Resin composition, prepreg, resin film, laminate, multilayer printed wiring board, and semiconductor package

Abstract

To provide a resin composition excellent in fire retardancy, a prepreg, a laminate sheet, a resin film, a multilayer printed board and a semiconductor package, each using the resin composition.SOLUTION: A resin composition contains (A) a resin, (B) a phosphorus fire retardant containing a spiro ring, and (C) a char-forming agent containing a condensed ring. A prepreg, a laminate sheet, a resin film, a multilayer printed board and a semiconductor package use the resin composition.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present embodiment relates to a resin composition, a prepreg, a resin film, a laminate, a multilayer printed wiring board, and a semiconductor package.

Background Art

[0002] Conventionally, halogen-based flame retardants containing halogens such as bromine have been used as flame retardants for resin compositions used in electronic components such as printed wiring boards and semiconductor encapsulants. However, in recent years, from the perspective of environmental considerations, the introduction of halogen-free products that do not use conventional bromine-based flame retardants containing halogens has been promoted.

[0003] Here, halogen-free means that it does not contain any halogen atoms or the content is extremely small. For example, the Japan Electronic Circuit Industry Association defines a copper-clad laminate for halogen-free printed wiring boards as having a chlorine (Cl) and bromine (Br) content of 900 ppm or less each, and a total content of 1500 ppm or less.

[0004] Therefore, as a flame retardant to replace halogen-containing compounds, for example, flame retardants that do not contain halogens such as metal hydroxides, metal oxides, condensed phosphate ester compounds, and intumescent flame retardants have been studied. Among these, intumescent flame retardants have attracted attention as materials expected to have higher flame retardancy than metal hydroxides, condensed phosphate ester compounds, etc.

[0005] As the intumescent flame retardant, ammonium polyphosphate containing a phosphorus atom and a nitrogen atom is often used. The intumescent flame retardant forms a carbonized film, which is a foamed expansion layer (intumescent layer), on the surface during combustion, and the foamed expansion layer exerts an action to stop combustion by exhibiting a heat insulation effect and a gas barrier effect.

[0006] Patent Document 1 discloses a composition that can impart processability and flame retardancy to a resin by mixing it with the resin, and a flame retardant resin composition containing the composition and the resin, which has excellent processability and flame retardancy. The composition contains: Component (A): at least one melamine salt selected from the group consisting of melamine orthophosphate, melamine pyrophosphate, and melamine polyphosphate; Component (B): at least one piperazine salt selected from the group consisting of piperazine orthophosphate, piperazine pyrophosphate, and piperazine polyphosphate; and Component (C): a monohydrate of alumina.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] By the way, in recent years, with the remarkable improvement in information communication volume, communication speed, etc. in network infrastructure equipment, large computers, etc., semiconductor packages mounted on these electronic devices need to support higher frequencies. Therefore, for various materials used in semiconductor packages, materials having a low dielectric constant and a low dielectric tangent that enable reduction of transmission loss are required. However, melamine polyphosphate salts, piperazine polyphosphate salts, etc. used in the technology of Patent Document 1 tend to deteriorate the dielectric properties of the resin composition. Therefore, it has been difficult to achieve both an excellent flame retardant and dielectric properties compatible with higher frequencies while using these flame retardants.

[0009] In addition, phosphorus-based flame retardants other than intumescent flame retardants are generally materials with inferior dielectric properties among the materials constituting substrates for printed wiring boards, semiconductor encapsulants, etc. Therefore, when the addition amount of these flame retardants is increased to improve flame retardancy, the dielectric properties of the semiconductor package may be impaired. That is, in order to improve the dielectric properties of the resin composition to cope with high frequencies, it is necessary to obtain sufficient flame retardancy with the minimum possible amount of flame retardant added, but such technology has not yet been established.

[0010] In view of such a situation, an object of the present embodiment is to provide a resin composition excellent in flame retardancy, a prepreg, a laminate, a resin film, a multilayer printed wiring board, and a semiconductor package using the resin composition.

Means for Solving the Problems

[0011] As a result of proceeding with studies to solve the above problems, the present inventors have found that the above problems can be solved by using a combination of a flame retardant having a specific structure and a char former having a specific structure. That is, the present embodiment relates to the following [1] to

[15] .

[0012] [1] (A) A resin, (B) A phosphorus-based flame retardant containing a spiro ring, (C) A char former containing a condensed ring, and a resin composition containing the same. [2] The resin composition according to [1] above, wherein the phosphorus-based flame retardant (B) containing a spiro ring contains a phosphonate diester structure. [3] The resin composition according to [2] above, wherein the phosphorus-based flame retardant (B) containing a spiro ring contains two phosphorus atoms, and each of the two rings constituting the spiro ring contains one phosphorus atom as a ring-forming atom, and the phosphorus atoms each form the phosphonate diester structure. [4] The resin composition according to [3] above, wherein the phosphorus-based flame retardant (B) containing a spiro ring is represented by the following general formula (B-1).

Chemical formula

[10] The resin composition according to [9] above, which is for a multilayer printed wiring board or a semiconductor encapsulant.

[11] A prepreg containing the resin composition according to [9] above.

[12] A resin film containing the resin composition according to [9] above.

[13] A laminate containing a cured product of the resin composition according to [9] above.

[14] A multilayer printed wiring board containing a cured product of the resin composition according to [9] above.

[15] A semiconductor package containing a cured product of the resin composition according to [9] above. [Effect of the Invention]

[0013] According to the present embodiment, it is possible to provide a resin composition excellent in flame retardancy, a prepreg, a laminate, a resin film, a multilayer printed wiring board, and a semiconductor package using the resin composition. [Brief Description of the Drawings]

[0014]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0015] In this specification, the numerical range indicated by "~" indicates a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively. For example, the notation of the numerical range "X~Y" (X and Y are real numbers) means a numerical range that is X or more and Y or less. And the description "X or more" in this specification means X and numerical values exceeding X, and the same applies when the numerical values are different. Also, the description "Y or less" in this specification means Y and numerical values less than Y. The lower limit value and the upper limit value of the numerical range described in this specification can be arbitrarily combined with the lower limit value or the upper limit value of other numerical ranges, respectively. In the numerical range described in this specification, the lower limit value or the upper limit value of the numerical range may be replaced with the value shown in the examples.

[0016] Each component and material exemplified in this specification may be used alone or in combination of two or more, unless otherwise specified. In this specification, the content of each component in the resin composition means the total amount of the plurality of substances present in the resin composition when there are a plurality of substances corresponding to each component in the resin composition, unless otherwise specified. In this specification, the "resin composition" includes a mixture of each component described later and a semi-cured product of the mixture.

