JP4586609B2 - Curable resin composition, prepreg, substrate, metal foil-clad laminate and printed wiring board - Google Patents

Description

  The present invention relates to a curable resin composition, a prepreg, a substrate, a metal foil-clad laminate, and a printed wiring board.

  The printed wiring board is obtained by forming printed wiring on a substrate obtained by heating and pressurizing a single prepreg having a matrix of an electrically insulating resin or a predetermined number of these prepregs. When the printed wiring is formed by the subtractive method, a metal-clad laminate is used. This metal-clad laminate is manufactured by stacking a metal foil such as a copper foil on one side or both sides of a prepreg and heating and pressing. As the electrically insulating resin, thermosetting resins such as phenol resins, epoxy resins, polyimide resins, bismaleimide-triazine resins are widely used, and thermoplastic resins such as fluororesins and polyphenylene ether resins are used. Sometimes.

  On the other hand, information terminal devices such as personal computers and mobile phones are widespread, but printed wiring boards mounted on them are becoming smaller and higher in density. Along with this, the mounting form has progressed from a pin insertion type to a surface mounting type, and further to an area array type represented by a BGA (ball grid array) using a plastic substrate. In a substrate on which a bare chip such as a BGA is directly mounted, the connection between the chip and the substrate is generally performed by wire bonding using thermosonic bonding. For this reason, the substrate on which the bare chip is mounted is exposed to a high temperature of 150 ° C. or higher, and a certain degree of high heat resistance is required for the electrically insulating resin in the substrate.

  In addition, from the viewpoint of environmental problems, lead-free solder is progressing. However, since the melting temperature of solder increases accordingly, higher heat resistance is required for the substrate. From the viewpoint of environmental problems, the requirement for halogen-free substrates is also increasing, and the use of brominated flame retardants has become difficult.

  Further, the substrate may be required to be capable of so-called repair, in which a chip once mounted is removed. In repair, when the mounted chip is removed and the chip is mounted again, the same amount of heat is applied to the substrate as in the first chip mounting. Therefore, a substrate that requires repairability is required to have high thermal shock resistance that can withstand the heat history applied cyclically. Generally, however, an electrically insulating resin has a shortage of thermal shock resistance. In some cases, a problem such as peeling between the substrate and the resin may occur.

  Therefore, a prepreg impregnated with a resin composition containing polyamideimide as an essential component on a fiber base has been proposed in order to improve thermal shock resistance, reflow resistance, and crack resistance and to improve fine wiring formation. (For example, see Patent Document 1.)

By the way, with the miniaturization and high performance of electronic devices, it is necessary to store printed wiring boards on which components are mounted in a limited space. As a method to deal with this problem, a method in which a plurality of printed wiring boards are arranged in multiple stages and connected to each other by a wire harness or a flexible wiring board, or a rigid-based rigid board in which a polyimide-based flexible board and a conventional rigid board are multilayered A method using a flex substrate is known.
JP 2003-55486 A

  However, in the case of a conventional prepreg, it has been difficult to achieve a sufficiently satisfactory level in all of the processability in manufacturing a substrate and the flame retardancy and flexibility of the substrate. For example, using a halogen-free flame retardant to make the obtained substrate sufficiently flame-retardant and flexible, the prepreg tack becomes excessively strong, and the substrate is formed by press molding or the like. The processability in manufacturing the is impaired.

  The present invention provides a prepreg that is excellent in processability when manufacturing a substrate, and that is excellent in flame retardancy while being halogen-free, and can obtain a substrate having a sufficiently large flexibility. With the goal. Another object of the present invention is to provide a curable resin composition suitably used in this prepreg, and a substrate, a metal foil-clad laminate and a printed wiring board obtained using this prepreg.

  In order to solve the above problems, the curable resin composition of the present invention contains an acrylic rubber and a phosphorus-containing filler, the acrylic rubber has a weight average molecular weight of 50,000 to 1,500,000, It is a curable resin composition containing a filler present in the form of solid particles in a cured product of the curable resin composition.

