JP2005105035A - Prepreg, manufacturing method thereof and laminated plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a prepreg which inhibits the increase in voids in a substrate, the melt viscosity rise in the prepreg and the bad influence on a copper foil while improving such lowering of a thermal expansion coefficient and such elevating of an elastic modulus under the environment of high temperatures as required for a printed wiring board and which is excellent in the productivity of laminated plates. <P>SOLUTION: The prepreg is inside the glass cloth yarn bundle arranged with inorganic particles having an average particle diameter of from 1 nm to 100 nm, is outside the glass cloth yarn bundle arranged with inorganic particles having an average particle diameter of 500 nm to 5,000 nm, and besides is on the surface layer of the glass cloth yarn bundle arranged with inorganic particles having an average particle diameter of from more than the average particle diameter of the inorganic particles inside the glass cloth yarn bundle to less than the average particle diameter of the inorganic particles outside the glass cloth yarn bundle. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a prepreg for making a glass cloth reinforced resin laminate used for a printed wiring board. More specifically, the present invention relates to a prepreg having a low thermal expansion coefficient, a high elastic modulus under a high temperature environment, a low dielectric constant, a low dielectric loss tangent, and a good moldability in manufacturing a glass cloth reinforced laminate. .

  A glass cloth reinforced resin laminate (hereinafter simply referred to as “laminate”) processed into a printed wiring board or the like is manufactured as follows. First, a glass cloth is impregnated with a matrix resin solution (hereinafter referred to as “resin varnish”) in which a matrix resin mainly composed of a thermosetting resin such as an epoxy resin or a polyimide resin is dissolved in an organic solvent. Next, the organic solvent is dried by heating to produce a glass cloth resin-impregnated prepreg (hereinafter simply referred to as “prepreg”) in which the matrix resin is in a semi-cured state (hereinafter also referred to as “B stage”). Finally, one or a plurality of metal foils such as copper foil and prepregs are superposed, laminated by heating and pressurizing, and the B stage matrix resin is completely cured to obtain a laminate.

The conventional use of the printed wiring board has been mainly a motherboard use for mounting semiconductor packages and electronic components. However, in recent years, as electronic devices have become faster and lighter, thinner and smaller, they have been expanded to use as a substrate for mounting semiconductor devices to form packages. In addition, a mounting form called “bare chip mounting” in which a semiconductor device is directly mounted on a mother board has been studied.
In the above-mentioned laminated board for substrate use or mother board use in a bare chip mounting form, it is essential to mount a semiconductor device on a printed wiring board having a fine pattern. However, the thermal expansion coefficient of a semiconductor device mainly composed of a silicon wafer is 3 to 4 ppm / ° C., whereas the thermal expansion coefficient of a laminated plate composed of a normal epoxy resin and E glass cloth is 15 to 30 ppm / ° C. For this reason, there is a mismatch in thermal expansion coefficient, which may cause mounting failure. In addition, along with the above-mentioned reduction in size, the semiconductor device is mounted on a thin printed wiring board under high-temperature reflow conditions, so that the elastic modulus of the printed wiring board is reduced and deformation may occur, resulting in mounting failure. .

An alumina ceramic substrate is useful for solving the mismatch of the thermal expansion coefficient of the laminated plate and the reduction of the elastic modulus under a high temperature environment. However, the alumina ceramic substrate has a firing temperature as high as 1500 to 1700 ° C. and is difficult to be used for general purposes, has poor post-processability such as drilling, cutting, and bonding, and has a high dielectric constant of 9 or more, so it is high speed. There is a disadvantage that it is not suitable for mounting a semiconductor device for calculation. For this reason, research is being conducted to achieve a low thermal expansion coefficient and a high elastic modulus in a high temperature environment with resin-based composite materials such as glass cloth reinforced resin laminates.
An example of this is the method of using Q glass for the glass cloth used in the glass cloth reinforced resin laminate, but there is a limit to lowering the coefficient of thermal expansion and increasing the modulus of elasticity in high-temperature environments. There is a problem that the drill wearability at the time is great.

Further, as an improvement on the matrix resin side, a method of dispersing an inorganic filler such as alumina in a resin varnish to be impregnated into glass cloth (for example, see Patent Document 1) has been proposed. However, in the examples described in Patent Document 1, the inorganic filler has a large average particle size of 80 μm, and the amount of dispersion in the resin varnish is only 20% by mass. That is, the inorganic filler has a low upper limit of the amount of dispersion with respect to the resin varnish and has a particle size that is not filled between the single yarns inside the yarn bundle of the glass cloth, so that a sufficient effect is not exhibited.
Further, by impregnating a glass cloth with an aqueous solution in which colloidal silica particles having a particle diameter of 45 nm are dispersed in water, or a mixed solution of the aqueous solution and an ethanol solution of silicon alkoxide, heat treatment is performed so that silica particles are formed in and on the surface of the yarn bundle. A method of forming a composite material by making an impregnated glass cloth and then impregnating it with a resin varnish has been proposed (see Patent Document 2). However, in the method described in Patent Document 2, since the inorganic particles are not contained in the resin varnish, sufficient curing cannot be achieved.

JP 03-005140 A JP 07-252370 A (see Examples 1-1 and 1-16)

  The present invention uses a prepreg having a low dielectric constant, a low dielectric loss tangent, and a good moldability while realizing a low thermal expansion coefficient and a high elastic modulus in a high temperature environment, and a method for producing the same, and the prepreg. It is an object to provide a laminate.

  In order to solve the above-mentioned problems, the present inventors tried to fill inorganic particles both inside and outside the glass yarn bundle. However, when the average particle size of the inorganic particles is large, the glass particles are not filled with the inorganic particles. On the other hand, it has been found that when the average particle size is small, the viscosity of the resin varnish increases to lower the coatability and increase the melt viscosity of the prepreg. As a result of intensive studies, first, a glass cloth was coated with a solution in which inorganic particles having a small particle size were dispersed, and the surface layer of the glass yarn bundle was filled with inorganic particles. It was found that by impregnating a resin varnish in which larger inorganic particles are dispersed, the filling amount of the inorganic particles can be increased without reducing the coatability of the resin varnish or increasing the melt viscosity of the prepreg. . And based on the said discovery, it came to the invention of the prepreg which has low dielectric constant, low dielectric loss tangent, and favorable moldability, implement | achieving low thermal expansion coefficient and high elastic modulus under high temperature environment.

