Production methods for laminate, laminated board, printed wiring board, and semiconductor package

Abstract

Provided is a production method for a laminate and a laminated board that do not readily suffer damage to an internal glass film. Also provided are a production method for a printed wiring board and a production method for a semiconductor package that use the production method for a laminate. Specifically, the production method for a laminate involves (1). (1) Producing a laminate by providing a prepreg that has a surface waviness (Wa) of no more than 5.0 μm on one or both sides of a glass film.

Description

Methods for manufacturing laminates, laminated boards, printed wiring boards, and semiconductor packages

[0001] The present disclosure relates to methods for manufacturing laminates, laminates, printed wiring boards, and semiconductor packages.

[0002] With the recent trend toward higher density semiconductor packages and faster communication speeds, further improvements in the warpage reduction of semiconductor packages are strongly desired. One known method for achieving low warpage in semiconductor packages is to incorporate an inorganic filler into the resin layer of a laminate for printed wiring boards to reduce thermal expansion. However, this method also has limitations because there is a limit to the amount of inorganic filler that can be incorporated. Under these circumstances, a laminate has been proposed that has resin layers and copper foils on the top and bottom of a glass film, i.e., a "copper foil / resin layer / glass film / resin layer / copper foil" configuration, with the aim of achieving higher dimensional stability by adjusting the thermal expansion coefficient of the printed wiring board (see Patent Document 1).

[0003] Patent No. 4657554

[0004] However, through investigations by the present inventors, it has been found that laminates having a structure of "copper foil / resin layer / glass film / resin layer / copper foil" tend to have a low yield because the internal glass film is easily damaged during transportation, handling, cutting, etc.

[0005] Therefore, the object of the present disclosure is to provide a method for manufacturing a laminate and a laminate plate in which the internal glass film is less likely to be damaged, and to provide a method for manufacturing a printed wiring board and a method for manufacturing a semiconductor package using the manufacturing method of the laminate or laminate plate.

[0006] As a result of extensive research, the present inventors have found that the above-mentioned object can be achieved by the present disclosure. The present disclosure includes the following embodiments [1] to [8]. [1] A method for manufacturing a laminate, including the following (1). (1) Manufacturing a laminate by arranging a prepreg having a surface waviness (Wa) of 5.0 μm or less on one or both sides of a glass film. [2] A method for manufacturing a laminate according to the above [1], wherein the prepreg used in the above (1) is manufactured by impregnating a fiber substrate with a thermosetting resin film. [3] A method for manufacturing a laminate according to the above [1] or [2], wherein the thickness of the glass film in the above (1) is 50 to 1,000 μm. [4] A method for manufacturing a laminate according to any one of the above [1] to [3], wherein the thickness of the prepreg in the above (1) is 10 to 300 μm. [5] A method for manufacturing a laminate, comprising the following (1) to (2) in this order. (1) Producing a laminate by placing a prepreg having a surface waviness (Wa) of 5.0 μm or less on one or both sides of a glass film. (2) Producing a laminate by placing a metal foil on one or both sides of the laminate and then hot-pressing and molding the laminate. [6] The method for producing a laminate according to [5] above, further comprising the following (1') between (1) and (2). (1') Producing a laminate by placing a glass film on one or both sides of the laminate obtained in (1) above, and then placing the prepreg on the glass film, or by repeating (1') twice or more times. [7] A method for producing a printed wiring board, comprising forming a wiring pattern on a laminate obtained by the method according to [5] or [6] above. [8] A method for producing a semiconductor package, comprising mounting a semiconductor element on a printed wiring board obtained by the method according to [7] above, and then encapsulating the semiconductor element with an encapsulating resin.

[0007] According to the present disclosure, it is possible to provide a method for manufacturing a laminate and a laminate plate in which the internal glass film is less likely to be damaged, and to provide a method for manufacturing a printed wiring board and a method for manufacturing a semiconductor package using the method for manufacturing the laminate or laminate plate.

[0008] FIG. 1 is a cross-sectional view schematically illustrating one aspect of a prepreg used in this embodiment. FIG. 2 is a cross-sectional view schematically illustrating one aspect of a prepreg used in this embodiment. FIG. 3 is a cross-sectional view of a fiber substrate contained in a prepreg used in this embodiment, for explaining the thickness of the fiber substrate. FIG. 4 is a top view of a copper-clad laminate, illustrating the state observed when a glass film inside the copper-clad laminate is cracked, in an example or comparative example. FIG. 5 is a schematic view illustrating a method for evaluating the handleability of a copper-clad laminate in an example and a comparative example. FIG. 6 is a cross-sectional view schematically illustrating the structure of a copper-clad laminate produced in Example 1 or 2. FIG. 7 is a cross-sectional view schematically illustrating the structure of a copper-clad laminate produced in Comparative Example 1 or 2. FIG. 8 is a cross-sectional view schematically illustrating the structure of a copper-clad laminate produced in Comparative Example 3.

[0009] An embodiment of the present disclosure will be described in detail below, but the present disclosure is not limited to the embodiment described below. In the numerical ranges described in this disclosure, the lower limit or upper limit of the numerical range may be replaced with a value shown in the examples. Furthermore, the lower limit and upper limit of a numerical range can be arbitrarily combined with the lower limit or upper limit of another numerical range. In the expression "AA to BB," the numerical values ​​AA and BB at both ends are included as the lower limit and upper limit, respectively, within the numerical range. In this disclosure, for example, the expression "10 or more" means 10 and a numerical value greater than 10, and this also applies when the numerical values ​​differ. Furthermore, for example, the expression "10 or less" means a numerical value less than 10 and this also applies when the numerical values ​​differ. Furthermore, unless otherwise specified, each component and material exemplified in this disclosure may be used alone or in combination of two or more types. In the present disclosure, when a plurality of substances corresponding to each component are present in the thermosetting resin composition, the content of each component in the thermosetting resin composition means the total amount of the plurality of substances present in the thermosetting resin composition, unless otherwise specified.

