JP2009275102A - Circuit connecting material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit connecting material for electric and electronic use required to have excellent heat-resistance and workability and especially quick curing properties. <P>SOLUTION: The circuit connecting material includes an adhesive composition and electrically conductive particles as components, wherein the adhesive composition contains a phenoxy resin, an alkylene oxide-modified bisphenol A epoxy resin, core-shell-type MBS (methacryl-butadiene-styrene) fine particles, and a latent epoxy curing agent. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a circuit connecting material.

Epoxy resin adhesives are widely used in various applications such as electricity, electronics, architecture, automobiles, and aircraft because of their high adhesive strength and excellent water resistance and heat resistance. Among them, 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 curing agent and are easy to use (for example, patents) Reference 1). In addition, an attempt to select an epoxy resin having various structures according to the intended use is known (for example, Patent Document 2). Recently, a radical curable adhesive using an acrylate derivative or a methacrylate derivative (hereinafter referred to as a (meth) acrylate derivative) and a peroxide which is a radical polymerization initiator has attracted attention. Radical curing can be cured in a short time because radicals that are reactive species are rich in reactivity (see, for example, Patent Documents 2 and 3).
JP-A-62-141083 Japanese Patent Application Laid-Open No. 08-315885 JP 2002-203427 A International Publication No. 98/044067 Pamphlet

  However, the film-like adhesive disclosed in Patent Document 1 has a disadvantage that heat resistance and moisture resistance are insufficient although it is excellent in workability. This is because a catalyst-type curing agent that is inert at room temperature is used for the purpose of obtaining good stability by coexistence of short-term curability (fast curability) and storage stability (storability). This is because a sufficient reaction cannot be obtained upon curing. In addition, in the case of polyaddition types such as acid anhydrides, aromatic amines, and polyphenols, which are hardeners frequently used for heat-resistant applications, curing requires several hours or more, and workability is insufficient. It is.

  Further, naphthalene-based epoxy resins as disclosed in Patent Document 2 have a naphthalene skeleton having a planar structure, so that steric hindrance is small and the reaction is easy, so that general bisphenol A and bisphenol F types and the like are used. Compared with epoxy resin, it has the property of having fast curability. However, there is also an improvement in that the rigidity of the naphthalene skeleton makes the cured product rigid and the adhesiveness is disadvantageous.

In addition, the radical curable adhesives described in Patent Documents 3 and 4 are difficult to obtain by the above-mentioned epoxy polymerization reaction, and can be connected at a low temperature and for a short time, but are hydrophilic and have a possibility of hydrolysis. Therefore, it is easy to absorb moisture during storage, and may cause a hydrolysis reaction due to moisture absorbed. That is, in the handling method, it is necessary to prevent moisture absorption as much as possible, and there is a problem of workability.
The present invention has been made in view of these problems, and it is an object of the present invention to provide an electrical / electronic circuit connection material which is excellent in heat resistance and workability and particularly requires short-time curing characteristics.

In order to solve the above problems, the present invention relates to the following.
1. In the circuit connecting material having the adhesive composition and conductive particles as components, the adhesive composition comprises a phenoxy resin, an alkylene oxide-modified bisphenol A type epoxy resin, core / shell type MBS (methacrylic / butadiene / styrene) fine particles, A circuit connection material containing an epoxy latent hardener.
2. Item 2. The circuit connecting material according to Item 1, wherein the phenoxy resin has a weight average molecular weight (Mw) of 10,000 or more.
3. Item 3. The circuit connection material according to Item 1 or 2, wherein the alkylene oxide-modified bisphenol A type epoxy resin is a propylene oxide modified bisphenol A type epoxy resin.
4). Item 4. The circuit connection material according to any one of Items 1 to 3, wherein the primary particle size of the core-shell type MBS fine particles is 100 to 300 nm.
5. Item 5. The circuit connection material according to any one of Items 1 to 4, wherein the conductive particles have an average particle size of 2 to 18 μm.
6). Item 6. The circuit connection material according to any one of Items 1 to 5, wherein the content of the conductive particles is 0.1 to 30 parts by volume with respect to 100 parts by volume of the adhesive composition.
7). Item 7. The circuit connection material according to any one of Items 1 to 6, wherein the shape is a film.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the circuit connection material suitable as an adhesive agent for electric / electronics for which a short-time curing characteristic is required.

