Prepreg, cured product of prepreg, laminate, printed wiring board, and semiconductor package

Abstract

Provided is a prepreg capable of suppressing the occurrence of molding defects in an insulating layer. Further provided are a cured product of a prepreg obtainable using the prepreg, a laminate, a printed wiring board, and a semiconductor package. Specifically, the prepreg contains a fiber base material, and a thermosetting resin composition or a semi-cured product of the thermosetting resin composition. The thermosetting resin composition contains (B) an inorganic filler having a volume average particle diameter of 2.0 μm or more. The thermosetting resin composition or the semi-cured product of the thermosetting resin composition protrudes from the surface of the fiber base material, and the thickness of the layer of the thermosetting resin composition or the semi-cured product of the thermosetting resin composition protruding from the surface of the fiber base material is 10 μm or more.

Description

Prepreg, cured product of prepreg, laminate, printed wiring board, and semiconductor package

[0001] The present disclosure relates to a prepreg, a cured product of the prepreg, a laminate, a printed wiring board, and a semiconductor package.

[0002] In recent years, the demand for high-performance and large-sized semiconductor package substrates has been increasing. To increase the size of semiconductor package substrates, it has been proposed to use a glass plate as a core substrate instead of an organic material (for example, a prepreg containing a glass cloth and a resin composition), which is an existing substrate material. However, since the organic material has important properties such as high adhesiveness to the conductor layer, there is also a demand for the development of a technology for increasing the size of semiconductor package substrates while still using the organic material as the core substrate. Another problem is that large semiconductor package substrates are prone to warping. When an organic material is used as the core substrate of a large-sized semiconductor package, the organic material has less rigidity than a glass plate, so the semiconductor package tends to warp more easily than when a glass plate is used. As a method for increasing the rigidity of the organic material, it is conceivable to contain an inorganic filler. As a resin composition containing an inorganic filler, for example, the resin composition described in Patent Document 1 is known.

[0003] Japanese Patent Application Laid-Open No. 2024-119896

[0004] In the examples of Patent Document 1, silica having an average particle diameter of 0.5 μm is used as the inorganic filler. By using an inorganic filler having a small average particle diameter in this way, the thickness of the thermosetting resin composition layer on the prepreg can be reduced, and thereby, it becomes easier to exhibit the effects of high elasticity and low thermal expansion due to the glass cloth. However, as a result of intensive studies by the present inventors, in the case of a resin composition containing an inorganic filler having a small average particle diameter, when the blending amount of the inorganic filler is increased to obtain higher rigidity (elastic modulus), it has been found that the tendency of forming defects in the formed insulating layer increases. Since the forming defects can cause deterioration of insulation reliability, it is required to suppress the occurrence of forming defects.

[0005] In view of the current situation, this disclosure aims to provide a prepreg that can suppress the occurrence of molding defects in the insulating layer, and to provide a cured prepreg, a laminate, a printed wiring board, and a semiconductor package obtained using the prepreg.

[0006] As a result of diligent research, the inventors have found that the thermosetting resin composition of this disclosure can achieve the above objective.

[0007] This disclosure includes the embodiments described in [1] to

[11] below. [1] A prepreg comprising a fibrous substrate and a thermosetting resin composition or a semi-cured product of the thermosetting resin composition, wherein the thermosetting resin composition contains (B) an inorganic filler with a volume average particle diameter of 2.0 μm or more, the thermosetting resin composition or the semi-cured product of the thermosetting resin composition protrudes from the surface of the fibrous substrate, and the thickness of the layer of the thermosetting resin composition or the semi-cured product of the thermosetting resin composition protruding from the surface of the fibrous substrate is 10 μm or more. [2] The prepreg according to [1] above, wherein the volume average particle diameter of component (B) is 50% or less of the thickness of the layer of the thermosetting resin composition or the semi-cured product of the thermosetting resin composition protruding from the surface of the fibrous substrate. [3] The prepreg according to [1] or [2] above, wherein the content of component (B) in the thermosetting resin composition is 55% by volume or more with respect to the total amount of solids. [4] The prepreg according to any one of [1] to [3] above, wherein the component (B) is one or more selected from the group consisting of silica, alumina, titanium oxide, mica, beryllium, barium titanate, potassium titanate, strontium titanate, calcium titanate, aluminum carbonate, magnesium hydroxide, aluminum hydroxide, aluminum silicate, calcium carbonate, calcium silicate, magnesium silicate, silicon nitride, boron nitride, clay, molybdate compounds, talc, aluminum borate, and silicon carbide. [5] The prepreg according to any one of [1] to [4] above, wherein the thermosetting resin composition further contains (A) a maleimide compound. [6] The prepreg according to [5] above, wherein the nitrogen atoms of the N-substituted maleimide group are bonded to each other via a linking group containing an aromatic ring. [7] The prepreg according to any one of [1] to [6] above, wherein the thermosetting resin composition further contains (C) a thermosetting resin (excluding the maleimide compound). [8] A cured prepreg according to any of [1] to [7] above. [9] A laminate having a cured prepreg according to any of [1] to [7] above and a metal foil.

[10] A printed circuit board having the laminate according to [9] above.

[11] A semiconductor package having the printed circuit board described in

[10] above and a semiconductor element.

[0008] This disclosure provides a prepreg capable of suppressing molding defects in the insulating layer, and also provides a cured prepreg, a laminate, a printed circuit board, and a semiconductor package obtained using the prepreg.

[0009] This is a schematic cross-sectional view of the prepreg of this embodiment. This is a digital camera image of the insulating layer surface of the copper-clad laminate in Example 1. This is a digital camera image of the insulating layer surface of the copper-clad laminate in Example 2. This is a digital camera image of the insulating layer surface of the copper-clad laminate in Example 3. This is a digital camera image of the insulating layer surface of the copper-clad laminate in Example 4.

