FRP precursor, FRP, metal-clad laminate, printed wiring board, and semiconductor package

Abstract

Provided is an FRP precursor which comes to have satisfactory laser processing accuracy and can attain a reduction of variations in dimensional-change ratio. Also provided is an FRP having satisfactory laser processing accuracy and reduced variations in dimensional-change ratio. A printed wiring board and a semiconductor package are further provided. Specifically, the FRP precursor comprises glass cloth and either a heat-curable resin composition or a semi-cured object formed from the heat-curable resin composition, wherein the glass cloth has a K (%), defined by the expression, of 30 or less. In the expression, A indicates warp width (μm), B indicates weft width (μm), a indicates warp-to-warp distance (μm), and b indicates weft-to-weft distance (μm).

Description

FRP Precursor, FRP, Metal-Clad Laminate, Printed Wiring Board, and Semiconductor Package

[0001] The present disclosure relates to an FRP precursor, FRP, a metal-clad laminate, a printed wiring board, and a semiconductor package.

[0002] FRP (Fiber Reinforced Plastics; fiber-reinforced plastic) is a composite material that uses a material with a high elastic modulus such as fiber as an aggregate and incorporates the aggregate into a base material (matrix) such as plastic to improve strength. It is a composite material that takes advantage of weather resistance, heat resistance, chemical resistance, and light weight, and is inexpensive, lightweight, and highly durable. Since the FRP has moldability and high strength, it is used in a wide range of fields such as structural materials for housing equipment, ships, vehicles, and aircraft, and electronic equipment by taking advantage of its insulation properties. Examples of FRP used in electronic equipment include cured products of prepregs, and prepregs in a pre-cured or semi-cured state correspond to FRP precursors. In recent years, with the improvement in performance of mobile electronic devices such as smartphones and tablet computers, miniaturization, thinning, and high density of semiconductor packages have been progressing. Therefore, the demand for thinning of the FRP precursor used in semiconductor packages has been increasing, and in order to meet this demand, attempts have been made to thin the FRP precursor while using a method of thermocompression bonding a resin film to a glass cloth during the production of the FRP precursor (see, for example, Patent Document 1).

[0003] International Publication No. 2018 / 181513

[0004] As FRP precursors become thinner, glass cloths are also becoming thinner. The inventors have investigated and found that when laser processing is performed to form fine via holes in thinned FRP precursors, the laser processing accuracy tends to be worse compared to thicker FRP precursors. Furthermore, with the miniaturization and thinning of semiconductor packages, a multi-stage lamination method is required for laminating FRP precursors, and the FRP precursors are subjected to multiple heat loads and stresses during lamination. Therefore, if the dimensional change rate of metal-clad laminates made using FRP precursors varies greatly, misalignment of vias connecting the layers may occur with each lamination. For this reason, it is necessary to stabilize the variation in the dimensional change rate of metal-clad laminates. However, the inventors have investigated and found that the variation in dimensional change rate can be large in thinned FRP precursors.

[0005] This disclosure has been made in view of the above-mentioned problems, and aims to provide an FRP precursor that has good laser processing accuracy and can suppress variations in dimensional change rate, an FRP that has good laser processing accuracy and suppresses variations in dimensional change rate, and a printed circuit board and a semiconductor package.

[0006] As a result of diligent research by the present inventors, we have found that the above objective can be achieved by the embodiments of the present disclosure. The present disclosure includes the following embodiments [1] to

[10] . [1] An FRP precursor comprising glass cloth and a thermosetting resin composition or a semi-cured product of the thermosetting resin composition, wherein the glass cloth has a K (%) defined by the following formula of 30 or less. (In the formula, A is the warp width (μm), B is the weft width (μm), a is the distance between warp threads (μm), and b is the distance between weft threads (μm).) [2] In K, a = (25,000 - AX) / X and b = (25,000 - BY) / Y [wherein X is the density of warp threads (threads / 25 mm), and Y is the density of weft threads (threads / 25 mm). A, B, a, and b are as defined above.], the FRP precursor described in [1] above. [3] The FRP precursor described in [1] or [2] above, wherein the thickness of the glass cloth is 5 to 50 μm. [4] The FRP precursor described in any of [1] to [3] above, wherein A is 50 to 250 (μm) and B is 80 to 350 (μm). [5] An FRP precursor according to any one of [1] to [4] above, wherein a is 100 to 200 (μm) and b is 30 to 140 (μm). [6] An FRP precursor according to any one of [1] to [5] above, wherein the content (solid content) of the thermosetting resin composition or the semi-cured product of the thermosetting resin composition is 60 to 90% by mass of the total amount of the FRP precursor. [7] FRP which is a cured product of the FRP precursor according to any one of [1] to [6] above. [8] A metal-clad laminate comprising metal foil and the FRP according to [7] above. [9] A printed circuit board comprising the FRP according to [7] above or the metal-clad laminate according to [8] above.

[10] A semiconductor package comprising the printed circuit board according to [9] above and a semiconductor element.

[0007] According to the present invention, it is possible to provide an FRP precursor that exhibits good laser processing accuracy and suppresses variations in dimensional change rate, an FRP that exhibits good laser processing accuracy and suppresses variations in dimensional change rate, and a printed circuit board and a semiconductor package.