In the present invention, the adhesive composition contains a phenoxy resin, an alkylene oxide-modified bisphenol A type epoxy resin, core / shell type MBS fine particles, and a latent curing agent.
First, the phenoxy resin that can be used in the present invention will be described. The phenoxy resin corresponds to a high molecular weight epoxy resin having a weight average molecular weight of 10,000 or more obtained from high performance liquid chromatography (HLC), and there are types such as bisphenol A type, F 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. As the molecular weight increases, film formability can be obtained more easily, and the melt viscosity that affects fluidity during connection can be set in a high range. The weight average molecular weight is usually 10,000 to 150,000, and more preferably 10,000 to 80,000 from the viewpoint of melt viscosity and compatibility with other resins. When the weight average molecular weight is less than 10,000, the film formability as an adhesive film tends to be lowered, and when it exceeds 150,000, the fluidity of the resin at the time of connection tends to be lowered.

In addition, the weight average molecular weight prescribed | regulated by this application means what was measured using the analytical curve by a standard polystyrene by the gel permeation chromatography method (GPC) according to the following conditions.
<GPC conditions> Equipment used: Hitachi L-6000 (Hitachi, Ltd.), column: Gel Pack GL-R420 + Gel Pack GL-R430 + Gel Pack GL-R440 (3 in total) [trade name, manufactured by Hitachi Chemical Co., Ltd.], elution Liquid: Tetrahydrofuran, Measurement temperature: 40 ° C., Flow rate: 1.75 ml / min, Detector: L-3300RI [Hitachi, Ltd.]
When these resins contain polar groups such as hydroxyl groups and carboxyl groups, compatibility with epoxy resins is improved, and films having a uniform appearance and characteristics can be obtained, and curing can be carried out for a short time by promoting reaction during curing. It is preferable also from the point which obtains.

  The alkylene oxide-modified bisphenol A type epoxy resin used in the present invention preferably has at least two alkylene oxide units in one molecule. Specifically, an epoxy resin obtained by adding an alkylene such as ethylene or propylene when bisphenol A is reacted with epichlorohydrin can be mentioned. Since these alkylene oxide-modified bisphenol A type epoxy resins have an alkylene chain that is a flexible skeleton as compared with other epoxy resins, the curing stress generated during curing shrinkage can be reduced. Moreover, since the basic skeleton is of bisphenol A type, the cured product can give good heat resistance and adhesiveness. Among these, since the propylene oxide modified epoxy resin has a longer alkylene chain than ethylene, the viscosity of the epoxy resin becomes low. This is more preferable from the viewpoint of the handleability of the resin and the fluidity at the time of connection.

Further, for this alkylene oxide-modified epoxy resin, as required, 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 In addition, various epoxy compounds having two or more glycidyl groups in one molecule such as glycidylamine, glycidyl ester, biphenyl, alicyclic, and chlorine cyclic may be used alone or in combination of two or more. Is possible. 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.

  MBS used in the present invention refers to those having a core-shell structure in which methacrylic acid and styrene are graft-polymerized on the surface of butadiene rubber fine particles. The MBS fine particles preferably have a primary particle size of 100 to 300 nm. If it is smaller than 100 nm, the fluidity of the resin tends to be reduced, and if it is larger than 300 nm, sufficient stress relaxation is difficult to obtain.

Next, the blending amount will be described. It is assumed that phenoxy resin and epoxy resin are 100% by weight as resin components, and the amount of MBS fine particles is defined as a ratio to this.
That is, the phenoxy resin is desirably 40 to 60% by weight from the viewpoint of film forming property and epoxy resin curing reaction. Since the epoxy resin is an amount obtained by subtracting the amount of the phenoxy resin from 100% by weight of the resin component, the amount is preferably 40 to 60% by weight. If the epoxy resin is less than 40% by weight, the resin strength after curing tends to be insufficient, and if it exceeds 60% by weight, the film formability tends to be lowered. The MBS fine particles are desirably 10 to 30% by weight with respect to 100% by weight of the resin component. When the amount is less than 10% by weight, the stress relaxation ability is hardly exhibited, and the improvement of the adhesive force is hardly obtained. If it exceeds 30% by weight, the flow of the adhesive is inhibited and the connection resistance is increased.

  Examples of the latent curing agent include onium salts such as sulfonium salts, phosphonium salts, and ammonium salts, and these can be used alone or as a mixture of two or more. These are cationic polymerization type so-called ion-polymerizable catalyst-type curing agents, which are preferable because they are easy to obtain fast curability and less chemical equivalent considerations are required.

  In the adhesive composition obtained above, as usual additives, for example, fillers, softeners, accelerators, anti-aging agents, colorants, flame retardants, thixotropic agents, coupling agents, phenol resins, etc. It is also possible to contain a curing agent. Among these, conductive particles, fillers such as silica, and coupling agents of various systems such as silane, titanium, chromium, zirconium, and aluminum are particularly effective.

