JP6004017B2 - Insulating resin sheet and method for producing multilayer printed wiring board using the insulating resin sheet - Google Patents

Description

  The present invention relates to an insulating resin sheet useful for forming an insulating layer of a multilayer printed wiring board, 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 build-up method in which insulating layers and conductor layers are alternately stacked on a core substrate is known. For the insulation layer formation, an adhesive film in which a thermosetting resin layer is formed exclusively on a plastic film is used. The adhesive film is laminated (laminated) on the inner circuit board, the plastic film is peeled off, and then the thermosetting resin is used. Is thermally cured to form an insulating layer. On the other hand, due to recent needs for downsizing of electronic devices and electronic components, multilayer printed wiring boards tend to be made thinner and thinner, for example, the core substrate is required to be thinner or omitted. . 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 and Patent Document 2 disclose B-stage resin composition sheets in which an additive resin composition layer is formed on one side of a prepreg.

JP 2003-249664 A JP 2003-313324 A

  When a prepreg is used for an interlayer insulating layer, the resin composition layer on the surface of the prepreg becomes thin due to the flow of the resin composition impregnated in the prepreg or the expansion of the glass cloth through the lamination to the inner circuit board and the thermosetting process. Become. Therefore, when the surface of the insulating layer is roughened with an oxidizing agent or the like for forming a conductor layer by plating, there arises a problem that the fibrous sheet base material in the prepreg is exposed. Therefore, the present inventors used an insulating resin sheet in which a thermosetting resin composition layer as described in Patent Documents 1 and 2 was laminated on one side of a prepreg in a method for producing a multilayer printed wiring board by a build-up method. Tried to apply. That is, when the insulating resin sheet was laminated on the inner layer circuit board with a vacuum laminator, it was found that the insulating resin sheet sufficiently followed the circuit irregularities of the inner layer circuit board and the embedding property of the circuit irregularities was also good. . On the other hand, the laminated insulating resin sheet reflects the circuit irregularities of the inner layer circuit board, and the surface becomes irregular. Therefore, in order to smooth the surface of the insulating resin sheet, when the insulating resin sheet is heated and pressurized with a metal plate under normal pressure and the surface is smoothed, the thermosetting resin composition layer on the surface of the insulating resin sheet flows, A phenomenon was found in which the thickness of some of the thermosetting resin composition layers was reduced reflecting the unevenness of the circuit. In addition, after forming the insulating layer by thermosetting the insulating resin sheet, when the surface of the insulating layer is roughened and the conductor layer is formed by plating, the fibrous sheet base material of the prepreg is removed from the thinned portion. As a result, a phenomenon was found in which the formation of a conductor layer caused a defect.

  Therefore, the subject of this invention is providing the insulating resin sheet which has a fibrous sheet base material which does not have a problem of exposure of the above fibrous sheet base material, when a multilayer printed wiring board is manufactured using it. There is.

  As a result of earnest research to solve the above problems, the present inventors have used an insulating resin sheet composed of a cured product layer and a prepreg layer of a thermosetting resin composition in the production of a multilayer printed wiring board. It has been found that even when the surface of the insulating layer is roughened, the exposure of the fibrous sheet substrate as described above can be suppressed, and the present invention has been completed.

That is, the present invention includes the following contents.
[1] An insulating resin sheet having a cured layer of a thermosetting resin composition on one side of a prepreg.
[2] The insulating resin sheet according to the above [1], further comprising a support layer on the cured product layer.
[3] The insulating resin sheet according to [2], which is obtained by adhering a cured sheet having a cured layer of a thermosetting resin composition formed on a support layer to one side of a prepreg.
[4] The insulating resin sheet according to the above [2] or [3], wherein the cured product layer side of the support layer is subjected to a release treatment.
[5] The insulating resin sheet according to any one of [2] to [4], wherein the support layer is a plastic film.
[6] The insulating resin sheet according to any one of [1] to [5], wherein the prepreg surface of the insulating resin sheet is protected by a protective film.
[7] The insulating resin sheet according to any one of [1] to [6], wherein the thickness of the prepreg is 10 to 70 μm.
[8] The insulating resin sheet according to any one of [1] to [7], wherein the cured product layer of the thermosetting resin composition is 1 to 30 μm.
[9] (1) Laminating process in which an insulating resin sheet is placed on a circuit board so as to be in contact with both sides or one side of the circuit board, and is laminated on the circuit board by heating and pressing through an elastic material under reduced pressure. (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 according to any one of [1] to [8], which is used in a method for producing a multilayer printed wiring board including a thermosetting step.
[10] The insulating resin sheet according to the above [9], wherein the cured product layer of the thermosetting resin composition has substantially no fluidity in the laminating step and the smoothing step.
[11] A multilayer printed wiring board in which an insulating layer is formed of the insulating resin sheet according to any one of [1] to [10].
[12] (1) The insulating resin sheet according to any one of [1] to [10] is installed on the inner circuit board so that the prepreg 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 layer circuit board by heating and pressing through an elastic material, (2) a smoothing step of heating and pressurizing 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 thermosetting the smoothed insulating resin sheet.
[13] The method according to [12] above, wherein the insulating resin sheet in the laminating step and the smoothing step is heated and pressed from above the support layer.
[14] 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 a circuit for forming a circuit in the conductor layer The method according to [12] or [13] above, further comprising a forming step.

