Insulating resin material and printed wiring board

Abstract

The present disclosure provides a resin sheet (3) which can be used to make an insulating layer having a conductor embedded therein, and with which it is easy to embed the conductor in the insulating layer and moldability is unlikely to deteriorate. This resin sheet (3) contains an uncured product or a semi-cured product of a thermosetting resin composition (X1). The melt viscosity measured using an elevated flow tester is 10 Pa·s to 2,000 Pa·s inclusive at measurement conditions of 130°C and 1 MPa and is 6 Pa·s to 1,200 Pa·s inclusive at measurement conditions of 130°C and 4 MPa.

Description

[Technical Field]

[0001] The present disclosure relates to a resin sheet, a prepreg, an insulating resin material, and a printed wiring board, and more particularly to a resin sheet and a prepreg that can be used to prepare an insulating layer of a printed wiring board, an insulating resin material comprising the resin sheet and the prepreg, and a printed wiring board comprising an insulating layer prepared from the resin sheet and the prepreg. [Background technology]

[0002] Patent Document 1 discloses a method for producing a multilayer printed wiring board by forming a laminate by disposing a heat-meltable and thermosetting resin sheet between the exposed via hole surface of a substrate and a prepreg containing an inorganic filler. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-37362 Summary of the Invention

[0004] An object of the present disclosure is to provide a resin sheet and prepreg that can be used to prepare an insulating layer in which a conductor is embedded, that allows the conductor to be easily embedded in the insulating layer, and that is less likely to deteriorate in formability, an insulating resin material that includes the resin sheet and the prepreg, and a printed wiring board that includes an insulating layer prepared from the resin sheet and the prepreg.

[0005] A resin sheet according to one embodiment of the present disclosure includes an uncured or semi-cured product of a thermosetting resin composition (X1), and has a melt viscosity of 10 Pa·s or more and 2000 Pa·s or less at 130°C and 1 MPa, as measured using a high-temperature flow tester, and a melt viscosity of 6 Pa·s or more and 1200 Pa·s or less at 130°C and 4 MPa.

[0006] A prepreg according to one embodiment of the present disclosure is used together with the resin sheet and comprises a substrate and an uncured or semi-cured product of thermosetting resin composition (X2) impregnated into the substrate, and the uncured or semi-cured product of thermosetting resin composition (X2) has a melt viscosity of 500 Pa s or more and 6000 Pa s or less under measurement conditions of 130°C and 4 MPa, as measured using a Koka-shiki flow tester.

[0007] An insulating resin material according to one aspect of the present disclosure includes the resin sheet and the prepreg overlapping the resin sheet.

[0008] A printed wiring board according to one aspect of the present disclosure includes a core material including an insulating substrate and a conductor overlapping the insulating substrate, and an insulating layer overlapping the core material and covering the conductor, the insulating layer including a first layer in contact with the core material that is a cured product of the resin sheet, and a second layer overlapping the first layer that is a cured product of the prepreg. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view of a prepreg, a resin sheet, a core material, and a laminate constituted of the prepreg, the resin sheet, and the core material in one embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic cross-sectional view of a printed wiring board according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] According to the inventor's research, when a printed wiring board is produced by stacking a resin sheet and a prepreg on top of a conductor and laminating them together to produce an insulating layer made of a cured product of the resin sheet and prepreg on top of the conductor, and embedding the conductor in the cured product of the resin sheet, if the conductor is thick, it becomes difficult to sufficiently embed the conductor in the cured product of the resin sheet, and even if the conductor can be embedded, the formability when forming the insulating layer from the resin sheet and prepreg is likely to deteriorate.

[0011] Therefore, the inventors conducted research and development to develop a resin sheet that can be used to create an insulating layer in which a conductor is embedded, that makes it easy to embed a conductor in the insulating layer, and that is less likely to deteriorate in formability, and has led to the completion of the present disclosure.

[0012] An embodiment of the present disclosure will be described below. Note that the embodiment described below is merely one of various embodiments of the present disclosure. The following embodiment can be modified in various ways depending on the design as long as the object of the present disclosure can be achieved.

[0013] The resin sheet 3 according to this embodiment includes an uncured or semi-cured thermosetting resin composition (X1) (hereinafter also referred to as composition (X1)). The melt viscosity measured using a high-temperature flow tester at 130°C and 1 MPa is 10 Pa·s or more and 2000 Pa·s or less, and the melt viscosity measured at 130°C and 4 MPa is 6 Pa·s or more and 1200 Pa·s or less. The uncured product may be composition (X1) itself, or, if composition (X1) contains a solvent, may be a product produced by volatilizing the solvent from composition (X1) without proceeding with the curing reaction of composition (X1). The semi-cured product is a product produced by partially curing composition (X1), which is in a so-called B-stage state.

