Prepreg, metal-clad laminate, printed wiring board, and semiconductor package

Abstract

Provided are: a prepreg capable of exhibiting low thermal expansion; a metal-clad laminate having low thermal expansion; a printed wiring board having the metal-clad laminate; and a semiconductor package having the printed wiring board. Specifically, the prepreg contains a resin composition or a semi-cured product of the resin composition, wherein the resin composition contains (A) a bismaleimide compound. In the bismaleimide compound (A), nitrogen atoms in two maleimide groups are bonded by an organic group, and the organic group has three aromatic hydrocarbon groups.

Description

Prepregs, metal-clad laminates, printed circuit boards, and semiconductor packages

[0001] This embodiment relates to prepregs, metal-clad laminates, printed circuit boards, and semiconductor packages.

[0002] In recent years, the miniaturization and increased performance of electronic devices have led to advancements in wiring density and integration in the fields of printed circuit boards and semiconductor packages. In these electronic devices, insulating materials containing thermosetting resins, etc., are used as substrate materials in prepregs or metal-clad laminates used in the manufacture of printed circuit boards. However, stress can occur during component mounting due to the difference in thermal expansion coefficients between the insulating material and the semiconductor chip. This stress is thought to cause warping of the semiconductor package and can be a factor that reduces reliability. As a method to bring the thermal expansion coefficient of the insulating material closer to that of the semiconductor chip, a method of reducing the thermal expansion of the insulating material by compounding silica as an inorganic filler into the insulating material is known (see, for example, Patent Document 1).

[0003] Excerpt from Japanese Patent Publication No. 2024-035604, paragraph

[0107]

[0004] However, when a large amount of inorganic filler such as silica is added to the insulating material, the viscosity of the resin varnish increases and its fluidity decreases. This causes the inorganic filler, such as silica, to be unevenly distributed within the insulating layer, thus limiting the amount of inorganic filler that can be added. Therefore, the method of reducing thermal expansion by adding inorganic filler such as silica to the insulating material has a limit to the amount of inorganic filler that can be added. Thus, the development of alternative methods for reducing the thermal expansion of metal-clad laminates containing insulating materials is highly anticipated.

[0005] In view of the current situation, this embodiment aims to provide a prepreg capable of exhibiting low thermal expansion, a metal-clad laminate having low thermal expansion, a printed circuit board having the metal-clad laminate, and a semiconductor package having the printed circuit board.

[0006] As a result of advancing studies to solve the above problems, the present inventors have found that the problems can be solved by the embodiments described in this specification. The present disclosure includes the following embodiments [1] to

[10] . [1] A prepreg containing a resin composition or a semi-cured product of the resin composition, wherein the resin composition contains (A) a bismaleimide compound, and in the (A) bismaleimide compound, nitrogen atoms in two maleimide groups are bonded by an organic group, and the organic group has three aromatic hydrocarbon groups. [2] The prepreg according to [1] above, wherein the aromatic hydrocarbon group possessed by the (A) bismaleimide compound is a group selected from the following group. (R ａ１ ~R ａ８ each independently represents an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, an alkoxyl group having 1 to 10 carbon atoms, or a halogen atom. n ａ１ is an integer from 0 to 4, n ａ２ and n ａ３ each independently is an integer from 0 to 3, n ａ４ is an integer from 0 to 2, n ａ５ is an integer from 0 to 4, n ａ６ is an integer from 0 to 3, n ａ７ is an integer from 0 to 2, n ａ８(0 or 1. * indicates a bonding site.) [3] The prepreg according to [1] or [2] above, wherein the linking group that bonds the aromatic hydrocarbon groups of the (A) bismaleimide compound is a linking group selected from the group consisting of ether groups and alkylene groups having 1 to 5 carbon atoms. [4] The prepreg according to any one of [1] to [3] above, wherein the (A) bismaleimide compound includes a modified product of one or more selected from the group consisting of monoamine compounds and diamine compounds. [5] The prepreg according to [4] above, wherein the diamine compound is one or more selected from the group consisting of aromatic diamine compounds having two amino groups directly bonded to the aromatic ring and siloxanediamine compounds having two primary amino groups. [6] The prepreg according to any one of [1] to [5] above, wherein the resin composition further contains (B) an inorganic filler. [7] The prepreg according to any one of [1] to [6], wherein the resin composition further contains (C) a curing accelerator. [8] A metal-clad laminate having a metal foil and a laminate containing a cured product of the prepreg according to any one of [1] to [7]. [9] A printed circuit board having the metal-clad laminate according to [8].

[10] A semiconductor package having the printed circuit board according to [9].

[0007] According to this embodiment, it is possible to provide a prepreg capable of exhibiting low thermal expansion, a metal-clad laminate having low thermal expansion, a printed circuit board having the metal-clad laminate, and a semiconductor package having the printed circuit board.

[0008] This is an image of the molecular model obtained by the simulation in Reference Example 1. For comparison, this is an image of the molecular model obtained by the simulation in Reference Example 1.

[0009] In this specification, numerical ranges indicated using "~" represent a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. For example, the notation "X~Y" (where X and Y are real numbers) means a numerical range that is greater than or equal to X and less than or equal to Y. In this specification, "greater than or equal to X" means a number greater than or equal to X. In this specification, "less than or equal to Y" means a number less than or equal to Y. The lower and upper limits of numerical ranges described in this specification can be arbitrarily combined with the lower or upper limits of other numerical ranges. In numerical ranges described in this specification, the lower or upper limit of that numerical range may be replaced with the values ​​shown in the examples.