  According to the insulating resin sheet of the present invention, 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, even if the surface of the insulating layer is roughened after the insulating layer is formed by thermosetting, the fiber base material of the prepreg is not exposed, and the conductor layer can be satisfactorily formed by plating. A high multilayer printed wiring board can be manufactured.

Hereinafter, the present invention will be described with reference to preferred embodiments thereof.
The prepreg used in the present invention can be obtained by impregnating a sheet-like fiber base material with a thermosetting resin composition and drying by heating.

  The thermosetting resin composition 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 the thermosetting resin composition include an epoxy resin, a cyanate ester resin, and a phenol resin. And a composition containing at least a thermosetting resin such as a bismaleimide-triazine resin, a polyimide resin, an acrylic resin, and a vinylbenzyl resin and a curing agent thereof. 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 & 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 Resin Co., Ltd.), and the like. 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, and as a commercially available product of such a polyvinyl acetal resin, for example, Denki 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, a linear polyimide obtained by reacting a bifunctional hydroxyl group-terminated polybutadiene, a diisocyanate compound and a tetrabasic acid anhydride (described in JP-A-2006-37083), a polysiloxane skeleton-containing polyimide (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.

  Examples of commercially available phenolic and naphtholic curing agents include MEH-7700, MEH-7810, MEH-7785 (Maywa Kasei Co., Ltd.), NHN, CBN, GPH (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), and 4,4 ′. -Ethylidenediphenyl 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, Derived from cresol novolac, etc. Examples thereof include polyfunctional cyanate resins and prepolymers in which these cyanate resins are partially triazine. Specific examples of the cyanate ester resin include, for example, a phenol novolac type polyfunctional cyanate ester resin (“PT30” manufactured by Lonza Japan Co., Ltd., cyanate equivalent 124) and a part or all of bisphenol A dicyanate being triazine. Examples include prepolymers ("BA230" manufactured by Lonza Japan Co., Ltd., cyanate equivalent 232).

  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. A ratio that falls within a range is preferable, and a ratio that becomes a range between 0.5 and 1.0 is more preferable. When a cyanate ester resin is used, 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 such curing accelerators 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. In addition, when using a cyanate ester resin as an epoxy resin curing agent, an organometallic compound that has been used as a curing catalyst in a conventional 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 organometallic 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. Examples of other components include flame retardants such as organic phosphorus flame retardants, organic nitrogen-containing phosphorus compounds, nitrogen compounds, silicone flame retardants, and metal hydroxides; organics such as silicone powder, nylon powder, and fluororesin powder. Fillers; thickeners such as olben and benton; high molecular defoamers or leveling agents such as silicones and fluororesins; adhesion-imparting agents such as imidazole, thiazole, triazole and silane coupling agents Colorants such as phthalocyanine blue, phthalocyanine green, iodin green, disazo yellow, carbon black and the like.

The sheet-like fiber base material used for a prepreg is not specifically limited, For example, 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. In particular, when it is used for forming an insulating layer of a multilayer printed wiring board, a thin one having a thickness of 50 μm or less is preferably used, and particularly preferably 10 to 40 μm. As a specific example of the sheet-like fiber base material, as a glass cloth base material, for example, Style 1027MS (manufactured by Asahi Sebel Co., Ltd. (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 (warp) Density 72 yarns / 25 mm, weft density 69 yarns / 25 mm, fabric weight 23 g / m ² , thickness 21 μm), Arisawa Seisakusho 1027NS (warp density 75 yarns / 25 mm, weft density 75 yarns / 25 mm, fabric weight 19 0.5 g / m ² , thickness 16 μm), Arisawa Seisakusho 1015 NS (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, fabric weight 11 g / m ² , thickness 10 μm). . 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. Further, 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 near the surface. Remarkably easy to appear.

The prepreg can be produced by a known hot melt method, solvent method or the like. In the hot-melt method, the resin composition and the release paper having good peelability are coated once without being dissolved in an organic solvent, and then laminated on a sheet-like fiber base material or directly applied by a die coater. Thus, a prepreg is manufactured. The solvent method is a method in which the sheet-like fiber base material is impregnated into the sheet-like fiber base material by immersing the sheet-like fiber base material in a resin composition varnish in which the resin composition is dissolved in an organic solvent, and then dried. . It can also be prepared by continuously laminating an adhesive film made of a thermosetting resin composition laminated on a support layer from both sides of a sheet-like reinforcing substrate under heating and pressure conditions.

  Examples of organic solvents 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, acetate esters such as carbitol acetate, cellosolve, butyl Examples thereof include carbitols such as carbitol, aromatic hydrocarbons such as toluene and xylene, dimethylformamide, dimethylacetamide, N-methylpyrrolidone and the like. One organic solvent may be used, or two or more organic solvents may be used in combination.

