JP4110589B2 - Circuit connection member and circuit board manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a circuit connecting member and a method for manufacturing a circuit board which are formed between electrodes of two circuit boards, for example, in a liquid crystal panel or the like, and suitable for connecting both electrodes.
[0002]
[Prior art]
As adhesives that bond two circuit boards together and provide electrical continuity between these electrodes, thermoplastic materials such as styrene and polyester, and thermosetting materials such as epoxy and silicone are known. ing.
Among them, epoxy resin adhesives are widely used in various applications such as electricity, electronics, architecture, automobiles and airplanes because of their high adhesive strength and excellent water resistance and heat resistance. In particular, one-pack type epoxy resin adhesives are used in the form of films, pastes, and powders because they do not require mixing of the main agent and the curing agent and are easy to use. In this case, it is common to obtain specific performance by various combinations of an epoxy resin, a curing agent, and a modifier. For example, an attempt of JP-A-62-141083 is known.
[0003]
[Problems to be solved by the invention]
However, when connecting circuit boards facing each other with a circuit connecting material using a conventional epoxy resin adhesive, if the connection time is limited to, for example, 15 seconds, the adhesive strength of the connecting portion is insufficient at a temperature of 140 ° C. or lower. The connection reliability was not good.
In 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 force can be obtained under relatively low heating conditions of 140 ° C. or less, The circuit connection material having a working life of 10 hours or more and having good connection reliability is provided.
[0004]
[Means for Solving the Problems]
Circuit connecting member of the present invention is a circuit for connecting members of the anisotropic conductive characterized by consisting of the adhesive composition and conductive particles that mandatory components (1) to (4).
(1) Epoxidized polybutadiene (2) Naphthalene epoxy resin (3) Aromatic sulfonium salt (4) Phenoxy resin As the naphthalene epoxy resin (2), a cresol novolac / naphthol type epoxy resin is used. The average particle diameter of the conductive particles is preferably 2 to 18 μm, and the content of the conductive particles is preferably 0.1 to 10 parts (volume) with respect to 100 parts (volume) of the adhesive composition. The shape of the circuit connection member is a film. The method of manufacturing a circuit board according to the present invention includes 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. Between the first connection terminal and the second connection terminal arranged opposite to each other, the circuit connection member of the present invention is interposed between the first connection terminal and the first connection terminal arranged opposite to each other by heating and pressing. The second connection terminal is electrically connected.
[0005]
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 strength of the connection portion of 300 N / m or more, and have low activity at room temperature. As a result of intensive investigations on a connection material that can provide good connection reliability, the object is to use an adhesive composition essentially comprising the following components (1) to (4) and a circuit connection member made of conductive particles. The present invention has been completed by finding out what is achieved.
(1) Epoxidized polybutadiene (2) Naphthalene epoxy resin (3) Aromatic sulfonium salt (4) Phenoxy resin
DETAILED DESCRIPTION OF THE INVENTION
Epoxidized polybutadiene used in the present invention is polybutadiene partially epoxidized with double bonds. Epoxidized polybutadiene is superior in reactivity with aromatic sulfonium salts compared to bisphenol A type epoxy resins, etc., improves the towability of the adhesive composition, and improves the adhesion to metals such as copper. preferable. Moreover, it is preferable to set it as 1 to 50 weight% with respect to the whole resin component from the point of film-forming property or hardening reaction, and 5 to 20 weight% is more preferable.
[0007]
The naphthalene epoxy resin used in the present invention has a skeleton containing at least one naphthalene ring in one molecule, and includes naphthol, naphthalene diol, naphthol / cresol, and the like. Naphthalene-based epoxy resins are superior to other heat-resistant epoxy resins in various physical properties, improve the Tg of the cured product of the adhesive composition, and lower the linear expansion coefficient (α2) at high temperatures. It is more preferable from the point that it becomes possible. The blending amount is preferably 10 to 80% by weight based on the entire resin component from the viewpoint of film formability and curing reaction.
[0008]
Further, for this naphthalene-based epoxy resin, if necessary, for example, bisphenol type epoxy resin derived from epichlorohydrin and bisphenol A, F, AD, S, etc., epoxy novolac resin derived from epichlorohydrin and phenol novolac or cresol novolac, It is possible to use various epoxy compounds having two or more glycidyl groups in one molecule such as glycidylamine, glycidyl ester, biphenyl, alicyclic, and chlorine cyclic, or a mixture of two or more. . Among the above-mentioned mixable epoxy resins, bisphenol-type epoxy resins are preferable because grades having different molecular weights are widely available, and adhesiveness, reactivity, and the like can be arbitrarily set.