  As the conductive particles, there are metal particles such as Au, Ag, Ni, Cu, and solder, carbon, etc., and these and non-conductive glass, ceramics, plastics, etc. formed by coating the above-mentioned conductive layer. 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 by volume with respect to 100 parts by volume of the adhesive component (adhesive composition). In order to prevent an adjacent circuit from being short-circuited by excessive conductive particles, the amount is more preferably 0.1 to 10 parts by volume. As a coupling agent, an epoxy group, an acryl group, and a vinyl group-containing material are particularly preferable from the viewpoint of improving adhesiveness.

  In the present invention, the adhesive composition is usually useful as a one-pack type adhesive, particularly as a film adhesive for bonding an IC chip and a substrate or bonding electrical circuits to each other. 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 emulsion, and formed on a releasable substrate such as a release paper, or the compounded liquid 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. At this time, the solvent to be used is preferably an aromatic hydrocarbon-based and oxygen-containing mixed solvent in order to improve the solubility of the material. Here, the SP value of the oxygen-containing solvent is preferably in the range of 8.1 to 10.7 in terms of protection of the latent curing agent, and acetates are more preferable. The boiling point of the solvent can be 150 ° C. or less. When the boiling point exceeds 150 ° C., a high temperature is required for drying, which is close to the activation temperature of the latent curing agent, resulting in a decrease in the latency, and a low workability at the time of drying. For this reason, the boiling point is preferably 60 to 150 ° C, more preferably 70 to 130 ° C.

  The connection of the electrode using the circuit connection material obtained by this invention is demonstrated. This method is a method for connecting electrodes in which a circuit connecting material 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.

  In the present invention, by containing a phenoxy resin, an alkylene oxide-modified epoxy resin and a latent curing agent, it is possible to improve the short-time connectivity while obtaining both fast curing and storage stability. is there. The reason for this is that the presence of a hydroxyl group in the phenoxy resin accelerates the curing reaction of the alkylene oxide-modified epoxy resin to enable fast curing, but the cationic polymerization rate of the epoxy resin itself is fast, The present invention is not limited to those having this function. In addition, since the phenoxy resin has a high molecular weight and a relatively high viscosity, it may be possible to obtain good preservability because it is difficult to come in contact with the latent curing agent in the normal temperature range. Phenoxy resin has a long molecular chain and is similar in structure to epoxy resin, and acts as a flexible material in a composition with high machine density and provides high toughness, so it has a high strength but a tough composition. can get. In the circuit connecting material according to the present invention, the adhesive to be used contains a phenoxy resin, an alkylene oxide-modified epoxy resin, MBS fine particles, and a latent curing agent, and the type and boiling point of the solvent are specified and dried below the activation temperature of the latent curing agent. Therefore, there is no deterioration of the curing agent, and stable storage stability is obtained.

Hereinafter, the present invention will be described in detail based on examples. In addition, each compounding ratio was shown in Table 1.
Example 1
50 g of phenoxy resin (manufactured by Toto Kasei Co., Ltd., trade name YP-70, weight average molecular weight 55000) in weight ratio with toluene (boiling point 110.6 ° C., SP value 8.90) / ethyl acetate (boiling point 77.1 ° C., It was dissolved in a mixed solvent of SP value 9.10) = 50/50 to obtain a solution having a solid content of 40% by weight. 50 g of an alkylene oxide-modified epoxy resin (propylene oxide-modified bisphenol A type epoxy resin, manufactured by ADEKA Corporation, trade name EP-4010S, epoxy equivalent 350, total chlorine 0.05%)) was used as a stock solution. 20 g of MBS (manufactured by Mitsubishi Rayon Co., Ltd., trade name: METABLEN C132, primary particle size: about 300 nm) was ultrasonically dispersed in ethyl acetate to obtain a 15% by weight dispersion. SI-60LA (trade name of Sanshin Chemical Industry Co., Ltd.) was used as the latent curing agent. A nickel layer having a thickness of 0.2 μm is provided on the surface of particles having polystyrene as a core, a gold layer having a thickness of 0.02 μm is provided outside the nickel layer, and conductive particles having an average particle diameter of 3 μm and a specific gravity of 2.0. Was made. An adhesive composition was prepared by blending 100 parts by weight of a resin component, 20 parts by weight of MBS fine particles, and 5 parts by weight of a latent curing agent in a solid weight ratio. Furthermore, with respect to 100 parts by volume of the adhesive composition, 3 parts by volume of conductive particles were mixed and dispersed, and this was further applied to a PET resin film having a thickness of 50 μm using a coating apparatus, at 60 ° C. for 3 minutes. A circuit connecting material having an adhesive layer thickness of 20 μm was obtained by hot air drying.