[0010] In this disclosure, the term "resin component" is defined as all components of the solid content constituting the thermosetting resin composition, excluding inorganic compounds such as inorganic fillers, as well as flame retardants and flame retardant aids, as described below. In this disclosure, "solid content" refers to components other than the solvent, and components that are liquid at 25°C are also considered solid content. The expression "containing XX" described in this disclosure may mean that XX is contained in a reacted state if XX is reactive, or may simply mean that XX is contained as is, or may include both of these aspects. Any combination of the items described in this disclosure is also included in this disclosure and the present embodiment.

[0011] [Method for manufacturing a laminate and a laminate plate] One aspect of this embodiment is a method for manufacturing a laminate, including the following (1): (1) Manufacturing a laminate by arranging a prepreg having a surface waviness (Wa) of 5.0 μm or less on one or both sides of a glass film. Another aspect of this embodiment is a method for manufacturing a laminate, including the following (1) and (2) in this order: (1) Manufacturing a laminate by arranging a prepreg having a surface waviness (Wa) of 5.0 μm or less on one or both sides of a glass film. (2) Manufacturing a laminate by arranging a metal foil on one or both sides of the laminate and then hot-pressing and molding the laminate. Hereinafter, (1) and (2) will be described in this order.

[0012] (1) Production of Laminates <Prepreg> The prepreg used in (1) has a surface waviness (Wa) of 5.0 μm or less. Such prepregs are not particularly limited, but prepregs having regions impregnated with a thermosetting resin composition and regions not impregnated with a fiber substrate (see FIGS. 1 and 2) can be used. It is believed that the small surface waviness of the prepreg used in (1) makes it possible to produce laminates and laminates in which the internal glass film is less likely to break. By intentionally providing regions in the fiber substrate that are not impregnated with the thermosetting resin composition, the layer of thermosetting resin composition near the surface (hereinafter referred to as the resin layer) does not follow the waviness of the glass cloth. As a result, it is believed that the waviness of the fiber substrate is less likely to be reflected on the surface of the prepreg, making it easier to reduce the surface waviness of the prepreg. The prepreg can be produced by impregnating a fiber substrate with a thermosetting resin film. On the other hand, in the method of immersing a fiber substrate in a resin varnish and then drying it, the thermosetting resin composition tends to follow the waviness of the glass cloth, and the surface waviness of the prepreg becomes large, making it difficult to produce a prepreg with a surface waviness (Wa) of 5.0 μm or less used in this embodiment.

[0013] As described above, the surface waviness (Wa) of the prepreg is 5.0 μm or less, preferably 3.0 μm or less, more preferably 2.5 μm or less, even more preferably 2.0 μm or less, and may be 1.5 μm or less. The lower limit of the surface waviness (Wa) of the prepreg is not particularly limited, but may be 0.01 μm or more, 0.1 μm or more, or 0.2 μm or more. In other words, the surface waviness (Wa) of the prepreg of this embodiment may be 0.01 to 5.0 μm.

[0014] Here, the surface waviness (Wa) in this disclosure refers to the arithmetic mean height (Wa) that can be obtained from a waviness curve in accordance with ISO 4287 (1997). JIS B 0601 (2001) may be used instead of ISO 4287 (1997). The surface waviness (Wa) in this disclosure can be measured by the following method. Using a shape analysis laser microscope "VK-X100" (manufactured by Keyence Corporation), shape measurement is performed automatically using an observation application to obtain a waviness curve in accordance with ISO 4287 (1997) or JIS B 0601 (2001). The obtained waviness curve is subjected to surface roughness analysis using an analysis application to calculate the surface waviness (Wa). Here, the waviness curve is a curve obtained by applying a phase compensation high-pass filter λc (λc=80 μm) to the profile curve to remove wavelengths less than 80 μm from the profile curve. The analysis range is 1,000 μm x 1,000 μm.

[0015] Unless otherwise specified, the surface waviness (Wa) of the prepreg in this disclosure refers to the surface waviness on both sides of the prepreg, and the "surface" refers to the surface that will be overlapped when multiple prepregs are stacked to produce a laminate or a metal-clad laminate, or the surface opposite thereto, and does not include the side. Furthermore, in this disclosure, the "face direction" of the prepreg means the direction along the surface of the prepreg on the surface of the prepreg, as shown in FIG. 2. Furthermore, in this disclosure, the "in-plane direction" means the direction along the surface of the fiber substrate inside the fiber substrate, as shown in FIG. 2. In both the "face direction" and the "in-plane direction," the direction is parallel to the direction extending approximately perpendicularly from one side of the prepreg to the side opposite that side. In this disclosure, "approximately perpendicular" means substantially perpendicular, and approximately perpendicular is preferably 86 to 94°, more preferably 88 to 92°, even more preferably 89 to 91°, and particularly preferably 90°.

[0016] (Regarding the Presence of Regions Unimpregnated with the Thermosetting Resin Composition in the Fiber Base Material) As described above, the prepreg preferably has regions impregnated with the thermosetting resin composition and regions unimpregnated with the fiber base material. In particular, it is more preferable that the unimpregnated regions are present, and preferably that the unimpregnated regions are present intermittently. The presence of the unimpregnated regions can be confirmed by determining the proportion of the impregnated regions of the thermosetting resin composition in the fiber base material. In other words, if the proportion of the impregnated regions is not 100%, it means that there are unimpregnated regions. In this embodiment, the proportion of the impregnated regions of the thermosetting resin composition in the fiber base material is not particularly limited, but may be 30 to 98%, 30 to 95%, 40 to 95%, 50 to 90%, or 60 to 85%. Note that if the proportion of the impregnated regions is 30% or more, unimpregnated regions are likely to be present intermittently. From this perspective, it is preferable that the proportion of the impregnated regions is 50% or more.

[0017] (Surface Roughness (Ra)) The prepreg is not particularly limited, but preferably has a surface roughness (arithmetic mean roughness Ra; hereinafter, sometimes simply referred to as "Ra") of 0.1 to 5 μm. The surface roughness (Ra) in this disclosure refers to the arithmetic mean height (Ra) that can be obtained from a roughness curve in accordance with ISO 4287 (1997). JIS B 0601 (2001) may be used instead of ISO 4287 (1997). Note that the surface roughness (Ra) in this disclosure refers to the surface roughness (Ra) obtained by measurement using a shape analysis laser microscope "VK-X100" (manufactured by Keyence Corporation). Here, the roughness curve is a curve obtained by applying a phase compensation high-pass filter λc (λc = 80 μm) to the cross-sectional curve and removing wavelengths of 80 μm or more from the cross-sectional curve. The analysis range is set to 1,000 μm×1,000 μm.

