Laminate, metal-clad laminated plate, and wiring board

Abstract

One aspect of the present invention is a laminate comprising: a first insulating layer that contains a cured product (A) of a first resin composition; a second insulating layer that contains a cured product (B) of a second resin composition and that is laminated on a first main-surface side of the first insulating layer; and a third insulating layer that contains a cured product (C) of a third resin composition and that is laminated on the second main-surface side of the first insulating layer. The thickness of the first insulating layer is 10-300 μm, and the thickness of each of the second insulating layer and the third insulating layer is 8-50 μm. The tensile storage elastic modulus of the cured product (A) at 30°C is not less than 3.5 GPa, and the tensile storage elastic modulus of each of the cured product (B) and the cured product (C) at 30°C is equal to or less than 3 GPa.

Description

Laminate, metal-clad laminate, and wiring board

[0001] The present invention relates to a laminate, a metal-clad laminate, and a wiring board.

[0002] Electronic devices are becoming increasingly sophisticated, with increased functionality, higher performance, thinner design, and smaller size. Accordingly, mounting technologies for wiring boards mounted on electronic devices, such as higher integration, higher wiring density, and multi-layering, are rapidly advancing. Therefore, wiring boards, particularly those used as semiconductor package substrates, are required to minimize warpage that occurs during component mounting and package assembly, for example. Examples of materials for wiring boards that are intended to suppress such warpage include resin compositions described in Patent Documents 1 and 2.

[0003] Patent Documents 1 and 2 describe resin compositions containing an epoxy resin and a curing agent, in which the average linear thermal expansion coefficient of a cured product obtained by curing the resin composition under predetermined conditions divided by the crosslink density of the cured product satisfies a predetermined relationship. Patent Documents 1 and 2 disclose that resin compositions can be obtained that can give cured products with reduced warpage.

[0004] Examples of wiring boards used as semiconductor package substrates include multilayer wiring boards in which rewiring layers such as build-up layers are formed on wiring boards that serve as inner layer substrates to achieve multi-layering. When manufacturing wiring boards used as semiconductor package substrates, holes may be drilled in the insulating layer to achieve multi-layering. For this reason, the insulating layer provided on the wiring board is also required to have excellent processability so that such hole drilling can be performed appropriately.

[0005] JP 2021-161205 A JP 2021-161206 A

[0006] The present invention has been made in view of the above circumstances, and has an object to provide a laminate, a metal-clad laminate, and a wiring board that are suppressed in warping and have excellent processability.

[0007] One aspect of the present invention is a laminate comprising: a first insulating layer including a cured product (A) of a first resin composition; a second insulating layer including a cured product (B) of a second resin composition and laminated on a first main surface side of the first insulating layer; and a third insulating layer including a cured product (C) of a third resin composition and laminated on a second main surface side of the first insulating layer; wherein the thickness of the first insulating layer is 10 to 300 μm, the thicknesses of the second insulating layer and the third insulating layer are each 8 to 50 μm, the tensile storage modulus of the cured product (A) at 30° C. is 3.5 GPa or more, and the tensile storage moduli of the cured products (B) and (C) at 30° C. are each 3 GPa or less.

[0008] These and other objects, features, and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings.

[0009] Fig. 1 is a schematic cross-sectional view showing an example of a laminate according to an embodiment of the present invention. Fig. 2 is a schematic cross-sectional view showing another example of a laminate according to an embodiment of the present invention. Fig. 3 is a schematic cross-sectional view showing an example of a metal-clad laminate according to an embodiment of the present invention. Fig. 4 is a schematic cross-sectional view showing another example of a metal-clad laminate according to an embodiment of the present invention. Fig. 5 is a schematic cross-sectional view showing an example of a wiring board according to an embodiment of the present invention. Fig. 6 is a schematic cross-sectional view showing another example of a wiring board according to an embodiment of the present invention.

[0010] Semiconductor package substrates tend to become larger in size to accommodate the increasing functionality of electronic devices and to accommodate larger and larger semiconductor chips. Semiconductor package substrates also tend to become thinner. As semiconductor package substrates become larger and thinner, warping of semiconductor packages mounting semiconductor chips on the semiconductor package substrate becomes more likely, resulting in mounting defects. For this reason, even as semiconductor package substrates become larger and thinner, there is a demand for minimal warping during component mounting and package assembly. To reduce warping of semiconductor package substrates, it is conceivable to increase the elastic modulus and lower the coefficient of thermal expansion (CTE). For example, in the case of wiring boards, it is conceivable to provide an insulating layer with a higher elastic modulus and a lower coefficient of thermal expansion (CTE) as the insulating layer provided on the wiring board. Examples of materials for obtaining such insulating layers include resin compositions that have a low linear expansion coefficient and a high crosslink density, and can be cured to form a product. Since the cured product of such a resin composition can suppress warpage, it is believed that an insulating layer containing the cured product of the resin composition can suppress warpage. On the other hand, to improve the mounting reliability of a semiconductor package, it is necessary to improve not only reliability during mounting of a semiconductor chip on a semiconductor package substrate (primary mounting), but also reliability during mounting of the semiconductor package on a motherboard (secondary mounting). The present inventors have found that simply suppressing warpage of the semiconductor package substrate by increasing the elastic modulus and lowering the thermal expansion coefficient of the insulating layer provided on the semiconductor package substrate may improve reliability during primary mounting, but may result in increased distortion between the insulating layer and the motherboard on which the semiconductor package is mounted, potentially preventing reliability during secondary mounting. For this reason, the present inventors have found that wiring boards used as semiconductor package substrates are required to suppress warpage not only by increasing the elastic modulus and lowering the thermal expansion coefficient of the insulating layer provided thereon, but also by using other methods, such as using a laminate in which multiple insulating layers are stacked, to suppress warpage.

[0011] As described above, during the manufacturing process of a wiring board used as a semiconductor package substrate, holes may be drilled in the insulating layer to achieve multi-layering, etc. The present inventors have found that if the elastic modulus of the insulating layer is increased too much in order to improve reliability during the primary mounting process, the hole drilling process tends to be difficult to perform. For this reason, the present inventors have found that the insulating layer provided on the wiring board is also required to have excellent processability so that such hole drilling process can be performed appropriately.

[0012] The present inventors have conducted extensive research into the configuration of semiconductor package substrates to suppress warpage of semiconductor package substrates while preventing distortion between the semiconductor package and the motherboard, which could impair reliability during secondary mounting, and to improve processability to facilitate drilling and other processes. As a result, the present inventors have focused on using a laminate comprising multiple insulating layers as an insulating layer in a substrate used for a semiconductor package substrate. They have found that warpage of the laminate can be suppressed and processability can be improved by adjusting the thickness of each of the multiple insulating layers and the elastic modulus of the cured product of the resin composition contained in the insulating layer. That is, after extensive research, the present inventors have found that the above-mentioned object of providing a laminate with suppressed warpage and excellent processability can be achieved by the present invention described below.

[0013] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these.

[0014] [Laminate] As shown in Figures 1 and 2, a laminate 10 according to an embodiment of the present invention includes a first insulating layer 11, a second insulating layer 12 laminated on the first main surface 11a side of the first insulating layer 11, and a third insulating layer 13 laminated on the second main surface 11b side of the first insulating layer 11. The thickness of the first insulating layer 11 is 10 to 300 µm, and the thicknesses of the second insulating layer 12 and the third insulating layer 13 are each 8 to 50 µm. The first insulating layer 11 includes a cured product (A) of a first resin composition, and the tensile storage modulus of the cured product (A) at 30°C is 3.5 GPa or more. The second insulating layer 12 and the third insulating layer 13 include a cured product (B) of a second resin composition and a cured product (C) of a third resin composition, respectively, and the tensile storage modulus of the cured products (B) and (C) at 30°C is 3 GPa or less. The laminate 10 can suppress warpage of the laminate and improve processability. That is, in a laminate such as the laminate 10, in which the second insulating layer 12 and the third insulating layer 13 are laminated on the first insulating layer 11, by setting the thickness of each layer and the modulus of elasticity of the cured product contained in each layer within the above range, warpage of the laminate can be suppressed and processability can be improved. Therefore, warpage can be suppressed not only by increasing the modulus of elasticity or lowering the thermal expansion coefficient, but also by adjusting the thickness of each layer and the modulus of elasticity of the cured product contained in each layer, and excellent processability can be achieved that allows for suitable drilling. Note that FIG. 1 is a schematic cross-sectional view showing an example of a laminate (the laminate 10) according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view showing another example of a laminate (the laminate 20) according to an embodiment of the present invention.

[0015] The first insulating layer 11 may be the first insulating layer 11 alone, as shown in Fig. 1 , or other layers, wiring, etc. may be formed on the first insulating layer 11. Specifically, the first insulating layer 11 may have wiring 111 formed thereon to form a wiring board 112, as shown in Fig. 2 . That is, a laminate 20 according to another embodiment of the present invention is a laminate in which a wiring board 112 having the wiring 111 on the first insulating layer 11 is used. The laminate 20 may be a laminate that is similar to the laminate 10 except that the wiring 111 is provided on the first insulating layer 11.

[0016] As described above, the first insulating layer 11 includes the cured product (A). The first insulating layer 11 preferably further includes a fibrous base material (including the cured product (A) and the fibrous base material) to enhance the warpage suppression effect of the first insulating layer 11. The first insulating layer 11 is preferably a cured prepreg. Examples of the prepreg include a prepreg including the first resin composition or a semi-cured product of the first resin composition and the fibrous base material. Forming the first insulating layer 11 by curing a prepreg including the first resin composition or a semi-cured product of the first resin composition is preferred because it allows for a first insulating layer 11 with enhanced warpage suppression effect to be obtained. The semi-cured product refers to a resin composition that has been partially cured to the extent that it can be further cured. The semi-cured product refers to a resin composition that has been semi-cured (B-staged). For example, when a resin composition is heated, its viscosity initially gradually decreases, then begins to harden, and its viscosity gradually increases. In such a case, the semi-cured state may be a state between when the viscosity starts to increase and when the composition is completely cured. The first resin composition and the fibrous base material will be described later.

[0017] As described above, the second insulating layer 12 is laminated on the first main surface 11a of the first insulating layer 11. Specifically, as shown in FIGS. 1 and 2, it is preferably laminated in contact with the first main surface 11a of the first insulating layer 11. Furthermore, the second insulating layer 12 preferably contains the cured product (B) and, unlike the first insulating layer 11, does not contain a fibrous base material. Furthermore, the second insulating layer 12 is preferably a cured film. Examples of the film include a film containing the second resin composition or a semi-cured product of the second resin composition. That is, forming the second insulating layer 12 by curing a film containing the second resin composition or a semi-cured product of the second resin composition is preferable because it allows for the second insulating layer 12 to be suitably obtained, exhibiting the effects of suppressing warpage and improving processability due to the presence of the second insulating layer 12. Furthermore, the third insulating layer 13 is similar to the second insulating layer 12, except that the third resin composition is used instead of the second resin composition. The second insulating layer 12 and the third insulating layer 13 may be layers having the same thickness, modulus of elasticity, composition, etc., or may be layers having different thicknesses, moduli of elasticity, composition, etc., as long as they each have a thickness of 8 to 50 μm and the cured products (A) and (B) contained therein have a tensile storage modulus of 3.5 GPa or more at 30° C. The second resin composition and the third resin composition will be described later.

