Method for manufacturing circuit board, and resin sheet used therein

Abstract

Provided are: a method for manufacturing a circuit board; and a resin sheet used therein, wherein even when using a substrate having a large area, it is possible to suppress an increase in the surface potential of a support while suppressing the generation of interfacial voids. The method for manufacturing a circuit board comprises (X) a step in which a resin sheet including a support having first and second surfaces and a resin composition layer disposed on the second surface of the support is laminated onto a substrate such that the resin composition layer is bonded to the substrate, wherein the following conditions (i), (ii-1), and (ii-2) are satisfied.　(i) The atmospheric pressure is reduced at the same time as or before the resin composition layer and the substrate are bonded. (ii-1) The total specific surface area of an inorganic filler in the resin composition layer is 1.5 m2 / g or more (in terms of non-volatile components). (ii-2) The surface resistivity of the first surface of the support is 1.0×1010 Ω / sq. or less.

Description

Circuit board manufacturing method and resin sheet used therein

[0001] The present invention relates to a method for manufacturing a circuit board and a resin sheet used in the same.

[0002] In the manufacture of circuit boards such as wafer level packages (WLPs) and panel level packages (PLPs), redistribution layers are generally formed by applying a curable resin material to a substrate such as a wafer or panel substrate using a spin coating method, curing the material to form an insulating layer, then forming a conductor layer, and repeating this process to form multiple layers (see, for example, Patent Document 1).

[0003] JP 2018-87986 A

[0004] As electronic devices become more sophisticated, circuit boards for semiconductor packages are required to have finer wiring, and to achieve this, it is necessary to form insulating layers with excellent surface flatness. Furthermore, the insulating layers of circuit boards are required to have various properties, such as excellent dielectric properties to reduce transmission loss when operating in a high-frequency environment, and the ability to suppress warpage when forming large-area insulating layers in the manufacture of WLP or PLP. These requirements are likely to become increasingly stringent in the future.

[0005] The present inventors attempted to use an insulating material in the form of a resin sheet in order to achieve high functionality in an insulating layer, such as good dielectric properties and low warpage, while also providing an insulating layer with good surface flatness. Specifically, they investigated a technology in which a resin sheet having a resin composition layer provided on a support is used, and the resin composition layer is laminated on a substrate such as a wafer and cured to form an insulating layer. As a result, they confirmed that when the substrate has a large area, voids (hereinafter also referred to as "interface voids") tend to occur at the interface between the resin composition layer and the substrate, which can cause swelling or cracks in the insulating layer during curing, making it impossible to manufacture the desired circuit board.

[0006] As a result of examining a technology that can suppress the generation of interfacial voids even when an insulating material in the form of a resin sheet is applied to a substrate with a large area, the following was found: (a) the atmospheric pressure is reduced simultaneously with or before the bonding of the resin composition layer and the substrate, and (b) the total specific surface area of ​​the inorganic filler in the resin composition layer is 1.5 m２ It has been found that the generation of interfacial voids can be suppressed by adjusting the size and content of the inorganic filler so that the porosity is 1 / g or more (calculated as non-volatile components).

[0007] On the other hand, it has been found that although the above techniques (a) and (b) can suppress the generation of interfacial voids, the surface potential of the support increases to a degree that raises concerns about damage to the semiconductor chip, particularly when the substrate has a large area. Such an increase in surface potential tends to be significant in the composition of the resin composition layer aimed at further reducing the dielectric loss tangent and warpage.

[0008] The object of the present invention is to provide a method for manufacturing a circuit board, and a resin sheet to be used therefor, which can suppress the occurrence of interfacial voids and the increase in the surface potential of the support, even when a large-area substrate is used.

[0009] As a result of extensive investigations, the present inventors have found that the above-mentioned problems can be solved by a method for manufacturing a circuit board and a resin sheet having the following configurations, and have thus completed the present invention.

[0010] That is, the present invention includes the following: [1] A method for producing a circuit board, comprising: (X) a step of laminating a resin sheet, which includes a support having a first and second surface and a resin composition layer provided on the second surface of the support, onto a substrate so that the resin composition layer is bonded to the substrate, and which satisfies the following conditions (i), (ii-1), and (ii-2): (i) reducing the atmospheric pressure simultaneously with or before bonding the resin composition layer to the substrate; (ii-1) reducing the atmospheric pressure so that the total specific surface area of ​​the inorganic filler in the resin composition layer is 1.5 m; ２ / g or more (non-volatile component equivalent). (ii-2) The surface resistivity of the first surface of the support is 1.0 × 10 １０[2] The method according to [1], wherein the substrate is (a) a semiconductor wafer having an electrode pad surface, (b) a carrier substrate on which a plurality of semiconductor chips obtained by dividing the semiconductor wafer of (a) are arranged spaced apart from each other so that the electrode pad surfaces are exposed, (c) a substrate on which a sealing resin for sealing the semiconductor chips is further provided on the carrier substrate of (b), (d) a substrate on which a rewiring layer is further provided on the sealing resin of the substrate of (c), (e) a carrier substrate on which a plurality of semiconductor chips obtained by dividing the semiconductor wafer of (a) are arranged spaced apart from each other so that the electrode pad surfaces face the carrier substrate, (f) a semiconductor chip sealing substrate on which the electrode pad surfaces are exposed, which is obtained by further providing a sealing resin for sealing the semiconductor chips on the carrier substrate of (e) and then peeling the carrier substrate, or (g) a substrate on which a rewiring layer is further provided on the electrode pad surface side of the semiconductor chip sealing substrate of (f). [3] The method according to [1], wherein the substrate is a substrate with a release layer. [4] The method according to any one of [1] to [3], wherein the main surface dimension (minimum dimension) of the substrate is 150 mm or more. [5] The method according to any one of [1] to [4], comprising, after step (X), one or more steps selected from: (1) a step of curing the resin composition layer to form an insulating layer, (2) a step of drilling the insulating layer, (3) a step of desmearing the insulating layer, and (4) a step of forming a conductor layer on the surface of the insulating layer. [6] The method according to any one of [1] to [5], wherein the resin composition layer contains a stress relaxation material. [7] The method according to any one of [1] to [6], wherein the circuit board is a wafer-level package or a panel-level package. [8] A resin sheet used in a method for producing a circuit board, comprising a step of laminating a resin sheet including a resin composition layer on a substrate so that the resin composition layer is bonded to the substrate, and satisfying the following condition (i): (i) reducing the atmospheric pressure simultaneously with or before bonding the resin composition layer to the substrate, the resin sheet comprising a support having first and second surfaces and a resin composition layer provided on the second surface of the support, and (ii-1) a total specific surface area of ​​the inorganic filler in the resin composition layer is 1.5 m ２ / g or more (non-volatile component equivalent), and (ii-2) the surface resistivity of the first surface of the support is 1.0 × 10 １０[9] The resin sheet according to [8], wherein the main surface dimension (minimum dimension) of the substrate is 150 mm or more.

[10] The resin sheet according to [8], wherein the total specific surface area of ​​the inorganic filler in the resin composition layer is 4.0 m ２

[11] The resin sheet according to [8] or [9], wherein the surface resistivity of the second surface of the support is 1.0 × 10 / g or more (in terms of non-volatile components). １０

[10] The resin sheet according to any one of [8] to

[10] , wherein the resin composition layer has a melt viscosity of 50,000 poise at 100°C or less.

[11] The resin sheet according to any one of [8] to

[10] , wherein the resin composition layer contains a stress relaxation material.

[12] The resin sheet according to any one of [8] to

[11] , wherein the resin composition layer has a melt viscosity of 50,000 poise at 100°C or less.

[13] The resin sheet according to any one of [8] to

[12] , wherein the resin composition layer has a melt viscosity of 50,000 poise at 100°C or less.

[0011] According to the present invention, it is possible to provide a method for manufacturing a circuit board and a resin sheet used therefor, which can suppress the occurrence of interfacial voids and the increase in the surface potential of the support, even when a large-area substrate is used.

[0012] The present invention will be described in detail below with reference to preferred embodiments thereof. However, the present invention is not limited to the following embodiments and examples, and can be implemented with any modifications within the scope of the claims of the present invention and their equivalents.

[0013] [Method for manufacturing circuit board] The method for manufacturing a circuit board of the present invention (hereinafter also simply referred to as "the manufacturing method of the present invention") comprises: (X) a step of laminating a resin sheet comprising a support having first and second surfaces and a resin composition layer provided on the second surface of the support onto a substrate such that the resin composition layer is bonded to the substrate, and is characterized in that the following conditions (i), (ii-1) and (ii-2) are satisfied: (i) the atmospheric pressure is reduced simultaneously with or before bonding of the resin composition layer to the substrate; (ii-1) the total specific surface area of ​​the inorganic filler in the resin composition layer is 1.5 m ２ / g or more (non-volatile component equivalent). (ii-2) The surface resistivity of the first surface of the support is 1.0 × 10 １０ Ω / sq. or less

[0014] As mentioned above, various properties are required for the insulating layer of a circuit board, such as excellent dielectric properties to reduce transmission loss when operating in a high-frequency environment, and the ability to suppress warping when forming a large-area insulating layer in the manufacture of WLP or PLP, and these requirements are likely to become increasingly strict in the future. One approach to meeting these requirements is to change the composition of the insulating material, but with conventional ink- or granular-form insulating materials, it is sometimes difficult to sufficiently adjust the coatability and melt flowability when applied to a substrate while meeting the above requirements, and there are limitations to forming an insulating layer with good surface flatness to achieve even finer wiring on circuit boards.

[0015] The present inventors have attempted to use an insulating material in the form of a resin sheet in order to obtain an insulating layer that satisfies the characteristics required for an insulating layer of a circuit board to a high degree and has good surface flatness. In this regard, it has been confirmed that when an insulating material in the form of a resin sheet is applied to a substrate with a large area, interfacial voids may occur, making it impossible to manufacture the desired circuit board. The occurrence of these interfacial voids can be prevented by improvements in the equipment and process aspects and the composition of the insulating material, namely, (a) reducing the atmospheric pressure simultaneously with or before bonding the resin composition layer to the substrate, and (b) reducing the total specific surface area of ​​the inorganic filler in the resin composition layer to 1.5 m. ２ / g or more (non-volatile component equivalent). On the other hand, it has been found that when the above techniques (a) and (b) are adopted, a new problem arises in that the surface potential of the support increases to a level that raises concerns about damage to the semiconductor chip, particularly when the area of ​​the substrate is large. It has also been found that the problem of such an increase in surface potential tends to become more pronounced in resin composition layer compositions aiming for even lower dielectric tangent and reduced warpage.

[0016] In contrast, the manufacturing method of the present invention, which satisfies all of the above specific conditions (i), (ii-1), and (ii-2), can suppress the occurrence of interfacial voids and suppress an increase in the surface potential of the support, even when an insulating material in the form of a resin sheet is applied to a large-area substrate. Combined with the inherent advantage of the approach of employing an insulating material in the form of a resin sheet, which is that it is easy to form an insulating layer with good surface flatness even when compositional improvements are made to highly satisfy the properties required of the insulating layer of a circuit board, the manufacturing method of the present invention significantly contributes to realizing even finer wiring while highly satisfying the properties required of the insulating layer of a circuit board.

[0017] <Step (X)> The method for producing a circuit board of the present invention includes: (X) a step of laminating a resin sheet, which includes a support having a first surface and a second surface and a resin composition layer provided on the second surface of the support, onto a substrate such that the resin composition layer is bonded to the substrate.

[0018] The "substrate" used in step (X) is a circuit board that is ｓｔWhen manufacturing using the chip-first process, a semiconductor wafer having a circuit element with a predetermined function and an electrode pad surface on which a plurality of electrode pads electrically connected to the circuit element are formed may be used. The semiconductor wafer is preferably, but not limited to, a silicon (Si)-based wafer. For example, a gallium arsenide (GaAs)-based, indium phosphide (InP)-based, gallium phosphide (GaP)-based, gallium nitride (GaN)-based, gallium telluride (GaTe)-based, zinc selenium (ZnSe)-based, silicon carbide (SiC)-based wafer may also be used. The chip-first process is a process in which a semiconductor chip is first provided and then a rewiring layer is formed on the electrode pad surface (e.g., JP 2002-289731 A, JP 2006-173345 A, etc.). In such a chip 1st method, particularly when manufacturing a fan-out structure package, the semiconductor wafer is first singulated, and each semiconductor chip is arranged spaced apart from one another on a carrier substrate, followed by resin sealing. A rewiring layer is then formed on the exposed electrode pad surfaces and the surrounding sealing resin layer (e.g., JP 2012-15191 A, JP 2015-126123 A, etc.). As the carrier substrate, a known substrate used in manufacturing fan-out structure packages may be used, and the type thereof is not particularly limited, but examples include a glass substrate, a metal substrate, a plastic substrate, etc. In such an embodiment, the "substrate" referred to in step (X) may be a substrate in which singulated semiconductor chips are sealed with sealing resin around their periphery so that their electrode pad surfaces are exposed. For example, a carrier substrate may be used on which multiple semiconductor chips formed by singulating a semiconductor wafer are arranged spaced apart from one another so that their electrode pad surfaces are exposed, and a sealing resin for sealing the semiconductor chips is further provided on the carrier substrate. As described below, the method for manufacturing a circuit board of the present invention is widely applicable to the manufacture of circuit boards that include a step of laminating a resin sheet onto a substrate, and can be applied not only to the formation of a rewiring layer (insulating layer) as described above, but also to the formation of a sealing layer or a solder resist layer.For example, when forming a sealing layer in manufacturing a fan-out structure package using the chip 1st method, the "substrate" referred to in step (X) may be a carrier substrate on which multiple semiconductor chips formed by dividing a semiconductor wafer are spaced apart from one another. As described below, circuit board manufacturing methods can be classified into face-up and face-down types based on the chip mounting direction. In the face-up type, the semiconductor chip is positioned so that the electrode pad surface is exposed, while in the face-down type, the semiconductor chip is positioned so that the electrode pad surface faces the carrier substrate. Furthermore, when forming a solder resist layer, step (X) may be performed to form a protective layer after forming a rewiring layer (the manufacturing procedure including the formation of a conductor layer will be described later).

[0019] Therefore, in one embodiment, the base material is (a) a semiconductor wafer having an electrode pad surface, (b) a carrier substrate having a plurality of semiconductor chips obtained by dividing the semiconductor wafer of (a) arranged thereon at a distance from one another so that the electrode pad surfaces are exposed, (c) a substrate having a sealing resin further provided on the carrier substrate of (b) that seals the semiconductor chips, (d) a substrate having a redistribution layer further provided on the sealing resin of the substrate of (c), (e) a carrier substrate having a plurality of semiconductor chips obtained by dividing the semiconductor wafer of (a) arranged thereon at a distance from one another so that the electrode pad surfaces face the carrier substrate, (f) a semiconductor chip sealing substrate having an exposed electrode pad surface, which is obtained by further providing a sealing resin further on the carrier substrate of (e) that seals the semiconductor chips and then peeling off the carrier substrate, or (g) a substrate having a redistribution layer further provided on the electrode pad surface side of the semiconductor chip sealing substrate of (f). Here, (a) corresponds to the case where a rewiring layer (insulating layer) is formed when manufacturing a fan-in structure package, (c) and (f) correspond to the case where a rewiring layer (insulating layer) is formed when manufacturing a fan-out structure package, (b) and (e) correspond to the case where a sealing layer is formed, and (d) and (g) correspond to the case where a solder resist layer is formed. Also, (b) to (d) correspond to the case where a face-up type method is adopted, and (e) to (g) correspond to the case where a face-down type method is adopted.