[0010] In the numerical ranges described in this disclosure, the upper or lower limits of the numerical range may be replaced with the values ​​shown in the examples. Furthermore, the lower and upper limits of a numerical range may be arbitrarily combined with the lower or upper limits of other numerical ranges. In the notation "AA to BB" for a numerical range, the numbers AA and BB at both ends are included in the range as the lower and upper limits, respectively. In this disclosure, for example, "10 or more" means 10 and numbers greater than 10, and this applies even if the numbers are different. Similarly, for example, "10 or less" means 10 and numbers less than 10, and this applies even if the numbers are different. Furthermore, unless otherwise specified, each component and material exemplified in this disclosure may be used alone or in combination of two or more. In this disclosure, if there are multiple substances corresponding to each component in the resin composition, unless otherwise specified, the content of each component in the resin composition means the total amount of such multiple substances present in the resin composition.

[0011] In this disclosure, "resin components" refers to all components of the resin composition that constitute the solid content, excluding inorganic compounds such as inorganic fillers described later. In this disclosure, "solid content" refers to components other than organic solvents described later, and components that are liquid at 25°C (excluding organic solvents) are also considered to be solid content. The expression "contains XX" as described in this disclosure means that XX may be contained in a reacted state if XX is reactable, or it may simply mean that XX is contained. Any combination of the matters described in this disclosure is also included in this disclosure and these embodiments.

[0012] [Prepreg] The prepreg of this embodiment is as follows: A prepreg containing a fibrous substrate and a thermosetting resin composition or a semi-cured product of the thermosetting resin composition, wherein the thermosetting resin composition contains (B) an inorganic filler with a volume average particle diameter of 2.0 μm or more, the thermosetting resin composition or the semi-cured product of the thermosetting resin composition protrudes from the surface of the fibrous substrate, and the thickness of the layer of the thermosetting resin composition or the semi-cured product of the thermosetting resin composition protruding from the surface of the fibrous substrate (hereinafter sometimes abbreviated as "thermosetting resin composition layer") is 10 μm or more.

[0013] In this embodiment, the prepreg has a thermosetting resin composition layer that extends beyond the surface of the fibrous substrate (at least one surface, preferably both surfaces) with a thickness of 10 μm or more (see Figure 1). This thickness design is generally not adopted because it tends to impair the low thermal expansion and high elasticity effects of the fibrous substrate. However, in this embodiment, by incorporating "(B) an inorganic filler with a volume average particle diameter of 2.0 μm or more" into the thermosetting resin composition in the aforementioned thickness design, it was possible to improve low thermal expansion and increase elasticity. Furthermore, because the thickness of the thermosetting resin composition layer that extends beyond the surface of the fibrous substrate is 10 μm or more, it is also possible to increase the density of component (B), thereby further improving low thermal expansion while suppressing molding defects such as streaking in the insulating layer of the laminate. From the above viewpoint, the thickness of the thermosetting resin composition layer protruding from the surface of the fiber substrate is preferably 15 μm or more, more preferably 20 μm or more, even more preferably 30 μm or more, particularly preferably 40 μm or more, and most preferably 50 μm or more, and is also preferably twice or more the volume average particle diameter of component (B). The thickness of the thermosetting resin composition layer protruding from the surface of the fiber substrate may be 10 to 80 μm, 10 to 70 μm, or 10 to 60 μm. Conventionally, in prepregs for interlayer insulating layers of printed circuit boards, the thickness of the thermosetting resin composition layer protruding from the surface of the fiber substrate has not been set to such a large size from the viewpoint of low thermal expansion and elastic modulus (rigidity), as well as from the viewpoint of suppressing thickness variations caused by the flow of resin components. However, in the prepreg of this embodiment, by setting the thickness of the thermosetting resin composition layer protruding from the surface of the fiber substrate to the above range, it becomes possible to increase the amount of component (B), which has a large particle size, in order to further increase the elastic modulus (rigidity), and even in that case, molding defects tend to occur less frequently in the insulating layer that is formed. Here, the thickness of the thermosetting resin composition layer protruding from the surface of the fiber substrate refers to the average value of a total of five locations: the four corners of the prepreg (however, 10 mm from the edge of the prepreg) and the center. A micrometer can be used to measure these thicknesses.

[0014] The fiber substrate is preferably a sheet-like fiber substrate. The material of the fiber substrate may include inorganic fibers such as E-glass, D-glass, S-glass, and Q-glass (quartz glass); organic fibers such as polyimide, polyester, and tetrafluoroethylene; and mixtures thereof. Among these, inorganic fibers are preferred as the material of the fiber substrate, and glass fibers are more preferred. The fiber substrate may have the shape of a woven fabric, non-woven fabric, rawhide, chopped strand mat, or surfacing mat, and among these, a woven fabric is preferred. In other words, the fiber substrate is preferably a glass woven fabric (glass cloth). The thickness of the fiber substrate (see Figure 1) is not particularly limited and may be 1 to 200 μm, 3 to 150 μm, 5 to 120 μm, or 5 to 100 μm. Here, the thickness of the fiber substrate in the prepreg is the average value of five points: the four corners of the fiber substrate in the prepreg (however, 10 mm from the edge of the glass cloth) and the center. The thickness of the fiber substrate can be measured after removing the thermosetting resin composition layer by etching or other means, or the thickness of the fiber substrate to be used can be measured in advance before prepreg manufacturing.

[0015] The components that the aforementioned thermosetting resin composition may contain will be described later.

[0016] The prepreg of this embodiment can be manufactured using a resin film formed from a thermosetting resin composition, as described below, and a fibrous substrate. For example, the resin film formed from the thermosetting resin composition, as described below, can be obtained by impregnating a fibrous substrate, for example, by a lamination method. The thermosetting resin composition in the prepreg obtained after lamination is B-staged. Here, in this disclosure, B-staged means being in the B-stage state as defined in JIS K6900 (1994). There are no particular restrictions on the lamination conditions; roll lamination may be performed under atmospheric pressure, or vacuum lamination may be performed, but vacuum lamination is preferred. The conditions for vacuum lamination are not particularly limited, but the heating temperature is preferably 50 to 170°C, more preferably 110 to 160°C, the pressurizing time is preferably 10 to 120 seconds, more preferably 20 to 80 seconds, and the bonding pressure is preferably 0.05 to 1.5 MPa, more preferably 0.1 to 1.2 MPa.