[0010] Each component and material exemplified herein may be used alone or in combination of two or more, unless otherwise specified. In this specification, the content of each component in a resin composition means the total amount of multiple substances present in the resin composition, unless otherwise specified, if multiple substances corresponding to each component are present in the resin composition. In this specification, "resin composition" means a mixture of two or more components containing resin components, and includes a mixture in the B-stage state as defined in JIS K6900 (1994). However, the type and content of each component in a resin composition in the B-stage state means the type and content of each component before reaching the B-stage state, that is, the type and amount of components blended when manufacturing the resin composition.

[0011] In this specification, "solids" refers to components in the resin composition other than organic solvents, as described later, and components that are liquid at room temperature around 25°C are also considered to be solids. Furthermore, "resin components" is defined as all components of the resin composition that constitute the solids, excluding inorganic compounds such as (B) inorganic fillers, as described later.

[0012] The mechanism of action described herein is speculative and does not limit the mechanism by which the resin composition according to this embodiment exerts its effects.

[0013] Embodiments that combine any combination of the information described herein are also included.

[0014] [Prepreg] The prepreg of this embodiment is a prepreg comprising a resin composition or a semi-cured product of the resin composition, wherein the resin composition contains (A) a bismaleimide compound, and the (A) bismaleimide compound has nitrogen atoms in two maleimide groups bonded by an organic group, and the organic group has three aromatic hydrocarbon groups. By being a prepreg containing the specific bismaleimide compound, the metal-clad laminate obtained using the prepreg has excellent low thermal expansion properties.

[0015] The components that the resin composition may contain will be described below in order.

[0016] <(A) Bismaleimide Compound> The resin composition contains the (A) bismaleimide compound, which improves its low thermal expansion properties. The (A) bismaleimide compound has nitrogen atoms in two maleimide groups bonded by an organic group, and the organic group is a bismaleimide compound having three aromatic hydrocarbon groups. Here, "having three aromatic hydrocarbon groups" does not mean having three or more aromatic hydrocarbon groups, but rather having exactly three aromatic hydrocarbon groups. The reason why such a bismaleimide compound exhibits a low thermal expansion effect is presumed to be that the particular bismaleimide compound has a structure that makes it easy for molecules to stack, and thermal expansion is suppressed by this stacking. However, this is merely a presumption, and even if this presumption is incorrect, it will not adversely affect the scope of this embodiment. It is also presumed that bismaleimide compounds having only two aromatic hydrocarbon groups may also exhibit the aforementioned stacking effect. However, bismaleimide compounds having only two aromatic hydrocarbon groups have a high tendency to precipitate in organic solvents, which presents another problem: the stability of the resin varnish is low and handling is difficult. The bismaleimide compound (A) has the advantage of not precipitation easily in organic solvents (for example, propylene glycol monomethyl ether), thus avoiding this problem.

[0017] The aromatic hydrocarbon group of the (A) bismaleimide compound is preferably a group selected from the following group from the viewpoint of reducing thermal expansion.

[0018]

[0019] The aromatic hydrocarbon group of the (A) bismaleimide compound is more preferably a group selected from the following group from the viewpoint of reducing thermal expansion.

[0020]

[0021] The aromatic hydrocarbon group of the (A) bismaleimide compound is even more preferably a group selected from the following group from the viewpoint of reducing thermal expansion.

[0022]

[0023] The aromatic hydrocarbon group of the (A) bismaleimide compound is particularly preferably the following group from the viewpoint of reducing thermal expansion.

[0024]

[0025] R ａ１ ~R ａ８ Each independently represents an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, an alkoxyl group having 1 to 10 carbon atoms, or a halogen atom. n ａ１ is an integer of 0 to 4, n ａ２ and n ａ３ Each independently is an integer of 0 to 3, n ａ４ is an integer of 0 to 2, n ａ５ is an integer of 0 to 4, n ａ６ is an integer of 0 to 3, n ａ７ is an integer of 0 to 2, n ａ８ is 0 or 1. * indicates the bonding site.

[0026] R ａ１ ~R ａ８Examples of C1-C10 alkyl groups represented by include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl groups. The alkyl group may be linear or branched. From the viewpoint of low thermal expansion, the number of carbon atoms in the alkyl group is preferably 1-6, more preferably 1-5, and even more preferably 1-3. ａ１ ~R ａ８ Examples of alkenyl groups having 2 to 10 carbon atoms include vinyl groups, allyl groups, propenyl groups, and butenyl groups. These alkenyl groups may be linear or branched. From the viewpoint of reducing thermal expansion, the number of carbon atoms in the alkenyl group is preferably 2 to 6, more preferably 2 to 5, and even more preferably 2 or 3. ａ１ ~R ａ８ Examples of alkynyl groups having 2 to 10 carbon atoms include ethynyl groups and propargyl groups. The alkynyl group may be linear or branched. From the viewpoint of reducing thermal expansion, the number of carbon atoms in the alkynyl group is preferably 2 to 6, more preferably 2 to 5, and even more preferably 2 or 3. ａ１ ~R ａ８ Examples of alkoxy groups having 1 to 10 carbon atoms include methoxy groups, ethoxy groups, n-propoxy groups, isopropoxy groups, n-butoxy groups, t-butoxy groups, etc. The alkoxy group may be linear or branched. From the viewpoint of reducing thermal expansion, the number of carbon atoms in the alkoxy group is preferably 1 to 6, more preferably 1 to 5, and even more preferably 1 to 3. ａ１ ~R ａ８ Examples of halogen atoms represented include fluorine, chlorine, bromine, and iodine atoms.

