JP2009231222A - Insulating resin sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insulating resin sheet in which a sheetlike fiber base material included in a prepreg is not exposed on the surface of an insulating layer concerning to the insulating resin sheet formed by the prepreg in order to form the insulating layer of a multilayer printed wire board. <P>SOLUTION: The insulating resin sheet includes a cured prepreg layer, and a thermosetting resin composition layer formed on both sides of the cured prepreg layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an insulating resin sheet prepared from a prepreg obtained by impregnating a sheet-like fiber base material with a thermosetting resin composition, and a method for producing a multilayer printed wiring board using the insulating resin sheet.

  Conventionally, as a manufacturing technique of a multilayer printed wiring board, a manufacturing method by a built-up method in which insulating layers and conductor layers are alternately stacked on a core substrate is known. According to this manufacturing method, for the formation of the insulating layer, an adhesive film in which a thermosetting resin layer is formed exclusively on a plastic film is used. This adhesive film is laminated (laminated) on the inner circuit board, and the plastic film is laminated. After peeling, the insulating layer is formed by thermosetting the thermosetting resin. On the other hand, due to recent needs for miniaturization of electronic devices and electronic parts, multilayer printed wiring boards tend to be made thinner and thinner, for example, requiring a thinner or omitted core substrate. Thus, in order to reduce the thickness of a multilayer printed wiring board, in order to maintain the mechanical strength of the multilayer printed wiring board, it is considered effective to apply a prepreg as a material for forming an interlayer insulating layer.

  For example, Patent Document 1 discloses a method of forming an insulating layer on a circuit board by sheet-feeding glass cloth prepreg and copper foil with a vacuum pressure laminator. However, due to the recent trend toward smaller and thinner electronic devices, there is an increasing demand for fine wiring even in multilayer printed wiring boards. To meet these demands, a conductor layer is formed from copper foil. Instead, it is advantageous to form the conductor layer by plating by a semi-additive method.

  As prepregs for forming an interlayer insulating layer of a multilayer printed wiring board, Patent Documents 2 and 3 disclose insulating resin sheets in which a thermosetting resin composition layer is formed on the prepreg.

JP 2003-0332740 A JP 2003-249664 A JP 2003-313324 A

  In the manufacturing method of a multilayer printed wiring board by a built-up method using an adhesive film, a thermosetting resin composition layer is laminated using a vacuum laminator, and then the insulating layer is formed by thermosetting the layer. The After such an insulating layer is formed, a conductor layer can be formed by plating by a semi-additive method. On the other hand, in the case of the prepreg, if the prepreg is made to follow the circuit irregularities of the inner layer circuit board and the fluidity of the thermosetting resin composition impregnated in the prepreg is secured so that the circuit irregularities can be sufficiently embedded, In the thermosetting process, the fluidity of the resin becomes too high, so that the resin oozes out and the fiber base material such as glass cloth is exposed on the surface of the insulating layer, which causes problems in the formation of the insulating layer. .

  Therefore, as a means for causing the prepreg to follow the circuit irregularities of the inner circuit board and sufficiently embedding the resin composition in the circuit irregularities, there is a method of further providing a thermosetting resin composition layer on the prepreg as in Patent Documents 2 and 3. It is considered effective. When the inventors laminated an insulating resin sheet having a thermosetting resin composition laminated on both surfaces of a prepreg with a vacuum laminator, the insulating resin sheet sufficiently followed the circuit irregularities of the inner circuit board, and the circuit irregularities were It was found that the embeddability was also good. On the other hand, the laminated insulating resin sheet has an uneven surface reflecting the circuit unevenness. Therefore, in order to smooth the surface of the insulating resin sheet, when the adhesive sheet is heated and pressurized with a metal plate under normal pressure, the thermosetting resin composition layer on the surface of the insulating resin sheet flows, so that the unevenness of the circuit is reflected. Thus, a phenomenon has been found in which the thickness of some of the thermosetting resin composition layers is reduced. In addition, when the insulating resin sheet is thermally cured to form an insulating layer, and then the surface of the insulating layer is roughened and a conductor layer is formed by plating, the prepreg is formed from the portion where the thickness of the thermosetting resin composition layer is reduced. A phenomenon was found in which the fibrous sheet base material was exposed and problems occurred in the formation of the conductor layer.

  Accordingly, an object of the present invention is to provide an insulating resin sheet in which the fibrous sheet base material is not exposed as described above when a multilayer printed wiring board is produced from the insulating resin sheet having the fibrous sheet base material. There is.

  As a result of intensive studies to solve the above problems, the present inventors have produced an insulating resin sheet comprising a cured prepreg layer and a cured resin composition layer formed on both surfaces of the cured prepreg layer, to produce a multilayer printed wiring board. As a result, it was found that the exposure of the fibrous sheet base material described above can be suppressed even when the surface of the formed insulating layer is roughened, and the present invention has been completed.

That is, the present invention includes the following contents.
[1] An insulating resin sheet comprising a cured prepreg layer and a thermosetting resin composition layer formed on both surfaces of the cured prepreg layer.
[2] The insulating resin sheet according to [1], wherein the cured prepreg is obtained by thermosetting a prepreg obtained by impregnating a sheet-like fiber base material with a thermosetting resin composition.
[3] The insulating resin sheet is arranged on the inner circuit board so that the thermosetting resin composition layer is in contact with both surfaces or one surface of the inner circuit board, and the insulating resin sheet is placed under the reduced pressure through the elastic material. Laminating step of laminating on the inner layer circuit board by heating and pressurizing, (2) Smoothing smoothing the insulating resin sheet by heating and pressurizing the laminated insulating resin sheet with a metal plate or metal roll And (3) the above-mentioned [1] or [2] used in a method for producing a multilayer printed wiring board comprising a thermosetting step of forming an insulating layer by thermosetting a smoothed insulating resin sheet The insulating resin sheet as described.
[4] The above-mentioned [3], wherein the glass transition temperature of the cured prepreg is (P-18) or higher when the higher one of the temperature of the laminating step and the temperature of the smoothing step is P ° C. Insulating resin sheet.
[5] The above-mentioned [3], wherein the glass transition temperature of the cured prepreg is (P-12) or higher when the higher one of the temperature in the laminating step and the temperature in the smoothing step is P ° C. Insulating resin sheet.
[6] The above-mentioned [3], wherein the glass transition temperature of the cured prepreg is (P-10) or higher when the higher one of the temperature of the laminating step and the temperature of the smoothing step is P ° C. Insulating resin sheet.
[7] The insulating resin sheet according to any one of [1] to [6], wherein a protective film is formed on one side or both sides of the thermosetting resin composition layer.
[8] The insulating resin sheet according to the above [7], wherein the protective film is a polyethylene terephthalate film.
[9] A multilayer printed wiring board in which an insulating layer is formed of the insulating resin sheet according to any one of [1] to [8].
[10] (1) The insulating resin sheet according to any one of the above [1] to [8] is disposed on the inner circuit board so that the thermosetting resin composition layer is in contact with both surfaces or one surface of the inner circuit board. , By laminating on the inner circuit board by heating and pressurizing through an elastic material under reduced pressure, (2) by heating and pressurizing the laminated insulating resin sheet with a metal plate or a metal roll A method for producing a multilayer printed wiring board, comprising: a smoothing step of smoothing the insulating resin sheet; and (3) a thermosetting step of forming an insulating layer by thermosetting the smoothed insulating resin sheet.
[11] The method according to [10], wherein the insulating resin sheet is heated and pressed from above the protective film in the laminating step and the smoothing step.
[12] Drilling step for drilling in the insulating layer, roughening step for roughening the insulating layer, plating step for forming a conductor layer by plating on the surface of the roughened insulating layer, and circuit for forming a circuit in the conductor layer The production method according to the above [10] or [11], further comprising a forming step.