  That is, the first of the present invention is a prepreg comprising a glass cloth, inorganic particles, and a matrix resin, wherein the inorganic particles are present in the glass yarn bundle constituting the glass cloth, the glass yarn bundle The yarn bundle surface layer inorganic particles existing in the outer surface of the glass yarn bundle surface layer having a thickness of 0.5 to 10 μm, and the yarn bundle outer inorganic particles existing outside the glass yarn bundle surface layer, The inorganic particles have an average particle size of 1 nm or more and 100 nm or less, the inorganic particles outside the yarn bundle have an average particle size of 500 nm or more and 5000 nm or less, and the average particle size of the inorganic particles in the yarn bundle surface layer is the average particle size of the inorganic particles in the yarn bundle The prepreg is characterized in that it is less than the average particle diameter of the inorganic particles outside the yarn bundle. The average particle size of the inorganic particles in the yarn bundle surface is larger than the average particle size of the inorganic particles in the yarn bundle, or the chemical composition and average particle size of the inorganic particles in the yarn bundle surface layer are the chemistry of the inorganic particles in the yarn bundle. The composition and the average particle diameter are preferably the same. Moreover, it is preferable that the glass cloth is composed of a glass yarn bundle having a twist number of 0.2 times / inch or less.

In the second aspect of the present invention, after applying and drying a liquid in which inorganic particles having an average particle size of 1 nm or more and less than 500 nm are dispersed in a glass cloth, a resin varnish containing inorganic particles having an average particle size of 500 nm or more and 5000 nm or less is applied. It is a manufacturing method of the prepreg characterized by the above-mentioned.
A third aspect of the present invention is a laminated board characterized in that one or more prepregs according to the first aspect of the present invention and a metal foil are laminated and molded.

  The laminate of the present invention has the effects of low dielectric constant and low dielectric loss tangent while realizing low thermal expansion coefficient and high elastic modulus under high temperature environment, and the prepreg of the present invention adds to these effects. And has an effect of showing good moldability.

Hereinafter, the present invention will be described in detail.
(1) Glass cloth The glass cloth used for the prepreg of the present invention may be any glass cloth such as E glass, A glass, D glass, S glass, etc., and the composition of the glass is not limited. The weave density of the glass cloth is 10 to 200/25 mm, preferably 15 to 100/25 mm, and more preferably 40 to 80/25 mm. The mass of the glass cloth is 5 to 400 g / m ² , preferably 10 to 300 g / m ² , and glass cloths such as plain weave, satin weave, twill weave, and nanako weave can be used. Moreover, since the glass cloth which uses the thread | yarn whose number of twists is 0.2 times / inch or less (henceforth "non-twisted thread") as a glass thread to comprise can reduce the stress of the twist direction which exists, This is preferable because the effect of reducing warpage can be achieved. As the non-twisted yarn, it is more preferable to use a yarn of 0.1 times / inch or less because the above-described effect is further increased.
Regarding the surface treatment of the glass cloth, a glass cloth at a stage where a sizing agent necessary for weaving is removed, or a glass cloth obtained by treating the glass cloth with a silane coupling agent or the like by a known surface treatment method is preferable. Further, a glass cloth subjected to fiber opening processing by a high-pressure water flow such as a columnar flow or an ultrasonic wave by a high-frequency vibration method in water is also preferable.

(2) Inorganic particles The glass yarn used for the glass cloth for manufacturing a general prepreg is formed by bundling 50 to 1000 single yarns having a diameter of 4 μm to 8 μm to form one glass yarn bundle. Is woven using the glass yarn bundle for warp and weft. The inorganic particles used in the prepreg of the present invention are formed of the inorganic particles in the yarn bundle, the inorganic particles in the yarn bundle, and the inorganic particles outside the yarn bundle depending on the position of the glass yarn constituting the glass cloth or the difference in the average particle diameter. Consider three types.
In the definition of the inside of the glass yarn bundle of the present invention and the outside of the glass yarn bundle, in the cross section of the glass yarn bundle perpendicular to the length direction of the yarn, the single unit present on the outermost side among the plurality of single yarns constituting the glass yarn bundle. In the yarn group, a line obtained by sequentially connecting the common tangents of two adjacent single yarns is referred to as a boundary line 1, the inside of the boundary line 1 is inside the glass yarn bundle, and the outside of the boundary line 1 is outside the glass yarn bundle. To do. When the distance between adjacent outermost single yarn 2A and single yarn 2B is equal to or smaller than the diameter of the single yarn, boundary line 1 connects single yarn 2A and single yarn 2B as they are (see FIG. 1). On the other hand, when the distance 4 between the adjacent outermost single yarn 2A and single yarn 2B is larger than the diameter of the single yarn, the boundary line 1 is the outermost single yarn 2C existing between the single yarn 2A and the single yarn 2B. It is assumed that the single yarn 2A and the single yarn 2B are connected to each other (see FIG. 2).

The inorganic particles in the yarn bundle mean the inorganic particles existing between the single yarns constituting the glass yarn bundle in the glass yarn bundle. The inorganic particles in the yarn bundle may be a mixture of two or more kinds of inorganic particles.
The yarn bundle surface inorganic particles are inorganic particles outside the glass yarn bundle whose average particle diameter is present on the outer part in contact with the boundary line 1 (hereinafter referred to as “yarn bundle surface layer portion”). Inorganic particles smaller than the average particle diameter of The thickness of the yarn bundle surface layer portion is preferably in the range of 0.5 μm to 10 μm from the boundary line 1. The yarn bundle surface layer inorganic particles may be a mixture of two or more inorganic particles.
The above-mentioned inorganic particles in the yarn bundle and the inorganic particles on the surface of the yarn bundle may be inorganic particles having the same average particle size and chemical composition (hereinafter referred to as “same inorganic particles”). It may be inorganic particles having different chemical compositions (hereinafter referred to as “different inorganic particles”). When the inorganic particles are a mixture of the inorganic particles A and the inorganic particles B, the state that the mixing ratio is different between the inorganic particles in the yarn bundle and the inorganic particles in the yarn bundle surface layer also corresponds to the different inorganic particles.

The non-yarn bundle inorganic particles are inorganic particles that are outside the glass yarn bundle and are present outside the above-described yarn bundle surface layer. Since the average particle size of the inorganic particles outside the yarn bundle is 500 nm or more and 5000 nm or less and different from the average particle size of the inorganic particles on the surface of the yarn bundle, the inorganic particles outside the yarn bundle and the inorganic particles outside the yarn bundle are different inorganic particles. Therefore, a boundary line exists between the yarn bundle surface layer inorganic particles and the yarn bundle non-thread inorganic particles (hereinafter referred to as “boundary line 2”). The thickness of the surface portion of the yarn bundle referred to in the present invention is represented by an average value of the distance between the boundary line 2 and the boundary line 1, and the cross section of the glass yarn bundle is exposed by cutting the prepreg embedded in an embedding resin, It is determined by observing the cross section with an electron microscope.
In the present invention, the average particle diameter of the inorganic particles means the average of the diameters of the particles. When the shape of the particles is a solid other than a sphere, such as a rectangular parallelepiped, a cylinder, a fiber, or the like, it means the average of the equivalent volume sphere equivalent diameter which is the diameter of a sphere having the same volume as the solid. Moreover, the average particle diameter in the case of comprising a mixture of two or more kinds of inorganic particles is calculated by the volume average shown in the following formula (i).
Average particle diameter = 1/100 × Σ (Di × Vi) −Formula (i)
Di: average particle diameter of inorganic particles i
Vi: Volume fraction (%) of all inorganic particles i in all inorganic particles