[0027] n ａ１ From the viewpoint of reducing thermal expansion, n is preferably an integer from 0 to 3, more preferably an integer from 0 to 2, even more preferably 0 or 1, and particularly preferably 0. ａ２ and n ａ３ From the viewpoint of reducing thermal expansion, each of these values ​​is preferably an integer between 0 and 2, more preferably 0 or 1, and even more preferably 0. ａ４From the viewpoint of reducing thermal expansion, n is preferably 0 or 1, more preferably 0. ａ５ From the viewpoint of reducing thermal expansion, n is preferably an integer from 0 to 3, more preferably an integer from 0 to 2, even more preferably 0 or 1, and particularly preferably 0. ａ６ From the viewpoint of minimizing thermal expansion, n is preferably an integer between 0 and 2, more preferably 0 or 1, and even more preferably 0. ａ７ From the viewpoint of reducing thermal expansion, n is preferably 0 or 1, more preferably 0. ａ８ From the viewpoint of reducing thermal expansion, this is preferably 0.

[0028] The linking groups that connect the aromatic hydrocarbon groups of the (A) bismaleimide compound are preferably selected from the group consisting of ether groups and alkylene groups having 1 to 5 carbon atoms, from the viewpoint of low thermal expansion. The linking groups that connect the aromatic hydrocarbon groups of the (A) bismaleimide compound may consist of only one type of linking group selected from the group consisting of ether groups and alkylene groups having 1 to 5 carbon atoms, or two or three types, but it is preferable that there is only one type. However, the (A) bismaleimide compound may have multiple linking groups of only one type that connect the aromatic hydrocarbon groups.

[0029] In the bismaleimide compound (A) described above, the "organic group" to which the nitrogen atoms in the two maleimide groups are linked preferably includes the following structure, and more preferably has the following structure.

[0030] (In the formula, R ａ１ ~R ａ３ and n ａ１ ~n ａ３ This is as explained above. Multiple Rs within the same structural formula ａ１ and n ａ１ The elements may be identical or different. (* indicates a bonding site.)

[0031] In the bismaleimide compound (A) described above, the "organic group" to which the nitrogen atoms in the two maleimide groups are linked is more preferably one of the following structures, and even more preferably one of the following structures.

[0032] (* indicates the binding site.)

[0033] In the bismaleimide compound (A) described above, the "organic group" to which the nitrogen atoms in the two maleimide groups are linked is particularly preferably one of the following structures, and most preferably one of the following structures.

[0034] (* indicates the binding site.)

[0035] The bismaleimide compound (A) may be a bismaleimide compound represented by any of the following structures.

[0036]

[0037] (A) There are no particular restrictions on the method for producing the bismaleimide compound, and known methods and methods described in the examples can be used and applied. For example, the bismaleimide compound (A) can be produced by reacting maleic anhydride with the diamine compound having the organic group to obtain an intermediate, then cyclizing the intermediate by reacting it with sodium acetate in the presence of acetic anhydride, and washing sequentially with a basic aqueous solution and water as needed. Various bismaleimide compounds (A) can be produced by changing the diamine compound and adjusting the reaction conditions as appropriate.

[0038] Furthermore, the (A) bismaleimide compound may include a modified form obtained by one or more compounds selected from the group consisting of monoamine compounds and diamine compounds. The modified form is a modified bismaleimide compound obtained by the reaction of the maleimide group of the bismaleimide compound with the amino group of the monoamine compound or the diamine compound. The monoamine compound is not particularly limited and can be any monoamine compound having an acidic substituent, such as o-aminophenol, m-aminophenol, p-aminophenol, o-aminobenzoic acid, m-aminobenzoic acid, p-aminobenzoic acid, o-aminobenzenesulfonic acid, m-aminobenzenesulfonic acid, p-aminobenzenesulfonic acid, 3,5-dihydroxyaniline, or 3,5-dicarboxyaniline. The diamine compound is preferably one or more selected from the group consisting of aromatic diamine compounds having two amino groups directly bonded to the aromatic ring and siloxanediamine compounds having two primary amino groups, and from the viewpoint of low thermal expansion, siloxanediamine compounds having two primary amino groups are more preferred. Examples of the aromatic diamine compound include 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-[1,3-phenylenebis(1-methylethylidene)]bisaniline, and 4,4'-[1,4-phenylenebis(1-methylethylidene)]bisaniline.

[0039] Furthermore, if a siloxanediamine compound having two primary amino groups is added separately to a resin varnish without reacting it with a bismaleimide compound, the siloxanediamine compound having two primary amino groups tends to bleed out from the cured resin composition. However, as mentioned above, reacting the siloxanediamine compound having two primary amino groups with a bismaleimide compound tends to effectively suppress this bleed-out.

[0040] (Content of (A) bismaleimide compound) In the resin composition, there are no particular restrictions on the content of (A) bismaleimide compound, but it is preferably 5 to 80% by mass, more preferably 5 to 65% by mass, even more preferably 10 to 55% by mass, particularly preferably 15 to 50% by mass, and most preferably 25 to 45% by mass, based on the total amount of solids (100% by mass) in the resin composition. When the content of (A) bismaleimide compound is above the lower limit, the heat resistance, moldability, processability, low thermal expansion, and peel strength of the copper foil tend to be better. Also, when the content of (A) bismaleimide compound is below the upper limit, the dielectric properties tend to be better.