[0008] This is a plan view showing a portion of the glass cloth contained in the FRP precursor of this embodiment. This is a conceptual diagram of an example of a manufacturing apparatus that can be used to manufacture the FRP precursor of this embodiment. This is a schematic diagram for explaining the vertical and horizontal diameters of the vias on the evaluation substrate when evaluating the laser processability in the examples and comparative examples. This is a schematic diagram showing the drilling process performed when evaluating the dimensional change rate in the examples and comparative examples. This is a graph showing the evaluation results of the dimensional change rate in Example 1. This is a graph showing the evaluation results of the dimensional change rate in Example 2. This is a graph showing the evaluation results of the dimensional change rate in Example 3. This is a graph showing the evaluation results of the dimensional change rate in Example 4. This is a graph showing the evaluation results of the dimensional change rate in Comparative Example 1.

[0009] [FRP Precursor] The FRP precursor of this embodiment is the following FRP precursor: An FRP precursor containing glass cloth and a thermosetting resin composition or a semi-cured product of the thermosetting resin composition, wherein the glass cloth has a K (%) defined by the following formula of 30 or less. (In the formula, A represents the warp width (μm), B represents the weft width (μm), a represents the distance between warp threads (μm), and b represents the distance between weft threads (μm).) The FRP precursor in this embodiment may be a prepreg.

[0010] A and B are the average values ​​of the thread widths at any 10 locations when observed with an optical microscope (magnification: 100x). Also, a and b are the average values ​​of the distances between threads at any 10 locations when observed with an optical microscope (magnification: 100x). Figure 1 shows a plan view of the glass cloth with A and B and a and b clearly indicated.

[0011] The value of K can be said to be close to the porosity of the glass cloth. When K is 30 or less, the laser processing accuracy of the metal-clad laminate is good and the variation in the rate of dimensional change is effectively suppressed. From a similar viewpoint, the value of K(%) is preferably 28 or less, more preferably 26 or less, even more preferably 25 or less, and may be 20 or less, 17 or less, 12 or less, or 10 or less. The lower limit of the value of K(%) is not particularly limited, but from the viewpoint of the impregnation of the resin varnish into the glass cloth, it is preferably 5 or more, more preferably 7 or more. In other words, the value of K(%) is preferably 5 to 30. The value of K(%) may be 10 to 30, 13 to 30, 13 to 26, 5 to 17, or 5 to 12.

[0012] The A (μm) is not particularly limited, but from the viewpoint of laser processing accuracy, suppression of variations in dimensional change rate, and impregnation of the resin varnish into the glass cloth, it is preferably 50 to 250, more preferably 70 to 230, even more preferably 80 to 200, particularly preferably 85 to 150, most preferably 90 to 140, and may also be 90 to 130. The B (μm) is not particularly limited, but from the viewpoint of laser processing accuracy, suppression of variations in dimensional change rate, and impregnation of the resin varnish into the glass cloth, it is preferably 80 to 350, more preferably 90 to 300, even more preferably 100 to 270, may also be 100 to 250, may also be 100 to 220, may also be 100 to 200, may also be 110 to 180, and may also be 120 to 170.

[0013] In K, it is preferable that a = (25,000 - AX) / X and b = (25,000 - BY) / Y. Here, X represents the density of the warp threads (threads / 25 mm), and Y represents the density of the weft threads (threads / 25 mm). X (threads / 25 mm) is not particularly limited, but is preferably 50 to 150, more preferably 60 to 130, even more preferably 65 to 120, and may also be 70 to 120, 80 to 120, 85 to 120, or 90 to 120. Y (threads / 25 mm) is not particularly limited, but is preferably 50 to 150, more preferably 60 to 130, even more preferably 65 to 120, and may also be 70 to 120, 80 to 120, 85 to 120, or 90 to 120. Furthermore, while a (μm) is not particularly limited, it is preferably 100 to 200, more preferably 110 to 180, and even more preferably 120 to 160. While b (μm) is not particularly limited, it is preferably 30 to 140, more preferably 40 to 120, and even more preferably 45 to 100.

[0014] The aforementioned glass cloth is not particularly limited, but is usually composed of one row of warp threads and one row of weft threads.

[0015] From the viewpoint of thinning the FRP precursor, the thickness of the glass cloth is preferably 5 to 50 μm, more preferably 5 to 40 μm, even more preferably 5 to 30 μm, particularly preferably 5 to 20 μm, most preferably 5 to 15 μm, and may also be 5 to 13 μm, 6 to 12 μm, 8 to 12 μm, or 10 to 12 μm. While a glass cloth thickness below the above upper limit contributes to thinning the FRP precursor, generally, this tends to reduce laser processing accuracy and increase the variation in dimensional change rate. However, with the FRP precursor of this embodiment, even if the glass cloth thickness is below the above upper limit, good laser processing accuracy can be maintained and the variation in dimensional change rate can be suppressed to a small extent.

[0016] (Method for producing FRP precursor) The method for producing the FRP precursor in this embodiment is not particularly limited, but one method is to pressure-impregnate a glass cloth with a thermosetting resin film. Hereinafter, the thermosetting resin film may be simply referred to as "resin film". The terms "thermosetting resin film" and "resin film" do not include the protective film and support described later. In addition, in this invention, "pressure pressing" means applying pressure while in contact.

[0017] An example of a method for manufacturing the FRP precursor of this embodiment will be described below with reference to Figure 2. Figure 2 shows a roll-to-roll FRP precursor manufacturing apparatus. The FRP precursor manufacturing apparatus 1 press-fits and impregnates a resin film 54 onto one side of a glass cloth 40, and press-fits a second support 56 onto the other side of the glass cloth 40. The FRP precursor manufacturing apparatus 1 is placed under normal pressure.