  Even when laminated on the inner layer circuit board by a vacuum laminator, the insulating resin sheet sufficiently follows the circuit irregularities of the inner layer circuit board, and the embedding property of the circuit irregularities is also good. Further, even when the surface of the insulating resin sheet is smoothed after lamination, the phenomenon that the thickness of the resin composition layer is reduced reflecting circuit irregularities can be suppressed. Therefore, according to the present invention, after the insulating layer is formed by thermosetting, even if the surface of the insulating layer is roughened, the fiber base material of the prepreg is not exposed, and the conductor layer can be satisfactorily formed by plating. And a highly reliable multilayer printed wiring board can be manufactured.

  Hereinafter, the present invention will be described with reference to preferred embodiments.

  The “cured prepreg” in the present invention is obtained by thermosetting a prepreg obtained by impregnating a sheet-like fiber base material with a thermosetting resin composition. The thermosetting resin composition does not necessarily need to be completely thermoset, and may be cured to such an extent that the effects of the present invention are exhibited. A general prepreg used for forming an insulating layer such as a printed wiring board usually needs to maintain adhesion in a laminating process or the like laminated on an inner circuit board. Therefore, the thermosetting resin composition impregnated in a general prepreg has fluidity (flowability). Therefore, even if such a general prepreg is, for example, the B stage, the reactivity of the impregnated thermosetting resin composition is significantly lower than that of the cured prepreg, and its glass transition temperature is usually not measured. Is possible. Moreover, even when it is measurable, the glass transition temperature is at least room temperature or lower.

When producing a multilayer printed wiring board using the insulating resin sheet of the present invention, generally, (1) the insulating resin sheet is applied to the inner layer circuit board so that the thermosetting resin composition layer is in contact with both surfaces or one surface of the inner circuit board. Laminating step of laminating and laminating on the inner circuit board by placing and heating and pressurizing through an elastic material under reduced pressure, (2) heating and pressurizing the laminated insulating resin sheet with a metal plate or a metal roll It is manufactured through a smoothing step and (3) a thermosetting step of forming an insulating layer by thermosetting the smoothed insulating resin sheet. At this time, if the glass transition temperature of the cured prepreg is too low, in the laminating step and / or smoothing step, the holding ability of the sheet-like fiber substrate by the cured product is lowered, and the substrate is caused by the expansion of the sheet-like fiber substrate. There is a tendency for exposure problems to become apparent. Therefore, the cured prepreg is preferably cured until it has a sufficiently high glass transition temperature so that exposure due to expansion of the sheet-like fiber substrate does not occur in the laminating step and the smoothing step. The appropriate glass transition temperature varies depending on the temperature of the laminating step and the smoothing step, but preferably (P-18) ° C. when the higher one of the temperature of the laminating step and the temperature of the smoothing step is P ° C. It is above, More preferably, it is (P-12) degree C or more, Most preferably, it is (P-10) degree C or more. In addition, the “temperature of the laminating process” and the “temperature of the smoothing process” in the present application are more specifically the maximum temperature when heating in the laminating process and the maximum temperature when heating in the smoothing process, respectively. Refers to temperature. For example, when the laminating step and the smoothing step are both performed at 120 ° C., the glass transition temperature of the thermosetting resin composition needs to be at least 102 ° C. or higher. In general, since the laminating step and the smoothing step are performed at least at 70 ° C. or higher, specifically, the glass transition temperature needs to be at least 52 ° C. or higher. The upper limit of the glass transition temperature is not particularly limited, but the glass transition temperature of a generally cured thermosetting resin composition is often 300 ° C. or less, and this can be set as a general upper limit.
For example, as described above, when the prepreg is cured to such an extent that a glass transition temperature of 52 ° C. or higher is observed, the thermosetting resin composition impregnated in the prepreg substantially flows in the laminating step. Or has little or no adhesion. Therefore, this cured prepreg (for example, a prepreg cured to such an extent that a glass transition temperature of 52 ° C. or higher is observed) is laminated on the inner circuit board alone without forming a thermosetting resin composition layer on both sides. However, it is impossible to form an insulating layer by embedding a circuit. In this respect, the cured prepreg is clearly distinguished from a general prepreg used for forming an insulating layer such as a printed wiring board.

  The “glass transition temperature” as used in the present application is a value indicating heat resistance, and is determined according to the method described in JIS K 7179. Specifically, thermomechanical analysis (TMA), dynamic mechanical analysis (DMA) It is measured using etc. Examples of thermomechanical analysis (TMA) include TMA-SS6100 (manufactured by Seiko Instruments Inc.), TMA-8310 (manufactured by Rigaku Corporation), and the like. Examples of dynamic mechanical analysis (DMA) include DMS-6100. (Manufactured by Seiko Instruments Inc.). Further, when the glass transition temperature is higher than the decomposition temperature and the glass transition temperature is not actually observed, the decomposition temperature can be regarded as the glass transition temperature in the present application. The decomposition temperature here is defined as a temperature at which the mass reduction rate is 5% when measured according to the method described in JIS K 7120.

As a sheet-like fiber base material, what is conventionally used as a base material for prepregs, such as a glass cloth, an aramid nonwoven fabric, a liquid crystal polymer nonwoven fabric, can be used, for example. In particular, when it is used for forming an insulating layer of a multilayer printed wiring board, a thin one having a thickness of 30 μm or less is preferably used, and particularly preferably 10 to 30 μm. As a specific example of the sheet-like fiber base material, as a glass cloth base material, for example, Asahi Sebel Co., Ltd. Style 1027MS (warp density 75/25 mm, weft density 75/25 mm, fabric weight 20 g / m ² , thickness 19 μm), Asahi Sebel Co., Ltd. style 1037MS (warp density 70/25 mm, weft density 73/25 mm, fabric weight 24 g / m ² , thickness 28 μm), Arisawa Seisakusho 1037 NS (War density: 72/25 mm, Weft density: 69/25 mm, Fabric weight: 23 g / m ² , Thickness: 21 μm), Arisawa Seisakusho 1027NS (War density: 75/25 mm, Weft density: 75/25 mm, Fabric (Weight: 19.5 g / m ² , thickness: 16 μm), Arisawa Seisakusho 1015NS (warp density 95/25 mm, weft density 95/25 mm) , Cloth weight 17.5 g / m ² , thickness 15 μm), 1000 NS manufactured by Arisawa Manufacturing Co., Ltd. (warp density 85/25 mm, weft density 85/25 mm, cloth weight 11 g / m ² , thickness 10 μm) Can be mentioned. Examples of the liquid crystal polymer non-woven fabric include vesicles of an aromatic polyester non-woven fabric manufactured by Kuraray Co., Ltd. (weight per unit area: 6 to 15 g / m ² ) and Vectran.
As a sheet-like fiber substrate, glass cloth is widely used. Glass cloth used for multilayer printed wiring boards is generally manufactured by weaving yarns with several tens to hundreds of glass filaments bundled with an automatic loom, etc., and usually prevents yarn fraying and scuffing when the yarns are bundled. To be twisted. For this reason, in the prepreg, some glass fibers are not evenly arranged, and overlapping places locally exist. The place where the glass fibers overlap is thicker than the other places. In addition, in the prepreg manufacturing process, the glass cloth may exist not in the center of the prepreg but in the vicinity of the surface due to the slack of the glass cloth. In general, the exposure of the sheet-like fiber base material in the insulating resin sheet is particularly at a portion where the thickness of the sheet-like fiber base material is locally large, or where a part of the sheet-like fiber base material is in the vicinity of the surface. Remarkably easy to appear.