For these epoxy resins, it is preferable to use a high-purity product in which impurity ions (Na +, Cl-, etc.), hydrolyzable chlorine, etc. are reduced to 300 ppm or less to prevent electron migration.
[0009]
The latent curing agent used in the present invention is an aromatic sulfonium salt having a benzyl group, and this type of curing agent is preferable because it has characteristics of latency and rapid curing. 2-20 weight part is preferable with respect to 100 weight part of resin components from the reactive point, and, as for the compounding quantity of a hardening | curing agent, 4-10 weight part is more preferable.
It is preferable to use these curing agents coated with a polymer material such as polyurethane or polyester, a metal thin film such as Ni or Cu, and an inorganic material such as calcium silicate so that the pot life can be extended.
[0010]
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 there are other types such as bisphenol A type and AD type as well as the epoxy resin. Since these are similar in structure to epoxy resins, they have good compatibility and also have good adhesive properties. The larger the molecular weight, the easier the film-forming property is obtained, and the melt viscosity that affects the fluidity during connection can be set in a wide range. An average molecular weight of about 10,000 to 80,000 is more preferable from the viewpoints of melt viscosity and compatibility with other resins. When these resins contain polar groups such as hydroxyl groups and carboxyl groups, the compatibility with the epoxy resin is improved, and a film having a uniform appearance and characteristics can be obtained, and the reaction at the time of curing is accelerated. It is also preferable from the viewpoint of obtaining curing. The blending amount is preferably 20 to 80% by weight based on the entire resin component from the viewpoint of film formability and acceleration of the curing reaction. Further, bisphenol A type phenoxy resin or acrylic resin may be mixed as appropriate for adjusting the melt viscosity.
[0011]
In the adhesive composition obtained above, as usual additives, for example, fillers, softeners, accelerators, anti-aging agents, colorants, flame retardants, thixotropic agents, coupling agents and phenol resins, Curing agents such as melamine resins and isocyanates can also 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.
[0012]
Examples of the conductive particles include metal particles such as Au, Ag, Ni, Cu, and solder, carbon, and the like, and those in which the conductive layer described above is formed by coating or the like on non-conductive glass, ceramic, plastic, or the like. Good. In the case of using plastic as a core or hot-melt metal particles, it is preferable because it has deformability by heating and pressurization, so that the contact area with the electrode is increased at the time of connection and reliability is improved. The conductive particles are properly used in a wide range of 0.1 to 30 parts (volume) with respect to 100 parts (volume) of the adhesive component. In order to prevent an adjacent circuit from being short-circuited by excessive conductive particles, it is more preferably 0.1 to 10 parts (volume).
As the coupling agent, an amino group, an epoxy group, and an isocyanate group-containing material are particularly preferable from the viewpoint of improving adhesiveness.
[0013]
The adhesive composition of the present invention is particularly useful as a one-pack type adhesive, particularly as a film-like adhesive for bonding an IC chip and a substrate or bonding electrical circuits. In this case, for example, the adhesive composition obtained above is liquefied as a dispersion in the case of a solvent or an emulsion, and formed on a peelable substrate such as a release paper, or the compounded solution is formed on a substrate such as a nonwoven fabric. Is formed on a peelable substrate, dried at a temperature lower than the activation temperature of the curing agent, and the solvent or dispersion may be removed.
[0014]
The electrode connection using the circuit connection member obtained in the present invention will be described.
This method is an electrode connection method in which a circuit connection member is formed between opposing electrodes on a substrate, and contact between both electrodes and adhesion between the substrates are obtained by heating and pressing. As the substrate for forming the electrodes, semiconductors, inorganic substances such as glass and ceramics, organic substances such as polyimide and polycarbonate, and combinations of these composites such as glass / epoxy can be applied.
[0015]
The circuit connection member of the present invention can also be used when, for example, a semiconductor chip is bonded and fixed to a substrate and an adhesive film by a face-down method, and the electrodes are electrically connected.
That is, the first circuit member having the first connection terminal and the second circuit member having the second connection terminal are disposed so that the first connection terminal and the second connection terminal face 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 the first connection terminal and the second connection that are arranged to face each other by heating and pressing. A circuit board can be manufactured by electrically connecting terminals.
[0016]
As such a circuit member, a chip component such as a semiconductor chip, a resistor chip or a capacitor chip, a substrate such as a printed circuit board, or the like is used.