  The drying conditions are not particularly limited, but in order to laminate on the inner circuit board, the thermosetting resin composition needs to have fluidity (flowability) and adhesiveness at the temperature in the laminating process. Therefore, it is important that the thermosetting resin composition is not cured as much as possible during drying. On the other hand, if a large amount of the organic solvent remains in the prepreg, it may cause swelling after curing. Therefore, the content of the organic solvent in the thermosetting resin composition is usually 5% by mass or less, preferably 2% by mass. It is dried so that it becomes less than%. Accordingly, drying conditions are set from both viewpoints, and the conditions vary depending on the curability of the thermosetting resin composition and the amount of the organic solvent in the varnish. For example, the varnish containing 30 to 60% by mass of the organic solvent. In general, it can be dried at 80 to 180 ° C. for about 3 to 13 minutes. In addition, those skilled in the art can appropriately set suitable drying conditions through simple experiments.

  Although the thickness of the prepreg differs depending on the thickness of the conductor layer of the inner circuit board, the thickness of the conductor layer is usually 10 to 30 μm, and the thickness of the prepreg is usually in the range of 10 to 70 μm. From the viewpoint of the cost and the thinness desired as the insulating resin sheet, it is more preferably 12 to 50 μm, and further preferably 12 to 40 μm. In addition, although the exposure of a fiber base material tends to be eased, so that the thickness of a prepreg is large, it becomes disadvantageous for thickness reduction of a multilayer printed wiring board. According to the insulating resin sheet of the present invention, it is possible to simultaneously suppress the fiber base material exposure and reduce the thickness of the multilayer printed wiring board. The thickness of the prepreg can be easily controlled by adjusting the amount of impregnation of the thermosetting resin composition. Further, the prepreg needs to have fluidity that can be laminated without forming a void in the wiring portion of the inner layer circuit board, and preferably has a minimum melt viscosity in the range of 200 to 7000 poise, and in the range of 400 to 3000 poise. It is particularly preferred that

  The “cured product layer of the thermosetting resin composition” in the present invention is obtained by thermosetting the thermosetting resin composition. As a thermosetting resin composition, if it is suitable for the insulating layer of a multilayer printed wiring board, it can be used without a restriction | limiting especially, The thing similar to the thermosetting resin composition used for the prepreg demonstrated above is used. be able to. In addition, the thermosetting resin composition used for the prepreg and the thermosetting resin composition used for the cured product layer may be the same or different.

The cured product layer in the insulating resin sheet of the present invention is obtained, for example, by a method of thermosetting the thermosetting resin composition of the adhesive sheet in which the thermosetting resin composition layer is formed on the support layer . That is, the adhesive sheet is prepared by a method known to those skilled in the art, for example, by preparing a resin varnish in which a thermosetting resin composition is dissolved in an organic solvent, applying the resin varnish on a support layer , and blowing hot air or the like. It is manufactured by heating and drying the organic solvent to form a thermosetting resin composition layer. The thermosetting resin composition of the adhesive sheet thus obtained is thermoset to obtain a cured sheet, which is a prepreg. The insulating resin sheet of this invention can be obtained by passing through the process of adhering to one side. In the production of the adhesive sheet, it is also possible to obtain a cured product sheet by heating the resin varnish applied on the support layer and performing drying and curing simultaneously or sequentially. The insulating resin sheet of the present invention can also be obtained through a step of bonding the cured product sheet to one side of the prepreg.

  Examples of the organic solvent used for the preparation of the resin varnish include ketones such as acetone, methyl ethyl ketone, and cyclohexanone, ethyl acetate, butyl acetate, cellosolve acetate, acetate esters such as propylene glycol monomethyl ether acetate, carbitol acetate, cellosolve, butyl Examples thereof include carbitols such as carbitol, aromatic hydrocarbons such as toluene and xylene, dimethylformamide, dimethylacetamide, N-methylpyrrolidone and the like. Two or more organic solvents may be used in combination.

Although the drying conditions in the case of preparing an adhesive sheet are not specifically limited, it is dried so that the content of the organic solvent in the thermosetting resin composition layer is usually 10% by mass or less, preferably 5% by mass or less. Depending on the amount of organic solvent in the resin varnish, for example, a resin varnish containing 30 to 60% by mass of an organic solvent can be dried at 50 to 150 ° C. for about 3 to 10 minutes. Curing conditions when the thermosetting resin composition layer of the adhesive sheet is sequentially cured, or when drying and curing of the resin varnish applied on the support layer are performed simultaneously are not particularly limited, for example, 30 to In a varnish containing 60% by mass of an organic solvent, a cured product layer can be formed by heating at a temperature of about 50 to 200 ° C. for about 10 minutes to 10 hours. The drying and curing conditions can be appropriately set by those skilled in the art through simple experiments.

A plastic film is preferably used as the support layer . In addition to the plastic film, release paper, copper foil, metal foil such as aluminum foil, and the like can also be used as the support layer . Examples of the plastic film include polyethylene terephthalate (hereinafter sometimes abbreviated as “PET”), polyester such as polyethylene naphthalate, polycarbonate, acrylic resin, cyclic polyolefin, triacetyl cellulose, polyether sulfide, polyether ketone, polyimide, and the like. Is mentioned. Among these, a polyethylene terephthalate film and a polyethylene naphthalate film are preferable, and an inexpensive polyethylene terephthalate film is particularly preferable. In the support layer , particularly when a plastic film is used, in order to make the peelable from the cured product of the thermosetting resin composition layer, the formation surface of the thermosetting resin composition layer was subjected to a release treatment. preferable to use a support layer having a release layer. Metal foil can be removed with an etching solution, but when a thermosetting resin composition is thermoset using a plastic film as a support layer , it is difficult to peel the plastic film from the cured product without a release layer. It becomes. The release agent used for the release treatment is not particularly limited as long as the cured product can be peeled from the support layer , and examples thereof include silicone release agents and alkyd resin release agents. 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 thereof 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. Moreover, when using copper foil as a support body, you may utilize this copper foil as a conductor layer, without peeling. Although the thickness of a support body is not specifically limited, Usually, it is 10-150 micrometers, Preferably it is used in 25-50 micrometers.