  The thermosetting resin composition impregnated into the sheet-like fiber base material can be used without particular limitation as long as it is suitable for the insulating layer of the multilayer printed wiring board. Specific examples of such a thermosetting resin composition include an epoxy resin, a cyanate ester resin, a phenol resin, a bismaleimide-triazine resin, a polyimide resin, an acrylic resin, a vinylbenzyl resin, and a curing agent thereof. And a composition containing at least. Among them, a composition containing an epoxy resin as the thermosetting resin is preferable, and for example, a composition containing an epoxy resin, a thermoplastic resin, and a curing agent is preferable.

  Examples of the epoxy resin include bisphenol A type epoxy resin, biphenyl type epoxy resin, naphthol type epoxy resin, naphthalene type epoxy resin, bisphenol F type epoxy resin, phosphorus-containing epoxy resin, bisphenol S type epoxy resin, and alicyclic epoxy resin. , Aliphatic chain epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolak type epoxy resin, epoxy resin having butadiene structure, diglycidyl etherified product of bisphenol, diglycidyl etherified product of naphthalenediol, phenol Glycidyl etherified products of alcohols, diglycidyl etherified products of alcohols, and alkyl-substituted products, halides and hydrogenated products of these epoxy resins. It is. These epoxy resins may be used alone or in combination of two or more.

  Among these, the epoxy resin has a bisphenol A type epoxy resin, a naphthol type epoxy resin, a naphthalene type epoxy resin, a biphenyl type epoxy resin, and a butadiene structure from the viewpoint of heat resistance, insulation reliability, and adhesion to a metal film. Epoxy resins are preferred. Specific examples of such an epoxy resin include a liquid bisphenol A type epoxy resin (“Epicoat 828EL” manufactured by Japan Epoxy Resin Co., Ltd.), a naphthalene type bifunctional epoxy resin (“HP4032” manufactured by Dainippon Ink and Chemicals, Inc.), “ HP4032D]), naphthalene type tetrafunctional epoxy resin (“HP4700” manufactured by Dainippon Ink and Chemicals, Inc.), naphthol type epoxy resin (“ESN-475V” manufactured by Tohto Kasei Co., Ltd.), epoxy resin having a butadiene structure ( "PB-3600" manufactured by Daicel Chemical Industries, Ltd.), epoxy resins having a biphenyl structure ("NC3000H", "NC3000L" manufactured by Nippon Kayaku Co., Ltd., "YX4000" manufactured by Japan Epoxy Resins Co., Ltd.), etc.) It is done.

  A thermoplastic resin can be blended with the thermosetting resin composition for the purpose of imparting appropriate flexibility to the cured resin composition. Examples of the thermoplastic resin include phenoxy resin, polyvinyl acetal resin, polyimide, polyamideimide, polyethersulfone, polysulfone, and the like. Any one of these thermoplastic resins may be used alone, or two or more thereof may be used in combination. The thermoplastic resin is preferably blended at a rate of 0.5 to 60% by weight, preferably 3 to 50% by weight, when the nonvolatile component of the thermosetting resin composition is 100% by weight. Is more preferable.

  Examples of commercially available phenoxy resins include FX280 and FX293 manufactured by Toto Kasei Co., Ltd., YX8100, YL6954, and YL6974 manufactured by Japan Epoxy Resin Co., Ltd.

  As the polyvinyl acetal resin, a polyvinyl butyral resin is preferable. Examples of commercially available polyvinyl acetal resin include, for example, Denka Butyral 4000-2, 5000-A, 6000-C, 6000-EP, manufactured by Denki Kagaku Kogyo Co., Ltd. Sekisui Chemical Co., Ltd. S REC BH series, BX series, KS series, BL series, BM series, etc. are mentioned.

  As a commercial item of polyimide, for example, polyimide “Rika Coat SN20” and “Rika Coat PN20” manufactured by Shin Nippon Rika Co., Ltd. may be mentioned. Also, linear polyimides (described in JP-A-2006-37083) obtained by reacting a bifunctional hydroxyl group-terminated polybutadiene, a diisocyanate compound and a tetrabasic acid anhydride, and polysiloxane skeleton-containing polyimides (JP-A-2002). Modified polyimides such as those described in JP-A No. 12667 and JP-A No. 2000-319386.

  Examples of commercially available polyamideimides include polyamideimides “Vilomax HR11NN” and “Vilomax HR16NN” manufactured by Toyobo Co., Ltd. In addition, modified polyamideimides such as polysiloxane skeleton-containing polyamideimides “KS9100” and “KS9300” manufactured by Hitachi Chemical Co., Ltd. may be mentioned.

  Examples of commercially available products of polyethersulfone include polyethersulfone “PES5003P” manufactured by Sumitomo Chemical Co., Ltd.

  Examples of commercially available products of polysulfone include polysulfone “P1700” and “P3500” manufactured by Solven Advanced Polymers Co., Ltd.

  Examples of the curing agent include amine-based curing agents, guanidine-based curing agents, imidazole-based curing agents, phenol-based curing agents, naphthol-based curing agents, acid anhydride-based curing agents, or epoxy adducts and microcapsules thereof. Examples include cyanate ester resins. Among these, a phenol type curing agent, a naphthol type curing agent, and a cyanate ester resin are preferable. These curing agents may be used alone or in combination of two or more.

  As a commercial item of a phenol type hardening | curing agent and a naphthol type hardening | curing agent, for example, MEH-7700, MEH-7810, MEH-7851 (made by Meiwa Kasei Co., Ltd.), NHN, CBN, GPH (made by Nippon Kayaku Co., Ltd.) ), SN170, SN180, SN190, SN475, SN485, SN495, SN375, SN395 (manufactured by Tohto Kasei Co., Ltd.), LA7052, LA7054, LA3018, LA1356 (manufactured by Dainippon Ink & Chemicals, Inc.), and the like.