[0018] The thickness of the first insulating layer 11 is 10 to 300 μm, preferably 10 to 250 μm, and more preferably 10 to 200 μm. The thicknesses of the second insulating layer 12 and the third insulating layer 13 are each 8 to 50 μm, preferably 8 to 40 μm, and more preferably 8 to 35 μm. The thicknesses of the second insulating layer 12 and the third insulating layer 13 may be the same or different, as long as they are each 8 to 50 μm. The thicknesses of the second insulating layer 12 and the third insulating layer 13 are preferably thinner than the thickness of the first insulating layer 11. Specifically, the ratios of the thicknesses of the second insulating layer 12 and the third insulating layer 13 to the thickness of the first insulating layer 11 [(thickness of the second insulating layer 12) / (thickness of the first insulating layer 11) and (thickness of the third insulating layer 13) / (thickness of the first insulating layer 11)] are preferably 1 or less, and more preferably 0.03 to 0.85. Furthermore, the thicknesses of the second insulating layer 12 and the third insulating layer 13 are each thinner than the thickness of the first insulating layer 11, and the differences from the thickness of the first insulating layer 11 [(thickness of the first insulating layer 11) - (thickness of the second insulating layer 12) and (thickness of the first insulating layer 11) - (thickness of the third insulating layer 13)] are preferably 10 to 290 μm, and more preferably 15 to 285 μm. If the first insulating layer 11 is too thin, warpage tends to be insufficiently suppressed. This is thought to be because the first insulating layer 11 is relatively thin compared to the second insulating layer 12 and the third insulating layer 13, and the warpage suppression effect of the first insulating layer 11 containing a cured product with a relatively high elastic modulus is reduced. Furthermore, if the first insulating layer 11 is too thick, even if warpage can be suppressed, this suppression is achieved by increasing the elastic modulus and lowering the thermal expansion coefficient of the insulating layer provided in the semiconductor package substrate, and it tends not to suppress warpage while suppressing deterioration of secondary mountability. Furthermore, if the second insulating layer 12 and the third insulating layer 13 are too thin, processability cannot be sufficiently improved, and drilling and other processes tend to be difficult to perform. Furthermore, if not only the second insulating layer 12 and the third insulating layer 13 but also the first insulating layer 11 are too thin, warpage tends to be insufficiently suppressed.This is thought to be because the first insulating layer 11 cannot sufficiently suppress warpage, and even if the second insulating layer 12 and the third insulating layer 13 are provided, the warpage suppression effect of these layers cannot be fully exerted. Note that, as with the case where the first insulating layer 11 is too thick, if the second insulating layer 12 and the third insulating layer 13 are thick, the elastic modulus of the insulating layer provided in the semiconductor package substrate is increased and the thermal expansion coefficient is reduced, thereby suppressing warpage of the semiconductor package substrate, but it tends not to suppress warpage while suppressing deterioration of secondary mountability. Furthermore, if the second insulating layer 12 and the third insulating layer 13 are too thick, warpage tends to be insufficiently suppressed. This is thought to be because the first insulating layer 11 is relatively thin, reducing the warpage suppression effect of the first insulating layer 11, which contains a cured product with a relatively high elastic modulus. From the above, if the thicknesses of the first insulating layer 11, the second insulating layer 12, and the third insulating layer 13 are each within the above ranges, warping is further suppressed and a laminate with excellent processability can be obtained.

[0019] The tensile storage modulus of the cured product (A) at 30°C ("tensile storage modulus at 30°C" may also be simply referred to as "tensile storage modulus") is 3.5 GPa or more, preferably 4.5 to 10 GPa, and more preferably 6 to 10 GPa. The tensile storage modulus of the cured product (B) and the cured product (C) is each 3 GPa or less, preferably 0.5 to 3 GPa, and more preferably 0.5 to 2 GPa. The tensile storage modulus of the cured product (B) and the tensile storage modulus of the cured product (C) may be the same or different, so long as they are each 3 GPa or less. The ratios of the tensile storage moduli of the cured product (B) and the cured product (C) to the tensile storage modulus of the cured product (A) [(tensile storage modulus of the cured product (B)) / ((tensile storage modulus of the cured product (A)) and ((tensile storage modulus of the cured product (C)) / ((tensile storage modulus of the cured product (A))]] are preferably 0.05 to 0.7 times, and more preferably 0.05 to 0.45 times. The differences of the tensile storage moduli of the cured product (B) and the cured product (C) from the tensile storage modulus of the cured product (A) [(tensile storage modulus of the cured product (A)) - (tensile storage modulus of the cured product (B)] and ((tensile storage modulus of the cured product (A)) - (tensile storage modulus of the cured product (C)]] are preferably 1.5 to 9.5 GPa, and more preferably 2.5 to 9.5 GPa, respectively. If the tensile storage modulus of the cured product (A) is too low, warpage tends to be insufficiently suppressed. This is thought to be because if the tensile storage modulus of the cured product (A) is too low, the elastic modulus of the first insulating layer 11 also becomes low, thereby reducing the warpage suppression effect of the first insulating layer 11. Furthermore, if the tensile storage modulus of the cured products (B) and (C) is too high, processability cannot be sufficiently improved, and drilling and other processes tend to be difficult to perform. This is thought to be because if the tensile storage modulus of the cured products (B) and (C) is too high, the elastic modulus of the second insulating layer 12 and the third insulating layer 13 also becomes high. From the above, when the tensile storage modulus of the cured products (A), (B), and (C) are each within the above range, warpage is further suppressed and a laminate with excellent processability can be obtained.The tensile storage modulus here refers to the storage modulus when the object to be measured is at 30°C, and examples thereof include values ​​measured at 30°C by the tensile method of dynamic mechanical analysis (DMA).

[0020] The thermal expansion coefficient (T1) of the cured product (A) at 50 to 100°C ("thermal expansion coefficient at 50 to 100°C" may also be simply referred to as "thermal expansion coefficient") is preferably 35 ppm / °C or less, more preferably 5 to 30 ppm / °C, and even more preferably 5 to 25 ppm / °C. The thermal expansion coefficient (T2) of the cured product (B) and the thermal expansion coefficient (T3) of the cured product (C) are each preferably 100 ppm / °C or less, more preferably 10 to 80 ppm / °C, and even more preferably 10 to 60 ppm / °C. The thermal expansion coefficient (T2) of the cured product (B) and the thermal expansion coefficient (T3) of the cured product (C) may be the same or different. Furthermore, the thermal expansion coefficient (T1) of the cured product (A) is preferably smaller than both the thermal expansion coefficient (T2) of the cured product (B) and the thermal expansion coefficient (T3) of the cured product (C). Specifically, the ratio (T1 / T2) of the thermal expansion coefficient (T1) of the cured product (A) to the thermal expansion coefficient (T2) of the cured product (B), and the ratio (T1 / T3) of the thermal expansion coefficient (T1) of the cured product (A) to the thermal expansion coefficient (T3) of the cured product (C) are both preferably 1 or less, and more preferably 0.05 to 0.9. The difference (T2-T1) between the thermal expansion coefficient (T2) of the cured product (B) and the thermal expansion coefficient (T3) of the cured product (C) in the thermal expansion coefficient (T1) of the cured product (A) is preferably 5 to 95 ppm / °C, more preferably 10 to 75 ppm / °C. If the thermal expansion coefficient (T1) of the cured product (A) is too high, warpage tends to be insufficiently suppressed. This is thought to be because if the thermal expansion coefficient (T1) of the cured product (A) is too high, the thermal expansion coefficient of the first insulating layer 11 also increases, thereby reducing the warpage suppression effect of the first insulating layer 11. Furthermore, if the thermal expansion coefficient (T2) of the cured product (B) and the thermal expansion coefficient (T3) of the cured product (C) are too high, warpage tends to be insufficiently suppressed.This is thought to be because if the thermal expansion coefficients (T2) of the cured product (B) and (T3) of the cured product (C) are too high, the thermal expansion coefficients of the second insulating layer 12 and the third insulating layer 13 also become high, and even if the second insulating layer 12 and the third insulating layer 13 are provided, the warpage suppression effect of these layers cannot be fully exerted. From the above, it can be seen that a laminate with better warpage suppression can be obtained if the thermal expansion coefficients of the cured products (A), (B), and (C) are each within the above ranges. The thermal expansion coefficient here refers to the thermal expansion coefficient at 50 to 100°C, and examples include the average thermal expansion coefficient at 50 to 100°C calculated from the thermal expansion coefficient measured by changing the temperature using the TMA (thermo-mechanical analysis) method.

[0021] The dielectric loss tangents of the second insulating layer 12 and the third insulating layer 13 are each preferably 0.004 or less, more preferably 0.0035 or less, and even more preferably 0.003 or less. Smaller dielectric loss tangents of the second insulating layer 12 and the third insulating layer 13 are preferable, but in practice, the limit is often around 0.0005. Therefore, the dielectric loss tangents of the second insulating layer 12 and the third insulating layer 13 are each preferably 0.0005 to 0.004, more preferably 0.0005 to 0.0035, and even more preferably 0.0005 to 0.003.

[0022] The relative dielectric constants of the second insulating layer 12 and the third insulating layer 13 are preferably 3 or less, more preferably 2.8 or less, and even more preferably 2.6 or less. The smaller the relative dielectric constants of the second insulating layer 12 and the third insulating layer 13, the more preferable, but in practice, the limit is often about 2. For this reason, the relative dielectric constants of the second insulating layer 12 and the third insulating layer 13 are preferably 2 to 3, more preferably 2 to 2.8, and even more preferably 2 to 2.6.

[0023] If the dielectric tangent and relative dielectric constant of the second insulating layer 12 and the third insulating layer 13 stacked on the first insulating layer 11 are within the above ranges, the signal transmission speed can be increased and loss during signal transmission can be reduced in a wiring board including the laminate.

[0024] The dielectric constant and dielectric loss tangent here are the dielectric constant and dielectric loss tangent of each layer at a frequency of 10 GHz, and examples thereof include the dielectric constant and dielectric loss tangent of each layer at a frequency of 10 GHz measured by a cavity resonator perturbation method.

[0025] The dielectric loss tangent and relative dielectric constant of the first insulating layer 11 have less effect on the signal transmission speed and loss during signal transmission than those of the second insulating layer 12 and the third insulating layer 13. For example, the dielectric loss tangent of the first insulating layer 11 is preferably 0.02 or less, more preferably 0.015 or less. The relative dielectric constant of the first insulating layer 11 is preferably 5 or less, more preferably 4.8 or less. Similarly to the second insulating layer 12, the dielectric loss tangent and relative dielectric constant of the first insulating layer 11 are also preferably small. However, the limits are approximately 0.0005 and 2, respectively, which are the lower limit values ​​of the dielectric loss tangent and relative dielectric constant, respectively.

[0026] (Resin Composition) The first resin composition, the second resin composition, and the third resin composition (each resin composition) are not particularly limited as long as the cured product of each resin composition satisfies the above-mentioned configuration. Preferably, each resin composition contains an inorganic filler. Since the first insulating layer 11, the second insulating layer 12, and the third insulating layer (each insulating layer) each contain a cured product of the respective resin composition, each resin composition also contains a curable resin. Therefore, it is preferable that each resin composition contains a curable resin and an inorganic filler.

[0027] In the second resin composition and the third resin composition, the content of the inorganic filler is preferably 25 to 250 mass% and more preferably 25 to 200 mass% relative to the total amount of the second resin composition and the third resin composition excluding the inorganic filler. When the content of the inorganic filler in the second resin composition and the third resin composition is within the above range, a laminate with suppressed warpage can be suitably obtained while exhibiting excellent processability that allows for suitable drilling. In the first resin composition, the content of the inorganic filler is preferably 50 to 250 mass% and more preferably 50 to 200 mass% relative to the total amount of the first resin composition excluding the inorganic filler. When the content of the inorganic filler in the first resin composition is within the above range, a laminate with suppressed warpage can be suitably obtained. This is thought to be due to the fact that the obtained first insulating layer 11 is a layer that can suitably exhibit the warpage suppression effect of the first insulating layer 11. In the second resin composition and the third resin composition, the content of the curable resin is preferably 10 to 90 mass% relative to the total amount of the second resin composition and the third resin composition excluding the inorganic filler. In the first resin composition, the content of the curable resin is preferably 10 to 90 mass% relative to the total amount of the first resin composition excluding the inorganic filler.