[0014] An insulating layer 8 in which a conductor 9 is embedded can be produced from this resin sheet 3. This allows the resin sheet 3 to be used, for example, to produce the insulating layer 8 in a printed wiring board 5. In this embodiment, when the insulating layer 8 in which a conductor 9 is embedded is produced from the resin sheet 3, the conductor 9 can be easily embedded in the insulating layer 8 and moldability is not easily impaired.

[0015] The prepreg 2 according to this embodiment is used by being layered on a resin sheet 3. It comprises a substrate 4 and an uncured or semi-cured product of a thermosetting resin composition (X2) (hereinafter also referred to as composition (X2)) impregnated into the substrate 4. The uncured or semi-cured product of composition (X2) has a melt viscosity of 500 Pa·s or more and 6000 Pa·s or less at 130°C and 4 MPa, as measured using a high-temperature flow tester. The uncured product may be composition (X2) itself, or may be a product produced by volatilizing the solvent from composition (X2) without proceeding with the curing reaction of composition (X2) if the composition (X2) contains a solvent. The semi-cured product is a product produced by partially curing composition (X2), which is in a so-called B-stage state.

[0016] An insulating layer 8 in which a conductor 9 is embedded can be produced from the prepreg 2 and the resin sheet 3. This allows the prepreg 2 and the resin sheet 3 to be used, for example, to produce the insulating layer 8 in a printed wiring board 5. In this embodiment, when the insulating layer 8 in which a conductor 9 is embedded is produced from the prepreg 2 and the resin sheet 3, the conductor 9 is particularly easily embedded in the insulating layer 8, and moldability is particularly unlikely to deteriorate.

[0017] The preparation of insulating layer 8 and the manufacturing of printed wiring board 5 will be described with reference to FIGS.

[0018] To produce the insulating layer 8 from the prepreg 2 and the resin sheet 3, specifically, as shown in FIG. 1, a core material 11 including a conductor 9 such as a conductor wiring is prepared. The core material 11 includes, for example, an insulating substrate 10 and the conductor 9 overlapping the insulating substrate 10. There are no particular restrictions on the materials of the insulating substrate 10 and the conductor 9 as long as they are applicable as materials for printed wiring boards. The insulating substrate 10 is, for example, a resin substrate such as a glass-based epoxy resin substrate, and the conductor 9 is, for example, copper wiring produced by an additive method, a subtractive method, or the like.

[0019] In the example shown in Figure 1, the core material 11 has, as conductors 9, a first conductor 91 overlapping one surface (first surface 101) of the insulating substrate 10 and a second conductor 92 overlapping a second surface 102 of the insulating substrate 10 opposite the first surface 101.

[0020] An electronic component 13 may be mounted on the surface of the core material 11 on which the conductor 9 is located. The electronic component 13 is, for example, an IC, an LSI, or the like, but is not limited to these.

[0021] As shown in Fig. 1, a core material 11, a resin sheet 3, and a prepreg 2 are stacked in this order so that the conductor 9 and the resin sheet 3 face each other, thereby obtaining a laminate 12. As shown in Fig. 1, the laminate 12 may further include a metal foil 14. In this case, the core material 11, the resin sheet 3, the prepreg 2, and the metal foil 14 are stacked in this order so that the conductor 9 and the resin sheet 3 face each other, thereby obtaining the laminate 12, as shown in Fig. 1. The metal foil 14 is, for example, copper foil, but is not limited to this.

[0022] 1 , a resin sheet 3, a prepreg 2, and a metal foil 14 are laminated in this order on the first conductor 91 side of the core material 11, and a resin sheet 3, a prepreg 2, and a metal foil 14 are laminated in this order on the second conductor 92 side of the core material 11. That is, the metal foil 14, the prepreg 2, the resin sheet 3, the core material 11, the resin sheet 3, the prepreg 2, and the metal foil 14 are laminated in this order. Note that the resin sheet 3 and the prepreg 2 may be laminated on only one side of the core material 11.

[0023] The laminate 12 is heat-pressed. As a result, the resin sheet 3 first softens or melts, reducing its viscosity, and flows to conform to the shape of the conductors 9. If electronic components 13 are mounted on the core material 11, the resin sheet 3 also flows to conform to the shape of the electronic components 13. As a result, the conductors 9 are embedded in the resin sheet 3. If electronic components 13 are mounted on the core material 11, the electronic components 13 are also embedded in the resin sheet 3. Next, the resin sheet 3 is cured. As a result, a first layer 7, which is a cured product of the resin sheet 3, is produced, and the conductors 9 are embedded in this first layer 7. If electronic components 13 are mounted on the core material 11, the electronic components 13 are also embedded in the first layer 7.