  Examples of the cyanate ester resin include bisphenol A dicyanate, polyphenol cyanate (oligo (3-methylene-1,5-phenylene cyanate), 4,4′-methylenebis (2,6-dimethylphenyl cyanate), 4,4′- Ethylidene diphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis (4-cyanate) phenylpropane, 1,1-bis (4-cyanatephenylmethane), bis (4-cyanate-3,5-dimethylphenyl) Bifunctional cyanate resins such as methane, 1,3-bis (4-cyanatephenyl-1- (methylethylidene)) benzene, bis (4-cyanatephenyl) thioether, bis (4-cyanatephenyl) ether, phenol novolac, cresol No Examples thereof include polyfunctional cyanate resins derived from racks, prepolymers in which these cyanate resins are partially triazines, etc. Specific examples of such cyanate ester resins include phenol novolac type polyfunctional cyanate ester resins (Lonza Japan Ltd.). ) “PT30”, cyanate equivalent 124), or a prepolymer in which a part or all of bisphenol A dicyanate is triazine-modified into a trimer (“BA230” manufactured by Lonza Japan Co., Ltd., cyanate equivalent 232), and the like. .

  The mixing ratio of the epoxy resin and the curing agent is such that when a phenolic curing agent or a naphthol curing agent is used, the phenolic hydroxyl group equivalent of these curing agents is 0.4 to 2.0 with respect to the epoxy equivalent 1 of the epoxy resin. The ratio that is in the range is preferable, and the ratio that is in the range of 0.5 to 1.0 is more preferable. When using a cyanate ester resin, a ratio in which the cyanate equivalent is in the range of 0.3 to 3.3 with respect to the epoxy equivalent 1 is preferable, and a ratio in the range of 0.5 to 2.0 is more preferable.

  The thermosetting resin composition may further contain a curing accelerator in addition to the curing agent. Examples of the curing accelerator include imidazole compounds and organic phosphine compounds, and specific examples include 2-methylimidazole and triphenylphosphine. When using a hardening accelerator, it is preferable to use a hardening accelerator in 0.1-3.0 mass% with respect to an epoxy resin. When using a cyanate ester resin as an epoxy resin curing agent, an organometallic compound conventionally used as a curing catalyst in a system in which an epoxy resin composition and a cyanate compound are used together for the purpose of shortening the curing time. May be added. Examples of such organometallic compounds include organic copper compounds such as copper (II) acetylacetonate, organic zinc compounds such as zinc (II) acetylacetonate, cobalt (II) acetylacetonate, and cobalt (III) acetyl. Examples include organic cobalt compounds such as acetonate. These organic metal compounds may be used alone or in combination of two or more. The amount of the organometallic compound added is usually in the range of 10 to 500 ppm, more preferably in the range of 25 to 200 ppm in terms of metal, relative to the cyanate ester resin.

  Further, the thermosetting resin composition can contain an inorganic filler in order to reduce the thermal expansion of the cured resin composition. Examples of the inorganic filler include silica, alumina, mica, mica, silicate, barium sulfate, magnesium hydroxide, titanium oxide, and the like. Among these, silica and alumina are preferable, and silica is particularly preferable. The average particle size of the inorganic filler is preferably 3 μm or less, and particularly preferably 1.5 μm or less, from the viewpoint of insulation reliability. The content of the inorganic filler is preferably 20 to 60% by mass, and more preferably 20 to 50% by mass when the nonvolatile component of the thermosetting resin composition is 100% by mass.

  Furthermore, the thermosetting resin composition can contain other components as necessary. Other components include, for example, organic phosphorus flame retardants, organic nitrogen-containing phosphorus compounds, nitrogen compounds, silicone flame retardants, flame retardants such as metal hydroxides; organic filling such as silicon powder, nylon powder, fluorine powder, etc. Agents; thickeners such as olben and benton; silicone-based, fluorine-based and other polymeric antifoaming agents or leveling agents; imidazole-based, thiazole-based, triazole-based, and silane-based coupling agents; phthalocyanine -Coloring agents such as blue, phthalocyanine green, iodin green, disazo yellow, carbon black and the like.

  The cured prepreg of the present invention can be obtained by thermosetting an ordinary prepreg produced by a production method known per se.

  Examples of the usual method for producing a prepreg include known hot melt methods and solvent methods. In the hot melt method, the thermosetting resin composition is once coated on a release paper having good peelability from the composition without dissolving the thermosetting resin composition in an organic solvent, and then laminated on a glass cloth. Alternatively, it is a method for producing a prepreg by direct coating with a die coater or the like. The solvent method is to impregnate the sheet-like fiber substrate with the resin composition varnish by immersing the sheet-like fiber substrate in a resin composition varnish obtained by dissolving the thermosetting resin composition in an organic solvent, and then drying. It is a method to make it. Also, an adhesive film (thermosetting resin composition film) made of a thermosetting resin composition laminated on a plastic film is laminated continuously under heating and pressure conditions from both sides of the sheet-like fiber substrate. Can also be prepared. Examples of the organic solvent for preparing the varnish include ketones such as acetone, methyl ethyl ketone and cyclohexanone, ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, acetates such as carbitol acetate, cellosolve, butyl Examples thereof include carbitols such as carbitol, aromatic hydrocarbons such as toluene and xylene, dimethylformamide, dimethylacetamide, and N-methylpyrrolidone. These organic solvents may be used alone or in combination of two or more.

  The drying conditions in the solvent method are not particularly limited, but if a large amount of organic solvent remains in the prepreg, it will cause swelling after curing, so the content of the organic solvent in the thermosetting resin composition is usually 5% by weight. % Or less, preferably 2% by weight or less. The specific drying conditions vary depending on the curability of the thermosetting resin composition and the amount of the organic solvent in the varnish. For example, in a varnish containing 30 to 60% by weight of an organic solvent, it is usually 3 at 80 to 180 ° C. It can be dried for about 13 minutes. Since a normal prepreg used for a circuit board or the like retains adhesive ability, it is important to prevent the thermosetting resin composition from being cured as much as possible during drying. On the other hand, in the present invention, a cured prepreg obtained by curing a thermosetting resin composition is used. It does not specifically limit as hardening conditions, For example, hardening temperature can be performed in 130-200 degreeC and hardening time in the range of 15-60 minutes. The prepreg may be compression cured by applying pressure. A plurality of layers may be compressed and cured. In the case of the solvent method, a cured prepreg may be prepared by performing a drying step and a curing step together. The conditions are not particularly limited. For example, in a varnish containing 30 to 60% by weight of an organic solvent, it can be prepared by drying at a temperature of about 80 to 200 ° C. for about 5 to 40 minutes.

  The thickness of the cured prepreg layer is not particularly limited, but is usually preferably 12 to 70 μm, and more preferably 12 to 60 μm from the viewpoint of the cost of the glass cloth used and the desired thinness as an insulating resin sheet. In addition, this thickness can be easily controlled by adjusting the amount of impregnation of the thermosetting resin composition.

  As the thermosetting resin used for the thermosetting resin composition layer formed on both surfaces of the cured prepreg layer, the same thermosetting resin composition as that used for the prepreg described above can be used. In addition, the kind of thermosetting resin composition used for a thermosetting resin composition layer may be the same as that of the thermosetting resin composition used for a prepreg layer, or may differ. Moreover, the thermosetting resin composition used for a thermosetting resin composition layer may use the same thing on both surfaces, and may use a different kind of thing.

