Resin composition for forming circuit board, and application of the same

Abstract

To provide a resin composition for forming circuit board by which a cured product having excellent low elastic modulus and low linear expansion coefficient is obtained.SOLUTION: A resin composition for circuit board contains (A) thermosetting resin, (B) stress-reducing agent, and (C) inorganic filler, where the thermosetting resin (A) is one or more kinds of resin selected from the group consisting of epoxy resin and benzoxazine resin, the stress-reducing agent (B) includes one or more kinds selected from the group consisting of (B1) urethane acrylate, (B2) epoxidized polybutadiene, and (B3) silicone particles, and in a cured product obtained by curing the composition, a domain phase of the stress-reducing agent (B) is formed in a continuous phase made of the thermosetting resin (A).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition for forming a circuit board and its use. [Background technology]

[0002] In recent years, as semiconductor chips have become thinner, various properties such as high rigidity and a low coefficient of linear expansion have been required for the circuit board on which the semiconductor chip is mounted in order to suppress warpage of the semiconductor package.

[0003] Patent Documents 1 to 4 disclose resin compositions containing a thermosetting resin and an inorganic filler together with a specific benzoxazine compound or epoxidized polybutadiene, etc. Patent Documents 5 to 8 disclose resin compositions containing a thermosetting resin and an inorganic filler together with a silicone powder, etc.

[0004] Patent Document 9 discloses a resin composition containing a thermosetting resin, an elastomer having a urethane structural unit that reacts with the thermosetting resin, and an inorganic filler. It states that the cured product of the resin composition contains domains with an average maximum length of 15 μm or less. Patent Document 10 discloses a resin composition containing a thermosetting resin, an inorganic filler, and a polymer resin having a urethane skeleton and having a glass transition temperature of 30°C or less. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2020-143239 [Patent Document 2] International Publication No. 2021 / 010431 [Patent Document 3] Japanese Patent Application Laid-Open No. 2008-274274 [Patent Document 4] Patent Publication No. 2021-80392 [Patent Document 5] Japanese Patent Application Laid-Open No. 2009-24056 [Patent Document 6] Japanese Patent Application Laid-Open No. 2008-214602 [Patent Document 7] Japanese Patent Application Laid-Open No. 2010-275497 [Patent Document 8] International Publication No. 2011 / 126070 [Patent Document 9] Japanese Patent Application Publication No. 2017-110104 [Patent Document 10] Japanese Patent Publication No. 2023-36603 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the conventional techniques described in Patent Documents 1 to 10, warpage occurs in the semiconductor package, and there is room for improvement in the reliability of connection between the semiconductor element and the circuit board. [Means for solving the problem]

[0007] The present inventors have discovered that by using a predetermined combination of components in a resin composition for forming a circuit board, it is possible to obtain a cured product with a low elastic modulus and a low linear expansion coefficient, and to suppress warping of semiconductor packages, and have completed the present invention. That is, the present invention can be shown as follows.

[0008] [1] (A) a thermosetting resin; (B) a stress reducing agent; (C) an inorganic filler; A resin composition for circuit boards, comprising: the thermosetting resin (A) is one or more resins selected from the group consisting of epoxy resins and benzoxazine resins; The stress reducing agent (B) (B1) urethane acrylate, (B2) epoxidized polybutadiene, and (B3) Silicone particles Contains one or more selected from the group consisting of A resin composition for circuit boards, wherein in a cured product obtained by curing the resin composition for circuit boards, a domain phase of the stress reducing agent (B) is formed in a continuous phase of the thermosetting resin (A). [2] The resin composition for circuit boards according to [1], wherein the thermosetting resin (A) contains a benzoxazine resin. [3] The resin composition for circuit boards according to [1] or [2], wherein the stress reducing agent (B) comprises a urethane acrylate (B1), an epoxidized polybutadiene (B2), and silicone particles (B3). [4] The thermosetting resin (A) includes an epoxy resin; The resin composition for circuit boards according to any one of [1] to [3], further comprising an active ester curing agent (D). [5] The resin composition for forming a circuit board according to [4], wherein the active ester curing agent (D) has a structure represented by the following general formula (1): [ka] In general formula (1), A is a substituted or unsubstituted arylene group linked via an aliphatic cyclic hydrocarbon group, Ar′ is a substituted or unsubstituted aryl group, B is a structure represented by the following general formula (B): [ka] (In general formula (B), Ar represents a substituted or unsubstituted arylene group; Y represents a single bond, a substituted or unsubstituted linear alkylene group having 1 to 6 carbon atoms, or a substituted or unsubstituted cyclic alkylene group having 3 to 6 carbon atoms, a substituted or unsubstituted divalent aromatic hydrocarbon group, an ether bond, a carbonyl group, a carbonyloxy group, a sulfide group, or a sulfone group; and n represents an integer of 0 to 4.) k is the average value of the repeating units and is in the range of 0.25 to 3.5. [6] The resin composition for circuit boards according to any one of [1] to [5], wherein the domain phase of the stress-reducing agent (B) has an average domain size of 8 μm or less. [7] The resin composition for circuit boards according to any one of [1] to [6], wherein the stress reducing agent (B) contains a urethane acrylate (B1). [8] The resin composition for circuit boards according to any one of [1] to [7], wherein the epoxy equivalent of the epoxidized polybutadiene (B2) is 100 g / eq or more and 220 g / eq or less. [9] The resin composition for circuit boards according to any one of [1] to [8], wherein the viscosity of the epoxidized polybutadiene (B2) at 45°C is 2,000 MPa·s or more and 30,000 mPa / s or less.

[10] The resin composition for circuit boards according to any one of [1] to [9], wherein the silicone particles (B3) are a silicone composite powder or a silicone resin powder.

[11] The resin composition for forming a circuit board according to any one of [1] to

[10] , The storage modulus E' at 30°C of the cured product obtained by heat-treating a prepreg obtained by impregnating a fiber substrate with the resin composition for forming a circuit board at 200°C for 2 hours 30 The resin composition for forming a circuit board has a modulus of elasticity of 20.0 GPa or less.

[12] The resin composition for forming a circuit board according to any one of [1] to

[11] , The storage modulus E' at 250°C of the cured product obtained by heat-treating a prepreg obtained by impregnating a fiber substrate with the resin composition for forming a circuit board at 200°C for 2 hours is 250 The resin composition for forming a circuit board has a modulus of 13.0 GPa or less.

[13] The resin composition for forming a circuit board according to any one of [1] to

[12] , A resin composition for forming a circuit board, wherein a prepreg obtained by impregnating a fiber substrate with the resin composition for forming a circuit board is heat-treated at 200°C for 2 hours to obtain a cured product, the cured product having a linear expansion coefficient α1 of 3 ppm / °C or more and 15 ppm / °C or less, as measured under the following condition 1: (Condition 1) Using a thermomechanical analyzer, perform two cycles of thermomechanical analysis under the conditions of a temperature range of 30 to 260°C, a heating rate of 10°C / min, a load of 10 g, and compression mode. The average value of the linear expansion coefficient in the planar direction (longitudinal (X) direction) in the range of 50°C to 150°C is defined as the linear expansion coefficient α1.

[14] The resin composition for forming a circuit board according to any one of [1] to

[13] , A resin composition for forming a circuit board, wherein a prepreg is obtained by impregnating a fiber substrate with the resin composition for forming a circuit board, and the prepreg is heat-treated at 200°C for 2 hours to obtain a cured product, which has a linear expansion coefficient α2 of 5 ppm / °C or more and 18 ppm / °C or less, as measured under the following condition 2: (Condition 2) Using a thermomechanical analyzer, perform two cycles of thermomechanical analysis under the conditions of a temperature range of 30 to 260°C, a heating rate of 10°C / min, a load of 10 g, and compression mode. The average value of the linear expansion coefficient in the planar direction (longitudinal (X) direction) in the range of 30 to 260°C is defined as the linear expansion coefficient α2.

[15] The resin composition for forming a circuit board according to any one of [1] to

[14] , A resin composition for forming a circuit board, wherein a resin flow rate obtained by measuring a prepreg obtained by impregnating a fiber base material with the resin composition for forming a circuit board under the following condition 3 is 2% or more and 40% or less. (Condition 3) In accordance with IPC-TM-650, four 102 mm square sheets of the prepreg were stacked to obtain a laminate (mass: W1). The laminate was sandwiched between two metal plates and maintained at a temperature of 171°C and a pressure of 1.38 MPa for 10 minutes to obtain a cured product. The resin that flowed out of the cured product was removed, and the cured product was punched out to a diameter of 81.1 mm and its mass was measured (mass: W2). The resin flow rate (%) of the resin composition for forming circuit boards was calculated using the following formula. Formula: [(W1-2xW2) / W1]×100

[16] A resin sheet made of the resin composition for forming a circuit board according to any one of [1] to

[15] .

[17] A carrier substrate; A resin film with a carrier, comprising: a resin sheet formed on the carrier base and made of the resin composition for forming a circuit board according to any one of [1] to

[15] .

[18] A prepreg obtained by impregnating a fiber base material with the resin composition for forming a circuit board according to any one of [1] to

[15] .

[19] A laminate comprising the prepreg according to

[18] above and a metal layer disposed on at least one surface thereof.

[20] A printed wiring board having an insulating layer made of a cured product of the resin composition for forming a circuit board according to any one of [1] to

[15] .

[21] The printed wiring board according to

[20] ; a semiconductor element mounted on a circuit layer of the printed wiring board or embedded in the printed wiring board.

[22] A coreless substrate having a build-up layer including an insulating layer formed of a cured product of the resin composition for forming a circuit board according to any one of [1] to

[15] and a circuit layer. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a resin composition for forming a circuit board that can give a cured product having a low modulus of elasticity and a low coefficient of linear expansion. In other words, it is possible to provide a resin composition for forming a circuit board that has an excellent balance of these properties. By using the resin composition for forming a circuit board of this embodiment for a circuit board, warpage of the semiconductor package can be suppressed, and the connection reliability between the semiconductor element and the circuit board can be improved. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a cross-sectional view showing an example of the configuration of a resin film with a carrier in the present embodiment. [Figure 2] 1A to 1C are cross-sectional views showing an example of a manufacturing process for a semiconductor device according to an embodiment of the present invention. [Figure 3] 1A to 1C are cross-sectional views showing steps in an example of a manufacturing process for a coreless substrate according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all drawings, similar components are denoted by similar reference numerals, and their description will be omitted where appropriate. For example, "1 to 10" represents "1 or more" to "10 or less" unless otherwise specified.

[0012] The resin composition for circuit boards of the present embodiment comprises (A) a thermosetting resin, (B) a stress reducing agent, and (C) an inorganic filler, the thermosetting resin (A) is one or more resins selected from the group consisting of epoxy resins and benzoxazine resins; The stress reducing agent (B) (B1) urethane acrylate, (B2) epoxidized polybutadiene, and (B3) Silicone particles Contains one or more selected from the group consisting of In the cured product obtained by curing the composition, a domain phase of the stress-reducing agent (B) is formed in a continuous phase of the thermosetting resin (A).

[0013] The resin composition for forming a circuit board according to the present embodiment, which has the above-described configuration, can provide a cured product having a low modulus of elasticity and a low coefficient of linear expansion. By using the resin composition for forming a circuit board according to the present embodiment for a circuit board, warpage of the semiconductor package can be suppressed, and the connection reliability between the semiconductor element and the circuit board can be improved.

[0014] [Thermosetting resin (A)] The thermosetting resin (A) is made of one or more resins selected from the group consisting of epoxy resins and benzoxazine resins.

[0015] (epoxy resin) The epoxy resin may be any monomer, oligomer, or polymer having two or more epoxy groups in one molecule, and there are no limitations on the molecular weight or molecular structure.

[0016] In this embodiment, examples of the epoxy resin include biphenyl-type epoxy resins; bisphenol-type epoxy resins such as bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, and tetramethylbisphenol F-type epoxy resins; stilbene-type epoxy resins; novolac-type epoxy resins such as phenol novolac-type epoxy resins and cresol novolac-type epoxy resins; multifunctional epoxy resins such as triphenolmethane-type epoxy resins and alkyl-modified triphenolmethane-type epoxy resins; aralkyl-type epoxy resins such as phenol aralkyl-type epoxy resins having a phenylene skeleton, phenol aralkyl-type epoxy resins having a biphenylene skeleton, and biphenyl aralkyl-type epoxy resins; naphthol-type epoxy resins such as dihydroxynaphthalene-type epoxy resins and epoxy resins obtained by glycidyl etherifying a dihydroxynaphthalene dimer; triazine-nucleus-containing epoxy resins such as triglycidyl isocyanurate and monoallyl diglycidyl isocyanurate; and bridged cyclic hydrocarbon compound-modified phenol-type epoxy resins such as dicyclopentadiene-modified phenol-type epoxy resins. These may be used alone or in combination of two or more.

[0017] Among these, from the viewpoint of low elastic modulus, the epoxy resin preferably contains one or more types selected from the group consisting of phenol aralkyl epoxy resins, biphenyl epoxy resins, bisphenol epoxy resins, novolac epoxy resins, and triphenolmethane epoxy resins, and more preferably contains one or more types selected from the group consisting of phenol aralkyl epoxy resins represented by the following general formula (1), biphenyl epoxy resins represented by the following general formula (2), and bisphenol epoxy resins represented by the following general formula (3).

[0018] [ka]

[0019] In formula (1), Ar 1 represents a phenylene group or a naphthylene group, and Ar 1 When Ar is a naphthylene group, the glycidyl ether group may be bonded to either the α-position or the β-position. 2 represents any one of a phenylene group, a biphenylene group, and a naphthylene group. a and R b each independently represents a hydrocarbon group having 1 to 10 carbon atoms, g is an integer of 0 to 5, and h is an integer of 0 to 8. n 3 represents the degree of polymerization, and its average value is 1 to 3. In this embodiment, Ar 1 represents a phenylene group, and Ar 2 represents a biphenylene group, and g and h are 0, it is more preferable that the epoxy resin is a biphenylaralkyl type epoxy resin.