[0024] The prepreg 2 also first softens or melts, reducing its viscosity and allowing it to flow, and then hardens to form the second layer 6. In this way, the printed wiring board 5 shown in FIG. 2 is manufactured.

[0025] The printed wiring board 5 includes an insulating substrate 10, a conductor 9, and an insulating layer 8, which are laminated in this order. When the laminate 12 includes a metal foil 14, the printed wiring board 5 further includes the metal foil 14 overlapping the insulating layer 8. Conductor wiring may be produced by patterning the metal foil 14, for example by etching. In this case, the printed wiring board 5 includes conductor wiring overlapping the insulating layer 8. When an electronic component 13 is mounted on the core material 11, the printed wiring board 5 also includes the electronic component 13. The insulating layer 8 includes a second layer 6 that is a cured product of the prepreg 2 and a first layer 7 that is a cured product of the resin sheet 3, and the conductor 9 is located on the opposite side of the first layer 7 from the second layer 6. In this embodiment, the conductor 9 and the electronic component 13 are embedded in the first layer 7.

[0026] When printed wiring board 5 is manufactured in this manner, conductors 9 can be embedded in insulating layer 8 by flowing softened or melted resin sheet 3, and the conductors 9 are less likely to come into contact with base material 4 in prepreg 2 within insulating layer 8, which tends to improve the reliability of printed wiring board 5 when heated. Furthermore, within insulating layer 8, there is no base material 4 in first layer 7, but there is a base material 4 in second layer 6, so the number of base materials 4 used can be reduced and the thickness of insulating layer 8 can be easily reduced.

[0027] The conditions for hot pressing the laminate 12 are appropriately set depending on the respective compositions of the composition (X1) and the composition (X2), and for example, the heating temperature is 150°C or higher and 250°C or lower, the pressing pressure is 0.5 MPa or higher and 5 MPa or lower, and the treatment time is 60 minutes or higher and 120 minutes or lower.

[0028] As described above, the melt viscosity η1 of the resin sheet 3 measured using a high-temperature flow tester at 130°C and 1 MPa is 10 Pa·s or more and 2000 Pa·s or less, and the melt viscosity η2 at 130°C and 4 MPa is 6 Pa·s or more and 1200 Pa·s or less. By ensuring that the melt viscosity η1 at 1 MPa is 10 Pa·s or more and the melt viscosity η2 at 4 MPa is 6 Pa·s or more, the first layer 7 is less likely to be unfilled or contain bubbles. This improves the reliability of the printed wiring board 5. Furthermore, by ensuring that the melt viscosity η1 at 1 MPa is 2000 Pa·s or less and the melt viscosity η2 at 4 MPa is 1200 Pa·s or less, resin outflow during the fabrication process of the first layer 7 is less likely. This reduces the variation in thickness of the insulating layer 8 and prevents the conductor 9 from contacting the base material 4 of the prepreg 2, reducing the likelihood of defects in long-term insulation reliability tests. That is, when the conductor 9 and the base material 4 of the prepreg 2 are close to each other, ions tend to move easily along the base material 4, which can cause ion migration, but the presence of the first layer 7 between the conductor 9 and the prepreg 2 makes ion migration less likely to occur. A specific example of a method for measuring the melt viscosity will be described in the Examples below.

[0029] The melt viscosity η2 measured at 130°C and 4 MPa is thought to be particularly related to the fluidity, i.e., filling ability, of the resin sheet 3 when it flows to follow the conductor 9. Relatively high pressure is applied to the portion of the resin sheet 3 surrounding the conductor 9 during molding, and if the melt viscosity η2 is within the above range, the fluidity of this portion is thought to be good and the filling ability is thought to be improved. Furthermore, the melt viscosity η1 measured at 130°C and 1 MPa is thought to be particularly related to the ease with which the resin flows out of the resin sheet 3, i.e., the thickness accuracy of the insulating layer 8. Relatively low pressure is applied to the edge portions of the resin sheet 3 during molding, and if the melt viscosity η1 is within the above range, excessive fluidity in this portion is thought to be less likely to occur, and the resin in the resin sheet 3 is thought to be less likely to leak out.

[0030] The melt viscosity η1 measured under conditions of 130°C and 1 MPa is preferably 30 Pa·s or higher, and even more preferably 50 Pa·s or higher. Furthermore, this melt viscosity η1 is more preferably 1000 Pa·s or lower, and even more preferably 500 Pa·s or lower. The melt viscosity η2 measured under conditions of 130°C and 4 MPa is more preferably 10 Pa·s or higher, and even more preferably 20 Pa·s or higher. Furthermore, this melt viscosity η2 is more preferably 600 Pa·s or lower, and even more preferably 300 Pa·s or lower.