  This curable resin composition of the present invention is a curable resin composition in which a crosslinked structure is formed by heating or the like to become a cured product. In the curable resin composition, the acrylic rubber having a weight average molecular weight in the specific range described above and solid particles in the cured product. In combination with a phosphorus-containing filler that exists as it is, it is a prepreg that is excellent in processability when manufacturing a substrate when used as a prepreg matrix, and is flame-retardant while being halogen-free. In addition to being excellent, a prepreg capable of obtaining a substrate having a sufficiently large flexibility was obtained.

  The average particle size of the phosphorus-containing filler is preferably 0.1 to 30 μm. Thereby, the tack of the prepreg is sufficiently reduced and the processability is particularly excellent, and the flexibility can be increased while maintaining the sufficient flame retardancy of the substrate.

  The curable resin composition of the present invention contains 0.1 to 10% by mass of phosphorus based on the entire curable resin composition in order to further improve the flame retardancy and flexibility. It is preferable.

  It is preferable that the said filler which exists in the particle form in the hardened | cured material of curable resin composition contains the phosphinic acid aluminum salt. This makes it possible to achieve a higher level of processability when manufacturing the substrate, and flame retardancy and flexibility of the substrate.

  The curable resin composition of the present invention contains at least one flame retardant selected from the group consisting of red phosphorus, phosphate ester, ammonium polyphosphate, melamine polyphosphate, and phosphazene compound from the viewpoint of improving flame retardancy. It is preferable.

  In addition, the curable resin composition of the present invention has at least one difficulty selected from the group consisting of calcium molybdate, aluminum hydroxide, magnesium hydroxide, calcium hydroxide and hydrotalcite from the viewpoint of improving flame retardancy. It is preferable to contain a flame retardant.

  The curable resin composition of the present invention preferably further contains a thermosetting resin, and an epoxy resin is preferable as the thermosetting resin.

  The acrylic rubber preferably has an epoxy group at a rate such that the epoxy value is 2 to 18 equivalent / kg. Thereby, it becomes more excellent in the point of the heat resistance and dimensional stability of a board | substrate.

  The prepreg of the present invention has a fiber base material and the curable resin composition of the present invention impregnated therein. This prepreg of the present invention is a prepreg excellent in processability when producing a substrate by using the curable resin composition of the present invention, and is excellent in flame retardancy while being halogen-free. A substrate having a sufficiently large flexibility can be obtained.

  The prepreg of the present invention preferably has a tack measured by a probe tack test method of 1 to 50 gf. Thereby, the production efficiency at the time of manufacturing a board | substrate by press molding etc. is raised especially.

  The thickness of the fiber base material is preferably 100 μm or less. Thereby, the flexibility of the obtained substrate can be made larger.

  The substrate of the present invention is a substrate obtained by heating and pressurizing the prepreg of the present invention. Further, the metal foil-clad laminate of the present invention comprises the substrate of the present invention and a metal foil provided on at least one surface of the substrate, and the printed wiring board of the present invention is the present invention. And a wiring pattern made of a metal foil provided on at least one surface of the substrate.

  These substrates, metal foil-clad laminates, and printed wiring boards have sufficient flame retardancy and flexibility by being manufactured using the prepreg of the present invention.

  According to the present invention, there is provided a prepreg that is excellent in processability when manufacturing a substrate, and is capable of obtaining a substrate having a sufficiently large flexibility while being excellent in flame retardancy while being halogen-free. Is done. Moreover, according to this invention, the curable resin composition used suitably in this prepreg is provided.

  Furthermore, according to this invention, the board | substrate, metal foil tension laminated board, and printed wiring board which have sufficient flame retardance and flexibility are provided. In particular, the printed lint wiring board according to the present invention can be arbitrarily bent, and can be stored in a casing of an electronic device with high density.

  Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

  FIG. 1 is a perspective view showing an embodiment of a prepreg according to the present invention. A prepreg 100 shown in FIG. 1 is a sheet-like prepreg composed of a fiber base material and a curable resin composition impregnated therein.