[0041] <(B) Inorganic Filler> The resin composition may further contain (B) an inorganic filler. The resin composition tends to have better low thermal expansion, heat resistance and flame retardancy when it contains (B) an inorganic filler. One type of (B) inorganic filler may be used alone, or two or more types may be used in combination.

[0042] (B) Examples of inorganic fillers include silica, alumina, titanium oxide, mica, beryllium, barium titanate, potassium titanate, strontium titanate, calcium titanate, aluminum carbonate, magnesium hydroxide, aluminum silicate, calcium carbonate, calcium silicate, magnesium silicate, silicon nitride, boron nitride, clay, talc, molybdate compounds (such as zinc molybdate), aluminum borate, silicon carbide, etc. Among these, silica, alumina, mica, and talc are preferred from the viewpoint of low thermal expansion, heat resistance, and flame retardancy, with silica and alumina being more preferred. Examples of silica include precipitated silica produced by the wet method with a high water content, and dry silica produced by the dry method that contains almost no bound water, etc. Examples of dry silica include crushed silica, fumed silica, and fused silica, depending on the manufacturing method.

[0043] (B) The average particle size of the inorganic filler is not particularly limited, but from the viewpoint of dispersibility and fine wiring properties of the inorganic filler, it is preferably 0.01 to 20 μm, more preferably 0.1 to 10 μm, even more preferably 0.2 to 1 μm, and particularly preferably 0.3 to 0.8 μm. In this specification, the average particle size of the inorganic filler refers to the particle size at the point corresponding to 50% of the volume when the cumulative frequency distribution curve by particle size is determined with the total volume of the particles set to 100%. The average particle size of the inorganic filler can be measured, for example, by a particle size distribution analyzer using laser diffraction scattering. The shape of the inorganic filler can be spherical, crushed, etc., and it is preferably spherical.

[0044] The resin composition may contain a coupling agent for the purpose of improving the dispersibility of the inorganic filler and its adhesion to the organic component. Examples of coupling agents include silane coupling agents and titanate coupling agents. Among these, silane coupling agents are preferred. Examples of silane coupling agents include aminosilane coupling agents, vinylsilane coupling agents, and epoxysilane coupling agents.

[0045] If the resin composition contains a coupling agent, the surface treatment of the inorganic filler (B) may be performed by the coupling agent. Specifically, the surface treatment method for the inorganic filler (B) may be an integral blend treatment method in which the coupling agent is added after the inorganic filler (B) has been blended into the resin composition, or it may be a method of pre-treating the inorganic filler (B) with the coupling agent dry or wet. Among these, from the viewpoint of more effectively expressing the characteristics of the inorganic filler (B), the method of pre-treating the inorganic filler (B) with the coupling agent dry or wet is preferred. The inorganic filler (B) may be pre-dispersed in an organic solvent to form a slurry before being mixed with other components in order to improve its dispersibility in the resin composition.

[0046] (Content of (B) inorganic filler) When the resin composition contains (B) inorganic filler, there are no particular restrictions on the content of (B) inorganic filler, but it is preferably 20 to 95% by mass, more preferably 35 to 95% by mass, even more preferably 45 to 90% by mass, particularly preferably 50 to 85% by mass, and most preferably 55 to 75% by mass, relative to the total solid content (100% by mass) of the resin composition. When the content of (B) inorganic filler is above the lower limit, the low thermal expansion properties, heat resistance and flame retardancy tend to be better. Also, when the content of (B) inorganic filler is below the upper limit, the moldability and peel strength of the copper foil tend to be better.

[0047] <(C) Curing Accelerator> The resin composition may further contain (C) a curing accelerator. The resin composition tends to have improved curability, resulting in better dielectric properties, heat resistance, and peel strength of the copper foil. (C) A curing accelerator may be used alone or in combination of two or more types.

[0048] (C) Examples of curing accelerators include acidic catalysts such as p-toluenesulfonic acid; amine compounds such as triethylamine, pyridine, tributylamine, and dicyandiamide; imidazole compounds such as methylimidazole, phenylimidazole, and 1-cyanoethyl-2-phenylimidazole; isocyanate-masquimidazole compounds such as the addition reaction product of hexamethylene diisocyanate resin and 2-ethyl-4-methylimidazole; tertiary amine compounds; quaternary ammonium compounds; phosphorus compounds such as triphenylphosphine; and carboxylates of manganese, cobalt, zinc, etc. Among these, imidazole compounds, isocyanate-masquimidazole compounds, and carboxylates are preferred from the viewpoint of curing acceleration effect and storage stability, and isocyanate-masquimidazole compounds are more preferred.

[0049] (Content of (C) curing accelerator) When the resin composition contains (C) curing accelerator, there are no particular restrictions on the content of (C) curing accelerator, but it is preferably 0.01 to 5 parts by mass, more preferably 0.01 to 3 parts by mass, even more preferably 0.05 to 1.5 parts by mass, and particularly preferably 0.1 to 1.0 parts by mass, per 100 parts by mass of the total amount of resin components. When the content of (C) curing accelerator is above the lower limit, a sufficient curing acceleration effect tends to be easily obtained. Also, when the content of (C) curing accelerator is below the upper limit, storage stability tends to be better.