[0031] The thixotropy index (TI) of the resin sheet 3 is preferably 1.1 or more. In this case, resin outflow is particularly unlikely to occur during the production process of the first layer 7. The thixotropy index is defined as the ratio (η1 / η2) of the melt viscosity η1 at the above measurement conditions of 130°C and 1 MPa to the melt viscosity η2 at the above measurement conditions of 130°C and 4 MPa. It is also preferable that this thixotropy index is 15 or less. In this case, the filling property of the insulating layer 8 is likely to be particularly good. The thixotropy index is more preferably 1.2 or more and 8.0 or less, and particularly preferably 1.3 or more and 4.0 or less.

[0032] The resin flow amount of the resin sheet 3, measured by the Glinis method under measurement conditions of 130°C and 0.5 MPa, is preferably 40% or less. In this case, resin outflow during the process of producing the first layer 7 from the resin sheet 3 is further suppressed, the thickness precision of the insulating layer 8 is more likely to be improved, and the conductor 9 is further prevented from contacting the base material 4 in the prepreg 2. This resin flow amount is more preferably 35% or less, and even more preferably 30% or less. Specific examples of methods for measuring the resin flow amount will be described in the Examples below.

[0033] As described above, the melt viscosity of the uncured or semi-cured composition (X2) in prepreg 2 measured at 130°C and 4 MPa using a Koka flow tester is 500 Pa·s or more and 6000 Pa·s or less. This facilitates further improvement in the thickness accuracy of insulating layer 8 and further prevents conductor 9 from contacting substrate 4 in prepreg 2. This is presumably because excessive flow of prepreg 2 is prevented when forming second layer 6 from prepreg 2, thereby preventing excessive flow of resin sheet 3 associated with the flow of prepreg 2. Specific examples of methods for measuring melt viscosity are described in the Examples section below.

[0034] The melt viscosity is more preferably 700 Pa·s or more, and even more preferably 1000 Pa·s or more, and more preferably 5000 Pa·s or less, and even more preferably 4000 Pa·s or less.

[0035] It is preferable that the melt viscosity of the prepreg 2, measured under conditions of 130°C and 4 MPa, be higher than the melt viscosity of the resin sheet 3, measured under conditions of 130°C and 4 MPa, and it is particularly preferable that the melt viscosity of the prepreg 2 be 2000 Pa·s or more.

[0036] The prepreg 2 and the resin sheet 3 will be described in more detail.

[0037] As described above, the resin sheet 3 is an uncured or semi-cured product of the composition (X1). There are no particular limitations on the composition (X1) as long as it can be used to produce the insulating layer 8 of the printed wiring board 5.

[0038] Composition (X1) contains a thermosetting resin. In this embodiment, the thermosetting resin may contain at least one selected from the group consisting of thermosetting monomers, oligomers, and prepolymers. The thermosetting resin may contain at least one selected from the group consisting of epoxy resins, polyimide resins, phenolic resins, bismaleimide triazine resins, and thermosetting polyphenylene ether resins. The epoxy resin may contain at least one component selected from the group consisting of bisphenol A epoxy resins, bisphenol F epoxy resins, cresol novolac epoxy resins, bisphenol A novolac epoxy resins, bisphenol F novolac epoxy resins, naphthalene epoxy resins, biphenyl epoxy resins, dicyclopentadiene epoxy resins, and multifunctional epoxy resins. The epoxy equivalent of the epoxy resin is preferably 120 g / eq or more and 800 g / eq or less, more preferably 170 g / eq or more and 600 g / eq or less. The components that the thermosetting resin may contain are not limited to those listed above.

[0039] The composition (X1) may further contain an appropriate additive selected from the group consisting of a curing agent, a curing accelerator, a flame retardant, a rubber component, an inorganic filler, etc. The composition (X1) may further contain a solvent.

[0040] The curing agent contains at least one selected from the group consisting of, for example, diamine-based curing agents, difunctional or higher phenol-based curing agents, acid anhydride-based curing agents, dicyandiamide, and low-molecular-weight polyphenylene ether compounds. The difunctional or higher phenol-based curing agent contains, for example, bisphenol A novolac phenolic resin. The diamine-based curing agent contains, for example, at least one selected from the group consisting of primary amines and secondary amines. The functional group equivalent of the curing agent is preferably 20 g / eq or more and 500 g / eq or less.

[0041] The curing accelerator contains at least one selected from the group consisting of, for example, imidazole compounds, tertiary amine compounds, organic phosphine compounds, and metal soaps. The imidazole compound contains, for example, 2-ethyl-4-methylimidazole (2E4MZ).

[0042] The flame retardant contains at least one selected from the group consisting of, for example, halogenated flame retardants and non-halogenated flame retardants. The halogenated flame retardant contains, for example, a bromine-containing compound. The non-halogenated flame retardant contains, for example, at least one selected from the group consisting of phosphorus-containing compounds and nitrogen-containing compounds.

