JP7495708B2 - Multilayer board manufacturing method - Google Patents

Description

The present invention relates to a photosensitive adhesive composition, a dry film containing this photosensitive adhesive composition, and a method for producing a multilayer substrate having a layer containing a cured product of this photosensitive adhesive composition.

In response to demands for higher performance in electronic devices, printed wiring boards are becoming more multi-layered. One method for multi-layering printed wiring boards is to bond two components together using an adhesive.

For example, Patent Document 1 discloses a photosensitive composition that has adhesive properties even after a photocuring reaction and after pattern formation, and discloses that this photosensitive adhesive composition is used to bond substrates together.

International Publication No. 2011/071107

However, although the photosensitive adhesive composition of Patent Document 1 can bond components such as glass substrates together, it is difficult to obtain sufficient bonding strength.

The object of the present invention is to provide a photosensitive adhesive composition, a dry film, and a method for manufacturing a multilayer board that can achieve high bonding strength when joining two components.

The photosensitive adhesive composition according to one embodiment of the present invention contains a carboxyl group-containing resin (A), a photopolymerization initiator (B), and a photopolymerizable compound (C). The photosensitive adhesive composition is used to bond the first member and the second member via the first adhesive layer and the second adhesive layer by preparing a first adhesive layer and a second adhesive layer on the first member and the second member, respectively, and overlapping and adhering the first adhesive layer and the second adhesive layer.

A dry film according to one embodiment of the present invention contains a dried product of the photosensitive adhesive composition.

In one embodiment of the present invention, the method for manufacturing a multilayer substrate comprises preparing a first adhesive layer and a second adhesive layer on a first member and a second member, respectively, from the photosensitive adhesive composition or the dry film, and bonding the first adhesive layer and the second adhesive layer together to bond the first member and the second member together via the first adhesive layer and the second adhesive layer.

The photosensitive adhesive composition and dry film of one embodiment of the present invention can achieve high bonding strength when bonding a first member and a second member.

The manufacturing method for a multilayer board according to one aspect of the present invention produces a multilayer board with high bonding strength between the components.

FIG. 1 is a cross-sectional view showing an outline of a multilayer substrate according to an embodiment of the present invention. 2A to 2E are cross-sectional views showing an example (first example) of a process for manufacturing a multilayer substrate according to an embodiment of the present invention. 3A to 3F are cross-sectional views showing another example (second example) of the process for manufacturing a multilayer substrate.

The following describes the embodiments of the present invention. In the following description, "(meth)acrylic" means at least one of "acrylic" and "methacrylic". For example, (meth)acrylate means at least one of acrylate and methacrylate.

The photosensitive adhesive composition of this embodiment contains a carboxyl group-containing resin (A), a photopolymerization initiator (B), and a photopolymerizable compound (C). The photosensitive adhesive composition is used to bond the first member 1 and the second member 2 via the first adhesive layer 11 and the second adhesive layer 12 by preparing a first adhesive layer 11 and a second adhesive layer 12 on the first member 1 and the second member 2, respectively, and overlapping and adhering the first adhesive layer 11 and the second adhesive layer 12.

According to this embodiment, the first adhesive layer 11 and the second adhesive layer 12 are prepared from the photosensitive adhesive composition as described above, and the first member 1 and the second member 2 are joined via the first adhesive layer 11 and the second adhesive layer 12, so that it is easy to realize a high bonding strength between the first member 1 and the second member 2. In addition, hereinafter, when the first adhesive layer 11 and the second adhesive layer 12 are overlapped to join the first member 1 and the second member 2, the layer consisting of the first adhesive layer 11 and the second adhesive layer 12 interposed between the first member 1 and the second member 2 may be referred to as the bonding layer 13. In addition, at least one of the first member 1 and the second member 2 may be a printed wiring board having an insulating layer and a conductor wiring overlapping the insulating layer, or may be a metal-clad laminate having a supporting substrate made of a resin material or the like and a metal foil such as copper foil overlapping the supporting substrate. More specific examples of the first member 1 and the second member 2 will be described later.

In particular, the photosensitive adhesive composition of this embodiment can achieve high bonding strength between the first member 1 and the second member 2 even when the first adhesive layer 11 and the second adhesive layer 12 formed on the first member 1 and the second member 2, respectively, are cured by exposure to light such as ultraviolet light, and then the first member 1 and the second member 2 are bonded via the first adhesive layer 11 and the second adhesive layer 12.

Furthermore, in this embodiment, after the photosensitive resin composition is exposed to light, it can be developed using an alkaline solution or the like. Therefore, in the photosensitive adhesive composition of this embodiment, an appropriate pattern can be imparted to the first adhesive layer 11 and the second adhesive layer 12 by a photolithography method. In this case, the first member 1 and the second member 2 can be bonded via the first adhesive layer 11 and the second adhesive layer 12 having an appropriate pattern, and high bonding strength can be achieved. Therefore, it is also possible to produce a bonding layer 13 having a high-definition pattern from the photosensitive adhesive composition.

The reason why the first adhesive layer 11 and the second adhesive layer 12 formed by the photosensitive adhesive composition of this embodiment have high adhesion and can provide high bonding strength when bonding the first member 1 and the second member 2 is not clear, but is presumed to be due to the following reasons.

When the photosensitive adhesive composition contains a carboxyl group-containing resin (A), a photopolymerization initiator (B), and a photopolymerizable compound (C), it is believed that the adhesive layers can be bonded together in a state where the first member 1 and the first adhesive layer 11, and the second member 2 and the second adhesive layer 12 are in strong adhesion to each other by curing the adhesive layers by irradiation with light such as ultraviolet light. It is also believed that the first adhesive layer 11 and the second adhesive layer 12 formed from the photosensitive adhesive composition can be bonded together with strong adhesion strength even in a photocured state.

According to the photosensitive adhesive composition of this embodiment, even if the substrate has several tens of layers, for example 10 layers each, of the first member 1 and the second member 2, the first adhesive layer 11 and the second adhesive layer 12 are formed on the first member 1 and the second member 2, respectively, and the first adhesive layer 11 and the second adhesive layer 12 are bonded together to form the bonding layer 13. This makes it possible to produce a multilayer substrate having a larger number of layers, for example 20 layers or more. Therefore, the photosensitive adhesive composition of this embodiment can be suitably used to bond multilayer substrates together to produce a substrate with even more layers.

The components that may be contained in the photosensitive adhesive composition according to this embodiment are described in detail below.

The carboxyl group-containing resin (A) has a carboxyl group. The carboxyl group-containing resin (A) preferably has an ethylenically unsaturated group. Since the carboxyl group-containing resin (A) has an ethylenically unsaturated group, the photosensitive adhesive composition containing the carboxyl group-containing resin (A) has photoreactivity. Therefore, the carboxyl group-containing resin (A) can impart photosensitivity, specifically ultraviolet curability, to the photosensitive adhesive composition.

The carboxyl group-containing resin (A) preferably contains a carboxyl group-containing resin having an aromatic ring. The carboxyl group-containing resin (A) contains an aromatic ring, which can impart high heat resistance and insulation reliability to the cured product of the photosensitive adhesive composition containing the carboxyl group-containing resin (A). The carboxyl group-containing resin (A) more preferably contains a carboxyl group-containing resin having a polycyclic aromatic ring of any one of a biphenyl skeleton, a naphthalene skeleton, a fluorene skeleton, and an anthracene skeleton. The carboxyl group-containing resin (A) contains a polycyclic aromatic ring of any one of a biphenyl skeleton, a naphthalene skeleton, a fluorene skeleton, and an anthracene skeleton, which can impart high heat resistance and insulation reliability to the cured product of the photosensitive adhesive composition containing the carboxyl group-containing resin (A). It is even more preferable that the carboxyl group-containing resin (A) contains a carboxyl group-containing resin having a bisphenolfluorene skeleton. By including a bisphenolfluorene skeleton in the carboxyl group-containing resin (A), the cured product of the photosensitive adhesive composition containing the carboxyl group-containing resin (A) can be imparted with even higher heat resistance and insulation reliability.

The carboxyl group-containing resin (A) preferably contains a carboxyl group-containing resin (A1) having a bisphenolfluorene skeleton, as described below. The carboxyl group-containing resin (A1) is, for example, a reaction product of an intermediate, which is a reaction product of an epoxy compound (a1) having a bisphenolfluorene skeleton represented by the following formula (1) with a carboxylic acid (a2) containing an unsaturated group-containing carboxylic acid (a2-1), and an acid anhydride (a3). In the formula (1), R ₁ to R ₈ are each independently hydrogen, an alkyl group having 1 to 5 carbon atoms, or a halogen. The carboxyl group-containing resin (A1) is synthesized by reacting an epoxy compound (a1) having a bisphenolfluorene skeleton (S1) represented by the following formula (1) with a carboxylic acid (a2) containing an unsaturated group-containing carboxylic acid (a2-1), and then reacting the intermediate obtained thereby with an acid anhydride (a3).

In formula (1), R ₁ to R ₈ are each independently hydrogen, an alkyl group having from 1 to 5 carbon atoms, or a halogen. That is, each of R ₁ to R ₈ in formula (1) may be hydrogen, an alkyl group having from 1 to 5 carbon atoms, or a halogen. This is because even if hydrogen in the aromatic ring is replaced with a low-molecular-weight alkyl group or a halogen, there is no adverse effect on the physical properties of the carboxyl group-containing resin (A1), and rather, the heat resistance or flame retardancy of a cured product of a photosensitive adhesive composition containing the carboxyl group-containing resin (A1) may be improved.

When the carboxyl group-containing resin (A1) has a bisphenol fluorene skeleton represented by formula (1), the carboxyl group-containing resin (A1) preferably has at least one alkyl group. In this case, the dielectric loss tangent of the cured layer containing the cured product of the photosensitive adhesive composition can be further reduced. For example, it is preferable that at least one of R ₁ to R ₈ in formula (1) is an alkyl group having 1 to 5 carbon atoms.

The carboxyl group-containing resin (A1) has a bisphenol fluorene skeleton represented by formula (1) derived from the epoxy compound (a1), which can impart high heat resistance and insulation reliability to the cured product of the photosensitive adhesive composition. In addition, the carboxyl group-containing resin (A1) has a carboxyl group derived from the acid anhydride (a3), which can impart excellent developability to the photosensitive adhesive composition. Furthermore, the photosensitive adhesive composition contains an epoxy resin, which can impart thermosetting properties to the photosensitive adhesive composition.

The carboxyl group-containing resin (A1) can be synthesized, for example, as described below. To synthesize the carboxyl group-containing resin (A1), first, at least a part of the epoxy group (see formula (2)) of the epoxy compound (a1) is reacted with a carboxylic acid (a2) containing an unsaturated group-containing carboxylic acid (a2-1) to synthesize an intermediate. The synthesis of the intermediate is defined as the first reaction. The intermediate has a structure (S3) shown in the following formula (3) generated by a ring-opening addition reaction between the epoxy group and the carboxylic acid (a2). That is, the intermediate has a secondary hydroxyl group in the structure (S3) generated by a ring-opening addition reaction between the epoxy group and the carboxylic acid (a2). In formula (3), A is a carboxylic acid residue. This A contains an unsaturated group-containing carboxylic acid residue.

Next, the secondary hydroxyl group in the intermediate is reacted with the acid anhydride (a3). This allows the synthesis of a carboxyl group-containing resin (A1). The reaction between the intermediate and the acid anhydride (a3) is defined as the second reaction. The acid anhydride (a3) may include an acid monoanhydride and an acid dianhydride. An acid monoanhydride is a compound having one acid anhydride group formed by dehydration condensation of two carboxyl groups in one molecule. An acid dianhydride is a compound having two acid anhydride groups formed by dehydration condensation of four carboxyl groups in one molecule.

The acid anhydride (a3) may contain at least one of the acid dianhydride (a3-2) and the acid monoanhydride (a3-1). When the acid anhydride (a3) contains the acid monoanhydride (a3-1), the carboxyl group-containing resin (A1) has a bisphenol fluorene skeleton (S1) represented by formula (1) and a structure (S4) represented by the following formula (4).

Structure (S4) is produced by reacting the secondary hydroxyl group in intermediate structure (S3) with the acid anhydride group in acid monoanhydride (a3-1). In formula (4), A is a carboxylic acid residue, and B is an acid monoanhydride residue. This A contains an unsaturated group-containing carboxylic acid residue.

When the acid anhydride (a3) contains the acid dianhydride (a3-2), the carboxyl group-containing resin (A1) has a bisphenol fluorene skeleton (S1) shown in formula (1) and a structure (S5) shown in the following formula (5).