(2a) Inorganic particles in the yarn bundle The inorganic particles in the yarn bundle used for the prepreg of the present invention are preferably inorganic particles having an average particle diameter of 1 nm or more and 100 nm or less. The average particle size of the inorganic particles in the yarn bundle is more preferably 5 nm or more and 80 nm or less, and most preferably 8 nm or more and 70 nm or less. In order to fill the inorganic particles with a sufficient density in the gaps between the single yarns in the glass yarn bundle, the average particle size needs to be less than 100 nm. Further, when the average particle size is smaller than 1 nm, the surface area becomes too large, and there is a possibility that poor impregnation of the matrix resin may occur at the time of preparing the prepreg.
As the above-mentioned inorganic particles, inorganic particles made of an inorganic oxide are preferable, and examples include silicon dioxide such as titanium oxide and amorphous silica, alumina, zinc oxide, colloidal silica obtained by growing metal alkoxide by a sol-gel method, alumina sol, and the like. The
In particular, as the inorganic particles in the yarn bundle, inorganic particles containing an inorganic oxide having an equilibrium moisture content of 5% by mass or less, more preferably 3% by mass or less, of 80% by mass or more, more preferably 90% by mass or more, It is preferable at the point which can obtain the laminated board which is excellent in a characteristic. The equilibrium moisture content referred to here is the drying at the time of drying for 2 hours at 110 ° C. according to JISK5101 after curing for 48 hours under conditions of 23 ° C. and 65% relative humidity. Indicates the weight loss rate.

As the inorganic oxide having an equilibrium moisture content of 5% by mass or less, titanium oxide, silicon dioxide, alumina, zinc oxide or the like obtained by a method of firing sol-gel particles or a method of self-combusting metal powder in an oxidizing gas stream is preferable. . Since the colloidal silica described above has a hydrophilic silanol group, the equilibrium moisture content is increased, and as a result, the dielectric loss tangent may be increased. Therefore, by firing at about 400 ° C., the silanol group is reduced to reduce the equilibrium moisture content. It is more preferable to use a reduced one. In particular, it is possible to stably produce a prepreg by using inorganic particles in a yarn bundle containing 80% by mass or more, more preferably 90% by mass or more of titanium oxide in which fine particles of 100 nm or less are industrially stably produced. Therefore, it is more preferable. The form of titanium oxide that can be used in the present invention is not limited, but chemically stable rutile titanium oxide is preferable, and titanium oxide surface-coated with silica, alumina or the like is more preferable in order to improve stability. .
The inorganic particles in the yarn bundle may be subjected to a surface treatment with a silane coupling agent, a titanate coupling agent or the like in order to improve compatibility with the matrix resin and adhesion.

(2b) Yarn bundle surface layer inorganic particles Yarn bundle surface layer inorganic particles used in the prepreg of the present invention have an average particle size equal to or larger than the average particle size of the inorganic particles in the yarn bundle and smaller than the average particle size of the inorganic particles outside the yarn bundle. It is. The average particle diameter of the yarn bundle surface layer inorganic particles is preferably 1 nm or more and less than 500 nm, more preferably 50 nm or more and less than 400 nm, and most preferably 80 nm or more and less than 300 nm. By making the average particle size of the inorganic particles on the surface of the yarn bundle smaller than the average particle size of the inorganic particles outside the yarn bundle, the inorganic particles can be filled with high density by the unevenness of the surface layer of the glass yarn bundle. In particular, the average particle diameter is preferably less than 500 nm in order to fill the surface layer of the glass fiber bundle having irregularities formed from single yarns having a diameter of 4 μm to 8 μm with sufficient density. Further, when the average particle size is smaller than 1 nm, the surface area becomes too large, and there is a possibility that poor impregnation of the matrix resin may occur at the time of preparing the prepreg.

When the yarn bundle surface layer inorganic particles are different from the inorganic particles in the yarn bundle, by setting the average particle diameter of the yarn bundle surface inorganic particles to be larger within the above range, the glass yarn bundle The improvement of the packing density of the inorganic particles into the inside and the improvement of the matrix resin impregnation property can be made compatible, which is preferable. On the other hand, when the yarn bundle surface layer inorganic particles are the same inorganic particles as the yarn bundle inorganic particles, both inorganic particles can be applied at once, which is preferable because the production method can be simplified.
Further, the thickness of the yarn bundle surface layer portion where the yarn bundle surface layer inorganic particles are present needs to be set depending on the thickness of the glass cloth used and the thickness of the prepreg to be prepared. In order to ensure the fluidity of the matrix resin and maintain the moldability, the thickness of the yarn bundle surface layer is preferably 0.5 to 10 μm, more preferably 1 to 8 μm, and most preferably 2 to 6 μm.

As the yarn bundle surface layer inorganic particles, inorganic oxides are preferable like the inorganic particles in the yarn bundle, silicon dioxide such as titanium oxide and amorphous silica, alumina, zinc oxide, colloidal silica obtained by growing metal alkoxide by a sol-gel method, An alumina sol etc. are illustrated. In particular, the inorganic particles containing 50% by mass or more, more preferably 70% by mass or more of silicon dioxide having an equilibrium moisture content of 5% by mass or less, more preferably 3% by mass or less are used as the yarn bundle surface layer inorganic particles. It is preferable at the point which gives the laminated board which is excellent in.
The yarn bundle surface layer inorganic particles may be subjected to surface treatment with a silane coupling agent, a titanate coupling agent or the like in order to improve compatibility with the matrix resin and adhesion.

(2c) Inorganic particles outside the yarn bundle The inorganic particles outside the yarn bundle used for the prepreg of the present invention are inorganic particles having an average particle diameter of 500 nm or more and 5000 nm or less. As will be described later in the prepreg production, inorganic particles outside the yarn bundle are dispersed in a resin varnish and impregnated into a glass cloth. Therefore, it is necessary not to disturb the heat melting and fluidity of the resin varnish in order to ensure the adhesiveness at the time of lamination molding and the filling property between the wiring patterns in the case of a multilayer substrate. The influence of the inorganic particles on the melt viscosity of the matrix resin varies depending on the chemical composition and shape, but the average particle size is 500 nm or more, preferably 750 nm or more, more preferably 1000 nm or more in order to increase the melt viscosity as the particle size decreases. It is. Moreover, since the surface smoothness of a board | substrate and the filling property to a wiring pattern fall, so that a particle diameter is small, an average particle diameter is 5000 nm or less, Preferably it is 4000 nm or less, More preferably, it is 3000 nm or less.