[0020] [ka]

[0021] In formula (2), there are multiple R c each independently represents a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms. 5 represents the degree of polymerization, and its average value is 0 to 4.

[0022] [ka]

[0023] In formula (3), there are multiple R d and R e each independently represents a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms. 6 represents the degree of polymerization, and its average value is 0 to 4. In this embodiment, there are multiple R d represents a hydrogen atom, and multiple Re represents a methyl group, a bisphenol F type epoxy resin is more preferred.

[0024] The epoxy resin may be contained in an amount of preferably 1 to 20 mass %, more preferably 2 to 15 mass %, and even more preferably 3 to 12 mass %, based on the total solids mass of the resin composition for forming a circuit board of this embodiment. By setting the content of the epoxy resin to be equal to or greater than the above-mentioned lower limit, a low dielectric loss tangent can be obtained. On the other hand, by setting the content of the epoxy resin to be equal to or less than the above-mentioned upper limit, an increase in viscosity can be suppressed, and good impregnation properties can be obtained.

[0025] When the thermosetting resin (A) contains an epoxy resin, it is preferable to use an active ester curing agent (D) described below.

[0026] (benzoxazine resin) The thermosetting resin (A) can include a benzoxazine resin. The benzoxazine resin of this embodiment is a (co)polymer (ring-opening polymer) of a compound having two or more benzoxazine rings. From the viewpoint of improving heat resistance, the compound having two or more benzoxazine rings can include, for example, at least one of a compound represented by the following general formula (4) and a compound represented by the following general formula (5), and preferably includes at least a compound represented by the following general formula (4).

[0027] [ka]

[0028] In the general formula (4), R3 is a divalent organic group having 1 to 30 carbon atoms, and may contain one or more of an oxygen atom and a nitrogen atom. From the viewpoint of improving the high-temperature storage properties of the encapsulant, R3 is preferably an organic group containing an aromatic ring. In this embodiment, the compound represented by the general formula (4) may be, for example, a compound represented by the following formula (4a):

[0029] [ka]

[0030] [ka]

[0031] In the general formula (5), R4 is a divalent organic group having 1 to 30 carbon atoms, and may contain one or more of an oxygen atom, a nitrogen atom, and a sulfur atom. Two R5 are each independently an aromatic hydrocarbon group having 1 to 12 carbon atoms.

[0032] The content of the benzoxazine resin is preferably 8% by mass or more, more preferably 10% by mass or more, and even more preferably 12% by mass or more, based on the total amount of the resin composition for forming a circuit board (solid content). By making the content of the benzoxazine resin equal to or more than the above lower limit, the linear expansion coefficient is reduced, making it easier to suppress warpage. On the other hand, the content of the benzoxazine resin is preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 28% by mass or less, based on the total amount of the resin composition for forming a circuit board (solid content). By setting the content of the benzoxazine resin to the above upper limit or less, the cured product of the resin composition for forming a circuit board can be made to have good embeddability while maintaining good elasticity.

[0033] [Stress reducing agent (B)] The stress reducing agent (B) contains one or more selected from the group consisting of urethane acrylate (B1), epoxidized polybutadiene (B2), and silicone particles (B3).

[0034] In the cured product obtained by curing the resin composition for forming a circuit board of this embodiment, a domain phase of the stress-reducing agent (B) is formed in a continuous phase of the thermosetting resin (A). The average domain size of the domain phase of the stress reducing agent (B) is preferably 8 μm or less, more preferably 6 μm or less, and even more preferably 5 μm or less. The lower limit is not particularly limited, but is 0.01 μm or more, preferably 0.05 μm or more. When the average domain size of the domain phase of the stress-reducing agent (B) is within the above range, the resin composition for forming a circuit board can give a cured product with an excellent low modulus of elasticity and a low coefficient of linear expansion.

[0035] In this embodiment, the average domain size of the domain phase of the stress-reducing agent (B) is determined by impregnating a fiber substrate with the resin composition for forming a circuit board of this embodiment, heat-treating the resulting prepreg for 2 hours at 200°C, polishing the cross section of the cured product, and photographing the cross section with a scanning electron microscope. From the image, 10 domain phases are randomly selected, and their domain sizes are measured by approximating them to circles using image processing and analysis software, and the average value is the average domain size.

[0036] (Urethane acrylate (B1)) The stress reducing agent (B) includes a urethane acrylate (B1). Any known urethane acrylate (B1) can be used as long as it is a resin having an acrylic group at the terminal and a urethane bond in the structure, as long as the effects of the present invention are achieved.

[0037] In this embodiment, for example, the urethane acrylate (B1) can be obtained by reacting a polyol compound (b1) with a compound (b2) made of a diisocyanate and a (meth)acrylate having an active hydrogen group.

[0038] The polyol compound (b1) is not particularly limited, and examples thereof include polyether polyols, polycarbonate polyols, and polyester polyols. Among these, polyether polyols and polyester polyols are preferred as the polyol compound (b1) of the present embodiment. Furthermore, among polyether polyols, polyoxyalkylene polyols are particularly preferred.

[0039] Examples of polyoxyalkylene polyols include polyoxyethylene polyols, polyoxypropylene polyols, poly(oxyethylene-oxypropylene) polyols, polyoxytetramethylene polyols, etc. Preferred polyoxyalkylene polyols are polyoxypropylene polyols and oxyethylene-terminated polyoxypropylene polyols.

[0040] The compound (b2) can be obtained by reacting a diisocyanate compound with a (meth)acrylate having an active hydrogen group. The diisocyanate is not particularly limited, and examples thereof include aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates, etc. As the diisocyanate of the present embodiment, alicyclic diisocyanates are preferred, and among alicyclic diisocyanates, isophorone diisocyanate is preferred.

[0041] Examples of alicyclic diisocyanates include 4,4'-methylenebis(cyclohexyl isocyanate), methylcyclohexane-2,4 (or 2,6)-diisocyanate, 1,3-(isocyanatomethyl)cyclohexane, isophorone diisocyanate, dimer acid diisocyanate, 1,3-cyclohexylene diisocyanate, and 4,4'-methylene-bis(cyclohexyl isocyanate).

[0042] Specific examples of the active hydrogen group include a hydroxyl group, an amino group, and an imino group, with a hydroxyl group being particularly preferred.In this specification, "(meth)acrylate" means methacrylate and acrylate.

[0043] Examples of (meth)acrylates having an active hydrogen group include hydroxy(meth)acrylates such as 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, 2-hydroxybutyl(meth)acrylate, 3-hydroxybutyl(meth)acrylate, polyethylene glycol mono(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, and 2-hydroxy-1-acryloxy-3-(meth)acrylate.

[0044] The compound (b2) can be obtained by reacting a diisocyanate with a (meth)acrylate having an active hydrogen group in a molar ratio of 1:1.

[0045] The urethane acrylate (B1) is prepared by reacting a polyol compound (b1) with a compound (b2) to form a urethane-forming reaction, whereby the active hydrogen groups in the polyol react with the isocyanate groups in the compound (b2) to form a bond between the two compounds. The reaction time for the urethane-forming reaction varies depending on the presence or absence of a catalyst, the type of catalyst, and the temperature, but is generally 12 to 36 hours. The reaction temperature is 50 to 150°C.

[0046] As the urethane acrylate (B1), for example, a resin represented by the following general formula (a) can be used.

[0047] [ka]

[0048] In general formula (a), Q 1 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and are preferably a hydrogen atom or a methyl group. X 1 are each independently a linear or branched alkylene group having 1 to 6 carbon atoms, and preferably a linear alkylene group having 2 to 4 carbon atoms.

[0049] X 2are each independently a divalent group having a linear or branched alkylene group having 1 to 6 carbon atoms or an alicyclic group having 3 to 20 carbon atoms, and are preferably a divalent group having an alicyclic group having 3 to 20 carbon atoms. Preferred examples of the divalent group having an alicyclic group having 3 to 20 carbon atoms include the following groups.

[0050] [ka]

[0051] In the above formula, R 1 are each independently a linear or branched alkylene group having 1 to 15 carbon atoms which may have a single bond or a double bond, and are preferably a linear alkylene group having 1 to 10 carbon atoms which may have a single bond or a double bond. R 2 represents a linear or branched alkyl group having 1 to 8 carbon atoms. a represents an integer of 0 to 4;

[0052] R 3 are each independently a single bond or a linear or branched alkylene group having 1 to 5 carbon atoms, and are preferably a single bond or a linear alkylene group having 1 to 3 carbon atoms. R 4 represents a single bond or a linear or branched alkylene group having 1 to 3 carbon atoms. * indicates a bond.

[0053] In general formula (a), X 3 are each independently a linear or branched alkylene group having 1 to 10 carbon atoms, and preferably a linear or branched alkylene group having 2 to 8 carbon atoms. n represents the average number of repeating units of 5 to 500. The urethane acrylate (B1) has low elasticity and excellent dispersibility in the thermosetting resin (A), so that the cured product obtained from the resin composition for forming a circuit board of this embodiment has a low elastic modulus and a low coefficient of linear expansion.

[0054] In the present embodiment, the mass average molecular weight of the urethane acrylate (B1) is preferably 100 or more and 80,000 or less, more preferably 500 or more and 60,000 or less, and even more preferably 1,000 or more and 30,000 or less.

[0055] The mass average molecular weight may be measured by a general molecular weight measurement method, and specifically, may be a value measured using gel permeation chromatography (GPC).

[0056] By setting the mass average molecular weight of the urethane acrylate (B1) to the above lower limit or more, the excellent dielectric properties of the polyether resin are exhibited, and the cured product thereof is further provided with a resin composition having excellent adhesion and heat resistance. On the other hand, by setting the mass average molecular weight of the urethane acrylate (B1) to the above upper limit or less, the moldability, solvent solubility, and storage stability are improved.

[0057] The urethane acrylate (B1) has excellent dispersibility, and in the cured product obtained by curing the resin composition for forming a circuit board of this embodiment, a domain phase of the urethane acrylate (B1) is formed in a continuous phase of the thermosetting resin (A), forming a phase-separated structure consisting of these phases. The phase-separated structure is a sea-island structure, in which the sea phase is composed of the continuous phase and the island phase is composed of the domain phase.

[0058] The average domain size of the domain phase is preferably 8 μm or less, more preferably 6 μm or less, and even more preferably 5 μm or less. The lower limit is not particularly limited, but is 0.01 μm or more, preferably 0.05 μm or more. When the average domain size of the domain phase of the urethane acrylate (B1) is within the above range, the resin composition for forming a circuit board can give a cured product with a low modulus of elasticity and a low coefficient of linear expansion.

[0059] The content of the urethane acrylate (B1) is preferably 0.1 to 15 mass %, more preferably 0.2 to 10 mass %, and even more preferably 0.5 to 5 mass %, based on the total solid mass of the resin composition.

[0060] By setting the content of the urethane acrylate (B1) to the above lower limit or more, a low modulus of elasticity and a low coefficient of linear expansion can be obtained. On the other hand, by setting the content of the urethane acrylate (B1) to the above upper limit or less, an increase in viscosity can be suppressed, and good moldability and impregnation properties can be obtained.

[0061] (Epoxidized polybutadiene (B2)) The epoxidized polybutadiene (B2) has a structure in which an epoxy group is introduced into polybutadiene. The epoxy equivalent of the epoxidized polybutadiene (B2) is 100 g / eq or more and 220 g / eq or less, preferably 120 g / eq or more and 200 g / eq or less, more preferably 140 g / eq or more and 180 g / eq or less. By ensuring that the epoxy equivalent is within the above range, the domain size can be reduced, and an excellent cured product can be obtained with a low modulus of elasticity and a low coefficient of linear expansion.

[0062] The viscosity of the epoxidized polybutadiene (B2) at 45°C is preferably 2,000 MPa·s or more and 30,000 mPa / s or less, more preferably 3,000 MPa·s or more and 20,000 mPa / s or less, and even more preferably 4,000 MPa·s or more and 10,000 mPa / s or less. When the viscosity is within the above range, the composition has excellent dispersibility in the thermosetting resin (A), and an excellent cured product can be obtained due to its low modulus of elasticity and low coefficient of linear expansion.

[0063] The viscosity can be measured by a Brookfield viscometer.

[0064] As the epoxidized polybutadiene (B2), for example, a resin represented by the following general formula (i) can be used.

[0065] [ka] In general formula (i), R 1 and R 2 each independently represents a hydrogen atom, a hydroxyl group, or an alkyl group having 1 to 3 carbon atoms, preferably a hydrogen atom or a hydroxyl group, more preferably a hydrogen atom. n represents the average number of repeating units of 5 to 100. The epoxidized polybutadiene (B2) represented by the general formula (i) is Epolead PB3600 (where R 1 and R 2 is a hydroxyl group, manufactured by Daicel Chemical Industries, Ltd.), Epolead PB4700 (where R 1 and R 2 is a hydrogen atom, manufactured by Daicel Chemical Industries, Ltd.

[0066] In the cured product obtained by curing the resin composition for forming a circuit board of this embodiment, domain phases of the epoxidized polybutadiene (B2) are formed in a continuous phase of the thermosetting resin (A), and a phase-separated structure consisting of these phases is formed. The phase-separated structure is a sea-island structure, in which the sea phase is composed of the continuous phase and the island phase is composed of the domain phase.