Structure (S5) is produced by the reaction of two acid anhydride groups in the acid dianhydride (a3-2) with two secondary hydroxyl groups in the intermediate. That is, structure (S5) is produced by crosslinking two secondary hydroxyl groups with the acid dianhydride (a3-2). Note that two secondary hydroxyl groups present in one molecule of the intermediate may be crosslinked with each other, or two secondary hydroxyl groups present in each of two molecules of the intermediate may be crosslinked with each other. When two secondary hydroxyl groups present in each of two molecules of the intermediate are crosslinked with each other, the molecular weight increases. In formula (5), A is a carboxylic acid residue, and D is an acid dianhydride residue. This A includes an unsaturated group-containing carboxylic acid residue.

The secondary hydroxyl groups in the intermediate are reacted with an acid anhydride (a3) to obtain a carboxyl group-containing resin (A1). When the acid anhydride (a3) contains an acid dianhydride (a3-2) and an acid monoanhydride (a3-1), a part of the secondary hydroxyl groups in the intermediate is reacted with the acid dianhydride (a3-2), and another part of the secondary hydroxyl groups in the intermediate is reacted with the acid monoanhydride (a3-1). This allows the synthesis of a carboxyl group-containing resin (A1). In this case, the carboxyl group-containing resin (A1) has a bisphenolfluorene skeleton (S1), a structure (S4), and a structure (S5).

The carboxyl group-containing resin (A1) may further have a structure (S6) shown in the following formula (6). Structure (S6) is generated when only one of the two acid anhydride groups in the acid dianhydride (a3-2) reacts with a secondary hydroxyl group in the intermediate. In formula (6), A is a carboxylic acid residue, and D is an acid dianhydride residue. This A contains an unsaturated group-containing carboxylic acid residue.

When some of the epoxy groups in the epoxy compound (a1) remain unreacted during the synthesis of the intermediate, the carboxyl group-containing resin (A1) may have the structure (S2) shown in formula (2), i.e., an epoxy group. Also, when some of the structure (S3) in the intermediate remains unreacted, the carboxyl group-containing resin (A1) may have the structure (S3).

When the acid anhydride (a3) contains an acid dianhydride (a3-2), the reaction conditions during the synthesis of the carboxyl group-containing resin (A1) are optimized to reduce the number of structures (S2) and (S6) in the carboxyl group-containing resin (A1), or to almost completely eliminate structures (S2) and (S6) from the carboxyl group-containing resin (A1).

As described above, the carboxyl group-containing resin (A1) has a bisphenolfluorene skeleton (S1), and when the acid anhydride (a3) contains an acid monoanhydride (a3-1), it has a structure (S4), and when the acid anhydride contains an acid dianhydride (a3-2), it can have a structure (S5). Furthermore, when the acid anhydride (a3) contains an acid monoanhydride (a3-1), the carboxyl group-containing resin (A1) may have at least one of the structures (S2) and (S3). Furthermore, when the acid anhydride (a3) contains an acid dianhydride (a3-2), the carboxyl group-containing resin (A1) may have at least one of the structures (S2) and (S6). Furthermore, when the acid anhydride (a3) contains an acid monoanhydride (a3-1) and an acid dianhydride (a3-2), the carboxyl group-containing resin (A1) may have at least one of the structures (S2), (S3), and (S6).

In addition, when the epoxy compound (a1) itself has a secondary hydroxyl group, that is, for example, when n=1 or more in the formula (7) described below, the carboxyl group-containing resin (A1) may have a structure resulting from the reaction of the secondary hydroxyl group in the epoxy compound (a1) with the acid anhydride (a3).

The structure of the carboxyl group-containing resin (A1) described above is reasonably inferred based on technical common knowledge, and it is not possible to identify the structure of the carboxyl group-containing resin (A1) by analysis. The reason is as follows. When the epoxy compound (a1) itself has a secondary hydroxyl group (for example, when n is 1 or more in formula (7)), the structure of the carboxyl group-containing resin (A1) changes significantly depending on the number of secondary hydroxyl groups in the epoxy compound (a1). In addition, when the intermediate reacts with the acid dianhydride (a3-2), as described above, two secondary hydroxyl groups present in one molecule of the intermediate may be crosslinked with the acid dianhydride (a3-2), or two secondary hydroxyl groups present in each of the two molecules of the intermediate may be crosslinked with the acid dianhydride (a3-2). For this reason, the finally obtained carboxyl group-containing resin (A1) contains a plurality of molecules with different structures, and its structure cannot be identified even by analyzing the carboxyl group-containing resin (A1).

The carboxyl group-containing resin (A1) has an ethylenically unsaturated group derived from the unsaturated group-containing carboxylic acid (a2-1), and therefore has photoreactivity. Therefore, the carboxyl group-containing resin (A1) can impart photosensitivity (specifically, UV curing) to the photosensitive adhesive composition. In addition, the carboxyl group-containing resin (A1) has a carboxyl group derived from the acid anhydride (a3), and therefore can impart developability to the photosensitive adhesive composition with an alkaline aqueous solution containing at least one of an alkali metal salt and an alkali metal hydroxide. Furthermore, when the acid anhydride (a3) contains the acid dianhydride (a3-2), the molecular weight of the carboxyl group-containing resin (A1) depends on the number of crosslinks by the acid dianhydride (a3-2). Therefore, a carboxyl group-containing resin (A1) with an appropriately adjusted acid value and molecular weight can be obtained. When the acid anhydride (a3) contains an acid dianhydride (a3-2) and an acid monoanhydride (a3-1), the amount of the acid dianhydride (a3-2) and the acid monoanhydride (a3-1), as well as the amount of the acid monoanhydride (a3-1) relative to the acid dianhydride (a3-2), can be controlled to easily obtain a carboxyl group-containing resin (A1) with the desired molecular weight and acid value.

The weight average molecular weight of the carboxyl group-containing resin (A1) is preferably 700 or more and 10,000 or less. When the weight average molecular weight is 700 or more, the tackiness of the film formed from the photosensitive adhesive composition is further suppressed, and the insulation reliability and plating resistance of the cured product are further improved. Furthermore, when the weight average molecular weight is 10,000 or less, the developability of the photosensitive adhesive composition with an alkaline aqueous solution is particularly improved. The weight average molecular weight is more preferably 900 or more and 8,000 or less, and particularly preferably 1,000 or more and 5,000 or less.

The acid value of the solid content of the carboxyl group-containing resin (A1) is preferably 60 mgKOH/g or more and 140 mgKOH/g or less. In this case, the developability of the photosensitive adhesive composition is particularly improved. The acid value of the solid content is more preferably 80 mgKOH/g or more and 135 mgKOH/g or less, and even more preferably 90 mgKOH/g or more and 130 mgKOH/g or less.

The polydispersity of the carboxyl group-containing resin (A1) is preferably 1.0 or more and 4.8 or less. In this case, the photosensitive adhesive composition can be provided with excellent developability while ensuring good insulation reliability and plating resistance (e.g., whitening resistance during electroless nickel/gold plating) of the cured product formed from the photosensitive adhesive composition. The polydispersity of the carboxyl group-containing resin (A1) is more preferably 1.1 or more and 4.0 or less, and even more preferably 1.2 or more and 2.8 or less. The polydispersity is the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the carboxyl group-containing resin (A1).

The weight average molecular weight (Mw) of the carboxyl group-containing resin (A1) is calculated from the molecular weight measurement results by gel permeation chromatography. The molecular weight measurement by gel permeation chromatography can be performed, for example, under the following conditions.

GPC device: Showa Denko SHODEX SYSTEM 11,
Column: SHODEX KF-800P, KF-005, KF-003, KF-001, four columns in series;
Mobile phase: THF,
Flow rate: 1 ml/min,
Column temperature: 45°C,
Detector: RI,
Conversion: Polystyrene.

The raw materials for the carboxyl group-containing resin (A1) and the reaction conditions for synthesizing the carboxyl group-containing resin (A1) are described in detail below.

The epoxy compound (a1) has, for example, a structure (S7) shown in the following formula (7). In formula (7), n is, for example, a number from 0 to 20. In order to make the molecular weight of the carboxyl group-containing resin (A1) an appropriate value, it is particularly preferable that the average of n is from 0 to 1. If the average of n is within the range of from 0 to 1, especially when the acid anhydride (a3) contains the acid dianhydride (a3-2), an excessive increase in molecular weight due to the addition of the acid dianhydride (a3-2) is easily suppressed.

The carboxylic acid (a2) includes an unsaturated group-containing carboxylic acid (a2-1). The carboxylic acid (a2) may include only the unsaturated group-containing carboxylic acid (a2-1). Alternatively, the carboxylic acid (a2) may include the unsaturated group-containing carboxylic acid (a2-1) and a carboxylic acid other than the unsaturated group-containing carboxylic acid (a2-1).

The unsaturated group-containing carboxylic acid (a2-1) can contain, for example, a compound having only one ethylenically unsaturated group in one molecule. More specifically, the unsaturated group-containing carboxylic acid (a2-1) may contain at least one compound selected from the group consisting of, for example, acrylic acid, methacrylic acid, ω-carboxy-polycaprolactone (n≈2) monoacrylate, crotonic acid, cinnamic acid, 2-acryloyloxyethyl succinic acid, 2-methacryloyloxyethyl succinic acid, 2-acryloyloxyethyl phthalic acid, 2-methacryloyloxyethyl phthalic acid, 2-acryloyloxypropyl phthalic acid, 2-methacryloyloxypropyl phthalic acid, 2-acryloyloxyethyl maleic acid, 2-methacryloyloxyethyl maleic acid, β-carboxyethyl acrylate, 2-acryloyloxyethyl tetrahydrophthalic acid, 2-methacryloyloxyethyl tetrahydrophthalic acid, 2-acryloyloxyethyl hexahydrophthalic acid, and 2-methacryloyloxyethyl hexahydrophthalic acid. Preferably, the unsaturated group-containing carboxylic acid (a2-1) contains acrylic acid.

The carboxylic acid (a2) may contain a polybasic acid (a2-2). The polybasic acid (a2-2) is an acid in which two or more hydrogen atoms can be substituted with metal atoms in one molecule. The polybasic acid (a2-2) preferably has two or more carboxyl groups. In this case, the epoxy compound (a1) reacts with both the unsaturated group-containing carboxylic acid (a2-1) and the polybasic acid (a2-2). The polybasic acid (a2-1) crosslinks the epoxy groups present in two molecules of the epoxy compound (a1), thereby increasing the molecular weight. This further controls the tackiness of the film formed from the photosensitive adhesive composition and further improves the insulation reliability and plating resistance of the cured product.

The polybasic acid (a2-2) preferably contains a dicarboxylic acid. The polybasic acid (a2-2) can contain, for example, one or more compounds selected from the group consisting of 4-cyclohexene-1,2-dicarboxylic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, and terephthalic acid. Preferably, the polybasic acid (a2-2) contains 4-cyclohexene-1,2-dicarboxylic acid.

When reacting the epoxy compound (a1) with the carboxylic acid (a2), an appropriate method can be adopted. For example, a reactive solution is obtained by adding the carboxylic acid (a2) to a solvent solution of the epoxy compound (a1), and further adding a thermal polymerization inhibitor and a catalyst as necessary, and stirring and mixing. This reactive solution can be reacted by a conventional method at a temperature of preferably 60°C to 150°C, particularly preferably 80°C to 120°C, to obtain an intermediate. The solvent in this case can contain at least one component selected from the group consisting of ketones such as methyl ethyl ketone and cyclohexanone, aromatic hydrocarbons such as toluene and xylene, and acetate esters such as ethyl acetate, butyl acetate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, and propylene glycol monomethyl ether acetate, and dialkyl glycol ethers. The thermal polymerization inhibitor contains at least one of hydroquinone and hydroquinone monomethyl ether, for example. The catalyst may contain at least one component selected from the group consisting of tertiary amines such as benzyldimethylamine and triethylamine, quaternary ammonium salts such as trimethylbenzylammonium chloride and methyltriethylammonium chloride, triphenylphosphine, and triphenylstibine.

The catalyst preferably contains triphenylphosphine. That is, it is preferable to react the epoxy compound (a1) with the carboxylic acid (a2) in the presence of triphenylphosphine. In this case, the ring-opening addition reaction between the epoxy group in the epoxy compound (a1) and the carboxylic acid (a2) is particularly promoted, and a reaction rate (conversion rate) of 95% or more, 97% or more, or nearly 100% can be achieved. Therefore, an intermediate having the structure (S3) can be obtained in high yield. In addition, the occurrence of ion migration in the layer containing the cured product of the photosensitive adhesive composition is suppressed, and the insulation reliability of the layer is further improved.