[0020] In addition, the circuit board is covered with the rewiring layer 1st (RDL-1 ｓｔ When manufacturing the circuit board by the 1st rewiring layer method, the "substrate" used in step (X) may be a substrate with a release layer. The 1st rewiring layer method is a method in which a rewiring layer is first provided, and then a semiconductor chip is provided on the rewiring layer in a state in which the electrode pad surface can be electrically connected to the rewiring layer (e.g., JP 2015-35551 A, JP 2015-170767 A, etc.). In the 1st rewiring layer method, after providing the semiconductor chip on the rewiring layer, the substrate with a release layer is peeled off to expose the rewiring layer. Such a 1st rewiring layer method is particularly suitable for manufacturing a package with a fan-out structure. The substrate with a release layer may be a known substrate used when manufacturing a circuit board by the 1st rewiring layer method. The type of substrate is not particularly limited, but examples include a glass substrate with a release layer, a metal substrate with a release layer, and a plastic substrate with a release layer.

[0021] Thus, in one embodiment, the substrate is a substrate with a release layer.

[0022] The dimensions of the substrate are not particularly limited and may be determined according to the intended package design. Regarding the dimensions in the direction parallel to the main surface of the substrate (the dimensions in the X-Y direction; also simply referred to as "main surface dimensions"), in the case of a circular or approximately circular substrate (hereinafter also simply referred to as "circular substrate"), the diameter may be, for example, 100 mm (4 inches) or more, or 125 mm (5 inches) or more. According to the manufacturing method of the present invention, substrates with even larger areas can be used while suppressing the occurrence of interfacial voids and an increase in the surface potential of the support. For example, the diameter of the circular substrate may be 150 mm (6 inches) or more, 200 mm (8 inches) or more, 300 mm (12 inches) or more, or 450 mm (18 inches) or more. The upper limit of the diameter of the circular substrate is not particularly limited and may be, for example, 600 mm (24 inches) or less. Furthermore, in the case of a rectangular or substantially rectangular substrate (hereinafter also referred to as a "rectangular substrate"), the main surface dimensions (the short side dimensions in the case of a rectangle) can be, for example, 50 mm or more, 75 mm or more, 100 mm or more, or 125 mm or more. According to the manufacturing method of the present invention, even when a rectangular substrate is used, a substrate with a larger area can be used while suppressing the occurrence of interfacial voids and an increase in the surface potential of the support. For example, the main surface dimensions of the rectangular substrate (the short side dimensions in the case of a rectangle) may be 150 mm or more, 200 mm or more, 300 mm or more, or 450 mm or more. The upper limit of the main surface dimensions of the rectangular substrate is not particularly limited and can be, for example, 1000 mm or less.

[0023] Therefore, in one embodiment, the main surface dimension (minimum dimension) of the substrate is 150 mm or more. Note that the "main surface dimension (minimum dimension)" of the substrate refers to the diameter in the case of a circular substrate, and the dimension of the short side of the main surface in the case of a rectangular substrate.

[0024] As described above, according to the manufacturing method of the present invention, it is possible to use a substrate having a large area while suppressing the generation of interfacial voids and the increase in the surface potential of the support. For example, the area of ​​the substrate (projected area when viewed from a direction perpendicular to the main surface of the substrate) is 150 cm ２ Above, 200cm ２ Above, 300cm ２ Above, 500cm ２ More than 700cm ２ Above, 1000cm ２ Above, 1500cm ２The upper limit of the area of ​​the substrate is not particularly limited, and may be, for example, 10,000 cm ２ Below, 8000cm ２ It could be something like the following:

[0025] In step (X), a resin sheet (details will be described later) is laminated on a substrate so that the resin composition layer of the resin sheet is bonded to the substrate.

[0026] In the manufacturing method of the present invention, the atmospheric pressure is reduced simultaneously with or before bonding the resin composition layer and the substrate ("condition (i)"). By performing step (X) so as to satisfy condition (i) in combination with condition (ii-1) described below for the resin sheet, the generation of interfacial voids can be suppressed even when a large-area substrate is used.

[0027] Step (X) may be performed using any lamination device as long as it can achieve condition (i). For example, lamination devices (sheet attachment devices) described in JP-A-2013-229515 and JP-A-2006-310338 may be used.

[0028] From the viewpoint of suitably suppressing interfacial voids in combination with the condition (ii-1) described below, the atmospheric pressure (the atmospheric pressure in the chamber in which the resin sheet to be treated and the substrate are stored) is preferably 200 hPa or less, more preferably 150 hPa or less, and even more preferably 100 hPa or less, 80 hPa or less, 60 hPa or less, 50 hPa or less, 40 hPa or less, or 30 hPa or less. The atmospheric pressure may be reduced at the same time as the resin composition layer and the substrate are bonded to achieve the above atmospheric pressure, or the pressure may be reduced before the resin composition layer and the substrate are bonded to achieve the above atmospheric pressure, and then the resin composition layer and the substrate may be bonded.

[0029] In step (X), lamination of the resin sheet and the substrate is preferably carried out under heating conditions. The heating temperature when laminating the resin sheet to the substrate is preferably 60°C or higher, more preferably 80°C or higher or 90°C or higher, and the upper limit of the heating temperature is preferably 150°C or lower, more preferably 140°C or lower or 120°C or lower.

[0030] In step (X), the pressure (bonding pressure) when laminating the resin sheet and the substrate is preferably 0.098 MPa or more, more preferably 0.29 MPa or more, and the upper limit of the bonding pressure is preferably 1.77 MPa or less, more preferably 1.47 MPa or less.

[0031] In step (X), the time for laminating the resin sheet and the substrate (pressure bonding time) is preferably 20 seconds or more, more preferably 30 seconds or more, and the upper limit of the pressure bonding time is preferably 400 seconds or less, more preferably 300 seconds or less.

[0032] The member that presses the resin sheet and the substrate together (hereinafter also referred to as "pressure-bonding member") may be determined appropriately depending on the configuration of the lamination device, and examples thereof include an elastic material such as rubber, a metal plate, etc.

[0033] <Other Steps> The manufacturing method of the present invention may further include any conventionally known steps for manufacturing a desired circuit board, as long as the resin sheet satisfies the conditions (ii-1) and (ii-2) described below and step (X) is carried out so as to achieve the above condition (i).

[0034] Hereinafter, an example of other steps that may be further included in the production method of the present invention will be shown.

[0035] In one embodiment, the manufacturing method of the present invention includes, after the above-mentioned step (X), one or more steps selected from: (1) a step of curing the resin composition layer to form an insulating layer, (2) a step of drilling the insulating layer, (3) a step of desmearing the insulating layer, and (4) a step of forming a conductor layer on the surface of the insulating layer. For example, if step (X) is a step of forming a redistribution layer (an insulating layer), steps (1) to (4) may all be performed after step (X), and if step (X) is a step of forming a sealing layer or a solder resist layer, step (1) may be performed after step (X).

[0036] -Step (1)- In step (1), the resin composition layer is cured to form an insulating layer.

[0037] The curing conditions for the resin composition layer are not particularly limited, and conditions that are usually employed when forming an insulating layer for a circuit board may be used.

[0038] For example, the curing conditions for the resin composition layer vary depending on the type of resin composition, etc., but in one embodiment, the curing temperature is preferably 120° C. to 250° C., more preferably 150° C. to 240° C., and even more preferably 180° C. to 230° C. The curing time is preferably 5 minutes to 240 minutes, more preferably 10 minutes to 150 minutes, and even more preferably 15 minutes to 120 minutes.

[0039] Before curing the resin composition layer, the resin composition layer may be preheated at a temperature lower than the curing temperature. For example, prior to curing the resin composition layer, the resin composition layer may be preheated for 5 minutes or more, preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes, and even more preferably 15 minutes to 100 minutes, at a temperature of 50°C to 120°C, preferably 60°C to 115°C, and more preferably 70°C to 110°C. Preheating is advantageous because it makes it easier to achieve an insulating layer with low surface roughness after desmearing.

[0040] -Step (2)- In step (2), holes are drilled in the insulating layer.

[0041] This allows for the formation of holes for electrical continuity, such as via holes, in the insulating layer. Step (2) may be performed using, for example, a drill, a laser, plasma, or the like, depending on the composition of the resin composition used to form the insulating layer. The dimensions and shape of the holes may be determined appropriately depending on the design of the circuit board.

[0042] -Step (3)- In step (3), the insulating layer is subjected to a desmear treatment.

[0043] This makes it possible to remove smears that have occurred in the via holes due to the drilling process. The desmearing treatment is not particularly limited and can be performed by various known methods. In one embodiment, the desmearing treatment may be a dry desmearing treatment, a wet desmearing treatment, or a combination thereof.

[0044] An example of a dry desmear treatment is a desmear treatment using plasma. In the desmear treatment using plasma, a gas is introduced into a plasma generator to generate plasma, and the plasma is used to treat the insulating layer, thereby removing smears generated in the via holes. The method for generating plasma is not particularly limited, and examples include microwave plasma, which generates plasma using microwaves, high-frequency plasma, atmospheric pressure plasma, which is generated under atmospheric pressure, and vacuum plasma, which is generated under vacuum, with vacuum plasma, which is generated under vacuum, being preferred. Furthermore, the plasma used in the desmear treatment is preferably RF plasma, which is excited by high frequency.

[0045] The gas to be converted into plasma is not particularly limited as long as it can remove smears in the via holes. For example, SF ６ In this case, the gas to be converted into plasma may be SF ６ In addition to, for example, Ar, O ２ Among these, from the viewpoint of easily realizing an insulating layer with small surface roughness after desmearing, the gas to be converted into plasma is SF ６ and Ar and O ２ and SF ６ , Ar and O ２ A mixed gas containing the following is more preferred.

[0046] science fiction ６ When a mixed gas of SF and other gases is used, the mixture ratio (SF ６ From the viewpoint of easily realizing an insulating layer having a small surface roughness after desmearing, the ratio of the gas mixture ratio of the insulating layer to the other gases (unit: sccm) is preferably 1 / 0.01 to 1 / 1, more preferably 1 / 0.05 to 1 / 1, and even more preferably 1 / 0.1 to 1 / 1.

[0047] The time for the desmear treatment using plasma is not particularly limited, but is preferably 30 seconds or more, more preferably 60 seconds or more, 90 seconds or more, or 120 seconds or more. The upper limit of the desmear treatment time is preferably 10 minutes or less, more preferably 5 minutes or less, from the viewpoint of easily realizing an insulating layer with small surface roughness after the desmear treatment.

[0048] The desmear treatment using plasma can be carried out using a commercially available plasma desmear treatment apparatus. Among the commercially available plasma desmear treatment apparatuses, examples suitable for use in manufacturing circuit boards include a plasma dry etching apparatus manufactured by Oxford Instruments, a microwave plasma apparatus manufactured by Nissin, and an atmospheric pressure plasma etching apparatus manufactured by Sekisui Chemical Co., Ltd.

[0049] The dry desmearing treatment may also be a dry sandblasting treatment in which an abrasive is sprayed from a nozzle to polish the treatment object. The dry sandblasting treatment can be performed using a commercially available dry sandblasting treatment device. When a water-soluble abrasive is used as the abrasive, washing with water after the dry sandblasting treatment prevents the abrasive from remaining inside the via hole, and smears can be effectively removed.

[0050] From the viewpoint of easily realizing an insulating layer with small surface roughness regardless of the composition of the resin composition layer, etc., the desmearing treatment is preferably a dry desmearing treatment, and among these, a desmearing treatment using plasma is more preferable. Therefore, in a preferred embodiment, the insulating layer is subjected to a dry desmearing treatment, and particularly preferably to a desmearing treatment using plasma.

[0051] Examples of wet desmear treatments include desmear treatments using an oxidizing agent solution. When desmear treatments are performed using an oxidizing agent solution, it is preferable to perform a swelling treatment using a swelling solution, an oxidation treatment using an oxidizing agent solution, and a neutralization treatment using a neutralizing solution in this order. Examples of swelling solutions include "Swelling Dip Securiganth P" and "Swelling Dip Securiganth SBU" manufactured by Atotech Japan Co., Ltd. The swelling treatment is preferably performed by immersing the substrate with via holes formed therein in a swelling solution heated to 60°C to 80°C for 5 to 10 minutes. The oxidizing agent solution is preferably an alkaline permanganate aqueous solution, such as a solution obtained by dissolving potassium permanganate or sodium permanganate in an aqueous sodium hydroxide solution. The oxidation treatment using an oxidizing solution is preferably carried out by immersing the substrate after swelling treatment in an oxidizing solution heated to 60°C to 80°C for 10 to 30 minutes. Commercially available alkaline permanganate aqueous solutions include "Concentrate Compact P," "Concentrate Compact CP," and "Dosing Solution Securigance P" manufactured by Atotech Japan Co., Ltd. The neutralization treatment using a neutralizing solution is preferably carried out by immersing the substrate after oxidation treatment in a neutralizing solution at 30°C to 50°C for 3 to 10 minutes. The neutralizing solution is preferably an acidic aqueous solution, and a commercially available product thereof is, for example, "Reduction Solution Securigance P" manufactured by Atotech Japan Co., Ltd.

[0052] The wet desmearing treatment may also be a wet sandblasting treatment in which an abrasive and a dispersion medium are sprayed from a nozzle to polish the treatment target. The wet sandblasting treatment can be carried out using a commercially available wet sandblasting treatment device.

[0053] In one preferred embodiment, the insulating layer is subjected to a wet desmear treatment, and particularly preferably, the insulating layer is desmeared using an oxidizing agent solution.

[0054] When the dry desmear treatment and the wet desmear treatment are performed in combination, the dry desmear treatment may be performed first, or the wet desmear treatment may be performed first.

[0055] The support of the resin sheet may be removed before step (4), or may be removed between step (X) and step (1), between step (1) and step (2), between step (2) and step (3), or after step (3). From the viewpoint of easily realizing an insulating layer with small surface roughness after desmearing, the support is preferably removed after step (2), and more preferably removed after step (3).

[0056] -Step (4)- In step (4), a conductor layer is formed on the surface of the insulating layer.

[0057] In one embodiment, the conductor layer may be formed by plating. For example, a conductor layer having a desired wiring pattern can be formed by plating the surface of the insulating layer using a conventionally known technique such as a semi-additive method or a full-additive method. From the viewpoint of ease of production, it is preferable to form the conductor layer by a semi-additive method. An example of forming the conductor layer by a semi-additive method will be described below.