[0018] By setting the Ra of the prepreg of this embodiment to 0.1 μm or more, appropriate unevenness is imparted to the surface of the prepreg, thereby reducing the amount of static electricity and improving handleability. On the other hand, by setting the Ra to 5 μm or less, the thickness precision of the metal-clad laminate tends to be improved. From this perspective, the Ra of the prepreg may be 0.15 to 3 μm, 0.2 to 2 μm, 0.2 to 1.6 μm, 0.2 to 1.0 μm, or 0.2 to 0.7 μm. Unless otherwise specified, the Ra of the prepreg in this disclosure refers to the Ra of at least one surface of the prepreg, and the "surface" refers to the surface that will be overlapped when multiple prepregs are stacked to produce a laminate or a metal-clad laminate, or the surface opposite thereto, and does not include the side surface. It is preferable that the Ra of at least one surface of the prepreg is within the above range, and it is more preferable that the Ra of both surfaces is within the above range.

[0019] (Fiber Substrate) The fiber substrate contained in the prepreg used in (1) above can be any well-known fiber substrate used in various electrical insulating laminates. Examples of the fiber substrate material include natural fibers such as paper and cotton linters; inorganic fibers such as glass fibers and asbestos; organic fibers such as aramid, polyimide, polyvinyl alcohol, polyester, tetrafluoroethylene, and acrylic; and mixtures thereof. Among these, inorganic fibers are preferred from the viewpoint of flame retardancy, and glass fibers are more preferred. Examples of glass fibers include glass cloths made from E-glass, C-glass, D-glass, S-glass, etc.; glass cloths made from short fibers bonded with an organic binder; and blends of glass fibers and cellulose fibers. Among these, glass cloths made from E-glass are preferred. The shape of the fiber substrate is not particularly limited, and may be a woven fabric, a nonwoven fabric, a roving, a chopped strand mat, a surfacing mat, or the like. The shape of the fiber substrate may also be a woven fabric. The material and shape can be appropriately selected depending on the intended use and performance of the molded product. As the fiber substrate, one type may be used alone, or two or more types of materials and two or more types of shapes may be used in combination as necessary. The fiber substrate may be a fiber substrate consisting of one layer or a fiber substrate consisting of multiple layers. Note that a fiber substrate consisting of one layer means a fiber substrate consisting of only entangled fibers, and when there is a fiber substrate that is not entangled, it is classified as a fiber substrate consisting of multiple layers. The materials and shapes of two or more layer fiber substrates may be the same or different.

[0020] The thickness of the fiber substrate (see FIG. 3) may be 10 to 300 μm, 10 to 200 μm, 10 to 150 μm, or 12 to 100 μm. In the present disclosure, the thickness of the fiber substrate is the thickness at the portion shown in FIG. 3, and is the average value of values ​​obtained by measuring any five positions of the fiber substrate with a micrometer.

[0021] (Thermosetting Resin Composition) As described above, the prepreg used in (1) contains the fiber substrate and a thermosetting resin composition. The thermosetting resin composition contains at least a thermosetting resin. The components contained in the thermosetting resin composition are not particularly limited, but preferably contain at least one selected from the group consisting of a curing agent, a curing accelerator, an inorganic filler, an organic filler, a coupling agent, a leveling agent, an antioxidant, a flame retardant, a flame retardant assistant, a thixotropic agent, a thickener, a flexible material, a surfactant, and a photopolymerization initiator, in addition to the thermosetting resin. Each component contained in the thermosetting resin composition will be described below in order.

[0022] (Thermosetting Resin) Examples of thermosetting resins include epoxy resins, polyimide resins, maleimide resins, modified maleimide resins, phenolic resins, modified polyphenylene ether resins, cyanate resins, isocyanate resins, benzoxazine resins, oxetane resins, amino resins, unsaturated polyester resins, allyl resins, dicyclopentadiene resins, silicone resins, triazine resins, bismaleimide triazine resins, and melamine resins. Examples of the modified maleimide resin include a reaction product of a maleimide compound having at least two N-substituted maleimide groups with one or more compounds selected from the group consisting of monoamine compounds and diamine compounds. The maleimide resin does not include the modified maleimide resin. The modified polyphenylene ether resin is preferably a polyphenylene ether resin having an ethylenically unsaturated bond-containing group at its terminal, and more preferably a polyphenylene ether resin having an ethylenically unsaturated bond-containing group at both terminals. Examples of the ethylenically unsaturated bond-containing group include unsaturated aliphatic hydrocarbon groups such as vinyl, allyl, 1-methylallyl, isopropenyl, 2-butenyl, 3-butenyl, and styryl; and groups containing a heteroatom and an ethylenically unsaturated bond, such as maleimide and (meth)acryloyl groups. The thermosetting resin is not particularly limited to the examples given above, and known thermosetting resins can be used. One type of thermosetting resin may be used alone, or two or more types may be used in combination. From the viewpoints of moldability and electrical insulation, the thermosetting resin preferably contains one or more types selected from the group consisting of epoxy resins, polyimide resins, maleimide resins, modified maleimide resins, cyanate resins, modified polyphenylene ether resins, and bismaleimide triazine resins, and more preferably contains one or more types selected from the group consisting of epoxy resins, maleimide resins, modified maleimide resins, and cyanate resins.

[0023] The epoxy resin is preferably an epoxy resin having two or more epoxy groups per 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 are also classified into various epoxy resins based on differences in their main skeletons. For example, each of the above types of epoxy resins is further classified into bisphenol-type epoxy resins, alicyclic epoxy resins, aliphatic linear epoxy resins, novolac-type epoxy resins, stilbene-type epoxy resins, naphthalene-skeleton-containing epoxy resins, biphenyl-type epoxy resins, xylylene-type epoxy resins, and dihydroanthracene-type epoxy resins. One type of epoxy resin may be used alone, or two or more types may be used in combination from the viewpoints of insulation reliability and heat resistance. The epoxy resin may be a novolac-type epoxy resin or a phenol novolac-type epoxy resin.

