JP2005068299A - High permittivity epoxy resin paste and electronic part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high permittivity epoxy resin paste which has a dielectric constant of at least 15 after cured, is excellent in electric characteristics such as a dielectric dissipation factor or the like, and exhibits mechanical characteristics such as peel strength of at least 5 N/cm, and to provide an electronic part or the like which is manufactured by a relatively simple method using the high permittivity epoxy resin paste, reduced in its size, and used within a high frequency range (around 10 GHz). <P>SOLUTION: The high permittivity epoxy resin paste comprises 25-65 vol% of a mixture, composed of 65-95 vol% of an epoxy resin (including a curing agent and a curing accelerator) with 5-35 vol% of a butadiene-acrylonitrile copolymer, and 35-75 vol% of a high permittivity powder, and has a dielectric constant of at least 15 and peel strength of at least 5 N/cm after cure. In particular, the butadiene-acrylonitrile copolymer is modified with a carboxy group. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a high-dielectric-constant epoxy resin paste and an electronic component using the same.

In recent years, electronic devices for communication, consumer use, industrial use, etc. have more electrical characteristics such as heat resistance, dimensional stability, high dielectric constant, and dielectric loss tangent in terms of materials due to downsizing and higher density of mounting methods. It is requested. Also, as high-frequency electronic components, sintered ferrite and sintered ceramics are used for merits such as downsizing. However, in this case, there are problems such as a complicated manufacturing process. It is desired. For example, a substrate having a high dielectric constant is required from the formation of a composite circuit in which a printed wiring board has a capacitor effect. However, since polyimide, epoxy resin, etc., which are materials used for printed wiring boards, have a dielectric constant (ε) of about 3 to 4 at most, an attempt to make this a dielectric constant of several tens or more increases the resin material. It is necessary to add a large amount of dielectric ceramic powder or the like. As a specific substrate, a prepreg obtained by adding ceramic powder with high dielectric constant to phenol resin, epoxy resin, fluororesin or polyphenylene ether resin, impregnating and drying glass cloth or glass nonwoven fabric is laminated and molded. It is known that the substrate has a high dielectric constant. However, in order to obtain a high dielectric constant substrate by such a method, it is necessary to add a large amount to the resin, for example, 50% by volume fraction of the resin. This is 500 to 1000 parts by weight in terms of 100 parts by weight of the resin. When such a large amount of high dielectric constant powder is added to the resin, a problem arises in the mechanical characteristics and electrical characteristics of the obtained substrate. That is, there are problems of mechanical properties such as tensile strength and electrical properties such as dielectric loss tangent. With regard to such a technique, Patent Document 1 is known, but even in this case, there is still no sufficient dielectric constant and excellent electrical characteristics such as mechanical characteristics and dielectric loss tangent have not been obtained. However, it is the current situation.
JP-A-8-69712

  Therefore, the problem to be solved by the present invention is a high dielectric constant having a dielectric constant of 15 or more after curing the paste, excellent electrical characteristics such as dielectric loss tangent, and mechanical properties having a peel strength of 5 N / cm or more. Providing a low-priced epoxy resin paste, and further providing a miniaturized electronic component, etc., used in the high-frequency region (about 10 GHz) manufactured by a relatively simple method using the high-dielectric constant epoxy resin paste It is in.

  The problem to be solved is, as described in claim 1, 25 to 65 vol% of a mixture of 65 to 95 vol% of an epoxy resin (including a curing agent and a curing accelerator) and 5 to 35 vol% of a butadiene acrylonitrile copolymer. And a high dielectric constant powder of 35 to 75 vol%, and a high dielectric constant epoxy resin paste having a dielectric constant after curing of the paste of 15 or more and a peel strength of 5 N / cm or more is solved. In particular, as described in claim 2, the butadiene acrylonitrile copolymer is solved by forming a high dielectric constant epoxy resin paste modified with a carboxyl group.

  Further, as described in claim 3, the high dielectric constant powder is solved by using a high dielectric constant epoxy resin paste which is a barium titanate powder. According to a fourth aspect of the present invention, the barium titanate powder is solved by using a high dielectric constant epoxy resin paste containing at least one of calcium, tin, zirconium, strontium, and niobium.