[0017] In this specification, the "solid content" refers to the non-volatile component excluding volatile substances such as solvents, and indicates the components that remain without volatilizing when the resin composition is dried, including those in a liquid state, a syrup state, and a wax state at room temperature. Here, room temperature in this specification means 25°C.

[0018] The mechanism of action described in this specification is speculative and does not limit the mechanism by which the resin composition according to this embodiment exhibits its effects. Aspects in which the matters described in this specification are arbitrarily combined are also included in this embodiment.

[0019] [Resin composition] The resin composition of this embodiment is a resin composition containing (A) a resin, (B) a phosphorus-based flame retardant containing a spiro ring, and (C) a char former containing a condensed ring.

[0020] The reason why the resin composition of this embodiment has excellent flame retardancy is not clear, but it is speculated as follows. The (C) char former containing a condensed ring contained in the resin composition of this embodiment contains a condensed ring that is difficult to thermally decompose. Therefore, even during combustion, it is difficult to be reduced to low molecular weight and has a property of easily forming a char. Therefore, the resin composition of this embodiment containing the (C) char former containing a condensed ring forms a sufficient amount of char derived from the (C) char former efficiently during combustion. On the other hand, the (B) phosphorus-based flame retardant containing a spiro ring contained in the resin composition of this embodiment also has high thermal stability and tends to be difficult to completely decompose even during combustion. Therefore, at the temperature at which the (C) char former containing a condensed ring changes to a char, the (B) phosphorus-based flame retardant containing a spiro ring continues to exist in the system without thermal decomposition and is considered to function as a crosslinking agent between the chars. And a char having sufficient crosslinking is considered to contribute to the formation of a dense skin layer with few voids and the formation of an intumescent layer expanded by foaming immediately below the surface layer. Due to the heat insulation effect and the shielding effect of combustion gases of this intumescent layer, the resin composition of this embodiment is considered to have excellent flame retardancy. Hereinafter, each component that the resin composition of this embodiment may contain will be described in order.

[0021] <(A) Resin> The (A) resin is not particularly limited and may be appropriately selected according to the use of the resin composition. (A) The resin may be a thermosetting resin or a thermoplastic resin. Examples of the thermosetting resin include epoxy resin, phenol resin, unsaturated imide resin, cyanate resin, isocyanate resin, benzoxazine resin, oxetane resin, amino resin, unsaturated polyester resin, allyl resin, dicyclopentadiene resin, silicone resin, triazine resin, melamine resin, etc. Examples of the thermoplastic resin include polyethylene resin, polypropylene resin, polystyrene resin, polyphenylene ether resin, phenoxy resin, polycarbonate resin, polyester resin, polyamide resin, polyamideimide resin, polyimide resin, xylene resin, polyphenylene sulfide resin, polyetherimide resin, polyetheretherketone resin, polyetherimide resin, silicone resin, tetrafluoroethylene resin, etc. Among these, from the viewpoint of making the resin composition of the present embodiment suitable for electronic component applications where high heat resistance and the like are required, the (A) resin is preferably a thermosetting resin, more preferably an epoxy resin, a phenol resin, or an unsaturated imide resin. (A) The resin may be used alone or in combination of two or more.

[0022] The content of the (A) resin in the resin composition of the present embodiment is not particularly limited, but in the solid content of the resin composition excluding the inorganic filler, it is preferably 50 to 99% by mass, more preferably 70 to 95% by mass, and still more preferably 80 to 90% by mass. When the content of the (A) resin is equal to or higher than the above lower limit value, it tends to be easy to sufficiently obtain the characteristics derived from the (A) resin. Also, when the content of the (A) resin is equal to or lower than the above upper limit value, it tends to be easy to obtain excellent flame retardancy based on the (B) phosphorus-based flame retardant containing a spiro ring and the (C) char former containing a condensed ring.

[0023] <(B) Phosphorus-based flame retardant containing a spiro ring> The resin composition of the present embodiment contains a (B) phosphorus-based flame retardant containing a spiro ring. In the present specification, the "spiro ring" refers to a chemical structure in which one atom is shared by two rings. The atom shared by the two rings is preferably a carbon atom, but may also be an atom other than a carbon atom. (B) The phosphorus-based flame retardant containing a spiro ring may be used alone or in combination of two or more.

[0024] (B) The phosphorus-based flame retardant containing a spiro ring preferably contains a phosphonate diester structure from the viewpoint of flame retardancy. (B) As the phosphonate diester structure of the phosphorus-based flame retardant containing a spiro ring, a structure represented by the following general formula (B-2) is preferable.

[0025] [Chemical formula] (In the formula, R B1 is an alkyl group, an aromatic hydrocarbon group or an aromatic heterocyclic group. * is a site bonded to an organic group constituting the phosphate ester.)

[0026] The number of carbon atoms of the alkyl group represented by R B1 in the above general formula (B-2) is preferably 1 to 10, more preferably 1 to 5, and still more preferably 1 to 3. Note that the number of carbon atoms of the substituent is not included in the number of carbon atoms of the alkyl group. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group and the like. These alkyl groups may be either linear or branched. The alkyl group may or may not have a substituent. Examples of the substituent that the alkyl group may have include, for example, an aromatic hydrocarbon group described below; an aromatic heterocyclic group described below; a halogen atom; an alkoxy group, an aryloxy group, a hydroxy group, a carboxy group, an amino group, a glycidyl ether group; a group formed by combining these, and the like. The number of carbon atoms of the substituent of the alkyl group is preferably 1 to 20, more preferably 1 to 12, and still more preferably 1 to 10.

[0027] R in the general formula (B-2) above B1 The number of carbon atoms of the aromatic hydrocarbon group represented by is preferably 6 to 20, more preferably 6 to 15, and still more preferably 6 to 12. Note that the number of carbon atoms of the aromatic hydrocarbon group does not include the number of carbon atoms of the substituent. Examples of the aromatic hydrocarbon group include a phenyl group, a naphthyl group, and the like. The aromatic hydrocarbon group may or may not have a substituent. Examples of the substituent that the aromatic hydrocarbon group may have include, for example, the alkyl group described above; an aromatic heterocyclic group described below; a halogen atom; an alkoxy group, an aryloxy group, a hydroxy group, a carboxy group, an amino group, a glycidyl ether group; a group formed by combining these, and the like. The number of carbon atoms of the substituent of the aromatic hydrocarbon group is preferably 1 to 20, more preferably 1 to 12, and still more preferably 1 to 10.