  The fiber base material in the prepreg 100 is a flexible fiber base material that can be bent arbitrarily, and the thickness thereof is preferably 100 μm or less. Thereby, when it combines with the curable resin composition of the specific composition which is mentioned later, the flexibility of the board | substrate obtained increases synergistically, and it becomes very easy to bend | fold arbitrarily. In order to further increase the flexibility of the substrate, the thickness is more preferably 50 μm or less, and further preferably 30 μm or less. On the other hand, the lower limit of the thickness of the fiber substrate is not particularly limited, but is preferably 5 μm or more, and more preferably 10 μm or more. Here, by using the fiber base material, the dimensional change accompanying heating, moisture absorption, etc. in the manufacturing process of the substrate is sufficiently small.

  The form of the fiber base material can be appropriately selected from those generally used when producing metal foil-clad laminates and multilayer printed wiring boards, but usually fiber base materials such as woven fabrics and nonwoven fabrics are used. . The fibers constituting the fiber substrate include glass, alumina, asbestos, boron, silica alumina glass, silica glass, tyranno, silicon carbide, silicon nitride, zirconia, and other inorganic fibers, aramid, polyetheretherketone, polyetherimide , Organic fibers such as polyethersulfone, carbon and cellulose, or mixed papers thereof. Among these, glass fiber is preferable. In particular, glass cloth (glass fiber woven fabric) is preferably used as the fiber base material.

  The curable resin composition in the prepreg 100 contains acrylic rubber and a phosphorus-containing filler dispersed in solid particles.

  The acrylic rubber is a rubber mainly composed of a polymer having a monomer unit of (meth) acrylic acid alkyl ester, and its weight average molecular weight is 50,000 to 1,500,000, more preferably 300,000 to 1,500,000. If the weight average molecular weight of the acrylic rubber is less than 50,000, the tack of the prepreg tends to be too strong or the flexibility of the substrate tends to decrease. If it exceeds 1.5 million, the flexibility of the substrate decreases. Tend to. Here, said weight average molecular weight is a value measured by gel permeation chromatography (GPC) analysis, and means a standard polystyrene equivalent value. The GPC analysis can be performed, for example, using “GL8300 MDT-5” (trade name, manufactured by Hitachi Chemical Co., Ltd.) as a column and tetrahydrofuran (THF) as an eluent. In the present specification, the term “(meth) acryl” means methacryl or acryl.

  Generally, (meth) acrylic acid alkyl ester generates a polymer by addition polymerization of its (meth) acrylic group by generating radicals. In this (meth) acrylic acid alkyl ester, the alkyl group is preferably an alkyl group having 1 to 20 carbon atoms which may have a substituent. Examples of the substituent for the alkyl group include an alicyclic group, a glycidyl group, a hydroxyl group, and a nitrogen-containing cyclic group.

  Specific examples of the (meth) acrylic acid alkyl ester include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, isobutyl acrylate, ethylene glycol methyl ether acrylate, Cyclohexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, isobornyl acrylate, acrylate amide, isodecyl acrylate, octadecyl acrylate, lauryl acrylate, allyl acrylate, N-vinylpyrrolidone acrylate, methacryl Methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, isobutyl methacrylate, methacrylate Lenglycol methyl ether, cyclohexyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, isobornyl methacrylate, methacrylamide, isodecyl methacrylate, octadecyl methacrylate, lauryl methacrylate, allyl methacrylate, N methacrylate -Vinylpyrrolidone and dimethylaminoethyl methacrylate are mentioned.

  The acrylic rubber preferably has an epoxy group. In this case, the epoxy value of the acrylic rubber is preferably 2 to 18 equivalent / kg, and more preferably 2 to 8 equivalent / kg. When the epoxy value is less than 2 equivalents / kg, the heat resistance of the substrate decreases due to a decrease in the glass transition temperature of the cured product, and when it exceeds 18 equivalents / kg, the dimensional stability of the substrate decreases due to an increase in storage modulus. To do.