[0018] The FRP precursor manufacturing apparatus 1 comprises a glass cloth delivery device 2, a resin film delivery device 3, an FRP precursor heating and pressing device 6, an FRP precursor pressurizing and cooling device 7, and an FRP precursor winding device 8. Preferably, the FRP precursor manufacturing apparatus 1 further comprises a protective film peeling mechanism 4 and a protective film winding device 5. The FRP precursor manufacturing apparatus 1 may also have a glass cloth heating device (not shown) for heating the glass cloth before it is sent to the FRP precursor heating and pressing device 6, and a resin film heating device (not shown) for heating the resin film before it is sent to the FRP precursor heating and pressing device 6.

[0019] The glass cloth dispensing device 2 is a device that dispenses the glass cloth 40 wound on a roll by rotating the roll in the opposite direction to the winding direction. In Figure 2, the glass cloth dispensing device 2 is dispensing the glass cloth 40 from the underside of the roller toward the FRP precursor heating and pressurizing device 6.

[0020] The resin film dispensing device 3 has a roll around which a protective film-attached resin film 50 (hereinafter also simply referred to as "multilayer film 50") is wound, and a support mechanism that rotatably supports the roll while applying a predetermined tension to the multilayer film 50 being dispensed. The device dispenses the multilayer film 50 wound around the roll by rotating the roll in the opposite direction to the winding direction. The resin film dispensing device 3 is located on the surface 40a side of the dispensed glass cloth 40 and dispenses the multilayer film 50 from below the roller toward one of the protective film peeling mechanisms 4 such that the protective film 52 is on the side of the dispensed glass cloth 40.

[0021] The protective film peeling mechanism 4 is a deflection roller located on the surface 40a side of the fed-out glass cloth 40. The protective film peeling mechanism 4 receives the multilayer film 50, which is fed out from the resin film feeding device 3 and moves toward the protective film peeling mechanism 4, on the surface of the rotating deflection roller. Furthermore, it is a mechanism that peels the protective film 52 from the multilayer film 50 by advancing the resin film 54 of the multilayer film 50 toward the FRP precursor heating and pressurizing device 6 and advancing the protective film 52 toward the protective film winding device 5. As a result, the glass cloth side film surface 54a of the resin film 54 is exposed.

[0022] The protective film winding device 5 is located on the surface 40a side of the fed-out glass cloth 40 and is a winding device that winds up the protective film 52 that has been peeled off by the protective film peeling mechanism 4.

[0023] The FRP precursor heating and pressing device 6 includes a pair of heating and compression rollers and a compression force application mechanism (not shown) that applies compressive force to the pair of heating and compression rollers. The pair of heating and compression rollers have heating elements inside so that they can be heated to a predetermined set temperature. The FRP precursor heating and pressing device 6 forms a sheet-like FRP precursor 60 by pressing and impregnating a resin film 54 onto a glass cloth 40 with a rotating pair of heating and compression rollers (film pressing process), and also sends the FRP precursor 60 toward the FRP precursor pressurizing and cooling device 7. At this time, the resin film 54 is laminated onto the glass cloth 40 so that the glass cloth side film surface 54a side adheres to the glass cloth 40 surface 40a side, thereby forming the FRP precursor 60. The temperature of the heating and pressing rollers is preferably in the range of -20 to 30°C, which is the minimum melt viscosity temperature of the resin film used, and more preferably in the range of -10 to 20°C. Here, the measurement of the minimum melt viscosity temperature of the resin film is not particularly limited, but for example, it can be performed using a rheometer manufactured by T.A. Instrument Japan Co., Ltd. at a heating rate of 3°C / min. Furthermore, the linear pressure when the resin film is pressure-pressed and impregnated into the glass cloth is preferably 0.1 to 1 MPa, more preferably 0.2 to 0.7 MPa, and even more preferably 0.2 to 0.5 MPa. The FRP precursor 60 sent out from the FRP precursor heating and pressurizing device 6 is in a high-temperature state.

[0024] The FRP precursor pressurizing and cooling device 7 includes a pair of cooling and compression rollers and a compression force application mechanism (not shown) that applies compressive force to the pair of cooling and compression rollers. The pair of cooling and compression rollers compress and cool the high-temperature FRP precursor 60, which is sent out from the FRP precursor heating and pressurizing device 6, with the rotating pair of cooling and compression rollers, and send it to the FRP precursor winding device 8.

[0025] The FRP precursor winding device 8 includes a roll for winding the sheet-like FRP precursor 60 fed out from the FRP precursor pressurizing and cooling device 7, and a drive mechanism (not shown) for rotating the roll.

[0026] [Resin Film] The resin film used in the method for producing the FRP precursor is a thermosetting resin film, which is formed from a thermosetting resin composition into a film. The thermosetting resin composition contains at least a thermosetting resin. In addition to the thermosetting resin, examples of other materials that may be used as needed include curing agents, curing accelerators, inorganic fillers, organic fillers, coupling agents, leveling agents, antioxidants, flame retardants, flame retardant aids, thixotropy imparters, thickeners, thixotropy imparters, flexible materials, surfactants, photopolymerization initiators, etc., and it is preferable to contain at least one selected from these. The components contained in the thermosetting resin composition will be described in order below.

