Printed wiring board

Abstract

Provided is a thin printed wiring board capable of suppressing warping in a component mounting process. A printed wiring board is a printed wiring board including first and second solder resist layers, wherein the thickness of the first solder resist layer is set to t1 (μm), the modulus of elasticity after curing (23°C) is set to G1 (GPa), the thickness of the second solder resist layer is set to t2 (μm), the modulus of elasticity after curing (23°C) is set to G2 (GPa), and the thickness of the printed wiring board is set to Z (μm), and the following conditions (1) to (3) are satisfied: (1) Z ≤ 250; (2) (t1 + t2) / Z ≥ 0.1; and (3) G1 × [t1 / (t1 + t2)] + G2 × [t2 / (t1 + t2)] ≥ 6, G1 being 6 or greater.

Description

[0001] This application is a divisional application of Chinese Patent Application No. 201510070892.7, filed on February 11, 2015, entitled "Printed Wiring Board". TECHNICAL FIELD

[0002] The present application relates to a printed wiring board. BACKGROUND

[0003] In order to prevent the attachment of solder to unwanted portions during the mounting process of semiconductor chips (hereinafter also referred to as "parts"), and in order to prevent corrosion of the circuit board, a solder resist layer is generally provided as a protective film on the outermost layer of the printed wiring board. The solder resist layer is generally formed by providing a layer of a photocurable resin composition on the circuit board, and then exposing and developing the layer (for example, Patent Document 1).

[0004] PRIOR ART DOCUMENTS

[0005] PATENT DOCUMENTS

[0006] Patent Document 1: Japanese Patent Application Publication No. 2009-258613 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] In recent years, with the replacement of lead-containing solder with lead-free solder, the reflow soldering temperature during the mounting process of parts has increased. Furthermore, in recent years, in order to achieve the miniaturization of electronic devices, further thinning of printed wiring boards has continued to progress.

[0009] The present inventors have found that, with the progress of thinning of printed wiring boards, warping of the printed wiring boards occurs during the mounting process of parts, resulting in problems such as deformation of the circuit and poor contact of the parts.

[0010] The present application provides a thin printed wiring board that can suppress warping during the mounting process of parts.

[0011] MEANS FOR SOLVING THE PROBLEMS

[0012] The present inventors have conducted earnest research on the above problem, and as a result, have found that the above problem can be solved by using two layers of solder resist layers having specific thicknesses and elastic moduli in combination, thereby completing the present application.

[0013] That is, the present application includes the following:

[0014] [1] A printed wiring board comprising a first solder resist layer and a second solder resist layer, wherein

[0015] When the thickness of the first solder resist layer is set to t1 (μm), the elastic modulus after curing (23°C) is set to G1 (GPa), the thickness of the second solder resist layer is set to t2 (μm), the elastic modulus after curing (23°C) is set to G2 (GPa), and the thickness of the printed wiring board is set to Z (μm), the following conditions (1) to (3) are satisfied:

[0016] (1) Z ≤ 250;

[0017] (2) (t1 + t2) / Z ≥ 0.1; and

[0018] (3) G1 x [t1 / (t1 + t2)] + G2 x [t2 / (t1 + t2)] ≥ 6,

[0019] G1 is 6 or more;

[0020] [2] The printed wiring board according to [1], wherein the glass transition temperature (Tg) after curing of the first solder resist layer is 150°C or more;

[0021] [3] The printed wiring board according to [1] or [2], wherein the first solder resist layer is formed by curing a resin composition having an inorganic filler content of 60 mass% or more;

[0022] [4] The printed wiring board according to any one of [1] to [3], wherein the condition (2) is 0.1 ≤ (t1 + t2) / Z ≤ 0.5;

[0023] [5] The printed wiring board according to any one of [1] to [4], wherein G2 is 6 or more;

[0024] [6] The printed wiring board according to any one of [1] to [5], wherein when the elastic modulus after curing (200°C) of the first solder resist layer is set to G1' (GPa) and the elastic modulus after curing (200°C) of the second solder resist layer is set to G2' (GPa), the following condition (4) is further satisfied:

[0025] (4) G1' x [t1 / (t1 + t2)] + G2' x [t2 / (t1 + t2)] ≥ 0.2;

[0026] [7] A semiconductor device comprising the printed wiring board according to any one of [1] to [6];

[0027] [8] A resin sheet set for a solder resist layer of a printed wiring board, the resin sheet set comprising:

[0028] a first resin sheet including a first support and a first resin composition layer joined to the first support; and a second resin sheet including a second support and a second resin composition layer joined to the second support, wherein a thickness of the first resin composition layer is set as t1 (μm), an elastic modulus after curing (23°C) is set as G1 (GPa), a thickness of the second resin composition layer is set as t2 (μm), an elastic modulus after curing (23°C) is set as G2 (GPa), and a thickness of the printed wiring board is set as Z (μm), the following conditions (1') to (3') are satisfied: an elastic modulus after curing (23°C) is set as G2 (GPa), and a thickness of the printed wiring board is set as Z (μm), the following conditions (1') to (3') are satisfied: an elastic modulus after curing (23°C) is set as G2 (GPa), and a thickness of the printed wiring board is set as Z (μm), the following conditions (1') to (3') are satisfied:

[0029] (1') Z < 250;

[0030] (2) (t1 + t2) / Z > 0.1; and (3) G1 x [t1 / (t1 + t2)] + G2 x [t2 / (t1 + t2)] > 6,

[0031]

[0032] G1 is 6 or more.

[0033] Effects of the Invention

[0034] According to the present application, a thin printed wiring board capable of suppressing warping in a component mounting process can be provided. DETAILED DESCRIPTION

[0035] [Printed wiring board]

[0036] The printed wiring board of the present application includes a first solder resist layer and a second solder resist layer, a thickness of the first solder resist layer is set as t1 (μm), an elastic modulus after curing (23°C) is set as G1 (GPa), a thickness of the second solder resist layer is set as t2 (μm), an elastic modulus after curing (23°C) is set as G2 (GPa), and a thickness of the printed wiring board is set as Z (μm), the following conditions (1) to (3) are satisfied:

[0037] (1) Z < 250;

[0038] (2) (t1 + t2) / Z > 0.1; and

[0039] (3) G1 x [t1 / (t1 + t2)] + G2 x [t2 / (t1 + t2)] > 6,

[0040] G1 is 6 or more.

[0041] The printed wiring board of the present application, which combines the first and second solder resist layers having specific thicknesses and elastic moduli, can suppress warping even in a component mounting process using a higher reflow soldering temperature, and thus can suppress occurrence of problems such as circuit deformation and poor component contact.

[0042] ​- Condition (1)

[0043] Condition (1) relates to the thickness Z (μm) of the printed wiring board of the present application. The thickness Z of the printed wiring board refers to the thickness of the entire printed wiring board including the circuit substrate, and the first and second solder resist layers provided on both sides of the circuit substrate. From the viewpoint of thinness, the thickness (Z) of the printed wiring board of the present application is 250 μm or less, preferably 240 μm or less, more preferably 230 μm or less, further preferably 220 μm or less, further more preferably 210 μm or less, particularly preferably 200 μm or less, 190 μm or less, 180 μm or less, 170 μm or less, 160 μm or less, or 150 μm or less. The printed wiring board of the present application can suppress warping in the mounting process even in the case of thinness as described above. The lower limit of the thickness (Z) is not particularly limited, but is usually 20 μm or more or 30 μm or more.

[0044] - Condition (2)

[0045] Condition (2) relates to the thicknesses tl (μm) and t2 (μm) of the first and second solder resist layers contained in the printed wiring board of the present application. Here, the thicknesses tl (μm) and t2 (μm) of the first and second solder resist layers are the thicknesses from the base surface of the circuit substrate (the portion of the surface of the circuit substrate where no surface circuit is present). From the viewpoint of suppressing warping of the printed wiring board in the mounting process, the ratio of the sum of the thicknesses of the first and second solder resist layers (tl + t2) to the thickness Z of the printed wiring board, i.e., the (tl + t2) / Z ratio, is 0.1 or more, although it is also related to the right-hand side value of Condition (3), but is preferably 0.15 or more, more preferably 0.2 or more, 0.22 or more, 0.24 or more, 0.26 or more, 0.28 or more, or 0.3 or more. From the viewpoint of obtaining a printed wiring board having a desired wiring density, the upper limit of the (tl + t2) / Z ratio is preferably 0.5 or less, more preferably 0.45 or less, further preferably 0.4 or less, 0.39 or less, 0.38 or less, 0.37 or less, 0.36 or less, 0.36 or less, or 0.34 or less.

[0046] The thickness tl of the first solder resist layer is not particularly limited as long as the above-described specific (tl + t2) / Z ratio is satisfied, but is preferably 5 μm or more, more preferably 10 μm or more, further preferably 15 μm or more, 20 μm or more, or 25 μm or more. The upper limit of the thickness tl is not particularly limited as long as the above-described specific (tl + t2) / Z ratio is satisfied, but is preferably 120 μm or less, more preferably 100 μm or less, further preferably 80 μm or less, 70 μm or less, 60 μm or less, 50 μm or less, 40 μm or less, or 30 μm or less.

[0047] The thickness t2 of the second solder resist layer is not particularly limited as long as the above specific (t1 + t2) / Z ratio is satisfied, and can be determined in consideration of the thickness t1 of the first solder resist layer and the thickness Z of the printed wiring board. The upper limit of the thickness t2 of the second solder resist layer can generally be 120 μm or less or 100 μm or less, and the lower limit of the thickness t2 can generally be 5 μm or more or 10 μm or more.

[0048] -Condition (3)-

[0049] Condition (3) relates to the elastic modulus (23°C) after curing of the first and second solder resist layers contained in the printed wiring board of the present application. As described below, the first and second solder resist layers are formed by curing a resin composition. The elastic modulus (23°C) after curing refers to the elastic modulus of the solder resist layer at 23°C after curing of the resin composition. When the elastic modulus (23°C) after curing of the first and second solder resist layers is G1 (GPa) and G2 (GPa), respectively, from the viewpoint of suppressing warping of the printed wiring board in the mounting process, the value of the formula: G1 x [t1 / (t1 + t2)] + G2 x [t2 / (t1 + t2)] (hereinafter also referred to as "thickness-weighted average value of G1 and G2") is preferably 6 or more, more preferably 6.2 or more, still more preferably 6.4 or more, further more preferably 6.6 or more, and further more preferably 6.8 or more. If the thickness-weighted average value of G1 and G2 is 6.8 or more, warping of the printed wiring board in the mounting process can be suppressed even in the case where the thickness Z of the printed wiring board is further reduced to 200 μm or less. From the viewpoint that warping of the printed wiring board in the mounting process can be suppressed even in the case where the thickness Z of the printed wiring board is reduced while the (t1 + t2) / Z ratio is further decreased, it is particularly preferred that the thickness-weighted average value of G1 and G2 be 7 or more, 7.5 or more, 8 or more, 8.5 or more, 9 or more, 9.5 or more, 10 or more, 10.5 or more, 11 or more, 11.5 or more, 12 or more, 12.5 or more, or 13 or more. The upper limit of the thickness-weighted average value of G1 and G2 is not particularly limited, but can generally be 40 or less, 30 or less, or the like. The elastic modulus (23°C) after curing of the first and second solder resist layers can be measured using a tensile testing machine according to a tensile load method at 23°C. As the tensile testing machine, for example, "RTC-1250A" (manufactured by ORIENTEC Corporation) can be cited.

[0050] The elastic modulus (23°C) of the first solder resist layer after curing, i.e., G1 (GPa) is 6 or more. The value of G1 is not particularly limited as long as it is 6 or more and the thickness-weighted average of G1 and G2 is within the above specific range, but from the viewpoint of sufficiently suppressing warping of the printed wiring board in the mounting process, it is preferably 6.2 or more, more preferably 6.4 or more, further preferably 6.6 or more, further more preferably 6.8 or more, particularly preferably 7 or more, 7.5 or more, 8 or more, 8.5 or more, 9 or more, 9.5 or more, 10 or more, 10.5 or more, 11 or more, 11.5 or more, 12 or more, 12.5 or more, or 13 or more. The upper limit of G1 is not particularly limited, but it can generally be 40 or less, 30 or less, or the like.

[0051] The elastic modulus (23°C) of the second solder resist layer after curing, i.e., G2 (GPa) is not particularly limited as long as the thickness-weighted average of G1 and G2 is within the above specific range. For example, the value of G2 can be determined within the range of 1 to 30 as long as the thickness-weighted average of G1 and G2 is within the above specific range. From the viewpoint of easily suppressing warping of the printed wiring board in the mounting process even in the case where the (t1 + t2) / Z ratio is further reduced while the thickness Z of the printed wiring board is reduced, it is particularly preferable that the value of G2 be 6 or more.

[0052] From the viewpoint of further suppressing warping of the printed wiring board in the mounting process, it is preferable that, when the elastic modulus (200°C) of the first and second solder resist layers after curing is G1' (GPa) and G2' (GPa), respectively, the following condition (4) be satisfied:

[0053] (4) G1' x [t1 / (t1 + t2)] + G2' x [t2 / (t1 + t2)] ≥ 0.2;

[0054] (G1' and G2' thickness-weighted average value) is 0.22 or more, and further preferably 0.24 or more. If the thickness-weighted average value of G1' and G2' is 0.24 or more, warping of the printed wiring board in the mounting process can be suppressed even in the case where the thickness Z of the printed wiring board is further reduced to 200 μm or less. From the viewpoint that warping of the printed wiring board in the mounting process can be suppressed even in the case where the (t1 + t2) / Z ratio is further reduced while the thickness Z of the printed wiring board is reduced, it is particularly preferable that the thickness-weighted average value of G1' and G2' be 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1.0 or more, 1.1 or more, 1.2 or more, 1.3 or more, or 1.4 or more. The upper limit of the thickness-weighted average value of G1' and G2' is not particularly limited, but is usually 15 or less, 10 or less, or the like. Note that the elastic modulus (200°C) after curing refers to the elastic modulus of the solder resist layer at 200°C after the resin composition is cured, and can be measured at 200°C using a tensile testing machine according to the tensile load method.

