Method for manufacturing multilayer substrate and curable resin composition for manufacturing multilayer substrate

Abstract

Disclosed is a method for manufacturing a multilayer substrate, the method including: a first step for forming a first insulating resin layer that contains a maleimide resin on a base material; a second step for forming a second insulating resin layer; and a third step for collectively curing at least the first insulating resin layer and the second insulating resin layer.

Description

Method for manufacturing multilayer substrate and curable resin composition for manufacturing multilayer substrate

[0001] The present disclosure relates to a method for producing a multilayer substrate and a curable resin composition for producing a multilayer substrate.

[0002] In recent years, with the increasing sophistication of semiconductor applications, the logic semiconductors, AI semiconductors, advanced SoCs (System on Chip) and the like used therein have also been seeing progress in the high integration of semiconductor packages through the application of techniques such as SiPs (System in Package), chiplets, heterogeneous integration, etc. Specifically, as the number of processor cores increases for the purpose of high-speed signal transmission and improved arithmetic processing, studies are being conducted to improve performance through structural innovations such as finer wiring, higher density, larger substrates, and more multi-layered structures using semiconductor chips, package substrates, redistribution layers (RDLs), and interposers. Furthermore, cutting-edge semiconductor packages tend to integrate a wide variety of functions, such as analog circuits and radio frequency (RF) circuits. In addition, with the convergence of photonics and electronics, the addition of optical wiring, optical engines, and I / O interfaces (optical-electrical conversion units) is expected, so further improvements in the electrical properties of the insulating resin layers and adhesive layers used therein are required.

[0003] In Patent Document 1, a circuit layer is formed by laminating an insulating resin layer containing epoxy resin onto an insulating substrate equipped with a circuit and subjecting it to a heat curing treatment, and then forming a circuit on the insulating resin layer. Similar processes are further repeated to stack the circuit layers and produce a multilayer wiring board.

[0004] JP 2013-038140 A

[0005] In conventional methods for manufacturing multilayer wiring boards using an epoxy resin for the insulating resin layer, it was necessary to laminate and heat-cure the insulating resin layer for each layer, leaving room for improvement in terms of manufacturing efficiency.

[0006] Furthermore, in order to further improve the quality of signal transmission, it has been desired to form an insulating resin layer having low dielectric properties.

[0007] The present disclosure has been made in view of the above problems, and aims to provide a method for manufacturing a multilayer substrate, which can manufacture a multilayer substrate having an insulating resin layer with good dielectric properties and can improve manufacturing efficiency, and a curable resin composition for manufacturing a multilayer substrate.

[0008] In order to solve the above problems, the present disclosure provides the following method for producing a multilayer substrate and a curable resin composition for producing a multilayer substrate.

[0009] [1] A method for manufacturing a multilayer substrate, comprising: a first step of forming a first insulating resin layer containing a maleimide resin on a substrate; a second step of forming a second insulating resin layer; and a third step of simultaneously curing at least the first and second insulating resin layers. [2] The manufacturing method according to [1], further comprising, after the second step and before the third step, a step of forming one or more other insulating resin layers, wherein all insulating resin layers except the second insulating resin layer and the insulating resin layer formed last among the one or more other insulating resin layers contain a maleimide resin, and the third step is a step of simultaneously curing the first insulating resin layer, the second insulating resin layer, and the one or more other insulating resin layers. [3] The manufacturing method according to [1] or [2], further comprising, after the first step and before the second step, a step of forming a circuit on the first insulating resin layer. [4] A curable resin composition for manufacturing a multilayer substrate, containing a maleimide resin.

[0010] According to the present disclosure, it is possible to provide a method for manufacturing a multilayer substrate that can manufacture a multilayer substrate having an insulating resin layer with good dielectric properties and improve manufacturing efficiency, and a curable resin composition for manufacturing a multilayer substrate.

[0011] Fig. 1 is a flow diagram for explaining one embodiment of a method for manufacturing a multilayer substrate according to the present embodiment; Fig. 2 is a schematic cross-sectional view showing an example of a multilayer substrate manufactured by the method for manufacturing a multilayer substrate according to the present embodiment; Fig. 3 is a schematic cross-sectional view showing an example of a multilayer substrate manufactured by the method for manufacturing a multilayer substrate according to the present embodiment; Fig. 4 is a schematic cross-sectional view showing an example of a multilayer substrate manufactured by the method for manufacturing a multilayer substrate according to the present embodiment;

[0012] Hereinafter, several embodiments of the present disclosure will be described in detail, but the present disclosure is not limited to the following embodiments.

[0013] In this specification, numerical ranges indicated using "to" indicate ranges that include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range may be replaced with the upper or lower limit of another numerical range. Furthermore, in numerical ranges described in this specification, the upper or lower limit of that numerical range may be replaced with a value shown in the Examples. When referring to the amount of each component in a composition in this specification, if multiple substances corresponding to each component are present in the composition, unless otherwise specified, this refers to the total amount of those multiple substances present in the composition. "A or B" may contain either A or B, or both. "Solid content" refers to the non-volatile content of a resin composition excluding volatile substances (water, solvent, etc.). In other words, "solid content" refers to components other than the solvent that remain without volatilizing during drying of the resin composition, as described below, and also includes components that are liquid, syrup-like, or waxy at room temperature (25°C). In this specification, for example, "(meth)acrylic" means "acrylic" and its corresponding "methacrylic", and the same applies to other similar terms.

[0014] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. However, the present disclosure is not limited to the following embodiments.

[0015] [Method for Manufacturing a Multilayer Substrate] The method for manufacturing a multilayer substrate according to this embodiment includes a first step of forming a first insulating resin layer containing a maleimide resin on a substrate, a second step of forming a second insulating resin layer, and a third step of simultaneously curing at least the first and second insulating resin layers. Compared to insulating resin layers that do not contain maleimide resin, insulating resin layers containing maleimide resin are easier to process circuits in even before the resin layers are fully cured (e.g., in a B-stage state), eliminating the need for a curing step each time an insulating resin layer is laminated, as in the past. Therefore, according to the method for manufacturing a multilayer substrate according to this embodiment, multiple insulating resin layers (at least the first and second insulating resin layers) can be laminated in an uncured state and then simultaneously cured (fully cured), thereby reducing the number of curing steps compared to conventional methods for manufacturing a multilayer substrate and improving manufacturing efficiency. Furthermore, insulating resin layers containing maleimide resin have excellent dielectric properties. Therefore, the method for manufacturing a multilayer substrate according to this embodiment allows the manufacture of a multilayer substrate having insulating resin layers with excellent dielectric properties. Furthermore, since an insulating resin layer containing maleimide resin is less prone to warping, a multilayer substrate including such a layer tends to have excellent mechanical strength.

[0016] 1 is a flow diagram illustrating one embodiment of a method for manufacturing a multilayer substrate according to the present disclosure. As shown in FIG. 1 , one embodiment of the method for manufacturing a multilayer substrate according to the present disclosure includes a step of forming a first insulating resin layer on a substrate (first step), a step of forming a circuit on the first insulating resin layer, a step of forming a second insulating resin layer (second step), a step of forming a circuit on the second insulating resin layer, a build-up step of forming one or more insulating resin layers other than the first insulating resin layer and the second insulating resin layer, and a step of collectively curing the insulating resin layers including the first insulating resin layer and the second insulating resin layer (the first insulating resin layer, the second insulating resin layer, and one or more other insulating resin layers) (third step). In the second step, the second insulating resin layer may be formed on the first insulating resin layer. In the embodiment shown in FIG. 1, a process of forming a circuit in the first insulating resin layer, a process of forming a circuit in the second insulating resin layer, and a build-up process are included, but these processes are optional processes and may or may not be included in the embodiments of the method for manufacturing a multilayer substrate according to the present disclosure.