When the epoxy compound (a1) and the carboxylic acid (a2) are reacted, the amount of the carboxylic acid (a2) relative to 1 mole of the epoxy group of the epoxy compound (a1) is preferably 0.5 moles or more and 1.2 moles or less. In this case, a photosensitive adhesive composition having excellent photosensitivity and stability is obtained. From the same viewpoint, the amount of the unsaturated group-containing carboxylic acid (a2-1) relative to 1 mole of the epoxy group of the epoxy compound (a1) is preferably 0.5 moles or more and 1.2 moles or less, and more preferably 0.8 moles or more and 1.2 moles or less. Alternatively, when the carboxylic acid (a2) contains a carboxylic acid other than the unsaturated group-containing carboxylic acid (a2-1), the amount of the unsaturated group-containing carboxylic acid (a2-1) relative to 1 mole of the epoxy group of the epoxy compound (a1) may be 0.5 moles or more and 0.95 moles or less. In addition, when the carboxylic acid (a2) contains a polybasic acid (a2-2), the amount of the polybasic acid (a2-2) relative to 1 mole of the epoxy group of the epoxy compound (a1) is preferably 0.025 moles or more and 0.25 moles or less. In this case, a photosensitive adhesive composition with excellent photosensitivity and stability is obtained.

The intermediate thus obtained has a hydroxyl group produced by the reaction between the epoxy group of the epoxy compound (a1) and the carboxyl group of the carboxylic acid (a2).

The acid monoanhydride (s3-1) is a compound having one acid anhydride group. The acid monoanhydride (a3-1) can contain an anhydride of a dicarboxylic acid. The acid monoanhydride (a3-1) can contain at least one compound selected from the group consisting of, for example, phthalic anhydride, 1,2,3,6-tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, succinic anhydride, methylsuccinic anhydride, maleic anhydride, citraconic anhydride, glutaric anhydride, cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride, and itaconic anhydride. In particular, it is preferable that the acid monoanhydride (a3-1) contains 1,2,3,6-tetrahydrophthalic anhydride. That is, it is preferable that the acid anhydride (a3) contains 1,2,3,6-tetrahydrophthalic anhydride. That is, it is preferable that the carboxyl group-containing resin (A1) has the structure (S4), and B in formula (4) contains a 1,2,3,6-tetrahydrophthalic anhydride residue. In this case, while ensuring good developability of the photosensitive adhesive composition, the tackiness of the film formed from the photosensitive adhesive composition can be further suppressed and the insulation reliability and plating resistance of the cured product can be further improved. The amount of 1,2,3,6-tetrahydrophthalic anhydride relative to the total acid monoanhydride (a3-1) is preferably 20 mol% or more and 100 mol% or less, and more preferably 40 mol% or more and 100 mol% or less, but is not limited to these ranges.

Acid dianhydride (a3-2) is a compound having two acid anhydride groups. Acid dianhydride (a3-2) can contain an anhydride of a tetracarboxylic acid. The acid dianhydride (a3-2) may contain at least one compound selected from the group consisting of, for example, 1,2,4,5-benzenetetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, methylcyclohexene tetracarboxylic dianhydride, tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, ethylene tetracarboxylic dianhydride, 9,9'-bis (3,4-dicarboxyphenyl) fluorene dianhydride, glycerin bisanhydrotrimellitate monoacetate, ethylene glycol bisanhydrotrimellitate, 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, 1,3,3a,4,5,9b-hexahydro-5 (tetrahydro-2,5-dioxo-3-furanyl) naphtho [1,2-c] furan-1,3-dione, 1,2,3,4-butane tetracarboxylic dianhydride, and 3,3',4,4'-biphenyl tetracarboxylic dianhydride. In particular, it is preferable that the acid dianhydride (a3-2) contains 3,3',4,4'-biphenyltetracarboxylic dianhydride. That is, it is preferable that D in formula (5) and formula (6) contains a 3,3',4,4'-biphenyltetracarboxylic dianhydride residue. In this case, while ensuring good developability of the photosensitive adhesive composition, the tackiness of the film formed from the photosensitive adhesive composition can be further suppressed and the insulation reliability and plating resistance of the cured product can be further improved. The amount of 3,3',4,4'-biphenyltetracarboxylic dianhydride relative to the entire acid dianhydride (a3-2) is preferably 20 mol% or more and 100 mol% or less, and more preferably 40 mol% or more and 100 mol% or less, but is not limited to these ranges.

When reacting the intermediate with the acid anhydride (a3), an appropriate method can be used. For example, the acid anhydride (a3) is added to a solvent solution of the intermediate, and if necessary, a thermal polymerization inhibitor and a catalyst are added and mixed by stirring to obtain a reactive solution. The reactive solution is reacted by a conventional method at a temperature preferably from 60°C to 150°C, particularly preferably from 80°C to 120°C, to obtain the carboxyl group-containing resin (A1). As the solvent, catalyst, and polymerization inhibitor, appropriate ones can be used, and the solvent, catalyst, and polymerization inhibitor used in the synthesis of the intermediate can also be used as they are.

The catalyst preferably contains triphenylphosphine in particular. That is, it is preferable to react the intermediate with the acid anhydride (a3) in the presence of triphenylphosphine. In this case, the reaction between the secondary hydroxyl group in the intermediate and the acid anhydride (a3) is particularly promoted, and a reaction rate (conversion rate) of 90% or more, 95% or more, 97% or more, or almost 100% can be achieved. Therefore, the carboxyl group-containing resin (A1) having at least one of the structures (S4) and (S5) can be obtained in high yield. In addition, the occurrence of ion migration in the layer containing the cured product of the photosensitive adhesive composition is suppressed, and the insulation reliability of the layer is further improved.

When the acid anhydride (a3) contains an acid dianhydride (a3-2) and an acid monoanhydride (a3-1), the amount of the acid dianhydride (a3-2) is preferably 0.05 mol or more and 0.24 mol or less per mole of epoxy group in the epoxy compound (a1). Also, the amount of the acid monoanhydride (a3-1) is preferably 0.3 mol or more and 0.7 mol or less per mole of epoxy group in the epoxy compound (a1). In this case, a carboxyl group-containing resin (A1) with an appropriately adjusted acid value and molecular weight can be easily obtained.

It is also preferable to react the intermediate with the acid anhydride (a3) under air bubbling. In this case, excessive increase in the molecular weight of the carboxyl group-containing resin (A1) produced is suppressed, and the developability of the photosensitive adhesive composition with an alkaline aqueous solution is particularly improved.

The carboxyl group-containing resin (A) may contain only the carboxyl group-containing resin (A1) or only a carboxyl group-containing resin other than the carboxyl group-containing resin (A1), or may contain the carboxyl group-containing resin (A1) and a carboxyl group-containing resin other than the carboxyl group-containing resin (A1). The carboxyl group-containing resin other than the carboxyl group-containing resin (A1) includes a carboxyl group-containing resin that does not have a bisphenolfluorene skeleton (hereinafter, also referred to as a carboxyl group-containing resin (A2)).

The carboxyl group-containing resin (A2) may contain, for example, a compound (hereinafter referred to as component (A2-1)) that has a carboxyl group and is not photopolymerizable. The (A2-1) component contains, for example, a polymer of an ethylenically unsaturated monomer that contains an ethylenically unsaturated compound having a carboxyl group. The ethylenically unsaturated compound having a carboxyl group may contain compounds such as acrylic acid, methacrylic acid, and ω-carboxy-polycaprolactone (n≒2) monoacrylate. The ethylenically unsaturated compound having a carboxyl group may also contain a reaction product of pentaerythritol triacrylate, pentaerythritol trimethacrylate, or the like with a dibasic acid anhydride. The ethylenically unsaturated monomer may further contain an ethylenically unsaturated compound that does not have a carboxyl group, such as 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl-2-hydroxyethyl phthalate, or a linear or branched aliphatic or alicyclic (but may have some unsaturated bonds in the ring) (meth)acrylic acid ester.

The carboxyl group-containing resin (A2) may contain a compound having a carboxyl group and an ethylenically unsaturated group (hereinafter referred to as the (A2-2) component). The carboxyl group-containing resin (A2) may contain only the (A2-2) component. The (A2-2) component contains, for example, a resin (referred to as the first resin (x)) which is a reaction product of an intermediate which is a reaction product of an epoxy compound (x1) having two or more epoxy groups in one molecule with an ethylenically unsaturated compound (x2) and at least one compound (x3) selected from the group consisting of polycarboxylic acids and their anhydrides. The first resin (x) is obtained, for example, by adding a compound (x3) to an intermediate obtained by reacting an epoxy group in the epoxy compound (x1) with a carboxyl group in the ethylenically unsaturated compound (x2). The epoxy compound (x1) may contain an appropriate epoxy compound such as a cresol novolac type epoxy compound, a phenol novolac type epoxy compound, or a biphenyl novolac type epoxy compound. In particular, the epoxy compound (x1) preferably contains at least one compound selected from the group consisting of biphenyl novolac type epoxy compounds and cresol novolac type epoxy compounds. The epoxy compound (x1) may contain only a biphenyl novolac type epoxy compound, or may contain only a cresol novolac type epoxy compound. The epoxy compound (x1) may contain a polymer of an ethylenically unsaturated compound (z). The ethylenically unsaturated compound (z) contains a compound (z1) having an epoxy group, such as glycidyl (meth)acrylate, or further contains a compound (z2) having no epoxy group, such as 2-(meth)acryloyloxyethyl phthalate. The ethylenically unsaturated compound (x2) preferably contains at least one of acrylic acid and methacrylic acid. The compound (x3) contains at least one compound selected from the group consisting of polycarboxylic acids, such as phthalic acid, tetrahydrophthalic acid, and methyltetrahydrophthalic acid, and anhydrides of these polycarboxylic acids. In particular, it is preferable that compound (x3) contains at least one polycarboxylic acid selected from the group consisting of phthalic acid, tetrahydrophthalic acid, and methyltetrahydrophthalic acid.

The (A2-2) component may contain a resin (referred to as the second resin (y)) which is a reaction product between a polymer of an ethylenically unsaturated monomer containing an ethylenically unsaturated compound having a carboxyl group and an ethylenically unsaturated compound having an epoxy group. The ethylenically unsaturated monomer may further contain an ethylenically unsaturated compound having no carboxyl group. The second resin (y) is obtained by reacting an ethylenically unsaturated compound having an epoxy group with a part of the carboxyl groups in the polymer. The ethylenically unsaturated monomer may further contain an ethylenically unsaturated compound having no carboxyl group. The ethylenically unsaturated compound having a carboxyl group contains, for example, compounds such as acrylic acid, methacrylic acid, ω-carboxy-polycaprolactone (n≒2) monoacrylate, pentaerythritol triacrylate, and pentaerythritol trimethacrylate. Ethylenically unsaturated compounds without a carboxyl group include, for example, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl-2-hydroxyethyl phthalate, linear or branched aliphatic or alicyclic (which may have some unsaturated bonds in the ring) (meth)acrylic acid esters, etc. Ethylenically unsaturated compounds with an epoxy group preferably include glycidyl (meth)acrylate.

The carboxyl group-containing resin (A) contains only the carboxyl group-containing resin (A1), only the carboxyl group-containing resin (A2), or both the carboxyl group-containing resin (A1) and the carboxyl group-containing resin (A2). The carboxyl group-containing resin (A) preferably contains 30% by mass or more of the carboxyl group-containing resin (A1), more preferably 50% by mass or more, even more preferably 60% by mass or more, and even more preferably 100% by mass. In this case, the heat resistance and insulation reliability of the cured product of the photosensitive adhesive composition can be particularly improved. In addition, the tackiness of the film formed from the photosensitive adhesive composition can be sufficiently reduced. Furthermore, the developability of the photosensitive adhesive composition with an alkaline aqueous solution can be ensured. Therefore, the photosensitive adhesive composition can also be suitably used to form an insulating layer.

The photopolymerization initiator (B) is a component that can improve the photosensitivity of the photosensitive adhesive composition. The photopolymerization initiator (B) preferably contains, for example, an acylphosphine oxide-based photopolymerization initiator (B1). In this case, when the photosensitive adhesive composition is exposed to light such as ultraviolet light, the photosensitive adhesive composition can be given high photosensitivity. In addition, the occurrence of ion migration in the layer containing the cured product of the photosensitive adhesive composition is suppressed, and the insulation reliability of the layer is further improved. In addition, the acylphosphine oxide-based photopolymerization initiator (B1) does not easily inhibit the electrical insulation of the cured product. Therefore, even when the photosensitive adhesive composition is exposed to light and cured, a cured product with excellent electrical insulation is obtained, and this cured product is suitable, for example, as an interlayer insulation layer.

