Method for manufacturing circuit board

Abstract

To provide a method for manufacturing a circuit board which can suppress occurrence of voids in a cavity where a component is stored.SOLUTION: A method for manufacturing a circuit board using a core substrate where a cavity is formed, a temporary fixing film, and a resin sheet including a support and a resin composition layer includes: a step (2) of placing a component in the cavity; a step (3) of pressing the support by a rigid member, and laminating the resin sheet and the core substrate; and a step (4) of curing the resin composition layer, in this order. The method includes or not include a step (5) of pressing the support by an elastic member so that the resin composition layer and the core substrate are joined to each other, between the step (2) and the step (3). In the step (3), a product of pressing force of pressing the support by the rigid member and pressing time is within a specific range. In the step (5), a product of pressing force of pressing the support by the elastic member and pressing time satisfies a specific condition.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a circuit board. [Background technology]

[0002] Components such as bare chips and chip capacitors may be mounted on a circuit board provided in a semiconductor device. Such components may be embedded inside the circuit board to meet the demands for higher functionality and smaller size (Patent Document 1). For example, when manufacturing a high-performance CPU, it is desirable to embed the components inside a core board. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-216636 A Summary of the Invention [Problem to be solved by the invention]

[0004] A preferred method for embedding components using a resin composition is to laminate a resin sheet having a resin composition layer containing the resin composition on a core substrate having a cavity in which the components are housed. This method can shorten the tact time. However, this method can cause voids to occur in the cavity after the components are embedded.

[0005] The present invention has been devised in view of the above-mentioned problems, and has an object to provide a method for manufacturing a circuit board that can suppress the occurrence of voids in a cavity that houses a component. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result, have found that the above-mentioned problems can be solved by appropriately adjusting a pressing member for pressing the support for lamination and the pressing conditions using the pressing member in a step of laminating a resin sheet including a support and a resin composition layer and a core substrate, and have completed the present invention. That is, the present invention includes the following.

[0007] <1> A method for manufacturing a circuit board using a core substrate having a cavity penetrating the core substrate, a temporary fixing film, and a resin sheet including a support and a resin composition layer; The manufacturing method comprises: A step (1) of adhering a temporary fixing film to one side of a core substrate; (2) placing the part in the cavity; (3) pressing the support with a rigid member to laminate the resin sheet and the core substrate so that the resin composition layer and the core substrate are bonded; A step (4) of curing the resin composition layer; in this order; The manufacturing method may or may not include a step (5) between the step (2) and the step (3) of pressing the support with an elastic member so as to bond the resin composition layer and the core substrate; In step (3), the pressing force F with which the rigid member presses the support R and pressing time T R The product of H R But 200kgf sec / cm 2 That's it; When the manufacturing method includes the step (5), the pressing force F with which the elastic member presses the support in the step (5) E and pressing time T E The product of H E A method for producing a circuit board, wherein the following formula (I) is satisfied: 2×H E <H R (I) <2> The pressing temperature in step (3) is 50°C or higher and 140°C or lower. <1> A method for manufacturing the circuit board according to claim 1. <3> The pressing temperature in step (5) is 50°C or higher and 140°C or lower. <1> or <2> A method for manufacturing the circuit board according to claim 1. <4> The resin composition layer contains (A) a curable resin and (B) an inorganic filler; <1> ~ <3> 13. A method for manufacturing a circuit board according to claim 12. <5> The amount of the (B) inorganic filler contained in the resin composition layer is 65% by mass or more relative to 100% by mass of the non-volatile components in the resin composition layer. <4> A method for manufacturing the circuit board according to claim 1. <6> The average linear thermal expansion coefficient of the cured product obtained by curing the resin composition layer at 200°C for 90 minutes is less than 25 ppm / °C at 25°C to 150°C. <1> ~ <5> 13. A method for manufacturing a circuit board according to claim 12. <7> The ratio of the volume of the part placed in the cavity to the volume of the cavity is 30 volume % or more. <1> ~ <6> 13. A method for manufacturing a circuit board according to claim 12. Effect of the Invention

[0008] According to the present invention, it is possible to provide a method for manufacturing a circuit board that can suppress the occurrence of voids in a cavity that houses a component. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view for explaining step (1) of the first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic cross-sectional view for explaining the step (2) of the first embodiment of the present invention. [Diagram 3] FIG. 3 is a schematic cross-sectional view for explaining the step (3) of the first embodiment of the present invention. [Figure 4] FIG. 4 is a schematic cross-sectional view for explaining the step (3) of the first embodiment of the present invention. [Diagram 5] FIG. 5 is a schematic cross-sectional view for explaining the step (4) of the first embodiment of the present invention. [Figure 6]FIG. 6 is a schematic cross-sectional view for explaining step (5) of the second embodiment of the present invention. [Figure 7] FIG. 7 is a schematic plan view showing the state of the core substrate as viewed from the thickness direction, for explaining the positions of the cavities formed in the first embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described below with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and may be modified and implemented as desired without departing from the scope of the claims and their equivalents.

[0011] In the following description, unless otherwise specified, the "in-plane direction" refers to a direction perpendicular to the thickness direction.

[0012] <Outline of Circuit Board Manufacturing Method> The method for manufacturing a circuit board of the present invention is a method for manufacturing a circuit board using a core substrate, a temporary fixing film, and a resin sheet. The core substrate has a cavity penetrating the core substrate. The resin sheet includes a support and a resin composition layer. The resin composition layer includes a resin composition, and preferably includes only the resin composition.

[0013] This manufacturing method is A step (1) of adhering a temporary fixing film to one side of a core substrate; (2) placing the part in the cavity; (3) pressing the support with a rigid member to laminate the resin sheet and the core substrate so that the resin composition layer and the core substrate are bonded; A step (4) of curing the resin composition layer; Includes, in this order.

[0014] In addition, in this manufacturing method, between the step (2) and the step (3), Step (5) of pressing the support with an elastic member so that the resin composition layer and the core substrate are bonded to each other. It may or may not include.

[0015] In step (3), the rigid member presses the support with a pressing force F R and pressing time T R Product of H R But 200kgf sec / cm 2 In addition, when the manufacturing method includes the step (5), the pressing force F with which the elastic member presses the support in the step (5) is E and pressing time T E Product of H E But the product H R and the following formula (I) is satisfied. 2×H E <H R (I)

[0016] According to the above-described method for manufacturing a circuit board, it is possible to manufacture a circuit board in which the generation of voids in the cavity in which the components are housed is suppressed.

[0017] The inventors speculate that the mechanism by which the above-mentioned effects are obtained is as follows. However, the technical scope of the present invention is not limited to the mechanism described below.

[0018] In general, when a core substrate having a cavity is laminated with a resin sheet, the cavity is filled with the resin composition by flowing into the cavity not only the resin composition contained in the resin composition layer in the front portion facing the cavity, but also the resin composition contained in the resin composition layer in the peripheral portion around the cavity. That is, the resin composition is pushed in the thickness direction from the front portion of the resin composition layer facing the cavity toward the cavity. At the same time, the resin composition moves in the in-plane direction from the portion (peripheral portion) of the resin composition layer around the cavity that receives the pressing force toward the cavity, and the resin composition is pushed into the cavity. Then, the resin composition is filled into the cavity by these resin compositions.

[0019] Conventionally, in order to ensure that the resin sheet sufficiently follows the unevenness of the surface of the core substrate, when laminating the core substrate and the resin sheet, the resin sheet is generally pressed by an elastic member. When pressing, the elastic member presses the resin sheet while deforming according to the shape of the core substrate. However, when a core substrate having a cavity is used, the elastic member that receives pressure during pressing deforms to follow the cavity, narrowing the passage of the resin composition moving from the periphery of the cavity toward the cavity. As a result, the resin composition supplied to the cavity is insufficient, causing voids.

[0020] Generally, the greater the pressure applied during pressing, the greater the degree of deformation of the elastic member. Therefore, if the pressing force is simply increased, the stress for moving the resin composition becomes greater, but the passage for the resin composition becomes narrower due to the greatly deformed elastic member, so that the resin composition supplied to the cavity is ultimately insufficient. Therefore, it is difficult to suppress voids by simply increasing the pressing force.

[0021] In contrast, in the method for manufacturing a circuit board of the present invention, a rigid member is used to sufficiently press the resin sheet. The rigid member generally does not deform even when subjected to stress, and therefore the resin composition can be uniformly pressed without narrowing the passage of the resin composition. The resin composition that is sufficiently pressed under uniform pressure without narrowing the passage can be smoothly filled into the cavity, thereby suppressing voids.

[0022] The lamination of the core substrate and the resin sheet is preferably performed by a vacuum lamination method using a laminator. As the laminator, a commercially available product such as "CVP700" manufactured by Nikko Materials Co., Ltd. may be used.

[0023] <First embodiment: embodiment not including step (5)> Hereinafter, a method for manufacturing a circuit board according to a first embodiment of the present invention will be described with reference to the drawings. In the first embodiment described below, a manufacturing method that does not include a step (5) of pressing the support of the resin sheet with an elastic member between the steps (2) and (3) will be described.

[0024] (Explanation of step (1)) 1 is a schematic cross-sectional view for explaining step (1) of the first embodiment of the present invention. As shown in FIG. 1, the method for manufacturing a circuit board according to the present embodiment includes step (1) of adhering a temporary fixing film 30 to one surface 10D of a core substrate 10 having a cavity 20 formed therein.

[0025] Core substrate 10 has, as its main surfaces, a first surface 10U and a second surface 10D on the opposite side to first surface 10U. Core substrate 10 has a cavity 20 formed therein, penetrating core substrate 10. Typically, cavity 20 penetrates core substrate 10 in the thickness direction, and is open to both first surface 10U and second surface 10D.

[0026] Examples of the core substrate 10 include a glass epoxy substrate, a metal substrate, a polyester substrate, a polyimide substrate, a BT resin substrate, and a thermosetting polyphenylene ether substrate, and the like, with a glass epoxy substrate being preferred. The core substrate 10 may also include a conductor layer (not shown). This conductor layer may be patterned. The conductor layer can be used as circuit wiring such as via wiring and surface wiring. The core substrate 10 also includes intermediate products on which an insulating layer and / or a conductor layer is to be further formed, for example, when manufacturing a semiconductor chip package or a printed wiring board.

[0027] The thickness of the core substrate 10 can be set according to the size of the circuit substrate to be manufactured. Usually, the thickness of the core substrate 10 corresponds to the depth of the cavity 20. Generally, the deeper the cavity 20, the more likely voids are to occur in the cavity 20. That is, generally, the larger the component, the more likely voids are to occur in a cavity deep enough to accommodate the large component, and therefore, the thick core substrate that can have the deep cavity tends to be more likely to generate voids. In contrast, the manufacturing method according to the present embodiment makes it possible to suppress the generation of voids even under conditions in which voids were easily generated in the past. From the viewpoint of utilizing the advantage of being able to suppress the generation of such voids, it is preferable to adopt a core substrate 10 having a deep cavity 20 in which voids were easily generated in the past, and therefore, it is preferable that the thickness of the core substrate 10 is large.

[0028] Specifically, the thickness of the core substrate 10 may be, for example, 50 μm or more, 100 μm or more, or 200 μm or more. In particular, from the viewpoint of utilizing the effect of suppressing voids even when using a thick core substrate 10 in which voids were easily generated in the past, the thickness of the core substrate 10 is preferably 400 μm or more, more preferably 500 μm or more, and even more preferably 600 μm or more. In addition, from the viewpoint of thinning the circuit board, the upper limit of the thickness of the core substrate 10 is preferably 3 mm or less, more preferably 2.5 mm or less, and even more preferably 2 mm or less. Usually, the thickness of the core substrate 10 coincides with the depth of the cavity 20 as described above, so the range of the depth of the cavity 20 may be the same as the range of the thickness of the core substrate 10.

[0029] Only one cavity 20 may be formed in the core substrate 10, or multiple cavities 20 may be formed with intervals between them. The pitch between the cavities 20 depends on the opening dimensions of the cavity 20 itself, but from the viewpoint of miniaturization of the circuit board, it is preferably 10 mm or less, more preferably 9 mm or less, and even more preferably 8 mm or less. The lower limit is, for example, 1 mm or more, 2 mm or more, etc. The pitch between the cavities 20 may be the same or different across the core substrate 10.

[0030] The dimensions of cavity 20 are set so that a component (not shown in FIG. 1) can be housed in cavity 20. In general, the smaller openings 21 and 22 of cavity 20, the more likely voids are to occur in cavity 20. From the viewpoint of utilizing the advantage of being able to suppress the occurrence of voids, a cavity 20 with a small opening diameter that is close to the size of an embedded component in which voids were likely to occur in conventional technology is preferred. The dimensions of cavity 20 may be the same or different across core substrate 10.

[0031] The opening shape of the cavity 20 is not particularly limited. The opening shape of the cavity 20 refers to the shape of the openings 21 and 22 of the cavity 20 when the core substrate 10 is viewed from the thickness direction. Examples of the opening shape of the cavity 20 include a rectangle, a circle, a substantially rectangle, and a substantially circle. The opening shape of the cavity 20 may be the same or different throughout the core substrate 10.

[0032] The core substrate 10 can be manufactured by a method that includes forming the cavity 20 in the pre-formed core substrate 10. The cavity 20 can be formed by a method that uses, for example, a drill, a laser, a plasma, or an etching medium, depending on the composition of the core substrate 10.

[0033] The step (1) includes adhering a temporary fixing film 30 to one surface 10D of the core substrate 10. By adhering the temporary fixing film 30, one opening 22 of the cavity 20 is closed by the temporary fixing film 30. Therefore, the component placed in the cavity 20 can be stably held in the cavity 20.

[0034] The temporary fixing film 30 preferably has an adhesive surface 30U having sufficient adhesiveness to hold the component in order to stably hold the component in the cavity 20. Examples of such a temporary fixing film 30 include "PFDKE-1525TT" (polyimide film with adhesive) manufactured by Arisawa Manufacturing Co., Ltd. and UC series (UV tape for wafer dicing) manufactured by Furukawa Electric Co., Ltd.

[0035] (Explanation of step (2)) 2 is a schematic cross-sectional view for explaining step (2) of the first embodiment of the present invention. As shown in FIG. 2, the method for manufacturing a circuit board according to this embodiment includes, after step (1), step (2) of placing a component 40 in a cavity 20.

[0036] Usually, the component 40 is placed in the cavity 20 through the opening 21 opened in the first surface 10U, and the component 40 is placed on the bottom of the cavity 20. When the temporary fixing material 30 having an adhesive surface 30U is provided, the component 40 adheres to the adhesive surface 30U of the temporary fixing film 30 exposed through the cavity 20, and is fixed.

[0037] As the component 40, an appropriate electronic component is usually selected depending on the desired characteristics. Examples of the component 40 include passive components such as capacitors, inductors, and resistors; active components such as semiconductor chips; etc. The same component 40 may be attached to all the cavities 20, or different components 40 may be attached to each cavity 20.

[0038] The ratio of the volume of the part 40 placed in the cavity 20 to the volume of the cavity 20 is preferably within a specific range. Hereinafter, the ratio may be referred to as the "occupancy ratio". Specifically, the occupancy ratio is preferably 15 volume% or more, more preferably 20 volume% or more, even more preferably 25 volume% or more, and preferably 60 volume% or less, more preferably 50 volume% or less, and even more preferably 45 volume% or less. In general, when the part 40 is stored in the cavity 20, the passage through which the resin composition can flow in the cavity 20 becomes narrower by the part 40, and thus the pressure loss in the passage becomes large. Therefore, it becomes difficult for the resin composition to enter the cavity 20 by the part 40, and as a result, voids are easily generated. Conventionally, when the occupancy ratio of the part 40 to the cavity 20 is large as described above, it was difficult to suppress the voids, but according to the manufacturing method of this embodiment, it is possible to suppress the generation of such voids. From the viewpoint of utilizing the advantage of being able to suppress the occurrence of voids in this way, it is preferable that the occupancy rate of the component 40 with respect to the cavity 20 be within the above-mentioned range.

[0039] Typically, the thickness of the component 40 is equal to or smaller than the depth of the cavity 20. Unless otherwise specified, the "thickness of the component 40" refers to the dimension of the component 40 in the depth direction of the cavity 20, and therefore refers to the dimension of the component 40 in the thickness direction of the core substrate 10. In one example, the range of the ratio of the thickness of the component 40 to the depth of the cavity 20 (thickness of the component 40 / depth of the cavity 20) is preferably 0.01 or more, more preferably 0.1 or more, even more preferably 0.2 or more, even more preferably 0.3 or more, even more preferably 0.4 or more, and is preferably 1.0 or less, more preferably less than 1.0, even more preferably less than 0.8, and even more preferably less than 0.6. Generally, the depth of cavity 20 corresponds to the thickness of core substrate 10, so that the range of the ratio of the thickness of component 40 to the thickness of core substrate 10 (thickness of component 40 / thickness of core substrate 10) can be the same as the above-mentioned range of the ratio of the thickness of component 40 to the depth of cavity 20 (thickness of component 40 / depth of cavity 20).