[0017] [Thermosetting resin composition] The thermosetting resin composition is a thermosetting resin composition containing (B) an inorganic filler with a volume average particle diameter of 2.0 μm or more, and more preferably contains (A) a maleimide compound or the like. The components contained in the thermosetting resin composition will be described in detail below, starting with component (A).

[0018] ((A) Maleimide compound) The thermosetting resin composition tends to have excellent solder heat resistance and moldability when it contains component (A). The maleimide compound preferably contains at least one selected from the group consisting of maleimide compounds and derivatives thereof having one or more (preferably two or more) N-substituted maleimide groups. Maleimide compounds having one or more N-substituted maleimide groups are not particularly limited, but preferably aromatic maleimide compounds having one N-substituted maleimide group bonded to an aromatic ring, such as N-phenylmaleimide, N-(2-methylphenyl)maleimide, N-(4-methylphenyl)maleimide, N-(2,6-dimethylphenyl)maleimide, N-(2,6-diethylphenyl)maleimide, N-(2-methoxyphenyl)maleimide, N-benzylmaleimide; 4,4'-diphenylmethanebismaleimide, bis(4-maleimidophenyl) ether, bis(4-maleimidophenyl) sulfone, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethanebismaleimide, 4-methyl-1,3-phenylenebismaleimide, Examples include aromatic bismaleimide compounds having two N-substituted maleimide groups preferably bonded to an aromatic ring, such as m-phenylenebismaleimide, 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane, and indan ring-containing aromatic bismaleimide; aromatic polymaleimide compounds having three or more N-substituted maleimide groups preferably bonded to an aromatic ring, such as polyphenylmethanemaleimide and biphenylaralkyl-type maleimide; and aliphatic maleimide compounds having N-substituted maleimide groups bonded to an aliphatic hydrocarbon group, such as N-dodecylmaleimide, N-isopropylmaleimide, and N-cyclohexylmaleimide, 1,6-bismaleimide-(2,2,4-trimethyl)hexane, and pyrophosphate binder-type long-chain alkylbismaleimide.Among these, from the viewpoint of compatibility with other resin components, copper foil peel strength, solder heat resistance, low thermal expansion, and mechanical properties, aromatic bismaleimide compounds having two N-substituted maleimide groups bonded to the aromatic ring, preferably aromatic polymaleimide compounds having three or more N-substituted maleimide groups bonded to the aromatic ring, more preferably 4,4'-diphenylmethanebismaleimide, 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane, and polyphenylmethanemaleimide, and even more preferably 4,4'-diphenylmethanebismaleimide. Furthermore, in the maleimide compounds, it is preferable that the nitrogen atom of the maleimide group is bonded to the aromatic ring in all cases of "preferably one N-substituted maleimide group bonded to the aromatic ring," "preferably two N-substituted maleimide groups bonded to the aromatic ring," and "preferably three or more N-substituted maleimide groups bonded to the aromatic ring." In the maleimide compound, it is preferable that the nitrogen atoms of the N-substituted maleimide group are bonded to each other via a linking group, and more preferably that the nitrogen atoms of the N-substituted maleimide group are bonded to each other via a linking group containing an aromatic ring.

[0019] Examples of maleimide compound derivatives include addition reaction products of a maleimide compound having one or more (preferably two or more) N-substituted maleimide groups and an amine compound. Examples of the amine compound include monoamine compounds and diamine compounds. The amine compound may be used alone or in combination of two or more. Examples of the monoamine compound include monoamine compounds having acidic substituents such as o-aminophenol, m-aminophenol, p-aminophenol, o-aminobenzoic acid, m-aminobenzoic acid, p-aminobenzoic acid, o-aminobenzenesulfonic acid, m-aminobenzenesulfonic acid, p-aminobenzenesulfonic acid, 3,5-dihydroxyaniline, and 3,5-dicarboxyaniline. The monoamine compound may be used alone or in combination of two or more. The diamine compounds include 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 4,4'-diaminodiphenylpropane, 2,2'-bis(4,4'-diaminodiphenyl)propane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylethane, 3,3'-diethyl-4,4'-diaminodiphenylethane, 4,4'-diaminodiphenyl ether, and 4,4'-diaminodiphenylthioe Examples include aromatic diamine compounds in which an amino group is bonded to an aromatic hydrocarbon group, such as 3,3'-dihydroxy-4,4'-diaminodiphenylmethane, 2,2',6,6'-tetramethyl-4,4'-diaminodiphenylmethane, 3,3'-dichloro-4,4'-diaminodiphenylmethane, 3,3'-dibromo-4,4'-diaminodiphenylmethane, 2,2',6,6'-tetrachloro-4,4'-diaminodiphenylmethane, and 2,2',6,6'-tetrabromo-4,4'-diaminodiphenylmethane; siloxanediamines; etc. Diamine compounds may be used individually or in combination of two or more. The siloxanediamine is a silicone compound having a primary amino group at its terminus.

[0020] A preferred embodiment of the maleimide compound derivative is a so-called siloxane-modified maleimide compound, which is an addition reaction product of a maleimide compound having one or more (preferably two or more) N-substituted maleimide groups with a siloxanediamine. Preferably, the siloxane-modified maleimide compound is an addition product of an aromatic bismaleimide compound having two N-substituted maleimide groups bonded to an aromatic ring and a siloxanediamine; more preferably, an addition product of 4,4'-diphenylmethanebismaleimide, 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane, or an indan ring-containing aromatic bismaleimide and a siloxanediamine; even more preferably, an addition product of 4,4'-diphenylmethanebismaleimide and a siloxanediamine, or an addition product of 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane and a siloxanediamine; and particularly preferably, an addition product of 4,4'-diphenylmethanebismaleimide and a siloxanediamine. The weight-average molecular weight (Mw) of the siloxane-modified maleimide compound is not particularly limited, but may be 400 to 10,000, 1,000 to 5,000, or 1,500 to 4,000.