[0050] <Other Components> The resin composition may further contain, if necessary, one or more optional components selected from the group consisting of resin components other than the above components, flame retardants, antioxidants, heat stabilizers, antistatic agents, ultraviolet absorbers, pigments, colorants, lubricants, organic solvents, and other additives. Examples of resin materials other than the above components include thermosetting resins; elastomers, etc. The thermosetting resin is preferably one or more selected from the group consisting of epoxy resins, phenolic resins, cyanate resins, isocyanate resins, benzoxazine resins, oxetane resins, amino resins, unsaturated polyester resins, allyl resins, dicyclopentadiene resins, silicone resins, triazine resins, and melamine resins; more preferably one or more selected from the group consisting of epoxy resins, phenolic resins, cyanate resins, isocyanate resins, amino resins, unsaturated polyester resins, and silicone resins; even more preferably one or more selected from the group consisting of epoxy resins, phenolic resins, cyanate resins, and isocyanate resins; and particularly preferably one or more selected from the group consisting of epoxy resins, phenolic resins, and cyanate resins. The elastomer is preferably one or more selected from the group consisting of styrene elastomers, maleimide elastomers, olefin elastomers, urethane elastomers, polyester elastomers, polyamide elastomers, acrylic elastomers, and silicone elastomers. In this specification, a resin composition containing an organic solvent may be referred to as a resin varnish. Each of the above optional components may be used individually or in combination of two or more. There are no particular restrictions on the content of the above optional components in the resin composition, and they may be used as needed, within a range that does not hinder the effects of this embodiment. The content of the above optional components may be, for example, 0 to 20% by mass, 0.1 to 15% by mass, 1 to 10% by mass, or 1 to 5% by mass, based on the total solid content (100% by mass). Furthermore, the resin composition may not contain the above optional components, depending on the desired performance.

[0051] (Content of resin components) There are no particular restrictions on the content of resin components in the resin composition, but from the viewpoint of low thermal expansion, heat resistance, flame retardancy, and peel strength of copper foil, it is preferably 5 to 80% by mass, more preferably 10 to 60% by mass, and even more preferably 20 to 45% by mass, based on the total solid content (100% by mass) of the resin composition.

[0052] (Method for manufacturing prepregs) There are no particular limitations on the method for manufacturing the prepregs of this embodiment, but for example, they can be manufactured by impregnating or coating a fiber substrate with a varnish-like resin composition, and then heating and drying the resin composition to partially cure it (B-stage). The heating and drying temperature is preferably 80 to 180°C, more preferably 100 to 140°C. The heating and drying time is set appropriately in consideration of the gelation time of the resin composition.

[0053] [Metal-clad laminate] The metal-clad laminate of this embodiment is a metal-clad laminate having a metal foil and a laminate containing a cured product of the prepreg of this embodiment. Since the metal-clad laminate of this embodiment is a metal-clad laminate containing the specific bismaleimide compound, it has excellent low thermal expansion properties.

[0054] In the metal-clad laminate of this embodiment, examples of the metal foil include copper foil, aluminum foil, tin foil, tin-lead alloy (solder) foil, nickel foil, etc. Other examples include a three-layer composite foil with nickel, nickel-phosphorus, nickel-tin alloy, nickel-iron alloy, lead, lead-tin alloy, etc. as an intermediate layer, with a copper layer of 0.5 to 15 μm and a copper layer of 10 to 300 μm on both sides, or a two-layer composite foil made of aluminum and copper foil. Copper foil and aluminum foil are preferred as the metal foil, with copper foil being more preferred. The thickness of the metal foil can be the thickness generally used for laminates, for example, 1 to 200 μm.

[0055] The metal-clad laminate of this embodiment may contain a fibrous substrate, or it may contain a cured prepreg comprising the fibrous substrate and the resin composition or a semi-cured product of the resin composition. Here, a semi-cured product of the resin composition means that the resin composition is in the B-stage state as defined in JIS K6900 (1994).

[0056] Examples of the fiber base material include woven fabrics and nonwoven fabrics. The fiber base material is preferably a woven fabric. Furthermore, the fiber base material is preferably a sheet-like fiber base material. Examples of materials for the fiber base material include inorganic fibers such as glass, alumina, asbestos, boron, silica-alumina glass, silica glass, tyranno, silicon carbide, silicon nitride, and zirconia; organic fibers such as aramid, polyetheretherketone, polyetherimide, polyethersulfone, carbon, and cellulose; and blends thereof. Among these, inorganic fibers are preferred, and glass fibers are more preferred. In other words, the base material is preferably a woven glass fiber fabric, i.e., glass cloth. Examples of materials for the glass cloth include E glass, D glass, S glass, and Q glass (quartz glass). The material for the glass cloth may be E glass, S glass, Q glass, or S glass. The thickness of the fiber base material is preferably 5 to 200 μm, but may also be 10 to 150 μm, 20 to 130 μm, 50 to 130 μm, or 70 to 120 μm. By keeping the thickness of the fiber base material below the above upper limit, dimensional changes due to temperature changes, moisture absorption, etc. during the manufacturing process can be reduced.