[0040] (Explanation of step (3)) 3 and 4 are schematic cross-sectional views for explaining step (3) of the first embodiment of the present invention. As shown in FIG. 3, the manufacturing method of the circuit board according to this embodiment includes step (3) of laminating a resin sheet 50 including a support 51 and a resin composition layer 52 and a core substrate 10 after step (2). This lamination is performed by pressing the support 51 with a rigid member 60 as shown by the arrow A1 so that the resin composition layer 52 and the core substrate 10 are bonded. This lamination causes a part of the resin composition contained in the resin composition layer 52 to enter the cavity 20. Therefore, as shown in FIG. 4, the cavity 20 is filled with the resin composition, and the resin composition layer 52 is formed in the cavity 20. Therefore, the component 40 in the cavity 20 can be embedded by the resin composition layer 52. In addition, usually, another part of the resin composition contained in the resin composition layer 52 does not enter the cavity 20, so that the resin composition layer 52 can also be formed on the first surface 10U of the core substrate 10. When the core substrate 10 has a conductor layer (not shown) such as a circuit wiring on the first surface 10U in contact with the resin composition layer 52, the conductor layer can be embedded in the resin composition layer 52.

[0041] The rigid member 60 is made of a rigid material. As the rigid material, a material having a rigidity sufficient to fill the cavity 20 of the core substrate 10 with a resin composition can be used. As the rigid material, a material that does not deform when the support 51 is pressed is preferable.

[0042] As the rigid material, a material having a large elastic modulus (Young's modulus) can be used. The elastic modulus of the rigid material is usually 1 GPa or more, preferably 10 GPa or more, more preferably 50 GPa or more, and preferably 500 GPa or less, more preferably 400 GPa or less, and even more preferably 300 GPa or less. The elastic modulus of the rigid material can be measured by a free resonance method at 23°C.

[0043] The rigid material is preferably a metal material. Examples of the metal material include iron, aluminum, and alloys thereof. Examples of the alloy include stainless steel. Among them, stainless steel is preferable because of its excellent rust resistance.

[0044] Usually, the rigid member 60 has a flat, planar pressing surface 60D. Then, pressing is performed so that this pressing surface 60D is in direct contact with the support 51 of the resin sheet 50. Two members are in "direct" contact with each other means that there is no other member between the two members, unless otherwise specified. When the support 51 is pressed with such a flat pressing surface 60D, pressure can be applied uniformly in the in-plane direction to the resin composition layer 52. Therefore, uniform pressure can be applied not only to the front portion facing the opening 21 of the cavity 20 but also to the wide peripheral portion around the opening 21, and the resin composition can be efficiently moved from the resin composition layer 52 in those portions to the cavity 20. In addition, by applying pressure uniformly, it is possible to suppress the occurrence of places with locally low pressure in the cavity 20. Therefore, voids can be particularly effectively suppressed. Furthermore, usually, the flatness of the surface of the resin composition layer 52 (the surface in contact with the support 51) can be increased.

[0045] Usually, the pressing surface 60D of the rigid member 60 is formed of a rigid material and has high rigidity. In one example, the Vickers hardness of the pressing surface 60D of the rigid member 60 is preferably 150HV or more, more preferably 200HV or more, even more preferably 300HV or more, and is preferably 1000HV or less, more preferably 700HV or less. The Vickers hardness can be measured at 23°C in accordance with JIS Z 2244.

[0046] In step (3), the above-mentioned rigid member 60 applies a pressing force F R and pressing time T R The product H R The support 51 is pressed under the condition that the product H R The range is usually 200 kgf sec / cm 2More than 500kgf sec / cm, preferably 500kgf sec / cm 2 More preferably, 1,000 kgf sec / cm 2 More preferably, 1,500 kgf sec / cm 2 More than 4,000 kgf sec / cm is especially preferable. 2 The upper limit is, for example, 10,0000 kgf sec / cm 2 Below, 8,000kgf·sec / cm 2 Below, 6,000kgf·sec / cm 2 It can be the following: R In the case where the rigid member 60 presses the support 51 under the condition that the thickness of the support 51 falls within the above-mentioned range, the generation of voids can be suppressed. In addition, by pressing under such conditions, in the case where the core substrate 10 has a conductor layer (not shown) such as a circuit wiring on the first surface 10U that contacts the resin composition layer 52, the conductor layer can be embedded particularly well with the resin composition layer 52.

[0047] In step (3), the pressing force F of the rigid member 60 pressing the support 51 R is the pressing force F R and pressing time T R The product H R can be set to fall within the above range. In particular, from the viewpoint of smoothly filling the cavity 20, the pressing force F R The range is preferably 2kgf / cm 2 More preferably, 3kgf / cm 2 More preferably, 5kgf / cm 2 The upper limit is, for example, 100 kgf / cm 2 Below, 40kgf / cm 2 Below 20kgf / cm 2 It could be the following, etc.

[0048] In step (3), the rigid member 60 presses the support 51 for a pressing time T R is the pressing force F R and pressing time T R The product H R can be set to fall within the above range. In particular, from the viewpoint of smoothly filling the cavity 20, the pressing time TR The range is preferably 10 seconds or more, more preferably 20 seconds or more, particularly preferably 30 seconds or more, and is preferably 30 minutes or less, more preferably 20 minutes or less, particularly preferably 10 minutes or less.

[0049] The pressing of the support 51 by the rigid member 60 in step (3) is preferably performed at a pressing temperature higher than room temperature. By heating the resin composition layer 52 to an appropriate pressing temperature, the viscosity of the resin composition is reduced and the fluidity is improved, so that the resin composition can be smoothly filled into the cavity 20. Therefore, the generation of voids can be effectively suppressed. The pressing temperature is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 70°C or higher, and is preferably 140°C or lower, more preferably 130°C or lower, and even more preferably 120°C or lower. The specific pressing temperature is preferably set so that the viscosity of the resin composition can be reduced depending on the composition of the resin composition contained in the resin composition layer 52. Usually, the temperature of the rigid member 60 is adjusted to the pressing temperature.

[0050] The pressing of the support 51 by the rigid member 60 in step (3) is preferably carried out in a reduced pressure environment. The range of the vacuum degree of the reduced pressure environment is preferably 20 hPa or less, more preferably 15 hPa or less, even more preferably 10 hPa or less, and particularly preferably 5 hPa or less. The lower limit is ideally 0 hPa or more, but is usually 0.1 hPa or more. When lamination is carried out in such a high level of vacuum, the generation of voids can be effectively suppressed.

[0051] (Explanation of step (4)) 5 is a schematic cross-sectional view for explaining step (4) of the first embodiment of the present invention. The method for producing a circuit board according to this embodiment includes step (4) of curing the resin composition layer 52 after step (3). By curing the resin composition layer 52, an insulating layer 70 can be obtained as shown in FIG. 5. Thus, a circuit board 100 including a core substrate 10, components 40, and insulating layer 70 can be produced. Since the insulating layer 70 is a cured layer obtained by curing the resin composition layer 52, it contains a cured product of the resin composition, and preferably contains only the cured product of the resin composition.

[0052] For curing the resin composition layer 52, an appropriate method can be adopted depending on the composition of the resin composition contained in the resin composition layer 52. For example, when a thermosetting resin composition is used, the resin composition can be cured by heating.

[0053] The curing conditions for the resin composition layer 52 may vary depending on the composition of the resin composition, but the curing temperature is preferably in the range of 120°C to 240°C (more preferably in the range of 150°C to 220°C, and particularly preferably in the range of 160°C to 210°C), and the curing time is preferably in the range of 5 minutes to 180 minutes (more preferably in the range of 10 minutes to 150 minutes, and particularly preferably in the range of 15 minutes to 120 minutes).

[0054] Before curing, the resin composition layer 52 may be preheated at a temperature lower than the curing temperature. For example, prior to curing, the resin composition layer 52 may be preheated at a temperature of 50° C. or higher and lower than 120° C. (preferably 60° C. or higher and 110° C. or lower, more preferably 70° C. or higher and 100° C. or lower) for 5 minutes or more (preferably 5 to 150 minutes, more preferably 15 to 120 minutes).

[0055] (Optional process description) The method for producing a circuit board according to the first embodiment of the present invention may further include any step in combination with the steps described above. For example, the method for producing a circuit board may include a step of peeling off the temporary fixing film after step (4).

[0056] The method for producing a circuit board may include, for example, a step of peeling off the support of the resin sheet after step (3). The support may be peeled off before step (4) or after step (4). Furthermore, when the support includes a metal foil, the support may not be peeled off and may be used to form a conductor layer as described below.

[0057] The method for manufacturing a circuit board may include, for example, a step of forming a conductor layer on an insulating layer. There is no limitation on the method for forming the conductor layer. For example, when a resin sheet provided with a support containing a metal foil is used in step (4), the conductor layer as a circuit may be formed by a subtractive method or a modified semi-additive method using the metal foil.

[0058] In the subtractive method, a circuit is usually formed by selectively removing unnecessary parts (non-circuit forming parts) of the metal foil by a removal method such as etching. The circuit formation by the subtractive method can be carried out, for example, by a method including, in this order: i) providing an etching resist on the surface of the metal foil (i.e., the surface opposite to the insulating layer), ii) exposing and developing the etching resist to form a wiring pattern, iii) etching and removing the exposed metal foil parts, and iv) removing the etching resist.

[0059] In the modified semi-additive method, the non-circuit forming portion of the metal foil is usually protected by a plating resist, and a metal such as copper is thickly applied to the circuit forming portion by electrolytic plating, and then the plating resist is removed, and the metal foil other than the circuit forming portion is removed by etching to form a circuit. The circuit formation by the modified semi-additive method can be carried out, for example, by a method including the following in this order: i) providing a plating resist on the surface of the metal foil (i.e., the surface opposite to the insulating layer), ii) exposing and developing the plating resist to form a wiring pattern, iii) electrolytic plating through the plating resist, iv) removing the plating resist, and v) etching and removing the metal foil other than the circuit forming portion. If the metal foil is thick, the entire surface of the metal foil may be thinned by a removal method such as etching before the above i) so that the metal foil has a desired thickness.

[0060] The conductor layer may be formed without using a metal foil. Examples of the method for forming such a conductor layer include a plating method, a sputtering method, and a vapor deposition method. For example, a conductor layer having a desired wiring pattern may be formed by plating the surface of the insulating layer by an appropriate method such as a semi-additive method or a full-additive method.

[0061] The method for manufacturing a circuit board may include, for example, a step of drilling holes in an insulating layer. This step allows holes such as via holes and through holes to be formed in the insulating layer. As a specific example, when a hole that communicates from the surface of the insulating layer to a component is formed in the insulating layer, a conductive layer on the insulating layer and the component can be electrically connected by forming a conductive layer in the hole, so that interlayer connection through the hole can be realized. As another specific example, when a hole that communicates from the surface of the insulating layer to the circuit wiring of the core substrate is formed in the insulating layer, a conductive layer can be formed in the hole, so that the conductive layer on the insulating layer and the circuit wiring of the core substrate can be electrically connected, so that interlayer connection through the hole can be realized. Examples of methods for forming holes include laser irradiation, etching, mechanical drilling, and the like. The dimensions and shape of the hole can be appropriately determined according to the design of the circuit substrate.

[0062] When a hole is formed in an insulating layer, a smear (resin residue) may be formed in the hole. Therefore, the manufacturing method of a circuit board may include, for example, a step of removing the smear in the hole after the hole is formed. This step may be called a desmear step. The desmear treatment may be, for example, a wet desmear treatment using a swelling liquid, an oxidizing agent, and a neutralizing liquid, or may be a dry desmear treatment such as a plasma treatment. The desmear treatment may cause the surface of the insulating layer to be roughened.

[0063] In the method for manufacturing a circuit board, for example, before forming a conductor layer on the insulating layer, a roughening treatment may be performed on the insulating layer. This roughening treatment usually roughens the surface of the insulating layer including the inside of the holes. The roughening treatment may be either a dry or wet roughening treatment. An example of the dry roughening treatment is a plasma treatment. An example of the wet roughening treatment is a method in which a swelling treatment using a swelling liquid, a roughening treatment using an oxidizing agent, and a neutralization treatment using a neutralizing liquid are performed in this order.

[0064] The method for producing a circuit board may, for example, repeatedly form a conductor layer on an insulating layer and then form an optional insulating layer to produce a circuit board having a multilayer structure such as a multilayer printed wiring board.

[0065] In the method for manufacturing the circuit board, for example, a conductor layer may be formed on the second surface 10D of the core substrate 10 opposite to the first surface 10U laminated with the resin sheet 50. The formation of the conductor layer and the formation of an optional insulating layer on the second surface 10D may be repeated. At this time, any optional treatment such as drilling, desmearing, roughening, etc. may be performed on the optional insulating layer, as necessary.

[0066] In the first embodiment, a method for manufacturing a circuit board is described that does not include step (5) of pressing the support of the resin sheet with an elastic member before step (3), but the manufacturing method may include a step of pressing the support of the resin sheet with any pressing member other than the elastic member before step (3). However, it is preferable that the manufacturing method for a circuit board according to this embodiment does not include a step of pressing the support of the resin sheet with any pressing member as described above before step (3). Therefore, it is preferable that the pressing of the support first performed after step (2) is the pressing described in step (3) with a rigid member.

[0067] (Description of the circuit board to be manufactured) According to the manufacturing method of the first embodiment described above, a circuit board can be manufactured that includes a core substrate having a cavity, a component housed in the cavity, and an insulating layer filling the cavity. The insulating layer may be formed not only in the cavity, but also on the surface of the core substrate outside the cavity. In this circuit board, the component in the cavity is embedded in the insulating layer filling the cavity.

[0068] In the cavities of the manufactured circuit board, the occurrence of voids as spaces where no components or insulating layers are present is suppressed. Therefore, for example, when the circuit board has a plurality of cavities in which components are housed, the number of cavities in which voids are occurring can be reduced, and preferably, the cavities in which voids are occurring can be eliminated.

[0069] The insulating layer included in the circuit board preferably has a small average linear thermal expansion coefficient. The specific range of the average linear thermal expansion coefficient of the insulating layer can usually be the same as the range of the average linear thermal expansion coefficient of the cured product obtained by curing the resin composition layer of the resin sheet described later under the curing conditions of 200 °C for 90 minutes, from 25 °C to 150 °C. When the insulating layer has such a small average linear thermal expansion coefficient, warping of the circuit board can be suppressed. Also, generally, in order to obtain an insulating layer having such a small average linear thermal expansion coefficient, it is required that the insulating layer contains an inorganic filler. However, such an insulating layer containing an inorganic filler has conventionally tended to generate voids. On the other hand, according to the manufacturing method according to the present embodiment, even when an insulating layer having such a small average linear thermal expansion coefficient is adopted, generation of voids can be suppressed.

[0070] The average linear thermal expansion coefficient of the insulating layer can be measured by performing thermomechanical analysis by the tensile loading method using a thermomechanical analyzer. The measurement is performed under the measurement conditions of a load of 1 g and a heating rate of 5 °C / min, and can be measured in the temperature range from 25 °C to 150 °C. As the specific measurement operation, those described in the <CTE measurement test> of the examples described later can be adopted.

[0071] Examples of the circuit board include printed wiring boards and semiconductor chip packages. Examples of the semiconductor chip package include FC-CSP, MIS-BGA package, ETS-BGA package, Fan-out type WLP (Wafer Level Package), Fan-in type WLP, Fan-out type PLP (Panel Level Package), and Fan-in type PLP. However, the circuit board is not limited to those exemplified here. Also, in these circuit boards, the insulating layer may include, for example, an interlayer insulating layer, a redistribution formation layer, a mold underfill layer, a solder resist layer, and the like.

[0072] <Second Embodiment: Embodiment including Step (5)> A method for manufacturing a circuit board according to a second embodiment of the present invention will be described below with reference to the drawings. In the second embodiment described below, a manufacturing method including a step (5) of pressing the support of the resin sheet with an elastic member between steps (2) and (3) will be described.

[0073] (Explanation of step (1)) 1, the method for manufacturing a circuit board according to the second embodiment includes a step (1) of adhering a temporary fixing film 30 to one surface 10D of a core substrate 10 having a cavity 20 formed therein. The step (1) according to the second embodiment can be carried out in the same manner as the step (1) according to the first embodiment, and can provide the same advantages as those described in the first embodiment.

[0074] (Explanation of step (2)) The method for manufacturing a circuit board according to the second embodiment includes, after step (1), step (2) of placing a component 40 in cavity 20, as shown in Fig. 2. Step (2) according to the second embodiment can be performed in the same manner as step (2) according to the first embodiment, and can provide the same advantages as those described in the first embodiment.

[0075] (Explanation of step (5)) FIG. 6 is a schematic cross-sectional view for explaining step (5) of the second embodiment of the present invention. As shown in FIG. 6, the manufacturing method of the circuit board according to this embodiment includes a step (5) of pressing the support 51 of the resin sheet 50 with an elastic member 80 as shown by the arrow A2 so that the resin composition layer 52 of the resin sheet 50 and the core substrate 10 are bonded after step (2) and before step (3). This pressing causes the resin composition layer 52 to adhere to the first surface 10U of the core substrate 10, and a part of the resin composition contained in the resin composition layer 52 enters the cavity 20. However, unlike step (3) described in the first embodiment, the resin composition that enters the cavity 20 fills a part of the cavity 20 and does not usually fill the entire cavity 20. In this embodiment, the part of the cavity 20 that is not filled with the resin composition in step (5) is filled in step (3) described later.

[0076] The elastic member 80 is made of an elastic material. The elastic material may be a material having enough elasticity to press the support 51 while deforming in response to pressure when pressed. The elastic material may be a material having a small elastic modulus (Young's modulus). The elastic modulus of the elastic material is usually 0.1 MPa or more, preferably 1 MPa or more, more preferably 2 MPa or more, and usually 100 MPa or less, preferably 90 MPa or less, more preferably 80 MPa or less. The elastic modulus E [MPa] of the elastic material is determined by measuring the durometer hardness A [Hs] at 23°C and using the formula (M1) shown below. An example of the elastic material is rubber.