[0067] The average domain size of the domain phase is preferably 8 μm or less, more preferably 6 μm or less, and even more preferably 5 μm or less. The lower limit is not particularly limited, but is 0.01 μm or more, preferably 0.05 μm or more. When the average domain size of the domain phase of the epoxidized polybutadiene (B2) is within the above range, the resin composition for forming a circuit board can give a cured product with an even lower modulus of elasticity and a lower coefficient of linear expansion.

[0068] The content of the epoxidized polybutadiene (B2) is preferably 0.05 to 10 mass %, more preferably 0.1 to 8 mass %, and even more preferably 0.15 to 5 mass %, based on the total solid mass of the resin composition.

[0069] By setting the content of the epoxidized polybutadiene (B2) to the above lower limit or more, a low modulus of elasticity and a low coefficient of linear expansion can be obtained. On the other hand, by setting the content of the epoxidized polybutadiene (B2) to the above upper limit or less, an increase in viscosity can be suppressed, and good moldability and impregnation properties can be obtained.

[0070] (Silicone particles (B3)) Examples of silicone particles (B3) include silicone composite powders having a structure in which rubber powder is coated with silicone resin, silicone resin powders having a structure in which silicone resin is crosslinked in a three-dimensional network pattern, and silicone rubber powders having a structure in which linear silicone resin is crosslinked, and these can be used alone or in combination of two or more.

[0071] The silicone particles (B3) are preferably silicone composite powder or silicone resin powder, such as phenyl-modified silicone resin powder and alkyl group-containing silicone resin powder.

[0072] The silicone particles (B3) have high heat resistance, low elasticity, and excellent dispersibility in the thermosetting resin (A), and therefore the cured product obtained from the resin composition for forming a circuit board of this embodiment has excellent mechanical strength, a low elastic modulus, and a low coefficient of linear expansion.

[0073] In this embodiment, in a thermogravimetric analysis in which the silicone particles (B3) are heated from room temperature at a rate of 10°C / min, the temperature at which the thermal weight loss rate reaches 5% by mass is preferably 250°C or higher, more preferably 280°C or higher, and even more preferably 300°C or higher. As a result, a cured product obtained from the resin composition for forming a circuit board has better heat resistance, and a semiconductor package using the cured product has better product reliability.

[0074] Average particle size (median diameter) of silicone particles (B3) D 50is preferably 0.2 μm or more and 10.0 μm or less, more preferably 0.5 μm or more and 8.0 μm or less, and even more preferably 1.0 μm or more and 5.0 μm or less. When the average particle size of the silicone particles (B3) is within the above range, they have excellent dispersibility in the thermosetting resin (A), and therefore an excellent cured product can be obtained with a low modulus of elasticity and a low coefficient of linear expansion. The average particle size (median size) can be measured on a volume basis using, for example, a laser diffraction / scattering particle size distribution measuring device.

[0075] Silicone particles (B3) have a sharp particle size distribution, and the cumulative 90% particle diameter (D 90 ) and cumulative 10% particle size (D 10 ) and the difference (D 90 -D 10 ) is preferably 7.0 μm or less, more preferably 5.0 μm or less, and even more preferably 3.0 μm or less. There is no particular restriction on the lower limit, but it is 1.0 μm or more.

[0076] When the particle size distribution of the silicone particles (B3) is within the above range, the silicone particles (B3) have excellent dispersibility in the thermosetting resin (A) and are uniformly present in the composition and the cured product, making it possible to obtain an excellent cured product with a low modulus of elasticity and a low coefficient of linear expansion.

[0077] Examples of silicone resin powders used in this embodiment include KMP-590, KMP-701, X-52-854, and KMP-708 (phenyl-modified with a three-dimensional network crosslinked structure) manufactured by Shin-Etsu Chemical Co., Ltd., and Tospearl 120, Tospearl 130, Tospearl 140, XC99-A8808, and XR39-D0490 (methyl-containing with a three-dimensional network crosslinked structure) manufactured by Momentive Corp. Examples of silicone composite powders include KMP-600, KMP-601, KMP-605, X-52-7030, X-52-7143, X-52-5153A, and X-52-5153B manufactured by Shin-Etsu Chemical Co., Ltd.

[0078] In the cured product obtained by curing the resin composition for forming a circuit board of this embodiment, the silicone particles (B3) are dispersed in the thermosetting resin (A) to form a domain phase. The average domain size of the domain phase is the average particle size.

[0079] The content of the silicone particles (B3) is preferably 1 to 30 mass % relative to the total solid mass of the resin composition, more preferably 2 to 20 mass %, and even more preferably 3 to 12 mass %.

[0080] By setting the content of the silicone particles (B3) at or above the lower limit, a low modulus of elasticity and a low coefficient of linear expansion can be obtained, while by setting the content of the silicone particles (B3) at or below the upper limit, an increase in viscosity is suppressed, and good moldability and impregnation properties can be obtained.

[0081] In this embodiment, the stress reducing agent (B) contains one or more selected from the group consisting of urethane acrylate (B1), epoxidized polybutadiene (B2) and silicone particles (B3), preferably two or more, and more preferably three of these.

[0082] When the stress-reducing agent (B) contains (B1) and (B2), the amount of the stress-reducing agent (B) is, relative to the total solid content by mass of the resin composition for forming a circuit board, The content of the urethane acrylate (B1) is preferably 0.1 to 15 mass%, more preferably 0.2 to 10 mass%, and even more preferably 0.5 to 5 mass%, The content of the epoxidized polybutadiene (B2) is preferably from 0.05 to 10% by mass, more preferably from 0.1 to 8% by mass, and even more preferably from 0.15 to 5% by mass. This makes it possible to obtain a resin composition for forming circuit boards that has excellent moldability, and also to obtain a cured product that has a low modulus of elasticity and a low coefficient of linear expansion.

[0083] When the stress-reducing agent (B) contains (B1) and (B3), the amount of the stress-reducing agent (B) is, relative to the total solid content by mass of the resin composition for forming a circuit board, The content of the urethane acrylate (B1) is preferably 0.1 to 15 mass%, more preferably 0.2 to 10 mass%, and even more preferably 0.5 to 5 mass%, The content of the silicone particles (B3) is preferably from 1 to 30% by mass, more preferably from 2 to 20% by mass, and even more preferably from 3 to 10% by mass. This makes it possible to obtain a resin composition for forming circuit boards that has excellent moldability, and also to obtain a cured product that has a low modulus of elasticity and a low coefficient of linear expansion.

[0084] When the stress-reducing agent (B) contains (B2) and (B3), the amount of the stress-reducing agent (B) is, relative to the total solid content by mass of the resin composition for forming a circuit board, The content of the epoxidized polybutadiene (B2) is preferably 0.05 to 10 mass%, more preferably 0.1 to 8 mass%, and even more preferably 0.15 to 5 mass%, The content of the silicone particles (B3) is preferably from 1 to 30% by mass, more preferably from 2 to 20% by mass, and even more preferably from 3 to 10% by mass. This makes it possible to obtain a resin composition for forming circuit boards that has excellent moldability, and also to obtain a cured product that has a low modulus of elasticity and a low coefficient of linear expansion.

[0085] When the stress-reducing agent (B) contains all of (B1) to (B3), the amount of the stress-reducing agent (B) relative to the total solid content by mass of the resin composition for forming a circuit board is: The content of the urethane acrylate (B1) is preferably 0.1 to 15 mass%, more preferably 0.2 to 10 mass%, and even more preferably 0.5 to 5 mass%, The content of the epoxidized polybutadiene (B2) is preferably 0.05 to 10 mass%, more preferably 0.1 to 8 mass%, and even more preferably 0.15 to 5 mass%, The content of the silicone particles (B3) is preferably from 1 to 30% by mass, more preferably from 2 to 20% by mass, and even more preferably from 3 to 10% by mass. This makes it possible to obtain a resin composition for forming circuit boards that has excellent moldability, and also to obtain a cured product that has a low modulus of elasticity and a low coefficient of linear expansion.

[0086] In this embodiment, other stress-reducing agents may be contained in addition to the stress-reducing agent (B). Examples of other stress-reducing agents include silicone oil, silicone rubber, and carboxyl-terminated butadiene acrylonitrile rubber. When other stress-reducing agents are contained, the content of the other stress-reducing agents is preferably 0.1 to 10 mass% relative to the total solid mass of the resin composition for forming a circuit board.

[0087] [Inorganic filler (C)] Examples of the inorganic filler (C) include silicates such as talc, calcined clay, uncalcined clay, mica, and glass; oxides such as titanium oxide, alumina, boehmite, silica, and fused silica; carbonates such as calcium carbonate, magnesium carbonate, and hydrotalcite; hydroxides such as aluminum hydroxide, magnesium hydroxide, and calcium hydroxide; sulfates or sulfites such as barium sulfate, calcium sulfate, and calcium sulfite; borates such as zinc borate, barium metaborate, aluminum borate, calcium borate, and sodium borate; nitrides such as aluminum nitride, boron nitride, silicon nitride, and carbon nitride; and titanates such as strontium titanate and barium titanate. Among these, talc, alumina, glass, silica, mica, aluminum hydroxide, and magnesium hydroxide are preferred, and silica is particularly preferred. As the inorganic filler, one of these may be used alone, or two or more may be used in combination.

[0088] The lower limit of the average particle diameter of the inorganic filler (C) is not particularly limited, but may be, for example, 0.01 μm or more, or 0.05 μm or more. This can prevent the viscosity of the resin composition for circuit boards of this embodiment from increasing, improving workability during the production of an insulating layer. The upper limit of the average particle diameter of the inorganic filler (C) is also not particularly limited, but is, for example, preferably 5.0 μm or less, more preferably 2.0 μm or less, and even more preferably 1.0 μm or less. This can prevent phenomena such as sedimentation of the inorganic filler in the resin composition for circuit boards of this embodiment, allowing a more uniform resin film to be obtained.

[0089] In this embodiment, the average particle diameter of the inorganic filler (C) is determined by measuring the particle size distribution of the particles on a volume basis using, for example, a laser diffraction particle size distribution analyzer (LA-500 manufactured by HORIBA Corporation) and determining the particle diameter at which the cumulative 50% of the particle size distribution is reached (D 50 ) can be used as the average particle size.

[0090] The inorganic filler (C) preferably contains silica particles. The silica particles may be spherical. The average particle size of the silica particles is not particularly limited, but may be, for example, 5.0 μm or less, 0.1 μm or more and 4.0 μm or less, or 0.2 μm or more and 2.0 μm or less. This can further improve the filling property of the inorganic filler (C).

[0091] The content of the inorganic filler (C) is preferably 40 to 85 mass %, more preferably 45 to 80 mass %, and even more preferably 50 to 70 mass %, based on the total solid content mass of the resin composition. By setting the content of the inorganic filler (C) to the above lower limit or more, it is possible to provide a cured resin film with a particularly low linear expansion coefficient while maintaining impregnation properties. On the other hand, by setting the content of the inorganic filler (C) to the above upper limit or less, it is possible to reduce the viscosity of the resin composition, which makes it easier to improve moldability and impregnation properties.

[0092] [Active ester curing agent (D)] When the thermosetting resin (A) contains an epoxy resin, an active ester curing agent (D) can be used. The active ester curing agent (D) may be a compound having one or more active ester groups in one molecule. Among them, preferred active ester curing agents (D) are compounds having two or more highly reactive ester groups in one molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds.

[0093] Preferred examples of the active ester curing agent (D) include active ester curing agents containing a dicyclopentadiene-type diphenol structure, active ester curing agents containing a naphthalene structure, active ester curing agents containing an acetylated product of phenol novolac, and active ester curing agents containing a benzoylated product of phenol novolac, and at least one of these may be used. Among these, active ester curing agents containing a naphthalene structure and active ester curing agents containing a dicyclopentadiene-type diphenol structure are more preferred. The "dicyclopentadiene-type diphenol structure" refers to a divalent structural unit consisting of phenylene-dicyclopentylene-phenylene.

[0094] In this embodiment, the active ester curing agent (D) may be, for example, a resin having a structure represented by the following general formula (1).

[0095] [ka]

[0096] In general formula (1), "B" is a structure represented by general formula (B).

[0097] [ka]

[0098] In general formula (B), Ar is a substituted or unsubstituted arylene group. Examples of the substituent of the substituted arylene group include an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group, and an aralkyl group.

[0099] Y is a single bond, a substituted or unsubstituted linear alkylene group having 1 to 6 carbon atoms, a substituted or unsubstituted cyclic alkylene group having 3 to 6 carbon atoms, a substituted or unsubstituted divalent aromatic hydrocarbon group, an ether bond, a carbonyl group, a carbonyloxy group, a sulfide group, or a sulfone group. Substituents for the above groups include alkyl groups having 1 to 4 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, phenyl groups, and aralkyl groups.

[0100] Preferred examples of Y include a single bond, a methylene group, -CH(CH3)2-, an ether bond, an optionally substituted cycloalkylene group, and an optionally substituted 9,9-fluorenylene group. n is an integer of 0 to 4, and is preferably 0 or 1. Specifically, B is a structure represented by the following general formula (B1) or (B2).

[0101] [ka]

[0102] In the general formula (B1) and the general formula (B2), Ar and Y have the same meanings as in the general formula (B). A is a substituted or unsubstituted arylene group linked via an aliphatic cyclic hydrocarbon group; Ar' is a substituted or unsubstituted aryl group; k is the average value of the repeating units and is in the range of 0.25 to 3.5.

[0103] The resin composition for forming a circuit board of this embodiment contains a specific active ester curing agent, and the resulting cured product can have excellent dielectric properties and an excellent low dielectric loss tangent.

[0104] The active ester curing agent (D) used in the resin composition for forming a circuit board of this embodiment has an active ester group represented by formula (B). In the curing reaction between the epoxy resin and the active ester curing agent, the active ester group of the active ester curing agent reacts with the epoxy group of the epoxy resin to generate a secondary hydroxyl group. This secondary hydroxyl group is blocked by the ester residue of the active ester curing agent. This reduces the dielectric tangent of the cured product. In one embodiment, the structure represented by the above formula (B) is preferably at least one selected from the following formulae (B-1) to (B-6).