Examples of inorganic particles outside the yarn bundle include inorganic oxide particles such as silicon dioxide such as titanium oxide and amorphous silica, alumina and zinc oxide, colloidal silica obtained by growing metal alkoxide by a sol-gel method, and alumina sol, talc and mica. Inorganic particles obtained by pulverizing minerals such as wollastonite and inorganic hydroxide particles such as aluminum hydroxide and magnesium hydroxide can be preferably used. In particular, as inorganic particles outside the yarn bundle, inorganic particles containing 50% by mass or more, more preferably 70% by mass or more of silicon dioxide having an equilibrium moisture content of 5% by mass or less, more preferably 3% by mass or less are electrical characteristics. It is preferable at the point from which the laminated board which is excellent in is obtained.
In addition, the inorganic particles outside the yarn bundle may be subjected to a surface treatment with a silane coupling agent, a titanate coupling agent or the like in order to improve compatibility with the matrix resin and adhesion.

(3) Matrix resin As the matrix resin used in the present invention, either a thermosetting resin or a thermoplastic resin can be used. As a thermosetting resin, a) a compound having an epoxy group and a compound having an amino group, a phenol group, an acid anhydride group, a hydrazide group, an isocyanate group, a cyanate group, a hydroxyl group, etc. that react with the epoxy group Or an epoxy resin to be cured by adding a catalyst having a reaction catalytic ability such as an imidazole compound, a tertiary amine compound, a urea compound, or a phosphorus compound, and b) a compound having an allyl group, a methacryl group, or an acrylic group A radical polymerization type curable resin that is cured using a thermal decomposition catalyst or a photodecomposition type catalyst as a reaction initiator, and c) a maleimide triazine that is cured by reacting a compound having a cyanate group with a compound having a maleimide group Resin, d) thermosetting polyimide resin that cures by reacting maleimide compound and amine compound, e) Benzoxazine resin to crosslink cured by thermal polymerization of a compound having a Zookisajin ring are exemplified.

Examples of the thermoplastic resin include polyphenylene ether, modified polyphenylene ether, polyphenylene sulfide, polysulfone, polyether sulfone, polyarylate, aromatic polyamide, polyether ether ketone, thermoplastic polyimide, insoluble polyimide, polyamideimide, and fluororesin. Illustrated. Moreover, you may use together a thermosetting resin and a thermoplastic resin.
A resin varnish is prepared by dissolving the matrix resin described above in an organic solvent. As the organic solvent, toluene, xylene, acetone, 2-butanone, 2-methoxyethanol, N, N-dimethylformamide, N, N-dimethylacetamide and the like can be preferably used.

(4) Prepreg production In the method for producing a prepreg of the present invention, first, an inorganic particle-filled glass cloth in which inorganic particles are applied to the inside of the glass yarn bundle constituting the glass cloth and the surface portion of the glass yarn bundle is prepared. As a method for applying inorganic particles to glass cloth, a dispersion liquid in which the inorganic particles are dispersed in water or an organic solvent (hereinafter referred to as “inorganic particle dispersion liquid”) is prepared, and A) the inorganic particle dispersion liquid. After the glass cloth is passed through the bath, the glass cloth is squeezed with a slit or mangle so that a predetermined amount of the inorganic particle dispersion is applied to the glass cloth and adhered to the surface of the glass yarn bundle. Removing the excess inorganic particle dispersion and obtaining a certain amount of treatment liquid coating, or B) applying a certain amount of inorganic particle dispersion directly to the glass cloth while pressing with a roll coater, die coater, gravure coater, etc. A method of coating (hereinafter, both A and B methods are simply referred to as “impregnation”) can be preferably used.

In producing an inorganic particle-filled glass cloth in which the inorganic particles in the yarn bundle surface layer and the inorganic particles in the yarn bundle are the same kind of inorganic particles, an inorganic particle dispersion in which inorganic particles having an average particle diameter of 1 nm to 100 nm are dispersed in the glass cloth. A method of coating the yarn bundle surface layer inorganic particles and the yarn bundle inorganic particles by coating and drying the liquid is preferred. In order to increase the thickness of the surface layer of the glass yarn bundle, the same inorganic particle dispersion may be applied twice or more within a range in which the thickness does not exceed 10 μm.
On the other hand, when producing an inorganic particle-filled glass cloth in which the average particle size of the inorganic particles in the yarn bundle surface layer is larger than the average particle size of the inorganic particles in the yarn bundle, the inorganic particle dispersion having a small particle size mainly serving as the inorganic particles in the yarn bundle After applying the liquid, a method of applying an inorganic particle dispersion liquid having a slightly larger particle diameter, which mainly becomes the yarn bundle surface layer inorganic particles, can be used. Further, by utilizing the fact that the glass cloth itself acts as a particle sieve, the average particle diameter is 1 nm or more and 100 nm or less, the average particle diameter is 1 nm or more and less than 500 nm, and the average particle diameter of the inorganic particles A is A method of applying the inorganic particles in the yarn bundle and the inorganic particles on the surface of the yarn bundle at a time using the inorganic particle dispersion mixed with the large inorganic particles B can also be used. The latter method is preferable because it has the advantage of being applied only once.

The amount of inorganic particles attached to the inorganic particle-filled glass cloth is preferably about 3 to 30% by mass, although it depends on the type of glass cloth.
Next, as a method for producing a prepreg from an inorganic particle-filled adhered glass cloth, a resin varnish mixed with inorganic particles outside the yarn bundle (hereinafter referred to as “inorganic particle dispersion varnish”) is accumulated in a bath, and an inorganic material is contained in the bath. After passing through the particle-filled adhering glass cloth, a method of making a constant thickness with a slit or mangle can be preferably used (hereinafter referred to as “coating”).
The weight ratio of the inorganic particles to the matrix resin component in the inorganic particle-dispersed varnish is preferably 30 to 80%, more preferably 40 to 75%. At this time, the inorganic particle-filled adhered glass cloth is preferably dried once after coating the inorganic particle dispersion and then impregnated into the inorganic particle dispersion varnish, but the solvent of the inorganic particle dispersion is compatible with the inorganic particle dispersion varnish. In the case of the organic solvent to be used, the inorganic particle-dispersed varnish may be directly impregnated without drying.

Finally, the organic solvent of the inorganic particle-dispersed varnish is heated and dried to be B-staged to produce a prepreg. The B-stage is preferably performed under conditions of 90 to 200 ° C. and 30 seconds to 5 minutes.
In addition, it is also possible to remove the water | moisture content and hydroxyl group of an inorganic oxide by heating said inorganic particle filling adhesion glass cloth with the temperature of 100 to 1000 degreeC with a batch-type heating apparatus or a continuous heating apparatus. . In addition, before impregnating the inorganic particle-filled glass cloth with the inorganic particle-dispersed varnish, it is possible to surface-treat with a silane coupling agent, a titanate coupling agent, or the like. As a surface treatment method of this coupling agent, a wet method in which a liquid in which a coupling agent is dispersed or dissolved in water (hereinafter referred to as “surface treatment liquid”) is applied and dried, or is dispersed or dissolved in an organic solvent. A surface treatment method such as a dry method in which the applied liquid is applied and dried, a coupling agent alone, or a gas phase method in which the treatment is performed in a sprayed or vaporized atmosphere with a solvent and a dispersion is possible.