Examples of the acylphosphine oxide photopolymerization initiator (B1) include monoacylphosphine oxide photopolymerization initiators such as 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and 2,4,6-trimethylbenzoyl-ethyl-phenyl-phosphinate, as well as bis-(2,6-dichlorobenzoyl)phenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-2,5-dimethylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, and bis-(2,6-dichlorobenzoyl)-1-naphthylphosphine oxide. The photopolymerization initiator (B1) may contain at least one component selected from the group consisting of bisacylphosphine oxide-based photopolymerization initiators such as phosphine oxide, bis-(2,6-dimethoxybenzoyl)phenylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide, bis-(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and (2,5,6-trimethylbenzoyl)-2,4,4-trimethylpentylphosphine oxide. In particular, it is preferable that the acylphosphine oxide-based photopolymerization initiator (B1) contains 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, and it is also preferable that the acylphosphine oxide-based photopolymerization initiator (B1) contains only 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide.

It is preferable that the photopolymerization initiator (B) contains a hydroxyketone-based photopolymerization initiator (B2) in addition to the acylphosphine oxide-based photopolymerization initiator (B1). That is, it is preferable that the photosensitive adhesive composition contains a hydroxyketone-based photopolymerization initiator (B2). In this case, the photosensitive adhesive composition can be imparted with even higher photosensitivity than when the hydroxyketone-based photopolymerization initiator (B2) is not contained. As a result, when a coating film formed from the photosensitive adhesive composition is cured by irradiating it with light such as ultraviolet light, it is possible to sufficiently cure the coating film from its surface to its deep parts. Examples of hydroxyketone-based photopolymerization initiators (B2) include 1-hydroxy-cyclohexyl-phenyl-ketone, phenylglyoxylic acid methyl ester, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one, and 2-hydroxy-2-methyl-1-phenyl-propan-1-one.

The mass ratio of the acylphosphine oxide-based photopolymerization initiator (B1) to the hydroxyketone-based photopolymerization initiator (B2) is preferably within the range of 1:0.01 to 1:10. In this case, it is possible to improve the curability near the surface of the coating film formed from the photosensitive adhesive composition and the curability in the deeper portions in a well-balanced manner.

It is also preferable that the photopolymerization initiator (B) contains a photopolymerization initiator (B3) having a benzophenone skeleton. That is, it is also preferable that the photosensitive adhesive composition contains an acylphosphine oxide-based photopolymerization initiator (B1) and a photopolymerization initiator (B3) having a benzophenone skeleton, or contains an acylphosphine oxide-based photopolymerization initiator (B1), a hydroxyketone-based photopolymerization initiator (B2), and a photopolymerization initiator (B3) having a benzophenone skeleton. In this case, when the coating film formed from the photosensitive adhesive composition is partially exposed and then developed, the curing of the unexposed parts is suppressed, so that the resolution is particularly high. For this reason, a cured product of the photosensitive adhesive composition having a very fine pattern can be formed. In particular, when an interlayer insulating layer of a multilayer printed wiring board is produced from the photosensitive adhesive composition and a small diameter hole for a through hole is provided in this interlayer insulating layer by a photolithography method (see FIG. 3), the small diameter hole can be formed precisely and easily. An example of a photopolymerization initiator (B3) having a benzophenone skeleton is bis(diethylamino)benzophenone.

The amount of the photopolymerization initiator (B3) having a benzophenone skeleton relative to the acylphosphine oxide-based photopolymerization initiator (B1) is preferably 0.5% by mass or more and 20% by mass or less. When the amount of the photopolymerization initiator (B3) having a benzophenone skeleton relative to the acylphosphine oxide-based photopolymerization initiator (B1) is 0.5% by mass or more, the resolution is particularly high. In addition, when the amount of the photopolymerization initiator (B3) having a benzophenone skeleton relative to the acylphosphine oxide-based photopolymerization initiator (B1) is 20% by mass or less, the photopolymerization initiator (B3) having a benzophenone skeleton is less likely to inhibit the electrical insulation of the cured product of the photosensitive adhesive composition. From the same viewpoint, the amount of bis(diethylamino)benzophenone relative to the acylphosphine oxide-based photopolymerization initiator (B1) is preferably 0.5% by mass or more and 20% by mass or less.

The photosensitive adhesive composition may further contain an appropriate photopolymerization accelerator, sensitizer, etc. For example, the photosensitive adhesive composition may contain oxime esters such as 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime); benzoin and its alkyl ethers; acetophenones such as acetophenone and benzyl dimethyl ketal; anthraquinones such as 2-methylanthraquinone; 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-isopropyl ... The photosensitive adhesive composition may contain at least one component selected from the group consisting of thioxanthones such as xanthone, 4-isopropylthioxanthone, and 2,4-diisopropylthioxanthone; benzophenones such as benzophenone and 4-benzoyl-4'-methyldiphenyl sulfide; xanthones such as 2,4-diisopropylxanthone; and α-hydroxyketones such as 2-hydroxy-2-methyl-1-phenyl-propan-1-one; and compounds containing nitrogen atoms such as 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone. The photosensitive adhesive composition may contain, together with the photopolymerization initiator (B), an appropriate photopolymerization accelerator and sensitizer such as a tertiary amine such as p-dimethylbenzoic acid ethyl ester, p-dimethylaminobenzoic acid isoamyl ester, and 2-dimethylaminoethyl benzoate. The photosensitive adhesive composition may contain at least one of a photopolymerization initiator for visible light exposure and a photopolymerization initiator for near-infrared exposure, as necessary. The photosensitive adhesive composition may contain, together with the photopolymerization initiator (B), a coumarin derivative such as 7-diethylamino-4-methylcoumarin, which is a sensitizer for laser exposure, a carbocyanine dye, a xanthene dye, etc.

The photopolymerizable compound (C) can impart photocurability to the photosensitive adhesive composition. The photopolymerizable compound (C) preferably contains at least one selected from the group consisting of photopolymerizable monomers and photopolymerizable prepolymers. The photopolymerizable monomer can contain at least one compound selected from the group consisting of monofunctional (meth)acrylates such as 2-hydroxyethyl (meth)acrylate; and polyfunctional (meth)acrylates such as diethylene glycol di(meth)acrylate, trimethylolpropane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ε-caprolactone-modified pentaerythritol hexaacrylate, and tricyclodecane dimethanol di(meth)acrylate.

In particular, the photopolymerizable compound (C) preferably contains a trifunctional compound, i.e., a compound having three unsaturated bonds in one molecule. In this case, the resolution is improved when the film formed from the photosensitive adhesive composition is exposed and developed, and the developability of the photosensitive adhesive composition with an alkaline aqueous solution is particularly improved. The trifunctional compound can contain at least one compound selected from the group consisting of, for example, trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, ethoxylated isocyanuric acid tri(meth)acrylate, ε-caprolactone-modified tris-(2-acryloxyethyl)isocyanurate, and ethoxylated glycerin tri(meth)acrylate.

It is also preferable that the photopolymerizable compound (C) contains a phosphorus-containing compound (phosphorus-containing unsaturated compound). In this case, the flame retardancy of the cured product of the photosensitive adhesive composition is improved. Examples of phosphorus-containing unsaturated compounds include 2-methacryloyloxyethyl acid phosphate (specific examples are Light Ester P-1M and Light Ester P-2M, manufactured by Kyoeisha Chemical Co., Ltd.), 2-acryloyloxyethyl acid phosphate (specific example is Light Acrylate P-1A, manufactured by Kyoeisha Chemical Co., Ltd.), diphenyl-2-methacryloyloxyethyl phosphate (specific example is MR-260, manufactured by Daihachi Kogyo Co., Ltd.), and the HFA series manufactured by Showa Polymer Co., Ltd. (specific example is Diphenyl It can contain at least one compound selected from the group consisting of HFA-6003 and HFA-6007, which are addition reaction products of dipentaerythritol hexaacrylate and HCA (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide), HFA-3003 and HFA-6127, which are addition reaction products of caprolactone-modified dipentaerythritol hexaacrylate and HCA (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide), etc.

The photopolymerizable prepolymer may contain at least one compound selected from the group consisting of prepolymers obtained by polymerizing a monomer having an ethylenically unsaturated bond and then adding an ethylenically unsaturated group, and oligo(meth)acrylate prepolymers. The oligo(meth)acrylate prepolymers may contain at least one component selected from the group consisting of epoxy(meth)acrylate, polyester(meth)acrylate, urethane(meth)acrylate, alkyd resin(meth)acrylate, silicone resin(meth)acrylate, and spiran resin(meth)acrylate.

The photosensitive adhesive composition preferably contains an organic filler (D). When the photosensitive adhesive composition contains an organic filler (D), the effect of improving the bonding strength when bonding the first member 1 and the second member 2 by bonding the first adhesive layer 11 and the second adhesive layer 12 formed from the photosensitive adhesive composition on the first member 1 and the second member 2 to each other is remarkable. In addition, the organic filler (D) has high compatibility in the photosensitive adhesive composition and can impart stronger thixotropy to the photosensitive adhesive composition. Therefore, the moldability can be improved when forming an adhesive layer from the photosensitive adhesive composition.

The organic filler (D) preferably has at least one functional group selected from the group consisting of a carboxyl group, an epoxy group, and an amino group. In this case, the first adhesive layer 11 and the second adhesive layer 12 formed from the photosensitive adhesive composition on the first member 1 and the second member 2 are bonded to each other, which can particularly improve the bonding strength when bonding the first member 1 and the second member 2.

In particular, when the photosensitive adhesive composition contains an organic filler having a carboxyl group (hereinafter also referred to as organic filler (D1)), the developability of the photosensitive adhesive composition can be improved. In addition, when the photosensitive adhesive composition contains the organic filler (D1), the non-uniformity of the cured layer caused by the fluidity of the photosensitive adhesive composition can be reduced. This makes it easier to make the thickness of the cured layer uniform. In this case, the photosensitive adhesive composition does not need to contain a rheology control agent. The carboxyl group of the organic filler (D1) is formed as a side chain in the product by polymerizing or crosslinking a carboxylic acid monomer such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, or itaconic acid. The carboxylic acid monomer has a carboxyl group and a polymerizable unsaturated double bond. The organic filler (D1) enhances the thixotropy of the photosensitive adhesive composition, thereby improving the stability (particularly storage stability) of the photosensitive adhesive composition. Furthermore, since the organic filler (D1) has a carboxyl group, it can improve the developability of the cured product containing the photosensitive adhesive composition and can improve the compatibility of the crystalline epoxy resin (E1) described below to prevent crystallization in the photosensitive adhesive composition. The carboxyl group content of the organic filler (D1), for example, is preferably such that the acid value of the organic filler (D1) is 1 mgKOH/g or more and 60 mgKOH/g or less as determined by acid-base titration. If the acid value is less than 1 mgKOH/g, the stability of the photosensitive adhesive composition and the developability of the cured product may be reduced. If the acid value is more than 60 mgKOH/g, the moisture resistance reliability of the cured product may be reduced. It is more preferable that the acid value of the organic filler (D1) is 3 mgKOH/g or more and 40 mgKOH/g or less.

When the organic filler (D) has an amino group, the organic filler (D) contains, for example, melamine. When the organic filler (D) having an amino group contains melamine, the content of melamine is preferably 0.1% by mass or more and 6% by mass or less when the content of the carboxyl group-containing resin (A) is taken as 100 parts by mass.

It is also preferable that the organic filler (D) has a hydroxyl group. In this case, too, the bonding strength can be further improved when bonding the first member 1 and the second member 2 together by bonding the first adhesive layer 11 and the second adhesive layer 12 formed from the photosensitive adhesive composition.

The average primary particle diameter of the organic filler (D) is preferably 1 μm or less. When the average primary particle diameter of the organic filler (D) is 1 μm or less, the thixotropy of the photosensitive adhesive composition is efficiently increased. Therefore, the stability of the photosensitive adhesive composition is further improved. In addition, when the average primary particle diameter of the organic filler (D) is 1 μm or less, the organic filler can be uniformly dispersed, and the bonding strength when bonding the first adhesive layer 11 and the second adhesive layer 12 to bond the first member 1 and the second member 2 is improved. The average primary particle diameter of the organic filler (D) is not particularly limited in its lower limit, but is preferably, for example, 0.001 μm or more. The average primary particle diameter of the organic filler (D) is measured as D50 by a laser diffraction type particle size distribution measuring device. It is more preferable that the average primary particle diameter of the organic filler (D) is 0.4 μm or less, and even more preferable that it is 0.1 μm or less. In this case, the roughness of the rough surface formed on the cured product can be particularly fine. In addition, scattering during exposure can be suppressed in the photosensitive adhesive composition, which can further improve the resolution of the photosensitive adhesive composition.