[0028] As described above, each of the resin compositions includes a curable resin and may further include a curing agent. That is, each of the resin compositions preferably includes the curable resin, the curing agent, and an inorganic filler. The curable resin is not particularly limited, and examples thereof include a polyphenylene ether compound. That is, each of the resin compositions preferably includes the polyphenylene ether compound, the curing agent, and an inorganic filler. Furthermore, when the second resin composition and the third resin composition contain the curing agent, the content of the curing agent is preferably 5 to 70 mass% relative to the total amount of each of the second resin composition and the third resin composition excluding the inorganic filler. Furthermore, when the first resin composition contains the curing agent, the content of the curing agent is preferably 5 to 70 mass% relative to the total amount of the first resin composition excluding the inorganic filler.

[0029] Polyphenylene Ether Compounds Examples of the polyphenylene ether compounds include polyphenylene ether compounds having a reactive carbon-carbon unsaturated bond, and more specifically, polyphenylene ether compounds having at least one of a group represented by the following formula (1) and a group represented by the following formula (2) in the molecule. More specifically, the polyphenylene ether compounds include modified polyphenylene ether compounds terminally modified with at least one of a group represented by the formula (1) and a group represented by the formula (2).

[0030] In formula (1), p represents 0 to 10, Z represents an arylene group, and R １ ~R ３ each independently represents a hydrogen atom or an alkyl group.

[0031] In formula (2), R ４ represents a hydrogen atom or an alkyl group.

[0032] In the formula (1), p represents 0 to 10. Z represents an arylene group. １ ~R ３ are independent of each other. That is, R １ ~R３ may be the same group or different groups. １ ~R ３ represents a hydrogen atom or an alkyl group.

[0033] In the formula (1), when p is 0, this indicates that Z is directly bonded to the end of the polyphenylene ether.

[0034] The arylene group is not particularly limited. Examples of the arylene group include monocyclic aromatic groups such as a phenylene group, and polycyclic aromatic groups in which the aromatic ring is not monocyclic but is polycyclic, such as a naphthalene ring. The arylene group also includes derivatives in which a hydrogen atom bonded to the aromatic ring is substituted with a functional group such as an alkenyl group, an alkynyl group, a formyl group, an alkylcarbonyl group, an alkenylcarbonyl group, or an alkynylcarbonyl group. The alkyl group is not particularly limited, and is preferably an alkyl group having 1 to 18 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms. Specific examples include a methyl group, an ethyl group, a propyl group, a hexyl group, and a decyl group.

[0035] In the formula (2), R ４ represents a hydrogen atom or an alkyl group. The alkyl group is not particularly limited, and is preferably, for example, an alkyl group having 1 to 18 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms. Specific examples include a methyl group, an ethyl group, a propyl group, a hexyl group, and a decyl group.

[0036] Preferred specific examples of the group represented by formula (1) include a vinylbenzyl group (ethenylbenzyl group) and a vinylphenyl group represented by formula (3) below. Examples of the vinylbenzyl group include an o-ethenylbenzyl group, a p-ethenylbenzyl group, and an m-ethenylbenzyl group. Examples of the group represented by formula (2) include an acryloyl group and a methacryloyl group.

[0037]

[0038] The polyphenylene ether compound has at least one of the group represented by formula (1) and the group represented by formula (2) in the molecule, and may have one type or two or more types of these groups. The polyphenylene ether compound may have, for example, any one of an o-ethenylbenzyl group, a p-ethenylbenzyl group, and an m-ethenylbenzyl group, or may have two or three types of these groups.

[0039] The polyphenylene ether compound has a polyphenylene ether chain in the molecule, and preferably has, for example, a repeating unit represented by the following formula (4) in the molecule.

[0040] In formula (4), t represents 1 to 50. ５ ~R ８ are independent of each other. That is, R ５ ~R ８ may be the same group or different groups. ５ ~R ８ represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a formyl group, an alkylcarbonyl group, an alkenylcarbonyl group, or an alkynylcarbonyl group, among which a hydrogen atom and an alkyl group are preferred.

[0041] R ５ ~R ８ Specific examples of the functional groups mentioned in the above include the following:

[0042] The alkyl group is not particularly limited, but is preferably an alkyl group having 1 to 18 carbon atoms, and more preferably an alkyl group having 1 to 10 carbon atoms. Specific examples include a methyl group, an ethyl group, a propyl group, a hexyl group, and a decyl group.

[0043] The alkenyl group is not particularly limited, but is preferably an alkenyl group having 2 to 18 carbon atoms, and more preferably an alkenyl group having 2 to 10 carbon atoms. Specific examples include a vinyl group, an allyl group, and a 3-butenyl group.

[0044] The alkynyl group is not particularly limited, but is preferably an alkynyl group having 2 to 18 carbon atoms, and more preferably an alkynyl group having 2 to 10 carbon atoms. Specific examples include an ethynyl group and a prop-2-yn-1-yl group (propargyl group).

[0045] The alkylcarbonyl group is not particularly limited as long as it is a carbonyl group substituted with an alkyl group, but for example, an alkylcarbonyl group having 2 to 18 carbon atoms is preferred, and an alkylcarbonyl group having 2 to 10 carbon atoms is more preferred. Specific examples include an acetyl group, a propionyl group, a butyryl group, an isobutyryl group, a pivaloyl group, a hexanoyl group, an octanoyl group, and a cyclohexylcarbonyl group.

[0046] The alkenylcarbonyl group is not particularly limited as long as it is a carbonyl group substituted with an alkenyl group, but for example, an alkenylcarbonyl group having 3 to 18 carbon atoms is preferred, and an alkenylcarbonyl group having 3 to 10 carbon atoms is more preferred. Specific examples include an acryloyl group, a methacryloyl group, and a crotonoyl group.

[0047] The alkynylcarbonyl group is not particularly limited as long as it is a carbonyl group substituted with an alkynyl group, but for example, an alkynylcarbonyl group having 3 to 18 carbon atoms is preferred, and an alkynylcarbonyl group having 3 to 10 carbon atoms is more preferred. Specific examples include a propioloyl group.

[0048] The weight-average molecular weight (Mw) of the polyphenylene ether compound is not particularly limited. Specifically, it is preferably 500 to 5,000, more preferably 800 to 4,000, and even more preferably 1,000 to 3,000. The weight-average molecular weight may be measured by a general molecular weight measurement method, specifically, a value measured using gel permeation chromatography (GPC), etc. Furthermore, when the polyphenylene ether compound has a repeating unit represented by the formula (4) in the molecule, t is preferably a value such that the weight-average molecular weight of the polyphenylene ether compound falls within this range. Specifically, t is preferably 1 to 50.

[0049] When the weight-average molecular weight of the polyphenylene ether compound is within this range, the compound has the excellent low dielectric properties of polyphenylene ether, and the cured product not only has excellent heat resistance but also has excellent moldability. This is believed to be due to the following reasons. When the weight-average molecular weight of a typical polyphenylene ether is within this range, the compound has a relatively low molecular weight, which tends to reduce the heat resistance of the cured product. In this regard, the polyphenylene ether compound according to this embodiment has at least one of the group represented by formula (1) and the group represented by formula (2) in its molecule, which is believed to result in a cured product with sufficiently high heat resistance. Furthermore, when the weight-average molecular weight of the polyphenylene ether compound is within this range, the compound has a relatively low molecular weight, which is believed to result in excellent moldability. Therefore, it is believed that such a polyphenylene ether compound not only has excellent heat resistance but also has excellent moldability.

[0050] The average number (number of terminal functional groups) of at least one of the groups represented by formula (1) and the group represented by formula (2) (substituents) per molecule of the polyphenylene ether compound is not particularly limited. Specifically, the number of terminal functional groups is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1.5 to 3. If the number of terminal functional groups is too small, it tends to be difficult to obtain a cured product with sufficient heat resistance. Furthermore, if the number of terminal functional groups is too large, the reactivity becomes too high, which may result in problems such as reduced shelf life and reduced fluidity of the resin composition. In other words, when such a polyphenylene ether compound is used, there is a risk of moldability problems, such as poor molding, such as the generation of voids during multilayer molding, making it difficult to obtain a highly reliable printed wiring board, due to insufficient fluidity.

[0051] The number of terminal functional groups of a polyphenylene ether compound can be exemplified by a numerical value representing the average number of the substituents per molecule of all polyphenylene ether compounds present in 1 mole of the polyphenylene ether compound. The number of terminal functional groups can be measured, for example, by measuring the number of hydroxyl groups remaining in the obtained polyphenylene ether compound and calculating the difference from the number of hydroxyl groups in the polyphenylene ether before it has the substituents (before modification). This difference from the number of hydroxyl groups in the polyphenylene ether before modification is the number of terminal functional groups. The number of hydroxyl groups remaining in the polyphenylene ether compound can be measured by adding a quaternary ammonium salt (tetraethylammonium hydroxide) that associates with hydroxyl groups to a solution of the polyphenylene ether compound and measuring the UV absorbance of the resulting mixed solution.

[0052] The intrinsic viscosity of the polyphenylene ether compound is not particularly limited. Specifically, it is preferably 0.03 to 0.12 dl / g, more preferably 0.04 to 0.11 dl / g, and even more preferably 0.06 to 0.095 dl / g. If the intrinsic viscosity is too low, the molecular weight tends to be low, and it tends to be difficult to achieve low dielectric properties such as a low dielectric constant and a low dielectric loss tangent. On the other hand, if the intrinsic viscosity is too high, the viscosity tends to be high, sufficient fluidity cannot be achieved, and the moldability of the cured product tends to be reduced. Therefore, if the intrinsic viscosity of the polyphenylene ether compound is within the above range, excellent heat resistance and moldability of the cured product can be achieved.

[0053] The intrinsic viscosity here is the intrinsic viscosity measured in methylene chloride at 25° C., and more specifically, it is the value measured, for example, with a viscometer using a 0.18 g / 45 ml methylene chloride solution (liquid temperature: 25° C.). Examples of such viscometers include the AVS500 Visco System manufactured by Schott.

[0054] Examples of the polyphenylene ether compound include a polyphenylene ether compound represented by the following formula (5) and a polyphenylene ether compound represented by the following formula (6). As the polyphenylene ether compound, these polyphenylene ether compounds may be used alone, or these two types of polyphenylene ether compounds may be used in combination.

[0055]

[0056] In formula (5) and formula (6), R ９ ~R １６ and R １７ ~R ２４ each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a formyl group, an alkylcarbonyl group, an alkenylcarbonyl group, or an alkynylcarbonyl group. １ and X ２each independently represents a group represented by the above formula (1) or a group represented by the above formula (2). A and B represent repeating units represented by the following formula (7) and formula (8), respectively. In addition, in formula (6), Y represents a linear, branched, or cyclic hydrocarbon having 20 or less carbon atoms.

[0057]

[0058] In formula (7) and formula (8), m and n each represent an integer of 0 to 20. ２５ ~R ２８ and R ２９ ~R ３２ each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a formyl group, an alkylcarbonyl group, an alkenylcarbonyl group, or an alkynylcarbonyl group.