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples.
(Glass cloth)
Glass cloth A: Style 1037 glass cloth from which weaving sizing agent is removed by an incineration method (manufactured by Asahi Schwer, glass type: E glass, single yarn diameter: 4 μm, number of single yarns constituting yarn: 100, weaving method : Plain weave, weave density: warp 70 / inch, width 73 / inch, yarn twist number: 1 turn / inch, weight 28.0 g / m ² , volume 11.0 cm ³ / m ² ) .
Glass cloth B: A glass cloth obtained by subjecting the above-described glass cloth A to a surface treatment with a silane coupling agent was used.
Glass cloth C: Style 1116 glass cloth from which weaving sizing agent is removed by incineration method (Asahi Sebel Inc., glass type: E glass, single yarn diameter: 5 μm, number of single yarns constituting yarn: 400, weaving method : Plain weave, weave density: vertical 60 pieces / inch, width 58 pieces / inch, yarn twist number: 1 turn / inch, weight 104.2 g / m ² , volume amount: 41.0 cm ³ / m ² ) .
Glass cloth D: The same glass cloth as the glass cloth C was used except that weaving was performed using a non-twisted yarn having a yarn twist number of 0.1 times / inch.

(Inorganic particle dispersion)
Inorganic particle dispersion A: A colloidal silica 20% by mass aqueous dispersion (PL-3 manufactured by Fuso Chemical Co., Ltd.) having an equilibrium moisture content of 6% and an average particle diameter of 30 nm was prepared. It was confirmed that the equilibrium moisture content was 4% by heating the colloidal silica at 400 ° C. for 10 hours.
Inorganic particle dispersion B: A silicon dioxide surface-treated titanium oxide (STR100W, manufactured by Sakai Chemical Industry Co., Ltd.) having an equilibrium moisture content of 2% and an average particle diameter of 10 nm was prepared in an amount of 25% by mass.
Inorganic particle dispersion C: amorphous silicon dioxide (hereinafter referred to as “calcined amorphous silica”) prepared by a firing method having an average particle size of 300 nm (SP-0.3B manufactured by Fuso Chemical Co., Ltd.) 25% by mass aqueous dispersion It was created.
Inorganic particle dispersion D: A surface-protective titanium oxide (R9020 manufactured by Ishihara Sangyo Co., Ltd.) 25 mass% aqueous dispersion having an average particle diameter of 200 nm was prepared.
Inorganic particle dispersion E: A fired amorphous silica (SP-4B manufactured by Fuso Chemical Co., Ltd.) 25 mass% aqueous dispersion having an average particle diameter of 4 μm was prepared.

(Matrix resin)
Matrix resin A: Tetraglycidyldiaminodiphenylmethane (trade name Epicoat 604, manufactured by Japan Epoxy Resin Co., Ltd.) 25.0 mass%, bisphenol A type epoxy resin (trade name Epicoat 1001, manufactured by Japan Epoxy Resins Co., Ltd.) 25.0 mass% , High bromine bisphenol A type epoxy resin (trade name Epicoat 5050, manufactured by Japan Epoxy Resin Co., Ltd.) 46.9% by mass, dicyandiamide 3.0% by mass, 2-ethyl-4-methylimidazole 0.1% by mass The composition was adjusted.
Matrix resin B: triallyl isocyanurate (registered trademark TAIC, Nippon Kasei Co., Ltd.) 20.0 mass%, orthodiallyl phthalate prepolymer (registered trademark Daiso DAP, Daiso Corporation) 65.0 mass%, decabromodiphenyl A resin composition comprising 10.0% by mass of ethane and 5.0% by mass of 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane (registered trademark Perhexa 25B, manufactured by NOF Corporation) was prepared. did.

(Organic solvent)
Organic solvent A: An organic solvent comprising 40.0 parts by mass of N, N-dimethylformamide, 40.0 parts by mass of 2-methoxyethanol, and 20.0 parts by mass of 2-butanone was prepared.
Organic solvent B: An organic solvent comprising 20.0 parts by mass of toluene, 20.0 parts by mass of acetone, and 60.0 parts by mass of 2-butanone was prepared.

(Inorganic particle dispersion varnish)
Inorganic particle-dispersed varnish A: A resin solution of 20% by mass of matrix resin A, 50% by mass of organic solvent A, and 30% by mass of calcined amorphous silica (SP-4B manufactured by Fuso Chemical Co., Ltd.) having an average particle diameter of 4 μm was prepared.
Inorganic particle-dispersed varnish B: A resin solution of 20% by mass of matrix resin B, 50% by mass of organic solvent B, and 30% by mass of calcined amorphous silica (SP-4B manufactured by Fuso Chemical Co., Ltd.) having an average particle size of 4 μm was prepared.
Inorganic particle-dispersed varnish C: A resin solution of 20% by mass of matrix resin A, 50% by mass of organic solvent A, and 30% by mass of calcined talc (BST manufactured by Nippon Talc Co., Ltd.) having an average particle diameter of 4 μm was prepared.
Inorganic particle-dispersed varnish D: A resin solution of 15.4% by mass of matrix resin A, 50% by mass of organic solvent A, and 44.6% of calcined amorphous silica (SP-4B, manufactured by Fuso Chemical Co., Ltd.) was prepared.
Inorganic particle-dispersed varnish E: A resin solution of 12.5% by mass of matrix resin A, 50% by mass of organic solvent A, and 32.5% by mass of calcined amorphous silica (SP-4B manufactured by Fuso Chemical Co., Ltd.) having an average particle size of 4 μm was prepared.
Inorganic particle-dispersed varnish F: 20% by mass of matrix resin A, 50% by mass of organic solvent A, and 30% by mass of Aerosil-type silicon dioxide (hereinafter referred to as “Aerosil-type silica”) having an average particle size of 30 nm A resin solution was prepared.
Inorganic particle-dispersed varnish G: A resin solution of 20% by mass of matrix resin A, 50% by mass of organic solvent A, and 30% by mass of calcined amorphous silica (SP-25B manufactured by Fuso Chemical Co., Ltd.) having an average particle size of 25 μm was prepared.

(Surface treatment liquid)
Surface treatment liquid A: A silane coupling agent solution containing 80% by mass of ethanol, 10% by mass of epoxy silane (SH6040 manufactured by Toray Dow Corning Co., Ltd.) and 10% by mass of distilled water was prepared.
Surface treatment liquid B: A silane coupling agent solution containing 80% by mass of ethanol, 10% by mass of methacrylsilane (SZ6030 manufactured by Toray Dow Corning Co., Ltd.) and 10% by mass of distilled water was prepared.