[0077]

number

[0078] The elastic member 80 may be, for example, a plate or sheet made of an elastic material. The elastic member 80 has a pressing surface 80D for pressing the support 51 of the resin sheet 50. Pressing is performed so that the pressing surface 80D is in direct contact with the support 51 of the resin sheet 50. When such pressing is performed, the resin sheet 50 can sufficiently follow the surface shape of the first surface 10U of the core substrate 10, so that the adhesion between the first surface 10U of the core substrate 10 and the resin composition layer 52 can be improved. In addition, when the core substrate 10 has a conductor layer (not shown) such as a circuit wiring on the first surface 10U, the conductor layer can be embedded by the resin composition layer 52. At this time, the resin sheet 50 can sufficiently follow the surface shape of the core substrate 10, so that good embedding properties can be achieved.

[0079] In the step (5), the elastic member 80 presses the support 51 with a pressing force F E and pressing time T E The product H E is carried out so as to satisfy the following formula (I). 2×H E <H R (I) Here, HR is the pressing force F with which the rigid member presses the support in step (3), as described above. R and pressing time T R Product of H R Represents.

[0080] In step (5), the pressing force F of the elastic member 80 pressing the support 51 E is the pressing force F E and pressing time T E The product H E can be set so as to satisfy the above formula (I). In particular, from the viewpoint of increasing the adhesion between the first surface 10U of the core substrate 10 and the resin composition layer 52, the pressing force F E The range is preferably 1 kgf / cm 2 More preferably, 2kgf / cm 2 More preferably, 3kgf / cm 2 More than 20kgf / cm 2 Less than or equal to 18kgf / cm 2 Less than 15kgf / cm, more preferably 15kgf / cm 2 The following is the result.

[0081] In step (5), the elastic member 80 presses the support 51 for a pressing time T E is the pressing force F E and pressing time T E The product H E can be set so as to satisfy the above formula (I). In particular, from the viewpoint of increasing the adhesion between the first surface 10U of the core substrate 10 and the resin composition layer 52, the pressing time T E The range is preferably 1 second or more, more preferably 2 seconds or more, even more preferably 5 seconds or more, and is preferably 60 seconds or less, more preferably 50 seconds or less, and particularly preferably 40 seconds or less.

[0082] The pressing of the support 51 by the elastic member 80 in step (5) is preferably performed at a pressing temperature higher than room temperature. The range of the pressing temperature in step (5) may be the same as the range of the pressing temperature in step (3) described in the first embodiment. In this case, the pressing temperature in step (5) and the pressing temperature in step (3) may be the same or different. Usually, the temperature of the elastic member 80 is adjusted to the above-mentioned pressing temperature.

[0083] The pressing of the support 51 by the elastic member 80 in step (5) is preferably performed in a reduced pressure environment. The range of the vacuum degree of the reduced pressure environment in step (5) may be the same as the range of the vacuum degree in step (3) described in the first embodiment. In this case, the vacuum degree in step (5) and the vacuum degree in step (3) may be the same or different. When pressing is performed in such a high level of vacuum, the generation of voids can be effectively suppressed.

[0084] (Explanation of step (3)) The method for manufacturing a circuit board according to the second embodiment includes a step (3) of laminating the resin sheet and the core substrate by pressing the support 51 with a rigid member 60 after the step (5) so that the resin composition layer 52 of the resin sheet 50 and the core substrate 10 are bonded. By laminating in the step (3), the resin composition is filled in the portion of the cavity 20 that was not filled with the resin composition in the step (5), and thus, as shown in FIG. 4, the resin composition layer 52 is formed in the cavity 20. Thus, the component 40 in the cavity 20 can be embedded by the resin composition layer 52. Also, as in the first embodiment, the resin composition layer 52 can usually be formed on the first surface 10U of the core substrate 10 as well.

[0085] Step (3) according to the second embodiment can be carried out in the same manner as step (3) according to the first embodiment, and the same advantages as those described in the first embodiment can be obtained. R , pressing time T R , and their product H R The pressing temperature and the degree of vacuum in the pressing environment may be the same as those in the step (3) according to the first embodiment.

[0086] In this embodiment, since support 51 of resin sheet 50 is pressed by elastic member 80 in step (5) prior to step (3), filling of resin composition into cavity 20 usually proceeds halfway. Therefore, even if pressing by a rigid member is performed under milder conditions than in step (3) according to the first embodiment, it is possible to suppress voids.

[0087] Therefore, in the step (3) according to the second embodiment, the pressing force F R and pressing time T R The product H R The range may be the same as that in step (3) according to the first embodiment, but for example, 200 kgf sec / cm 2 Above, 210kgf·sec / cm 2 Above, 220kgf·sec / cm 2 or more than 230kgf sec / cm 2 It may be more than 1000kgf sec / cm 2 Below, 800kgf·sec / cm 2 or less than 600kgf sec / cm 2 The product H R When the amount of the filling material falls within the above range, the cavity 20 can be filled with less energy and in less time while suppressing the generation of voids.

[0088] In addition, the pressing force F with which the rigid member 60 presses the support 51 in the step (3) according to the second embodiment is R may be the same as in step (3) according to the first embodiment, but may be, for example, 1 kgf / cm 2 More than 2kgf / cm 2 or more than 3kgf / cm 2 It may be more than 50kgf / cm 2 Below 30kgf / cm 2 or less than 10kgf / cm 2 The pressing force F R When the amount of heat applied falls within the above range, the cavity 20 can be filled with less energy while suppressing the generation of voids.

[0089] Furthermore, in the step (3) according to the second embodiment, the pressing time T R The pressing time T may be the same as that of the step (3) according to the first embodiment, but may be, for example, 5 seconds or more, 10 seconds or more, or 20 seconds or more, and may be 5 minutes or less, 3 minutes or less, or 2 minutes or less. R When the filling time falls within the above range, the cavity 20 can be filled in a short time while suppressing the generation of voids.

[0090] (Explanation of step (4)) The method for manufacturing a circuit board according to the second embodiment includes, after step (3), step (4) of curing the resin composition layer 52. By curing the resin composition layer 52, an insulating layer 70 can be obtained, as shown in FIG. 5. Thus, a circuit board 100 including a core substrate 10, components 40, and insulating layer 70 can be manufactured. Step (4) according to the second embodiment can be performed in the same manner as step (4) according to the first embodiment, and the same advantages as those described in the first embodiment can be obtained.

[0091] (Optional process description) The method for producing a circuit board according to the second embodiment of the present invention may further include any step in combination with the steps described above. Examples of the optional steps that may be included in the method for producing a circuit board according to the second embodiment include the same optional steps as those that may be included in the method for producing a circuit board according to the first embodiment.

[0092] (Description of the circuit board to be manufactured) According to the manufacturing method of the second embodiment described above, it is possible to manufacture a circuit board similar to the manufacturing method of the first embodiment. Therefore, according to the manufacturing method of the circuit board of the second embodiment, it is possible to obtain the same advantages as the manufacturing method of the circuit board of the first embodiment.

[0093] <Explanation of resin sheet> The resin sheet used in the above-mentioned manufacturing method includes a support and a resin composition layer. Examples of the support include a film made of a plastic material, a metal foil, and a release paper, and a film made of a plastic material and a metal foil are preferred.

[0094] When a film made of a plastic material is used as the support, examples of the plastic material include polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as "PET") and polyethylene naphthalate (hereinafter sometimes abbreviated as "PEN"), polycarbonate (hereinafter sometimes abbreviated as "PC"), acrylics such as polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, polyimide, etc. Among these, polyethylene terephthalate and polyethylene naphthalate are preferred, and inexpensive polyethylene terephthalate is particularly preferred.

[0095] When a metal foil is used as the support, examples of the metal foil include copper foil, aluminum foil, etc., and copper foil is preferred. As the copper foil, a foil made of a single metal, copper, or an alloy of copper and another metal (e.g., tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) may be used.

[0096] The surface of the support to be bonded to the resin composition layer may be subjected to a matte treatment, a corona treatment, or an antistatic treatment.

[0097] As the support, a support with a release layer having a release layer on the surface to be bonded to the resin composition layer may be used. The release agent used in the release layer of the support with a release layer may be, for example, one or more release agents selected from the group consisting of alkyd resins, polyolefin resins, urethane resins, and silicone resins. The support with a release layer may be a commercially available product, for example, "SK-1", "AL-5", and "AL-7" manufactured by Lintec Corporation, "Lumirror T60" manufactured by Toray Industries, Inc., "Purex" manufactured by Teijin Limited, and "Unipeel" manufactured by Unitika Limited, which are PET films having a release layer mainly composed of an alkyd resin-based release agent.

[0098] The thickness of the support is not particularly limited, but is preferably in the range of 5 μm to 75 μm, and more preferably in the range of 10 μm to 60 μm. When a support with a release layer is used, it is preferable that the total thickness of the support with a release layer is in the above range.

[0099] The resin composition layer is a layer formed on a support and contains a resin composition. This resin composition layer preferably contains only the resin composition.

[0100] The resin composition layer and the resin composition as a material thereof usually contain (A) a curable resin. The (A) curable resin as the (A) component may be a thermosetting resin, a photocurable resin, or a combination thereof. In particular, the (A) curable resin preferably contains a thermosetting resin, or may contain only a thermosetting resin. The (A) curable resin may be used alone or in combination of two or more kinds.

[0101] As the thermosetting resin, a resin that can be cured when heat is applied can be used. Examples of the thermosetting resin include epoxy resin, phenol resin, active ester resin, carbodiimide resin, cyanate resin, acid anhydride resin, amine resin, benzoxazine resin, thiol resin, and radical polymerizable resin. The thermosetting resin may be used alone or in combination of two or more. Among them, the thermosetting resin preferably includes at least one selected from the group consisting of epoxy resin, phenol resin, active ester resin, carbodiimide resin, and radical polymerizable resin.

[0102] From the viewpoint of increasing the adhesion between the insulating layer and the conductor layer that can be formed on the insulating layer, it is preferable to use a combination of an epoxy resin and a resin that can react with the epoxy resin to harden the resin composition. The resin that can react with the epoxy resin to harden the resin composition may be referred to as a "hardening agent" hereinafter. Examples of hardening agents include phenolic resins, active ester resins, cyanate resins, carbodiimide resins, acid anhydride resins, amine resins, benzoxazine resins, and thiol resins. Among them, phenolic resins, active ester resins, and carbodiimide resins are preferred. In addition, the hardening agent may be used alone or in combination of two or more types.

[0103] The epoxy resin is a curable resin having an epoxy group. Examples of epoxy resins include bixylenol type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol AF type epoxy resins, dicyclopentadiene type epoxy resins, trisphenol type epoxy resins, naphthol novolac type epoxy resins, phenol novolac type epoxy resins, tert-butyl-catechol type epoxy resins, naphthalene type epoxy resins, naphthol type epoxy resins, anthracene type epoxy resins, glycidylamine type epoxy resins, glycidyl ester type epoxy resins, cresol novolac type epoxy resins, phenol aralkyl type epoxy resins, biphenyl type epoxy resins, linear aliphatic epoxy resins, epoxy resins having a butadiene structure, alicyclic epoxy resins, heterocyclic epoxy resins, spiro ring-containing epoxy resins, cyclohexane type epoxy resins, cyclohexane dimethanol type epoxy resins, naphthylene ether type epoxy resins, trimethylol type epoxy resins, tetraphenylethane type epoxy resins, isocyanurate type epoxy resins, and phenolphthalimidine type epoxy resins. The epoxy resin may be used alone or in combination of two or more kinds.

[0104] From the viewpoint of obtaining an insulating layer having excellent heat resistance, the epoxy resin preferably contains an aromatic structure. The aromatic structure is a chemical structure generally defined as aromatic, and includes polycyclic aromatic rings and aromatic heterocycles. Examples of epoxy resins containing an aromatic structure include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol AF type epoxy resins, dicyclopentadiene type epoxy resins, trisphenol type epoxy resins, naphthol novolac type epoxy resins, phenol novolac type epoxy resins, tert-butyl-catechol type epoxy resins, naphthalene type epoxy resins, naphthol type epoxy resins, anthracene type epoxy resins, bisxylenol type epoxy resins, glycidylamine type epoxy resins having an aromatic structure, glycidyl ester type epoxy resins having an aromatic structure, cresol novolac type epoxy resins, biphenyl type epoxy resins, linear aliphatic epoxy resins having an aromatic structure, epoxy resins having a butadiene structure having an aromatic structure, alicyclic epoxy resins having an aromatic structure, heterocyclic epoxy resins, spiro ring-containing epoxy resins having an aromatic structure, cyclohexane dimethanol type epoxy resins having an aromatic structure, naphthylene ether type epoxy resins, trimethylol type epoxy resins having an aromatic structure, and tetraphenylethane type epoxy resins having an aromatic structure.

[0105] The (A) curable resin preferably contains, as an epoxy resin, an epoxy resin having two or more epoxy groups in one molecule. The proportion of the epoxy resin having two or more epoxy groups in one molecule relative to 100% by mass of the non-volatile components of the epoxy resin is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more.

[0106] Epoxy resins include epoxy resins that are liquid at a temperature of 20° C. (hereinafter sometimes referred to as "liquid epoxy resins") and epoxy resins that are solid at a temperature of 20° C. (hereinafter sometimes referred to as "solid epoxy resins"). The resin composition may contain only liquid epoxy resins as the epoxy resin, or may contain only solid epoxy resins, or may contain a combination of liquid epoxy resins and solid epoxy resins.

[0107] The liquid epoxy resin is preferably a liquid epoxy resin having two or more epoxy groups in one molecule.

[0108] As the liquid epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, naphthalene type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, phenol novolac type epoxy resin, alicyclic epoxy resin having an ester skeleton, cyclohexane type epoxy resin, cyclohexane dimethanol type epoxy resin, and epoxy resin having a butadiene structure are preferred.

[0109] Specific examples of liquid epoxy resins include "HP4032", "HP4032D", and "HP4032SS" (naphthalene type epoxy resins) manufactured by DIC Corporation; "828US", "828EL", "jER828EL", "825", and "Epicoat 828EL" (bisphenol A type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "jER807" and "1750" (bisphenol F type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "jER152" (phenol novolac type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "630", "630LSD", and "604" (glycidylamine type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "ED-523T" (glycirol type epoxy resin) manufactured by ADEKA Corporation; "EP-3950L" and "EP-3980S" (glycidylamine type epoxy resins) manufactured by ADEKA Corporation; Examples of such epoxy resins include "EP-4088S" (dicyclopentadiene type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ZX1059" (mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YD-8125G" (bisphenol A type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "EX-721" (glycidyl ester type epoxy resin) manufactured by Nagase Chemtex Corporation; "Celloxide 2021P" (alicyclic epoxy resin having an ester skeleton) manufactured by Daicel Corporation; "PB-3600" manufactured by Daicel Corporation, "JP-100" and "JP-200" (epoxy resin having a butadiene structure) manufactured by Nippon Soda Co., Ltd.; "ZX1658" and "ZX1658GS" (liquid 1,4-glycidylcyclohexane type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd. These may be used alone or in combination of two or more types.

[0110] As the solid epoxy resin, a solid epoxy resin having three or more epoxy groups in one molecule is preferable, and an aromatic solid epoxy resin having three or more epoxy groups in one molecule is more preferable.

[0111] Preferred solid epoxy resins include bixylenol type epoxy resins, naphthalene type epoxy resins, naphthalene type tetrafunctional epoxy resins, naphthol novolac type epoxy resins, cresol novolac type epoxy resins, dicyclopentadiene type epoxy resins, trisphenol type epoxy resins, naphthol type epoxy resins, biphenyl type epoxy resins, naphthylene ether type epoxy resins, anthracene type epoxy resins, bisphenol A type epoxy resins, bisphenol AF type epoxy resins, phenol aralkyl type epoxy resins, tetraphenylethane type epoxy resins, and phenolphthalimidine type epoxy resins.

[0112] Specific examples of solid epoxy resins include "HP4032H" (naphthalene type epoxy resin) manufactured by DIC Corporation; "HP-4700" and "HP-4710" (naphthalene type tetrafunctional epoxy resins) manufactured by DIC Corporation; "N-690" (cresol novolac type epoxy resin) manufactured by DIC Corporation; "N-695" (cresol novolac type epoxy resin) manufactured by DIC Corporation; "HP-7200", "HP-7200HH", "HP-7200H", and "HP-7200L" (dicyclopentadiene type epoxy resins) manufactured by DIC Corporation; "EXA-7311" and "E XA-7311-G3, EXA-7311-G4, EXA-7311-G4S, HP6000, HP-6000L (naphthylene ether type epoxy resin); EPPN-502H (trisphenol type epoxy resin) manufactured by Nippon Kayaku; NC7000L (naphthol novolac type epoxy resin) manufactured by Nippon Kayaku; NC3000H, NC3000, NC3000L, NC3000FH, NC3100 (biphenyl type epoxy resin) manufactured by Nippon Steel Chemical & Material; ESN475V manufactured by Nippon Steel Chemical & Material. , "ESN4100V" (naphthalene type epoxy resin); "ESN485" (naphthol type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ESN375" (dihydroxynaphthalene type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YX4000H", "YX4000", "YX4000HK", "YL7890" (bixylenol type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd.; "YL6121" (biphenyl type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd.; "YX8800" (anthracene type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd. Examples of epoxy resins that can be used include "YX7700" (phenol aralkyl type epoxy resin) manufactured by Osaka Gas Chemicals; "PG-100" and "CG-500" manufactured by Osaka Gas Chemicals; "YX7760" (bisphenol AF type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL7800" (fluorene type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1010" (bisphenol A type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1031S" (tetraphenylethane type epoxy resin) manufactured by Mitsubishi Chemical Corporation; and "WHR991S" (phenolphthalimidine type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.These may be used alone or in combination of two or more.