[0058] First, a plating seed layer is formed on the surface of the insulating layer by electroless plating. The plating seed layer includes at least a conductive seed layer. The conductive seed layer functions as an electrode in electroplating. The conductive material constituting the conductive seed layer is not particularly limited as long as it exhibits sufficient conductivity, and suitable examples include copper, palladium, gold, platinum, silver, aluminum, and alloys thereof. The plating seed layer may also include a diffusion barrier layer. The diffusion barrier layer is a layer that prevents the conductive material constituting the conductive seed layer from diffusing into the insulating layer and causing dielectric breakdown. The material constituting the diffusion barrier layer is also not particularly limited as long as it can suppress or prevent the diffusion of the conductive material constituting the conductive seed layer, and suitable examples include titanium, tungsten, tantalum, and alloys thereof. After a conductor layer is formed on the plating seed layer in a desired pattern, unnecessary portions other than the conductor layer-forming portion are removed by etching or the like. In this case, a thinner plating seed layer makes it easier to remove the unnecessary portions of the plating seed layer and minimizes erosion of the conductor pattern when removing the unnecessary portions, which is advantageous for achieving fine wiring. The thickness of the plating seed layer is preferably 1000 nm (1 μm) or less, more preferably 800 nm or less, 600 nm or less, 500 nm or less, 400 nm or less, or 300 nm or less. Since the manufacturing method of the present invention can realize an insulating layer with excellent surface flatness, the thickness of the plating seed layer may be even thinner. For example, the thickness of the plating seed layer may be 250 nm or less, 200 nm or less, 150 nm or less, 140 nm or less, 120 nm or less, or 100 nm or less. When the plating seed layer includes a diffusion barrier layer, the "thickness of the plating seed layer" in the present invention refers to the average thickness of the entire plating seed layer, including not only the conductive seed layer but also the diffusion barrier layer. When the plating seed layer includes a diffusion barrier layer, the thickness of the diffusion barrier layer is not particularly limited as long as it can suppress or prevent diffusion of the conductive material constituting the conductive seed layer. However, from the viewpoint of contributing to fine wiring, the thickness is preferably 20 nm or less, more preferably 15 nm or less, and even more preferably 10 nm or less. The lower limit of the thickness of the diffusion barrier layer is not particularly limited, and may be, for example, 1 nm or more, 3 nm or more, or 5 nm or more.In this case, the remainder of the plating seed layer is preferably a conductive seed layer, and the thickness of the conductive seed layer may be determined in relation to the thickness of the diffusion barrier layer so that the thickness of the entire plating seed layer is within the above-mentioned preferred range.

[0059] The plating seed layer may be formed by dry plating or wet plating. Examples of dry plating include physical vapor deposition (PVD) methods such as sputtering, ion plating, and vacuum deposition, and chemical vapor deposition (CVD) methods such as thermal CVD and plasma CVD. Examples of wet plating include electroless plating. Dry plating is preferred from the viewpoint of being able to form a thin plating seed layer with a more uniform thickness, and sputtering is particularly preferred from the viewpoint of being able to realize fine wiring with excellent adhesion strength.

[0060] Next, a mask pattern is formed on the formed plating seed layer, exposing a portion of the plating seed layer corresponding to the desired wiring pattern. A metal layer is formed on the exposed plating seed layer by electrolytic plating, and the mask pattern is then removed. The conductive material used for the metal layer is not particularly limited. In a preferred embodiment, the metal layer contains one or more metals selected from the group consisting of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium. The metal layer may be a single metal layer or an alloy layer. Examples of alloy layers include layers formed from alloys of two or more metals selected from the above group (e.g., nickel-chromium alloys, copper-nickel alloys, and copper-titanium alloys).

[0061] Thereafter, unnecessary plating seed layer is removed by etching or the like, and a conductor layer having a desired wiring pattern (hereinafter also referred to as a "conductor pattern") can be formed.

[0062] According to the manufacturing method of the present invention, a conductor pattern having an L / S ratio of preferably 5 / 5 μm or less, more preferably 4 / 4 μm or less, and even more preferably 3 / 3 μm or less or 2 / 2 μm or less can be formed, and even a conductor pattern having an L / S ratio of 1 / 1 μm can be suitably formed. According to the manufacturing method of the present invention, such a conductor pattern having a small L / S ratio can be formed with a thickness of preferably 3 μm or less, 2.5 μm or less, 2 μm or less, 1.5 μm or less, or 1 μm or less. The lower limit of the thickness of the conductor pattern can be, for example, 0.5 μm or more, 0.6 μm or more, etc.

[0063] The above-mentioned step (X) and steps (1) to (4) are also collectively referred to as a rewiring formation step. By repeatedly performing the rewiring formation step, a rewiring layer with a multilayer structure can be formed. When forming a rewiring layer with a multilayer structure, it is preferable to apply the manufacturing method of the present invention when forming the rewiring layer on the semiconductor chip side (generally, the rewiring layer formed first in the chip 1st method, and the rewiring layer formed last in the rewiring 1st method), and the manufacturing method of the present invention may also be applied to all of the multilayer rewiring layers.

[0064] According to the manufacturing method of the present invention, it is possible to realize a circuit board such as WLP or PLP using a large-area base material while suppressing the occurrence of interfacial voids and an increase in the surface potential of the support.

[0065] Methods for manufacturing circuit boards such as WLP and PLP are as described above with reference to patent documents. For example, when manufacturing a WLP with a fan-in structure, a semiconductor wafer having an electrode pad surface on which circuit elements having predetermined functions and multiple electrode pads electrically connected to the circuit elements are formed is used as the "substrate," and step (X) is performed so that the electrode pad surface is bonded to the resin composition layer. Steps (1), (2), (3), and (4) are then performed in order to form a rewiring layer on the electrode pad surface of the semiconductor wafer. By repeatedly performing these steps, it is also possible to form a multilayer rewiring layer. Then, board connection terminals such as bumps are formed on the surface of the rewiring layer opposite the semiconductor wafer, and the rewiring layer is singulated to manufacture a WLP with a fan-in structure.

[0066] For example, when manufacturing a fan-out WLP, a semiconductor wafer having circuit elements with predetermined functions and multiple electrode pads electrically connected to the circuit elements is first singulated. Each semiconductor chip is then spaced apart on a carrier substrate (such as a glass substrate, metal substrate, or plastic substrate) and then resin-sealed to obtain a substrate in which the diced semiconductor chips are encapsulated with a sealing resin so that their electrode pad surfaces are exposed. Using such a substrate as a "base material," step (X) is performed so that the surface of the substrate facing the electrode pads is bonded to the resin composition layer. Steps (1), (2), (3), and (4) are then performed in sequence to form a rewiring layer on the electrode pad surfaces of the semiconductor chips and the surrounding sealing resin layer. Repeating these steps can also form multiple rewiring layers. Finally, board connection terminals such as bumps are formed on the surface of the rewiring layer opposite the substrate, and the wafer is then singulated again to manufacture a fan-out WLP.

[0067] In particular, the fan-out structure WLP or PLP obtained by the manufacturing method of the present invention is advantageous because, combined with the inherent feature of the fan-out structure that a rewiring layer can be formed over a large area, it is possible to form extremely fine and high-density wiring over a large area while providing an insulating layer that highly satisfies dielectric properties, low warpage, etc. Therefore, in one embodiment, the circuit board manufactured by the manufacturing method of the present invention is a WLP or PLP, and more preferably a fan-out structure WLP (FOWLP) or a fan-out structure PLP (FOPLP).

[0068] While circuit board manufacturing methods such as WLP and PLP have undergone a wide variety of developments, including the aforementioned chip 1st method and rewiring layer 1st method, as well as chip mounting orientation (face-down type, face-up type), the present invention relates to a highly versatile technology that can be widely applied to the manufacture of circuit boards, including the step of laminating a resin sheet onto a substrate during the manufacturing process. For example, as described above, the circuit board manufacturing method of the present invention can be applied to the formation of a sealing layer and a solder resist layer in addition to the formation of a rewiring layer.

[0069] [Resin Sheet] The resin sheet used in the manufacturing method of the present invention (hereinafter also simply referred to as "resin sheet of the present invention") will be described below.

[0070] The resin sheet of the present invention includes a support having a first surface and a second surface, and a resin composition layer provided on the second surface of the support, and satisfies the following conditions (ii-1) and (ii-2): (ii-1) the total specific surface area of ​​the inorganic filler in the resin composition layer is 1.5 m ２ / g or more (non-volatile component equivalent). (ii-2) The surface resistivity of the first surface of the support is 1.0 × 10 １０ Ω / sq. or less

[0071] <Resin Composition Layer> From the viewpoint of suppressing the occurrence of interfacial voids in combination with the above-mentioned condition (i), the resin composition layer contains an inorganic filler so as to satisfy the above-mentioned condition (ii-1).

[0072] - Inorganic filler - Regarding the condition (ii-1), the "total specific surface area of ​​the inorganic filler in the resin composition layer" means the total surface area of ​​the inorganic filler contained per 1 g of the nonvolatile components of the resin composition layer. The total specific surface area of ​​the inorganic filler in the resin composition layer is calculated by dividing the specific surface area of ​​the inorganic filler by A [m ２ / g] and the content of the inorganic filler when the non-volatile components in the resin composition layer are taken as 100% by mass is taken as B [% by mass], the specific surface area can be calculated by the formula: (A × B) / 100. Here, when a combination of multiple inorganic fillers is used, the specific surface area of ​​all the inorganic fillers contained in the resin composition layer may be taken as A, and the content of all the inorganic fillers may be taken as B in the same manner.

[0073] In order to suppress the occurrence of interfacial voids in combination with the above-mentioned condition (i), the total specific surface area of ​​the inorganic filler in the resin composition layer is 1.5 m ２ / g or more, preferably 2.0m ２ / g or more, more preferably 2.5m ２ / g or more, more preferably 3.0m ２ / g or more or 3.5m ２ / g or more. According to the production method of the present invention, which satisfies the condition (ii-1) in combination with the above-mentioned condition (i) and further satisfies the condition (ii-2), it is possible to further increase the total specific surface area of ​​the inorganic filler while suppressing an increase in the surface potential of the support. For example, when the total specific surface area of ​​the inorganic filler in the resin composition is 4.0 m ２ / g or more, 5.0m ２ / g or more, 6.0m ２ / g or more, 7.0m ２ / g or more, 8.0m ２ / g or more or 9.0m ２ / g or more. Therefore, in a preferred embodiment, the total specific surface area of ​​the inorganic filler in the resin composition layer is 4.0 m ２ In order to improve the properties of the insulating layer formed, such as lowering the dielectric loss tangent and the coefficient of thermal expansion, it is beneficial to incorporate a high content of inorganic filler, and the production method of the present invention, which can increase the total specific surface area of ​​the inorganic filler in the resin composition layer while suppressing an increase in the surface potential of the support, significantly contributes to highly satisfying each function required of the insulating layer of a circuit board.

[0074] The upper limit of the total specific surface area of ​​the inorganic filler in the resin composition layer is preferably 25 m from the viewpoint of suppressing an increase in the surface potential of the support. ２ / g or less, 20m ２ / g or less, 18m ２ / g or less, 16m ２ / g or less or 15m ２ / g or less.

[0075] Examples of inorganic filler materials 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 titanate zirconate, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate. Among these, silica is particularly preferred. Examples of silica include amorphous silica, fused silica, crystalline silica, synthetic silica, and hollow silica. Spherical silica is preferred. The inorganic filler may be used alone or in combination of two or more.

[0076] Commercially available inorganic fillers include, for example, "SP60-05" and "SP507-05" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "SC2500SQ", "SO-C4", "SO-C2", "SO-C1", "YC100C", "YA050C", "YA050C-MJE", and "YA010C" manufactured by Admatechs Co., Ltd.; "UFP-30", "DAW-03", and "FB-105FD" manufactured by Denka Co., Ltd.; "Silfil NSS-3N", "Silfil NSS-4N", and "Silfil NSS-5N" manufactured by Tokuyama Corporation; "CellSpheres" and "MGH-005" manufactured by Taiheiyo Cement Corporation; and "Sfereek" and "BA-1" manufactured by JGC Catalysts and Chemicals Co., Ltd.

[0077] The average particle size of the inorganic filler is preferably 3 μm or less, more preferably 2 μm or less, even more preferably 1 μm or less, 0.8 μm or less, 0.6 μm or less, 0.5 μm or less, 0.4 μm or less, or 0.3 μm or less, from the viewpoint of easily realizing an insulating layer with low surface roughness after desmearing. The lower limit of the average particle size is not particularly limited, but is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.07 μm or more, 0.1 μm or more, or 0.2 μm or more. The average particle size of the inorganic filler can be measured by a laser diffraction / scattering method based on Mie scattering theory. Specifically, the particle size distribution of the inorganic filler is created on a volume basis using a laser diffraction / scattering particle size distribution analyzer, and the median diameter is used as the average particle size. A 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 it ultrasonically for 10 minutes. The measurement sample was measured using a laser diffraction particle size distribution analyzer, with blue and red light source wavelengths used and a flow cell system to measure the volumetric particle size distribution of the inorganic filler, and the average particle size was calculated as the median diameter from the obtained particle size distribution. An example of a laser diffraction particle size distribution analyzer is the "LA-960" manufactured by Horiba, Ltd.

[0078] The specific surface area (A) of the inorganic filler is not particularly limited as long as it satisfies the preferred range of the "total specific surface area of ​​the inorganic filler in the resin composition layer" in relation to the content (B) of the inorganic filler in the resin composition. However, it is preferably 2 m ２ / g or more, more preferably 4m ２ / g or more, more preferably 5m ２ / g or more, 6m ２ / g or more, 8m ２ / g or more or 10m ２ The upper limit of the specific surface area is not particularly limited, but is preferably 100 m ２ / g or less, more preferably 80m ２ / g or less, more preferably 60m ２ / g or less or 50m ２The specific surface area of ​​the inorganic filler can be obtained in accordance with the BET method by adsorbing nitrogen gas onto the surface of a sample using a specific surface area measuring device (Macsorb HM-1210 manufactured by Mountech Co., Ltd.) and calculating the specific surface area using the BET multipoint method.

[0079] The inorganic filler may be a non-hollow inorganic filler (preferably non-hollow silica) with a porosity of 0% by volume, or a hollow inorganic filler (preferably hollow silica) with a porosity of more than 0% by volume, or may contain both. The inorganic filler may contain only a non-hollow inorganic filler (preferably non-hollow silica), or only a hollow inorganic filler (preferably hollow silica), or may contain a combination of a non-hollow inorganic filler (preferably non-hollow silica) and a hollow inorganic filler (preferably hollow silica). When the inorganic filler contains a hollow inorganic filler, it is preferable because it is easy to realize a resin composition that leads to a cured product with a lower dielectric constant and better dielectric properties. The porosity of the hollow inorganic filler is preferably 10% by volume or more, more preferably 15% by volume or more, and even more preferably 20% by volume or more, and its upper limit is preferably 90% by volume or less, more preferably 85% by volume or less, and even more preferably 80% by volume or less, 75% by volume or less, 70% by volume or less, 65% by volume or less, 60% by volume or less, 55% by volume or less, or 50% by volume or less. The porosity P (vol %) of the inorganic filler is defined as the volume-based ratio of the total volume of one or more voids present inside the particle to the total volume of the particle based on the outer surface of the particle (total volume of voids / volume of particle), and is, for example, a measured value D of the actual density of the inorganic filler. Ｍ (g / cm ３ ), and the theoretical value D of the material density of the material forming the inorganic filler Ｔ (g / cm ３ ) is used to calculate the value according to the following formula (1).

