Printed wiring board and its manufacturing method

Abstract

To provide a printed wiring board including, in the same hardened layer, a via hole with an opening diameter of 50 μm or more, which can be formed efficiently by sandblasting and a via hole with an opening diameter of 32 μm or less, which can be formed by laser processing.SOLUTION: A printed wiring board includes a hardened layer formed by thermosetting a resin composition containing a thermosetting resin. The hardened layer includes: a first via hole which has a first opening with an opening diameter of 50 μm or more on one surface of the hardened layer and which is formed to penetrate through the hardened layer from the first opening; and a second via hole which has a second opening with an opening diameter of 32 μm or less on the surface and which is formed to penetrate through the hardened layer from the second opening. The hardened layer has a thickness of 25 μm or less and an elastic modulus at 25°C of 5 GPa or more and 15 GPa or less.SELECTED DRAWING: Figure 13

Description

[Technical Field]

[0001] The present invention relates to a printed wiring board having via holes and a method for manufacturing the same. [Background technology]

[0002] In recent years, as the packaging structure of printed wiring boards has become more complex and denser, the opening diameter of the via holes formed in the solder resist (insulating layer) has become smaller and the distance between the openings of the via holes has become narrower (narrower pitch), making it difficult to ensure insulation reliability using the photo-curing solder resist that has been commonly used up until now.

[0003] On the other hand, there is also an increasing demand for structures having via holes with different sizes of openings (i.e., both large and small opening via holes) on the same plane of solder resist (insulating layer).

[0004] It is known that thermosetting solder resist (insulating layer) has higher insulation reliability than photocurable solder resist (insulating layer). However, to date, due to the aspects of via hole processability and the technical aspects of coplanar substrate processing, there is no known industrially applicable method that can form large-opening via holes and small-opening via holes at high density in the same layer in thermosetting solder resist (insulating layer) (Patent Documents 1 to 3).

[0005] Additionally, thermosetting solder resist (insulating layer) tends to increase the rate of cracking and warping, and this issue needed to be overcome. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2018-032752 A (Patent Application No. 2016-164431) [Patent Document 2] JP 2010-123632 A (Patent Application No. 2008-293793) [Patent Document 3] JP 2009-119879 A (Patent Application No. 2009-051636) Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention aims to find conditions under which large via holes formed by sandblasting and small via holes formed by laser processing can be efficiently formed in the same cured layer, while suppressing the occurrence of cracks and warping, in a cured layer (insulating layer) having relatively high insulating reliability formed using a resin composition containing a thermosetting resin, and to provide a printed wiring board having via holes with an opening diameter of 50 μm or more (large openings) that can be efficiently formed by sandblasting and via holes with an opening diameter of 32 μm or less (small openings) that can be formed by laser processing in the same cured layer, and a method for manufacturing the same. [Means for solving the problem]

[0008] The present inventors have conducted extensive research to solve the above-mentioned problems. As a result, they have found that by setting the thickness of the cured layer to 25 μm or less and the modulus of elasticity of the cured layer at 25° C. to 5 GPa or more and 15 GPa or less, it is possible to efficiently form large via holes by sandblasting and small via holes by laser processing while suppressing the occurrence of cracks and warpage, and have completed the present invention. That is, the present invention includes the following.

[0009] [1] A cured layer formed by thermally curing a resin composition containing a thermosetting resin, the hardened layer comprises: a first via hole having a first opening having an opening diameter of 50 μm or more on one surface of the hardened layer and formed so as to penetrate the hardened layer from the first opening; and a second via hole having a second opening having an opening diameter of 32 μm or less on the surface and formed so as to penetrate the hardened layer from the second opening, The thickness of the cured layer is 25 μm or less, The printed wiring board has an elastic modulus at 25°C of the cured layer of 5 GPa or more and 15 GPa or less. [2] The printed wiring board according to [1] above, wherein the modulus of elasticity of the cured layer at 25°C is 10 GPa or more. [3] The printed wiring board according to [1] or [2] above, wherein the linear thermal expansion coefficient of the cured layer is 50 ppm / °C or less. [4] The printed wiring board according to any one of the above [1] to [3], wherein the cured layer has a coefficient of linear thermal expansion of 17 ppm / °C or more. [5] The printed wiring board according to any one of the above [1] to [4], wherein the thickness of the cured layer is 3 μm or more. [6] The printed wiring board according to any one of the above [1] to [5], wherein the resin composition contains an epoxy resin as the thermosetting resin. [7] The printed wiring board according to [6] above, wherein the content of the epoxy resin in the resin composition is 8% by mass or more and 40% by mass or less, when the non-volatile components in the resin composition are 100% by mass. [8] The printed wiring board according to any one of the above [1] to [7], wherein the resin composition further contains an inorganic filler. [9] The printed wiring board according to [8] above, wherein the content of the inorganic filler in the resin composition is 40% by mass or more and 77% by mass or less, when the non-volatile components in the resin composition are 100% by mass.

[10] A semiconductor device comprising the printed wiring board according to any one of [1] to [9] above.

[11] A cured layer formed by thermally curing a resin composition containing a thermosetting resin, the hardened layer comprises: a first via hole having a first opening having an opening diameter of 50 μm or more on one surface of the hardened layer and formed so as to penetrate the hardened layer from the first opening; and a second via hole having a second opening having an opening diameter of 32 μm or less on the surface and formed so as to penetrate the hardened layer from the second opening, The thickness of the cured layer is 25 μm or less, A method for producing a printed wiring board, wherein the modulus of elasticity of the cured layer at 25°C is 5 GPa or more and 15 GPa or less, A method for manufacturing a printed wiring board, comprising: a step of sandblasting the hardened layer to form the first via hole in the hardened layer; and a step of irradiating a laser toward the hardened layer after the first via hole has been formed, to form the second via hole in the hardened layer.

[12] The method for producing a printed wiring board according to

[11] above, further comprising the step of performing a desmear treatment on the printed wiring board after the second via hole has been formed. [Effects of the Invention]

[0010] According to the present invention, conditions have been found that enable large via holes formed by sandblasting and small via holes formed by laser processing to be efficiently formed in the same cured layer, which has a relatively high insulating reliability and is formed using a resin composition containing a thermosetting resin, while suppressing the occurrence of cracks and warping.This makes it possible to provide a printed wiring board that has, in the same cured layer, via holes with an opening diameter of 50 μm or more (large openings) that can be efficiently formed by sandblasting and via holes with an opening diameter of 32 μm or less (small openings) that can be formed by laser processing, and a method for manufacturing the same.

[0011] In this way, by realizing the manufacture of printed wiring boards in which via holes with different opening diameters are provided in the same cured layer using materials with relatively high insulating reliability, it becomes possible to design semiconductor devices that are more complex and precise than ever before. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view schematically showing an example of a circuit board and a resin sheet used in a method for producing a printed wiring board according to one embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view schematically showing an example of a resin sheet laminate prepared in one step in a method for producing a printed wiring board according to one embodiment of the present invention. [Figure 3]FIG. 3 is a cross-sectional view schematically showing an example of a laminate after formation of a hardening layer, which is prepared in one step of a method for producing a printed wiring board according to one embodiment of the present invention. [Figure 4] FIG. 4 is a cross-sectional view schematically showing an example of a laminate after removal of the support, which is prepared in one step in a method for producing a printed wiring board according to one embodiment of the present invention. [Figure 5] FIG. 5 is a cross-sectional view schematically showing an example of a laminated board after lamination of a resist film, which is prepared in one step of a method for producing a printed wiring board according to one embodiment of the present invention. [Figure 6] FIG. 6 is a cross-sectional view schematically showing an example of a laminate after a photomask is provided, which is prepared in one step of a method for manufacturing a printed wiring board according to one embodiment of the present invention. [Figure 7] FIG. 7 is a cross-sectional view schematically showing an example of a laminate after development treatment, which is prepared in one step in a method for producing a printed wiring board according to one embodiment of the present invention. [Figure 8] FIG. 8 is a cross-sectional view schematically showing an example of a laminate after the formation of a first via hole, which is prepared in one step of a method for manufacturing a printed wiring board according to one embodiment of the present invention. [Figure 9] FIG. 9 is a cross-sectional view schematically showing an example of a printed wiring board after the formation of a second via hole, which is manufactured in one step of a method for manufacturing a printed wiring board according to one embodiment of the present invention. [Figure 10] FIG. 10 is a cross-sectional view schematically showing an example of a printed wiring board after removing a sandblast mask manufactured in one step of a method for manufacturing a printed wiring board according to one embodiment of the present invention. [Figure 11] FIG. 11 is a cross-sectional view schematically showing an example of a printed wiring board after forming a conductor layer, which is manufactured in one step of a method for manufacturing a printed wiring board according to one embodiment of the present invention. [Figure 12] FIG. 12 is a cross-sectional view schematically showing an example of a printed wiring board after solder balls are formed, which is manufactured in one step of a method for manufacturing a printed wiring board according to one embodiment of the present invention. [Figure 13]FIG. 13 is a cross-sectional view schematically showing an example of a printed wiring board package manufactured using a printed wiring board according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] 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.

[0014] <Printed wiring board> FIG. 10 is a cross-sectional view schematically illustrating an example of a printed wiring board according to an embodiment of the present invention. As shown in FIG. 10, the printed wiring board according to an embodiment of the present invention includes a cured layer 30 formed by thermally curing a resin composition containing a thermosetting resin. The cured layer 30 includes a first via hole 70 and a second via hole 80. By forming the cured layer 30 using a thermosetting resin as a component of the resin composition, insulation reliability can be improved compared to conventional cured layers formed using a photocurable resin. This allows the printed wiring board of the present invention to be designed with a narrower pitch between via holes.

[0015] The first via hole 70 has a first opening 71 on one surface of the hardened layer 30 (the same surface as the second opening 81) and is formed so as to penetrate the hardened layer 30 from the first opening 71. The first via hole 70 has a large opening diameter that is too large to be processed by a laser, and therefore can usually be formed by sandblasting.

[0016] The opening diameter of the first opening 71 in the first via hole 70 is 50 μm or more, and from the viewpoint of ease of processing by sandblasting, it is preferably 70 μm or more, and more preferably 90 μm or more. It is usually difficult to form a via hole having an opening diameter of less than 50 μm by sandblasting. The upper limit of the opening diameter of the first opening 71 is not particularly limited, but may be, for example, 10,000 μm or less, 5,000 μm or less, 1,000 μm or less, 500 μm or less, etc. The shape of the first opening 71 is not particularly limited, and may be a circle, a substantially triangle, a substantially quadrangle (including a substantially square or a substantially rectangle), etc., and the opening diameter of the first opening 71 means its shortest diameter (diameter).

[0017] The minimum pitch of the first via holes 70 can be set narrower because the insulating reliability of the cured product is higher than that of conventional products, and is preferably 1000 μm or less, more preferably 500 μm or less, even more preferably 300 μm or less, still more preferably 200 μm or less, and particularly preferably 100 μm or less. The minimum pitch of the first via holes 70 is the shortest distance from the center (center of gravity) of a first opening 71 to the center (center of gravity) of another nearest first opening 71 on the same surface of the cured layer 30.

[0018] The first via hole 70 is formed from the first opening 71 on one surface of the hardened layer 30 to its through-hole on the other surface of the hardened layer 30 opposite to the first opening 71. Therefore, the depth of the first via hole 70 is the thickness T of the hardened layer 30. 30 (See FIG. 3 ). The first via hole 70 may have a tapered shape, for example, such that the diameter narrows from a first opening 71 on one surface of the hardened layer 30 toward its through-hole on the other surface of the hardened layer 30 opposite the first opening 71.

[0019] The second via hole 80 has a second opening 81 on one surface of the hardened layer 30 (the same surface as the first opening 71) and is formed so as to penetrate the hardened layer 30 from the second opening 81. The second via hole has a small opening diameter for processing by sandblasting, and therefore can usually be formed by laser processing.

[0020] The opening diameter of the second opening 81 in the second via hole 80 is 32 μm or less. The lower limit of the opening diameter of the second opening 81 is not particularly limited, but may be, for example, 1 μm or more, 5 μm or more, 10 μm or more, etc. The shape of the second opening 81 is not particularly limited, but since it is formed by laser processing in one embodiment, it may be preferably circular, and the opening diameter of the second opening 81 means its shortest diameter (diameter).

[0021] The minimum pitch of the second via holes 80 can be set narrower because the insulating reliability of the cured product is higher than that of conventional products, and is preferably 100 μm or less, more preferably 50 μm or less, even more preferably 30 μm or less, even more preferably 10 μm or less, and particularly preferably 5 μm or less. The minimum pitch of the second via holes 80 is the shortest distance from the center (center of gravity) of a given second opening 81 to the center (center of gravity) of the nearest other second opening 81 on the same surface of the cured layer 30. The minimum pitch of the second via holes 80 may be smaller, larger, or the same as the minimum pitch of the first via holes 70.

[0022] The second via hole 80 is formed from the second opening 81 on one side of the hardened layer 30 to its through-hole on the other side of the hardened layer 30 opposite to the second opening 81. Therefore, the depth of the second via hole 80 is the thickness T of the hardened layer 30. 30 (See FIG. 3 ). The second via hole 80 may have a tapered shape, for example, such that the diameter narrows from the second opening 81 on one surface of the hardened layer 30 toward its through-hole on the other surface of the hardened layer 30 opposite the second opening 81.

[0023] Thickness T of the hardened layer 30 30 The thickness T of the hardened layer 30 may be 25 μm or less, preferably 22 μm or less, and more preferably 20 μm or less. 30 If the thickness T of the hardened layer 30 exceeds 25 μm, it may be difficult to form a via hole. 30From the viewpoint of ensuring the required interlayer insulation, the lower limit may be preferably 3 μm or more, more preferably 5 μm or more, even more preferably 8 μm or more, and particularly preferably 10 μm or more.

[0024] The elastic modulus of the hardened layer 30 at 25°C is 5 GPa or more, and from the viewpoint of further improving sandblasting processability, it is preferably 8 GPa or more, more preferably 10 GPa or more. If the elastic modulus is below 5 GPa, it may be difficult to form the first via hole 70 by sandblasting. The upper limit of the elastic modulus of the hardened layer 30 at 25°C is 15 GPa or less. If the elastic modulus exceeds 15 GPa, warping of the hardened layer 30 may become significant. The elastic modulus of the hardened layer 30 at 25°C can be measured by the method described in Test Example 1 below.

[0025] The linear thermal expansion coefficient of the hardened layer 30 is preferably 50 ppm / °C or less, and more preferably 40 ppm / °C or less, from the viewpoint of further suppressing cracking in the hardened layer 30. The lower limit of the linear thermal expansion coefficient of the hardened layer 30 can be, for example, 10 ppm / °C or more, 15 ppm / °C or more, or 17 ppm / °C or more. The linear thermal expansion coefficient of the hardened layer 30 can be measured by the method described in Test Example 2 below.

[0026] In one embodiment, the printed wiring board of the present invention includes a circuit board 10 having, in addition to the cured layer 30, a support substrate 11 and a conductor layer 12 provided on at least a portion of the support substrate 11. In this embodiment, the cured layer 30 is provided on the circuit board 10 so as to cover the conductor layer 12.

[0027] In this embodiment, the first via hole 70 is formed so as to penetrate the hardened layer 30 from a first opening 71 on the side of the hardened layer 30 opposite to the side that contacts the circuit board 10, and reach the surface of the conductor layer 12 of the circuit board 10, and the second via hole 80 is formed so as to penetrate the hardened layer 30 from a second opening 81 on the side of the hardened layer 30 opposite to the side that contacts the circuit board 10, and reach the surface of the conductor layer 12 of the circuit board 10.

[0028] Fig. 11 is a cross-sectional view schematically showing another example of a printed wiring board according to one embodiment of the present invention. In one embodiment, as shown in Fig. 11, the printed wiring board of the present invention has a conductor layer 12' formed in a first via hole 70 from a first opening 71 to the surface of the conductor layer 12 of the circuit board 10 where the through-hole portion is located, and in a second via hole 80 from a second opening 81 to the surface of the conductor layer 12 of the circuit board 10 where the through-hole portion is located.

[0029] In this embodiment, the printed wiring board of the present invention further includes a conductor layer 12' formed on the surface of the first opening 71 outside the first via hole 70, continuing from inside the first via hole 70, and a conductor layer 12' formed on the surface of the second opening 81 outside the second via hole 80, continuing from the second via hole 80. In this embodiment, the conductor layer 12' formed on the surface of the first opening 71 or the second opening 81 is electrically conductive with the conductor layer 12 in the pre-formed circuit board 10 via the conductor layer 12' formed in the first via hole 70 or the second via hole 80, respectively. In this embodiment, a conductor layer 12' is further formed on at least a portion of the surface of the cured layer 30 opposite to the side that contacts the circuit board 10, continuing from the conductor layer 12' on the surface of the first opening 71 or the second opening 81.

[0030] 12 is a cross-sectional view schematically illustrating another example of a printed wiring board according to an embodiment of the present invention. In this embodiment, the printed wiring board of the present invention further includes, as shown in FIG. 12, a first solder ball 90a formed on the surface of the conductor layer 12′ formed on the surface of the first opening 71, and a second solder ball 90b formed on the surface of the conductor layer 12′ formed on the surface of the second opening 81. The first solder ball 90a may be larger in size than the second solder ball 90b.