  The acrylic rubber having an epoxy group is obtained, for example, by copolymerizing glycidyl (meth) acrylate as a (meth) acrylic acid alkyl ester with another monomer copolymerizable therewith. An acrylic rubber having an epoxy value within the above range can be obtained by appropriately adjusting the copolymerization ratio at the time of copolymerization. Usually, the acrylic rubber which has an epoxy value of 2-18 equivalent / kg is obtained by making the ratio of a monomer other than this into 5-15 weight part with respect to 100 weight part of glycidyl (meth) acrylates. The acrylic rubber having an epoxy group is, for example, “HTR860P3” (manufactured by Nagase ChemteX Corporation, trade name, epoxy value 3.05), “HM6-1M50” (manufactured by Nagase ChemteX Corporation, trade name, epoxy (Value 8.00) is commercially available.

  The acrylic rubber may have acrylonitrile or the like as a monomer unit in addition to the (meth) acrylic acid alkyl ester.

  The acrylic rubber is obtained, for example, by radical polymerization using a radical polymerization initiator that generates radicals. Examples of radical polymerization initiators include persulfates such as azobisisobutyronitrile (AIBN), tert-butyl perbenzoate, benzoyl peroxide, lauroyl peroxide, potassium persulfate, cumene hydroperoxide, and t-butyl hydroperoxide. Dicumyl peroxide, di-t-butyl peroxide, 2,2′-azobis-2,4-dimethylvaleronitrile, t-butyl perisobutyrate, t-butyl perpivalate, hydrogen peroxide / ferrous salt, Examples thereof include persulfate / sodium acid sulfite, cumene hydroperoxide / ferrous salt, benzoyl peroxide / dimethylaniline, and the like. These may be used alone or in combination of two or more.

  In the curable resin composition, the content ratio of the acrylic rubber is preferably 20 to 60% by mass based on the total amount of the curable resin composition. When the acrylic rubber content is less than 20% by mass, the glass transition temperature is drastically lowered and the heat resistance tends to be reduced, and when it exceeds 60% by mass, voids remain in the fiber substrate such as glass cloth. It tends to be easier.

  The phosphorus-containing filler in the curable resin composition is a filler (hereinafter referred to as “insoluble filler”) that is dispersed in solid particles in the curable resin composition before curing and remains in the solid particles in the cured product. And containing phosphorus. The average particle size of the phosphorus-containing filler is preferably in the range of 0.1 to 30 μm. If the average particle size of the phosphorus-containing filler exceeds 30 μm, the flexibility of the substrate tends to decrease, and if it is less than 0.1 μm, the prepreg tack tends to increase. Here, the said average particle diameter of a phosphorus containing filler is an average particle diameter measured by a laser diffraction method. The average particle diameter can be measured by a laser diffraction method using, for example, “SALD-2000” which is a laser diffraction particle size distribution measuring apparatus manufactured by Shimadzu Corporation.

  It is particularly preferable that the phosphorus-containing filler as the insoluble filler contains an aluminum phosphinate. Thereby, especially remarkable effects are obtained with respect to tackiness of the prepreg and flame retardancy and flexibility of the substrate. As a phosphorus containing filler which contains an aluminum phosphinate and can be used as an insoluble filler, for example, “OP930” (trade name, manufactured by Clariant Japan Co., Ltd.) is commercially available. In addition, as a phosphorus-containing filler that can be used as an insoluble filler, “HCA-HQ” (trade name, manufactured by Sanko Co., Ltd.) is also available as a commercial product.

  In addition to the phosphorus-containing filler as described above, the curable resin composition further contains a filler that dissolves in the cured product after curing (hereinafter referred to as “soluble filler”), and contains phosphorus. It may be.

  The curable resin composition preferably contains at least one flame retardant selected from the group consisting of red phosphorus, phosphate ester, ammonium polyphosphate, melamine polyphosphate, and phosphazene compound. Here, these flame retardants may be contained in the curable resin composition as the insoluble filler described above, or may be contained as a soluble filler. Alternatively, these flame retardants may be components dissolved in the curable resin composition before curing.