[0021] (Content of component (A)) When the thermosetting resin composition contains component (A), the content of component (A) is not particularly limited, but from the viewpoint of solder heat resistance and moldability, it is preferably 10 to 90 parts by mass, more preferably 20 to 85 parts by mass, even more preferably 30 to 80 parts by mass, and particularly preferably 45 to 75 parts by mass, per 100 parts by mass of the resin component in the thermosetting resin composition. When the content of component (A) is above the lower limit, solder heat resistance and moldability tend to improve, and when it is below the upper limit, the decrease in low thermal expansion tends to be suppressed.

[0022] ((B) Inorganic filler with a volume average particle diameter of 2.0 μm or more) The thermosetting resin composition, by containing component (B), exhibits excellent low thermal expansion, heat resistance, and flame retardancy. Furthermore, because the volume average particle diameter of component (B) is 2.0 μm or more, even if the content of component (B) is high, it is possible to suppress the occurrence of molding defects in the insulating layer. The content of component (B) will be described later. From the viewpoint of suppressing the occurrence of molding defects in the insulating layer, the volume average particle diameter of component (B) is preferably 2.5 μm or more, more preferably 3.0 μm or more, and may also be 3.5 μm or more, 4.0 μm or more, 5.0 μm or more, 7.0 μm or more, 8.0 μm or more, or 9.0 μm or more. There is no particular upper limit to the volume-average particle diameter of component (B), but from the viewpoint of insulation reliability, it is preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less, and particularly preferably the volume-average particle diameter is 50% or less of the thickness of the varnish when applied. In other words, the volume-average particle diameter of component (B) may be 2.0 to 50 μm, and the preferred values ​​for the lower and upper limits of this numerical range are as described above. Here, the volume-average particle diameter is the particle diameter at the point corresponding to 50% of the volume when the cumulative frequency distribution curve by particle diameter is obtained with the total volume of the particles set to 100%. In this disclosure, the volume-average particle diameter is the value measured with a particle diameter distribution measuring device using the laser diffraction scattering method, and more specifically the value measured by the method described in the examples.

[0023] Component (B) is not particularly limited, but examples include silica, alumina, titanium oxide, mica, beryllium, barium titanate, potassium titanate, strontium titanate, calcium titanate, aluminum carbonate, magnesium hydroxide, aluminum hydroxide, aluminum silicate, calcium carbonate, calcium silicate, magnesium silicate, silicon nitride, boron nitride, clay (such as calcined clay), molybdate compounds (such as zinc molybdate), talc, aluminum borate, silicon carbide, etc. Component (B) may be used alone or in combination of two or more. Among these, silica, alumina, mica, and talc are preferred from the viewpoint of low thermal expansion, heat resistance, and flame retardancy, silica and alumina are more preferred, and silica is even more preferred. Examples of silica include crushed silica, fumed silica, and fused silica (fused spherical silica).

[0024] (Content of component (B)) The content of component (B) in the thermosetting resin composition is not particularly limited, but is preferably 1 to 80% by volume, more preferably 5 to 75% by volume, even more preferably 10 to 75% by volume, even more preferably 30 to 75% by volume, particularly preferably 50 to 75% by volume, and most preferably 60 to 75% by volume, relative to the total amount of solids in the thermosetting resin composition. When the content of component (B) is above the lower limit, it tends to be excellent in low thermal expansion, heat resistance and flame retardancy. When the content of component (B) is below the upper limit, it tends to be good in moldability and insulation reliability. As mentioned above, in this embodiment, even if the content of component (B) is high, it is possible to suppress the occurrence of molding defects in the insulating layer, so it is possible to set the content of component (B) to 55% by volume or more relative to the total amount of solids in the thermosetting resin composition. When the content of component (B) is increased, the content of component (B) may be 60% by volume or more relative to the total amount of solids in the thermosetting resin composition, preferably 60 to 80% by volume, more preferably 63 to 78% by volume, even more preferably 63 to 75% by volume, particularly preferably 63 to 73% by volume, and most preferably 65 to 70% by volume.

[0025] Furthermore, when using component (B), a coupling agent may be used in combination as needed to improve the dispersibility of component (B) and the adhesion between component (B) and the organic components in the thermosetting resin composition. The coupling agent is not particularly limited, and for example, a silane coupling agent or a titanate coupling agent may be appropriately selected and used. One type of coupling agent may be used alone, or two or more types may be used in combination. The amount of coupling agent used is also not particularly limited. When using a coupling agent, a so-called integral blending method may be used, in which the coupling agent is added after the component (B) has been blended into the thermosetting resin composition. However, it is preferable to use an inorganic filler in which the coupling agent has been pre-treated on the inorganic filler surface by dry or wet methods. By adopting this method, the characteristics of component (B) can be expressed more effectively.

[0026] In this embodiment, when component (B) is used, in order to improve the dispersibility of component (B) in the thermosetting resin composition, component (B) may be used as a slurry in which it has been pre-dispersed in an organic solvent, if necessary. Examples of organic solvents include those described later.

[0027] ((C) Thermosetting resin) The thermosetting resin composition may or may not contain (C) a thermosetting resin (excluding maleimide compounds). Examples of component (C) include one or more thermosetting resins selected from the group consisting of epoxy resins, phenolic resins, cyanate resins, isocyanate resins, benzoxazine resins, oxetane resins, amino resins (such as melamine resins), bismaleimidotriazine resins, unsaturated polyester resins, allyl resins, dicyclopentadiene resins, and silicone resins. Component (C) is preferably one or more selected from the group consisting of epoxy resins, phenolic resins, cyanate resins, isocyanate resins, amino resins, unsaturated polyester resins, and silicone resins; more preferably one or more selected from the group consisting of epoxy resins, phenolic resins, cyanate resins, and isocyanate resins; even more preferably one or more selected from the group consisting of epoxy resins, phenolic resins, and cyanate resins; and particularly preferably an epoxy resin.

