JPH10273635A - Connecting member for circuit and production of circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject connecting member capable of connecting a circuit board in high adhesiveness and high reliability in the connection while maintaining both properties of rapid curing property and shelf life by including an epoxidized polybutadiene, a naphthalene-based epoxy resin, an aromatic sulfonium salt and a phenoxy resin. SOLUTION: This connecting member comprises an adhesive composition consisting essentially of (A) an epoxidized polybutadiene, (B) a naphthalene-based epoxy resin (preferably cresol-novolak/naphthol type epoxy resin), (C) an aromatic sulfonium salt and (D) a phenoxy resin and (E) electroconductive particles (preferably having 2-18 μm average particle diameter). Furthermore, preferably, the content of the component A is 1-50 wt.% and the content of the component B is 10-80 wt.% and the content of the component D is 20-80 wt.% based on total amount of resin components and the component C is preferably used in an amount of 2-20 pts.wt. based on 100 pts.wt. resin component, and the component E is preferably used in an amount of 0.1-30 pts. vol. based on 100 pts. vol. adhesive component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit connecting member which is formed between electrodes of two circuit boards in a liquid crystal panel or the like and is suitable for connecting both electrodes, and a method of manufacturing a circuit board. It is.

[0002]

2. Description of the Related Art Along with bonding two circuit boards together,
As an adhesive for obtaining electrical conduction between these electrodes, a styrene-based or polyester-based thermoplastic material, or an epoxy-based or silicone-based thermosetting material is known. Among them, epoxy resin-based adhesives have high adhesive strength and are excellent in water resistance and heat resistance.
It is frequently used for various purposes such as construction, automobiles, and aircraft.
In particular, one-pack type epoxy resin-based adhesives are used in the form of a film, paste, or powder because they do not need to be mixed with a main agent and a curing agent and are easy to use. In this case, it is general to obtain a specific performance by various combinations of an epoxy resin and a curing agent and a modifier,
For example, the trial of Japanese Patent Application Laid-Open No. 62-141083 is known.

[0003]

However, in a conventional circuit connecting material using an epoxy resin-based adhesive, when connecting circuit boards facing each other, the connection time is reduced to, for example, one.
When the time is limited to 5 seconds, at a temperature of 140 ° C. or lower, the adhesive strength of the connection portion is insufficient, and the connection reliability is not good.
The present invention provides a method for connecting circuit boards facing each other, even when the connection time is limited to 10 to 20 seconds.
Sufficient adhesive strength can be obtained under relatively low temperature heating conditions of 40 ° C. or less, and a pot life of 10 hours or more at room temperature.
It is to provide a circuit connection material having good connection reliability.

[0004]

According to the present invention, there is provided a circuit connecting member comprising an adhesive composition having the essential components (1) to (4) and conductive particles. (1) Epoxidized polybutadiene (2) Naphthalene-based epoxy resin (3) Aromatic sulfonium salt (4) Phenoxy resin As the naphthalene-based epoxy resin (2), a cresol novolak / naphthol type epoxy resin is used.
The average particle size of the conductive particles is preferably from 2 to 18 μm, and the content of the conductive particles is preferably from 0.1 to 10 parts (by volume) based on 100 parts (by volume) of the adhesive composition. The shape of the circuit connecting member is used in the form of a film. The method for manufacturing a circuit board of the present invention includes a first circuit member having a first connection terminal,
A second circuit member having a second connection terminal, the first connection terminal and the second connection terminal are arranged facing each other, between the first connection terminal and the second connection terminal arranged facing each other. The circuit connecting member of the present invention is interposed therebetween, and the first connecting terminal and the second connecting terminal arranged opposite to each other are electrically connected by heating and pressing.