[0055] From the viewpoint of sufficiently suppressing warping of the printed wiring board in the mounting process, it is preferable that the elastic modulus (200°C) after curing of the first solder resist layer, i.e., G1' (GPa), be 0.2 or more, more preferably 0.22 or more, further preferably 0.24 or more, and particularly preferably 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1.0 or more, 1.1 or more, 1.2 or more, 1.3 or more, or 1.4 or more. The upper limit of G1' is not particularly limited, but is usually 15 or less, 10 or less, or the like.

[0056] It is preferable that the elastic modulus (200°C) after curing of the second solder resist layer, i.e., G2' (GPa), be such that the thickness-weighted average value of G1' and G2' in the relationship between G1' and G2' be within the above specific range. For example, as long as the thickness-weighted average value of G1' and G2' is within the above specific range, the value of G2' is preferably within the range of 0.1 to 10. From the viewpoint that warping of the printed wiring board in the mounting process can be easily suppressed even in the case where the (t1 + t2) / Z ratio is further reduced while the thickness Z of the printed wiring board is reduced, it is particularly preferable that the value of G2' be 0.2 or more.

[0057] The printed wiring board of the present application satisfying the above conditions (1), (2) and (3) can suppress warpage even in a mounting process using a higher reflow soldering temperature. In one embodiment, the printed wiring board of the present application can suppress warpage of the printed wiring board to 50 μm or less in a mounting process using a higher reflow soldering temperature having a peak temperature of 260°C. In the present application, when the warpage behavior of a 25 mm square portion in the center of the printed wiring board is observed using a shadow moire device, the warpage of the printed wiring board is the difference between the maximum height and the minimum height of displacement data. In the measurement, the printed wiring board is once passed through a reflow soldering device of a reflow temperature profile (profile for lead-free assembly; peak temperature 260°C, time required for temperature increase from 25°C to the peak temperature 5 minutes) described in IPC / JEDEC J-STD-020C ("Moisture / Reflow Sensitivity Classification For Nonhermetic Solid State Surface Mount Devices", July 2004), and then one side of the printed wiring board is subjected to a heating treatment according to the reflow temperature profile according to the above IPC / JEDEC J-STD-020C, and displacement data is obtained for grid lines provided on the other side of the printed wiring board. It should be noted that, as the reflow soldering device, for example, "HAS-6116" manufactured by Antom Corporation of Japan can be cited; and as the shadow moire device, for example, "TherMoire AXP" manufactured by Akrometrix Corporation can be cited. By making the right side value of condition (3) the above suitable value, even in the case where the (t1 + t2) / Z ratio is further reduced while the thickness Z of the printed wiring board is reduced, the warpage of the printed wiring board in the mounting process can be suppressed to 48 μm or less, 46 μm or less, 44 μm or less, 42 μm or less, or 40 μm or less.

[0058] [Resin sheet group for solder resist layer of printed wiring board]

[0059] The printed wiring board of the present application can be manufactured by providing first and second solder resist layers having specific thickness and elastic modulus on both sides of a circuit substrate.

[0060] Hereinafter, a group of resin sheets (also referred to as "resin sheet group") that can be used in manufacturing the printed wiring board of the present application will be described.

[0061] The resin sheet group for the solder resist layer of the printed wiring board of the present application is characterized by comprising:

[0062] a first resin sheet including a first support and a first resin composition layer joined to the first support; and a second resin sheet including a second support and a second resin composition layer joined to the second support, the thickness of the first resin composition layer being set to the elastic modulus after curing (23°C) being set to G1 (GPa), the thickness of the second resin composition layer being set to the elastic modulus after curing (23°C) being set to G2 (GPa), the thickness of the printed wiring board being set to Z (μm), the following conditions (1') to (3') are satisfied:

[0063] (1') Z < 250;

[0064] (2') and

[0065] (3')

[0066] G1 is 6 or more.

[0067] By using the resin sheet set to form the first and second solder resist layers, the printed wiring board of the present application satisfying conditions (1), (2) and (3) can be easily manufactured.

[0068] Condition (1') corresponds to the above condition (1). The suitable range of Z is as shown in the description of condition (1).

[0069] Condition (2') corresponds to the above condition (2). When the resin composition layer is laminated on the circuit substrate to form the solder resist layer, the thickness of the resulting solder resist layer is usually thicker than the thickness of the resin composition layer due to the presence of the surface circuit of the circuit substrate. Therefore, by satisfying condition (2'), condition (2) can be easily satisfied regardless of the thickness of the surface circuit of the circuit substrate or the density of the surface circuit. In condition (2'), in determining the suitable range of the ratio of , "t1" and "t2" in condition (2) can be replaced by and respectively. Similarly, in determining the suitable range of and , the suitable range of "t1" and "t2" in the above condition (2) can be replaced by and respectively. It should be noted that, in determining and , they are determined to be the same as or thicker than the thickness of the surface circuit of the circuit substrate.

[0070] Condition (3') corresponds to the above condition (3). As described above, the elastic modulus (23°C) after curing of the solder resist layer means the elastic modulus (23°C) after curing of the resin composition used to constitute the solder resist layer, and the suitable ranges of G1and G2are as described for condition (3). Further, the suitable ranges of the right-hand values of condition (3') are as described for condition (3).

[0071] From the viewpoint of further suppressing warping of the printed wiring board in the mounting process, it is preferable that the elastic modulus (200°C) after curing of the first and second resin composition layers be set to G1'(GPa) and G2'(GPa), respectively, and the following condition (4') be satisfied:

[0072] (4')

[0073] As for the suitable ranges of the right-hand values of condition (4'), as described for condition (4), the suitable ranges of G1'and G2'are as described for condition (4).

[0074] <RESIN COMPOSITION>

[0075] The resin composition for the first and second resin composition layers can be either a thermosetting resin composition or a photocurable resin composition, as long as it exhibits the above-mentioned specific modulus of elasticity after curing and has sufficient chemical resistance and insulation. For example, as the thermosetting resin composition, a resin composition containing a thermosetting resin and a curing agent can be exemplified. As the thermosetting resin, a conventionally known thermosetting resin used in forming a solder resist layer of a printed wiring board can be used, of which an epoxy resin is preferred. Thus, in one embodiment, the thermosetting resin composition for the first and second resin composition layers contains (a) an epoxy resin and (b) a curing agent. Further, a suitable photocurable resin composition can be formed by further adding a photocurable resin to the above-mentioned thermosetting resin composition. As the photocurable resin, a conventionally known photocurable resin used in forming a solder resist layer of a printed wiring board can be used, of which a photocurable alkali-soluble resin is preferred from the viewpoint that opening formation by exposure and development (photolithography) can be easily performed. Thus, in one embodiment, the photocurable resin composition for the first and second resin composition layers contains (a) an epoxy resin, (b) a curing agent, and (c) a photocurable alkali-soluble resin. The photocurable resin composition can further contain one or more selected from (d) a photopolymerization initiator, (e) a photosensitizer, and (f) a diluent. Note that, in the present application, a resin composition in which opening formation by photolithography is possible, including a photocurable resin, is referred to as a "photocurable resin composition" even when it has thermosetting properties. The resin composition that can be used for the first and second resin composition layers, whether it is a thermosetting resin composition or a photocurable resin composition, can further contain additives such as (g) an inorganic filler, (h) a thermoplastic resin, (i) a curing accelerator, (j) a flame retardant, and (k) an organic filler, as needed.

[0076] Hereinafter, the epoxy resin, the curing agent, the photocurable alkali-soluble resin, the photopolymerization initiator, the photosensitizer, the diluent, and the additives, which are materials that can be used as the resin composition in the first and second resin composition layers, will be described.

[0077] - (a) Epoxy Resin -

[0078] As the epoxy resin, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, dicyclopentadiene type epoxy resin, trisphenol type epoxy resin, naphthol novolak type epoxy resin, phenol novolak type epoxy resin, t-butyl- catechol type epoxy resin, naphthalene type epoxy resin, naphthol type epoxy resin, anthracene type epoxy resin, glycidyl amine type epoxy resin, glycidyl ester type epoxy resin, cresol novolak type epoxy resin, biphenyl type epoxy resin, linear aliphatic epoxy resin, epoxy resin having a butadiene structure, alicyclic epoxy resin, heterocyclic epoxy resin, epoxy resin containing a spiro ring, cyclohexane dimethanol type epoxy resin, naphthylene ether type epoxy resin, and trimethylol type epoxy resin, etc. can be exemplified. The epoxy resin can be used singly one kind, or two or more kinds can be used in combination.

[0079] It is preferable that the epoxy resin comprises an epoxy resin having two or more epoxy groups in one molecule. It is preferable that at least 50% by mass or more, based on 100% by mass of the non-volatile component of the epoxy resin, is an epoxy resin having two or more epoxy groups in one molecule. Among them, it is preferable to comprise an epoxy resin having two or more epoxy groups in one molecule and being in a liquid state at a temperature of 20°C (hereinafter referred to as "liquid epoxy resin"), and an epoxy resin having three or more epoxy groups in one molecule and being in a solid state at a temperature of 20°C (hereinafter referred to as "solid epoxy resin"). By using a combination of a liquid epoxy resin and a solid epoxy resin as the epoxy resin, a resin composition having excellent flexibility can be obtained. Also, the breaking strength of the solder resist layer formed by curing the resin composition is improved. In particular, in the case where the resin composition is a thermosetting resin composition, it is preferable to use a combination of a liquid epoxy resin and a solid epoxy resin. In the case where the resin composition is a photocurable resin composition, it is preferable to use a solid epoxy resin as the epoxy resin.

[0080] As the liquid epoxy resin, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a phenol novolac type epoxy resin, and a naphthalene type epoxy resin are preferred, and a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, and a naphthalene type epoxy resin are more preferred. As specific examples of the liquid epoxy resin, "HP4032", "HP4032D", "HP4032SS" (naphthalene type epoxy resin) manufactured by DIC Corporation; "jER828EL" (bisphenol A type epoxy resin), "jER807" (bisphenol F type epoxy resin), "jER152" (phenol novolac type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "ZX1059" (mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin) manufactured by Nippon Steel Chemical Co., Ltd.; "EX-721" (glycidyl ester type epoxy resin) manufactured by Nagasechemtex Corporation can be listed. These liquid epoxy resins can be used singly or two or more kinds can be used in combination.

[0081] As the solid epoxy resin, a naphthalene type tetrafunctional epoxy resin, a cresol novolac type epoxy resin, a dicyclopentadiene type epoxy resin, a triphenol type epoxy resin, a naphthol novolac type epoxy resin, a biphenyl type epoxy resin, or a naphthalene ether type epoxy resin are preferred, a naphthalene type tetrafunctional epoxy resin, a biphenyl type epoxy resin, or a naphthalene ether type epoxy resin are more preferred, and a naphthalene type tetrafunctional epoxy resin, a biphenyl type epoxy resin are further preferred. As specific examples of the solid epoxy resin, "HP-4700", "HP-4710" (naphthalene type tetrafunctional epoxy resin), "N-690" (cresol novolac type epoxy resin), "N-695" (cresol novolac type epoxy resin), "HP-7200" (dicyclopentadiene type epoxy resin), "EXA7311", "EXA7311-G3", "EXA7311-G4", "EXA7311-G4S", "HP6000" (naphthalene ether type epoxy resin) manufactured by DIC Corporation; "EPPN-502H" (triphenol epoxy resin), "NC7000L" (naphthol novolac epoxy resin), "NC3000H", "NC3000", "NC3000L", "NC3100" (biphenyl type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "ESN475" (naphthol novolac type epoxy resin), "ESN485V" (naphthol novolac type epoxy resin) manufactured by Nippon Steel Chemical Co., Ltd.; "YX4000H", "YL6121" (biphenyl type epoxy resin), "YX4000HK" (xylenol type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "PG-100", "CG-500" manufactured by Osaka Gas Chemicals Co., Ltd.; "YL7800" (fluorene type epoxy resin) manufactured by Mitsubishi Chemical Corporation, and the like can be listed.

[0082] In the case where a liquid epoxy resin and a solid epoxy resin are used in combination as the epoxy resin, the amount ratio (liquid epoxy resin : solid epoxy resin) is preferably in the range of 1 : 0.1 to 1 : 4 in terms of mass ratio. By making the amount ratio of the liquid epoxy resin and the solid epoxy resin in this range, the following effects can be obtained: i) moderate tackiness can be produced in the case of use in the form of a resin sheet; ii) sufficient flexibility can be obtained and the workability is improved in the case of use in the form of a resin sheet; and iii) a solder resist layer or the like having sufficient breaking strength can be obtained. From the viewpoint of the effects of i) to iii) above, the amount ratio of the liquid epoxy resin and the solid epoxy resin (liquid epoxy resin : solid epoxy resin) is more preferably in the range of 1 : 0.3 to 1 : 3.5 in terms of mass ratio, further preferably in the range of 1 : 0.6 to 1 : 3 in terms of mass ratio, and particularly preferably in the range of 1 : 0.8 to 1 : 2.5 in terms of mass ratio.

[0083] The content of the epoxy resin in the resin composition is preferably 3% by mass or more, more preferably 5% by mass or more, and further preferably 7% by mass or more or 9% by mass or more. There is no particular limitation on the upper limit of the content of the epoxy resin, but it is preferably 50% by mass or less, more preferably 45% by mass or less, and further more preferably 40% by mass or less or 35% by mass or less.

[0084] Note that, in the present application, the content of each component constituting the resin composition is a value when the total amount of nonvolatile components in the resin composition is 100% by mass.