  As the phosphate ester, a monomer type phosphate ester or a condensed type phosphate ester can be used. The monomer type phosphate ester is “Reophos TPP” (Ajinomoto Fine Techno Co., Ltd., trade name), and the condensed phosphate ester is “Reophos RDP” and “Reophos BAPP” (Ajinomoto Fine Techno Co., Ltd. trade name). Each is commercially available. As for red phosphorus, “Nobaquel” (trade name, manufactured by Phosphor Chemical Co., Ltd.) and “Hishiguard” (trade name, manufactured by Nippon Chemical Industry Co., Ltd.) are commercially available. As for polyphosphoric acid, “PMP100” (manufactured by Nissan Chemical Co., Ltd., trade name) and “Exorit OP1311” (manufactured by Clariant Japan KK, trade name) are commercially available. As for phosphazene, “SBP100” (trade name, manufactured by Otsuka Chemical Co., Ltd.) is commercially available.

  The phosphorus content in the curable resin composition is preferably in the range of 0.1 to 10% by mass. If the content is less than 0.1% by weight, the flame retardancy tends to decrease, and if it exceeds 10% by mass, the flexibility of the substrate tends to decrease.

  Moreover, the curable resin composition contains at least one flame retardant selected from the group consisting of calcium molybdate, aluminum hydroxide, magnesium hydroxide, calcium hydroxide and hydrotalcite, in addition to the above flame retardant. You may contain. These are used as insoluble fillers or soluble fillers, or as components that dissolve in the resin.

  It is preferable that the curable resin composition contains a thermosetting resin composed of a compound having a plurality of crosslinkable functional groups that are crosslinked by heating. This thermosetting resin is particularly preferably an epoxy resin composed of a polyepoxy compound having a plurality of epoxy groups as crosslinkable functional groups. Specific examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, biphenyl type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolak type epoxy resin, Naphthalene skeleton-containing epoxy resin, aralkylene skeleton-containing epoxy resin, phenol biphenyl aralkyl type epoxy resin, phenol salicylaldehyde novolac type epoxy resin, lower alkyl group-substituted phenol salicylaldehyde novolak type epoxy resin, dicyclopentadiene skeleton type epoxy resin, polyfunctional glycidyl Examples include amine-type epoxy resins and polyfunctional alicyclic epoxy resins, which are used alone or in combination. It is possible. As the biphenyl aralkyl type epoxy resin, “NC-3000H” (trade name, manufactured by Nippon Kayaku Co., Ltd.) is used. As the phosphorus-containing epoxy resin, “ZX-1548” (trade name, manufactured by Toto Kasei Co., Ltd.) is used. As the cresol novolac type epoxy resin, “EPICLON N-660” (manufactured by Dainippon Ink Co., Ltd., trade name) is available as a commercial product.

  When using an epoxy resin, the hardening | curing agent or hardening accelerator can also be used together. As the curing agent, a polyphenol compound having a plurality of phenolic hydroxyl groups is preferable. Examples of the polyphenol compound include hydroquinone, phenol resin, cresol resin, and the like, and these can be used in combination of two or more as required. Polyphenol compounds include aminophenol-modified novolak resin “Phenolite LA-1356” (trade name, manufactured by Dainippon Ink Co., Ltd.), biphenyl novolak “MEH-7851” (trade name, manufactured by Meiwa Kasei Co., Ltd.), etc. Is commercially available. As the curing accelerator, amines and imidazoles are preferably used. Examples of amines include dicyandiamide, diaminodiphenylethane, guanylurea and the like. Examples of imidazoles include 2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate. And imidazole compounds such as benzimidazole. Although the compounding quantity of a hardening accelerator can be suitably determined according to the quantity etc. of the epoxy group in a curable resin composition, generally, it is 0 with respect to 100 weight part of the whole curable resin composition. It is preferable to set it as 0.01 to 10 weight part.

  In addition to the components described above, the curable resin composition may include a crosslinking agent such as isocyanate and melamine, an inorganic filler such as silica, a conductive particle, a coupling agent, a pigment, a leveling agent, and an antifoam as necessary. An agent, an ion trap agent and the like may be contained.