[0028] R in the general formula (B-2) above B1 The number of carbon atoms of the aromatic heterocyclic group represented by is preferably 6 to 20, more preferably 6 to 15, and still more preferably 6 to 12. Note that the number of carbon atoms of the aromatic heterocyclic group does not include the number of carbon atoms of the substituent. Examples of the aromatic heterocyclic group include residues of aromatic heterocycles such as pyridine, pyridazine, pyrimidine, pyrazine, 1,3,5-triazine, carbazole, dibenzofuran, dibenzothiophene, phenoxazine, phenothiazine, dihydroacridine, and the like. The aromatic heterocyclic group may or may not have a substituent. Examples of the substituent that the aromatic heterocyclic group may have include, for example, the above-described alkyl group; the above-described aromatic hydrocarbon group; a halogen atom; an alkoxy group, an aryloxy group, a hydroxy group, a carboxy group, an amino group, a glycidyl ether group; a group formed by combining these, and the like. The number of carbon atoms of the substituent of the aromatic heterocyclic group is preferably 1 to 20, more preferably 1 to 12, still more preferably 1 to 10.

[0029] R described above B1 Among the above-described options of R, from the viewpoint of flame retardancy, R B1 is preferably an alkyl group, more preferably an alkyl group substituted with an aromatic hydrocarbon group, still more preferably an alkyl group substituted with a phenyl group, even more preferably a methyl group or an ethyl group substituted with a phenyl group, and particularly preferably a methyl group substituted with a phenyl group.

[0030] (B) The number of phosphorus atoms contained in the phosphorus-based flame retardant containing a spiro ring in its molecular structure is preferably 1 to 5, more preferably 1 to 3, still more preferably 1 or 2. (B) When the phosphorus-based flame retardant containing a spiro ring has a plurality of phosphorus atoms, each phosphorus atom preferably has a structure represented by the above general formula (B-2).

[0031] (B) The number of ring members of the two rings constituting the spiro ring of the phosphorus-based flame retardant containing a spiro ring is each independently preferably 4 to 10, more preferably 5 to 8, still more preferably 5 to 7, and particularly preferably 6. That is, the spiro ring of the phosphorus-based flame retardant containing a spiro ring preferably has a structure in which two 6-membered rings share one atom, and more preferably has a structure in which two 6-membered rings share one carbon atom.

[0032] (B) A phosphorus-based flame retardant containing a spiro ring preferably contains two phosphorus atoms from the viewpoint of flame retardancy. Each of the two rings constituting the spiro ring contains one phosphorus atom as a ring-forming atom, and each of these phosphorus atoms preferably forms a phosphonate diester structure. In this specification, the ring-forming atom refers to an atom that constitutes the ring itself of a compound having a structure in which atoms are bonded in a ring shape. Atoms that do not constitute the ring (for example, hydrogen atoms bonded to the atoms constituting the ring) are not included in the ring-forming atoms. Such a phosphorus-based flame retardant containing a (B) spiro ring is preferably represented by the following general formula (B-1).

[0033] [Chemical formula] (In the formula, R B1 each independently represents an alkyl group, an aromatic hydrocarbon group, or an aromatic heterocyclic group.)

[0034] Regarding the description of R B1 in the above general formula (B-1), it is the same as the description of R B1 in the above general formula (B-2).

[0035] Examples of the phosphorus-based flame retardant containing a (B) spiro ring include 3,9-bis(phenylmethyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-bis(1-phenylethyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-bis(2-phenylethyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-bis(diphenylmethyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, and the like. Among these, 3,9-bis(phenylmethyl)-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane is preferred.

[0036] In the resin composition of the present embodiment, the content of the phosphorus-based flame retardant containing a (B) spiro ring is not particularly limited, but in the solid content of the resin composition excluding the inorganic filler, it is preferably 0.1 to 20% by mass, more preferably 1 to 15% by mass, and still more preferably 4 to 10% by mass. When the content of the phosphorus-based flame retardant containing a (B) spiro ring is equal to or higher than the above lower limit value, it tends to be easier to obtain more excellent flame retardancy. Also, when the content of the phosphorus-based flame retardant containing a (B) spiro ring is equal to or lower than the above upper limit value, it tends to be easier to obtain good dielectric properties.

[0037] <(C) char former containing a condensed ring> The resin composition of the present embodiment contains a (C) char former containing a condensed ring. As described above, the (C) char former containing a condensed ring has a property of being easily charred by containing a condensed ring. The (C) char former containing a condensed ring may be used alone or in combination of two or more.

[0038] The (C) char former containing a condensed ring preferably has a functional group from the viewpoint of having reactivity with the phosphorus-based flame retardant containing a (B) spiro ring under heating and forming a better intumescent layer. More preferably, it has one or more functional groups selected from the group consisting of a carbonyl group, a hydroxy group, a thiol group, and an amino group, and still more preferably, it has a carbonyl group. For example, when a thermosetting resin is selected as the (A) resin and the (C) char former containing a condensed ring has a functional group capable of reacting with the thermosetting resin, the functional group of the (C) char former containing a condensed ring may be consumed by the reaction with the (A) resin. From the viewpoint of suppressing such a phenomenon, the (C) char former containing a condensed ring preferably has a functional group that does not have reactivity with the (A) thermosetting resin. From the same viewpoint, the (C) char former containing a condensed ring may not have one or more selected from the group consisting of a hydroxy group, a thiol group, an amino group, and an epoxy group.

[0039] (C) The char-forming agent containing a condensed ring has a mass retention rate (hereinafter sometimes referred to as "850°C mass retention rate") when heated from 30°C to 850°C under a nitrogen atmosphere at a heating rate of 20°C / min, preferably 20% by mass or more, more preferably 30% by mass or more, still more preferably 50% by mass or more, and particularly preferably 60% by mass or more. When the 850°C mass retention rate of the char-forming agent containing a condensed ring is at least the above lower limit value, char derived from the char-forming agent containing a condensed ring tends to be sufficiently formed. Also, there is no particular limitation on the upper limit value of the 850°C mass retention rate of the char-forming agent containing a condensed ring, and it may be 100% by mass, but from the viewpoints of ease of production, etc., it may be 98% by mass or less, 95% by mass or less, or 90% by mass or less. Specifically, the 850°C mass retention rate can be measured by the method described in the examples.

[0040] The number of carbon atoms of the char-forming agent containing a condensed ring is preferably 25 or more, more preferably 27 or more, and still more preferably 30 or more. When the number of carbon atoms of the char-forming agent containing a condensed ring is at least the above lower limit value, char derived from the char-forming agent containing a condensed ring tends to be sufficiently formed. Also, there is no particular limitation on the upper limit value of the number of carbon atoms of the char-forming agent containing a condensed ring, but from the viewpoints of handleability, availability, etc., it may be 100 or less, 80 or less, or 50 or less.