[0057] (Method for manufacturing metal-clad laminates) There are no particular restrictions on the method for manufacturing metal-clad laminates, and known methods can be used. For example, first, the adhesive surfaces on both sides of one prepreg of this embodiment, or the adhesive surfaces on both sides of a laminate obtained by laminating two or more prepregs of this embodiment (preferably 2 to 30 sheets, more preferably 2 to 20 sheets, and even more preferably 4 to 12 sheets), are placed together with the metal foil. The resulting laminate can then be manufactured by heating and pressing under reduced pressure of less than 100 hPa, preferably at 130 to 260°C, more preferably at 180 to 250°C, even more preferably at 210 to 250°C, and preferably at press conditions of 0.5 to 10 MPa, and even more preferably at 1 to 5 MPa.

[0058] In the metal-clad laminate of this embodiment, the prepreg (more specifically, the resin composition in the prepreg) is C-staged and cured. In other words, the laminate of this embodiment contains a C-staged prepreg, and the metal-clad laminate of this embodiment can also be said to contain a C-staged prepreg and metal foil. Hereinafter, C-staged means bringing the material to the C-stage state as defined in JIS K6900 (1994).

[0059] (Glass transition temperature) The glass transition temperature of the cured resin composition contained in the metal-clad laminate of this embodiment may be 270 to 470°C, 320 to 430°C, or 350 to 400°C. The glass transition temperature is the temperature at which the maximum value of tanδ, which is the ratio of the loss modulus to the storage modulus, is obtained when a dynamic viscoelasticity analyzer (DMA) is used to measure the tensile mode, temperature range 40 to 400°C, heating rate 10°C / min, frequency 10 Hz, and strain 3 μm (constant), and is measured in more detail according to the method described in the examples.

[0060] (Linear expansion coefficient) The linear expansion coefficient of the cured resin composition contained in the metal-clad laminate of this embodiment may be 3.0 to 6.3 ppm / °C, 3.5 to 6.0 ppm / °C, 4.0 to 5.8 ppm / °C, 4.5 to 5.8 ppm / °C, or 5.2 to 5.8 ppm / °C. The smaller the linear expansion coefficient, the better the low thermal expansion properties. The linear expansion coefficient is a value obtained by measuring the dimensional change using a thermomechanical measuring device (TMA) in compression mode, temperature range 25 to 260°C, heating rate 10°C / min, and load 0.1 N. More specifically, it is a value measured according to the method described in the examples.

[0061] [Printed Wiring Board] The printed wiring board of this embodiment is a printed wiring board having a metal-clad laminate. The printed wiring board of this embodiment may also be a multilayer printed wiring board having a metal-clad laminate. In this specification, when simply referred to as a printed wiring board, multilayer printed wiring boards are also included. The printed wiring board of this embodiment does not necessarily have to include the metal-clad laminate of this embodiment as is; for example, it may include a metal-clad laminate that has undergone circuit formation processing such as drilling, metal plating, or etching of metal foil. The printed wiring board of this embodiment can be manufactured by using the metal-clad laminate of this embodiment and performing circuit formation processing such as drilling, metal plating, or etching of metal foil using known methods, and further performing multilayer processing as necessary.

[0062] [Semiconductor Package] The semiconductor package of this embodiment includes the printed circuit board of this embodiment and semiconductor elements. In other words, the semiconductor package of this embodiment is made by mounting semiconductor elements on the printed circuit board of this embodiment. The semiconductor package of this embodiment can be manufactured, for example, by mounting semiconductor elements such as semiconductor chips and memory at predetermined positions on the printed circuit board of this embodiment by known methods, and sealing the semiconductor elements with a sealing resin or the like.

[0063] The embodiment will be described in detail below with reference to examples. However, this embodiment is not limited to the following examples.

[0064] The weight-average molecular weight (Mw) was measured using the following procedure. (Method for measuring weight-average molecular weight (Mw)) It was calculated from a calibration curve using standard polystyrene by gel permeation chromatography (GPC). The calibration curve was approximated by a cubic equation using standard polystyrene: PStQuick Kit L (Type; A-500, A-1000, A-2500, A-5000, F-2, F-4, F-20, F-40, Mw = 266 to 427,000) [manufactured by Tosoh Corporation, product name]. The GPC measurement conditions are shown below. Instrument: High-speed GPC instrument HLC-8420GPC EcoSEC Elite(R) Columns: Guard column; "TSKgel Guardcolumn SuperHZ-L" + Columns; "TSKgel SuperHZ4000" + "TSKgel SuperHZ2500" + "TSKgel SuperHZ2000" + "TSKgel SuperHZ1000" (all manufactured by Tosoh Corporation, product names) Column size: 4.6 x 20 mm (guard column), 4.6 x 150 mm (column) Eluent: Tetrahydrofuran Sample concentration: 5 mg / 5 mL Injection volume: 2 μL Flow rate: 1.00 mL / min Measurement temperature: 40°C