The organic filler (D) is preferably dispersed in the photosensitive adhesive composition with a maximum particle diameter of less than 1.0 μm, more preferably less than 0.5 μm. The maximum particle diameter is measured, for example, by a laser diffraction particle size distribution measuring device. Alternatively, the maximum particle diameter is measured by observing the cured product with a transmission electron microscope (TEM). The organic filler (D) may aggregate in the photosensitive adhesive composition (e.g., may form secondary particles), and in that case, the maximum particle diameter means the size of the particles after aggregation. If the maximum particle diameter of the organic filler (D) in the dispersed state is within the above range, the roughness of the rough surface formed in the cured product can be further refined. In addition, scattering during exposure is suppressed in the photosensitive adhesive composition, thereby further improving the resolution of the photosensitive adhesive composition. In addition, the stability of the photosensitive adhesive composition can be improved. It is particularly preferable that the average primary particle diameter of the organic filler (D) is 0.1 μm or less, and the organic filler (D) is dispersed with a particle diameter of 0.5 μm or less. When particle aggregation occurs, the maximum particle size is usually larger than the average primary particle size.

The organic filler (D) preferably contains a rubber component. The rubber component can impart flexibility to the cured product of the photosensitive adhesive composition. The rubber component can be composed of a resin. The rubber component preferably contains at least one polymer selected from the group consisting of crosslinked acrylic rubber, crosslinked NBR, crosslinked MBS, and crosslinked SBR. In this case, the rubber component can impart excellent flexibility to the cured product of the photosensitive adhesive composition. Furthermore, in this case, the surface of the cured product layer can also be imparted with a more appropriate roughness. The rubber component contains a crosslinked structure formed when the monomers constituting the above polymer are copolymerized. NBR is generally a copolymer of butadiene and acrylonitrile, and is classified as a nitrile rubber. MBS is generally a copolymer composed of three components, methyl methacrylate, butadiene, and styrene, and is classified as a butadiene-based rubber. SBR is generally a copolymer of styrene and butadiene, and is classified as a styrene rubber. Specific examples of the organic filler (D) include XER-91-MEK manufactured by JSR Corporation, XER-32-MEK manufactured by JSR Corporation, and XSK-500 manufactured by JSR Corporation. Among these organic fillers ( D ), XER-91-MEK is a crosslinked rubber (NBR) having a carboxyl group with an average primary particle size of 0.07 μm, and is provided as a methyl ethyl ketone dispersion containing 15% by weight of this crosslinked rubber and having an acid value of 10.0 mgKOH/g. XER-32-MEK is a dispersion in which a polymer (linear particles) of a carboxyl group-modified hydrogenated nitrile rubber is dispersed in methyl ethyl ketone at a content of 17% by weight based on the total amount of the dispersion. Furthermore, XSK-500 is a crosslinked rubber (SBR) having an average primary particle size of 0.07 μm and containing carboxyl groups and hydroxyl groups, and is provided in a methyl ethyl ketone dispersion containing 15% by weight of this crosslinked rubber. In this manner, the organic filler (D) may be blended in the photosensitive adhesive composition in the form of a dispersion. That is, the rubber component may be blended in the photosensitive adhesive composition in the form of a dispersion. In addition to the above, specific examples of the organic filler (D) include part number XER-92 manufactured by JSR Corporation.

The organic filler (D) may contain a particle component other than the rubber component. In this case, the organic filler (D) may contain at least one particle component selected from the group consisting of acrylic resin fine particles having a carboxyl group and cellulose fine particles having a carboxyl group. The acrylic resin fine particles having a carboxyl group may contain at least one particle component selected from the group consisting of non-crosslinked styrene-acrylic resin fine particles and crosslinked styrene-acrylic resin fine particles. A specific example of the non-crosslinked styrene-acrylic resin fine particles is product number FS-201 (average primary particle diameter 0.5 μm) manufactured by Nippon Paint Industrial Coatings Co., Ltd. Specific examples of the crosslinked styrene-acrylic resin fine particles are product number MG-351 (average primary particle diameter 1.0 μm) and product number BGK-001 (average primary particle diameter 1.0 μm) manufactured by Nippon Paint Industrial Coatings Co., Ltd. In addition, the organic filler (D) may contain a particle component other than the particle components selected from the rubber component, acrylic resin fine particles, and cellulose fine particles. In this case, the organic filler (D) can contain a particle component having a carboxyl group. That is, the particle component having a carboxyl group may be different from the particle component selected from the rubber component, the acrylic resin fine particles, and the cellulose fine particles.

Here, when the photosensitive adhesive composition contains an organic filler (D), the organic filler (D) may cause light scattering in the photosensitive adhesive composition during exposure. In this case, it is preferable that the photosensitive adhesive composition contains the above-mentioned acylphosphine oxide-based photopolymerization initiator (B1) and hydroxyketone-based photopolymerization initiator (B2). This allows good developability to be obtained even when the photosensitive adhesive composition is exposed to light and cured. It is particularly preferable that the mass ratio of the acylphosphine oxide-based photopolymerization initiator (B1) to the hydroxyketone-based photopolymerization initiator (B2) is within the range of 1:0.01 to 1:1. From the same viewpoint, it is also preferable that the photosensitive adhesive composition contains a photopolymerization initiator (B3) having a benzophenone skeleton, and in this case, it is particularly preferable that the amount of the photopolymerization initiator (B3) having a benzophenone skeleton is 1% by mass or more and 18% by mass or less relative to the acylphosphine oxide-based photopolymerization initiator (B1). From the same viewpoint, the amount of bis(diethylamino)benzophenone is particularly preferably 1% by mass or more and 18% by mass or less relative to the acylphosphine oxide-based photopolymerization initiator (B1).

It is preferable that the photosensitive adhesive composition further contains an epoxy compound (E). In this case, the bonding strength can be further improved when bonding the first member 1 and the second member 2 together by bonding the first adhesive layer 11 and the second adhesive layer 12 formed from the photosensitive adhesive composition. Furthermore, the insulating properties of the multilayer substrate 10 formed by bonding the first member 1 and the second member 2 can be improved.

The epoxy compound (E) can impart thermosetting properties to the photosensitive adhesive composition. The epoxy compound (E) preferably contains a crystalline epoxy resin (E1). In this case, the developability of the layer formed from the photosensitive adhesive composition can be improved. In this case, when the photosensitive adhesive composition further contains the above-mentioned organic filler (D1), the carboxyl group in the organic filler (D1) can improve the compatibility of the crystalline epoxy resin (E1). This can prevent recrystallization of the crystalline epoxy resin (E1) in the photosensitive adhesive composition. The epoxy compound (E) may further contain an amorphous epoxy resin (E2). Here, the "crystalline epoxy resin" is an epoxy resin that has a melting point, and the "amorphous epoxy resin" is an epoxy resin that does not have a melting point.

The crystalline epoxy resin (E1) preferably contains one or more components selected from the group consisting of, for example, 1,3,5-tris(2,3-epoxypropyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, hydroquinone-type crystalline epoxy resin (specifically, Nippon Steel & Sumikin Chemical Co., Ltd., product name YDC-1312), biphenyl-type crystalline epoxy resin (specifically, Mitsubishi Chemical Co., Ltd., product name YX-4000), diphenyl ether-type crystalline epoxy resin (specifically, Nippon Steel Chemical & Material Co., Ltd., product name YSLV-80DE), bisphenol-type crystalline epoxy resin (specifically, Nippon Steel & Sumikin Chemical Co., Ltd., product name YSLV-80XY), tetrakisphenolethane-type crystalline epoxy resin (specifically, Nippon Kayaku Co., Ltd., product name GTR-1800), and bisphenolfluorene-type crystalline epoxy resin (specifically, epoxy resin having structure (S7)).

It is preferable that the crystalline epoxy resin (E1) has two epoxy groups per molecule. In this case, it is possible to make it even more difficult for cracks to occur in the cured product when temperature changes are repeated.

The crystalline epoxy resin (E1) preferably has an epoxy equivalent of 150 g/eq or more and 300 g/eq or less. This epoxy equivalent is the gram weight of the crystalline epoxy resin (E1) containing 1 gram equivalent of epoxy groups. The crystalline epoxy resin (E1) has a melting point. The melting point of the crystalline epoxy resin (E1) is, for example, 70°C or more and 180°C or less.

In particular, the epoxy compound (E) preferably contains a crystalline epoxy resin (E1-1) having a melting point of 110°C or less. In this case, the developability of the photosensitive adhesive composition with an alkaline aqueous solution is particularly improved. In this case, the resolution (opening property) of the adhesive layer formed from the photosensitive adhesive composition can also be improved. The crystalline epoxy resin (E1-1) having a melting point of 110°C or less can contain at least one component selected from the group consisting of, for example, biphenyl type epoxy resin (specific example, product number YX-4000 manufactured by Mitsubishi Chemical Corporation), biphenyl ether type epoxy resin (specific example, product number YSLV-80DE manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), bisphenol type epoxy resin (specific example, product number YSLV-80XY manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), and bisphenol fluorene type crystalline epoxy resin (specific example, epoxy resin having structure (S7)).

Examples of the amorphous epoxy resin (E2) include phenol novolac type epoxy resins (specifically, EPICLON N-775 manufactured by DIC Corporation), cresol novolac type epoxy resins (specifically, EPICLON N-695 manufactured by DIC Corporation), bisphenol A novolac type epoxy resins (specifically, EPICLON N-865 manufactured by DIC Corporation), bisphenol A type epoxy resins (specifically, jER1001 manufactured by Mitsubishi Chemical Corporation), bisphenol F type epoxy resins (specifically, jER4004P manufactured by Mitsubishi Chemical Corporation), bisphenol S type epoxy resins (specifically, EPICLON N-865 manufactured by DIC Corporation), and the like. EXA-1514), bisphenol AD type epoxy resin, biphenyl novolac type epoxy resin (specific example is product number NC-3000 manufactured by Nippon Kayaku Co., Ltd.), hydrogenated bisphenol A type epoxy resin (specific example is product number ST-4000D manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), naphthalene type epoxy resin (specific examples are product numbers EPICLON HP-4032, EPICLON HP-4700, EPICLON HP-4770 manufactured by DIC Corporation), tertiary butyl catechol type epoxy resin (specific example is product number EPICLON HP-820 manufactured by DIC Corporation), dicyclopentadiene type epoxy resin (specific example is product number EPICLON HP-820 manufactured by DIC Corporation), HP-7200), adamantane type epoxy resins (specific examples include ADAMANTATEX-E-201, manufactured by Idemitsu Kosan Co., Ltd.), special bifunctional epoxy resins (specific examples include YL7175-500 and YL7175-1000, manufactured by Mitsubishi Chemical Corporation; EPICLON TSR-960, EPICLON TER-601, EPILON TSR-250-80BX, EPICLON 1650-75MPX, EPICLON EXA-4850, EPICLON EXA-4816, EPICLON EXA-4822, and EPICLON EXA-4832, manufactured by DIC Corporation), EXA-9726; product number YSLV-120TE manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), rubber-like core-shell polymer modified bisphenol A type epoxy resin (specific example is product number MX-156 manufactured by Kaneka Corporation), rubber-like core-shell polymer modified bisphenol F type epoxy resin (specific example is product number MX-136 manufactured by Kaneka Corporation), and rubber particle-containing bisphenol F type epoxy resin (specific example is product number Kane Ace MX-130 manufactured by Kaneka Corporation).

When the photosensitive adhesive composition contains an epoxy compound (E), it is preferable that the photosensitive adhesive composition contains both a crystalline epoxy resin (E1) and an amorphous epoxy resin (E2). In this case, the bonding strength when bonding adhesive layers made from the photosensitive adhesive composition to each other can be further improved, and the resolution (opening ability) of the adhesive layer can be further improved.

The epoxy compound (E) may contain a phosphorus-containing epoxy resin. In this case, the flame retardancy of the cured product of the photosensitive adhesive composition is improved. The phosphorus-containing epoxy resin may be contained in the crystalline epoxy resin (E1) or in the amorphous epoxy resin (E2). Examples of the phosphorus-containing epoxy resin include phosphoric acid-modified bisphenol F type epoxy resin (specific examples are EPICLON EXA-9726 and EPICLON EXA-9710 manufactured by DIC Corporation), Epotohto FX-305 manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., etc.

The amounts of the components in the photosensitive adhesive composition are appropriately adjusted so that the photosensitive adhesive composition is photocurable and developable in an alkaline solution.