[0085] The epoxy equivalent of the epoxy resin is preferably in the range of 50 to 3000, more preferably in the range of 80 to 2000, and further preferably in the range of 110 to 1000. By making the epoxy equivalent in this range, a solder resist layer having sufficient crosslinking density and excellent heat resistance can be obtained. Note that the epoxy equivalent refers to the mass of a resin containing one equivalent of an epoxy group, and can be measured in accordance with JIS K7236.

[0086] The weight average molecular weight of the epoxy resin is preferably in the range of 100 to 5000, more preferably in the range of 250 to 3000, and further preferably in the range of 400 to 1500. Here, the weight average molecular weight of the epoxy resin refers to the polystyrene-converted weight average molecular weight measured by a gel permeation chromatography (GPC) method.

[0087] (b) Curing agent

[0088] The curing agent is not particularly limited as long as it has a function of curing the epoxy resin, and examples thereof include phenol-based curing agents, naphthol-based curing agents, active ester-based curing agents, benzoxazine-based curing agents, and cyanate-based curing agents. The curing agent can be used alone or two or more kinds thereof can be used in combination.

[0089] As the phenolic curing agent and the naphthol curing agent, from the viewpoint of obtaining a solder resist layer excellent in heat resistance and water resistance, a phenolic curing agent having a novolak structure, or a naphthol curing agent having a novolak structure is preferred. In addition, from the viewpoint of obtaining a solder resist layer excellent in adhesion to a circuit board, a nitrogen-containing phenolic curing agent, more preferably a phenolic curing agent containing a triazine skeleton is preferred. Among them, from the viewpoint of obtaining a solder resist layer highly satisfying heat resistance, water resistance, and adhesion to a circuit board, a phenolic curing agent containing a triazine skeleton is preferred.

[0090] As specific examples of the phenolic curing agent and the naphthol curing agent, for example, "MEH-7700", "MEH-7810", "MEH-7851" manufactured by Meiwa Plastic Industries, Ltd.; "NHN", "CBN", "GPH" manufactured by Japan Epoxy Resin Co., Ltd.; "SN170", "SN180", "SN190", "SN475", "SN485", "SN495", "SN375", "SN395" manufactured by Tokyo Ohka Kogyo Co., Ltd.; "LA7052", "LA7054", "LA3018" manufactured by DIC Corporation, and the like can be listed.

[0091] From the viewpoint of obtaining a solder resist layer having excellent heat resistance, an active ester-based curing agent is also preferable. The active ester-based curing agent is not particularly limited, but generally, a compound having two or more ester groups having high reactivity in one molecule, such as phenol esters, thiophenol esters, N-hydroxy amine esters, esters of heterocyclic hydroxyl compounds, and the like, is preferably used. The active ester-based curing agent is preferably an active ester-based curing agent obtained by condensation reaction of a carboxylic acid compound and / or a thiocarboxylic acid compound with a hydroxyl compound and / or a mercaptan compound. In particular, from the viewpoint of improving heat resistance, an active ester-based curing agent obtained from a carboxylic acid compound and a hydroxyl compound is preferable, and an active ester-based curing agent obtained from a carboxylic acid compound and a phenol compound and / or a naphthol compound is more preferable. As the carboxylic acid compound, for example, benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, pyromellitic acid, and the like can be exemplified. As the phenol compound or the naphthol compound, for example, hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalein, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, a-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucinol, pyrogallol, dicyclopentadiene-type biphenol compounds, phenol novolacs, and the like can be exemplified. Here, the "dicyclopentadiene-type biphenol compound" refers to a biphenol compound obtained by condensing two molecules of phenol in one molecule of dicyclopentadiene.

[0092] Specifically, an active ester compound containing a dicyclopentadiene-type biphenol structure, an active ester compound containing a naphthalene structure, an active ester compound containing an acetylated product of a phenol novolac, and an active ester compound containing a benzoylated product of a phenol novolac are preferable, and among them, an active ester compound containing a naphthalene structure and an active ester compound containing a dicyclopentadiene-type biphenol structure are more preferable. The "dicyclopentadiene-type biphenol structure" refers to a divalent structural unit consisting of phenylene-dicyclopentadiene-phenylene.

[0093] As commercially available products of active ester-based curing agents, active ester compounds containing a dicyclopentadiene type biphenol structure can be exemplified by "EXB9451", "EXB9460", "EXB9460S", "HPC-8000-65T" (manufactured by DIC Corporation); active ester compounds containing a naphthalene structure can be exemplified by "EXB9416-70BK" (manufactured by DIC Corporation); active ester compounds containing acetylated products of phenol novolak can be exemplified by "DC808" (manufactured by Mitsubishi Chemical Corporation); active ester compounds containing benzoylated products of phenol novolak can be exemplified by "YLH1026" (manufactured by Mitsubishi Chemical Corporation); and the like.

[0094] As specific examples of benzoxazine-based curing agents, "HFB2006M" (manufactured by Showa Highpolymer Co., Ltd.), "P-d", "F-a" (manufactured by Shikoku Chemicals Corporation) can be exemplified.

[0095] As cyanate-based curing agents, for example, difunctional cyanate ester resins such as bisphenol A dicyanate, polyphenol cyanate, oligo(3-methylene-l,5-phenylene cyanate), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylenediphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanatophenyl)propane, 1,1-bis(4-cyanatophenyl)methane, bis(4-cyanato-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanatophenyl-l-(methyl ethylene))benzene, bis(4-cyanatophenyl)sulfide, and bis(4-cyanatophenyl)ether, polyfunctional cyanate ester resins derived from phenol novolak and cresol novolak, and the like, and prepolymers formed by partially triazinizing these cyanate ester resins can be exemplified. As specific examples of cyanate-based curing agents, "PT30" and "PT60" (both are phenol novolak type polyfunctional cyanate ester resins), "BA230" (a prepolymer formed by partially or completely triazinizing bisphenol A dicyanate into a trimer), and the like (manufactured by Lonza Japan Co., Ltd.) can be exemplified.

[0096] The amount ratio of the epoxy resin to the curing agent, in terms of the ratio of the total number of epoxy groups of the epoxy resin to the total number of reactive groups of the curing agent, is preferably in the range of 1 : 0.2 to 1 : 2, more preferably 1 : 0.3 to 1 : 1.5, and further preferably 1 : 0.4 to 1 : 1.2. Here, the reactive groups of the curing agent refer to active hydroxyl groups, active ester groups, and the like, and vary depending on the type of the curing agent. In addition, the total number of epoxy groups of the epoxy resin refers to the value obtained by totaling the values obtained by dividing the solid content mass of each epoxy resin by the epoxy equivalent for all of the epoxy resins; and the total number of reactive groups of the curing agent refers to the value obtained by totaling the values obtained by dividing the solid content mass of each curing agent by the reactive group equivalent for all of the curing agents. By having the amount ratio of the epoxy resin to the curing agent in the above range, the heat resistance of the solder resist layer obtained is further improved.

[0097] (c) a photocurable alkali-soluble resin

[0098] As the photocurable alkali-soluble resin, there is no particular limitation as long as it is a photocurable resin containing an alkali-soluble group (e.g., a carboxyl group, a phenolic hydroxyl group, or the like), and a conventionally known photocurable alkali-soluble resin used when forming a solder resist layer of a printed wiring board can be used. Among them, as the photocurable alkali-soluble resin, a resin containing an alkali-soluble group and a radically polymerizable unsaturated group is preferable, and a resin containing a carboxyl group and a radically polymerizable unsaturated group, a resin containing a phenolic hydroxyl group and a radically polymerizable unsaturated group are more preferable. The photocurable alkali-soluble resin can be used alone or two or more kinds can be used in combination.

[0099] As the resin containing a carboxyl group and a radically polymerizable unsaturated group, for example, an acid pendant type unsaturated epoxy ester resin formed by reacting an epoxy resin with an unsaturated carboxylic acid and then with an acid anhydride, or the like can be exemplified.

[0100] As the epoxy resin, the same epoxy resins as those of the (a) component can be used, and from the viewpoint of obtaining good developability and insulation reliability, a bisphenol F type epoxy resin, a bisphenol A type epoxy resin, a cresol novolak type epoxy resin are preferable, and a bisphenol F type epoxy resin, a cresol novolak type epoxy resin are more preferable. The epoxy resin can be used alone or two or more kinds can be used in combination.

[0101] As the unsaturated carboxylic acid, for example, acrylic acid, methacrylic acid, cinnamic acid, crotonic acid, and the like can be exemplified, and from the viewpoint of obtaining good photocuring properties, acrylic acid, methacrylic acid are preferable. The unsaturated carboxylic acid can be used alone or two or more kinds can be used in combination.

[0102] As the carboxylic anhydride, for example, maleic anhydride, succinic anhydride, itaconic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic dianhydride, and the like can be exemplified, and from the viewpoint of obtaining good developability and insulation reliability, succinic anhydride and tetrahydrophthalic anhydride are preferred. The anhydride can be used singly or two or more kinds can be used in combination.

[0103] The acid side group type unsaturated epoxy ester resin can be obtained by reacting an unsaturated carboxylic acid with an epoxy resin in the presence of a catalyst to form an unsaturated epoxy ester resin, and reacting the unsaturated epoxy ester resin with an anhydride. The reaction is a publicly known technique, and the reaction conditions such as the reaction temperature, the reaction time, the kind or the amount of the catalyst can be appropriately determined by those skilled in the art.

[0104] The acid side group type unsaturated epoxy ester resin can be used commercially available. As the commercially available product, for example, "ZFR-1533H" (a reaction product of a bisphenol F type epoxy resin, acrylic acid, and tetrahydrophthalic anhydride), "ZAR-2000" (a reaction product of a bisphenol A type epoxy resin, acrylic acid, and succinic anhydride) manufactured by Nippon Kayaku Co., Ltd., "PR-3000" (a reaction product of a cresol novolak type epoxy resin, acrylic acid, and a carboxylic anhydride) manufactured by Showa Denko K.K., and the like can be exemplified.

[0105] The resin containing a phenolic hydroxyl group and a radically polymerizable unsaturated group can be synthesized, for example, by reacting a resin containing a phenolic hydroxyl group with a compound containing a radically polymerizable unsaturated group and an isocyanate group.

[0106] As the resin containing a phenolic hydroxyl group, for example, phenol novolak resin, cresol novolak resin, bisphenol A novolak resin, naphthol novolak resin can be exemplified, and from the viewpoint of obtaining good developability and insulation reliability, phenol novolak resin and cresol novolak resin are preferred. The resin containing a phenolic hydroxyl group can be used singly or two or more kinds can be used in combination.

[0107] As the compound containing a radical-polymerizable unsaturated group and an isocyanate group, for example, (meth)acryloyl isocyanate; isocyanate (meth)acrylate ethyl ester (isocyanate ethyl (meth)acrylate); and a reaction product obtained by subjecting a polyisocyanate compound to a partial addition reaction with a (meth)acrylate compound having a functional group capable of reacting with an isocyanate group (for example, a hydroxyl group), and the like can be exemplified. Here, as the polyisocyanate compound, for example, 3-isocyanate-3, 5, 5-trimethylcyclohexyl isocyanate, toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, methylene diphenyl isocyanate, poly-methylene polyphenyl polyisocyanate, and the like can be exemplified; and as the (meth)acrylate compound having a functional group capable of reacting with an isocyanate group, for example, pentaerythritol tri(meth)acrylate, 2-hydroxyethyl (meth)acrylate, N-methylol acrylamide, glycerol di(meth)acrylate, dipentaerythritol penta(meth)acrylate, and the like can be exemplified.

[0108] The resin containing a phenolic hydroxyl group and a radical-polymerizable unsaturated group can be obtained by reacting a resin containing a phenolic hydroxyl group with a compound containing a radical-polymerizable unsaturated group and an isocyanate group in the presence of a catalyst. The reaction is a publicly known technique, and the reaction conditions such as the reaction temperature, the reaction time, the kind or the amount of the catalyst, and the like can be appropriately determined by those skilled in the art.

[0109] From the viewpoint of obtaining a good clarity, the number average molecular weight (Mn) of the polystyrene conversion of the photocurable alkali-soluble resin is preferably from 500 to 1,000,000, more preferably from 1,000 to 50,000, and further preferably from 1,500 to 35,000. The Mn of the photocurable alkali-soluble resin can be measured, for example, by a gel permeation chromatography (GPC) method. The measurement is performed by a (GPC) method (polystyrene conversion). The Mn can be calculated, for example, using LC-9A / RID-6A manufactured by Shimadzu Corporation as a measuring device, using Shodex K-800P / K-804L / K-804L manufactured by Showa Denko K.K. as a column, using chloroform or the like as a mobile phase, performing the measurement at a column temperature of 40°C, and calculating by using a standard curve of a standard polystyrene.

[0110] From the viewpoint of obtaining a solder resist layer exhibiting good insulation reliability, the solid content acid value of the photocurable alkali-soluble resin is preferably 100 mgKOH / g or less, more preferably 90 mgKOH / g or less, and further preferably 80 mgKOH / g or less or 70 mgKOH / g or less. The solid content acid value is preferably further reduced as long as sufficient developability is obtained, and from this viewpoint, a resin containing a phenolic hydroxyl group and a radically polymerizable unsaturated group is particularly preferable as the photocurable alkali-soluble resin.

[0111] From the viewpoint of obtaining good developability, the content of the photocurable alkali-soluble resin in the resin composition is preferably 10% by mass or more, more preferably 15% by mass or more, and further preferably 20% by mass or more. From the viewpoint of obtaining a solder resist layer that is excellent in heat resistance, the upper limit of the content of the photocurable alkali-soluble resin is preferably 60% by mass or less, more preferably 50% by mass or less, and further preferably 40% by mass or less.