[0041] The char-forming agent containing a condensed ring preferably contains a condensed ring in which 3 or more rings are condensed, more preferably contains a condensed ring in which 5 or more rings are condensed, and still more preferably contains a condensed ring in which 7 or more rings are condensed. When the char-forming agent containing a condensed ring contains a condensed ring in which the number of rings is at least the above lower limit value, char derived from the char-forming agent containing a condensed ring tends to be sufficiently formed. Further, the char-forming agent containing a (C) condensed ring may contain a condensed ring in which 20 or fewer rings are condensed, may contain a condensed ring in which 15 or fewer rings are condensed, or may contain a condensed ring in which 12 or fewer rings are condensed, from the viewpoint of handleability.

[0042] The ring constituting the condensed ring of the char-forming agent containing a (C) condensed ring may be any of an aromatic ring, an aliphatic ring, or a heterocyclic ring, but preferably contains an aromatic ring from the viewpoint of easy char formation.

[0043] The number of condensed rings of the char-forming agent containing a (C) condensed ring is preferably 1 to 5, more preferably 1 to 3, and still more preferably 1 or 2. Here, the "number of condensed rings" is counted with one condensed ring in which two or more rings are condensed as one.

[0044] Examples of the char-forming agent containing a (C) condensed ring include anthrone compounds such as anthrone, benzanthrone, isoviolanthrone, lavantrone, and indanthrone; and azo compounds such as Sudan Black, Sudan I, Sudan II, and Sudan R. Among these, from the viewpoint of char-forming property, anthrone compounds are preferred, and isoviolanthrone is more preferred.

[0045] The content of the char-forming agent containing a (C) condensed ring in the resin composition of the present embodiment is not particularly limited, but is preferably 0.1 to 20% by mass, more preferably 1 to 15% by mass, and still more preferably 4 to 10% by mass in the solid content of the resin composition excluding the inorganic filler. When the content of the char-forming agent containing a (C) condensed ring is at least the above lower limit value, it tends to be easier to obtain more excellent flame retardancy. Further, when the content of the char-forming agent containing a (C) condensed ring is at most the above upper limit value, it tends to be easier to reduce the influence of the char-forming agent containing a (C) condensed ring on the mechanical properties and the like of the resin composition.

[0046] The mass ratio [(C) / (B)] of the char-forming agent containing a condensed ring (C) to the phosphorus-based flame retardant containing a spiro ring (B) in the resin composition of the present embodiment is not particularly limited, but is preferably 0.1 to 9, more preferably 0.3 to 4, and still more preferably 0.7 to 1.5. When the mass ratio of the char-forming agent containing a condensed ring (C) to the phosphorus-based flame retardant containing a spiro ring (B) is within the above range, more excellent flame retardancy tends to be easily obtained.

[0047] <Other components> The resin composition of the present embodiment may or may not contain other components as necessary in addition to the above components. Examples of other components include inorganic fillers, curing accelerators, flame retardants other than component (B), organic solvents, and other additives. For each of these, one kind may be used alone, or two or more kinds may be used in combination.

[0048] Examples of inorganic fillers include silica, alumina, barium sulfate, talc, clay, mica powder, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum borate, barium titanate, strontium titanate, calcium titanate, bismuth titanate, titanium oxide, barium zirconate, calcium zirconate, etc. Among these, silica is preferable.

[0049] The average particle diameter of the inorganic filler is not particularly limited, but is preferably 0.05 to 10 μm, more preferably 0.1 to 5 μm, still more preferably 0.2 to 1 μm, and particularly preferably 0.3 to 0.8 μm. Here, the average particle diameter in the present embodiment refers to the particle diameter at the point corresponding to 50% by volume when a cumulative frequency distribution curve by particle diameter is obtained with the total volume of the particles being 100%, and can be measured with a particle size distribution measuring device using the laser diffraction scattering method or the like.

[0050] When the resin composition of this embodiment contains an inorganic filler, its content is preferably 20 to 90% by mass, more preferably 30 to 80% by mass, and still more preferably 40 to 70% by mass in the solid content of the resin composition. When the content of the inorganic filler is equal to or higher than the above lower limit value, good low thermal expansion properties and high frequency characteristics tend to be easily obtained. Also, when the content of the inorganic filler is equal to or lower than the above upper limit value, the moldability tends to be good.

[0051] The curing accelerator is a component used for the purpose of accelerating the curing reaction when the (A) resin is a thermosetting resin. Examples of the curing accelerator include imidazole-based curing accelerators such as imidazoles and their derivatives; organic phosphorus compounds; secondary amines, tertiary amines, quaternary ammonium salts, and the like. Among these, imidazole-based curing accelerators are preferred. When the resin composition of this embodiment contains a curing accelerator, its content is preferably 0.01 to 15 parts by mass, more preferably 0.1 to 10 parts by mass, and still more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the component (A). When the content of the curing accelerator is equal to or higher than the above lower limit value, the curing reaction of the (A) resin tends to proceed more efficiently. Also, when the content of the curing accelerator is equal to or lower than the above upper limit value, a homogeneous reaction tends to proceed easily.

[0052] Examples of the flame retardant other than the phosphorus-based flame retardant containing a spiro ring (B) include phosphorus-based flame retardants not containing a spiro ring, metal hydrates, halogen-based flame retardants, and the like. Among these, from the viewpoint of environmental problems, phosphorus-based flame retardants and metal hydrates are preferred. The phosphorus-based flame retardant may be an inorganic phosphorus-based flame retardant, but from the viewpoints of dielectric properties, adhesion to conductors, heat resistance, glass transition temperature, low thermal expansion properties, and flame retardancy, an organic phosphorus-based flame retardant is preferred. Examples of inorganic phosphorus-based flame retardants include red phosphorus; ammonium phosphates such as monoammonium phosphate, diammonium phosphate, triammonium phosphate, and ammonium polyphosphate; inorganic nitrogen-containing phosphorus compounds such as phosphoric acid amide; phosphoric acid; phosphine oxide, and the like. Examples of organic phosphorus-based flame retardants include aromatic phosphate esters, monosubstituted phosphonic acid diesters, disubstituted phosphinic acid esters, metal salts of disubstituted phosphinic acids, organic nitrogen-containing phosphorus compounds, cyclic organic phosphorus compounds, phosphine oxide compounds, and the like. Here, examples of the metal salts of disubstituted phosphinic acids include lithium salts, sodium salts, potassium salts, calcium salts, magnesium salts, aluminum salts, titanium salts, zinc salts, and the like.