That is, the present inventors can connect circuit conductors facing each other on two circuit boards by heating at 140 ° C. for about 20 seconds, have an adhesive force of 300 N / m or more at room temperature, and at room temperature. As a result of intensive studies on a connection material having low activity and good connection reliability, the object of the present invention is to provide an adhesive composition essentially comprising the following components (1) to (4) and a circuit material comprising conductive particles. The present invention has been completed by finding out what can be achieved by the connecting member. (1) Epoxidized polybutadiene (2) Naphthalene epoxy resin (3) Aromatic sulfonium salt (4) Phenoxy resin

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The epoxidized polybutadiene used in the present invention is a polybutadiene in which a double bond is partially epoxidized. Epoxidized polybutadiene has better reactivity with aromatic sulfonium salts than bisphenol A type epoxy resin, etc., improves the towability of the adhesive composition, and improves the adhesive strength with metals such as copper. preferable. The amount is preferably from 1 to 50% by weight, more preferably from 5 to 20% by weight, based on the whole resin component from the viewpoint of film forming properties and curing reaction.

The naphthalene-based epoxy resin used in the present invention has a skeleton containing at least one naphthalene ring in one molecule, and includes naphthol-based, naphthalene-diol-based, and naphthol / cresol-based. Naphthalene-based epoxy resin has excellent physical properties compared to other heat-resistant epoxy resins, and also improves the Tg of the cured product of the adhesive composition, and lowers the linear expansion coefficient (α2) in a high-temperature region. Is more preferable in that it becomes possible. The amount is preferably from 10 to 80% by weight based on the whole resin component from the viewpoint of film forming properties and curing reaction.

[0008] Further, the naphthalene epoxy resin may be, if necessary, for example, a bisphenol type epoxy resin derived from epichlorohydrin and bisphenol A, F, AD, S, etc., or an epoxy novolak derived from epichlorohydrin and phenol novolak or cresol novolak. Resin, glycidylamine, glycidyl ester, biphenyl, alicyclic, chlorinated, etc.
Various epoxy compounds having at least two glycidyl groups can be used alone or in combination of two or more. Among the above mixable epoxy resins, bisphenol-type epoxy resins are preferred because grades having different molecular weights are widely available and adhesiveness and reactivity can be arbitrarily set. These epoxy resins contain impurity ions (Na +, Cl-, etc.) and hydrolyzable chlorine
It is preferable to use a high-purity product reduced to ppm or less in order to prevent electron migration.

The latent curing agent used in the present invention is an aromatic sulfonium salt having a benzyl group.
It is preferable because it has the characteristics of latency and rapid curing. The amount of the curing agent is preferably 2 to 20 parts by weight, more preferably 4 to 10 parts by weight, based on 100 parts by weight of the resin component from the viewpoint of reactivity. These curing agents are polyurethane-based,
Microcapsules coated with a polymer substance such as a polyester-based substance, a metal thin film such as Ni or Cu, and an inorganic substance such as calcium silicate are preferable because the pot life can be extended.

The phenoxy resin used in the present invention will be described. The bisphenol F-type phenoxy resin corresponds to a high-molecular-weight epoxy resin having a molecular weight of 10,000 or more determined by high-performance liquid chromatography (HLC), and similarly to the epoxy resin, there are other types such as bisphenol A type and AD type. Since these have similar structures to epoxy resins, they have good compatibility and good adhesiveness. The larger the molecular weight, the more easily the film-forming property can be obtained, and the melt viscosity which affects the fluidity at the time of connection can be set in a wide range. The average molecular weight is 10,000 to 800
A value of about 00 is more preferable from the viewpoint of the melt viscosity and compatibility with other resins. When these resins contain a polar group such as a hydroxyl group or a carboxyl group, the compatibility with the epoxy resin is improved, and a film having a uniform appearance and properties can be obtained. It is preferable from the viewpoint of obtaining curing. From the viewpoint of promoting film forming property and curing reaction, the amount of the compound is 20
It is preferably set to 80% by weight. Further, bisphenol A type phenoxy resin or acrylic resin may be appropriately mixed for adjusting the melt viscosity.

In the adhesive composition obtained above, for example, fillers, softeners, accelerators, antioxidants, coloring agents, flame retardants, thixotropic agents, coupling agents, and the like, as ordinary additives, etc. A curing agent such as a phenol resin, a melamine resin, and an isocyanate may be contained. Among these, conductive particles, fillers such as titanium oxide and silica, and coupling agents of various systems such as silane, titanium, chromium, zirconium, and aluminum are particularly effective.