The prepreg 100 preferably has a tack measured by a probe tack test method of 1 to 50 gf. This probe tack test method is a test method for obtaining the force required to peel the probe in the vertical direction from the test piece after the probe is brought into contact with the test piece for a predetermined time while applying a constant load. And the tack in this invention means the value of the maximum load when this probe tack test is performed on the following conditions, heating the prepreg as a test piece at 40 degreeC, and a probe is peeled off. The probe tack test can be performed using, for example, a probe tack tester according to JISZ0237-1991 (such as a tack tester manufactured by Reska Co., Ltd.).
・ Probe diameter: 5mm
・ Probe speed: 30 mm / min ・ Load for pressing the probe: 100 gf
・ Probe contact time: 2 seconds

  The prepreg 100 can be manufactured, for example, by impregnating a fiber base material with a varnish in which a curable resin composition is dissolved or dispersed in a solvent, and removing the solvent from the varnish by heating at 80 ° C to 180 ° C. . In the prepreg 100, the solvent used in the varnish may remain, but it is preferable that 80% by mass or more of the solvent contained in the varnish is removed. Further, the varnish is applied to the fiber base material in such a ratio that the amount of the curable resin composition in the varnish is 30 to 80% by mass with respect to the total mass of the curable resin composition and the fiber base material in the varnish. It is preferable to impregnate.

  FIG. 2 is a partial cross-sectional view showing an embodiment of a metal foil-clad laminate according to the present invention. A metal foil-clad laminate 200 shown in FIG. 2 includes a substrate 30 obtained by heating and pressing one prepreg 100 and two metal foils 10 provided in close contact with both surfaces of the substrate 30. The

  The metal foil-clad laminate 200 is obtained, for example, by stacking metal foils on both sides of the prepreg 100 and heating and pressurizing the metal foil to cure the curable resin composition in the prepreg 100. The heating at this time is performed at 130 to 250 ° C, preferably 150 to 210 ° C. The pressurization is performed at a pressure in the range of 0.5 to 20 MPa, preferably 1 to 8 MPa.

  As the metal foil 10, a copper foil or an aluminum foil is generally used, but a copper foil is preferable. As the copper foil, one having a thickness of 5 to 200 μm, which is usually used for a copper clad laminate, can be used, but in order to increase the flexibility of the metal foil clad laminate, the thickness is 5 to 18 μm. More preferably. Alternatively, nickel, nickel-phosphorus, nickel-tin alloy, nickel-iron alloy, lead, lead-tin alloy, etc. are used as intermediate layers, and a 0.5-15 μm copper layer and a 10-300 μm copper layer are provided on both sides. Alternatively, a three-layer composite foil or a two-layer composite foil in which aluminum and copper foil are combined can be used.

  The embodiment of the metal foil-clad laminate is not limited to the above aspect. For example, a plurality of prepregs 100 may be used to make the substrate a multilayer fiber reinforced resin layer, or a metal foil may be provided only on one side of the substrate.

  FIG. 3 is a partial cross-sectional view showing an embodiment of a printed wiring board according to the present invention. A printed wiring board 300 shown in FIG. 3 is mainly composed of the substrate 30 and the wiring pattern 11 formed on both surfaces of the substrate 30 and formed of patterned metal foil. A plurality of through holes 70 are formed through the substrate 30 in a direction substantially perpendicular to the main surface, and a metal plating layer 60 having a predetermined thickness is formed on the hole wall of the through hole 70. . The printed wiring board 300 is obtained by forming a wiring pattern on the metal foil-clad laminate 200 described above. The wiring pattern can be formed by a conventionally known method such as a subtractive method. The printed wiring board 300 is particularly preferably used as a so-called flexible printed wiring board.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples.