[0053] The resin composition of this embodiment may not contain a flame retardant other than the phosphorus-based flame retardant containing a spiro ring (B). However, when it contains a flame retardant other than the phosphorus-based flame retardant containing a spiro ring (B), the content of the flame retardant other than the phosphorus-based flame retardant containing a spiro ring (B) may be more than 0% by mass and 5% by mass or less, more than 0% by mass and 1% by mass or less, or more than 0% by mass and 0.1% by mass or less in the solid content of the resin composition excluding the inorganic filler.

[0054] Examples of organic solvents include acetone, methyl ethyl ketone, toluene, xylene, cyclohexanone, 4-methyl-2-pentanone, ethyl acetate, ethylene glycol monoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, N,N-dimethylformamide, N,N-dimethylacetamide, and the like.

[0055] Examples of other additives include ultraviolet absorbers such as benzotriazoles; antioxidants such as hindered phenol antioxidants and styrenated phenol antioxidants; photoinitiators such as benzophenones, benzyl ketals, and thioxanthones; optical brighteners such as stilbene derivatives, urea compounds, adhesion improvers such as silane coupling agents; crosslinking agents such as cyanamide-based crosslinking agents, and the like. The content of other additives is not particularly limited, and it may be used as necessary within a range that does not inhibit the effects of the present embodiment.

[0056] In the solid content of the resin composition of the present embodiment excluding the inorganic filler, the total content of (A) resin, (B) phosphorus-based flame retardant containing a spiro ring, and (C) char former containing a condensed ring is preferably 90 to 100% by mass, more preferably 93 to 99% by mass, and still more preferably 96 to 98% by mass. When the total content of (A) resin, (B) phosphorus-based flame retardant containing a spiro ring, and (C) char former containing a condensed ring is within the above range, it tends to be easier to obtain more excellent flame retardancy while sufficiently obtaining the properties derived from the (A) resin.

[0057] <Method for producing resin composition> The resin composition of the present embodiment can be produced by mixing the above components. When mixing the components, the components may be dissolved or dispersed while stirring. Also, conditions such as the order of mixing the raw materials, the mixing temperature, and the mixing time are not particularly limited and may be arbitrarily set according to the type of raw materials and the like.

[0058] <Use of resin composition> The uses of the resin composition of this embodiment are not particularly limited. For example, it is suitable for multilayer printed wiring boards such as resin films and prepregs; for semiconductor encapsulants; for electronic component applications such as solder resists, underfill materials, and die bonding materials. In addition to electronic component applications, it can also be applied to various applications that require flame retardancy, such as building materials, interior materials, and packaging materials. Among these, for the resin composition of this embodiment, it is preferable that (A) the resin is a thermosetting resin and is used for multilayer printed wiring boards or semiconductor encapsulants.

[0059] [Prepreg] The prepreg of this embodiment is a prepreg containing the resin composition of this embodiment, wherein (A) the resin is a thermosetting resin. The prepreg of this embodiment is preferably obtained by impregnating or coating the resin composition of this embodiment on a sheet-like fiber-reinforced substrate and then B-staging it. In this specification, B-staging means bringing it into the state of B-stage defined in JIS K6900 (1994), and is also referred to as semi-curing.

[0060] As the sheet-like fiber-reinforced substrate contained in the prepreg of this embodiment, known sheet-like fiber-reinforced substrates used for various laminated boards for electrical insulation materials can be used. Examples of the material of the sheet-like fiber-reinforced substrate include inorganic fibers such as E-glass, D-glass, S-glass, and Q-glass; organic fibers such as polyimide, polyester, and tetrafluoroethylene; and mixtures thereof. These sheet-like fiber-reinforced substrates have shapes such as woven fabrics, non-woven fabrics, rovings, chopped strand mats, and surfacing mats. The thickness of the sheet-like fiber-reinforced substrate is not particularly limited, but from the viewpoints of mechanical strength and thinning of the prepreg, it is preferably 0.01 to 0.5 mm, more preferably 0.02 to 0.3 mm, and even more preferably 0.03 to 0.1 mm. The sheet-like fiber-reinforced base material may be surface-treated with a coupling agent or the like, or may be mechanically fibrillated, from the viewpoints of the impregnation property of the resin composition, heat resistance, moisture absorption resistance, and processability when formed into a laminate.

[0061] The prepreg of the present embodiment can be produced, for example, by impregnating or coating the sheet-like fiber-reinforced base material with the resin composition of the present embodiment and then drying it as necessary. As a method for impregnating or coating the resin composition of the present embodiment onto the sheet-like fiber-reinforced base material, for example, a hot melt method, a solvent method, or the like can be adopted.

[0062] The hot melt method is a method of impregnating or coating a resin composition that does not contain an organic solvent onto a sheet-like fiber-reinforced base material. As one aspect of the hot melt method, there is a method in which the resin composition of the present embodiment that does not contain an organic solvent is once coated on a release-coated paper with good releasability, and then the coated resin composition is laminated onto a sheet-like fiber-reinforced base material. As another aspect of the hot melt method, there is a method of directly coating the resin composition of the present embodiment that does not contain an organic solvent onto a sheet-like fiber-reinforced base material using a die coater or the like.

[0063] The solvent method is a method of impregnating or coating a resin composition containing an organic solvent onto a sheet-like fiber-reinforced base material. Specifically, for example, there is a method of immersing a sheet-like fiber-reinforced base material in the resin composition of the present embodiment containing an organic solvent and then drying it. By drying, the organic solvent in the resin composition can be removed, and the resin composition can be B-staged. The drying temperature is not particularly limited, but from the viewpoints of productivity and appropriately B-staging the resin composition of the present embodiment, it is preferably 50 to 200°C, more preferably 100 to 190°C, and even more preferably 150 to 180°C. The drying time is not particularly limited, but from the viewpoints of productivity and moderately B-staging the resin composition of the present embodiment, it is preferably 1 to 30 minutes, more preferably 2 to 15 minutes, and still more preferably 3 to 10 minutes.

[0064] The solid content concentration derived from the resin composition in the prepreg of the present embodiment is not particularly limited, but from the viewpoint of obtaining better moldability when forming a laminated board, it is preferably 20 to 90% by mass, more preferably 25 to 80% by mass, and still more preferably 30 to 75% by mass.

[0065] The thickness of the prepreg of the present embodiment is not particularly limited, but from the viewpoints of moldability and enabling high-density wiring, it is preferably 0.01 to 0.5 mm, more preferably 0.02 to 0.3 mm, and still more preferably 0.03 to 0.1 mm.