Examples of the method for forming the thermosetting resin composition layer on both surfaces of the cured prepreg layer include the following three methods.
As a first method, a method of forming a thermosetting resin layer by impregnating a resin varnish with a cured prepreg and drying it can be mentioned. In addition, as this resin varnish, the thing similar to the varnish of an above described thermosetting resin composition can be used. The viscosity of the resin varnish is preferably in the range of 10 to 10,000 cps at 25 ° C., particularly preferably in the range of 100 cps to 1000 cps. The solid content of the resin varnish is preferably in the range of 10% to 60%, and more preferably in the range of 20% to 50%. The drying is preferably performed at 60 to 150 ° C. for 10 to 20 minutes.
As a second method, the resin varnish is coated on a protective film, dried to obtain an adhesive film (thermosetting resin composition film), and then laminated on both sides of the cured prepreg. Is mentioned. In order to accurately control the film thickness, such coating preferably uses a closed type die coater, and drying is preferably performed at 60 ° C. to 150 ° C. for about 10 minutes to 20 minutes.
Further, as a third method, there is a method in which the resin varnish is directly applied and dried on one surface of a cured prepreg, and then the resin varnish is applied and dried on the other surface. In order to accurately control the film thickness, it is preferable to use a closed type die coater, and drying is preferably performed at 60 ° C. to 150 ° C. for about 10 minutes to 20 minutes.

  The thickness of the thermosetting resin composition layer is such that the layer in contact with the inner circuit board (hereinafter also referred to as B layer) is 1 to 1 from the viewpoint of embedding the thermosetting resin composition layer in the circuit. It is preferable that it is 50 micrometers, and it is more preferable that it is 1-25 micrometers. The other layer (hereinafter sometimes referred to as A layer) is preferably 1 to 30 μm, more preferably 1 to 25 μm from the viewpoint of wiring formation. In addition, the layer (B layer) in contact with the inner layer circuit board needs to have fluidity that can be laminated or laminated without voids on the wiring portion of the inner layer circuit board. For that purpose, the minimum melt viscosity is preferably in the range of 200 to 7000 poise, and particularly preferably in the range of 400 to 3000 poise. In the other layer (A layer), it is necessary that the copper wiring can be easily formed. Therefore, it is required that the circuit can be formed by the semi-additive method.

  In general, the thickness of the insulating resin sheet is preferably 14 to 150 μm, more preferably 14 to 110 μm. A prepreg that can make the thickness of the insulating resin sheet less than 14 μm is difficult to produce at present, and if the thickness of the insulating resin sheet exceeds 150 μm, it is not suitable for thinning the multilayer printed wiring board. Become.

  The insulating resin sheet preferably has a protective film formed on both sides for the purpose of preventing dents and scratches on the surface and preventing foreign matter from adhering. Such a protective film is preferably a plastic film such as a polyethylene terephthalate (PET) film, a polypropylene film, or a polyethylene film. The thickness is preferably between 5 μm and 100 μm. In the laminating step and the smoothing step, it is preferable to heat and pressurize the protective film from the viewpoint of preventing the resin from adhering to the apparatus. In this case, it is preferable to use a PET film having excellent cost and heat resistance as the protective film. As the protective film, a film having a release layer in which a surface on which the thermosetting resin composition layer is formed is subjected to a release treatment may be used. Examples of the release agent used for the release treatment include a silicone release agent and an alkyd resin release agent. A commercially available plastic film with a release layer may be used, and a preferable one is, for example, a PET film having a release layer mainly composed of an alkyd resin release agent, Lintec Corporation. Examples include SK-1, AL-5, and AL-7. Further, the plastic film may be subjected to mat treatment or corona treatment, and a release layer may be formed on the treated surface.

  The method for producing a multilayer printed wiring board of the present invention includes a step of laminating (laminating) an insulating resin sheet on at least one side of an inner layer circuit board, and curing the insulating resin sheet to form an insulating layer. Here, lamination of the insulating resin sheet on the inner layer circuit board is basically performed using one insulating resin sheet (one layer), but two or more (two layers) may be stacked and laminated. Note that the thickness of the insulating layer basically follows the thickness (total thickness) of the insulating resin sheet. Therefore, the thickness of the insulating layer is usually 14 to 150 μm, more preferably 14 to 110 μm.

In the laminating step, the insulating resin sheet is heated and pressurized under reduced pressure, and laminated on the inner layer circuit board. The heating and pressurization in the laminating step can be performed by pressing a heated metal plate such as a SUS mirror plate from the protective film side. At that time, it is preferable that the metal plate is not pressed directly, but is pressed through an elastic material such as heat-resistant rubber so that the insulating resin sheet sufficiently follows the circuit irregularities of the inner layer circuit board. The metal plate and the elastic material are not necessarily in contact with each other, and lamination may be performed by pressing air while applying pressure to the elastic material with compressed air in the presence of air between the metal plate and the elastic material. In addition, the temperature of this press becomes like this. Preferably it is 70-140 degreeC, More preferably, it is 80-130 degreeC. The pressure of such a press is preferably in the range of ^{1~11kgf / cm 2 (9.8 × 10} 4 ~107.9 × 10 4 N / m 2). In general, the laminating step is performed under reduced pressure in order to prevent generation of voids, and the air pressure is preferably under a reduced pressure of 20 mmHg (26.7 hPa) or less.

  After the laminating step, the laminated insulating resin sheet is smoothed, preferably by hot pressing with a metal plate or metal roll. The smoothing step is performed by heating and pressurizing the insulating resin sheet using a heated metal plate such as a SUS mirror plate or a metal roll. The smoothing step is preferably performed under normal pressure (atmospheric pressure). The smoothing step is more preferably performed with a metal plate. As such heating and pressurizing conditions, the same conditions as in the laminating step can be used.

  The laminating step and the smoothing step in the present invention can be performed continuously by a commercially available vacuum laminator. Examples of the commercially available vacuum laminator include a vacuum pressure laminator manufactured by Meiki Seisakusho, a vacuum applicator manufactured by Nichigo Morton, and the like.

  After the laminating step and / or the smoothing step, a thermosetting step is performed. In the thermosetting step, the insulating resin sheet is thermoset to form an insulating layer. The thermosetting conditions vary depending on the type of the thermosetting resin composition, but generally the curing temperature is in the range of 150 to 200 ° C., and the curing time is in the range of 15 to 60 minutes.

  The method for producing a multilayer printed wiring board of the present invention may further include a drilling step for drilling an insulating layer and a roughening step for roughening the insulating layer. In addition, these processes can be performed according to the various methods used for manufacture of a multilayer printed wiring board well-known to those skilled in the art. Moreover, in the manufacturing method of the multilayer printed wiring board of this invention, the process of peeling the remaining protective film may be further included after a lamination process, a smoothing process, a thermosetting process, or a punching process. As long as the protective film has been subjected to a release treatment, it can be peeled off from the thermally cured insulating resin sheet (insulating layer). The protective film may be peeled off manually or mechanically by an automatic peeling device.

  The drilling step can be performed, for example, by forming a hole such as a via hole or a through hole in the insulating layer with a laser such as a drill, a carbon dioxide laser, or a YAG laser, or a plasma. In a multilayer printed wiring board, formation of a through hole (through hole) is generally performed in a core substrate, and a built-up insulating layer is generally conducted by a via hole. Moreover, a mechanical drill is generally used for forming the through hole.