The amount of the carboxyl group-containing resin (A) relative to the solid content of the photosensitive adhesive composition is preferably 5% by mass or more and 85% by mass or less, more preferably 10% by mass or more and 75% by mass or less, and even more preferably 20% by mass or more and 50% by mass or less. The amount of the carboxyl group-containing resin (A1) relative to the solid content of the photosensitive adhesive composition is preferably 5% by mass or more and 85% by mass or less, more preferably 10% by mass or more and 75% by mass or less, and even more preferably 20% by mass or more and 50% by mass or less. The amount of the photopolymerization initiator (B) relative to the carboxyl group-containing resin (A) is preferably 0.1% by mass or more and 30% by mass or less, and even more preferably 1% by mass or more and 25% by mass or less.

The amount of the photopolymerizable compound (C) relative to the carboxyl group-containing resin (A) is preferably 1% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 45% by mass or less, and even more preferably 21% by mass or more and 40% by mass or less.

When the photosensitive adhesive composition contains an organic filler (D), the content of the organic filler (D) relative to the carboxyl group-containing resin (A) is preferably 0.1% by mass or more and 60% by mass or less. The content of the organic filler (D) relative to the carboxyl group-containing resin (A) is more preferably 0.5% by mass or more and 30% by mass or less, even more preferably 1% by mass or more and 17% by mass or less, and particularly preferably 3% by mass or more and 15% by mass or less.

When the organic filler (D) contains a rubber component, the content of the rubber component relative to the carboxyl group-containing resin (A) is preferably 1% by mass or more and 60% by mass or less, more preferably 2% by mass or more and 20% by mass or less, and even more preferably 3% by mass or more and 17% by mass or less.

When the photosensitive adhesive composition contains an epoxy compound (E), the amount of the epoxy compound (E) is preferably such that the total equivalent weight of the epoxy group contained in the epoxy compound (E) is 0.7 to 2.5 relative to 1 equivalent weight of the carboxyl group contained in the carboxyl group-containing resin (A), more preferably 0.7 to 2.3, and even more preferably 0.7 to 2.0. The total equivalent weight of the epoxy group contained in the crystalline epoxy resin (E1) is preferably 0.1 to 2.0 relative to 1 equivalent weight of the carboxyl group contained in the carboxyl group-containing resin (A), more preferably 0.2 to 1.9, and even more preferably 0.3 to 1.5. Alternatively, the total equivalent weight of the epoxy group contained in the crystalline epoxy resin (E1) may be 0.7 to 2.5 relative to 1 equivalent weight of the carboxyl group contained in the carboxyl group-containing resin (A).

The photosensitive adhesive composition may further contain components other than those described above, as long as they do not impair the effects of this embodiment.

The photosensitive adhesive composition may contain at least one resin selected from the group consisting of blocked isocyanates of the tolylene diisocyanate type, morpholine diisocyanate type, isophorone diisocyanate type, and hexamethylene diisocyanate type blocked with caprolactam, oxime, malonic acid ester, etc.; butylated urea resin; various thermosetting resins other than those mentioned above; ultraviolet-curable epoxy (meth)acrylate; resins obtained by adding (meth)acrylic acid to epoxy resins such as bisphenol A type, phenol novolac type, cresol novolac type, and alicyclic type; and polymer compounds such as diallyl phthalate resin, phenoxy resin, urethane resin, and fluororesin.

The photosensitive adhesive composition may contain a curing agent for curing the epoxy compound (E). The curing agent may contain at least one component selected from the group consisting of imidazole derivatives such as imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 4-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole; amine compounds such as dicyandiamide, benzyldimethylamine, 4-(dimethylamino)-N,N-dimethylbenzylamine, 4-methoxy-N,N-dimethylbenzylamine, and 4-methyl-N,N-dimethylbenzylamine; hydrazine compounds such as adipic acid hydrazide and sebacic acid hydrazide; phosphorus compounds such as triphenylphosphine; acid anhydrides; phenols; mercaptans; Lewis acid amine complexes; and onium salts. Commercially available products of these components include, for example, 2MZ-A, 2MZ-OK, 2PHZ, 2P4BHZ, and 2P4MHZ (all trade names of imidazole-based compounds) manufactured by Shikoku Kasei Co., Ltd., and U-CAT3503N and UCAT3502T (all trade names of dimethylamine blocked isocyanate compounds), DBU, DBN, U-CATSA102, and U-CAT5002 (all bicyclic amidine compounds and their salts) manufactured by San-Apro Co., Ltd.

The photosensitive adhesive composition may further contain an inorganic filler. Examples of inorganic fillers include silica filler, barium sulfate, carbon nanotubes, talc, bentonite, aluminum hydroxide, magnesium hydroxide, and titanium oxide. For example, when the photosensitive adhesive composition contains a white material such as titanium oxide or zinc oxide, the photosensitive adhesive composition and its cured product can be whitened.

The photosensitive adhesive composition may contain an adhesion promoter. Examples of adhesion promoters include guanamine derivatives such as acetoguanamine (2,4-diamino-6-methyl-1,3,5-triazine) and benzoguanamine (2,4-diamino-6-phenyl-1,3,5-triazine), as well as S-triazine derivatives such as 2,4-diamino-6-methacryloyloxyethyl-S-triazine, 2-vinyl-4,6-diamino-S-triazine, 2-vinyl-4,6-diamino-S-triazine-isocyanuric acid adduct, and 2,4-diamino-6-methacryloyloxyethyl-S-triazine-isocyanuric acid adduct.

The photosensitive adhesive composition may contain a rheology control agent. The rheology control agent makes it easier to optimize the viscosity of the photosensitive adhesive composition. Examples of rheology control agents include urea-modified medium polarity polyamide (product numbers BYK-430 and BYK-431 manufactured by BIGBOO Japan Co., Ltd.), polyhydroxycarboxylic acid amide (product number BYK-405 manufactured by BIGBOO Japan Co., Ltd.), modified urea (product numbers BYK-410, BYK-411, and BYK-420 manufactured by BIGBOO Japan Co., Ltd.), polymeric urea derivative (product number BYK-415 manufactured by BIGBOO Japan Co., Ltd.), urea-modified urethane (product number BYK-425 manufactured by BIGBOO Japan Co., Ltd.), polyurethane (product number BYK-428 manufactured by BIGBOO Japan Co., Ltd.), castor oil wax, polyethylene wax, polyamide wax, bentonite, kaolin, and clay.

The photosensitive adhesive composition may contain at least one component selected from the group consisting of a curing accelerator; a colorant; a copolymer of silicone, acrylate, or the like; a leveling agent; a thixotropic agent; a polymerization inhibitor; an antihalation agent; a flame retardant; an antifoaming agent; an antioxidant; a surfactant; a pigment; and a polymer dispersant.

In preparing the photosensitive adhesive composition of this embodiment, for example, the raw materials of the photosensitive adhesive composition are mixed and kneaded by an appropriate kneading method using, for example, a three-roll mill, a ball mill, a sand mill, or the like, to prepare the photosensitive adhesive composition. When the raw materials contain liquid components, low-viscosity components, etc., the raw materials excluding the liquid components, low-viscosity components, etc. are first kneaded to prepare a mixture, and then the liquid components, low-viscosity components, etc. are added to the obtained mixture and mixed to prepare the photosensitive adhesive composition. When the photosensitive adhesive composition contains a solvent, first, a part or all of the solvent in the raw materials may be mixed, and then mixed with the remaining raw materials. In addition, when the photosensitive adhesive composition contains an organic filler (D), when a dispersion of the organic filler (D) is used, the photosensitive adhesive composition may be prepared by mixing the above-mentioned raw material components other than the organic filler (D) with the dispersion.

In consideration of storage stability, etc., the first agent may be prepared by mixing a portion of the components of the photosensitive adhesive composition, and the second agent may be prepared by mixing the remaining components. That is, the photosensitive adhesive composition may include a first agent and a second agent. In this case, for example, the first agent may be prepared by mixing and dispersing the photopolymerizable compound (C), a portion of the solvent, and a thermosetting component among the components of the photosensitive adhesive composition in advance, and the second agent may be prepared by mixing and dispersing the remaining components of the photosensitive adhesive composition. In this case, the first agent and the second agent are mixed at the appropriate time to prepare a mixed liquid, and the first adhesive layer 11 and the second adhesive layer 12 can be produced from this mixed liquid.

It is preferable that the photosensitive adhesive composition has such properties that a film having a thickness of 25 μm produced from the photosensitive adhesive composition can be developed with an aqueous sodium carbonate solution. In this case, it is possible to produce a sufficiently thick first adhesive layer 11 and second adhesive layer 12 from the photosensitive adhesive composition by a photolithography method. Of course, it is also possible to produce a first adhesive layer 11 and second adhesive layer 12 having a thickness of less than 25 μm from the photosensitive adhesive composition.

Whether a 25 μm thick film can be developed with an aqueous sodium carbonate solution can be confirmed by the following method. A wet coating film is formed by applying a photosensitive adhesive composition onto a suitable substrate, and the wet coating film is heated at 80° C. for 40 minutes to form a 25 μm thick film. In a state where a negative mask having an exposed portion that transmits ultraviolet light and a non-exposed portion that blocks ultraviolet light is directly applied to the film, the film is exposed to ultraviolet light under the condition of 500 mJ/cm ^2. After exposure, a process is performed in which a 1% Na ₂ CO ₃ aqueous solution at 30° C. is sprayed onto the film at a spray pressure of 0.2 MPa for 90 seconds, and then pure water is sprayed at a spray pressure of 0.2 MPa for 90 seconds. When the film is observed after this process, if the portion corresponding to the non-exposed portion of the film is removed and no residue is observed, it can be determined that the 25 μm thick film can be developed with an aqueous sodium carbonate solution. It is also possible to confirm whether a film of another thickness (e.g., 30 μm) can be developed with an aqueous sodium carbonate solution in the same manner.

The method for joining the first member 1 and the second member 2 using the photosensitive adhesive composition according to this embodiment, and the method for producing the multilayer substrate 10 will be described with reference to Figures 2A to 2E.

As described above, the photosensitive adhesive composition is used to prepare the first adhesive layer 11 and the second adhesive layer 12 when bonding the first member 1 and the second member 2 via the first adhesive layer 11 and the second adhesive layer 12 by adhering the first adhesive layer 11 and the second adhesive layer 12 that overlap the first member 1 and the second member 2, respectively. Therefore, the photosensitive adhesive composition can be used to prepare the multilayer substrate 10 from the first member 1 and the second member 2.

The first adhesive layer 11 and the second adhesive layer 12 may be formed on the first member 1 and the second member 2, respectively, by any suitable method, but specifically, for example, the following method is used.

First, the first member 1 and the second member 2 are prepared (see FIG. 2A). The first member 1 and the second member 2 are not particularly limited and may be formed from an appropriate material. The first member 1 and the second member 2 may be formed from the same material. More specifically, the first member 1 and the second member 2 may be, for example, a polyethylene terephthalate (PET) film, glass, polycarbonate, cycloolefin polymer, liquid crystal polymer, glass epoxy resin substrate, metal-clad laminate, silicon wafer, and a circuit board having conductor wiring such as a printed wiring board. Each of the first member 1 and the second member 2 may be, for example, a printed wiring board having an insulating layer 5, conductor wiring 3, 3 provided on one surface of the insulating layer 5 and the other surface on the opposite side, and a via 40 that conducts between the conductor wiring 3, 3, as shown in FIG. 1.

Below, a first example of a process for manufacturing a multilayer substrate 10 in which the first member 1 and the second member 2 are printed wiring boards having conductor wiring 3 will be specifically described with reference to Figures 2A to 2E.

A first adhesive layer 11 can be produced on the first member 1 by applying a photosensitive adhesive composition onto the first member 1 and, if necessary, drying or semi-curing the photosensitive adhesive composition by heating. A second adhesive layer 12 can be produced on the second member 2 by applying a photosensitive adhesive composition onto the second member 2 and, if necessary, drying or semi-curing the photosensitive adhesive composition by heating (see FIG. 2B). Any appropriate method may be used to apply the photosensitive adhesive composition, and examples of such methods include immersion, spraying, spin coating, roll coating, curtain coating, and screen printing. When the photosensitive adhesive composition is heated, for example, when the photosensitive adhesive composition contains a solvent, the photosensitive adhesive composition is heated at a temperature in the range of, for example, 60 to 120° C. to volatilize the solvent.