[0113] When a liquid epoxy resin and a solid epoxy resin are used in combination as the epoxy resin, the mass ratio thereof (liquid epoxy resin:solid epoxy resin) is preferably 20:1 to 1:20, more preferably 10:1 to 1:10, and particularly preferably 7:1 to 1:7.

[0114] The epoxy equivalent of the epoxy resin is preferably in the range of 50 g / eq. to 5,000 g / eq., more preferably 60 g / eq. to 3,000 g / eq., further preferably 80 g / eq. to 2,000 g / eq., and particularly preferably 110 g / eq. to 1,000 g / eq. The epoxy equivalent represents the mass of the resin per equivalent of epoxy group. This epoxy equivalent can be measured according to JIS K7236.

[0115] The weight average molecular weight (Mw) of the epoxy resin is preferably in the range of 100 to 5,000, more preferably 250 to 3,000, and further preferably 400 to 1500. The weight average molecular weight of the resin can be measured by gel permeation chromatography (GPC) as a polystyrene-equivalent value.

[0116] The range of the amount of the epoxy resin is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 5% by mass or more, and is preferably 35% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less, relative to 100% by mass of the nonvolatile components in the resin composition layer. The range of the amount of the epoxy resin relative to 100% by mass of the nonvolatile components in the resin composition layer may be the same as the range of the amount of the epoxy resin relative to 100% by mass of the nonvolatile components in the resin composition layer. The nonvolatile components of the resin composition layer refer to the components of the resin composition layer excluding the solvent, unless otherwise specified. The nonvolatile components of the resin composition refer to the components of the resin composition excluding the solvent, unless otherwise specified.

[0117] The range of the amount of the epoxy resin is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, and preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less, based on 100% by mass of the resin components in the resin composition layer. The range of the amount of the epoxy resin based on 100% by mass of the resin components in the resin composition may be the same as the range of the amount of the epoxy resin based on 100% by mass of the resin components in the resin composition layer. The resin component of the resin composition layer refers to the non-volatile components of the resin composition layer excluding the inorganic filler, unless otherwise specified. The resin component of the resin composition refers to the non-volatile components of the resin composition excluding the inorganic filler, unless otherwise specified.

[0118] As the phenolic resin, a compound having one or more, preferably two or more, hydroxyl groups bonded to an aromatic ring such as a benzene ring or a naphthalene ring in one molecule can be used. From the viewpoint of heat resistance and water resistance, a phenolic resin having a novolac structure is preferred. From the viewpoint of adhesion, a nitrogen-containing phenolic resin is preferred, and a triazine skeleton-containing phenolic resin is more preferred. Among them, from the viewpoint of highly satisfying heat resistance, water resistance, and adhesion, a triazine skeleton-containing phenolic novolac resin is preferred. Specific examples of phenolic resins include "MEH-7700", "MEH-7810", and "MEH-7851" manufactured by Meiwa Kasei Co., Ltd.; "NHN", "CBN", and "GPH" manufactured by Nippon Kayaku Co., Ltd.; "SN-170", "SN-180", "SN-190", "SN-475", "SN-485", "SN-495", "SN-375", and "SN-395" manufactured by Nippon Steel Chemical & Material Co., Ltd.; and "LA-7052", "LA-7054", "LA-3018", "LA-3018-50P", "LA-1356", "TD2090", and "TD-2090-60M" manufactured by DIC Corporation.

[0119] As the active ester resin, a compound having two or more highly reactive ester groups in one molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds, is preferably used. The active ester resin is preferably obtained by a condensation reaction between a carboxylic acid compound and / or a thiocarboxylic acid compound and a hydroxy compound and / or a thiol compound. In particular, from the viewpoint of improving heat resistance, an active ester resin obtained from a carboxylic acid compound and a hydroxy compound is preferred, and an active ester resin obtained from a carboxylic acid compound and a phenol compound and / or a naphthol compound is more preferred. Examples of the carboxylic acid compound include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid. Examples of phenol compounds or naphthol compounds include hydroquinone, resorcin, bisphenol A, bisphenol F, bisphenol S, phenolphthaline, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadiene-type diphenol compounds, phenol novolac, etc. Here, the term "dicyclopentadiene-type diphenol compounds" refers to diphenol compounds obtained by condensing one molecule of dicyclopentadiene with two molecules of phenol.

[0120] Specifically, the active ester resin is preferably a dicyclopentadiene type active ester resin, a naphthalene type active ester resin containing a naphthalene structure, an active ester resin containing an acetylated product of phenol novolac, or an active ester resin containing a benzoylated product of phenol novolac, and more preferably at least one selected from a dicyclopentadiene type active ester resin and a naphthalene type active ester resin. As the dicyclopentadiene type active ester resin, an active ester resin containing a dicyclopentadiene type diphenol structure is preferable.

[0121] Commercially available active ester resins include, for example, active ester resins containing a dicyclopentadiene-type diphenol structure such as "EXB9451", "EXB9460", "EXB9460S", "EXB-8000L", "EXB-8000L-65M", "EXB-8000L-65TM", "HPC-8000L-65TM", "HPC-8000", "HPC-8000-65T", "HPC-8000H", and "HPC-8000H-65TM" (manufactured by DIC Corporation); and active ester resins containing a naphthalene structure such as "HP-B-8151-62T", "EXB-8100L-65T", "EXB-8150-60T", and "EXB-815 Examples of such active ester resins include "EXB9401" (manufactured by DIC Corporation), an active ester resin which is an acetylated product of phenol novolac, such as "DC808" (manufactured by Mitsubishi Chemical Corporation), an active ester resin which is a benzoylated product of phenol novolac, such as "YLH1026", "YLH1030", and "YLH1048" (manufactured by Mitsubishi Chemical Corporation), and an active ester resin which contains a styryl group and a naphthalene structure, such as "PC1300-02-65MA" (manufactured by Air Water Corporation).

[0122] As the carbodiimide resin, a compound having one or more, preferably two or more, carbodiimide structures in one molecule can be used. Specific examples of the carbodiimide resin include aliphatic biscarbodiimides such as tetramethylene-bis(t-butylcarbodiimide) and cyclohexane bis(methylene-t-butylcarbodiimide); aromatic biscarbodiimides such as phenylene-bis(xylylcarbodiimide); aliphatic polycarbodiimides such as polyhexamethylenecarbodiimide, polytrimethylhexamethylenecarbodiimide, polycyclohexylenecarbodiimide, poly(methylenebiscyclohexylenecarbodiimide), and poly(isophoronecarbodiimide); poly(phenylenecarbodiimide), poly(naphthalenecarbodiimide), and the like. Examples of polycarbodiimides include aromatic polycarbodiimides such as poly(methylenediphenylenecarbodiimide), poly(tolylenecarbodiimide), poly(methyldiisopropylphenylenecarbodiimide), poly(triethylphenylenecarbodiimide), poly(diethylphenylenecarbodiimide), poly(triisopropylphenylenecarbodiimide), poly(diisopropylphenylenecarbodiimide), poly(xylylenecarbodiimide), poly(tetramethylxylylenecarbodiimide), poly(methylenediphenylenecarbodiimide), and poly[methylenebis(methylphenylene)carbodiimide]. Commercially available carbodiimide resins include, for example, "Carbodilite V-02B", "Carbodilite V-03", "Carbodilite V-04K", "Carbodilite V-07", and "Carbodilite V-09" manufactured by Nisshinbo Chemical Inc.; and "Stavaxol P", "Stavaxol P400", and "Hi-Kasil 510" manufactured by LANXESS AG.

[0123] As the cyanate resin, a compound having one or more, preferably two or more, cyanate groups in one molecule can be used. Examples of the cyanate resin include bifunctional cyanate resins such as bisphenol A dicyanate, polyphenol cyanate (oligo(3-methylene-1,5-phenylene cyanate)), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidene diphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanatephenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanatephenyl-1-(methylethylidene))benzene, bis(4-cyanatephenyl)thioether, and bis(4-cyanatephenyl)ether; polyfunctional cyanate resins derived from phenol novolac and cresol novolac; and prepolymers in which these cyanate resins are partially converted to triazine. Specific examples of cyanate resins include Lonza's "PT30" and "PT60" (both of which are phenol novolac type multifunctional cyanate resins), "BA230" and "BA230S75" (prepolymers in which part or all of bisphenol A dicyanate has been converted into triazine to form a trimer).

[0124] As the acid anhydride resin, a compound having one or more, preferably two or more, acid anhydride groups in one molecule can be used. Specific examples of the acid anhydride resin include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, hydrogenated methylnadic anhydride, trialkyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, and the like. Examples of such anhydrides include water, biphenyltetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, oxydiphthalic dianhydride, 3,3'-4,4'-diphenylsulfonetetracarboxylic dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-C]furan-1,3-dione, ethylene glycol bis(anhydrotrimellitate), and polymeric acid anhydrides such as styrene-maleic acid resin, which is a copolymer of styrene and maleic acid. Commercially available acid anhydride resins include, for example, "HNA-100", "MH-700", "MTA-15", "DDSA", and "OSA" manufactured by New Japan Chemical Co., Ltd.; "YH-306" and "YH-307" manufactured by Mitsubishi Chemical Corporation; "HN-2200" and "HN-5500" manufactured by Resonaq Corporation; and "EF-30", "EF-40", "EF-60", and "EF-80" manufactured by Cray Valley Chemical Industries, Ltd.

[0125] As the amine resin, a compound having one or more, preferably two or more, amino groups in one molecule can be used. Examples of the amine resin include aliphatic amines, polyether amines, alicyclic amines, aromatic amines, etc., among which aromatic amines are preferred. The amine resin is preferably a primary amine or secondary amine, more preferably a primary amine. Specific examples of the amine resin include 4,4'-methylenebis(2,6-dimethylaniline), 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, m-phenylenediamine, m-xylylenediamine, diethyltoluenediamine, 4,4'-diaminodiphenylether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, 2,2-bis(3-amino-4-hydroxyphenyl)propionate, and the like. Pan, 3,3-dimethyl-5,5-diethyl-4,4-diphenylmethanediamine, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis(4-(4-aminophenoxy)phenyl)sulfone, bis(4-(3-aminophenoxy)phenyl)sulfone, and the like. Commercially available amine resins include, for example, "SEIKACURE-S" manufactured by Seika Corporation; "KAYABOND C-200S", "KAYABOND C-100", "KAYAHARD AA", "KAYAHARD AB", and "KAYAHARD AS" manufactured by Nippon Kayaku Co., Ltd.; "Epicure W" manufactured by Mitsubishi Chemical Corporation; and "DTDA" manufactured by Sumitomo Seika Chemicals Co., Ltd.

[0126] Specific examples of benzoxazine resins include "JBZ-OP100D" and "ODA-BOZ" manufactured by JFE Chemical Corporation; "HFB2006M" manufactured by Showa Polymer Co., Ltd.; and "Pd" and "Fa" manufactured by Shikoku Chemical Industry Co., Ltd.

[0127] Examples of thiol resins include trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), and tris(3-mercaptopropyl)isocyanurate.

[0128] The range of the active group equivalent of the curing agent is preferably 50 g / eq. to 3000 g / eq., more preferably 100 g / eq. to 1000 g / eq., further preferably 100 g / eq. to 500 g / eq., and particularly preferably 100 g / eq. to 300 g / eq. The active group equivalent represents the mass of the curing agent per equivalent of the active group.

[0129] The weight average molecular weight range of the curing agent may be the same as the weight average molecular weight (Mw) range of the epoxy resin.

[0130] When the number of epoxy groups in the epoxy resin is 1, the range of the number of active groups in the curing agent is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more, and is preferably 5.0 or less, more preferably 3.0 or less, and even more preferably 2.0 or less. The "number of epoxy groups in the epoxy resin" refers to the total value obtained by dividing the mass of the non-volatile components of the epoxy resin present in the resin composition layer by the epoxy equivalent. The "number of active groups in the curing agent" refers to the total value obtained by dividing the mass of the non-volatile components of the curing agent present in the resin composition layer by the active group equivalent.

[0131] The range of the amount of the curing agent is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 5% by mass or more, and is preferably 35% by mass or less, more preferably 25% by mass or less, and even more preferably 15% by mass or less, relative to 100% by mass of the nonvolatile components in the resin composition layer. The range of the amount of the curing agent relative to 100% by mass of the nonvolatile components in the resin composition may be the same as the above-mentioned range of the amount of the curing agent relative to 100% by mass of the nonvolatile components in the resin composition layer.

[0132] The range of the amount of the curing agent is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, and is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less, relative to 100% by mass of the resin components in the resin composition layer. The range of the amount of the curing agent relative to 100% by mass of the resin components in the resin composition may be the same as the above-mentioned range of the amount of the curing agent relative to 100% by mass of the resin components in the resin composition layer.

[0133] As the radical polymerizable resin, a resin containing an ethylenically unsaturated bond can be used. Thus, the radical polymerizable resin can usually have a radical polymerizable group containing an ethylenically unsaturated bond. Examples of the radical polymerizable group include unsaturated hydrocarbon groups such as vinyl group, allyl group, 1-propenyl group, 3-cyclohexenyl group, 3-cyclopentenyl group, 2-vinylphenyl group, 3-vinylphenyl group, and 4-vinylphenyl group; and α,β-unsaturated carbonyl groups such as acryloyl group, methacryloyl group, and maleimide group (2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl group). The radical polymerizable resin preferably has two or more radical polymerizable groups.

[0134] Examples of the radical polymerizable resin include (meth)acrylic radical polymerizable resins, styrene radical polymerizable resins, allyl radical polymerizable resins, maleimide radical polymerizable resins, etc. The radical polymerizable resins may be used alone or in combination of two or more kinds.

[0135] As the (meth)acrylic radical polymerizable resin, a resin having one or more, preferably two or more, acryloyl groups and / or methacryloyl groups in one molecule can be used. As the (meth)acrylic radical polymerizable resin, for example, cyclohexane-1,4-dimethanol di(meth)acrylate, cyclohexane-1,3-dimethanol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,9-nonane dimethanol ... Low molecular weight (molecular weight less than 1000) aliphatic (meth)acrylic acid ester compounds such as diol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, glycerin tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate; dioxane glycol di(meth)acrylate, 3,6-dioxa-1,8-octanediol di(meth)acrylate, ) acrylate, 3,6,9-trioxaundecane-1,11-diol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene, ethoxylated bisphenol A di(meth)acrylate, propoxylated bisphenol A di(meth)acrylate, and other low molecular weight (molecular weight less than 1000) ether-containing (meth)acrylic acid ester compounds; tris(3-hydroxypropyl)isocyanurate tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, and other low molecular weight (molecular weight less than 1000) isocyanurate-containing (meth)acrylic acid ester compounds; and high molecular weight (molecular weight 1000 or more) acrylic acid ester compounds such as (meth)acrylic modified polyphenylene ether resins. As used herein, the term "(meth)acrylic acid" includes acrylic acid, methacrylic acid, and combinations thereof.The term "(meth)acrylate" includes acrylate, methacrylate, and combinations thereof. Commercially available (meth)acrylic radical polymerizable resins include, for example, "A-DOG" (dioxane glycol diacrylate) manufactured by Shin-Nakamura Chemical Co., Ltd., "DCP-A" (tricyclodecane dimethanol diacrylate), "DCP" (tricyclodecane dimethanol dimethacrylate), and "BPE-1300N" (ethoxylated bisphenol A dimethacrylate) manufactured by Kyoeisha Chemical Co., Ltd., "KAYARAD R-684" (tricyclodecane dimethanol diacrylate) and "KAYARAD R-604" (dioxane glycol diacrylate) manufactured by Nippon Kayaku Co., Ltd., and "SA9000" and "SA9000-111" (methacrylic modified polyphenylene ether) manufactured by SABIC.

[0136] As the styrene radical polymerizable resin, a resin having one or more, preferably two or more, vinyl groups directly bonded to an aromatic carbon atom in one molecule can be used. As the styrene radical polymerizable resin, for example, low molecular weight (molecular weight less than 1000) styrene compounds such as divinylbenzene, 2,4-divinyltoluene, 2,6-divinylnaphthalene, 1,4-divinylnaphthalene, 4,4'-divinylbiphenyl, 1,2-bis(4-vinylphenyl)ethane, 2,2-bis(4-vinylphenyl)propane, and bis(4-vinylphenyl)ether; high molecular weight (molecular weight 1000 or more) styrene compounds such as vinylbenzyl-modified polyphenylene ether resin and styrene-divinylbenzene copolymer can be mentioned. Commercially available styrene-based radical polymerizable resins include, for example, "ODV-XET(X03)", "ODV-XET(X04)", and "ODV-XET(X05)" (styrene-divinylbenzene copolymers) manufactured by Nippon Steel Chemical & Material Co., Ltd., and "OPE-2St 1200" and "OPE-2St 2200" (vinylbenzyl-modified polyphenylene ether resins) manufactured by Mitsubishi Gas Chemical Co., Inc.