These circuit members are usually provided with a large number of connection terminals (or a single connection terminal in some cases), 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 connection terminals arranged opposite to each other, and the connection terminals arranged opposite to each other by heating and pressing are electrically connected to form a circuit board.
By heating and pressurizing at least one set of circuit members, the connection terminals arranged opposite to each other can be electrically connected by direct contact or through conductive particles of an anisotropic conductive adhesive.
[0017]
[Action]
In the present invention, by containing an epoxidized polybutadiene, a naphthalene-based epoxy resin, an aromatic sulfonium salt, and a phenoxy resin, high adhesive strength and High reliability can be obtained.
[0018]
【Example】
Hereinafter, the present invention will be described in detail based on examples. In addition, each compounding ratio is put together in Table 1 of FIG.
Example 1
From bisphenol A and epichlorohydrin, 40 g of bisphenol A type phenoxy resin (average molecular weight 30000) was prepared by a general method, and this was dissolved in a mixed solvent of toluene / ethyl acetate = 50/50 by weight ratio to obtain a solid content of 40%. Solution.
5 g of epoxidized polybutadiene (manufactured by Daicel Chemical Industries, Ltd., trade name Epolide 4700 (epoxy equivalent 165)) was used.
10 g of a naphthalene 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 by weight to make 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 ethyl acetate solution of benzylsulfonium salt (trade name Sun-Aid SI-60L, manufactured by Sanshin Chemical Industry Co., Ltd.) 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. Particles (gold plastic particles) were prepared.
The resin component is mixed, 5 parts by weight of a latent curing agent is blended with 100 parts by weight of the resin component, and 3% by volume of conductive particles are further dispersed and coated on a fluororesin film having a thickness of 80 μm. And a circuit connecting member having an adhesive layer thickness of 25 μm was obtained by drying with hot air at 70 ° C. for 10 minutes.
[0019]
Example 2
A connection member for a circuit was obtained in the same manner as in Example 1 except that the blending amount of the bisphenol A type liquid epoxy resin (Epicoat 828) was 30 g and the epoxidized polybutadiene (Epolide 4700) was 20 g.
[0020]
Example 3
A circuit connection member was obtained in the same manner as in Example 1, except that the blending amount of the bisphenol A type liquid epoxy resin (Epicoat 828) was 35 g and the naphthalene type epoxy resin (NC-7000) was 20 g.
[0021]
Example 4
A circuit connection member was obtained in the same manner as in Example 1 except that the bisphenol A liquid epoxy resin (Epicoat 828) was an acrylic rubber-dispersed epoxy resin (product name: BPA-328, manufactured by Nippon Shokubai Co., Ltd.).
[0022]
Example 5
A circuit connection member was obtained in the same manner as in Example 1 except that the conductive particles (gold plastic particles) were replaced with nickel particles having an average particle diameter of 2 μm and an aggregate particle diameter of 10 μm.
[0023]
Example 6
A circuit connection member was obtained in the same manner as in Example 1 except that the blending amount of the conductive particles (gold plastic particles) was 7% by volume.
[0024]
Example 7
A circuit connection member was obtained in the same manner as in Example 1 except that the addition amount of the curing agent (SI-60) was 7.5 parts by weight.
[0025]
Comparative Example 1
A latent curing agent and a bisphenol A type liquid epoxy resin (Epicoat 828) are replaced with an aromatic sulfonium salt (SI-60), and an imidazole-modified product is used as a nucleus, and the surface is coated with polyurethane. Circuit connection in the same manner as in Example 1 except that the capsule-type curing agent was a masterbatch-type curing agent (trade name Novacure 3941HP, manufactured by Asahi Kasei Kogyo Co., Ltd.) dispersed in a liquid bisphenol F-type epoxy resin. A member was obtained.
[0026]
Comparative Example 2
A circuit connection member was obtained in the same manner as in Example 1 except that the blending amount of the bisphenol A type liquid epoxy resin (Epicoat 828) was 50 g and the epoxidized polybutadiene (Epolide 4700) was eliminated.
[0027]
Comparative Example 3
A connection member for a circuit was obtained in the same manner as in Example 1 except that the amount of the bisphenol A type liquid epoxy resin (Epicoat 828) was 55 g and the naphthalene epoxy resin (NC-7000) was eliminated.
