JP2006063315A - Prepreg, method for producing the same, laminated sheet and printed circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a prepreg, a laminated sheet and a printed circuit board prepared by using an epoxy resin composition having excellent dispersibility of varnish and high thermal conductivity at the same time. <P>SOLUTION: The prepreg is produced by impregnating an epoxy resin composition containing an epoxy resin and a curing agent in a fibrous sheet substrate and semicuring the composition. The epoxy resin is an epoxy resin compound having a molecular structure expressed by formula (1) [R is an alkyl (a ≤4C aliphatic hydrocarbon group), acetyl or a halogen; and n is 0-5 on an average] and contains an inorganic filler having a thermal conductivity of ≥20 W/m×K in an amount of 10-900 pts. vol. based on 100 pts. vol. of the solid component of the resin. The laminated sheet and the printed circuit board are produced by using the prepreg. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a prepreg to which a composition in which an epoxy resin having a high thermal conductivity and an inorganic filler having a high thermal conductivity are mixed, a manufacturing method thereof, and a laminated board or a printed wiring board using the prepreg.

An epoxy resin composition using an epoxy resin having a mesogenic structure is excellent in mechanical and thermal properties.
For example, Patent Document 1 discloses an epoxy resin composition containing a biphenol type epoxy resin and a polyhydric phenol resin curing agent as essential components. This epoxy resin composition can provide a cured product excellent in stability and strength at high temperatures, and can be used in a wide range of fields such as adhesion, casting, sealing, molding and lamination.
Further, Patent Document 2 discloses an epoxy resin monomer having in its molecule two mesogen structures connected by a bent chain. Epoxy resins made from this monomer are known to have a smectic structure.
Furthermore, Patent Document 3 discloses a resin composition containing an epoxy resin monomer having a mesogenic group. This epoxy resin is preferable as a resin for laminates that are excellent in thermal conductivity and require heat dissipation.

  However, an epoxy resin having such a mesogenic structure has a high melting point and is extremely insoluble in an organic solvent. Therefore, when preparing a varnish using such an epoxy resin, more organic solvent must be used, and the viscosity of the varnish decreases. Therefore, in the production of the prepreg, there is a problem that when the sheet-like fiber base material is impregnated and held in such a manner, the amount of the adhered resin cannot be increased. When a thickening third component is added to the varnish to compensate for the drawback, the self-alignment of the resin is disturbed, resulting in a problem that the thermal conductivity of the cured product is lowered.

Japanese Patent Application Laid-Open No. 07-090052 JP 09-118673 A JP-A-11-323162

  The problem to be solved by the present invention is to provide a prepreg using a composition in which an epoxy resin having a high thermal conductivity and an inorganic filler having a high thermal conductivity are mixed, and a laminate or a printed wiring board using the prepreg. And increasing the thermal conductivity of the cured epoxy resin.

The gist of the present invention for achieving the above-mentioned problems is as follows.
In the prepreg in which an epoxy resin composition containing an epoxy resin and a curing agent is held on a sheet-like fiber base material to be in a semi-cured state, the epoxy resin is an epoxy compound having a molecular structure represented by (formula 1), and heat An inorganic filler having a conductivity of 20 W / m · K or more is contained in the epoxy resin so as to be 10 to 900 parts by volume with respect to 100 parts by volume of the resin solid content. The said resin solid content means what combined the epoxy resin component and its hardening | curing agent component.

The prepreg is produced in a semi-cured state by holding an epoxy resin composition containing an epoxy resin, a curing agent, and an inorganic filler having a thermal conductivity of 20 W / m · K or more on a sheet-like fiber base material. When the epoxy resin composition in which the inorganic filler is blended in an amount of more than 100 parts by volume with respect to 100 parts by volume of the resin solid is held on a sheet-like fiber base material, the epoxy resin composition is mixed with a ball mill, a bead mill, a plurality of It is characterized by being kneaded by a kneading means selected from a roll mill composed of rolls of the above, or equivalent means to the kneading means and held on a sheet-like fiber base material to be in a semi-cured state.
The ball mill is a device for kneading and mixing raw materials by putting hard balls such as ceramic and metal and raw materials into a container and rotating them. The bead mill is an apparatus for kneading and mixing using fine beads (diameter of 1 mm or 0.1 mm) instead of the balls. The roll mill is, for example, a three-roll machine, and is an apparatus that introduces raw materials between rolls and kneads and mixes them with shear force between the rolls.

  The laminate according to the present invention is obtained by heat-pressing the above-described prepreg as the whole or a part of the prepreg layer that is integrally laminated. Moreover, the printed wiring board according to the present invention includes an insulating layer formed by heating and pressing the above-described prepreg layer.