[0024] The content of the thermosetting resin in the thermosetting resin composition is preferably 5 to 80 mass %, more preferably 10 to 60 mass %, and even more preferably 15 to 45 mass %, based on the total solid content.

[0025] (Curing Agent) For example, when the thermosetting resin contains an epoxy resin, examples of the curing agent include phenol-based curing agents, cyanate ester-based curing agents, acid anhydride-based curing agents, amine-based curing agents, and curing agents for epoxy resins such as active ester group-containing compounds. When the thermosetting resin contains a resin other than an epoxy resin, a known curing agent for the thermosetting resin can be used. One type of curing agent may be used alone, or two or more types may be used in combination.

[0026] The phenol-based curing agent is not particularly limited, but preferred examples include cresol novolac type phenolic resins, biphenyl aralkyl type phenolic resins, phenol novolac type phenolic resins, naphthylene ether type phenolic resins, and triazine skeleton-containing phenolic resins.

[0027] Examples of the cyanate ester curing agent include, but are not limited to, bisphenol A dicyanate and polyphenol cyanate (oligo(3-methylene-1,5-phenylene cyanate)). Examples of the acid anhydride curing agent include, but are not limited to, phthalic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, and pyromellitic anhydride. Examples of the amine curing agent include, but are not limited to, aliphatic amines such as triethylenetetramine and tetraethylenepentamine; and aromatic amines such as 4,4'-diaminodiphenylmethane. Furthermore, urea resins and the like can also be used as the curing agent.

[0028] When the thermosetting resin composition contains a curing agent, the content thereof is preferably 20 to 200 parts by mass, more preferably 20 to 150 parts by mass, and even more preferably 40 to 100 parts by mass per 100 parts by mass of the thermosetting resin. When the thermosetting resin composition contains a curing agent, the content thereof may be expressed in terms of functional group equivalent. Specifically, the content of the curing agent is preferably an amount that satisfies the formula: (mass of thermosetting resin / functional group equivalent) ≒ (mass of curing agent / functional group equivalent reactive with thermosetting resin) × constant C. The constant C varies depending on the type of functional group of the curing agent. When the functional group is a phenolic hydroxyl group, it is preferably 0.8 to 1.2; when the functional group is an amino group, it is preferably 0.2 to 0.4; and when the functional group is an active ester group, it is preferably 0.3 to 0.6. When the thermosetting resin contains an epoxy resin, the above formula becomes (mass of epoxy resin / epoxy group equivalent)≈(mass of curing agent / functional group equivalent capable of reacting with epoxy group)×constant C.

[0029] (Curing accelerator) As the curing accelerator, a general curing accelerator used for curing the thermosetting resin can be used.For example, when the thermosetting resin contains an epoxy resin, the curing accelerator can be an imidazole compound and its derivative; a phosphorus-based compound; a tertiary amine compound; a quaternary ammonium compound, etc. From the viewpoint of accelerating the curing reaction, an imidazole compound and its derivative are preferred. Specific examples of imidazole compounds and derivatives thereof include imidazole compounds such as 2-methylimidazole, 2-ethylimidazole, 2-undecylimidazole, 2-phenylimidazole, 1,2-dimethylimidazole, and 2,4-diamino-6-[2'-methylimidazolyl-(1')]ethyl-s-triazine; salts of the imidazole compounds and trimellitic acid such as 1-cyanoethyl-2-phenylimidazolium trimellitate; salts of the imidazole compounds and isocyanuric acid; and salts of the imidazole compounds and hydrobromic acid. The imidazole compounds and derivatives thereof may be used alone or in combination of two or more. The curing accelerator may be an imidazole compound and a derivative thereof, or may be an imidazole compound.

[0030] When the thermosetting resin composition contains a curing accelerator, the content thereof is preferably 0.1 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, and even more preferably 0.5 to 5 parts by mass, relative to 100 parts by mass of the thermosetting resin.

[0031] (Inorganic filler) The inorganic filler can reduce the thermal expansion coefficient and improve the coating strength. Examples of inorganic fillers include silica, alumina, barium sulfate, talc, mica, kaolin, boehmite, beryllia, barium titanate, potassium titanate, strontium titanate, calcium titanate, aluminum carbonate, magnesium hydroxide, aluminum hydroxide, aluminum borate, aluminum silicate, calcium carbonate, calcium silicate, magnesium silicate, zinc borate, zinc stannate, aluminum oxide, zirconia, mullite, magnesia, zinc oxide, titanium oxide, silicon carbide, silicon nitride, boron nitride, clay (e.g., calcined clay), molybdic acid compounds (e.g., zinc molybdate), short glass fibers, glass powder, and hollow glass beads. Preferred examples of the glass used to make short glass fibers, glass powder, and hollow glass beads include E-glass, T-glass, and D-glass. One type of inorganic filler may be used alone, or two or more types may be used in combination. Among these, silica and alumina are preferred from the viewpoint of reducing the coefficient of thermal expansion and the relative dielectric constant and dielectric loss tangent, and aluminum hydroxide is preferred from the viewpoint of heat resistance, with a combination of silica and aluminum hydroxide being more preferred. Examples of the silica include precipitated silica produced by a wet method and having a high water content, and dry-process silica produced by a dry method and containing almost no bound water. Further examples of dry-process silica include crushed silica, fumed silica, and fused silica (fused spherical silica), depending on the production method. The inorganic filler may be surface-treated with a surface treatment agent such as a silane coupling agent to improve moisture resistance, or may be hydrophobized to improve dispersibility.

[0032] When the thermosetting resin composition contains an inorganic filler, its content can be adjusted depending on the purpose of addition, but is preferably 0.1 to 65% by volume relative to the total solid content. A content of 0.1% by volume or more relative to the total solid content tends to reduce the thermal expansion coefficient. On the other hand, by limiting the content to 65% by volume or less, the viscosity during blending of the resin components does not become too high, and a decrease in workability tends to be easily suppressed. From the same perspective, the content of the inorganic filler is more preferably 10 to 60% by volume, even more preferably 15 to 55% by volume, and particularly preferably 30 to 55% by volume relative to the total solid content.

[0033] (Coupling Agent) The inclusion of a coupling agent improves the dispersibility of inorganic and organic fillers and improves adhesion to the reinforcing substrate and metal foil. One coupling agent may be used alone, or two or more may be used in combination. The coupling agent may be a titanate coupling agent, a silane coupling agent, or the like.