  Further, as described in claim 5, the dielectric constant after curing of the paste produced using the high dielectric constant epoxy resin paste according to any one of claims 1 to 4 is 15 or more, and the peel strength is 5N. It can be solved by using an electronic component of / cm or more.

  By using the high dielectric constant epoxy resin paste as described above, a high dielectric paste having high dielectric constant, excellent electrical characteristics such as dielectric loss tangent, and no deterioration in mechanical characteristics such as tensile strength can be obtained. can get. In addition, by using such a high dielectric constant epoxy resin paste, it is possible to obtain various miniaturized electronic components and the like that are used in the high frequency region (about 10 GHz) relatively easily.

  More specifically, it consists of 65 to 95 vol% of an epoxy resin (including a curing agent and a curing accelerator), 25 to 65 vol% of a butadiene acrylonitrile copolymer of 5 to 35 vol%, and high dielectric constant powder of 35 to 75 vol%. By using a high dielectric constant epoxy resin paste, and particularly when the butadiene acrylonitrile copolymer is a high dielectric constant epoxy resin paste modified with a carboxyl group, the dielectric constant after the paste is cured is 15 or more. A high dielectric constant epoxy resin paste having a mechanical property of having a dielectric loss tangent of 1.0% or less and a peel strength of 5 N / cm or more can be obtained.

  Further, the high dielectric constant powder is a barium titanate powder, and the barium titanate powder is a high dielectric constant epoxy resin paste containing at least one of calcium, tin, zirconium, strontium, and niobium. In addition to the above-described characteristics, a practical high dielectric constant epoxy resin paste can be obtained in which the Curie temperature of barium titanate is around room temperature.

  And, by using the high dielectric constant epoxy resin paste, the dielectric constant after curing the paste is 15 or more, the dielectric loss tangent is 1.0% or less, and the electrical characteristics are excellent, and the peel strength is high. Various miniaturized electronic components having a mechanical strength of 5 N / cm or more and sufficiently usable in a high-frequency region (about 10 GHz) can be obtained relatively easily.

  The present invention is described in detail below. The invention described in claim 1 includes an epoxy resin (including a curing agent and a curing accelerator) 65 to 95 vol% and a butadiene acrylonitrile copolymer 5 to 35 vol%, a mixture 25 to 65 vol%, and a high dielectric constant powder 35 to 35 vol%. By using an epoxy resin paste having a high dielectric constant of 75 vol%, the dielectric constant after curing the dielectric paste becomes 15 or more, and the dielectric loss tangent is excellent at 1.0% or less, and the tensile strength is as high as possible. Can be made a high dielectric paste having a mechanical strength of 5 N / cm or more as a peel strength. This is because the addition of the butadiene acrylonitrile copolymer (NBR) makes it possible to fill the high dielectric constant powder at a high level, and the addition of a small amount of the high dielectric constant powder is the same as in the conventional case. Therefore, electrical properties such as dielectric loss tangent are not deteriorated, and mechanical properties such as tensile strength are improved by the addition of NBR. It becomes sufficiently practical ones of cm or more.

  First, the epoxy resin used as the base resin will be described. The epoxy resin used in the present invention is not particularly limited, and bisphenol type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, polyfunctional glycidylamine resin, etc. Can be used. Of these, bisphenol-type epoxy resins are preferred. Further, when these epoxy resins having a number average molecular weight of about 100 to 1000 are used, it is possible to suppress an increase in viscosity of the obtained high dielectric paste, and to improve the coatability when forming electronic parts and the like. be able to. Furthermore, it is preferable because it has characteristics such as low dielectric loss and low crystallinity. The epoxy resin is usually supplied in a liquid state. In this case, the high dielectric constant powder can be directly added, mixed, and homogenized to obtain a high dielectric paste. When the epoxy resin is solid or has a high viscosity, it may be dissolved or diluted in an appropriate organic solvent such as toluene, xylene, methyl ethyl ketone, or the like. Such dilution with an organic solvent is preferable because it also serves to adjust the viscosity of the resulting high dielectric paste.