In the present invention, an inorganic filler having a thermal conductivity of 20 W / m · K or more is contained in the epoxy resin so as to be 10 to 900 parts by volume with respect to 100 parts by volume of the resin solid content, thereby facilitating the handling. A prepreg is constituted by applying an epoxy resin composition.
In this invention, it is essential that the addition amount of the inorganic filler with respect to an epoxy resin is 10-900 volume parts with respect to 100 volume parts of epoxy resin solid content. If the amount is less than 10 parts by volume, the inorganic filler settles and the inorganic filler content in the resin composition cannot be made constant, so that a prepreg having a uniform appearance cannot be produced. Moreover, since the viscosity of a resin composition varnish will increase too much when it exceeds 900 volume part, it becomes impossible to use for manufacture of a prepreg. If the addition amount of the inorganic filler is up to 100 parts by volume, the resin composition varnish can be uniformly stirred by a normal stirring means using stirring blades. However, when the amount of the inorganic filler added is more than 100 parts by volume, a large shear force is applied by a kneading means selected from a ball mill, a bead mill, a roll mill composed of a plurality of rolls, or an equivalent means. By kneading the resin composition, uniform stirring becomes possible. Moreover, if the heat conductivity of an inorganic filler is less than 20 W / m * K, the heat conductivity of a laminated board will not improve.
The epoxy resin composition applied to the present invention improves the viscosity of the varnish by adding an inorganic filler, compared to an epoxy resin composition in which a curing agent is added to an epoxy resin having a normal mesogenic structure, and the varnish is Since it is uniformly dispersed, handling becomes easy. For this reason, it is suitable as a material for lamination. Since the inorganic filler is not reactive with the resin component, it does not disturb the self-alignment of the resin effective for heat conduction, and does not cause a decrease in the thermal conductivity of the cured resin.

  The cured product obtained by heating and pressing the above prepreg has high thermal conductivity and contributes to providing a laminated board or printed wiring board having good thermal conductivity.

  In the present invention, it is important to use an inorganic filler having a high thermal conductivity. Epoxy compounds are general epoxy compounds having a biphenyl skeleton or a biphenyl derivative skeleton and having two or more epoxy groups in one molecule. The epoxy compound is preferably selected from those having the molecular structure represented by (Formula 2). Since the biphenyl group is more easily arranged, the thermal conductivity can be further increased. Further, two or more biphenyl skeletons or biphenyl derivative skeletons may be present in the same molecule.

  In the present invention, the inorganic filler has a thermal conductivity of 20 W / m · K or more, and is added in an amount of 10 to 900 parts by volume with respect to 100 parts by volume of the resin solid content. As long as the inorganic filler has a thermal conductivity of 20 W / m · K or more, it can contain a metal oxide, hydroxide, inorganic ceramics, or other filler. For example, inorganic powder fillers such as boron nitride, aluminum nitride, silicon nitride, silicon carbide, titanium nitride, zinc oxide, tungsten carbide, alumina, magnesium oxide, fibrous fillers such as synthetic fibers and ceramic fibers, colorants, etc. Yes, the thermal conductivity of the laminate is improved by using these together with the epoxy compound. A thermal conductivity of the inorganic filler of 30 W / m · K or more is preferable because the thermal conductivity of the laminated plate is further improved.

  Further, the shape of the filler may be any of powder (bulk shape, spherical shape), single fiber, long fiber, etc. In particular, in the case of a flat plate shape, the cured product is cured by the lamination effect of the inorganic filler itself. The thermal conductivity is further increased, which is preferable because the heat dissipation of the laminated board to which the thermal conductivity is applied is further improved. Two or more of these inorganic fillers may be used in combination.

  As the inorganic filler content of the epoxy resin composition is increased, the viscosity of the epoxy resin composition varnish increases due to its thixotropy and cohesiveness. For this reason, in an agitator using a stirring blade, if an inorganic filler exceeding 100 parts by volume is added to 100 parts by volume of the resin solid content, stirring becomes difficult and uniform dispersion of the resin composition becomes difficult. Therefore, the dispersibility of the resin composition is improved by kneading by a kneading means selected from a ball mill, a bead mill, a roll mill composed of a plurality of rolls, or a means equivalent to the kneading means, which generates a strong shear force. Viscosity also decreases. Thereby, it becomes possible to mix | blend an inorganic filler to 900 volume part. In addition, there is no problem in applying such a dispersion method to a resin composition having 100 parts by volume or less of an inorganic filler.

  As the curing agent to be blended with the epoxy resin, a curing agent conventionally used for advancing the curing reaction of the epoxy resin monomer can be used. Examples thereof include phenols or compounds thereof, amine compounds and derivatives thereof, acid anhydrides, imidazoles and derivatives thereof, and the like. Moreover, the hardening accelerator conventionally used in order to advance the polycondensation reaction with an epoxy resin monomer, phenols or its compound, amines, or its compound can be used for a hardening accelerator. Examples thereof include triphenylphosphine, imidazole and derivatives thereof, tertiary amine compounds and derivatives thereof.