[0017] In the method for manufacturing a multilayer substrate according to the present disclosure, each insulating resin layer formed in the first step, the second step, and the build-up step may be in the form of a resin-coated copper foil (RCC). When the insulating resin layer is formed in the form of an RCC, the thickness of the copper foil in the RCC is not particularly limited and may be 1 μm or more and 100 μm or less. The thickness of the resin layer in the RCC is also not particularly limited and may be 1 μm or more and 50 μm or less.

[0018] (First Step) In the first step, a first insulating resin layer containing a maleimide resin is formed on a substrate.

[0019] In the method for manufacturing a multilayer substrate according to this embodiment, the material of the substrate is not particularly limited. Examples of the substrate material include inorganic materials such as semiconductors, glass, ceramics, low temperature co-fired ceramics (LTCC), and high temperature co-fired ceramics (HTCC); metals such as aluminum and copper; magnetic materials such as pure iron, Fe—Si alloys, Fe—Al alloys, permalloy, sendust, permendur, soft ferrite, amorphous magnetic alloys, and nanocrystalline magnetic alloys; organic materials such as polyethylene terephthalate, polycarbonate, polyimide, polyphenylene ether, polyphenylene sulfide, polyether ether ketone, polytetrafluoroethylene (PTFE), liquid crystal polymers (LCPs), (meth)acrylic resins, cyclic olefin resins, and epoxy resins; and composites of glass and epoxy resins. The substrate may be a plastic substrate. The substrate may have holes. The substrate may have a coating layer formed thereon that covers the surface of the substrate (including the surfaces of the holes, if any). The coating layer according to this embodiment encompasses a structure having a shape formed on the entire surface of the substrate when observed in a plan view, as well as a structure having a shape formed on a part of the substrate.

[0020] In the method for manufacturing a multilayer substrate according to this embodiment, the substrate may be a glass substrate, and the first insulating resin layer may be formed so as to be in direct contact with the glass substrate. Conventional insulating resin layers that do not contain maleimide resin do not provide sufficient adhesion to the glass substrate, and it was necessary to form the insulating resin layer on the glass substrate via a bonding sheet or primer layer. In contrast, the first insulating resin layer, which contains maleimide resin, can provide good adhesion to the glass substrate and can be formed directly on the glass substrate without a bonding sheet or primer layer. In this case, the bonding sheet or primer layer is not required, thereby further improving manufacturing efficiency.

[0021] The coating layer that covers the surface of the glass substrate (including the surfaces of the holes, if any) may be a conductor layer. The conductor layer may be a circuit. A circuit may be formed on the glass substrate. A glass substrate on which a circuit has been formed in advance may be used, or a glass substrate on which no circuit has been formed may be prepared and a circuit may be formed on it. The method for forming a circuit on the glass substrate is not particularly limited, and a circuit may be formed directly on the glass substrate by plating or sputtering.

[0022] The thickness of the substrate is not particularly limited, but may be 25 μm or more and 1000 μm or less.

[0023] A through electrode may be formed on the substrate. The through electrode may be formed, for example, by at least partially filling a hole with a conductor, or by coating the surface of the hole with a conductor. The through electrode may be formed, for example, from copper or silver. The size of the through electrode is not particularly limited, and may be, for example, from 5 μm to 200 μm in diameter.

[0024] The substrate may have an electronic component built in. For example, examples of electronic components built in a glass substrate include semiconductor chips, capacitors, inductors, resistors, diodes, and transistors. One method for building an electronic component in a glass substrate is to form a cavity in the glass substrate and place the electronic component in the cavity. However, a substrate with an electronic component built in may also be produced by a method other than this.

[0025] The first insulating resin layer is formed from a curable resin composition containing a maleimide resin. The method for forming the first insulating resin layer is not particularly limited, but from the viewpoint of further improving production efficiency, the first insulating resin layer may be formed by laminating the curable resin composition containing a maleimide resin as a resin film on a substrate.

[0026] The first insulating resin layer may be formed by applying a curable resin composition to a substrate and then semi-curing the composition. Examples of methods for applying the curable resin composition include methods using a spin coater, a slit coater, or the like. Examples of methods for semi-curing the curable resin composition include drying at 60 to 150°C for 1 to 120 minutes, followed by heating at 150 to 260°C for 0.5 to 60 minutes or exposing the composition to an exposure dose of 100 to 1000 mJ / cm. ２ In one example, the curable resin composition is semi-cured by irradiating the curable resin composition with ultraviolet light.

[0027] The maleimide resin (hereinafter also referred to as "component (A)") can be obtained, for example, by reacting a tetracarboxylic dianhydride (a1) (hereinafter also referred to as "component (a1)"), an amine (a2) (hereinafter also referred to as "component (a2)"), and maleic anhydride (a3) ​​(hereinafter also referred to as "component (a3)"). Here, the component (a2) may contain dimer diamine. The component (A) can be used alone or in combination of two or more types.

[0028] The tetracarboxylic dianhydride of component (a1) can be any known polyimide raw material. Examples of component (a1) include pyromellitic anhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)naphtho[1,2-c]furan-1,3-dione, 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfone ... ,3',4,4'-benzophenonetetracarboxylic dianhydride, 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, bicyclo[2.2.2]oct-7-ene- 2,3,5,6-tetracarboxylic dianhydride, bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid) 1,4-phenylene, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 4,4'-(ethyne-1,2-diyl)diphthalic anhydride, 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, dicyclohexyl-3,4,3',4'-tetracarbo diphthalic anhydride, 3,4'-oxydiphthalic anhydride, 3,4'-biphthalic anhydride, norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic dianhydride, 5,5'-bis-2-norbornene-5,5',6,6'-tetracarboxylic-5,5',6,6'-dianhydride, and 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride.Among these, from the viewpoint of availability, pyromellitic anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, and 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride are preferred, and from the viewpoint of heat resistance, pyromellitic anhydride is particularly preferred. The component (a1) can be used alone or in combination of two or more.

[0029] The (a2) component may contain dimer diamine. As described in, for example, JP-A-9-12712, dimer diamine is a compound derived from a dimer acid, which is a dimer of an unsaturated fatty acid such as oleic acid. By using dimer diamine as the (a2) component, the dielectric properties of the cured product can be reduced. In this embodiment, any known dimer diamine can be used without particular limitation. The dimer diamine preferably includes, for example, at least one of a compound represented by the following general formula (1) and a compound represented by the following general formula (2):

[0030]

[0031] In formulas (1) and (2), m, n, p, and q each represent an integer of 1 or greater selected so that m+n=6 to 17 and p+q=8 to 19, and the bond shown by a dashed line represents a carbon-carbon single bond or a carbon-carbon double bond. However, when the bond shown by a dashed line is a carbon-carbon double bond, formulas (1) and (2) have a structure in which the number of hydrogen atoms bonded to each carbon atom constituting the carbon-carbon double bond is reduced by one from the number shown in formulas (1) and (2).

[0032] The dimer diamine may be one represented by the above general formula (2), particularly a compound represented by the following formula (3), from the viewpoints of solubility in organic solvents, heat resistance, heat-resistant adhesion, low viscosity, etc.

[0033]

[0034] Commercially available dimer diamine products include, for example, PRIAMINE 1075 and PRIAMINE 1074 (both manufactured by Cargill Japan LLC).

[0035] The component (a2) may contain an amine other than dimer diamine (hereinafter also referred to as "second amine"). The second amine is an amine that does not fall under the category of the above-mentioned dimer diamine. The second amine may be a diamine or triamine, or may be a diamine. By using an alicyclic diamine as the second amine, the dielectric constant can be further reduced. By using an aromatic diamine as the second amine, the elastic modulus and Tg of the cured product can be increased, and the CTE can be reduced.