<Example 1>
After impregnating the glass cloth A with the inorganic particle dispersion A and drying to produce a glass cloth having 3.25 g / m ² of colloidal silica having an average particle diameter of 30 nm attached thereto, the glass cloth A is impregnated with the inorganic particle dispersion C. It dried and produced the inorganic particle filling adhesion glass cloth which made 12.50 g / m < ² > adhere the baking amorphous silica whose average particle diameter is 300 nm. After the surface treatment liquid A is applied to the inorganic particle-filled glass cloth and dried, the inorganic particle-dispersed varnish A is applied to form a B stage, and the matrix resin and the calcined amorphous silica having an average particle diameter of 4 μm are added. Thus, a prepreg having a thickness of 50 μm adhered to 52.55 g / m ² was obtained.

<Example 2>
After impregnating the glass cloth A with the inorganic particle dispersion A and drying to produce a glass cloth having 3.25 g / m ² of colloidal silica having an average particle diameter of 30 nm attached thereto, the glass cloth A is impregnated with the inorganic particle dispersion C. It dried and produced the inorganic particle filling adhesion glass cloth which made 12.50 g / m < ² > adhere the baking amorphous silica whose average particle diameter is 300 nm. The inorganic particle-filled adhering glass cloth is heated in an oven at 400 ° C. for 24 hours to bring the equilibrium moisture content of the colloidal silica to 4% by mass, cooled, coated with the surface treatment liquid A and dried, and then inorganic particle-dispersed varnish. A was applied to form a B stage to obtain a prepreg having a thickness of 50 μm to which a total of 52.55 g / m ^{2 of} a matrix resin and a fired amorphous silica having an average particle diameter of 4 μm adhered.

<Example 3>
Glass cloth A is impregnated with inorganic particle dispersion B and dried to form glass cloth with 5.76 g / m ^{2 of} titanium oxide having an average particle diameter of 10 nm adhered, and then impregnated with inorganic particle dispersion C. It dried and produced the inorganic particle filling adhesion glass cloth which made 12.50 g / m < ² > adhere the baking amorphous silica whose average particle diameter is 300 nm. After the surface treatment liquid A is applied to the inorganic particle-filled glass cloth and dried, the inorganic particle-dispersed varnish A is applied to form a B stage, and the matrix resin and the calcined amorphous silica having an average particle diameter of 4 μm are added. Thus, a prepreg having a thickness of 50 μm adhered to 52.55 g / m ² was obtained.

<Example 4>
The glass cloth B was impregnated with the inorganic particle dispersion B and dried to prepare a glass cloth having 5.76 g / m ^{2 of} titanium oxide having an average particle diameter of 10 nm adhered thereto, and then impregnated with the inorganic particle dispersion C. It dried and produced the inorganic particle filling adhesion glass cloth which made 12.50 g / m < ² > adhere the baking amorphous silica whose average particle diameter is 300 nm. After the surface treatment liquid A is applied to the inorganic particle-filled glass cloth and dried, the inorganic particle-dispersed varnish A is applied to form a B stage, and the matrix resin and the calcined amorphous silica having an average particle diameter of 4 μm are added. Thus, a prepreg having a thickness of 50 μm adhered to 52.55 g / m ² was obtained.

<Example 5>
Glass cloth A was impregnated with inorganic particle dispersion B and dried to prepare glass cloth with 5.76 g / m ^{2 of} titanium oxide having an average particle diameter of 10 nm adhered, and then impregnated with inorganic particle dispersion D. It dried and produced the inorganic particle filling adhesion | attachment glass cloth which adhered 22.16 g / m < ² > of the titanium oxide with an average particle diameter of 200 nm. After the surface treatment liquid A is applied to the inorganic particle-filled glass cloth and dried, the inorganic particle-dispersed varnish A is applied to form a B stage, and the matrix resin and the calcined amorphous silica having an average particle diameter of 4 μm are added. Thus, a prepreg having a thickness of 50 μm adhered to 52.55 g / m ² was obtained.

<Example 6>
Glass cloth A is impregnated with an inorganic particle dispersion liquid in which inorganic particle dispersion liquid B and inorganic particle dispersion liquid C are mixed at a mass ratio of 43:57 and dried, and titanium oxide having an average particle diameter of 10 nm; An inorganic particle-filled glass cloth having a total of 18.26 g / m ² of calcined amorphous silica with an average particle diameter of 300 nm was prepared. After the surface treatment liquid A is applied to the inorganic particle-filled adhered glass cloth and dried, the inorganic particle-dispersed varnish B is applied to form a B stage, and the matrix resin and the calcined amorphous silica having an average particle diameter of 4 μm are added. Thus, a prepreg having a thickness of 50 μm adhered to 52.55 g / m ² was obtained.

<Example 7>
Glass cloth A is impregnated with an inorganic particle dispersion liquid in which inorganic particle dispersion liquid B and inorganic particle dispersion liquid C are mixed at a mass ratio of 43:57 and dried, and titanium oxide having an average particle diameter of 10 nm; An inorganic particle-filled glass cloth having a total of 18.26 g / m ² of calcined amorphous silica with an average particle diameter of 300 nm was prepared. After the surface treatment liquid B is applied to the inorganic particle filled glass cloth and dried, the inorganic particle-dispersed varnish A is applied to form a B stage, and the matrix resin and the calcined amorphous silica having an average particle diameter of 4 μm are added. Thus, a prepreg having a thickness of 50 μm adhered to 52.55 g / m ² was obtained.

<Example 8>
Glass cloth A is impregnated with inorganic particle dispersion B and dried to form glass cloth with 5.76 g / m ^{2 of} titanium oxide having an average particle diameter of 10 nm adhered, and then impregnated with inorganic particle dispersion C. It dried and produced the inorganic particle filling adhesion glass cloth which made 12.50 g / m < ² > adhere the baking amorphous silica whose average particle diameter is 300 nm. After the surface treatment liquid A is applied to the inorganic particle-filled adhered glass cloth and dried, the inorganic particle-dispersed varnish C is applied to form a B-stage, and the matrix resin and the calcined talc having an average particle diameter of 4 μm are combined. A prepreg having a thickness of 50 μm adhered to 66.45 g / m ² was obtained.

<Example 9>
The glass cloth C was impregnated with the inorganic particle dispersion B and dried to prepare an inorganic particle-filled glass cloth in which 10.80 g / m ^{2 of} titanium oxide having an average particle diameter of 10 nm was adhered. After the surface treatment liquid A is applied to the inorganic particle-filled glass cloth and dried, the inorganic particle-dispersed varnish A is applied to form a B stage, and the matrix resin and the calcined amorphous silica having an average particle diameter of 4 μm are added. A prepreg having a thickness of 100 μm and 92.80 g / m ² was obtained.