[0112] (d) a photopolymerization initiator

[0113] As the photopolymerization initiator, there is no particular limitation, and for example, 2-benzyl-2-dimethylamino-l-(4-morpholinophenyl)-l-butanone, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-[4-(4-morpholinyl)phenyl]-l-butanone, 2-methyl-[4-(methylthio)phenyl]-morpholino-l-propanone, benzophenone, methylbenzophenone, o-benzoylbenzoic acid, benzoyl ethyl ether, 2,2-diethoxyacetophenone, 2,4-diethylthioxanthone, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, ethyl-(2,4,6-trimethylbenzoyl)phenylphosphinic acid ester, 4,4'-bis(dimethylamino)benzophenone, l-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-l,2-diphenylethane-l-one, l-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-l-propane-l-one and the like alkylphenone-based photopolymerization initiators; bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide and the like acylphosphine oxide-based photopolymerization initiators; l-[4-(phenylthio)-l,2-octanedione 2-(O-benzoyl oxime)] and l-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-ethanone l-(O-acetyl oxime) and the like oxime ester-based photopolymerization initiators; and the like, and the acylphosphine oxide-based photopolymerization initiators, the oxime ester-based photopolymerization initiators are preferred. The photopolymerization initiator can be used alone or two or more kinds can be used in combination.

[0114] As the commercially available product of the photopolymerization initiator, for example, "IRGACURE 819" (bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide), "IRGACURE 907" (2-methyl-[4-(methylthio)phenyl]-morpholino-l-propanone), "OXE-01" (l-[4-(phenylthio)-l,2-octanedione 2-(O-benzoyl oxime)], "OXE-02" (l-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-ethanone l-(O-acetyl oxime)) and the like manufactured by BASF JAPAN Co., Ltd. are exemplified.

[0115] The content of the photopolymerization initiator in the resin composition is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and further preferably 0.3% by mass or more, from the viewpoint of obtaining good photocuring properties and insulating reliability. The upper limit of the content of the photopolymerization initiator is preferably 2% by mass or less, more preferably 1.5% by mass or less, and further preferably 1% by mass or less, from the viewpoint of being able to prevent a decrease in dimensional stability due to excessively high sensitivity.

[0116] -(e) photosensitizer

[0117] As the photosensitizer, for example, tertiary amines, pyrazolines, anthracenes, coumarins, xanthones, thioxanthones, and the like can be given, with thioxanthones being preferred, and 2,4-diethylthioxanthone being more preferred. The photosensitizer can be used singly or two or more kinds can be used in combination. As a commercially available product of the photosensitizer, for example, "DETX-S" (2,4-diethylthioxanthone) manufactured by Wako Pure Chemical Industries, Ltd. can be given.

[0118] The content of the photosensitizer in the resin composition is preferably 0.01% by mass or more to 1% by mass or less, and more preferably 0.05% by mass or more to 0.5% by mass or less, from the viewpoint of obtaining good photocuring properties.

[0119] -(f) diluent

[0120] The diluent is used to promote the photocuring reaction of the resin composition. As the diluent, for example, photosensitive (meth)acrylate compounds having one or more (meth)acryloyl groups in the molecule, which are liquid, solid, or semi-solid at room temperature, can be given.

[0121] As representative photosensitive (meth)acrylate compounds, for example, hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 2-hydroxybutyl acrylate; mono- or di-acrylates of diol compounds such as ethylene glycol, methoxytetraethylene glycol, polyethylene glycol, propylene glycol, tricyclodecane dimethanol, and the like; acrylamides such as N,N-dimethylacrylamide and N-hydroxymethylacrylamide; aminoalkyl acrylates such as N,N-dimethylaminoethyl acrylate; polyacrylates of polyhydric alcohols such as trimethylolpropane, pentaerythritol, di-pentaerythritol, and the like, or oxirane, oxetane, or ε-caprolactone adducts thereof; acrylates such as phenoxy acrylate, phenoxyethyl acrylate, and the like, or oxirane or oxetane adducts thereof; epoxy acrylates derived from glycidyl ethers such as trimethylolpropane triglycidyl ether; melamine acrylates; and / or methacrylates corresponding to the above acrylates, and the like can be given. Of these, mono- or di-(meth)acrylates of diol compounds, poly(meth)acrylates are preferred.

[0122] The diluent can be used singly or in combination of two or more. As commercially available products of the diluent, for example, "DPHA" (dipentaerythritol hexaacrylate) manufactured by Nippon Shokubai Co., Ltd., "DCPA" (tricyclodecane dimethanol diacrylate) manufactured by Kyoeisha Chemical Co., Ltd., and the like can be exemplified.

[0123] From the viewpoint of promoting the photocuring reaction and the viewpoint of preventing the cured product from becoming tacky, the content of the diluent in the resin composition is preferably from 0.5 to 10% by mass, and more preferably from 2 to 8% by mass.

[0124] (g) Inorganic Filler

[0125] As the inorganic filler, for example, the following can be exemplified: silica, alumina, glass, cordierite, silicon oxide, barium sulfate, talc, clay, mica powder, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, barium titanate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate, and the like. Among them, amorphous silica, fused silica, crystalline silica, synthetic silica, hollow silica, and the like are particularly suitable. In addition, as the silica, spherical silica is preferred. The inorganic filler can be used singly or in combination of two or more. As commercially available products of the spherical fused silica, for example, "SOC1", "SOC2", "SOC3", and "SOC4" manufactured by Admatechs Co., Ltd., "UFP-30", "UFP-80" manufactured by Eichen Chemical Industry Co., Ltd. can be exemplified.

[0126] The average particle size of the inorganic filler material is not particularly limited and can be appropriately determined according to the desired characteristics. From the viewpoint of improving the dispersibility of the inorganic filler material, the average particle size of the inorganic filler material is preferably 0.01 μm or more, more preferably 0.05 μm or more. From the viewpoint of obtaining sufficient insulation reliability, the average particle size of the inorganic filler material is preferably 4 μm or less, more preferably 3 μm or less, further preferably 2 μm or less, and even more preferably 1 μm or less. It should be noted that when the resin composition is a photocurable resin composition, from the viewpoint of obtaining good photocuring properties, the upper limit of the average particle size of the inorganic filler material is preferably 1 μm or less, more preferably 0.8 μm or less, and even more preferably 0.6 μm or less or 0.4 μm or less. The average particle size of the inorganic filler material can be determined using laser diffraction scattering based on the Mie scattering theory. Specifically, the particle size distribution of the inorganic filler material can be prepared on a volume basis using a laser diffraction scattering particle size distribution measuring device, and the median particle diameter can be measured as the average particle size. The sample used for measurement is preferably a sample formed by dispersing inorganic filler material in water using ultrasound. As a laser diffraction scattering particle size distribution measuring device, the "LA-500" manufactured by Horiba Corporation can be used.

[0127] From the perspective of improving moisture resistance and dispersibility, inorganic filler materials are preferably treated with one or more surface treatment agents, such as aminosilane coupling agents, epoxysilane coupling agents, mercaptosilane coupling agents, silane coupling agents, organosilazane compounds, and titanate coupling agents. Commercially available surface treatment agents include, for example, "KBM403" (3-epoxypropoxypropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., "KBM803" (3-mercaptopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., "KBE903" (3-aminopropyltriethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., and "SZ-31" (hexamethyldisilazane) manufactured by Shin-Etsu Chemical Industry Co., Ltd.

[0128] The degree of surface treatment by the surface treatment agent can be evaluated by the carbon content per unit surface area of ​​the inorganic filler. From the viewpoint of improving the dispersibility of the inorganic filler, the carbon content per unit surface area of ​​the inorganic filler is preferably 0.02 mg / m². 2 The above, more preferably 0.1 mg / m 2 The above is further preferred to be 0.2 mg / m³. 2 That's all. On the other hand, from the viewpoint of preventing an increase in the melt viscosity or melt viscosity in flake form of the resin varnish, 1 mg / m³ is preferred.2 Further preferably, the above is 0.8 mg / m 2 Further preferably, the above is 0.5 mg / m 2 Further preferably, the above is 0.5 mg / m

[0129] The amount of carbon per unit surface area of the inorganic filler can be measured by washing the inorganic filler after surface treatment with a solvent (e.g., methyl ethyl ketone (MEK)) and then measuring. Specifically, a sufficient amount of MEK as a solvent can be added to the inorganic filler after surface treatment with a surface treatment agent, and the mixture can be ultrasonically washed at 25°C for 5 minutes, the supernatant can be removed, and the solid component can be dried, and then the amount of carbon per unit surface area of the inorganic filler can be measured using a carbon analyzer. As the carbon analyzer, "EMIA-320V" manufactured by HORIBA, Ltd., or the like can be used.

[0130] The content of the inorganic filler in the resin composition is not particularly limited as long as a solder resist layer exhibiting a desired elastic modulus can be obtained. Although it also depends on the type of the epoxy resin or the curing agent, if the content of the inorganic filler in the resin composition is increased, the elastic modulus after curing of the resin composition tends to increase. For example, in the case of forming a resin composition layer exhibiting a high elastic modulus (23°C) of 6 GPa or more after curing, and further forming a solder resist layer, the content of the inorganic filler in the resin composition is preferably 60% by mass or more. In the case of forming a resin composition layer exhibiting a higher elastic modulus (23°C) after curing, and further forming a solder resist layer, the content of the inorganic filler in the resin composition is more preferably 65% by mass or more, and further preferably 70% by mass or more or 75% by mass or more.

[0131] In one embodiment, the content of the inorganic filler in the resin composition for the first resin composition layer and further for the first solder resist layer is preferably 60% by mass or more, more preferably 65% by mass or more, and further preferably 70% by mass or more or 75% by mass or more. The upper limit of the content of the inorganic filler in the resin composition for the first resin composition layer is not particularly limited, but from the viewpoint of the mechanical strength of the obtained solder resist layer, it can generally be 95% by mass or less, 90% by mass or less, or the like.

[0132] The content of the inorganic filler in the resin composition for the second resin composition layer and further for the second solder resist layer is appropriately determined in the range of 0% by mass to 95% by mass, more preferably in the range of 20% by mass to 85% by mass, as long as a second solder resist layer exhibiting a desired elastic modulus can be obtained, depending on the desired properties.

[0133] In a preferable embodiment, the resin composition for the first resin composition layer is a thermosetting resin composition, which contains the above-mentioned (a) epoxy resin, (b) curing agent, and (g) inorganic filler. In this embodiment, it is preferable that, in the thermosetting resin composition for the first resin composition layer, a mixture of liquid epoxy resin and solid epoxy resin (the mass ratio of liquid epoxy resin : solid epoxy resin is preferably in the range of 1 : 0.1 to 1 : 4, more preferably in the range of 1 : 0.3 to 1 : 3.5, further preferably in the range of 1 : 0.6 to 1 : 3, further more preferably in the range of 1 : 0.8 to 1 : 2.5) is contained as the (a) epoxy resin; one or more selected from the group consisting of phenol-based curing agents, naphthol-based curing agents, active ester-based curing agents, and cyanate-based curing agents (preferably one or more selected from the group consisting of phenol-based curing agents, naphthol-based curing agents, and active ester-based curing agents) is contained as the (b) curing agent; and silica is contained as the (g) inorganic filler. As to the thermosetting resin composition containing the above-mentioned specific components, the suitable contents of (a) epoxy resin, (b) curing agent, and (g) inorganic filler are as described above.

[0134] In the preferable other embodiment, the resin composition for the first resin composition layer is a photocurable resin composition, and contains the above-mentioned (a) epoxy resin, (b) curing agent, (c) photocurable alkali-soluble resin, and (g) inorganic filler. In this embodiment, it is preferable that, in the photocurable resin composition for the first resin composition layer, a mixture of liquid epoxy resin and solid epoxy resin (the mass ratio of liquid epoxy resin : solid epoxy resin is preferably in the range of 1 : 0.1 to 1 : 4, more preferably in the range of 1 : 0.3 to 1 : 3.5, further preferably in the range of 1 : 0.6 to 1 : 3, further more preferably in the range of 1 : 0.8 to 1 : 2.5) is contained as the (a) epoxy resin, or only solid epoxy resin is contained as the (a) epoxy resin; one or more selected from the group consisting of phenol-based curing agent, naphthol-based curing agent, active ester-based curing agent, and cyanate-based curing agent (preferably one or more selected from the group consisting of phenol-based curing agent, naphthol-based curing agent, and active ester-based curing agent) is contained as the (b) curing agent; a resin containing an alkali-soluble group and a radically polymerizable unsaturated group (preferably a resin containing a carboxyl group and a radically polymerizable unsaturated group, more preferably a resin containing a phenolic hydroxyl group and a radically polymerizable unsaturated group) is contained as the (c) photocurable alkali-soluble resin; and silica is contained as the (g) inorganic filler. As for the thermosetting resin composition containing the above-mentioned specific components, the suitable contents of (a) epoxy resin, (b) curing agent, (c) photocurable alkali-soluble resin, and (g) inorganic filler are as described above, but from the viewpoint of obtaining good heat resistance, insulation reliability, and developability, it is preferable that, when the nonvolatile component of the (c) photocurable alkali-soluble resin is 100 mass%, the (a) epoxy resin is preferably 5 mass% to 100 mass%, more preferably 10 mass% to 85 mass%. It should be noted that, in the case where the resin composition for the first resin composition layer is a photocurable resin composition, the photocurable resin composition further contains one or more selected from the group consisting of (d) photopolymerization initiator, (e) photosensitizer, and (f) diluent.

[0135] From the viewpoint of further suppressing warpage of the printed wiring board in the mounting process, the resin composition for the first resin composition layer and further for the first solder resist layer, whether it is a thermosetting resin composition or a photocurable resin composition, preferably has a glass transition temperature (Tg) after curing of 150°C or higher, more preferably 155°C or higher. The upper limit of the Tg is not particularly limited, but is typically 300°C or lower, 250°C or lower, or the like. The Tg of the resin composition after curing can be measured by thermomechanical analysis using a tensile load method. As a thermomechanical analysis device that can be used to measure the Tg of the resin composition after curing, for example, "Thermo Plus TMA8310" manufactured by Rigaku Corporation, "TMA-SS6100" manufactured by Seiko Instruments Inc. can be cited.

