing conduction failure.

Here, as the adhesive film 8, a thermosetting or thermoplastic resin film can be used. Further, without using such a film as an adhesive, a thermosetting or thermoplastic resin liquid used for a conventional anisotropic conductive adhesive may be applied between two circuit boards. .

The heating and pressurizing conditions for the final press bonding may be appropriately set according to the terminal materials of the two circuit boards, the type of the conductive particles 3 and the type of the adhesive.

[0023]

The conductive particle-transfer-type anisotropic conductive film of the present invention is a conventional bonding material in which conductive particles are embedded near the surface of a sheet-like insulating base material made of a thermoplastic resin (Japanese Patent Application Laid-Open No. Sho 64-14).
886 JP) and can be used as well, whereby it becomes possible to improve the continuity reliability than electric connection method that used the conventional anisotropic conductive adhesive, the present invention By using the electrical connection method described above, even if a large number of terminals are formed on the circuit board at a fine pitch, the connection can be made without causing a short circuit. That is, according to the electrical connection method of the present invention, the conductive particles are held in one layer on the film.
Using conductive particles transfer type anisotropic conductive film, the conductive
The conductive particles of the particle transfer type anisotropic conductive film are transferred only to the terminals to be connected on the first circuit board, and then the first circuit board and the second circuit board are bonded via an adhesive. Therefore, the conductive particles do not exist in portions other than the terminals to be connected on the circuit board. Therefore, no short circuit occurs. Also, by increasing the density of the conductive particles of the conductive particle transfer type anisotropic conductive film, the number of conductive particles connecting between the terminals of the two circuit boards can be increased, so that the conduction reliability can be increased. Can be improved.

Further, unlike the conventional transfer bump method,
Since it is not necessary to form a bump on the IC chip or to position the bump and the circuit board, an electrical connection process between the two circuit boards is facilitated.

[0025]

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

Example 1 ME of polyester resin (VE3220, manufactured by Unitika)
0.15 parts by weight of isocyanate (Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) was added to 100 parts by weight of a K15% solution,
Benzoguanamine particles are nickel and gold-plated conductive particles (Bright 20GNR10EH, diameter 10 μm,
1.5 parts by weight of Nippon Chemical Industry Co., Ltd.
The average thickness of the polyimide film having a thickness of 25μm The dispersion was coated with a 5 [mu] m, the conductive particles transfer type anisotropically
A conductive film (area ratio of conductive particles, about 21%) was prepared.

Next, this conductive particle transfer type anisotropic conductive film is cut into an appropriate size to obtain TAB (thickness: 75 μm).
Placed on a polyimide film substrate having terminals formed by applying a solder plating (tin: lead = 8: 2) having a thickness of 1 μm to a copper having a thickness of 35 μm at a pitch of 0.1 mm,
The first compression bonding was performed at 190 ° C., 5 kg / cm ² for 5 seconds. After cooling, the conductive particle transfer type anisotropic conductive film was peeled off from the TAB. Observation of the appearance in the image processing apparatus, guide
About 70% of the conductive particles of the electroconductive particle transfer type anisotropic conductive film were transferred to TAB, and the area ratio of the conductive particles on the terminal was 15%.

Next, an epoxy-based adhesive film having the composition shown in Table 1 was preliminarily pressure-bonded to the TAB, and then a glass substrate on which an ITO pattern having a pitch of 0.1 mm was formed.
° C., and the pressure bonding at 40Kg / cm ^2, 20 sec.

[0029]

(Epoxy adhesive film composition) (Components) (parts by weight) Bisphenol A type epoxy (Ep1007, manufactured by Yuka Shell) 36.02 Bisphenol A type epoxy (Ep828, manufactured by Yuka Shell) 36.02 Epoxysilane Coupling agent (A187, Nippon Yunika) 1.95 Modified imidazole (Hx3748, Asahi Kasei Kogyo) 26.00

As a result, the initial resistance of the TAB and ITO patterns is 9Ω at the maximum, and the MIL STD 202F10
After aging for 1000 hours by 6E, the resistance was stable at 15Ω at the maximum. No short circuit occurred.