<Example 10>
The glass cloth D was impregnated with the inorganic particle dispersion B and dried to prepare an inorganic particle-filled glass cloth in which 10.80 g / m ^{2 of} titanium oxide having an average particle diameter of 10 nm was adhered. After the surface treatment liquid A is applied to the inorganic particle-filled glass cloth and dried, the inorganic particle-dispersed varnish A is applied to form a B stage, and the matrix resin and the calcined amorphous silica having an average particle diameter of 4 μm are added. A prepreg having a thickness of 100 μm and 92.80 g / m ² was obtained.

<Comparative Example 1>
A glass cloth B was coated with an inorganic particle-dispersed varnish D to form a B stage to obtain a 50 μm thick prepreg in which a total of 68.30 g / m ^{2 of} a matrix resin and amorphous silica having an average particle diameter of 4 μm adhered. .
<Comparative example 2>
The glass cloth A was impregnated with the inorganic particle dispersion C and dried to prepare an inorganic particle-filled attached glass cloth in which 15.75 g / m ² of fired amorphous silica having an average particle diameter of 300 nm was adhered. After the surface treatment liquid A is applied to the inorganic particle-filled glass cloth and dried, the inorganic particle-dispersed varnish A is applied to form a B stage, and the matrix resin and the calcined amorphous silica having an average particle diameter of 4 μm are added. Thus, a prepreg having a thickness of 50 μm adhered to 52.55 g / m ² was obtained.

<Comparative Example 3>
Glass cloth A was impregnated with inorganic particle dispersion B and dried to form glass cloth with 5.76 g / m ^{2 of} titanium oxide having an average particle diameter of 10 nm adhered, and then impregnated with inorganic particle dispersion E. It dried and produced the inorganic particle filling adhesion glass cloth which adhered 5.00 g / m < ² > of the baking amorphous silica whose average particle diameter is 4 micrometers. After the surface treatment liquid A is applied to the inorganic particle-filled glass cloth and dried, the inorganic particle-dispersed varnish E is applied to form a B stage, and the matrix resin and the calcined amorphous silica having an average particle diameter of 4 μm are combined. Thus, a prepreg having a thickness of 50 μm adhered to 39.05 g / m ² was obtained.

<Comparative example 4>
Glass cloth A is impregnated with inorganic particle dispersion B and dried to form glass cloth with 5.76 g / m ^{2 of} titanium oxide having an average particle diameter of 10 nm adhered, and then impregnated with inorganic particle dispersion C. It dried and produced the inorganic particle filling adhesion glass cloth which made 12.50 g / m < ² > adhere the baking amorphous silica whose average particle diameter is 300 nm. After the surface treatment liquid A is applied to the inorganic particle-filled adhered glass cloth and dried, the inorganic particle-dispersed varnish F is applied to form a B stage, and the matrix resin and the aerosil-type silica having an average particle diameter of 30 nm are combined. Thus, a prepreg having a thickness of 50 μm adhered to 52.55 g / m ² was obtained.

<Comparative Example 5>
Glass cloth A is impregnated with inorganic particle dispersion B and dried to form glass cloth with 5.76 g / m ^{2 of} titanium oxide having an average particle diameter of 10 nm adhered, and then impregnated with inorganic particle dispersion C. It dried and produced the inorganic particle filling adhesion glass cloth which made 12.50 g / m < ² > adhere the baking amorphous silica whose average particle diameter is 300 nm. After the surface treatment liquid A is applied to the inorganic particle-filled adhered glass cloth and dried, the inorganic particle-dispersed varnish G is applied to form a B stage, and the matrix resin and the calcined amorphous silica having an average particle diameter of 25 μm are added. Thus, a prepreg having a thickness of 50 μm adhered to 52.55 g / m ² was obtained.
<Comparative Example 6>
After the surface treatment liquid A is applied to glass cloth C and dried, inorganic particle-dispersed varnish D is applied to form a B stage, and a total of 100.51 g of matrix resin and calcined amorphous silica having an average particle diameter of 4 μm. A prepreg having a thickness of 100 μm adhered to / m ² was obtained.

(Preparation of observation substrate)
One piece of the prepreg prepared in Examples and Comparative Examples was molded under heat and pressure at a rate of temperature increase from room temperature to 180 ° C. at 5 ° C./minute, and then at 180 ° C. for 120 minutes under a pressure of 4 G · Pa. An observation substrate was prepared.
(Laminate creation)
Twenty prepregs created in Examples and Comparative Examples are sandwiched between two 12 μm thick copper foils with a size of 20 cm square, and the temperature is raised from room temperature to 180 ° C. under a pressure of 10 G · Pa. A laminate was prepared by heating and pressing at a rate of 10 ° C./minute and then at 180 ° C. for 120 minutes.
(Observation of arrangement of inorganic particles in prepreg)
The cross section of the substrate for observation was observed with an electron microscope (magnification: 500 times), a) confirmation of the presence or absence of the arrangement of inorganic particles in the glass yarn bundle, and b) the thickness of the surface portion of the glass yarn bundle.

(Evaluation of number of voids in prepreg)
The substrate for observation was cut in a cross section perpendicular to the glass cross warp direction, the width of the weft direction was 1 cm x the thickness of the glass cloth was observed with an electron microscope (magnification: 500 times), and the number of voids in the range Was measured.
(Evaluation of melt viscosity of prepreg)
In the state where 10 prepregs were stacked, the viscosity was measured with RDAII (manufactured by Rheometrics Co., Ltd.) at a temperature rising rate of 10 ° C./min, and the minimum value was determined.
(Surface defect evaluation of laminates)
The surface of the laminate was visually observed, the number of locations where the copper foil was torn and the resin was flowing out on the surface of the copper foil was counted, and the number of both front and back surfaces was summed).

(Measurement of thermal expansion coefficient of laminate)
The copper foil of the laminated plate was removed by etching, washed with water, and then heated and dried at 200 ° C. for 3 hours in a nitrogen atmosphere using a thermomechanical analyzer (TMASS6000, manufactured by Seiko Instruments Inc.) at 10 ° C. The coefficient of thermal expansion in the thickness direction at 100 ° C. was measured at a heating rate of 10 min / min under conditions of 10 mN terminal load.
(Measurement of dielectric loss tangent of laminate)
After removing the copper foil of the laminated plate by etching, washing with water, and using a impedance analyzer (HP4291B, manufactured by Hewlett-Packard Japan) for the sample heat-dried at 200 ° C. for 3 hours in a nitrogen atmosphere, the dielectric loss tangent is obtained. It was measured.

(Measurement of warp measurement laminate)
Two prepregs created in Examples and Comparative Examples are sandwiched between two 12 μm thick copper foils with a size of 20 cm square, and the temperature is raised from room temperature to 180 ° C. under a pressure of 10 G · Pa. A laminate for warpage measurement was prepared by heating and pressing at a rate of 10 ° C./min and then at 180 ° C. for 120 minutes. The copper foil of the warp measurement laminate was removed by etching, washed with water, cut into 5 cm squares, and immersed in 260 ° C. molten solder for 20 seconds three times to measure the amount of warpage of the plate. . The amount of warpage was determined by placing a laminated plate on a surface plate and measuring the height of the four corners of the plate floating from the surface plate with a ruler.