[0136] In a preferable embodiment, the resin composition for the second resin composition layer is a thermosetting resin composition containing the above-described (a) epoxy resin and (b) curing agent. In this embodiment, it is preferable that the thermosetting resin composition for the second resin composition layer contain, as the (a) epoxy resin, a mixture of a liquid epoxy resin and a solid epoxy resin (the mass ratio of the liquid epoxy resin : solid epoxy resin is preferably in the range of 1 : 0.1 to 1 : 4, more preferably in the range of 1 : 0.3 to 1 : 3.5, further preferably in the range of 1 : 0.6 to 1 : 3, further more preferably in the range of 1 : 0.8 to 1 : 2.5), and contain, as the (b) curing agent, one or more selected from the group consisting of phenol-based curing agents, naphthol-based curing agents, active ester-based curing agents, and cyanate-based curing agents (preferably one or more selected from the group consisting of phenol-based curing agents, naphthol-based curing agents, and active ester-based curing agents). With respect to the thermosetting resin composition containing the above-described specific components, the appropriate contents of the (a) epoxy resin and the (b) curing agent are as described above. As described above, in order to achieve the second solder resist layer that exhibits the desired modulus of elasticity, the thermosetting resin composition for the second resin composition layer can further contain (g) inorganic filler material (preferably silica) in an amount in the range of 0 mass% to 95 mass% in the resin composition. Here, with respect to the constituent components of the resin composition, the expression "in an amount in the range of 0 mass% to n mass%" means both the case where the constituent component is not contained and the case where the amount is in the range of n mass% or less.

[0137] In the preferable other embodiment, the resin composition for the second resin composition layer is a photocurable resin composition, which contains the above-mentioned (a) epoxy resin, (b) curing agent, and (c) alkali-soluble resin of the photocuring type. In this embodiment, it is preferable that the photocurable resin composition for the second resin composition layer contains a mixture of liquid epoxy resin and solid epoxy resin (the mass ratio of liquid epoxy resin : solid epoxy resin is preferably in the range of 1 : 0.1 to 1 : 4, more preferably in the range of 1 : 0.3 to 1 : 3.5, further preferably in the range of 1 : 0.6 to 1 : 3, further more preferably in the range of 1 : 0.8 to 1 : 2.5) as the (a) epoxy resin, or contains only solid epoxy resin as the (a) epoxy resin; contains one or more selected from the group consisting of phenol-based curing agent, naphthol-based curing agent, active ester-based curing agent, and cyanate-based curing agent (preferably one or more selected from the group consisting of phenol-based curing agent, naphthol-based curing agent, and active ester-based curing agent) as the (b) curing agent; and contains a resin containing an alkali-soluble group and a radically polymerizable unsaturated group (preferably a resin containing a carboxyl group and a radically polymerizable unsaturated group, a resin containing a phenolic hydroxyl group and a radically polymerizable unsaturated group, more preferably a resin containing a phenolic hydroxyl group and a radically polymerizable unsaturated group) as the (c) alkali-soluble resin of the photocuring type. As for the thermosetting resin composition containing the above-mentioned specific components, the suitable contents of (a) epoxy resin, (b) curing agent, and (c) alkali-soluble resin of the photocuring type are as described above, but from the viewpoint of obtaining good heat resistance, insulation reliability, and developability, it is preferable that, when the non-volatile component of (c) alkali-soluble resin of the photocuring type is 100 mass%, (a) epoxy resin is preferably 5 mass% to 100 mass%, more preferably 10 mass% to 85 mass%. It is preferable that, in the case where the resin composition for the second resin composition layer is a photocurable resin composition, the photocurable resin composition further contains one or more selected from the group consisting of (d) photopolymerization initiator, (e) photosensitizer, and (f) diluent. As described above, in order to achieve the second solder resist layer exhibiting the desired modulus of elasticity, the photocurable resin composition for the second resin composition layer can further contain (g) inorganic filler (preferably silica), the content of which in the resin composition is in the range of 0 mass% to 95 mass%.

[0138] The resin composition for the second resin composition layer, and further for the second solder resist layer, whether it is a thermosetting resin composition or a photocurable resin composition, has no particular limitation in the glass transition temperature (Tg) after curing, provided that the desired modulus of elasticity is obtained. From the viewpoint of being able to suppress warping of the printed wiring board during the mounting process, the Tg after curing of the resin composition for the second resin composition layer, and further for the second solder resist layer, is preferably 150°C or higher, more preferably 155°C or higher. The upper limit of this Tg is not particularly limited, and is typically 300°C or lower, 250°C or lower, or the like.

[0139] In a preferred embodiment, the resin composition for the first and second resin composition layers is a thermosetting resin composition. In another preferred embodiment, the resin composition for the first and second resin composition layers is a photocurable resin composition. In still another preferred embodiment, the resin composition for the first resin composition layer is a thermosetting resin composition, and the resin composition for the second resin composition layer is a photocurable resin composition. In yet another preferred embodiment, the resin composition for the first resin composition layer is a photocurable resin composition, and the resin composition for the second resin composition layer is a thermosetting resin composition.

[0140] -(h) thermoplastic resin-

[0141] The resin composition for the first and second resin composition layers can further include a thermoplastic resin. As the thermoplastic resin, any thermoplastic resin commonly used when forming a solder resist layer of a printed wiring board can be used, and examples thereof include phenoxy resin, polyvinyl acetal resin, polyolefin resin, polybutadiene resin, polyimide resin, polyamide-imide resin, polyether sulfone resin, polyphenylene ether resin, and polysulfone resin. The thermoplastic resin can be used alone or two or more kinds thereof can be used in combination.

[0142] The weight average molecular weight of the thermoplastic resin, in terms of polystyrene, is preferably in the range of 8000 to 70000, more preferably in the range of 10000 to 60000, and further preferably in the range of 20000 to 60000. The weight average molecular weight of the thermoplastic resin, in terms of polystyrene, can be measured by gel permeation chromatography (GPC). Specifically, the weight average molecular weight of the thermoplastic resin, in terms of polystyrene, can be calculated by using LC-9A / RID-6A manufactured by Shimadzu Corporation as a measuring device, using Shodex K-800P / K-804L / K-804L manufactured by Showa Denko K.K. as columns, using chloroform or the like as a mobile phase, measuring at a column temperature of 40°C, and calculating using a standard curve of a standard polystyrene.

[0143] The content of the thermoplastic resin in the resin composition is not particularly limited as long as a solder resist layer exhibiting a desired modulus of elasticity can be obtained, but is preferably 0.1% by mass or more, more preferably 1% by mass or more, and further preferably 3% by mass or more, 5% by mass or more, or 7% by mass or more. The upper limit of the content of the thermoplastic resin is not particularly limited, but is preferably 50% by mass or less, more preferably 40% by mass or less, and further preferably 30% by mass or less. Although it also depends on the kind of the epoxy resin or the curing agent, and the content of the inorganic filler, if the content of the thermoplastic resin in the resin composition is increased, the modulus of elasticity after curing of the resin composition tends to decrease.

[0144] -(i) curing accelerator-

[0145] The resin composition for the first and second resin composition layers can further contain a curing accelerator. As the curing accelerator, any curing accelerator commonly used when forming a solder resist layer of a printed wiring board can be used, and for example, phosphorus-based curing accelerators, amine-based curing accelerators, imidazole-based curing accelerators, guanidine-based curing accelerators, and the like can be listed, with phosphorus-based curing accelerators, amine-based curing accelerators, and imidazole-based curing accelerators being preferred, and amine-based curing accelerators and imidazole-based curing accelerators being more preferred. The curing accelerator can be used singly or in combination of two or more.

[0146] The content of the curing accelerator in the resin composition is not particularly limited as long as a solder resist layer exhibiting a desired modulus of elasticity can be obtained, but is preferably in the range of 0.03% by mass to 3% by mass, based on the total amount of the nonvolatile components of the epoxy resin and the curing agent being 100% by mass.

[0147] -(j) flame retardant-

[0148] The resin composition for the first and second resin composition layers can further contain a flame retardant. As the flame retardant, any flame retardant commonly used when forming a solder resist layer of a printed wiring board can be used, and for example, organic phosphorus-based flame retardants, organic nitrogen-containing phosphorus compounds, nitrogen compounds, organic silicon-based flame retardants, metal hydroxides, and the like can be listed. The flame retardant can be used singly or in combination of two or more. The content of the flame retardant in the resin composition is not particularly limited as long as a solder resist layer exhibiting a desired modulus of elasticity can be obtained, but is preferably 0.5% by mass to 20% by mass, and more preferably 1% by mass to 15% by mass.

[0149] -(k) organic filler-

[0150] The resin composition for the first and second resin composition layers can further contain an organic filler material. As the organic filler material, any organic filler material commonly used when forming a solder resist layer of a printed wiring board can be used, and for example, rubber particles, polyamide fine particles, silicone particles, and the like can be listed, with rubber particles being preferred.

[0151] As the rubber particles, there are no particular limitations as long as they are fine particles of a resin that exhibits rubber elasticity and that is chemically crosslinked and insoluble and unfusible in an organic solvent, and for example, acrylonitrile butadiene rubber particles, butadiene rubber particles, acrylic rubber particles, and the like can be listed. As the rubber particles, specifically, XER-91 (manufactured by Nippon Gomu Co., Ltd.), Stafiloid AC3355, AC3816, AC3816N, AC3832, AC4030, AC3364, IM101 (all manufactured by Ganz Cheikosha Co., Ltd.), PARALOID EXL2655, EXL2602 (both manufactured by Wako Chemical Industries, Ltd.), and the like can be listed.

[0152] The average particle diameter of the organic filler material is preferably in the range of 0.005 μm to 1 μm, and more preferably in the range of 0.2 μm to 0.6 μm. The average particle diameter of the organic filler material can be measured using a dynamic light scattering method. For example, it can be measured by uniformly dispersing the organic filler material in a suitable organic solvent using ultrasonic waves or the like, using a high concentration particle diameter analyzer (FPAR-1000; manufactured by Otsuka Electronics Co., Ltd.), preparing a particle size distribution of the organic filler material on a mass basis, and taking the median particle diameter as the average particle diameter.

[0153] The content of the organic filler material in the resin composition is not particularly limited as long as a solder resist layer that exhibits a desired modulus of elasticity can be obtained, but is preferably in the range of 0.1 mass% to 6 mass%, and more preferably in the range of 0.5 mass% to 4 mass%.

[0154] -Other Components-

[0155] The resin composition for the first and second resin composition layers can contain other additives as needed, and as the other additives, for example, organic metal compounds such as organic copper compounds, organic zinc compounds, and organic cobalt compounds; and resin additives such as thickening agents, defoaming agents, leveling agents, adhesion-imparting agents, and colorants can be listed.

[0156] <Support>

[0157] As the support, whether it is the first support or the second support, for example, a film formed of a plastic material, a metal foil, a release paper can be listed, with a film formed of a plastic material and a metal foil being preferred.

[0158] In the case of using a thin film formed of a plastic material as the support, as the plastic material, for example, polyester such as polyethylene terephthalate (hereinafter sometimes referred to as "PET"), polyethylene naphthalate (hereinafter sometimes referred to as "PEN"), polycarbonate (hereinafter sometimes referred to as "PC"), acrylic such as polymethyl methacrylate (PMMA), cyclic polyolefin, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, polyimide, and the like can be exemplified. Among them, polyethylene terephthalate and polyethylene naphthalate are preferable, and inexpensive polyethylene terephthalate is particularly preferable.

[0159] In the case of using a metal foil as the support, as the metal foil, for example, copper foil, aluminum foil, and the like can be exemplified, and copper foil is preferable. As the copper foil, a foil formed of a single metal of copper can be used, or a foil formed of an alloy of copper and another metal (for example, tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, and the like) can be used.

[0160] The surface of the support to which the resin composition layer is joined can be subjected to mat treatment or corona treatment. In addition, as the support, a support with a release layer having a release layer on the surface to which the resin composition layer is joined can be used. As the release agent used in the release layer of the support with a release layer, for example, a release agent selected from one or more of alkyd resin, polyolefin resin, polyurethane resin, and silicone resin can be exemplified.

[0161] As a commercially available product of the support, for example, "SK-1", "AL-5", "AL-7" manufactured by LINTEC Corporation; "NS80A" manufactured by Toray Industries, Inc.; "R310-16B" manufactured by Mitsubishi Chemical Corporation; and the like can be exemplified.

[0162] The thickness of the support is not particularly limited, but is preferably in the range of 5 μm to 75 μm, more preferably in the range of 10 μm to 60 μm, and further preferably in the range of 10 μm to 45 μm. Note that, in the case of using a support with a release layer, the overall thickness of the support with a release layer is preferably in the above range.

[0163] The resin sheet, whether it is the first resin sheet or the second resin sheet, can be prepared, for example, by dissolving a resin composition in an organic solvent to prepare a resin varnish, applying the resin varnish on a support using a metal coater or the like, and drying the resin varnish.

[0164] As the organic solvent, for example, there can be mentioned ketones such as acetone, methyl ethyl ketone and cyclohexanone; acetic acid esters such as ethyl acetate, butyl acetate, cellulose acetate, propylene glycol monomethyl ether acetate and carbitol acetate; carbitols such as cellulose and butyl carbitol; aromatic hydrocarbons such as toluene and xylene; amide solvents such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone. The organic solvent can be used singly or in combination of two or more kinds.

[0165] The drying of the resin varnish can be performed by a publicly known drying method such as heating or blowing hot air. Although it varies depending on the boiling point of the organic solvent in the resin varnish, in the case where the resin varnish containing, for example, 30 to 60 mass% of the organic solvent is used, the resin composition layer can be formed on the support by drying at 50 to 150°C for 3 to 10 minutes.