  A roughening process can be performed by processing the insulating layer surface with oxidizing agents, such as alkaline permanganic acid aqueous solution, for example. The roughening process may also serve as a desmear process for holes such as via holes and through holes. Prior to the alkaline permanganate aqueous solution, the swelling treatment with a swelling liquid is preferably performed. Examples of the swelling liquid include Swelling Dip Securiganth P (Swelling Dip Securiganth P) and Swelling Dip Securiganth SBU (ABUTEC Japan Co., Ltd.).

  The swelling treatment is usually performed by attaching an insulating layer to the swelling liquid heated to about 60 to 80 ° C. for about 5 to 10 minutes. Examples of the alkaline permanganate aqueous solution include a solution in which potassium permanganate or sodium permanganate is dissolved in an aqueous solution of sodium hydroxide. The roughening treatment with the alkaline permanganic acid aqueous solution is usually performed at 60 to 80 ° C. for about 10 to 30 minutes. Examples of commercially available alkaline permanganate aqueous solutions include Concentrate Compact CP, Dosing Solution Securigans P manufactured by Atotech Japan Co., Ltd.

  In the method for producing a multilayer printed wiring board of the present invention, a plating step of forming a conductor layer by plating on the surface of the further roughened insulating layer, a step of annealing the inner circuit board by heating after forming the conductor layer, and a conductor A circuit forming step of forming a circuit in the layer may be further included. These steps can be performed according to various methods known to those skilled in the art and used in the production of multilayer printed wiring boards.

  A plating process is performed by forming a conductor layer by the method which combined the electroless plating and the electrolytic plating on the insulating layer surface in which the uneven anchor was formed by the roughening process, for example. At this time, plating is also formed in the via hole. A copper plating layer is preferable as the conductor layer. The copper plating layer is a method in which electroless copper plating and electrolytic copper plating are combined, or a plating resist having a pattern opposite to that of the conductor layer is formed, and the conductor layer is formed only by electroless copper plating. The thickness of the electroless plating layer is preferably 0.1 to 3 μm, more preferably 0.3 to 2 μm. On the other hand, the thickness of the electroplating layer is preferably a thickness of 3 to 35 μm, more preferably 5 to 20 μm, with the total thickness of the electroless plating layer. The via hole can be filled via by plating.

  The annealing treatment step can be performed, for example, by heating the circuit board at 150 to 200 ° C. for 20 to 90 minutes after forming the conductor layer. By performing the annealing treatment, the peel strength of the conductor layer can be further improved and stabilized.

  As the circuit formation process, for example, a subtractive method, a semi-additive method, or the like can be used. The semi-additive method is preferable for fine line formation. A pattern resist is applied on the electroless plating layer, an electrolytic plating layer (pattern plating layer) having a desired thickness is formed, the pattern resist is peeled off, and the electroless plating layer is formed. A circuit can be formed by removing by flash etching.

  The “inner layer circuit board” in the present invention is mainly patterned on one or both sides of a substrate such as a glass epoxy substrate, a metal substrate, a polyester substrate, a polyimide substrate, a BT resin substrate, a thermosetting polyphenylene ether substrate ( An intermediate product having a conductor layer (with a circuit formed), and when a multilayer printed wiring board is manufactured, an insulating layer and a conductor layer should be further formed on one or both sides thereof. In addition, it is preferable from the viewpoint of the adhesiveness of the insulating layer to the inner circuit board that the surface of the conductor layer has been previously roughened by blackening or the like.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.
In the following description, “part” means “part by mass”.

<Example 1>
(Create resin varnish)
Polyvinyl butyral resin (“KS-1” manufactured by Sekisui Chemical Co., Ltd.) is dissolved in a solvent in which ethanol and toluene are mixed at a ratio of 1: 1 at 60 ° C. so that the solid content is 15%. A butyral resin solution was obtained. Next, 28 parts of liquid bisphenol A type epoxy resin (epoxy equivalent 180, “Epicoat 828EL” manufactured by Japan Epoxy Resin Co., Ltd.) and naphthalene type tetrafunctional epoxy resin (epoxy equivalent 163, manufactured by Dainippon Ink & Chemicals, Inc.) 28 parts of “HP4700”) was dissolved by heating in a solvent consisting of 15 parts of methyl ethyl ketone (hereinafter abbreviated as “MEK”) and 15 parts of cyclohexanone with stirring. Thereto, 110 parts of a 50% solid content MEK solution of a naphthol-based curing agent (“SN-485” manufactured by Tohto Kasei Co., Ltd., phenolic hydroxyl group equivalent 215), a curing catalyst (“2E4MZ” manufactured by Shikoku Chemicals Co., Ltd.) ”) 0.1 part, 70 parts of spherical silica (average particle size 0.5 μm,“ SOC2 ”manufactured by Admatechs) and 30 parts of the polyvinyl butyral resin solution described above were mixed and dispersed uniformly with a high-speed rotary mixer. A resin varnish was prepared.

(Manufacture of thermosetting resin composition film)
A die coater is used so that the thickness of the thermosetting resin composition layer after drying is 10 μm, 13 μm, 14 μm, 18 μm, and 22 μm on a PET film (38 μm) treated with the alkyd mold release agent. When the thickness is 10 μm, the minimum melt viscosity is 1000 poise, and when the thickness is 13 μm, two types, 1300 and 1820 poise, are applied uniformly, and dried at 80 to 120 ° C. (average 100 ° C.). A thermosetting resin composition film having 1300 poise in the case of 14 μm, 1500 poise in the case of 18 μm, and 1800 poise in the case of 22 μm was obtained. Next, a 15 μm-thick polypropylene film was wound around the surface of the thermosetting resin composition film in a roll shape. Thereafter, the roll-shaped thermosetting resin composition film was slit into a width of 502 mm, and two types of 50-roll thermosetting resin composition films were obtained.

(Manufacture of cured prepreg)
The polypropylene film of the thermosetting resin composition film (thermosetting resin composition layer 10 μm) is peeled off, and the thermosetting resin composition layer is glass on both sides of Arisawa Seisakusho 1015 NS glass cloth (thickness 16 μm). Using a vacuum pressurizing laminator manufactured by Meiki Seisakusho Co., Ltd., vacuum suction at a temperature of 120 ° C. for 30 seconds, a temperature of 120 ° C., and a pressure of 7.0 kg / cm ² From the PET film, lamination was performed by pressing for 30 seconds through heat-resistant rubber. Next, pressing was performed under atmospheric pressure using a SUS end plate for 60 seconds under conditions of a temperature of 120 ° C. and a pressure of 5 kg / cm ² . The thickness of the obtained prepreg was 24 μm. This prepreg was cured at 160 ° C. for 10 minutes to obtain a cured prepreg having a glass transition temperature of 90 ° C.

(Manufacture of insulating resin sheets)
The polypropylene film of the obtained thermosetting resin composition film (thermosetting resin composition layer 13 μm) is peeled off and placed on both sides of the cured prepreg so that the thermosetting resin composition layer is on the cured prepreg side, Using a vacuum pressurizing laminator manufactured by Meiki Seisakusho Co., Ltd., after vacuum suction at a temperature of 120 ° C. for 30 seconds, heat resistant rubber was applied from above the PET film under the conditions of a temperature of 120 ° C. and a pressure of 7.0 kg / cm ^2. For 30 seconds. Next, pressing was performed for 60 seconds under atmospheric pressure using a SUS end plate at a temperature of 120 ° C. and a pressure of 5 kg / cm ² to obtain an insulating resin sheet. The cured resin composition layer on the inner circuit board side of the insulating resin sheet was the B layer, and the opposite layer was the A layer.