Example 2 A conductive particle transfer type anisotropic material was used in the same manner as in Example 1 except that 6 parts of solder particles (Sparkle Milon No. 1635MF, manufactured by Senju Metal Co., Ltd.) having a diameter of 10 μm were used as the conductive particles.
A conductive film was prepared.

This conductive particle transfer type anisotropic conductive film was first pressure-bonded to TAB in the same manner as in Example 1 and peeled off. As a result, the area ratio of the conductive particles on the terminals of the TAB was 18%.

Next, in the same manner as in the first embodiment, TAB and I
The glass substrate on which the TO pattern was formed was completely pressure bonded. As a result, the initial resistance is up to 8Ω and the MIL S
After aging by TD202F106E for 1000 hours, the maximum value was stable at 19Ω. No short circuit occurred.

Reference Example 1 After rubbing and charging a polyester release film with a cloth,
The same solder particles as in Example 2 were placed, and excess solder particles were wiped off to attach one layer of solder particles onto the polyester release film. The solder particles are converted into a heat-resistant adhesive tape (P
ET8083 (manufactured by Sony Chemical Co., Ltd.) using a hand roller to prepare a conductive particle transfer type anisotropic conductive film .

Next, TAB and I
The glass substrate on which the TO pattern was formed was completely pressure bonded. As a result, the initial resistance is at most 5Ω and the MIL S
Even after aging for 1000 hours by TD202F106E, it was stable at a maximum of 15Ω. No short circuit occurred.

COMPARATIVE EXAMPLE 1 30 resin particles similar to those in Example 2 were added to a resin binder having the same composition as the epoxy adhesive film used in Example 1.
phr was blended to prepare an anisotropic conductive film. When the particle area ratio of this anisotropic conductive film was measured, it was 20%.

Next, this anisotropic conductive film was sandwiched between the same TAB as in Example 1 and a glass substrate having an ITO pattern formed thereon, and pressed at 170 ° C., 40 kg / cm 2 for 20 seconds. As a result, the particle area ratio on the pattern was 17
%Met. The initial resistance is 7Ω at the maximum, and MIL
Even after aging by STD 202F106E for 1000 hours, the maximum value was stable at 19Ω, but the particles continued between the patterns, and short-circuiting occurred at four places in 120 pins.

[0038]

According to the present invention, when connecting terminals between two circuit boards, even if a large number of terminals to be connected are formed at a fine pitch on the circuit board, short-circuiting does not occur. The connection can be reliably and easily made so that high conduction reliability can be obtained.

[Brief description of the drawings]

FIG. 1 is a process explanatory view of an electrical connection method of the present invention.

FIG. 2 is a process explanatory view of the electrical connection method of the present invention.

[Explanation of symbols]

1 conductive particle transfer type anisotropic conductive film 2 film 3 conductive particles 4 binder layer 5 first circuit board 5a terminal of first circuit board 6 circuit board for electrical connection 7 second circuit board 7a second circuit Board terminals 8 Adhesive film

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI // H01R 12/06 H01R 9/09 C (56) References JP-A-2-54932 (JP, A) JP-A-63- 53805 (JP, A) JP-A-3-16147 (JP, A) JP-A-4-30532 (JP, A) JP-A-3-128937 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/60 311 H01L 21/60

Claims (2)

(57) [Claims] 1. An anisotropic conductive particle transfer type in which one layer of conductive particles is held by a binder layer formed on a film, and the conductive particles protrude from the binder layer.
Conductive film, the binder layer and thereby
The held conductive particles form the conductive particles in the resin binder.
Dispersed dispersion liquid, the thickness of the binder layer of the conductive particles
By applying on the film so that the particle size is less than
The conductive particles transfer type anisotropic conductive film, characterized in that those provided. 2. A method of terminal of the first circuit board and a terminal of the second circuit board are electrically connected, the conductive particles transfer type anisotropically of claim 1, wherein the terminal surface of the first circuit board Gender
Conductive film conductive particles causes <br/> superimposing a plane that is held in, and thermocompression bonding the two, only the conductive particles are transferred to the first circuit board of the terminal was peeled off, and then, the conductive particles A terminal surface of the first circuit board and the terminal surface of the second circuit board, onto which the surface has been transferred, is heated and pressed via an adhesive.