[0105] [ka]

[0106] In formulas (B-1) to (B-6), R 1 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group, or an aralkyl group,

[0107] R 2 are each independently any one of an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a phenyl group, and X is any one of a linear alkylene group having 2 to 6 carbon atoms, an ether bond, a carbonyl group, a carbonyloxy group, a sulfide group, and a sulfone group, n is an integer of 0 to 4, and p is an integer of 1 to 4.

[0108] The structures represented by the above formulas (B-1) to (B-6) are all highly oriented structures. Therefore, when an active ester curing agent containing such a structure is used, the resulting cured resin composition for forming a circuit board has a low dielectric tangent and excellent adhesion to metals, and is therefore suitable for use as a semiconductor encapsulation material.

[0109] Among them, from the viewpoint of low dielectric loss tangent, active ester curing agents having a structure represented by formula (B-2), formula (B-3) or formula (B-5) are preferred, and more preferred are active ester curing agents having a structure in which n is 0 in formula (B-2), a structure in which X is an ether bond in formula (B-3), or a structure in formula (B-5) in which two carbonyloxy groups are at the 4,4'-positions. 1 are preferably all hydrogen atoms.

[0110] In formula (1), "Ar'" is an aryl group, such as a phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, 3,5-xylyl group, o-biphenyl group, m-biphenyl group, p-biphenyl group, 2-benzylphenyl group, 4-benzylphenyl group, 4-(α-cumyl)phenyl group, 1-naphthyl group, 2-naphthyl group, etc. Among these, a 1-naphthyl group or a 2-naphthyl group is preferred, as this gives a cured product with a particularly low dielectric dissipation factor.

[0111] In this embodiment, "A" in the active ester curing agent represented by formula (1) is a substituted or unsubstituted arylene group linked via an aliphatic cyclic hydrocarbon group. Examples of such arylene groups include a structure obtained by a polyaddition reaction between an unsaturated aliphatic cyclic hydrocarbon compound containing two double bonds in one molecule and a phenolic compound.

[0112] Examples of the unsaturated aliphatic cyclic hydrocarbon compound containing two double bonds per molecule include dicyclopentadiene, cyclopentadiene polymers, tetrahydroindene, 4-vinylcyclohexene, 5-vinyl-2-norbornene, and limonene. These may be used alone or in combination of two or more. Among these, dicyclopentadiene is preferred because it can produce cured products with excellent heat resistance. Since dicyclopentadiene is contained in petroleum fractions, industrial dicyclopentadiene may contain cyclopentadiene polymers and other aliphatic or aromatic diene compounds as impurities. However, considering performance such as heat resistance, curability, and moldability, it is desirable to use a dicyclopentadiene product with a purity of 90% by mass or higher.

[0113] On the other hand, examples of the phenolic compound include phenol, cresol, xylenol, ethylphenol, isopropylphenol, butylphenol, octylphenol, nonylphenol, vinylphenol, isopropenylphenol, allylphenol, phenylphenol, benzylphenol, chlorophenol, bromophenol, 1-naphthol, 2-naphthol, 1,4-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, etc., and these may be used alone or in combination of two or more. Among these, phenol is preferred because it serves as an active ester curing agent with high curability and excellent dielectric properties in the cured product.

[0114] In a preferred embodiment, "A" in the active ester curing agent represented by formula (1) has a structure represented by formula (A): A resin composition containing an active ester curing agent in which "A" in formula (1) has the following structure produces a cured product with a low dielectric tangent and excellent adhesion.

[0115] [ka]

[0116] In formula (A), R 3 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group, or an aralkyl group, l is 0 or 1, and m is an integer of 1 or more.

[0117] Among the active ester curing agents represented by formula (1), more preferred are resins represented by the following formulas (1-1), (1-2) and (1-3), and particularly preferred is resin represented by the following formula (1-3).

[0118] [ka]

[0119] In formula (1-1), R 1 and R 3 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group, or an aralkyl group; Z is a phenyl group, a naphthyl group, or a phenyl group or naphthyl group having 1 to 3 alkyl groups having 1 to 4 carbon atoms on the aromatic nucleus; l is 0 or 1; and k is the average of the repeating units and is 0.25 to 3.5.

[0120] [ka]

[0121] In formula (1-2), R 1 and R 3 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group, or an aralkyl group; Z is a phenyl group, a naphthyl group, or a phenyl group or naphthyl group having 1 to 3 alkyl groups having 1 to 4 carbon atoms on the aromatic nucleus; l is 0 or 1; and k is the average of the repeating units and is 0.25 to 3.5.

[0122] [ka]

[0123] In formula (1-3), R 1 and R 3 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group, or an aralkyl group; Z is a phenyl group, a naphthyl group, or a phenyl group or naphthyl group having 1 to 3 alkyl groups having 1 to 4 carbon atoms on the aromatic nucleus; l is 0 or 1; and k is the average of the repeating units and is 0.25 to 3.5.

[0124] The active ester curing agent (D) used in this embodiment can be produced by a known method in which a phenolic compound (a) having a structure in which multiple aryl groups each having a phenolic hydroxyl group are linked via an aliphatic cyclic hydrocarbon group, an aromatic nucleus-containing dicarboxylic acid or a halide thereof (b), and an aromatic monohydroxy compound (c) are reacted.

[0125] The reaction ratios of the phenolic compound (a), aromatic nucleus-containing dicarboxylic acid or its halide (b), and aromatic monohydroxy compound (c) can be appropriately adjusted depending on the desired molecular design. Among these, since an active ester curing agent with higher curing properties can be obtained, it is preferable to use the respective raw materials in a ratio such that the phenolic hydroxyl groups of the phenolic compound (a) are in the range of 0.25 to 0.90 moles and the hydroxyl groups of the aromatic monohydroxy compound (c) are in the range of 0.10 to 0.75 moles per mole of the total of carboxyl groups or acid halide groups of the aromatic nucleus-containing dicarboxylic acid or its halide (b), and it is more preferable to use the respective raw materials in a ratio such that the phenolic hydroxyl groups of the phenolic compound (a) are in the range of 0.50 to 0.75 moles and the hydroxyl groups of the aromatic monohydroxy compound (c) are in the range of 0.25 to 0.50 moles.

[0126] Furthermore, when the total number of functional groups in the resin is the sum of the arylcarbonyloxy groups and phenolic hydroxyl groups in the resin structure, the functional group equivalent of the active ester curing agent (D) is preferably in the range of 200 g / eq or more and 230 g / eq or less, and more preferably in the range of 210 g / eq or more and 220 g / eq or less, in order to obtain a cured product with excellent curability and low dielectric constant and dielectric dissipation factor.

[0127] In the resin composition for forming a circuit board of this embodiment, the blending amounts of the active ester curing agent (D) and the epoxy resin are preferably such that the epoxy groups in the epoxy resin are 0.8 to 1.2 equivalents per equivalent of the total active groups in the active ester curing agent (D), since this results in a cured product with excellent curing properties and a low dielectric loss tangent. Here, the active groups in the active ester curing agent (D) refer to arylcarbonyloxy groups and phenolic hydroxyl groups in the resin structure.

[0128] The active ester curing agent (D) is used in an amount of preferably 2% by mass or more and 25% by mass or less, more preferably 5% by mass or more and 20% by mass or less, and even more preferably 7% by mass or more and 15% by mass or less, based on the total solid content mass of the resin composition. By including the specific active ester curing agent in the above range, the resulting cured product can have better dielectric properties and an even lower dielectric loss tangent.

[0129] [Other ingredients] The resin composition for forming a circuit board of this embodiment can be appropriately blended with other additives as needed, such as resins other than those described above, colorants, coupling agents, curing accelerators, curing agents, leveling agents, and organic fillers. The resin composition for forming a circuit board of this embodiment can be suitably used in a liquid form in which the above components are dissolved and / or dispersed in an organic solvent or the like.

[0130] Examples of resins other than those mentioned above include thermosetting resins such as benzocyclobutene resin, thermoplastic resins, phenoxy resins, cyanate resins, and the like. [Cyanate resin] The cyanate resin makes it easier to obtain a low coefficient of thermal expansion, a low dielectric constant, and a low dielectric loss tangent. It also improves peel strength and heat resistance.

[0131] The cyanate resin is preferably an aromatic cyanate resin, and specific examples thereof include novolac cyanate resins such as phenol novolac and cresol novolac; aralkyl cyanate resins such as phenyl aralkyl, biphenyl aralkyl, and naphthalene aralkyl; and bisphenol cyanate resins such as bisphenol A cyanate resin, bisphenol E cyanate resin, and tetramethyl bisphenol F cyanate resin.

[0132] Among these, bisphenol-type cyanate and / or novolac-type cyanate resins are preferred, and a combination of both is even more preferred. The reason for this is that bisphenol-type cyanate ester resins have fewer crosslinking points, so when triazine rings are formed, unreacted cyanate groups are less likely to remain, making it easier to maintain good dielectric properties. Furthermore, novolac-type cyanate resins form triazine rings after the curing reaction, which improves rigidity and heat resistance and makes them easier to accommodate miniaturization and higher frequencies. As the novolac type cyanate resin, for example, one represented by the following formula (I) can be used.

[0133] [ka]

[0134] The average repeating unit number n of the novolac cyanate resin represented by general formula (I) is any integer. The average repeating unit number n is not particularly limited, but is preferably 1 or more, more preferably 2 or more. When the average repeating unit number n is equal to or greater than the above-mentioned lower limit, the heat resistance of the novolac cyanate resin is improved, and elimination and volatilization of oligomers during heating can be suppressed. Furthermore, the average repeating unit number n is not particularly limited, but is preferably 10 or less, more preferably 7 or less. When n is equal to or less than the above-mentioned upper limit, an increase in melt viscosity can be suppressed, and the moldability of the prepreg can be improved.

[0135] The cyanate resin may also be modified, for example, it may contain butadiene-modified cyanate modified with butadiene. Specifically, the butadiene-modified cyanate may be obtained by mixing a cyanate ester compound with polybutadiene and then thermally polymerizing the mixture, and / or by mixing a polymer of a cyanate ester compound with polybutadiene and then thermally polymerizing the mixture. This allows for good heat resistance while achieving both good dielectric properties and low warpage.

[0136] Although there are no particular limitations on the lower limit of the weight-average molecular weight (Mw) of the cyanate resin, Mw is preferably at least 500, and more preferably at least 600. When Mw is at least the above lower limit, the occurrence of tackiness can be suppressed when a prepreg is produced, and the prepregs can be prevented from adhering to each other when they come into contact with each other, or from transferring.

[0137] Furthermore, the upper limit of Mw is not particularly limited, but is preferably not more than 4,500, more preferably not more than 3,000. When Mw is not more than the upper limit, the cyclization reaction of the cyanate resin (C) can be prevented from accelerating, and defects in the insulating layer and a decrease in the peel strength between the insulating layer and the metal layer can be prevented. The Mw of the cyanate resin can be measured, for example, by GPC (gel permeation chromatography, standard substance: polystyrene equivalent).

[0138] Furthermore, one type of cyanate resin may be used alone, or two or more types having different Mw may be used in combination, or one or more types may be used in combination with their prepolymers.

[0139] In this embodiment, the content of the cyanate resin is preferably 0.2 mass % or more, and more preferably 0.5 mass % or more, based on the total solid mass of the resin composition for forming a circuit board of this embodiment.

[0140] On the other hand, the content of the cyanate resin is preferably 10% by mass or less, and more preferably 5% by mass or less, based on the total solid mass of the resin composition for forming a circuit board of this embodiment.

[0141] [Coupling agent] The resin composition for forming a circuit board of this embodiment may contain a coupling agent. The coupling agent may be added directly during preparation of the resin composition, or may be added in advance to the inorganic filler (C). The use of a coupling agent can improve the wettability of the interface between the inorganic filler (C) and each resin. Therefore, the use of a coupling agent is preferable, and the heat resistance of the cured resin film can be improved. Furthermore, the use of a coupling agent can improve adhesion to copper foil. Furthermore, since moisture absorption resistance can be improved, adhesion to copper foil can be maintained even in a humid environment.

[0142] Examples of the coupling agent include silane coupling agents such as vinyl silane coupling agents, epoxy silane coupling agents, cationic silane coupling agents, and amino silane coupling agents, titanate coupling agents, and silicone oil coupling agents. One type of coupling agent may be used alone, or two or more types may be used in combination. In this embodiment, the coupling agent may contain a silane coupling agent. This can increase the wettability at the interface between the hollow silica particles (A) and each resin, and can further improve the heat resistance of the cured resin film.

[0143] As the silane coupling agent, various types can be used, and examples thereof include epoxy silane, amino silane, alkyl silane, ureido silane, mercapto silane, and vinyl silane.

[0144] Specific compounds include, for example, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, N-phenylγ-aminopropyltriethoxysilane, N-phenylγ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropyltriethoxysilane, N-6-(aminohexyl)3-aminopropyltrimethoxysilane, N-(3-(trimethoxysilylpropyl)-1,3-benzenedimethanane, γ-glycidoxypropyl Examples include vinyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, γ-ureidopropyltriethoxysilane, vinyltriethoxysilane, etc., and one or more of these can be used in combination. Among these, vinylsilane, epoxysilane, mercaptosilane, and aminosilane are preferred, and as the aminosilane, primary aminosilane or anilinosilane is more preferred.