  Further, the curing agent used in combination with the epoxy resin is not particularly limited, and various known curing agents for the epoxy resin, such as acid anhydride-based curing agents (for example, hexahydrophthalic anhydride) and amine-based curing agents. A curing agent or the like can be used, and the amount of the curing agent can be appropriately adjusted according to the type of epoxy resin and curing agent used. Further, it is preferable to use a curing accelerator in combination. The combined use of this curing accelerator has the effect of shortening the curing time after applying the high dielectric paste and lowering the curing temperature. Moreover, about the usage-amount, it is set as a suitable quantity according to the kind of epoxy resin and hardening | curing agent.

  The butadiene acrylonitrile copolymer (NBR), which is the other base resin, will be described because the copolymer exhibits rubber elasticity from its structure and is soluble in solvents such as toluene and methyl ethyl ketone (MEK). For example, they are used as adhesives for flexible wiring boards, packings requiring high strength, oil seals, O-rings, belts, and the like. Specifically, the product name “Nipol” from ZEON Corporation, the product name “HIKER” from BF Goodrich Chemical Co., and “PHR-1H” manufactured by Nippon Synthetic Rubber Co., Ltd. are known. In the present invention, as described in claim 2, the terminal is preferably modified with a carboxyl group. Thus, when it has a carboxyl group, since adhesiveness with metals, such as copper, improves, peel strength improves and there exists an effect which improves mechanical characteristics, such as tensile strength. In addition, since the high dielectric constant powder can be highly filled, an epoxy resin paste having a high dielectric constant can be obtained. Such a material may be selected from the above-mentioned commercially available products. For example, Nipol 1072J or Nipol 1072 manufactured by Nippon Zeon Co., Ltd., Hiker manufactured by BF Goodrich Chemical Co., PHR-1H manufactured by Nippon Synthetic Rubber Co., etc. can be used.

  And the said base resin is mixed so that it may consist of 65-95 vol% of epoxy resins (a hardening | curing agent and a hardening accelerator are included) and 5-35 vol% of butadiene acrylonitrile copolymers. This is because when the epoxy resin (including the curing agent and the curing accelerator) exceeds 95 vol%, the resin paste obtained due to insufficient flexibility becomes hard and the adhesiveness also decreases. If it is less than 65 vol%, the heat resistance is lowered and the dielectric constant is also lowered. Further, when the butadiene acrylonitrile copolymer (NBR) is less than 5 vol%, the resin paste obtained due to insufficient flexibility becomes hard and the adhesiveness becomes low. On the other hand, if it exceeds 35 vol%, the heat resistance is lowered and the dielectric constant is also lowered.

  Next, the high dielectric constant powder will be described. The high dielectric constant powder is preferably a ceramic powder, and has a higher relative dielectric constant and Q value (reciprocal of dielectric loss tangent) than the base resin serving as a dispersion medium in the high frequency band. It is preferable to have two or more types. The ratio in that case may be arbitrarily selected. In the present invention, it is preferable that the Q value is about 10 to 30000 and the dielectric loss tangent is 0.05 or less. The average particle size is about 0.01 to 100 μm, preferably about 0.01 to 10 μm. By setting it as such an average particle diameter, dispersibility improves and it becomes easy to obtain a high dielectric constant. On the other hand, if the particle size is smaller than the above, the specific surface area becomes large and it is difficult to achieve a high filling rate, and if the particle size is larger than the above range, it will settle when pasted. It is difficult to disperse uniformly. In addition, the shape thereof may be irregular particles, spherical shape, elliptical shape, flat shape, whisker shape or the like. In particular, an aspect ratio of 1.5 to 10 is preferable.