[0027] (Thermosetting resins) Examples of thermosetting resins include epoxy resins, phenolic resins, unsaturated imide resins, cyanate resins, isocyanate resins, benzoxazine resins, oxetane resins, unsaturated polyester resins, allyl resins, dicyclopentadiene resins, silicone resins, triazine resins, melamine resins, urea resins, furan resins, etc. However, the material is not limited to these, and any known thermosetting resin can be used. These can be used individually or in combination of two or more. Among these, epoxy resins are preferred from the viewpoint of workability, moldability, and manufacturing cost.

[0028] Examples of epoxy resins include novolac-type epoxy resins such as cresol novolac-type epoxy resin, phenol novolac-type epoxy resin, naphthol novolac-type epoxy resin, aralkyl novolac-type epoxy resin, and biphenyl novolac-type epoxy resin; bisphenol-type epoxy resins such as bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, bisphenol AD-type epoxy resin, bisphenol S-type epoxy resin, bisphenol T-type epoxy resin, bisphenol Z-type epoxy resin, and tetrabromobisphenol A-type epoxy resin; biphenyl-type epoxy resin, tetramethylbiphenyl-type epoxy resin, triphenyl-type epoxy resin, tetraphenyl-type epoxy resin, naphthol aralkyl-type epoxy resin, naphthalenediol aralkyl-type epoxy resin, naphthol aralkyl-type epoxy resin, fluorene-type epoxy resin, epoxy resin having a dicyclopentadiene skeleton, epoxy resin having an ethylenically unsaturated group in its skeleton, and alicyclic epoxy resins; diglycidyl ethers of polyfunctional phenols; and hydrogenated versions thereof. The epoxy resin may be used alone, or two or more types may be used in combination from the viewpoint of insulation reliability and heat resistance. The epoxy resin preferably contains a novolac-type epoxy resin, more preferably contains one or more selected from the group consisting of cresol novolac-type epoxy resins and phenol novolac-type epoxy resins, and even more preferably contains both cresol novolac-type epoxy resins and phenol novolac-type epoxy resins. Examples of commercially available epoxy resins include "EPICLON N-660" (manufactured by DIC Corporation), which is a cresol novolac-type epoxy resin, and "EPICLON 840S" (manufactured by DIC Corporation), "jER828EL," and "YL980" (all manufactured by Mitsubishi Chemical Corporation), which are bisphenol A-type epoxy resins.

[0029] Here, the epoxy resin is not particularly limited, but from the viewpoint of imparting flexibility, it may be an epoxy resin having two or more epoxy groups in one molecule and a structural unit derived from alkylene glycol with three or more carbon atoms in the alkylene group in the main chain. Furthermore, from the viewpoint of further improving flexibility, the structural unit derived from alkylene glycol with three or more carbon atoms in the alkylene group may be repeated two or more times in succession. As the alkylene glycol with three or more carbon atoms in the alkylene group, alkylene glycol with four or more carbon atoms in the alkylene group is preferred. The upper limit of the number of carbon atoms in the alkylene group is not particularly limited, but it is preferably 15 or less, more preferably 10 or less, and even more preferably 8 or less. Furthermore, from the viewpoint of flame retardancy, a halogenated epoxy resin may be used as the epoxy resin.

[0030] (Curing agent) When the thermosetting resin is an epoxy resin, examples of curing agents include phenolic curing agents, cyanate ester curing agents, acid anhydride curing agents, amine curing agents, and epoxy resin curing agents such as active ester group-containing compounds. When the thermosetting resin is a resin other than an epoxy resin, known curing agents for that thermosetting resin can be used. One type of curing agent may be used alone, or two or more types may be used in combination.

[0031] The phenolic curing agent is not particularly limited, but preferred examples include cresol novolac type curing agents, biphenyl type curing agents, phenol novolac type curing agents, naphthylene ether type curing agents, and triazine skeleton-containing phenolic curing agents. Commercially available phenolic curing agents include cresol novolac type curing agents such as KA-1160, KA-1163, and KA-1165 (all manufactured by DIC Corporation); biphenyl type curing agents such as MEH-7700, MEH-7810, and MEH-7851 (all manufactured by Meiwa Kasei Co., Ltd.); phenol novolac type curing agents such as Phenolite TD2090 (manufactured by DIC Corporation); naphthylene ether type curing agents such as EXB-6000 (manufactured by DIC Corporation); and triazine skeleton-containing phenolic curing agents such as LA3018, LA7052, LA7054, and LA1356 (all manufactured by DIC Corporation). Among these, cresol novolac type curing agents are preferred.

[0032] There are no particular limitations on the cyanate ester-based curing agent, but examples include bisphenol A dicyanate, polyphenol cyanate (oligo(3-methylene-1,5-phenylene cyanate)), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidene diphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanatephenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanatephenyl-1-(methylethylidene))benzene, bis(4-cyanatephenyl) thioether, and bis(4-cyanatephenyl) ether.

[0033] The acid anhydride-based curing agent is not particularly limited, but examples include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, hydrogenated methylnadic anhydride, trialkyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexen-1,2-dicarboxylic acid anhydride, trimellitic anhydride, pyromellitic anhydride, etc. The amine-based curing agent is not particularly limited, but examples include aliphatic amines such as triethylenetetramine, tetraethylenepentamine, and diethylaminopropylamine; aromatic amines such as metaphenylenediamine and 4,4'-diaminodiphenylmethane. Urea resin can also be used as a curing agent.