[0059] The polyphenylene ether compound represented by the formula (5) and the polyphenylene ether compound represented by the formula (6) are not particularly limited as long as they satisfy the above-mentioned constitution. Specifically, in the formulas (5) and (6), R ９ ~R １６ and R １７ ~R ２４ As described above, each of R is independent. ９ ~R １６ and R １７ ~R ２４ may be the same group or different groups. ９ ~R １６ and R １７ ~R ２４ represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a formyl group, an alkylcarbonyl group, an alkenylcarbonyl group, or an alkynylcarbonyl group, among which a hydrogen atom and an alkyl group are preferred.

[0060] In formula (7) and formula (8), m and n each preferably represent a value of 0 to 20, as described above. Furthermore, it is preferable that m and n represent a numerical value such that the sum of m and n is 1 to 30. Therefore, it is more preferable that m represents a value of 0 to 20, n represents a value of 0 to 20, and the sum of m and n represents a value of 1 to 30. Furthermore, R ２５ ~R ２８ and R ２９ ~R ３２ are independent of each other. That is, R ２５ ~R ２８ and R ２９ ~R ３２ may be the same group or different groups. ２５ ~R ２８ and R ２９ ~R ３２ represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a formyl group, an alkylcarbonyl group, an alkenylcarbonyl group, or an alkynylcarbonyl group, among which a hydrogen atom and an alkyl group are preferred.

[0061] R ９ ~R ３２ is R in the above formula (4). ５ ~R ８ is the same as

[0062] In the formula (6), as described above, Y is a linear, branched, or cyclic hydrocarbon having 20 or less carbon atoms. Examples of Y include a group represented by the following formula (9).

[0063] In the formula (9), R ３３ and R ３４ are each independently a hydrogen atom or an alkyl group. Examples of the alkyl group include a methyl group. Examples of the group represented by formula (9) include a methylene group, a methylmethylene group, and a dimethylmethylene group, and among these, a dimethylmethylene group is preferred.

[0064] In the formula (5) and the formula (6), X １ and X ２are each independently a group represented by the above formula (1) or a group represented by the above formula (2). In the polyphenylene ether compound represented by the above formula (5) and the polyphenylene ether compound represented by the above formula (6), X １ and X ２ may be the same group or different groups.

[0065] More specific examples of the polyphenylene ether compound represented by the formula (5) include polyphenylene ether compounds represented by the following formula (10).

[0066] More specific examples of the polyphenylene ether compound represented by the formula (6) include a polyphenylene ether compound represented by the following formula (11) and a polyphenylene ether compound represented by the following formula (12).

[0067]

[0068] In the above formulas (10) to (12), m and n are the same as m and n in the above formulas (7) and (8). １ ~R ３ , p and Z are R in the above formula (1). １ ~R ３ , p and Z. In the formulas (11) and (12), Y is the same as Y in the formula (6). In the formula (12), R ４ is R in the above formula (2). １ is the same as

[0069] Curing Agent The curing agent is a curing agent capable of reacting with the polyphenylene ether compound to cure a resin composition containing the polyphenylene ether compound. The curing agent is not particularly limited as long as it is a curing agent capable of curing a resin composition containing the polyphenylene ether compound, other than the polybutadiene compound and styrene-based block copolymer having an epoxy group in the molecule, as described below. Examples of the curing agent include styrene, styrene derivatives, compounds having an acryloyl group in the molecule, compounds having a methacryloyl group in the molecule, compounds having a vinyl group in the molecule, compounds having an allyl group in the molecule, compounds having an acenaphthylene structure in the molecule, compounds having a maleimide group in the molecule, and isocyanurate compounds having an isocyanurate group in the molecule.

[0070] Examples of the styrene derivatives include bromostyrene and dibromostyrene.

[0071] The compound having an acryloyl group in the molecule is an acrylate compound. Examples of the acrylate compound include monofunctional acrylate compounds having one acryloyl group in the molecule and polyfunctional acrylate compounds having two or more acryloyl groups in the molecule. Examples of the monofunctional acrylate compound include methyl acrylate, ethyl acrylate, propyl acrylate, and butyl acrylate. Examples of the polyfunctional acrylate compound include diacrylate compounds such as tricyclodecane dimethanol diacrylate.

[0072] The compound having a methacryloyl group in the molecule is a methacrylate compound. Examples of the methacrylate compound include monofunctional methacrylate compounds having one methacryloyl group in the molecule and polyfunctional methacrylate compounds having two or more methacryloyl groups in the molecule. Examples of the monofunctional methacrylate compound include methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate. Examples of the polyfunctional methacrylate compound include dimethacrylate compounds such as tricyclodecane dimethanol dimethacrylate, and trimethacrylate compounds such as trimethylolpropane trimethacrylate.

[0073] The compound having a vinyl group in the molecule is a vinyl compound. Examples of the vinyl compound include a monofunctional vinyl compound (monovinyl compound) having one vinyl group in the molecule, and a polyfunctional vinyl compound having two or more vinyl groups in the molecule. Examples of the polyfunctional vinyl compound include divinylbenzene and polybutadiene (polybutadiene oligomer, etc.). Examples of the polybutadiene oligomer include B1000 manufactured by Nippon Soda Co., Ltd.

[0074] The compound having an allyl group in the molecule is an allyl compound. Examples of the allyl compound include monofunctional allyl compounds having one allyl group in the molecule and polyfunctional allyl compounds having two or more allyl groups in the molecule. Examples of the polyfunctional allyl compound include triallyl isocyanurate compounds such as triallyl isocyanurate (TAIC), diallyl bisphenol compounds, and diallyl phthalate (DAP).

[0075] The compound having an acenaphthylene structure in the molecule is an acenaphthylene compound. Examples of the acenaphthylene compound include acenaphthylene, alkylacenaphthylenes, halogenated acenaphthylenes, and phenylacenaphthylenes. Examples of the alkylacenaphthylenes include 1-methylacenaphthylene, 3-methylacenaphthylene, 4-methylacenaphthylene, 5-methylacenaphthylene, 1-ethylacenaphthylene, 3-ethylacenaphthylene, 4-ethylacenaphthylene, and 5-ethylacenaphthylene. Examples of the halogenated acenaphthylenes include 1-chloroacenaphthylene, 3-chloroacenaphthylene, 4-chloroacenaphthylene, 5-chloroacenaphthylene, 1-bromoacenaphthylene, 3-bromoacenaphthylene, 4-bromoacenaphthylene, and 5-bromoacenaphthylene. Examples of the phenylacenaphthylenes include 1-phenylacenaphthylene, 3-phenylacenaphthylene, 4-phenylacenaphthylene, and 5-phenylacenaphthylene. The acenaphthylene compound may be a monofunctional acenaphthylene compound having one acenaphthylene structure in the molecule, as described above, or a polyfunctional acenaphthylene compound having two or more acenaphthylene structures in the molecule.

[0076] The compound having a maleimide group in the molecule is a maleimide compound. Examples of the maleimide compound include a monofunctional maleimide compound having one maleimide group in the molecule, a polyfunctional maleimide compound having two or more maleimide groups in the molecule, and a modified maleimide compound. Examples of the modified maleimide compound include a modified maleimide compound in which a portion of the molecule is modified with an amine compound, a modified maleimide compound in which a portion of the molecule is modified with a silicone compound, and a modified maleimide compound in which a portion of the molecule is modified with an amine compound and a silicone compound.

[0077] The compound having an isocyanurate group in the molecule is an isocyanurate compound. Examples of the isocyanurate compound include compounds further having an alkenyl group in the molecule (alkenyl isocyanurate compounds), such as triallyl isocyanurate (TAIC).

[0078] Among the above, the curing agent preferably contains, for example, an allyl compound having an allyl group in the molecule. As the allyl compound, an allyl isocyanurate compound having two or more allyl groups in the molecule is preferred, and triallyl isocyanurate (TAIC) is more preferred.

[0079] The curing agent may be used alone or in combination of two or more kinds.

[0080] The weight-average molecular weight of the curing agent is not particularly limited, but is preferably 100 to 5000, more preferably 100 to 4000, and even more preferably 100 to 3000. If the weight-average molecular weight of the curing agent is too low, the curing agent may be more likely to volatilize from the resin composition's blending components. Furthermore, if the weight-average molecular weight of the curing agent is too high, the viscosity of the resin composition varnish or the melt viscosity during heat molding may be too high. Therefore, when the weight-average molecular weight of the curing agent is within this range, a resin composition with superior heat resistance of the cured product can be obtained. This is thought to be because the reaction with the polyphenylene ether compound allows the resin composition containing the polyphenylene ether compound to be suitably cured. The weight-average molecular weight may be measured using a common molecular weight measurement method, specifically, a value measured using gel permeation chromatography (GPC), etc.

[0081] The average number of functional groups per molecule of the curing agent that contribute to the reaction with the polyphenylene ether compound (number of functional groups) varies depending on the weight-average molecular weight of the curing agent, but is preferably 1 to 20, and more preferably 2 to 18. If the number of functional groups is too small, it tends to be difficult to obtain sufficient heat resistance of the cured product. On the other hand, if the number of functional groups is too large, the reactivity becomes too high, which may cause problems such as reduced storage stability and reduced fluidity of the resin composition.

[0082] Inorganic Filler: Examples of the inorganic filler include those added to enhance the heat resistance and flame retardancy of the cured resin composition, and are not particularly limited. Furthermore, the inclusion of the inorganic filler can further enhance the heat resistance and flame retardancy. The inorganic filler is not particularly limited as long as it can be used as an inorganic filler contained in the resin composition. Specific examples of the inorganic filler include silica fillers such as spherical silica, metal oxide fillers such as alumina fillers, titanium oxide fillers, and mica fillers, metal hydroxide fillers such as aluminum hydroxide fillers and magnesium hydroxide fillers, talc fillers, aluminum borate fillers, barium sulfate fillers, and calcium carbonate fillers. Among these, silica fillers, mica fillers, and talc fillers are preferred, with spherical silica being more preferred. Furthermore, the inorganic fillers may be used alone or in combination of two or more. The inorganic filler may be used as it is, or may be surface-treated with a silane coupling agent, which will be described later.

[0083] The average particle size of the inorganic filler is not particularly limited, and is preferably 0.05 to 5 μm, and more preferably 0.05 to 1.5 μm. Here, the average particle size refers to the volume average particle size. The volume average particle size can be measured, for example, by laser diffraction or the like.

[0084] Other Components Each of the resin compositions may contain components (other components) other than the curable resin and the curing agent. Examples of other components contained in the resin composition include a polybutadiene compound having an epoxy group in its molecule, a styrene-based block copolymer, a silane coupling agent, a flame retardant, an initiator, a curing accelerator, an antifoaming agent, an antioxidant, a polymerization inhibitor, a polymerization retarder, a dispersant, a leveling agent, a heat stabilizer, an antistatic agent, an ultraviolet absorber, a dye or pigment, and a lubricant. Furthermore, each of the resin compositions may contain, in addition to the polyphenylene ether compound, a thermosetting resin such as an epoxy resin, an unsaturated polyester resin, or a thermosetting polyimide resin. Furthermore, the second resin composition and the third resin composition preferably contain, as the other components, a polybutadiene compound having an epoxy group in its molecule and a styrene-based polymer. That is, examples of the second resin composition and the third resin composition include a resin composition containing a curable resin such as the polyphenylene ether compound, the curing agent, a polybutadiene compound having an epoxy group in the molecule, a styrene-based polymer, and an inorganic filler.