[0065] [Production Example 1: Production of Modified Bismaleimide Compound 1] (1-1; Synthesis of 1,3-bis(4-maleimidophenoxy)benzene) 100 parts by mass of 1,3-bis(4-aminophenoxybenzene) was dissolved in 550 parts by mass of acetone, and then cooled to below 10°C in an ice bath. Next, 135 parts by mass of maleic anhydride was added to the resulting mixture while stirring, and the mixture was stirred at 25°C for 2 hours to allow it to react. The solid was filtered off from the resulting reaction mixture, and the obtained solid was dried in a vacuum dryer at 80°C for 1 hour to obtain 167 parts by mass of the following intermediate (1). Next, 100 parts by mass of intermediate (1), 440 parts by mass of acetic anhydride, and 33.6 parts by mass of sodium acetate were charged into a reactor and reacted by stirring at 90°C for 2 hours. The resulting reaction mixture was poured into cooling water, and the resulting solid was filtered off. The filtered solid was washed with 500 parts by mass of alkaline water, then with 500 parts by mass of pure water, and filtered again to recover it. The solid thus obtained was dried at 85°C for 3 hours to form the following structural formula 80 parts by mass of 1,3-bis(4-maleimidophenoxy)benzene represented by the formula were obtained. (1-2; Preparation of Modified Bismaleimide Compound 1) 150 parts by mass of propylene glycol monomethyl ether was charged into a 2 L reaction vessel that could be heated and cooled, equipped with a thermometer, a stirrer, and a moisture meter with a reflux condenser. 70 parts by mass of 1,3-bis(4-maleimidophenoxy)benzene obtained by the above method were added and dissolved by stirring at 110°C. Then, 30 parts by mass of polydimethylsiloxane modified with amines at both ends (average functional group equivalent of amino groups: 745 g / mol) were added and the mixture was reacted at 120°C for 3 hours to prepare a solution containing Modified Bismaleimide Compound 1. The weight-average molecular weight (Mw) of the obtained compound was 5,048. As shown in Figure 1, 1,3-bis(4-maleimidephenoxy)benzene, which was used as a raw material, has a structure in which molecules can easily stack. Therefore, it is thought that modified bismaleimide compound 1 also has a structure in which molecules can easily stack.

[0066] [Production Example 2: Production of Modified Bismaleimide Compound 2 (for Comparative Example)] In Production Example 1, instead of 1,3-bis(4-maleimidephenoxy)benzene, the following structural formula A modified bismaleimide compound 2-containing solution was prepared by performing the same procedure except that 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane, represented by , was used. The weight-average molecular weight (Mw) of the obtained compound was 5,484. As shown in Figure 2, 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane, used as a raw material, is significantly bent around the isopropylidene group, and other molecules can enter the resulting space from the ends, so it is thought to have a structure that makes it difficult for molecules to stack. Therefore, it is thought that modified bismaleimide compound 2 also has a structure that makes it difficult for molecules to stack.

[0067] Example 1 and Comparative Example 1 (I. Preparation of Resin Varnish) Each component shown in Table 1 was blended in the amounts shown in Table 1 (the units of blending amounts in Table 1 are parts by mass. In the case of a solution or dispersion, the units are parts by mass on a solid content basis) and mixed in methyl isobutyl ketone to obtain a resin varnish with a non-volatile content concentration (solid content concentration) of 56% by mass. (II. Preparation of Prepreg) The prepared resin varnish was mixed with glass cloth (S glass, thickness: 98 μm, basis weight: 114 g / m²). ２ After impregnation, the material was heated at 120°C for 3 minutes and dried to obtain a prepreg. (III. Preparation of double-sided copper-clad laminates) Seven layers of the prepreg were stacked, and 12 μm thick electrolytic copper foil "3EC-M3-VLP-12" (manufactured by Mitsui Mining & Smelting Co., Ltd., product name) was placed on both sides so that the M side (matte side) was facing the prepreg. A double-sided copper-clad laminate was prepared by heating and pressurizing under reduced pressure of less than 100 hPa at 240°C for 85 minutes under press conditions of 3 MPa.

[0068] [Measurement and Evaluation Methods] Using the double-sided copper-clad laminates obtained in the above examples and comparative examples, each measurement or evaluation was performed according to the following method. The results are shown in Table 1.

[0069] (1. Method for measuring linear expansion coefficient) The copper foil was removed from the double-sided copper-clad laminates obtained in each example by immersion in a 10% by mass solution of ammonium persulfate (manufactured by Mitsubishi Gas Chemical Company, Inc.), which is a copper etching solution. The resulting copper-free laminates were cut to a width of 5 mm and a length of 5 mm, and dried at 105°C for 30 minutes to be used as test specimens. The test specimens were stood upright with the vertical threads in the vertical direction, and a quartz probe with a diameter of 2 mm was inserted. Next, a thermomechanical measuring device (TMA) (manufactured by TA Instruments Inc., product name "TMA450EM") was used to measure the dimensional change by heating in compression mode, temperature range of 25 to 260°C, heating rate of 10°C / min, and load of 0.1 N (1st cycle), then cooling to 25°C, and heating again under the same conditions (2nd cycle). In the 2nd cycle, the average value of the dimensional change per unit temperature between 220 and 260°C was taken as the linear expansion coefficient (thermal expansion coefficient). The smaller the coefficient of linear expansion, the better the low thermal expansion performance.

[0070] (2. Method for Evaluating Heat Resistance) A copper-free laminate, from which the copper foil was etched off in the same manner as in "1. Method for Measuring the Coefficient of Linear Expansion," was cut to a width of 1 mm and a length of 30 mm, and then dried at 105°C for 30 minutes to prepare a test specimen. Both ends of the long side of the test specimen were clamped with upper and lower grips (grip spacing: 20 mm). Next, using a dynamic viscoelasticity analyzer (DMA), the specimen was loaded in tensile mode, temperature range 40 to 400°C, heating rate 10°C / min, frequency 10 Hz, and strain 3 μm (constant) to determine the temperature at which the maximum value of tanδ, the ratio of loss modulus to storage modulus, was obtained, and this temperature was defined as the glass transition temperature. The higher the glass transition temperature, the better the heat resistance.