[0036] When the second amine is a diamine, examples of the diamine include 1,3-diaminopropane, norbornanediamine, 4,4-methylenedianiline, 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene, 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 9,9-bis(4-aminophenyl)fluorene, 9,9-bis[3-fluoro-4-aminophenyl]fluorene, 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, bis(aminomethyl)norbornane, 4,4'-(hexafluoroisopropylidene)dianiline, 3(4),8(9)-bis(aminomethyl)tricyclo[5.2.1.0 ２，６]decane, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, isophoronediamine, 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(2-methylcyclohexylamine), 1,1-bis(4-aminophenyl)cyclohexane, 2,7-diaminofluorene, 4,4'-ethylenedianiline, 4,4'-methylenebis(2,6-diethylaniline), 4,4'-methylenebis(2-ethyl-6-methylaniline), 2,2-bis[4-(4-aminophenoxy)phenyl]propane, bis[4-(4-aminophenoxy)phenyl]methane, 4,4'-bis(4-aminophenoxy)biphenyl , bis[4-(4-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ketone, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 2,2'-dimethylbiphenyl-4,4'-diamine, (4,4'-diamino)diphenyl ether, (3,3'-diamino)diphenyl ether, paraphenylenediamine, orthophenylenediamine, metaphenylenediamine, 2,2'-dimethylbiphenyl-4,4'-diamine, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, etc. These can be used alone or in combination of two or more.

[0037] When the second amine is a triamine, examples of the triamine include tris(aminomethyl)amine, tris(2-aminoethyl)amine, tris(2-aminopropyl)amine, 2-(aminomethyl)-2-methyl-1,3-propanediamine, trimer triamine, 3,4,4'-triaminodiphenyl ether, 1,2,4-triaminobenzene, 1,3,5-triaminobenzene, 1,2,3-triaminobenzene, 1,3,5-triazine-2,4,6-triamine, 2,4,6-triaminopyrimidine, 1,3,5-tris(4-aminophenyl)benzene, and 1,3,5-tris(4-aminophenoxy)benzene. Among these, from the viewpoint of photocurability, aliphatic amines and alicyclic amines are preferred, and norbornanediamine, isophoronediamine, and tris(2-aminoethyl)amine are more preferred. These may be used alone or in combination of two or more.

[0038] The second amine may include one or both of the above-mentioned diamines and triamines, or may include an amine other than the diamines and triamines.

[0039] In component (a2), the molar ratio of the second amine to the total amount of amines (moles of second amine / (moles of dimer diamine+moles of second amine)) may be 0.70 or less, 0.50 or less, or 0.30 or less. When this ratio is 0.70 or less, the dielectric properties of the cured product can be further reduced.

[0040] When the second amine contains a diamine, the molar ratio of the diamine in the second amine to the total amount of diamine in component (a2) (number of moles of diamine in the second amine / (number of moles of dimer diamine + number of moles of diamine in the second amine)) may be 0.70 or less, 0.50 or less, or 0.30 or less. When this ratio is 0.70 or less, the dielectric properties of the cured product can be further reduced.

[0041] Component (A) can be produced by various known methods. For example, components (a1) and (a2) are first subjected to a polyaddition reaction at a temperature of about 60 to 120°C, preferably 70 to 90°C, for typically about 0.1 to 2 hours, preferably 0.1 to 1.0 hour. The resulting polyaddition product is then subjected to an imidization reaction, i.e., a dehydration ring-closing reaction, at a temperature of about 80 to 250°C, preferably 100 to 200°C, for about 0.5 to 30 hours, preferably 0.5 to 10 hours. The product of the dehydration ring-closing reaction is then subjected to a maleimidization reaction, i.e., a dehydration ring-closing reaction, with component (a3) ​​at a temperature of about 60 to 250°C, preferably 80 to 200°C, for about 0.5 to 30 hours, preferably 0.5 to 10 hours, to obtain the desired component (A).

[0042] In the imidization reaction or maleimidization reaction, various known reaction catalysts, dehydrating agents, and organic solvents can be used.

[0043] Examples of the reaction catalyst include aliphatic tertiary amines such as triethylamine, aromatic tertiary amines such as dimethylaniline, heterocyclic tertiary amines such as pyridine, picoline, isoquinoline, and organic acids such as methanesulfonic acid, paratoluenesulfonic acid monohydrate, etc. Examples of the dehydrating agent include aliphatic acid anhydrides such as acetic anhydride, and aromatic acid anhydrides such as benzoic anhydride.

[0044] Examples of organic solvents used in the reaction include aromatic hydrocarbons such as benzene, toluene, xylene, mesitylene, and pseudocumene; alcoholic solvents such as methanol, ethanol, isopropyl alcohol, butanol, pentanol, hexanol, propanediol, and phenol; ketone solvents such as acetone, methyl isobutyl ketone, methyl ethyl ketone, pentanone, hexanone, cyclopentanone, cyclohexanone, isophorone, and acetophenone; cellosolves such as methyl cellosolve and ethyl cellosolve, ester solvents such as methyl acetate, ethyl acetate, butyl acetate, methyl propionate, butyl formate, and γ-butyrolactone; and ethylene glycol mono-n-butyl ether. Examples of suitable organic solvents include glycol ether solvents such as ethylene glycol mono-iso-butyl ether, ethylene glycol mono-tert-butyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol mono-iso-butyl ether, triethylene glycol monoethyl ether, triethylene glycol mono-n-butyl ether, and tetraethylene glycol mono-n-butyl ether; and nitrogen-containing compounds such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropanamide, and 3-butoxy-N,N-dimethylpropanamide. These organic solvents can be used alone or in combination of two or more. From the viewpoint of solubility, it is preferable to use a combination of toluene, xylene, mesitylene, or pseudocumene with methanol or ethanol.

[0045] Component (A) can be purified by various known methods to increase its purity. For example, first, component (A) dissolved in an organic solvent and pure water are placed in a separatory funnel. The separatory funnel is then shaken and allowed to stand. Subsequently, the aqueous layer and the organic layer are separated, and only the organic layer is recovered, thereby purifying component (A).

[0046] An example of the structure of component (A) produced by the above method is shown in general formula (4) below.

[0047] In general formula (4), each X independently represents a tetravalent organic group, each Y independently represents a divalent organic group, and a represents an integer of 1 or greater. However, at least one of the multiple Ys represents the divalent organic group derived from the dimer diamine. Furthermore, X and Y may be an aliphatic group, an organic group having an alicyclic structure, or an aromatic ring, and may contain a heteroatom.

[0048] The molecular weight of component (A) can be controlled by the number of moles of component (a1) and component (a2), and the smaller the number of moles of component (a1) is relative to the number of moles of component (a2), the smaller the molecular weight can be. For the purpose of easily achieving the effects of the present disclosure, the number of moles of component (a1) per mole of component (a2), i.e., [number of moles of component (a1)] / [number of moles of component (a2)], is usually in the range of about 0.30 to 0.95, preferably 0.50 to 0.85.

[0049] From the viewpoint of solubility in solvents and heat resistance, the molecular weight of component (A) is preferably a weight average molecular weight (Mw) of 3,000 to 40,000, more preferably 4,000 to 30,000, and even more preferably 5,000 to 28,000, or 7,000 to 27,000. A weight average molecular weight of 40,000 or less tends to provide good solubility in organic solvents, while a weight average molecular weight of 3,000 or more tends to provide a sufficient effect of improving heat resistance. Mw can be measured by gel permeation chromatography (GPC) and converted using a calibration curve of standard polystyrene.

[0050] As the maleimide resin, from the viewpoint of low dielectric properties and adhesiveness, the maleimide resin represented by the above general formula (4) is preferred, and in particular, the maleimide resin obtained by reacting dimer diamine as the component (a2) is preferred.

[0051] As the component (A), commercially available compounds can also be used. Specific examples that can be used preferably include SFR-2300MR-T (synthesized from an amine including dimer diamine, a tetracarboxylic dianhydride, and maleic anhydride) manufactured by Resonac Co., Ltd., and BMI-3000 Commercial Grade (synthesized from dimer diamine, pyromellitic dianhydride, and maleic anhydride), BMI-1500, BMI-1700, and BMI-5000 manufactured by DESIGNER MOLECULES Inc.