[0028] The epoxy resin is preferably an epoxy resin having two or more epoxy groups in one molecule. Here, epoxy resins are classified into glycidyl ether type epoxy resins, glycidyl amine type epoxy resins, glycidyl ester type epoxy resins, etc. Among these, glycidyl ether type epoxy resins are preferred. The epoxy resins mentioned above can be further classified into various types of epoxy resins depending on the difference in their main skeleton. Within each of these types of epoxy resins, they can be further classified into bisphenol-type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, and bisphenol S type epoxy resin; alicyclic epoxy resins such as dicyclopentadiene type epoxy resin; aliphatic chain epoxy resins; novolac-type epoxy resins such as phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, bisphenol F novolac type epoxy resin, phenol aralkyl novolac type epoxy resin, and biphenyl aralkyl novolac type epoxy resin; stilbene type epoxy resin; naphthalene skeleton-containing epoxy resins such as naphthalene type epoxy resin, naphthol novolac type epoxy resin, and naphthol aralkyl type epoxy resin; biphenyl type epoxy resin; xylylene type epoxy resin; and dihydroanthracene type epoxy resin.

[0029] The aforementioned component (C) is not particularly limited, but may contain an epoxy resin having a viscosity of 30 Pa·s or less at 150°C, or component (C) may be an epoxy resin having a viscosity of 30 Pa·s or less at 150°C. In this disclosure, viscosity is a value based on a viscosity measurement method using an isothermal titration calorimeter (ICT). The epoxy resin having a viscosity of 30 Pa·s or less at 150°C is preferably 25 Pa·s or less, more preferably 10 Pa·s or less, and even more preferably 5 Pa·s or less. The lower limit of viscosity at 150°C is not particularly limited, but may be 5 mPa·s or more, 20 mPa·s or more, 50 mPa·s or more, or 100 mPa·s or more. In other words, the epoxy resin may have a viscosity of 5 mPa·s to 30 Pa·s at 150°C. By including an epoxy resin in component (C) whose viscosity at 150°C is within the aforementioned range, the viscosity of the thermosetting resin composition can be reduced even if component (A) has high viscosity, and the moldability tends to be good, thus making it easier to suppress molding defects in the insulating layer.

[0030] As epoxy resins with a viscosity of 30 Pa·s or less at 150°C, non-novolac epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, naphthalene type epoxy resin, cyclohexane type epoxy resin, cyclohexanedimethanol type epoxy resin, and epoxy resins having a butadiene structure are preferred, bisphenol A type epoxy resin and naphthalene type epoxy resin are more preferred, and bisphenol A type epoxy resin is even more preferred. Epoxy resins with a viscosity of 30 Pa·s or less at 150°C may be used individually or in combination of two or more types. Commercially available epoxy resins include: "HP4032," "HP4032D," and "HP4032SS" (all naphthalene-type epoxy resins) from DIC Corporation; "jER828US," "jER828EL," "jER828EL," "jER825," and "jER828EL" (all bisphenol A-type epoxy resins) from Mitsubishi Chemical Corporation; and "jER807" and "jER1750" (both bisphenol A-type epoxy resins) from Mitsubishi Chemical Corporation. Examples include: EP-4088S and EP-4040 (dicyclopentadiene type epoxy resin) manufactured by ADEKA Corporation; ZX1059 (a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; PB-3600 manufactured by Daicel Corporation; and JP-100 and JP-200 manufactured by Nippon Soda Co., Ltd. (all epoxy resins having a butadiene structure).

[0031] The weight-average molecular weight of the epoxy resin may be 200 to 3,000, 250 to 2,000, 300 to 1,800, or 400 to 1,500. If the weight-average molecular weight of the epoxy resin is above the lower limit, it tends to have excellent solder heat resistance, and if it is below the upper limit, it tends to exhibit low elasticity and flexibility. From the viewpoint of compatibility, the epoxy equivalent of the epoxy resin may be 150 to 500 g / eq, 200 to 450 g / eq, or 250 to 350 g / eq. The epoxy equivalent can be measured according to the method specified in JIS K7236 (2009).

[0032] (Content of (C) Thermosetting Resin) When the thermosetting resin composition contains component (C), the content of component (C) is not particularly limited, but is preferably 10 to 90 parts by mass, more preferably 15 to 80 parts by mass, even more preferably 20 to 70 parts by mass, and particularly preferably 25 to 55 parts by mass, per 100 parts by mass of the resin component in the thermosetting resin composition. When the content of component (C) is above the lower limit, the solder heat resistance and moldability tend to be good. When the content of component (C) is below the upper limit, the low thermal expansion tend to be good.

[0033] ((D) Curing Accelerator) The thermosetting resin composition may contain a (D) curing accelerator from the viewpoint of promoting the curing reaction. Examples of component (D) include amine-based curing accelerators, imidazole-based curing accelerators, phosphorus-based curing accelerators, organometallic salts, acidic catalysts, organic peroxides, etc. In this disclosure, imidazole-based curing accelerators are not classified as amine-based curing accelerators. Component (D) may be used alone or in combination of two or more. The thermosetting resin composition preferably contains an imidazole-based curing accelerator and a phosphorus-based curing accelerator as component (D), and may contain an imidazole-based curing accelerator or a phosphorus-based curing accelerator.

[0034] Examples of the amine-based curing accelerator include amine compounds having primary to tertiary amino groups, such as triethylamine, 4-aminopyridine, tributylamine, and dicyandiamide; and quaternary ammonium compounds. Examples of the imidazole-based curing accelerator include imidazole compounds such as methylimidazole, phenylimidazole, 2-undecylimidazole, and isocyanate-masquimidazole (for example, the addition product of hexamethylene diisocyanate resin and 2-ethyl-4-methylimidazole). Examples of the phosphorus-based curing accelerator include tertiary phosphines such as triphenylphosphine; and quaternary phosphonium compounds such as the addition product of p-benzoquinone with tri-n-butylphosphine. Examples of the organometallic salts include carboxylates of manganese, cobalt, zinc, etc. Examples of the acidic catalyst include p-toluenesulfonic acid. Examples of the aforementioned organic peroxides include dicumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexine-3,2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, t-butylperoxyisopropyl monocarbonate, and α,α'-di(t-butylperoxy)diisopropylbenzene.