[0066] [Resin film] The resin film of the present embodiment is a resin film containing the resin composition of the present embodiment in which the (A) resin is a thermosetting resin. The resin film of the present embodiment can be produced, for example, by applying the resin composition of the present embodiment containing an organic solvent, that is, a resin varnish, to a support and then heating and drying it.

[0067] Examples of the support include plastic films, metal foils, release papers, and the like. Examples of the plastic film include films of polyolefins such as polyethylene, polypropylene, and polyvinyl chloride; polyester films such as polyethylene terephthalate [hereinafter sometimes referred to as "PET."], polyethylene naphthalate; polycarbonate films, polyimide films, and the like. Among these, from the viewpoints of economy and handleability, a polyethylene terephthalate film is preferred. Examples of the metal foil include copper foil, aluminum foil, etc. When using a copper foil for the support, the copper foil can be used as the conductor layer as it is, and a circuit can be formed. In this case, as the copper foil, a rolled copper foil, an electrolytic copper foil, etc. can be used. When using a thin copper foil, from the viewpoint of improving workability, a copper foil with a carrier may be used. The support may be subjected to surface treatment such as mat treatment, corona treatment, etc. Further, the support may be subjected to a release treatment with a silicone resin-based release agent, an alkyd resin-based release agent, a fluororesin-based release agent, etc. The thickness of the support is not particularly limited, but from the viewpoints of handleability and economy, it is preferably 10 to 150 μm, more preferably 20 to 100 μm, and still more preferably 25 to 50 μm.

[0068] As the coating device for applying the resin varnish, for example, coating devices known to those skilled in the art such as a comma coater, a bar coater, a kiss coater, a roll coater, a gravure coater, a die coater, etc. can be used. These coating devices may be appropriately selected according to the film thickness to be formed. The drying conditions after applying the resin varnish may be appropriately determined according to the content of the organic solvent, boiling point, etc., and are not particularly limited. For example, in the case of a resin varnish containing 40 to 60% by mass of an aromatic hydrocarbon-based solvent, the drying temperature is not particularly limited, but from the viewpoints of productivity and moderately B-stageizing the resin composition of the present embodiment, it is preferably 50 to 200 °C, more preferably 100 to 190 °C, and still more preferably 150 to 180 °C. Also, in the case of the above resin varnish, the drying time is not particularly limited, but from the viewpoints of productivity and moderately B-stageizing the resin composition of the present embodiment, it is preferably 1 to 30 minutes, more preferably 2 to 15 minutes, and still more preferably 3 to 10 minutes.

[0069] The thickness of the resin film of the present embodiment can be appropriately determined according to the use of the resin film. From the viewpoints of moldability and enabling high-density wiring, it is preferably 5 to 150 μm, more preferably 10 to 100 μm, and still more preferably 15 to 60 μm.

[0070] The resin film of the present embodiment may have a protective film. The protective film is provided on the surface opposite to the surface on which the support of the resin film of the present embodiment is provided, and is used for the purpose of preventing adhesion of foreign substances and the like and damage to the resin film. The protective film is peeled off before laminating the resin film of the present embodiment on a circuit board or the like by lamination, hot pressing, or the like.

[0071] The resin film of the present embodiment is preferably used to form an insulating layer when manufacturing a multilayer printed wiring board. The resin film of the present embodiment is, for example, a layer that melts and flows by laminating on a circuit board and serves to embed the circuit board when manufacturing a multilayer printed wiring board. Further, the resin film of the present embodiment, for example, when there are through holes, via holes, etc. in the circuit board, flows into them and serves to fill the holes.

[0072] [Laminated board] The laminated board of the present embodiment is a laminated board containing a cured product of the resin composition of the present embodiment, where the resin is a thermosetting resin. Note that a laminated board having a metal foil may sometimes be referred to as a metal-clad laminated board. The metal of the metal foil is not particularly limited as long as it is used for electrical insulation material applications. For example, copper, gold, silver, nickel, platinum, molybdenum, ruthenium, aluminum, tungsten, iron, titanium, chromium, alloys containing one or more of these metal elements, etc. may be mentioned. Examples of alloys include copper-based alloys, aluminum-based alloys, iron-based alloys, etc. Examples of copper-based alloys include copper-nickel alloys, etc. Examples of iron-based alloys include iron-nickel alloys, etc. Among these, from the viewpoints of conductivity and availability, copper, nickel, aluminum, and iron-nickel alloys are preferred, copper and aluminum are more preferred, and copper is even more preferred. The thickness of the metal foil is not particularly limited, but is preferably 1 to 200 μm, more preferably 2 to 100 μm, and even more preferably 3 to 50 μm.

[0073] The laminate of the present embodiment can be manufactured, for example, by disposing metal foils on one or both sides of the prepreg of the present embodiment and then performing thermocompression molding. Normally, by this thermocompression molding, the prepreg in a semi-cured state is cured to obtain the laminate of the present embodiment. When performing thermocompression molding, only one prepreg may be used, or two or more prepregs may be laminated. Further, in addition to the prepreg and the metal foil, a substrate subjected to inner layer circuit processing may be included and thermocompression molded. For thermocompression molding, for example, a multi-stage press, a multi-stage vacuum press, a continuous molding machine, an autoclave molding machine, etc. can be used. The heating temperature of the thermocompression molding is not particularly limited, but is preferably 100 to 300 °C, more preferably 150 to 280 °C, and even more preferably 200 to 250 °C. The heating and pressurizing time of the thermocompression molding is not particularly limited, but is preferably 10 to 300 minutes, more preferably 30 to 200 minutes, and even more preferably 80 to 150 minutes. The pressure of the thermocompression molding is not particularly limited, but is preferably 1.5 to 5 MPa, more preferably 1.7 to 3 MPa, and even more preferably 1.8 to 2.5 MPa. However, these conditions can be appropriately adjusted according to the type of raw materials used, etc., and are not particularly limited.

[0074] [Multilayer printed wiring board] The multilayer printed wiring board of the present embodiment is a multilayer printed wiring board containing a cured product of the resin composition of the present embodiment, wherein (A) the resin is a thermosetting resin. The multilayer printed wiring board of the present embodiment includes, for example, a multilayer structure containing a cured product of the prepreg of the present embodiment, a cured product of the resin film of the present embodiment, or a laminate of the present embodiment, and a conductor circuit layer. Hereinafter, a method for manufacturing the multilayer printed wiring board of the present embodiment using the resin film of the present embodiment will be described.