[0085] Polybutadiene Compound Having Epoxy Groups in the Molecule The polybutadiene compound having epoxy groups in the molecule is not particularly limited, and examples include epoxidized polybutadiene, i.e., a compound in which epoxy groups have been introduced into the molecule by epoxidizing at least a portion of the carbon-carbon double bonds contained in polybutadiene, and a compound in which both terminals of polybutadiene have been glycidyl-etherified. The epoxidation is carried out, for example, by adding one oxygen atom to the carbon-carbon double bond contained in polybutadiene (non-epoxidized polybutadiene) using an epoxidizing agent to form a three-membered ring epoxy group. A compound in which both terminals of polybutadiene have been glycidyl-etherified can be obtained by adding epichlorohydrin to polybutadiene having hydroxyl groups at both terminals.

[0086] The polybutadiene (non-epoxidized polybutadiene) may have a stereostructure of carbon-carbon double bonds of any of cis-1,4, trans-1,4, cis-1,2, and trans-1,2, and the ratio thereof is not particularly limited.

[0087] The epoxidizing agent is not particularly limited as long as it can epoxidize the carbon-carbon double bonds contained in polybutadiene, and examples of the epoxidizing agent include percarboxylic acids such as peracetic acid, performic acid, perbenzoic acid, trifluoroperacetic acid, and perpropionic acid, organic hydroperoxides such as t-butyl hydroperoxide and cumene hydroperoxide, and hydrogen peroxide.

[0088] The polybutadiene compound having an epoxy group in its molecule preferably has an oxirane oxygen concentration of 1 to 10% by mass, more preferably 5 to 9% by mass. If the oxirane oxygen concentration is too low, the effect of adding the polybutadiene compound having an epoxy group in its molecule, i.e., the effect of improving the adhesion of the cured resin composition to metal foil, tends to be insufficient. On the other hand, if the oxirane oxygen concentration is too high, the epoxy groups tend to become too numerous, which tends to deteriorate the low dielectric properties. By using the polybutadiene compound having an epoxy group in its molecule whose oxirane oxygen concentration is within the above range, a resin composition can be obtained that, when cured, results in a cured product with low dielectric properties and high adhesion to metal foil.

[0089] The concentration of oxirane oxygen is an index of the content of epoxy groups contained in the polybutadiene compound having epoxy groups in the molecule, and can be measured, for example, by a hydrogen bromide-glacial acetic acid solution method.

[0090] Styrene-Based Polymer The styrene-based polymer is not particularly limited as long as it is a styrene-based polymer that can be used as a resin contained in a resin composition, etc., used to form an insulating layer provided in a metal-clad laminate, a wiring board, etc.

[0091] When each of the resin compositions contains the polybutadiene compound having an epoxy group in the molecule, the content of the polybutadiene compound having an epoxy group in the molecule is preferably 5 to 60 mass% with respect to the total amount of each of the resin compositions.

[0092] The styrene-based polymer may be, for example, a polymer obtained by polymerizing a monomer containing a styrene-based monomer, and may be a styrene-based copolymer. Examples of the styrene-based copolymer include copolymers obtained by copolymerizing one or more of the styrene-based monomers with one or more other monomers copolymerizable with the styrene-based monomer. The styrene-based copolymer may be a random copolymer or a block copolymer, as long as it has a structure derived from the styrene-based monomer in its molecule. Examples of the block copolymer include a binary copolymer of the structure (repeating unit) derived from the styrene-based monomer and the other copolymerizable monomer (repeating unit), a terpolymer of the structure (repeating unit) derived from the styrene-based monomer, the other copolymerizable monomer (repeating unit), and the structure (repeating unit) derived from the styrene-based monomer, and a terpolymer of the structure (repeating unit) derived from the styrene-based monomer, a random copolymer block (repeating unit) containing the other copolymerizable monomer and the styrene-based monomer, and the structure (repeating unit) derived from the styrene-based monomer. The styrene-based polymer may be a hydrogenated styrene-based copolymer obtained by hydrogenating the styrene-based copolymer. Furthermore, it is preferable that the styrene-based polymer is at least partially hydrogenated. By containing an at least partially hydrogenated styrene-based polymer, a resin composition can be obtained that has superior adhesion to metal foil and forms a cured product with superior dimensional stability. Furthermore, the styrene-based polymer may be a resin obtained by modifying a portion of the styrene-based copolymer, the at least partially hydrogenated styrene-based polymer, or the hydrogenated styrene-based copolymer with maleic anhydride.

[0093] The styrene-based monomer is not particularly limited, but examples thereof include styrene, styrene derivatives, styrene in which some of the hydrogen atoms on the benzene ring have been substituted with alkyl groups, styrene in which some of the hydrogen atoms on the vinyl group have been substituted with alkyl groups, vinyltoluene, α-methylstyrene, butylstyrene, dimethylstyrene, and isopropenyltoluene. These styrene-based monomers may be used alone or in combination of two or more. Furthermore, the copolymerizable other monomer is not particularly limited, but examples thereof include olefins such as α-pinene, β-pinene, and dipentene, non-conjugated dienes such as 1,4-hexadiene and 3-methyl-1,4-hexadiene, and conjugated dienes such as 1,3-butadiene and 2-methyl-1,3-butadiene (isoprene). These copolymerizable other monomers may be used alone or in combination of two or more.

[0094] More specific examples of the styrene-based polymer include methylstyrene (ethylene / butylene) methylstyrene block copolymers, methylstyrene (ethylene-ethylene / propylene) methylstyrene block copolymers, styrene-isoprene block copolymers, hydrogenated styrene-isoprene-styrene block copolymers, styrene (ethylene / butylene) styrene block copolymers, styrene (ethylene-ethylene / propylene) styrene block copolymers, styrene-butadiene block copolymers such as styrene-butadiene-styrene block copolymers, styrene-isobutylene-styrene block copolymers, styrene (butadiene / butylene) styrene block copolymers, methylstyrene (styrene / butadiene random copolymer block) methylstyrene copolymers, styrene (styrene / butadiene random copolymer block) styrene copolymers, and hydrogenated products of these at least partially hydrogenated.

[0095] As the styrene-based polymer, commercially available products may be used, such as Tuftec P1500, Tuftec H1221, Tuftec H1041, Tuftec H1517, and Tuftec M1913 manufactured by Asahi Kasei Corporation, and Asaprene T437 manufactured by Asahi Kasei Corporation.

[0096] As the styrene-based polymer, the above-exemplified styrene-based polymers may be used alone or in combination of two or more kinds.

[0097] The styrene polymer preferably has a weight-average molecular weight of 1,000 to 300,000, more preferably 10,000 to 200,000. If the molecular weight is too low, the glass transition temperature of the cured product of the resin composition tends to decrease, and the heat resistance tends to decrease. If the molecular weight is too high, the viscosity of the resin composition when made into a varnish or when heat-molded tends to become too high. The weight-average molecular weight may be measured by a general molecular weight measurement method, and specific examples include values ​​measured using gel permeation chromatography (GPC).

[0098] By including the styrene-based block copolymer in the resin composition, a resin composition can be obtained that, when cured, becomes a cured product that has high adhesiveness to metal foil.

[0099] When the resin composition contains the styrene polymer, the content of the styrene polymer is preferably 5 to 70% by mass relative to the total amount of the resin composition.

[0100] As described above, each of the resin compositions may contain a flame retardant. The inclusion of a flame retardant can enhance the flame retardancy of the cured resin composition. The flame retardant is not particularly limited. Specifically, in fields where halogen-based flame retardants such as bromine-based flame retardants are used, for example, ethylene dipentabromobenzene, ethylene bistetrabromoimide, decabromodiphenyl oxide, and tetradecabromodiphenoxybenzene, which have melting points of 300°C or higher, are preferred. The use of a halogen-based flame retardant is believed to suppress halogen elimination at high temperatures and prevent a decrease in heat resistance. In addition, in fields where halogen-free materials are required, phosphate ester-based flame retardants, phosphazene-based flame retardants, bisdiphenylphosphine oxide-based flame retardants, and phosphinate-based flame retardants are examples. A specific example of a phosphate ester-based flame retardant is condensed phosphate ester of dixylenyl phosphate. A specific example of a phosphazene-based flame retardant is phenoxyphosphazene. A specific example of a bisdiphenylphosphine oxide-based flame retardant is xylylenebisdiphenylphosphine oxide. A specific example of a phosphinate-based flame retardant is a metal phosphinate salt of an aluminum dialkylphosphinate. As the flame retardant, each of the exemplified flame retardants may be used alone or in combination of two or more.

[0101] As described above, each of the resin compositions may contain a silane coupling agent. The silane coupling agent may be contained in the resin composition, or may be contained as a silane coupling agent that has been surface-treated in advance on an inorganic filler contained in the resin composition. Among these, the silane coupling agent is preferably contained as a silane coupling agent that has been surface-treated in advance on an inorganic filler, and it is more preferable to contain the silane coupling agent in advance on an inorganic filler in this way, and further to contain the silane coupling agent in the resin composition. In addition, in the case of a prepreg, the silane coupling agent may be contained as a silane coupling agent that has been surface-treated in advance on a fibrous substrate in the prepreg.

[0102] Examples of the silane coupling agent include silane coupling agents having at least one functional group selected from the group consisting of a vinyl group, a styryl group, a methacryloyl group, an acryloyl group, and a phenylamino group. That is, the silane coupling agent includes compounds having at least one reactive functional group selected from a vinyl group, a styryl group, a methacryloyl group, an acryloyl group, and a phenylamino group, and further having a hydrolyzable group such as a methoxy group or an ethoxy group.

[0103] Examples of the silane coupling agent include those having a vinyl group, such as vinyltriethoxysilane and vinyltrimethoxysilane. Examples of the silane coupling agent include those having a styryl group, such as p-styryltrimethoxysilane and p-styryltriethoxysilane. Examples of the silane coupling agent include those having a methacryloyl group, such as 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropylethyldiethoxysilane. Examples of the silane coupling agent include those having an acryloyl group, such as 3-acryloxypropyltrimethoxysilane and 3-acryloxypropyltriethoxysilane. Examples of the silane coupling agent include those having a phenylamino group, such as N-phenyl-3-aminopropyltrimethoxysilane and N-phenyl-3-aminopropyltriethoxysilane.

[0104] As described above, each of the resin compositions may contain an initiator (reaction initiator). The curing reaction can proceed even if the resin composition does not contain a reaction initiator. However, depending on the process conditions, it may be difficult to raise the temperature high enough for curing to proceed, so a reaction initiator may be added. The reaction initiator is not particularly limited as long as it can accelerate the curing reaction between the polyphenylene ether compound and the curing agent. Specific examples include oxidizing agents such as α,α'-bis(t-butylperoxy-m-isopropyl)benzene, 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne, benzoyl peroxide, 3,3',5,5'-tetramethyl-1,4-diphenoquinone, chloranil, 2,4,6-tri-t-butylphenoxyl, t-butylperoxyisopropyl monocarbonate, and azobisisobutyronitrile. Furthermore, a metal carboxylate or the like can be used in combination, if necessary. This can further accelerate the curing reaction. Among these, α,α'-bis(t-butylperoxy-m-isopropyl)benzene is preferably used. α,α'-bis(t-butylperoxy-m-isopropyl)benzene has a relatively high reaction initiation temperature, so it can suppress the acceleration of the curing reaction when curing is not necessary, such as during prepreg drying, and can suppress a decrease in the shelf life of the resin composition. Furthermore, α,α'-bis(t-butylperoxy-m-isopropyl)benzene has low volatility, so it does not volatilize during prepreg drying or storage, and has good stability. Furthermore, the reaction initiators may be used alone or in combination of two or more.