[0166] The resin sheet, either the first resin sheet or the second resin sheet, can further contain a protective film on the surface of the resin composition layer which is not bonded to the support (i.e., the surface on the opposite side of the support). The protective film is useful for preventing the surface of the resin composition layer from being attached with dust or being scratched. As the material of the protective film, the same material as described for the support can be used. The thickness of the protective film is not particularly limited, but for example, it can be 1 to 40 μm. In the manufacture of the printed wiring board, the protective film is peeled off and the resin sheet can be used.

[0167] [Method for manufacturing printed wiring board]

[0168] The method for manufacturing the printed wiring board of the present application is not particularly limited as long as a printed wiring board satisfying the above conditions (1), (2) and (3) can be obtained. Hereinafter, as a preferred embodiment of the method for manufacturing the printed wiring board of the present application, a method for manufacturing a printed wiring board using the above-mentioned set of resin sheets for solder resist layer of printed wiring board will be described.

[0169] In a preferred embodiment, the printed wiring board of the present application can be manufactured by a method comprising the following steps (I) to (III) using the above-mentioned set of resin sheets for solder resist layer of printed wiring board.

[0170] (I) a step of laminating a first resin sheet comprising a first support and a first resin composition layer bonded to the first support on the first main surface of the circuit substrate so that the first resin composition layer is bonded to the first main surface of the circuit substrate;

[0171] (II) a step of laminating a second resin sheet comprising a second support and a second resin composition layer bonded to the second support on the second main surface of the circuit substrate so that the second resin composition layer is bonded to the second main surface of the circuit substrate;

[0172] (III) a step of curing the first and second resin composition layers to form first and second solder resist layers.

[0173] - Step (I) -

[0174] In Step (I), a first resin sheet including a first support and a first resin composition layer bonded to the first support is laminated on the first main surface of the circuit board having first and second main surfaces, so that the first resin composition layer is bonded to the first main surface of the circuit board.

[0175] The first resin sheet used in Step (I) is as described above in the description of [Resin sheet set for solder resist layer of printed wiring board].

[0176] In the present application, the "circuit board" refers to a board on which solder resist layers are to be further formed on both surfaces thereof in the production of a printed wiring board, and examples thereof include a board having first and second main surfaces facing each other and having circuit wiring formed by pattern processing on both the first and second main surfaces. The layer structure represented by the number of layers of the circuit wiring is not particularly limited and can be appropriately determined in accordance with the characteristics of the desired printed wiring board.

[0177] The thickness of the circuit board is not particularly limited as long as a printed wiring board satisfying the above conditions (1) and (2) can be obtained, but is preferably 240 μm or less, more preferably 220 μm or less, and further preferably 200 μm or less. According to the present application, even when a thinner circuit board is used, the warpage of the printed wiring board in the mounting step can be suppressed. For example, even when a circuit board having a thickness of 190 μm or less, 180 μm or less, 170 μm or less, 160 μm or less, 150 μm or less, 140 μm or less, 130 μm or less, 120 μm or less, 110 μm or less, or 100 μm or less is used, the warpage in the mounting step can be suppressed. The lower limit of the thickness of the circuit board is not particularly limited, but is preferably 10 μm or more, and more preferably 20 μm or more, from the viewpoint of improving the operability in the production of the printed wiring board. It should be noted that the thickness of the circuit board refers to the thickness of the entire circuit board including the thickness of the surface circuit. Here, when the value other than the thickness of the surface circuit in the thickness of the circuit board is denoted as t3 (μm), the above Z, tl, t2, and t3 satisfy the relationship of tl + t2 + t3 = Z.

[0178] The thickness of the surface circuit of the circuit board is not particularly limited, but from the viewpoint of thinning the printed wiring board, it is preferably 40 μm or less, more preferably 30 μm or less, further preferably 25 μm or less, further more preferably 20 μm or less, 18 μm or less, 16 μm or less, 14 μm or less, 12 μm or less, or 10 μm or less. The lower limit of the thickness of the surface circuit is not particularly limited, but it can be generally 1 μm or more, 3 μm or more, 5 μm or more, or the like.

[0179] From the viewpoint of suppressing the occurrence of deformation or cracks of the circuit, the coefficient of thermal expansion of the circuit board is preferably 16 ppm / °C or less, more preferably 14 ppm / °C or less, further preferably 12 ppm / °C or less. The lower limit of the coefficient of thermal expansion of the circuit board is also dependent on the composition of the resin composition used to form the solder resist layer, but it is preferably -2 ppm / °C or more, more preferably 0 ppm / °C or more, further preferably 4 ppm / °C or more. In the present application, the coefficient of thermal expansion of the circuit board is the linear coefficient of thermal expansion in the planar direction at 25 to 150°C, and can be obtained by thermomechanical analysis (TMA) using a tensile load method. As a thermomechanical analysis device that can be used to measure the linear coefficient of thermal expansion of the circuit board, for example, "Thermo Plus TMA8310" manufactured by Rigaku Corporation or "TMA-SS6100" manufactured by Seiko Instruments Inc. can be cited.

[0180] The flexural modulus of the circuit board is not particularly limited. In the present application, the warping in the mounting process can be suppressed regardless of the flexural modulus of the circuit board.

[0181] The lamination of the circuit board and the first resin sheet can be performed, for example, by thermocompressing (heat-pressing) the first resin sheet on the circuit board from the first support side. As a member for thermocompressing the first resin sheet on the circuit board (hereinafter also referred to as "heat-pressing member"), for example, a heated metal plate (SUS end plate or the like) or a metal roller (SUS roller) or the like can be cited. Note that, instead of directly pressing the heat-pressing member on the first resin sheet, it is preferable to press the first resin sheet so as to sufficiently follow the unevenness generated by the surface circuit of the circuit board via an elastic material such as heat-resistant rubber.

[0182] The heat-pressing temperature is preferably in the range of 80°C to 160°C, more preferably 100°C to 140°C; the heat-pressing pressure is preferably in the range of 0.098 MPa to 1.77 MPa, more preferably 0.29 MPa to 1.47 MPa; and the heat-pressing time is preferably in the range of 20 seconds to 400 seconds, more preferably 30 seconds to 300 seconds. It is preferable that the lamination be performed under reduced pressure conditions of 26.7 hPa or less.

[0183] The lamination can be performed using a commercially available vacuum laminator. As commercially available vacuum laminators, for example, there are a vacuum press-type laminator manufactured by Seiko Instruments & Electronics Co., Ltd., a vacuum applicator manufactured by Nichigo-Morton Co., Ltd., and the like.

[0184] The smoothing treatment of the first adhesive sheet after the lamination can be performed by pressing the heat-pressing member from the first support side under normal pressure (atmospheric pressure), for example. The pressing conditions for the smoothing treatment can be the same as the heat-pressing conditions for the lamination described above. The smoothing treatment can be performed using a commercially available laminator. Note that the lamination and the smoothing treatment can be continuously performed using the commercially available vacuum laminator described above.

[0185] -Process (II)-

[0186] In process (II), a second resin sheet including a second support and a second resin composition layer joined to the second support is laminated on the second main surface of the circuit substrate, and the second resin composition layer is joined to the second main surface of the circuit substrate.

[0187] The second resin sheet used in process (II) is as described in the above [Resin sheet set for solder resist layer of printed wiring board].

[0188] The lamination of the circuit substrate and the second resin sheet can be performed in the same manner as in process (I). The smoothing treatment described in process (I) can be performed on the second resin sheet after the lamination of the circuit substrate and the second resin sheet.

[0189] Processes (I) and (II) can be simultaneously performed using a commercially available vacuum laminator.

[0190] The first and second supports can be removed before process (III). Alternatively, the first and second supports can be removed after process (III) (in the case of using a thermosetting resin composition layer) or can be removed in process (III) (in the case of using a photocurable resin composition layer).

[0191] -Process (III)-

[0192] In process (III), the first and second resin composition layers are cured to form first and second solder resist layers.

[0193] The curing conditions for the resin composition layers are not particularly limited and can be conditions commonly used when forming a solder resist layer of a printed wiring board.

[0194] In the case where at least one of the first and second resin composition layers is a thermosetting resin composition layer, process (III) includes thermally curing the thermosetting resin composition layer to form a solder resist layer.

[0195] The conditions of the heat curing vary depending on the composition of the resin composition for the thermosetting resin composition layer, etc., but the curing temperature can be in the range of 120°C to 240°C (preferably in the range of 150°C to 210°C, more preferably in the range of 170°C to 190°C), and the curing time can be in the range of 5 minutes to 150 minutes (preferably in the range of 10 minutes to 120 minutes, more preferably in the range of 15 minutes to 90 minutes). The heat curing is preferably performed under atmospheric pressure (normal pressure). Note that the heat curing can be performed multiple times. For example, the process (III) can be performed multiple times before the process (IV) described later, or the process (III) can be performed one or more times before the process (IV) described later, and furthermore, the heat curing can be performed one or more times after the process (IV) and the process (V). In the case where the heat curing is performed n times, the "elastic modulus after the curing" described above indicates the elastic modulus after the heat curing is performed n times.

[0196] In the case where at least one of the first and second resin composition layers is the photocurable resin composition layer, the process (III) includes exposing the photocurable resin composition layer, developing, and baking to form a solder resist layer.

[0197] The exposure of the photocurable resin composition layer can be performed, for example, by irradiating active light to a specific portion of the photocurable resin composition layer using a mask pattern. By so doing, the photocurable resin composition of the irradiated portion can be photocured. As the active light, for example, ultraviolet rays, visible rays, electron rays, X-rays, etc. can be listed, and ultraviolet rays are particularly preferable. The amount of the irradiation of the ultraviolet rays is not particularly limited, and can be in the range commonly used when the photocurable resin composition is used to form a solder resist layer, and is preferably in the range of 10 mJ / cm 2 to 1000 mJ / cm 2 In the case where a support is present on the photocurable resin composition layer, the exposure can be performed from the support.

[0198] The development can be performed by removing the non-photocured portion (non-exposed portion) using a developing solution. By so doing, the desired pattern can be formed. Note that in the case where a support is present on the photocurable resin composition layer, the support can be removed before the development. As the developing solution, an alkaline developing solution is preferable, and for example, an aqueous sodium carbonate solution, an aqueous sodium hydroxide solution can be listed. As the developing method, for example, spraying, shaking immersion, brushing, scraping, etc. can be listed.

[0199] The conditions of the baking vary depending on the composition of the resin composition for the photocurable resin composition layer, and the baking temperature can be in the range of 120°C to 240°C (preferably in the range of 150°C to 210°C, more preferably in the range of 170°C to 190°C), and the baking time can be in the range of 5 minutes to 150 minutes (preferably in the range of 10 minutes to 120 minutes, more preferably in the range of 15 minutes to 90 minutes). The baking is preferably performed under atmospheric pressure (normal pressure). Note that the baking can be performed multiple times. In the case where the baking is performed n times, the "elastic modulus after curing" refers to the elastic modulus after the baking is performed n times.

[0200] In the case where at least one of the first and second resin composition layers is a thermosetting resin composition layer and the other is a photocurable resin composition layer, the baking performed on the photocurable resin composition layer can be performed simultaneously with the thermosetting of the thermosetting resin composition layer.

[0201] By performing the steps (I) to (III) using the resin sheet set of the present application, a printed wiring board satisfying the above conditions (1), (2), and (3) can be easily manufactured.

[0202] - Other Steps -

[0203] The method for manufacturing a printed wiring board can further include a step (IV) of forming an opening portion, and a step (V) of desmear treatment. The steps (IV) and (V) can be performed according to various methods known to those skilled in the art for manufacturing a printed wiring board. Note that in the case where the first and second supports are peeled after the step (III) (in the case where a thermosetting resin composition layer is used), the peeling of the first and second supports can be performed between the step (III) and the step (IV), between the step (IV) and the step (V), or after the step (V).

[0204] The step (IV) is a step of forming an opening portion. By so doing, an opening portion can be formed on a solder resist layer formed using a thermosetting resin composition. Note that the step (IV) can also be performed in order to form an opening portion on a solder resist layer formed using a photocurable resin composition, if necessary. The step (IV) can be performed using, for example, a drill, a laser, plasma, or the like, depending on the composition of the resin composition constituting the solder resist layer, and the like. The size or shape of the opening portion can be appropriately determined in accordance with the design of a component mounting substrate (also referred to as a "semiconductor device").

[0205] In the case where the opening portion is formed using a laser, as the laser light source, for example, a carbon dioxide laser, a YAG laser, an excimer laser, or the like can be exemplified. Among them, from the viewpoint of processing speed and cost, a carbon dioxide laser is preferred.

[0206] The step (V) is a step of removing surface contamination treatment. Residual resin (contamination, smears) is often attached to the inside of the opening portion formed in the step (IV). The contamination is a cause of poor electrical connection, and therefore, the treatment for removing the contamination (surface contamination removal treatment) is performed in the step (V).

[0207] The surface contamination removal treatment can be performed by a dry surface contamination removal treatment, a wet surface contamination removal treatment, or a combination of both.

[0208] As the dry surface contamination removal treatment, for example, a surface contamination removal treatment using plasma or the like can be cited. The surface contamination removal treatment using plasma can be performed using a commercially available plasma surface contamination removal treatment device. As examples suitable for the manufacturing of printed wiring boards, a microwave plasma device manufactured by Nissin Corporation, an atmospheric pressure plasma etching device manufactured by Sekisui Chemical Industry Co., Ltd., and the like can be cited.