[0052] From the viewpoint of achieving excellent production efficiency and dielectric properties, the content of component (A) may be 60 mass % or more, 80 mass % or more, 90 mass % or more, 95 mass % or more, or 100 mass % based on the total amount of resin components in the first insulating resin layer.

[0053] The first insulating resin layer may contain other resins or crosslinking agents in addition to component (A). Examples of other resins and crosslinking agents include epoxy resins, phenolic resins, (meth)acrylic resins, (meth)acrylate monomers, vinyl monomers, and benzoxazine. The total content of the other resins and crosslinking agents may be 40% by mass or less, or may be 5% by mass or more and 20% by mass or less, based on the total amount of component (A), other resins, and crosslinking agents in the first insulating resin layer.

[0054] The resin composition forming the first insulating resin layer may contain components other than the resin component, such as a polymerization initiator, a curing accelerator, an inorganic filler, a release agent, a flame retardant, an ion trapping agent, an antioxidant, an adhesion promoter, a stress reducing agent, a colorant, and a coupling agent.

[0055] Examples of the polymerization initiator include thermal radical polymerization initiators, organic peroxide compounds, azo compounds, etc. The polymerization initiators may be used alone or in combination of two or more.

[0056] Examples of the curing accelerator include phosphine compounds, compounds having a phosphonium salt, imidazole compounds, etc. The curing accelerators may be used alone or in combination of two or more.

[0057] Inorganic fillers are added to reduce the thermal expansion coefficient of the curable resin composition and improve its moisture resistance reliability. Examples of such inorganic fillers include silicas such as fused silica, crystalline silica, and cristobalite, alumina, silicon nitride, aluminum nitride, boron nitride, titanium oxide, glass fiber, and magnesium oxide. The average particle size and shape of these inorganic fillers can be selected depending on the application. Among these, spherical alumina, spherical fused silica, and glass fiber are preferred.

[0058] Mold release agents are added to improve releasability from a mold. Examples of mold release agents include carnauba wax, rice wax, candelilla wax, polyethylene, polyethylene oxide, polypropylene, montanic acid, montan wax which is an ester compound of montanic acid with saturated alcohol, 2-(2-hydroxyethylamino)ethanol, ethylene glycol, glycerin, etc., stearic acid, stearic acid ester, and stearic acid amide.

[0059] The flame retardant is added to impart flame retardancy. Known flame retardants can be used without any particular limitation. Examples of the flame retardant include phosphazene compounds, silicone compounds, zinc molybdate-supported talc, zinc molybdate-supported zinc oxide, aluminum hydroxide, magnesium hydroxide, and molybdenum oxide.

[0060] The ion trapping agent is added to the liquid resin composition to trap ionic impurities and prevent thermal and moisture-absorbing deterioration. Any known ion trapping agent can be used, and there is no particular limitation. Examples of the ion trapping agent include hydrotalcites, bismuth hydroxide compounds, and rare earth oxides.

[0061] From the viewpoint of low dielectric properties, the content of component (A) is preferably more than 50 parts by mass, and may be 60 parts by mass or more, 80 parts by mass or more, 90 parts by mass or more, 95 parts by mass or more, or 100 parts by mass, when the total amount of the first insulating resin layer is 100 parts by mass, or may be 55 to 99 parts by mass, 60 to 96 parts by mass, 70 to 92 parts by mass, or 80 to 90 parts by mass.

[0062] The thickness of the first insulating resin layer is not particularly limited, but may be 1 μm or more and 200 μm or less.

[0063] The position where the first insulating resin layer is formed is not particularly limited as long as it is on the substrate, and the first insulating resin layer may be formed so as to be in direct contact with the substrate, or may be formed on the substrate via another layer such as an adhesive layer, a metal layer, or an insulating resin layer. The other layer may be one layer or two or more layers. From the viewpoint of further improving manufacturing efficiency, it is preferable that the first insulating resin layer be formed so as to be in direct contact with the substrate.

[0064] When the first insulating resin layer is formed on the substrate via an insulating resin layer as another layer, a circuit may be formed on the insulating resin layer. The method for forming the circuit is not particularly limited, and examples thereof include a subtractive method, a semi-additive method (SAP), a modified semi-additive method (MSAP), etc.

[0065] An insulating resin layer may be further formed on the side surface of the substrate. When an insulating resin layer is further formed on the side surface of the substrate, the insulating resin layer may be formed on a portion of the side surface of the substrate, or on the entire side surface of the substrate. The insulating resin layer formed on the side surface of the substrate may be an insulating resin layer containing maleimide resin, and may be formed integrally with the first insulating resin layer. An insulating resin layer may be further formed on the surface of the substrate opposite to the first insulating resin layer. The insulating resin layer formed on the surface of the substrate opposite to the first insulating resin layer may be formed integrally with the insulating resin layer formed on the side surface of the substrate.

[0066] When the insulating resin layer formed on the side of the substrate is formed integrally with the first insulating resin layer, and when the insulating resin layer formed on the surface of the substrate opposite the first insulating resin layer is formed integrally with the insulating resin layer formed on the side of the substrate, the substrate is covered with an insulating resin layer containing maleimide.

[0067] (First Circuit Forming Step) The method for manufacturing a multilayer substrate according to the present disclosure may further include, after the first step, a step of forming a circuit in the first insulating resin layer (hereinafter also referred to as the "first circuit forming step").

[0068] The method for forming the circuit is not particularly limited, and examples thereof include a subtractive method, a semi-additive method (SAP), a modified semi-additive method (MSAP), etc. From the viewpoint of being able to form a more highly miniaturized circuit, it is preferable to form the circuit by SAP or MSAP, and from the viewpoint of further improving production efficiency, it is preferable to form the circuit by MSAP.

[0069] (Second Step) In the second step, a second insulating resin layer is formed. In the second step, the second insulating resin layer may be formed on the surface of the first insulating resin layer opposite the substrate, or the second insulating resin layer may be formed on the surface of the substrate opposite the first insulating resin layer. When the second insulating resin layer is formed on the surface of the first insulating resin layer opposite the substrate, a further substrate may be formed between the second insulating resin layer and the first insulating resin layer. When the second insulating resin layer is formed on the surface of the substrate opposite the first insulating resin layer, a further insulating resin layer or a further substrate may be laminated between the second insulating resin layer and the substrate.

[0070] The second insulating resin layer is formed from a curable resin composition. The method for forming the second insulating resin layer is not particularly limited, but from the viewpoint of further improving production efficiency, the second insulating resin layer may be formed by laminating the curable resin composition that forms the second insulating resin layer as a resin film on the surface of the first insulating resin layer opposite to the substrate.

[0071] The curable resin composition forming the second insulating resin layer may contain a maleimide resin, or may contain one or more other resins or crosslinking agents other than maleimide resins. Examples of other resins and crosslinking agents include epoxy resins, phenolic resins, (meth)acrylic resins, and benzoxazines. From the viewpoint of achieving excellent production efficiency and dielectric properties, the curable resin composition forming the second insulating resin layer may contain a maleimide resin. Examples of maleimide resins include those similar to those listed as the maleimide resins contained in the first insulating resin layer described above.

[0072] From the viewpoint of achieving excellent production efficiency and dielectric properties, the second insulating resin layer may contain 60 mass % or more, 80 mass % or more, 90 mass % or more, 95 mass % or more, or 100 mass % of maleimide resin, based on the total amount of component (A), other resins, and crosslinking agent in the second insulating resin layer.

[0073] The second insulating resin layer may contain components other than the resin component, including the same components as those listed above as other components that may be contained in the first insulating resin layer.