As the conductive particles, Au, Ag, Ni,
There are metal particles such as Cu and solder, carbon, and the like, and the conductive layer described above may be formed by coating the above conductive layer with non-conductive glass, ceramic, plastic, or the like.
In the case of plastic core or hot melt metal particles,
Heat and pressure are preferable because they have deformability, so that the contact area with the electrode increases during connection and reliability is improved. The conductive particles are used in an amount of 0.1 part based on 100 parts (volume) of the adhesive component.
Use up to 30 parts (volume) depending on the application. In order to prevent a short circuit or the like in an adjacent circuit due to excessive conductive particles, the amount is more preferably 0.1 to 10 parts (volume). As coupling agents, amino groups, epoxy groups,
And isocyanate group-containing materials are particularly preferred from the viewpoint of improving the adhesiveness.

The adhesive composition of the present invention is particularly useful as a one-part adhesive, particularly as a film adhesive for bonding an IC chip to a substrate or bonding electric circuits.
In this case, for example, the adhesive composition obtained above is liquefied as a dispersion or the like in the case of a solvent or an emulsion, and formed on a release substrate such as release paper, or the compounding solution is applied to a substrate such as a nonwoven fabric. May be formed on the peelable substrate by impregnation, dried at a temperature lower than the activation temperature of the curing agent, and the solvent or the dispersion may be removed.

The connection of the electrodes using the circuit connecting member obtained by the present invention will be described. In this method, a circuit connecting member is formed between opposing electrodes on a substrate, and the electrodes are connected by heating and pressing to obtain contact between the two electrodes and adhesion between the substrates. As a substrate on which electrodes are formed, inorganic materials such as semiconductors, glass, and ceramics, organic materials such as polyimide and polycarbonate, and combinations of these composite materials such as glass / epoxy can be used.

Further, the circuit connecting member of the present invention can be used, for example, when a semiconductor chip is adhered and fixed to a substrate with an adhesive film by a face-down method and both electrodes are electrically connected. That is, a first circuit member having a first connection terminal, and a second circuit member having a second connection terminal, the first connection terminal and the second connection terminal are arranged facing each other, The connection material (film adhesive) of the present invention is interposed between the first connection terminal and the second connection terminal that are arranged to face each other, and heated and pressurized, and the first connection terminal and the second connection that are arranged to face each other. The circuit board can be manufactured by electrically connecting the terminals.

Such circuit members include chip parts such as semiconductor chips, resistor chips, and capacitor chips.
A board such as a printed board is used. These circuit members are usually provided with a large number of connection terminals (in some cases, a single connection terminal may be provided), and at least one set of the circuit members is arranged so that at least a part of the connection terminals provided on the circuit members are opposed to each other. Then, an adhesive is interposed between the opposed connection terminals and heated and pressed to electrically connect the opposed connection terminals to form a circuit board. By heating and pressurizing at least one set of circuit members, the connection terminals arranged to face each other can be electrically connected by direct contact or via conductive particles of an anisotropic conductive adhesive.

[0017]

According to the present invention, epoxidized polybutadiene, naphthalene-based epoxy resin, aromatic sulfonium salt, and phenoxy resin are contained to obtain both fast-curing property and preservation property, and are high regardless of the type of circuit board. Adhesive strength and high reliability can be obtained.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. The respective mixing ratios are summarized in Table 1 in FIG. Example 1 Bisphenol A-type phenoxy resin (average molecular weight 30,000) 4 from bisphenol A and epichlorohydrin
0 g was prepared by a general method, and this was dissolved in a mixed solvent of toluene / ethyl acetate = 50/50 by weight to obtain a solution having a solid content of 40%. Epoxidized polybutadiene (Eporide 47, manufactured by Daicel Chemical Industries, Ltd.)
00 (epoxy equivalent: 165)) was used in an amount of 5 g. 10 g of a naphthalene-based epoxy resin (trade name: NC-7000, manufactured by Nippon Kayaku Co., Ltd.) was dissolved in a mixed solvent of toluene / methyl ethyl ketone = 50/50 at a weight ratio to obtain a 50% solution. 45 g of bisphenol A liquid epoxy resin (Epicoat 828, manufactured by Yuka Shell Co., Ltd.) was used. As the latent curing agent, a 50% by weight solution of benzylsulfonium salt in ethyl acetate (manufactured by Sanshin Chemical Industry Co., Ltd., trade name: Sun Aid SI-60L) was used. A nickel layer having a thickness of 0.2 μm is provided on the surface of particles having polystyrene as a core, and a gold layer having a thickness of 0.02 μm is provided outside the nickel layer. The conductive layer has an average particle size of 10 μm and a specific gravity of 2.0. Particles (gold plastic particles) were produced. The above resin component is mixed and a latent curing agent 5 is added to 100 parts by weight of the resin component.
Parts by weight, and further, 3% by volume of conductive particles are mixed and dispersed, applied to a fluororesin film having a thickness of 80 μm using a coating device, and dried at 70 ° C. for 10 minutes with hot air to obtain a thickness of the adhesive layer. Of 25 μm was obtained.