(Lamination and smoothing of insulating resin sheet)
The obtained insulating resin sheet was laminated on both sides of an inner layer circuit board (IPC MULTI-PURPOSE TESTBOARD No. IPC-B-25, circuit conductor thickness 18 μm, 0.8 mm thickness). Such a laminate uses a vacuum pressurizing laminator MVLP-500 manufactured by Meiki Seisakusho Co., Ltd., vacuum suction for 30 seconds at a temperature of 100 ° C., and then a PET film under the conditions of a temperature of 100 ° C. and a pressure of 7.0 kg / cm ^2. From above, lamination was performed by pressing through heat-resistant rubber for 30 seconds. Next, smoothing was performed under atmospheric pressure using a SUS end plate for 60 seconds under conditions of a temperature of 100 ° C. and a pressure of 5 kg / cm ² .

(Curing resin composition)
The PET film was peeled from the laminated insulating resin sheet, and the resin composition was cured under a curing condition of 180 ° C. for 30 minutes using a hot air circulating furnace to form an insulating layer. Thereby, the laminated board in which the insulating layer was formed on both surfaces of the inner circuit board was obtained.

(Roughening treatment)
The resulting laminate was subjected to a roughening treatment with a permanganate solution. First, as a swelling treatment, it is immersed in Swelling Dip Securiganth P (Swelling Dip Securiganth P) for 5 minutes at 60 ° C. Then, as an oxidation treatment, an outlet made by Atotech Japan Co., Ltd. Immerse it in a mixed solution of Rate Compact CP and Dosing Solution Securiganth P at 80 ° C. for 20 minutes, and then reduce it to Atotech Japan Co., Ltd. Reduction Solution Securiganth P500 (Reduction solution Securiganth P500) ) It was immersed in the solution at 40 ° C. for 5 minutes.

(Conductor layer formation by plating)
After applying an electroless copper plating catalyst to the surface of the insulating layer of the obtained multilayer substrate using an activator neogant 834 made of Atotech Japan, which contains palladium, the print gant MSK-DK made of Atotech containing tartrate Was used for electroless plating. Next, electrolytic plating was performed using copper sulfate so that the copper thickness was about 20 μm. Then, it hardened | cured for 30 minutes at 180 degreeC, and produced the target multilayer printed wiring board.

<Example 2>
A target multilayer printed wiring board was produced in the same manner as in Example 1 except that the glass transition temperature of the cured prepreg was 96 ° C.

<Example 3>
The object is the same as in Example 1 except that the glass transition temperature of the cured prepreg is 110 ° C., and the temperature in the lamination and smoothing step of the insulating resin sheet is 120 ° C. A multilayer printed wiring board was created.

<Example 4>
The objective is the same as in Example 1 except that the glass transition temperature of the cured prepreg is 120 ° C., and the temperature in the lamination and smoothing step of the insulating resin sheet is 120 ° C. A multilayer printed wiring board was created.

<Example 5>
The cured prepreg has a glass transition temperature of 120 ° C., the thicknesses of the A and B layers of the insulating resin sheet are 13 μm, the minimum melt viscosity is 1300 poise, and the insulating resin sheet is laminated and smoothed on the inner circuit board. A target multilayer printed wiring board was prepared in the same manner as in Example 1 except that the temperature in the process was 100 ° C.

<Example 6>
The cured prepreg has a glass transition temperature of 120 ° C., the thicknesses of the A and B layers of the insulating resin sheet are 18 μm, the minimum melt viscosity is 1500 poise, and the insulating resin sheet is laminated and smoothed on the inner circuit board. A target multilayer printed wiring board was prepared in the same manner as in Example 1 except that the temperature in the process was 100 ° C.

<Example 7>
The cured prepreg has a glass transition temperature of 120 ° C., an A layer thickness of the insulating resin sheet of 14 μm, a minimum melt viscosity of 1300 poise, a B layer thickness of 22 μm and a minimum melt viscosity of 1800 poise. A target multilayer printed wiring board was produced in the same manner as in Example 1 except that the temperature in the laminating and smoothing step was set to 100 ° C.

<Example 8>
The cured prepreg has a glass transition temperature of 100 ° C., an A layer thickness of the insulating resin sheet of 14 μm, a minimum melt viscosity of 1300 poise, a B layer thickness of 22 μm and a minimum melt viscosity of 1800 poise. A target multilayer printed wiring board was produced in the same manner as in Example 1 except that the temperature in the laminating and smoothing step was set to 100 ° C.

<Comparative Example 1>
A target multilayer printed wiring board was produced in the same manner as in Example 1 except that only a prepreg layer having a thickness of 45 μm was used instead of the insulating resin sheet having a three-layer structure.
The prepreg having a thickness of 45 μm is impregnated with the same resin varnish as in Example 1 in a 1015 NS glass cloth (thickness 16 μm) manufactured by Arisawa Manufacturing Co., Ltd. so that the thickness of the obtained prepreg is 45 μm. And obtained by drying at 80 to 150 ° C. for 10 minutes.

<Comparative Example 2>
A target multilayer printed wiring board was produced in the same manner as in Example 1 except that an uncured 24 μm prepreg produced by the same method as in Comparative Example 1 was used for the cured prepreg layer.

<Comparative Example 3>
A target multilayer printed wiring board was produced in the same manner as in Example 1 except that only a prepreg layer having a thickness of 50 μm was used instead of the insulating resin sheet having a three-layer structure.
The prepreg having a thickness of 50 μm is impregnated with the same resin varnish as in Example 1 in a 1015 NS glass cloth (thickness 16 μm) manufactured by Arisawa Manufacturing Co., Ltd. so that the thickness of the obtained prepreg becomes 50 μm. And obtained by drying at 80 to 150 ° C. for 10 minutes.

<Comparative example 4>
A target multilayer printed wiring board was produced in the same manner as in Example 1 except that only a prepreg layer having a thickness of 60 μm was used instead of the insulating resin sheet having a three-layer structure.
The prepreg having a thickness of 60 μm is impregnated with the same resin varnish as in Example 1 in a 1015 NS glass cloth (thickness 16 μm) manufactured by Arisawa Manufacturing Co., Ltd. so that the thickness of the obtained prepreg becomes 60 μm. And then dried at 80 to 150 ° C. for 14 minutes.

<Comparative Example 5>
A target multilayer printed wiring board was produced in the same manner as in Example 5 except that an uncured 24 μm prepreg produced by the same method as in Comparative Example 1 was used for the cured prepreg layer.

<Reference Example 1>
The target multilayer printed wiring board was prepared in the same manner as in Example 8 except that the prepreg was cured at 140 ° C. for 15 minutes to use a prepreg layer having a glass transition temperature of 80 ° C. .

<Reference Example 2>
A target multilayer printed wiring board was produced in the same manner as in Example 1 except that the glass transition temperature of the cured prepreg was 77 ° C.