[0034] (Organic Solvent) From the viewpoint of ease of handling, the thermosetting resin composition may further contain an organic solvent. In the present disclosure, a thermosetting resin composition containing an organic solvent may be referred to as a resin varnish. The organic solvent is not particularly limited, but examples thereof include alcohol-based solvents such as methanol, ethanol, methyl cellosolve, butyl cellosolve, and propylene glycol monomethyl ether; ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, butanone, cyclohexanone, and 4-methyl-2-pentanone; ester-based solvents such as ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate, and γ-butyrolactone; ether-based solvents such as tetrahydrofuran; aromatic solvents such as toluene, xylene, and mesitylene; nitrogen-containing solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; and sulfur-containing solvents such as dimethyl sulfoxide. The organic solvent may be used alone or in combination of two or more types.

[0035] From the viewpoint of ease of application, for example, the content of the organic solvent may be adjusted so that the nonvolatile content of the thermosetting resin composition is preferably 20 to 85 mass %, more preferably 40 to 80 mass %.

[0036] The method for preparing the thermosetting resin composition is not particularly limited, and conventionally known preparation methods can be used. For example, a thermosetting resin and, if necessary, other components can be added to the organic solvent, and then mixed and stirred using various mixers to prepare a resin varnish. Examples of mixers include ultrasonic dispersion type, high-pressure collision type dispersion type, high-speed rotation type dispersion type, bead mill type, high-speed shear dispersion type, and rotation-revolution type dispersion type mixers.

[0037] (Prepreg Thickness) The thickness of the prepreg used in step (1) may be appropriately determined depending on the thickness of the fiber substrate, etc., but may be 10 to 300 μm, 15 to 200 μm, 15 to 150 μm, 15 to 100 μm, 15 to 60 μm, or 20 to 40 μm. Here, the thickness of the prepreg refers to the thickness of one prepreg. In the present disclosure, the thickness of the prepreg is the average value of values ​​obtained by measuring any five locations with a Digimatic indicator.

[0038] (Prepreg Manufacturing Method) The prepreg can be manufactured by impregnating a fiber substrate with a thermosetting resin film, as described above. The resin film can be produced by forming a layer of a thermosetting resin composition (resin layer) on one side of a release film. The resin layer can be formed, for example, by applying the resin varnish to one side of the release film and then drying it. The method for applying the resin varnish is not particularly limited, and can be carried out using known coating devices such as a comma coater, bar coater, kiss coater, roll coater, gravure coater, and die coater. These coating devices are preferably selected appropriately depending on the film thickness of the resin layer. The drying temperature and drying time vary depending on the amount of organic solvent used, the boiling point of the organic solvent, etc.; for example, in the case of a resin varnish containing 30 to 70% by mass of organic solvent, a resin film can be suitably formed by drying at 50 to 160°C for 1 to 8 minutes. The film produced in this manner is sometimes referred to as a resin film with a release film.

[0039] (Thickness of Resin Film) The thickness of the resin film may be appropriately determined depending on the thickness of the prepreg, etc. For example, when the thickness of the fiber substrate is in the range of 10 to 300 μm, the thickness of the resin film is preferably 3 to 200 μm, more preferably 5 to 150 μm, even more preferably 7 to 100 μm, and may be 7 to 50 μm or even 7 to 30 μm. In the present disclosure, the thickness of the resin film is a value measured as follows. First, the total thickness of the resin-coated film after coating is measured using a Digimatic indicator at any five locations. The resin layer at those measurement locations is peeled off with adhesive tape, and the thickness of the release film is measured using a Digimatic indicator. The thickness of the release film is then subtracted from the total thickness to obtain the average value. When the thickness of the resin film is equal to or greater than the lower limit, a sufficient amount of resin for impregnating the glass cloth tends to be secured. When the thickness of the resin film is equal to or less than the upper limit, the resin film tends to be easier to manufacture.

[0040] (Release Film) Examples of the release film include organic films such as polyethylene terephthalate (PET), biaxially oriented polypropylene (OPP), polyethylene, polyvinyl fluoride, and polyimide; and metal or alloy films such as copper and aluminum. These release films may be subjected to a release treatment with a release agent. The thickness of the release film is not limited, and from the viewpoints of ease of handling when applying the thermosetting resin composition and economic efficiency, it is preferably 10 to 200 μm, more preferably 20 to 100 μm, and even more preferably 30 to 70 μm. Commercially available release films can be used.

[0041] (Method of Impregnating a Fiber Substrate with a Resin Film) Next, a method of impregnating a fiber substrate with the resin film by lamination will be described. First, the resin film with a release film is placed on at least one surface of the fiber substrate so that the resin film abuts the fiber substrate. Then, the placed resin film with a release film and the fiber substrate are heated and pressurized, thereby impregnating the fiber substrate with the resin film. At this time, it is preferable to provide intermittent regions in the fiber substrate that are not impregnated with the thermosetting resin composition. Here, heating and pressurization are preferably performed by lamination. Examples of lamination methods include (a) roll lamination and (b) lamination under reduced pressure using a vacuum lamination method or the like.

[0042] (a) The conditions for roll lamination are not particularly limited, but the heating temperature is preferably 80 to 180°C, and the applied pressure (linear pressure) is preferably 0.05 to 1.0 MPa / m. (b) The conditions for laminating under reduced pressure are not particularly limited, but the heating temperature is preferably 50 to 170°C, more preferably 110 to 160°C, the applied pressure time is preferably 10 to 120 seconds, more preferably 20 to 80 seconds, and the applied pressure is preferably 0.05 to 1.0 MPa, more preferably 0.1 to 0.6 MPa.