[0137] As the allyl radical polymerizable resin, a resin having one or more, preferably two or more, allyl groups in one molecule can be used. Examples of allyl radical polymerizable resins include aromatic carboxylic acid allyl ester compounds such as diallyl diphenate, triallyl trimellitate, diallyl phthalate, diallyl isophthalate, diallyl terephthalate, diallyl 2,6-naphthalenedicarboxylate, and diallyl 2,3-naphthalenecarboxylate; isocyanuric acid allyl ester compounds such as 1,3,5-triallyl isocyanurate and 1,3-diallyl-5-glycidyl isocyanurate; epoxy-containing aromatic allyl compounds such as 2,2-bis[3-allyl-4-(glycidyloxy)phenyl]propane; benzoxazine-containing aromatic allyl compounds such as bis[3-allyl-4-(3,4-dihydro-2H-1,3-benzoxazin-3-yl)phenyl]methane; ether-containing aromatic allyl compounds such as 1,3,5-triallyl ether benzene; and allyl silane compounds such as diallyl diphenyl silane. Commercially available allyl radical polymerizable resins include, for example, "TAIC" (1,3,5-triallyl isocyanurate) manufactured by Nippon Kasei Chemical Industry Co., Ltd., "DAD" (diallyl diphenate) manufactured by Nisshoku Techno Fine Chemical Co., Ltd., "TRIAM-705" (triallyl trimellitate) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name "DAND" (2,3-naphthalene carboxylate diallyl) manufactured by Nisshoku Techno Fine Chemical Co., Ltd., "ALP-d" (bis[3-allyl-4-(3,4-dihydro-2H-1,3-benzoxazin-3-yl)phenyl]methane) manufactured by Shikoku Kasei Corporation, "RE-810NM" (2,2-bis[3-allyl-4-(glycidyloxy)phenyl]propane) manufactured by Nippon Kayaku Co., Ltd., and "DA-MGIC" (1,3-diallyl-5-glycidyl isocyanurate) manufactured by Shikoku Kasei Corporation.

[0138] The maleimide radical polymerizable resin may be a resin having one or more, preferably two or more, maleimide groups in one molecule. The maleimide radical polymerizable resin may be an aromatic maleimide resin having a maleimide group directly bonded to an aromatic ring, or an aliphatic maleimide resin having no maleimide group directly bonded to an aromatic ring. Commercially available maleimide radical polymerizable resins include, for example, "SLK-2600" manufactured by Shin-Etsu Chemical Co., Ltd., "BMI-1500", "BMI-1700", "BMI-3000J", "BMI-689", and "BMI-2500" (dimer diamine structure-containing maleimide compounds) manufactured by Designer Molecules Inc., "BMI-6100" (aromatic maleimide compound) manufactured by Designer Molecules Inc., "MIR-5000-60T" and "MIR-3000-70MT" (biphenylaralkyl-type maleimide compounds) manufactured by Nippon Kayaku Co., Ltd., "BMI-70" and "BMI-80" manufactured by K.I. Chemical Industry Co., Ltd., and "BMI-2300" and "BMI-TMH" manufactured by Daiwa Kasei Kogyo Co., Ltd. In addition, as the maleimide-based radically polymerizable resin, a maleimide resin (an indane ring skeleton-containing maleimide compound) disclosed in the Japan Institute of Invention and Innovation's Technical Journal Publication No. 2020-500211 may be used.

[0139] The radical polymerizable group equivalent of the radical polymerizable resin is preferably 20 g / eq. to 3,000 g / eq., more preferably 50 g / eq. to 2,500 g / eq., further preferably 70 g / eq. to 2,000 g / eq., and particularly preferably 90 g / eq. to 1,500 g / eq. The radical polymerizable group equivalent represents the mass of the radical polymerizable resin per equivalent of the radical polymerizable group.

[0140] The weight average molecular weight (Mw) of the radical polymerizable resin is preferably 40,000 or less, more preferably 10,000 or less, further preferably 5,000 or less, and particularly preferably 3,000 or less. The lower limit is not particularly limited, but may be, for example, 150 or more.

[0141] The range of the amount of the radical polymerizable resin is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more, and is preferably 35% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less, relative to 100% by mass of the nonvolatile components in the resin composition layer. The range of the amount of the radical polymerizable resin relative to 100% by mass of the nonvolatile components in the resin composition may be the same as the above-mentioned range of the amount of the radical polymerizable resin relative to 100% by mass of the nonvolatile components in the resin composition layer.

[0142] The range of the amount of the radical polymerizable resin is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, and is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, relative to 100% by mass of the resin components in the resin composition layer. The range of the amount of the radical polymerizable resin relative to 100% by mass of the resin components in the resin composition may be the same as the above-mentioned range of the amount of the radical polymerizable resin relative to 100% by mass of the resin components in the resin composition layer.

[0143] The range of the amount of the (A) curable resin is preferably 2% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, and is preferably 35% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less, relative to 100% by mass of the nonvolatile components in the resin composition layer. The range of the amount of the (A) curable resin relative to 100% by mass of the nonvolatile components in the resin composition may be the same as the above-mentioned range of the amount of the (A) curable resin relative to 100% by mass of the nonvolatile components in the resin composition layer.

[0144] The range of the amount of the (A) curable resin is preferably 40% by mass or more, more preferably 60% by mass or more, and even more preferably 80% by mass or more, and is usually 100% by mass or less, preferably 99% by mass or less, based on 100% by mass of the resin components in the resin composition layer. The range of the amount of the (A) curable resin based on 100% by mass of the resin components in the resin composition may be the same as the above-mentioned range of the amount of the (A) curable resin based on 100% by mass of the resin components in the resin composition layer.

[0145] The resin composition layer and the resin composition as a material thereof preferably contain (B) inorganic filler. The (B) inorganic filler as the (B) component is particles of an inorganic material. Thus, the (B) inorganic filler is contained in the resin composition layer in the form of particles, and is usually contained in the insulating layer while maintaining the particle state. The (B) inorganic filler can reduce the linear thermal expansion coefficient of the insulating layer, thereby reducing the warpage of the circuit board. In addition, generally, when a resin composition layer containing (B) inorganic filler is used, there is a tendency for voids to easily occur in the cavity, but according to the above-mentioned manufacturing method, even when a resin composition layer in which voids are easily generated is adopted, the generation of the voids can be suppressed.

[0146] As the inorganic material forming the (B) inorganic filler, an inorganic compound is usually used. Examples of the material of the (B) inorganic filler include silica, alumina, glass, cordierite, silicon oxide, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, zirconium oxide, barium titanate, barium zirconate titanate, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate. Among these, silica and alumina are preferred, and silica is particularly preferred. Therefore, the (B) inorganic filler preferably contains silica, and may contain only silica. Examples of silica include amorphous silica, fused silica, crystalline silica, synthetic silica, and hollow silica. The silica is preferably spherical silica.The inorganic filler (B) may be used alone or in combination of two or more kinds.

[0147] (B) Commercially available inorganic fillers include, for example, "SP60-05" and "SP507-05" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YC100C", "YA050C", "YA050C-MJE", "YA010C", "SC2500SQ", "SO-C4", "SO-C2", and "SO-C1" manufactured by Admatechs Co., Ltd.; "UFP-30", "DAW-03", and "FB-105FD" manufactured by Denka Co., Ltd.; "Silfill NSS-3N", "Silfill NSS-4N", and "Silfill NSS-5N" manufactured by Tokuyama Corporation; and "Cellspheres" and "MGH-005" manufactured by Taiheiyo Cement Corporation.

[0148] The average particle size of the (B) inorganic filler is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.1 μm or more, and is preferably 10 μm or less, more preferably 5 μm or less, even more preferably 3 μm or less.

[0149] (B) The average particle size of the inorganic filler can be measured by a laser diffraction / scattering method based on the Mie scattering theory. Specifically, the particle size distribution of the inorganic filler is prepared on a volume basis using a laser diffraction / scattering particle size distribution measuring device, and the median diameter is used as the average particle size. The measurement sample can be prepared by weighing 100 mg of the inorganic filler and 10 g of methyl ethyl ketone into a vial and dispersing the mixture by ultrasonic waves for 10 minutes. The measurement sample can be measured by using a laser diffraction particle size distribution measuring device with blue and red light wavelengths as the light source, and the volume-based particle size distribution of the inorganic filler can be measured by a flow cell method, and the average particle size can be calculated from the obtained particle size distribution as the median diameter. An example of a laser diffraction particle size distribution measuring device is the "LA-960" manufactured by Horiba, Ltd.

[0150] (B) The specific surface area of ​​the inorganic filler is preferably 0.1 m 2 / g or more, more preferably 0.5m 2 / g or more, more preferably 1m 2 / g or more, particularly preferably 3m 2 / g or more, preferably 100m 2 / g or less, more preferably 70 m 2 / g or less, still more preferably 50 m 2 / g or less, particularly preferably 40 m 2 / g or less. The specific surface area of the inorganic filler can be measured by adsorbing nitrogen gas on the sample surface using a specific surface area measuring device (Macsorb HM-1210 manufactured by Mountech Co., Ltd.) in accordance with the BET method and calculating the specific surface area using the BET multi-point method.

[0151] (B) The inorganic filler is preferably treated with a surface treatment agent from the viewpoints of enhancing moisture resistance and dispersibility. Examples of the surface treatment agent include fluorine-containing silane coupling agents, aminosilane-based coupling agents, epoxysilane-based coupling agents, mercaptosilane-based coupling agents, silane-based coupling agents, alkoxysilanes, organosilazane compounds, titanate-based coupling agents, and the like. The surface treatment agent may be used alone or in any combination of two or more.

[0152] Examples of commercially available products of the surface treatment agent include "KBM403" (3-glycidoxypropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM803" (3-mercaptopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBE903" (3-aminopropyltriethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "SZ-31" (hexamethyldisilazane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM103" (phenyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM-4803" (long-chain epoxy type silane coupling agent) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM-7103" (3,3,3-trifluoropropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., and the like.

[0153] From the viewpoint of improving the dispersibility of the inorganic filler, the degree of surface treatment with the surface treatment agent is preferably within a specific range. Specifically, 100% by mass of the inorganic filler is preferably surface-treated with 0.2% to 5% by mass of the surface treatment agent, more preferably with 0.2% to 3% by mass of the surface treatment agent, and even more preferably with 0.3% to 2% by mass of the surface treatment agent.

[0154] The degree of surface treatment with the surface treatment agent can be evaluated by the amount of carbon per unit surface area of ​​the inorganic filler. From the viewpoint of improving the dispersibility of the inorganic filler, the amount of carbon per unit surface area of ​​the inorganic filler is set to 0.02 mg / m 2 More than 0.1 mg / m is preferable. 2 More preferably, 0.2 mg / m or more 2 On the other hand, from the viewpoint of preventing an increase in the melt viscosity of the resin composition layer, it is more preferable that the melt viscosity is 1.0 mg / m 2 Less than 0.8 mg / m is preferred. 2 Less than 0.5 mg / m is more preferable. 2 The following is even more preferred:

[0155] (B) The amount of carbon per unit surface area of ​​the inorganic filler can be measured after the surface-treated inorganic filler is washed with a solvent (e.g., methyl ethyl ketone (MEK)). Specifically, a sufficient amount of MEK as a solvent is added to the inorganic filler that has been surface-treated with a surface treatment agent, and ultrasonic cleaning is performed at 25°C for 5 minutes. After removing the supernatant and drying the solid content, the amount of carbon per unit surface area of ​​the inorganic filler can be measured using a carbon analyzer. As the carbon analyzer, the "EMIA-320V" manufactured by Horiba, Ltd., or the like can be used.

[0156] The range of the amount of the (B) inorganic filler in the resin composition layer is preferably 65% ​​by mass or more, more preferably 68% by mass or more, and even more preferably 70% by mass or more, and preferably 90% by mass or less, more preferably 88% by mass or less, and even more preferably 87% by mass or less, based on 100% by mass of the nonvolatile components in the resin composition layer. The range of the amount of the (B) inorganic filler based on 100% by mass of the nonvolatile components in the resin composition may be the same as the above-mentioned range of the amount of the (B) inorganic filler based on 100% by mass of the nonvolatile components in the resin composition layer. The resin composition layer containing the (B) inorganic filler in such an amount range can reduce the linear thermal expansion coefficient of the insulating layer and suppress the warping of the circuit board. In addition, a resin composition layer containing a large amount of the (B) inorganic filler has traditionally tended to easily generate voids in the cavity. In contrast, according to the above-mentioned method for producing a circuit board, even when a resin composition layer containing such a large amount of the (B) inorganic filler is used, the generation of voids can be suppressed.

[0157] The resin composition layer and the resin composition as a material thereof may contain a (C) thermoplastic resin as an optional component. The (C) thermoplastic resin as the (C) component does not include components corresponding to the (A) to (B) components. The (C) thermoplastic resin is usually contained in the resin composition layer in a state of being compatible with resin components other than the (C) thermoplastic resin, and is contained in the insulating layer while maintaining the compatible state.

[0158] The thermoplastic resin (C) usually has a large molecular weight. Specifically, the weight average molecular weight Mw of the thermoplastic resin (C) is preferably greater than 5,000, more preferably 8,000 or more, even more preferably 10,000 or more, particularly preferably 20,000 or more, and is preferably 100,000 or less, more preferably 70,000 or less, even more preferably 60,000 or less, particularly preferably 50,000 or less.

[0159] Examples of the (C) thermoplastic resin include phenoxy resin, polyimide resin, polyvinyl acetal resin, polyolefin resin, polybutadiene resin, polyamideimide resin, polyetherimide resin, polysulfone resin, polyethersulfone resin, polyphenylene ether resin, polycarbonate resin, polyetheretherketone resin, polyester resin, etc. The (C) thermoplastic resin may be used alone or in combination of two or more kinds.

[0160] Examples of the phenoxy resin include phenoxy resins having one or more skeletons selected from the group consisting of bisphenol A skeleton, bisphenol F skeleton, bisphenol S skeleton, bisphenolacetophenone skeleton, novolac skeleton, biphenyl skeleton, fluorene skeleton, dicyclopentadiene skeleton, norbornene skeleton, naphthalene skeleton, anthracene skeleton, adamantane skeleton, terpene skeleton, and trimethylcyclohexane skeleton. The terminal of the phenoxy resin may be any functional group such as a phenolic hydroxyl group or an epoxy group. Specific examples of phenoxy resins include "1256" and "4250" manufactured by Mitsubishi Chemical Corporation (both of which are phenoxy resins containing a bisphenol A skeleton); "YX8100" manufactured by Mitsubishi Chemical Corporation (phenoxy resin containing a bisphenol S skeleton); "YX6954" manufactured by Mitsubishi Chemical Corporation (phenoxy resin containing a bisphenol acetophenone skeleton); "FX280" and "FX293" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YL7500BH30", "YX6954BH30", "YX7553", "YX7553BH30", "YL7769BH30", "YL6794", "YL7213", "YL7290", "YL7482", and "YL7891BH30" manufactured by Mitsubishi Chemical Corporation.

[0161] Specific examples of polyimide resins include "SLK-6100" manufactured by Shin-Etsu Chemical Co., Ltd., and "Rikacoat SN20" and "Rikacoat PN20" manufactured by New Japan Chemical Co., Ltd.

[0162] Examples of polyvinyl acetal resins include polyvinyl formal resins and polyvinyl butyral resins, and polyvinyl butyral resins are preferred.Specific examples of polyvinyl acetal resins include S-LEC BH series, BX series (e.g., BX-5Z), KS series (e.g., KS-1), BL series, and BM series manufactured by Sekisui Chemical Co., Ltd.

[0163] Examples of polyolefin resins include ethylene-based copolymer resins such as low-density polyethylene, very low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-methyl acrylate copolymer; and polyolefin polymers such as polypropylene and ethylene-propylene block copolymer.

[0164] Examples of polybutadiene resins include hydrogenated polybutadiene skeleton-containing resins, hydroxyl group-containing polybutadiene resins, phenolic hydroxyl group-containing polybutadiene resins, carboxyl group-containing polybutadiene resins, acid anhydride group-containing polybutadiene resins, epoxy group-containing polybutadiene resins, isocyanate group-containing polybutadiene resins, urethane group-containing polybutadiene resins, polyphenylene ether-polybutadiene resins, etc. A part or all of the polybutadiene structure of the polybutadiene resin may be hydrogenated. Specific examples of polybutadiene resins include "Ricon 130MA8", "Ricon 130MA13", "Ricon 130MA20", "Ricon 131MA5", "Ricon 131MA10", "Ricon 131MA17", "Ricon 131MA20", and "Ricon 184MA6" (polybutadiene containing an acid anhydride group) manufactured by Cray Valley Corporation; "GQ-1000" (polybutadiene having hydroxyl groups and carboxyl groups introduced therein), "G-1000", "G-2000", and "G-3000" (polybutadiene having hydroxyl groups at both ends), "GI-1000", "GI-2000", and "GI-3000" (polybutadiene having hydrogenated hydroxyl groups at both ends) manufactured by Nippon Soda Co., Ltd.; and "FCA-061L" (hydrogenated polybutadiene skeleton epoxy resin) manufactured by Nagase ChemteX Corporation. Specific examples of polybutadiene resins include polyimide resins having a polybutadiene structure, a urethane structure, and an imide structure in the molecule. The polyimide resin can be produced as a linear polyimide resin (polyimide described in JP 2006-37083 A and WO 2008 / 153208 A) using hydroxyl-terminated polybutadiene, a diisocyanate compound, and a tetrabasic acid anhydride as raw materials. The content of the butadiene structure in the polyimide resin is preferably 60% by mass to 95% by mass, more preferably 75% by mass to 85% by mass. Details of the polyimide resin can be found in JP 2006-37083 A and WO 2008 / 153208 A, the contents of which are incorporated herein by reference.

[0165] Specific examples of polyamide-imide resins include "Viromax HR11NN" and "Viromax HR16NN" manufactured by Toyobo Co., Ltd. Specific examples of polyamide-imide resins also include modified polyamide-imides such as "KS9100" and "KS9300" (polysiloxane skeleton-containing polyamide-imide) manufactured by Resonac Corporation.