[0071]

[0072] The details of each component shown in Table 1 are as follows: [Component (A)] ・Bismaleimide compound 1: Modified bismaleimide compound 1 obtained in Production Example 1 ・Bismaleimide compound 2: Modified bismaleimide compound 2 obtained in Production Example 2 [Component (B)] ・Silica: Spherical fused silica, average particle size 0.5 μm [Component (C)] ・Curing accelerator: Isocyanate macimidazole compound, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name "G-8009L"

[0073] As can be seen from Table 1, the copper-clad laminate of this embodiment manufactured in Example 1 showed improved low thermal expansion compared to the copper-clad laminate manufactured in Comparative Example 1. It also exhibited superior heat resistance.

[0074] Reference Examples 1-2 and Comparative Reference Example 1: For the bismaleimide compounds used as raw materials in Example 1 and Comparative Example 1, the molecular cohesive energy density was investigated by simulation under the following conditions, and the linear expansion coefficient of component (A) itself was investigated (Reference Example 1 and Comparative Reference Example 1, respectively). Furthermore, in order to confirm that the effect of improving low thermal expansion demonstrated in Example 1 is also observed when other components (A) are used, the molecular cohesive energy density was investigated by simulation in the same manner as above, and the linear expansion coefficient of component (A) itself was investigated (Reference Example 2). The results are shown in Table 2.

[0075] (Bismaleimide compounds used in the simulation)

[0076] (Simulation Conditions) Molecular dynamics software "LAMMPS" (Sandia Corporation) was used to simulate the motion of 100 randomly arranged molecules using GAFF (General Amber Force Field) as the interaction potential energy. During the equilibrium process, an NPT ensemble with a constant number of molecules, pressure, and temperature was used, with a pressure of 1 atm (0.1 MPa) and a temperature of 300 K, and the molecules were allowed to interact for 0.1 nanoseconds. The volume of this final equilibrium-equipped simulation cell was then used for simulations to acquire physical properties. In the simulations to acquire physical properties, physical properties were collected for 2 nanoseconds under an NVT ensemble with a constant number of molecules, volume, and temperature, and the average value against the simulation time was obtained. Here, the volume of the simulation cell was 59 nm in Reference Example 1. ３ Reference example 2 shows 58 nm ３ In comparative example 1, 80 nm ３In each of the reference examples and comparative reference examples, simulations were performed for five different initial arrangements of the 100 molecules, and the physical properties (cohesive energy density and linear expansion coefficient) described below were taken as the average values ​​of these five patterns. The cohesive energy density was defined as the sum of the potential energies acting between molecules divided by the volume of the simulation cell, and the cohesive energy density was calculated when the 100 molecules were assembled. When the cohesive energy density is large and negative, it can be interpreted as a large attractive interaction between molecules, i.e., a high stacking ability. Furthermore, to simulate the bismaleimide compound becoming a cured product, the linear expansion coefficient was simulated in a state where polymerized decamers were assembled (Reference Examples 1 and 2: 27 polymers, Comparative Reference Example 1: 20 polymers).

[0077]

[0078] As can be seen from the comparison between Reference Examples 1-2 and Reference Comparative Example 1 in Table 2, the bismaleimide compounds used in Reference Examples 1-2 have a larger negative molecular aggregation energy density than the bismaleimide compound used in Comparative Reference Example 1. Therefore, it is inferred that the bismaleimide compounds used in Reference Examples 1-2 have a superior stacking effect.

Claims

1. A prepreg comprising a resin composition or a semi-cured product of the resin composition, wherein the resin composition contains (A) a bismaleimide compound, and the (A) bismaleimide compound has nitrogen atoms in two maleimide groups bonded by an organic group, and the organic group has three aromatic hydrocarbon groups.

2. The prepreg according to claim 1, wherein the aromatic hydrocarbon group of the (A) bismaleimide compound is a group selected from the following group. (R ａ１ ~R ａ８ each independently represents an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, an alkoxyl group having 1 to 10 carbon atoms, or a halogen atom. n ａ１ is an integer from 0 to 4, n ａ２ and n ａ３ each independently is an integer from 0 to 3, n ａ４ is an integer from 0 to 2, n ａ５ is an integer from 0 to 4, n ａ６ is an integer from 0 to 3, n ａ７ is an integer from 0 to 2, n ａ８ is 0 or 1. * indicates the bonding site.) 3. The prepreg according to claim 1, wherein the linking group that connects the aromatic hydrocarbon groups of the (A) bismaleimide compound is a linking group selected from the group consisting of ether groups and alkylene groups having 1 to 5 carbon atoms.

4. The prepreg according to claim 1, wherein the (A) bismaleimide compound comprises a modified form of one or more compounds selected from the group consisting of monoamine compounds and diamine compounds.

5. The prepreg according to claim 4, wherein the diamine compound is one or more selected from the group consisting of aromatic diamine compounds having two amino groups directly bonded to an aromatic ring and siloxanediamine compounds having two primary amino groups.

6. The prepreg according to claim 1, wherein the resin composition further contains (B) an inorganic filler.

7. The prepreg according to claim 1, wherein the resin composition further contains (C) a curing accelerator.

8. A metal-clad laminate comprising a metal foil and a laminate containing a cured prepreg according to claim 1.

9. A printed circuit board having a metal-clad laminate as described in claim 8.

10. A semiconductor package having a printed circuit board as described in claim 9.

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