JP6905160B1 - Curable adhesive sheet for devices - Google Patents

Abstract

A curable adhesive sheet for a device having an adhesive layer containing the following components (A) and (B). This curable adhesive sheet for devices has an adhesive layer that gives a cured product having excellent low dielectric properties in a high frequency region. Component (A): Polyphenylene ether resin having a vinyl group Component (B): Compound having two or more hydrocarbon groups having a double bond at the terminal

Description

The present invention relates to a curable adhesive sheet for a device having an adhesive layer that gives a cured product having excellent low dielectric properties in a high frequency region. In the present specification, the high frequency region refers to a region of 300 MHz to 300 GHz.

In recent years, with the miniaturization and weight reduction of electronic devices, flexible printed wiring boards (FPCs) are often used as wiring members.
The FPC can be obtained, for example, by forming an electric circuit by etching a copper foil obtained by laminating a copper foil on an insulating resin film such as polyimide (copper-clad laminate).
Further, usually, a coverlay film having an insulating resin base material and an adhesive layer is attached to a copper foil on which an electric circuit is formed to protect the electric circuit.

By the way, in recent years, with respect to communication devices such as smartphones, the frequency of electric signals has been increasing in order to handle a larger amount of data.
However, since the electric signal in the high frequency region is easily converted into heat, the transmission loss tends to increase when the electric signal is made high frequency.

In order to transmit electrical signals in the high-frequency region at high speed and with reduced transmission loss, the dielectric properties of the insulators (base materials, adhesives, etc.) that make up the wiring members have been improved (lower dielectric constant and lower dielectric constant). It has been done to make it a direct connection).

Patent Document 1 describes a laminate with an adhesive layer including a base film and an adhesive layer on at least one surface of the base film, wherein the adhesive layer comprises a specific adhesive composition. A laminate with an adhesive layer is described.
Patent Document 1 also describes that the laminate with an adhesive layer is excellent in electrical characteristics (low dielectric constant, low dielectric loss tangent) and the like.

JP-A-2018-150541

The cured product of the adhesive composition described in Patent Document 1 has low dielectric properties (in the present specification, "low dielectric properties" means "low dielectric constant and low dielectric loss tangent"). ..
However, in order to cope with the further increase in the frequency of electric signals expected in the future, it has been desired to form a cured product having further excellent low dielectric properties in the high frequency region.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a curable adhesive sheet for a device having an adhesive layer that gives a cured product having excellent low dielectric properties in a high frequency region.

In order to solve the above problems, the present inventors have diligently studied a curable adhesive sheet for devices having an adhesive layer. As a result, by using a polyphenylene ether resin having a vinyl group and a compound having two or more hydrocarbon groups having a double bond at the terminal, an adhesive layer that gives a cured product having excellent low dielectric properties in a high frequency region is formed. We have found that it is possible and have completed the present invention.

Thus, according to the present invention, the following curable adhesive sheets for devices [1] to [12] are provided.

[1] A curable adhesive sheet for a device having an adhesive layer containing the following components (A) and (B).
Component (A): Polyphenylene ether resin having a vinyl group Component (B): Compound having two or more hydrocarbon groups having a double bond at the terminal [2] The component (B) is a compound having a heterocyclic skeleton. , [1] The curable adhesive sheet for a device.
[3] The curable adhesive sheet for a device according to [2], wherein the heterocyclic skeleton is an isocyanurate skeleton or a glycoluril skeleton.
[4] The curable adhesive sheet for a device according to any one of [1] to [3], wherein the molecular weight of the component (B) is 1,000 or less.
[5] The curable adhesive sheet for a device according to any one of [1] to [4], wherein the component (B) has 2 hydrocarbon groups having a double bond at the end.
[6] The curable adhesive sheet for a device according to any one of [1] to [5], wherein the component (B) is a compound represented by the following formula.

(In the formula, R represents a saturated hydrocarbon group having 5 to 15 carbon atoms.)
[7] The curable adhesive sheet for a device according to any one of [1] to [6], wherein the adhesive layer contains an olefin resin as a binder resin.
[8] The curable adhesive sheet for devices according to [1] to [7], wherein the adhesive layer contains a resin having a reactive functional group as a binder resin.
[9] The curable adhesive sheet for a device according to any one of [1] to [8], wherein the adhesive layer further contains the following component (D).
Component (D) Component: Cationic Polymerization Initiator [10] The adhesive layer is a layer containing a compound having a cyclic ether group or a layer not containing a compound having a cyclic ether group and having a cyclic ether group. The curable adhesive sheet for a device according to any one of [1] to [9], wherein the content of the compound is less than 5% by mass in the adhesive layer.
[11] The adhesive layer is a layer containing a liquid compound at 25 ° C., and the content of the liquid compound at 25 ° C. is 5% by mass or more in the adhesive layer [1] to [ 10] The curable adhesive sheet for a device according to any one of.
[12] The curable adhesive sheet for a device according to [11], wherein at least one of the compounds liquid at 25 ° C. is a compound having two or more hydrocarbon groups having a double bond at the terminal.
[13] It has two or more hydrocarbon groups having a double bond at the terminal, and the content of the liquid compound at 25 ° C. is 90% by mass or more based on the total amount of the liquid compound at 25 ° C. [12]. ] The curable adhesive sheet for the device described in.