[0031] The method for producing a printed wiring board of the present invention includes the following steps (F) and (G). In one embodiment, it further includes the following step (H). In one embodiment of this embodiment, it further includes the following step (I). In one embodiment of this embodiment, it further includes the following step (J). In one embodiment of this embodiment, it further includes the following step (K). In one embodiment, it further includes the following step (E). In one embodiment of this embodiment, it further includes the following step (D). In one embodiment of this embodiment, it further includes the following step (C). In one embodiment of this embodiment, it further includes the following step (B). In one embodiment of this embodiment, it further includes the following step (A).

[0032] Step (A): A step of preparing a resin composition by mixing and dispersing the components to be contained in the resin composition, which will be described below. Step (B): A step of preparing a resin sheet including a support and a resin composition layer formed from a resin composition provided on the support. Step (C): A step of laminating a resin sheet on the circuit board 10 so that the resin composition layer of the resin sheet is bonded to the circuit board 10, thereby preparing a resin sheet laminate C. Step (D): A step of thermally curing the resin composition layer of the resin sheet laminate C to form a cured layer 30 formed of a cured product of the resin composition. Step (E): Step of removing the support from the laminate D after the hardened layer is formed Step (F): A step of sandblasting the hardened layer 30 of the laminate E after removing the support, and forming the first via hole 70 in the hardened layer 30 Step (G): A step of irradiating a laser toward the cured layer 30 of the laminate F2 after the first via hole has been formed, to form a second via hole 80 in the cured layer 30. Step (H): An optional step of removing the sandblasting mask if it remains on the printed wiring board G after the second via holes are formed. Step (I): A step of performing a desmear treatment on the printed wiring board H after removing the sandblast mask (the printed wiring board G after forming the second via hole). Step (J): A step of forming a new conductor layer 12′ in the first via hole 70 from the first opening 71 to the circuit board 10 in the printed wiring board I after desmearing, and continuously therefrom on the surface of the first opening 71 outside the first via hole 70, and in the second via hole 80 from the second opening 81 to the circuit board 10, and continuously therefrom on the surface of the second opening 81 outside the second hole 80. Step (K): A step of forming first solder balls 90a on the surface of conductor layer 12′ formed on the surface of first opening 71 in printed wiring board J after the formation of the conductor layer, and forming second solder balls 90b on the surface of conductor layer 12′ formed on the surface of second opening 81

[0033] The printed wiring board of the present invention can be made into a printed wiring board package L by further going through the following step (L).

[0034] Step (L): A step of electrically connecting the printed wiring board K after the solder balls have been formed to the first circuit board 10a and the second circuit board 10b placed in parallel therewith via the first solder balls 90a and the second solder balls 90b, and further sealing the spaces between the printed wiring board K and the first circuit board 10a and the second circuit board 10b with sealing resin 100, thereby manufacturing the printed wiring board package L.

[0035] Each step will be described in detail below.

[0036] <(A) Resin Composition Preparation Step> In step (A), the components to be contained in the resin composition, which will be described below, are mixed and dispersed to prepare the resin composition.

[0037] The resin composition prepared in step (A) can be produced, for example, by adding the components to be contained in the resin composition described below to any preparation vessel in any order and / or all or part of them at the same time, and mixing and dispersing them. During the process of adding and mixing each component, the temperature can be set appropriately, and heating and / or cooling may be performed temporarily or throughout. During or after the process of adding and mixing, the resin composition may be stirred or shaken using a stirring or shaking device such as a mixer to uniformly disperse it. Simultaneously with the stirring or shaking, degassing may be performed under low-pressure conditions, such as under vacuum.

[0038] The resin composition prepared in step (A) contains (a) a thermosetting resin. By using such a resin composition, a cured layer with excellent insulating properties can be obtained. Furthermore, the resin composition prepared in step (A) may further contain, in addition to (a) a thermosetting resin, (b) a curing accelerator, (c) a thermoplastic resin, (d) an inorganic filler, (e) an organic filler, (f) a flame retardant, (g) other additives, and (h) an organic solvent. Each component contained in the resin composition prepared in step (A) is described in detail below.

[0039] ((a) thermosetting resin) The resin composition prepared in step (A) contains (a) a thermosetting resin, such as an epoxy resin, an epoxy acrylate resin, a urethane acrylate resin, a urethane resin, a cyanate resin, a polyimide resin, a benzoxazine resin, an unsaturated polyester resin, a phenolic resin, a melamine resin, or a silicone resin.

[0040] ((a-1) Epoxy resin) The resin composition prepared in step (A) preferably contains (a-1) an epoxy resin as (a) a thermosetting resin. (a-1) An epoxy resin refers to a resin having an epoxy group.

[0041] Examples of (a-1) epoxy resins include bixylenol-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol S-type epoxy resins, bisphenol AF-type epoxy resins, dicyclopentadiene-type epoxy resins, trisphenol-type epoxy resins, naphthol novolac-type epoxy resins, phenol novolac-type epoxy resins, tert-butyl-catechol-type epoxy resins, naphthalene-type epoxy resins, naphthol-type epoxy resins, anthracene-type epoxy resins, glycidylamine-type epoxy resins, glycidyl ester-type epoxy resins, cresol novolac-type epoxy resins, biphenyl-type epoxy resins, linear aliphatic epoxy resins, epoxy resins having a butadiene structure, alicyclic epoxy resins, heterocyclic epoxy resins, spiro ring-containing epoxy resins, cyclohexane-type epoxy resins, cyclohexanedimethanol-type epoxy resins, naphthylene ether-type epoxy resins, trimethylol-type epoxy resins, and tetraphenylethane-type epoxy resins. Epoxy resins may be used alone or in combination of two or more.

[0042] The resin composition preferably contains, as the (a-1) epoxy resin, an epoxy resin having two or more epoxy groups per molecule. From the viewpoint of significantly achieving the desired effects of the present invention, the proportion of the epoxy resin having two or more epoxy groups per molecule relative to 100% by mass of the non-volatile components of the (a-1) epoxy resin is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more.

[0043] The (a-1) epoxy resin includes an epoxy resin that is liquid at a temperature of 25°C (hereinafter sometimes referred to as a "liquid epoxy resin") and an epoxy resin that is solid at a temperature of 25°C (hereinafter sometimes referred to as a "solid epoxy resin"). The resin composition prepared in step (A) may contain, as the (a-1) epoxy resin, only a liquid epoxy resin, or only a solid epoxy resin, or a combination of a liquid epoxy resin and a solid epoxy resin; in a preferred embodiment, the resin composition contains a combination of a liquid epoxy resin and a solid epoxy resin.

[0044] The liquid epoxy resin is preferably a liquid epoxy resin having two or more epoxy groups in one molecule.

[0045] Preferred liquid epoxy resins include glycerol-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol AF-type epoxy resins, naphthalene-type epoxy resins, glycidyl ester-type epoxy resins, glycidyl amine-type epoxy resins, phenol novolac-type epoxy resins, alicyclic epoxy resins having an ester skeleton, cyclohexanedimethanol-type epoxy resins, and epoxy resins having a butadiene structure, and more preferred are glycerol-type epoxy resins, bisphenol A-type epoxy resins, and bisphenol F-type epoxy resins.

[0046] Specific examples of liquid epoxy resins include "HP4032", "HP4032D", and "HP4032SS" (naphthalene type epoxy resins) manufactured by DIC Corporation; "828US", "jER828EL" (bisphenol A type epoxy resin), "jER807" (bisphenol F type epoxy resin), and "jER152" (phenol novolac type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "630" and "630LSD" manufactured by Mitsubishi Chemical Corporation; "ED-523T" (glycilol type epoxy resin (ADEKA glycilol)) and "EP-3980S" (glycidylamine type epoxy resin) manufactured by ADEKA Corporation; Examples include "EP-4088S" (dicyclopentadiene type epoxy resin); "ZX1059" (a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "EX-721" (glycidyl ester type epoxy resin) manufactured by Nagase ChemteX Corporation; "Celloxide 2021P" (alicyclic epoxy resin with an ester skeleton) and "PB-3600" (epoxy resin with a butadiene structure) manufactured by Daicel Corporation; and "ZX1658" and "ZX1658GS" (liquid 1,4-glycidylcyclohexane) manufactured by Nippon Steel Chemical & Material Co., Ltd.

[0047] As the solid epoxy resin, a solid epoxy resin having three or more epoxy groups in one molecule is preferred, and an aromatic solid epoxy resin having three or more epoxy groups in one molecule is more preferred.

[0048] 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.

[0049] 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-73" manufactured by DIC Corporation. 11", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP6000" (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" manufactured by Nippon Steel Chemical & Material Co., Ltd. (Naphthalene-type epoxy resin); "ESN485" (naphthol-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ESN375" (dihydroxynaphthalene-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YX4000H", "YX4000", "YX4000HK", 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; "YX77" manufactured by Mitsubishi Chemical Corporation Examples of epoxy resins include "00" (phenol aralkyl type epoxy resin); "PG-100" and "CG-500" manufactured by Osaka Gas Chemicals Co., Ltd.; "YL7760" (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.

[0050] When a liquid epoxy resin and a solid epoxy resin are used in combination as the (a-1) epoxy resin, the mass ratio thereof (liquid epoxy resin:solid epoxy resin) is preferably 1:1 to 1:20, more preferably 1:1.5 to 1:15, and particularly preferably 1:2 to 1:10.

[0051] The epoxy equivalent of the (a-1) epoxy resin is preferably 50 g / eq to 5000 g / eq, more preferably 50 g / eq to 3000 g / eq, even more preferably 80 g / eq to 2000 g / eq, and even more preferably 110 g / eq to 1000 g / eq. The epoxy equivalent is the mass of the resin per equivalent of epoxy groups. This epoxy equivalent can be measured according to JIS K7236.

[0052] From the viewpoint of significantly achieving the desired effects of the present invention, the weight-average molecular weight (Mw) of the (a-1) epoxy resin is preferably 100 to 5000, more preferably 250 to 3000, and even more preferably 400 to 1500. The weight-average molecular weight of the resin can be measured by gel permeation chromatography (GPC) as a polystyrene-equivalent value.

[0053] The content of the (a-1) epoxy resin in the resin composition prepared in step (A) is not particularly limited, but from the viewpoint of further suppressing cracking in the cured layer and further improving sandblasting processability, when the non-volatile components in the resin composition are taken as 100% by mass, the content is preferably 70% by mass or less, more preferably 60% by mass or less, even more preferably 50% by mass or less or 40% by mass or less, and particularly preferably 30% by mass or less or 20% by mass or less; and the lower limit is not particularly limited, but from the viewpoint of further suppressing warping of the cured layer, the content is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 8% by mass or more, and particularly preferably 10% by mass or more.

[0054] ((a-2) Epoxy curing agent) The resin composition prepared in step (A) may contain (a-1) an epoxy resin as the thermosetting resin (a), and may further contain (a-2) an epoxy curing agent as an optional component. The (a-2) epoxy curing agent reacts with the (a-1) epoxy resin to cure the resin composition.

[0055] The (a-2) epoxy curing agent is not particularly limited, but examples thereof include active ester curing agents, phenolic curing agents, carbodiimide curing agents, acid anhydride curing agents, amine curing agents, benzoxazine curing agents, cyanate ester curing agents, and thiol curing agents. Among these, active ester curing agents, phenolic curing agents, carbodiimide curing agents, and cyanate ester curing agents are preferred. The (a-2) epoxy curing agents may be used alone or in combination of two or more.

[0056] Examples of active ester curing agents include curing agents having one or more active ester groups per molecule. Among these, preferred active ester curing agents are compounds 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. 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, active ester curing agents obtained from a carboxylic acid compound and a hydroxy compound are preferred, and active ester curing agents obtained from a carboxylic acid compound and a phenol compound and / or a naphthol compound are more preferred.

[0057] 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.

[0058] 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, and phenol novolak. Here, "dicyclopentadiene-type diphenol compounds" refers to diphenol compounds obtained by condensing one dicyclopentadiene molecule with two phenol molecules.

[0059] Preferred specific examples of active ester curing agents include active ester compounds containing a dicyclopentadiene-type diphenol structure, active ester compounds containing a naphthalene structure, active ester compounds containing an acetylated product of phenol novolac, and active ester compounds containing a benzoylated product of phenol novolac. Among these, active ester compounds containing a naphthalene structure and active ester compounds containing a dicyclopentadiene-type diphenol structure are more preferred. The "dicyclopentadiene-type diphenol structure" refers to a divalent structure consisting of phenylene-dicyclopentylene-phenylene.

[0060] Commercially available active ester curing agents include active ester compounds containing a dicyclopentadiene-type diphenol structure, such as "EXB9451," "EXB9460," "EXB9460S," "HPC-8000," "HPC-8000H," "HPC-8000-65T," "HPC-8000H-65TM," and "EXB-8000L-65TM" (manufactured by DIC Corporation); and active ester compounds containing a naphthalene structure, such as "HPC-8150-62T," "EXB-8100L-65T," "EXB-8150L-65T," "EXB9416-70BK," and "HPC-8900-70BK." (manufactured by DIC Corporation); "DC808" (manufactured by Mitsubishi Chemical Corporation) as an active ester compound containing an acetylated product of phenol novolac; "YLH1026" (manufactured by Mitsubishi Chemical Corporation) as an active ester compound containing a benzoylated product of phenol novolac; "DC808" (manufactured by Mitsubishi Chemical Corporation) as an active ester-based curing agent which is an acetylated product of phenol novolac; and "YLH1026" (manufactured by Mitsubishi Chemical Corporation), "YLH1030" (manufactured by Mitsubishi Chemical Corporation), and "YLH1048" (manufactured by Mitsubishi Chemical Corporation) as active ester-based curing agents which are benzoylated products of phenol novolac.

[0061] Examples of phenolic curing agents include curing agents having one or more, preferably two or more, hydroxyl groups bonded to an aromatic ring (such as a benzene ring or a naphthalene ring) per molecule. Among these, compounds having a hydroxyl group bonded to a benzene ring are preferred. Furthermore, from the viewpoint of heat resistance and water resistance, phenolic curing agents having a novolac structure are preferred. Furthermore, from the viewpoint of adhesion, nitrogen-containing phenolic curing agents are preferred, and triazine skeleton-containing phenolic curing agents are more preferred. In particular, from the viewpoint of achieving high levels of heat resistance, water resistance, and adhesion, triazine skeleton-containing phenolic novolac curing agents are preferred.

[0062] Specific examples of phenolic curing agents include "MEH-7700", "MEH-7810", "MEH-7851", and "MEH-8000H" manufactured by Meiwa Kasei 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", "SN-495V", "SN-375", and "SN- 395"; "TD-2090", "TD-2090-60M", "LA-7052", "LA-7054", "LA-1356", "LA-3018", "LA-3018-50P", "EXB-9500", "HPC-9500", "KA-1160", "KA-1163", and "KA-1165" manufactured by DIC Corporation; and "GDP-6115L", "GDP-6115H", and "ELPC75" manufactured by Gun-ei Chemical Co., Ltd.

[0063] Examples of carbodiimide curing agents include curing agents having one or more, preferably two or more, carbodiimide structures in one molecule, such as aliphatic biscarbodiimides such as tetramethylene-bis(t-butylcarbodiimide) and cyclohexane-bis(methylene-t-butylcarbodiimide); aromatic biscarbodiimides such as phenylene-bis(xylylcarbodiimide); and aliphatic polycarbodiimides such as polyhexamethylenecarbodiimide, polytrimethylhexamethylenecarbodiimide, polycyclohexylenecarbodiimide, poly(methylenebiscyclohexylenecarbodiimide), and poly(isophoronecarbodiimide). ; aromatic polycarbodiimides such as poly(phenylenecarbodiimide), poly(naphthylenecarbodiimide), poly(tolylenecarbodiimide), poly(methyldiisopropylphenylenecarbodiimide), poly(triethylphenylenecarbodiimide), poly(diethylphenylenecarbodiimide), poly(triisopropylphenylenecarbodiimide), poly(diisopropylphenylenecarbodiimide), poly(xylylenecarbodiimide), poly(tetramethylxylylenecarbodiimide), poly(methylenediphenylenecarbodiimide), and poly[methylenebis(methylphenylene)carbodiimide].

[0064] Commercially available carbodiimide curing agents include, for example, "Carbodilite V-02B," "Carbodilite V-03," "Carbodilite V-04K," "Carbodilite V-07," and "Carbodilite V-09" manufactured by Nisshinbo Chemical Inc.; and "Stavaxol P," "Stavaxol P400," and "Hykasil 510" manufactured by Rhein Chemie.

[0065] The acid anhydride curing agent may be a curing agent having one or more acid anhydride groups in one molecule, and a curing agent having two or more acid anhydride groups in one molecule is preferred. Specific examples of the acid anhydride curing agent 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 acid anhydrides include biphenyltetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, oxydiphthalic dianhydride, 3,3'-4,4'-diphenylsulfonetetracarboxylic dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-C]furan-1,3-dione, ethylene glycol bis(anhydrotrimellitate), and polymeric acid anhydrides such as styrene-maleic acid resins (copolymers of styrene and maleic acid). Commercially available acid anhydride curing agents include "HNA-100," "MH-700," "MTA-15," "DDSA," and "OSA" from New Japan Chemical Co., Ltd., "YH-306" and "YH-307" from Mitsubishi Chemical Corporation, and "HN-2200" and "HN-5500" from Hitachi Chemical Co., Ltd.