[0080]

[0081] The actual density of the inorganic filler can be measured using, for example, a true density measuring device. Examples of true density measuring devices include the ULTRAPYCNOMETER 1000 manufactured by QUANTACHROME Co., Ltd. Nitrogen, for example, is used as the measurement gas.

[0082] The inorganic filler is preferably surface-treated with an appropriate surface treatment agent. By performing the surface treatment, the moisture resistance and dispersibility of the inorganic filler can be improved. Examples of the surface treatment agent include silane coupling agents such as vinyl silane coupling agents, epoxy silane coupling agents, styryl silane coupling agents, (meth)acrylic silane coupling agents, amino silane coupling agents, isocyanurate silane coupling agents, ureido silane coupling agents, mercapto silane coupling agents, isocyanate silane coupling agents, and acid anhydride silane coupling agents; non-silane coupling alkoxysilane compounds such as methyltrimethoxysilane and phenyltrimethoxysilane; and silazane compounds. The surface treatment agents may be used alone or in combination of two or more.

[0083] Examples of commercially available surface treatment agents include "KBM403" (3-glycidoxypropyltrimethoxysilane), "KBM803" (3-mercaptopropyltrimethoxysilane), "KBE903" (3-aminopropyltriethoxysilane), "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane), and "SZ-31" (hexamethyldisilazane), all manufactured by Shin-Etsu Chemical Co., Ltd.

[0084] The degree of surface treatment with the surface treatment agent is preferably within a predetermined range from the viewpoint of improving the dispersibility of the inorganic filler. Specifically, 100% by mass of the inorganic filler is preferably surface-treated with 0.2 to 5% by mass of the surface treatment agent.

[0085] 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 0.02 mg / m ２ More than 0.1 mg / m 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 content be 1.0 mg / m ２Preferably, 0.8 mg / m or less ２ More preferably, 0.5 mg / m or less ２ The following is even more preferable. The carbon amount 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 carbon amount per unit surface area of ​​the inorganic filler can be measured using a carbon analyzer. As the carbon analyzer, an "EMIA-320V" manufactured by Horiba, Ltd. or the like can be used.

[0086] The content (B) of the inorganic filler in the resin composition layer is not particularly limited as long as it satisfies the preferred range of the "total specific surface area of ​​the inorganic filler in the resin composition layer" in relation to the specific surface area (A) of the inorganic filler, but from the viewpoint of realizing an insulating layer with good properties such as low dielectric tangent and low thermal expansion coefficient, when the non-volatile components in the resin composition layer are taken as 100% by mass, preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 45% by mass or more, 50% by mass or more, 55% by mass or more, 60% by mass or more, 65% by mass or more, 66% by mass or more, 68% by mass or more, 70% by mass or more, 72% by mass or more, 74% by mass or more, or 75% by mass or more. The upper limit of the content of the inorganic filler is preferably 90% by mass or less, more preferably 85% by mass or less, 84% by mass or less, 82% by mass or less, or 80% by mass or less.

[0087] -Curable Resin- In the resin sheet of the present invention, the resin composition layer contains a curable resin as a resin. The type of curable resin is not particularly limited as long as it cures to form an insulating layer. The curable resin is preferably one or more types selected from the group consisting of thermosetting resins and radically polymerizable resins, as these resins have good properties such as insulation and heat resistance.

[0088] Examples of thermosetting resins include epoxy resins, benzocyclobutene resins, epoxy acrylate resins, urethane acrylate resins, urethane resins, polyimide resins, melamine resins, and silicone resins. The thermosetting resins may be used singly or in combination of two or more. Among these, the curable resin preferably contains an epoxy resin, from the viewpoint of satisfactorily satisfying the properties required for the insulating layer of a circuit board, such as good dielectric properties and low warpage.

[0089] The type of epoxy resin is not particularly limited as long as it has one or more (preferably two or more) epoxy groups per molecule. Examples of epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol AF type epoxy resins, phenol novolac type epoxy resins, tert-butyl-catechol type epoxy resins, naphthol type epoxy resins, naphthalene type epoxy resins, naphthylene ether type epoxy resins, glycidylamine type epoxy resins, glycidyl ester type epoxy resins, cresol novolac type epoxy resins, biphenyl type epoxy resins, phenol aralkyl type epoxy resins, biphenyl aralkyl type epoxy resins, fluorene skeleton type epoxy resins, dicyclopentadiene type epoxy resins, anthracene type epoxy resins, linear aliphatic epoxy resins, epoxy resins having a butadiene structure, alicyclic epoxy resins, heterocyclic epoxy resins, spiro ring-containing epoxy resins, cyclohexanedimethanol type epoxy resins, trimethylol type epoxy resins, and halogenated epoxy resins.

[0090] Epoxy resins can be classified into epoxy resins that are liquid at a temperature of 20°C (hereinafter referred to as "liquid epoxy resins") and epoxy resins that are solid at a temperature of 20°C (hereinafter referred to as "solid epoxy resins"). In the resin sheet of the present invention, the resin composition layer may contain only a liquid epoxy resin as the curable resin, only a solid epoxy resin, or a combination of a liquid epoxy resin and a solid epoxy resin. When a combination of a liquid epoxy resin and a solid epoxy resin is contained, the blending ratio (liquid:solid) may be in the range of 20:1 to 1:20 (preferably 10:1 to 1:10, more preferably 3:1 to 1:3) by mass.

[0091] The solid epoxy resin is preferably a solid epoxy resin having three or more epoxy groups per molecule, and more preferably an aromatic solid epoxy resin having three or more epoxy groups per molecule.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, phenolphthalimidine-type epoxy resins, and phenolphthalein-type epoxy resins.

[0092] 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; and "EXA-7" manufactured by DIC Corporation. 311", "EXA-7311-G3", "EXA-7311-G4S", "HP6000", "HP6000L" (naphthylene ether type epoxy resin); "EPPN-502H" (trisphenol type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC7000L" (naphthol novolac type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC3000H", "NC3000", "NC3000L", "NC3000FH", "NC3100" (biphenyl type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "ESN475V" (naphthylene ether type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd. phthalene-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", and "YL7890" (bixylenol-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL6121" (biphenyl-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX8800" (anthracene-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX770" manufactured by Mitsubishi Chemical Corporation 0" (phenol aralkyl type epoxy resin); "PG-100" and "CG-500" manufactured by Osaka Gas Chemicals Co., Ltd.; "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.

[0093] The liquid epoxy resin is preferably a liquid epoxy resin having two or more epoxy groups per molecule, such as bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol AF epoxy resin, hydrogenated bisphenol A epoxy resin, naphthalene epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, phenol novolac epoxy resin, alicyclic epoxy resin having an ester skeleton, cyclohexane epoxy resin, cyclohexanedimethanol epoxy resin, and epoxy resin having a butadiene structure.

[0094] Specific examples of liquid epoxy resins include "HP4032", "HP4032D", and "HP4032SS" (naphthalene type epoxy resins) manufactured by DIC Corporation; "828US", "828EL", "jER828EL", and "825" (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" (glycilol type epoxy resin) manufactured by ADEKA Corporation; "EP-3950L" and "EP-3980S" (glycidylamine type epoxy resins) manufactured by ADEKA Corporation; and "EP-4088S" (glycidylamine type epoxy resin) manufactured by ADEKA Corporation. Examples of epoxy resins include "ZX1059" manufactured by Nippon Steel Chemical & Material Co., Ltd. (a mixture of bisphenol A epoxy resin and bisphenol F epoxy resin); "EX-721" manufactured by Nagase ChemteX Corporation (a glycidyl ester epoxy resin); "Celloxide 2021P" manufactured by Daicel Corporation (an alicyclic epoxy resin having an ester skeleton); "PB-3600" manufactured by Daicel Corporation, "JP-100" and "JP-200" manufactured by Nippon Soda Co., Ltd. (epoxy resins having a butadiene structure); "ZX1658" and "ZX1658GS" manufactured by Nippon Steel Chemical & Material Co., Ltd. (1,4-glycidylcyclohexane epoxy resin); "YX8000" manufactured by Mitsubishi Chemical Corporation (a hydrogenated bisphenol A epoxy resin); and "KF-101" manufactured by Shin-Etsu Chemical Co., Ltd. (an epoxy-modified silicone resin). These may be used alone or in combination of two or more.

[0095] The epoxy group equivalent of the epoxy resin is preferably 50 g / eq. to 2000 g / eq., more preferably 60 g / eq. to 1000 g / eq., and even more preferably 80 g / eq. to 500 g / eq. The epoxy group equivalent is the mass of the epoxy resin containing one equivalent of epoxy groups, and can be measured in accordance with JIS K7236.

[0096] The weight average molecular weight (Mw) of the epoxy resin is preferably 100 to 5,000, more preferably 250 to 3,000, and even more preferably 400 to 1,500. The Mw of the epoxy resin can be measured by the GPC method as a polystyrene-equivalent value.

[0097] The type of radical polymerizable resin is not particularly limited as long as it has one or more (preferably two or more) radical polymerizable unsaturated groups in one molecule. Examples of radical polymerizable resins include resins having one or more radical polymerizable unsaturated groups selected from maleimide groups, vinyl groups, allyl groups, styryl groups, vinylphenyl groups, acryloyl groups, methacryloyl groups, fumaroyl groups, and maleoyl groups. Among these, from the viewpoint of satisfactorily satisfying the properties required for the insulating layer of a circuit board, such as good dielectric properties and low warpage, it is preferable that the curable resin contains one or more selected from maleimide resins, (meth)acrylic resins, and styryl resins.

[0098] The type of maleimide resin is not particularly limited as long as it has one or more (preferably two or more) maleimide groups (2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl groups) in one molecule. Examples of maleimide resins include: (1) maleimide resins containing an aliphatic skeleton having 36 carbon atoms derived from dimer diamine, such as "BMI-3000J," "BMI-5000," "BMI-1400," "BMI-1500," "BMI-1700," and "BMI-689" (all manufactured by DigiCner Molecules); (2) maleimide resins containing an indane skeleton, as described in the Japan Institute of Invention and Innovation Disclosure Technical Bulletin No. 2020-500211 (commercially available products include "MIR-5000-60T" (manufactured by Nippon Kayaku Co., Ltd.)); and (3) maleimide resins containing an aromatic ring skeleton directly bonded to the nitrogen atom of the maleimide group, such as "MIR-3000-70MT" (manufactured by Nippon Kayaku Co., Ltd.), "BMI-4000" (manufactured by Daiwa Kasei Co., Ltd.), and "BMI-80" (manufactured by Keiai Kasei Co., Ltd.).

[0099] The (meth)acrylic resin may be of any type, and may be a monomer or oligomer, as long as it has one or more (preferably two or more) (meth)acryloyl groups in one molecule. Here, the term "(meth)acryloyl group" is a general term for acryloyl groups and methacryloyl groups. Examples of methacrylic resins include (meth)acrylate monomers, as well as (meth)acrylic resins such as "A-DOG" (manufactured by Shin-Nakamura Chemical Co., Ltd.), "DCP-A" (manufactured by Kyoeisha Chemical Co., Ltd.), "NPDGA," "FM-400," "R-687," "THE-330," "PET-30," and "DPHA" (all manufactured by Nippon Kayaku Co., Ltd.).

[0100] The styryl resin is not particularly limited in type, and may be a monomer or oligomer, as long as it has one or more (preferably two or more) styryl groups or vinylphenyl groups in one molecule. Examples of the styryl resin include styrene monomers and styryl resins such as "OPE-2St," "OPE-2St 1200," and "OPE-2St 2200" (all manufactured by Mitsubishi Gas Chemical Company, Inc.).

[0101] In the resin sheet of the present invention, the resin composition layer may contain, as the curable resin, only a thermosetting resin, only a radically polymerizable resin, or a combination of a thermosetting resin and a radically polymerizable resin.

[0102] The content of the curable resin in the resin composition layer is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 12% by mass or more, 14% by mass or more, or 15% by mass or more, when the resin component in the resin composition layer is 100% by mass. The upper limit of the content is not particularly limited and may be determined depending on the properties required of the resin composition, but may be, for example, 80% by mass or less, 70% by mass or less, 60% by mass or less, or 50% by mass or less.

[0103] In the present invention, the term "resin component" refers to the non-volatile components constituting the resin composition layer, excluding the inorganic filler described below.

[0104] In the resin composition layer, when the non-volatile components of the curable resin are taken as 100% by mass, the content of the epoxy resin is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 55% by mass or more, 60% by mass or more, 65% by mass or more, or 70% by mass or more. The upper limit of the content of the epoxy resin in the curable resin is not particularly limited and may be 100% by mass, but may also be, for example, 95% by mass or less, 90% by mass or less, etc.

[0105] - Curing Agent - In the resin sheet of the present invention, the resin composition layer may contain a curing agent. The curing agent usually has the function of reacting with the curable resin to cure the resin composition.

[0106] Examples of the curing agent include active ester curing agents, phenol curing agents, naphthol curing agents, acid anhydride curing agents, cyanate ester curing agents, carbodiimide curing agents, amine curing agents, etc. The curing agents may be used alone or in combination of two or more.

[0107] In particular, from the viewpoint of providing a cured product (insulating layer) having excellent dielectric properties and conductor adhesion, it is preferable that the curing agent contains one or more selected from the group consisting of active ester-based curing agents, phenol-based curing agents, and naphthol-based curing agents, and it is particularly preferable that the curing agent contains an active ester-based curing agent from the viewpoint of providing a cured product having excellent dielectric properties. Thus, in one embodiment, the curing agent contains one or more selected from the group consisting of active ester-based curing agents, phenol-based curing agents, and naphthol-based curing agents, and more preferably contains an active ester-based curing agent.

[0108] As the active ester curing agent, a compound having one or more active ester groups per molecule can be used. Among them, as the active ester curing agent, a compound having two or more highly reactive ester groups per molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds, is preferred. The active ester curing agent is preferably one 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 curing agent obtained from a carboxylic acid compound and a hydroxy compound is preferred, and an active ester curing agent obtained from a carboxylic acid compound and a phenol compound and / or a naphthol compound is more preferred.

[0109] 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.

[0110] Examples of phenol compounds or naphthol compounds include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalene, 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 novolak, etc. Here, "dicyclopentadiene-type diphenol compounds" refers to diphenol compounds obtained by condensing one dicyclopentadiene molecule with two phenol molecules.

[0111] Specific preferred examples of the active ester curing agent include active ester curing agents containing a dicyclopentadiene-type diphenol structure, active ester curing agents containing a naphthalene structure, active ester curing agents containing an acetylated product of phenol novolac, and active ester curing agents containing a benzoylated product of phenol novolac. Among these, active ester curing agents containing a naphthalene structure and active ester curing agents containing a dicyclopentadiene-type diphenol structure are more preferred. The "dicyclopentadiene-type diphenol structure" refers to a divalent structural unit consisting of phenylene-dicyclopentylene-phenylene.