[0145] The content of the coupling agent can be appropriately adjusted based on the specific surface area of ​​the inorganic filler (C). The lower limit of the content of such a coupling agent may be, for example, 0.01 parts by mass or more, preferably 0.05 parts by mass or more, per 100 parts by mass of the total solid content of the resin composition. When the content of the coupling agent is equal to or more than the lower limit, the inorganic filler (C) can be sufficiently coated, and the heat resistance of the cured resin film can be improved. On the other hand, the upper limit of the content of the coupling agent may be, for example, 3 parts by mass or less, preferably 1.5 parts by mass or less, per 100 parts by mass of the total solid content of the resin composition. When the content of the coupling agent is equal to or less than the upper limit, the effect on the reaction can be suppressed, and a decrease in the bending strength of the cured resin film can be suppressed.

[0146] (curing accelerator) As the curing accelerator of this embodiment, known accelerators can be used. Examples of the organic compounds include organic metal salts such as zinc naphthenate, cobalt naphthenate, tin octoate, cobalt octoate, zinc octoate, bisacetylacetonate cobalt(II), and trisacetylacetonate cobalt(III); tertiary amines such as triethylamine, tributylamine, and diazabicyclo[2,2,2]octane; imidazoles such as 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 2-phenyl-4-methylimidazole, 2-ethyl-4-ethylimidazole, 2-phenyl-4-ethylimidazole, 2-phenyl-4-methyl-5-hydroxyimidazole, and 2-phenyl-4,5-dihydroxyimidazole; phenolic compounds such as phenol, bisphenol A, and nonylphenol; organic acids such as acetic acid, benzoic acid, salicylic acid, and paratoluenesulfonic acid; and onium salt compounds and derivatives thereof. These may be used alone or in combination of two or more. Among these, imidazole and onium salt compounds are preferred from the viewpoint of stably improving the resin curability. Such onium salt compounds are not particularly limited, but examples thereof include onium salt compounds represented by the following formula (IX):

[0147] [ka]

[0148] In formula (IX), P represents a phosphorus atom, R 1 , R 2 , R 3 and R 4 A each represents an organic group having a substituted or unsubstituted aromatic ring or heterocyclic ring, or a substituted or unsubstituted aliphatic group, and may be the same or different. - represents an anion of a proton donor with a valence of n (n≧1) that has at least one proton in the molecule that can be released outside the molecule, or a complex anion thereof.

[0149] The lower limit of the content of the curing accelerator is not particularly limited, but is preferably 0.005 to 5 mass %, more preferably 0.01 to 2 mass %, of the total resin composition (solid content). By setting the content of the curing accelerator to the above lower limit or more, a good curing acceleration effect can be obtained, while by setting the content of the curing accelerator to the above lower limit or more, the prepreg can be kept in a good state of storage.

[0150] <Varnish> In this embodiment, the varnish-like resin composition for forming a circuit board may contain a solvent. Examples of the solvent include organic solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, ethyl acetate, cyclohexane, heptane, cyclohexane, cyclohexanone, tetrahydrofuran, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ethylene glycol, cellosolve-based solvents, carbitol-based solvents, anisole, and N-methylpyrrolidone. These may be used alone or in combination of two or more.

[0151] When the resin composition for forming a circuit board is in the form of a varnish, the solid content of the resin composition may be, for example, 30% by mass to 80% by mass, more preferably 40% by mass to 70% by mass, which results in a resin composition with excellent workability and film-forming properties.

[0152] The varnish-like resin composition for forming circuit boards can be prepared by dissolving, mixing, and stirring the above-mentioned components in a solvent using various mixers, such as those used in ultrasonic dispersion, high-pressure collision dispersion, high-speed rotation dispersion, bead mill dispersion, high-speed shear dispersion, and rotation-revolution dispersion.

[0153] <Resin composition for circuit board formation> The resin composition for forming a circuit board of this embodiment contains a thermosetting resin (A), a stress-reducing agent (B), and an inorganic filler (C), and in the cured product obtained by curing the composition, a domain phase of the stress-reducing agent (B) is formed in a continuous phase of the thermosetting resin (A). The resin composition gives a cured product with an excellent low modulus of elasticity and a low coefficient of linear expansion.

[0154] The storage modulus E' at 30°C of the cured product obtained by heat-treating a prepreg obtained by impregnating a fiber substrate with the resin composition for forming a circuit board of the present embodiment at 200°C for 2 hours. 30 However, the storage modulus E' can be set to preferably 20.0 GPa or less, more preferably 19.0 GPa or less, and even more preferably 18.0 GPa or less. 30 The lower limit is not particularly limited, but can be 10.0 GPa or more. The prepreg obtained by impregnating a fiber base material with the resin composition for forming a circuit board of this embodiment has an excellent low elastic modulus at 30°C, which can suppress warping of the semiconductor package and further improve the connection reliability between the semiconductor element and the circuit board.

[0155] The storage modulus E' at 250°C of the cured product obtained by heat-treating a prepreg obtained by impregnating a fiber substrate with the resin composition for forming a circuit board of the present embodiment at 200°C for 2 hours is 250However, the storage modulus E' can be set to preferably 13.0 GPa or less, more preferably 12.0 GPa or less, and even more preferably 11.0 GPa or less. 250 The lower limit is not particularly limited, but can be 10.0 GPa or more. The prepreg obtained by impregnating a fiber base material with the resin composition for forming a circuit board of this embodiment has an excellent low elastic modulus at 250°C, which can suppress warping of the semiconductor package under the usage environment and further improve the connection reliability between the semiconductor element and the circuit board.

[0156] Furthermore, the storage modulus E' 30 and storage modulus E' 250 When the bond strength is in the above range, deformation of the prepreg is unlikely to occur even when temperature changes occur, warping can be suppressed in the use environment of a semiconductor package that includes the prepreg as a circuit board, and the connection reliability between the semiconductor element and the printed wiring board can be further improved.

[0157] Storage modulus E' 30 , storage modulus E' 250 Specifically, it can be measured as follows. A varnish-like resin composition for forming circuit boards (methyl ethyl ketone, nonvolatile content 70% by mass) is impregnated into glass woven fabric and dried for 10 minutes in a hot air dryer at 140°C to obtain a 60 μm-thick prepreg. Ultrathin copper foil is placed on both sides of the obtained prepreg, and the resulting prepreg is heated and press-molded at a pressure of 4 MPa and a temperature of 200°C for 2 hours. The copper foil of the resulting metal foil-attached resin substrate is removed by etching to obtain a cured prepreg. The cured product is subjected to dynamic viscoelasticity measurement at a temperature range of -50 to 350°C, a heating rate of 5°C / min, and a frequency of 1 Hz, and the storage modulus at 30°C (and 250°C) is measured.

[0158] Such a storage modulus E' 30 , storage modulus E' 250 To achieve this, it is important to appropriately control the types and amounts of the thermosetting resin (A), stress reducing agent (B), inorganic filler (C), curing accelerator, etc., as well as the prepreg manufacturing method.

[0159] The linear expansion coefficient α1 of the cured product of the prepreg obtained as described above using the resin composition for forming a circuit board of this embodiment, measured under the following condition 1, is preferably 3 ppm / °C or more and 15 ppm / °C or less, more preferably 5 ppm / °C or more and 13 ppm / °C or less, and even more preferably 7 ppm / °C or more and 12 ppm / °C or less. By setting the linear expansion coefficient α1 within the specified temperature range within the above range, the prepreg is less likely to deform even when temperature changes occur, and warping of a semiconductor package that uses the prepreg as a circuit board can be suppressed, further improving the connection reliability between the semiconductor element and the printed wiring board.

[0160] (Condition 1) Using a thermomechanical analyzer, perform two cycles of thermomechanical analysis under the conditions of a temperature range of 30 to 260°C, a heating rate of 10°C / min, a load of 10 g, and compression mode. The average value of the linear expansion coefficient in the planar direction (longitudinal (X) direction) in the range of 50°C to 150°C is defined as the linear expansion coefficient α1.

[0161] Furthermore, the linear expansion coefficient α2 of the cured product of the prepreg obtained as described above using the resin composition for forming a circuit board of this embodiment, measured under the following condition 2, is preferably 5 ppm / °C or more and 18 ppm / °C or less, more preferably 7 ppm / °C or more and 15 ppm / °C or less, and even more preferably 8 ppm / °C or more and 14 ppm / °C or less. Furthermore, since the linear expansion coefficient α2 over a wide temperature range is within the above range, the prepreg is less likely to deform even when temperature changes occur, and warping of a semiconductor package that includes the prepreg as a circuit board can be suppressed, further improving the connection reliability between the semiconductor element and the printed wiring board.

[0162] (Condition 2) Using a thermomechanical analyzer, perform two cycles of thermomechanical analysis under the conditions of a temperature range of 30 to 260°C, a heating rate of 10°C / min, a load of 10 g, and compression mode. The average value of the linear expansion coefficient in the planar direction (longitudinal (X) direction) in the range of 30 to 260°C is defined as the linear expansion coefficient α2.

[0163] In order to achieve such linear expansion coefficients α1 and α2, it is important to appropriately control the types and amounts of the thermosetting resin (A), stress reducing agent (B), inorganic filler (C), curing accelerator, etc., as well as the prepreg manufacturing method.

[0164] Furthermore, the resin composition for forming a circuit board of the present embodiment is The resin flow rate of a prepreg obtained by impregnating a fiber base material with the resin composition for forming a circuit board, measured under the following condition 3, is preferably 2% or more and 40% or less, more preferably 4% or more and 35% or less, and even more preferably 5% or more and 32% or less. When the resin flow rate of the resin composition for forming a circuit board of this embodiment is in the above range, the resin composition has excellent moldability, and therefore is excellent in suppressing warpage of the semiconductor package.

[0165] (Condition 3) In accordance with IPC-TM-650, four 102 mm square sheets of the prepreg were stacked to obtain a laminate (mass: W1). The laminate was sandwiched between two metal plates and maintained at a temperature of 171°C and a pressure of 1.38 MPa for 10 minutes to obtain a cured product. The resin that flowed out of the cured product was removed, and the cured product was punched out to a diameter of 81.1 mm and its mass was measured (mass: W2). The resin flow rate (%) of the resin composition for forming circuit boards was calculated using the following formula. Formula: [(W1-2xW2) / W1]×100

[0166] In order to achieve such a resin flow rate, it is important to appropriately control the types and amounts of the thermosetting resin (A), stress reducing agent (B), inorganic filler (C), curing accelerator, etc., as well as the prepreg manufacturing method.

[0167] <Resin sheet> Next, the resin sheet (resin film) of this embodiment will be described. The resin sheet of this embodiment can be obtained by forming the resin composition in a varnish form into a film. For example, the resin sheet of this embodiment can be obtained by applying the resin composition in a varnish form to a coating film and then removing the solvent from the coating film. In such a resin sheet, the solvent content can be 5 mass % or less based on the entire resin film. In this embodiment, the solvent removal step can be carried out under conditions of, for example, 100°C to 150°C and 1 minute to 5 minutes. This makes it possible to sufficiently remove the solvent while suppressing the progress of curing of the resin film containing a thermosetting resin. The resin sheet of the present embodiment may be composed of a resin film alone, or may be composed so as to contain a fiber base material inside.

[0168] <Prepreg> The prepreg of this embodiment is obtained by impregnating a fiber substrate with the resin composition. For example, the prepreg can be used as a sheet-like material obtained by impregnating a fiber substrate with the resin composition and then semi-curing the material. A sheet-like material having such a structure has excellent properties such as dielectric properties and mechanical and electrical connection reliability under high temperature and humidity conditions, and is suitable for producing an insulating layer for a printed wiring board, for example.

[0169] In this embodiment, the method for impregnating the resin composition into the fiber substrate is not particularly limited, but examples include a method in which the resin composition is dissolved in a solvent to prepare a resin varnish and the fiber substrate is immersed in the resin varnish, a method in which the resin varnish is applied to the fiber substrate using various coaters, a method in which the resin varnish is sprayed onto the fiber substrate using a sprayer, and a method in which both sides of the fiber substrate are laminated with the resin film made of the resin composition.

[0170] Examples of the fiber substrate include glass fiber substrates such as woven glass cloth and nonwoven glass cloth, inorganic fiber substrates such as woven or nonwoven cloth containing an inorganic compound other than glass as a component, and organic fiber substrates made of organic fibers such as aromatic polyamideimide resin, polyamide resin, aromatic polyester resin, polyester resin, polyimide resin, fluororesin, etc. Among these substrates, the use of a glass fiber substrate typified by woven glass cloth in terms of strength can improve the mechanical strength and heat resistance of the printed wiring board.

[0171] The thickness of the fiber base material is not particularly limited, but is preferably 5 μm to 150 μm, more preferably 10 μm to 100 μm, and even more preferably 12 μm to 90 μm. Use of a fiber base material having such a thickness can further improve the handleability during prepreg production.

[0172] When the thickness of the fiber substrate is equal to or less than the upper limit, the impregnation of the resin composition into the fiber substrate is improved, and the occurrence of strand voids and a decrease in insulation reliability can be suppressed. Furthermore, the formation of through-holes using carbon dioxide, UV, excimer, or other lasers can be facilitated. Furthermore, when the thickness of the fiber substrate is equal to or greater than the lower limit, the strength of the fiber substrate and prepreg can be improved. As a result, handling can be improved, prepreg production can be facilitated, and warping of the resin substrate can be suppressed.

[0173] As the glass fiber substrate, for example, a glass fiber substrate formed of one or more types of glass selected from E glass, S glass, D glass, T glass, NE glass, UT glass, L glass, HP glass, and quartz glass is preferably used.

[0174] In this embodiment, the prepreg can be used to form, for example, an insulating layer in a build-up layer or an insulating layer in a core layer of a printed wiring board. When the prepreg is used to form an insulating layer in a core layer of a printed wiring board, for example, two or more prepregs can be stacked and the resulting laminate can be heat-cured to form an insulating layer for the core layer.