Each of the first adhesive layer 11 and the second adhesive layer 12 may be made of a dry film containing a dried or semi-cured product of the photosensitive adhesive composition. In this case, for example, the photosensitive adhesive composition is first applied to a suitable support made of polyester or the like, and then heated to form a dry film, which is a dried or semi-cured product of the photosensitive adhesive composition, on the support. This results in a laminate (dry film with support) comprising a dry film and a support supporting the dry film. The dry film in this laminate is then superimposed on the first member 1, pressure is applied to the dry film and the first member 1, and the support is then peeled off from the dry film, transferring the dry film from the support to the first member 1. This results in a first adhesive layer 11 made of a dry film being provided on the first member 1. In a similar manner, a second adhesive layer 12 made of a dry film is provided on the second member 2.

Each of the first adhesive layer 11 and the second adhesive layer 12 may be cured by exposure. Since the photosensitive adhesive composition has photosensitivity, it can be cured by exposure. For example, each of the first adhesive layer 11 and the second adhesive layer 12 may be fully exposed by irradiating light such as ultraviolet light. The light source for exposure is, for example, selected from the group consisting of a chemical lamp, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra-high pressure mercury lamp, a xenon lamp, a metal halide lamp, an LED, a YAG, a g-line (436 nm), an h-line (405 nm), an i-line (365 nm), and a combination of two or more of g-line, h-line, and i-line. The light source is not limited to these, and may be any light source that can irradiate light that can cure the photosensitive adhesive composition. In addition, when the first adhesive layer 11 and the second adhesive layer 12 are produced by the above-mentioned dry film method, the dry film in the laminate may be superimposed on the first member 1 and the second member 2, and then the dry film may be exposed to light such as ultraviolet light through the support without peeling off the support, and the support may be peeled off from the dry film.

The thickness of each of the first adhesive layer 11 and the second adhesive layer 12 is not particularly limited, but may be, for example, 1 μm or more and 100 μm or less.

Next, the first adhesive layer 11 and the second adhesive layer 12 are stacked. As a result, a laminate in which the first member 1, the first adhesive layer 11, the second adhesive layer 12, and the second member 2 are stacked in this order is obtained. This laminate is heat-pressed using a vacuum laminator (vacuum laminator) or the like (see FIG. 2D). As a result, the first adhesive layer 11 and the second adhesive layer 12 are bonded, and the first member 1 and the second member 2 are bonded via the first adhesive layer 11 and the second adhesive layer 12. As a result, a multilayer substrate 10 is obtained (see FIG. 2E). The conditions of the heat press may be appropriately adjusted so as to bond the first adhesive layer 11 and the second adhesive layer 12, but for example, the press pressure is 0.01 MPa or more and 30 MPa or less, the heating temperature is 50 ° C. or more and 300 ° C. or less, and the heat press time is 1 second or more and 60 minutes or less. In this embodiment, it is also preferable to obtain a multilayer substrate 10 by further heating after heat-pressing the laminate as described above. As a result, a multilayer substrate 10 having a better bonding strength between the first member 1 and the second member 2 is obtained. The heating conditions may be set appropriately, but the heating temperature is preferably, for example, 50°C or higher and 300°C or lower, and the heating time is preferably 5 minutes or higher and 300 minutes or lower. The heating temperature is more preferably 80°C to 280°C, even more preferably 100°C to 250°C, and particularly preferably 130°C to 200°C. The heating time is more preferably 10 minutes to 250 minutes, even more preferably 20 minutes to 200 minutes, and particularly preferably 30 minutes to 180 minutes. In addition, when the photosensitive adhesive composition contains a crystalline epoxy resin, it is more preferable to heat the composition at a temperature equal to or higher than the melting point of the crystalline epoxy resin. In this case, the bonding strength is further improved.

In this way, according to this embodiment, the first adhesive layer 11 on the first member 1 and the second adhesive layer 12 on the second member 2 are overlapped and adhered to each other, so that the first member 1 and the second member 2 are joined via the first adhesive layer 11 and the second adhesive layer 12, thereby producing the multilayer substrate 10.

In the above, with reference to Figures 2A to 2E, a method for manufacturing a multilayer substrate 10 in which two members (a first member 1 and a second member 2) are bonded together is described, in which a first member 1 and a second member 2 are bonded together via a first adhesive layer 11 and a second adhesive layer 12 to produce a multilayer substrate 10. However, the method is not limited to this. As long as the members are bonded together by bonding together adhesive layers formed from the photosensitive adhesive composition described above, the multilayer substrate 10 may be produced by bonding three or more members.

When each of the first member 1 and the second member 2 is a printed wiring board, the printed wiring board may have only one insulating layer as described above, or may be a multilayer printed wiring board having multiple insulating layers. In other words, each of the first member 1 and the second member 2 may be a printed wiring board or the like in which several tens of layers, for example 10 or more layers, are stacked.

In addition, electrically insulating layers such as a solder resist layer and an interlayer insulating layer may be formed from a coating or dry film of the photosensitive adhesive composition according to this embodiment.

A second example of the method for manufacturing the multilayer substrate 10 will be described with reference to Figures 3A to 3F. In the second example, the photosensitive adhesive composition according to this embodiment is used to form a first adhesive layer 11 and a second adhesive layer 12 having an appropriate pattern by a photolithography method or the like, and then the first member 1 and the second member 2 are bonded together. Note that descriptions that overlap with the method described in the first example will be omitted as appropriate. Even when the first adhesive layer 11 and the second adhesive layer 12 have an appropriate pattern, high bonding strength between the first member 1 and the second member 2 can be achieved by bonding the first adhesive layer 11 and the second adhesive layer 12 together.

First, a first member 1 and a second member 2 are prepared. Each of the first member 1 and the second member 2 includes an insulating layer 5 and a conductor wiring 3 overlapping the insulating layer 5 (see FIG. 3A). Each of the first member 1 and the second member 2 is, for example, a printed wiring board. The thickness of the first member 1 and the second member 2 is not particularly limited, but is, for example, 1 μm or more and 10 mm or less.

A photosensitive adhesive composition is applied onto the first member 1 so as to cover the conductor wiring 3, forming a film. This film may be dried by heating.

A coating made of a dry film may be formed by overlaying a dry film made of a photosensitive adhesive composition on the first member 1 so as to cover the conductor wiring 3. In this case, as in the first example above, for example, a dry film in a laminate comprising a dry film and a support is overlaid on the first member 1, pressure is applied to the dry film and the first member 1, and then the support is peeled off from the dry film, transferring the dry film from the support to the first member 1. This provides a coating made of a dry film on the first member 1. In a similar manner, a coating made of a dry film is provided on the second member 2.

The first adhesive layer 11 is produced from the film by photolithography. Specifically, the film is partially exposed to ultraviolet light by applying a negative mask to the film, and the exposed parts are cured.

The negative mask has, for example, an exposed portion that transmits ultraviolet light and a non-exposed portion that blocks ultraviolet light. The non-exposed portion is provided at a position that coincides with the position of the opening 4 described below. The negative mask is, for example, a phototool such as a mask film or a dry plate. The ultraviolet light source may be the same as the light source described above. The exposure method may be a method other than the method using a negative mask. For example, the adhesive layer may be exposed by a direct writing method in which ultraviolet light emitted from a light source is irradiated only on the portion of the adhesive layer that is to be exposed.

The second adhesive layer 12 is prepared on the first member 2 in a manner similar to that for the first adhesive layer 11.

When the first adhesive layer 11 is made from a dry film, the dry film in the laminate may be superimposed on the first member 1, and then the coating made of the dry film may be exposed to light such as ultraviolet light through the support without peeling off the support, and then the support may be peeled off from the coating.

Next, the film is developed using a developer such as an alkaline solution to remove the unexposed portions of the film. This allows a first adhesive layer 11 having a pattern to be produced. In the example shown in FIG. 3C, the first adhesive layer 11 has an opening 4, and a portion of the conductor wiring 3 is exposed at the bottom of this opening 4.

In the development process, an appropriate developer can be used according to the composition of the photosensitive adhesive composition. The developer is, for example, an alkaline aqueous solution containing at least one of an alkali metal salt and an alkali metal hydroxide, or an organic amine. More specifically, the alkaline aqueous solution contains at least one component selected from the group consisting of sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium hydroxide, potassium hydroxide, ammonium hydroxide, tetramethylammonium hydroxide, and lithium hydroxide. The solvent in the alkaline aqueous solution may be water alone or a mixture of water and a hydrophilic organic solvent such as a lower alcohol. The organic amine contains at least one component selected from the group consisting of monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, and triisopropanolamine.

The developer is preferably an alkaline aqueous solution containing at least one of an alkali metal salt and an alkali metal hydroxide, and is particularly preferably an aqueous sodium carbonate solution. In this case, it is possible to improve the working environment and reduce the burden of waste disposal.

In addition, a second adhesive layer 12 having a pattern is prepared on the second member 2 using the same method as used to prepare the first adhesive layer 11.

Next, the first adhesive layer 11 and the second adhesive layer 12 are layered in the same manner as described above with reference to Figures 2C-D. This results in a laminate in which the first member 1, the first adhesive layer 11, the second adhesive layer 12, and the second member 2 are layered in this order. This laminate is heat pressed using a vacuum laminating device (vacuum laminator) or the like (see Figures 3D and 3E). This bonds the first adhesive layer 11 and the second adhesive layer 12 together, and the first member 1 and the second member 2 are joined via the first adhesive layer 11 and the second adhesive layer 12. This results in a multilayer substrate 10 (see Figure 3F).

When the first adhesive layer 11 and the second adhesive layer 12 are laminated, for example, as shown in FIG. 3D, the opening 4 in the first adhesive layer 11 and the opening 4 in the second adhesive layer 12 are laminated. As a result, a hole 41 (see, for example, FIG. 3E) penetrating the bonding layer 13 is created in the bonding layer 13. By disposing the conductive material 30 in this hole 41, the conductor wiring 3 of the first member 1 and the conductor wiring 3 of the second member 2 can be electrically connected via the conductive material 30. Specifically, for example, the conductive material 30 is disposed on the portion of the conductor wiring 3 of the first member 1 that is exposed at the bottom of the opening 4. In this state, the first adhesive layer 11 and the second adhesive layer 12 are laminated and bonded by heat pressing. At this time, the conductive material 30 melts, for example, and is electrically connected to each of the first member 1 and the second member 2. As a result, the conductive material 30 electrically connects the conductor wirings 3 to each other. The conductive material 30 is not particularly limited as long as it is a material having conductivity, but examples of the conductive material 30 include solder balls and conductive pastes.

A conductive material 30 is interposed on the conductor wiring 3 and in the portion (e.g., the opening 4 shown in FIG. 3C) of the first adhesive layer 11 and the second adhesive layer 12 that has been removed by exposure. In this case, the conductor wiring 3 in the first member 1 and the second member 2 can be electrically connected to each other via the conductive material 30.

Electronic components such as semiconductor chips, resistors, and inductors may be placed in the openings 4 or holes 41. In this case, a multilayer substrate 10 incorporating electronic components is obtained.

In this embodiment, it is also preferable to obtain the multilayer substrate 10 by further heating the laminate after heat pressing as described above. This results in a multilayer substrate 10 having better bonding strength between the first member 1 and the second member 2.

Thus, in this embodiment, even if the first adhesive layer 11 and the second adhesive layer 12 having a pattern are prepared from the photosensitive adhesive composition by a photolithography method, the first adhesive layer 11 and the second adhesive layer 12 can bond the first member 1 and the second member 2. In other words, the photosensitive adhesive composition of this embodiment allows the first adhesive layer 11 and the second adhesive layer 12 to have a high-definition pattern, and can achieve high bonding strength between the first member 1 and the second member 2.

Specific examples of the present invention are presented below. However, the present invention is not limited to these examples.

(1) Synthesis of Carboxyl Group-Containing Resin (1-1) Synthesis Example 1 (Carboxyl Group-Containing Resin A)
Into a four-neck flask equipped with a reflux condenser, a thermometer, an air blowing tube, and a stirrer, 250 parts by mass of a bisphenol fluorene type epoxy compound (an epoxy compound represented by formula (7) in which R ₁ to R ₈ in formula (7) are all hydrogen and have an epoxy equivalent of 250 g/eq), 72 parts by mass of acrylic acid, 1.5 parts by mass of triphenylphosphine, 0.2 parts by mass of methylhydroquinone, 60 parts by mass of propylene glycol monoethyl ether acetate, and 140 parts by mass of diethylene glycol monoethyl ether acetate were added. These were stirred under air bubbling to prepare a mixture. This mixture was heated in the flask under air bubbling while stirring under conditions of a heating temperature of 115° C. and a heating time of 12 hours. As a result, an intermediate solution was prepared.