[0105] As described above, each of the resin compositions may contain a curing accelerator. The curing accelerator is not particularly limited as long as it can accelerate the curing reaction of the resin composition. Specific examples of the curing accelerator include imidazoles and their derivatives, organophosphorus compounds, amines such as secondary amines and tertiary amines, quaternary ammonium salts, organoboron compounds, and metal soaps. Examples of the imidazoles include 2-ethyl-4-methylimidazole, 2-methylimidazole, 2-phenyl-4-methylimidazole, 2-phenylimidazole, and 1-benzyl-2-methylimidazole. Examples of the organophosphorus compounds include triphenylphosphine, diphenylphosphine, phenylphosphine, tributylphosphine, and trimethylphosphine. Examples of the amines include dimethylbenzylamine, triethylenediamine, triethanolamine, and 1,8-diaza-bicyclo(5,4,0)undecene-7 (DBU). Examples of the quaternary ammonium salt include tetrabutylammonium bromide. Examples of the organoboron-based compounds include tetraphenylboron salts such as 2-ethyl-4-methylimidazole tetraphenylborate, and tetra-substituted phosphonium tetra-substituted borates such as tetraphenylphosphonium ethyltriphenylborate. The metal soap refers to a fatty acid metal salt, and may be a linear fatty acid metal salt or a cyclic fatty acid metal salt. Specific examples of the metal soap include linear fatty acid metal salts and cyclic fatty acid metal salts having 6 to 10 carbon atoms. More specific examples include aliphatic metal salts composed of linear fatty acids such as stearic acid, lauric acid, ricinoleic acid, and octylic acid, or cyclic fatty acids such as naphthenic acid, and metals such as lithium, magnesium, calcium, barium, copper, and zinc. For example, zinc octylate is included. The curing accelerators may be used alone or in combination of two or more.

[0106] (Fibrous Substrate) As described above, the first insulating layer 11 preferably contains a fibrous substrate. The second insulating layer 12 and the third insulating layer 13 also preferably do not contain a fibrous substrate, but may contain a fibrous substrate. Examples of such fibrous substrates include, but are not limited to, glass cloth, aramid cloth, polyester cloth, glass nonwoven fabric, aramid nonwoven fabric, polyester nonwoven fabric, pulp paper, and linter paper. Glass cloth provides a laminate with excellent mechanical strength, and flattened glass cloth is particularly preferred. Examples of the flattening process include a method in which glass cloth is continuously compressed with a press roll at an appropriate pressure to flatten the yarn. The thickness of commonly used fibrous substrates is, for example, 0.01 mm or more and 0.3 mm or less. The glass fibers constituting the glass cloth are also not particularly limited, but examples include Q glass, NE glass, E glass, S glass, T glass, L glass, and L2 glass. The surface of the fibrous substrate may be treated with a silane coupling agent, which is not particularly limited, but may include, for example, a silane coupling agent having at least one group selected from the group consisting of a vinyl group, an acryloyl group, a methacryloyl group, a styryl group, an amino group, and an epoxy group in the molecule.

[0107] (Manufacturing Method) The method for manufacturing the laminate is not particularly limited as long as it can produce the laminate. For example, the method for manufacturing the laminate involves first heating and curing a prepreg containing the first resin composition or a semi-cured product of the first resin composition. Then, a film containing the second resin composition or a semi-cured product of the second resin composition is placed on one main surface of the cured product (first insulating layer), and a film containing the third resin composition or a semi-cured product of the third resin composition is placed on the other main surface of the first insulating layer. The cured product (first insulating layer) of the prepreg with the film placed on it is heated and pressurized to form an integrated laminate. This allows the laminate to be obtained. Furthermore, in this manufacturing method, a wiring board with wiring formed on the cured product can be used instead of the cured product to produce a laminate such as the one shown in FIG. 2. Alternatively, a film containing the second resin composition or a semi-cured product of the second resin composition is overlaid on one main surface of a prepreg containing the first resin composition or a semi-cured product of the first resin composition, and a film containing the third resin composition or a semi-cured product of the third resin composition is overlaid on the other main surface of the prepreg. The prepreg with the overlaid film is heated and pressurized to form an integrated laminate. This manufacturing method also produces the laminate. Furthermore, when manufacturing the laminate, a metal-clad laminate comprising the laminate, as described below, can be manufactured by overlaying a metal foil on the film of the cured product of the prepreg with the overlaid film, or by using a film with a metal foil as the film.

[0108] [Metal-clad laminate] As shown in FIG. 3, a metal-clad laminate 30 according to an embodiment of the present invention comprises the laminate 10 and a metal foil 14 laminated on the laminate 10. As shown in FIG. 3, the metal foil 14 may be laminated on both sides of the laminate 10, or on one side of the laminate 10. Furthermore, the laminate provided in the metal-clad laminate is not limited to the laminate 10 shown in FIG. 1, but may be any laminate according to the present embodiment, such as the laminate 20 shown in FIG. 2. That is, a metal-clad laminate 40 according to another embodiment of the present invention comprises the laminate 20 and a metal foil 14 laminated on the laminate 20, as shown in FIG. 4. Thus, a metal-clad laminate according to an embodiment of the present invention comprises the laminate according to the present embodiment and a metal foil laminated on at least one main surface of the laminate. Note that FIG. 3 is a schematic cross-sectional view showing an example of a metal-clad laminate according to an embodiment of the present invention (the metal-clad laminate 30), and FIG. 4 is a schematic cross-sectional view showing another example of a metal-clad laminate according to an embodiment of the present invention (the metal-clad laminate 40).

[0109] Examples of the metal foil 14 include copper foil and aluminum foil, and copper foil is preferred. When the metal foil is thin, it may be a carrier-supported copper foil having a release layer and a carrier to improve handling. The copper foil may contain copper, and may be made of, for example, copper or a copper alloy. Examples of the copper alloy include an alloy containing copper and at least one element selected from the group consisting of nickel, phosphorus, tungsten, arsenic, molybdenum, chromium, cobalt, and zinc.

[0110] The thickness of the metal foil 14 varies depending on the performance required of the final wiring board, and is not particularly limited. The thickness of the metal foil 14 can be set appropriately depending on the desired purpose, and is preferably 105 μm or less, and more preferably 0.2 to 35 μm. The arithmetic mean roughness (Ra) of the metal foil 14 is preferably 2 μm or less, and more preferably 0.1 to 1.5 μm. The ten-point mean roughness (Rz) of the metal foil 14 is preferably 10 μm or less, and more preferably 0.5 to 8 μm. The arithmetic mean roughness (Ra) and the ten-point mean roughness (Rz) are each measured using a method in accordance with JIS B0601 (2001), and more specifically, can be measured using a roughness meter or the like.

[0111] The metal foil 14 may be a surface-treated metal foil. The surface-treated metal foil may be surface-treated on both sides or on one side. Furthermore, when one side of the metal foil is surface-treated, it is preferable that the surface-treated surface contacts the laminate. Examples of the surface treatment include a silane coupling agent treatment, a roughening treatment, a heat-resistant treatment, and a rust-proofing treatment. The metal foil 14 may be subjected to one of these surface treatments alone or a combination of two or more surface treatments. The silane coupling agent used in the silane coupling agent treatment is not particularly limited, and examples include the same silane coupling agent as the silane coupling agent contained in the resin composition. Examples of the roughening treatment, the heat-resistant treatment, and the rust-proofing treatment include typical roughening treatments, heat-resistant treatments, and rust-proofing treatments applied to metal foils, respectively.

[0112] The method for producing the metal-clad laminate is not particularly limited as long as it can produce the metal-clad laminate. For example, the method for producing the metal-clad laminate includes first heating and curing a prepreg containing the first resin composition or a semi-cured product of the first resin composition. Then, a film containing the second resin composition or a semi-cured product of the second resin composition is superimposed on one main surface of the cured product, and a film containing the second resin composition or a semi-cured product of the second resin composition is superimposed on the other main surface of the cured product. Furthermore, the metal foil is superimposed on each of the films. The cured prepreg with the film and metal foil superimposed thereon is heated and pressurized to form an integrated laminate. This produces the metal-clad laminate. Alternatively, the metal-clad laminate can be produced by using a film with metal foil as the film when producing the laminate. Alternatively, a film containing the second resin composition or a semi-cured product of the second resin composition is layered on one main surface of a prepreg containing the first resin composition or a semi-cured product of the first resin composition, and a metal foil is layered on top of that. Meanwhile, a film containing the third resin composition or a semi-cured product of the third resin composition is layered on the other main surface of the prepreg, and a metal foil is layered on top of that. The prepreg with the layered film and metal foil is then heated and pressure molded to form an integrated laminate. This manufacturing method also produces the metal-clad laminate.

[0113] The laminate according to the present embodiment is a laminate that is suppressed in warp and has excellent processability. Therefore, the metal-clad laminate according to the present embodiment includes the laminate, and is therefore a metal-clad laminate that is suppressed in warp and has excellent processability.

[0114] [Wiring Board] As shown in FIG. 5, a wiring board 50 according to an embodiment of the present invention includes the laminate 10 and wiring 16 disposed on the laminate 10. The wiring 16 may be disposed on both sides of the laminate 10, as shown in FIG. 5, or on one side of the laminate 10. The laminate included in the wiring board is not limited to the laminate 10 shown in FIG. 1, but may be any laminate according to the present embodiment, such as the laminate 20 shown in FIG. 2. That is, a wiring board 60 according to another embodiment of the present invention includes the laminate 20 and wiring 16 disposed on the laminate 20, as shown in FIG. 6. Therefore, a wiring board according to an embodiment of the present invention includes the laminate according to the present embodiment and wiring disposed on at least one main surface of the laminate. When the laminate 20 shown in FIG. 2 is used as the laminate, the resulting wiring board is a multilayer wiring board. Note that FIG. 5 is a schematic cross-sectional view showing an example of a wiring board according to an embodiment of the present invention (the wiring board 50), and FIG. 6 is a schematic cross-sectional view showing another example of a wiring board according to an embodiment of the present invention (the wiring board 60).

[0115] The wiring 16 may be, for example, a wiring formed by partially removing the metal foil 14 .

[0116] The method for producing the wiring board is not particularly limited as long as it can produce the wiring board. Examples of methods for producing the wiring board include a method of producing a wiring board in which wiring is provided as a circuit on the surface of the laminate by etching the metal foil on the surface of the metal-clad laminate. That is, the wiring board is obtained by forming a circuit by partially removing the metal foil on the surface of the metal-clad laminate. In addition to the above methods, examples of methods for forming a circuit include circuit formation by a semi-additive process (SAP) or a modified semi-additive process (MSAP).

[0117] The wiring board according to this embodiment is a laminate that is suppressed in warping and has excellent processability. Therefore, the metal-clad laminate according to this embodiment includes the laminate, and is therefore a wiring board that is suppressed in warping and has excellent processability.

[0118] This specification discloses various aspects of the technology as described above, but the main technologies among them are summarized below.

[0119] A laminate according to a first aspect of the present invention comprises a first insulating layer containing a cured product (A) of a first resin composition, a second insulating layer containing a cured product (B) of a second resin composition and laminated on a first main surface side of the first insulating layer, and a third insulating layer containing a cured product (C) of a third resin composition and laminated on a second main surface side of the first insulating layer, wherein the thickness of the first insulating layer is 10 to 300 μm, the thicknesses of the second insulating layer and the third insulating layer are each 8 to 50 μm, the tensile storage modulus of the cured product (A) at 30° C. is 3.5 GPa or more, and the tensile storage moduli of the cured products (B) and (C) at 30° C. are each 3 GPa or less.

[0120] The laminate according to a second aspect of the present invention is the laminate according to the first aspect of the present invention, wherein the thermal expansion coefficient (T1) of the cured product (A) at 50 to 100°C is 35 ppm / °C or less.

[0121] A laminate according to a third aspect of the present invention is the laminate according to the first or second aspect of the present invention, wherein the thermal expansion coefficient (T2) of the cured product (B) at 50 to 100°C and the thermal expansion coefficient (T3) of the cured product (C) at 50 to 100°C are each 100 ppm / °C or less.