[0175] <Metal-clad laminate> The laminate of this embodiment is a metal-clad laminate in which a metal layer is disposed on at least one surface of the cured product of the prepreg. A method for manufacturing a metal-clad laminate using a prepreg is, for example, as follows.

[0176] Metal foil is placed on both or one of the outer surfaces of a prepreg or a laminate of two or more prepregs, and these are bonded under high vacuum conditions using a laminator or Becquerel apparatus, or metal foil is placed on both or one of the outer surfaces of the prepreg. When two or more prepregs are laminated, metal foil is placed on both or one of the outermost surfaces of the laminated prepregs. The laminate of prepregs and metal foil is then heated and pressurized to obtain a metal-clad laminate. It is preferable to continue pressing during the heating and pressurizing process until cooling is complete.

[0177] Examples of metals constituting the metal foil include copper, copper-based alloys, aluminum, aluminum-based alloys, silver, silver-based alloys, gold, gold-based alloys, zinc, zinc-based alloys, nickel, nickel-based alloys, tin, tin-based alloys, iron, iron-based alloys, Fe-Ni-based alloys such as Kovar (trade name), 42 alloy, Invar, and Super Invar, W, and Mo. Among these, copper or copper alloys are preferred as the metal constituting the metal foil 105 because they have excellent conductivity, are easy to form circuits by etching, and are inexpensive. That is, copper foil is preferred as the metal foil. As the metal foil, a metal foil with a carrier or the like can also be used. The thickness of the metal foil is preferably 0.5 μm or more and 20 μm or less, and more preferably 1.5 μm or more and 18 μm or less.

[0178] <Resin film with carrier> FIG. 1(a) is a cross-sectional view showing an example of the configuration of a resin film 10 with a carrier in this embodiment.

[0179] As shown in Fig. 1(a), the resin film 10 with a carrier of this embodiment can include a carrier substrate 40, a primer layer 30 for a plating process provided on the carrier substrate 40, and an insulating film 20 that serves as a base for the plating layer. In the resin film 10 with a carrier, it is preferable that at least one of the primer layer 30 and the insulating film 20 is made of a resin film made of the above-mentioned resin composition. This can improve the handleability of the resin film.

[0180] 1(b), the resin film 12 with a carrier of this embodiment can include a carrier substrate 40 and a resin film made of the resin composition formed on the carrier substrate 40. The resin film can be used as an insulating film 20 that serves as a base for a plating layer.

[0181] The resin films 10 and 12 with a carrier may be in a roll shape that can be wound up, or in a sheet shape such as a rectangular shape. The surfaces of the resin films 10 and 12 with a carrier may be exposed, or may be covered with a protective film (cover film). As the protective film, a film having a known protective function may be used, and for example, a PET film may be used.

[0182] In this embodiment, the carrier substrate 40 can be, for example, a polymer film or a metal foil. Examples of the polymer film include, but are not limited to, polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polycarbonate; release paper such as silicone sheets; and heat-resistant thermoplastic resin sheets such as fluorine-based resins and polyimide resins. Examples of the metal foil include, but are not limited to, copper and / or copper-based alloys, aluminum and / or aluminum-based alloys, iron and / or iron-based alloys, silver and / or silver-based alloys, gold and gold-based alloys, zinc and zinc-based alloys, nickel and nickel-based alloys, and tin and tin-based alloys. Among these, a polyethylene terephthalate sheet is most preferred due to its low cost and easy peel strength adjustment. This allows for easy peeling from the carrier-attached resin film 10 with an appropriate strength.

[0183] The lower limit of the thickness of the resin film is not particularly limited, but may be, for example, 1 μm or more, 3 μm or more, or 5 μm or more. This allows the mechanical strength of the resin film 10 to be increased. On the other hand, the upper limit of the thickness of the resin film 10 is not particularly limited, but may be, for example, 500 μm or less, 300 μm or less, or 100 μm or less. This allows the semiconductor device to be made thinner. The thickness of the resin film may be the thickness of the insulating film 20, or the combined thickness of the insulating film 20 and the primer layer 30.

[0184] The lower limit of the thickness of the primer layer 30 is, for example, 1 μm or more, and preferably 2 μm or more. This can improve insulation reliability. On the other hand, the upper limit of the thickness of the primer layer 30 is, for example, 10 μm or less, and preferably 8 μm or less. This can achieve a thinner printed wiring board. Furthermore, by setting the thickness of the primer layer 30 within the above range, a printed wiring board that can accommodate thinner thicknesses can be obtained without losing the properties of the insulating layer in the build-up layer.

[0185] The lower limit of the thickness of the insulating film 20 is, for example, 5 μm or more, and preferably 10 μm or more. This can improve insulation reliability. On the other hand, the upper limit of the thickness of the insulating film 20 is, for example, 50 μm or less, and preferably 40 μm or less. This can achieve a thinner printed wiring board. Furthermore, by setting the thickness of the insulating film 20 within the above range, it is possible to fill the irregularities of the inner layer circuit when manufacturing the printed wiring board, and it is also possible to ensure a suitable thickness of the insulating resin layer of the build-up layer.

[0186] The thickness of the carrier substrate 40 is not particularly limited, but may be, for example, 10 μm or more and 100 μm or less, or 10 μm or more and 70 μm or less, which is preferable because it improves the handleability when producing the carrier-attached resin film 10.

[0187] The resin film of the carrier-attached resin film 10 of this embodiment may be a single layer or a multilayer, and may be composed of one or more types of films. When the resin sheet is multilayered, it may be composed of the same type or different types. Furthermore, the carrier-attached resin film 10 may have a protective film on the outermost layer side of the resin film 10.

[0188] The resin sheet of this embodiment is a resin sheet made of the resin composition for forming a circuit board. The cured film of the resin film is composed of a cured product of the resin composition. The cured film of the cured product of the resin composition can be used as an insulating layer that constitutes a build-up layer of a printed wiring board.

[0189] <Printed wiring board> The printed wiring board of this embodiment is provided with an insulating layer made of the cured product of the above-mentioned resin sheet (cured product of the resin composition).

[0190] In this embodiment, the cured resin sheet can be used, for example, as a buildup layer of a normal printed wiring board, a buildup layer in a printed wiring board having no core layer, a buildup layer in a coreless substrate used in PLP, a buildup layer in an MIS substrate, etc. The insulating layer constituting such a buildup layer can also be suitably used as a buildup layer constituting a large-area printed wiring board used to collectively produce multiple semiconductor packages.

[0191] In the present embodiment, a resin sheet made of a resin composition for forming an insulating film may be impregnated with glass fibers. In a semiconductor package using such a resin film as a build-up layer, the linear expansion coefficient of the cured resin film can be reduced, and package warpage can be sufficiently suppressed.

[0192] (Semiconductor package) 2A to 2C are cross-sectional views showing an example of a manufacturing process for the semiconductor package 200 of this embodiment.

[0193] The semiconductor device (semiconductor package 200) of this embodiment can include a printed wiring board and a semiconductor element 240 mounted on a circuit layer of the printed wiring board or embedded in the printed wiring board. An outline of the manufacturing process for the semiconductor package 200 of this embodiment will be described below.

[0194] First, as shown in FIG. 2(a), a core substrate 100 is prepared, which includes an insulating layer 102, via holes 104, and a metal layer 108. The via holes 104 are formed in the insulating layer 102. A metal layer (via) is embedded in the via holes 104. The metal layer may be covered with an electroless metal plating film 106. The metal layer 108 (a circuit layer having a predetermined circuit pattern) formed on the surface of the insulating layer 102 is electrically connected to the vias formed in the via holes 104. In FIG. 2(a), the metal layer 108 is formed on one surface of the core substrate 100, but it may be formed on both surfaces.

[0195] Next, a resin film made of the resin composition for forming a circuit board is formed on one surface of the core substrate 100 so as to embed the metal layer 108. The resin film may be a multi-layer film including an insulating film 20 and a primer layer 30. Alternatively, the resin film may be a single layer of the insulating film 20 alone.

[0196] Subsequently, openings (not shown) are formed in the resin film. The openings can be formed so as to expose the metal layer 108. The method for forming the openings is not particularly limited, and may be, for example, a laser processing method, an exposure and development method, or a blasting method.

[0197] In this embodiment, after forming such openings, the resin film (insulating film 20, primer layer 30) may be thermally cured. This allows the resin film to be composed of a cured product of the resin composition for forming a circuit board of this embodiment.

[0198] If necessary, a desmearing process can be performed to remove smears generated inside the openings and roughen the surface of the resin film.

[0199] The desmearing method is not particularly limited, but can be performed, for example, as follows. First, the core substrate 100 laminated with a resin film is immersed in a swelling liquid containing an organic solvent, and then immersed in an alkaline permanganate aqueous solution to neutralize and roughen the substrate. Examples of organic solvents that can be used include diethylene glycol monobutyl ether and ethylene glycol. Examples of such swelling liquids include "Swelling Dip Securigant P" manufactured by Atotech Japan. Examples of permanganates that can be used include potassium permanganate and sodium permanganate. The temperature of the swelling liquid or the permanganate aqueous solution may be, for example, 50°C or higher and 100°C or lower. The immersion time in the swelling liquid or the permanganate aqueous solution may be, for example, 1 minute or longer and 30 minutes or shorter. In the desmearing step, only the wet desmearing described above can be performed, but plasma irradiation may also be performed in addition to the desmearing.

[0200] Next, an electroless metal plating film 202 is formed on the primer layer 30. An example of an electroless plating method will be described. For example, catalytic nuclei are applied to the surface of the primer layer 30, which is the base layer. The catalytic nuclei are not particularly limited, but may be, for example, precious metal ions or palladium colloid. Subsequently, the electroless metal plating film 202 is formed by electroless plating using the catalytic nuclei as the nuclei. For example, electroless plating containing copper sulfate, formalin, a complexing agent, sodium hydroxide, etc. may be used. After electroless plating, a heat treatment at 100°C or higher and 250°C or lower may be performed to stabilize the plating film.

[0201] Next, as shown in FIG. 2(b), a resist 204 having a predetermined opening pattern (openings 206) is formed on the electroless metal plating film 202. This opening pattern corresponds to, for example, a circuit pattern. The resist 204 is not particularly limited and any known material can be used, including liquid and dry films. In the case of forming fine wiring, a photosensitive dry film or the like can be used as the resist 204. An example using a photosensitive dry film will be described. For example, a photosensitive dry film is laminated on the electroless metal plating film 202, and the non-circuit formation area is exposed to light to harden it, and the unexposed area is dissolved and removed with a developer. The hardened photosensitive dry film is left behind to form the resist 204.

[0202] Next, as shown in FIG. 2( c), an electrolytic metal plating layer 208 is formed by electroplating at least within the opening pattern of the resist 204 and on the electroless metal plating film 202. The electroplating method is not particularly limited, but a known method used for ordinary printed wiring boards can be used, such as a method in which the substrate is immersed in a plating solution such as copper sulfate and an electric current is passed through the plating solution. The electrolytic metal plating layer 208 may have a single layer or a multilayer structure. The material for the electrolytic metal plating layer 208 is not particularly limited, but may be one or more of copper, copper alloy, 42 alloy, nickel, iron, chromium, tungsten, gold, and solder. Subsequently, as shown in FIG. 2(d), the resist 204 is removed using an alkaline remover, sulfuric acid, or a commercially available resist remover.

[0203] Next, as shown in FIG. 2( e), the electroless metal plating film 202 is removed from areas (openings 210) other than the area where the electrolytic metal plating layer 208 is formed. That is, the electroless metal plating film 202 underneath is selectively removed using the electrolytic metal plating layer 208 as a mask. For example, the electroless metal plating film 202 can be removed by soft etching (flash etching). Here, the soft etching process can be performed using an etching solution containing sulfuric acid and hydrogen peroxide. This allows the formation of a metal layer 220 having a predetermined pattern. In this way, the metal layer 220 composed of the electroless metal plating film 202 and the electrolytic metal plating layer 208 can be formed on the insulating layer made of the cured resin film of this embodiment by the semi-additive process (SAP).

[0204] Furthermore, a multilayer structure can be achieved by stacking build-up layers as needed on a printed wiring board composed of the core substrate 100 and the above build-up layers, and repeating the process of forming interlayer connections and circuits using a semi-additive process. In this way, the printed wiring board of this embodiment is obtained.

[0205] 2(f), build-up layers are laminated on the resulting printed wiring board as needed, and the steps of forming interlayer connections and circuits by a semi-additive process are repeated. Then, solder resist layers 230 are laminated on both sides or one side of the printed wiring board as needed.

[0206] The method for forming the solder resist layer 230 is not particularly limited, but may be, for example, a method in which a dry film type solder resist is laminated, exposed to light, and developed, or a method in which a liquid resist is printed and then exposed to light and developed.

[0207] Subsequently, a reflow process is performed to fix the semiconductor element 240 onto the connection terminals, which are part of the wiring pattern, via the solder bumps 250. Thereafter, the semiconductor element 240, the solder bumps 250, etc. are covered with an encapsulant layer 260 to be encapsulated.

[0208] In this embodiment, the thickness of the semiconductor element 240 can be 50 μm or more and 250 μm or less, and the thickness of the encapsulant layer 260 can be 100 μm or more and 350 μm or less. In recent years, the thickness of thinned semiconductor chips has sometimes been increased to increase the mechanical strength of the chips themselves. In such cases, if the circuit board is too rigid, warping of the semiconductor package cannot be suppressed, which can reduce the reliability of the connection between the semiconductor element and the circuit board. The cured product (resin film) obtained from the resin composition for forming a circuit board of this embodiment has a low modulus of elasticity and a low coefficient of linear expansion. Therefore, warping can be suppressed even in a semiconductor package 200 including a semiconductor element 240 and an encapsulant layer 260 of the above-described sizes, thereby improving the reliability of the connection of the semiconductor element 240. As a result of the above, the semiconductor package 200 shown in FIG. 2(f) is obtained.