In the cured product layer of the insulating resin sheet of the present invention, the thermosetting resin composition does not necessarily need to be completely thermoset, and may be cured to the extent that the effects of the present invention are exhibited. That is, since an adhesive sheet made of a support layer and a thermosetting resin composition layer, which is generally used for forming an interlayer insulating layer, needs to be embedded in a circuit by stacking on an inner layer circuit board, it is sufficient. Whereas it is necessary to have fluidity, the cured layer of the thermosetting resin composition in the insulating resin sheet of the present invention is laminated and smoothed to suppress the exposure of the prepreg sheet fiber substrate. It is important that the process has almost no fluidity, and it is more preferable that the process has substantially no fluidity. For example, using a vacuum laminator, a 12 cm x 15 cm cured product layer of a thermosetting resin composition is laminated on a FR4 substrate of 20 cm square and 0.8 mm thickness under the same conditions as the actual laminating step and smoothing step. A cured state in which smoothing is performed, and the maximum stain length at that time is preferably 0.3 mm or less, more preferably 0.2 mm or less, further preferably 0.1 mm or less, and particularly preferably substantially 0. It is preferable that For example, the maximum stain length measured under the following representative conditions can be used as an index of the degree of cure of the cured product layer that is preferable for use in the present invention. That is, using a vacuum laminator, a cured product layer 12 cm × 15 cm (rectangular cured product layer having a planar size of 12 cm × 15 cm) of the thermosetting resin composition was vacuum sucked at a temperature of 80 ° C. for 30 seconds, and then heated to a temperature of 80 Lamination was performed by pressing for 60 seconds through heat-resistant rubber under the conditions of ℃ and pressure of 7.0 kgf / cm ² , and further under atmospheric pressure using a SUS end plate at a temperature of 80 ° C. and a pressure of 5.5 kgf / cm ^2. When the smoothing treatment is performed by pressing for 90 seconds under the above conditions, the maximum spot length of the resin is measured, and the maximum spot length is preferably 0.3 mm or less, more preferably 0.2 mm or less. More preferably, it is 0.1 mm or less, and particularly preferably substantially 0.

The degree of curing of the thermosetting resin composition can also be evaluated by the glass transition temperature. In this invention, it is preferable to harden at least to such an extent that the glass transition temperature of hardened | cured material is observed. In general, an adhesive sheet composed of a support layer and a thermosetting resin composition used for forming an interlayer insulating layer has fluidity as described above. For example, the thermosetting resin composition layer is a B stage. However, the reactivity is extremely low, and it is usually impossible to measure the glass transition temperature. Even if it can be measured, the glass transition temperature is at least room temperature or lower. Generally, when cured to such an extent that a glass transition temperature is observed, the thermosetting resin composition substantially flows within the temperature range of a general laminating step and a smoothing step (about 70 ° C. to 140 ° C.). Have little or no fluidity. From these points, the general adhesive sheet and the cured product sheet in the present invention are clearly distinguished. The glass transition temperature of the cured product is more preferably 80 ° C. or higher. The upper limit of the glass transition temperature is not particularly limited, and generally the glass transition temperature of the cured thermosetting resin composition often falls within the range of 300 ° C. or less.

  The “glass transition temperature” here is a value indicating heat resistance, and is determined according to the method described in JIS K 7179. Specifically, thermal mechanical 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: And 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 invention. The decomposition temperature here is defined as a temperature at which the mass reduction rate when measured according to the method described in JIS K 7120 is 5%.

The thickness of the cured product layer of the thermosetting resin composition is usually in the range of 1 to 30 μm, and more preferably 1 to 20 μm. If it is too thin, it becomes difficult to produce a cured product layer and the effect of suppressing the exposure of the fiber substrate tends to be reduced. Moreover, when too thick, it will become disadvantageous for thickness reduction of a multilayer printed wiring board. The thickness can be easily controlled by adjusting the amount of the thermosetting resin composition applied to the support layer .

The insulating resin sheet of the present invention can be obtained by bonding the cured product layer of the thermosetting resin composition and the prepreg. For example, a method of laminating and bonding a cured product sheet composed of a support layer and a cured product layer of a thermosetting resin composition on one side of a prepreg, and laminating and adhering a prepreg to a cured product layer of the cured product sheet A method is mentioned. The cured product sheet and the prepreg may be wound into rolls and laminated in a continuous manner, or both roll-like sheets may be cut and laminated in a single wafer manner.