[0034] When the thermosetting resin composition contains a curing agent, the amount is preferably 20 to 150 parts by mass, more preferably 20 to 100 parts by mass, and even more preferably 40 to 100 parts by mass, per 100 parts by mass of the thermosetting resin. The amount of epoxy resin curing agent is preferably such that the ratio of the reactive group equivalents of the curing agent to the epoxy equivalents of the epoxy resin is 0.3 to 1.5 equivalents. When the amount of epoxy resin curing agent is within the above range, the degree of curing is easily controlled, and productivity is improved.

[0035] (Curing accelerator) As the curing accelerator, general curing accelerators used for curing the thermosetting resin can be used. For example, when the thermosetting resin is an epoxy resin, examples of curing accelerators include imidazole compounds and their derivatives; phosphorus compounds; tertiary amine compounds; quaternary ammonium compounds, etc. From the viewpoint of accelerating the curing reaction, imidazole compounds and their derivatives are preferred. Imidazole compounds and their derivatives include 2-methylimidazole, 2-ethylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 1,2-dimethylimidazole, 2-ethyl-1-methylimidazole, 1,2-diethylimidazole, 1-ethyl-2-methylimidazole, 2-ethyl-4-methylimidazole, 4-ethyl-2-methylimidazole, 1-isobutyl-2-methylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, and 2-phenyl-4,5-dihydroxymethylimidazole. Examples include imidazole compounds such as zole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 2,4-diamino-6-[2'-methylimidazolyl-(1')]ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]ethyl-s-triazine, and 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]ethyl-s-triazine; modified imidazole compounds such as isocyanate-masquimidazole and epoxy-masquimidazole; salts of the imidazole compounds with trimellitic acid, such as 1-cyanoethyl-2-phenylimidazolium trimellitate; salts of the imidazole compounds with isocyanuric acid; and salts of the imidazole compounds with hydrobromic acid. Among these, modified imidazole compounds are preferred, and isocyanate-masked imidazole is more preferred. The imidazole compound may be used alone or in combination of two or more.

[0036] If the thermosetting resin composition contains a curing accelerator, the amount 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 6 parts by mass, per 100 parts by mass of the thermosetting resin, from the viewpoint of storage stability and physical properties of the thermosetting resin composition.

[0037] (Inorganic Fillers) Inorganic fillers can improve impermeability and wear resistance, and reduce the coefficient of thermal expansion. Examples of inorganic fillers include oxides such as silica, aluminum oxide, zirconia, mullite, and magnesia; hydroxides such as aluminum hydroxide, magnesium hydroxide, and hydrotalcite; nitride ceramics such as aluminum nitride, silicon nitride, and boron nitride; natural minerals such as talc, montmorillonite, and saponite; metal particles, carbon particles, etc. Among these, oxides and hydroxides are preferred, silica and aluminum hydroxide are more preferred, and aluminum hydroxide is even more preferred.

[0038] When a thermosetting resin composition contains an inorganic filler, the amount of the filler varies depending on the purpose of addition, but it is preferably 0.1 to 65% by volume of the solid content of the thermosetting resin composition. For coloring and opacity purposes, an amount of 0.1% by volume or more tends to be sufficient. On the other hand, when added for volume increase purposes, keeping the amount below 65% by volume tends to suppress a decrease in adhesive strength, and also tends to prevent the viscosity from becoming too high when the resin components are blended, thus suppressing a decrease in workability. From a similar viewpoint, the amount of inorganic filler is more preferably 5 to 50% by volume, and even more preferably 10 to 40% by volume. Here, solid content refers to the components in the composition other than the organic solvent described later.

[0039] (Coupling Agent) By including a coupling agent, the dispersibility of inorganic and organic fillers is improved, and the adhesion to the reinforcing substrate is also improved. One type of coupling agent may be used alone, or two or more types may be used in combination. Silane-based coupling agents are preferred. Examples of silane-based coupling agents include aminosilane-based coupling agents [e.g., 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, etc.], epoxysilane-based coupling agents [e.g., 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, etc.], phenylsilane-based coupling agents, alkylsilane-based coupling agents, and alkenylsilane-based coupling agents [e.g., vinylsilane-based vinyl trichlorosilane, vinyltriethoxysilane, etc.]. Examples of coupling agents include alkynylsilane coupling agents, haloalkylsilane coupling agents, siloxane coupling agents, hydrosilane coupling agents, silazane coupling agents, alkoxysilane coupling agents, chlorosilane coupling agents, (meth)acrylicsilane coupling agents, aminosilane coupling agents, isocyanuratesilane coupling agents, ureidosilane coupling agents, mercaptosilane coupling agents, sulfidosilane coupling agents, and isocyanatesilane coupling agents. Among these, epoxysilane coupling agents are preferred, and 3-glycidoxypropyltrimethoxysilane is more preferred. In addition, so-called titanate coupling agents, in which the silane moiety is replaced with titanate, can also be used.

[0040] When the thermosetting resin composition contains a coupling agent, the amount is preferably 0.1 to 5 parts by mass, more preferably 0.1 to 4 parts by mass, and even more preferably 0.5 to 3 parts by mass, per 100 parts by mass of the thermosetting resin. If the amount is 0.01 parts by mass or more, it tends to sufficiently cover the surface of the aggregate and the surface of the filler, and if it is 5 parts by mass or less, it tends to suppress the generation of excess coupling agent.