Next, 60.8 parts by mass of 1,2,3,6-tetrahydrophthalic anhydride, 58.8 parts by mass of 3,3',4,4'-biphenyltetracarboxylic dianhydride, and 38.7 parts by mass of propylene glycol monomethyl ether acetate were added to the intermediate solution in the flask. These were heated at a heating temperature of 115°C for a heating time of 6 hours while stirring under air bubbling. Next, the mixture was heated at a heating temperature of 80°C for a heating time of 1 hour while stirring under air bubbling. This resulted in a 65% by mass solution of carboxyl group-containing resin A. The polydispersity of carboxyl group-containing resin A was 2.15, the weight average molecular weight was 3096, and the acid value was 105 mg KOH.

(1-2) Synthesis Example 2 (Carboxyl Group-Containing Resin B)
A mixture was prepared by adding 203 parts by mass of cresol novolac epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd., product number YDCN-700-5, epoxy equivalent 203), 106 parts by mass of diethylene glycol monoethyl ether acetate, 0.2 parts by mass of methylhydroquinone, 72 parts by mass of acrylic acid, and 1.5 parts by mass of triphenylphosphine into a four-neck flask equipped with a reflux condenser, a thermometer, an air inlet tube, and a stirrer. This mixture was heated at a heating temperature of 100° C. for a heating time of 4 hours.

Next, 68 parts by mass of tetrahydrophthalic acid, 0.3 parts by mass of methylhydroquinone, 0.5 parts by mass of triphenylphosphine, and 29 parts by mass of diethylene glycol monoethyl ether acetate were added to the mixture and heated at 90°C for 18 hours. Next, 34 parts by mass of petroleum naphtha (Swasol 1500) was added and heated at 90°C for 5 hours. This resulted in a 65% by mass solution of carboxyl group-containing resin B. The epoxy equivalent of carboxyl group-containing resin B was 9871 g/eq.

(2) Preparation of Photosensitive Adhesive Composition [Examples 1 to 18, Comparative Examples 1 and 2, Reference Example ]
Of the components shown in Tables 1 and 2 below, the powdery components were dispersed in advance in the solution of the carboxyl group-containing resin prepared in (1) above using a three-roll mill, and then all the components shown in Tables 1 and 2 below, and methyl ethyl ketone (solvent) as a diluent if necessary, were added to a flask, and the mixture was stirred and mixed at a temperature of 35° C. to prepare a composition, thereby obtaining a photosensitive adhesive composition. The details of the components shown in Tables 1 and 2 are as follows. In addition, the numerical values showing the amounts of the components in Tables 1 and 2 are the solid content amounts, but for organic fillers A to C and F, the numerical values shown in parentheses are the solid content amounts.
Photopolymerization initiator A: 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (manufactured by BASF, product number Irgacure TPO).
Photopolymerization initiator B: 1-hydroxycyclohexylphenylketone (manufactured by BASF, product number Irgacure 184).
Photopolymerization initiator C: 4,4'-bis(diethylamino)benzophenone.
Photopolymerizable compound A: trimethylolpropane triacrylate.
Photopolymerizable compound B: a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., product number KAYARAD DPHA).
Dispersion of organic filler A: A dispersion in which crosslinked rubber (NBR) having an average primary particle size of 0.07 μm was dispersed in methyl ethyl ketone at a content of 15% by weight based on the total amount of the dispersion (manufactured by JSR Corporation, product number XER-91-MEK; acid value 10.0 mgKOH/g).
Dispersion of organic filler B: A dispersion in which crosslinked rubber (SBR) having an average primary particle size of 0.07 μm was dispersed in methyl ethyl ketone at a content of 15% by weight based on the total amount of the dispersion (manufactured by JSR Corporation, product number XSK-500).
Dispersion of organic filler C: Polymer of carboxyl group-modified hydrogenated nitrile rubber. (Dispersion in which linear particles of rubber are dispersed in methyl ethyl ketone at a content of 17% by weight based on the total amount of the dispersion (manufactured by JSR Corporation, product number XER-32-MEK).)
Organic filler D: epoxy group-containing organic filler powder (glycidyl-modified acrylonitrile butadiene rubber having an average primary particle size of 0.3 μm).
Organic filler E: fine powder melamine (manufactured by Nissan Chemical Industries, Ltd.).
Organic filler F: Kane Ace MX-125, manufactured by Kaneka Corporation, containing 33% by mass of core-shell type SBR particles in bisphenol A type epoxy resin. Epoxy equivalent: 270 g/eq.).
Epoxy resin A: biphenyl-type crystalline epoxy resin (manufactured by Mitsubishi Chemical Corporation, product name YX-4000, melting point 105° C., epoxy equivalent 187 g/eq.).
Epoxy resin B: bisphenol type crystalline epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd., product name YSLV-80XY, melting point 75 to 85°C, epoxy equivalent 192 g/eq.).
Epoxy resin C solution: A solution obtained by dissolving a long-chain carbon chain-containing bisphenol A type epoxy resin (manufactured by DIC Corporation, product name EPICLON EXA-4816, liquid resin; epoxy equivalent: 410 g/eq) in diethylene glycol monoethyl ether acetate at a solid content of 90% (solid content: 90%), the epoxy equivalent calculated as 455.56 g/eq.).
Epoxy resin D: bisphenol A type epoxy resin, manufactured by Nippon Steel Chemical & Material Co., Ltd., product number YD-128, epoxy equivalent 187 g/eq.
- Solvent: methyl ethyl ketone.

(3) Preparation of Test Pieces Test pieces were prepared from the photosensitive adhesive compositions of the Examples, Comparative Examples , and Reference Examples as follows.

The photosensitive adhesive composition was applied to a polyethylene terephthalate (PET) film with an applicator, heated at 80°C for 20 minutes, and then heated further to 110°C and dried by heating at 110°C for 5 minutes to form a dry film with a thickness of 20 μm on the film.

Next, a biaxially oriented polypropylene film was thermocompressed onto the formed dry film at a heating temperature of 70°C to form a cover film on the dry film. After peeling off the formed cover film from the dry film, the dry film was placed over one entire surface of a 0.2 mm thick glass epoxy substrate (manufactured by Risho Kogyo Co., Ltd., product number CS-3357) and heat laminated using a vacuum laminator. The heat lamination conditions were a pressure of 0.5 MPa, a heating temperature of 70°C, and a heating and pressing time of 45 seconds. As a result, a coating of 20 μm thickness made of dry film was formed on the glass epoxy substrate, which was used as the test piece.

(4) Evaluation Test The test pieces of Examples 1 to 18, Comparative Examples 1 and 2, and Reference Example prepared in (3) above were evaluated according to the following procedures. The results are shown in Tables 1 and 2 below.

(4-1) Low Tack In each of the Examples, Comparative Examples , and Reference Examples , when the cover film was peeled off from the dry film, the low tack was evaluated according to the following evaluation criteria.
A: When the cover film was peeled off, there was no loud peeling noise and the cover film could be peeled off smoothly.
B: When the cover film was peeled off, a peeling sound was generated.
C: When the cover film was peeled off, a peeling noise was generated and the photosensitive adhesive composition was transferred to the cover film.

(4-2) Adhesion In each Example and Reference Example , the coating on the test piece was exposed to light over the entire surface, and the coating was cured to prepare two substrates each having a cured layer (adhesive layer) of the photosensitive adhesive composition on the member. The adhesive layers of the two substrates were bonded together and heat-laminated using a vacuum laminator. The heat-laminated conditions were a pressure of 0.5 MPa, a heating temperature of 100°C, and a heating time of 45 seconds. After the heat-laminated, the two substrates were subsequently heated at a heating temperature of 180°C and a heating time of 120 minutes. After heating for 120 minutes, the adhesive strength of the multilayer substrate in which the adhesive layers of the two members were bonded together was measured according to the method for measuring the adhesive strength of the copper foil of a copper-clad laminate of JIS-C6481, and the adhesiveness was evaluated according to the following criteria. In the Reference Example , the multilayer substrate was produced and evaluated without heating again after the heat-laminated.

In each of Comparative Examples 1 and 2, the coating on the test piece was exposed to light over the entire surface to cure the coating, thereby preparing one substrate having a cured layer (adhesive layer) of the photosensitive adhesive composition on a member, and one substrate having no adhesive layer. The adhesive layer of the substrate having an adhesive layer on a member and the substrate having no adhesive layer were bonded together to prepare a multilayer substrate under the same conditions as above, and the substrate was evaluated in the same manner as above.
A: Adhesion strength is higher than 1.5 kN/m.
B: The adhesion strength is higher than 1.3 kN/m and equal to or lower than 1.5 kN/m.
C: The adhesion strength is higher than 1.1 kN/m and equal to or lower than 1.3 kN/m.
D: The adhesion strength is higher than 0.9 kN/m and equal to or lower than 1.1 kN/m.
E: The adhesion strength is higher than 0.7 kN/m and equal to or lower than 0.9 kN/m.
F: The adhesion strength is 0.7 kN/m or less.

(4-3) Opening property A negative mask (a negative mask having a non-exposed portion of a pattern including circular shapes with diameters of 80 μm, 60 μm, 40 μm, and 20 μm) having a predetermined mask pattern was directly applied to the coating of the test piece prepared in (3) from above the PET film, and the coating was irradiated with light having wavelengths of 365 nm and 405 nm under the condition of 250 mJ/cm ² through the negative mask. As a result, vias were formed in the cured product of the coating of the test piece. In the development process, a 1% Na ₂ CO ₃ aqueous solution at 30° C. was sprayed on the coating at a spray pressure of 0.2 MPa for 90 seconds. Then, pure water was sprayed on the coating at a spray pressure of 0.2 MPa for 90 seconds. As a result, the unexposed part of the coating was removed. After exposure and before development, a polyethylene terephthalate film was peeled off from the dry film (coating). The opening property of the test piece obtained after exposure and development was evaluated according to the following criteria.
A: An opening was formed in a circular pattern having a diameter of 20 μm.
B: The circular pattern portion having a diameter of 40 μm was opened, but the circular pattern portion having a diameter of 20 μm was not opened.
C: The circular pattern portion having a diameter of 60 μm was opened, but the circular pattern portion having a diameter of 40 μm was not opened.
D: The circular pattern portion having a diameter of 80 μm was opened, but the circular pattern portion having a diameter of 60 μm was not opened.
E: No opening was observed in the circular pattern portion having a diameter of 80 μm.

(4-4) Moisture Resistance In each of the Examples, Comparative Examples , and Reference Examples , an adhesion sample (multilayer substrate) was prepared in the same manner as the evaluation substrate in "(4-2) Adhesion", and placed in a PCT measuring device and left for 50 hours under conditions of a temperature of 121°C and a humidity of 100%, after which the adhesion state of the two test pieces was observed, and the moisture resistance was evaluated according to the following criteria.
A: No peeling occurred.
B: Peeling occurred.

In addition, the same evaluation as above was performed on samples prepared by changing the heat lamination conditions or the heating conditions after heat lamination as described in "(4-2) Adhesion" of test pieces prepared with the same composition as in Example 2 as follows (Examples 19 to 23). The results are shown in Table 3.
(Example 19)
The heat lamination conditions were a pressure of 0.4 MPa, a heating temperature of 100° C., and a heating time of 45 seconds.
(Example 20)
The heat lamination conditions were a pressure of 1.0 MPa, a heating temperature of 70° C., and a heating time of 45 seconds.
(Example 21)
The heating conditions after the heat lamination were a heating temperature of 150° C. and a heating time of 30 minutes.
(Example 22)
The heating conditions after the heat lamination were a heating temperature of 95° C. and a heating time of 60 minutes.
(Example 23)
The heating conditions after the heat lamination were a heating temperature of 115° C. and a heating time of 60 minutes.

REFERENCE SIGNS LIST 1 First member 2 Second member 10 Multilayer substrate 11 First adhesive layer 12 Second adhesive layer

Claims (1)

forming a first adhesive layer and a second adhesive layer on a first member and a second member, respectively, from a photosensitive adhesive composition or a dry film containing a dried product of the photosensitive adhesive composition;
The first adhesive layer and the second adhesive layer are exposed to light to be cured, and then the first adhesive layer and the second adhesive layer are laminated and adhered to each other, thereby bonding the first member and the second member via the first adhesive layer and the second adhesive layer;
the photosensitive adhesive composition contains a carboxyl group-containing resin (A), a photopolymerization initiator (B), and a photopolymerizable compound (C), and is used to bond the first member and the second member via the first adhesive layer and the second adhesive layer by preparing the first adhesive layer and the second adhesive layer on the first member and the second member, respectively, exposing the first adhesive layer and the second adhesive layer to light to cure them, and then bonding them together;
A method for manufacturing a multilayer board.

Images