[0074] From the viewpoint of low dielectric properties, the content of the resin component in the second insulating resin layer is preferably more than 50 parts by mass, and may be 55 to 99 parts by mass, 60 to 96 parts by mass, 70 to 92 parts by mass, or 80 to 90 parts by mass, when the total amount of the second insulating resin layer is 100 parts by mass.

[0075] The thickness of the second insulating resin layer may be 1 μm or more and 200 μm or less.

[0076] (Second Circuit Forming Step) The method for manufacturing a multilayer substrate according to the present disclosure may further include a step of forming a circuit in the second insulating resin layer (hereinafter also referred to as a "second circuit forming step") after the second step. The method for forming the circuit is not particularly limited, and examples thereof include the methods exemplified in the first circuit forming step described above.

[0077] When the second insulating resin layer contains a maleimide resin, the second circuit forming step may be performed before the third step, from the viewpoint of further improving manufacturing efficiency.

[0078] (Build-up Process) When the second insulating resin layer contains a maleimide resin, the method may further include, after the second process and before the third process, a process of forming one or more other insulating resin layers (hereinafter also referred to as "N insulating resin layers" or "build-up layers") on the surface of the second insulating resin layer opposite the first insulating resin layer. N represents an integer of 1 or greater. When the second insulating resin layer is formed on the surface of the first insulating resin layer opposite the substrate, a build-up layer may be formed on the surface of the second insulating resin layer opposite the first insulating resin layer. When the second insulating resin layer is formed on the surface of the substrate opposite the first insulating resin layer, a build-up layer may be formed on the surface of the second insulating resin layer opposite the substrate, or a build-up layer may be formed on the surface of the first insulating resin layer opposite the substrate. When a second insulating resin layer is formed on the surface of the substrate opposite the first insulating resin layer, a build-up layer may be formed on both the surface of the second insulating resin layer opposite the substrate and the surface of the first insulating resin layer opposite the substrate.

[0079] When N is 1, the insulating resin layer formed as a build-up layer (hereinafter also referred to as the "third insulating resin layer") may or may not contain a maleimide resin. Furthermore, the third insulating resin layer may contain a resin other than the maleimide resin or a crosslinking agent.

[0080] When N is 2, the N insulating resin layers are referred to as the third insulating resin layer and the fourth insulating resin layer in the stacking order. In this case, the third insulating resin layer contains maleimide resin. By containing maleimide resin in the third insulating resin layer, circuits can be formed in each of the first to third insulating resin layers before the curing step is performed, and after the fourth insulating resin layer is formed, the first to fourth insulating resin layers can be cured collectively. The fourth insulating resin layer may or may not contain maleimide resin. Furthermore, the third insulating resin layer and the fourth insulating resin layer may contain a resin other than maleimide resin or a crosslinking agent.

[0081] When N is 3 or greater, the N insulating resin layers are referred to in stacking order as the third insulating resin layer, ..., the (N+1)th insulating resin layer, and the (N+2)th insulating resin layer. In this case, the third to (N+1)th insulating resin layers contain maleimide resin. That is, all of the N insulating resin layers except for the (N+2)th insulating resin layer, which is formed last, contain maleimide resin. By including the third to (N+1)th insulating resin layers in the maleimide resin, circuits can be formed in each of the first to (N+1)th insulating resin layers before the curing step, and the first to (N+2)th insulating resin layers can be cured collectively after the (N+2)th insulating resin layer is formed. The (N+2)th insulating resin layer may or may not contain maleimide resin. Furthermore, the third to (N+2)th insulating resin layers may contain a resin other than maleimide resin or a crosslinking agent.

[0082] The buildup layer is formed from a curable resin composition. The method for forming the buildup layer is not particularly limited, but from the viewpoint of excellent production efficiency, the buildup layer may be formed by laminating the curable resin composition that forms the buildup layer as a resin film on the insulating resin layer that forms the buildup layer.

[0083] The curable resin composition forming the build-up layer may contain a maleimide resin, or may contain one or more other resins or crosslinking agents other than the maleimide resin. Examples of the other resins and crosslinking agents include epoxy resins, phenolic resins, (meth)acrylic resins, and benzoxazines. From the viewpoint of excellent adhesion and dielectric properties, the curable resin composition forming the build-up layer may contain a maleimide resin. Examples of the maleimide resin, other resins, and crosslinking agents include the same as those listed above as the maleimide resin, other resins, and crosslinking agents contained in the first insulating resin layer.

[0084] From the viewpoint of excellent adhesion and dielectric properties, each buildup layer may contain 60% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 100% by mass of maleimide resin, based on the total amount of maleimide resin, other resins, and crosslinking agent in each buildup layer.

[0085] The build-up layer may contain components other than the maleimide resin, other resins, and cross-linking agents, including the same components as those listed above as other components that may be contained in the first insulating resin layer.

[0086] From the viewpoint of achieving better dielectric properties, the total content of the maleimide resin, other resin, and crosslinking agent in each buildup layer, when the total amount of each buildup layer is taken as 100 parts by mass, is preferably more than 50 parts by mass, and may be 60 parts by mass or more, 80 parts by mass or more, 90 parts by mass or more, 95 parts by mass or more, or 100 parts by mass, or may be 55 to 99 parts by mass, 60 to 96 parts by mass, 70 to 92 parts by mass, or 80 to 90 parts by mass.

[0087] The thickness of each layer of the build-up layer may be 1 μm or more and 200 μm or less. The thickness of each layer of the build-up layer may be the same or different.

[0088] In the build-up process, a circuit may be formed each time an insulating resin layer is formed, or on one or more predetermined insulating resin layers. The method for forming a circuit on an insulating resin layer is not particularly limited, and examples thereof include the methods exemplified in the first circuit formation process described above.

[0089] In the build-up process, a substrate may be laminated instead of an insulating resin layer, or one or more insulating resin layers and one or more substrates may be laminated. When one or more insulating resin layers and one or more substrates are laminated in the build-up process, the order in which the insulating resin layers and the substrates are laminated is not particularly limited, and for example, they may be laminated alternately. When one or more insulating resin layers and one or more substrates are laminated in the build-up process, a laminate in which one or more insulating resin layers and one or more substrates are laminated in advance may be laminated.

[0090] (Third Step) In the third step, at least the first insulating resin layer and the second insulating resin layer are cured together (fully cured). If N insulating resin layers are formed on the second insulating resin layer in the build-up step, the first insulating resin layer, the second insulating resin layer, and the N insulating resin layer are all cured together. By performing this third step, the insulating resin layers formed in steps prior to the third step are brought into a fully cured (C-stage) state.

[0091] The curing in the third step may be thermal curing or photocuring. The heat treatment temperature and time in the third step may be appropriately adjusted, and may be, for example, heat treatment at 150 to 250°C for about 5 to 240 minutes.

[0092] (Other Steps) In the method for manufacturing a multilayer substrate according to this embodiment, a build-up step may be further performed after the third step. That is, in the method for manufacturing a multilayer substrate according to this embodiment, the build-up step may be performed only before the third step, only after the third step, or both before and after the third step. The build-up step performed after the third step is not particularly limited. As with the build-up step performed before the third step described above, all insulating resin layers other than the insulating resin layer formed last may be layers containing maleimide resin, and multiple insulating resin layers may be cured collectively or each insulating resin layer may be cured one by one. The build-up step performed after the third step may be repeated multiple times. Even in the build-up step performed after the third step, when one or more insulating resin layers and one or more base layers are laminated, a laminate in which one or more insulating resin layers and one or more base layers are previously laminated may be laminated.

[0093] The method for manufacturing a multilayer substrate according to this embodiment may include, after the third step, a step of further laminating a substrate on the insulating resin layer formed last (hereinafter also referred to as a "substrate laminating step"). Examples of substrates to be laminated in the substrate laminating step include those similar to the substrate on which the above-described first insulating resin layer is formed.