[0209] As the wet surface contamination removal treatment, for example, a surface contamination removal treatment using an oxidizing agent solution or the like can be cited. In the case where the surface contamination removal treatment is performed using an oxidizing agent solution, it is preferable to sequentially perform swelling treatment by a swelling liquid, oxidation treatment by an oxidizing agent solution, and neutralization treatment by a neutralizing liquid. As the swelling liquid, for example, "Swelling Dip Securiganth P", "Swelling Dip Securiganth SBU", and the like manufactured by Atotech Japan Co., Ltd. can be cited. It is preferable that the swelling treatment be performed by immersing the substrate on which the opening portion is formed in the swelling liquid heated to 60°C to 80°C for 5 minutes to 10 minutes. As the oxidizing agent solution, an aqueous alkaline permanganate solution is preferable, and for example, a solution in which potassium permanganate or sodium permanganate is dissolved in an aqueous sodium hydroxide solution can be cited. It is preferable that the oxidation treatment by the oxidizing agent solution be performed by immersing the substrate after the swelling treatment in the oxidizing agent solution heated to 60°C to 80°C for 10 minutes to 30 minutes. As commercially available products of the aqueous alkaline permanganate solution, for example, "Concentrate Compact CP", "Dipping Solution Securiganth P", and the like manufactured by Atotech Japan Co., Ltd. can be cited. It is preferable that the neutralization treatment by the neutralizing liquid be performed by immersing the substrate after the oxidation treatment in the neutralizing liquid heated to 30°C to 50°C for 3 minutes to 10 minutes. As the neutralizing liquid, an acidic aqueous solution is preferable, and as commercially available products, for example, "Reduction solution Securiganth P" manufactured by Atotech Japan Co., Ltd. can be cited.

[0210] In the case where the dry-type surface contamination removal treatment and the wet-type surface contamination removal treatment are combined, the dry-type surface contamination removal treatment can be performed first, or the wet-type surface contamination removal treatment can be performed first.

[0211] The above describes the method for manufacturing a printed wiring board using the resin sheet set of the present application, but the method for manufacturing a printed wiring board of the present application is not particularly limited as long as a printed wiring board satisfying the above conditions (1), (2) and (3) can be obtained. For example, a varnish of the resin composition can be applied to both surfaces of the circuit substrate, and dried and cured to produce a printed wiring board.

[0212] [Semiconductor device]

[0213] A semiconductor device can be manufactured using the printed wiring board of the present application. Although the printed wiring board of the present application is thin, warping can be suppressed even in a component mounting process using a high reflow soldering temperature, and further, problems such as circuit deformation or component contact failure can be advantageously alleviated.

[0214] As the semiconductor device, various semiconductor devices used for electrical products (for example, computers, mobile phones, digital cameras, and televisions, etc.) and vehicles (for example, motorcycles, automobiles, electric cars, ships, and airplanes, etc.) and the like can be exemplified.

[0215] [Examples]

[0216] Hereinafter, the present application will be described more specifically by examples, but the present application is not limited to these examples. It should be noted that "parts" and "%" below respectively mean "mass parts" and "mass %" unless specifically stated.

[0217] First, various measurement methods and evaluation methods will be described.

[0218] [Preparation of evaluation substrate]

[0219] (1) Preparation of circuit substrate

[0220] A glass cloth substrate epoxy resin double-sided laminate having a circuit formed on both surfaces was subjected to roughening treatment of the surface circuit by etching 1 μm using a microetching agent (CZ8100 manufactured by MEC COMPANY LTD.), and a circuit board was prepared. As the glass cloth substrate epoxy resin double-sided laminate having a circuit formed on both surfaces, "HL832NSF-LCA" (size 100 mm x 150 mm, thickness 100 μm, coefficient of thermal expansion 4 ppm / °C, flexural modulus of elasticity 34 GPa, thickness of surface copper circuit 16 μm) manufactured by Mitsubishi Gas Chemical Company, Inc. was used for Examples 1, 2 and 4, and Comparative Examples 1 and 2, and "E679FGR" (size 100 mm x 150 mm, thickness 200 μm, coefficient of thermal expansion 14 ppm / K, flexural modulus of elasticity 26 GPa, thickness of surface copper circuit 16 μm (Example 3 and Comparative Example 3), 8 μm (Comparative Example 4)) manufactured by Hitachi Chemical Co., Ltd. was used for Example 3 and Comparative Examples 3 and 4.

[0221] (2) Lamination of Resin Sheets

[0222] The resin sheets produced in the following Production Examples were laminated to both surfaces of the circuit board obtained in the above (1) using a batch vacuum press laminator (2-Stage Buildup Laminator "CVP700" manufactured by Nichigo-Morton Co., Ltd.), with the resin composition layer being in contact with the circuit board. Lamination was performed as follows: after reducing the pressure to 13 hPa or less for 30 seconds, the sheets were pressed at 100°C under a pressure of 0.74 MPa for 30 seconds. Subsequently, the sheets were subjected to smoothing treatment by hot pressing at 100°C under a pressure of 0.5 MPa for 60 seconds under normal pressure.

[0223] Note that the combination of the first and second resin sheets laminated to both surfaces of the circuit board is shown in Table 1.

[0224] Subsequently, the resin composition layer was cured to form a solder resist layer as follows.

[0225] - Case where Resin Sheets 1 and 2 Containing a Thermosetting Resin Composition Layer are Used -

[0226] (3) Thermosetting of Resin Composition Layer

[0227] The support was peeled from the substrate obtained in the above (2). Subsequently, the resin composition layer was thermosetted to form a solder resist layer under curing conditions of 180°C for 30 minutes.

[0228] (4) Formation of Opening

[0229] A CO2 laser processing machine (Mitsubishi Electric Corporation "ML605GTWIII-5200U") was used to form a circular hole with an opening diameter of 60 μm under the following conditions 1 and a circular hole with an opening diameter of 500 μm under the following conditions 2.

[0230] Conditions 1: mask diameter 0.9 mm, pulse width 19 μs, energy 0.24 mJ, number of shots 2, burst mode

[0231] Conditions 2: mask diameter 10 mm, pulse width 15 μs, energy 18 mJ, number of shots 4, burst mode

[0232] (5) Removal of surface contamination treatment

[0233] After forming the opening portion, the circuit board was immersed in a swelling solution (Atotech Japan Corporation "Swelling Dip Securiganth P", an aqueous solution containing diethylene glycol monobutyl ether and sodium hydroxide) at 60°C for 5 minutes, in an oxidizing solution (Atotech Japan Corporation "Concentrate Compact CP", an aqueous solution of KMnO4: 60 g / L, NaOH: 40 g / L) at 80°C for 10 minutes, and finally in a neutralizing solution (Atotech Japan Corporation "Reduction solution Securiganth P", an aqueous solution of hydroxylamine sulfate) at 40°C for 5 minutes. Then, drying was performed at 100°C for 30 minutes, followed by heat curing at 180°C for 60 minutes to produce the evaluation board.

[0234] - Cases where the resin sheets 3, 4, and 5 containing the photocurable resin composition layer were used

[0235] (3') Exposure, development, and baking of the resin composition layer

[0236] The substrate obtained in the above (2) was left to stand at room temperature for 1 hour. Then, using a mask pattern, ultraviolet exposure of 100 mJ / cm 2 was performed from the support to form circular holes with opening diameters of 60 μm and 500 μm. The exposure can be performed using a pattern forming device (Ushio Inc. "UX-2240"). Subsequently, the support was left to stand at room temperature for 30 minutes, and the support was peeled off.

[0237] For the resulting substrate, a developer (2 mass% sodium hydroxide aqueous solution at 30°C) was sprayed at a spray pressure of 0.2 MPa for 40 seconds over the entire surface of the resin composition layer, and development was performed. Note that, for Comparative Example 2 using the resin sheet 4, a 1 mass% sodium carbonate aqueous solution at 30°C was used as the developer.

[0238] After development, drying was performed at 80°C for 30 minutes, followed by baking at 180°C for 90 minutes, to obtain an evaluation substrate.

[0239] 〔Preparation of evaluation cured product〕

[0240] An evaluation cured product was prepared in the following order.

[0241] -Case of using resin sheets 1 and 2 containing a thermosetting resin composition layer-

[0242] The resin composition layer of the resin sheets 1 and 2 was arranged so as to come into contact with the release surface of a PET film with a release layer ("PET501010" manufactured by LINTEC Corporation; hereinafter also referred to as "evaluation support") and lamination was performed using a vacuum laminator ("VP160" manufactured by Nichigo-Morton Corporation). The lamination conditions were: vacuum time 20 seconds, pressure bonding temperature 80°C, pressure bonding pressure 0.2 MPa, and pressure time 20 seconds.

[0243] After peeling the support derived from the resin sheet from the resulting laminate, the resin composition layer was thermally cured under curing conditions of 180°C for 90 minutes. Subsequently, the evaluation support was peeled, to obtain an evaluation cured product.

[0244] -Case of using resin sheets 3, 4, and 5 containing a photocurable resin composition layer-

[0245] In the same manner as in the above-described "Preparation 1 of evaluation cured product", the resin composition layer of the resin sheets 3, 4, and 5 was laminated on the release surface of a PET film with a release layer ("PET501010" manufactured by LINTEC Corporation; also referred to as "evaluation support").

[0246] After the resulting laminate was left to stand at room temperature for 1 hour, the resin composition layer was subjected to ultraviolet light exposure of 100 mJ / cm 2 at room temperature. After peeling the support derived from the resin sheet, the resin composition layer was subjected to treatment under baking conditions of 80°C for 30 minutes and then 180°C for 90 minutes. Subsequently, the evaluation support was peeled, to obtain an evaluation cured product.

[0247] <Warpage evaluation>

[0248] An evaluation substrate was passed once through a reflow soldering apparatus (HAS-6116 manufactured by Antom Co., Ltd., Japan) at a reflow soldering temperature of 260°C (reflow soldering temperature profile according to IPC / JEDEC J-STD-020C). Then, using a shadow moire apparatus (TherMoire AXP manufactured by Akrometrix), a displacement of a 25 mm square portion in the center of the evaluation substrate was measured based on a grid line provided on the upper surface of the evaluation substrate, according to a reflow soldering temperature profile according to IPC / JEDEC J-STD-020C (peak temperature of 260°C).

[0249] The difference between the maximum height and the minimum height of the obtained displacement data was "X" when it was 50 μm or more in the entire temperature range, and "O" when it was less than 50 μm.

[0250] Measurement of Elastic Modulus

[0251] The evaluation cured product was cut into a dumbbell shape to obtain a test piece. The test piece was subjected to tensile strength measurement using a tensile tester (RTC-1250A manufactured by ORIENTEC Co., Ltd.), and the elastic modulus at 23°C and at 200°C was calculated. The measurement was performed according to JIS K7127.

[0252] Measurement of Glass Transition Temperature (Tg)

[0253] The evaluation cured product was cut into a test piece having a width of 5 mm and a length of 15 mm. The test piece was subjected to thermal mechanical analysis using a thermal mechanical analysis apparatus (TMA-SS6100 manufactured by Seiko Instruments Inc.) by a tensile load method. Specifically, after the test piece was installed in the apparatus, two measurements were continuously performed under measurement conditions of a load of 1 g and a temperature increase rate of 5°C / minute. In the second measurement, the glass transition temperature Tg (°C) was calculated from a point at which the inclination of the dimensional change signal changed.

[0254] The resin sheets 1, 2, 3, 4, and 5 used in the examples and comparative examples were produced in the following order.

[0255] Production of Resin Sheet 1

[0256] Bisphenol A type epoxy resin ("jER828EL" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent weight about 185) 12 parts, naphthalene type epoxy resin ("HP4032SS" manufactured by DIC Corporation, epoxy equivalent weight about 144) 3 parts, dinaphthylol type epoxy resin ("YX4000HK" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent weight about 185) 6 parts, biphenyl type epoxy resin ("NC3000H" manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent weight about 288) 25 parts, phenoxy resin ("YX6954BH30" manufactured by Mitsubishi Chemical Corporation, 30 mass% solid content in 1:1 solution of MEK and cyclohexanone) 10 parts were dissolved in solvent naphtha 15 parts with stirring and heating. After cooling to room temperature, a phenol novolak type curing agent containing a triazine skeleton ("LA-7054" manufactured by DIC Corporation, hydroxyl equivalent weight 125, 60% solid content in MEK solution) 20 parts, naphthol type curing agent ("SN485" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., hydroxyl equivalent weight 215, 60% solid content in MEK solution) 10 parts, curing accelerator (4-dimethylaminopyridine (DMAP), 5 mass% solid content in MEK solution) 0.4 parts, flame retardant ("HCA-HQ" manufactured by Mitsui Kasei Co., Ltd., 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide, average particle diameter 2 μm) 3 parts, spherical silica (average particle diameter 1 μm, "SOC4" manufactured by Admatechs Co., Ltd., carbon content per unit surface area 0.47 mg / m 2 ) 240 parts, which had been surface-treated with an amino silane coupling agent ("KBM573" manufactured by Shin-Etsu Chemical Co., Ltd.), were uniformly dispersed using a high-speed rotary stirrer to produce resin varnish 1.

[0257] A PET film ("NS80A" manufactured by Toray Industries, Inc.) having a thickness of 38 μm was prepared as a support. Resin varnish 1 was uniformly applied to the smooth surface of the support to give a dried resin composition layer having a thickness of 16 μm, and the resulting product was dried at 80°C to 120°C (average 100°C) for 3 minutes to produce resin sheet 1.

[0258] Preparation of resin sheet 2

[0259] Instead of the phenoxy resin ("YX6954BH30" manufactured by Mitsubishi Chemical Corporation, 30 mass% solid content MEK / cyclohexanone = 1 / 1 solution) 10 parts, phenoxy resin ("YX6954BH30" manufactured by Mitsubishi Chemical Corporation, 30 mass% solid content MEK / cyclohexanone = 1 / 1 solution) 30 parts was used, and instead of the amino silane coupling agent ("KBM573" manufactured by Shin-Etsu Chemical Co., Ltd.) surface-treated spherical silica (average particle diameter 1 μm, "SOC4" manufactured by Admatechs Co., Ltd., carbon content per unit surface area 0.47 mg / m 2 ) 75 parts, amino silane coupling agent ("KBM573" manufactured by Shin-Etsu Chemical Co., Ltd.) surface-treated spherical silica (average particle diameter 1 μm, "SOC4" manufactured by Admatechs Co., Ltd., carbon content per unit surface area 0.47 mg / m 2 ) 240 parts, and the amount of solvent oil was changed from 15 parts to 10 parts, and otherwise the same method as in Production Example 1 was used to produce resin varnish 2, and then resin sheet 2.