[0066] Examples of the amine curing agent include curing agents having one or more, preferably two or more, amino groups in one molecule, such as aliphatic amines, polyether amines, alicyclic amines, and aromatic amines, among which aromatic amines are preferred from the viewpoint of achieving the desired effects of the present invention. The amine curing agent is preferably a primary amine or a secondary amine, and more preferably a primary amine. Specific examples of amine-based curing agents include 4,4'-methylenebis(2,6-dimethylaniline), 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 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-hydroxyphenyl)propane. 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 "SEIKACURE-S" manufactured by Seika Corporation, "KAYABOND C-200S", "KAYABOND C-100", "KAYAHARD AA", "KAYAHARD AB", and "KAYAHARD AS" manufactured by Nippon Kayaku Co., Ltd., and "Epicure W" manufactured by Mitsubishi Chemical Corporation.

[0067] Specific examples of benzoxazine curing agents include "JBZ-OP100D" and "ODA-BOZ" manufactured by JFE Chemical Corporation; "HFB2006M" manufactured by Showa Polymer Co., Ltd.; and "Pd" and "Fa" manufactured by Shikoku Chemicals Corporation.

[0068] 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, cresol novolac, etc.; and prepolymers in which these cyanate resins are partially converted to triazine. Specific examples of cyanate ester curing agents include "PT30" and "PT60" (phenol novolac type multifunctional cyanate ester resins), "ULL-950S" (multifunctional cyanate ester resin), "BADCy" (bisphenol A dicyanate), "BA230", and "BA230S75" (prepolymers in which part or all of bisphenol A dicyanate has been triazine converted to a trimer), all of which are manufactured by Lonza Japan.

[0069] Examples of thiol-based curing agents include trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), and tris(3-mercaptopropyl)isocyanurate.

[0070] The reactive group equivalent of the (a-2) epoxy curing agent is preferably 50 g / eq. to 3000 g / eq., more preferably 100 g / eq. to 1000 g / eq., even more preferably 100 g / eq. to 500 g / eq., and particularly preferably 100 g / eq. to 300 g / eq. The reactive group equivalent is the mass of the curing agent per equivalent of reactive group. For example, in the case of a phenol-based curing agent, the reactive group is a phenolic hydroxyl group. In the case of an acid anhydride-based curing agent, one equivalent of a carboxylic anhydride group (-CO-O-CO-) corresponds to two equivalents of reactive group.

[0071] The content of (a-2) epoxy curing agent in the resin composition prepared in step (A) is not particularly limited, but from the viewpoint of obtaining the effects of the invention more significantly, when the non-volatile components in the resin composition are taken as 100% by mass, the content is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and particularly preferably 20% by mass or less, and the lower limit thereof is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 3% by mass or more, and particularly preferably 5% by mass or more.

[0072] ((b) Curing accelerator) The resin composition prepared in step (A) may contain (a-1) an epoxy resin as (a) a thermosetting resin, and may further contain (b) a curing accelerator as an optional component. The (b) curing accelerator has the function of accelerating the curing of the (a-1) epoxy resin.

[0073] Examples of (b) curing accelerators include imidazole-based curing accelerators, phosphorus-based curing accelerators, urea-based curing accelerators, guanidine-based curing accelerators, metal-based curing accelerators, and amine-based curing accelerators, among which imidazole-based curing accelerators, metal-based curing accelerators, and amine-based curing accelerators are preferred. The (b) curing accelerators may be used alone or in combination of two or more.

[0074] Examples of the imidazole curing accelerator include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, and 1-benzyl-2-methylimidazole. Phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl -(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct , 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, 2-phenylimidazoline, and other imidazole compounds, as well as adducts of imidazole compounds with epoxy resins.

[0075] As the imidazole-based curing accelerator, commercially available products may be used, such as "1B2PZ", "2MZA-PW", and "2PHZ-PW" manufactured by Shikoku Chemical Industry Co., Ltd., and "P200-H50" manufactured by Mitsubishi Chemical Corporation.

[0076] Examples of the phosphorus-based curing accelerator include aliphatic phosphonium salts such as tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, tetrabutylphosphonium decanoate, tetrabutylphosphonium laurate, bis(tetrabutylphosphonium)pyromellitate, tetrabutylphosphonium hydrogenhexahydrophthalate, tetrabutylphosphonium 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenolate, and di-tert-butyldimethylphosphonium tetraphenylborate; methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, propyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, tetraphenylphosphonium bromide, p-tolyltriphenylphosphonium tetra-p-tolylborate, and tetraphenylphosphonium tetra-p-tolylborate. aromatic phosphonium salts such as tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, triphenylethylphosphonium tetraphenylborate, tris(3-methylphenyl)ethylphosphonium tetraphenylborate, tris(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, and butyltriphenylphosphonium thiocyanate; aromatic phosphine-borane complexes such as triphenylphosphine-triphenylborane; aromatic phosphine-quinone adducts such as triphenylphosphine-p-benzoquinone adduct; aliphatic phosphines such as tributylphosphine, tri-tert-butylphosphine, trioctylphosphine, di-tert-butyl(2-butenyl)phosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, and tricyclohexylphosphine;Dibutylphenylphosphine, di-tert-butylphenylphosphine, methyldiphenylphosphine, ethyldiphenylphosphine, butyldiphenylphosphine, diphenylcyclohexylphosphine, triphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tris(4-ethylphenyl)phosphine, tris(4-propylphenyl)phosphine, tris(4-isopropylphenyl)phosphine, tris(4-butylphenyl)phosphine, tris(4-tert-butylphenyl)phosphine, tris(2,4-dimethylphenyl)phosphine, tris(2,5-dimethylphenyl)phosphine, tris(2,6-dimethylphenyl)phosphine aromatic phosphines such as benzene, tris(3,5-dimethylphenyl)phosphine, tris(2,4,6-trimethylphenyl)phosphine, tris(2,6-dimethyl-4-ethoxyphenyl)phosphine, tris(2-methoxyphenyl)phosphine, tris(4-methoxyphenyl)phosphine, tris(4-ethoxyphenyl)phosphine, tris(4-tert-butoxyphenyl)phosphine, diphenyl-2-pyridylphosphine, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, 1,2-bis(diphenylphosphino)acetylene, and 2,2'-bis(diphenylphosphino)diphenyl ether;

[0077] Examples of the urea-based curing accelerator include 1,1-dimethylurea; aliphatic dimethylureas such as 1,1,3-trimethylurea, 3-ethyl-1,1-dimethylurea, 3-cyclohexyl-1,1-dimethylurea, and 3-cyclooctyl-1,1-dimethylurea; 3-phenyl-1,1-dimethylurea, 3-(4-chlorophenyl)-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea, 3-(2-methylphenyl)-1,1-dimethylurea, 3-(4-methylphenyl)-1,1-dimethylurea, and 3-(3,4-dimethylphenyl)-1,1-dimethylurea. aromatic dimethylureas such as toluene bis(dimethylurea), 3-(4-isopropylphenyl)-1,1-dimethylurea, 3-(4-methoxyphenyl)-1,1-dimethylurea, 3-(4-nitrophenyl)-1,1-dimethylurea, 3-[4-(4-methoxyphenoxy)phenyl]-1,1-dimethylurea, 3-[4-(4-chlorophenoxy)phenyl]-1,1-dimethylurea, 3-[3-(trifluoromethyl)phenyl]-1,1-dimethylurea, N,N-(1,4-phenylene)bis(N',N'-dimethylurea), and N,N-(4-methyl-1,3-phenylene)bis(N',N'-dimethylurea) [toluene bisdimethylurea].

[0078] Examples of guanidine curing accelerators include dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1-methylbiguanide, 1-ethylbiguanide, 1-n-butylbiguanide, 1-n-octadecylbiguanide, 1,1-dimethylbiguanide, 1,1-diethylbiguanide, 1-cyclohexylbiguanide, 1-allylbiguanide, 1-phenylbiguanide, and 1-(o-tolyl)biguanide.

[0079] Examples of metal-based curing accelerators include organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Specific examples of organometallic complexes include organic cobalt complexes such as cobalt(II) acetylacetonate and cobalt(III) acetylacetonate, organic copper complexes such as copper(II) acetylacetonate, organic zinc complexes such as zinc(II) acetylacetonate, organic iron complexes such as iron(III) acetylacetonate, organic nickel complexes such as nickel(II) acetylacetonate, and organic manganese complexes such as manganese(II) acetylacetonate. Examples of organometallic salts include zinc octoate, tin octoate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

[0080] Examples of the amine-based curing accelerator include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, and 1,8-diazabicyclo(5,4,0)-undecene.

[0081] As the amine-based curing accelerator, commercially available products may be used, for example, "MY-25" manufactured by Ajinomoto Fine-Techno Co., Ltd.

[0082] The content of (b) the curing accelerator in the resin composition prepared in step (A) is not particularly limited, but from the viewpoint of significantly obtaining the effects of the present invention, when the non-volatile components in the resin composition are taken as 100% by mass, the content is preferably 2% by mass or less, more preferably 1% by mass or less, even more preferably 0.5% by mass or less, and particularly preferably 0.2% by mass or less, and the lower limit thereof may be, for example, 0% by mass or more, 0.001% by mass or more, 0.01% by mass or more, etc.

[0083] ((c) Thermoplastic resin) The resin composition prepared in step (A) may contain (c) a thermoplastic resin as an optional component.

[0084] Examples of (c) thermoplastic resins include phenoxy resins, polyvinyl acetal resins, acrylic resins, polyolefin resins, polybutadiene resins, polyimide resins, polyamideimide resins, polysulfone resins, polyethersulfone resins, polyphenylene ether resins, polyetherimide resins, polycarbonate resins, polyetheretherketone resins, and polyester resins, and among these, polyphenylene ether resins and phenoxy resins are preferred. (c) Thermoplastic resins may be used singly or in combination of two or more.

[0085] Examples of phenoxy resins include phenoxy resins having one or more skeletons selected from the group consisting of bisphenol A, bisphenol F, bisphenol S, bisphenolacetophenone, novolac, biphenyl, fluorene, dicyclopentadiene, norbornene, naphthalene, anthracene, adamantane, terpene, and trimethylcyclohexane. The terminal of the phenoxy resin may be any functional group such as a phenolic hydroxyl group or an epoxy group. One type of phenoxy resin may be used alone, or two or more types may be used in combination. Specific examples of phenoxy resins include "1256" and "4250" (both phenoxy resins containing a bisphenol A skeleton), "YX8100" (phenoxy resin containing a bisphenol S skeleton), and "YX6954" (phenoxy resin containing a bisphenol acetophenone skeleton) manufactured by Mitsubishi Chemical Corporation; "FX280" and "FX293" manufactured by Nippon Steel Chemical & Material Co., Ltd.; and "YX7200B35," "YL7500BH30," "YX6954BH30," "YX7553," "YX7553BH30," "YL7769BH30," "YL6794," "YL7213," "YL7290," and "YL7482" manufactured by Mitsubishi Chemical Corporation.

[0086] Examples of polyvinyl acetal resins include polyvinyl formal resins and polyvinyl butyral resins, with polyvinyl butyral resins being preferred. Specific examples of polyvinyl acetal resins include Denka Butyral 4000-2, Denka Butyral 5000-A, Denka Butyral 6000-C, and Denka Butyral 6000-EP, all manufactured by Denki Kagaku Kogyo Co., Ltd., and S-LEC BH series, BX series (e.g., BX-5Z), KS series (e.g., KS-1), BL series, and BM series, all manufactured by Sekisui Chemical Co., Ltd.

[0087] The acrylic resin refers to a polymer obtained by polymerizing a monomer component containing a (meth)acrylic acid ester monomer. The monomer component constituting the acrylic resin may contain, in addition to the (meth)acrylic acid ester monomer, a (meth)acrylamide monomer, a styrene monomer, a functional group-containing monomer, or the like as a copolymerization component. Specific examples of acrylic resins include "ARUFON UP-1000," "ARUFON UP-1010," "ARUFON UP-1020," "ARUFON UP-1021," "ARUFON UP-1061," "ARUFON UP-1080," "ARUFON UP-1110," "ARUFON UP-1170," "ARUFON UP-1190," "ARUFON UP-1500," "ARUFON UH-2000," "ARUFON UH-2041," "ARUFON UH-2190," "ARUFON UHE-2012," "ARUFON UC-3510," "ARUFON UG-4010," "ARUFON US-6100," and "ARUFON US-6170," all manufactured by Toagosei Co., Ltd. These may be used alone or in combination of two or more.

[0088] Examples of polyolefin resins include ethylene copolymer resins such as low-density polyethylene, very low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-methyl acrylate copolymer; and polyolefin elastomers such as polypropylene and ethylene-propylene block copolymer.

[0089] Examples of polybutadiene resins include hydrogenated polybutadiene skeleton-containing resins, hydroxy group-containing polybutadiene resins, phenolic hydroxy group-containing polybutadiene resins, carboxy group-containing polybutadiene resins, acid anhydride group-containing polybutadiene resins, epoxy group-containing polybutadiene resins, isocyanate group-containing polybutadiene resins, urethane group-containing polybutadiene resins, and polyphenylene ether-polybutadiene resins.

[0090] Specific examples of polyimide resins include "Rikacoat SN20" and "Rikacoat PN20" manufactured by New Japan Chemical Co., Ltd. Specific examples of polyimide resins also include modified polyimides such as linear polyimides obtained by reacting bifunctional hydroxyl group-terminated polybutadiene, a diisocyanate compound, and a tetrabasic acid anhydride (polyimides described in JP-A No. 2006-37083), and polysiloxane skeleton-containing polyimides (polyimides described in JP-A Nos. 2002-12667 and 2000-319386).

[0091] Specific examples of polyamide-imide resins include "Vylomax HR11NN" and "Vylomax HR16NN" manufactured by Toyobo Co., Ltd. Specific examples of polyamide-imide resins also include modified polyamide-imides such as "KS9100" and "KS9300" (polysiloxane skeleton-containing polyamide-imides) manufactured by Hitachi Chemical Co., Ltd.

[0092] A specific example of the polyethersulfone resin is "PES5003P" manufactured by Sumitomo Chemical Co., Ltd.

[0093] Specific examples of polysulfone resins include polysulfones "P1700" and "P3500" manufactured by Solvay Advanced Polymers K.K.

[0094] Specific examples of polyphenylene ether resins include oligophenylene ether-styrene resins "OPE-2St1200" and "OPE-2St2200" manufactured by Mitsubishi Gas Chemical Company, Inc., and "NORYL SA90" manufactured by SABIC. Specific examples of polyetherimide resins include "Ultem" manufactured by GE.

[0095] Examples of polycarbonate resins include hydroxyl group-containing carbonate resins, phenolic hydroxyl group-containing carbonate resins, carboxyl group-containing carbonate resins, acid anhydride group-containing carbonate resins, isocyanate group-containing carbonate resins, and urethane group-containing carbonate resins. Specific examples of polycarbonate resins include "FPC0220" manufactured by Mitsubishi Gas Chemical Company, Inc., "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. Specific examples of polyether ether ketone resins include "Sumiploy K" manufactured by Sumitomo Chemical Co., Ltd. Examples of polyester resins include polyethylene terephthalate resins.

[0096] The weight-average molecular weight of the (c) thermoplastic resin is preferably 8,000 or more, more preferably 10,000 or more, even more preferably 20,000 or more, and preferably 100,000 or less, more preferably 70,000 or less, even more preferably 60,000 or less. The weight-average molecular weight of the resin can be measured by gel permeation chromatography (GPC) as a polystyrene-equivalent value.

[0097] The content of the (c) thermoplastic resin in the resin composition prepared in step (A) is not particularly limited, but from the viewpoint of significantly obtaining the effects of the present invention, when the non-volatile components in the resin composition are taken as 100% by mass, the content is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and particularly preferably 25% by mass or less, and the lower limit is, for example, 0% by mass or more, 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and particularly preferably 1% by mass or more.

[0098] ((d) Inorganic filler) The resin composition prepared in step (A) may contain (d) an inorganic filler as an optional component.

[0099] (d) Inorganic compounds are used as the inorganic filler material. Examples of (d) 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. (d) Inorganic fillers may be used alone or in combination.

[0100] (d) Examples of commercially available inorganic fillers include "UFP-30" manufactured by Denka Company Limited; "SP60-05" and "SP507-05" manufactured by Nippon Steel & Sumikin Materials Co., Ltd.; "YC100C," "YA050C," "YA050C-MJE," and "YA010C" manufactured by Admatechs Co., Ltd.; "Silfill NSS-3N," "Silfill NSS-4N," and "Silfill NSS-5N" manufactured by Tokuyama Corporation; and "SC2500SQ," "SO-C4," "SO-C2," and "SO-C1" manufactured by Admatechs Co., Ltd.

[0101] (d) The specific surface area of ​​the inorganic filler is preferably 1 m 2 / g or more, more preferably 2m 2 / g or more, particularly preferably 3m 2 / g or more. There is no particular upper limit, but it is preferably 60m 2 / g or less, 50m 2 / g or less or 40m 2 The specific surface area is determined 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.) according to the BET method, and then calculating the specific surface area using the BET multipoint method.

[0102] (d) From the viewpoint of significantly achieving the desired effects of the present invention, the average particle size of the inorganic filler is preferably 0.01 μm or more, more preferably 0.05 μm or more, particularly preferably 0.1 μm or more, and is preferably 5 μm or less, more preferably 2 μm or less, and even more preferably 1 μm or less.