[0075] When manufacturing a multilayer printed wiring board using the resin film of the present embodiment, first, the resin film of the present embodiment is laminated on one or both sides of a circuit board. After arranging the resin film of the present embodiment so as to be in contact with the circuit board, for example, it can be laminated on the circuit board by pressure-bonding while applying pressure and heat by a vacuum laminator, thereby laminating the resin film of the present embodiment on the circuit board. Examples of the circuit board used for the multilayer printed wiring board include those having a conductor layer (circuit) subjected to pattern processing formed on one or both sides of, for example, a glass epoxy, a metal substrate, a polyester substrate, a polyimide substrate, a BT resin substrate, a thermosetting polyphenylene ether substrate, etc. From the viewpoint of adhesiveness, the surface of the conductor layer of the circuit board may be previously roughened by a blackening treatment or the like.

[0076] Next, after peeling the support of the resin film as necessary, the resin film is heat-cured to form an insulating layer. The heating temperature during heat-curing is not particularly limited, but is preferably 100 to 300 °C, more preferably 120 to 280 °C, and still more preferably 150 to 250 °C. The heating time during heat-curing is not particularly limited, but is preferably 2 to 300 minutes, more preferably 5 to 200 minutes, and still more preferably 10 to 150 minutes.

[0077] After forming the insulating layer by the above method, drilling may be performed as necessary. Drilling is a process of forming via holes, through holes, etc. by drilling, laser, plasma, a combination of these, or other methods in the circuit board and the formed insulating layer. As the laser used for drilling, for example, a carbon dioxide laser, a YAG laser, a UV laser, an excimer laser, etc. are used.

[0078] Next, the surface of the insulating layer may be roughened with an oxidizing agent. Also, when via holes, through holes, etc. are formed in the insulating layer and the circuit board, the so-called "smear" generated during the formation of these may be removed with an oxidizing agent. The roughening treatment and the removal of smear can be performed simultaneously. By the roughening treatment, an anchor of unevenness can be formed on the surface of the insulating layer. Examples of the oxidizing agent include permanganates such as potassium permanganate and sodium permanganate, dichromates, ozone, hydrogen peroxide, sulfuric acid, nitric acid, etc. Among these, an aqueous sodium hydroxide solution of potassium permanganate and an aqueous sodium hydroxide solution of sodium permanganate, which are oxidizing agents widely used in the manufacture of multilayer printed wiring boards by the build-up method, are preferable.

[0079] Next, a conductor layer is formed on the surface of the roughened insulating layer. The conductor layer can be formed, for example, by plating. Examples of the plating method include electroless plating method, electrolytic plating method, etc. Examples of the metal for plating include copper, gold, silver, nickel, platinum, molybdenum, ruthenium, aluminum, tungsten, iron, titanium, chromium, and alloys containing at least one of these metal elements. Among these, copper and nickel are preferable, and copper is more preferable. Note that it is also possible to adopt a method of forming a plating resist having a pattern opposite to the wiring pattern first, and then forming the wiring pattern only by electroless plating. Also, after forming the conductor layer, an annealing process may be performed. By performing the annealing process, the adhesion strength between the interlayer insulating layer and the conductor layer tends to be further improved and stabilized.

[0080] As a method of patterning the conductor layer to form a circuit, for example, known methods such as a subtractive method, a full additive method, a semi-additive method (SAP: SemiAdditive Process), a modified semi-additive method (m-SAP: modified Semi Additive Process), etc. can be used.

[0081] [Semiconductor Package] The semiconductor package of the present embodiment is a semiconductor package containing a cured product of the resin composition of the present embodiment, where (A) the resin is a thermosetting resin. Examples of the semiconductor package of the present embodiment include those obtained by mounting a semiconductor on the multilayer printed wiring board of the present embodiment. The semiconductor package of the present embodiment can be manufactured, for example, by mounting a semiconductor chip, a memory, etc. on the multilayer printed wiring board of the present embodiment by a known method.

Examples

[0082] Hereinafter, the present embodiment will be specifically described with reference to examples. However, the present embodiment is not limited to the following examples.

[0083] [Measurement of Mass Residual Ratio at 850°C] The mass residual ratio at 850°C of the raw materials and the raw material mixture was measured by the following procedure using a differential thermal thermogravimetric simultaneous measurement device "STA7200" (manufactured by Hitachi High-Tech Science Corporation). A 10-mg sample to be measured was charged into a platinum pan (diameter: 5.2 mm, height: 5.0 mm), heated from 30°C to 850°C under the conditions of a nitrogen flow rate of 100 mL / min and a heating rate of 20°C / min, and then held at 850°C for 10 minutes. Subsequently, the residual rate of the mass after holding at 850°C for 10 minutes with respect to the mass at 30°C before heating was determined as the 850°C mass residual rate.

[0084] Example 1, Comparative Examples 1 to 3 (Manufacture of Resin Composition) Each component listed in Table 1 was blended according to the blending amounts listed in Table 1 together with methyl ethyl ketone, and then stirred and mixed to prepare a resin composition with a solid content concentration of 62% by mass. In Table 1, the unit of the blending amount of each component is parts by mass, and in the case of a solution, it means parts by mass in terms of solid content conversion. Note that the component (B) shown in Table 1 is a compound having a structure represented by the following formula (B-3).

[0085]

Chemical formula

[0086] Also, the 850°C mass residual rate of isoviolanthrone as the component (C) was 77.7% by mass.

[0087] (Manufacture of Prepreg) Next, the resin varnish obtained above was impregnated into an E-glass cloth with a thickness of 0.095 mm, and then dried at 120°C for 5 minutes to obtain a prepreg.

[0088] (Manufacture of Laminated Board) Copper foils with a thickness of 18 μm were stacked on both sides of a stack of 4 prepregs obtained above, and then heat-press formed at a temperature of 230°C and a pressure of 2.0 MPa for 90 minutes to fabricate a double-sided copper-clad laminated board with a thickness of 0.42 mm.

[0089] [Evaluation of Flame Retardancy] The outer copper foil of the double-sided copper-clad laminate was removed by immersing it in a copper etching solution, and a test piece was prepared by cutting it into a length of 125 mm, a width of 13 mm, and a thickness of 0.42 mm. Next, in accordance with the test method (V method) of UL94, a 20 mm flame was applied to the lower end of the vertically held test piece twice for 10 seconds each, and the combustion distance of the test piece was measured. The combustion distance was measured as the combustion distance in the length direction of the central part in the width direction of the test piece, and was obtained as the average value of 5 test pieces for each example. The results are shown in Table 1.