[0043] (Method for Providing Unimpregnated Regions) As described above, it is preferable to provide regions unimpregnated with the thermosetting resin composition in the fiber substrate. The method is not particularly limited, but examples thereof include adjusting the conditions for heating and pressurizing the resin film with a release film and the fiber substrate. Specifically, the lamination conditions are exemplified. Specific methods for adjusting the heating and pressurizing conditions are not particularly limited, but examples thereof include the following method. First, a prepreg is produced under predetermined heating and pressurizing conditions, and then the proportion of impregnated regions of the thermosetting resin composition in the fiber substrate is determined based on the calculation method. If the impregnated regions are 100% as a result, that is, if there are no unimpregnated regions, the heating temperature or the pressurizing pressure is reduced, or both the heating temperature and the pressurizing pressure are reduced, and the prepreg is re-produced, and the proportion of impregnated regions is determined again. By repeating this process as necessary, the conditions for producing a prepreg having unimpregnated regions, preferably intermittently in the in-plane direction, can be easily determined. Furthermore, if it is desired to adjust the proportion of unimpregnated regions to a lower value, the heating temperature or the pressurizing pressure can be increased, or both the heating temperature and the pressurizing pressure can be increased, and the prepreg can be re-prepared. From the viewpoint of providing intermittent regions of the thermosetting resin composition in the fiber substrate, the heating temperature is preferably 100 to 160°C, more preferably 110 to 160°C, and even more preferably 120 to 150°C. Furthermore, from the viewpoint of providing intermittent regions of the thermosetting resin composition in the fiber substrate, the pressurizing pressure is preferably 0.2 MPa or more, more preferably 0.2 to 1.0 MPa, even more preferably 0.3 to 0.8 MPa, and particularly preferably 0.3 to 0.6 MPa. When laminating under reduced pressure, it is also possible to adjust the proportion of unimpregnated regions by adjusting the degree of vacuum.

[0044] It is preferable to laminate one or more resin films on each side of the fiber substrate. The number of resin films per side of the fiber substrate is preferably one or two, more preferably one. After the resin film is impregnated into the fiber substrate, the fiber substrate is cooled as necessary, and the release film is peeled off from the resulting prepreg with the release film, thereby obtaining the prepreg.

[0045] (Production of Laminate) In the above (1), a laminate is produced by placing the prepreg on one or both sides of a glass film. The number of prepregs placed may be one per side, or two or more per side. It is also preferable to place the prepreg on both sides of the glass film. The material of the glass film is not particularly limited, but examples include E-glass, C-glass, D-glass, and S-glass. The thickness of the glass film is not particularly limited, but is preferably 50 to 1,000 μm, more preferably 50 to 500 μm, even more preferably 70 to 300 μm, particularly preferably 100 to 250 μm, and most preferably 120 to 200 μm.

[0046] Also preferred is an embodiment that further includes the following (1') between (1) and (2). (1') A laminate is manufactured by disposing a glass film on one or both sides of the laminate obtained in (1) above, and then disposing the prepreg on the glass film, or by repeating (1') two or more times. By disposing a glass film on one or both sides of the laminate obtained in (1) above, and then disposing the prepreg on the glass film, for example, a laminate having a configuration of "glass film / prepreg / glass film / prepreg" or a laminate having a configuration of "prepreg / glass film / prepreg / glass film / prepreg / glass film / prepreg" is formed. Furthermore, by disposing a glass film on one or both sides of the laminate obtained in (1) above, and then repeating (1') n times (n is an integer of 2 or more), for example, a laminate having a configuration of "glass film / prepreg ( / glass film / prepreg) ｎ" (prepreg / glass film / ) ｎ Prepreg / glass film / prepreg ( / glass film / prepreg) ｎ " is formed.

[0047] (2) Manufacturing of Laminated Plates A laminated plate is manufactured by placing metal foil on one or both sides of the laminate and then hot-pressing and molding it. More specifically, metal foil can be placed so that it abuts the prepreg of the outermost layer of the laminate, and then hot-pressing and molding it. For example, hot-pressing and molding can be performed with a configuration such as "metal foil / prepreg / glass film / prepreg / metal foil." It is preferable to place metal foil on both sides of the laminate and then hot-press and molding it. A laminated plate obtained by placing metal foil on both sides of the laminate and then hot-pressing and molding it is also called a metal-clad laminated plate. Examples of the metal foil include copper foil, aluminum foil, tin foil, tin-lead alloy (solder) foil, and nickel foil. The thickness of the metal foil can be the thickness commonly used for laminated plates, but may be, for example, 1 to 200 μm. Other examples that can be used include a three-layer composite foil in which an intermediate layer is made of nickel, nickel-phosphorus, nickel-tin alloy, nickel-iron alloy, lead, lead-tin alloy, or the like, and a copper layer of 0.5 to 15 μm and a copper layer of 10 to 300 μm are provided on both sides of the intermediate layer, and a two-layer composite foil in which aluminum and copper foil are combined. When the metal foil is copper foil, the metal-clad laminate is called a copper-clad laminate.

[0048] Specific examples of the hot and pressure molding method include a method of hot and pressure molding in a vacuum press, where the degree of vacuum is preferably 300 kPa or less, more preferably 100 kPa or less, the temperature is preferably 130 to 350 ° C, more preferably 150 to 300 ° C, and even more preferably 170 to 250 ° C, and the pressure is preferably 0.5 to 10 MPa, more preferably 1 to 5 MPa, and even more preferably 2 to 5 MPa. This hot and pressure molding allows the thermosetting resin composition to flow into the unimpregnated regions of the fiber substrate, thereby tending to suppress the generation of voids. It should be noted that a laminate without metal foil can also be obtained by removing the metal foil from the metal-clad laminate of this embodiment by etching or the like.

[0049] [Method for manufacturing a printed wiring board] The present disclosure also provides a method for manufacturing a printed wiring board, which includes forming a wiring pattern on the laminate obtained by the manufacturing method. Examples of methods for forming the wiring pattern include known methods such as a subtractive method, a full-additive method, a semi-additive method (SAP: Semi-Additive Process), and a modified semi-additive method (m-SAP: Modified Semi-Additive Process).

[0050] [Method for Manufacturing a Semiconductor Package] The present disclosure also provides a method for manufacturing a semiconductor package, which includes mounting a semiconductor element on a printed wiring board obtained by the manufacturing method, and then encapsulating the semiconductor element with an encapsulating resin. That is, a semiconductor package can be manufactured by mounting a semiconductor element such as a semiconductor chip or memory at a predetermined position on the printed wiring board obtained by the manufacturing method using a known method, and then encapsulating the semiconductor element with an encapsulating resin or the like.