[0103] The average particle size of the (d) inorganic filler can be measured by a laser diffraction / scattering method based on Mie scattering theory. Specifically, a volumetric particle size distribution of the (d) inorganic filler is created 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 (d) inorganic filler and 10 g of methyl ethyl ketone into a vial and dispersing the mixture ultrasonically for 10 minutes. The measurement sample is measured using a laser diffraction particle size distribution analyzer with blue and red wavelength light sources using a flow cell system to measure the volumetric particle size distribution of the (d) inorganic filler, and the average particle size can be calculated as the median diameter from the particle size distribution obtained. Examples of laser diffraction particle size distribution analyzers include the LA-960 manufactured by Horiba, Ltd.

[0104] (d) The inorganic filler is preferably treated with a surface treatment agent from the viewpoint of improving moisture resistance and dispersibility. Examples of the surface treatment agent include vinylsilane coupling agents, (meth)acrylic coupling agents, fluorine-containing silane coupling agents, aminosilane coupling agents, epoxysilane coupling agents, mercaptosilane coupling agents, silane coupling agents, alkoxysilanes, organosilazane compounds, and titanate coupling agents. Among these, vinylsilane coupling agents, (meth)acrylic coupling agents, and aminosilane coupling agents are preferred from the viewpoint of achieving the effects of the present invention significantly. Furthermore, the surface treatment agent may be used alone or in any combination of two or more.

[0105] Commercially available surface treatment agents include, for example, Shin-Etsu Chemical Co., Ltd.'s "KBM1003" (vinyltriethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM503" (3-methacryloxypropyltriethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM403" (3-glycidoxypropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM803" (3-mercaptopropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBE903" (3-aminopropyltriethoxysilane), and Shin-Etsu Chemical Co., Ltd.'s "KBM1003" (vinyltriethoxysilane). Examples of suitable silane coupling agents include "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "SZ-31" (hexamethyldisilazane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM103" (phenyltrimethoxysilane), "KBM-4803" (long-chain epoxy-type silane coupling agent) manufactured by Shin-Etsu Chemical Co., Ltd., and "KBM-7103" (3,3,3-trifluoropropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd.

[0106] The degree of surface treatment with the surface treatment agent preferably falls within a predetermined range from the viewpoint of improving the dispersibility of the (d) inorganic filler. Specifically, 100 parts by mass of the (d) inorganic filler is preferably surface-treated with 0.2 to 5 parts by mass of the surface treatment agent, more preferably 0.2 to 3 parts by mass, and even more preferably 0.3 to 2 parts by mass.

[0107] The degree of surface treatment with the surface treatment agent can be evaluated by the amount of carbon per unit surface area of ​​(d) the inorganic filler. (d) The amount of carbon per unit surface area of ​​the inorganic filler is set to 0.02 mg / m from the viewpoint of improving the dispersibility of the inorganic filler. 2 More than 0.1 mg / m is preferable. 2 More preferably, 0.2 mg / m or more 2 On the other hand, from the viewpoint of suppressing an increase in the melt viscosity of the resin composition and the melt viscosity in the form of a sheet, it is more preferable that the content be 1 mg / m 2 Preferably less than 0.8 mg / m 2 Less than 0.5 mg / m is more preferable. 2 The following is even more preferred:

[0108] The carbon amount per unit surface area of ​​the (d) inorganic filler can be measured after the surface-treated (d) 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 (d) 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 (d) inorganic filler can be measured using a carbon analyzer. An "EMIA-320V" manufactured by Horiba, Ltd., or the like can be used as the carbon analyzer.

[0109] The content of the inorganic filler (d) in the resin composition prepared in step (A) is not particularly limited, but from the viewpoint of further suppressing cracking in the cured layer and further improving sandblasting processability, when the non-volatile components in the resin composition are taken as 100% by mass, it is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, and particularly preferably 60% by mass or more or 70% by mass or more. Furthermore, the upper limit is not particularly limited, but from the viewpoint of further suppressing warping of the cured layer, it is preferably 85% by mass or less, more preferably 80% by mass or less, even more preferably 77% by mass or less, and particularly preferably 75% by mass or less.

[0110] ((e) Organic filler) The resin composition prepared in step (A) may contain (e) an organic filler as an optional component.

[0111] As the (e) organic filler, any organic filler that can be used when forming an insulating layer of a printed wiring board can be used. The (e) organic filler may be used alone or in any combination of two or more types in any ratio.

[0112] (e) Examples of organic fillers include rubber particles, polyamide particles, silicone particles, etc. Commercially available rubber particles may be used, such as "EXL2655" manufactured by Dow Chemical Japan and "AC3816N" manufactured by Aica Kogyo Co., Ltd.

[0113] From the viewpoint of excellent dispersibility in the resin composition, the average particle size of the particles of (e) the organic filler is preferably 5 μm or less, more preferably 4 μm or less, and even more preferably 3 μm or less. The lower limit of the average particle size of the (e) organic filler is not particularly limited, but is preferably 0.05 μm or more, more preferably 0.08 μm or more, and particularly preferably 0.10 μm or more.

[0114] The content of the (e) organic filler in the resin composition prepared in step (A) is not particularly limited, but from the viewpoint of significantly obtaining the effects of the present invention, when the non-volatile components in the resin composition are taken as 100% by mass, the content is preferably 5% by mass or less, more preferably 2% by mass or less, even more preferably 1% by mass or less, and particularly preferably 0.5% by mass or less, and the lower limit thereof may be, for example, 0% by mass or more, 0.001% by mass or more, 0.01% by mass or more, 0.1% by mass or more, etc.

[0115] (f) Flame retardants The resin composition prepared in step (A) may contain (f) a flame retardant as an optional component.

[0116] Examples of (f) flame retardants include phosphorus-based flame retardants such as phosphazene compounds, phosphates, phosphoric acid esters, polyphosphates, phosphinates, phosphinic acid esters, phosphonates, and phosphonic acid esters; nitrogen-based flame retardants such as aliphatic amine compounds, aromatic amine compounds, nitrogen-containing heterocyclic compounds, and urea compounds; inorganic flame retardants such as metal hydroxides (e.g., magnesium hydroxide and aluminum hydroxide) and antimony compounds (e.g., antimony trioxide, antimony pentoxide, and sodium antimonate); and halogen-based flame retardants such as hexabromobenzene, chlorinated paraffin, brominated polycarbonate resin, brominated epoxy resin, brominated phenoxy resin, brominated polyphenylene ether resin, brominated polystyrene resin, and brominated benzyl polyacrylate resin. Among these, phosphorus-based flame retardants are preferred. (f) Flame retardants may be used alone or in combination.

[0117] Examples of the phosphazene compound include phenoxycyclophosphazene compounds such as hexaphenoxycyclotriphosphazene, tris(4-hydroxyphenoxy)triphenoxycyclotriphosphazene, hexakis(4-hydroxyphenoxy)cyclotriphosphazene, tris(4-methylphenoxy)triphenoxycyclotriphosphazene, tris(4-cyanophenoxy)triphenoxycyclotriphosphazene, hexakis(4-aminophenoxy)cyclotriphosphazene, tris[4-(2-glycidyloxyethyl)phenoxy]triphenoxycyclotriphosphazene, and octaphenoxycyclotetraphosphazene.

[0118] Examples of phosphates include ammonium phosphate, melamine phosphate, and piperazine phosphate.

[0119] Examples of phosphate esters include non-halogenated aliphatic phosphate esters such as trimethyl phosphate, triethyl phosphate, tributyl phosphate, and trioctyl phosphate; non-halogenated aromatic phosphate esters such as triphenyl phosphate, cresyl diphenyl phosphate, dicresyl phenyl phosphate, tricresyl phosphate, tris(2,6-dimethylphenyl)phosphate, tris(4-isopropylphenyl)phosphate, tris(4-tert-butylphenyl)phosphate, bis(4-tert-butylphenyl)phenyl phosphate, hydroxyphenyl diphenyl phosphate, octyl diphenyl phosphate, and 2-ethylhexyl diphenyl phosphate; and halogenated aliphatic phosphate esters such as tris(1-chloro-2-propyl)phosphate, tris(1,3-dichloro-2-propyl)phosphate, and tris[3-bromo-2,2-bis(bromomethyl)propyl]phosphate.

[0120] Examples of polyphosphates include ammonium polyphosphate and melamine polyphosphate.

[0121] Examples of phosphinates include dialkylphosphinates such as aluminum tris(diethylphosphinate), zinc bis(diethylphosphinate), aluminum tris(methylethylphosphinate), zinc bis(methylethylphosphinate), and titanium tetrakis(diethylphosphinate); and diarylphosphinates such as zinc bis(diphenylphosphinate) and titanium tetrakis(diphenylphosphinate).

[0122] Examples of phosphinic acid esters include dialkylphosphinic acid esters such as methyl dimethylphosphinate, ethyl dimethylphosphinate, ethyl diethylphosphinate, vinyl diethylphosphinate, and phenyl diethylphosphinate; acyclic diarylphosphinic acid esters such as phenyl diphenylphosphinate, methyl diphenylphosphinate, and ethyl diphenylphosphinate; 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphinate; 10-(1,4-dihydroxy-2-naphthyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-(2,5-dihydroxybiphenyl-4-yl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-[2,4-di(glycidyloxy)phenyl]-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, etc. Cyclic diarylphosphinic acid esters of the above; cyclic monoarylphosphinic acid esters such as 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; 9,10-dihydro-10-benzyl-9-oxa-10-phosphaphenanthrene-10-oxide, 10-[2,3-bis(2-hydroxyethoxycarbonyl)propyl]-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, or polyether polycondensates thereof cyclic arylalkylphosphinic acid esters such as 10-(2-cyanoethyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-[2-(3,4-epoxycyclohexyl)ethyl]-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and 10-(3-glycidyloxypropyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0123] Examples of phosphonates include zinc methanephosphonate, zinc ethylphosphonate, zinc butylphosphonate, and zinc phenylphosphonate.

[0124] Examples of phosphonate esters include aliphatic phosphonates such as diphenyl methylphosphonate, dibutyl butylphosphonate, diethyl ethylphosphonate, diethyl (methoxymethyl)phosphonate, and diethyl vinylphosphonate; and aromatic phosphonates such as diethyl phenylphosphonate, divinyl phenylphosphonate, and diallyl phenylphosphonate.

[0125] The (f) flame retardant preferably contains a phosphorus-based flame retardant, more preferably a phenolic hydroxyl group-containing phosphorus-based flame retardant, and particularly preferably a phenolic hydroxyl group-containing phosphinic acid ester. The phenolic hydroxyl group equivalent of the phenolic hydroxyl group-containing phosphorus-based flame retardant is not particularly limited, but is preferably 80 g / eq. to 1,000 g / eq., more preferably 100 g / eq. to 500 g / eq., even more preferably 110 g / eq. to 300 g / eq., even more preferably 120 g / eq. to 200 g / eq., and preferably 130 g / eq. to 180 g / eq. The phenolic hydroxyl group equivalent is the mass of the phosphorus-based flame retardant per equivalent of phenolic hydroxyl group. The phenolic hydroxyl group-containing phosphorus-based flame retardant, like the (C-1) epoxy curing agent, has the function of curing the (B) epoxy resin.

[0126] (f) Examples of commercially available flame retardants include "SPH-100," "SPS-100," "SPB-100," and "SPE-100" (phosphazene compounds) manufactured by Otsuka Chemical Co., Ltd.; "FP-100," "FP-110," "FP-300," and "FP-400" (phosphazene compounds) manufactured by Fushimi Pharmaceutical Co., Ltd.; "HCA-NQ," "HCA-HQ," "HCA-HQ-HST," and "HCA-HQ-HS" (phosphinic acid esters (containing phenolic hydroxyl groups)) manufactured by Sankosha; and "PX-200," "PX-201," "PX-202," "CR-733S," "CR-741," and "CR-747" (phosphate esters) manufactured by Daihachi Chemical Industry Co., Ltd.

[0127] The content of the flame retardant (f) in the resin composition prepared in step (A) is not particularly limited, but from the viewpoint of significantly obtaining the effects of the present invention, when the non-volatile components in the resin composition are taken as 100% by mass, the content is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 7% by mass or less, and particularly preferably 5% by mass or less, and the lower limit thereof may be, for example, 0% by mass or more, 0.001% by mass or more, 0.01% by mass or more, 0.1% by mass or more, etc.

[0128] ((g) Other additives) The resin composition prepared in step (A) may further contain optional additives as non-volatile components. Examples of such additives include organometallic compounds such as organocopper compounds, organozinc compounds, and organocobalt compounds; colorants such as phthalocyanine blue, phthalocyanine green, iodine green, diazo yellow, crystal violet, titanium oxide, and carbon black; polymerization inhibitors such as hydroquinone, catechol, pyrogallol, and phenothiazine; leveling agents such as silicone-based leveling agents and acrylic polymer-based leveling agents; thickeners such as bentone and montmorillonite; antifoaming agents such as silicone-based antifoaming agents, acrylic-based antifoaming agents, fluorine-based antifoaming agents, and vinyl resin-based antifoaming agents; ultraviolet absorbers such as benzotriazole-based ultraviolet absorbers; and adhesive agents such as urea silanes. Examples of the (g) other additives include adhesion improvers; adhesion promoters such as triazole-based adhesion promoters, tetrazole-based adhesion promoters, and triazine-based adhesion promoters; antioxidants such as hindered phenol-based antioxidants and hindered amine-based antioxidants; fluorescent brighteners such as stilbene derivatives; surfactants such as fluorine-based surfactants and silicone-based surfactants; dispersants such as phosphate ester-based dispersants, polyoxyalkylene-based dispersants, acetylene-based dispersants, silicone-based dispersants, anionic dispersants, and cationic dispersants; 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 anhydride-based stabilizers. (g) Other additives may be used alone or in combination of two or more in any ratio. The content of (g) other additives can be determined appropriately by those skilled in the art.

[0129] ((h) Organic solvents) The resin composition prepared in step (A) may further contain an arbitrary organic solvent as a volatile component in addition to the nonvolatile components described above. (h) The organic solvent may be any known organic solvent, and the type is not particularly limited. (h) The organic solvent may be, for example, a ketone-based solvent such as acetone, methyl ethyl ketone, methyl isobutyl ketone, or cyclohexanone; an ester-based solvent such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, isoamyl acetate, methyl propionate, ethyl propionate, or γ-butyrolactone; an ether-based solvent such as tetrahydropyran, tetrahydrofuran, 1,4-dioxane, diethyl ether, diisopropyl ether, dibutyl ether, or diphenyl ether; an alcohol-based solvent such as methanol, ethanol, propanol, butanol, or ethylene glycol; or a 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl diglycol acetate, γ-butyrolactone, or methyl methoxypropionate. Examples of suitable organic solvents include ether ester solvents such as methyl lactate, ethyl lactate, and methyl 2-hydroxyisobutyrate; ether alcohol solvents such as 2-methoxypropanol, 2-methoxyethanol, 2-ethoxyethanol, propylene glycol monomethyl ether, and diethylene glycol monobutyl ether (butyl carbitol); amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; sulfoxide solvents such as dimethyl sulfoxide; nitrile solvents such as acetonitrile and propionitrile; aliphatic hydrocarbon solvents such as hexane, cyclopentane, cyclohexane, and methylcyclohexane; and aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, and trimethylbenzene. (h) Organic solvents may be used singly or in combination of two or more in any ratio.

[0130] The amount of (h) organic solvent contained in the resin composition prepared in step (A) is not particularly limited, but when all components in the resin composition are taken as 100% by mass, it can be, for example, 60% by mass or less, 40% by mass or less, 30% by mass or less, 20% by mass or less, 15% by mass or less, 10% by mass or less, 5% by mass or less, etc.

[0131] <(B) Resin sheet preparation process> In step (B), a resin sheet is prepared that includes a support and a resin composition layer provided on the support. The resin composition layer is formed from the resin composition obtained in step (A).

[0132] 1 is a cross-sectional view schematically showing an example of a circuit board 10 used in step (C) and a resin sheet 20 prepared in step (B). The circuit board 10 will be described in step (C). In the resin sheet 20 prepared in step (B), a resin composition layer 22 is provided on a support 21, as shown in an example in FIG.

[0133] As a method for forming the resin composition layer 22, for example, the liquid resin composition obtained in step (A) is used as is, or a resin composition is prepared by dissolving the resin composition in an organic solvent, and this is applied onto the support 21 using a die coater or the like, and then dried to form the resin composition layer 22.

[0134] The organic solvent may be the same as the organic solvent described as a component of the resin composition. The organic solvent may be used alone or in combination of two or more.

[0135] Drying may be performed by known methods such as heating or hot air blowing. Drying conditions are not particularly limited, but drying is performed so that the content of organic solvent in resin composition layer 22 becomes 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 composition, for example, when a resin composition containing 30% by mass to 60% by mass of organic solvent is used, resin composition layer 22 can be formed on support 21 by drying at 50°C to 150°C for 3 to 10 minutes.

[0136] Thickness T of the resin composition layer 22 after drying 22 From the viewpoint of easily forming via holes, the thickness is preferably 25 μm or less, more preferably 22 μm or less, and particularly preferably 20 μm or less, and from the viewpoint of ensuring the required interlayer insulation, the thickness is preferably 3 μm or more, more preferably 5 μm or more, even more preferably 8 μm or more, and particularly preferably 10 μm or more.