  The total thickness of the prepreg layer and the cured product layer of the thermosetting resin composition in the insulating resin sheet of the present invention is usually in the range of 11 μm to 100 μm, more preferably in the range of 13 to 70 μm, and particularly in the range of 13 to A range of 55 μm is preferred. If the thickness of the insulating resin sheet is too thin, circuit embedding tends to be insufficient in forming the insulating layer, and manufacturing is difficult. Moreover, when the thickness of the insulating resin sheet is too thick, it is disadvantageous for making the multilayer printed wiring board thinner.

In the insulating resin sheet of the present invention, the prepreg surface not bonded to the cured product layer is preferably protected by a protective film for the purpose of preventing dents and scratches on the surface and preventing foreign matter from adhering. As the protective film, the same plastic film as described in the explanation of the support layer can be used. The thickness of the protective film is usually 1 to 40 μm, preferably 10 to 30 μm.

The method for producing a multilayer printed wiring board of the present invention includes a step of laminating the insulating resin sheet of the present invention on one or both sides of an inner circuit board, and curing the insulating resin sheet to form an insulating layer. The following steps (1) to (3) are included.
(1) An insulating resin sheet is placed on an inner layer circuit board so that the prepreg is in contact with both sides or one side of the inner layer circuit board, and is laminated on the circuit board by heating and pressing through an elastic material under reduced pressure. Laminating step, (2) smoothing step of heating and pressing the laminated insulating resin sheet with a metal plate or metal roll, and (3) forming the insulating layer by thermosetting the smoothed insulating resin sheet Thermosetting process.

  Here, the thickness of the insulating layer basically follows the total thickness of the cured product layer of the thermosetting resin composition and the prepreg. Therefore, the thickness of the insulating layer is usually 11 to 100 μm, preferably 13 to 70 μm, more preferably 13 to 55 μm.

The laminating process will be described. Lamination is generally performed by laminating the insulating resin sheet on the inner layer circuit board by heating and pressing the insulating resin sheet on the inner layer circuit board under reduced pressure. Under reduced pressure is an atmosphere in which the air pressure is reduced to 20 mmHg (26.7 hPa) or less. In the laminating process, heating and pressurization can be performed by pressing a heated metal plate such as a SUS mirror plate from the support layer side. The insulating resin sheet is pressed through an elastic material such as heat-resistant rubber so that the insulating resin sheet sufficiently follows. The temperature of the press is preferably 70 to 140 ° C. (more preferably 80 to 130 ° C.), and the pressure is preferably 1 to 11 kgf / cm ² (9.8 × 10 ^{4 to} 107.9 × 10 ⁴ N / m ² ). It is done in the range.

  After the laminating step, the laminated insulating resin sheet is smoothed. The smoothing step is generally performed by heating and pressurizing the insulating resin sheet with a metal plate such as a heated SUS mirror plate or a metal roll under normal pressure (under atmospheric pressure). The smoothing is more preferably performed using a metal plate. As 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 process or the smoothing process, a thermosetting process is performed. In the thermosetting step, the insulating resin sheet is thermoset to form an insulating layer. In the thermosetting process, the prepreg layer is mainly thermoset. The thermosetting conditions vary depending on the type of the thermosetting resin composition, but generally the curing temperature is 150 to 200 ° C. and the curing time is 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. 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. In the manufacturing method of the multilayer printed wiring board of this invention, you may further include the process of peeling a support body layer from the thermosetting insulating resin sheet. Peeling of the support layer is preferably performed after the thermosetting process or the drilling process. The support layer may be peeled manually or mechanically by an automatic peeling device. When a metal foil is used as the support layer , it may be removed by etching with an etching solution.

  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 is generally performed in a core substrate, and a built-up insulating layer is generally conducted by a via hole. In general, a mechanical drill is 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 SBU) and Swelling Dip Securiganth SBU (manufactured by Atotech 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 circuit board by heating after forming the conductor layer, and a conductor layer A circuit forming step for forming a circuit 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. For the copper plating layer, a method in which electroless copper plating and electrolytic copper plating are combined is usually used, but a plating resist having a pattern opposite to that of the conductor layer may be formed, and the conductor layer may be formed only by electroless copper plating. Is possible. 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 formed as a 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 electroplating layer having a desired thickness is formed, the pattern resist is peeled off, and the electroless plating layer is removed by flash etching. Thus, a circuit can be formed.

  The “inner layer circuit board” in the present invention is a pattern processed on one or both sides of a glass epoxy board, metal board, polyester board, polyimide board, BT resin board, thermosetting polyphenylene ether board (circuit formation). I) An intermediate product that has a conductor layer and in which a multilayer printed wiring board is to be further formed with an insulating layer and a conductor layer. In addition, it is preferable from the viewpoint of the adhesiveness of the insulating layer to the inner layer 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”.

(Create resin varnish)
Polyvinyl butyral resin (“KS-1” manufactured by Sekisui Chemical Co., Ltd.) in a solvent in which ethanol and toluene are mixed at a ratio of 1: 1 (mass ratio) at 60 ° C. so that the solid content is 15%. It was dissolved to obtain a polyvinyl butyral resin solution. 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.) "HP4700") was dissolved in a mixed 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 Toto 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 were mixed and dispersed uniformly with a high-speed rotary mixer. A resin varnish was prepared.