[0041] (Organic Solvent) From the perspective of facilitating handling, an organic solvent may be further added to the thermosetting resin composition. In this specification, a resin composition containing an organic solvent may sometimes be referred to as a resin varnish. When forming a resin film, it is preferably used as a resin varnish from the perspective of workability. The organic solvent is not particularly limited, but examples include alcohol solvents such as methanol, ethanol, propanol, butanol, methyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, and tripropylene glycol monomethyl ether; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, butanone, cyclohexanone, and 4-methyl-2-pentanone; ester solvents such as ethyl acetate, butyl acetate, and propylene glycol monomethyl ether acetate; ether solvents such as tetrahydrofuran; aromatic solvents such as toluene, xylene, and mesitylene; nitrogen atom-containing solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; sulfur atom-containing solvents such as dimethyl sulfoxide, and the like. Among these, from the perspectives of solubility and appearance after coating, ketone solvents are preferred, cyclohexanone, methyl ethyl ketone, and methyl isobutyl ketone are more preferred, and cyclohexanone and methyl ethyl ketone are even more preferred. The organic solvent may be used alone or in combination of two or more kinds.

[0042] From the perspective of ease of coating, for example, the content of the organic solvent is adjusted so that the solid content of the thermosetting resin composition is preferably 20 to 85% by mass, more preferably 40 to 80% by mass.

[0043] In the FRP precursor of this embodiment, the content rate (content rate of solid content) of the thermosetting resin composition or the semi-cured product of the thermosetting resin composition is preferably 60 to 90% by mass, more preferably 65 to 85% by mass, and even more preferably 70 to 80% by mass with respect to the total amount of the FRP precursor.

[0044] (Method for Producing Thermosetting Resin Film) First, after adding the thermosetting resin and, if necessary, other components to the organic solvent, mix and stir using various mixers to obtain a resin varnish. Examples of mixers include mixers such as ultrasonic dispersion method, high-pressure collision dispersion method, high-speed rotation dispersion method, bead mill method, high-speed shear dispersion method, and rotation-revolution dispersion method. The obtained resin varnish is applied to a carrier film, unnecessary organic solvent is removed, and then semi-cured (B-staged) to produce a thermosetting resin film. As the carrier film, organic films such as polyethylene terephthalate (PET), biaxially oriented polypropylene (OPP), polyethylene, polyvinyl fluoride, and polyimide; films of copper, aluminum, and alloys of these metals; films obtained by performing a release treatment with a release agent on the surface of these organic films or metal films, etc. may be mentioned. When winding the produced resin film with a roller, it is preferable to arrange the carrier film on the surface coated with the thermosetting resin composition and semi-cured and wind it in a state sandwiching the thermosetting resin composition because the workability is good.

[0045] In addition, there is no particular limitation on the thickness of the resin film. When using a resin film thinner than the thickness of the aggregate, two or more resin films may be attached to one surface of the aggregate. Also, when using two or more resin films, those with different thermosetting degrees or blending compositions of the resin films may be combined and used. The thickness of the resin film may be 5 to 100 μm, may be 5 to 70 μm, may be 5 to 50 μm, may be 5 to 35 μm, or may be 10 to 30 μm. The FRP precursor may be cut to an arbitrary size as necessary, adhered to a predetermined object as necessary, and then thermally cured. Also, the FRP precursor may be wound around a roll in advance and used by roll-to-roll.

[0046] <Support> Examples of the support for the resin film (first support) include organic films such as polyethylene terephthalate (PET), biaxially oriented polypropylene (OPP), polyethylene, polyvinyl fluorate, and polyimide; films of copper, aluminum, and alloys of these metals; and films in which the surface of these organic films or metal films has been treated with a release agent.

[0047] The second support for the resin film is the same as the first support described above. Preferably, the first support and the second support are made of the same material. When the first support and the second support are made of the same material, the behavior during heat bonding becomes uniform on both sides of the FRP precursor, which can suppress the occurrence of increased residual stress and appearance defects such as wrinkles in the product due to differences in thermal shrinkage and dimensional change rates of the supports during heat bonding.

[0048] [FRP, Metal-Clad Laminate] One aspect of this embodiment is FRP as a cured product of an FRP precursor. The metal-clad laminate of this embodiment is a metal-clad laminate containing metal foil and the FRP of this embodiment. The FRP, which is a cured product of an FRP precursor, is obtained by C-stage (curing) an FRP precursor that is in a B-stage (semi-cured) state.

[0049] Specifically, a metal-clad laminate can be manufactured by laminating one or more (preferably 2 to 20) FRP precursors and arranging metal foil on one or both sides, preferably both sides. A substrate with an inner layer circuit may be sandwiched between the FRP precursors. Through this lamination process, the FRP precursors are cured (C-staged) to become FRP.

[0050] As the lamination conditions, known conditions used in the manufacture of metal-clad laminates used in printed circuit boards can be adopted. For example, conditions can be adopted in which lamination is performed using a multi-stage press, multi-stage vacuum press, continuous molding, autoclave molding machine, etc., at a temperature of 100 to 250°C, a pressure of 0.2 to 10 MPa, and a heating time of 0.1 to 5 hours.

[0051] The thickness of the metal foil is preferably 40 μm or less, more preferably 1 to 40 μm, even more preferably 5 to 40 μm, even more preferably 5 to 35 μm, particularly preferably 5 to 25 μm, and most preferably 5 to 17 μm.