[0051] Next, the present embodiment will be described in more detail with reference to the following examples, but these examples do not limit the contents of the disclosure and the present embodiment.

[0052] The surface waviness of the prepreg produced in each example was measured according to the following method. The results are shown in Table 1. (Method for Measuring Surface Waviness) Using a shape analysis laser microscope "VK-X100" (manufactured by Keyence Corporation), shape measurement was performed automatically using an observation application to obtain a waviness curve in accordance with ISO 4287 (1997). The obtained waviness curve was subjected to surface roughness analysis using an analysis application to calculate the surface waviness (Wa). Here, the waviness curve is a curve obtained by applying a phase-compensated high-pass filter λc (λc = 80 μm) to the cross-sectional curve and removing wavelengths shorter than 80 μm from the cross-sectional curve. The analysis range was 1,000 μm x 1,000 μm. The surface waviness (Wa) was measured on both sides of the prepreg, and the larger value was used.

[0053] Furthermore, the copper-clad laminates produced in each example were evaluated according to the following methods.

[0054] (1. Method for evaluating yield during copper-clad laminate manufacturing) Five copper-clad laminates were prepared for each example. If the internal glass film was cracked, this could be confirmed from above the copper foil as shown in Figure 4. Therefore, the appearance was visually observed from above the copper foil, and the number of glass films that were not cracked among the five was counted.

[0055] (2. Method for Evaluating the Handling Properties of Copper-Clad Laminates) Evaluation substrates were prepared by cutting a piece measuring 250 mm long x 250 mm wide from the copper-clad laminate obtained in each example. As shown in FIG. 5 , the evaluation substrate was placed so that 60 mm from its edge was in contact with the table, and the edge of the evaluation substrate on the table was pressed against the table with fingers, causing the evaluation substrate to bend under its own weight. After the above operation, the appearance of the evaluation substrate was visually observed and evaluated according to the following evaluation criteria. A: No cracks occurred in the glass film. C: The glass film was cracked.

[0056] (3. Method for evaluating cutting processability of copper-clad laminate) The copper-clad laminate obtained in each example was cut into a size of 40 mm length x 40 mm width using a small precision cutting machine "Isomet LS" (manufactured by Buehler) to prepare evaluation substrates. The cut surfaces of the evaluation substrates were visually observed to check for cracks and chips, and evaluated according to the following evaluation criteria. A: No cracks or chips in the substrate on the cut surface. C: Cracks or chips in the substrate on the cut surface.

[0057] Production Example 1 (1-1. Preparation of Resin Varnish A) 60 parts by mass of phenol novolac epoxy resin "EPICLON (registered trademark) N-770" (manufactured by DIC Corporation, epoxy equivalent: 188 g / eq), 40 parts by mass of biphenyl aralkyl phenol resin (manufactured by UBE Inc., trade name: MEH-7700), 17.5 parts by mass of aluminum hydroxide, 86 parts by mass of fused silica, 0.5 parts by mass of 2-methylimidazole, and methyl isobutyl ketone and cyclohexanone as dilution solvents were mixed to prepare a white resin varnish A (aluminum hydroxide content: 8% by volume, fused silica content: 32% by volume) with a solids concentration of 65% by mass.

[0058] Production Example 2 (2-1. Preparation of modified maleimide resin) 595.8 g of bis(4-maleimidophenyl)methane, 54.2 g of 4,4′-diaminodiphenylmethane, and 350.0 g of propylene glycol monomethyl ether were placed in a 2 L reaction vessel equipped with a thermometer, a stirrer, a reflux condenser, and a moisture content monitor, and the contents were allowed to react under reflux for 5 hours to obtain a solution of modified maleimide resin. (2-2. Preparation of Resin Varnish B) 107 parts by mass of the modified maleimide resin solution, 30 parts by mass of tetrafunctional naphthalene-type epoxy resin "EXA-4710" (manufactured by DIC Corporation), 17.5 parts by mass of aluminum hydroxide, 130 parts by mass of fused silica, 0.5 parts by mass of 2,4-diamino-6-[2'-undecylimidazolyl-(1)']-ethyl-S-triazine, and methyl isobutyl ketone and cyclohexanone as dilution solvents were mixed to prepare a brown resin varnish B (aluminum hydroxide content: 8% by volume, fused silica content: 41.5% by volume) having a solids concentration of 65% by mass.

[0059] Example 1 (1. Preparation of Resin Film) The resin varnish A obtained in Production Example 1 was applied to a PET film (manufactured by Toyobo Film Solutions Co., Ltd., thickness: 50 μm, release film, product name: G2) using a comma coater. At this time, the amount applied was adjusted so that the coating width was 530 mm and the thickness after drying was 11 μm. Thereafter, the film was heated and dried at 130° C. for 2 minutes to prepare a resin film A with a PET film. (2. Preparation of Prepreg) Next, a glass cloth "IPC#1017" (manufactured by Nitto Boseki Co., Ltd., basis weight: 13 g / m ２The resin layer surface of the PET film-attached resin film A was placed on both sides of a fiber substrate (substrate width: 530 mm, thickness: 15 μm) so that the resin layer surface of the PET film-attached resin film A abutted against the glass cloth. This "PET film / resin film A / glass cloth / resin film A / PET film" laminate was heated and pressure molded under vacuum using a vacuum laminating device. In this manner, a PET film-attached prepreg was obtained in which the glass cloth was impregnated with the thermosetting resin composition of the resin film. The vacuum lamination conditions were a heating plate temperature of 130°C, a pressure of 0.5 MPa, a vacuum degree of 100 kPa or less, and a vacuum time of 30 seconds. The PET film was peeled from the resulting PET film-attached prepreg to obtain a 25 μm-thick prepreg 1 having regions impregnated and unimpregnated with the thermosetting resin composition in the fiber substrate. The thickness of prepreg 1 was determined as the average of the values ​​measured at five randomly selected locations using a leveled base and a Digimatic Indicator (manufactured by Mitutoyo Corporation). (3. Preparation of Laminate and Copper-Clad Laminate) A laminate was prepared by placing one prepreg 1 on each side of a glass film (150 μm thick, manufactured by Nippon Electric Glass Co., Ltd.). Then, 3 μm-thick copper foil "MT18Ex" (manufactured by Mitsui Mining & Smelting Co., Ltd., with an 18 μm-thick carrier copper foil) was placed on the top and bottom of the laminate. Next, pressing was performed under the following conditions to prepare copper-clad laminate 1 "copper foil / prepreg 1 / glass film / prepreg 1 / copper foil" (see Figure 6). The obtained copper-clad laminate 1 was subjected to the above-mentioned evaluations. The results are shown in Table 1. - Pressing conditions - Heating conditions: The temperature was raised from 25°C to 185°C at a rate of 3°C / min, and the temperature was maintained at 185°C for 90 minutes, followed by cooling for 30 minutes. Pressure conditions (pressure applied to the prepreg sandwiched between copper foils): 4 MPa (from the start of heating to the end of cooling).