(Manufacture of cured product sheet)
Uniformly with a die coater so that the thickness of the thermosetting resin composition layer after drying is 15 μm on the release treatment surface of the PET film (38 μm) treated with the alkyd mold release agent. By applying and drying at 80 to 120 ° C. (average 100 ° C.) for 6 to 8 minutes, an adhesive sheet having a minimum melt viscosity of 1300 poise of the thermosetting resin composition layer was obtained. A 15 μm-thick polypropylene film was bonded as a protective film on the surface of the adhesive sheet and wound up in a roll shape. Thereafter, the roll-shaped adhesive sheet was slit to a width of 502 mm to obtain a 50-roll adhesive sheet. The protective film of the adhesive sheet was peeled off and thermally cured at 150 ° C. for 15 minutes, 160 ° C. for 15 minutes, 170 ° C. for 15 minutes, and 180 ° C. for 15 minutes, respectively, and the glass transition temperature of the cured product of the thermosetting resin composition was 86 respectively. A cured product sheet having temperatures of 99 ° C, 99 ° C, 113 ° C, and 129 ° C was obtained. On the other hand, in the same manner, a thermosetting resin composition layer having a thickness of 10 μm and a roll adhesive sheet having a thickness of 5 μm is obtained, the protective film is peeled off, and the thermosetting resin composition is thermally cured at 180 ° C. for 15 minutes. Two types of cured sheets having a glass transition temperature of 129 ° C. of the cured product were obtained.

(Manufacture of prepreg)
The resin varnish was impregnated into Arisawa Seisakusho 1015NS glass cloth (thickness 16 μm) and then dried until the residual solvent amount in the resin became 0.6% to obtain a prepreg having a thickness of 35 μm. Next, a 15 μm thick polypropylene film was laminated on one side of the prepreg, and a 38 μm PET film was laminated on the other side.

(Manufacture of insulating resin sheets)
The prepreg from which the polypropylene film has been peeled is placed on the cured surface of the cured sheet having a glass transition temperature of 86 ° C. of the cured product of the thermosetting resin composition, and a vacuum pressure laminator manufactured by Meiki Seisakusho is used. In use, after vacuum suction at a temperature of 120 ° C. for 30 seconds, lamination was carried out for 30 seconds via a heat-resistant rubber on the PET film under the conditions of a temperature of 120 ° C. and a pressure of 7.0 kg / cm ² . 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.

(Lamination of insulating resin sheet)
The obtained insulating resin sheet was laminated on both surfaces of an inner layer circuit board (IPC MULTI-PURPOSE TESTBOARD No. IPC-B-25, 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 80 ° C., and then a PET film under the conditions of a temperature of 80 ° C. and a pressure of 7.0 kg / cm ^2. From above, lamination was carried out by pressing through heat-resistant rubber for 60 seconds. Next, pressing was performed for 90 seconds under conditions of a temperature of 80 ° C. and a pressure of 5.5 kg / cm ² using an SUS end plate under atmospheric pressure.

(Curing resin composition)
The PET film was peeled off from the laminated insulating resin sheet, and the thermosetting resin composition (prepreg) 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 manufactured by Atotech Japan Co., Ltd. for 5 minutes at 60 ° C. Then, as an oxidation treatment, manufactured by Atotech Japan Co., Ltd. Concentrate Compact CP and Dosing Solution Securiganth P500 for 20 minutes at 80 ° C. Then, as a reduction treatment, Reduction Solution Securiganth P500 manufactured by Atotech Japan Co., Ltd. ) 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 laminate using an activator neogant 834 made of Atotech Japan, which contains palladium, a print gantt made of Atotech Japan, containing tartrate. Electroless plating was performed using MSK-DK. Next, electrolytic plating was performed using copper sulfate so that the copper thickness was about 20 μm. Thereafter, curing was performed at 180 ° C. for 30 minutes to obtain a multilayer printed wiring board.

  As the cured product sheet, a cured product sheet having a glass transition temperature of 99 ° C. (a thickness of the thermosetting resin composition layer (cured product layer) of 15 μm) was used in the same manner as in Example 1, A multilayer printed wiring board was obtained.

  As the cured product sheet, except that a cured product sheet having a glass transition temperature of 113 ° C. (the thickness of the thermosetting resin composition layer (cured product layer) is 15 μm) was used, as in Example 1, A multilayer printed wiring board was obtained.

  A multilayer printed wiring board was obtained in the same manner as in Example 1 except that the insulating resin sheet was laminated on the inner circuit board and the temperature in the smoothing step was 100 ° C.

  As a cured product sheet, a cured product sheet having a glass transition temperature of 99 ° C. (a thickness of a thermosetting resin composition layer (cured product layer) of 15 μm) is used, and the insulating resin sheet is laminated on the inner circuit board. And the multilayer printed wiring board was obtained like Example 1 except the temperature of a smoothing process being 100 degreeC.

  As a cured product sheet, a cured product sheet having a glass transition temperature of 113 ° C. (thermosetting resin composition layer (cured product layer) thickness of 15 μm) is used, and the insulating resin sheet is laminated on the inner circuit board. And the multilayer printed wiring board was obtained like Example 1 except the temperature of a smoothing process being 100 degreeC.