Example 2 Bisphenol A type liquid epoxy resin (Epicoat 82)
Example 1 was repeated except that the blending amount of 8) was 30 g and the epoxidized polybutadiene (Eporide 4700) was 20 g.
In the same manner as in the above, a circuit connecting member was obtained.

Example 3 Bisphenol A type liquid epoxy resin (Epicoat 82
A circuit connecting member was obtained in the same manner as in Example 1, except that the blending amount of 8) was 35 g and the naphthalene-based epoxy resin (NC-7000) was 20 g.

Example 4 Bisphenol A type liquid epoxy resin (Epicoat 82
A circuit connecting member was obtained in the same manner as in Example 1 except that 8) was changed to an acrylic rubber-dispersed epoxy resin (trade name: BPA-328, manufactured by Nippon Shokubai Co., Ltd.).

Example 5 Conductive particles (gold plastic particles) were mixed with an average particle size of 2 μm.
m, and a connection member for a circuit was obtained in the same manner as in Example 1, except that nickel particles having an aggregate particle size of 10 μm were used.

Example 6 The amount of the conductive particles (gold plastic particles) was 7% by volume.
Other than that described above, a circuit connecting member was obtained in the same manner as in Example 1.

Example 7 A circuit connecting member was obtained in the same manner as in Example 1 except that the amount of the curing agent (SI-60) was changed to 7.5 parts by weight.

Comparative Example 1 A latent curing agent and a bisphenol A type liquid epoxy resin (Epicoat 828) were replaced with an aromatic sulfonium salt (SI-60), and an imidazole-modified product was used as a nucleus, and the surface was coated with polyurethane. Example 1 was the same as Example 1 except that a microcapsule-type curing agent having an average particle size of 5 μm was used as a masterbatch-type curing agent (manufactured by Asahi Kasei Kogyo Co., Ltd., trade name NOVACURE 3941HP) dispersed in a liquid bisphenol F type epoxy resin. Similarly, a circuit connecting member was obtained.

Comparative Example 2 Bisphenol A type liquid epoxy resin (Epicoat 82
A circuit connecting member was obtained in the same manner as in Example 1 except that the blending amount of 8) was changed to 50 g and the naphthalene-based epoxy resin (NC-7000) was eliminated.

Comparative Example 3 Bisphenol A type liquid epoxy resin (Epicoat 82
A circuit connecting member was obtained in the same manner as in Example 1, except that the blending amount of 8) was 55 g and the epoxidized polybutadiene (Epolide 4700) was eliminated.

Circuit Connection Using the above-described circuit connection member, a flexible circuit board (FPC) having 500 copper circuits having a line width of 50 μm, a pitch of 100 μm, and a thickness of 18 μm is connected at 140 ° C., 2M
It was heated and pressed at Pa for 20 seconds and connected over a width of 2 mm. At this time, after the adhesive surface of the circuit connecting member is pasted on one FPC in advance, it is temporarily connected by heating and pressing at 70 ° C. and 0.5 MPa for 5 seconds, and then the fluororesin film is peeled off and the other side is removed. FPC. In addition, the aforementioned FP
C at a temperature of 140 ° C. and 2 MPa at a temperature of 140 ° C. and 2 MPa.
It was heated and pressurized for 2 seconds and connected over a width of 2 mm. At this time, a temporary connection was made to the ITO glass in the same manner as described above.