Specific high dielectric constant powder, the epoxy resin paste when not required so high dielectric constant, _Mg 2 _SiO 4 of dielectric constant of about _{10~1000, Al 2 O 3, MgTiO} 3, ZnTiO 3 Zn ₂ TiO ₄ , TiO ₂ , CaTiO ₃ , SrTiO ₃ , SrZrO ₃ , BaTi ₂ O ₅ , BaTi ₄ O ₉ , Ba ₂ Ti ₉ O ₂₀ , Ba ₂ (Ti, Sn) ₉ O ₂₀ , (ZrTiO ₄ , Zr, Sr) TiO ₄ , BaNd ₂ Ti ₅ O ₁₄ , BaSm ₂ TiO ₁₄ , Bi ₂ O ₃ BaONd ₂ O ₃ TiO ₂ , PbOBaONd ₂ O ₃ TiO ₂ , (Bi ₂ O ₃ , PbO) BaONd ₂ O _{3 2, La 2 Ti 2 O 7} , Nd 2 Ti 2 O 7, (Li, Sm) TiO 3, Ba ( _{g 1/3 Ta 2/3) O 3,} Ba (Zn 1/3 Ta 2/3) O 3, Ba (Zn 1/3 Nd 2/3) O 3, Sr (Zn 1/3 Nd 2/3 ) O ₃ or the like is used. Among these, TiO ₂ , CaTiO ₃ , SrTiO ₃ , BaONd ₂ O ₃ —TiO ₂ , Bi ₂ O ₃ —BaO—Nd ₂ O ₃ —TiO, BaTi ₄ O ₉ , Ba ₂ Ti ₉ O ₂₀ , Ba _{2 (Ti, Sn) O 20,} MgO-TiO 2, ZnO-TiO 2, MgO-SiO 2, Al 2 O 3 or the like, is preferred.

For epoxy resin pastes that require a relatively high dielectric constant, BaTiO ₃ , (Ba, Pb) TiO ₃ , Ba (Ti, Zr) O ₃ , (Ba, Sr) having a dielectric constant of 1000 or more. ) TiO ₃ , Ba (Ca, Sn) TiO ₃ , etc. may be used. In particular, the barium titanate powder (BaTiO ₃ ) described in claim ₃ and, as described in claim 4, calcium (Ca), tin (Sn), zirconium (Zr), strontium (Sr), niobium ( Since the barium titanate powder containing at least one of Nb) is easy to obtain a dielectric paste having a high dielectric constant, and the Curie temperature of the barium titanate powder can be around room temperature, a high dielectric constant epoxy It becomes practical as a resin paste. Further, the barium titanate powder is preferable because it can reduce the distortion of crystallites and increase the dielectric constant by heat treatment. Usually, it is carried out at 1200-1400 ° C. for about 10 minutes to 10 hours. The high dielectric constant powder described above may be single crystal or polycrystalline.

  Moreover, the addition amount of the said high dielectric constant powder shall be 35-75 vol% with respect to the said mixture 25-65 vol% which is base resin. This is because when the amount of the high dielectric constant powder is less than 35 vol%, the intended dielectric constant of 15 or more cannot be obtained, and when the high dielectric constant powder exceeds 75 vol%, the viscosity Becomes too high, a dense high-dielectric-constant epoxy resin paste cannot be obtained, and the coatability deteriorates. Further, the strength of the obtained dielectric thin film is also reduced, and the Q value is also greatly reduced. More preferably, the high dielectric constant powder is set in the range of 40 to 60 vol% because the dielectric constant is high, the dielectric loss tangent is good, and the peel strength is high. When the peel strength is 5 N / cm or more, the mechanical properties as a thin film capacitor or the like are sufficiently satisfied.

  The high dielectric constant epoxy resin paste is produced by stirring and kneading with a ball mill, three rolls or other equipment. In order to facilitate kneading and processing, a viscosity adjusting solvent may be added. This viscosity is normally about 100 to 100,000 cPs. By adjusting the viscosity in this way, the coating property can be improved in the production of a thin film or the like using the high dielectric paste. In addition, what is necessary is just to select a preferable thing as a solvent according to the polymer to be used, Specifically, toluene, acetone, methyl ethyl ketone (MEK), etc. are used. The high dielectric constant epoxy resin paste thus obtained can be applied and dried by screen printing, ink jet, roll coater, spin coating or the like to form a necessary thin film. As described above, the peel strength has a mechanical strength of 5 N / cm or more, the dielectric constant (ε) after curing is 15 or more, and the dielectric loss tangent (tan δ) is 1.0% or less. Thus, a small electronic component that can be used sufficiently can be manufactured relatively easily. Specifically, a thin film capacitor, a low-pass filter, a high-frequency circuit board, and the like can be given.