  The epoxy resin composition containing an epoxy resin, a curing agent, an inorganic filler, and a curing accelerator may contain a flame retardant, a diluent, a plasticizer, a coupling agent, and the like as necessary. Moreover, when impregnating this epoxy resin composition in a sheet-like fiber base material and drying and manufacturing a prepreg, a solvent can be used as needed. These uses do not affect the thermal conductivity of the cured product.

  The prepreg according to the present invention is obtained by impregnating the above epoxy resin composition into a sheet-like fiber base material (woven fabric or non-woven fabric) made of glass fiber or organic fiber, followed by drying by heating, so that the epoxy resin is in a semi-cured state. It is a thing. The laminate is formed by heating and pressing the prepreg as a whole layer or a part of the prepreg layer, and copper foil or the like on one side or both sides by the heating and pressing as necessary. Bond metal foils together. Furthermore, the printed wiring board is provided with an insulating layer formed by heating and press-molding the prepreg layer, and has a single-sided printed wiring board, a double-sided printed wiring board, and further, a printed wiring on the inner layer and the surface layer. It is a multilayer printed wiring board.

  The printed wiring board having the above-described configuration has good heat conductivity of the insulating layer and excellent heat dissipation. It is suitable for printed wiring boards for automobile equipment and high-density mounting printed wiring boards such as personal computers.

  Examples of the present invention will be described below, and the present invention will be described in detail. In the following examples and comparative examples, “part” means “part by mass”. Moreover, this invention is not limited to a present Example, unless it deviates from the summary.

Example 1
As an epoxy resin monomer component, prepare 100 parts of an epoxy resin monomer having a biphenyl skeleton (Japan Epoxy Resin “YL6121H”, epoxy equivalent 175), and dissolve it at 100 ° C. in 100 parts of methyl isobutyl ketone (Wako Pure Chemical Industries, Ltd.). , Returned to room temperature.
As a curing agent, 22 parts of 1,5-diaminonaphthalene (“1,5-DAN” manufactured by Wako Pure Chemical Industries, Ltd., amine equivalent 40) is prepared and dissolved in 100 parts of methyl isobutyl ketone (manufactured by Wako Pure Chemical Industries) at 100 ° C. And returned to room temperature.
“YL6121H” is an epoxy resin monomer in which R = —CH ₃ and n = 0.1 in the molecular structural formula (formula 1) described above and n = 0.1 in the molecular structural formula (formula 2). This is an epoxy resin monomer containing an equimolar amount of the epoxy resin monomer.
The epoxy resin monomer solution and the curing agent solution are mixed and stirred with a stirring blade type homomixer to form a uniform varnish, and boron nitride (“GP” manufactured by Denki Kagaku Kogyo, average particle size: 8 μm, as an inorganic filler) Heat conductivity 60W / m · K, particle shape: flat plate) 107 parts (50 parts by volume with respect to 100 parts by volume of resin solids) and 67 parts of methyl isobutyl ketone (Wako Pure Chemical Industries) were added and mixed and stirred. An epoxy resin varnish was prepared.
The epoxy resin composition varnish was impregnated into a 0.2 mm thick glass fiber woven fabric and dried by heating to obtain a prepreg. Four prepregs and copper foils were stacked on both sides thereof and integrated by heating and pressurizing for 90 minutes under conditions of a temperature of 175 ° C. and a pressure of 4 MPa to obtain a laminate having a thickness of 0.8 mm.

The results of measuring the thermal conductivity of the laminate obtained in Example 1 are shown together in Table 1 together with the composition of the epoxy resin composition.
Thermal conductivity: A plate-like sample of 50 mm × 120 mm was cut out from the laminate and measured at room temperature in accordance with the probe method.

Comparative Example 1
A prepreg and a laminate were obtained in the same manner as in Example 1 except that “YL6121H” was not used and a bisphenol A type epoxy resin (“EP828” manufactured by Japan Epoxy Resin, epoxy equivalent 185) was used instead. The thermal conductivity of this laminate was 0.5 W / m · K, which was significantly smaller than that of Example 1.

Comparative Example 2 (for the invention of the production method)
The varnish of the epoxy resin composition was prepared in the same manner as in Example 1 except that the blending volume part of the inorganic filler with respect to 100 volume parts of the resin solid content including the epoxy resin monomer and the curing agent was changed to 120 volume parts. did. However, in the stirring with a homomixer, the viscosity of the varnish of the epoxy resin composition became too high, and a varnish for producing a prepreg could not be obtained.