[0052] From the viewpoint of conductivity, the metal of the metal foil is preferably copper, gold, silver, nickel, platinum, molybdenum, ruthenium, aluminum, tungsten, iron, titanium, chromium, or an alloy containing at least one of these metallic elements. Preferred alloys include copper-based alloys, aluminum-based alloys, and iron-based alloys. Examples of copper-based alloys include copper-nickel alloys. Examples of iron-based alloys include iron-nickel alloys (42 alloy). Among these, copper, nickel, and 42 alloy are more preferred as the metal, and copper is even more preferred from the viewpoint of availability and cost.

[0053] [Printed Wiring Board] The printed wiring board of this embodiment is a printed wiring board that includes FPR or metal-clad laminate of this embodiment. The printed wiring board of this embodiment can be manufactured, for example, by forming a wiring pattern on the laminate of this embodiment. Examples of known methods for forming the wiring pattern include the subtractive method, the fully additive method, the semi-additive process (SAP), or the modified semi-additive process (m-SAP).

[0054] [Semiconductor Package] The semiconductor package of this embodiment is a semiconductor package formed by mounting semiconductors on a printed circuit board of this embodiment. The semiconductor package of this embodiment can be manufactured by mounting semiconductor elements such as semiconductor chips and memory at predetermined positions on the printed circuit board of this embodiment and sealing the semiconductor elements with a sealing resin or the like.

[0055] Next, the present invention will be described in more detail with reference to the following examples, but these examples are not intended to limit the present invention.

[0056] Preparation Example 1 (Preparation of Resin Varnish) 100 parts by mass of phenol novolac type epoxy resin (N-660; manufactured by DIC Corporation) and 60 parts by mass of cresol novolac resin (KA-1165; manufactured by DIC Corporation) were mixed with 15 parts by mass of cyclohexane and 130 parts by mass of methyl ethyl ketone, and the mixture was stirred to dissolve. 180 parts by mass of aluminum hydroxide (CL-303; manufactured by Sumitomo Chemical Co., Ltd.) as an inorganic filler, 1 part by mass of a coupling agent (A-187; manufactured by Momentive Performance Materials Inc.), and 2.5 parts by mass of isocyanate macusimidazole (G8009L; manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as a curing accelerator were added, and the mixture was stirred to dissolve and disperse, obtaining a resin varnish with a solid content of 70% by mass.

[0057] Manufacturing Example 1 (Preparation of Resin Film A) A 580 mm wide PET film (S-10; manufactured by Toray Industries, Inc.) was used as a support. The resin varnish obtained in Preparation Example 1 was applied to the support with a coating width of 540 mm so that the thickness of the resin film after drying would be 10 to 20 μm. Then, it was dried at 130°C for 3 minutes to produce a support-attached resin film A.

[0058] Examples 1-4, Comparative Example 1 (Production of FRP Precursor) Next, using the apparatus shown in Figure 2, one resin film A with a support obtained above was placed on each side of the glass cloth shown in Table 1, with the resin film side facing the glass cloth side. The laminate in this state was sandwiched between heated and pressurized rolls, and the resin film was pressurized and impregnated into the glass cloth. After that, the obtained FRP precursor was cooled with a cooling roll and wound up with an FRP precursor winding device. The lamination pressure was 0.3 MPa, the pressurized roll temperature was 130°C, and the line speed was 1.0 m / min.

[0059] (Manufacturing of copper-clad laminates) After forming a laminate by stacking one FRP precursor obtained in each example on each side of a 0.2 mm thick copper-clad laminate, a 12 μm thick copper foil "3EC-M3-VLP-12" (manufactured by Mitsui Mining & Smelting Co., Ltd.) is placed on both sides of the laminate, and the process is carried out at a temperature of 190°C and a pressure of 25 kgf / cm². ２A 0.3 mm thick double-sided copper-clad laminate was fabricated by heating and pressurizing at 2.45 MPa for 90 minutes, and this was used as a substrate for evaluating laser processability. In addition, a 12 μm thick copper foil "3EC-M3-VLP-12" (manufactured by Mitsui Mining & Smelting Co., Ltd.) was placed on both sides of a laminate made by stacking two FRP precursors obtained in each example, and the temperature was set to 190°C and the pressure to 25 kgf / cm². ２ Double-sided copper-clad laminates with a thickness of 0.04 to 0.08 mm were fabricated by heating and pressurizing at 2.45 MPa for 90 minutes, and these were used as substrates for evaluating the rate of dimensional change. For each example, the laser processing accuracy and rate of dimensional change were evaluated using the following method.

[0060] (1. Laser processability) For the evaluation substrates for laser processability obtained in each example, CO ２ Using a laser processing machine (VIAMECHLC-2N252 / 2C (H18), manufactured by Via Mechanics Co., Ltd.), via holes (hereinafter sometimes simply referred to as "vias") were formed under the following conditions: mask diameter 4.4 mm, focus offset value 0.000, pulse width 10 μs, power 29 W, aperture 32, and number of shots 1. The vertical and horizontal diameters of the top of the vias on the obtained evaluation substrate (see Figure 3) were observed and measured using a scanning electron microscope (SEM). In addition, the vertical diameters of the top and bottom of the vias (both average values ​​for 10 arbitrary vias) were observed and measured using a scanning electron microscope (SEM). The target value for the ratio of the vertical diameter to the horizontal diameter (vertical diameter / horizontal diameter) of the top of the vias was 1.05 or less. Furthermore, the ratio of the vertical diameter at the top of the via to the vertical diameter at the bottom of the via (vertical diameter at the top of the via / vertical diameter at the bottom of the via) is a target value of 1.2 or less. The results are shown in Table 1.