[0137] Examples of the support 21 include films made of plastic materials, metal foils, and release paper, with films made of plastic materials and metal foils being preferred.

[0138] When a film made of a plastic material is used as the support 21, examples of the plastic material include polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as "PET") and polyethylene naphthalate (hereinafter sometimes abbreviated as "PEN"), polycarbonate (hereinafter sometimes abbreviated as "PC"), acrylics such as polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, polyimide, etc. Among these, polyethylene terephthalate and polyethylene naphthalate are preferred, with inexpensive polyethylene terephthalate being particularly preferred.

[0139] When a metal foil is used as the support 21, examples of the metal foil include copper foil and aluminum foil, with copper foil being preferred. The copper foil may be a foil made of a single metal, copper, or a foil made of an alloy of copper and another metal (for example, tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.).

[0140] The surface of the support 21 that is to be bonded to the resin composition layer 22 may be subjected to a matte treatment, a corona treatment, or an antistatic treatment.

[0141] Alternatively, the support 21 may be a support with a release layer, which has a release layer on the surface that bonds with the resin composition layer 22. 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. Commercially available products may be used as the support with a release layer, including, for example, "PET501010," "SK-1," "AL-5," and "AL-7" manufactured by Lintec Corporation; "Lumirror T60" manufactured by Toray Industries, Inc.; "Purex" manufactured by Teijin Limited; and "Uni-Peel" manufactured by Unitika Limited, which are PET films having a release layer primarily composed of an alkyd resin-based release agent.

[0142] Thickness T of the support 21 21 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 with a release layer is used, it is preferable that the thickness of the entire support with a release layer is in the above range.

[0143] The resin sheet 20 may further include other layers as necessary. Examples of other layers include a protective film (not shown) conforming to the support and provided on the surface of the resin composition layer 22 that is not bonded to the support 21 (i.e., the surface opposite to the support). The thickness of the protective film (not shown) is not particularly limited, but is, for example, 1 μm to 40 μm. By laminating the protective film (not shown), it is possible to prevent the adhesion of dust and the like to the surface of the resin composition layer 22 and prevent scratches.

[0144] The resin sheet 20 can be stored in a rolled state. If the resin sheet 20 has a protective film, it can be used by peeling off the protective film.

[0145] <(C) Resin Sheet Laminate Preparation Process> In step (C), the resin sheet 20 prepared in step (B) is laminated on the circuit board 10 so that the resin composition layer 22 of the resin sheet 20 is bonded to the circuit board 10, thereby preparing a resin sheet laminate C. In the following description, the intermediate product having the cured layer before the first via holes and the second via holes are formed may be referred to as a "laminate."

[0146] As shown in FIG. 1, the circuit board 10 includes a support substrate 11 and a conductor layer 12 provided on a portion of the support substrate 11.

[0147] The conductive material used for the conductor layer 12 is not particularly limited. In a preferred embodiment, the conductor layer 12 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 conductor layer 12 may be a single metal layer or an alloy layer. Examples of alloy layers include layers formed from an alloy of two or more metals selected from the above group (e.g., nickel-chromium alloy, copper-nickel alloy, and copper-titanium alloy). Among these, from the viewpoints of versatility, cost, ease of patterning, etc., in the formation of the conductor layer 12, a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of a nickel-chromium alloy, copper-nickel alloy, or copper-titanium alloy is preferred. A single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of a nickel-chromium alloy, is more preferred, and a single metal layer of copper is even more preferred.

[0148] Conductor layer 12 may have a single layer structure or a multi-layer structure in which two or more single metal layers or alloy layers made of different types of metals or alloys are laminated. When conductor layer 12 has a multi-layer structure, the layer in contact with the insulating layer of support substrate 11 is preferably a single metal layer of chromium, zinc, or titanium, or an alloy layer of a nickel-chromium alloy.

[0149] Thickness T of the conductor layer 12 12Although it depends on the design of the circuit board 10, the thickness T of the conductor layer 12 is usually 35 μm or less, preferably 30 μm or less, and more preferably 25 μm or less. 12 The lower limit of is not particularly limited, but is usually 3 μm or more, preferably 5 μm or more.

[0150] Fig. 2 is a cross-sectional view schematically showing an example of the resin sheet laminate C prepared in step (C). In the resin sheet laminate C prepared in step (C), as shown in Fig. 2, a resin sheet 20 is laminated on a circuit board 10 such that a resin composition layer 22 covers a conductor layer 12.

[0151] If the resin sheet 20 has a protective film, the protective film (not shown) is peeled off before the resin sheet 20 is laminated on the circuit board 10.

[0152] The resin sheet 20 can be laminated onto the circuit board 10, for example, by thermocompression bonding the resin sheet 20 to the circuit board 10 from the support 21 side of the resin sheet 20. Examples of a member for thermocompression bonding the resin sheet 20 to the circuit board 10 (hereinafter also referred to as a "thermocompression bonding member") include a heated metal plate (such as a SUS plate) or a metal roll (SUS roll). Note that rather than pressing the thermocompression bonding member directly onto the resin sheet 20, it is preferable to press it via an elastic material such as heat-resistant rubber so that the resin sheet 20 can sufficiently conform to the surface irregularities of the circuit board 10.

[0153] The resin sheet 20 may be laminated onto the circuit board 10 by a vacuum lamination method. In the vacuum lamination method, the thermocompression temperature is preferably in the range of 60°C to 160°C, more preferably 80°C to 140°C, the thermocompression pressure is preferably in the range of 0.098MPa to 1.77MPa, more preferably 0.29MPa to 1.47MPa, and the thermocompression time is preferably in the range of 20 seconds to 400 seconds, more preferably 30 seconds to 300 seconds. The resin sheet 20 is laminated onto the circuit board 10 under reduced pressure conditions, preferably a pressure of 26.7 hPa or less.

[0154] The resin sheet 20 can be laminated onto the circuit board 10 using a commercially available vacuum laminator. Examples of commercially available vacuum laminators include a vacuum pressure laminator manufactured by Meiki Seisakusho Co., Ltd., a vacuum applicator manufactured by Nikko Materials Co., Ltd., and a batch-type vacuum pressure laminator.

[0155] After laminating the resin sheet 20 on the circuit board 10, the laminated resin sheet 20 may be smoothed under normal pressure (atmospheric pressure), for example, by pressing a thermocompression member from the support 21 side. The pressing conditions for the smoothing treatment may be the same as the thermocompression conditions for lamination described above. The smoothing treatment may be performed using a commercially available laminator. Note that lamination and smoothing treatment may be performed consecutively using the commercially available vacuum laminator described above.

[0156] The thickness T of the resin composition layer 22 after laminating the resin sheet 20 on the circuit board 10 22 From the viewpoint of easily forming via holes, the thickness T' is preferably 25 μm or less, more preferably 22 μm or less, and particularly preferably 20 μm or less, and from the viewpoint of ensuring the required interlayer insulation, it may be preferably 3 μm or more, more preferably 5 μm or more, even more preferably 8 μm or more, and particularly preferably 10 μm or more. 22 ' is the thickness from the surface of the resin composition layer 22 that contacts the conductor layer 12 of the circuit board 10 to the surface that contacts the support 21 on the opposite side to the side that contacts the circuit board 10.

[0157] <(D) Hardened layer formation process> In step (D), the resin composition layer 21 of the resin sheet laminate C prepared in step (C) is thermally cured to form a cured layer (insulating layer) made of a cured product of the resin composition.

[0158] Fig. 3 is a cross-sectional view schematically illustrating an example of a laminate D after the formation of a cured layer prepared in step (D). In the laminate D after the formation of a cured layer prepared in step (D), as shown in Fig. 3, a cured layer 30 formed by thermally curing a resin composition layer 22 is laminated on the circuit board 10 so as to cover the conductor layer 12, and a support 21 is present on the surface of the cured layer 30 opposite to the side that contacts the circuit board 10.

[0159] The thermal curing conditions for the resin composition layer 22 may vary depending on the type of resin composition, etc. In one example, the curing temperature may be preferably 120°C to 240°C, more preferably 130°C to 220°C, and even more preferably 150°C to 210°C. The curing time may be preferably 5 minutes to 120 minutes, more preferably 10 minutes to 100 minutes, and even more preferably 15 minutes to 100 minutes.

[0160] Before thermally curing the resin composition layer 22, the resin composition layer 22 may be preheated at a temperature lower than the curing temperature. For example, before thermally curing the resin composition layer 22, the resin composition layer 22 may be preheated at a temperature of 50°C or higher and lower than 120°C (preferably 60°C or higher and 115°C or lower, more preferably 70°C or higher and 110°C or lower) for 5 minutes or longer (preferably 5 to 150 minutes, more preferably 15 to 120 minutes, and even more preferably 15 to 100 minutes).

[0161] Thickness T of the hardened layer 30 30 From the viewpoint of easily forming via holes, the thickness T of the cured layer 30 is 25 μm or less, preferably 22 μm or less, more preferably 20 μm or less, and from the viewpoint of ensuring the required interlayer insulation, it is preferably 3 μm or more, more preferably 5 μm or more, even more preferably 8 μm or more, and particularly preferably 10 μm or more. 30 is the thickness from the surface of the cured layer 30 that contacts the conductor layer 12 of the circuit board 10 to the surface that contacts the support 21 on the opposite side to the side that contacts the circuit board 10.

[0162] The elastic modulus of the hardened layer 30 at 25°C is 5 GPa or more, and from the viewpoint of further improving sandblasting processability, it is preferably 8 GPa or more, more preferably 10 GPa or more. If the elastic modulus is below 5 GPa, it may be difficult to form the first via hole by sandblasting. The upper limit of the elastic modulus of the hardened layer 30 at 25°C is 15 GPa or less. If the elastic modulus exceeds 15 GPa, warping of the hardened layer 30 tends to increase. The elastic modulus of the hardened layer 30 at 25°C can be measured by the method described in Test Example 1 below.

[0163] From the viewpoint of further suppressing the occurrence of cracks in the hardened layer, the linear thermal expansion coefficient of the hardened layer 30 is preferably 50 ppm / °C or less, more preferably 40 ppm / °C or less. The lower limit of the linear thermal expansion coefficient of the hardened layer 30 can be, for example, 10 ppm / °C or more, 15 ppm / °C or more, or 17 ppm / °C or more. The linear thermal expansion coefficient of the hardened layer 30 can be measured by the method described in Test Example 2 below.

[0164] <(E) Support Removal Step> In step (E), the support 21 is removed from the laminate D after the formation of the cured layer obtained in step (D). Although the method of thermally curing the resin composition layer 22 without removing the support 21 has been described so far, the support 21 may be removed after laminating the resin sheet 20 in step (C) and before thermally curing the resin composition layer 22 in step (D).

[0165] Fig. 4 is a cross-sectional view schematically illustrating an example of the laminate E prepared in step (E) after the support body is removed. In the laminate E prepared in step (E) after the support body is removed, as shown in Fig. 4, the surface of the cured layer 30 opposite to the side that contacts the circuit board 10 is exposed due to the removal of the support body 21.

[0166] The method for removing the support 21 is not particularly limited.

[0167] <(F) First Via Hole Formation Process> In step (F), a sandblasting process is performed on the hardened layer 30 (specific position in the hardened layer 30 where the first via hole 70 is to be formed) of the laminate E after removing the support prepared in step (E), and the first via hole 70 is formed in the hardened layer 30.

[0168] The first via hole 70 has a first opening 71 on the sandblasted side of the hardened layer 30 opposite to the side in contact with the circuit board 10, and is formed so as to penetrate the hardened layer 30 from the first opening 71 and reach the surface of the conductor layer 12 of the circuit board 10. Typically, the first via hole 70 can be formed as a tapered hole.

[0169] In sandblasting, abrasive grains are typically ejected from a nozzle and collided with specific positions on the surface of the hardened layer 30 opposite the side that contacts the circuit board 10. Typically, the abrasive grains are ejected using air at an appropriate pressure. The hardened layer 30 is scraped by the impact of the abrasive grains, thereby forming a first via hole 70 having a first opening 71 in the hardened layer 30. The abrasive grains may be ejected without containing any liquid (dry blasting) or in the form of a slurry containing a liquid (wet blasting).

[0170] The diameter of the first opening 71 in the first via hole 70 formed in step (F) is 50 μm or more. From the viewpoint of ease of processing by sandblasting, it is preferably 70 μm or more, and more preferably 90 μm or more. It is difficult to form a via hole having an opening with a diameter of less than 50 μm by sandblasting. The upper limit of the diameter of the first opening 71 is not particularly limited, but may be, for example, 10,000 μm or less, 5,000 μm or less, 1,000 μm or less, or 500 μm or less. The shape of the first opening 71 is not particularly limited, and may be a circle, a substantially rectangular shape (including a substantially square), or the like, and the diameter of the first opening 71 refers to its shortest diameter (diameter). Unless otherwise specified, the shape of the first opening 71 refers to the shape as viewed in the thickness direction of the laminate. The first via hole 70 usually has a tapered shape in which the diameter of the bottom contacting the surface of the conductor layer 12 is smaller than the diameter of the first opening 71.

[0171] The minimum pitch of the first via holes 70 can be set narrower because the insulation reliability of the cured product is higher than that of conventional products, and is preferably 100 μm or less, more preferably 50 μm or less, even more preferably 30 μm or less, still more preferably 10 μm or less, and particularly preferably 5 μm or less. The minimum pitch of the first via holes 70 is the shortest distance from the center (center of gravity) of a first opening 71 to the center (center of gravity) of the nearest other first opening 71 on the same surface of the cured layer 30.

[0172] A cured layer made of a photosensitive resin composition is generally flexible and therefore difficult to accurately grind by the impact of abrasive grains, whereas the cured layer 30 formed by thermally curing the resin composition obtained in step (A) has an elastic modulus of 5 GPa or more and 15 GPa or less, and therefore can be smoothly ground by the impact of abrasive grains. Therefore, the first via hole 70 can be formed with high precision by sandblasting, and excellent processability can be achieved.

[0173] The sandblasting process is usually performed with a sandblasting mask placed on the hardened layer 30 in order to selectively form the first via holes 70 having the first openings 71 at specific positions.

[0174] When a sandblasting mask is used in the sandblasting process, in one embodiment, step (F) may include step (F1) of placing a sandblasting mask on the hardened layer 30, and step (F2) of spraying abrasive grains toward the hardened layer 30 through a mask opening where the sandblasting mask is not placed to form a first via hole 70.

[0175] In step (F1), a sandblasting mask is placed on the surface of the hardened layer 30 opposite the side that contacts the circuit board 10, so that a mask opening is formed at a specific position where the first via hole 70 is to be formed. After the sandblasting mask is placed, abrasive grains are sprayed from a nozzle toward the hardened layer 30. At the positions of the mask openings where the sandblasting mask is not present, the abrasive grains directly collide with the hardened layer 30, scraping the hardened layer 30. On the other hand, at positions other than the mask openings where the sandblasting mask is present, the abrasive grains are blocked by the sandblasting mask, so the hardened layer 30 is not scraped. Thus, the first via hole 70 having the first opening 71 can be selectively formed at the positions of the mask openings that are not covered by the sandblasting mask.

[0176] To form the sandblasting mask, it is preferable to use a resist film that allows precise control of the shape and size of the mask openings.

[0177] When a resist film is used to form a sandblasting mask, the step (F1) of placing the sandblasting mask on the cured layer 30 may, in one embodiment, include the steps of: (F1a) laminating a resist film on the cured layer 30 of the laminate E after the support has been removed; (F1b) placing a photomask at a position where a mask opening should be formed on the resist film laminated in step (F1a); and (F1c) performing an exposure process and a development process on the resist film after the photomask is placed in step (F1b) to form the mask opening and the sandblasting mask.

[0178] Fig. 5 is a cross-sectional view schematically showing an example of a laminate F1a prepared in step (F1a) after lamination of the resist film 40. In the laminate F1a prepared in step (F1a) after lamination of the resist film 40, as shown in Fig. 5 as an example, the resist film 40 is laminated on the surface of the curing layer 30 opposite to the side that contacts the conductor layer 12 of the circuit board 10. The lamination conditions for the curing layer 30 and the resist film 40 are not particularly limited and may be the same as the lamination conditions for the circuit board and resin sheet described above, for example.

[0179] The resist film 40 may be one that forms a sandblasting mask 60 by exposure and development. The sandblasting mask 60 formed from the resist film 40 may be resistant to sandblasting. The resist film 40 may be, for example, a photosensitive film formed from a photoresist composition. Examples of such resist films 40 include dry films containing resins such as novolac resins and acrylic resins.

[0180] Thickness T of the resist film 40 40 From the viewpoint of improving the processability of via holes, the thickness is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more, and is preferably 100 μm or less, more preferably 70 μm or less, and even more preferably 50 μm or less.

[0181] Fig. 6 is a cross-sectional view schematically illustrating an example of a laminate F1b prepared in step (F1b) after the photomask 50 is provided. In the laminate F1b prepared in step (F1b) after the photomask 50 is provided, the photomask 50 is provided at a position where the cured layer 30 should be opened (a position where the first opening 60 described below should be formed) on the surface of the resist film 40 opposite to the side that contacts the cured layer 30, as shown in Fig. 6 as an example.