[0090]

Table 1

[0091] From Table 1, it can be seen that the resin composition of Example 1 containing the phosphorus-based flame retardant containing a (B) spiro ring and the char former containing a (C) condensed ring has a combustion distance equivalent to that of Comparative Example 3 where the addition amount of the phosphorus-based flame retardant is doubled, and a high flame retardancy effect is obtained with a small amount of the phosphorus-based flame retardant used. On the other hand, the resin compositions of Comparative Example 1 that do not contain the phosphorus-based flame retardant containing a (B) spiro ring and the char former containing a (C) condensed ring, and Comparative Example 2 that do not contain the phosphorus-based flame retardant containing a (B) spiro ring had a large combustion distance and were inferior in flame retardancy.

[0092] Reference Example 1, Comparative Reference Examples 1 to 3 Next, using a raw material mixture obtained by mixing the phosphorus-based flame retardant containing a (B) spiro ring and the char former containing a (C) condensed ring, which are the raw materials of the resin composition of the present embodiment, the formability of the intumescent layer was confirmed. Samples were prepared by blending the components shown in Table 2 according to the blending amounts shown in Table 2, and the 850 °C mass residue rate was measured by the method described above. After measuring the 850 °C mass residue rate, the samples were cooled under a nitrogen flow rate of 100 mL / min, and the dimensions and appearance of the residue in the platinum pan were confirmed. The 850 °C mass residue rate and dimensions are shown in Table 2, and the appearance photographs of the residue are shown in FIGS. 1 to 3. The phosphorus-based flame retardant containing a spiro ring shown in Table 2 is the same as that used in Example 1.

[0093] [Table 2]

[0094] From Table 2, it can be seen that Reference Example 1, which is a mixture of (B) a phosphorus-based flame retardant containing a spiro ring and (C) a char former containing a condensed ring, which are the raw materials of the resin composition of this embodiment, has a higher mass residue ratio at 850 °C than Reference Comparative Examples 2 and 3 that use an aromatic condensed phosphate ester, which is a comparative component, instead of the (B) phosphorus-based flame retardant containing a spiro ring.

[0095] Also, in Reference Example 1, no shrinkage was observed in the dimensions of the residue, and the height was higher than the height before measurement. On the other hand, the dimensions of the residues in Reference Comparative Examples 2 and 3 were both shrunk compared to before measurement.

[0096] Figure 1(a) shows a macroscopic photograph of the residue of Reference Example 1 after the differential thermal thermogravimetric simultaneous test, Figure 1(b) shows that of Reference Comparative Example 2, and Figure 1(c) shows that of Reference Comparative Example 3. For the residue 1 of Reference Example 1 shown in Figure 1(a), the bottom of the platinum pan could not be seen, and the height position of the residue was higher than the height position of the sample before measurement. On the other hand, the residue 1 of Reference Comparative Example 2 shown in Figure 1(b) and the residue 1 of Reference Comparative Example 3 shown in Figure 1(c) had shrunk during the differential thermal thermogravimetric simultaneous test, and the bottom of the platinum pan (2 in Figures 1(b) and (c)) was exposed due to the shrinkage. Note that the white-looking part inside the platinum pan in Figure 1(a) is the part where the residue 1 reflects light and looks white, not the bottom of the platinum pan.

[0097] Figure 2(a) shows an optical microscope photograph of the surface of the residue of Reference Example 1, Figure 2(b) shows that of Reference Comparative Example 2, and Figure 2(c) shows that of Reference Comparative Example 3. Although several large voids (3 in Figure 2(a)) were observed on the surface of the residue of Reference Example 1 shown in Figure 2(a), no clear voids were seen in the part other than the voids, and a skin layer with a smooth surface structure was formed. On the other hand, a large number of small voids were present on the surfaces of the residues of Comparative Reference Example 2 shown in FIG. 2(b) and the residues of Comparative Reference Example 3 shown in FIG. 2(c), covering the whole.

[0098] FIG. 3 shows an optical micrograph of the side surface of the residue of Reference Example 1. In the side surface of the residue of Reference Example 1, a structure in which large pores are supported by pillars (4 in FIG. 3) was confirmed.

[0099] As described above, by using in combination the phosphorus-based flame retardant containing a (B) spiro ring and the char former containing a (C) condensed ring, which are the raw materials of the resin composition of the present embodiment, a dense skin layer with few voids on the surface layer and a good intumescent layer expanded by foaming directly below the surface layer were confirmed to be formed.

Explanation of Signs

[0100] 1 Residue after measurement of 850 °C mass retention rate 2 Bottom of platinum pan 3 Void of residue 4 Residue pillar

Claims

1. (A) a resin, (B) a phosphorus-based flame retardant containing a spiro ring, (C) a char former containing a condensed ring, and a resin composition containing the same, wherein the char former (C) containing a condensed ring has a mass residue ratio of 20% by mass or more when heated from 30°C to 850°C under the condition of a heating rate of 20°C / min in a nitrogen atmosphere.

2. The resin composition according to claim 1, wherein the phosphorus-based flame retardant (B) containing a spiro ring contains a phosphonate diester structure.

3. The resin composition according to claim 2, wherein the phosphorus-based flame retardant (B) containing a spiro ring contains two phosphorus atoms, and each of the two rings constituting the spiro ring contains one phosphorus atom as a ring-forming atom, and each of the phosphorus atoms forms the phosphonate diester structure.

4. The resin composition according to claim 3, wherein the phosphorus-based flame retardant (B) containing a spiro ring is represented by the following general formula (B-1). 【Chemical Formula 1】 (In the formula, R Ｂ１ each independently represents an alkyl group, an aromatic hydrocarbon group or an aromatic heterocyclic group.)

5. The resin composition according to any one of claims 1 to 4, wherein the char former (C) containing a condensed ring has at least one functional group selected from the group consisting of a carbonyl group, a hydroxy group, a thiol group and an amino group.

6. The resin composition according to any one of claims 1 to 5, wherein the char former (C) containing a condensed ring has 25 or more carbon atoms.

7. The resin composition according to any one of claims 1 to 6, wherein the char former (C) containing a condensed ring contains a condensed ring in which three or more rings are condensed.

8. The resin composition according to any one of claims 1 to 7, wherein the resin (A) is a thermosetting resin.

9. The resin composition according to claim 8, which is for a multilayer printed wiring board or a semiconductor encapsulant.

10. A prepreg containing the resin composition according to claim 8.

11. A resin film containing the resin composition according to claim 8.

12. A laminate containing a cured product of the resin composition according to claim 8.

13. A multilayer printed wiring board containing a cured product of the resin composition according to claim 8.

14. A semiconductor package containing a cured product of the resin composition according to claim 8.

Images