[0209] <Wiring board> In this embodiment, the wiring board is a substrate (laminate) with metal foil on one or both sides of which a conductor layer is formed by etching the metal foil into a desired pattern on a dielectric substrate, allowing it to be used as a wiring board on which miniaturized, high-density components are mounted.

[0210] Furthermore, the wiring board of this embodiment can include a microstrip line (feed circuit) and a conductor plate (patch) on the dielectric substrate, the microstrip line including a microstrip line formed by etching the metal foil of a base material (laminate) with metal foil. Furthermore, various pads, vias, and patterns are added to the antenna and device circuit using the wiring board of this embodiment.

[0211] The above etching can be performed by chemical etching (wet etching), and the etching solution can be a copper chloride solution, nitric acid, or the like, or can be performed by a method using other acidic solutions, alkaline solutions, or the like.

[0212] The bonding with the metal foil can be carried out by a known method. For example, the adhesive film and the metal foil can be bonded by continuous processing using a hot roll laminating device having one or more pairs of metal rolls or a double belt press (DBP). Because the device configuration is simple and it is advantageous in terms of maintenance costs, the bonding of the adhesive film and the metal foil is preferably carried out by thermal lamination using a hot roll laminating device having one or more pairs of metal rolls.

[0213] The wiring board of this embodiment may be used in a high frequency band of microwaves, for example, 10 GHz to 100 GHz. In particular, by using a frequency of 60 GHz or higher, moisture absorption can be effectively suppressed, resulting in high reliability.

[0214] <Coreless substrate> 3A to 3C are cross-sectional views showing an example of a manufacturing process for the coreless substrate 300 of this embodiment. First, a sacrificial substrate is prepared. While Fig. 3(a) illustrates a configuration in which the first metal foil 303 is provided in contact with both surfaces of the insulating substrate 301, the sacrificial substrate may be any substrate as long as the first metal foil 303 is provided in contact with at least one surface of the insulating substrate 301. More specifically, the first metal foil 303 is provided on the insulating substrate 301 so that at least a portion of it can be peeled off from the sacrificial substrate in a peeling step described below.

[0215] The first metal foil 303 may be a laminate of multiple metal foils, and in this case, a step of directly bonding the insulating substrate and the first metal foil 303 may be included. More specifically, the step of preparing the sacrificial substrate may include a step of preparing a laminate in which a carrier foil and a metal foil are formed in this order on the insulating substrate 301. In this way, the sacrificial substrate and the first metal foil 303 can be easily separated by peeling the metal foil and the carrier foil.

[0216] A resin substrate is an example of insulating substrate 301. A specific example of the material of the resin substrate is a resin substrate using a prepreg impregnated with the resin composition for circuit boards of this embodiment.

[0217] Specific examples of the material of the first metal foil 303 include one or more selected from the group consisting of copper, nickel, and tin.

[0218] After preparing a sacrificial substrate, a first conductor pattern 305 is formed on a first metal foil 303 of the sacrificial substrate. In this embodiment, the formation of each conductor pattern, such as the first conductor pattern 305, is preferably performed by a modified semi-additive (MSAP) method, from the viewpoint of enabling circuit formation with a narrower pitch. For example, after forming a predetermined resist pattern covering the top of the first metal foil 303, a metal film is selectively grown by an electrolytic plating process such as electrolytic copper plating using the first metal foil 303 as a seed layer to obtain the first conductor pattern 305, and the resist is then removed. Specific examples of the material of the first conductive pattern 305 include one or more selected from the group consisting of copper, nickel, and tin, and copper is preferred.

[0219] After the first conductor pattern 305 is formed, as shown in Fig. 3(b), a first insulating layer 307 is formed on the first conductor pattern 305 so as to cover the first conductor pattern 305. The first insulating layer 307 may be formed, for example, on the entire upper surface of the sacrificial substrate. Here, a second metal foil 309 is provided on the surface of the first insulating layer 307, and the first insulating layer 307 is formed so that the second metal foil 309 is disposed on the outside in the laminated structure. From the viewpoint of improving the strength of first insulating layer 307, a prepreg impregnated with the resin composition for a circuit board of this embodiment can be used as first insulating layer 307.

[0220] After forming the second metal foil 309, a metal film is selectively grown using the second metal foil 309 as a seed layer, for example, by MSAP, to form a second conductor pattern 313, which is a circuit, and via wiring 311 connecting the first conductor pattern 305 and the second conductor pattern 313 ( FIG. 3( c) ). Specifically, vias connecting to the first conductor pattern 305 are formed at predetermined positions in the first insulating layer 307, and after desmearing, a metal plating layer is formed by electroless plating or the like to cover the inner walls of the vias and the upper surface of the second metal foil 309. Thereafter, a resist pattern is selectively formed at predetermined positions on the second metal foil 309, and a metal film constituting the via wiring 311 and the second conductor pattern 313 is grown in the areas where the resist is not formed by electrolytic plating, such as electrolytic copper plating. Thereafter, the resist film is peeled off, and the second metal foil 309 is etched away. The second metal foil 309 may be removed simultaneously with or separately from the first metal foil 303.

[0221] After forming the second conductive pattern 313, a lamination step may be further performed before the peeling step described below. For example, an insulating film covering the second conductive pattern 313 may be formed on the first insulating layer 307. Furthermore, as described below, a third conductive pattern connected to the second conductive pattern 313 may be formed.

[0222] After the second conductive pattern 313 is formed, the insulating substrate 301 is removed. As shown in Fig. 3(d), the insulating substrate 301 is removed from the laminate by peeling the first metal foil 303 from the sacrificial substrate. For example, when the first metal foil 303 is a laminate of a carrier foil and a metal foil, the carrier foil on the insulating substrate 301 is peeled from the metal foil.

[0223] 3(e), the first metal foil 303 remaining under the first insulating layer 307 is removed. From the viewpoint of reducing metal residue, the step of removing the first metal foil 303 preferably includes a step of etching the first metal foil 303, and more preferably a step of flash etching the first metal foil 303. The flash etching can be, for example, etching using an etching solution containing sulfuric acid and hydrogen peroxide. When etching the first metal foil 303, the second metal foil 309 remaining on the first insulating layer 307 may also be etched away. Through the above steps, the coreless substrate 300 is obtained.

[0224] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above can be adopted as long as they do not impair the effects of the present invention. [Example]

[0225] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0226] [Raw materials] Details of the raw materials for each component in Table 1 are as follows: Inorganic filler: Silica particles "SC4050" (average particle size 1.0 μm, phenylaminosilane treated) manufactured by Admatechs Co., Ltd.

[0227] Coupling agent 1: Epoxy silane coupling agent (γ-glycidoxypropyltrimethoxysilane) "A-187" manufactured by Momentive Coupling agent 2: N-phenyl-3-aminopropyltrimethoxysilane, "KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd.

[0228] Stress reducing agent 1: Phenyl-modified silicone resin powder "KMP-708" (average particle size 2 μm, temperature at which thermal weight loss is 5% by mass as measured by the following method: 470°C) manufactured by Shin-Etsu Chemical Co., Ltd. (Method for measuring thermal weight loss rate) Using a temperature-controllable drying device, approximately 10 mg of the composition obtained in the example was heated from 100°C at a heating rate of 10°C / min, and the weight loss rate of the sample was measured in the temperature range up to 600°C, thereby performing thermogravimetric analysis. The temperature at which the thermal weight loss rate reached 5% by mass was then measured. Stress reducing agent 2: Methyl group-containing silicone resin powder "Tospearl" (average particle size 1.7 μm, temperature at which thermal weight loss measured by the above method reaches 5% by mass: 320°C) manufactured by Momentive Stress reducing agent 3: Silicone composite powder "X-52-5153A" (average particle size 2.0 μm, epoxy group-containing surface, temperature at which the thermal weight loss rate measured by the above method reaches 5% by mass: 335°C) manufactured by Shin-Etsu Chemical Co., Ltd.

[0229] Stress reducing agent 4: Epoxidized polybutadiene "PB4700" (epoxy equivalent 165g / eq, viscosity (45℃) 6,300mPa / s, average molecular weight Mn 2000-3500) manufactured by Daicel Corporation Stress reducing agent 5: Urethane acrylate containing an alicyclic structure derived from alicyclic isocyanate, "Art Resin UN-6304" (Mw 13,000), manufactured by Negami Chemical Industries, Ltd.

[0230] Stress reducing agent 6: Carboxyl-terminated acrylonitrile-butadiene rubber (CTBN1008SP, manufactured by Ube Industries, Ltd.)

[0231] Epoxy resin 1: Bisphenol F type epoxy resin "Epicron 830S" manufactured by DIC Corporation Epoxy resin 2: Biphenyl aralkyl epoxy resin "NC-3000H" manufactured by Nippon Kayaku Co., Ltd. Epoxy resin 3: Naphthalene-type epoxy resin "Epiclon HP-4710" manufactured by DIC Corporation

[0232] Benzoxazine resin: Pd-type benzoxazine "Pd400C" (manufactured by Shikoku Chemical Industry Co., Ltd.) represented by the above formula (4a) Cyanate resin: Phenol novolac cyanate resin "PT-30S" manufactured by Lonza

[0233] Active ester hardener Active ester curing agent prepared by the following method (Method for preparing active ester curing agent) A flask equipped with a thermometer, dropping funnel, condenser, fractionating column, and stirrer was charged with 203.0 g of 1,3-benzenedicarboxylic acid dichloride (molar number of acid chloride groups: 2.0 mol) and 1,338 g of toluene. The system was then vacuum-purged with nitrogen to dissolve the reactants. Next, 96.5 g (0.67 mol) of α-naphthol and 219.5 g of dicyclopentadiene phenol resin (molar number of phenolic hydroxyl groups: 1.33 mol) were charged, and the system was vacuum-purged with nitrogen to dissolve the reactants. Subsequently, while purging with nitrogen gas, the system was maintained at 60°C or below, and 400 g of 20% aqueous sodium hydroxide solution was added dropwise over 3 hours. Stirring was continued under these conditions for 1.0 hour. After the reaction was completed, the mixture was allowed to stand, allowing the liquid to separate, and the aqueous layer was removed. Water was then added to the toluene phase containing the dissolved reactants, and the mixture was stirred and mixed for approximately 15 minutes. The mixture was then allowed to stand, allowing the liquid to separate, and the aqueous layer was removed. This procedure was repeated until the pH of the aqueous layer reached 7. The water was then removed by decanting, yielding an activated ester resin in the form of a toluene solution with a nonvolatile content of 65%. The structure of the resulting activated ester resin was confirmed to be R 1 and R 3The active ester resin had a structure in which π was a hydrogen atom, Z was a naphthyl group, and l was 0. The average value k of the repeating units of the active ester resin was calculated from the reaction equivalent ratio and was in the range of 0.5 to 1.0. The obtained active ester resin specifically had a structure represented by the following chemical formula (6). In the following formula, the average value k of the repeating units was 0.5 to 1.0. [ka]

[0234] Curing accelerator 1: TBZ (2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole) manufactured by Shikoku Chemicals Corporation Curing accelerator 2: 2PZ-PW (2-phenylimidazole) manufactured by Shikoku Chemicals Corporation

[0235] Example 1 1. Preparation of a varnish-like resin composition for forming circuit boards Each component was dissolved or dispersed at the solid content shown in Table 1, adjusted with methyl ethyl ketone to a non-volatile content of 70% by mass, and stirred using a high-speed stirrer to prepare a varnish-like resin composition for forming circuit boards (resin varnish). The numerical values ​​showing the blending ratio of each component in Table 1 indicate the blending ratio (mass %) of each component relative to the total solid content of the resin composition.

[0236] 2. Prepreg manufacturing S-glass woven fabric (basis weight 13 g / m) listed in Table 2 2 ) and S-glass woven fabric (basis weight 11 g / m 2 ) was impregnated with a resin varnish using an applicator and dried for 10 minutes in a hot air dryer at 170°C to obtain a prepreg having the thickness shown in Table 2.

[0237] 3. Manufacturing of resin substrates Ultra-thin copper foil (Mitsui Mining & Smelting Co., Ltd., Microthin Ex, 2.0 μm) was laminated on both sides of the prepreg, and the prepreg was heated and press-molded at a pressure of 4 MPa and a temperature of 200°C for 2 hours to obtain a resin substrate. The thickness of the core layer (the portion consisting of the resin substrate) of the obtained resin substrate with metal foil was 0.06 mm.

[0238] (Examples 2 to 4 and Comparative Example 1) A resin varnish was prepared in the same manner as in Example 1, except that the compositions of the various components were changed to those shown in Table 1. Furthermore, an S-glass woven fabric (basis weight 13 g / m) shown in Table 2 was used. 2 ) and S-glass woven fabric (basis weight 11 g / m 2 ) was impregnated with the obtained resin varnish using an applicator and dried for 10 minutes in a hot air dryer at 170°C to obtain a prepreg having the thickness shown in Table 2. Furthermore, a resin substrate was produced in the same manner as in Example 1.

[0239] The prepregs and resin substrates obtained in the examples and comparative examples were evaluated as follows. The evaluation results are shown in Table 2.