[0182] In the exposure treatment of step (F1c), active energy rays (not shown) are typically irradiated onto the surface of the resist film 40 (exposed portion) where the photomask 50 is not installed in the laminate F1b after the photomask has been installed. The exposed portion of the resist film 40 irradiated with the active energy rays by the exposure treatment is photocured. The portion of the surface of the resist film 40 where the photomask 50 is installed (non-exposed portion) is blocked by the active energy rays, so the active energy rays typically cannot reach it and are not photocured.

[0183] Examples of active energy rays include ultraviolet rays, visible light rays, electron beams, and X-rays, with ultraviolet rays being preferred. The dose and duration of ultraviolet rays can be appropriately set depending on the material and thickness of the resist film 40. As an exposure method, instead of the contact exposure method described above with reference to FIG. 6 in which a photomask 50 is brought into close contact with the resist film 40 and exposed, a non-contact exposure method in which a photomask 50 is not brought into close contact with the resist film 40 and exposed using parallel light may be used.

[0184] After the exposure process, the resist film 40 is subjected to a development process to remove the photomask 50 and the unexposed portions of the resist film 40. The development process may be either wet development or dry development. Examples of the development method include a dipping method, a puddle method, a spray method, a brushing method, and a scraping method.

[0185] 7 is a cross-sectional view schematically illustrating an example of a laminate F1c after the development process prepared in step (F1c). In the laminate F1c after the development process prepared in step (F1c), as shown in an example in FIG. 7, after the development process, mask openings 61 are formed in the unexposed portions of the resist film 40 that were blocked by the photomask 50, and a sandblast mask 60 is formed on the surface of the cured layer 30 other than the mask openings 61 so as to be bonded to the cured layer 30.

[0186] As an example of the exposure process and the development process, one form has been described using FIG. 7 in which a sandblast mask 60 is formed from the exposed portion of the resist film 40 and the non-exposed portion is removed to form the mask opening 61. However, other forms are also known in which a sandblast mask 60 is formed from the non-exposed portion of the resist film 40 and the exposed portion is removed to form the mask opening 61, and such forms may be used instead.

[0187] In the step (F2), abrasive grains are sprayed onto the hardened layer 30 through the mask openings 61 to form the first via holes 70.

[0188] FIG. 8 is a cross-sectional view schematically illustrating an example of a laminate F2 prepared in step (F2) after the formation of a first via hole. In step (F2), abrasive particles collide with and selectively remove the hardened layer 30 in the portion of the hardened layer 30 exposed by the mask opening 61, which is not covered by the sandblasting mask 60. As shown in FIG. 8, a first via hole 70 is formed so as to penetrate the hardened layer 30 from the first opening 71 to the surface of the conductor layer 12 of the circuit board 10. On the other hand, in the portion of the hardened layer 30 covered by the sandblasting mask 60, the sprayed abrasive particles are blocked by the sandblasting mask 60 and do not collide with the hardened layer 30, so the hardened layer 30 is not typically removed. Typically, the first opening 71 of the first via hole 70 formed can have approximately the same planar shape as the mask opening 61. Unless otherwise specified, the planar shape refers to the shape as viewed in the thickness direction of the laminate.

[0189] The sandblasting may be either a dry blasting process in which abrasive grains are blasted, or a wet blasting process in which a slurry containing abrasive grains and a liquid is blasted.

[0190] Examples of abrasive grains include particles mainly composed of silicon oxides such as silica and glass; metals such as steel, stainless steel, zinc, and copper; ceramics such as garnet, zirconia, silicon carbide, alumina, and boron carbide; and materials such as dry ice. Among these, from the viewpoint of significantly achieving the desired effects of the present invention, silicon oxide particles and ceramic particles are preferred, and alumina particles, silicon carbide particles, and silica particles are preferred. Of the silica particles, crystalline silica particles are preferred.

[0191] Commercially available abrasive grains may be used, such as "DAW-03" manufactured by Denka Co., Ltd., "AY2-75" (alumina) manufactured by Nippon Steel Chemical & Material Co., Ltd., "GP#4000" and "SER-A06" (silicon carbide) manufactured by Shinano Electric Refining Co., Ltd., "IMSIL A-8" (crystalline silica) manufactured by Tatsumori Co., Ltd., and "Fuji Random WA" (fused alumina) manufactured by Fuji Manufacturing Co., Ltd.

[0192] From the viewpoint of improving the workability of the first via hole 70, the modified Mohs hardness of the abrasive grains used in the sandblasting treatment is preferably 5 or more, more preferably 6 or more, and particularly preferably 7 or more. The upper limit can usually be 15 or less. The modified Mohs hardness of the abrasive grains can be measured using a Mohs hardness tester.

[0193] The average particle size of the abrasive grains is preferably 0.5 μm or more, more preferably 1.0 μm or more, more preferably 2.0 μm or more, and is preferably 50 μm or less, more preferably 30 μm or less, even more preferably 20 μm or less, and particularly preferably 15 μm or less, from the viewpoint of improving the workability of the first via hole 70. The average particle size of the abrasive grains can be measured, for example, by observation with a scanning electron microscope, and in detail, this can be done by the method described in JP 2008-41932 A.

[0194] The average particle diameter of the abrasive grains is set to be equal to the thickness T 30 The thickness T of the hardened layer 30 is preferably smaller than 30 The ratio of the average particle size of the abrasive grains to the average particle size of the abrasive grains is preferably 0.01 or more, more preferably 0.02 or more, particularly preferably 0.04 or more, and is preferably 0.80 or less, more preferably 0.50 or less, particularly preferably 0.30 or less.

[0195] The pressure (processing pressure) for spraying the abrasive grains is preferably 0.05 MPa or more, more preferably 0.1 MPa or more, even more preferably 0.15 MPa or more, and is preferably 1 MPa or less, more preferably 0.8 MPa or less, even more preferably 0.5 MPa or less, from the viewpoint of improving the processability of the first via hole 70 and forming the first via hole 70 in a short time. Here, the processing pressure is the value at the surface of the hardened layer 30.

[0196] <(G) Step of forming second via hole> In step (G), a laser is irradiated (through the sandblasting mask 60 if present, or directly onto the hardened layer 30 if the sandblasting mask 60 has been removed beforehand) onto the hardened layer 30 of the laminate F2 produced in step (F) after the formation of the first via hole (specific position in the hardened layer 30 where the second via hole 80 is to be formed) to form the second via hole 80 in the hardened layer 30. Note that if the sandblasting treatment in step (F) is performed after step (G), problems such as a decrease in the reliability of electrical continuity due to abrasive grains getting into the second via hole 80 formed in step (G) may occur. Therefore, the sandblasting treatment in step (F) is usually performed before step (G).

[0197] The second via hole 80 has a second opening 81 on the side of the hardened layer 30 opposite to the side that contacts the circuit board 10, and is formed as a tapered hole that penetrates the hardened layer 30 from the second opening 81 and reaches the surface of the conductor layer 12 of the circuit board 10.

[0198] 9 is a cross-sectional view schematically illustrating an example of a printed wiring board G after the formation of the second via hole manufactured in step (G). In the printed wiring board G after the formation of the second via hole manufactured in step (G), as shown in an example in FIG. 9, a new opening overlapping the second opening 81 is formed in the sandblasting mask 60, and a tapered second via hole 80 is formed so as to penetrate the cured layer 30 from the second opening 81 to the conductor layer 12 of the circuit board 10.

[0199] The diameter of the second opening 81 in the second via hole 80 formed in step (G) is 32 μm or less. The lower limit of the diameter of the second opening 81 is not particularly limited, but may be, for example, 1 μm or more, 5 μm or more, 10 μm or more, etc. The shape of the second opening 81 is not particularly limited, but since it is formed by laser processing in one embodiment, it may be preferably circular, and the diameter of the second opening 81 means its shortest diameter (diameter). Unless otherwise specified, the shape of the second opening 81 refers to the shape as viewed in the thickness direction of the printed wiring board. The second via hole 80 usually has a tapered shape in which the diameter of the bottom part that contacts the surface of the conductor layer 12 is smaller than the diameter of the second opening 81.

[0200] The minimum pitch of the second via holes 80 can be set narrower because the insulation reliability of the cured product is higher than that of conventional products, and is preferably 100 μm or less, more preferably 50 μm or less, even more preferably 30 μm or less, still more preferably 10 μm or less, and particularly preferably 5 μm or less. The minimum pitch of the second via holes 80 is the shortest distance from the center (center of gravity) of a given second opening 81 to the center (center of gravity) of another second opening 81 that is closest to it on the same surface of the cured layer 30.

[0201] Examples of the laser used in the step (G) include a CO2 laser (carbon dioxide laser), a YAG laser, a UV-YAG laser, a YVO4 laser, a YLF laser, an excimer laser, etc. An appropriate laser light source may be used depending on the characteristics of the cured layer 30, etc.

[0202] The laser irradiation conditions in step (G) are not particularly limited as long as they can form a second via hole 80 having a small-diameter second opening 81, and may be determined appropriately depending on the type of laser light source, the type of sandblasting mask 60, the thickness of the cured layer 30, the type of resin composition used to form the cured layer 30, etc.

[0203] The following is an example of irradiation conditions when a carbon dioxide gas laser is used as the laser light source: When a carbon dioxide gas laser is used as the laser light source, laser light with a wavelength of 9.3 μm to 10.6 μm is generally used.

[0204] When a carbon dioxide laser is used in step (G), the number of laser shots varies depending on the depth of the second via hole 80 to be formed, the top diameter, the type of laser light source, the type of sandblast mask 60, and the type of resin composition used to form the cured layer 30, but is typically selected in the range of 1 to 10 shots. From the viewpoint of increasing the processing speed and improving the productivity of circuit boards, a smaller number of shots is preferable, preferably in the range of 1 to 5 shots, and more preferably in the range of 1 to 3 shots. Note that when the number of shots is 2 or more, the laser light may be irradiated in either burst mode or cycle mode.

[0205] When a carbon dioxide laser is used in step (G), the energy of the laser beam is set to preferably 0.2 mJ or more, more preferably 0.3 mJ or more, and even more preferably 0.4 mJ or more, although this depends on factors such as the number of shots, the depth of the second via hole 80, the type of laser light source, the type of sandblasting mask 60, and the type and thickness of the resin composition used to form the cured layer 30. The upper limit of the energy of the laser beam is preferably 20 mJ or less, more preferably 15 mJ or less, and even more preferably 10 mJ or less.

[0206] Next, irradiation conditions when a UV-YAG laser is used as the laser light source will be exemplified. When a UV-YAG laser is used as the laser light source, laser light with a wavelength of 0.2 μm to 0.4 μm is generally used.

[0207] When a UV-YAG laser is used in step (G), the number of laser shots varies depending on the depth of the second via hole 80 to be formed, the top diameter, the type of laser light source, the type of sandblasting mask 60, and the type of resin composition used to form the cured layer 30, but is usually selected in the range of 10 to 200 shots. From the viewpoint of increasing the processing speed and improving the productivity of circuit boards, a smaller number of shots is preferable, preferably in the range of 10 to 100 shots, and more preferably in the range of 10 to 80 shots.

[0208] When a UV-YAG laser is used in step (G), the energy of the laser light varies depending on the number of shots, the depth of the second via hole 80, the type of laser light source, the type of sandblasting mask 60, the type of resin composition used to form the cured layer 30, and other factors, but is set to preferably 0.05 W or more, more preferably 0.10 W or more, and even more preferably 0.15 W or more. The upper limit of the laser light energy is preferably 10 W or less, more preferably 5 W or less, and even more preferably 3 W or less.

[0209] The laser irradiation in step (G) may be carried out using a commercially available laser device, such as Hitachi Via Mechanics' "LC-2E21B / 1C" (carbon dioxide laser device), Mitsubishi Electric's "605GTWIII(-P)" (carbon dioxide laser device), and ESI's "MODEL5330xi" and "MODEL5335" (UV-YAG laser devices).

[0210] <(H) Sandblast mask removal process> In step (H), if the sandblasting mask 60 remains on the printed wiring board G obtained in step (G) after the formation of the second via holes, the sandblasting mask 60 is removed. Step (H) is an optional step.

[0211] The method for removing the sandblasting mask 60 in step (H) is not particularly limited, but for example, when a resist film 40 is used to form the sandblasting mask 60, the resist film 40 may be brought into contact with a removal liquid capable of dissolving the resist film 40, and then dissolved and removed. Examples of the contacting method include, but are not limited to, a dipping method, a spraying method, and a coating method.

[0212] The removal of the sandblasting mask 60 is not limited to after the laser irradiation in step (G), but may be performed after the sandblasting treatment in step (F), before the laser irradiation in step (G), after the desmearing in step (I), or before the formation of the conductor layer in step (J).

[0213] <(I) Desmearing process> In step (I), a desmear treatment is performed on the printed wiring board H after removing the sandblast mask in step (H) (the printed wiring board G after forming the second via holes obtained in step (G)).

[0214] Resin residue (smear) may be present inside (particularly at the bottom) of the second via hole 80 formed using a laser in step (G). Since such smear can cause poor electrical connection between layers, a process for removing the smear (desmear process) is carried out in step (I).

[0215] Fig. 10 is a cross-sectional view schematically showing an example of a desmeared printed wiring board I manufactured in step (I). In the desmeared printed wiring board I manufactured in step (I), as shown in Fig. 10, the sandblasting mask 60 is removed and the surface of the hardened layer 30 in which the first openings 71 and the second openings 81 are formed is exposed.

[0216] The method of the desmear treatment performed in step (I) is not particularly limited, and can be any of various known methods. The desmear treatment performed in step (I) may be, for example, a dry desmear treatment, a wet desmear treatment, or a combination thereof.

[0217] An example of the dry desmear treatment is a desmear treatment using plasma. The desmear treatment using plasma can be carried out using a commercially available plasma desmear treatment device. Among the commercially available plasma desmear treatment devices, examples suitable for use in manufacturing printed wiring boards include a microwave plasma device manufactured by Nissin Corporation and an atmospheric pressure plasma etching device manufactured by Sekisui Chemical Co., Ltd.

[0218] The dry desmearing process may also be a dry sandblasting desmearing process in which an abrasive is sprayed from a nozzle to polish the treatment target. The dry sandblasting desmearing process can be performed using a commercially available dry sandblasting desmearing device. When a water-soluble abrasive is used as the abrasive, by performing a water washing process after the dry sandblasting desmearing process, the abrasive does not remain inside the second via hole, and smears can be effectively removed.

[0219] Examples of wet desmear treatments include desmear treatments using an oxidizing agent solution, etc. When desmear treatments using an oxidizing agent solution are performed, it is preferable to perform a swelling treatment using a swelling liquid, an oxidation treatment using an oxidizing agent solution, and a neutralization treatment using a neutralizing liquid in this order.

[0220] Examples of the swelling liquid include "Swelling Dip Securigans P" and "Swelling Dip Securigans SBU" manufactured by Atotech Japan Co., Ltd. The swelling treatment is preferably carried out by immersing the substrate on which the second via holes have been formed in a swelling liquid heated to 60°C to 80°C for 5 to 10 minutes.

[0221] The oxidizing agent solution is preferably an alkaline permanganate aqueous solution, such as a solution prepared by dissolving potassium permanganate or sodium permanganate in an aqueous solution of sodium hydroxide. The oxidation treatment using the oxidizing agent solution is preferably carried out by immersing the printed wiring board after swelling treatment in the oxidizing agent solution heated to 60°C to 80°C for 10 to 30 minutes. Commercially available alkaline permanganate aqueous solutions include "Concentrate Compact CP" and "Dosing Solution Securigance P" manufactured by Atotech Japan Co., Ltd.

[0222] The neutralization treatment with a neutralizing solution is preferably carried out by immersing the substrate after the oxidation treatment in the neutralizing solution for 3 to 10 minutes at a temperature of 30 to 50° C. The neutralizing solution is preferably an acidic aqueous solution, and a commercially available product such as "Reduction Solution Securigant P" manufactured by Atotech Japan Co., Ltd. is an example.

[0223] The wet desmearing treatment may also be a wet sandblasting desmearing treatment in which an abrasive and a dispersion medium are sprayed from a nozzle to polish the treatment target. The wet sandblasting desmearing treatment can be performed using a commercially available wet sandblasting desmearing treatment device.

[0224] 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.

[0225] <(J) Conductor Layer Formation Process> In step (J), a new conductor layer 12' is formed in the printed wiring board I after the desmearing in step (I), within the first via hole 70 from the first opening 71 to the circuit board 10, continuously therefrom on the surface of the first opening 71 outside the first via hole 70, within the second via hole 80 from the second opening 81 to the circuit board 10, and continuously therefrom on the surface of the second opening 81 outside the second via hole 80.

[0226] 11 is a cross-sectional view schematically illustrating an example of a printed wiring board J after the formation of a conductor layer produced in step (J). In the printed wiring board J after the formation of a conductor layer produced in step (J), as shown in FIG. 11, a conductor layer 12' is formed in the first via hole 70 from the first opening 71 to the surface of the conductor layer 12 of the circuit board 10, which is the bottom (through-hole portion), and continuously therefrom on the surface of the first opening 71 outside the first via hole 70; in the second via hole 80 from the second opening 81 to the surface of the conductor layer 12 of the circuit board 10, which is the bottom (through-hole portion), and continuously therefrom on the surface of the second opening 81 outside the second via hole 80. Therefore, the conductor layer 12' formed on the surface of the first opening 71 or the second opening 81 is electrically conductive with the conductor layer 12 of the circuit board 10 that has been formed previously via the conductor layer 12' formed in the first via hole 70 or the second via hole 80, respectively.