[0043] The rubber component contains, for example, elastomer fine particles. The elastomer fine particles contain, for example, core-shell type fine particles having a core-shell structure with a core layer and a shell layer, the shell layer being compatible with the epoxy resin. The polymer constituting the shell layer contains, for example, at least one selected from the group consisting of polymethyl methacrylate, polystyrene, etc. The polymer constituting the core layer contains, for example, at least one selected from the group consisting of acrylic polymers, silicone polymers, butadiene polymers, isoprene polymers, etc.

[0044] The inorganic filler contains at least one selected from the group consisting of, for example, silica, aluminum hydroxide, magnesium hydroxide, aluminum silicate, magnesium silicate, talc, clay, mica, and molybdenum compounds. The silica contains at least one selected from the group consisting of, for example, spherical silica and crushed silica. The molybdenum compound contains, for example, molybdenum trioxide. The content of the inorganic filler is preferably 20 parts by mass or more and 1,400 parts by mass or less per 100 parts by mass of the total mass of the thermosetting resin and curing agent.

[0045] The solvent contains at least one selected from the group consisting of, for example, an appropriate organic solvent, water, etc. The organic solvent contains at least one selected from the group consisting of, for example, benzene, toluene, N,N-dimethylformamide (DMF), acetone, methyl ethyl ketone, methanol, ethanol, cellosolves, etc.

[0046] The components that the composition (X1) can contain are not limited to those mentioned above.

[0047] For example, the composition (X1) may contain a phenoxy resin, which can impart flexibility to the prepreg 2 made from the composition (X1) and reduce the occurrence of powder falling off.

[0048] When producing the resin sheet 3, for example, the composition (X1) is formed into a sheet by a coating method or the like. The coating method may be, for example, a dipping method, a spraying method, a spin coating method, a roll coating method, a curtain coating method, or a screen printing method. Subsequently, the composition (X1) is dried or semi-cured by heating, thereby producing the resin sheet 3.

[0049] The melt viscosity and resin flow rate of the resin sheet 3 can be achieved by appropriately setting the types and amounts of components in the composition (X1), the heating conditions of the composition (X1) when producing the resin sheet 3, etc. 1 ) by blending a low viscosity component into composition (X 1 The melt viscosity of the resin sheet 3 can be reduced and the amount of resin flow can be increased by increasing the amount of low-viscosity components in the composition (X1), lowering the heating temperature, shortening the heating time, etc. In addition, by adjusting the type, particle size, and amount of the inorganic filler in the composition (X1), the melt viscosity at measurement conditions of 130°C and 1 MPa and the melt viscosity at measurement conditions of 130°C and 4 MPa can each be adjusted.

[0050] The thickness of the resin sheet 3 is, for example, 50 μm or more and 200 μm or less. In the example shown in Fig. 1, one resin sheet 3 is used, but two or more resin sheets 3 may be laminated.

[0051] As described above, the prepreg 2 comprises the base material 4 and the uncured or semi-cured product of the composition (X2) impregnated into the base material 4.

[0052] The substrate 4 is, for example, an inorganic fiber woven fabric, an inorganic fiber nonwoven fabric, an organic fiber woven fabric, or an organic fiber nonwoven fabric. The inorganic fiber is, for example, glass fiber or a fiber of an inorganic material other than glass. The glass constituting the glass fiber is, for example, E-glass, D-glass, S-glass, NE-glass, T-glass, or quartz. The organic fiber is, for example, aramid fiber, polyparaphenylene benzobisoxazole (PBO) fiber, polybenzimidazole (PBI) fiber, polytetrafluoroethylene (PTFE) fiber, polyparaphenylene benzobisthiazole (PBZT) fiber, or wholly aromatic polyester fiber.

[0053] The composition (X2) is not particularly limited as long as it can be used to prepare the insulating layer 8 of the printed wiring board 5.

[0054] Composition (X2) contains a thermosetting resin. The thermosetting resin contains at least one component selected from the group consisting of, for example, epoxy resin, polyimide resin, phenol resin, bismaleimide triazine resin, and thermosetting polyphenylene ether resin. The epoxy resin contains at least one component selected from the group consisting of, for example, bisphenol A epoxy resin, bisphenol F epoxy resin, cresol novolac epoxy resin, bisphenol A novolac epoxy resin, bisphenol F novolac epoxy resin, naphthalene epoxy resin, biphenyl epoxy resin, dicyclopentadiene epoxy resin, and multifunctional epoxy resin. The epoxy equivalent of the epoxy resin is preferably 120 g / eq or more and 800 g / eq or less, more preferably 170 g / eq or more and 600 g / eq or less. However, the components that the thermosetting resin may contain are not limited to those described above.