[0112] Commercially available active ester compounds include active ester compounds containing a dicyclopentadiene-type diphenol structure, such as "EXB9451," "EXB9460," "EXB9460S," "HPC-8000L-65TM," "HPC-8000-65T," and "HPC-8000H-65TM" (manufactured by DIC Corporation); active ester compounds containing a naphthalene structure, such as "EXB-8100L-65T," "EXB-9416-70BK," and "HPC-8150-62T" (manufactured by DIC Corporation); and phosphorus Examples of the active ester compound include "EXB9401" (manufactured by DIC Corporation), "DC808" (manufactured by Mitsubishi Chemical Corporation) as an active ester compound which is an acetylated product of phenol novolac, "YLH1026", "YLH1030", and "YLH1048" (manufactured by Mitsubishi Chemical Corporation) as active ester compounds which are benzoylated products of phenol novolac, and "PC1300-02-65MA" (manufactured by Air Water Inc.) as an active ester compound containing a styryl group and a naphthalene structure.

[0113] As the phenol-based curing agent and naphthol-based curing agent, those having a novolac structure are preferred from the viewpoint of heat resistance and water resistance. Furthermore, from the viewpoint of adhesion to the conductor layer, nitrogen-containing phenol-based curing agents and nitrogen-containing naphthol-based curing agents are preferred, and triazine skeleton-containing phenol-based curing agents and triazine skeleton-containing naphthol-based curing agents are more preferred.

[0114] Specific examples of phenol-based curing agents and naphthol-based curing agents include, for example, "MEH-7700", "MEH-7810", "MEH-7851", and "MEH-8000H" manufactured by Meiwa Chemical Industry Co., Ltd.; "NHN", "CBN", and "GPH" manufactured by Nippon Kayaku Co., Ltd.; and "SN-170", "SN-180", "SN-190", "SN-475", "SN-485", "SN-495", and "SN- 495V", "SN-375", and "SN-395" manufactured by DIC Corporation; "TD-2090", "LA-7052", "LA-7054", "LA-1356", "LA-3018-50P", "EXB-9500", "HPC-9500", "KA-1160", "KA-1163", and "KA-1165" manufactured by Gun-ei Chemical Co., Ltd.; and "GDP-6115L", "GDP-6115H", and "ELPC75" manufactured by Gun-ei Chemical Co., Ltd.

[0115] Examples of acid anhydride curing agents include curing agents having one or more acid anhydride groups in one molecule. Specific examples of acid anhydride curing agents 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, and benzophenonetetracarboxylic dianhydride. Examples of suitable acid anhydrides include polymeric acid anhydrides such as styrene-maleic acid resins obtained by copolymerizing styrene and maleic acid, ethylene glycol bis(anhydrotrimellitate), styrene anhydride, bis(trimethylsilyl)propanol ...

[0116] Examples of cyanate ester curing agents 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 triazine converted. Specific examples of cyanate ester curing agents include "PT30" and "PT60" (phenol novolac type multifunctional cyanate ester resins), "ULL-950S" (multifunctional cyanate ester resin), "BA230" and "BA230S75" (prepolymers in which part or all of bisphenol A dicyanate has been triazinated to form a trimer), all of which are manufactured by Lonza Japan Co., Ltd.

[0117] Specific examples of carbodiimide curing agents include Carbodilite (registered trademark) V-03 (carbodiimide group equivalent: 216 g / eq.), V-05 (carbodiimide group equivalent: 262 g / eq.), and V-07 (carbodiimide group equivalent: 200 g / eq.), all manufactured by Nisshinbo Chemical Inc.; and V-09 (carbodiimide group equivalent: 200 g / eq.); and Stavaxol (registered trademark) P (carbodiimide group equivalent: 302 g / eq.) manufactured by Rhein Chemie AG.

[0118] Examples of the amine-based curing agent include curing agents having one or more amino groups in one molecule, such as aliphatic amines, polyether amines, alicyclic amines, and aromatic amines. Specific examples of the amine-based curing agent include 4,4'-methylenebis(2,6-dimethylaniline), diphenyldiaminosulfone, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, m-phenylenediamine, m-xylylenediamine, diethyltoluenediamine, 4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, and 2,2-bis(3-amino-4-hydroxybenzoyl)methylpropional. bis(4-aminophenoxy)biphenyl)propane, 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-based curing agents may be used, and examples thereof include "KAYABOND C-200S," "KAYABOND C-100," "KAYAHARD A-A," "KAYAHARD A-B," and "KAYAHARD A-S" manufactured by Nippon Kayaku Co., Ltd., and "Epicure W" manufactured by Mitsubishi Chemical Corporation.

[0119] From the viewpoint of being able to produce a cured product having excellent dielectric properties and conductor adhesion, the content of the curing agent in the resin composition is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, 20% by mass or more, 25% by mass or more, or 30% by mass or more, based on 100% by mass of the resin component in the resin composition. The upper limit of the content is not particularly limited and may be determined depending on the properties required of the resin composition, but may be, for example, 70% by mass or less, 60% by mass or less, or 55% by mass or less.

[0120] As described above, from the viewpoint of obtaining a cured product with excellent dielectric properties, the curing agent preferably contains an active ester-based curing agent. When the resin composition layer contains an active ester-based curing agent as the curing agent, the content of the active ester-based curing agent in the curing agent is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, 75% by mass or more, or 80% by mass or more, when the non-volatile components of the curing agent are taken as 100% by mass, from the viewpoint of obtaining a cured product with particularly excellent dielectric properties. The upper limit of the content of the active ester-based curing agent in the curing agent is not particularly limited, and may be 100% by mass, but may also be, for example, 95% by mass or less, 90% by mass or less, etc.

[0121] When the resin composition layer contains an active ester curing agent as a curing agent, the mass ratio of the active ester curing agent to the curable resin (active ester curing agent / curable resin) is preferably 0.5 or more, more preferably 0.6 or more, and even more preferably 0.7 or more or 0.8 or more, from the viewpoint of exhibiting particularly excellent dielectric properties. The upper limit of the mass ratio (active ester curing agent / curable resin) may be, for example, 2 or less, 1.8 or less, 1.6 or less, or 1.5 or less.

[0122] In a preferred embodiment, the resin composition layer contains an inorganic filler, a curable resin, and a curing agent, and satisfies the above-mentioned condition (ii-1). The resin composition layer may further contain one or more materials selected from the group consisting of a stress relaxation material and a curing accelerator, as long as the above-mentioned condition (ii-1) is satisfied and the effects of the present invention are not impaired.

[0123] - Stress Relief Material - The resin composition layer may further contain a stress relief material. By including a stress relief material, warping can be suppressed even when an insulating layer is formed on a substrate with a large area.

[0124] The stress relaxation material is preferably a resin having one or more structures selected from a polybutadiene structure, a polysiloxane structure, a poly(meth)acrylate structure, a polyalkylene structure, a polyalkyleneoxy structure, a polyisoprene structure, a polyisobutylene structure, and a polycarbonate structure in its molecule, and more preferably a resin having one or more structures selected from a polybutadiene structure, a poly(meth)acrylate structure, a polyalkyleneoxy structure, a polyisoprene structure, a polyisobutylene structure, and a polycarbonate structure. The term "(meth)acrylate" encompasses both methacrylate and acrylate. These structures may be contained in the main chain or in the side chain.

[0125] The stress relaxation material preferably has a high molecular weight from the viewpoint of suppressing warpage. The number average molecular weight (Mn) of the stress relaxation material is preferably 1,000 or more, more preferably 1,500 or more, and even more preferably 2,000 or more, 2,500 or more, 3,000 or more, 4,000 or more, or 5,000 or more. The upper limit of Mn is preferably 1,000,000 or less, more preferably 900,000 or less, 800,000 or less, or 700,000 or less. The number average molecular weight (Mn) can be measured as a polystyrene-equivalent value by gel permeation chromatography (GPC).

[0126] From the viewpoint of suppressing warpage, the stress relaxation material is preferably one or more types selected from resins having a glass transition temperature (Tg) of 25° C. or less and resins that are liquid at 25° C. Here, for resins with multiple observed Tg values, if the lowest Tg is 25° C. or less, the resin falls under the category of "resin having a Tg of 25° C. or less."

[0127] For resins having a Tg of 25° C. or less, the Tg is preferably 20° C. or less, more preferably 15° C. or less. The lower limit of the Tg is not particularly limited, but it can usually be −50° C. or more. Furthermore, for resins that are liquid at 25° C., they are preferably liquid at 20° C. or less, more preferably liquid at 15° C. or less.

[0128] From the viewpoint of realizing an insulating layer with high cohesive force (interlayer adhesion strength) by reacting with the curable resin, etc., the stress relaxation material preferably has a functional group that can react with the curable resin, etc. The functional group that can react with the curable resin, etc. also includes a functional group that appears upon heating.

[0129] In one embodiment, the functional group reactive with the curable resin or the like is one or more functional groups selected from the group consisting of a hydroxy group, a carboxy group, an acid anhydride group, a phenolic hydroxyl group, an epoxy group, an isocyanate group, and a urethane group. Among these, the functional group is preferably a hydroxy group, an acid anhydride group, a phenolic hydroxyl group, an epoxy group, an isocyanate group, or a urethane group, and more preferably a hydroxy group, an acid anhydride group, a phenolic hydroxyl group, or an epoxy group. However, when an epoxy group is contained as a functional group, the number average molecular weight (Mn) is preferably 5,000 or more.

[0130] In one embodiment, the stress relaxation material includes a resin containing a polybutadiene structure (hereinafter also referred to as a "polybutadiene resin"), and the polybutadiene structure may be partially or entirely hydrogenated.

[0131] Specific examples of polybutadiene resins include "Ricon 130MA8", "Ricon 130MA13", "Ricon 130MA20", "Ricon 131MA5", "Ricon 131MA10", "Ricon 131MA17", "Ricon 131MA20", and "Ricon 184MA6" (acid anhydride group-containing polybutadienes) manufactured by Cray Valley Corporation; "JP-100", "JP-200" (epoxidized polybutadiene), "GQ-1000" (hydroxyl group- and carboxyl group-introduced polybutadiene), "G-1000", "G-2000", and "G-3000" (polybutadiene with hydroxyl groups at both ends), "GI-1000", "GI-2000", and "GI-3000" (hydrogenated polybutadiene with hydroxyl groups at both ends) manufactured by Nippon Soda Co., Ltd.; and Daicel Chemical Industries, Ltd. Examples of suitable polybutadiene resins include "PB3600" and "PB4700" (polybutadiene-skeleton epoxy resins), "Epofriend A1005," "Epofriend A1010," and "Epofriend A1020" (epoxidized styrene, butadiene, and styrene block copolymers) manufactured by Nagase ChemteX Corporation, and "FCA-061L" (hydrogenated polybutadiene-skeleton epoxy resin) and "R-45EPT" (polybutadiene-skeleton epoxy resin) manufactured by Nagase ChemteX Corporation. Examples of suitable polybutadiene resins include hydroxyl-terminated polybutadiene, linear polymers derived from diisocyanate compounds and tetrabasic acid anhydrides (polymers described in JP 2006-37083 A and WO 2008 / 153208 A), and phenolic hydroxyl group-containing butadienes. The content of the butadiene structure in the polymer is preferably 50% by mass or more, and more preferably 60% to 95% by mass. For details of the polymer, please refer to the descriptions in JP-A-2006-37083 and WO 2008 / 153208, the contents of which are incorporated herein by reference.

[0132] In one embodiment, the stress relaxation material includes a resin containing a poly(meth)acrylate structure (hereinafter also referred to as "poly(meth)acrylic resin"). Specific examples of poly(meth)acrylic resins include Teisan Resin "SG-70L", "SG-708-6", "WS-023", "SG-700AS", and "SG-280TEA" (carboxy group-containing acrylic ester copolymer resin, acid value 5 to 34 mgKOH / g, weight average molecular weight 400,000 to 900,000, Tg -30 to 5°C), "SG-80H", "SG-80H-3", and "SG-P3" (epoxy group-containing acrylic ester copolymer resin, epoxy equivalent 4761 to 14285 g / eq, weight average molecular weight 350,000) manufactured by Nagase ChemteX Corporation. to 850,000, Tg 11 to 12°C), "SG-600TEA", "SG-790" (hydroxy group-containing acrylic ester copolymer resin, hydroxyl value 20 to 40 mgKOH / g, weight average molecular weight 500,000 to 1,200,000, Tg -37 to -32°C), "ME-2000", "W-116.3" (carboxy group-containing acrylic ester copolymer resin), "W-197C" (hydroxy group-containing acrylic ester copolymer resin), "KG-25", "KG-3000" (epoxy group-containing acrylic ester copolymer resin) manufactured by Negami Chemical Industrial Co., Ltd.

[0133] In one embodiment, the stress relief material includes a resin containing a polycarbonate structure (hereinafter also referred to as "polycarbonate resin"). Specific examples of polycarbonate resins include "T6002" and "T6001" (polycarbonate diols) manufactured by Asahi Kasei Chemicals Corporation, and "C-1090," "C-2090," and "C-3090" (polycarbonate diols) manufactured by Kuraray Co., Ltd. Linear polyimides made from hydroxyl-terminated polycarbonate, diisocyanate compounds, and tetrabasic acid anhydrides can also be used. The carbonate structure content of the polyimide resin is preferably 50% by mass or more, more preferably 60% to 95% by mass. For details of the polyimide resin, please refer to the description in International Publication No. WO 2016 / 129541, the contents of which are incorporated herein by reference.

[0134] In one embodiment, the stress relief material includes a resin containing a polysiloxane structure (hereinafter also referred to as "polysiloxane resin"). Specific examples of polysiloxane resins include "SMP-2006," "SMP-2003PGMEA," and "SMP-5005PGMEA" manufactured by Shin-Etsu Silicones Co., Ltd., and linear polyimides made from amine-terminated polysiloxanes and tetrabasic acid anhydrides (see, for example, International Publication No. 2010 / 053185, Japanese Patent Application Laid-Open No. 2002-12667, and Japanese Patent Application Laid-Open No. 2000-319386).

[0135] In one embodiment, the stress relaxation material includes a resin containing a polyalkylene structure or a polyalkyleneoxy structure (hereinafter also referred to as a "polyalkylene resin" and a "polyalkyleneoxy resin", respectively). Specific examples of polyalkylene resins and polyalkyleneoxy resins include "PTXG-1000" and "PTXG-1800" manufactured by Asahi Kasei Fibers Corporation.

[0136] In one embodiment, the stress relief material includes a resin containing a polyisoprene structure (hereinafter also referred to as "polyisoprene resin"). Specific examples of polyisoprene resin include "KL-610" and "KL613" manufactured by Kuraray Co., Ltd.

[0137] In one embodiment, the stress relief material includes a resin containing a polyisobutylene structure (hereinafter also referred to as "polyisobutylene resin"). Specific examples of polyisobutylene resins include "SIBSTAR-073T" (styrene-isobutylene-styrene triblock copolymer) and "SIBSTAR-042D" (styrene-isobutylene diblock copolymer), both manufactured by Kaneka Corporation.