[0028]
Circuit connection Using the circuit connection member described above, flexible circuit boards (FPC) having 500 copper circuits with a line width of 50 μm, a pitch of 100 μm, and a thickness of 18 μm are heated and pressed at 140 ° C. and 2 MPa for 20 seconds to obtain a width. Connected over 2 mm. At this time, after pasting the adhesive surface of the circuit connection member on one FPC in advance, it was temporarily connected by heating and pressing at 70 ° C. and 0.5 MPa for 5 seconds, and then the fluororesin film was peeled off and the other Connected to the FPC.
Further, the above-mentioned FPC and glass (surface resistance 20Ω / port) on which a thin layer of indium oxide (ITO) was formed were heated and pressurized at 140 ° C. and 2 MPa for 20 seconds to be connected over a width of 2 mm. At this time, temporary connection was made to ITO glass in the same manner as described above.
[0029]
Measurement of Adhesive Strength of Connection Portion The adhesiveness between the adhesive used in the FPC and each adhesive composition was evaluated by measuring the adhesive force per 1 cm according to JIS-z0237 by a 90-degree peeling method. Two types of FPC were used, each using # 7100 (trade name, manufactured by Toray Industries, Inc.) and Yodogawa E (trade name, manufactured by Yodogawa Paper Co., Ltd.) as an adhesive. Then, using these two types of FPCs, circuit connected bodies were produced and measured. As a measuring device, Tensilon UTM-4 (peeling speed 50 mm / min, 25 ° C.) manufactured by Toyo Baldwin Co., Ltd. was used.
The measurement results are shown in Table 2 of FIG. In Examples 1 to 7 and Comparative Example 3 using epoxidized polybutadiene and aromatic sulfonium salt, good adhesive strength was obtained regardless of the type of adhesive of FPC. However, in Comparative Examples 1 and 2 where no epoxidized polybutadiene or aromatic sulfonium salt is used, the adhesive strength is weak. This is because a sufficient reaction can be obtained with the aromatic sulfonium salt, and the adhesive strength is greatly improved by the epoxidized polybutadiene. Comparative Example 3 has a low adhesive force due to insufficient reaction.
[0030]
After the connection resistance measurement circuit is connected, the resistance value between adjacent circuits of the FPC including the connection part is measured with a multimeter after being initially held in a constant temperature and humidity chamber at 85 ° C. and 85% RH for 500 hours. did. The resistance value is shown as an average (x + 3σ) of 150 resistances between adjacent circuits.
These results are shown in Table 2 of FIG. The connection members for circuits obtained in Examples 1 to 7 and Comparative Example 2 showed good connectivity. On the other hand, Comparative Example 3 using no naphthalene-based epoxy and Comparative Example 1 using HX-3941HP as a latent curing agent have poor adhesive properties and poor adhesion due to insufficient curing reaction. The increase in resistance after the constant temperature and humidity test was remarkable.
[0031]
【The invention's effect】
As described above in detail, according to the present invention, when connecting circuit boards facing each other, even when the connection time is limited to 10 to 20 seconds, relatively low heating conditions of 140 ° C. or lower are sufficient. It has become possible to provide a connection member for a circuit suitable as an electrical / electronic adhesive that can obtain an adhesive force and has good connection reliability.
In addition, the circuit board manufacturing method of the present invention makes it possible to manufacture a circuit board with excellent reliability.
[Brief description of the drawings]
FIG. 1 is a table showing the compounding ratio (Table 1) of Examples, and the measurement results (Table 2) of the adhesive strength and connection resistance of connecting portions.

Claims (6)

An anisotropic conductive 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   The circuit connection member according to claim 1, wherein the naphthalene-based epoxy resin (2) is a cresol novolac / naphthol type epoxy resin.   The circuit connection member according to claim 1, wherein the conductive particles have an average particle diameter of 2 to 18 μm.   The circuit connection member according to any one of claims 1 to 3, wherein the content of the conductive particles is 0.1 to 10 parts (volume) with respect to 100 parts (volume) of the adhesive composition.   The circuit connection member according to any one of claims 1 to 4, wherein the shape is a film shape.   A first circuit member having a first connection terminal and a second circuit member having a second connection terminal are disposed so that the first connection terminal and the second connection terminal are opposed to each other, and the opposed arrangement is performed. The circuit connection member according to any one of claims 1 to 5 is interposed between the first connection terminal and the second connection terminal, and the first connection terminal and the second connection terminal disposed opposite to each other by heating and pressing. A method of manufacturing a circuit board in which two connection terminals are electrically connected.

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