  A multilayer printed wiring board was obtained in the same manner as in Example 1 except that the insulating resin sheet was laminated on the inner circuit board and the temperature in the smoothing step was 120 ° C.

  As a cured product sheet, a cured product sheet having a glass transition temperature of 99 ° C. (a thickness of a thermosetting resin composition layer (cured product layer) of 15 μm) is used, and the insulating resin sheet is laminated on the inner circuit board. And the multilayer printed wiring board was obtained like Example 1 except the temperature of a smoothing process being 120 degreeC.

  As a cured product sheet, a cured product sheet having a glass transition temperature of 113 ° C. (thermosetting resin composition layer (cured product layer) thickness of 15 μm) is used, and the insulating resin sheet is laminated on the inner circuit board. And the multilayer printed wiring board was obtained like Example 1 except the temperature of a smoothing process being 120 degreeC.

  As a cured product sheet, a cured product sheet having a glass transition temperature of 129 ° C. (a thickness of a thermosetting resin composition layer (cured product layer) of 15 μm) is used, and the insulating resin sheet is laminated on the inner circuit board. And the multilayer printed wiring board was obtained like Example 1 except the temperature of a smoothing process being 100 degreeC.

  As the cured product sheet, a cured product sheet having a glass transition temperature of 129 ° C. (the thickness of the thermosetting resin composition layer (cured product layer) is 10 μm) is used, and the insulating resin sheet is laminated on the inner circuit board. And the multilayer printed wiring board was obtained like Example 1 except the temperature of a smoothing process being 100 degreeC.

  As the cured product sheet, a cured product sheet having a glass transition temperature of 129 ° C. (the thickness of the thermosetting resin composition layer (cured product layer) is 5 μm) is used, and the insulating resin sheet is laminated on the inner circuit board. And the multilayer printed wiring board was obtained like Example 1 except the temperature of a smoothing process being 100 degreeC.

  As a cured product sheet, a cured product sheet having a glass transition temperature of 129 ° C. (a thickness of a thermosetting resin composition layer (cured product layer) of 15 μm) is used, and the insulating resin sheet is laminated on the inner circuit board. And the multilayer printed wiring board was obtained like Example 1 except the temperature of a smoothing process being 120 degreeC.

  As the cured product sheet, a cured product sheet having a glass transition temperature of 129 ° C. (the thickness of the thermosetting resin composition layer (cured product layer) is 10 μm) is used, and the insulating resin sheet is laminated on the inner circuit board. And the multilayer printed wiring board was obtained like Example 1 except the temperature of a smoothing process being 120 degreeC.

  As the cured product sheet, a cured product sheet having a glass transition temperature of 129 ° C. (the thickness of the thermosetting resin composition layer (cured product layer) is 5 μm) is used, and the insulating resin sheet is laminated on the inner circuit board. And the multilayer printed wiring board was obtained like Example 1 except the temperature of a smoothing process being 120 degreeC.

<Comparative Example 1>
A multilayer printed wiring board was obtained in the same manner as in Example 1 except that only the 50 μm thick prepreg layer was used instead of the insulating resin sheet. 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 2>
A multilayer printed wiring board was obtained in the same manner as in Example 1 except that an adhesive sheet (adhesive sheet used for producing the cured product sheet in Example 1) was used instead of the cured product sheet.

  Evaluation about the hardened | cured material sheet | seat, prepreg, insulating resin sheet, and multilayer printed board which were obtained by the above Example and the comparative example was performed as follows. The results are shown in Table 1 below.

(Evaluation of liquidity)
Using a vacuum pressure laminator manufactured by Meiki Seisakusho Co., Ltd., cut the cured sheet into a rectangle with a planar size of 12 cm x 15 cm, and concentrate it on a 20 cm square 0.8 mm thick FR4 substrate. The sample was placed, laminated and smoothed under the same conditions as in the examples and comparative examples, and the fluidity was evaluated based on the length of the spots. Laminating is performed by vacuum suction at a temperature of 80 ° C. for 30 seconds, and then smoothed by pressing from a PET film through a heat-resistant rubber for 60 seconds under the conditions of a temperature of 80 ° C. and a pressure of 7.0 kg / cm ² . Was pressed for 90 seconds under the conditions of a temperature of 80 ° C. and a pressure of 5.5 kg / cm ² using an SUS end plate under atmospheric pressure. After pressing, the maximum bleed length of the resin protruding from the four sides was measured.
The stain length is the length in the direction perpendicular to the end (end) of the resin that protrudes from the end (end) of the PET film, and is a CCD microscope (manufactured by Keyence Corporation). , VH6300).

(Measurement of glass transition temperature)
A small piece of the cured layer of the thermosetting resin composition in the cured sheet obtained in Examples and Comparative Examples was used as a sample, and a model DMS-6100 manufactured by Seiko Instruments Inc. was used as a thermomechanical analyzer (DMA). , And measured in “tensile mode”. This measurement was performed in the range of 25 ° C. to 240 ° C. at a temperature increase of 2 ° C./min. A value obtained by rounding off the first decimal place of the maximum value of the loss tangent (tan δ) obtained by the ratio between the storage elastic modulus (E ′) and the loss elastic modulus (E ″) obtained by the measurement was taken as the glass transition temperature. If it was uncured and could not be measured, the measurement was impossible.