[0055] The composition (X2) may further contain an appropriate additive selected from the group consisting of a curing agent, a curing accelerator, a flame retardant, a rubber component, etc. The composition (X2) may further contain a solvent.

[0056] The curing agent contains at least one selected from the group consisting of, for example, diamine-based curing agents, difunctional or higher phenol-based curing agents, acid anhydride-based curing agents, dicyandiamide, and low-molecular-weight polyphenylene ether compounds. The difunctional or higher phenol-based curing agent contains, for example, bisphenol A novolac phenolic resin. The diamine-based curing agent contains, for example, at least one selected from the group consisting of primary amines and secondary amines. The functional group equivalent of the curing agent is preferably 20 g / eq or more and 500 g / eq or less.

[0057] The curing accelerator contains at least one selected from the group consisting of, for example, imidazole compounds, tertiary amine compounds, organic phosphine compounds, and metal soaps. The imidazole compound contains, for example, 2-ethyl-4-methylimidazole (2E4MZ).

[0058] The flame retardant contains at least one selected from the group consisting of, for example, halogenated flame retardants and non-halogenated flame retardants. The halogenated flame retardant contains, for example, a bromine-containing compound. The non-halogenated flame retardant contains, for example, at least one selected from the group consisting of phosphorus-containing compounds and nitrogen-containing compounds.

[0059] The rubber component contains, for example, elastomer fine particles. The elastomer fine particles contain, for example, core-shell type fine particles having a core-shell structure with a core layer and a shell layer, the shell layer being compatible with the epoxy resin. The polymer constituting the shell layer contains, for example, at least one selected from the group consisting of polymethyl methacrylate, polystyrene, etc. The polymer constituting the core layer contains, for example, at least one selected from the group consisting of acrylic polymers, silicone polymers, butadiene polymers, isoprene polymers, etc.

[0060] The solvent contains at least one selected from the group consisting of, for example, an appropriate organic solvent, water, etc. The organic solvent contains at least one selected from the group consisting of, for example, benzene, toluene, N,N-dimethylformamide (DMF), acetone, methyl ethyl ketone, methanol, ethanol, cellosolves, etc.

[0061] The components that the composition (X2) can contain are not limited to those mentioned above.

[0062] For example, the composition (X2) may contain a phenoxy resin, which imparts flexibility to the resin sheet 3 made from the composition (X2) and can reduce the occurrence of powder falling off.

[0063] The composition (X2) may contain an inorganic filler. When the composition (X2) contains an inorganic filler, the content of the inorganic filler is appropriately adjusted within a range that does not impair the effect of this embodiment.

[0064] The prepreg 2 is prepared by impregnating the substrate 4 with the composition (X2) and then set The prepreg 2 is produced by heating the composition (X2) to dry or semi-cure it. The conditions for heating the composition (X2) are appropriately adjusted depending on the composition of the composition (X2) and the physical properties to be imparted to the prepreg 2.

[0065] The uncured or semi-cured product of composition (X2) in prepreg 2 can have the above melt viscosity by appropriately setting the types and amounts of components in composition (X2) and the heating conditions for composition (X2) when producing prepreg 2. For example, the melt viscosity of the uncured or semi-cured product of composition (X2) can be adjusted by adding a low-viscosity component to composition (X2), increasing the amount of low-viscosity component in composition (X2), lowering the heating temperature, shortening the heating time, or the like.

[0066] By overlapping the resin sheet 3 and the prepreg 2 and hot pressing them, an insulating resin material 1 including the resin sheet 3 and the prepreg 2 overlapping the resin sheet 3 can be produced.

[0067] As described above, the insulating layer 8 can be made from the resin sheet 3 and the prepreg 2, and the printed wiring board 5 having the insulating layer 8 can be manufactured.

[0068] When manufacturing the printed wiring board 5, the thickness of the conductor 9 embedded in the insulating layer 8, i.e., the thickness of the conductor 9 in the core material 11, is, for example, 70 μm or more and 500 μm or less. In this embodiment, even if the conductor 9 is thick in this manner, the conductor 9 can be easily embedded in the insulating layer 8 and formability is not easily deteriorated. Furthermore, if the conductor 9 is thick in this manner, the current value that can be passed through the conductor 9 can be increased accordingly. Therefore, the printed wiring board 5 can also be used for industrial equipment and automotive circuit boards that require high current. The thickness of the conductor 9 is more preferably 100 μm or more and 450 μm or less, and even more preferably 130 μm or more and 420 μm or less. However, the thickness of the conductor 9 is not limited to the above.