[0061] (2. Dimensional Change Rate) For the evaluation substrates used to determine the dimensional change rate obtained in each example, holes with a diameter of 1.0 mm were drilled in the surface as shown in Figure 4. As shown in Figure 4, the distances between two points in the warp direction (1-3, 2-4) and the weft direction (1-2, 3-4) of the glass cloth were measured using an image measuring instrument "QV-A808P1L-D" (manufactured by Mitutoyo Corporation), and these measured distances were set as initial values. Subsequently, the outer layer copper foil was removed by immersion in a copper etching solution (chemical type: ammonium persulfate, temperature: 90°C, processing time: 5 minutes), and after rinsing with water and wiping off the water, the substrate was heated in a dryer at 80°C for 5 minutes. After cooling, the distances between two points in the warp direction (1-3, 2-4) and the weft direction (1-2, 3-4) were measured in the same manner as the initial value measurement method. The rate of change of each measurement distance relative to its initial value [(measured value - initial value) × 100 / initial value] was calculated (corresponding to "ET" in Figures 5-9). Next, the material was heated at 180°C for 1 hour and then allowed to cool naturally for 20 minutes. Here, the distances of two points each in the warp direction (1-3, 2-4) and the weft direction (1-2, 3-4) were measured again in the same manner as described above. The rate of change of each measurement distance relative to its initial value [(measured value - initial value) × 100 / initial value] was calculated (corresponding to "E1" in Figures 5-9). Finally, the material was heated again at 180°C for 1 hour and then allowed to cool naturally for 20 minutes. Then, the distances of two points each in the warp direction (1-3, 2-4) and the weft direction (1-2, 3-4) were measured again in the same manner as described above. The rate of change of each measurement distance relative to its initial value [(measured value - initial value) × 100 / initial value] was calculated (corresponding to "E2" in Figures 5-9). The results for Examples 1 to 4 and Comparative Example 1 are shown in Figures 5 to 8 and 9, respectively. White circles (〇) represent the dimensional change rate in the warp direction, and black circles (●) represent the dimensional change rate in the weft direction. In ET, E1, and E2, it is preferable that the width of the dimensional change rate (the width of the bars above and below the white and black circles in the figures) is small.

[0062]

[0063] In Examples 1 to 4, the ratio of the vertical diameter at the top of the via to the horizontal diameter at the top of the via (vertical diameter / horizontal diameter), and the ratio of the vertical diameter at the top of the via to the vertical diameter at the bottom of the via (vertical diameter at the top of the via / vertical diameter at the bottom of the via), are small, indicating excellent laser processability. In Comparative Example 1, the laser processability was inferior compared to Examples 1 to 4. Furthermore, in Examples 1 to 4, it can be seen from Figures 5 to 8 that the variation in the rate of dimensional change is suppressed. On the other hand, in Comparative Example 1, it can be seen from Figure 9 that the variation in the rate of dimensional change is large. It can also be seen that in Examples 1 to 4 (Figures 5 to 8), the rate of dimensional change itself is improved compared to Comparative Example 1 (Figure 9).

[0064] 1. FRP precursor manufacturing apparatus 2. Glass cloth dispensing apparatus 3. Resin film dispensing apparatus 4. Protective film peeling mechanism 5. Protective film winding apparatus 6. FRP precursor heating and pressurizing apparatus 7. FRP precursor pressurizing and cooling apparatus 8. FRP precursor winding apparatus 40. Glass cloth 40a. Surface of glass cloth 40b. Back of glass cloth 50. Resin film with protective film (multilayer film) 52. Protective film 54. Resin film 54a. Surface of resin film on the glass cloth side (glass cloth side film surface) 60. FRP precursor

Claims

1. An FRP precursor comprising glass cloth and a thermosetting resin composition or a semi-cured product of the thermosetting resin composition, wherein the glass cloth has a K (%) defined by the following formula of 30 or less. (In the formula, A represents the warp thread width (μm), B represents the weft thread width (μm), a represents the distance between warp threads (μm), and b represents the distance between weft threads (μm).) 2. In K, a = (25,000 - AX) / X and b = (25,000 - BY) / Y [where X is the warp density (threads / 25 mm) and Y is the weft density (threads / 25 mm). A, B, a, and b are as defined above.], the FRP precursor according to claim 1.

3. The FRP precursor according to claim 1, wherein the thickness of the glass cloth is 5 to 50 μm.

4. The FRP precursor according to claim 1, wherein A is 50 to 250 (μm) and B is 80 to 350 (μm).

5. The FRP precursor according to claim 1, wherein a is 100 to 200 μm and b is 30 to 140 μm.

6. The FRP precursor according to claim 1, wherein the content of the thermosetting resin composition or the semi-cured product of the thermosetting resin composition (solid content) is 60 to 90% by mass with respect to the total amount of the FRP precursor.

7. FRP, which is a cured product of the FRP precursor described in claim 1.

8. A metal-clad laminate comprising metal foil and the FRP described in claim 7.

9. A printed circuit board comprising the FRP described in claim 7 or the metal-clad laminate described in claim 8.

10. A semiconductor package comprising a printed circuit board according to claim 9 and a semiconductor element.

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