[0138] In another preferred embodiment, the stress relief material includes an organic filler. A wide variety of organic fillers containing a rubber component can be used as the organic filler. Examples of the rubber component contained in the organic filler include silicone-based elastomers such as polydimethylsiloxane; olefin-based thermoplastic elastomers such as polybutadiene, polyisoprene, polychlorobutadiene, ethylene-vinyl acetate copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-isobutylene copolymer, acrylonitrile-butadiene copolymer, isoprene-isobutylene copolymer, isobutylene-butadiene copolymer, ethylene-propylene-diene terpolymer, and ethylene-propylene-butene terpolymer; and thermoplastic elastomers such as acrylic thermoplastic elastomers such as polypropyl(meth)acrylate, polybutyl(meth)acrylate, polycyclohexyl(meth)acrylate, and polyoctyl(meth)acrylate. Furthermore, silicone-based rubbers such as polyorganosiloxane rubber may be mixed into the rubber component. The rubber component contained in the rubber particles has a Tg of, for example, 0° C. or less, preferably −10° C. or less, more preferably −20° C. or less, and even more preferably −30° C. or less.

[0139] In one embodiment, the organic filler is a core-shell rubber particle comprising a core particle containing the above-mentioned rubber component and a shell portion obtained by graft copolymerization of a monomer component copolymerizable with the rubber component contained in the core particle. Here, the term "core-shell" does not necessarily refer only to those in which the core particle and the shell portion are clearly distinguishable, but also includes those in which the boundary between the core particle and the shell portion is unclear, and the core particle does not necessarily have to be completely covered with the shell portion.

[0140] Specific examples of organic fillers containing a rubber component include "CHT" manufactured by Cheil Industries; "B602" manufactured by UMGABS; "Paraloid EXL-2602," "Paraloid EXL-2603," "Paraloid EXL-2655," "Paraloid EXL-2311," "Paraloid EXL2313," "Paraloid EXL-2315," "Paraloid KM-330," "Paraloid KM-336P," and "Paraloid KCZ-201" manufactured by Kureha Chemical Industry Co., Ltd.; and "Metabrene C" manufactured by Mitsubishi Rayon Co., Ltd. -223A," "Metablen E-901," "Metablen S-2001," "Metablen W-450A," "Metablen SRK-200," "Kane Ace M-511," "Kane Ace M-600," "Kane Ace M-400," "Kane Ace M-580," and "Kane Ace MR-01" manufactured by Kaneka Corporation, and "Staphyloid AC3355," "Staphyloid AC3816," "Staphyloid AC3832," "Staphyloid AC4030," and "Staphyloid AC3364" manufactured by Aica Kogyo Co., Ltd. These are core-shell type rubber particles.

[0141] When the resin composition layer contains a stress relaxation material, the content of the stress relaxation material in the resin composition layer is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, and even more preferably 4% by mass or more or 5% by mass or more, based on 100% by mass of the resin component in the resin composition, from the viewpoint of realizing an insulating material that can suppress warping. In this regard, while increasing the content of the stress relaxation material in the resin composition layer can suppress warping, the present inventors have found that in a circuit board manufacturing method that satisfies condition (ii-1) in combination with condition (i) and aims to suppress the occurrence of interfacial voids, the surface potential of the support tends to increase significantly to the extent that damage to the semiconductor chip is a concern. In contrast, according to the manufacturing method of the present invention that satisfies condition (ii-1) in combination with condition (i) and further satisfies condition (ii-2), the content of the stress relaxation material can be further increased while suppressing the increase in the surface potential of the support. For example, the content of the stress relaxation material in the resin composition layer may be increased to 6% by mass or more, 8% by mass or more, 10% by mass or more, 12% by mass or more, 14% by mass or more, or 15% by mass or more, when the resin component in the resin composition is taken as 100% by mass. The upper limit of the content is preferably 40% by mass or less, more preferably 35% by mass or less or 30% by mass or less.

[0142] The content of the stress relaxation material in the resin composition layer is also expressed as the mass ratio of the stress relaxation material to the total of the curable resin and the curing agent, i.e., stress relaxation material / [curable resin + curing agent], of preferably 0.05 or more, more preferably 0.06 or more, 0.08 or more, or 0.1 or more. The upper limit of this mass ratio is preferably 3 or less, more preferably 2 or less, 1.8 or less, 1.6 or less, or 1.5 or less.

[0143] -Curing Accelerator- The resin composition layer may further contain a curing accelerator. By including a curing accelerator, the curing time and curing temperature can be efficiently adjusted.

[0144] Examples of the curing accelerator include organic phosphine compounds such as "TPP", "TPP-K", "TPP-S", and "TPTP-S" (manufactured by Hokko Chemical Industry Co., Ltd.); imidazole compounds such as "Curesol 2MZ", "2E4MZ", "Cl1Z", "Cl1Z-CN", "Cl1Z-CNS", "Cl1Z-A", "2MZ-OK", "2MA-OK", and "2PHZ" (manufactured by Shikoku Chemical Industry Co., Ltd.); amine adduct compounds such as Novacure (manufactured by Asahi Chemical Industry Co., Ltd.) and Fujicure (manufactured by Fuji Chemical Industry Co., Ltd.); amine compounds such as 1,8-diazabicyclo[5,4,0]undecene-7,4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, and 4-dimethylaminopyridine; and organometallic complexes or organometallic salts of cobalt, copper, zinc, iron, nickel, manganese, tin, and the like.

[0145] When the resin composition layer contains a curing accelerator, the content of the curing accelerator in the resin composition may be determined according to the properties required of the resin composition, but when the resin component in the resin composition is taken as 100% by mass, it is preferably 3% by mass or less, more preferably 2% by mass or less, and even more preferably 1% by mass or less, and the lower limit may be 0.001% by mass or more, 0.01% by mass or more, 0.05% by mass or more, etc.

[0146] Other Additives In the resin sheet of the present invention, the resin composition layer may further contain other additives. Examples of such additives include radical polymerization initiators such as peroxide-based radical polymerization initiators and azo-based radical polymerization initiators; thermoplastic resins such as phenoxy resins, polyvinyl acetal resins, polysulfone resins, polyethersulfone resins, polyphenylene ether resins, polyetheretherketone resins, and polyester resins; organometallic compounds such as organic copper compounds, organic zinc compounds, and organic cobalt 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; antifoaming agents such as silicone-based antifoaming agents, acrylic-based antifoaming agents, fluorine-based antifoaming agents, and vinyl resin-based antifoaming agents; and benzotriazole-based ultraviolet surfactants such as fluorine-based surfactants and silicone-based surfactants; flame retardants such as phosphorus-based flame retardants (e.g., phosphate ester compounds, phosphazene compounds, phosphinic acid compounds, red phosphorus), nitrogen-based flame retardants (e.g., melamine sulfate), halogen-based flame retardants, and inorganic flame retardants (e.g., antimony trioxide); dispersants such as phosphate ester-based dispersants, polyoxyalkylene-based dispersants, acetylene-based dispersants, silicone-based dispersants, anionic dispersants, and cationic dispersants; and stabilizers such as borate-based stabilizers, titanate-based stabilizers, aluminate-based stabilizers, zirconate-based stabilizers, isocyanate-based stabilizers, carboxylic acid-based stabilizers, and carboxylic acid anhydride-based stabilizers. The content of such additives may be determined depending on the properties required for the resin composition layer.

[0147] In the resin sheet of the present invention, the thickness of the resin composition layer may be determined depending on the intended design of the circuit board, but is preferably 50 μm or less, more preferably 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, or 20 μm or less. The lower limit of the thickness of the resin composition layer is not particularly limited, but can usually be 1 μm or more, 2 μm or more, 3 μm or more, 5 μm or more, etc.

[0148] From the viewpoint of ease of handling when laminating to a substrate, the melt viscosity of the resin composition layer at 100°C is preferably 50,000 poise or less, more preferably 45,000 poise or less, even more preferably 40,000 poise or less, 35,000 poise or less, or 30,000 poise or less. As mentioned above, from the viewpoint of suppressing warpage, it is preferable that the resin composition layer contains a stress relaxation material. In this regard, the present inventors have found that when the melt viscosity of the resin composition layer in the lamination temperature range is reduced, for example, when the content of the stress relaxation material in the resin composition layer is increased, in a manufacturing method of a circuit board that satisfies the condition (ii-1) in combination with the above-mentioned condition (i) and aims to suppress the occurrence of interfacial voids, the increase in the surface potential of the support tends to be so significant that damage to the semiconductor chip is a concern. In contrast, according to the manufacturing method of the present invention, which satisfies condition (ii-1) in combination with condition (i) and further satisfies condition (ii-2), it is possible to suppress an increase in the surface potential of the support even if the melt viscosity of the resin composition layer is further reduced by, for example, increasing the content of the stress relaxation material. For example, the melt viscosity of the resin composition layer at 100°C may be 25,000 poise or less, 20,000 poise or less, 18,000 poise or less, 16,000 poise or less, 15,000 poise or less, 14,000 poise or less, 12,000 poise or less, or 10,000 poise or less. From the viewpoint of further suppressing the occurrence of interfacial voids, the melt viscosity of the resin composition layer at 100°C is preferably 1,000 poise or more, 1,500 poise or more, or 2,000 poise or more. In the present invention, the melt viscosity at 100° C. of the resin composition layer can be measured according to the method described in the section <Measurement of Melt Viscosity> below.

[0149] <Support> In the resin sheet of the present invention, the support has first and second surfaces, and the surface resistivity of the first surface is 1.0 × 10 １０ Ω / sq. or less (the above "condition (ii-2)").

[0150] In the present invention, the first surface of the support refers to an exposed surface that is not in contact with the resin composition layer, and the second surface of the support refers to a surface that is in contact with the resin composition layer.

[0151] As described above, the inventors have discovered that by using a resin sheet having a resin composition layer that satisfies condition (ii-1) and performing step (X) so as to satisfy condition (i), the occurrence of interfacial voids can be suppressed even when a large-area substrate is used. On the other hand, they have discovered that a new problem arises, particularly when the substrate has a large area: the surface potential of the support increases to a level that raises concerns about damage to the semiconductor chip. Furthermore, as described above, the problem of increased surface potential tends to become more pronounced in resin composition layer compositions that aim for even lower dielectric tangent and reduced warpage. By satisfying condition (ii-2) in combination with conditions (i) and (ii-1), the inventors have made it possible to suppress the occurrence of interfacial voids and to suppress an increase in the surface potential of the support, even when an insulating material in the form of a resin sheet is applied to a large-area substrate.

[0152] In the manufacture of a circuit board, from the viewpoint of suppressing an increase in the surface potential of the support, the surface resistivity of the first surface of the support is 1.0×10 １０ Ω / sq. or less, preferably 1.0×10 ９ Ω / sq. or less, more preferably 1.0×10 ８ Ω / sq. or less, more preferably 5.0×10 ７ Ω / sq. Below, 1.0×10 ７ Ω / sq. Below, 5.0×10 ６ Ω / sq. Below, 1.0×10 ６ Ω / sq. or less or 5.0 x 10 ５ The lower limit of the surface resistivity is not particularly limited, but is usually 1.0 × 10 １ Ω / sq. Above, 5.0×10１ Ω / sq. Above, 1.0×10 ２ In the present invention, the surface resistivity of the surface of the support can be measured according to the method described in the section <Measurement of Surface Resistivity> below.

[0153] The surface resistivity of the second surface of the support is not particularly limited, and may be, for example, 1.0×10 １５ Ω / sq. Below, 1.0×10 １４ Ω / sq. Below, 5.0×10 １３ Ω / sq. or less, but from the viewpoint of further suppressing the increase in the surface potential of the support, it is preferably 1.0×10 １２ Ω / sq. or less, more preferably 1.0×10 １１ Ω / sq. or less, more preferably 1.0×10 １０ Ω / sq. Below, 1.0×10 ９ Ω / sq. Below, 1.0×10 ８ Ω / sq. or less or 5.0 x 10 ７ The lower limit of the surface resistivity is not particularly limited, but is usually 1.0 × 10 １ Ω / sq. Above, 5.0×10 １ Ω / sq. Above, 1.0×10 ２ Ω / sq. or more.

[0154] The material and configuration of the support are not particularly limited as long as it satisfies the above condition (ii-2). Examples of the support include thermoplastic resin films, metal foils, and release papers, and thermoplastic resin films are preferred.

[0155] When a thermoplastic resin film is used as the support, examples of the thermoplastic resin include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), acrylics such as polycarbonate (PC) and polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, polyimide, etc. Among these, polyethylene terephthalate and polyethylene naphthalate are preferred.

[0156] The surface of the support that is bonded to the resin composition layer (the "second surface") may be subjected to a matte treatment, a corona treatment, or an antistatic treatment. A support having a release layer on the second surface may also be used as the support. Examples of the release agent used in the release layer of the support with a release layer include one or more release agents selected from the group consisting of alkyd resins, polyolefin resins, urethane resins, and silicone resins.

[0157] As described above, in the resin sheet of the present invention, the support is characterized in that the surface resistivity of the first surface thereof is within a desired range (condition (ii-2)).

[0158] To satisfy the condition (ii-2), the support of the resin sheet of the present invention is preferably subjected to an antistatic treatment. Examples of such antistatic treatment include (a) providing an antistatic layer containing an antistatic agent on the first surface side (and, if necessary, the second surface side) of the support, and (b) adding an antistatic agent to the material constituting the support.

[0159] The antistatic agent may be one or more conventionally known antistatic agents selected from, for example, conductive polymers, conductive fine particles, ionic compounds, and quaternary ammonium salt compounds. Suitable examples of conductive polymers include polythiophene-based conductive polymers, polyaniline-based conductive polymers, and polypyrrole-based conductive polymers. Examples of polythiophene-based conductive polymers include polythiophene, poly(3-alkylthiophene), poly(3-thiophene-β-ethanesulfonic acid), and mixtures (including doped mixtures) of polyalkylenedioxythiophene and polystyrene sulfonate (PSS). Examples of polyaniline-based conductive polymers include polyaniline, polymethylaniline, and polymethoxyaniline. Examples of polypyrrole-based conductive polymers include polypyrrole, poly(3-methylpyrrole), and poly(3-octylpyrrole). Suitable examples of conductive fine particles include conductive inorganic fine particles such as tin oxide, antimony-doped tin oxide (ATO), indium oxide-tin oxide (ITO), zinc oxide, and antimony pentoxide; fine particles in which the surfaces of organic fine particles such as silicone fine particles are coated with a conductive compound; and conductive fine particles such as carbon fine particles. Suitable examples of ionic compounds include nitrogen-containing onium salts, sulfur-containing onium salts, phosphorus-containing onium salts, alkali metal salts, and alkaline earth metal salts. Suitable examples of quaternary ammonium salt compounds include pyrrolidium rings, quaternized alkylamines, copolymers thereof with acrylic acid or methacrylic acid, quaternized N-alkylaminoacrylamides, vinylbenzyltrimethylammonium salts, and 2-hydroxy-3-methacryloxypropyltrimethylammonium salts.