[0094] After the substrate laminating step, any one or a combination of two or more of the following steps may be further performed as necessary: ​​the first step, the first circuit forming step, the second step, the second circuit forming step, the build-up step, the third step, and the substrate laminating step. This allows, for example, the manufacture of a multilayer substrate in which a plurality of substrates and a plurality of insulating resin layers are alternately laminated.

[0095] 2 is a schematic cross-sectional view showing an example of a multilayer substrate manufactured by the manufacturing method of a multilayer substrate according to this embodiment. The multilayer substrate 100 includes a first insulating resin layer 11 containing a maleimide resin on a substrate 10, and a second insulating resin layer 12 on the surface of the first insulating resin layer 11 opposite the substrate 10. Although not shown in FIG. 2 , a through electrode may be formed in the substrate 10, and circuits may be formed in the first insulating resin layer 11 and the second insulating resin layer 12. The multilayer substrate 100 may be electrically connected to semiconductor chips such as logic semiconductors (CPUs, GPUs, SoCs, etc.), memory semiconductors (SRAMs, DRAMs, HBMs, etc.), analog semiconductors (analog ICs, RFICs, I / O devices, etc.), and power semiconductors (power amplifiers, etc.).

[0096] 3 is a schematic cross-sectional view showing an example of a multilayer substrate manufactured by the manufacturing method of a multilayer substrate according to this embodiment. The multilayer substrate 200 includes a base material 20, first insulating resin layers 21a and 21b, second insulating resin layers 22a and 22b provided on the surfaces of the first insulating resin layers 21a and 21b opposite the base material 20, and insulating resin layers 23a, 23b, 23c, and 23d (build-up layers 23a, 23b, 23c, and 23d) provided on the surfaces of the second insulating resin layers 22a and 22b opposite the first insulating resin layers 21a and 21b. The second insulating resin layers 22a and 22b of the multilayer substrate 200 may be formed in the same process or in different processes. For example, after the first insulating resin layer 21a, the second insulating resin layer 22a, the buildup layer 23a, and the buildup layer 23b are cured all at once, the first insulating resin layer 21b, the second insulating resin layer 22b, the buildup layer 23c, and the buildup layer 23d may be formed on the surface of the base material 20 opposite to the first insulating resin layer 21a. Note that, although Fig. 3 shows two buildup layers formed on the top and bottom of the base material 20, the number of buildup layers is not limited to this. Furthermore, at least one of the first insulating resin layers 21a and 21b may be a layer that does not contain maleimide resin (an insulating resin layer that does not fall under the category of the first insulating resin layer).

[0097] Through electrodes 24a, 24b, 24c, and 24d are formed in the base material 20. A circuit 25 is formed in each insulating resin layer, and bumps 26 are formed on one surface of the multilayer substrate 200 for electrically connecting the circuit 25 of the multilayer substrate 200 to a package substrate, a motherboard, or the like (not shown). Electrical connection to a semiconductor chip or the like (not shown) is made by a method such as a ball grid array (BGA), microbumps, bumpless Cu-Cu bonding, or hybrid bonding (Cu-Cu direct bonding).

[0098] The bumps electrically connect the multilayer substrate to the semiconductor chip, the multilayer substrate to the interposer, and the multilayer substrate to the motherboard. Examples of materials for forming the bumps include conductors such as solder.

[0099] FIG. 4 is a schematic cross-sectional view showing an example of a multilayer substrate manufactured by the manufacturing method of a multilayer substrate according to this embodiment. Multilayer substrate 300 includes base materials 30a and 30b and insulating resin layers 38a, 38b, and 38c stacked alternately. In multilayer substrate 300 shown in FIG. 4, one of insulating resin layers 38a, 38b, and 38c is a first insulating resin layer, and another of insulating resin layers 38a, 38b, and 38c is a second insulating resin layer. At least the first insulating resin layer and the second insulating resin layer are cured together. The remaining layer is not particularly limited and may be cured together with the first insulating resin layer and the second insulating resin layer, or may be cured separately from the first insulating resin layer and the second insulating resin layer. However, from the viewpoint of improving manufacturing efficiency, it is preferable that insulating resin layers 38a, 38b, and 38c are all cured together. Although not shown in Fig. 4, through electrodes may be formed in the base materials 30a and 30b, circuits may be formed in the insulating resin layers 38a, 38b, and 38c, and the multilayer substrate 300 may be electrically connected to a semiconductor chip. Although Fig. 4 shows a two-layer base material, the number of layers of the base material is not limited to this.

[0100] [Curable Resin Composition for Manufacturing Multilayer Substrate] The curable resin composition for manufacturing a multilayer substrate according to this embodiment contains a maleimide resin. Examples of the maleimide resin include the maleimide resins described above. Because the curable resin composition for manufacturing a multilayer substrate according to this embodiment contains a maleimide resin, circuit processing can be performed even in a state before curing (B-stage state) of the insulating resin layer formed from the curable resin composition, thereby improving the manufacturing efficiency of the multilayer substrate. Furthermore, the insulating resin layer containing the maleimide resin has excellent dielectric properties. Therefore, the curable resin composition for manufacturing a multilayer substrate according to this embodiment can manufacture a multilayer substrate having an insulating resin layer with good dielectric properties, thereby improving the manufacturing efficiency of the multilayer substrate.

[0101] The curable resin composition for manufacturing a multilayer substrate according to this embodiment may contain a resin or a crosslinking agent other than the maleimide resin, such as an epoxy resin, a phenolic resin, a (meth)acrylic resin, or a benzoxazine.

[0102] From the viewpoint of excellent production efficiency and dielectric properties, the content of the maleimide resin in the curable resin composition for producing a multilayer substrate according to this embodiment may be 60% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 100% by mass based on the total amount of the component (A), other resins, and crosslinking agent in the curable resin composition.

[0103] From the viewpoint of low dielectric properties, the content of the maleimide resin is preferably more than 50 parts by mass, and may be 60 parts by mass or more, 80 parts by mass or more, 90 parts by mass or more, 95 parts by mass or more, or 100 parts by mass, when the total amount of the curable resin composition is 100 parts by mass, or may be 55 to 99 parts by mass, 60 to 96 parts by mass, 70 to 92 parts by mass, or 80 to 90 parts by mass.

[0104] The curable resin composition may contain other components in addition to the resin component, such as the components listed above as other components that may be contained in the first insulating resin layer.

[0105] The preparation means, conditions, etc. of the curable resin composition are not particularly limited. For example, a method may be used in which predetermined amounts of each main component are thoroughly and uniformly stirred and mixed using a mixer or the like, and then kneaded using a mixing roll, an extruder, a kneader, a roll, an extruder, etc. The kneading method is not particularly limited.

[0106] From the viewpoint of coatability, the viscosity of the curable resin composition according to this embodiment at 25°C may be 400 to 4000 mPa s, 400 to 3000 mPa s, or 500 to 2000 mPa s. The viscosity of the curable resin composition at 25°C can be measured using an E-type viscometer.

[0107] The present disclosure will be described in more detail with reference to the following reference examples, although the present disclosure is not limited to these reference examples.