Examples 2-6
Using the varnish of the epoxy resin composition in which the compounding volume part of boron nitride with respect to 100 parts by volume of the resin solid content including the epoxy resin monomer and the curing agent is changed as shown in Table 1, the other processes are the same as in Example 1. Thus, a prepreg and a laminate were obtained. In preparing the varnish, the mixture was stirred with a homomixer until the volume part of boron nitride was 100 parts by volume, and kneading was performed using a ball mill when the composition exceeded that.
As a result of cutting out a plate sample of 50 mm × 120 mm from this laminated plate and measuring the thermal conductivity, the amount of boron nitride in the range of 10 to 900 parts by volume with respect to the resin solid content (Examples 1 to 6) was added. As the value increases, the thermal conductivity also increases. When kneading with a ball mill, a prepreg and a laminate were produced in a range exceeding 100 parts by volume and 900 parts by volume, and high thermal conductivity was obtained.

Example 7
Instead of using boron nitride “GP”, instead of aluminum nitride, which is a spherical inorganic filler (“R15S” manufactured by Toyo Aluminum, average particle size 15 μm, thermal conductivity 100 W / m · K, particle shape: spherical) A prepreg and a laminate were obtained in the same manner as in Example 1 except that 154 parts (50 parts by volume with respect to 100 parts by volume of the resin solid content) were used. The laminated board had a thermal conductivity of 1.6 W / m · K, which was slightly lower than Example 1, but a laminated board having a high thermal conductivity was obtained.

Example 8
Instead of using boron nitride “GP”, instead of magnesium oxide, which is a spherical inorganic filler (“5301” manufactured by Kyowa Chemical, average particle size 5 μm, thermal conductivity 30 W / m · K, particle shape: spherical) A prepreg and a laminate were obtained in the same manner as in Example 1 except that 166 parts (50 parts by volume with respect to 100 parts by volume of the resin solid content) were used. The laminated board had a thermal conductivity of 1.3 W / m · K, which was slightly lower than Example 1, but a laminated board having a high thermal conductivity was obtained.

Comparative Example 3
In Example 1, boron nitride is not used as the inorganic filler, and instead, aluminum hydroxide having a low thermal conductivity and spherical particles (“C-302A” manufactured by Sumitomo Chemical Co., Ltd., average particle diameter of 2.0 μm, A prepreg and a laminate were obtained in the same manner as in Example 1 except that 115 parts (50 parts by volume with respect to 100 parts by volume of the resin solid content) of 115 parts (thermal conductivity: 3.0 W / m · K, particle shape: spherical) was used. . The thermal conductivity of this laminate was 0.7 W / m · K, which was greatly reduced from that of Example 1.

Comparative Examples 4 and 5
Using the varnish of the epoxy resin composition in which the blending volume part of the inorganic filler with respect to 100 parts by volume of the resin solid content combining the epoxy resin monomer and the curing agent is changed as shown in Table 1, other than that is the same as in Example 1 Thus, a prepreg and a laminate were obtained. When the volume part of the filler relative to 100 parts by volume of the resin solid content was 5 parts by volume, the impregnation unevenness was confirmed in the prepreg as in Comparative Example 1, and the thermal conductivity was lowered (Comparative Example 4). If the volume is 910 parts by volume, the viscosity becomes too high and kneading by a ball mill becomes difficult, and the sheet-like fiber base material cannot be uniformly impregnated, making it impossible to produce a prepreg and a laminate (Comparative Example 5). .

Claims (6)

In the prepreg in which an epoxy resin composition containing an epoxy resin and a curing agent is held on a sheet-like fiber base material to be in a semi-cured state, the epoxy resin is an epoxy compound having a molecular structure represented by (formula 1), and heat A prepreg containing an inorganic filler having a conductivity of 20 W / m · K or more in an epoxy resin so as to be 10 to 900 parts by volume with respect to 100 parts by volume of a resin solid content.

  The prepreg according to claim 1, wherein the inorganic filler is not spherical. The prepreg according to claim 1 or 2, wherein the epoxy resin is an epoxy compound having a molecular structure represented by (Formula 2).

  The epoxy resin composition containing an epoxy resin, a hardening | curing agent, and an inorganic filler with a thermal conductivity of 20 W / m · K or more is held on a sheet-like fiber base material, and is in a semi-cured state. In the production of a prepreg, an epoxy resin composition in which the inorganic filler is blended in an amount of more than 100 parts by volume with respect to 100 parts by volume of resin solids, the epoxy resin composition is mixed with a ball mill, a bead mill, and a plurality of rolls. A method for producing a prepreg, characterized by being kneaded by a kneading means selected from a configured roll mill or a means equivalent to the kneading means and held in a sheet-like fiber base material to be in a semi-cured state.   The laminated board formed by heat-press-molding the prepreg in any one of Claims 1-3 as the whole layer or one part layer of a prepreg layer.   A printed wiring board comprising an insulating layer formed by heat-pressing the prepreg layer according to claim 1.