Examples 2-3
The solid weight ratio of the phenoxy resin / propylene oxide modified epoxy resin was changed to 50 g / 50 g, but 40 g / 60 g (Example 2) and 60 g / 40 g (Example 3) were used. A circuit connection material was obtained.

Example 4
A circuit connection material was obtained in the same manner as in Example 1 except that the weight of the MBS fine particles was 30 g.

Example 5
The amount of the propylene oxide-modified epoxy resin is 40 g, and 10 g of bisphenol type epoxy resin (bisphenol A type epoxy resin, Yuka Shell Epoxy Co., Ltd., trade name Epicoat 828, epoxy equivalent 184) is added. A circuit connection material was obtained in the same manner as in Example 1.

Example 6
A circuit connection material was obtained in the same manner as in Example 1 except that the blending amount of the conductive particles was 7 parts by volume.

Example 7
A circuit connection material was obtained in the same manner as in Example 1 except that the particle size of the conductive particles was 5 μm.

Example 8
A circuit connection material was obtained in the same manner as in Example 1 except that the conductive particles were replaced with nickel particles having an average particle diameter of 2 μm and an aggregate particle diameter of 10 μm.

Comparative Example 1
A circuit connecting material was obtained in the same manner as in Example 1 except that a bisphenol type epoxy resin (Epicoat 828) was used instead of the propylene oxide-modified epoxy resin.

(Circuit connection)
Using the circuit connection material described above, flexible circuit boards (FPC) having 500 copper circuits having a line width of 50 μm, a pitch of 100 μm, and a thickness of 8 μm were heated and pressurized at 180 ° C. and 3 MPa for 5 seconds to connect over a width of 2 mm. . At this time, after adhering the adhesive surface of the circuit connecting material on the FPC in advance, the pressure connection was performed by heating and pressing at 70 ° C. and 0.5 MPa for 2 seconds, and then the PET resin film was peeled off. Connected to one FPC. Further, the above FPC and glass (surface resistance 20Ω / □) on which a thin layer of indium oxide (ITO) was formed were heated and pressurized at 180 ° C. and 3 MPa for 5 seconds to be connected over a width of 1.5 mm. At this time, temporary connection was made to ITO glass in the same manner as described above.

(Measurement of connection resistance)
After the circuit connection, the resistance value between adjacent circuits of the FPC including the connection portion was measured with a multimeter. The resistance value is shown as an average of 150 resistances of adjacent circuits. These results are shown in Table 1. The circuit connection material obtained in Example 1 showed good connectivity. The circuit connection materials of Examples 2 to 8 also show good connection resistance.

(Measurement of adhesive strength)
After the circuit connection, the FPC including the connection part was cut out to a width of 1 cm, and measurement was performed by a 90-degree peel method using a tencil meter. These results are shown in Table 1. The circuit connection material obtained in Example 1 showed good connectivity. The circuit connection materials of Examples 2 to 8 also show good connection resistance. On the other hand, Comparative Example 1 using a bisphenol-type epoxy resin instead of the propylene oxide-modified epoxy resin in Example 4 cannot obtain the effect of improving the adhesive force because the stress relaxation of the cured product is insufficient.

  According to the present invention, it was possible to provide a circuit connection material suitable as an electrical / electronic adhesive that requires short-time curing characteristics.

Claims (7)

  In the circuit connecting material having the adhesive composition and conductive particles as components, the adhesive composition comprises a phenoxy resin, an alkylene oxide-modified bisphenol A type epoxy resin, core / shell type MBS (methacrylic / butadiene / styrene) fine particles, A circuit connection material containing an epoxy latent hardener.   The circuit connecting material according to claim 1, wherein the weight average molecular weight (Mw) of the phenoxy resin is 10,000 or more.   The circuit connecting material according to claim 1 or 2, wherein the alkylene oxide-modified bisphenol A type epoxy resin is a propylene oxide modified bisphenol A type epoxy resin.   The circuit connection material according to any one of claims 1 to 3, wherein the primary particle size of the core-shell type MBS fine particles is 100 to 300 nm.   The circuit connection material according to claim 1, wherein the conductive particles have an average particle size of 2 to 18 μm.   The circuit connection material according to any one of claims 1 to 5, wherein the content of the conductive particles is 0.1 to 30 parts by volume with respect to 100 parts by volume of the adhesive composition.   The circuit connection material according to claim 1, wherein the shape is a film shape.