[0227] In addition, a conductor layer 12' is formed on at least a portion of the surface of the cured layer 30 opposite the side that contacts the circuit board 10, so as to be continuously joined to the cured layer 30 from the conductor layer 12' formed on the surface of the first opening 71 outside the first via hole 70, and a conductor layer 12' is formed on the surface of the second opening 81 outside the second via hole 80, so as to be continuously joined to the cured layer 30.

[0228] The conductive material used for the conductor layer 12' is not particularly limited. In a preferred embodiment, the conductor layer 12' 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 conductor layer 12' may be a single metal layer or an alloy layer. Examples of alloy layers include layers formed from an alloy of two or more metals selected from the above group (e.g., nickel-chromium alloy, copper-nickel alloy, copper-titanium alloy, and nickel-gold alloy). Among these, from the viewpoints of versatility in forming the conductor layer 12', cost, ease of patterning, etc., a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of a nickel-chromium alloy, a copper-nickel alloy, a copper-titanium alloy, or a nickel-gold alloy, is preferred, a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of a nickel-chromium alloy or a nickel-gold alloy is more preferred, and a single metal layer of copper is even more preferred.

[0229] The conductor layer 12' may have a single layer structure or a multi-layer structure in which two or more single metal layers or alloy layers made of different types of metals or alloys are laminated, but in one embodiment, a multi-layer structure is preferred. When the conductor layer 12' has a multi-layer structure, the layer in contact with the hardening layer 30 is preferably a single metal layer of chromium, zinc, titanium, or copper, or a nickel-chromium alloy alloy layer. The exposed layer not in contact with the hardening layer 30 (the layer that bonds with the first solder ball 90a or second solder ball 90b formed in the following step (K)) is preferably a nickel-gold alloy layer.

[0230] The thickness T of the conductor layer 12′ formed on at least a part of the surface of the cured layer 30 opposite to the side in contact with the circuit board 10, on the surface of the first opening 71 outside the first via hole 70, and on the surface of the second opening 81 outside the second via hole 80 12’ The thickness T of the conductor layer 12′ can be equal to each other. 12’Although it depends on the design of the desired circuit board, the thickness T of the conductor layer 12' is usually 35 μm or less, preferably 30 μm or less, and more preferably 25 μm or less. 12’ The lower limit of is not particularly limited, but is usually 3 μm or more, preferably 5 μm or more.

[0231] In one embodiment, step (J) includes, in this order, step (J1) of forming a metal layer by dry plating on the surface of the hardened layer 30, and step (J2) of forming a conductor layer 12' by wet plating on the surface of the metal layer formed in step (J1). In another embodiment, step (J) includes step (J') of forming a conductor layer 12' by wet plating on the surface of the hardened layer 30. It is preferable that the surface of the hardened layer 30 has been roughened in advance by the desmear treatment in step (H) or has been roughened under similar conditions.

[0232] Examples of the dry plating method in step (J1) include physical vapor deposition (PVD) methods such as vapor deposition, sputtering, ion plating, and laser ablation, and chemical vapor deposition (CVD) methods such as thermal CVD and plasma CVD, among which vapor deposition and sputtering are preferred. The metal layer may be formed by combining two of these dry plating methods.

[0233] The thickness of the metal layer formed in step (J1) is not particularly limited, but is preferably 5 nm to 2 μm, more preferably 10 nm to 1 μm, and even more preferably 20 nm to 500 nm. The metal layer formed in step (J1) may have a single-layer structure or a multi-layer structure. When the metal layer formed in step (J1) has a multi-layer structure, it is preferable that the thickness of the entire metal layer is within the above range.

[0234] In step (J2), a conductor layer 12' having a desired pattern can be formed by wet plating using a semi-additive method using the metal layer as a plating seed layer. Specifically, a mask pattern is formed on the metal layer (plating seed layer) formed in step (J1) to expose a portion of the metal layer (plating seed layer) corresponding to the desired wiring pattern. After forming a conductor layer on the exposed metal layer (plating seed layer) by electrolytic plating, the mask pattern is removed. Thereafter, unnecessary metal layer (plating seed layer) is removed by etching or the like to form a conductor layer 12' having the desired wiring pattern.

[0235] In step (J'), a conductor layer 12' is formed by directly wet plating the surface of the cured layer 30. For example, a conductor layer 12' having a desired wiring pattern can be formed by a semi-additive method using a combination of electroless plating and electrolytic plating.

[0236] <(K) Solder ball formation process> In step (K), a first solder ball 90a is formed on the surface of the conductor layer 12' formed on the surface of the first opening 71 in the printed wiring board J after the conductor layer is formed in step (I), and a second solder ball 90b is formed on the surface of the conductor layer 12' formed on the surface of the second opening 81.

[0237] 12 is a cross-sectional view schematically illustrating an example of a printed wiring board K after the formation of solder balls manufactured in step (K). In the printed wiring board K after the formation of solder balls manufactured in step (K), as shown in one example in FIG. 12, a first solder ball 90a is formed on the conductor layer 12′ formed on the surface of the first opening 71 so as to be electrically conductive with the conductor layer 12′, and a second solder ball 90b, which is larger than the first solder ball 90a, is formed on the conductor layer 12′ formed on the surface of the second opening 81 so as to be electrically conductive with the conductor layer 12′.

[0238] In the printed wiring board of the present invention, via holes having different opening diameters are formed in the cured layer, so that solder balls of different sizes can be formed according to the different opening diameters of the via holes.

[0239] <(L) Printed wiring board package formation process> In step (L), the printed wiring board K after the solder balls have been formed in step (K) is electrically connected to the first circuit board 10a and the second circuit board 10b, which are placed in parallel thereto, via the first solder balls 90a and the second solder balls 90b, and the spaces between the printed wiring board K and the first circuit board 10a and the second circuit board 10b are sealed with sealing resin 100 to produce a printed wiring board package L.

[0240] Fig. 13 is a cross-sectional view schematically illustrating an example of a printed wiring board package L manufactured in step (L). In the printed wiring board package L manufactured in step (L), as shown in Fig. 13, a second circuit board 10b is placed in parallel to and at a predetermined distance from the surface of the printed wiring board K on the side on which the first solder balls 90a and the second solder balls 90b are formed, in the thickness direction of the printed wiring board K, and a first circuit board 10a is placed in parallel to and at a predetermined distance from the surface of the second circuit board 10b opposite the printed wiring board K side, in the thickness direction of the second circuit board 10b.

[0241] Second circuit board 10b typically has a smaller board area than printed wiring board K and first circuit board 10a. Printed wiring board K and first circuit board 10a each have areas that overlap with second circuit board 10b and areas that do not. Only first circuit board 10a exists in the thickness direction of the portion of printed wiring board K where first solder balls 90a are formed, while both second circuit board 10b and first circuit board 10a exist and overlap in the thickness direction of the portion of printed wiring board K where second solder balls 90b are formed.

[0242] The printed wiring board K is electrically connected to the first circuit board 10a via first solder balls 90a of the printed wiring board K and solder balls 90a' of the first circuit board, and is electrically connected to the second circuit board 10b via second solder balls 90b of the printed wiring board K and solder balls 90b' of the second circuit board. Furthermore, the spaces between the printed wiring board K and the first circuit board 10a and the second circuit board 10b are sealed with sealing resin 100.

[0243] Since via holes with different opening diameters are formed in the cured layer of the printed wiring board of the present invention, first solder balls 90a and second solder balls 90b of different sizes can be formed according to the opening diameters of the different via holes, thereby allowing the printed wiring board K to be electrically connected to the first circuit board 10a and the second circuit board 10b, which are placed at different distances, via the first solder balls 90a and second solder balls 90b of different sizes, respectively.This makes it possible to design more complex and precise semiconductor devices.

[0244] <Semiconductor device> The semiconductor device of the present invention includes the printed wiring board of the present invention (for example, in the form of a printed wiring board package). Examples of the semiconductor device include various semiconductor devices used in electrical appliances (for example, computers, mobile phones, smartphones, tablet devices, wearable devices, digital cameras, medical equipment, and televisions) and vehicles (for example, motorcycles, automobiles, trains, ships, and aircraft). [Example]

[0245] 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 and pressure conditions are room temperature (25°C) and atmospheric pressure (1 atm).

[0246] <Preparation Example 1: Preparation of Resin Composition 1> Biphenyl-type epoxy resin (Nippon Kayaku Co., Ltd. "NC-3000-L", epoxy equivalent: approx. 269) 10 parts, liquid 1,4-glycidylcyclohexane (Nippon Steel Chemical & Material Co., Ltd. "ZX1658", epoxy equivalent: approx. 135) 10 parts, bixylenol-type epoxy resin (Mitsubishi Chemical Co., Ltd. "YX4000H", epoxy equivalent: approx. 185) 10 parts, active ester compound (DIC Corporation "HPC-8000 50 parts of "-65T", active group equivalent weight approximately 223, 65% solids in toluene solution), 6 parts of triazine skeleton-containing phenolic curing agent (DIC Corporation "LA-3018-50P", hydroxyl group equivalent weight approximately 151, 50% solids in 2-methoxypropanol solution), 10 parts of phenoxy resin (Mitsubishi Chemical Corporation "YX7553BH30", 30% solids in 1:1 solution of MEK and cyclohexanone), carbodiimide The compound (Nisshinbo Chemical Co., Ltd.'s "V-03," active group equivalent weight approximately 216, toluene solution with a solid content of 50% by mass) was 10 parts, and the surface of spherical silica (Admatechs Co., Ltd.'s "SO-C2," average particle size 0.5 μm) was surface-treated with an aminosilane coupling agent (Shin-Etsu Chemical Co., Ltd.'s "KBM573"), 220 parts of phosphorus-based flame retardant (Sankosha Co., Ltd.'s "HCA-HQ-HS," 10-(2,5-dihydroxyphenyl)-10-hydroxybenzoyl)propanol ...") was 220 parts. Resin composition 1 (varnish-like) was prepared by mixing 1 part of fluoro-9-oxa-10-phosphaphenanthrene-10-oxide, 1 part of rubber particles ("Staphyloid AC3816N" manufactured by Aica Kogyo Co., Ltd.), 5 parts of a curing accelerator (4-dimethylaminopyridine (DMAP), MEK solution with a solids content of 5% by mass), 25 parts of methyl ethyl ketone, and 15 parts of cyclohexanone and dispersing the mixture uniformly using a high-speed rotating mixer.

[0247] <Preparation Example 2: Preparation of Resin Composition 2> Biphenyl epoxy resin (Nippon Kayaku "NC-3000-L", epoxy equivalent: approx. 269) 30 parts, bisphenol A epoxy resin (Mitsubishi Chemical "828EL", epoxy equivalent: approx. 180) 20 parts, tetraphenylethane epoxy resin (Mitsubishi Chemical "jER1031S", epoxy equivalent: approx. 198) 5 parts, triazine skeleton-containing phenol novolac hardener (DIC "LA-7054", hydroxyl equivalent: approx. 125, MEK solution with 60% solids) 10 parts, phenol novolac hardener (DIC "TD-2090-6" 0M", hydroxyl equivalent weight approximately 105, solid content 60%), 10 parts of phenoxy resin (Mitsubishi Chemical Corporation "YX7553BH30", a 1:1 solution of MEK and cyclohexanone with a solid content of 30%), 8 parts of phenoxy resin, 35 parts of spherical silica (Admatechs Co., Ltd. "SO-C2", average particle size 0.5 μm) surface-treated with an aminosilane coupling agent (Shin-Etsu Chemical Co., Ltd. "KBM573"), 35 parts of spherical silica (Denka Co., Ltd. "UFP-30", average particle size 0.3 μm, specific surface area 30.7 m) surface-treated with a methacrylsilane coupling agent (Shin-Etsu Chemical Co., Ltd. "KBM503"). 2 35 parts of hydroxybenzoate (10-(2,5-dihydroxyphenyl)-10-hydroxy-9-oxa-10-phosphaphenanthrene-10-oxide), 5 parts of a phosphorus-based flame retardant ("HCA-HQ-HS" manufactured by Sankosha, 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide), 3 parts of a curing accelerator (4-dimethylaminopyridine (DMAP), MEK solution with a solids content of 5%), 20 parts of methyl ethyl ketone, and 10 parts of cyclohexanone were mixed and uniformly dispersed in a high-speed rotating mixer to prepare Resin Composition 2 (varnish-like).

[0248] <Preparation Example 3: Preparation of Resin Composition 3> Bisphenol A epoxy resin (Mitsubishi Chemical Corporation "828EL", epoxy equivalent: approx. 180) 20 parts, naphthol epoxy resin (Nippon Steel Chemical & Material Corporation "ESN-475V", epoxy equivalent: approx. 332) 10 parts, bixylenol epoxy resin (Mitsubishi Chemical Corporation "YX4000H", epoxy equivalent: approx. 185) 10 parts, naphthylene ether epoxy resin (DIC Corporation "HP6000", epoxy equivalent: approx. 260) 20 parts, cyanate ester curing agent (Lonza Japan Co., Ltd. "BA230S75", cyanate equivalent: approx. 235, MEK solution with 75% solids) 10 parts, cyanate ester curing agent (Lonza Japan Co., Ltd. "BADCy", cyanate equivalent: approx. 142) 10 parts, active ester compound (DIC Corporation " 20 parts of "HPC-8000-65T," active group equivalent weight approximately 223, 65% solids in toluene solution), 8 parts of phenoxy resin (Mitsubishi Chemical Corporation's "YX7553BH30," 30% solids in 1:1 solution of MEK and cyclohexanone), 85 parts of spherical silica (Admatechs Co., Ltd.'s "SO-C2," average particle size 0.5 μm) surface-treated with an aminosilane coupling agent (Shin-Etsu Chemical Co., Ltd.'s "KBM573"), 3 parts of curing accelerator (4-dimethylaminopyridine (DMAP), 5% solids in MEK solution), 5 parts of cobalt (III) acetylacetonate (Tokyo Chemical Industry Co., Ltd.'s 1% MEK solution), 30 parts of methyl ethyl ketone, and 15 parts of cyclohexanone were mixed and uniformly dispersed using a high-speed rotating mixer to prepare Resin Composition 3 (varnish).

[0249] <Preparation Example 4: Preparation of Resin Composition 4> Bisphenol A epoxy resin (Mitsubishi Chemical Corporation "828EL", epoxy equivalent: approximately 180) 15 parts, bixylenol epoxy resin (Mitsubishi Chemical Corporation "YX4000H", epoxy equivalent: approximately 185) 25 parts, active ester compound (DIC Corporation "HPC-8000-65T", active group equivalent: approximately 223, toluene solution with 65% solids) 40 parts, styrene-modified polyphenylene ether resin (Mitsubishi Gas Chemical Corporation "OPE-2St1200" (number average molecular weight: approximately 100%) Amount: 1200 (50 parts of toluene solution with a solids content of 60%), 50 parts of spherical silica ("SO-C2" manufactured by Admatechs, average particle size 0.5 μm) surface-treated with an aminosilane coupling agent ("KBM573" manufactured by Shin-Etsu Chemical Co., Ltd.), 240 parts of a curing accelerator (10% MEK solution of "1B2PZ" manufactured by Shikoku Kasei Co., Ltd.), 40 parts of methyl ethyl ketone, and 20 parts of cyclohexanone were mixed and uniformly dispersed in a high-speed rotating mixer to prepare Resin Composition 4 (varnish-like).

[0250] <Preparation Example 5: Preparation of Resin Composition 5> The amount of spherical silica (Admatechs "SO-C2", average particle size 0.5 μm) surface-treated with an aminosilane coupling agent (Shin-Etsu Chemical Co., Ltd. "KBM573") was reduced from 35 parts to 20 parts, and the amount of spherical silica (Denka Co., Ltd. "UFP-30", average particle size 0.3 μm, specific surface area 30.7 m) surface-treated with a methacrylsilane coupling agent (Shin-Etsu Chemical Co., Ltd. "KBM503") was reduced from 35 parts to 20 parts. 2 Resin composition 5 (varnish-like) was prepared in the same manner as in Preparation Example 2, except that the amount of hydroxybenzoates (1 / g) used was changed from 35 parts to 20 parts.

[0251] <Preparation Example 6: Preparation of Resin Composition 6> Resin composition 6 (varnish-like) was prepared in the same manner as in Preparation Example 1, except that the amount of spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd., average particle size 0.5 μm) surface-treated with an aminosilane coupling agent ("KBM573" manufactured by Shin-Etsu Chemical Co., Ltd.) was changed from 220 parts to 300 parts.

[0252] <Test Example 1: Measurement of Elastic Modulus> The resin compositions obtained in Preparation Examples 1 to 6 were uniformly applied to the release surface of a release-treated polyethylene terephthalate film ("AL5" manufactured by Lintec Corporation, thickness 38 μm) and dried at 80 to 120°C (average 100°C) for 6 minutes to produce a resin sheet with a resin composition layer thickness of 40 μm.

[0253] A glass cloth-based epoxy resin double-sided copper-clad laminate (Panasonic Corporation's "R5715ES", thickness 0.7 mm, 255 mm square) was placed on the release agent-untreated side of a release agent-treated PET film (Lintec Corporation's "501010", thickness 38 μm, 240 mm square), and the four sides were fixed with polyimide adhesive tape (width 10 mm) (hereinafter sometimes referred to as the "fixed PET film").