Tables 1 to 3 show the evaluation results of the prepregs and laminates prepared in Examples 1 to 10 and Comparative Examples 1 to 6.
As is clear from Table 1, the prepregs of the present invention obtained in Examples 1 to 10 exhibit good characteristics.
On the other hand, Comparative Example 1 is a prepreg in which the yarn bundle inorganic particles and the yarn bundle surface inorganic particles are not arranged, and is a conventional prepreg for a low thermal expansion substrate that is generally produced. If an attempt is made to fill the prepreg of Comparative Example 1 with an amount of inorganic particles equivalent to that of Example 1, the density of the inorganic particles outside the yarn bundle must be increased. For this reason, the melt viscosity of the prepreg was high.
In addition, when inorganic particles are present in the yarn bundle as in the example, the space is small and the resin component efficiently enters by capillary action, but in the case of Comparative Example 1, the capillary phenomenon is difficult to work, and the resin is in this space. It became difficult to be filled with ingredients.
For the above reason, voids were generated in the glass yarn bundle in the observation substrate of Comparative Example 1.
And since only the resin component entered into the voids in the yarn bundle, the density of inorganic particles outside the yarn bundle further increased, and the melt viscosity became as high as 8000 Pa · s.
On the other hand, inorganic particles are not present in the space inside the yarn bundle, and the larger thermal expansion of the filled resin component has a strong influence, and the thermal expansion coefficient of the produced laminate is as large as 35 ppm / ° C. .

Comparative Example 2 was a prepreg in which the inorganic particles in the yarn bundle were not arranged, and the same phenomenon as Comparative Example 1 was observed. Specifically, as shown in Table 2, in the observation substrate prepared from the prepreg of Comparative Example 2, voids were generated in the glass yarn bundle. Further, the melt viscosity of the prepreg of Comparative Example 2 was as high as 7000 Pa · s, and the thermal expansion coefficient of the prepared laminate was as high as 30 ppm / ° C.
Comparative example 3 is a prepreg in which the yarn bundle surface layer inorganic particles and the yarn bundle outer inorganic particles have the same particle diameter (4 μm).
In Comparative Example 3, since the space of the inorganic particles on the surface of the yarn bundle is large and the space needs to be filled with the resin component, the observation substrate made from the prepreg of Comparative Example 3 as shown in Table 2 is Voids were generated outside the glass yarn bundle.
Further, since a resin was required in the space of the yarn bundle surface layer inorganic particles, the density of inorganic particles outside the yarn bundle increased, and the melt viscosity of the prepreg of Comparative Example 3 was as high as 7500 Pa · s.
Comparative Example 4 is a prepreg in which inorganic particles outside the yarn bundle having an average particle diameter of 30 nm are arranged. The smaller the particle size, the higher the resin varnish viscosity and the prepreg viscosity. For this reason, the resin component was hardly filled in the yarn bundle, and as shown in Table 2, the observation substrate made from the prepreg of Comparative Example 4 had voids in the glass yarn bundle. The melt viscosity of the prepreg of Comparative Example 4 was as high as 9000 Pa · s.

Comparative Example 5 is a prepreg in which inorganic particles outside the yarn bundle having an average particle diameter of 25 μm are arranged. When the particles outside the yarn bundle are large, the space between the particles becomes large, and bubbles due to solvent drying or the like in the preparation of the prepreg tend to remain between the particles. As shown in Table 2, the observation made from the prepreg of this comparative example 5 The substrate for the substrate had voids outside the glass yarn bundle, and had many surface defects that were thought to be caused by the copper foil being broken by inorganic particles having a particle diameter larger than the thickness of the copper foil.
Comparative Example 6, like the prepreg of Comparative Example 1, is a prepreg in which the inorganic particles in the yarn bundle and the inorganic particles in the surface of the yarn bundle are not disposed, and is equivalent to a conventional prepreg for a low thermal expansion substrate that is generally produced. The same phenomenon as in Comparative Example 1 was observed. Specifically, as shown in Table 2, in the observation substrate prepared from the prepreg of Comparative Example 6, voids were generated in the glass yarn bundle. Further, the melt viscosity was as high as 7500 Pa · s, and the thermal expansion coefficient of the prepared laminate was slightly high at 22 ppm / ° C.
In addition, as shown in Table 3, when a glass cloth using untwisted yarn was used as the glass cloth used in the prepreg of the present invention, it was possible to obtain a laminate with less warping.

  The prepreg and laminate of the present invention can be suitably used in the field of printed wiring boards.

It is a schematic diagram of the one aspect | mode of the cross section of the glass yarn bundle for demonstrating the boundary line 1. FIG. It is a schematic diagram of another aspect of the cross section of the glass yarn bundle for demonstrating the boundary line 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Glass yarn bundle 2 Single yarn 2A Outermost single yarn 2B Outermost single yarn 2C Single yarn 2C which adjoins 2A Single yarn 2A and outermost single yarn 3 which exists between single yarn 2B Boundary line 1
4 Distance between adjacent outermost single yarn 2A and single yarn 2B

Claims (6)

  A prepreg composed of a glass cloth, inorganic particles, and a matrix resin, wherein the inorganic particles are present in the glass yarn bundles constituting the glass cloth, outside the glass yarn bundles and 0.5 to It consists of yarn bundle surface inorganic particles existing in the surface portion of the glass yarn bundle having a thickness of 10 μm and inorganic particles outside the yarn bundle existing outside the surface layer of the glass yarn bundle, and the inorganic particles in the yarn bundle have an average particle diameter of 1 nm. The inorganic particle outside the yarn bundle has an average particle size of 500 nm or more and 5000 nm or less, the average particle size of the inorganic particle on the surface of the yarn bundle is not less than the average particle size of the inorganic particle in the yarn bundle, and the inorganic particle outside the yarn bundle. A prepreg having an average particle size of less than 1.   The prepreg according to claim 1, wherein the average particle diameter of the inorganic particles in the surface of the yarn bundle is larger than the average particle size of the inorganic particles in the yarn bundle.   2. The prepreg according to claim 1, wherein the chemical composition and average particle diameter of the yarn bundle surface layer inorganic particles are the same as the chemical composition and average particle diameter of the inorganic particles in the yarn bundle.   The prepreg according to any one of claims 1 to 3, wherein the glass cloth is formed of a glass yarn bundle having a twist number of 0.2 times / inch or less.   A prepreg characterized by coating a liquid in which inorganic particles having an average particle diameter of 1 nm or more and less than 500 nm are dispersed on a glass cloth and then applying a resin varnish containing inorganic particles having an average particle diameter of 500 nm or more and 5000 nm or less. Production method.   A laminated board, wherein one or more of the prepregs according to any one of claims 1 to 4 and a metal foil are laminated and molded.

Images