[0122] A laminate according to a fourth aspect of the present invention is a laminate according to any one of the first to third aspects of the present invention, wherein the dielectric loss tangent of the second insulating layer and the third insulating layer is each 0.004 or less at 10 GHz.

[0123] A laminate according to a fifth aspect of the present invention is a laminate according to any one of the first to fourth aspects of the present invention, wherein the second insulating layer and the third insulating layer each have a relative dielectric constant of 3 or less at 10 GHz.

[0124] A laminate according to a sixth aspect of the present invention is a laminate according to any one of the first to fifth aspects of the present invention, wherein the first insulating layer further contains a fibrous base material, and the second insulating layer and the third insulating layer do not contain a fibrous base material.

[0125] A laminate according to a seventh aspect of the present invention is a laminate according to any one of the first to sixth aspects of the present invention, wherein the second resin composition contains an inorganic filler and the content of the inorganic filler is 25 to 250 mass% relative to the total amount of the second resin composition excluding the inorganic filler, and the third resin composition contains an inorganic filler and the content of the inorganic filler is 25 to 250 mass% relative to the total amount of the third resin composition excluding the inorganic filler.

[0126] A laminate according to an eighth aspect of the present invention is a laminate according to any one of the first to seventh aspects of the present invention, wherein the second insulating layer is a layer formed by curing a film containing the second resin composition or a semi-cured product of the second resin composition, and the third insulating layer is a layer formed by curing a film containing the third resin composition or a semi-cured product of the third resin composition.

[0127] A laminate according to a ninth aspect of the present invention is a laminate according to any one of the first to eighth aspects of the present invention, wherein the first insulating layer is a layer formed by curing a prepreg containing the first resin composition or a semi-cured product of the first resin composition.

[0128] A metal-clad laminate according to a tenth aspect of the present invention is a metal-clad laminate comprising a laminate according to any one of the first to ninth aspects of the present invention and a metal foil laminated on at least one main surface side of the laminate.

[0129] A metal-clad laminate according to an eleventh aspect of the present invention is the metal-clad laminate according to the tenth aspect of the present invention, wherein the metal foil includes a copper foil.

[0130] A wiring board according to a twelfth aspect of the present invention is a wiring board comprising a laminate according to any one of the first to ninth aspects of the present invention and wiring arranged on at least one main surface side of the laminate.

[0131] According to the present invention, it is possible to provide a laminate, a metal-clad laminate, and a wiring board that are suppressed in warping and have excellent processability.

[0132] The present invention will be explained in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0133] Examples 1 to 10 and Comparative Examples 1 to 5 The resin compositions used in the examples will be described.

[0134] <First Insulating Layer> First, each component used in preparing the first resin composition used to form the first insulating layer will be described.

[0135] Modified PPE-1: A polyphenylene ether compound having a vinylbenzyl group (ethenylbenzyl group) at the end (a modified polyphenylene ether compound obtained by reacting polyphenylene ether with chloromethylstyrene).

[0136] Specifically, it is a modified polyphenylene ether compound obtained by the following reaction.

[0137] First, 200 g of polyphenylene ether (SA90 manufactured by SABIC Innovative Plastics, 2 terminal hydroxyl groups, weight average molecular weight Mw 1700), 30 g of a 50:50 mass ratio mixture of p-chloromethylstyrene and m-chloromethylstyrene (chloromethylstyrene: CMS manufactured by Tokyo Chemical Industry Co., Ltd.), 1.227 g of tetra-n-butylammonium bromide as a phase transfer catalyst, and 400 g of toluene were charged into a 1-liter three-neck flask equipped with a temperature controller, a stirrer, a cooling device, and a dropping funnel, and the mixture was stirred. The polyphenylene ether, chloromethylstyrene, and tetra-n-butylammonium bromide were stirred until they were dissolved in toluene. The mixture was gradually heated, and finally heated until the liquid temperature reached 75 ° C. Then, an aqueous sodium hydroxide solution (20 g sodium hydroxide / 20 g water) was added dropwise to the solution as an alkali metal hydroxide over 20 minutes. The mixture was then stirred at 75°C for an additional 4 hours. Next, the contents of the flask were neutralized with 10% by mass hydrochloric acid, and a large amount of methanol was added. This caused a precipitate to form in the liquid in the flask. That is, the product contained in the reaction solution in the flask was reprecipitated. The precipitate was then filtered, washed three times with a mixture of methanol and water in a mass ratio of 80:20, and then dried under reduced pressure at 80°C for 3 hours.

[0138] The obtained solid was １ H-NMR (400MHz, CDCl ３ , TMS). As a result of NMR measurement, a peak derived from a vinylbenzyl group (ethenylbenzyl group) was confirmed at 5 to 7 ppm. This confirmed that the obtained solid was a modified polyphenylene ether compound having a vinylbenzyl group (ethenylbenzyl group) as the substituent at the molecular end. Specifically, it was confirmed that it was an ethenylbenzylated polyphenylene ether. This obtained modified polyphenylene ether compound is represented by the above formula (11), in which Y in formula (11) is a dimethylmethylene group (represented by formula (9), and R in formula (9) is ３３ and R ３４ is a methyl group), Z is a phenylene group, and R １~R ３ was a hydrogen atom and p was 1.

[0139] The number of terminal functional groups of the modified polyphenylene ether was measured as follows.

[0140] First, the modified polyphenylene ether was accurately weighed. The weight at that time was designated X (mg). Then, this weighed modified polyphenylene ether was dissolved in 25 mL of methylene chloride, and 100 μL of a 10 mass% ethanol solution of tetraethylammonium hydroxide (TEAH) (TEAH:ethanol (volume ratio) = 15:85) was added to the solution, and the absorbance (Abs) at 318 nm was measured using a UV spectrophotometer (UV-1600 manufactured by Shimadzu Corporation). Then, from the measurement results, the number of terminal hydroxyl groups of the modified polyphenylene ether was calculated using the following formula.

[0141] Residual OH amount (μmol / g) = [(25×Abs) / (ε×OPL×X)]×10 ６ Here, ε is the extinction coefficient and is 4700 L / mol·cm, and OPL is the cell optical path length and is 1 cm.

[0142] The calculated residual OH amount (number of terminal hydroxyl groups) of the modified polyphenylene ether was almost zero, which indicated that the hydroxyl groups of the polyphenylene ether before modification were almost entirely modified. This indicated that the decrease from the number of terminal hydroxyl groups of the polyphenylene ether before modification was the number of terminal hydroxyl groups of the polyphenylene ether before modification. In other words, it was found that the number of terminal hydroxyl groups of the polyphenylene ether before modification was the number of terminal functional groups of the modified polyphenylene ether. In other words, the number of terminal functional groups was two.

[0143] The intrinsic viscosity (IV) of the modified polyphenylene ether was measured in methylene chloride at 25° C. Specifically, the intrinsic viscosity (IV) of the modified polyphenylene ether was measured by using a viscometer (AVS500 Visco System manufactured by Schott) to measure a 0.18 g / 45 ml methylene chloride solution (liquid temperature 25° C.). As a result, the intrinsic viscosity (IV) of the modified polyphenylene ether was 0.086 dl / g.

[0144] The molecular weight distribution of the modified polyphenylene ether was measured using GPC. The weight average molecular weight (Mw) was calculated from the molecular weight distribution. The Mw was found to be 1,900.

[0145] DCP: Tricyclodecane dimethanol dimethacrylate (NK Ester DCP manufactured by Shin-Nakamura Chemical Co., Ltd.) B1000: Polybutadiene oligomer (B1000 manufactured by Nippon Soda Co., Ltd.) Inorganic filler: Spherical silica (dry powder) (2500SQ manufactured by Admatechs Co., Ltd., average particle size 0.6 μm)

[0146] 70 parts by mass of modified PPE-1, 15 parts by mass of DCP, and 15 parts by mass of B1000 were added to a mixed solvent of toluene and methyl ethyl ketone (MEK) (mass ratio of approximately 1:1) so that the solids concentration was 50% by mass, and the mixture was stirred for 60 minutes to mix. Thereafter, an inorganic filler was added to the resulting mixture in the inorganic filler content (parts by mass) shown in Table 1, and the mixture was dispersed using a bead mill. This resulted in a varnish-like resin composition (varnish).

[0147] Next, a prepreg was obtained as follows.

[0148] The prepregs used in Examples 1 to 4 were produced by impregnating a fibrous substrate (glass cloth: #1006 type, E-glass, manufactured by Nitto Boseki Co., Ltd.) with the resulting varnish and then drying by heating at 130° C. for 3 minutes. The content of the components that constitute the resin by the curing reaction relative to the prepreg (resin content) was adjusted to about 55% by mass, and the thickness after curing was adjusted to 10 μm.

[0149] Next, a prepreg was obtained as follows.

[0150] The prepreg for forming the 10 μm thick first insulating layer (the prepreg used in Examples 1 to 4 and Comparative Example 5) was produced by impregnating the obtained varnish into a fibrous substrate (glass cloth: #1006 type, E-glass manufactured by Nitto Boseki Co., Ltd.) and then heating and drying for 3 minutes at 130° C. In this process, the content of the components that constitute the resin by the curing reaction relative to the prepreg (resin content) was adjusted to be approximately 55 mass %, and further, the thickness after curing was adjusted to be 10 μm.

[0151] The prepreg for forming the 20 μm thick first insulating layer (the prepreg used in Examples 5 and 6) was produced by impregnating the obtained varnish into a fibrous substrate (glass cloth: #1010 type, E-glass manufactured by Nitto Boseki Co., Ltd.) and then heating and drying for 3 minutes at 130° C. In this process, the content of the components that constitute the resin by the curing reaction relative to the prepreg (resin content) was adjusted to be approximately 70 mass %, and further, the thickness after curing was adjusted to be 20 μm.

[0152] The prepreg for forming the 300 μm thick first insulating layer (the prepreg used in Examples 7 to 10) was produced by impregnating a fibrous substrate (glass cloth: #2116 type, E-glass manufactured by Nitto Boseki Co., Ltd.) with the obtained varnish, heating and drying it for 3 minutes at 130°C, and stacking three sheets of it. At this time, the content of the components that make up the resin by the curing reaction relative to the prepreg (resin content) was adjusted to be about 45 mass% and further adjusted so that the thickness after curing would be 300 μm.

[0153] The prepreg for forming the 18 μm thick first insulating layer (the prepreg used in Comparative Example 1) was produced by impregnating the obtained varnish into a fibrous substrate (glass cloth: #1010 type, E-glass manufactured by Nitto Boseki Co., Ltd.) and then heating and drying for 3 minutes at 130° C. In this process, the content of the components that make up the resin by the curing reaction relative to the prepreg (resin content) was adjusted to be approximately 68 mass %, and further, the thickness after curing was adjusted to be 18 μm.

[0154] The prepreg for forming the 600 μm-thick first insulating layer (the prepreg used in Comparative Example 4) was produced by impregnating a fibrous substrate (glass cloth: #2116 type, E-glass, manufactured by Nitto Boseki Co., Ltd.) with the obtained varnish, heating and drying it for 3 minutes at 130°C, and stacking six of these. The content of the components that make up the resin through the curing reaction relative to the prepreg (resin content) was adjusted to about 45 mass%, and the thickness after curing was adjusted to 600 μm.

[0155] <Second Insulating Layer and Third Insulating Layer> First, the components used in preparing the second resin composition and the third resin composition used to form the second insulating layer and the third insulating layer will be described.