[0166] A specific example of the polyethersulfone resin is "PES5003P" manufactured by Sumitomo Chemical Co., Ltd.

[0167] Specific examples of polysulfone resins include polysulfones "P1700" and "P3500" manufactured by Solvay Advanced Polymers.

[0168] A specific example of the polyphenylene ether resin is NORYL SA90 manufactured by SABIC, etc. A specific example of the polyetherimide resin is ULTEM manufactured by GE, etc.

[0169] Examples of polycarbonate resins include hydroxyl group-containing carbonate resins, phenolic hydroxyl group-containing carbonate resins, carboxyl group-containing carbonate resins, acid anhydride group-containing carbonate resins, isocyanate group-containing carbonate resins, and urethane group-containing carbonate resins. Specific examples of polycarbonate resins include Mitsubishi Gas Chemical's "FPC0220," Asahi Kasei's "T6002" and "T6001" (polycarbonate diols), and Kuraray's "C-1090," "C-2090," and "C-3090" (polycarbonate diols). Specific examples of polycarbonate resins include polyimide resins having an imide structure, a urethane structure, and a polycarbonate structure in the molecule. The polyimide resin can be produced as a linear polyimide resin using hydroxyl group-terminated polycarbonate, a diisocyanate compound, and a tetrabasic acid anhydride as raw materials. The content of the carbonate structure in the polyimide resin is preferably 60% by mass to 95% by mass, more preferably 75% by mass to 85% by mass. For details of the polyimide resin, refer to the description in International Publication No. 2016 / 129541, the contents of which are incorporated herein by reference.

[0170] A specific example of the polyether ether ketone resin is "Sumiploy K" manufactured by Sumitomo Chemical Co., Ltd.

[0171] Examples of polyester resins include polyethylene terephthalate resins, polyethylene naphthalate resins, polybutylene terephthalate resins, polybutylene naphthalate resins, polytrimethylene terephthalate resins, polytrimethylene naphthalate resins, and polycyclohexane dimethyl terephthalate resins.

[0172] The thermoplastic resin (C) may contain an elastomer. The elastomer is a resin having flexibility, and is preferably a resin having rubber elasticity or a resin exhibiting rubber elasticity by polymerizing with other components. Examples of rubber elasticity include resins that exhibit an elastic modulus of 1 GPa or less when a tensile test is performed at a temperature of 25°C and a humidity of 40% RH in accordance with the Japanese Industrial Standards (JIS K7161).

[0173] The elastomer is preferably one or more selected from resins having a glass transition temperature (Tg) of 25° C. or less and resins that are liquid at 25° C. or less. The glass transition temperature of the resin having a glass transition temperature (Tg) of 25° C. or less is preferably 20° C. or less, more preferably 15° C. or less. The lower limit of the glass transition temperature is not particularly limited, but it can usually be −15° C. or more. Furthermore, the resin that is liquid at 25° C. is preferably a resin that is liquid at 20° C. or less, more preferably a resin that is liquid at 15° C. or less. The glass transition temperature can be measured by DSC (differential scanning calorimetry).

[0174] The range of the amount of the (C) thermoplastic resin is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.2% by mass or more, and is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less, relative to 100% by mass of the nonvolatile components in the resin composition. The range of the amount of the (C) thermoplastic resin relative to 100% by mass of the nonvolatile components in the resin composition may be the same as the above-mentioned range of the amount of the (C) thermoplastic resin relative to 100% by mass of the nonvolatile components in the resin composition layer.

[0175] The range of the amount of the (C) thermoplastic resin is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, and is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less, relative to 100% by mass of the resin components in the resin composition layer. The range of the amount of the (C) thermoplastic resin relative to 100% by mass of the resin components in the resin composition may be the same as the above-mentioned range of the amount of the (C) thermoplastic resin relative to 100% by mass of the resin components in the resin composition layer.

[0176] The resin composition layer and the resin composition as a material thereof may contain a flame retardant (D) as an optional component. The flame retardant (D) as component (D) does not include components corresponding to components (A) to (C). The flame retardant (D) can improve the flame retardancy of the insulating layer.

[0177] Examples of the (D) flame retardant include phosphazene compounds, organic phosphorus flame retardants, organic nitrogen-containing phosphorus compounds, nitrogen compounds, silicone flame retardants, metal hydroxides, etc. The (D) flame retardant may be used alone or in combination of two or more kinds.

[0178] Examples of (D) flame retardants include "SPH-100", "SPS-100", "SPB-100", and "SPE-100" (phosphazenes) manufactured by Otsuka Chemical Co., Ltd.; "FP-100", "FP-110", "FP-300", and "FP-400" (phosphazenes) manufactured by Fushimi Pharmaceutical Co., Ltd.; "HCA-NQ", "HCA-HQ", and "HCA-HQ-HST" (phosphinic acid esters (containing phenolic hydroxyl groups)) manufactured by Sankosha; and "PX-200", "PX-201", "PX-202", "CR-733S", "CR-741", and "CR-747" (phosphate esters) manufactured by Daihachi Chemical Industry Co., Ltd.

[0179] The range of the amount of the flame retardant (D) is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 1% by mass or more, and is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 2% by mass or less, relative to 100% by mass of the nonvolatile components in the resin composition layer. The range of the amount of the flame retardant (D) relative to 100% by mass of the nonvolatile components in the resin composition may be the same as the above-mentioned range of the amount of the flame retardant (D) relative to 100% by mass of the nonvolatile components in the resin composition layer.

[0180] The range of the amount of the flame retardant (D) is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more, and preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, relative to 100% by mass of the resin components in the resin composition layer. The range of the amount of the flame retardant (D) relative to 100% by mass of the resin components in the resin composition may be the same as the above-mentioned range of the amount of the flame retardant (D) relative to 100% by mass of the resin components in the resin composition layer.

[0181] The resin composition layer and the resin composition as a material thereof may contain (E) a curing accelerator as an optional component. The (E) curing accelerator as the (E) component does not include the components corresponding to the above-mentioned (A) to (D). The (E) curing accelerator functions as a curing catalyst that accelerates the curing of the (B) curable resin.

[0182] As the (E) curing accelerator, an appropriate one can be used depending on the type of the (A) curing resin. For example, when the (A) curing resin contains an epoxy resin, examples of the (E) curing accelerator that can accelerate the curing of the epoxy resin include phosphorus-based curing accelerators, urea-based curing accelerators, guanidine-based curing accelerators, imidazole-based curing accelerators, metal-based curing accelerators, and amine-based curing accelerators. The (E) curing accelerators may be used alone or in combination of two or more.

[0183] Examples of the phosphorus-based curing accelerator include aliphatic phosphonium salts such as tetrabutyl phosphonium bromide, tetrabutyl phosphonium chloride, tetrabutyl phosphonium acetate, tetrabutyl phosphonium decanoate, tetrabutyl phosphonium laurate, bis(tetrabutyl phosphonium)pyromellitate, tetrabutyl phosphonium hydrogenhexahydrophthalate, tetrabutyl phosphonium 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenolate, and di-tert-butyldimethylphosphonium tetraphenylborate; methyl triphenyl phosphonium bromide, ethyl triphenyl phosphonium bromide, propyl triphenyl phosphonium bromide, butyl triphenyl phosphonium bromide, benzyl triphenyl phosphonium chloride, tetraphenyl phosphonium bromide, p-tolyl triphenyl phosphonium tetra-p-tolylborate, tetraphenyl phosphonium bromide, and the like. aromatic phosphonium salts such as tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, triphenylethylphosphonium tetraphenylborate, tris(3-methylphenyl)ethylphosphonium tetraphenylborate, tris(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, and butyltriphenylphosphonium thiocyanate; aromatic phosphine-borane complexes such as triphenylphosphine-triphenylborane; aromatic phosphine-quinone adducts such as triphenylphosphine-p-benzoquinone adduct; aliphatic phosphines such as tributylphosphine, tri-tert-butylphosphine, trioctylphosphine, di-tert-butyl(2-butenyl)phosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, and tricyclohexylphosphine;Dibutylphenylphosphine, di-tert-butylphenylphosphine, methyldiphenylphosphine, ethyldiphenylphosphine, butyldiphenylphosphine, diphenylcyclohexylphosphine, triphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tris(4-ethylphenyl)phosphine, tris(4-propylphenyl)phosphine, tris(4-isopropylphenyl)phosphine, tris(4-butylphenyl)phosphine, tris(4-tert-butylphenyl)phosphine, tris(2,4-dimethylphenyl)phosphine, tris(2,5-dimethylphenyl)phosphine, tris(2,6-dimethylphenyl)phosphine Examples of aromatic phosphines include tris(3,5-dimethylphenyl)phosphine, tris(2,4,6-trimethylphenyl)phosphine, tris(2,6-dimethyl-4-ethoxyphenyl)phosphine, tris(2-methoxyphenyl)phosphine, tris(4-methoxyphenyl)phosphine, tris(4-ethoxyphenyl)phosphine, tris(4-tert-butoxyphenyl)phosphine, diphenyl-2-pyridylphosphine, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, 1,2-bis(diphenylphosphino)acetylene, and 2,2'-bis(diphenylphosphino)diphenyl ether.

[0184] Examples of the urea-based curing accelerator include 1,1-dimethylurea; aliphatic dimethylureas such as 1,1,3-trimethylurea, 3-ethyl-1,1-dimethylurea, 3-cyclohexyl-1,1-dimethylurea, and 3-cyclooctyl-1,1-dimethylurea; 3-phenyl-1,1-dimethylurea, 3-(4-chlorophenyl)-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea, 3-(2-methylphenyl)-1,1-dimethylurea, 3-(4-methylphenyl)-1,1-dimethylurea, and 3-(3,4-dimethylphenyl)-1,1-dimethylurea. aromatic dimethylureas such as butylurea, 3-(4-isopropylphenyl)-1,1-dimethylurea, 3-(4-methoxyphenyl)-1,1-dimethylurea, 3-(4-nitrophenyl)-1,1-dimethylurea, 3-[4-(4-methoxyphenoxy)phenyl]-1,1-dimethylurea, 3-[4-(4-chlorophenoxy)phenyl]-1,1-dimethylurea, 3-[3-(trifluoromethyl)phenyl]-1,1-dimethylurea, N,N-(1,4-phenylene)bis(N',N'-dimethylurea), and N,N-(4-methyl-1,3-phenylene)bis(N',N'-dimethylurea) [toluene bisdimethylurea].

[0185] Examples of the guanidine curing accelerator include dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1-methylbiguanide, 1-ethylbiguanide, 1-n-butylbiguanide, 1-n-octadecylbiguanide, 1,1-dimethylbiguanide, 1,1-diethylbiguanide, 1-cyclohexylbiguanide, 1-allylbiguanide, 1-phenylbiguanide, and 1-(o-tolyl)biguanide.

[0186] Examples of the imidazole-based curing accelerator include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, and 1-benzyl-2-methylimidazole. Phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl -(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct , 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, 2-phenylimidazoline, and other imidazole compounds and adducts of imidazole compounds and epoxy resins. Commercially available imidazole curing accelerators include, for example, "1B2PZ", "2E4MZ", "2MZA-PW", "2MZ-OK", "2MA-OK", "2MA-OK-PW", "2PHZ", "2PHZ-PW", "Cl1Z", "Cl1Z-CN", "Cl1Z-CNS", and "C11Z-A" manufactured by Shikoku Chemical Industry Co., Ltd.; and "P200-H50" manufactured by Mitsubishi Chemical Corporation.

[0187] Examples of the metal-based hardening accelerators include organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, tin, etc. Specific examples of the organometallic complexes include organocobalt complexes such as cobalt(II) acetylacetonate and cobalt(III) acetylacetonate, organocopper complexes such as copper(II) acetylacetonate, organozinc complexes such as zinc(II) acetylacetonate, organoiron complexes such as iron(III) acetylacetonate, organonickel complexes such as nickel(II) acetylacetonate, and organomanganese complexes such as manganese(II) acetylacetonate. Examples of the organometallic salts include zinc octylate, tin octylate, zinc naphthenate, cobalt naphthenate, tin stearate, zinc stearate, etc.

[0188] Examples of the amine-based hardening accelerators include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, 1,8-diazabicyclo(5,4,0)-undecene, etc. As the amine-based hardening accelerator, commercially available products may be used, and examples thereof include "MY-25" manufactured by Ajinomoto Fine-Techno Co., Inc.

[0189] (E) The range of the amount of the hardening accelerator is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, still more preferably 0.03% by mass or more, and preferably 5% by mass or less, more preferably 1% by mass or less, still more preferably 0.5% by mass or less, based on 100% by mass of the non-volatile components in the resin composition layer. Also, the range of the amount of the hardening accelerator (E) with respect to 100% by mass of the non-volatile components in the resin composition may be the same as the above range of the amount of the hardening accelerator (E) with respect to 100% by mass of the non-volatile components in the resin composition layer.

[0190] (E) The amount of the curing accelerator preferably ranges from 0.01% by mass or more, more preferably 0.05% by mass or more, still more preferably 0.1% by mass or more, and preferably 5% by mass or less, more preferably 2% by mass or less, still more preferably 1% by mass or less, based on 100% by mass of the resin component in the resin composition layer. Also, the range of the amount of the (E) curing accelerator based on 100% by mass of the resin component in the resin composition may be the same as the above range of the amount of the (E) curing accelerator based on 100% by mass of the resin component in the resin composition layer.

[0191] The resin composition layer and the resin composition as its material may contain, as an optional component, (F) a polymerization initiator. The (F) polymerization initiator as the component (F) does not include components corresponding to the above-mentioned components (A) to (E). The (F) polymerization initiator may be used alone or in combination of two or more.

[0192] The type of the (F) polymerization initiator can be selected according to the type of the (A) curable resin. For example, when the (A) curable resin contains a radical polymerizable resin, it is preferable to use a radical polymerization initiator as the (F) polymerization initiator. Examples of the radical polymerization initiator include peroxide-based radical polymerization initiators and azo-based radical polymerization initiators. Among them, peroxide-based radical polymerization initiators are preferable.

[0193] Examples of the peroxide radical polymerization initiator include hydroperoxide compounds such as 1,1,3,3-tetramethylbutyl hydroperoxide; dialkyl peroxide compounds such as tert-butylcumyl peroxide, di-tert-butyl peroxide, di-tert-hexyl peroxide, dicumyl peroxide, 1,4-bis(1-tert-butylperoxy-1-methylethyl)benzene, and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane; and diacyl peroxide compounds such as dilauroyl peroxide, didecanoyl peroxide, dicyclohexyl peroxydicarbonate, and bis(4-tert-butylcyclohexyl)peroxydicarbonate. peroxyester compounds such as tert-butyl peroxyacetate, tert-butyl peroxybenzoate, tert-butyl peroxyisopropyl monocarbonate, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyneodecanoate, tert-hexylperoxyisopropyl monocarbonate, tert-butyl peroxylaurate, (1,1-dimethylpropyl)2-ethylperhexanoate, tert-butyl 2-ethylperhexanoate, tert-butyl 3,5,5-trimethylperhexanoate, tert-butylperoxy-2-ethylhexyl monocarbonate, and tert-butylperoxymaleic acid.

[0194] (F) Examples of commercially available polymerization initiators include “Perbutyl C”, “Perbutyl A”, “Perbutyl P”, “Perbutyl L”, “Perbutyl O”, “Perbutyl ND”, “Perbutyl Z”, “Perbutyl I”, “Percumyl P”, “Percumyl D”, “Perhexyl D”, “Perhexyl A”, “Perhexyl I”, “Perhexyl Z”, “Perhexyl ND”, “Perhexyl O”, and “Perhexyl PV”, all manufactured by NOF Corporation.

[0195] The range of the amount of the (F) polymerization initiator is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, even more preferably 0.05% by mass or more, and is preferably 5% by mass or less, more preferably 1% by mass or less, even more preferably 0.1% by mass or less, relative to 100% by mass of the nonvolatile components in the resin composition layer. The range of the amount of the (F) polymerization initiator relative to 100% by mass of the nonvolatile components in the resin composition may be the same as the above-mentioned range of the amount of the (F) polymerization initiator relative to 100% by mass of the nonvolatile components in the resin composition layer.

[0196] The range of the amount of the (F) polymerization initiator is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, and is preferably 5% by mass or less, more preferably 2% by mass or less, even more preferably 1% by mass or less, relative to 100% by mass of the resin components in the resin composition layer. The range of the amount of the (F) polymerization initiator relative to 100% by mass of the resin components in the resin composition may be the same as the above-mentioned range of the amount of the (F) polymerization initiator relative to 100% by mass of the resin components in the resin composition layer.