[0035] (Content of curing accelerator (D)) When the thermosetting resin composition contains component (D), the content of component (D) is not particularly limited, but is preferably 0.01 to 3.0 parts by mass, more preferably 0.05 to 2.5 parts by mass, even more preferably 0.1 to 2.0 parts by mass, and particularly preferably 0.3 to 1.5 parts by mass, per 100 parts by mass of the resin component in the thermosetting resin composition. When the content of component (D) is within the above range, better heat resistance, storage stability, and moldability tend to be obtained.

[0036] (Other Components) The thermosetting resin composition may or may not contain, as other components, one or more selected from the group consisting of flame retardants, flame retardant aids, antioxidants, adhesion improvers, heat stabilizers, antistatic agents, ultraviolet absorbers, pigments, colorants, and lubricants. It may also contain or may not contain any other components. When the thermosetting resin composition contains these other components (flame retardants, flame retardant aids, antioxidants, adhesion improvers, heat stabilizers, antistatic agents, ultraviolet absorbers, pigments, colorants, lubricants, and other components), the amount of each is not particularly limited, but may be, for example, 0.01 parts by mass or more, 10 parts by mass or less, 5 parts by mass or less, 1 part by mass or less, or not contained at all, per 100 parts by mass of the resin component in the thermosetting resin composition.

[0037] The thermosetting resin composition is not particularly limited, but the total amount of components (A) to (B) [however, if the thermosetting resin composition contains at least one of components (C) and (D), the total amount including those components] is preferably more than 50% by mass (including 100% by mass), more preferably 70% by mass or more (including 100% by mass), even more preferably 80% by mass or more (including 100% by mass), particularly preferably 90% by mass or more (including 100% by mass), and may be 100% by mass.

[0038] (Organic solvent) The thermosetting resin composition may be a so-called "varnish" containing an organic solvent, from the viewpoint of facilitating handling and facilitating the production of prepregs or resin films described later. The organic solvent is not particularly limited, but examples include alcohol-based solvents such as ethanol, propanol, butanol, methyl cellosolve, butyl cellosolve, and propylene glycol monomethyl ether; ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ether-based solvents such as tetrahydrofuran; aromatic solvents such as toluene, xylene, and mesitylene; nitrogen atom-containing solvents such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone; sulfur atom-containing solvents such as dimethyl sulfoxide; and ester-based solvents such as γ-butyrolactone. From the viewpoint of solubility, ketone-based solvents and alcohol-based solvents are preferred, methyl ethyl ketone and propylene glycol monomethyl ether are more preferred, and propylene glycol monomethyl ether is even more preferred. One organic solvent may be used alone, or two or more may be used in combination.

[0039] When the thermosetting resin composition is used as a varnish, the solid content concentration is preferably 30 to 90% by mass, more preferably 40 to 80% by mass, and even more preferably 55 to 75% by mass. When the solid content concentration of the thermosetting resin composition is within the above range, the thermosetting resin composition becomes easier to handle, the impregnation into the substrate and the appearance of the manufactured prepreg become good, and the coating properties when it is made into a resin film also become good.

[0040] The thermosetting resin composition can be produced by mixing the components in a known manner. In this case, each component may be dissolved or dispersed in the organic solvent while stirring. The mixing order, temperature, time, and other conditions are not particularly limited and can be set arbitrarily.

[0041] [Cured Prepreg] Another aspect of this embodiment is a cured prepreg of this embodiment. For example, in a laminate described later, the prepreg of this embodiment exists as a cured product. The cured prepreg of this embodiment can be obtained by removing the metal foil of the laminate by etching or the like. The surface roughness of the cured prepreg of this embodiment may be increased by treating its surface with an etching solution or the like. The surface roughness (Rz) of the cured prepreg of this embodiment is not particularly limited, but for example, it is preferably 10 μm or less, more preferably 5 μm or less, may be 3 μm or less, may be 2 μm or less, and is not particularly limited, but may be 0.1 μm or more, may be 0.3 μm or more, may be 0.5 μm or more, or may be 0.8 μm or more. Here, the surface roughness (Rz) is the maximum height roughness (Rz) that can be obtained from the roughness curve according to ISO 4287 (1997).

[0042] [Resin Film] The aforementioned resin film that can be used in the production of the prepreg of this embodiment is a resin film containing the thermosetting resin composition or a semi-cured product of the thermosetting resin composition. The resin film can be produced, for example, by applying a thermosetting resin composition containing an organic solvent, i.e., a varnish, to a support, heating and drying it, and semi-curing it (B-stage) as needed. The thickness of the resin film is preferably 10 to 80 μm, more preferably 15 to 70 μm, even more preferably 20 to 60 μm, and particularly preferably 40 to 60 μm, from the viewpoint of enabling high filling of component (B). Examples of the support include plastic film, metal foil, and release paper. The drying temperature and drying time can be appropriately determined according to the amount of organic solvent used and the boiling point of the organic solvent used, but the resin film can be suitably formed by drying at 50 to 200°C for about 1 to 10 minutes.

[0043] [Laminated Plate] The laminated plate of the present embodiment is a laminated plate having a cured product of the prepreg of the present embodiment and a metal foil. The laminated plate of the present embodiment can be produced, for example, by disposing a metal foil on one or both sides of one sheet of the prepreg of the present embodiment, or by disposing a metal foil on one or both sides of a laminate obtained by stacking two or more (preferably 2 to 30, more preferably 2 to 20, still more preferably 2 to 10) sheets of the prepreg of the present embodiment, and then performing heat and pressure molding. In the laminated plate obtained by this manufacturing method, the thermosetting resin composition in the prepreg of the present embodiment is C-staged. In the present disclosure, C-staging means bringing it into the state of the C-stage defined in JIS K6900 (1994). Note that a laminated plate having a metal foil may be referred to as a metal-clad laminated plate. The metal of the metal foil is not particularly limited, but from the viewpoint of conductivity, it may be copper, gold, silver, nickel, platinum, molybdenum, ruthenium, aluminum, tungsten, iron, titanium, chromium, or an alloy containing one or more of these metal elements. Copper and aluminum are preferable, and copper is more preferable. The method of performing heat and pressure molding is not particularly limited. For example, it can be performed under the conditions of a temperature of 100 to 300°C, a pressure of 0.2 to 10 MPa, and a time of 0.1 to 5 hours. Also, for heat and pressure molding, a method of maintaining a vacuum state for 0.5 to 5 hours using a vacuum press or the like can be adopted.