[0108] <Preparation of Maleimide Resin and Curable Resin Composition> (Preparation Example 1) A 2L pressure-resistant SUS container (manufactured by Todoroki Sangyo Co., Ltd.) equipped with a cooling tube, a separation tank, a nitrogen inlet tube, a thermocouple, and a stirrer, and equipped with equipment capable of carrying out a reaction under pressure while refluxing the solvent, was charged with 111 parts by mass of pyromellitic dianhydride (manufactured by Daicel Corporation, PMDA), 907 parts by mass of toluene (manufactured by Wako Pure Chemical Industries, Ltd.), and 200 parts by mass of methanol (manufactured by Daishin Chemical Co., Ltd.). Next, nitrogen gas was introduced into the container and pressurized to a gauge pressure of 250 kPa, after which the temperature was raised to 80 ° C. and maintained at that temperature for 0.5 hours. Subsequently, 368 parts by mass of dimer diamine (trade name "PRIAMINE 1075", manufactured by Croda Japan Co., Ltd.) was added dropwise at a rate of 12.3 g / min. After the dropwise addition, the mixture was maintained at 80 ° C. for 0.5 hours, and then 9.2 parts by mass of methanesulfonic acid was added. The temperature was then raised to 160°C while removing the alcohol-based solvent from the reaction solution. After the temperature was raised, a dehydration ring-closing reaction was carried out at 160°C for 2 hours, and the water and alcohol-based solvent were removed from the reaction solution, yielding a solution containing an intermediate polyimide resin. Subsequently, the resulting solution containing the polyimide resin was cooled to 130°C, and 50 parts by mass of maleic anhydride (manufactured by Fuso Chemical Co., Ltd.) was added. The temperature was then raised to 160°C. After the temperature was raised, a dehydration ring-closing reaction was carried out at 160°C for 4 hours, and the water in the reaction solution was removed, yielding a solution containing maleimide resin (A-1a).

[0109] The obtained solution containing maleimide resin (A-1a) was placed in a separatory funnel, and 1,200 parts by mass of pure water was added. The separatory funnel was shaken and allowed to stand. After standing, the organic layer and the aqueous layer were separated, and only the organic layer was recovered. The recovered organic layer was placed in a 1 L glass container equipped with a cooler, a nitrogen inlet tube, a thermocouple, a stirrer, and a vacuum pump, and the temperature was raised to 88 to 93°C. After removing the water, the temperature was raised to 115°C and the solvent was partially removed for 0.5 hours to obtain a curable resin composition (A-1).

[0110] (Preparation Example 2) Into a 0.3 L flask equipped with a condenser, a separation tank, a nitrogen inlet tube, a thermocouple, and a stirrer, 31.22 parts by mass of BISDA (4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride (manufactured by SABIC, trade name "SD1100P-1000"), 126.36 parts by mass of pseudocumene (manufactured by Toyo Gosei Co., Ltd.), 27.65 parts by mass of Solmix A-11 (trade name, manufactured by Japan Alcohol Sales Co., Ltd., alcohol-based solvent), and 29.99 parts by mass of γ-butyrolactone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added. After addition, the temperature was raised to 80°C and kept at 80°C for 0.5 hours, and 21.59 parts by mass of dimer diamine (trade name "PRIAMINE 1075", manufactured by Croda Japan Co., Ltd.) was added dropwise. After the dropwise addition, 13.94 parts by mass of BAFL (9,9-bis(4-aminophenyl)fluorene) was added. Then, 4.00 parts by mass of methanesulfonic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added, and the temperature was raised to 160°C. After the temperature was raised, 40.00 parts by mass of toluene (Yamaichi Chemical Industry Co., Ltd.) was added, and a dehydration ring-closing reaction was carried out at 160°C for 2 hours. The water and alcohol solvent in the reaction solution were removed, and a solution containing an intermediate polyimide resin was obtained. Subsequently, the resulting solution containing the polyimide resin was cooled to 130°C, and 5.93 parts by mass of maleic anhydride (manufactured by Fuso Chemical Co., Ltd.) was added. The temperature was raised to 160°C, and a dehydration ring-closing reaction was carried out for 4 hours. The water in the reaction solution was removed, and a solution containing maleimide resin (A-2a) was obtained.

[0111] The obtained maleimide resin (A-2a) was placed in a separatory funnel, and 500 parts by mass of pure water was added. The separatory funnel was shaken and allowed to stand. After standing, the aqueous layer and the organic layer separated, and only the organic layer was recovered. The recovered organic layer was placed in a 0.3 L glass vessel equipped with a cooler, a nitrogen inlet tube, a thermocouple, a stirrer, and a vacuum pump, heated to 88 to 93°C, and after removing the water, heated to 100°C. The solvent was partially removed for 0.5 hours under a reduced pressure of 0.1 MPa from atmospheric pressure, to obtain a curable resin composition (A-2).

[0112] (Preparation Example 3) A solution of curable resin composition (A-3) was obtained in the same manner as in Preparation Example 2, except that BISDA (4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride was changed to 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (manufactured by JFE Chemical Corporation, trade name "BPAF")), BAFL (9,9-bis(4-aminophenyl)fluorene) was changed to norbornanediamine (manufactured by Mitsui Fine Chemicals, Inc., trade name "NBDA"), and the blending amounts of each component were changed as shown in Table 1.

[0113] The weight average molecular weight (Mw) of the maleimide resins and the solid content of the curable resin compositions obtained in Preparation Examples 1 to 3 were determined by the following methods. The results are shown in Table 1.

[0114] [Weight-average molecular weight (Mw) of maleimide resin] The weight-average molecular weight of the maleimide resin was measured by gel permeation chromatography (GPC). A sample prepared by dissolving maleimide resin in tetrahydrofuran (THF) to a concentration of 3% by mass was injected in an amount of 50 μL into a column (one GL-R420 (Hitachi High-Tech Fielding Corporation), one GL-R430 (Hitachi High-Tech Fielding Corporation), and one GL-R440 (Hitachi High-Tech Fielding Corporation)) heated to 30°C. Measurement was performed using THF as the developing solvent at a flow rate of 1.6 mL / min. The detector used was an L-3350 RI detector (Hitachi, Ltd.), and the weight-average molecular weight (Mw) was calculated from the elution time using a molecular weight / elution time curve prepared using standard polystyrene (Tosoh Corporation).

[0115] [Solid content of curable resin composition] Curable resin composition X １ g to weight Z １ The weight of the aluminum dish (including the remaining resin composition) after heating at 150°C for 0.5 hours is Z ２ g, the solid content (mass%) was calculated using the following formula: Solid content (mass%) = {(Z ２ -Z １ ) / X １} x 100

[0116]

[0117] <Preparation of Laminate Including B-Stage Film Containing Maleimide Resin> The following components were prepared for preparation of a laminate including a B-stage film containing a maleimide resin. Inorganic filler: 5SM-CK2 (manufactured by Admatechs Co., Ltd., silica mass 70%, average particle size 0.5 μm, methyl isobutyl ketone dispersion) Polymerization initiator: Percumyl D (manufactured by NOF Corporation, dicumyl peroxide) Organic solvent: Cyclopentanone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) MIBK (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., methyl isobutyl ketone)

[0118] (Laminate (1)) A resin composition was prepared by blending 0.589 g of a polymerization initiator, Percumyl D (C-1), with 100 g of curable resin composition (A-1). Next, using an applicator, the resin composition was applied to a support film (polyethylene terephthalate film, manufactured by Toyobo Co., Ltd., trade name "A5300", film thickness 50 μm) so that the thickness after drying would be 25 μm, and the coating was dried in a dryer at 120°C for 10 minutes. Thereafter, a UV irradiator (a UV irradiator with a conveyor, manufactured by GS Yuasa Corporation, using a metal halide lamp (MAL 500NAL)) was used to irradiate the coating with 100 mW / cm from the support film side. ２ , 150 mJ / cm ２ A laminate (1) was produced comprising a support film and a film in a B-stage state (semi-cured state).

[0119] (Laminates (2) to (5)) Laminates (2) to (5) were produced in the same manner as laminate (1), except that the type of curable resin composition and the amount of each component (unit: g) were changed as shown in Table 2.