[0197] The resin composition layer and the resin composition as a material thereof may contain an optional additive (G) as an optional component. The optional additive (G) does not include the components corresponding to the above-mentioned components (A) to (F). Examples of the optional additive (G) include organometallic compounds such as organocopper compounds, organozinc compounds, and organocobalt compounds; colorants such as phthalocyanine blue, phthalocyanine green, iodine green, diazo yellow, crystal violet, titanium oxide, and carbon black; polymerization inhibitors such as hydroquinone, catechol, pyrogallol, and phenothiazine; leveling agents such as silicone-based leveling agents and acrylic polymer-based leveling agents; thickeners such as bentone and montmorillonite; defoamers such as silicone-based defoamers, acrylic defoamers, fluorine-based defoamers, and vinyl resin-based defoamers; ultraviolet absorbers such as benzotriazole-based ultraviolet absorbers; adhesion improvers such as urea silane; triazole-based adhesion imparting agents, tetrazo Examples of the adhesiveness imparting agent include phenol-based adhesiveness imparting agents and triazine-based adhesiveness imparting agents; antioxidants such as hindered phenol-based antioxidants; fluorescent brighteners such as stilbene derivatives; surfactants such as fluorine-based surfactants and silicone-based surfactants; dispersants such as phosphate ester-based dispersants, polyoxyalkylene-based dispersants, acetylene-based dispersants, silicone-based dispersants, anionic dispersants, and cationic dispersants; stabilizers such as borate-based stabilizers, titanate-based stabilizers, aluminate-based stabilizers, zirconate-based stabilizers, isocyanate-based stabilizers, carboxylic acid-based stabilizers, and carboxylic anhydride-based stabilizers; photopolymerization initiator assistants such as tertiary amines; photosensitizers such as pyrarizones, anthracenes, coumarins, xanthones, and thioxanthones. (G) The optional additives may be used alone or in combination of two or more.

[0198] The resin composition may further contain a (H) solvent as an optional volatile component in combination with the non-volatile components such as the above-mentioned components (A) to (G). As the (H) solvent, an organic solvent is usually used. Examples of the organic solvent include ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester-based solvents such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, isoamyl acetate, methyl propionate, ethyl propionate, and γ-butyrolactone; ether-based solvents such as tetrahydropyran, tetrahydrofuran, 1,4-dioxane, diethyl ether, diisopropyl ether, dibutyl ether, diphenyl ether, and anisole; alcohol-based solvents such as methanol, ethanol, propanol, butanol, and ethylene glycol; 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl diglycol acetate, γ-butyrolactone, and methyl methoxypropionate. Examples of suitable solvents include ether ester solvents such as ethyl acetate, ester alcohol solvents such as methyl lactate, ethyl lactate, and methyl 2-hydroxyisobutyrate, ether alcohol solvents such as 2-methoxypropanol, 2-methoxyethanol, 2-ethoxyethanol, propylene glycol monomethyl ether, and diethylene glycol monobutyl ether (butylcarbitol), amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone, sulfoxide solvents such as dimethyl sulfoxide, nitrile solvents such as acetonitrile and propionitrile, aliphatic hydrocarbon solvents such as hexane, cyclopentane, cyclohexane, and methylcyclohexane, and aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, and trimethylbenzene. The (H) solvent may be used alone or in combination of two or more.

[0199] The amount of (H) solvent is not particularly limited, but may be, for example, 60 mass% or less, 40 mass% or less, 30 mass% or less, 20 mass% or less, 15 mass% or less, 10 mass% or less, etc., relative to 100 mass% of all components in the resin composition layer, or may be 0 mass%.

[0200] The resin composition layer preferably has a melt viscosity in a specific range at at least one of the pressing temperature in step (3) and the pressing temperature in step (5), and more preferably has a melt viscosity in a specific range at both the pressing temperature in step (3) and the pressing temperature in step (5). The specific range is preferably 300 poise or more, more preferably 700 poise or more, and more preferably 1,000 poise or more, and preferably 60,000 poise or less, more preferably 50,000 poise or less, and more preferably 40,000 poise or less. Usually, the resin composition has a melt viscosity in the same range as the resin composition layer at at least one of, and preferably both of, the pressing temperature in step (3) and the pressing temperature in step (5). When the melt viscosity is in the above range, it is possible to effectively suppress the generation of voids.

[0201] The melt viscosity can be measured using a dynamic viscoelasticity measuring device. This measurement can be performed by increasing the temperature from an initial temperature of 70° C. to 180° C. at a temperature increase rate of 5° C. / min. The measurement conditions can be a measurement temperature interval of 2.5° C., a vibration frequency of 1 Hz, and a strain of 5 deg. Specific measurement procedures can be those described in <Melt viscosity and tan δ measurement test> described in the examples.

[0202] The resin composition layer preferably has a loss tangent tanδ in a specific range at at least one of the pressing temperatures in step (3) and the pressing temperatures in step (5), and more preferably has a loss tangent tanδ in a specific range at both the pressing temperatures in step (3) and the pressing temperatures in step (5). The specific range is preferably 0.8 or more, more preferably 0.9 or more, and even more preferably 1.0 or more, and is preferably 2.0 or less, more preferably 1.8 or less, and even more preferably 1.7 or less. Usually, the resin composition has a loss tangent tanδ in the same range as the resin composition layer at at least one of the pressing temperatures in step (3) and the pressing temperatures in step (5), and preferably both. When the loss tangent tanδ is in the above range, it is possible to effectively suppress the generation of voids.

[0203] The loss tangent tanδ can be measured using a dynamic viscoelasticity measuring device. This measurement can be performed by increasing the temperature from an initial temperature of 70° C. to 180° C. at a temperature increase rate of 5° C. / min. The measurement conditions can be a measurement temperature interval of 2.5° C., a vibration frequency of 1 Hz, and a strain of 5 deg. Specific measurement procedures can be those described in <Melt viscosity and tanδ measurement test> described in the examples.

[0204] In the above-mentioned method for producing a circuit board, an insulating layer is obtained as a cured product obtained by curing a resin composition layer. The insulating layer formed contains a cured product of the resin composition, and preferably contains only the cured product of the resin composition. Since heat is usually applied when curing the resin composition layer, volatile components such as (H) solvent among the components contained in the resin composition layer may volatilize due to the heat during curing. Therefore, the insulating layer and the cured product of the resin composition as a material thereof may contain non-volatile components of the resin composition or reaction products thereof.

[0205] The average linear thermal expansion coefficient at 25°C to 150°C of the cured product obtained by curing the resin composition layer of the resin sheet under the curing condition of 200°C for 90 minutes is preferably in a specific range. Specifically, the range of the average linear thermal expansion coefficient is preferably less than 25 ppm / °C, more preferably less than 22 ppm / °C, even more preferably less than 20 ppm / °C, and particularly preferably less than 18 ppm / °C. The lower limit can be, for example, 1 ppm / °C or more, 3 ppm / °C or more, etc. When a resin sheet having such a resin composition layer is used, an insulating layer having a small average linear thermal expansion coefficient can be obtained, so that warping of the circuit board can be suppressed. In addition, in general, in order to obtain such a small average linear thermal expansion coefficient, the resin composition layer is required to contain a large amount of inorganic filler, but when a resin composition layer containing such a large amount of inorganic filler is used, there has been a tendency that voids are easily generated. In contrast, according to the manufacturing method according to this embodiment, even when a resin composition layer that can obtain such a small average linear thermal expansion coefficient is adopted, the generation of voids can be suppressed.

[0206] The average linear thermal expansion coefficient can be measured by curing the resin composition layer under the curing conditions of 200°C for 90 minutes to obtain a cured product, and then performing thermomechanical analysis by the tensile loading method using a thermomechanical analyzer. The measurement is carried out under the measurement conditions of a load of 1 g and a heating rate of 5°C / min, and can be measured in the temperature range from 25°C to 150°C. The specific measurement operation can adopt the one described in the <CTE measurement test> of the examples described later.

[0207] The cured product obtained by curing the resin composition layer of the resin sheet under the curing conditions of 200°C for 90 minutes can usually have excellent dielectric properties. For example, it can have a low dielectric tangent. In one example, the dielectric tangent of the cured product is preferably 0.0100 or less, more preferably 0.0080 or less, and still more preferably 0.0070 or less. The lower limit of the dielectric tangent is not particularly limited and can be, for example, 0.0010 or more. When using a resin sheet having such a resin composition layer, an insulating layer with a low dielectric tangent can be obtained. The dielectric tangent can be measured by the cavity resonance perturbation method at a measurement frequency of 5.8 GHz and a measurement temperature of 23°C.

[0208] The thickness of the resin composition layer may be equal to or greater than the depth of the cavity, or may be less than the depth of the cavity. Therefore, the thickness of the resin composition layer may be equal to or greater than the thickness of the core substrate, or may be less than the thickness of the core substrate. From the viewpoint of supplying a sufficient amount of the resin composition into the cavity, the thickness of the resin composition layer is preferably 10 μm or more, more preferably 20 μm or more, and still more preferably 30 μm or more. Also, from the viewpoint of thinning the circuit board, the thickness of the resin composition layer is preferably 400 μm or less, more preferably 300 μm or less, and still more preferably 200 μm or less.

[0209] According to the study by the present inventor, it has been found that, in the past, when a thin resin composition layer is used to fill a deep cavity with a resin composition, voids tended to occur particularly easily. In contrast, even when such a thin resin composition layer is used, the production method according to the above-mentioned embodiment can suppress the occurrence of voids. From the viewpoint of effectively utilizing the effect of suppressing the occurrence of voids, the ratio of the thickness of the resin composition layer to the depth of the cavity (thickness of the resin composition layer / depth of the cavity) may be in a specific range. Specifically, the range of the ratio (thickness of the resin composition layer / depth of the cavity) is preferably less than 1.0, more preferably less than 0.5, even more preferably less than 0.3, even more preferably less than 0.2, even more preferably less than 0.1, and is preferably 0.005 or more, more preferably 0.01 or more, and even more preferably 0.02 or more. Generally, the depth of the cavity corresponds to the thickness of the core substrate, and therefore the range of the ratio of the thickness of the resin composition layer to the thickness of the core substrate (thickness of the resin composition layer / thickness of the core substrate) can be the same as the above-mentioned range of the ratio of the thickness of the resin composition layer to the depth of the cavity (thickness of the resin composition layer / depth of the cavity).

[0210] In addition, according to the study by the present inventor, it has been found that, in the past, when a thick part is embedded using a thin resin composition layer, voids tended to occur particularly easily. In contrast, even when such a thin resin composition layer is used, the production method according to the above-mentioned embodiment can suppress the occurrence of voids. From the viewpoint of effectively utilizing the effect of suppressing the occurrence of voids, the ratio of the thickness of the resin composition layer to the thickness of the part (thickness of the resin composition layer / thickness of the part) may be in a specific range. Specifically, the range of the ratio (thickness of the resin composition layer / thickness of the part) is preferably less than 1.0, more preferably less than 0.5, even more preferably less than 0.3, even more preferably less than 0.2, particularly preferably less than 0.15, and is preferably 0.01 or more, more preferably 0.03 or more, even more preferably 0.05 or more, and even more preferably 0.08 or more.

[0211] The resin sheet may include an optional layer in combination with the support and the resin composition layer. For example, the optional layer may be a protective film equivalent to the support provided on the surface of the resin composition layer not bonded to the support (i.e., the surface opposite to the support). The thickness of the protective film is not particularly limited, but is, for example, 1 μm to 40 μm. By laminating the protective film, it is possible to suppress adhesion of dirt and scratches on the surface of the resin composition layer. When the resin sheet has a protective film, the resin sheet can usually be used by peeling off the protective film.

[0212] The resin sheet can be produced, for example, by a method including preparing a resin composition and forming a resin composition layer on a support using the resin composition.

[0213] The resin composition can be produced, for example, by mixing components that can be contained in the resin composition. The components may be mixed partially or entirely at the same time, or may be mixed sequentially. In the process of mixing each component, the temperature may be appropriately set, and thus heating and / or cooling may be performed temporarily or throughout. In addition, stirring or shaking may be performed in the process of mixing each component.

[0214] The formation of a resin composition layer on a support can be carried out, for example, by preparing a liquid (varnish-like) resin composition as is or by dissolving the resin composition in a solvent to prepare a liquid (varnish-like) resin composition, applying this to the support using a coating device such as a die coater, and then drying to form a resin composition layer.

[0215] The solvent may be the same as the (H) solvent described as a component of the resin composition. One type of solvent may be used alone, or two or more types may be used in combination.

[0216] Drying may be performed by heating, blowing hot air, or the like. Drying conditions are not particularly limited, but drying is performed so that the content of the solvent in the resin composition layer is usually 10% by mass or less, preferably 5% by mass or less. Although it varies depending on the boiling point of the solvent in the resin composition, for example, when a resin composition containing 30% by mass to 60% by mass of a solvent is used, the resin composition layer can be formed by drying at 50°C to 150°C for 2 minutes to 10 minutes.

[0217] <Semiconductor device> The circuit board can be used for manufacturing a semiconductor device. The semiconductor device includes the circuit board described above. Examples of the semiconductor device include various semiconductor devices used in electrical products (e.g., computers, mobile phones, smartphones, tablet devices, wearable devices, digital cameras, medical devices, televisions, etc.) and vehicles (e.g., motorcycles, automobiles, trains, ships, aircraft, etc.). These semiconductor devices may be manufactured by a method including manufacturing a circuit board by the manufacturing method described above. EXAMPLES

[0218] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these examples. In the following description, the terms "parts" and "%" used to express amounts refer to "parts by mass" and "% by mass", respectively, unless otherwise specified. Furthermore, the operations described below were carried out at room temperature (23°C) and atmospheric pressure (1 atm), unless otherwise specified.

[0219] <Synthesis Example 1. Synthesis of Elastomer A> In a reaction vessel, 69 g of bifunctional hydroxyl-terminated polybutadiene ("G-3000" manufactured by Nippon Soda Co., Ltd., number average molecular weight = 3000, hydroxyl equivalent = 1800 g / eq.), 40 g of aromatic hydrocarbon mixed solvent ("IPZOL 150" manufactured by Idemitsu Petrochemical Co., Ltd.), and 0.005 g of dibutyltin laurate were placed and mixed to dissolve uniformly. When the mixture became uniform, the temperature was raised to 60°C, and 8 g of isophorone diisocyanate ("IPDI" manufactured by Evonik Degussa Japan Co., Ltd., isocyanate equivalent = 113 g / eq.) was added while stirring, and the reaction was carried out for about 3 hours.

[0220] Next, 23 g of cresol novolak resin (DIC "KA-1160", hydroxyl equivalent = 117 g / eq.) and 80 g of ethyl diglycol acetate (Daicel) were added to the reaction mixture, and the mixture was heated to 150°C with stirring and reacted for about 10 hours. -1 The disappearance of the NCO peak was confirmed. The disappearance of the NCO peak was regarded as the end point of the reaction, and the reaction product was cooled to room temperature. The reaction product was then filtered through a 100-mesh filter cloth to obtain an elastomer A having a butadiene structure and a phenolic hydroxyl group (phenolic hydroxyl group-containing butadiene resin: non-volatile components 45% by mass). The number average molecular weight of elastomer A was 5900, and the glass transition temperature was -7°C.

[0221] <Explanation of inorganic filler used> Inorganic filler A: average particle size 3μm, specific surface area 3.5m 2 / g, silica particles surface-treated with a surface treatment agent ("KBM573" manufactured by Shin-Etsu Chemical Co., Ltd.). Inorganic filler B: average particle size 0.5μm, specific surface area 5.9m 2 / g, silica particles surface-treated with a surface treatment agent ("KBM573" manufactured by Shin-Etsu Chemical Co., Ltd.).

[0222] <Production Example 1. Production of Resin Sheet 1 (Resin Sheet Used in Examples 1 and 2 and Comparative Example 1)> 30 parts of bixylenol type epoxy resin ("YX4000HK" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent weight approximately 185 g / eq.), 20 parts of biphenyl type epoxy resin ("NC3000L" manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent weight approximately 272 g / eq.), and 10 parts of naphthylene ether type epoxy resin ("HP-6000L" manufactured by DIC Corporation, epoxy equivalent weight 215 g / eq.) were dissolved by heating with stirring in a mixed solvent of 20 parts of solvent naphtha and 30 parts of cyclohexanone. This was cooled to room temperature to prepare a dissolved composition of the epoxy resins. The epoxy resin solution composition was mixed with 30 parts of elastomer A (45% by mass non-volatile content), 20 parts of a phenolic curing agent having a triazine skeleton and a novolac structure (DIC Corporation's "LA3018-50P", active group equivalent of about 151 g / eq., 2-methoxypropanol solution with 50% non-volatile content), 50 parts of an active ester curing agent (DIC Corporation's "HPC-8000-65T", active group equivalent of about 223 g / eq., toluene solution with 65% non-volatile content), and 100 parts of a carbodiimide. A resin varnish 1 was produced by mixing 10 parts of a system curing agent (Nisshinbo Chemical's "V-03", carbodiimide group equivalent 216 g / eq., toluene solution with 50% nonvolatile content), 1 part of a curing accelerator (1-benzyl-2-phenylimidazole (1B2PZ), MEK solution with 10% nonvolatile content), 10 parts of a curing accelerator (4-dimethylaminopyridine (DMAP), MEK solution with 2.5% solid content), and 650 parts of inorganic filler A and uniformly dispersing the mixture in a high-speed rotating mixer.

[0223] A polyethylene terephthalate film ("AL5" manufactured by Lintec Corporation, thickness 38 μm) with a release layer was prepared as a support. The resin varnish 1 was uniformly applied onto the release layer of this support so that the thickness of the resin composition layer after drying would be 65 μm. Thereafter, the resin varnish 1 was dried at 80°C to 120°C (average 100°C) for 2.5 minutes to produce a resin sheet 1a with a support and a resin composition layer.

[0224] Furthermore, a resin sheet 1b for CTE measurement was produced by the same method as that for producing the resin sheet 1a, except that the amount of resin varnish 1 applied was changed so that the thickness of the resin composition layer after drying was 40 μm.