Measurement of Adhesive Strength of Connection Portion The adhesiveness between the adhesive used for the FPC and each adhesive composition was evaluated by measuring the adhesive force per 1 cm by a 90-degree peeling method according to JIS-z0237. . The used FPCs are # 7100 (trade name, manufactured by Toray Industries, Inc.) and Egawa E
(Manufactured by Tomoegawa Co., Ltd., trade name) were used as adhesives to produce two types. Then, using the two types of FPCs, circuit connected bodies were manufactured and measured. The measuring device is Tensilon UTM manufactured by Toyo Baldwin Co., Ltd.
-4 (peeling speed 50 mm / min, 25 ° C.) was used. The measurement results are shown in Table 2 of FIG. In Examples 1 to 7 and Comparative Example 3 using the epoxidized polybutadiene and the aromatic sulfonium salt, good adhesive strength was obtained irrespective of the type of the FPC adhesive. However, in Comparative Examples 1 and 2, in which the epoxidized polybutadiene and the aromatic sulfonium salt were not used, the adhesive strength was weak. This is because a sufficient reaction is obtained by the aromatic sulfonium salt, and the adhesive strength is remarkably improved by the epoxidized polybutadiene. Comparative Example 3 has a low adhesive strength due to insufficient reaction.

Measurement of connection resistance After connecting the circuits, the resistance value between the adjacent circuits of the FPC including the above-mentioned connection portion was initially and for 500 hours kept in a thermo-hygrostat at 85 ° C. and 85% RH. It was measured with a meter.
Resistance value is the average of 150 points of resistance between adjacent circuits (x + 3σ)
Indicated by The results are shown in Table 2 of FIG. Example 1
To 7, and the circuit connecting members obtained in Comparative Example 2 exhibited good connectivity. On the other hand, Comparative Example 3 using no naphthalene-based epoxy, HX-3941 as a latent curing agent
In Comparative Example 1 using HP, the adhesive property was poor due to insufficient adhesive properties and insufficient curing reaction, and the resistance after the constant temperature and humidity test was remarkably increased.

[0031]

As described in detail above, according to the present invention,
When connecting circuit boards facing each other, even when the connection time is limited to 10 seconds to 20 seconds, sufficient adhesive strength can be obtained under relatively low temperature heating conditions of 140 ° C. or less, and connection reliability is good. Thus, it has become possible to provide a circuit connecting member suitable as an electric / electronic adhesive.
Further, the method for manufacturing a circuit board of the present invention has made it possible to manufacture a highly reliable circuit board.

[Brief description of the drawings]

FIG. 1 is a table showing the mixing ratio (Table 1) of the examples and the measurement results (Table 2) of the adhesive strength and the connection resistance of the connection portion.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H05K 3/38 H05K 3/38 E (72) Inventor Itsuo Watanabe 48 Tsudai, Tsukuba-shi, Ibaraki Pref.

Claims (6)

[Claims] 1. A circuit connecting member comprising an adhesive composition essentially comprising the components (1) to (4) and conductive particles. (1) Epoxidized polybutadiene (2) Naphthalene epoxy resin (3) Aromatic sulfonium salt (4) Phenoxy resin 2. The circuit connecting member according to claim 1, wherein the naphthalene epoxy resin (2) is a cresol novolak / naphthol type epoxy resin. 3. The circuit connecting member according to claim 1, wherein the conductive particles have an average particle size of 2 to 18 μm. 4. The adhesive composition according to claim 1, wherein the content of the conductive particles is
The circuit connecting member according to any one of claims 1 to 3, wherein the amount is 0.1 to 10 parts (volume) with respect to 0 part (volume). 5. The circuit connecting member according to claim 1, wherein the shape is a film. 6. A first circuit member having a first connection terminal and a second circuit member having a second connection terminal are arranged with the first connection terminal and the second connection terminal facing each other. The circuit connecting member according to any one of claims 1 to 5 is interposed between the first connection terminal and the second connection terminal arranged opposite to each other, and the first connection terminal arranged oppositely by heating and pressing. A method of manufacturing a circuit board for electrically connecting a second connection terminal to a circuit board.