[0240] (1) Resin flow rate In accordance with IPC-TM-650, four 102 mm square sheets of the prepreg were stacked to obtain a laminate (mass: W1). The laminate was sandwiched between two metal plates and maintained at a temperature of 171°C and a pressure of 1.38 MPa for 10 minutes to obtain a cured product. The resin that flowed out of the cured product was removed, and the cured product was punched out to a diameter of 81.1 mm and its mass was measured (mass: W2). The resin flow rate (%) of the resin composition for forming a circuit board was calculated using the following formula. Formula: [(W1-2xW2) / W1]×100

[0241] (2) Average domain size of the domain phase The cross section of the obtained resin substrate with metal foil was polished and photographed using a scanning electron microscope. From the observed image, 10 domain phases were randomly selected and binarized using image processing analysis software (Adobe Photoshop), and their areas were calculated. The domain sizes were then measured by approximating them to circles. The average value was taken as the average domain size.

[0242] (3) Storage modulus E' The storage modulus E' was measured by dynamic viscoelasticity measurement (DMA device, Q800 manufactured by TA Instruments). The copper foil of the obtained resin substrate with metal foil was removed by etching, and a test piece of 8 mm x 40 mm was cut out from the resin substrate to obtain a cured prepreg. Next, using the cured prepreg obtained, measurements were performed at a temperature range of -50 to 350 °C, a heating rate of 5 °C / min, and a frequency of 1 Hz to measure the storage modulus E' at 30 °C. 30 , storage modulus E' at 250°C 250 obtained.

[0243] (4) Glass transition temperature (Tg) The glass transition temperature (Tg) was measured in accordance with JIS C-6481 (DMA method) by dynamic viscoelasticity measurement (DMA device, Q800 manufactured by TA Instruments). Using the cured prepreg used for storage modulus E', dynamic viscoelasticity measurements were performed at a temperature range of -50 to 350°C, a heating rate of 5°C / min, and a frequency of 1 Hz. The glass transition temperature was defined as the temperature (°C) at which the loss tangent tanδ reached its maximum value.

[0244] (5) Linear thermal expansion coefficient The copper foil was removed from the resulting metal-foil-attached resin substrate by etching, and a 6 mm x 5 mm test piece was cut from the resulting resin substrate to obtain a cured prepreg. Next, the resulting cured prepreg was subjected to two cycles of thermomechanical analysis (TMA) using a TMA (TA Instruments, Q400) under the following conditions: a temperature range of 30 to 260°C, a heating rate of 10°C / min, a load of 10 g, and compression mode. The average linear expansion coefficient α1 in the in-plane direction (longitudinal (X) direction) over the temperature range of 50°C to 150°C and the average linear expansion coefficient α2 in the in-plane direction (longitudinal (X) direction) over the temperature range of 150°C to 250°C were obtained. (6) Peel strength The peel strength was measured in accordance with JISC-6481. The sample used was a resin substrate with metal foil electroplated with 20 μm of copper.

[0245] (6) Warping (Coreless substrate manufacturing) A sheet of prepreg (LAZ-6785GT-R, manufactured by Sumitomo Bakelite Co., Ltd.) was prepared, and the carrier foil side of peelable copper foil (manufacturer: Mitsui Mining & Smelting Co., Ltd., model number MT18Ex, thickness 5 μm) was bonded to both sides of it to obtain a sacrificial substrate with metal foil. The bonding conditions were a pressure of 2 MPa, a temperature of 220°C, and 2 hours. The thickness of the resulting sacrificial substrate with metal foil was 151 μm. The buildup prepreg and metal foil (manufacturer: Mitsui Mining & Smelting Co., Ltd., model number MT18Ex, thickness 5 μm) obtained in the Examples and Comparative Examples were laminated on both sides of the metal foil-attached sacrificial substrate obtained as described above, and the resulting mixture was heated and pressurized at a pressure of 2 MPa and a temperature of 220°C for 2 hours to form a first buildup layer on both sides of the metal foil-attached sacrificial substrate. This process was then repeated twice to form second and third buildup layers. The build-up layer was peeled off from the obtained sacrificial substrate by peeling off the peelable copper foil, and a coreless substrate 1 was obtained. The metal foil on the sacrificial substrate side of the obtained coreless substrate was removed by flash etching. After etching, the solder resist was formed and the obtained coreless substrate had the following thickness. When the prepreg thickness is 35 μm: the coreless substrate thickness is 165 μm When the prepreg thickness is 30 μm: the coreless substrate thickness is 150 μm When the prepreg thickness is 25 μm: the coreless substrate thickness is 135 μm When the prepreg thickness is 23 μm: the coreless substrate thickness is 120 μm When the prepreg thickness is 18 μm: the coreless substrate thickness is 95 μm (Semiconductor device manufacturing) The semiconductor device was obtained by mounting a semiconductor element (TEG chip, size 10 mm x 10 mm, thickness 0.17 mm) with solder bumps on the obtained coreless substrate by thermocompression bonding using a flip-chip bonder. Next, the solder bumps were melt-bonded in an IR reflow furnace, and then filling with liquid encapsulating resin (Sumitomo Bakelite Co., Ltd., CRP-4152S) and curing the liquid encapsulating resin. The liquid encapsulating resin was cured at a temperature of 150°C for 120 minutes. The solder bumps of the semiconductor element were formed from a eutectic with a Sn / Pb composition. Finally, the substrate was singulated into pieces measuring 14 mm x 14 mm using a router to obtain the semiconductor device. (Measurement of package warpage) The obtained semiconductor device (14 mm x 14 mm) was placed with the semiconductor element surface facing down in the sample chamber of a temperature-variable laser coordinate measuring machine (manufactured by Hitachi Technology and Services, Model LS220-MT100MT50), and the warpage of the semiconductor device was measured at room temperature (25°C) and 260°C using the measuring machine. The warpage was measured by measuring displacement in the height direction, and the largest difference in displacement was taken as the amount of warpage. The measurement range was 13 mm x 13 mm. The warpage evaluations (each symbol) listed in Table 2 are as shown in Table 3. Note that since the measurement of PKG warpage depends on the thickness of the coreless substrate, the evaluation was made as shown in Table 3 for each coreless substrate thickness.

[0246] [Table 1]

[0247] [Table 2]

[0248] [Table 3]

[0249] [Table 4]

[0250] The resin composition for forming a circuit board in the example contains a specified (A) thermosetting resin, a specified (B) stress-reducing agent, and a (C) inorganic filler, and in the cured product obtained by curing the composition, a domain phase of the stress-reducing agent (B) is formed in a continuous phase made of the thermosetting resin (A), thereby exhibiting a low modulus of elasticity and a low coefficient of linear expansion, and suppressing warpage of the semiconductor package. This demonstrates that by using the resin composition for forming a circuit board of this embodiment in a circuit board, warpage of the semiconductor package can be suppressed and the connection reliability between the semiconductor element and the circuit board can be improved. [Explanation of symbols]

[0251] 10 Resin film with carrier 12 Resin film with carrier 20 insulating film 30 primer layer 40 Carrier substrate 100 Core Layer 102 Insulating layer 104 Beer Hall 106 Electroless metal plating film 108 Metal layer 200 Semiconductor Packages 202 Electroless metal plating film 204 Resist 206 Opening 208 Electrolytic metal plating layer 210 Opening 220 metal layer 230 Solder resist layer 240 Semiconductor elements 250 solder bumps 260 Encapsulant layer 300 Coreless Substrate 301 Insulating substrate 303 First Metal Foil 305 First Conductor Pattern 307 First insulating layer 309 Second Metal Foil 310 Coreless substrate 311 Via wiring 313 Second Conductor Pattern

Claims

1. (A) a thermosetting resin; (B) a stress reducing agent; (C) an inorganic filler; A resin composition for circuit boards, comprising: the thermosetting resin (A) is one or more resins selected from the group consisting of epoxy resins and benzoxazine resins; The stress reducing agent (B) (B1) urethane acrylate, (B2) epoxidized polybutadiene, and (B3) Silicone particles Contains one or more selected from the group consisting of A resin composition for circuit boards, wherein in a cured product obtained by curing the resin composition for circuit boards, a domain phase of the stress reducing agent (B) is formed in a continuous phase of the thermosetting resin (A).

2. The resin composition for circuit boards according to claim 1 , wherein the thermosetting resin (A) comprises a benzoxazine resin.

3. 2. The resin composition for circuit boards according to claim 1, wherein the stress reducing agent (B) comprises a urethane acrylate (B1), an epoxidized polybutadiene (B2), and silicone particles (B3).

4. The thermosetting resin (A) contains an epoxy resin, The resin composition for circuit boards according to claim 1 , further comprising an active ester curing agent (D).

5. The resin composition for forming a circuit board according to claim 4 , wherein the active ester curing agent (D) has a structure represented by the following general formula (1): 【Chemical 1】 In general formula (1), A represents a substituted or unsubstituted arylene group linked via an aliphatic cyclic hydrocarbon group, and Ar′ represents a substituted or unsubstituted aryl group. B is a structure represented by the following general formula (B): 【Chemistry 2】 (In general formula (B), Ar is a substituted or unsubstituted arylene group; Y is a single bond, a substituted or unsubstituted linear alkylene group having 1 to 6 carbon atoms, or a substituted or unsubstituted cyclic alkylene group having 3 to 6 carbon atoms, a substituted or unsubstituted divalent aromatic hydrocarbon group, an ether bond, a carbonyl group, a carbonyloxy group, a sulfide group, or a sulfone group; and n is an integer of 0 to 4.) k is the average value of the repeating units and is in the range of 0.25 to 3.

5.

6. 2. The resin composition for circuit boards according to claim 1, wherein the domain phase of the stress-reducing agent (B) has an average domain size of 8 μm or less.

7. The resin composition for circuit boards according to claim 1 , wherein the stress reducing agent (B) comprises a urethane acrylate (B1).

8. 2. The resin composition for circuit boards according to claim 1, wherein the epoxy equivalent of the epoxidized polybutadiene (B2) is 100 g / eq or more and 220 g / eq or less.

9. 2. The resin composition for circuit boards according to claim 1, wherein the viscosity of the epoxidized polybutadiene (B2) at 45°C is 2,000 MPa·s or more and 30,000 mPa / s or less.

10. 2. The resin composition for circuit boards according to claim 1, wherein the silicone particles (B3) are a silicone composite powder or a silicone resin powder.

11. The resin composition for forming a circuit board according to claim 1, The storage modulus E' at 30°C of the cured product obtained by heat-treating a prepreg obtained by impregnating a fiber substrate with the resin composition for forming a circuit board at 200°C for 2 hours is ３０ The resin composition for forming a circuit board has a modulus of 20.0 GPa or less.

12. The resin composition for forming a circuit board according to claim 1, The storage modulus E' at 250°C of the cured product obtained by heat-treating a prepreg obtained by impregnating a fiber substrate with the resin composition for forming a circuit board at 200°C for 2 hours is ２５０ The resin composition for forming a circuit board has a modulus of 13.0 GPa or less.

13. The resin composition for forming a circuit board according to claim 1, A resin composition for forming a circuit board, wherein a prepreg obtained by impregnating a fiber substrate with the resin composition for forming a circuit board is heat-treated at 200°C for 2 hours to obtain a cured product, the cured product having a linear expansion coefficient α1 measured under the following condition 1 of 3 ppm / °C or more and 15 ppm / °C or less. (Condition 1) Using a thermomechanical analyzer, thermomechanical analysis is performed for two cycles under the conditions of a temperature range of 30 to 260°C, a heating rate of 10°C / min, a load of 10 g, and compression mode. The average value of the linear expansion coefficient in the planar direction (longitudinal (X) direction) in the range of 50 to 150°C is defined as the linear expansion coefficient α1.

14. The resin composition for forming a circuit board according to claim 1, A resin composition for forming a circuit board, wherein a prepreg obtained by impregnating a fiber substrate with the resin composition for forming a circuit board is heat-treated at 200°C for 2 hours to obtain a cured product, the cured product having a linear expansion coefficient α2 of 5 ppm / °C or more and 18 ppm / °C or less, as measured under the following condition 2: (Condition 2) Using a thermomechanical analyzer, thermomechanical analysis is performed for two cycles under the conditions of a temperature range of 30 to 260°C, a heating rate of 10°C / min, a load of 10 g, and compression mode. The average value of the linear expansion coefficient in the planar direction (longitudinal (X) direction) in the range of 30 to 260°C is defined as the linear expansion coefficient α2.

15. The resin composition for forming a circuit board according to claim 1, A resin composition for forming a circuit board, wherein a prepreg obtained by impregnating a fiber substrate with the resin composition for forming a circuit board has a resin flow rate measured under the following condition 3 of 2% or more and 40% or less. (Condition 3) According to IPC-TM-650, four 102 mm square sheets of the prepreg were stacked to obtain a laminate (mass: W1). The laminate was sandwiched between two metal plates and held at a temperature of 171°C and a pressure of 1.38 MPa for 10 minutes to obtain a cured product. The resin that flowed out of the cured product was removed, and the cured product was punched out to a diameter of 81.1 mm and its mass was measured (mass: W2). The resin flow rate (%) of the resin composition for forming a circuit board is calculated using the following formula. Formula: [(W1-2xW2) / W1]×100

16. A resin sheet comprising the resin composition for forming a circuit board according to any one of claims 1 to 15.

17. A carrier substrate; A resin film with a carrier, comprising: a resin sheet formed on the carrier base and comprising the resin composition for forming a circuit board according to any one of claims 1 to 15.

18. A prepreg obtained by impregnating a fiber substrate with the resin composition for forming a circuit board according to any one of claims 1 to 15.

19. A laminate comprising the prepreg according to claim 18 and a metal layer disposed on at least one surface of the prepreg.

20. A printed wiring board comprising an insulating layer formed from a cured product of the resin composition for forming a circuit board according to any one of claims 1 to 15.

21. The printed wiring board according to claim 20; a semiconductor element mounted on a circuit layer of the printed wiring board or embedded in the printed wiring board.

22. A coreless substrate comprising a build-up layer including an insulating layer formed of a cured product of the resin composition for forming a circuit board according to any one of claims 1 to 15, and a circuit layer.

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