[0156] Modified PPE-2: a modified polyphenylene ether compound in which the terminal hydroxyl group of polyphenylene ether is modified with a methacryloyl group [represented by the above formula (12), in which Y in the above formula (12) is a dimethylmethylene group (represented by the above formula (9), in which R ３３ and R ３４ wherein R is a methyl group, SA9000 manufactured by SABIC Innovative Plastics, number average molecular weight Mn 2300, number of terminal functional groups 2] Tuftec H1221: styrene (ethylene / butylene) styrene copolymer (SEBS) (Tuftec H1221 manufactured by Asahi Kasei Corporation) TAIC: triallyl isocyanurate (TAIC manufactured by Nippon Kasei Chemical Industry Co., Ltd.) JP100: polybutadiene compound having epoxy groups in the molecule (JP100 manufactured by Nippon Soda Co., Ltd., epoxidized polybutadiene in which epoxy groups are introduced by oxidation of the vinyl groups of 1,2-polybutadiene, oxirane concentration: 7.7% by mass) Perbutyl P: α,α'-di(t-butylperoxy)diisopropylbenzene (PBP) (Perbutyl P manufactured by NOF Corporation) Inorganic filler: spherical silica (dry powder) (2500SQ manufactured by Admatechs Co., Ltd., average particle size 0.6 μm)

[0157] 40 parts by weight of modified PPE-2, 40 parts by weight of Tuftec H1221, 10 parts by weight of TAIC, 10 parts by weight of JP100, and 1 part by weight of Perbutyl P were added to a mixed solvent of toluene and methyl ethyl ketone (MEK) (mass ratio of approximately 1:1) to a solids concentration of 50% by weight, and the mixture was stirred for 60 minutes. Thereafter, an inorganic filler was added to the resulting mixture in the inorganic filler content (parts by weight) shown in Table 1, and the mixture was dispersed using a bead mill. This resulted in a varnish-like resin composition (varnish).

[0158] Next, a film was obtained as follows.

[0159] The obtained varnish was applied to a copper foil (3EC-VLP, manufactured by Mitsui Mining & Smelting Co., Ltd., thickness 12 μm) and dried by heating at 100° C. for 2 minutes to prepare a copper foil-attached film. The amount of coating was adjusted so that the thickness of the resin after drying would be the thickness (μm) shown in Table 1.

[0160] (Tensile Storage Modulus) The tensile storage modulus at 30°C of the cured product of the resin composition (first resin composition) used to form the first insulating layer was measured. Specifically, the measurement was performed using the following method. First, the first resin composition was applied to a release film so that the thickness after heat drying was 0.04 mm, and then heat-dried at 140°C for 3 minutes to produce a film made of the cured product of the first resin composition. The resulting film was peeled from the release film and cut into 10 mm x 40 mm pieces. The cut film was used as a test piece and attached to a dynamic viscoelasticity measuring device (DMS6100 manufactured by Seiko Instruments Inc.). Testing was performed using a tensile method under conditions of a strain amplitude of 10 μm, a frequency of 10 Hz (sine wave), and a temperature rise rate of 10°C / min over a temperature range from -40°C to 260°C, and the tensile storage modulus (GPa) at 30°C was measured. The results are shown in Table 1.

[0161] The tensile storage moduli at 30°C of the cured products of the resin composition used to form the second insulating layer (second resin composition) and the resin composition used to form the third insulating layer (third resin composition) were measured in the same manner as for the tensile storage modulus of the cured product of the first resin composition. The results are also shown in Table 1.

[0162] (Coefficient of Thermal Expansion: CTE) The coefficient of thermal expansion of each of the first resin composition, the second resin composition, and the third resin composition was measured by the following measurement method.

[0163] Using the test specimen in the tensile storage modulus measurement method, the thermal expansion coefficient (CTE: ppm / °C) in the plane direction (tensile direction, Y-axis direction) of the test specimen was measured by the TMA method (thermo-mechanical analysis). Specifically, a TMA device (TMA6000 manufactured by SII NanoTechnology Inc.) was used for the measurement, and measurements were made in compression mode. In order to eliminate the influence of thermal distortion of the test specimen, the test specimen was heated from 30°C to 320°C at a heating rate of 10°C / min while being pulled with a load of 10 g in the Y direction, and then cooled to room temperature. Thereafter, the test specimen was heated from 30°C to 320°C at a heating rate of 10°C / min while being pulled with a load of 10 g in the Y direction. A temperature displacement chart was obtained during this temperature increase. The average thermal expansion coefficient from 50 to 100°C was calculated from the temperature displacement chart obtained at this time. The results are shown in Table 1.

[0164] (Dielectric Properties: Relative Permittivity Dk and Dielectric Loss Tangent Df) The relative permittivity Dk and dielectric loss tangent Df of each of the second insulating layer and the third insulating layer were measured by the following measurement method.

[0165] The dielectric constant and dielectric loss tangent (Df) of the test specimen at 10 GHz were measured by a cavity resonator perturbation method using the test specimen in the tensile storage modulus measurement method. Specifically, the dielectric constant (Dk) and dielectric loss tangent (Df) of the test specimen at 10 GHz were measured using a network analyzer (N5230A manufactured by Keysight Technologies, Inc.). The results are shown in Table 1.

[0166] <Metal-clad laminate> The resin-coated film was placed on both sides of the obtained prepreg so that the film side was in contact, and this was used as a pressure body. It was heated to a temperature of 220°C at a temperature increase rate of 3°C / min, and heated and pressurized at 220°C for 120 minutes under a pressure of 3 MPa. The prepreg and the film were cured with the film in contact with the prepreg, and a laminate (metal-clad laminate) with copper foil adhered to both sides was obtained. The cured product of the prepreg was the first insulating layer, and the cured products of the film were the second insulating layer and the third insulating layer. In each example, the second insulating layer and the third insulating layer were layers obtained from the same film.

[0167] The metal-clad laminates produced as described above were evaluated by the following methods.

[0168] [Warpage] Two sheets of the obtained metal-clad laminate were prepared and cut to 12 mm x 12 mm. A grid-like pattern with a copper residual ratio of 30% was formed on one of the two cut metal-clad laminates, and a grid-like pattern with a copper residual ratio of 18% was formed on the other. These were then laminated together and used as a support. A 9.6 mm x 9.6 mm x 0.15 mm semiconductor chip was placed on the support via a 9.6 mm x 9.6 mm x 0.02 mm die attach film (DAF, HR-9070G-1 manufactured by Resonac Co., Ltd.). An epoxy resin molding material (EMC, CV8714MYT manufactured by Panasonic Industries Co., Ltd.) was layered on the support to cover the semiconductor chip. The thickness of this EMC was 0.08 mm in the area where the semiconductor chip was present and 0.25 mm (= 0.15 mm + 0.02 mm + 0.08 mm) in the area where the semiconductor chip was not present. The warpage of the semiconductor package thus obtained at 30°C and at 260°C was measured using a projection moire warpage / deformation measurement system (TDM Compact3 manufactured by Insidix).The difference between the measured warpage at 30°C and the measured warpage at 260°C [swing amount: (warpage at 30°C) - (warpage at 260°C)] was calculated.The results are shown in Table 1.

[0169] [Punching properties] After etching the copper foil of the obtained metal-clad laminate, a cylindrical shape with a diameter of 81.1 mm was punched out of the etched portion using a trimming device (MKP-1000 (patented) manufactured by Mikado Technos Co., Ltd.), and the presence of cracks was visually confirmed on the cut surface. If the presence of cracks was not confirmed, it was found that the workability, such as drilling workability, was excellent. The results are shown in Table 1. If the presence of cracks was not confirmed, it was recorded as "absent" in Table 1, and if the presence of cracks was confirmed, it was recorded as "present" in Table 1.

[0170]

[0171] Table 1 shows that when a first insulating layer containing a cured product with a tensile storage modulus of 3.5 GPa or more and having a thickness of 10 to 300 μm was laminated with a second insulating layer and a third insulating layer containing a cured product with a tensile storage modulus of 3 GPa or less and having a thickness of 8 to 50 μm (Examples 1 to 10), warpage was suppressed and a laminate with excellent processability was obtained. Specifically, the laminates of Examples 1 to 10 were able to suppress warpage compared to a laminate containing only the first insulating layer without the second insulating layer and the third insulating layer (Comparative Example 1). Note that when the thickness of the first insulating layer was set to 600 μm, which is greater than 300 μm, warpage could be suppressed even without the second insulating layer and the third insulating layer, but processability was reduced. Furthermore, the laminates of Examples 1 to 10 were able to suppress warpage compared to a laminate not containing the first insulating layer (Comparative Examples 2 and 3). Furthermore, even though the laminates of Examples 1 to 10 had a first insulating layer, a second insulating layer, and a third insulating layer, warping was suppressed compared to when the tensile storage modulus of the first insulating layer was less than 3.5 GPa (Comparative Example 5).

[0172] This application is based on Japanese Patent Application No. 2023-170288 filed on September 29, 2023, the contents of which are incorporated herein by reference.

[0173] In order to express the present invention, the present invention has been properly and sufficiently described through the embodiments in the above, but it should be recognized that those skilled in the art can easily change and / or improve the above-mentioned embodiments. Therefore, unless the changes or improvements made by those skilled in the art are at a level that causes departure from the scope of the claims described in the claims, such changes or improvements are interpreted as being included in the scope of the claims.

[0174] According to the present invention, a laminate, a metal-clad laminate, and a wiring board are provided which are suppressed in warping and have excellent processability.

Claims

1. A laminate comprising a first insulating layer comprising a cured product of a first resin composition (A), a second insulating layer comprising a cured product of a second resin composition (B) and laminated on a first main surface side of the first insulating layer, and a third insulating layer comprising a cured product of a third resin composition (C) and laminated on a second main surface side of the first insulating layer, wherein the first insulating layer has a thickness of 10 to 300 μm, the second insulating layer and the third insulating layer each have a thickness of 8 to 50 μm, the cured product (A) has a tensile storage modulus at 30° C. of 3.5 GPa or more, and the cured products (B) and (C) each have a tensile storage modulus of 3 GPa or less at 30° C.

2. The laminate according to claim 1, wherein the thermal expansion coefficient (T1) of the cured product (A) at 50 to 100°C is 35 ppm / °C or less.

3. The laminate described in claim 1, wherein the thermal expansion coefficient (T2) of the cured product (B) at 50 to 100°C and the thermal expansion coefficient (T3) of the cured product (C) at 50 to 100°C are each 100 ppm / °C or less.

4. The laminate according to claim 1, wherein the dielectric tangent of each of the second insulating layer and the third insulating layer is 0.004 or less at 10 GHz.

5. The laminate according to claim 1, wherein the second insulating layer and the third insulating layer each have a relative dielectric constant of 3 or less at 10 GHz.

6. The laminate according to claim 1, wherein the first insulating layer further comprises a fibrous base material, and the second insulating layer and the third insulating layer do not comprise a fibrous base material.

7. A laminate according to claim 1, wherein the second resin composition contains an inorganic filler, and the content of the inorganic filler is 25 to 250 mass% based on the total amount of the second resin composition excluding the inorganic filler, and the third resin composition contains an inorganic filler, and the content of the inorganic filler is 25 to 250 mass% based on the total amount of the third resin composition excluding the inorganic filler.

8. The laminate according to claim 1, wherein the second insulating layer and the third insulating layer are each a cured film.

9. The laminate according to claim 1, wherein the first insulating layer is a cured prepreg.

10. A metal-clad laminate comprising the laminate according to any one of claims 1 to 9 and a metal foil laminated on at least one main surface of the laminate.

11. The metal-clad laminate of claim 10, wherein the metal foil comprises copper foil.

12. A wiring board comprising the laminate according to any one of claims 1 to 9, and wiring arranged on at least one main surface of the laminate.

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