[0160] When an antistatic layer is provided on the first surface side (and, if necessary, the second surface side) of the support as an antistatic treatment for the support, the antistatic layer preferably contains a binder component in addition to the antistatic agent. The binder component is not particularly limited as long as it is a component that can disperse the antistatic agent and can form a film, and for example, a curable resin such as a polyester resin, a urethane resin, or an acrylic resin may be used.

[0161] The content of the antistatic agent in the antistatic layer is not particularly limited as long as the desired surface resistivity can be achieved, and may be appropriately determined. For example, the content of the antistatic agent is preferably 0.01% by mass or more, more preferably 0.05% by mass or more or 0.1% by mass or more, and the upper limit thereof is preferably 50% by mass or less, more preferably 30% by mass or less, when the total mass of the antistatic layer is taken as 100% by mass.

[0162] Therefore, in one embodiment, in the resin sheet of the present invention, the support is an antistatic layer-attached support having an antistatic layer bonded to the first surface of the support.

[0163] Examples of suitable embodiments (layer configurations) of the resin sheet of the present invention using a support with an antistatic layer are shown below: (1) Resin composition layer / support / antistatic layer (2) Resin composition layer / release layer / support / antistatic layer (3) Resin composition layer / antistatic layer / support / antistatic layer (4) Resin composition layer / release layer / antistatic layer / support / antistatic layer

[0164] The above embodiments (1) to (4) all use a support having an antistatic layer bonded to its first surface. Of these, embodiments (3) and (4) have an antistatic layer also provided on the second surface of the support, which makes it possible to reduce the surface resistivity of the second surface of the support.

[0165] When a release layer is provided on the second surface of the support, the release layer may contain the above-mentioned antistatic agent to provide an antistatic release layer. In this case, the release layer also functions as an antistatic layer.

[0166] Another example of antistatic treatment for a support is to add the above-mentioned antistatic agent to the material constituting the support to form a support exhibiting antistatic properties. For example, when the support is a thermoplastic resin film, an antistatic agent is added to the thermoplastic resin and the thermoplastic resin is formed into a film, thereby forming a thermoplastic resin film exhibiting antistatic properties.

[0167] Examples of suitable embodiments (layer structures) of the resin sheet of the present invention using a support exhibiting antistatic properties are shown below: (5) Resin composition layer / antistatic support (6) Resin composition layer / release layer / antistatic support

[0168] In the resin sheet of the present invention, the thickness of the support is not particularly limited, but is preferably in the range of 5 μm to 75 μm, more preferably in the range of 10 μm to 60 μm. When a support having an antistatic layer or a release layer is used, it is preferable that the thickness of the entire support, including the thickness of the antistatic layer or the release layer, is in the above-mentioned range.

[0169] The resin sheet of the present invention can be produced, for example, by preparing a resin varnish by dissolving a resin composition in an organic solvent, applying this resin varnish to the second surface side of the support using a die coater or the like, and then drying it to form a resin composition layer.

[0170] Examples of organic solvents include ketones such as acetone, methyl ethyl ketone (MEK), and cyclohexanone; acetate esters such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, and carbitol acetate; carbitols such as cellosolve and butyl carbitol; aromatic hydrocarbons such as toluene and xylene; and amide solvents such as dimethylformamide, dimethylacetamide (DMAc), and N-methylpyrrolidone. The organic solvents may be used alone or in combination of two or more.

[0171] Drying may be carried out by known methods such as heating or hot air blowing. Drying conditions are not particularly limited, but drying is carried out so that the amount of residual solvent in the resin composition layer is 10% by mass or less, preferably 5% by mass or less. Although this varies depending on the boiling point of the organic solvent in the resin varnish, for example, when a resin varnish containing 30% by mass to 60% by mass of organic solvent is used, the resin composition layer can be formed by drying at 50°C to 150°C for 3 to 10 minutes.

[0172] As described above, the resin sheet of the present invention includes a support having a first surface and a second surface, and a resin composition layer provided on the second surface of the support, and satisfies the following conditions (ii-1) and (ii-2): (ii-1) the total specific surface area of ​​the inorganic filler in the resin composition layer is 1.5 m ２ / g or more (non-volatile component equivalent). (ii-2) The surface resistivity of the first surface of the support is 1.0 × 10 １０ Ω / sq. or less

[0173] Such a resin sheet of the present invention can be suitably used in the method for producing a circuit board of the present invention, i.e., the method for producing a circuit board, which includes a step of laminating a resin sheet containing a resin composition layer on a substrate so that the resin composition layer is bonded to the substrate, and satisfies the following condition (i): (i) reducing the atmospheric pressure simultaneously with or before bonding of the resin composition layer to the substrate.

[0174] This makes it possible to suppress the occurrence of interfacial voids and to suppress an increase in the surface potential of the support, even when applied to a large-area substrate. Combined with the inherent advantage of the approach of adopting an insulating material in the form of a resin sheet, which is that it is easy to form an insulating layer with good surface flatness even when the composition is improved to highly satisfy the properties required for the insulating layer of a circuit board, the resin sheet of the present invention significantly contributes to the realization of even finer wiring while highly satisfying the properties required for the insulating layer of a circuit board.

[0175] The present invention will be described in more detail below with reference to examples. The present invention is not limited to these examples. In the following, "parts" and "%" representing amounts mean "parts by mass" and "% by mass", respectively, unless otherwise specified. Unless otherwise specified, the temperature, pressure, and humidity conditions are room temperature (25°C), atmospheric pressure (1 atm), and 50% RH.

[0176] First, various measurement and evaluation methods will be explained.

[0177] <Melt Viscosity Measurement> The melt viscosity of the resin composition layers of the resin sheets prepared in the Examples and Comparative Examples was measured using a dynamic viscoelasticity measuring device (Rheosol-G3000 manufactured by U.B.M. Co., Ltd.). 1 g of a sample resin composition collected from the resin composition layer was heated using parallel plates with a diameter of 18 mm from a starting temperature of 60°C to 200°C at a heating rate of 5°C / min, and the dynamic viscoelastic modulus was measured under the measurement conditions of a measurement temperature interval of 2.5°C, a frequency of 1 Hz, and a strain of 1 deg, and the melt viscosity (poise) at 100°C was measured.

[0178] <Measurement of Surface Resistivity> The surface resistivity (Ω / sq.) of the supports used in the examples and comparative examples was measured using a surface resistivity measuring device ("ST-4" manufactured by Simco Japan Co., Ltd., double ring electrode method).

[0179] <Evaluation of interface voids> (1) Lamination of resin sheet The resin sheets prepared in the examples and comparative examples were laminated on one side of a substrate using a sheet attachment device so that the resin composition layer was bonded to the substrate. In comparative example 1, after bonding the resin composition layer and the substrate, the chamber in which the resin sheet to be treated and the substrate were stored was depressurized to an atmospheric pressure of 13 hPa or less. On the other hand, in examples 1 to 8 and comparative example 2, the chamber in which the resin sheet to be treated and the substrate were stored was depressurized to an atmospheric pressure of 13 hPa or less, and then the resin composition layer and the substrate were bonded. Then, the resin sheet was laminated on the substrate by pressing at a temperature of 100 ° C. and a pressure of 5 MPa for 100 seconds.

[0180] In this evaluation, an 8-inch silicon wafer ("8-inch wafer" in Table 1) and a 5 cm square copper-clad laminate ("5 cm CCL" in Table 1) were prepared as substrates.

[0181] (2) Evaluation of Interfacial Voids After peeling off the support from the obtained laminate of the resin sheet and the substrate, the laminate was observed under an optical microscope (150x magnification) to evaluate whether or not voids were present at the interface between the resin composition layer and the substrate, and evaluated according to the following criteria.

[0182] Evaluation criteria: ◯: No voids present. Δ: Voids present (less than 10 voids in the surface). ×: Voids present (10 or more voids in the surface).

[0183] <Evaluation of Surface Potential> (1) Lamination of Resin Sheets A laminate of a resin sheet and a substrate was obtained in the same manner as in the above <Evaluation of Interfacial Voids>.

[0184] (2) Evaluation of Surface Potential The surface potential (kV) of the support of the obtained laminate was measured using a surface potential meter ("FMX-004" manufactured by Simco Japan Co., Ltd.) and evaluated according to the following criteria.

[0185] Evaluation criteria: ◯: Surface potential is 2 kV or less △: Surface potential is more than 2 kV and less than 4 kV ×: Surface potential is more than 4 kV

[0186] <Evaluation of Warpage> (1) Lamination of Resin Sheet A laminate of a resin sheet and a substrate was obtained in the same manner as in <Evaluation of Interfacial Voids> above, except that a 12-inch silicon wafer ("12-inch wafer" in Table 1) was used as the substrate instead of the 8-inch silicon wafer.

[0187] (2) Curing of Resin Composition Layer The obtained laminate was placed in an oven at 180° C. and heated for 90 minutes to cure the resin composition layer. The obtained substrate is referred to as “Evaluation Substrate A.”

[0188] (3) Evaluation of Warpage The edge of the obtained evaluation substrate A was pressed against a horizontal table, and the distance between the edge of the substrate on the opposite side of the pressed part and the table was measured as the amount of warpage. The warpage was evaluated according to the following criteria.

[0189] Criteria for evaluation of warpage: ○: Amount of warpage is 0 mm or more and 2 mm or less ×: Amount of warpage is more than 2 mm

[0190] <Support Used> The layer structure of the support used in the Examples and Comparative Examples is as follows: In the following, the right side of the support (PET film) is the "first surface" side, and the left side is the "second surface" side.

[0191] Support 1: PET film / antistatic layer (surface resistivity of the first surface: 1.0×10 ５Ω / sq., surface resistivity of the second surface > 1.0 x 10 １３ Ω / sq., thickness about 38 μm) Support 2: release layer / PET film / antistatic layer (surface resistivity of first surface 1.0×10 ５ Ω / sq., surface resistivity of the second surface > 1.0 x 10 １３ Ω / sq., thickness about 38 μm) Support 3: release layer / antistatic layer / PET film / antistatic layer (surface resistivity of first surface 1.0×10 ５ Ω / sq., surface resistivity of the second surface 1.0×10 ７ Ω / sq., thickness about 38 μm) Support 4: release layer / PET film (surface resistivity of first surface >1.0×10 １３ Ω / sq., surface resistivity of the second surface > 1.0 x 10 １３ Ω / sq., thickness approximately 38 μm)

[0192] Synthesis Example 1 (Production of Hollow Silica Particles A) 40 g of methanol, 0.3 g of a 25% solids aqueous solution of tetramethylammonium hydroxide, 0.7 g of dodecyltrimethylammonium chloride, and 0.4 g of hexane were added to a reaction vessel and stirred to dissolve. 120 g of ion-exchanged water was added to the methanol solution to precipitate emulsified droplets of hexane. 0.85 g of tetramethoxysilane was then slowly added, and the mixture was stirred at room temperature (25°C) for 8 hours, followed by aging for 12 hours. The resulting white precipitate was then filtered using Advantec filter paper (5C), washed with 300 mL of water, and dried at 90°C for 8 hours to obtain a dry powder of silica particles.

[0193] The obtained dried powder was heated to 600°C at a rate of 1°C / min with an air flow (3 L / min) using a high-speed heating electric furnace ("SK-2535E" manufactured by Motoyama Corporation), and calcined at 600°C for 2 hours to remove organic components, thereby obtaining hollow silica precursor particles. 0.5 g of these hollow silica precursor particles was transferred to an alumina crucible and calcined in the electric furnace at 1000°C in air for 72 hours to obtain hollow silica particles A (average particle size 1.6 μm, BET specific surface area 12 m ２ / g, and a porosity of 50% by volume.

[0194] Synthesis Example 2 (Production of Hollow Silica Particles B) Hollow silica particles B were synthesized according to the description in Japanese Patent No. 5940188. Specifically, hollow silica particles B were synthesized by the following procedure.

[0195] Water glass aqueous solution (SiO ２ / Na ２ O molar ratio 3.2, SiO ２ Using 300 g of silica-based particle precursor particles (1), 300 g of silica-based particle precursor particles (1) were sprayed into hot air at an inlet temperature of 400°C using a two-fluid nozzle at a flow rate of 0.12 kg / hr and air at a flow rate of 31,800 L / hr (air / liquid volume ratio 31,800) using a two-fluid nozzle. The outlet temperature was 150°C. Next, 50 g of silica-based particle precursor particles (1) were immersed in 500 g of a 10 wt% sulfuric acid aqueous solution and stirred for 2 hours. Next, the mixture was dried and heated in a dryer at 90°C for 12 hours to obtain hollow silica particles.

[0196] The obtained hollow silica particles were heated to 600°C at a rate of 1°C / min with an air flow (3 L / min) using a high-speed heating electric furnace (SK-2535E manufactured by Motoyama Co., Ltd.) and calcined at 600°C for 2 hours. After that, 0.5 g of the hollow silica particles were transferred to an alumina crucible and calcined in air at 1000°C for 72 hours using the electric furnace to obtain hollow silica particles B (average particle size 2.0 μm, BET specific surface area 3.8 m). ２ / g, and a porosity of 20% by volume.

[0197] Synthesis Example 3 (Synthesis of Stress Relief Material A) 69 g of bifunctional hydroxyl-terminated polybutadiene ("G-3000" manufactured by Nippon Soda Co., Ltd., number average molecular weight: 3000, hydroxyl group equivalent: 1800 g / eq.), 40 g of an aromatic hydrocarbon mixed solvent ("IPZOL 150" manufactured by Idemitsu Petrochemical Co., Ltd.), and 0.005 g of dibutyltin laurate were placed in a reaction vessel and mixed to uniformly dissolve. The resulting solution was heated to 60°C, and 8 g of isophorone diisocyanate ("IPDI" manufactured by Evonik Degussa Japan Co., Ltd., isocyanate group equivalent: 113 g / eq.) was added with further stirring, and the reaction was carried out for approximately 3 hours. This produced a first reaction solution.

[0198] Next, 23 g of cresol novolak resin (KA-1160 manufactured by DIC Corporation, hydroxyl group equivalent: 117 g / eq.) and 60 g of ethyl diglycol acetate (manufactured by Daicel Corporation) were added to the first reaction solution, and the temperature was raised to 150°C with stirring, and the reaction was carried out for about 10 hours. As a result, a second reaction solution was obtained. －１ The disappearance of the NCO peak was confirmed. The disappearance of the NCO peak was considered to be the end point of the reaction, and the temperature of the second reaction solution was lowered to room temperature. The second reaction solution was then filtered through a 100-mesh filter cloth. As a result, a solution (non-volatile component 50% by mass) containing a stress relaxation material A (phenolic hydroxyl group-containing polybutadiene resin) having reactive functional groups as a non-volatile component was obtained as the filtrate. The number average molecular weight of the stress relaxation material A was 5,900, and the glass transition temperature was -7°C.