Example 1
90 g (epoxy resin: 30% by mass) of a methyl ethyl ketone solution of “NC-3000H” (trade name, manufactured by Nippon Kayaku Co., Ltd.) which is an epoxy resin, “EXB-9829” (manufactured by Nippon Kayaku Co., Ltd., 120 g of methyl ethyl ketone solution (trade name) (resin solid content 10% by weight) and 0.2 g of 2-phenylimidazole were mixed and stirred for about 1 hour until the whole became uniform. A slurry in which 20 g of “OP930” (trade name, manufactured by Clariant Japan Co., Ltd.), which is a phosphorus-containing filler (insoluble filler) as a component, was dispersed in methyl ethyl ketone was added and further stirred for 1 hour. Then, 200 g of methyl ethyl ketone solution (acrylic rubber: 20% by mass) of acrylic rubber “HTR860P3” (manufactured by Nagase ChemteX Corporation, trade name, weight average molecular weight: 860,000) was further added and stirred for 1 hour to remove bubbles. Therefore, the varnish which consists of a resin composition and a solvent with which the content rate of phosphorus after removing a solvent was 5 mass% on the basis of the whole resin composition was prepared for 24 hours.

(Example 2)
A varnish comprising a resin composition and a solvent was prepared in the same manner as in Example 1 except that “HM6-1M50” (manufactured by Nagase ChemteX Corporation, trade name, weight average molecular weight: 500,000) was used as the acrylic rubber. .

(Example 3)
A varnish comprising a resin composition and a solvent was prepared in the same manner as in Example 1 except that the amount of OP930 was 40 g.

Example 4
A varnish comprising a resin composition and a solvent was prepared in the same manner as in Example 2 except that the amount of OP930 was 40 g.

(Comparative Example 1)
A varnish composed of a resin composition and a solvent was prepared in the same manner as in Example 1, except that 20 g of “Aerosil 200” (trade name, manufactured by Nippon Aerosil Co., Ltd.), which is silica particles, was used instead of OP930.

(Comparative Example 2)
A varnish comprising a resin composition and a solvent in the same manner as in Example 1, except that 30 g of “PX200” (Daihachi Chemical Co., Ltd.), which is a soluble filler mainly composed of phosphate ester, was used instead of OP930. Was prepared.

(Comparative Example 3)
A varnish comprising a resin composition and a solvent was prepared in the same manner as in Example 1 except that an acrylic rubber having a weight average molecular weight of 40,000 was synthesized and used instead of the acrylic rubber “HTR860P3”.

(Comparative Example 4)
A varnish comprising a resin composition and a solvent was prepared in the same manner as in Example 1 except that an acrylic rubber having a weight average molecular weight of 2 million was synthesized and used instead of the acrylic rubber “HTR860P3”.

<Preparation of prepreg and copper clad laminate>
The varnishes prepared in the above examples and comparative examples were impregnated into a glass cloth “1037” (trade name, manufactured by Asahi Schwer, Inc.) having a thickness of 0.028 mm, respectively, and then heated at 120 ° C. for 20 minutes to remove the solvent. Removal of the prepreg was obtained. A laminate in which an electrolytic copper foil “F2-WS-18” (trade name, manufactured by Furukawa Circuit Foil Co., Ltd.) having a thickness of 18 μm is laminated on both surfaces of the obtained prepreg so that the adhesive surface thereof is combined with the prepreg, 200 A double-sided copper-clad laminate was prepared by heating and pressing at 4 ° C. under a vacuum press condition of 4 MPa for 30 minutes.

<Evaluation of prepreg and double-sided copper-clad laminate>
-Flexibility A test piece having a size of width 10 mm x length 100 mm was cut out from a wiring board obtained by etching the copper foil of the copper clad laminate. This test piece is placed on a table with a pin having a diameter of 0.50 mm, and when the test piece is locally bent by reciprocating the roller once on the test piece in the portion where the pin is pinched, The presence or absence of occurrence was observed.
A: No abnormality B: Whitening due to partial cracking C: Whitening due to overall cracking

-Tack It was performed by the probe tack test method. Specifically, after a 40 ° C. heated probe was pressed against a prepreg heated on a stage heated to 40 ° C., the maximum load when it was peeled off was determined and used as a tack. At this time, the probe diameter was 5 mm, the probe speed was 30 mm / min, the load for pressing the probe was 100 gf, and the probe contact time was 2 seconds. A similar test was performed on five test pieces, and the average value was obtained. As the measuring apparatus, a probe tack tester (Resca Co., Ltd. tack tester) according to JISZ0237-1991 was used.