[0069] When electronic components 13 are mounted on core material 11, the thickness of electronic components 13 is, for example, 100 μm or more and 500 μm or less. The thickness of electronic components 13 is the maximum height of electronic components 13 in core material 11 relative to the surface of insulating substrate 10. In this embodiment, even if electronic components 13 are thick in this manner, electronic components 13 can be easily embedded in insulating layer 8 and formability is not easily impaired. The thickness of electronic components 13 is more preferably 100 μm or more and 450 μm or less, and even more preferably 130 μm or more and 420 μm or less. However, the thickness of electronic components 13 is not limited to the above. [Example]

[0070] More specific examples of this embodiment will be presented below, but this embodiment is not limited to the following examples.

[0071] 1. Resin sheet (1) Preparation of resin sheet Compositions were prepared by mixing the components shown in the resin sheet composition columns of Tables 1 and 2. Details of the components shown in Tables 1 and 2 are as follows. -Brominated epoxy resin: Brominated bisphenol A epoxy resin. Manufactured by DIC Corporation. Product name: EPICLON 1121N-80M. -Bisphenol A epoxy resin: DIC Corporation. Product name: 1051-75M. -Cresol novolac epoxy resin: DIC Corporation. Product name: EPICLON N-690-75M. -DICY: Dicyandiamide. -2E4MZ: 2-ethyl-4-methylimidazole. -Phenoxy resin: Manufactured by Nippon Steel Chemical & Material Co., Ltd. Part number YP50EK35. - Solvent: a mixed solvent containing methyl ethyl ketone (MEK), propylene glycol monomethyl ether (PGME) and N,N-dimethylformamide (DMF).

[0072] The composition was applied onto a PET film and heated at the heating temperature and for the heating time shown in Tables 1 and 2. As a result, a resin sheet having the thickness shown in Tables 1 and 2 was obtained.

[0073] (2) Resin sheet characteristic test The resin sheet was subjected to the following property tests, the results of which are shown in Tables 1 and 2.

[0074] (2-1) Film properties The resin sheet was subjected to a bending test using a bending tester with a cylindrical mandrel method. The results were rated as "A" when no cracks were observed with a mandrel diameter of 10 mm, "B" when cracks were observed with a mandrel diameter of 10 mm but not with a mandrel diameter of 20 mm, and "C" when cracks were observed with a mandrel diameter of 20 mm.

[0075] (2-2) Melt Viscosity and TI The resin sheet was peeled off from the PET film to obtain a sample. The melt viscosity η1 of this sample was measured using a high-temperature flow tester (Shimadzu Corporation, model FT-500D / 100D) at a temperature of 130°C and a pressure of 1 MPa.

[0076] Similarly, the melt viscosity η2 of the sample was measured under the measurement conditions of a temperature of 130° C. and a pressure of 4 MPa.

[0077] Furthermore, the thixotropy index (η1 / η2) was calculated from the results of the melt viscosity measurements.

[0078] (2-3) Resin flow rate The resin sheet was peeled off from the PET film and cut to prepare a test piece measuring 100 mm x 100 mm.

[0079] The test piece was sandwiched between two release films, and then placed between hot plates and heat-pressed at 130°C, 0.5 MPa, and for 300 seconds.

[0080] The weight (W1) of the test piece before heat pressing was measured. After heat pressing, the test piece was punched out to obtain a sample with a diameter of 80 mm. The weight (W2) of this sample was measured. From this result, the amount of resin flow was calculated using the formula: amount of resin flow = (W1 - 2 × W2) / W1 × 100 (%).

[0081] 2. Prepreg (1) Prepreg preparation Compositions were prepared by mixing the components shown in the prepreg composition columns in Tables 1 and 2. Details of the components shown in Tables 1 and 2 are as follows. -Brominated epoxy resin: Brominated bisphenol A epoxy resin. Manufactured by DIC Corporation. Product name: EPICLON 1121N-80M. -Cresol novolac epoxy resin: DIC Corporation. Product name: EPICLON N-690-75M. -DICY: Dicyandiamide. -2E4MZ: 2-ethyl-4-methylimidazole. -SO-25R: Spherical silica. Manufactured by Admatechs. Product name: SO-25R. -R974: Fumed silica. Manufactured by Nippon Aerosil Co., Ltd. Product name: R974. Silane coupling agent: 3-glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd., product number KBM-403. -Phenoxy resin: Manufactured by Nippon Steel Chemical & Material Co., Ltd. Part number YP50EK35. -Acrylic ester polymer: Nagase Chemtech Corporation. Product name: Teisan Resin SG-P3. - Solvent: a mixed solvent containing methyl ethyl ketone (MEK), propylene glycol monomethyl ether (PGME) and N,N-dimethylformamide (DMF).