  Using the various samples described in Table 1, the effect of the present invention was confirmed. The sample was bisphenol A type epoxy resin (YD-8125, manufactured by Toto Kasei Co., Ltd.) as an epoxy resin, and 52 wt% of 3 or 4-methylhexahydrophthalic anhydride (HN-5500, manufactured by Hitachi Chemical Co., Ltd.) as a curing agent %, 2,4,6-tris (dimethylaminomethyl) phenol (Japan Epoxy Resin, Epicure 3010) 1 wt% as a curing accelerator, and carboxyl group-modified butadiene acrylonitrile copolymer (Nippon Zeon, Nippon) 1072) and a barium titanate powder containing calcium and tin (FUJI Titanium, BT-206, ε = 18000) are added. In order to adjust the viscosity, a necessary amount of toluene was added.

The production of the sample in more detail was described. After adding the various resins excluding the internal curing accelerator, barium titanate and toluene, the mixture was kneaded for 24 hours in a ball mill to adjust the viscosity to 1000 to 2000 cPs. The curing accelerator was added to this to make a paste. This dielectric paste was applied onto a copper foil using a bar coater and dried (150 ° C. × 30 minutes) to form a thin film having a thickness of 25 μm. Next, after curing at 170 ° C. for 40 minutes, the capacitance (C) was measured with an LCZ meter, and the dielectric constant (ε) and dielectric loss tangent (tan δ) were determined. Further, the dielectric paste is similarly formed into a thin film on a 25 μm thick polyimide film with an adhesive on one side, and then a copper foil with a thickness of 5 μm is applied to the adhesive side at a pressure of 50 kg / cm ^2. Then, a press treatment was performed at 160 ° C. for 1 hour to form a sample, and the peel strength of the thin film at this time was measured at 180 °. Note that the peel strength was measured with the aid of JIS standard C6471 “copper peel strength”. The results are listed in Table 1.

  As is apparent from Table 1, the high dielectric constant epoxy resin paste of the present invention has a high dielectric constant after curing of the paste, an excellent dielectric loss tangent, and a high peel strength. On the other hand, as a comparative example, any one of the dielectric constant, the dielectric loss tangent, and the peel strength deviates from the target value of the present invention. More specifically, as described in Examples 1 to 6, a mixture of an epoxy resin (including a curing agent and a curing accelerator) and a butadiene acrylonitrile copolymer of 65 to 95: 5 to 35 vol% is 25 to 25%. In the range of 65 vol% and high dielectric constant powder of 35 to 75 vol%, the dielectric constant (ε) is 15 or more, the dielectric loss tangent (tan δ) is 1.0% or less, and the peel strength is 5 N / cm or more. Understand. On the other hand, even if the ratio of the epoxy resin and the NBR shown in Comparative Examples 1 and 2 is within the range of the present invention, if the ratio of the base resin and the barium titanate powder is out of the range of the present invention, the dielectric constant is This is not preferable because it is less than 15, the peel strength is less than 5 N / cm, and the dielectric loss tangent exceeds 1.0%. In addition, as described in Comparative Examples 3 and 4, when the ratio between the epoxy resin and NBR is out of the scope of the present invention, the dielectric constant is less than 15 and the peel strength is less than 5 N / cm. It can be seen that the tangent exceeds 1.0% and is not preferable.

By using the above-mentioned epoxy resin paste with a high dielectric constant, it can be used in a high frequency region (about 10 GHz), has high dielectric constant, excellent electrical characteristics such as dielectric loss tangent, and excellent mechanical characteristics with high peel strength. It is also useful as various small electronic components.

Claims (5)

  It consists of 25 to 65 vol% of a mixture of epoxy resin (including a curing agent and a curing accelerator) 65 to 95 vol% and butadiene acrylonitrile copolymer 5 to 35 vol%, and high dielectric constant powder 35 to 75 vol%. A high dielectric constant epoxy resin paste having a dielectric constant of 15 or more and a peel strength of 5 N / cm or more.   2. The high dielectric constant epoxy resin paste according to claim 1, wherein the butadiene acrylonitrile copolymer is modified with a carboxyl group.   3. The high dielectric constant epoxy resin paste according to claim 1, wherein the high dielectric constant powder is a barium titanate powder.   The high dielectric constant epoxy resin paste according to claim 3, wherein the barium titanate powder contains at least one of calcium, tin, zirconium, strontium, and niobium. An electronic component using the high dielectric constant epoxy resin paste according to any one of claims 1 to 4, having a dielectric constant after curing of the paste of 15 or more and a peel strength of 5 N / cm or more.