-Flame retardance The copper foil was removed from the double-sided copper clad laminated board by etching, and the sample of the laminated board formed by heating and pressurizing a prepreg was produced. This sample was subjected to UL-94 vertical combustion test or thin material vertical combustion test. In this test, for example, when the afterflame and afterglow time was less than 10 seconds and the combustion distance was less than 125 mm, V-0 and VTM-0 were determined.

  As shown in Table 1, the tack measured by the robe tack test method of the prepreg produced using the curable resin compositions of Examples 1 to 4 was 10 gf, and was excellent in handleability during pressing. The laminated board obtained by heating and pressurizing this had sufficient flame retardancy. Moreover, this laminated board did not recognize the occurrence of cracks in the flexibility test, and had such a flexibility that it could be bent arbitrarily.

  On the other hand, the tack of the prepreg produced using the curable resin composition of Comparative Example 1 was 10 gf, but the flame retardancy of the laminate obtained using this was HB, which was insufficient. Met. The prepreg produced using the curable resin composition of Comparative Example 2 had a tack of 210 gf and was difficult to handle during pressing. The laminate obtained by using the curable resin composition of Comparative Example 3 has low flame retardancy with VTM-1 and V-1 in the UL-94 combustion test, and also has low flexibility and cracks when bent. Occurred and whitened. The laminate obtained using the curable resin composition of Comparative Example 4 had low flexibility, and cracks occurred during bending.

It is a perspective view which shows one Embodiment of the prepreg by this invention. It is a fragmentary sectional view showing one embodiment of a metal foil tension laminate sheet by the present invention. It is a fragmentary sectional view showing one embodiment of a printed wiring board by the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Metal foil, 11 ... Wiring pattern, 30 ... Board | substrate, 60 ... Metal plating layer, 70 ... Through-hole, 100 ... Pre-preg, 200 ... Metal foil clad laminated board, 300 ... Printed wiring board.

Claims (12)

A prepreg having a fiber base material, a curable resin composition containing acrylic rubber and a phosphorus-containing filler and impregnating the fiber base material,
The acrylic rubber has a weight average molecular weight of 50,000 to 1,500,000, and the acrylic rubber has an epoxy group at a ratio of an epoxy value of 2 to 18 equivalents / kg,
The phosphorus-containing filler contains a filler containing an aluminum phosphinate that exists in solid particles in the cured product of the curable resin composition.
Prepreg . The prepreg of Claim 1 whose average particle diameter of the said phosphorus containing filler is 0.1-30 micrometers. The prepreg of Claim 1 or 2 in which the said curable resin composition contains 0.1-10 mass% phosphorus on the basis of the whole quantity of the said curable resin composition. The curable resin composition, red phosphorus, phosphoric acid ester, ammonium polyphosphate contains at least one flame retardant selected from the group consisting of melamine polyphosphate and phosphazene compounds, either of claims 1-3 one The prepreg according to Item. The curable resin composition, calcium molybdate, aluminum hydroxide, magnesium hydroxide, containing at least one flame retardant selected from the group consisting of calcium hydroxide and hydrotalcite, any claim 1-3 The prepreg according to claim 1 . The prepreg according to any one of claims 1 to 5 , wherein the curable resin composition further contains a thermosetting resin. The prepreg according to claim 6 , wherein the thermosetting resin is an epoxy resin. The prepreg as described in any one of Claims 1-7 whose tack measured by a probe tack test method is 1-50 gf. The prepreg as described in any one of Claims 1-8 whose thickness of the said fiber base material is 100 micrometers or less. Substrate obtained by applying heat and pressure to the prepreg according to any one of claims 1-9. A metal foil-clad laminate comprising the substrate according to claim 10 and a metal foil provided on at least one surface of the substrate. A printed wiring board comprising: the substrate according to claim 10 ; and a wiring pattern made of a metal foil provided on at least one surface of the substrate.

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