[0044] (Elastic Modulus) The elastic modulus (storage elastic modulus) at 30°C of the cured product of the prepreg in the laminated plate of the present embodiment is preferably 15 GPa or more, may be 15 to 30 GPa, may be 17 to 27 GPa, or may be 18 to 25 GPa from the viewpoint of the warpage reduction effect. Here, the storage elastic modulus at 30°C is a value measured using a dynamic viscoelasticity measuring device, and more specifically, it is a value measured by the method described in the examples.

[0045] (Coefficient of linear thermal expansion) The coefficient of linear thermal expansion of the cured product of the prepreg in the laminate of the present embodiment is preferably 15 ppm / °C or less, may be 5 to 15 ppm / °C, or may be 7 to 13 ppm / °C from the viewpoint of the warpage reduction effect. Here, the coefficient of linear thermal expansion is a value obtained by performing thermomechanical analysis by the compression method using a thermomechanical measurement device (TMA), and more specifically, is a value measured by the method described in the examples.

[0046] [Printed wiring board] The printed wiring board of the present embodiment has one or more selected from the group consisting of the cured product of the prepreg of the present embodiment and the cured product of the laminate of the present embodiment. The printed wiring board of the present embodiment can be manufactured by performing circuit formation processing such as drilling, metal plating, etching of metal foil, etc. by a known method using one or more selected from the group consisting of the prepreg of the present embodiment and the laminate of the present embodiment. Further, a multilayer printed wiring board can also be manufactured by performing multilayer bonding processing as necessary. In the printed wiring board of the present embodiment, the prepreg of the present embodiment is in the C-stage. In this way, the prepreg of the present embodiment serves as an interlayer insulating layer of the printed wiring board.

[0047] [Semiconductor package] The semiconductor package of the present embodiment is a semiconductor package having the printed wiring board of the present embodiment and a semiconductor element. The semiconductor package of the present embodiment can be manufactured by mounting a semiconductor element such as a semiconductor chip or a memory at a predetermined position on the printed wiring board of the present embodiment and sealing the semiconductor element with a sealing resin or the like.

[0048] Although the preferred embodiments have been described above, these are examples for the explanation of the present disclosure, and the scope of the present disclosure is not intended to be limited only to these embodiments. The present disclosure includes various aspects different from the above embodiments within the scope not departing from the gist thereof.

[0049] Hereinafter, the present embodiment will be specifically described with reference to examples. However, the present embodiment is not limited to the following examples.

[0050] Production Example 1 (Production of a Maleimide Compound Derivative (Maleimide Compound 1)) In a 2 L volume reaction vessel that can be heated and cooled, equipped with a thermometer, a stirrer, and a moisture meter with reflux condenser, 358.0 g of 4,4'-diphenylmethanebismaleimide, 54.5 g of p-aminophenol, and 412.50 g of propylene glycol monomethyl ether were mixed (maleimide group equivalent) / (-NH ２ After mixing in a ratio such that the equivalent amount (based on the number of groups) = 4.0, the mixture was reacted under reflux for 5 hours to obtain a solution of a derivative of the maleimide compound (maleimide compound 1).

[0051] [Examples 1-4, Comparative Example 1] (1. Preparation of Varnish) A thermosetting resin composition (varnish) with a solid content of 70% by mass was prepared by mixing and stirring each component listed in Table 1 with propylene glycol monomethyl ether at room temperature according to the blending amounts listed in Table 1. (2. Preparation of Resin Film) The varnish thus obtained was applied to a PET film (manufactured by Toray Industries, Inc., thickness: 50 μm, product name: S10) using a comma coater so that the thickness after drying was 55 μm. Then, a resin film with a PET film was prepared by heating and drying at 140°C for 2 minutes.

[0052] (3. Preparation of Prepreg) The PET film-attached resin film obtained in "2. Preparation of Resin Film" above was placed on both sides of a glass cloth "IPC#1010" (manufactured by Nitto Boseki Co., Ltd., thickness: 11 μm, S glass, size 250 mm x 250 mm) so that the resin layer surface of the PET film-attached resin film was in contact with the glass cloth. This laminate of "PET film / resin film / glass cloth / resin film / PET film" was heated and pressurized under vacuum using a vacuum laminating apparatus. In this way, a PET film-attached prepreg was obtained in which the thermosetting resin composition of the resin film was impregnated into the glass cloth. The vacuum lamination conditions were a heating plate temperature of 130°C, a pressing pressure of 1.0 MPa, a vacuum degree of 100 kPa or less, a vacuum time of 30 seconds, and a heating time of 30 seconds. The PET film was peeled off from the obtained PET film-attached prepreg to obtain a prepreg (thickness 110 μm) in which the thickness of the thermosetting resin composition layers on both sides that protruded onto the glass cloth was the same. However, while prepregs could be produced by the above procedure in Examples 1 to 4, in Comparative Example 1, it was not possible to laminate it onto the fiber substrate, and therefore a prepreg could not be produced. The reason why a prepreg could not be produced in Comparative Example 1 (specifically, the resin film peeled off after lamination) is presumed to be that, with an inorganic filler having an average particle size of 0.5 μm, the resin component is used to fill the gaps between the inorganic fillers, resulting in insufficient resin component to fill the gaps in the glass cloth. The thickness of the prepreg was taken as the average value of the values ​​obtained by measuring at a total of five locations: the four corners of the prepreg (however, 10 mm from the edge of the prepreg) and the center, using a horizontally adjusted base and a digital indicator (manufactured by Mitutoyo Corporation). Furthermore, the thickness of the thermosetting resin composition layer protruding onto the glass cloth was determined by subtracting the thickness of the glass cloth from the thickness of the prepreg and multiplying the result by 1 / 2, which was found to be 50 μm.