[0060] Example 2 A resin film B with a PET film was produced by the same procedure as in "1. Preparation of a resin film" in Example 1, except that the resin varnish B obtained in Production Example 2 was used instead of the resin varnish A. Furthermore, a prepreg 2 with a thickness of 25 μm was obtained by the same procedure as in "2. Preparation of a prepreg" in Example 1, except that the resin film B with a PET film was used instead of the resin film A with a PET film. A copper-clad laminate 2 "copper foil / prepreg 2 / glass film / prepreg 2 / copper foil" (see FIG. 6) was produced by the same procedure as in "3. Preparation of a laminate and a copper-clad laminate" in Example 1, except that prepreg 2 was used instead of prepreg 1 and the heating conditions in the press conditions were changed to "heating from 25°C to 230°C at a heating rate of 3°C / min, holding at 230°C for 90 minutes, and then cooling for 30 minutes." The copper-clad laminate 2 was then subjected to the above-described evaluations. The results are shown in Table 1.

[0061] Comparative Example 1 Glass cloth "IPC#1017" (manufactured by Nitto Boseki Co., Ltd., basis weight: 13 g / m ２ A copper-clad laminate X (copper foil / prepreg X / glass film / prepreg X / copper foil) was prepared by immersing a copper-clad laminate X (base material width: 530 mm, thickness: 15 μm) in the resin varnish A prepared in Production Example 1, removing it, and then heating and drying it at 140°C for 3.5 minutes to obtain prepreg X (thickness: 25 μm). A copper-clad laminate X (copper foil / prepreg X / glass film / prepreg X / copper foil) (see FIG. 7) was produced by carrying out the same operations as in "3. Production of laminate and copper-clad laminate" in Example 1, except that prepreg X was used instead of prepreg 1. The obtained copper-clad laminate X was subjected to the above-mentioned evaluations. The results are shown in Table 1.

[0062] Comparative Example 2 Glass cloth "IPC#2116" (manufactured by Nitto Boseki Co., Ltd., basis weight: 104 g / m ２A copper-clad laminate Y (copper foil / prepreg Y / glass film / prepreg Y / copper foil) was prepared by immersing a copper-clad laminate Y (base material width: 530 mm, thickness: 91 μm) in resin varnish B prepared in Production Example 2, removing it, and then heating and drying it at 140°C for 3.5 minutes to obtain prepreg Y (thickness: 25 μm). A copper-clad laminate Y (copper foil / prepreg Y / glass film / prepreg Y / copper foil) (see FIG. 7) was produced by carrying out the same operations as in "3. Production of laminate and copper-clad laminate" in Example 2, except that prepreg Y was used instead of prepreg 2. The obtained copper-clad laminate Y was subjected to the above-mentioned evaluations. The results are shown in Table 1.

[0063] Comparative Example 3 A copper-clad laminate Z "copper foil / resin film A / E-glass film / resin film A / copper foil" (see FIG. 8) was produced by the same procedure as in Example 1, except that resin film A was used instead of prepreg 1 in "3. Production of laminate and copper-clad laminate" of Example 1. The obtained copper-clad laminate Z was subjected to the above-mentioned evaluations. The results are shown in Table 1.

[0064] From the results in Table 1, it can be seen that the copper-clad laminates produced in Examples 1 and 2 had high yields because the internal glass film did not crack during production. Furthermore, the copper-clad laminates produced in Examples 1 and 2 also had excellent handleability and cutting processability, making them highly industrially useful. On the other hand, the copper-clad laminates produced in Comparative Examples 1 and 2 had excellent handleability and cutting processability, but the internal glass film sometimes cracked during production, resulting in reduced yields. Furthermore, the copper-clad laminate produced in Comparative Example 3 often had internal glass film cracks during production, and had poor handleability and cutting processability.

[0065] 1 Glass film 2 Prepreg 1 used in Example 1 or Prepreg 2 used in Example 2 3 Copper foil 4 Prepreg X used in Comparative Example 1 or Prepreg Y used in Comparative Example 2 5 Resin film A used in Comparative Example 3

Claims

1. A method for producing a laminate, comprising the following (1): (1) Producing a laminate by disposing a prepreg having a surface waviness (Wa) of 5.0 μm or less on one or both sides of a glass film.

2. The method for producing a laminate according to claim 1, wherein the prepreg used in (1) is produced by impregnating a thermosetting resin film into a fiber substrate.

3. The method for producing a laminate according to claim 1, wherein the glass film has a thickness of 50 to 1,000 μm.

4. The method for producing a laminate according to claim 1, wherein in (1), the prepreg has a thickness of 10 to 300 μm.

5. A method for manufacturing a laminate comprising the following steps (1) and (2) in this order: (1) Producing a laminate by arranging a prepreg having a surface waviness (Wa) of 5.0 μm or less on one or both sides of a glass film, and (2) Producing a laminate by arranging a metal foil on one or both sides of the laminate and then hot-pressing and molding the laminate.

6. The method for producing a laminate according to claim 5, further comprising the following (1') between (1) and (2): (1') producing a laminate by arranging a glass film on one or both sides of the laminate obtained in (1) and then arranging the prepreg on the glass film, or by repeating (1') two or more times.

7. A method for producing a printed wiring board, comprising forming a wiring pattern on the laminate obtained by the method according to claim 5.

8. A method for manufacturing a semiconductor package, comprising mounting a semiconductor element on the printed wiring board obtained by the manufacturing method according to claim 7, and then sealing the semiconductor element with a sealing resin.

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