[0260] < Production Example 3) > Production of Resin Sheet 3

[0261] Instead of the phenoxy resin ("YX6954BH30" manufactured by Mitsubishi Chemical Corporation, 30 mass% solid content MEK / cyclohexanone = 1 / 1 solution) 10 parts, phenoxy resin ("YX6954BH30" manufactured by Mitsubishi Chemical Corporation, 30 mass% solid content MEK / cyclohexanone = 1 / 1 solution) 30 parts was used, and instead of the amino silane coupling agent ("KBM573" manufactured by Shin-Etsu Chemical Co., Ltd.) surface-treated spherical silica (average particle diameter 1 μm, "SOC4" manufactured by Admatechs Co., Ltd., carbon content per unit surface area 0.47 mg / m 2)120 parts, spherical silica (average particle diameter 0.1 μm, "UFP-30" manufactured by Kanto Chemical Co., Inc.) surface-treated with an amino silane-based coupling agent ("KBM573" manufactured by Shin-Etsu Chemical Co., Ltd.), 20 parts, a diluent ("DPHA" manufactured by Nippon Kayaku Co., Ltd., dipentaerythritol hexaacrylate), 10 parts, a curing accelerator ("2P4MZ" manufactured by Shikoku Chemicals Corporation, 2-phenyl-4-methylimidazole, 2.5 mass% of nonvolatile components in MEK solution), 8.8 parts, rubber particles ("AC3816N" manufactured by Ganz Chemical Industry Co., Ltd.), 2.4 parts, a photosensitizer ("DETX-S" manufactured by Nippon Kayaku Co., Ltd., 2,4-diethylthioxanthone, 10 mass% of nonvolatile components in MEK solution), 4.4 parts, and diethylene glycol monoethyl ether acetate, 10 parts were mixed, uniformly dispersed with a high-speed rotary stirrer, and a resin varnish 3 was prepared.

[0262] A PET film ("R310-16B" manufactured by Mitsubishi Chemical, Inc.) having a thickness of 16 μm was prepared as a support. The resin varnish 3 was uniformly applied to the support so that the thickness of the dried resin composition layer reached 23 μm, and the resin sheet 3 was prepared by drying at 75°C to 120°C (average 100°C) for 5 minutes.

[0263] (Synthesis Example 1) Synthesis of the alkali-soluble photocurable resin A

[0264] In a 300 mL separable flask, carbitol acetate 25 g and 3-isocyanato-3,5,5-trimethylcyclohexyl isocyanate (manufactured by Evonik) 50 g were weighed and heated and stirred at 40°C. Separately, pentaerythritol triacrylate-containing substance ("M306" manufactured by Toagosei Co., Ltd.) 92.23 g, carbitol acetate 25 g, dibutyl tin dilaurate (manufactured by Tokyo Chemical Industry Co., Ltd.) 0.45 g, and hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.) 0.4 g were weighed, and mixed with a stirrer ("awatoritenrataro" manufactured by Shinki Co., Ltd.) for 8 minutes to obtain a mixed solution 1. The obtained mixed solution 1 was dropped into the above 300 mL separable flask over 1 hour or more using a dropping funnel. Then, heating and stirring were performed at 40°C for 30 minutes to obtain a reactant of 3-isocyanato-3,5,5-trimethylcyclohexyl isocyanate and pentaerythritol triacrylate 193.08 g.

[0265] On the other hand, in a 500 mL separable flask, carbitol acetate 132.26 g, phenol novolak resin (DIC Corporation "TD-2090") 132.26 g were weighed and stirred at 75°C until completely dissolved. Next, the above reaction product 193.08 g was added, and heating and stirring were performed at 85°C until the isocyanate group disappeared by infrared (IR). After cooling to 40°C, ethanol (pure chemical corporation) 3.11 g was added, and stirring was performed for 2 hours or more to obtain a photocurable alkali-soluble resin A (acrylate-modified phenol resin) containing an acrylate group and a phenolic hydroxyl group 460.71 g. The properties of the obtained photocurable alkali-soluble resin A are shown below,

[0266] • Solvent-soluble matter of 60 mass% of solid content

[0267] • Acrylate group ratio: 18%

[0268] • Number average molecular weight (Mn) in terms of polystyrene: 4000

[0269] • Hydroxyl equivalent: 246.

[0270] Manufacture of Resin Sheet 4

[0271] A xylenol-type epoxy resin (Mitsubishi Chemical Corporation "YX4000HK", epoxy equivalent 185, 30 mass% of non-volatile components in a 1:1 solution of MEK and cyclohexanone) 80 parts, a photocurable alkali-soluble resin containing an acrylate group and a carboxyl group (Japan Chemical Industry Co., Ltd. "ZFR-1533H", bisphenol F-type epoxy acrylate, 68% of solid content in diethylene glycol monoethyl ether acetate solution, acid value 70 mgKOH / g) 147 parts, a photopolymerization initiator (BASF JAPAN Corporation "IRGACURE907", 2-methyl-[4-(methylthio)phenyl]morpholino-1-propanone) 2.5 parts, spherical silica (average particle diameter 0.5 μm, Admatechs Corporation "SOC2", carbon content per unit surface area 0.39 mg / m 2)80 parts, 20 parts of spherical silica (average particle diameter 0.1 μm, "UFP-30" manufactured by Kabushiki Kaisha Zeria, surface treated with an amino silane coupling agent ("KBM573" manufactured by Shokubai K.K.), 10 parts of a diluent ("DCPA" manufactured by Kyoeisha Chemical Co., Ltd., tricyclodecane dimethanol diacrylate), 8.8 parts of a curing accelerator ("2P4MZ" manufactured by Shikoku Chemicals Corporation, 2-phenyl-4-methylimidazole, 2.5 mass% of nonvolatile components in MEK solution), 2.4 parts of rubber particles ("AC3816N" manufactured by Ganz Chemical Industry Co., Ltd.), 2 parts of a photosensitizer ("DETX-S" manufactured by Nippon Kayaku Co., Ltd., 2,4-diethylthioxanthone, 10 mass% of nonvolatile components in MEK solution), and 3 parts of diethylene glycol monoethyl ether acetate (an organic solvent) were mixed, uniformly dispersed with a high-speed rotary stirrer, and a resin varnish 4 was prepared.

[0272] A PET film ("R310-16B" manufactured by Mitsubishi Plastics, Inc., thickness 16 μm) was prepared as a support. The resin varnish 4 was uniformly applied to the support so that the thickness of the dried resin composition layer became 23 μm, and the resin sheet 4 was prepared by drying at 75 to 120°C (average 100°C) for 5 minutes.

[0273] Preparation of resin sheet 5

[0274] The resin varnish 3 was uniformly applied so that the thickness of the dried resin composition layer became 8 μm, and the resin sheet 5 was prepared by drying at 75 to 120°C (average 100°C) for 2 minutes in the same manner as in Production Example 3.

[0275] The resin sheets 1 to 5 obtained were combined as shown in Table 1 below, and resin sheet sets 1 to 6 were prepared. In addition, for the resin sheets 1 to 5 used in each resin sheet set, evaluation-use cured products were prepared in accordance with the above-mentioned "Preparation of evaluation-use cured products", and the elastic modulus and the glass transition temperature (Tg) were measured. The results are shown in Table 1.

[0276] [Table 1]

[0277] (Table 1)

[0278] Example 1

[0279] An evaluation-use substrate was obtained using the resin sheet set 1 in accordance with the above-mentioned "Preparation of evaluation-use substrate". The evaluation results are shown in Table 2.

[0280] Example 2

[0281] An evaluation-use substrate was obtained using the resin sheet set 2 in accordance with the above-mentioned "Preparation of evaluation-use substrate". The evaluation results are shown in Table 2.

[0282] Example 3

[0283] Using the resin sheet set 1, an evaluation substrate was obtained according to the above-described "Preparation of Evaluation Substrate". The evaluation results are shown in Table 2.

[0284] Example 4

[0285] Using the resin sheet set 3, an evaluation substrate was obtained according to the above-described "Preparation of Evaluation Substrate". The evaluation results are shown in Table 2.

[0286] Comparative Example 1

[0287] Using the resin sheet set 4, an evaluation substrate was obtained according to the above-described "Preparation of Evaluation Substrate". The evaluation results are shown in Table 2.

[0288] Comparative Example 2

[0289] Using the resin sheet set 5, an evaluation substrate was obtained according to the above-described "Preparation of Evaluation Substrate". The evaluation results are shown in Table 2.

[0290] Comparative Example 3

[0291] Using the resin sheet set 4, an evaluation substrate was obtained according to the above-described "Preparation of Evaluation Substrate". The evaluation results are shown in Table 2.

[0292] Comparative Example 4

[0293] Using the resin sheet set 6, an evaluation substrate was obtained according to the above-described "Preparation of Evaluation Substrate". The evaluation results are shown in Table 2.

[0294] [Table 2]

[0295] (Table 2)

[0296]

Claims

1. A printed circuit board, comprising a first solder resist layer and a second solder resist layer, wherein the thickness Z of the printed circuit board is less than 250 μm, wherein, The first and second solder resist layers are formed by curing a resin composition. The inorganic filler content in the resin composition contained in the first solder resist layer is 60% by mass or more. The inorganic filler material in the resin composition contained in the first solder resist layer consists only of silicon dioxide. The thickness t1 of the first solder resist layer is greater than 15 μm and less than 25 μm. The thickness t2 of the second solder resist layer is greater than 20 μm and less than 25 μm. When the thickness of the first solder resist layer is set as t1 (μm), the elastic modulus (23℃) of the resin composition contained in the first solder resist layer after curing is set as G1 (GPa), and the thickness of the second solder resist layer is set as t2 (μm) and the elastic modulus (23℃) after curing is set as G2 (GPa), the following conditions (2)~(3) are satisfied: (2) (t1+t2) / Z≥0.1; and (3) G1×[t1 / (t1+t2)]+G2×[t2 / (t1+t2)]≥6, G1 is 6 or higher.

2. The printed circuit board according to claim 1, wherein, The glass transition temperature (Tg) of the first solder resist layer after curing is above 150℃.

3. The printed circuit board according to claim 1, wherein, Condition (2) is 0.1≤(t1+t2) / Z≤0.

5.

4. The printed circuit board according to claim 1, wherein, G2 is 6 or higher.

5. The printed circuit board according to claim 1, wherein, When the elastic modulus (200℃) of the first solder resist layer after curing is set as G1' (GPa) and the elastic modulus (200℃) of the second solder resist layer after curing is set as G2' (GPa), the following condition (4) is further satisfied: (4)G1'×[t1 / (t1+t2)]+G2'×[t2 / (t1+t2)]≥0.

2.

6. The printed circuit board according to any one of claims 1 to 5, wherein, The second solder resist layer contains a resin composition, the elastic modulus (at 23°C) of which after curing is 6 GPa or higher, and G2 is the elastic modulus (at 23°C) of the resin composition contained in the second solder resist layer after curing.

7. A semiconductor device comprising a printed circuit board according to any one of claims 1 to 6.

8. A resin sheet assembly for use as a solder resist layer in a printed circuit board, wherein the thickness Z of the printed circuit board is 250 μm or less, and the resin sheet assembly comprises: A first resin sheet, the first resin sheet comprising a first support and a first resin composition layer bonded to the first support; and The second resin sheet includes a second support and a second resin composition layer bonded to the second support. The solder resist layer comprises: a first solder resist layer formed by curing a first resin composition layer, and a second solder resist layer formed by curing a second resin composition layer. The inorganic filler content in the resin composition contained in the first resin composition layer is 60% by mass or more. The inorganic filler material in the resin composition contained in the first resin composition layer consists only of silicon dioxide. The thickness t of the first resin composition layer 1p The size is greater than 10μm and less than 23μm. The thickness t of the second resin composition layer 2p The size is greater than 10μm and less than 23μm. Let the thickness of the first resin composition layer be t. 1p Let G1 (GPa) be the elastic modulus (at 23°C) of the cured resin composition in the first resin composition layer, and let t be the thickness of the second resin composition layer. 2p When the elastic modulus (μm) after curing (23℃) is set to G2 (GPa), the following conditions (2')~(3') must be met: (2') (t 1p +t 2p ) / Z≥0.1; and (3’) G1×[t 1p / (t 1p +t 2p )]+G2×[t 2p / (t 1p +t 2p )]≥6, G1 is 6 or higher.

9. A resin sheet comprising a support and a first resin composition layer of thickness t1 (μm) bonded to the support, and the resin sheet being used in a printed wiring board with a designed thickness Z (μm) of 250 μm or less to form one of a first solder resist layer disposed on a first main surface of a circuit board and a second solder resist layer disposed on a second main surface. The first solder resist layer is formed by curing the first resin composition layer. The second solder resist layer is formed by curing the second resin composition layer. The inorganic filler content in the resin composition contained in the first resin composition layer is 60% by mass or more. The inorganic filler material in the resin composition contained in the first resin composition layer consists only of silicon dioxide. The thickness t1 of the first solder resist layer is greater than 15 μm and less than 25 μm. The thickness t2 of the second solder resist layer is greater than 20 μm and less than 25 μm. The elastic modulus G1 (GPa) of the cured resin composition contained in the first resin composition layer at 23°C is 6 GPa or more, and... When the thickness of the second resin composition layer in the second resin sheet used to form the other of the first solder resist layer and the second solder resist layer is t2 (μm) and the elastic modulus of the cured second resin composition layer at 23°C is G2 (GPa), the first resin composition layer satisfies the following conditions: (t1+t2) / Z≥0.1; and G1×[t1 / (t1+t2)]+G2×[t2 / (t1+t2)]≥6.

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