[0053] (4. Fabrication of Copper-Clad Laminate) Six prepregs obtained in "3. Fabrication of Prepregs" were stacked, and 12 μm thick copper foil "GTS-12" (manufactured by Furukawa Electric Co., Ltd.) was placed above and below them. Next, a copper-clad laminate was fabricated by press molding under the following conditions. - Press molding conditions - Heating conditions: The temperature was raised from 25°C to 230°C at a heating rate of 3°C / min, held at 230°C for 90 minutes, and then cooled for 30 minutes. Pressure conditions (pressure applied to the six prepregs sandwiched between copper foils): 3 MPa (from the start of heating to the end of cooling)

[0054] (a. Appearance evaluation of the insulating layer) The outer copper foil of the copper-clad laminate obtained by the above method was removed by immersion in a copper etching solution (10% by mass solution of ammonium persulfate, manufactured by Mitsubishi Gas Chemical Company, Inc.), and the surface of the exposed insulating layer was visually observed. If there were no molding defects, it was evaluated as "good". Figures 2 to 5 show images of the insulating layer surface taken with a digital camera in Examples 1 to 4, respectively.

[0055] (b. Measurement of Elastic Modulus) The outer copper foil of the copper-clad laminate obtained by the above method was removed by immersion in a copper etching solution (10% by mass solution of ammonium persulfate, manufactured by Mitsubishi Gas Chemical Company, Inc.), then cut to a size of 1.5 mm × 30 mm, and dried at 105°C for 1 hour to be used as the evaluation substrate. The storage modulus at 30°C of the evaluation substrate was measured using a dynamic viscoelasticity measuring device (manufactured by UBM Co., Ltd.). A higher storage modulus at 30°C is preferable as it indicates a better warp reduction effect.

[0056] (c. Measurement of Linear Thermal Expansion Coefficient) The outer copper foil of the copper-clad laminate obtained by the above method was removed by immersion in a copper etching solution (10% by mass solution of ammonium persulfate, manufactured by Mitsubishi Gas Chemical Company, Inc.), then cut to a size of 5 mm x 5 mm, and dried at 105°C for 1 hour to serve as the evaluation substrate. Thermomechanical analysis was performed using the compression method with a thermomechanical measuring device (TMA) [TA Instrument Japan Co., Ltd., Q400 (model number)]. After mounting the evaluation substrate in the X direction, measurements were taken twice under measurement conditions of a load of 5 g and a heating rate of 10°C / min. The average thermal expansion coefficient (average of linear thermal expansion coefficients in the planar direction) from 30°C to 100°C in the second measurement was calculated and this was taken as the value of the linear thermal expansion coefficient.

[0057]

[0058] The details of each component listed in Table 1 are as follows: [(A) Component] Maleimide compound 1: A derivative of the maleimide compound obtained in Production Example 1 [(B) Inorganic filler] Inorganic filler 1: Spherical fused silica, volume average particle diameter = 22 μm Inorganic filler 2: Spherical fused silica, volume average particle diameter = 16 μm (for comparison) Inorganic filler 3: Spherical fused silica, volume average particle diameter = 0.5 μm The volume average particle diameter of the inorganic filler was measured using a laser diffraction scattering particle size distribution analyzer "LA-920" (manufactured by Horiba, Ltd.).

[0059] [(C) Thermosetting resins] • Epoxy resin 1: "EP-4040", manufactured by ADEKA Corporation, viscosity at 25°C: 300 mPa·s, epoxy equivalent: 308 g / eq • Epoxy resin 2: "NC-7000-L", manufactured by Nippon Kayaku Co., Ltd., solid at 25°C, epoxy equivalent: 308 g / eq

[0060] [(D) Curing accelerator] ・Curing accelerator 1: Isocyanate mask imidazole "G8009L" (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)

[0061] The results in Table 1 show that in the case of the prepregs of Examples 1 to 4, there were no molding defects in the insulating layer of the copper-clad laminate, indicating high insulation reliability. Furthermore, it can be seen that they have high elastic modulus (rigidity) and low thermal expansion. On the other hand, in the case of Comparative Example 1, a resin film with a high density of small-particle inorganic fillers was used, making it impossible to laminate it to a fiber substrate (specifically, the resin film peeled off from the glass cloth after lamination), and thus the prepreg itself could not be manufactured.

Claims

1. A prepreg comprising a fibrous substrate and a thermosetting resin composition or a semi-cured product of the thermosetting resin composition, wherein the thermosetting resin composition contains (B) an inorganic filler with a volume average particle diameter of 2.0 μm or more, the thermosetting resin composition or the semi-cured product of the thermosetting resin composition protrudes from the surface of the fibrous substrate, and the thickness of the layer of the thermosetting resin composition or the semi-cured product of the thermosetting resin composition protruding from the surface of the fibrous substrate is 10 μm or more.

2. The prepreg according to claim 1, wherein the volume-average particle size of component (B) is 50% or less of the thickness of the layer of the thermosetting resin composition or the semi-cured product of the thermosetting resin composition that protrudes from the surface of the fibrous substrate.

3. The prepreg according to claim 1, wherein the content of component (B) in the thermosetting resin composition is 55% by volume or more with respect to the total amount of solids.

4. The prepreg according to claim 1, wherein component (B) is one or more selected from the group consisting of silica, alumina, titanium oxide, mica, beryllium, barium titanate, potassium titanate, strontium titanate, calcium titanate, aluminum carbonate, magnesium hydroxide, aluminum hydroxide, aluminum silicate, calcium carbonate, calcium silicate, magnesium silicate, silicon nitride, boron nitride, clay, molybdate compounds, talc, aluminum borate, and silicon carbide.

5. The prepreg according to claim 1, wherein the thermosetting resin composition further contains (A) a maleimide compound.

6. The prepreg according to claim 5, wherein the nitrogen atoms of the N-substituted maleimide group are bonded to each other via a linking group containing an aromatic ring.

7. The prepreg according to claim 1, wherein the thermosetting resin composition further contains (C) a thermosetting resin (excluding maleimide compounds).

8. A cured product of the prepreg according to claim 1.

9. A laminate having a cured prepreg according to claim 1 and a metal foil.

10. A printed circuit board having the laminate described in claim 9.

11. A semiconductor package having a printed circuit board according to claim 10 and a semiconductor element.

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