<Reference Example 3>
The objective is the same as in Example 1 except that the glass transition temperature of the cured prepreg is 86 ° C., and the temperature in the lamination and smoothing step of the insulating resin sheet is 120 ° C. A multilayer printed wiring board was created.

<Reference Example 4>
The objective is the same as in Example 1 except that the glass transition temperature of the cured prepreg is 100 ° C., and the temperature in the lamination and smoothing step of the insulating resin sheet is 120 ° C. A multilayer printed wiring board was created.

  The cured prepregs, thermosetting resin compositions, insulating resin sheets or multilayer printed wiring boards obtained in the above Examples and Comparative Examples were evaluated as follows. The results are shown in Tables 1 and 2 below.

(Measurement of glass transition temperature)
A small piece of the cured prepreg obtained in Examples and Reference Examples was used as a sample, and measurement was performed in “tensile mode” using a model DMS-6100 manufactured by Seiko Instruments Inc. as a thermomechanical analyzer (DMA). This measurement was performed in the range of 25 ° C. to 240 ° C. at a temperature increase of 2 ° C./min. The value obtained by rounding down the decimal point of the maximum value of the loss tangent (tan δ) obtained by the ratio of the storage elastic modulus (E ′) and loss elastic modulus (E ″) obtained by the measurement was defined as the glass transition temperature. The uncured prepreg of the comparative example was not allowed to be measured because the glass transition temperature could not be measured.

(Measurement of minimum melt viscosity)
A model Rheosol-G3000 manufactured by UBM was used, and the amount of resin was 1 g. Further, a parallel plate having a diameter of 18 mm was used, and measurement was performed at a measurement start temperature of 60 ° C., a temperature increase rate of 5 ° C./min, and a frequency of 1 Hz / deg. The lowest viscosity value (η) was taken as the lowest melt viscosity.

(Measurement of thickness of prepreg layer, cured prepreg layer, thermosetting resin composition layer and insulating resin sheet)
It measured using the contact-type film thickness meter (the Mitutoyo company make, MCD-25MJ).

(Measurement of resin thickness on glass cloth and thickness of glass cloth)
The cross section of the stepped portion of the P coupon portion in the inner layer circuit board was cut out, and measurement was performed using a CCD type microscope (manufactured by Keyence Corporation, VH6300) or a scanning electron microscope (SEM). The “P coupon part” is a conductor circuit in an inner circuit board (IPC MULTI-PURPOSE TESTBOARD No. IPC-B-25, circuit conductor thickness 18 μm, 0.8 mm thickness) laminated with an insulating resin sheet. Refers to the part.

(Exposed glass cloth and plating residue)
The plating film on the P coupon of the inner layer circuit board was peeled off, and the presence or absence of exposure of the glass cloth was observed using a CCD type microscope (VH6300, manufactured by Keyence Corporation). When the glass cloth is exposed, the plated copper remains in the copper plating, so that the plated copper remains even after the plating film is peeled off.
[Evaluation]
○: No exposure of glass cloth on the resin surface of the P coupon and no plating copper residue.
X: Exposed glass cloth on the resin surface of the P coupon and / or plated copper residue.

(Embedment into circuit)
The laminated board which cut out the cross section of the level | step-difference part of the P coupon part in an inner layer circuit board was observed with the scanning electron microscope (SEM), and it was confirmed whether resin was embedded between the circuits.
[Evaluation]
○: Resin is embedded between circuits.
X: There is a void remaining between the circuits, and the embedding is insufficient.

As is clear from the results shown in Table 2, the insulating resin sheets having the cured prepregs of Examples 1 to 8 were laminated on the inner circuit board and cured, and then subjected to roughening treatment. There was no plating copper residue. On the other hand, in the insulating resin sheets of Comparative Examples 1 to 5, exposure of the glass cloth due to the roughening treatment was observed.
Moreover, the thickness of the resin on the glass cloth of the insulating resin sheet having the cured prepreg shown in Examples 1 to 8 is 10 μm or more, and the insulating resin sheets of Comparative Examples 1 to 3 are 4 in thickness. ˜7 μm.

  The insulating resin sheet of the present invention is suitably used as an insulating material for multilayer printed wiring boards.

FIG. 1 is a schematic cross-sectional view of an insulating resin sheet of the present invention.

Explanation of symbols

1 cured prepreg layer 2 A layer 3 B layer

Claims (12)

  An insulating resin sheet comprising a cured prepreg layer and a thermosetting resin composition layer formed on both surfaces of the cured prepreg layer.   The insulating resin sheet according to claim 1, wherein the cured prepreg is obtained by thermosetting a prepreg obtained by impregnating a sheet-like fiber base material with a thermosetting resin composition. The insulating resin sheet is
(1) The insulating resin sheet is placed on the inner layer circuit board so that the thermosetting resin composition layer is in contact with both sides or one side of the inner layer circuit board, and heated and pressed through an elastic material under reduced pressure, thereby Laminating process to laminate on circuit board,
(2) A smoothing step of smoothing the insulating resin sheet by heating and pressing the laminated insulating resin sheet with a metal plate or a metal roll, and (3) thermosetting the smoothed insulating resin sheet. The insulating resin sheet of Claim 1 or 2 used for the manufacturing method of a multilayer printed wiring board provided with the thermosetting process which forms an insulating layer by this.   The insulating resin sheet according to claim 3, wherein the glass transition temperature of the cured prepreg is (P-18) or higher when the higher one of the temperature in the laminating step and the temperature in the smoothing step is set to P ° C.   The insulating resin sheet according to claim 3, wherein the glass transition temperature of the cured prepreg is (P-12) or higher when the higher one of the temperature of the laminating step and the temperature of the smoothing step is P ° C.   The insulating resin sheet of Claim 3 whose glass transition temperature of the said hardening prepreg is (P-10) or more, when the higher one of the temperature of the said lamination process and the temperature of the smoothing process is set to P degreeC.   The insulating resin sheet according to claim 1, wherein a protective film is formed on one side or both sides of the thermosetting resin composition layer.   The insulating resin sheet according to claim 7, wherein the protective film is a polyethylene terephthalate film.   The multilayer printed wiring board with which the insulating layer was formed with the insulating resin sheet of any one of Claims 1-8.   (1) The insulating resin sheet according to any one of claims 1 to 8 is disposed on the inner circuit board so that the thermosetting resin composition layer is in contact with both surfaces or one surface of the inner circuit board, and under reduced pressure. A laminating step of laminating on the inner circuit board by heating and pressing through an elastic material, and (2) an insulating resin sheet by heating and pressing the laminated insulating resin sheet with a metal plate or a metal roll. And (3) a method for producing a multilayer printed wiring board, comprising: a thermosetting step of forming an insulating layer by thermosetting the smoothed insulating resin sheet.   The manufacturing method of Claim 10 with which the heating and pressurization of the insulating resin sheet in the said lamination process and smoothing process are performed from a protective film.   A drilling step for drilling in the insulating layer, a roughening step for roughening the insulating layer, a plating step for forming a conductor layer by plating on the surface of the roughened insulating layer, and a circuit forming step for forming a circuit in the conductor layer. The manufacturing method according to claim 10 or 11, further comprising:

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