(Measurement of minimum melt viscosity)
Model Rheosol-G3000 manufactured by UBM Co., Ltd. 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 heating rate of 5 ° C./min, and a frequency of 1 Hz / deg. The lowest viscosity value (η) was taken as the lowest melt viscosity.
The minimum melt viscosity of the thermosetting resin composition of the prepreg layer used in the examples and comparative examples was about 1500 poise. Further, the melt viscosity of the cured product layer of the example was 500,000 poise or more and could not be measured. The minimum melt viscosity of the thermosetting resin composition layer of Comparative Example 2 was about 1600 poise.

(Measurement of insulation resin sheet, cured sheet layer, and prepreg thickness)
It measured using the contact-type film thickness meter (Mitutoyo Co., Ltd. product, MCD-25MJ).

(Exposed glass cloth and remaining copper plating)
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). In addition, 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]
○: The glass cloth is not exposed on the resin surface of the P coupon, and there is no plating copper residue.
X: The glass cloth is exposed on the resin surface of the P coupon, or there is a plated copper residue in that place.

(Embedment into circuit)
The laminated board which cut out the cross section of the level | step-difference part of the P coupon part in a 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 filling is insufficient.

  As is apparent from the results shown in Table 1, the insulating resin sheets comprising the prepregs and cured product layers of Examples 1 to 15 were laminated to the inner circuit board and cured, and then subjected to roughening treatment. Was not exposed on the resin surface, and there was no plated copper residue. On the other hand, in Comparative Example 1 in which the prepreg was used alone and in Comparative Example 2 in which the insulating resin sheet composed of the prepreg and the thermosetting resin composition layer (uncured) was used, the exposure of the glass cloth due to the roughening treatment was observed. It was done.

  The present invention relates to a method for manufacturing an insulating resin sheet useful for forming an insulating layer of a multilayer printed wiring board. By using an insulating resin sheet obtained by the manufacturing method, the surface of the prepreg is roughened even if the surface of the insulating layer is roughened. A highly reliable multilayer printed wiring board can be produced without exposing the fiber base material. The obtained multilayer printed wiring board is used as, for example, a high-density small-sized printed wiring board on which a semiconductor chip is mounted, and a small and lightweight new semiconductor in which the core substrate is thinned or omitted. It can also be expected to be used as a package material.

  This application is based on Japanese Patent Application No. 2008-078624 filed in Japan, the contents of which are incorporated in full herein.

Claims (11)

Having a cured product layer of a thermosetting resin composition on one side of the prepreg,
Further having a support layer on the cured product layer,
The cured product layer side of the support layer is subjected to a release treatment,
The thickness of the cured product layer is 1 to 15 μm,
The prepreg is an insulating resin sheet containing a sheet-like fiber base material,
The glass transition temperature of the cured product layer, or the decomposition temperature at which the mass reduction rate of the cured product layer is 5% is 80 ° C. or higher, or
The cured product layer is cut into a rectangle having a planar size of 12 cm × 15 cm, vacuum suctioned at a temperature of 80 ° C. for 30 seconds, and then pressed through a heat resistant rubber for 60 seconds at a temperature of 80 ° C. and a pressure of 7.0 kgf / cm ^2. The maximum bleed length of the resin is 0.3 mm or less when pressed for 90 seconds at a temperature of 80 ° C. and a pressure of 5.5 kgf / cm ² using a SUS end plate under atmospheric pressure. Oh Ru, insulating resin sheet. Sheet of the cured product cured product layer formed of the thermosetting resin composition is adhered to one surface of the prepreg on a support layer, an insulating resin sheet according to claim 1. The insulating resin sheet according to claim 1 or 2 , wherein the support layer is a plastic film. The insulating resin sheet according to any one of claims 1 to 3 , wherein the thickness of the prepreg is 10 to 70 µm. The insulating resin sheet according to any one of claims 1 to 3 , wherein the thickness of the prepreg is 10 to 40 µm. The insulating resin sheet according to any one of claims 1 to 5, wherein the prepreg surface of the insulating resin sheet is protected by a protective film. (1) A laminating process in which an insulating resin sheet is placed on an inner layer circuit board so as to be in contact with both surfaces or one side of the inner layer circuit board, and is laminated on the inner layer circuit board by heating and pressing through an elastic material under reduced pressure. (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 any one of Claims 1-5 used for the manufacturing method of the multilayer printed wiring board containing the thermosetting process to do. The multilayer printed wiring board with which the insulating layer was formed with the insulating resin sheet of any one of Claims 1-5 . (1) The insulating resin sheet according to any one of claims 1 to 5 is placed on the inner circuit board so that the prepreg layer is in contact with both surfaces or one surface of the inner circuit board, and the elastic material is interposed under reduced pressure. Laminating step for laminating on the inner circuit board by heating and pressurizing, (2) smoothing step for heating and pressurizing the laminated insulating resin sheet with a metal plate or metal roll, and (3) smoothing A method for producing a multilayer printed wiring board, comprising a thermosetting step of thermosetting the insulating resin sheet.   The method according to claim 9, wherein heating and pressurization of the insulating resin sheet in the laminating step and the smoothing step are performed from above the support layer.   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 method according to claim 9 or 10, further comprising: