JPH10121363A - Production of prepreg for printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve processability of drilling and insulating characteristics such as resistance to electrolytic corrosion by treating a substrate with a silicone oligomer and a coupling agent and impregnating a resin or varnish into the treated substance. SOLUTION: A substrate of glass cloth, etc., is treated with a silicone oligomer having one or more functional groups such as alkoxyl group and silanol group reacting with hydroxyl group of substrate surface and one or more organic functional groups such as one or more epoxy groups or amino groups and amino group-containing hydrochloric acid reacting with a resin for impregnation such as epoxy resin, containing one or more kinds of bifunctional, trifunctional or tetrafunctional siloxane units in the molecule and obtained by three-dimensional condensation reaction and a silane-based coupling agent in a same bath or at two stages using different bath. Then, the treated substrate is impregnated with a resin or varnish such as epoxy resin and subjected to drying treatment after drying to prepare the objective prepreg for printed circuit boards.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a prepreg used for a metal foil-clad laminate such as a printed wiring board or a multilayer printed wiring board.

[0002]

2. Description of the Related Art A prepreg is prepared by laminating a predetermined number of sheets, placing a metal foil on one or both sides and heating and pressing with a parallel hot plate to form a metal-clad laminate, or forming a metal-laminated laminate on both sides with a metal foil. It is used when forming a multilayer printed wiring board by laminating on both sides of an inner layer printed wiring board which has been subjected to circuit processing on a certain laminated board, arranging metal foil on the outside thereof, and heating and pressing with a parallel hot plate.

[0003] A prepreg is usually produced by impregnating a resin varnish on a substrate surface-treated with a surface treatment agent such as a silane coupling agent, and then drying the resin so that the resin is semi-cured. In this drying step, the reaction between the treatment agent and the resin on the surface of the base material progresses to a certain extent, and also proceeds during heating when forming a laminate or a multilayer printed wiring board, thereby increasing the adhesiveness between the base material and the resin. I have. The adhesiveness between the base material and the resin interface has a great effect on properties such as heat absorption, drill workability, insulation properties, etc., as well as moisture absorption properties in the case of a laminate.

On the other hand, with the miniaturization and high performance of electronic devices, laminated boards used for printed wiring boards are required to have better heat resistance, drilling workability, insulation properties, etc. than ever before. For this reason, it is necessary to further improve the adhesiveness between the base material and the resin interface, which affects these properties.

[0005]

FIG. 1 shows an ideal model of the surface of a substrate treated with a general silane coupling agent. The chemically adsorbed silane coupling agent forms a certain layer, and exhibits adhesiveness with the resin layer. However, it is said that industrial processing of inorganic materials is completed in a very short time, and is thus in a processing form containing many defects as shown in FIG. The chemically adsorbed silane coupling agent does not evenly cover the surface, and there are many physically adsorbed silane coupling agents that are easily dissolved in the resin layer. The original adhesiveness cannot be expected in such a chemically adsorbed layer having many defects, and conversely, the physical adsorbed layer causes unevenness of the cured resin near the interface and further lowers the adhesiveness due to lower strength. Probability is high.

As a technique for improving the adhesiveness between the substrate and the resin interface, a method of increasing the reactivity with the resin by adjusting the type and number of the organic functional groups possessed by the ordinary surface treatment agent (Japanese Patent Laid-Open No. Sho 63)
JP-A-230729 and JP-B-62-40368), however, only by increasing the reactivity with the resin, a rigid layer can be formed, and it is difficult to reduce residual stress or the like generated at the interface. No significant improvement can be expected. As an improvement method including a reduction in residual stress at the interface, a method using a long-chain polysiloxane in combination with a surface treatment agent to reduce stress (Japanese Unexamined Patent Application Publication No. 3-62845, Japanese Unexamined Patent Application Publication No.
However, the reactivity between the surface treating agent and the long-chain polysiloxane is very low under ordinary processing conditions, and a general long-chain polysiloxane has an alkoxyl group that reacts with the base material. It is very difficult to exhibit high adhesiveness at the interface due to the fact that the prepreg is not impregnated due to the influence of hydrophobicity such as the methyl group of the long-chain polysiloxane.

On the other hand, Japanese Patent Application Laid-Open No. Hei 1-24953 is characterized in that a chain polysiloxane having both an alkoxyl group which reacts with an inorganic filler and an organic functional group which reacts with a resin is used. However, when the polysiloxane chain is lengthened as shown in FIG. 3, it is highly likely that the chain becomes horizontal on the surface of the base material due to the orientation of a hydrophobic group such as a methyl group, and it is difficult for the chain to enter the resin. It is easy to form a rigid layer because it is adsorbed to the substrate at several places.
Even if it enters the resin, the resin surrounds the chain,
It is difficult to reduce the interface stress according to the chain length. In addition, the layer that is physically adsorbed tends to form a large ring, which tends to cause deterioration in the physical properties of the cured resin.

The present invention solves the above-mentioned problems of the prior art and provides a method for producing a prepreg which exhibits excellent drilling workability and insulating properties when a laminated board or a multilayer printed wiring board is formed. .

[0009]

SUMMARY OF THE INVENTION The present invention relates to a prepreg obtained by impregnating a base material with a resin or varnish or drying after impregnation with a functional group reactive with hydroxyl groups on the base material surface as shown in FIG. A method for producing a prepreg for a printed wiring board, comprising using a substrate treated with a silicone oligomer which has been subjected to a three-dimensional condensation reaction and has one or more organic functional groups each reacting with the prepreg. Hereinafter, the present invention will be described.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The substrate used in the present invention is not particularly limited as long as it is used for producing a metal foil-clad laminate or a multilayer printed wiring board. A substrate is used. Examples of the fiber base material include inorganic fibers such as glass, alumina, asbestos, boron, silica-alumina glass, silica glass, tyrano, silicon carbide, silicon nitride, zirconia, and carbon, and aramid, polyetheretherketone, polyetherimide, and polyetherimide. There are organic fibers such as ethersulfone, cellulose and the like, and a blending system thereof, and a woven fabric of glass fiber is particularly preferably used.

The surface treatment state of the substrate treated with these silicone oligomers is not particularly limited, and may be a substrate treated with an ordinary surface treatment agent containing a silane coupling agent or the like. A pre-treated substrate having a hydroxyl group capable of reacting with the oligomer is preferred.

The silicone oligomer to be treated on the substrate has been subjected to a three-dimensional condensation reaction in advance, and has a functional group that reacts with a hydroxyl group on the surface of the substrate and an organic functional group that reacts with the resin.
There are no particular restrictions on the molecular weight, skeleton, etc., as long as it has at least one siloxane unit, but the degree of polymerization of the siloxane unit is 2 to 70 in the polymer.
The degree is preferred. This degree of polymerization is obtained by conversion from a number average molecular weight or a weight average molecular weight by GPC (gel permeation chromatography). If the degree of polymerization is low, it tends to volatilize during drying of prepreg production, etc., and if it exceeds 70, the heat resistance decreases. Bifunctional, trifunctional, tetrafunctional siloxane units of R ₂ Si02 _{/ 2} , RSi03 _{/ 2} , Si
_04/2 means the following structures, respectively.

[0013]

Here, R is the same or another organic group, specifically, methyl group, ethyl group, phenyl group, vinyl group, epoxy group, mercapto group, acrylic group, amino group, amino group-containing hydrochloride. And amino group-containing inorganic acid salts. The organic group preferably contains one or more organic functional groups that react with the resin, and an epoxy group, an amino group, and an amino group-containing hydrochloride are generally used. The functional group that reacts with the hydroxyl group on the substrate surface is not particularly limited, but an alkoxyl group or a silanol group is generally preferable. Further, the silicone oligomer preferably contains at least one kind of bifunctional, trifunctional or tetrafunctional siloxane unit in the molecule, and the tetrafunctional siloxane unit accounts for 5 mol% or more of the entire silicone oligomer. And more preferred. The silicone oligomer has been subjected to a three-dimensional condensation reaction in advance, but the one that has been reacted to such an extent that it does not become a gel before blending is used. For this purpose, the reaction temperature, the reaction time, the oligomer composition ratio, and the type and amount of the catalyst are changed and adjusted. Acetic acid, hydrochloric acid,
It is preferable to synthesize with an acidic solution such as maleic acid or phosphoric acid.

There is no particular limitation on the method of treating the silicone oligomer with respect to the substrate such as the treatment solution and the treatment conditions, but the amount of adhesion to the substrate is preferably in the range of 0.01% by weight to 5% by weight. When the content is 0.01% by weight or less, the effect of improving the interfacial adhesion is difficult to obtain, and when the content is 5% by weight or more, heat resistance and the like deteriorate. Also,
The treatment liquid for treating the base material may contain additives including various solvents and various coupling agents in addition to the silicone oligomer. Coupling agents include silane-based coupling agents and titanate-based coupling agents, and generally, epoxy silane-based, aminosilane-based, cationic silane-based, vinylsilane-based, acrylic silane-based, and mercaptosilane-based silane coupling agents. And their composite systems are often used in an arbitrary amount. Further, a coupling agent may be treated on the surface of the substrate treated with the treatment liquid. The type of the coupling agent and the treatment conditions are not particularly limited, but the amount of the coupling agent attached is 5% by weight. The following is preferred.

The resin for the prepreg used in the present invention is not particularly limited, and examples thereof include epoxy resin, polyimide resin, triazine resin, phenol resin, melamine resin, polyester resin, and modified resins of these resins. Can be Further, these resins may be used in combination of two or more kinds, and may be various solvent solutions as needed. As the solvent, any solvent such as an alcohol, a polyester, a ketone, an amide, an aromatic hydrocarbon, an ester, and a nitrile may be used, and a mixed solvent of several kinds may be used.

As the curing agent, various conventionally known curing agents can be used. For example, when an epoxy resin is used as the resin, dicyandiamide, diaminodiphenylmethane, diaminodiphenylsulfone, phthalic anhydride, pyromellitic anhydride, Examples include polyfunctional phenols such as phenol novolak and cresol novolak. Often, accelerators are used to accelerate the reaction between the resin and the curing agent. The type and amount of the accelerator are not particularly limited. For example, an imidazole compound, an organic phosphorus compound, a tertiary amine, a quaternary ammonium salt, or the like is used, and two or more kinds may be used in combination.

The conditions for coating the prepreg used in the present invention are not particularly limited, but when a solvent solution is used, drying at a temperature at which the solvent can be volatilized or higher is preferable.

According to the present invention described above, the substrate is treated with a three-dimensionally condensation-reacted silicone oligomer having at least one functional group that reacts with a hydroxyl group on the surface of the substrate and one or more organic functional groups that react with the resin. Therefore, when a laminated board or multilayer printed wiring board is used, the silicone oligomer has a cushion-like role at the interface between the base material and the resin with respect to the thin and rigid processing agent layer using the conventional silane coupling agent. However, the strain generated at the interface can be reduced, and the excellent adhesiveness inherent to the resin can be brought out.

[0020]

Embodiments of the present invention will be specifically described below.

(Example 1) A solution prepared by mixing 40 g of tetramethoxysilane, 14 g of dimethoxydimethylsilane and 126 g of methanol in a glass flask equipped with a stirrer, a condenser and a thermometer was mixed with 0.5 g of acetic acid and distilled water. After stirring at 50 ° C. for 1 hour, 15 g of allyl glycidyl ether was added to chloroplatinate (2% by weight).
(Isopropyl alcohol solution) was added, and the mixture was further stirred for 7 hours to synthesize an epoxy-modified silicone oligomer. The polymerization degree of the siloxane unit of the obtained silicone oligomer was 13 (converted from the number average molecular weight by GPC, the same applies hereinafter). Methanol was added to this silicone oligomer solution to prepare a treatment liquid having a solid content of 1% by weight.

Example 2 In the same manner as in Example 1, a solution containing 40 g of trimethoxymethylsilane, 15.6 g of dimethoxydimethylsilane, and 130 g of methanol was prepared.
After 0.5 g of acetic acid and 13.2 g of distilled water were mixed and stirred at 50 ° C. for 1 hour, 17 g of allyl glycidyl ether was added.
And 0.04 g of chloroplatinate (2% by weight isopropyl alcohol solution) were added, and the mixture was further stirred for 7 hours to synthesize an epoxy-modified silicone oligomer. The degree of polymerization of the siloxane unit of the obtained silicone oligomer was 11. Methanol was added to this silicone oligomer solution to prepare a treatment liquid having a solid content of 1% by weight.

Example 3 As in Example 1, 32 g of dimethoxydimethylsilane and 8 g of tetramethoxysilane were used.
g, 17 g of dimethoxymethylsilane and 9 g of methanol
To a solution prepared by mixing 8 g, 0.5 g of acetic acid and 16.
After mixing 2 g and stirring at 50 ° C. for 1 hour, 18.2 g of allyl glycidyl ether and 0.04 g of chloroplatinate (2% by weight isopropyl alcohol solution) were added, and the mixture was further stirred for 7 hours to obtain an epoxy-modified silicone. Oligomers were synthesized. The polymerization degree of the siloxane unit of the obtained silicone oligomer was 18. Methanol was added to this silicone oligomer solution to prepare a treatment liquid having a solid content of 1% by weight.

(Example 4) As in Example 1, 9 g of dimethoxydimethylsilane and 20 g of tetramethoxysilane were used.
g, dimethoxymethylsilane 11 g, methanol 9
0.5 g acetic acid and 14 g distilled water
After mixing and stirring at 50 ° C. for 1 hour, 11.8 g of allyl glycidyl ether and 0.03 g of chloroplatinate (2% by weight isopropyl alcohol solution) were added, and the mixture was further stirred for 7 hours to obtain an epoxy-modified silicone oligomer. Was synthesized. The degree of polymerization of the siloxane unit of the obtained silicone oligomer was 20. Methanol was added to this silicone oligomer solution to prepare a treatment liquid having a solid content of 1% by weight.

Example 5 As in Example 1, 9 g of trimethoxymethylsilane and 20 g of tetramethoxysilane were used.
g, dimethoxymethylsilane 11 g, methanol 9
0.5 g of acetic acid and 13 parts of distilled water were added to the solution containing 2 g of the mixture.
After mixing 2 g and stirring at 50 ° C. for 1 hour, 11.2 g of allyl glycidyl ether and 0.03 g of chloroplatinate (2% by weight isopropyl alcohol solution) were added, and the mixture was further stirred for 7 hours to obtain an epoxy-modified silicone. Oligomers were synthesized. The polymerization degree of the siloxane unit of the obtained silicone oligomer was 16. Methanol was added to this silicone oligomer solution to prepare a treatment liquid having a solid content of 1% by weight.

(Example 6) As in Example 1, 9 g of dimethoxydimethylsilane and 20 g of tetramethoxysilane were used.
g, dimethoxymethylsilane 11 g, methanol 9
0.5 g acetic acid and 14 g distilled water
After mixing and stirring at 50 ° C. for 1 hour, 5.9 g of allylamine and 0.02 g of chloroplatinate (2% by weight isopropyl alcohol solution) were added, and the mixture was further stirred for 7 hours to synthesize an amine-modified silicone oligomer. did. The polymerization degree of the siloxane unit of the obtained silicone oligomer was 18. Methanol was added to this silicone oligomer solution to prepare a treatment liquid having a solid content of 1% by weight.

Example 7 As in Example 1, 9 g of dimethoxydimethylsilane and 20 g of tetramethoxysilane were used.
g, dimethoxymethylsilane 11 g, methanol 9
0.5 g acetic acid and 14 g distilled water
After mixing and stirring at 50 ° C. for 1 hour, 9.7 g of allylamine hydrochloride and 0.03 g of chloroplatinate (2% by weight isopropyl alcohol solution) were added, and the mixture was further stirred for 7 hours to obtain a cationically modified silicone oligomer. Synthesized. The polymerization degree of the siloxane unit of the obtained silicone oligomer was 17. Methanol was added to this silicone oligomer solution to prepare a treatment liquid having a solid content of 1% by weight.

Example 8 γ-glycidoxypropyltrimethoxysilane (trade name: A-) was added to the silicone oligomer solution obtained in Example 4 as a silane coupling agent.
187, manufactured by Nippon Unicar Co., Ltd.), and methanol was further added to prepare a treatment liquid having a solid content of 1% by weight.

Example 9 N-β was added to the silicone oligomer solution obtained in Example 4 as a silane coupling agent.
-(N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane hydrochloride (trade name: SZ-6)
032, manufactured by Dow Corning Toray Silicone Co., Ltd.), and methanol was further added to prepare a treatment liquid having a solid content of 1% by weight.

Next, the processing solutions prepared in Examples 1 to 9
A glass cloth having a thickness of 0.2 mm, which had been heat-treated and degreased, was immersed as a glass fiber base material, and then dried by heating at 120 ° C. to obtain a glass cloth having a silicone oligomer adhered to the surface. The adhesion amount of the silicone oligomer was 0.07 to 0.12% by weight.

(Example 10) On the glass cloth treated in Example 4, γ-glycidoxypropyltrimethoxysilane (trade name: A-187, manufactured by Nippon Unicar Co., Ltd.) was used as a silane coupling agent in solid content. The glass cloth was further treated with an aqueous solution containing 0.5% by weight and 0.5% by weight of acetic acid, and dried by heating at 120 ° C. The attached amount of the silane coupling agent was 0.04% by weight.

Example 11 N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane hydrochloride (trade name) was added to the glass cloth treated in Example 4 as a silane coupling agent. SZ-6032, manufactured by Dow Corning Toray Silicone Co., Ltd.) was further treated with an aqueous solution containing 0.5% by weight of solid content and 0.5% by weight of acetic acid to obtain a glass cloth which was heated and dried at 120 ° C. . The attached amount of the silane coupling agent was 0.05% by weight.

Example 12 In the treatment solution prepared in Example 4, 0.1% of γ-glycidoxypropyltrimethoxysilane (trade name: A-187, manufactured by Nippon Unicar Co., Ltd.) was used as a glass fiber base material. After immersing the glass cloth having a thickness of 0.2 mm to which weight% was adhered, it was dried by heating at 120 ° C. to obtain a glass cloth having a silicone oligomer adhered to the surface. The adhesion amount of the silicone oligomer was 0.05% by weight.

Example 13 N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane.hydrochloride (trade name) was added to the treatment solution prepared in Example 4 as a glass fiber base material. SZ-16032, manufactured by Dow Corning Toray Silicone Co., Ltd.) was immersed in a glass cloth having a thickness of 0.2 mm to which 0.1% by weight was adhered, and then heated and dried at 120 ° C. to adhere a silicone oligomer to the surface. Got the cloth. The adhesion amount of the silicone oligomer was 0.04% by weight.

(Comparative Example 1) As a glass fiber substrate, 0.1% by weight of γ-glycidoxypropyltrimethoxysilane (trade name: A-187, manufactured by Nippon Unicar Co., Ltd.) used in Example 12 was adhered. A 0.2 mm thick glass cloth was used.

Comparative Example 2 N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane hydrochloride (trade name: SZ-6032) used in Example 13 as a glass fiber base material Toray Dow Corning Silicone Co., Ltd.) having a thickness of 0.2 mm was used.

(Comparative Example 3) Instead of the silicone oligomer treatment liquid, an epoxy-modified silicone oil (trade name: K
F101, manufactured by Shin-Etsu Chemical Co., Ltd.)
A 0.2% by weight heat-degreased glass cloth as a glass fiber substrate is immersed in a solution containing the same by weight as a glass fiber substrate, and then heated and dried at 120 ° C. to attach a silicone oil to the surface of the glass cloth. I got The attached amount of silicone oil was 0.12% by weight.

After impregnating the glass cloths obtained in Examples 1 to 13 and Comparative Examples 1 to 3 with the following epoxy resin varnish,
The resultant was dried by heating at 40 ° C. for 5 to 10 minutes to obtain a prepreg having a resin content of 41% by weight. Four prepregs are stacked, and copper foil having a thickness of 35 μm is stacked on both sides thereof at 170 ° C. for 90 minutes.
A double-sided copper-clad laminate was produced under a pressing condition of 4.0 MPa. 100 parts by weight of brominated bisphenol A epoxy resin (epoxy equivalent: 530) 4 parts by weight of dicyandiamide 0.5 part by weight of 2-ethyl-4-methylimidazole 0.5 parts by weight of the above compound was added to methyl ethyl ketone and ethylene glycol monomethyl ether (50: 50% by weight). Dissolve,
A varnish having a nonvolatile content of 70% by weight was produced.

The resulting double-sided copper-clad laminate was evaluated for drill workability, water absorption, solder heat resistance and insulation resistance. Table 1 shows the results.

[0040]

[Table 1]

The test method is as follows. Drill workability: Using a drill of φ0.4 mm, rotation speed: 80,000 rpm, feed rate: 3,200 mm /
Mining was performed, and a hole wall crack due to peeling of the interface between the base material and the resin was evaluated. The hole wall cracks were obtained by boiling a drilled test piece with a red check solution for 1 hour, and then measuring the ratio of the area permeated around the hole to the hole area by an image processing device based on surface observation with a microscope (average of 20 holes). Unit:% Water absorption: 2 in normal and pressure cooker testers
It was calculated from the weight difference after holding for a time. Unit:% by weight Solder heat resistance: After being held in a pressure cooker tester for 2 hours, immersed in solder at 260 ° C. for 20 seconds,
The appearance was visually inspected. “OK” in the table means that there is no measling or blistering. Electrolytic corrosion resistance: 300 μm between hole walls evaluated by drilling workability
85 ° C / 85% RH, 100
The time until conduction breakdown when V was applied was measured. In addition, all conduction breakdowns are caused by CAF (Conductive Anodi
c Filaments).

From the above results, Examples 1 to 13 are excellent as compared with Comparative Examples 1 and 2, which have been conventionally performed, without deterioration in solder heat resistance and the like, and are resistant to thermal shock.
Also, the inner wall cracks during drilling are remarkably small, and are excellent in reducing the impact during drilling. The moisture absorption rate is
Although almost the same, it can be seen that the electrolytic corrosion resistance is significantly improved and excellent.

[0043]

According to the prepreg for a printed wiring board of the present invention, when it is used as a laminated board, the insulating properties such as drilling workability and electric corrosion resistance can be improved without lowering the properties of the conventional laminated board. .

[Brief description of the drawings]

FIG. 1 is a model of a cross section of a substrate showing an ideal state when a silane coupling agent is treated on the surface of the substrate.

FIG. 2 is a model of a cross section of a substrate showing an actual state when a silane coupling agent is treated on the surface of the substrate.

FIG. 3 is a cross-sectional model of a substrate when the substrate surface is treated with a long-chain polysiloxane.

FIG. 4 is a model when treated with the silicone oligomer of the present invention.

[Explanation of symbols]

1: chemically adsorbed silicone chain (having a chemical bond with the substrate) 2: physically adsorbed silicone chain (having no chemical bond with the substrate) 3: resin 4: inside the silicone chain Chain by bonding

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H05K 1/03 610 H05K 1/03 610T // D06M 15/643 D06M 15/643 (72) Inventor Masahisa Oze Shimodate, Ibaraki 1500 Ogawa Inside the Shimodate Plant of Hitachi Chemical Co., Ltd.

Claims (12)

[Claims] 1. A prepreg obtained by impregnating a base material with a resin or varnish or drying after impregnation, wherein a prepreg having at least one functional group reacting with a hydroxyl group on the surface of the base material and one or more organic functional groups reacting with the resin are provided. A method for producing a prepreg for a printed wiring board, comprising using a substrate treated with a silicone oligomer subjected to a three-dimensional condensation reaction. 2. The prepreg for a printed wiring board according to claim 1, wherein the silicone oligomer contains at least one kind of trifunctional (RSo3 _{/ 2} ) or tetrafunctional (Si04 _{/ 2} ) siloxane unit in the molecule. Production method (wherein, R groups are the same or different organic groups). 3. The prepreg for a printed wiring board according to claim 1, wherein the silicone oligomer has bifunctional (R ₂ Si02 _{/ 2} ) and tetrafunctional (Si04 _{/ 2} ) as siloxane units contained in the molecule. Wherein R groups are the same or different organic groups. 4. The manufacture of the silicone oligomer is a trifunctional a siloxane unit containing in the molecule (RSi0 _3/2) and tetrafunctional (Si0 _4/2) for printed wiring board prepreg according to claim 1 consisting of A method wherein the R groups are the same or different organic groups. 5. The prepreg for a printed wiring board according to claim 1, wherein the silicone oligomer comprises difunctional (R ₂ SiO _2/2 ) and trifunctional (RSiO _3/2 ) siloxane units in the molecule. Wherein R groups are the same or different organic groups. 6. The silicone oligomer according to claim 1, wherein the siloxane units contained in the molecule are difunctional (R ₂ SiO _2/2 ), trifunctional (RSiO _3/2 ), and tetrafunctional (Si04 _{/ 2} ). Item 1. The method for producing a prepreg for a printed wiring board according to Item 1, wherein the R groups are the same or different organic groups. 7. The method according to claim 4, wherein the silicone oligomer contains 4
5 mol of functional (Si04 _{/ 2} ) siloxane units in total
The method for producing a prepreg for a printed wiring board according to any one of claims 3, 4 and 6, wherein the R groups are the same or different organic groups. 8. The method for producing a prepreg for a printed wiring board according to claim 1, wherein a coupling agent is used in combination with the treatment with the silicone oligomer. 9. The method for producing a prepreg for a printed wiring board according to claim 1, wherein the prepreg is treated with a coupling agent after being treated with a silicone oligomer. 10. The method for producing a prepreg for a printed wiring board according to claim 1, wherein the organic functional group of the silicone oligomer is an epoxy group. 11. The method for producing a prepreg for a printed wiring board according to claim 1, wherein the organic functional group of the silicone oligomer is an amino group. 12. The production of a prepreg for a printed wiring board according to claim 1, wherein the organic functional group of the silicone oligomer is an amino group-containing organic acid salt or an inorganic acid salt. Method.