[0225] <Production Example 2. Production of Resin Sheet 2 (Resin Sheet Used in Examples 3 to 4 and Comparative Example 2)> Two parts of a bisphenol A type epoxy resin ("YD-8125G" manufactured by Nippon Steel Chemical & Material Co., Ltd., epoxy equivalent of about 174 g / eq.), 5 parts of a bixylenol type epoxy resin ("YX4000HK" manufactured by Mitsubishi Chemical Co., Ltd., epoxy equivalent of about 185 g / eq.), 5 parts of a naphthylene ether type epoxy resin ("EXA-7311-G4" manufactured by DIC Corporation, epoxy equivalent of about 213 g / eq.), 15 parts of a biphenyl type epoxy resin ("NC3000L" manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent of about 272 g / eq.), and 10 parts of a phenoxy resin ("YX7553BH30" manufactured by Mitsubishi Chemical Co., Ltd., a 1:1 solution of cyclohexanone:methyl ethyl ketone (MEK) with a solid content of 30 mass%) were dissolved in a mixed solvent of 15 parts of solvent naphtha and 10 parts of cyclohexanone by heating with stirring. After cooling to room temperature, 5 parts of a triazine skeleton-containing cresol novolac-based hardener (DIC Corporation's "LA3018-50P", hydroxyl group equivalent of about 151 g / eq., 2-methoxypropanol solution with a solid content of 50%), 12 parts of an active ester-based hardener (DIC Corporation's "HPC-8000-65T", active group equivalent of about 223 g / eq., toluene solution with a non-volatile content of 65% by mass), and a carbodiimide resin (Nisshinbo Chemical Corporation's "V-03", carbodiimide equivalent of 216 g / eq.) were added thereto. eq., 50% by mass of non-volatile components in toluene solution), 10 parts of a curing accelerator (4-dimethylaminopyridine (DMAP), 2.5% by mass of solids in MEK solution), 3 parts of a flame retardant (Sankosha's "HCA-HQ", 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide, average particle size 1.2 μm), and 130 parts of inorganic filler B were mixed and uniformly dispersed in a high-speed rotating mixer to produce resin varnish 2.

[0226] A resin sheet 2a having a support and a resin composition layer (thickness 65 μm) and a resin sheet 2b for CTE measurement having a support and a resin composition layer (thickness 40 μm) were produced by the same method as in Production Example 1, except that the resin varnish 2 thus obtained was used instead of resin varnish 1.

[0227] <Production Example 3. Production of Resin Sheet 3 (Resin Sheet Used in Examples 5 to 6 and Comparative Example 3)> 10 parts of bisphenol type epoxy resin ("ZX1059" manufactured by Nippon Steel Chemical & Material Co., Ltd., a 1:1 mixture of bisphenol A type and bisphenol F type, epoxy equivalent 169 g / eq.) and 50 parts of naphthol type epoxy resin ("ESN475V" manufactured by Nippon Steel Chemical & Material Co., Ltd., epoxy equivalent approximately 330 g / eq.) were heated and dissolved in 40 parts of solvent naphtha with stirring. This was cooled to room temperature to prepare a dissolved composition of the epoxy resin. To this epoxy resin solution, 5 parts of a phenoxy resin ("YX7553BH30" manufactured by Mitsubishi Chemical Corporation, a 1:1 solution of MEK and cyclohexanone with a non-volatile content of 30% by mass), 5 parts of a phenolic hardener having a triazine skeleton and a novolak structure ("LA3018-50P" manufactured by DIC Corporation, active group equivalent of about 151 g / eq., 2-methoxypropanol solution with a non-volatile content of 50%), 70 parts of an active ester hardener ("HPC-8000-65T" manufactured by DIC Corporation, active group equivalent of about 223 g / eq., toluene solution with a non-volatile content of 65% by mass), 100 parts of a (meth)acrylic acid ester (" A resin varnish 3 was produced by mixing 20 parts of "A-DOG", (meth)acryloyl group equivalent 156 g / eq.), 20 parts of a carbodiimide curing agent ("V-03" manufactured by Nisshinbo Chemical Inc., carbodiimide group equivalent 216 g / eq., toluene solution with 50% nonvolatile content by mass), 15 parts of a curing accelerator (1-benzyl-2-phenylimidazole (1B2PZ), MEK solution with 10% nonvolatile content by mass), 6 parts of a polymerization initiator ("Perkmyl D" manufactured by NOF Corporation, MEK solution with 20% nonvolatile content by mass), 420 parts of inorganic filler B, 10 parts of cyclohexanone, and 10 parts of MEK, and dispersing the mixture uniformly using a high-speed rotating mixer.

[0228] A resin sheet 3a having a support and a resin composition layer (thickness 65 μm) and a resin sheet 3b for CTE measurement having a support and a resin composition layer (thickness 40 μm) were produced by the same method as in Production Example 1, except that the resin varnish 3 thus obtained was used instead of resin varnish 1.

[0229] <Measurement Test of Melt Viscosity and Tanδ> Only the resin composition layer was peeled off from the resin sheets (i.e., resin sheets 1a, 2a, or 3a) having a resin composition layer with a thickness of 65 μm produced in Production Examples 1 to 3, and the resin composition layer was compressed with a mold to prepare measurement pellets (diameter 18 mm, 1.2 g to 1.3 g) of the resin composition.

[0230] Using a dynamic viscoelasticity measuring device ("Rheosol - G3000" manufactured by UBM), for 1.3 g of the measurement pellets of the resin composition, the dynamic viscoelastic modulus was measured, and the melt viscosity (poise) and loss tangent tanδ at the extrusion temperatures shown in Table 1 and Table 2 were calculated. The measurement of the dynamic viscoelastic modulus was carried out using a parallel plate with a diameter of 18 mm, heating from an initial temperature of 70°C to 180°C at a heating rate of 5°C / min. Also, the measurement conditions were a measurement temperature interval of 2.5°C, a frequency of 1 Hz, and a strain of 5 deg.

[0231] <CTE Measurement Test> A polyethylene terephthalate film (manufactured by Lintec Corporation, "501010", thickness 38 μm, 240 mm square, hereinafter sometimes referred to as "release PET film") having a release-treated surface and an untreated surface without release treatment was prepared. The release PET film was placed on a glass cloth substrate epoxy resin double-sided copper-clad laminate (manufactured by Matsushita Electric Works, "R5715ES", thickness 0.7 mm, 255 mm square) such that the untreated surface of the release PET film was in contact with the laminate. The four sides of the release PET film were fixed to the glass cloth substrate epoxy resin double-sided copper-clad laminate with a polyimide adhesive tape (width 10 mm).

[0232] The resin sheet (i.e., resin sheet 1b, 2b or 3b, 200 mm square) having a 40 μm thick resin composition layer produced in Production Examples 1 to 3 was laminated at the center of a release PET film so that the resin composition layer was in contact with the release surface of the release PET film using a batch-type vacuum pressure laminator (a two-stage build-up laminator "CVP700" manufactured by Nikko Materials Co., Ltd.). The lamination was performed by reducing the pressure for 30 seconds to 13 hPa or less, and then pressing at 100°C and a pressure of 0.74 MPa for 30 seconds.

[0233] Next, the support was peeled off from the resin sheet, and the resin composition layer was thermally cured by heating for 90 minutes in an oven at 200° C. The glass cloth-based epoxy resin double-sided copper-clad laminate and the release PET film were peeled off to obtain a cured product for evaluation as a thermally cured product of the resin composition layer.

[0234] The "cured product for evaluation" was cut to obtain a test piece with a width of about 5 mm and a length of about 15 mm. A thermomechanical analysis was performed on this test piece by a tensile load method using a thermomechanical analyzer (Rigaku's "Thermo Plus TMA8310"). Specifically, after mounting the test piece on the device, measurements were performed twice in succession under the measurement conditions of a load of 1 g and a temperature rise rate of 5°C / min. The first time, the temperature was raised to 200°C, and the second time, the temperature was raised to 260°C. The average linear thermal expansion coefficient (ppm / °C) from 25°C to 150°C in the second measurement was calculated.

[0235] <Example 1> (Manufacturing of evaluation boards) Fig. 7 is a schematic plan view showing the state of the core substrate viewed from the thickness direction to explain the position of the cavities formed in Example 1. As shown in Fig. 7, 20 cavities 211-214, 221-224, 231-234, 241-244, and 251-254 were formed in a copper-clad laminate ("MCL-E-705G" manufactured by Resonac, 250 mm long, 250 mm wide, and 1.4 mm thick) as the core substrate 200. Specifically, four cavities 211-214 were formed in the central portion 210 of the core substrate 200. The opening of each of the cavities 211-214 was a square with a length of 2.2 mm and a width of 2.2 mm. The interval between these cavities 211-214 was 1 mm. Furthermore, in four corners 220, 230, 240 and 250 located 75 mm vertically and horizontally away from the central portion 210, four cavities 221 to 224, 231 to 234, 241 to 244 and 251 to 254 were formed, similarly to the central portion 210.

[0236] A temporary fixing film ("PFDKE-1525TT" manufactured by Arisawa Manufacturing Co., Ltd.) was attached to one side of the core substrate to close one opening of the cavity. A silicon chip (length 2.0 mm, width 2.0 mm, thickness 650 μm) was placed as a component in each cavity to obtain an intermediate substrate.

[0237] The resin sheet 1a produced in Production Example 1 was laminated onto one side of the intermediate substrate using a batch-type vacuum pressure laminator (a two-stage build-up laminator "CVP700" manufactured by Nikko Materials Co., Ltd.) so that the resin composition layer of the resin sheet was bonded to the core substrate of the intermediate substrate. This lamination was carried out by reducing the pressure for 30 seconds to 3 hPa or less, and then pressing the resin sheet with a rigid member made of SUS. The lamination conditions were a pressing temperature of 100°C and a pressing pressure of 15 kgf / cm. 2 The pressing time was 300 seconds.

[0238] After lamination, the support was peeled off. The resin composition layer was then thermally cured by heating in an oven at 200° C. for 90 minutes to obtain an evaluation board corresponding to a circuit board. In the evaluation board obtained, the silicon chip in the cavity of the core board was embedded in the cured resin composition filled in the cavity.

[0239] (Void evaluation test) All 20 cavities in the evaluation substrate were observed, and the number of voids that occurred in the cavities was counted. The number of voids was evaluated according to the following criteria. Excellent: No voids Acceptable: 1 to 3 cavities with voids Defective: 4 to 20 cavities with voids

[0240] <Example 2> An intermediate substrate was produced by the same method as in Example 1. The resin sheet 1a produced in Production Example 1 was laminated onto one side of the intermediate substrate using a batch-type vacuum pressure laminator (a two-stage build-up laminator "CVP700" manufactured by Nikko Materials Co., Ltd.) so that the resin composition layer of the resin sheet 1a was bonded to the core substrate of the intermediate substrate. This lamination was performed by reducing the pressure for 30 seconds to 3 hPa or less, pressing the resin sheet with a rubber elastic member, and then further pressing the resin sheet with a SUS rigid member. The lamination conditions were a pressing temperature of 100°C and a pressing pressure of 10 kgf / cm in the pressing process using the elastic member. 2 The pressing time was 10 seconds. In the pressing process using the rigid member, the pressing temperature was 100°C and the pressing pressure was 7 kgf / cm 2 The pressing time was 35 seconds.

[0241] After lamination, the support was peeled off. The resin composition layer was then thermally cured by heating in an oven at 200° C. for 90 minutes to obtain an evaluation board corresponding to a circuit board. In the obtained evaluation board, the silicon chip in the cavity of the core board was embedded in the cured resin composition filled in the cavity. The evaluation board was subjected to a void evaluation test by the same method as in Example 1.

[0242] <Example 3> The evaluation substrate was manufactured and evaluated in the same manner as in Example 1, except that the resin sheet 2a manufactured in Manufacturing Example 2 was used instead of the resin sheet 1a manufactured in Manufacturing Example 1, and the pressing temperature during lamination was changed to 70°C.

[0243] <Example 4> The evaluation substrate was manufactured and evaluated in the same manner as in Example 2, except that the resin sheet 2a manufactured in Manufacturing Example 2 was used instead of the resin sheet 1a manufactured in Manufacturing Example 1, and the pressing temperature during lamination was changed to 70°C in both the pressing process using the elastic member and the pressing process using the rigid member.

[0244] <Example 5> An evaluation substrate was produced and evaluated in the same manner as in Example 1, except that the resin sheet 3a produced in Production Example 3 was used instead of the resin sheet 1a produced in Production Example 1.

[0245] <Example 6> An evaluation substrate was produced and evaluated in the same manner as in Example 2, except that the resin sheet 3a produced in Production Example 3 was used instead of the resin sheet 1a produced in Production Example 1.

[0246] <Comparative Example 1> The pressing force during the pressing process using the elastic member is 7kgf / cm 2 and the pressing time was changed to 30 seconds. Furthermore, the pressing pressure in the pressing process using the rigid member was changed to 5.5 kgf / cm 2 and the pressing time was changed to 60 seconds. Except for the above, the evaluation substrate was manufactured and evaluated in the same manner as in Example 2.

[0247] <Comparative Example 2> Instead of the resin sheet 1a manufactured in Manufacturing Example 1, the resin sheet 2a manufactured in Manufacturing Example 2 was used. In addition, the pressing temperature in the pressing step using the elastic member was changed to 70°C, and the pressing pressure was changed to 7 kgf / cm. 2The pressing temperature in the pressing process using the rigid member was changed to 70°C, and the pressing pressure was changed to 5.5kgf / cm. 2 and the pressing time was changed to 60 seconds. Except for the above, the evaluation substrate was manufactured and evaluated in the same manner as in Example 2.

[0248] <Comparative Example 3> The resin sheet 3a manufactured in Manufacturing Example 3 was used instead of the resin sheet 1a manufactured in Manufacturing Example 1. The pressing pressure in the pressing step by the elastic member was 7 kgf / cm 2 and the pressing time was changed to 30 seconds. Furthermore, the pressing pressure in the pressing process using the rigid member was changed to 5.5 kgf / cm 2 and the pressing time was changed to 60 seconds. Except for the above, the evaluation substrate was manufactured and evaluated in the same manner as in Example 2.

[0249] <Comparative Example 4> In the pressing process using the elastic member, the pressing pressure is set to 20 kgf / cm 2 The evaluation substrate was manufactured and evaluated in the same manner as in Example 2, except that the pressure was changed to 60 seconds and the pressing time was changed to 60 seconds.

[0250] <Comparative Example 5> The pressing force during the pressing process using the rigid member is 2kgf / cm 2 The evaluation substrate was manufactured and evaluated in the same manner as in Example 2, except that the pressure was changed to 30 seconds and the pressing time was changed to 30 seconds.

[0251] <Comparative Example 6> The pressing force in the pressing process using the rigid member is 5kgf / cm 2 The evaluation substrate was manufactured and evaluated in the same manner as in Example 1, except that the pressure was changed to 10 s and the pressing time was changed to 20 s.

[0252] <Result> The results of the Examples and Comparative Examples are shown in the following table. In the table, the abbreviations have the following meanings. (B) Content: The content of (B) inorganic filler relative to 100 mass% of non-volatile components. Pressing temperature: the pressing temperature in steps (3) and (5). Melt viscosity: the melt viscosity of the resin composition layer at the pressing temperature. Tan δ: tan δ of the resin composition layer at the pressing temperature. CTE: The average coefficient of linear thermal expansion at 25°C to 150°C of a cured product obtained by curing a resin composition layer at 200°C for 90 minutes.

[0253] [Table 1]

[0254] [Table 2] [Explanation of symbols]

[0255] 10 Core Board 10U front page 10D second side 20 Cavity 21 Opening 22 Opening 30 Temporary Fixing Film 30U adhesive side 40 parts 50 Resin sheet 51 Support 52 Resin composition layer 60 Rigid Members 60D Pressing surface 70 Insulating layer 80 Elastic member 80D Pressing surface 100 Circuit Board

Claims

1. A method for producing a circuit board using a core board having a cavity penetrating the core board, a temporary fixing film, and a resin sheet including a support and a resin composition layer; The manufacturing method comprises: A step (1) of adhering a temporary fixing film to one surface of a core substrate; (2) placing a part in the cavity; (3) pressing the support with a rigid member to laminate the resin sheet and the core substrate so that the resin composition layer and the core substrate are bonded; A step (4) of curing the resin composition layer; in that order; The manufacturing method may or may not include a step (5) between the step (2) and the step (3) of pressing the support with an elastic member so as to bond the resin composition layer and the core substrate; In step (3), the pressing force F with which the rigid member presses the support Ｒ and pressing time T Ｒ The product of H Ｒ , 200 kgf sec / cm ２ And that is all; When the manufacturing method includes the step (5), the pressing force F with which the elastic member presses the support in the step (5) Ｅ and pressing time T Ｅ The product of H Ｅ A method for producing a circuit board, wherein the following formula (I) is satisfied: 2×H Ｅ <H Ｒ (I)

2. The method for producing a circuit board according to claim 1 , wherein the pressing temperature in the step (3) is 50° C. or higher and 140° C. or lower.

3. The method for producing a circuit board according to claim 1 , wherein the pressing temperature in step (5) is 50° C. or higher and 140° C. or lower.

4. The method for producing a circuit board according to claim 1 , wherein the resin composition layer comprises (A) a curable resin and (B) an inorganic filler.

5. The method for producing a circuit board according to claim 4 , wherein the amount of the inorganic filler (B) contained in the resin composition layer is 65% by mass or more relative to 100% by mass of the nonvolatile components in the resin composition layer.

6. The method for producing a circuit board according to claim 1, wherein the resin composition layer is cured at 200°C for 90 minutes to obtain a cured product having an average linear thermal expansion coefficient of less than 25 ppm / °C from 25°C to 150°C.

7. 2. The method for manufacturing a circuit board according to claim 1, wherein a ratio of a volume of the component placed in the cavity to a volume of the cavity is 30 volume % or more.

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