[0120]

[0121] <Preparation of cured film containing maleimide resin> (Cured film (B-1)) A Cu foil (manufactured by Mitsui Mining & Smelting Co., Ltd., trade name "3EC-M2S-VLP") was attached to the B-stage (semi-cured) film in the laminate (1) using a vacuum laminator under conditions of 100 ° C., 120 seconds, -100 kPa, to obtain an adhesive sheet (1) having a support film / B-stage film / copper foil configuration. Thereafter, the support film of the adhesive sheet (1) was peeled off, and a curing treatment was carried out for 60 minutes at 200 ° C. using a nitrogen dryer (manufactured by Yamato Scientific Co., Ltd., model number: DN410I) in a nitrogen atmosphere. After curing, the copper foil was removed by etching with an aqueous ammonium persulfate solution and dried at 105 ° C. for 30 minutes to produce a cured film (B-1).

[0122] (Cured Films (B-2) to (B-5)) Cured films (B-2) to (B-5) were produced in the same manner as cured film (1), except that laminate (1) was replaced by laminates (2) to (5).

[0123] <Preparation of Maleimide Resin-Free Cured Films> The following materials were prepared as maleimide resin-free cured films: B-6: Liquid crystal polymer (LCP) film (manufactured by Kuraray Co., Ltd., product name "Vextar", product number "CTQ-100") B-7: PTFE film (manufactured by Nitto Denko Corporation, product name "Nitoflon", product number "#900UL")

[0124] [Adhesion] <Preparation of test pieces for measuring adhesive strength> (Reference Example 1) A low-roughness copper foil (manufactured by Furukawa Electric Co., Ltd., product name: FZ-WS-18) or a smooth copper foil (manufactured by Fukuda Metal Foil & Powder Co., Ltd., product name: CF-T9DA-SV-18) was bonded to the B-stage (semi-cured) film of the laminate (1) using a vacuum laminator under conditions of 100°C, 120 seconds, and -100 kPa, to obtain an adhesive sheet (1-2) having a configuration of support film / B-stage film / copper foil. Thereafter, the support film of the adhesive sheet (2) was peeled off, and the adhesive sheet (2) was bonded to a low-roughness copper foil (Furukawa Electric Co., Ltd., product name: FZ-WS-18) or a smooth copper foil (Fukuda Metal Foil & Powder Co., Ltd., product name: CF-T9DA-SV-18) using a vacuum laminator under conditions of 100°C, 120 seconds, and -100 kPa to obtain an adhesive sheet (1-3) having a copper foil / B-stage film / copper foil configuration. The adhesive sheet (1-3) was cured in a dryer at 200°C for 60 minutes to produce a test piece of Reference Example 1.

[0125] (Reference Examples 2 to 5) Test pieces of Reference Examples (2) to (5) were prepared in the same manner as Reference Example (1), except that the laminate (1) was changed to laminates (2) to (5).

[0126] Comparative Reference Example 1 A test piece for Comparative Reference Example 1 was prepared in the same manner as in Reference Example 1, except that a cured film (B-6) was used instead of the film in a B-stage state (semi-cured state), and the film was bonded to the copper foil using a hand roller on a hot plate at a temperature of 315°C.

[0127] Comparative Reference Example 2 A test piece for Comparative Reference Example 2 was prepared in the same manner as in Reference Example 1, except that a cured film (B-7) was used instead of the film in a B-stage state (semi-cured state), and the bonding to the copper foil was carried out using a hand roller on a hot plate at a temperature of 330° C. Note that, because the cured film (B-7) did not adhere to the smooth copper foil, an adhesive sheet having a configuration of smooth copper foil / cured film (B-7) / smooth copper foil could not be prepared.

[0128] <Measurement of adhesive strength> The adhesive strength of the prepared test pieces was measured. The adhesive strength was measured using a 90° peel tester (Yamaden Co., Ltd., RHEONER II CREEP METER RE2-3305B) by peeling a smooth copper foil or a low-roughening copper foil from the cured film at 90° at room temperature at a pulling rate of 5 mm / s, and the adhesive strength between the cured film and the copper foil was evaluated according to the following evaluation criteria. The results are shown in Table 3.

[0129] <Evaluation criteria for adhesive strength> A: adhesive strength of 1.0 kN / m or more B: adhesive strength of 0.5 kN / m or more but less than 1.0 kN / m C: adhesive strength less than 0.5 kN / m

[0130]

[0131] [Dielectric Properties] The relative dielectric constant (Dk) and dielectric loss tangent (Df) of the cured film were measured by the following procedure.

[0132] [Measurement of Dielectric Constant (Dk) and Dielectric Loss Tangent (Df)] (Reference Examples 6 to 10 and Comparative Reference Examples 3 and 4) 50 mm x 50 mm test specimens were prepared using the cured films. These test specimens were dried in a dryer at 105°C for 30 minutes and then left at room temperature (25°C) and 52% humidity for 24 hours. The dielectric constant (Dk) and dielectric loss tangent (Df) were then measured from 20 to 100 GHz by the balanced disc resonator method (BCDR method) using a network analyzer (product name "P5003A", manufactured by KEYSIGHT Technologies) and a split cylinder resonator (manufactured by KEYSIGHT Technologies). The results are shown in Table 4.

[0133]

[0134] Example 1 [Preparation of Multilayer Substrate 1] First, a film in a B-stage state (semi-cured state) of the laminate (1) was bonded to a glass substrate A (alkali-free glass "Eagle XG" manufactured by Corning Incorporated, 0.5 mm thick) cut to a length of 5 cm on a side using a vacuum laminator under conditions of 130°C, 90 seconds, and -100 kPa, to obtain an adhesive sheet (1-4) having a glass substrate A / film in a B-stage state / support film configuration. Two sheets of this adhesive sheet (1-4) and one sheet of glass substrate B (alkali-free glass "Eagle XG" manufactured by Corning Incorporated, 0.5 mm thick) cut to a length of 5 cm on a side were prepared.

[0135] Next, the support film of adhesive sheet (1-4) was peeled off, and the adhesive sheet was placed so that the film side in the B-stage state faced the glass substrate B, thereby preparing a structure (1) of glass substrate B / film in the B-stage state / glass substrate A. Furthermore, the support film of another adhesive sheet (1-4) was peeled off, and the adhesive sheet was placed so that the film side in the B-stage state faced the glass substrate A of the structure (1), thereby preparing a structure (2) of glass substrate B / film in the B-stage state / glass substrate A / film in the B-stage state / glass substrate A.

[0136] The component (2) was then subjected to a pressure curing treatment at 2.5 KN, 200°C, and 10 minutes in a heat and pressure device (20 KN SE work hot plate press WHP-2-300, manufactured by Kosei Hydraulic Machinery Co., Ltd.), to produce a multilayer substrate 1 as shown in FIG. 4. The multilayer substrate 1 was efficiently produced by curing the component (2) all at once under heat and pressure. Furthermore, no peeling between the substrate and the film was observed in the obtained multilayer substrate 1.

[0137] 100, 200, 300... multilayer substrate, 10, 20, 30a, 30b... base material, 11, 21a, 21b... first insulating resin layer, 12, 22a, 22b... second insulating resin layer, 23a, 23b, 23c, 23d... insulating resin layer (build-up layer), 24a, 24b, 24c, 24d... through electrodes, 25... circuit, 26... bump, 38a, 38b, 38c... insulating resin layer.

Claims

1. A method for manufacturing a multilayer substrate, comprising: a first step of forming a first insulating resin layer containing maleimide resin on a substrate; a second step of forming a second insulating resin layer; and a third step of simultaneously curing at least the first insulating resin layer and the second insulating resin layer.

2. The manufacturing method according to claim 1, further comprising the step of forming one or more other insulating resin layers after the second step and before the third step, wherein the second insulating resin layer and all of the insulating resin layers other than the insulating resin layer formed last among the one or more other insulating resin layers contain maleimide resin, and the third step is a step of simultaneously hardening the first insulating resin layer, the second insulating resin layer, and the one or more other insulating resin layers.

3. The manufacturing method according to claim 1, further comprising the step of forming a circuit on said first insulating resin layer after said first step and before said second step.

4. A curable resin composition for producing a multilayer substrate, containing a maleimide resin.

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