[0082] A glass cloth (#1080) made of E-glass was prepared as the substrate, and the substrate was impregnated with the composition, which was then heated at the heating temperature and for the heating time shown in Tables 1 and 2. This resulted in prepregs having the resin contents and thicknesses shown in Tables 1 and 2.

[0083] (2) Melt viscosity The substrate was removed from the prepreg to obtain a sample. The melt viscosity of this sample was measured using a high-temperature flow tester (Shimadzu Corporation, model FT-500D / 100D) at a temperature of 130°C and a pressure of 4 MPa. The results are shown in Tables 1 and 2.

[0084] 3.Evaluation Test (1) Fillability A core material was prepared, comprising an insulating substrate and conductor wiring on both sides of the insulating substrate. The insulating substrate was a glass cloth-based epoxy resin substrate, and each conductor wiring was made of copper, with a remaining copper ratio of 60%. Some core materials also had electronic components mounted on them. The thickness of the conductor in the core material when no electronic components were mounted, and the thickness of the electronic components when electronic components were mounted, are shown in the "Thickness of the conductor or electronic components in the core material" column in Tables 1 and 2.

[0085] One or more resin sheets, prepreg, and 35 μm thick copper foil were stacked on each side of the core material in this order. That is, copper foil, prepreg, one or more resin sheets, core material, one or more resin sheets, prepreg, and copper foil were stacked in this order. The number of resin sheets is as shown in Tables 1 and 2. A laminate was thus obtained. This laminate was heat-pressed at 200°C, 22 MPa, and 60 minutes to obtain a printed wiring board.

[0086] This printed wiring board was cut, and the resulting cross section was polished and then observed to check for the presence or absence of voids between the insulating layer and the conductor wiring and electronic components.

[0087] The same evaluation was also carried out when the remaining copper ratio of the conductor wiring was set to 80%.

[0088] As a result, the case where no voids were observed in either the case where the remaining copper ratio was 60% or 80% was evaluated as "A", the case where voids were observed in the case where the remaining copper ratio was 60% but not in the case where the remaining copper ratio was 80% was evaluated as "B", and the case where voids were observed in both the case where the remaining copper ratio was 60% and 80% was evaluated as "C".

[0089] (2) Plate thickness accuracy A printed wiring board was obtained under the same conditions as in the above "(1) Filling property" (except that the remaining copper ratio of each conductor wiring was only 60%).

[0090] The thickness of the printed wiring board was measured with a micrometer at five positions on the printed wiring board. If the difference between the maximum and minimum of the five measurements obtained was 10% or less of the theoretical thickness of the printed wiring board, it was evaluated as "A", if it was more than 10% but less than 20%, it was evaluated as "B", and if it was more than 20%, it was evaluated as "C".

[0091] [Table 1]

[0092] [Table 2] [Explanation of symbols]

[0093] 1. Insulating resin material 2 Prepreg 3 Resin sheet 4 Base material 5. Printed wiring board 6 Second layer 7 First layer 8. Insulating layer 9 Conductors 10. Insulating substrate 11 Core material 13 Electronic Components 14 Metal foil

Claims

1. A laminated laminated laminate comprising a resin sheet and a prepreg overlapping the resin sheet, The resin sheet is An uncured or semi-cured product of the thermosetting resin composition (X1), The melt viscosity measured using a high-temperature flow tester under the measurement conditions of 130°C and 1 MPa is 10 Pa s or more and 2000 Pa s or less, and the melt viscosity measured under the measurement conditions of 130°C and 4 MPa is 6 Pa s or more and 1200 Pa s or less, The prepreg is A substrate and an uncured or semi-cured product of a thermosetting resin composition (X2) impregnated into the substrate, the uncured or semi-cured product of the thermosetting resin composition (X2) has a melt viscosity of 500 Pa s or more and 6000 Pa s or less at 130°C and 4 MPa, as measured using a Koka-shiki flow tester; Insulating resin material.

2. The resin flow amount of the resin sheet measured by the Glynnis method under measurement conditions of 130 °C and 0.5 MPa is 40% or less. The insulating resin material according to claim 1 .

3. A core material including an insulating substrate and a conductor overlapping the insulating substrate; an insulating layer overlying the core material and covering the conductor; The insulating layer includes a first layer that is a cured product of the resin sheet in the insulating resin material according to claim 1 and that is in contact with the core material, and a second layer that is a cured product of the prepreg in the insulating resin material according to claim 1 and that is overlaid on the first layer. Printed wiring board.

4. The thickness of the conductor is 70 μm or more and 500 μm or less. The printed wiring board according to claim 3 .

5. Further comprising an electronic component mounted on the core material, The electronic component is embedded in the insulating layer. The printed wiring board according to claim 3 or 4.

6. The thickness of the electronic component is 70 μm or more and 500 μm or less. The printed wiring board according to claim 5 .

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