JP2010260990A - Prepreg, method for producing the same and printed wiring board using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a prepreg that is excellent in thermal conductivity, is inexpensive, has excellent processability and satisfies wiring embedding property in the case of multilayer formation and to provide a substrate. <P>SOLUTION: A prepreg 1 is composed of a core material 3 and a composite material 4 impregnated into the core material 3. The composite material 4 is composed of a resin body 6 in a semi-cured state and an inorganic filler 5 dispersed in the resin body and the content of the composite material 4 in the prepreg 1 is not less than 55 vol.% to not more than 95 vol.%. The content of the inorganic filler 5 in the composite material is not less than 35 vol.% to not more than 65 vol.%. and the inorganic filler is an inorganic filler such as magnesium oxide and the like which has a median diameter of not less than 1 μm to not more than 10 μm and a BET specific surface area of not less than 0.1 m<SP>2</SP>/g to not more than 2.0 m<SP>2</SP>/g. The composite material includes one or more kinds of wetting dispersants and more preferably, further includes one or more kinds of organosilicon compounds. Thus, the prepreg has enhanced thermal conductivity and enhanced processability. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a prepreg used when mounting various electronic components such as power semiconductors requiring heat countermeasures at high density, a manufacturing method thereof, and a printed wiring board using the prepreg.

  Conventionally, as a printed wiring board for mounting an electronic component, a laminate of a plurality of sheets, integrated, and a cured member made of a prepreg made of glass epoxy resin and copper foil is used.

  With the miniaturization and high performance of equipment, heat generation of electronic components often becomes a problem, and printed wiring boards having heat dissipation (or thermal conductivity) are required as a new heat countermeasure.

  In order to increase the thermal conductivity of the prepreg and the printed wiring board after curing, it has been proposed to add an inorganic filler at a high density.

  For example, boron nitride, nitrogenated magnesium carbonate, magnesium hydroxide, calcium carbonate, calcium oxide, aluminum hydroxide, alumina and other nitrides, titanium oxide, magnesium oxide carbonate, magnesium hydroxide, calcium carbonate, calcium oxide, hydroxide Examples include the use of inorganic fillers such as oxides such as aluminum and alumina (Patent Document 1: JP-A-60-136298).

  In general, when the inorganic filler is highly filled, the viscosity of the composite material composed of the resin and the inorganic filler during prepreg production is increased, and when the varnish is formed with a solvent, the dispersibility of the inorganic filler decreases and the occurrence of sediment There is a concern that uneven distribution of the filler occurs after the impregnation application, and problems such as warpage and solder heat resistance are considered. Therefore, the action of adding a wetting and dispersing agent or an organosilicon compound is known in order to improve the dispersibility of the filler under high filling conditions (Patent Document 2: JP 2001-96668 A).

  Regarding the inorganic filler, the above-mentioned nitride is expensive in price, and if the filling amount of the inorganic filler is increased, the prepreg and a printed wiring board using the prepreg become very expensive. In addition, metal oxides such as titanium oxide, magnesium oxide carbonate, magnesium hydroxide, calcium carbonate, calcium oxide, aluminum hydroxide, and alumina have a high hardness and can be easily machined when creating printed wiring boards. Inferior.

  Therefore, it is conceivable to use magnesium oxide as the inorganic filler as a filler that is inexpensive in price, excellent in workability, and has high thermal conductivity.

  However, inexpensive magnesium oxide is generally called light-burned magnesia, and the particles are formed in the form of aggregated primary particles of submicron to several μm, so the surface area is very large and the BET ratio Since the surface area has a high value, it is difficult to blend a high filling amount. Therefore, it has been proposed to obtain higher fluidity by improving the shape of magnesium oxide as in International Publication No. 2005/033214 (Patent Document 3: International Publication No. 2005/033214). However, in these inventions, although the absorption and flow coefficient of particles are improved, the particle size itself is limited.

  However, in a printed wiring board in which a wiring pattern made of copper foil is formed in a plurality of layers, in order to improve the mounting density, at least one surface of the inner layer is provided with a laminate on which a copper foil pattern shape is processed. Furthermore, in order to improve the wiring density, it is necessary to specify the thickness of the prepreg to ensure the number of layers, and in addition, the line pattern / space itself of the wiring pattern must be designed more precisely. ing.

  Furthermore, in the wiring board which takes measures against heat, there is a use such as providing a thick copper foil of 70 μm or the like in order to improve the thermal conductivity by the inner layer copper foil.

  On such a laminate in which the inner layer copper foil wiring pattern shape is processed, when setting a prepreg and further forming a wiring pattern with copper foil on the upper layer, an inorganic filler is put in a certain amount, and In a system in which the amount of the composite material in the prepreg is limited, a phenomenon such as whitening occurs due to a void in the vicinity of the copper foil wiring pattern due to a decrease in fluidity of the composite material.

  Therefore, in order to form a printed wiring board in which a copper foil wiring pattern is formed in a plurality of layers having excellent thermal conductivity, the thickness of the prepreg is limited, and the embedding property of the thick inner layer copper foil pattern is In addition to increasing the varnishing viscosity during prepreg production, reducing the dispersibility of the inorganic filler, generating precipitates, uneven distribution of the filler after impregnation, etc. It has become a challenge.

  For example, Patent Documents 1 to 3 are known as prior art document information relating to this application.

JP 60-136298 A JP 2001-96668 A International Publication No. 2005/033214

  As described above, in the case of the conventional printed wiring board, increasing the filling amount of the inorganic filler to increase the thermal conductivity of the printed wiring board causes problems in prepreg creation, and further increases in price and decreases in workability. Furthermore, the wiring embedding property of the printed wiring board is deteriorated.

  Therefore, the present invention focuses on inorganic fillers and additives when constituting a prepreg, and further focuses on the composition of the constituent resin and the base material, and overcomes the above problems while increasing the thermal conductivity of the printed wiring board. An object of the present invention is to provide a prepreg and a printed wiring board that can maintain characteristics.

A prepreg having a thermal conductivity of 0.5 W / (mK) or more and 30 W / (mK) or less after curing, the prepreg comprising a core material and a composite material impregnated in the core material,
The composite material is composed of a semi-cured resin body, an inorganic filler dispersed in the resin body, and one or more wet dispersion materials, and the proportion of the composite material in the prepreg is 55% by volume to 95% by volume. And the proportion of the inorganic filler in the composite material is 35 volume% or more and 65 volume% or less, and the inorganic filler is magnesium oxide and magnesium carbonate, magnesium hydroxide, calcium carbonate, calcium oxide, aluminum hydroxide, alumina , Aluminum nitride, boron nitride, silicon carbide, silicon nitride, silica, zinc oxide, titanium oxide, tin oxide, carbon, and an inorganic filler composed of at least one selected from zircon silicate, and the inorganic filler and a median diameter of 1μm or more 10μm or less, BET specific surface area of 0.1 m ² / SUMMARY by at most more than ^2m 2 / g.

  According to the prepreg of the present invention, a manufacturing method thereof, and a printed wiring board using the prepreg, it is possible to obtain a prepreg and a printed wiring board that are excellent in thermal conductivity, solve the wiring embedding, and have excellent workability. In addition, by using a printed wiring board manufactured using the prepreg of the present invention, it is possible to mount electronic components and the like at high density, thereby reducing the size and performance of liquid crystal displays, plasma TVs, and various electronic devices. It becomes possible.

Sectional drawing and enlarged sectional view of the prepreg in the embodiment of the present invention The figure which shows an example of the manufacturing process of the prepreg in embodiment of this invention Sectional drawing which shows the manufacturing process of the multilayer printed wiring board in embodiment of this invention Sectional drawing which shows the manufacturing process of the multilayer printed wiring board in embodiment of this invention

(Embodiment 1)
Hereinafter, a prepreg will be described as a first embodiment of the present invention.

  FIG. 1A is a cross-sectional view of a prepreg in the embodiment.

  As shown in FIG. 1A, a prepreg 1 described in the embodiment is composed of a core material 3 and a composite material 4 which is a semi-cured resin body 6 impregnated in the core material 3. And the opening part (part shown by the arrow 7) of the core material 3 and the surface of the core material 3 are covered (or filled) with the composite material 4.

  Next, the structure of the opening will be described in detail. FIG. 1B is an enlarged cross-sectional view of the opening of the prepreg in the embodiment of the present invention. As shown in FIG. 1B, the composite material 4 has an inorganic filler 5 dispersed in a semi-cured resin body 6.

  Here, in the embodiment, the core 3 is positively formed with an opening, and the opening is filled with a semi-cured resin body 6 as shown in FIG. This will increase the thermal conductivity in the direction.

  The thickness of the core material 3 is desirably 10 μm or more and 300 μm or less. When the thickness of the core material 3 is less than 10 μm, the mechanical strength (for example, tensile strength) of the prepreg 1 (or a printed wiring board formed by curing the prepreg 1) may be affected. When the thickness of the core material 3 exceeds 300 μm, the thickness of the prepreg 1 is increased, which may affect the handleability (for example, difficult to wind).

  When a woven fabric is used for the core material 3, in FIG. 1A, an arrow 7 indicates an opening portion of the core material 3 in which the core material fibers 2 are woven (this opening portion is also called a basket hole portion). Is). Moreover, when the nonwoven fabric is used for the core material 3, the arrow 7 has shown the space where a fiber does not exist among the core materials 3 obtained by the core material fiber 2 couple | bonding as an opening part. Here, the aperture ratio is a percentage (unit:%) of the area ratio of the opening in which the core fiber is not present when the core material is projected.

  The opening ratio in the core material 3 is preferably 50% or less. In particular, 25% to 50% is desirable. When the opening ratio is less than 25%, the heat conductivity in the thickness direction of the prepreg 1 (that is, heat conduction through the opening) may be affected. Further, when the opening ratio exceeds 50%, the tensile strength of the prepreg 1 may be affected.

  Further, by making the prepreg 1 difficult to contract in the XY direction, the prepreg 1 can be made difficult to extend in the Z direction (thickness direction). As a result, the effect of improving the reliability of the printed wiring board in the Z direction (for example, the connection reliability of the through hole portion) can be obtained. This is because the thermal expansion in the Z direction is suppressed.

  Moreover, the effect of improving the workability of the via hole by the laser of the prepreg 1 or a drill is also acquired by raising the aperture ratio of the core material 3.

  In the present invention, a glass cloth with a thickness of 80 μm was used as the core material, and a glass cloth with a thickness of 40 μm was used as a thin material.

  The thickness of the prepreg 1 is desirably 20 μm or more and 500 μm or less. When the thickness of the prepreg 1 is less than 20 μm, the mechanical strength (for example, tensile strength) of the prepreg 1 (or a printed wiring board formed by curing the prepreg 1) may be affected. Further, when the thickness exceeds 500 μm, the handling property (for example, difficult to wind) may be affected.

(Embodiment 2)
Next, as a second embodiment, an example of a method for manufacturing the prepreg 1 will be described with reference to FIG. FIG. 2 is a schematic diagram illustrating an example of a method for manufacturing the prepreg 1 in cross section. In FIG. 2, 8 is a roll, which schematically shows part of the prepreg manufacturing equipment. 9 is a composite material varnish and 10 is a tank. In the tank 10, the member forming the composite material 4, that is, the resin body 6 and the inorganic filler 5 are dissolved in a predetermined solvent (for example, methyl ethyl ketone, alcohols, cyclopentanone, etc .: methyl ethyl ketone is used in this embodiment).・ Set in a mixed state.

  Then, as shown in FIG. 2, the core material 3 is set on the roll 8 and sent in the direction indicated by the arrow 7 a to impregnate the composite material varnish 9 set in the tank 10. The amount of impregnation of the composite material varnish 9 impregnated in the core material 3 is adjusted while turning the roll 8 in the direction of the arrow 7b. Then, the solvent component is removed from the impregnated composite material varnish 9 by flowing through a dryer or the like (not shown) as indicated by an arrow 7c. Furthermore, the prepreg 1 is continuously produced by making the resin component contained in the composite material into a semi-cured state (state before main curing, so-called B-stage state) by heating or the like. In addition, the manufacturing method of the prepreg 1 is not limited to this.

  Moreover, the core fiber 2 and the inorganic filler 5 are surface-treated by performing a surface treatment on the core fiber 2 with a surface treatment agent such as a silane coupling agent, a phosphate ester, a sulfonate ester, or a carboxylic ester. By having a bonding force through the agent, both the thermal conductivity and mechanical strength of the prepreg 1 can be achieved.

  Here, when the viscosity of the composite material varnish 9 is high, the coating property is lowered, the surface property of the prepreg is lowered, and this may cause a poor adhesion at the time of forming the final printed wiring board. In particular, when the proportion of the inorganic filler 5 is large, it is affected by the properties of the inorganic filler, and the viscosity characteristics are significantly changed. As a result, the productivity of the prepreg and the printed wiring board is greatly affected.

(Embodiment 3)
Next, as a third embodiment, a method for manufacturing a printed wiring board having high thermal conductivity using the prepreg 1 will be described.

  3A and 3B are cross-sectional views illustrating an example of a method for fixing (or integrating) a copper foil to the surface of the prepreg 1.

  First, as shown in FIG. 3A, a copper foil 12 is set on one or more surfaces of a prepreg 1 including a semi-cured composite material 4 and a core material 3 impregnated with the semi-cured composite material 4. Then, the press 11 is moved as indicated by the arrow 7, and the copper foil 12 is attached to one or more surfaces of the prepreg 1. 3A and 3B, a mold set on the press 11 is not shown. These members are integrated at a predetermined temperature and pressure. Thereafter, the press 11 is pulled away in the direction of the arrow 7 as shown in FIG. In this way, the copper foil 12 is fixed to one or more surfaces of the prepreg 1 to obtain a laminate 14. In this way, by fixing the copper foil 12 on the prepreg 1 without using an adhesive or the like, high thermal conductivity of the finished laminate 14 is realized.

Next, the copper foil 12 fixed to one or more surfaces of the laminate 14 is patterned into a predetermined shape. Note that patterning steps (photoresist application, exposure, development, copper foil 12 etching, photoresist removal step, etc.) are not shown.

  Next, with reference to FIGS. 4A to 4C, a state in which the stacked body 14 is stacked to form a four-layer printed wiring board will be described.

  FIGS. 4A to 4C are schematic views illustrating in section how a multilayer (for example, four layers) printed wiring board is created.

  First, as shown to FIG. 4 (A), the laminated body 14 which provided the copper foil pattern 13 which processed the copper foil 12 in the predetermined pattern shape at least on the one surface or more is prepared. And the prepreg 1 is set so that this laminated body 14 may be pinched | interposed. Further, a copper foil 12 is set on the outside of the prepreg 1. In addition, when using the commercially available copper foil 12, the adhesive force (anchor effect) of the copper foil 12 and the prepreg 1 can be improved by setting the rough surface side to the prepreg 1 side. In this state, a press device (not shown) is used to pressurize, heat, and integrate these members. By heating at the time of pressing, the semi-cured composite material 4 included in the prepreg 1 is softened, and the pattern of the copper foil 12 fixed on the prepreg 1 (or the embedding of a step by the pattern) or the copper foil 12 The effect of increasing the adhesion is obtained. Moreover, the effect which fixes the copper foil 12 is also acquired, without using an adhesive agent. In this way, the laminated body 14 is created.

  Next, the hole 15 is formed in the predetermined position of this laminated body 14, and it is set as the state of FIG. 4 (B). In FIG. 4B, the hole 15 is formed by a drill, a laser or the like (both not shown).

  Thereafter, copper plating is performed on the inner wall of the hole 15 to obtain the state shown in FIG. As shown in FIG. 4C, interlayer connection between the copper foils 12 formed on the inner layer or the surface layer is performed by the copper plating portion 16. Next, the printed wiring board 17 is completed by forming a solder resist (not shown) or the like.

  Here, the amount of the composite material 4 in the prepreg 1 is determined by the amount of the composite material 4 impregnated into the glass core material 3. If the amount of the composite material 4 is not sufficient, the content of the inorganic filler 5 in the prepreg 1 is lowered, and it becomes difficult to obtain sufficient thermal conductivity. Furthermore, since sufficient thickness of the composite material 4 which covers the surface of the core material 3 cannot be ensured, the absorption effect of the thickness of the inner layer copper foil pattern 13 in FIGS. 3 (A) to 3 (B) is reduced. In particular, in the high thermal conductivity prepreg according to the present invention, the thickness absorption effect varies depending on the filling amount of the inorganic filler 5, so that a poor filling of the inner layer copper foil pattern 13 occurs.

  In addition, if the amount of impregnation is too large, in addition to the adverse effect of the handling properties of the prepreg, it is difficult to dry the varnish 9 or when the prepreg is created due to insufficient semi-cured state and when the printed wiring board is produced, The effects of sticking and even dropping off are considered. Therefore, the ratio of the prepreg of the composite material is 35 to 95% by volume, desirably 55 to 90% by volume.

(Embodiment 4)
Next, the member which comprises the semi-hardened composite material 4 is demonstrated in detail using Embodiment 4. FIG.

  The composite material 4 is composed of a thermosetting resin mainly composed of an epoxy resin and an inorganic filler that enhances heat conductivity. For example, the thermosetting resin mainly composed of an epoxy resin enhances moldability as a printed wiring board. Therefore, a thermoplastic resin can be added instead of the rubber resin. Note that a thermoplastic resin as well as a rubber resin may be added in the form of fine particles with an epoxy resin or the like. By doing so, the effect of improving the mechanical strength can be obtained even with a small amount. Further, an acrylic resin, which is a kind of thermoplastic resin, can be made into a fine particle shape and added for use as a stress relaxation agent or a composite material reinforcing material.

  In addition, thermal conductivity in a resin part can be raised by making 40 weight% or more of epoxy resins into crystalline epoxy resin. When the proportion of the crystalline epoxy resin in the entire epoxy resin is less than 40% by weight, the effect of adding the crystalline epoxy resin may not be obtained. Moreover, heat conduction can be improved by making all of the epoxy resin (or 100% by weight) crystalline epoxy. Moreover, although the crystalline epoxy resin after hardening may be easily broken in some cases, it can be made difficult to break by adding a rubber resin or a thermoplastic resin. By adding these as fine particles, the influence on heat conduction can be suppressed.

  In the present invention, a wetting and dispersing agent or an organic silicon compound is added as an additive to the heat-conducting inorganic filler 5.

  Here, examples of the wetting dispersant include a dispersant having a molecular structure having both a polar hydrophilic group adsorbed on the inorganic filler 5 and a nonpolar hydrophobic group compatible with the resin. Saturated polyester copolymer or unsaturated polyester copolymer, polycarboxylic acid copolymer, alkylammonium salt or unsaturated polyamine amide salt, polyhydric alcohol ether or polyacrylic acid-polystyrene copolymer Is mentioned.

  Here, the polar hydrophilic group that adsorbs to the inorganic filler 5 is desirably determined according to the surface activity of the inorganic filler 5, and has an acidic adsorbing group in a highly alkaline system such as magnesium oxide. Thus, the affinity is improved, and further, the presence of a plurality of the polar groups in the molecule improves the adsorptivity to the surface of the inorganic filler 5.

  As the organosilicon compound, an organosilicon compound having a hydrolyzable group composed of Si—O—R and an organic functional group that interacts with an organic substance can be used. For example, examples include an alkoxysilane having a hydrocarbon structure from a silane coupling agent having a vinyl group, an epoxy group, or a methacryloxy group as an organic functional group.

  Here, in the organosilicon compound, 1 to 3 (plural) hydrolyzable groups starting from Si atoms are adsorbed on the inorganic surface (including bonds by dehydration condensation), and the organic functional group interacts with the organic system. By doing so, the reciprocity between the inorganic filler 5 and the resin body 6 is improved. Compared with the wet dispersion described above, the density of adsorbing groups in the molecule is large and the functional group has a small molecular weight. Many. For this reason, in systems such as magnesium oxide, it compensates for the adsorption to the inorganic filler adsorption surface, which is insufficient with wet dispersion, and also provides the interreactivity of the organic functional groups with the resin body 6 and a relatively low water content hydrocarbon. With the organic functional group of the system, effects such as imparting reactivity to the resin body 6 and improving the plasticity can be obtained, and with the system using magnesium oxide for the inorganic filler 5 and the like, the improvement of moisture resistance, which is a problem of the substance, can be achieved. It is also possible to obtain.

  Moreover, the addition amount of this additive is 0.1-30 wt% with respect to 5 amount of inorganic fillers, It is desirable to add 0.2-5 wt% desirably.

  Next, as an example and a comparative example, as shown in the following (Table 1), in an additive composition of an inorganic filler characterized by being a median diameter and BET, and a corresponding wetting and dispersing agent and an organosilicon compound, A printed wiring board was created.

  Here, for the wetting and dispersing agent, BYK-W903 and BYK-W9010, multifunctional wetting and dispersing agents of BYK Chemie, alkyl ammonium salt DISPERBYK-180 of block copolymer containing acid groups, and blocks that have an affinity for pigments The copolymer Disper-BYK2163 is selected from Disper-BYK2164 DisperBYK-2155, and the organosilicon compound includes, as an alkoxysilane, phenyltriethoxysilane (KBM-103 manufactured by Shin-Etsu Chemical Co., Ltd.) having a phenyl group in the organic chain, phenyltri Ethoxysilane (KBE-103 manufactured by Shin-Etsu Chemical Co., Ltd.), 3-glycidoxypropyltrimethoxysilane (KBM-403 manufactured by Shin-Etsu Chemical Co., Ltd.) having an epoxy group in the organic chain as a silane coupling agent, 3-glycidoxypropyltri It was selected from ethoxysilane (KBE-403 manufactured by Shin-Etsu Chemical Co., Ltd.) and used.

  The measurement results of the characteristics of the printed wiring board 17 prepared as this example include the heat conduction of the printed wiring board molded body, the wiring embedding property at the time of multilayer formation, the results of the moisture and heat resistance test, and the Line / Space when using a thin prepreg. The wiring formability and varnish viscosity were evaluated.

  The detailed configuration in each measurement is shown below.

  Here, the filler content in the composite material was designed to be 40% by volume.

  In order to mix with the epoxy resin and the curing agent so as to have a predetermined inorganic filler content, the solid content was mixed and dissolved in a predetermined amount of solvent of 80% by weight, varnished, and the viscosity was evaluated. . After that, for those having a high viscosity (500 mPa · s or more), adjustment was made by adding a solvent to the solid content so that the viscosity could be impregnated and applied.

  Further, impregnation was applied so that the amount of the composite material with respect to the prepreg was 80% by volume, and a molded article for measuring thermal conductivity, a molded article for embedding preparation, and a moisture absorption solder heat test specimen were formed. Here, regarding the embedding property, in FIG. 4A, the thickness of the copper foil pattern 13 was set to be 35% of the thickness of the prepreg 1 and the embedding property was confirmed. In the moisture absorption heat resistance test, a printed wiring board having a copper foil on the entire surface was formed, and after a pretreatment of drying at 125 ° C. for 24 hours, as a moisture absorption treatment, (1) left for 192 h at 30 ° C.-60 RH%, (2 ) After absorbing moisture under two conditions of 174 h at 85 ° C.-60 RH%, the presence or absence of blistering in the solder flow at 260 ° C. for 3 minutes was confirmed with a sample of n = 3.

  Next, as a verification of thin prepreg, a prepreg using a core material thickness of 40 μm is formed, and using this prepreg, a printed wiring board pattern can be formed with a copper foil wiring pattern (Line / Space = 40 μm / 40 μm). It was confirmed.

  The results are shown in (Table 2).

  As shown in Table 2, in the varnish viscosity, the composite material varnish was used in the system using the high BET inorganic filler of Comparative Example 1 or the system of Comparative Example 2 without the wet dispersion or addition of the silane coupling material. An increase in varnish viscosity, which causes deterioration of prepreg coating productivity, has been observed due to the mutual agglomeration between the inorganic filler surface and the resin.

On the other hand, the median diameter of the fillers of Examples 1 to 6 is 1 μm or more and 10 μm or less, and the BET specific surface area is a magnesium oxide filler of 2 m ² / g or less. Furthermore, the wetting dispersant and the organosilicon compound By adding one or more types, it is possible to maintain and reduce the viscosity, and to prevent deterioration of the prepreg coating productivity.

  Next, with regard to thermal conductivity, 0.5 W / (mK) or more is secured in any composition, but the system using the high BET inorganic filler of Comparative Example 1 and the wet dispersion and organic of Comparative Example 2 are used. In the system in which no silicon compound is added, poor wiring embedding is observed. Further, in Comparative Examples 1 and 2, since the adhesion between the molded body interface and the copper foil is poor, a defect that causes swelling also occurs in the heat resistance test after moisture absorption. The effects of the wet dispersion and the addition of the organosilicon compound will be described in detail below (Table 3).

  Comparative Example 3 is a system using a filler in which BET is reduced by increasing the particle diameter. In such a system, the wiring embedding property is improved. However, in the thin prepreg, when the wiring pattern L / S = 40 μm / 40 μm, the line-shaped unevenness is generated and the line is peeled off and cannot be formed. It has become. This is presumably because the presence of large particles with respect to the line width greatly reduced the surface roughness of the thin prepreg, resulting in a decrease in line linearity and adhesion.

In contrast, by using an inorganic filler having a median diameter of 10 μm or less and a BET specific surface area of 2.0 m ² / g or less, it is possible to form a wiring pattern even in a thin prepreg. is doing.

Thus, the median diameter of the fillers of Examples 1 to 6 is 1 μm or more and 10 μm or less, the BET specific surface area is 2.0 m ² / g or less, and further, the wetting dispersant and the organosilicon compound are 1 By adding more than one type, it is possible to satisfy the thermal conductivity and the wiring embedding property at the time of multilayer formation, and also secure a wiring pattern that can be formed in a thin prepreg.

  Further, by adding an organosilicon compound in addition to the wetting and dispersing agent, further improvement of the moisture resistance test can be seen as in Examples 1 to 5.

  Furthermore, in order to verify in more detail the effects of the addition of the wetting and dispersing agent and the organosilicon compound and the effects of the filler shape, the amount of filler / composite material is 20% by volume for each composition of (Table 1). The prepreg and the printed wiring board were formed by changing the volume to 80% by volume or less, and the relationship between the thermal conductivity with respect to the filler amount in the composite material and the wiring embedding property at the time of multilayer formation was evaluated.

  The results are shown in (Table 3).

As is apparent from the results of (Table 3), in order to obtain a thermal conductivity of 0.5 / (mK) or more regardless of the shape of the filler, the filler addition amount is 35 volume% or more. However, the wiring embeddability differs depending on the shape of the filler and the presence or absence of additives (however, in Comparative Examples 1 and 2, prepreg formation was impossible because the varnish viscosity was not adjustable).

As a result of using magnesium oxide having a filler particle size of 3 μm and a high BET of 10 m ² / g in Comparative Example 1, when the filler amount is 35% by volume, the wiring embeddability has already deteriorated, both the thermal conductivity and It is impossible to satisfy.

On the other hand, when a filler with a filler particle size of 3 μm and a BET of 1 m ² / g is used, even in Comparative Example 2 without wet dispersion and addition of an organosilicon compound, the wiring embedding ability is up to 35 volume% filler. A slightly improved tendency is seen, which is better than Comparative Example 1.

  In addition, in Example 6 in which the wetting dispersant was added, the wiring embedding was good up to a filler amount of 50%, and in Example 1 in which both the wetting dispersant and the organosilicon compound were added, even better. The result is obtained.

Furthermore, as in Examples 2 and 3 and 4 and Comparative Example 3, the BET specific surface area is in the range of 2.0 m ² / g or less (up to 0.6 m ² / g) regardless of the particle diameter of the filler. When the filler particle diameter is changed, the wiring embedding property is obtained even with the filler amount satisfying the thermal conductivity regardless of the particle diameter.

Thus, in the magnesium oxide which is an inorganic filler, the embedding characteristic is improved by setting the BET to 2.0 m ² / g or less. This is because even when a certain amount of filler is filled, the influence of the surface activity of magnesium oxide is reduced, so that the amount of resin adsorbed and unevenly distributed between the filler surface and between the filler and inside the filler is reduced. It is considered that the flow of the resin at the time of hot press molding is possible, and as a result, the resin is pushed into the step of the wiring pattern, which is improved.

  Further, by adding a wetting and dispersing agent, when the resin is dissolved during heating press, the wetting and dispersing agent is previously adsorbed on the surface of magnesium oxide, which is an inorganic filler, so that the molten resin filler By preventing excessive adsorption and uneven distribution on the particle surface and inside the filler, and further increasing the interaction of the hydrophobic group of the wetting and dispersing agent with the resin, the effect of dispersing the filler in the molten resin also increases. As a result, it is considered that the wiring embedding property is improved because the fluidity during hot pressing is greatly improved.

  This effect becomes more effective in the BET specific surface area-reducing filler, as described above, because the surface active point of the filler is lowered, and further, the filler surface is also improved in crystallinity due to improved sintering.

  Furthermore, by adding an organosilicon compound, improvement in moisture resistance and further improvement in embedding property are seen. This is thought to be due to an increase in the effect of improving fluidity, as well as the moisture resistance of the organosilicon compound, as well as the coating effect on the filler surface that could not be coated with the wet dispersant, as well as the effect of filler dispersibility. Furthermore, among them, it is considered effective by selecting an organic functional group having a hydrocarbon-based phenyl group to increase the plastic effect with respect to the epoxy resin at the time of melting.

As is apparent from this result, in the state where the amount of the inorganic filler component necessary for obtaining a constant heat conduction is added, the wiring embeddability is greatly reduced when the BET specific surface area is 2 m ² / g or more. On the other hand, the median diameter of the filler is 1 μm or more and 10 μm or less, the BET specific surface area is 0.1 m ² / g or more and 2 m ² / g or less, and further, one or more kinds of wetting dispersant are added. This makes it possible to easily reduce the varnish viscosity during prepreg creation, easily create a uniform prepreg, satisfy the thermal conductivity and wiring embedding properties during multilayer formation, and be thin. Even in the prepreg, the formation of fine wiring was maintained, and good results were obtained without the occurrence of blistering by the moisture absorption heat test.

  Furthermore, by adding an organosilicon compound, it is possible to further improve the wiring embedding property and the moisture absorption heat resistance test result, and this effect is further effective particularly when magnesium oxide is used as the inorganic filler. .

Furthermore, a printed wiring formed by laminating and curing a plurality of prepregs having a heat conductivity after curing of 0.5 W / (mK) to 30.0 W / (mK) and a copper foil processed into a predetermined pattern A prepreg having a thermal conductivity of 0.5 W / (mK) or more and 30.0 W / (mK) or less after the prepreg is cured, the prepreg being impregnated with a core material and the core material The composite material is composed of a semi-cured resin body and an inorganic filler dispersed in the resin body, and the ratio of the composite material in the prepreg is 75% by volume to 95% by volume. And the proportion of the inorganic filler in the composite material is not less than 35% by volume and not more than 65% by volume, and the inorganic filler comprises magnesium oxide, magnesium carbonate, magnesium hydroxide, carbonic acid Inorganic consisting of at least one selected from Lucium, Calcium oxide, Aluminum hydroxide, Alumina, Aluminum nitride, Boron nitride, Silicon carbide, Silicon nitride, Silica, Zinc oxide, Titanium oxide, Tin oxide, Carbon, Zircon silicate The filler has a median diameter of not less than 1 μm and not more than 10 μm, a BET specific surface area of not less than 0.1 m ² / g and not more than 2.0 m ² / g, and one kind of wetting dispersant By providing a printed wiring board comprising the above, more preferably containing at least one organic silicon compound, and the inorganic filler is preferably magnesium oxide, a cellular phone, plasma Miniaturization and high performance of televisions, electrical components, and industrial devices that require heat dissipation can be realized.

  As described above, by using the prepreg according to the present invention and the manufacturing method thereof and the printed wiring board using the prepreg, it is possible to reduce the size of a mobile phone, a plasma television, an electrical component, or an industrial device that requires heat dissipation. And high performance.

1 Prepreg 2 Core fiber 3 Core material (woven fabric, non-woven fabric)
DESCRIPTION OF SYMBOLS 4 Composite material 5 Inorganic filler 6 Semi-hardened resin body 7 Arrow 8 Roll 9 Composite material varnish 10 Tank 11 Press 12 Copper foil 13 Copper foil pattern 14 Laminated body 15 Hole 16 Copper plating part 17 Printed wiring board

Claims (10)

A prepreg having a thermal conductivity after curing of 0.5 W / (mK) to 30.0 W / (mK), the prepreg comprising a core material and a composite material impregnated in the core material,
The composite material is composed of a semi-cured resin body, an inorganic filler dispersed in the resin body, and one or more wet dispersion materials.
The proportion of the composite material in the prepreg is 55% by volume or more and 95% by volume or less,
And the ratio of the inorganic filler in the said composite material is 35 volume% or more and 65 volume% or less,
The inorganic filler is magnesium oxide and magnesium carbonate, magnesium hydroxide, calcium carbonate, calcium oxide, aluminum hydroxide, alumina, aluminum nitride, boron nitride, silicon carbide, silicon nitride, silica, zinc oxide, titanium oxide, tin oxide, A prepreg having at least one selected from carbon and zircon silicate, having a median diameter of 1 μm to 10 μm and a BET specific surface area of 0.1 m ² / g to 2.0 m ² / g. The prepreg according to claim 1, wherein the wetting and dispersing agent comprises a copolymer containing one or more functional groups composed of acidic groups. The prepreg according to claim 1, wherein the composite material contains an organosilicon compound in addition to the wetting and dispersing agent. The ratio of magnesium oxide in an inorganic filler is 30 volume% or more, The prepreg as described in any one of Claim 1 to 3. The prepreg according to claim 1, wherein the core material has an aperture ratio of 50% or less and a thickness of 10 μm to 300 μm. The prepreg according to claim 1, wherein the resin body is an epoxy resin and a curing agent. The prepreg according to claim 6, wherein 40% by volume or more of the epoxy resin is a crystalline epoxy resin. The semi-cured resin body occupying the prepreg comprises at least one of a resin body composed of at least an epoxy resin and a curing agent, a thermoplastic resin having a glass transition temperature of 50 ° C. or higher and 130 ° C. or lower, and a rubber-like resin. The prepreg according to claim 1. A first step of preparing a composite material having a thermal conductivity of 0.5 W / (mK) or more and 30.0 W / (mK) or less comprising a resin body and an inorganic filler;
A second step of impregnating the composite material into a core material having a thickness of 10 μm to 300 μm;
In the manufacturing method of the prepreg which consists of the 3rd process which makes the said resin body a semi-hardened state,
In the first step, the inorganic filler is magnesium oxide having a median diameter of 1 μm to 10 μm and a BET specific surface area of 0.1 m ² / g to 2.0 m ² / g, and a wetting and dispersing agent. And a method for producing a prepreg comprising at least one silane coupling material. A printed wiring board obtained by laminating and curing a plurality of prepregs having a thermal conductivity after curing of 0.5 W / (mK) or more and 30 W / (mK) or less and a copper foil processed into a predetermined pattern,
The prepreg consists of a core material and a composite material impregnated in the core material,
The composite material is composed of a semi-cured resin body, an inorganic filler dispersed in the resin body, and one or more wet dispersion materials.
The ratio of the prepreg of the composite material is 75 volume% or more and 95 volume% or less,
And the ratio of the inorganic filler in a composite material is 35 volume% or more and 65 volume% or less,
The inorganic filler is magnesium oxide and magnesium carbonate, magnesium hydroxide, calcium carbonate, calcium oxide, aluminum hydroxide, alumina, aluminum nitride, boron nitride, silicon carbide, silicon nitride, silica, zinc oxide, titanium oxide, tin oxide, It is composed of an inorganic filler composed of at least one selected from carbon and zircon silicate, the median diameter of the filler is 1 μm or more and 10 μm or less, and the BET specific surface area is 2 m ² / g or less. Printed wiring board.

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