[0254] The resulting adhesive film with a thickness of 40 μm was laminated onto the release-treated surface of the fixed PET film using a batch-type vacuum pressure laminator (MVLP-500, manufactured by Meiki Co., Ltd.). The pressure was reduced for 30 seconds to 13 hPa or less, and then the film was pressed at 100°C and a pressure of 0.74 MPa for 30 seconds.

[0255] Next, the release-treated polyethylene terephthalate film ("AL5" manufactured by Lintec Corporation, thickness 38 μm) was peeled off, and the adhesive film was thermally cured in an oven at 190° C. for 90 minutes.

[0256] After thermal curing, the polyimide adhesive tape was peeled off, and the cured product was removed from the glass cloth-based epoxy resin double-sided copper-clad laminate. The PET film ("501010" manufactured by Lintec Corporation) was also peeled off, yielding a sheet-like cured product for evaluation.

[0257] The resulting cured product for evaluation was subjected to a tensile test at 25°C using a Tensilon universal testing machine (manufactured by A&D Co., Ltd.) in accordance with Japanese Industrial Standards (JIS K7127) to measure the modulus of elasticity (GPa).

[0258] <Test Example 2: Measurement of linear thermal expansion coefficient> The cured product for evaluation obtained in Test Example 1 was cut into test pieces approximately 5 mm wide and 15 mm long, and thermomechanical analysis was performed using a Rigaku Corporation thermomechanical analyzer (Thermo Plus TMA8310) by the tensile load method. After mounting the test piece in the analyzer, measurements were performed twice consecutively under the measurement conditions of a load of 1 g and a heating rate of 5°C / min. The average linear thermal expansion coefficient from 25°C to 150°C was calculated from the two measurements.

[0259] The amounts of raw materials used based on the solid content of Resin Compositions 1 to 6 in Preparation Examples 1 to 6, and the measurement results of Test Examples 1 and 2 are summarized in Table 1 below.

[0260] [Table 1]

[0261] <Example 1: Preparation of evaluation printed wiring board 1> (1) Preparation of resin sheet Resin composition 1 obtained in Preparation Example 1 was uniformly applied to the release surface of a release-treated polyethylene terephthalate film ("AL5" manufactured by Lintec Corporation, thickness 38 μm) and dried at 80 to 120°C (average 100°C) for 6 minutes to produce a resin sheet with a resin composition layer thickness of 15 μm.

[0262] (2) Laminating resin sheets The resulting resin sheet with a thickness of 15 μm was laminated using a batch-type vacuum pressure laminator (MVLP-500, manufactured by Meiki Co., Ltd.) so that the resin composition layer was in contact with both sides of a laminate (circuit board) whose copper (conductor layer) surface had been roughened using a "CZ8201" manufactured by MEC Co., Ltd. The lamination was performed by reducing the pressure for 30 seconds to 13 hPa or less, and then pressing for 30 seconds at 100°C and a pressure of 0.74 MPa.

[0263] (3) Curing of the resin composition layer The laminated plate with the resin sheet (resin sheet laminated plate) was heated at 180° C. for 30 minutes to thermally cure the resin composition layer in the laminate plate, thereby forming an insulating layer (cured layer).

[0264] (4) Via processing by sandblasting Next, the release-treated polyethylene terephthalate film of the resin sheet was peeled off, and then a resist film (Nikko Materials Co., Ltd., NCM340, thickness 40 μm) was attached to the surface of the insulating layer. The resist film was laminated using a batch-type vacuum pressure laminator (Meiki Seisakusho Co., Ltd., "MVLP-500"), which was depressurized for 30 seconds to a pressure of 13 hPa or less, and then pressurized at a pressure of 0.1 MPa and a temperature of 70°C for 20 seconds. After that, a glass mask with a via pattern was placed on the polyethylene terephthalate film, which was the protective layer of the dry film, and a UV lamp was used to irradiate the film with an irradiation intensity of 140 mJ / cm. 2 After UV irradiation, the substrate was sprayed with a 1% sodium carbonate aqueous solution at 25°C at a spray pressure of 0.15 MPa for 45 seconds. After that, the substrate was washed with water to form a via pattern for forming a circular first via hole (opening size (diameter) on the insulating layer surface: 100 μm). After that, sandblasting was performed using #2000 alumina abrasive grain slurry (average grain size 6.7 μm) as abrasive grains to form a pattern for the first via hole.

[0265] (5) Laser via processing A pattern of circular second via holes was formed on the surface of the insulating layer using a UV-YAG laser processing machine ("LU-2L212 / M50L" manufactured by Via Mechanics Co., Ltd.). The opening diameter (diameter) of the second via holes on the surface of the insulating layer was 20 μm. After the second via holes were formed, the resist film was removed.

[0266] (6) Via fill plating and copper land pattern formation The laminate with the insulating layer and the first and second via holes formed therein was immersed in a swelling solution (Atotech Japan's "Swelling Dip Securigant P," a sodium hydroxide solution containing diethylene glycol monobutyl ether) at 60°C for 10 minutes, then in an oxidizing agent (Atotech Japan's "Concentrate Compact CP," a potassium permanganate solution with a concentration of approximately 6% by mass and approximately 4% by mass of sodium hydroxide) at 80°C for 20 minutes, and finally in a neutralizing solution (Atotech Japan's "Reduction Solution Securigant P," a hydroxylamine sulfate solution) at 40°C for 5 minutes. The laminate was then dried at 80°C for 30 minutes. It was then immersed in an electroless plating solution containing PdCl2 at 40°C for 5 minutes, followed by immersion in an electroless copper plating solution at 25°C for 20 minutes. The laminate was then annealed by heating at 150°C for 30 minutes, after which an etching resist was applied and a copper land pattern was formed by etching. Thereafter, via fill and copper lands (conductor layers) were formed by copper sulfate electrolytic plating, and annealing treatment was carried out at 180° C. for 60 minutes to prepare a printed wiring board 1 for evaluation.

[0267] <Example 2: Preparation of evaluation printed wiring board 2> Evaluation printed wiring board 2 was produced in the same manner as in Example 1, except that resin composition 2 obtained in Preparation Example 2 was used instead of resin composition 1, the thickness of the resin composition layer of the resin sheet was changed from 15 μm to 20 μm, the opening diameter of the circular first via hole formed by sandblasting was changed from 100 μm to 200 μm, a CO2 laser processing machine (Hitachi Via Mechanics' "LC-2E21B / 1C") was used instead of a UV-YAG laser processing machine, and the opening diameter of the circular second via hole was changed from 20 μm to 30 μm.

[0268] <Example 3: Preparation of evaluation printed wiring board 3> Evaluation printed wiring board 3 was produced in the same manner as in Example 1, except that resin composition 3 obtained in Preparation Example 3 was used instead of resin composition 1, the thickness of the resin composition layer of the resin sheet was changed from 15 μm to 20 μm, the opening shape of the first via hole formed by sandblasting was changed from circular to approximately square with an opening diameter (length of one side of the square) of 200 μm, a CO2 laser processing machine (Hitachi Via Mechanics' "LC-2E21B / 1C") was used instead of a UV-YAG laser processing machine, and the opening diameter of the circular second via hole was changed from 20 μm to 30 μm.

[0269] <Example 4: Preparation of evaluation printed wiring board 4> An evaluation printed wiring board 4 was produced in the same manner as in Example 1, except that resin composition 4 obtained in Preparation Example 4 was used instead of resin composition 1, and the opening diameter of the circular first via hole formed by sandblasting was changed from 100 μm to 200 μm.

[0270] <Comparative Example 1: Preparation of Evaluation Printed Wiring Board 5> The thickness of the resin composition layer of the resin sheet was changed from 15 μm to 30 μm, and a CO2 laser processing machine (Hitachi Via Mechanics' "LC-2E21B / 1C") was used instead of a UV-YAG laser processing machine to attempt to form a circular second via hole with an opening diameter of 35 μm. However, the cured layer was too thick to expose the underlying copper pattern, so evaluation printed wiring board 5 was produced in the same manner as in Example 1.

[0271] <Comparative Example 2: Preparation of Evaluation Printed Wiring Board 6> The thickness of the resin composition layer of the resin sheet was changed from 15 μm to 20 μm, and an attempt was made to form circular first via holes with an opening diameter of 30 μm by sandblasting instead of circular first via holes with an opening diameter of 100 μm, but the underlying copper pattern could not be exposed while the resist film remained.Furthermore, a CO2 laser processing machine (Hitachi Via Mechanics' "LC-2E21B / 1C") was used instead of the UV-YAG laser processing machine, and the opening diameter of the circular second via holes was changed from 20 μm to 30 μm.Except for this, evaluation printed wiring board 6 was produced in the same manner as in Example 1.

[0272] <Comparative Example 3: Preparation of Evaluation Printed Wiring Board 7> Resin composition 5 obtained in Preparation Example 5 was used instead of resin composition 1, the thickness of the resin composition layer of the resin sheet was changed from 15 μm to 20 μm, and the opening diameter of the circular first via hole formed by sandblasting was changed from 100 μm to 200 μm. An attempt was made to form a first via hole, but the underlying copper pattern could not be exposed while the resist film remained.Furthermore, a CO2 laser processing machine (Hitachi Via Mechanics' "LC-2E21B / 1C") was used instead of the UV-YAG laser processing machine, and the opening diameter of the circular second via hole was changed from 20 μm to 30 μm.Except for this, evaluation printed wiring board 7 was produced in the same manner as in Example 1.

[0273] <Comparative Example 4: Preparation of Evaluation Printed Wiring Board 8> An evaluation printed wiring board 8 was produced in the same manner as in Example 1, except that resin composition 6 obtained in Preparation Example 6 was used instead of resin composition 1, the thickness of the resin composition layer of the resin sheet was changed from 15 μm to 20 μm, the opening diameter of the circular first via hole formed by sandblasting was changed from 100 μm to 200 μm, a CO2 laser processing machine (Hitachi Via Mechanics' "LC-2E21B / 1C") was used instead of a UV-YAG laser processing machine, and the opening diameter of the circular second via hole was changed from 20 μm to 30 μm.

[0274] <Evaluation Example 1: Evaluation of sandblasting processability> The processing time for forming the first via hole by sandblasting in step (4) of each example was measured, and the sandblasting processability was evaluated according to the following evaluation criteria.

[0275] Evaluation criteria "Good": The underlying copper pattern can be exposed while the resist film remains, and the processing time is less than 5 minutes. "△": The underlying copper pattern can be exposed while the resist film remains, and the processing time is 5 minutes or more. "X": Unable to expose the underlying copper pattern while the resist film remains

[0276] <Evaluation Example 2: Evaluation of crack suppression> The evaluation board was subjected to a thermal cycle test in which one cycle consisted of 10 minutes at -55°C and 10 minutes at 125°C (number of cycles: 1000). After the thermal cycle test, the cross section of the laminate was observed with an SEM (magnification 4500x) to check for cracks or peeling at the via connection, and the connection reliability was evaluated according to the following evaluation criteria.

[0277] Evaluation criteria "○": Of the 20 via connection parts, including 10 via connection parts of any observed first via holes and 10 via connection parts of any observed second via holes, there were no cracks or peeling. "△": 1 to 2 cracks or peelings were found among 20 via connection parts, including 10 via connection parts of the first via hole and 10 via connection parts of the second via hole. "X": Three or more cracks or peelings were found among a total of 20 via connection parts, including 10 via connection parts of any observed first via holes and 10 via connection parts of any observed second via holes.

[0278] <Evaluation Example 3: Evaluation of warpage suppression> The resin sheet having the specific resin composition layer thickness obtained in step (1) of each example was laminated to one side of a glass cloth double-sided copper-clad laminate (copper foil thickness 18 μm, substrate thickness 0.2 mm, Hitachi Chemical Co., Ltd. "MCL-E679 FGR", size 15 cm × 18 cm) using a batch-type vacuum pressure laminator (Nikko Materials Co., Ltd. two-stage build-up laminator "CVP700"). After removing the PET film, the laminate was thermally cured at 190°C for 90 minutes, placed on a flat surface, and the amount of warping was confirmed and evaluated according to the following evaluation criteria.

[0279] Evaluation criteria "○": The average amount of warping at each of the four corners is less than 1 cm "△": The average amount of warping at each of the four corners is 1 cm or more but less than 2 cm "×": The average amount of warping at each of the four corners is 2 cm or more.

[0280] The characteristics of the evaluation printed wiring boards 1 to 8, and the measurement and evaluation results of Evaluation Examples 1 to 3 are summarized in Table 2 below.

[0281] [Table 2]

[0282] As described above, when the thickness of the hardened layer was 25 μm or less and the elastic modulus of the hardened layer at 25° C. was 5 GPa or more and 15 GPa or less, the sandblasting processability was excellent, the first via hole and the second via hole could be successfully formed, and furthermore, the occurrence of cracks and warping could be suppressed. In Comparative Example 1, where the thickness of the hardened layer exceeded 25 μm, the hardened layer was too thick, so the second via hole could not be formed by laser treatment. In Comparative Example 2, an attempt was made to form a via hole with an opening diameter of less than 50 μm by sandblasting, but it was not possible. In Comparative Example 3, where the elastic modulus was less than 5 GPa, the sandblasting processability was reduced, so the first via hole could not be formed by sandblasting. Furthermore, the occurrence of numerous cracks was confirmed. In Comparative Example 4, where the elastic modulus exceeded 15 GPa, significant warping was confirmed. [Explanation of symbols]

[0283] 10 Circuit Board 10a first circuit board 10b Second circuit board 11 Support substrate 12 Conductor layer 12' Conductor layer 20 Resin sheet 21 Support 22 Resin composition layer 30 Hardened layer 40 Resist Film 50 Photomasks 60 Sandblast Mask 61 Mask opening 70 First Beer Hall 71 First opening 80 Second Beer Hall 81 Second opening 90a First solder ball 90b Second solder ball 90a' Solder balls of first circuit board 90b' Solder balls of second circuit board 100 Sealing resin

Claims

1. a cured layer formed by thermally curing a resin composition containing a thermosetting resin; the hardened layer comprises: a first via hole having a first opening with an opening diameter of 50 μm or more and 500 μm or less on one surface of the hardened layer, the first via hole being formed so as to penetrate the hardened layer from the first opening; and a second via hole having a second opening with an opening diameter of 32 μm or less on the one surface, the second via hole being formed so as to penetrate the hardened layer from the second opening, a minimum pitch of the first via holes is a shortest distance from a center of a first opening of one of the plurality of first via holes to a center of another first opening that is closest to the center of the first opening on the one surface of the same hardened layer, and is 1000 μm or less; a minimum pitch of the second via holes is a shortest distance from a center of a second opening of one of the plurality of second via holes to a center of another second opening that is closest to the center of the other second opening on the one surface of the same hardened layer, and is 100 μm or less; The thickness of the cured layer is 25 μm or less, The elastic modulus of the cured layer at 25°C is 5 GPa or more and 15 GPa or less, A method for producing a printed wiring board, wherein the linear thermal expansion coefficient of the cured layer is 10 ppm / °C or more and 50 ppm / °C or less, A method for manufacturing a printed wiring board, comprising: a step of sandblasting the hardened layer to form the first via hole in the hardened layer; and a step of irradiating a laser toward the hardened layer after the first via hole has been formed, to form the second via hole in the hardened layer.

2. The method for manufacturing a printed wiring board according to claim 1 , further comprising the step of performing a desmear process on the printed wiring board after the second via hole has been formed.

3. The method for manufacturing a printed wiring board according to claim 2 , wherein the first via holes have a minimum pitch of 500 μm or less.

4. The method for manufacturing a printed wiring board according to claim 2 , wherein the minimum pitch of the first via holes is 300 μm or less.

5. The method for manufacturing a printed wiring board according to claim 2 , wherein the minimum pitch of the first via holes is 200 μm or less.

6. The method for manufacturing a printed wiring board according to claim 2 , wherein the first via holes have a minimum pitch of 100 μm or less.

7. The method for manufacturing a printed wiring board according to claim 2 , wherein the minimum pitch of the second via holes is 50 μm or less.

8. The method for manufacturing a printed wiring board according to claim 2 , wherein the minimum pitch of the second via holes is 30 μm or less.

9. The method for manufacturing a printed wiring board according to claim 2 , wherein the minimum pitch of the second via holes is 10 μm or less.

10. The method for manufacturing a printed wiring board according to claim 2 , wherein the minimum pitch of the second via holes is 5 μm or less.

11. The method for manufacturing a printed wiring board according to any one of claims 1 to 10, wherein the cured layer has an elastic modulus at 25°C of 10 GPa or more.

12. The method for manufacturing a printed wiring board according to any one of claims 1 to 11, wherein the cured layer has a linear thermal expansion coefficient of 17 ppm / °C or more.

13. The method for manufacturing a printed wiring board according to any one of claims 1 to 12, wherein the cured layer has a thickness of 3 µm or more.

14. The method for producing a printed wiring board according to any one of claims 1 to 13, wherein the resin composition contains an epoxy resin as a thermosetting resin.

15. The method for producing a printed wiring board according to claim 14, wherein the content of the epoxy resin in the resin composition is 8% by mass or more and 40% by mass or less, when the non-volatile components in the resin composition are 100% by mass.

16. The method for producing a printed wiring board according to any one of claims 1 to 15, wherein the resin composition further contains an inorganic filler.

17. The method for producing a printed wiring board according to claim 16, wherein the content of the inorganic filler in the resin composition is 40% by mass or more and 77% by mass or less, when the non-volatile components in the resin composition are 100% by mass.

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