[0199] Example 1. Preparation of Resin Sheet 1 (1) Preparation of Resin Composition A resin composition containing 3 parts of bisphenol A epoxy resin (manufactured by Mitsubishi Chemical Corporation, "828EL," epoxy equivalent: 189 g / eq.), 4 parts of naphthylene ether epoxy resin (manufactured by DIC Corporation, "HP6000," epoxy equivalent: 250 g / eq.), 4 parts of bixylenol epoxy resin (manufactured by Mitsubishi Chemical Corporation, "YX4000H," epoxy equivalent: 185 g / eq.), 2 parts of a stress relaxation agent (manufactured by Dow Chemical Company, "Paraloid EXL2655"), and 2 parts of spherical silica (manufactured by Admatechs Co., Ltd., "SO-C2," average particle size: 0.5 μm, specific surface area: 5.8 m) surface-treated with an amine-based silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., "KBM573"). ２ / g)), 76 parts of 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), 3 parts of a phenolic curing agent ("KA-1160" manufactured by DIC Corporation, a phenolic hydroxyl group equivalent of 117 g / eq.), 3 parts of an active ester curing agent ("HPC-8000-65T" manufactured by DIC Corporation, an active group equivalent of 223 g / eq., a toluene solution with a solid content of 65% by mass), 0.05 parts of a curing accelerator (4-dimethylaminopyridine (DMAP)), and 15 parts of methyl ethyl ketone were mixed and uniformly dispersed using a high-speed rotary mixer to prepare a varnish of the resin composition.

[0200] (2) Preparation of Resin Sheet The prepared varnish was uniformly applied to the second surface of the support 1 so that the thickness of the resin composition layer after drying would be 50 μm. Thereafter, the varnish was dried at 80°C to 120°C (average 100°C) for 4 minutes to prepare a resin sheet 1 including a support and a resin composition layer provided on the second surface of the support. In the obtained resin sheet 1, the total specific surface area of ​​the inorganic filler in the resin composition layer was 4.4 m ２ / g.

[0201] [Example 2. Preparation of Resin Sheet 2] Resin sheet 2 was prepared in the same manner as in Example 1, except that support 2 was used instead of support 1. In the obtained resin sheet 2, the total specific surface area of ​​the inorganic filler in the resin composition layer was 4.4 m ２ / g.

[0202] [Example 3. Preparation of Resin Sheet 3] Resin sheet 3 was prepared in the same manner as in Example 1, except that support 3 was used instead of support 1. In the obtained resin sheet 3, the total specific surface area of ​​the inorganic filler in the resin composition layer was 4.4 m ２ / g.

[0203] Example 4. Preparation of resin sheet 4 (1) Preparation of resin composition (i) Spherical silica (manufactured by Admatechs Co., Ltd., "SO-C2", average particle size 0.5 μm, specific surface area 5.8 m) surface-treated with an inorganic filler (amine-based silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., "KBM573")) ２ (ii) the amount of inorganic filler (spherical silica (Denka Company, Ltd. "UFP-30", average particle size 0.3 μm, specific surface area 30.7 m) surface-treated with an amine-based silane coupling agent (Shin-Etsu Chemical Co., Ltd. "KBM573")) was changed from 76 parts to 50 parts, ２ A varnish of the resin composition was prepared in the same manner as in Example 1, except that 20 parts of PEG-14 hydroxybenzoate (1 / g) was used.

[0204] (2) Preparation of Resin Sheet Resin sheet 4 was prepared in the same manner as in Example 1, except that support 2 was used instead of support 1 and the varnish of the prepared resin composition was applied to the second surface of support 2. In the obtained resin sheet 4, the total specific surface area of ​​the inorganic filler in the resin composition layer was 9.6 m ２ / g.

[0205] [Example 5. Preparation of resin sheet 5] (1) Preparation of resin composition 3 parts of bisphenol A type epoxy resin ("828EL" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 189 g / eq.), 1 part of naphthylene ether type epoxy resin ("HP6000" manufactured by DIC Corporation, epoxy equivalent 250 g / eq.), 4 parts of bixylenol type epoxy resin ("YX4000H" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 185 g / eq.), 2 parts of stress relaxation material ("Paraloid EXL2655" manufactured by Dow Chemical Company), 3 parts of stress relaxation material ("JP-100" manufactured by Nippon Soda Co., Ltd., epoxidized polybutadiene resin), stress relaxation material A 3 parts of an inorganic filler (spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd., average particle size 0.5 μm, specific surface area 5.8 m) surface-treated with an amine-based silane coupling agent ("KBM573" manufactured by Shin-Etsu Chemical Co., Ltd.) ２ A varnish of the resin composition was prepared by mixing 76 parts of a phenolic curing agent ("KA-1160" manufactured by DIC Corporation, phenolic hydroxyl group equivalent 117 g / eq.), 2 parts of an active ester curing agent ("HPC-8000-65T" manufactured by DIC Corporation, active group equivalent 223 g / eq., toluene solution with a solids content of 65% by mass), 0.05 parts of a curing accelerator (4-dimethylaminopyridine (DMAP)), and 15 parts of methyl ethyl ketone, and dispersing the mixture uniformly using a high-speed rotary mixer.

[0206] (2) Preparation of Resin Sheet Resin sheet 5 was prepared in the same manner as in Example 1, except that support 2 was used instead of support 1 and the varnish of the prepared resin composition was applied to the second surface of support 2. In the obtained resin sheet 5, the total specific surface area of ​​the inorganic filler in the resin composition layer was 4.4 m ２ / g.

[0207] [Example 6. Preparation of resin sheet 6] (1) Preparation of resin composition An inorganic filler (spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd., average particle size 0.5 μm, specific surface area 5.8 m) surface-treated with an amine-based silane coupling agent ("KBM573" manufactured by Shin-Etsu Chemical Co., Ltd.)) was used. ２ 76 parts of inorganic filler (spherical alumina surface-treated with KBM573 (average particle size 2 μm, specific surface area 2.1 m)) ２A varnish of the resin composition was prepared in the same manner as in Example 1, except that 110 parts of PEG-14 hydroxybenzoate (1 / g) was used.

[0208] (2) Preparation of Resin Sheet Resin sheet 6 was prepared in the same manner as in Example 1, except that support 3 was used instead of support 1 and the varnish of the prepared resin composition was applied to the second surface of support 3. In the obtained resin sheet 6, the total specific surface area of ​​the inorganic filler in the resin composition layer was 1.7 m ２ / g.

[0209] Example 7. Preparation of resin sheet 7 (1) Preparation of resin composition (i) Spherical silica (manufactured by Admatechs Co., Ltd., "SO-C2", average particle size 0.5 μm, specific surface area 5.8 m) surface-treated with an inorganic filler (an amine-based silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., "KBM573")) ２ A varnish of a resin composition was prepared in the same manner as in Example 5, except that the blending amount of (i) the hydroxybenzoate (hydroxybenzoate / hydroxybenzoate) (1 / g)) was changed from 76 parts to 66 parts, and 10 parts of (ii) hollow silica particles A were used.

[0210] (2) Preparation of Resin Sheet Resin sheet 7 was prepared in the same manner as in Example 1, except that support 3 was used instead of support 1 and the varnish of the prepared resin composition was applied to the second surface of support 3. In the obtained resin sheet 7, the total specific surface area of ​​the inorganic filler in the resin composition layer was 5.0 m ２ / g.

[0211] Example 8. Preparation of resin sheet 8 (1) Preparation of resin composition (i) Spherical silica (manufactured by Admatechs Co., Ltd., "SO-C2", average particle size 0.5 μm, specific surface area 5.8 m) surface-treated with an inorganic filler (an amine-based silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., "KBM573")) ２ A varnish of a resin composition was prepared in the same manner as in Example 5, except that the blending amount of (i) the hydroxybenzoate (hydroxybenzoate) (1 / g)) was changed from 76 parts to 66 parts, and 10 parts of (ii) hollow silica particles B were used.

[0212] (2) Preparation of Resin Sheet Resin sheet 8 was prepared in the same manner as in Example 1, except that support 3 was used instead of support 1 and the varnish of the prepared resin composition was applied to the second surface of support 3. In the obtained resin sheet 8, the total specific surface area of ​​the inorganic filler in the resin composition layer was 4.2 m ２ / g.

[0213] Comparative Example 1. Preparation of Resin Sheet C1 (1) Preparation of Resin Composition (i) 2 parts of a stress relaxation material ("Paraloid EXL2655" manufactured by Dow Chemical Company) was not used, and (ii) an inorganic filler (spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd., average particle size 0.5 μm, specific surface area 5.8 m) surface-treated with an amine-based silane coupling agent ("KBM573" manufactured by Shin-Etsu Chemical Co., Ltd.)) was used. ２ A varnish of the resin composition was prepared in the same manner as in Example 1, except that the blending amount of 20 parts of hydroxybenzoates (1 / g) was changed from 76 parts to 20 parts.

[0214] (2) Preparation of Resin Sheet Resin sheet C1 was produced in the same manner as in Example 1, except that support 4 was used instead of support 1 and the varnish of the prepared resin composition was applied to the second surface of support 4. In the obtained resin sheet C1, the total specific surface area of ​​the inorganic filler in the resin composition layer was 2.8 m ２ / g.

[0215] Comparative Example 2: Preparation of Resin Sheet C2 (1) Preparation of Resin Composition A varnish of a resin composition was prepared in the same manner as in Example 4, except that 2 parts of the stress relaxation material ("Paraloid EXL2655" manufactured by The Dow Chemical Company) was not used.

[0216] (2) Preparation of Resin Sheet Resin sheet C2 was prepared in the same manner as in Example 1, except that support 4 was used instead of support 1 and the varnish of the prepared resin composition was applied to the second surface of support 4. In the obtained resin sheet C2, the total specific surface area of ​​the inorganic filler in the resin composition layer was 9.8 m ２ / g.

[0217] The results of Examples 1 to 8 and Comparative Examples 1 and 2 are shown in Table 1.

[0218]

[0219] As a result of studying a technology for forming an insulating layer by laminating a resin composition layer onto a substrate using a resin sheet and curing it, it was confirmed that interfacial voids tend to occur when the area of ​​the substrate is large (Comparative Example 1; in Comparative Example 1, after bonding the resin composition layer and the substrate, the pressure inside the chamber containing the resin sheet and substrate to be treated was reduced).

[0220] As a result of examining a technology that can suppress the generation of interfacial voids even when an insulating material in the form of a resin sheet is applied to a substrate with a large area, the following was found: (a) the atmospheric pressure is reduced simultaneously with or before the bonding of the resin composition layer and the substrate, and (b) the total specific surface area of ​​the inorganic filler in the resin composition layer is 1.5 m ２ / g or more (non-volatile component equivalent), it was found that the generation of interfacial voids could be suppressed (Comparative Example 2). However, on the other hand, it was found that the surface potential of the support increases, particularly when the area of ​​the substrate is large (Comparative Example 2). Note that in Comparative Example 2 and Examples 1 to 8, the atmospheric pressure was reduced to a desired value before the resin composition layer and the substrate were bonded, but it was also confirmed that the same tendency (the generation of interfacial voids was suppressed but the surface potential of the support increased) occurred when the atmospheric pressure was reduced simultaneously with the bonding of the resin composition layer and the substrate.

[0221] In contrast, in the manufacturing method of the present invention, which satisfies all of the above-mentioned conditions (i), (ii-1), and (ii-2), it has been confirmed that even when an insulating material in the form of a resin sheet is applied to a large-area substrate, the occurrence of interfacial voids can be suppressed and an increase in the surface potential of the support can be suppressed (Examples 1 to 8).

Claims

1. A method for manufacturing a circuit board, comprising: (X) a step of laminating a resin sheet, which includes a support having a first and second surface and a resin composition layer provided on the second surface of the support, onto a substrate so that the resin composition layer is bonded to the substrate, and which satisfies the following conditions (i), (ii-1) and (ii-2): (i) reducing the atmospheric pressure simultaneously with or prior to bonding of the resin composition layer to the substrate; (ii-1) reducing the total specific surface area of ​​the inorganic filler in the resin composition layer to 1.5 m; ２ / g or more (non-volatile component equivalent). (ii-2) The surface resistivity of the first surface of the support is 1.0×10 １０ Ω / sq. or less 2. The method according to claim 1, wherein the base material is (a) a semiconductor wafer having an electrode pad surface; (b) a carrier substrate having a plurality of semiconductor chips obtained by singulating the semiconductor wafer (a) arranged thereon at a distance from one another so that the electrode pad surfaces are exposed; (c) a substrate having a sealing resin further provided on the carrier substrate (b) for sealing the semiconductor chips; (d) a substrate having a redistribution layer further provided on the sealing resin of the substrate (c); (e) a carrier substrate having a plurality of semiconductor chips obtained by singulating the semiconductor wafer (a) arranged thereon at a distance from one another so that the electrode pad surfaces face the carrier substrate; (f) a semiconductor chip sealing substrate having an exposed electrode pad surface, which is obtained by further providing a sealing resin for sealing the semiconductor chips on the carrier substrate (e) and then peeling off the carrier substrate; or (g) a substrate having a redistribution layer further provided on the electrode pad surface side of the semiconductor chip sealing substrate (f).

3. The method according to claim 1, wherein the substrate is a substrate with a release layer.

4. The method according to claim 1, wherein the main surface dimension (minimum dimension) of the substrate is 150 mm or more.

5. The method according to claim 1, comprising, after step (X), one or more steps selected from the group consisting of: (1) a step of curing the resin composition layer to form an insulating layer; (2) a step of drilling the insulating layer; (3) a step of desmearing the insulating layer; and (4) a step of forming a conductor layer on a surface of the insulating layer.

6. The method of claim 1, wherein the resin composition layer comprises a stress relief material.

7. The method according to any one of claims 1 to 6, wherein the circuit board is a wafer level package or a panel level package.

8. A resin sheet used in a manufacturing method of a circuit board, comprising a step of laminating a resin sheet including a resin composition layer onto a substrate so that the resin composition layer is bonded to the substrate, and satisfying the following condition (i): (i) reducing the atmospheric pressure at the same time as or before bonding the resin composition layer to the substrate, the resin sheet comprising a support having a first and second surface and a resin composition layer provided on the second surface of the support, (ii-1) a total specific surface area of ​​the inorganic filler in the resin composition layer is 1.5 m ２ / g or more (non-volatile component equivalent), and (ii-2) the surface resistivity of the first surface of the support is 1.0 × 10 １０ A resin sheet having a surface roughness of Ω / sq. or less.

9. The resin sheet according to claim 8, wherein the main surface dimension (minimum dimension) of the substrate is 150 mm or more.

10. The total specific surface area of ​​the inorganic filler in the resin composition layer is 4.0 m ２ The resin sheet according to claim 8, wherein the viscosity is 100 / g or more (calculated as non-volatile component).

11. The surface resistivity of the second surface of the support is 1.0×10 １０ The resin sheet according to claim 8, wherein the elastic modulus is Ω / sq. or less.

12. The resin sheet according to claim 8, wherein the resin composition layer contains a stress relaxation material.

13. The resin sheet according to any one of claims 8 to 12, wherein the melt viscosity of the resin composition layer at 100°C is 50,000 poise or less.