According to the present invention, there is provided a curable adhesive sheet for a device having an adhesive layer that gives a cured product having excellent low dielectric properties in a high frequency region.

The curable adhesive sheet for a device of the present invention has an adhesive layer containing the following components (A) and (B).
Component (A): Polyphenylene ether resin having a vinyl group (B) Component: A compound having two or more hydrocarbon groups having a double bond at the terminal.

[Component (A): Polyphenylene ether resin having a vinyl group]
The adhesive layer of the curable adhesive sheet for devices of the present invention contains a polyphenylene ether resin having a vinyl group (hereinafter, may be referred to as "polyphenylene ether resin (A)") as a component (A).
The polyphenylene ether resin refers to a resin having a polyphenylene skeleton in the main chain.
The polyphenylene skeleton is the following formula

It means a skeleton having a repeating unit represented by, or a repeating unit in which a hydrogen atom in the above formula is substituted.

Since the polyphenylene ether resin (A) has a polyphenylene ether skeleton, the cured product of the adhesive layer containing the polyphenylene ether resin (A) is excellent in low dielectric properties.

Examples of the polyphenylene ether skeleton in the polyphenylene ether resin (A) include those represented by the following formula (1).

In the formula (1), X is a divalent group represented by the following formula (2) or the formula (3), and Y is a divalent group represented by the following formula (4) independently. The group, a and b are integers from 0 to 100, and at least one of a and b is 1 or more. * Represents a bond (hereinafter the same).

In the formula (2), R ^{1 to} R ⁸ independently represent a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group, and are preferably a hydrogen atom or a methyl group.

In the formula (3), R ^{9 to} R ¹⁶ independently represent a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group, and are preferably a hydrogen atom or a methyl group. A represents a linear, branched, or cyclic divalent hydrocarbon group having 20 or less carbon atoms.

In the formula (4), R ^{17 to} R ²⁰ independently represent a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group, and are preferably a hydrogen atom or a methyl group.

Examples of the polyphenylene ether skeleton in the polyphenylene ether resin (A) include those represented by the following formula (5).

Since the polyphenylene ether resin (A) has a vinyl group, the cured product of the adhesive layer containing the polyphenylene ether resin (A) is excellent in low dielectric properties, crosslinkability and heat resistance.
The vinyl group in the polyphenylene ether resin (A) may form a part of a hydrocarbon-based substituent, such as a vinylbenzyl group and a vinylnaphthyl group. That is, the polyphenylene ether resin (A) is formed by bonding a vinyl group or a vinyl group-containing hydrocarbon group to the polyphenylene ether skeleton.

As the polyphenylene ether resin (A), one having a vinyl group or a vinyl group-containing hydrocarbon group at both ends of the polyphenylene ether skeleton is preferable because a cured product having excellent low dielectric properties can be easily obtained.

Such a polyphenylene ether resin (A) can be obtained by forming a polyphenylene ether skeleton and then introducing a vinyl group or a vinyl group-containing hydrocarbon group at both ends.
Specifically, a bifunctional phenol compound and a monofunctional phenol compound are reacted to obtain a polymer having phenolic hydroxyl groups at both ends, and then 4- (chloromethyl) styrene is used to change the terminal phenolic hydroxyl groups to vinyl. By benzyl etherification, a polyphenylene ether resin (A) having vinyl benzyl groups at both ends of the polyphenylene ether skeleton can be obtained.

Examples of the polyphenylene ether resin (A) include those represented by the following formula (6).

As the polyphenylene ether resin (A), a commercially available product can also be used. Examples of commercially available products include OPE-2St (modified polyphenylene ether resin having vinylbenzyl groups at both ends) manufactured by Mitsubishi Gas Chemical Company.

The weight average molecular weight (Mw) of the polyphenylene ether resin (A) is preferably 500 to 5,000, more preferably 500 to 3,000.
The weight average molecular weight (Mw) of the polyphenylene ether resin (A) can be determined as a standard polystyrene-equivalent value by performing gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.

As the polyphenylene ether resin (A), one type can be used alone, or two or more types can be used in combination.

The content of the polyphenylene ether resin (A) is preferably 10% by mass or more, more preferably 15 to 50% by mass in the adhesive layer. The content of the polyphenylene ether resin (A) may be 10 to 40% by mass in the adhesive layer when the content of the binder resin described later is large.
When the content of the polyphenylene ether resin (A) is 10% by mass or more in the adhesive layer, it becomes easy to obtain a cured product having excellent low dielectric properties while improving the curability of the adhesive layer.

[Component (B): Compound having two or more hydrocarbon groups having a double bond at the terminal]
The adhesive layer of the curable adhesive sheet for devices of the present invention is a compound having two or more hydrocarbon groups having a double bond at the terminal as the component (B) (hereinafter referred to as "polyfunctional compound (B)"). There is.).

Since the polyfunctional compound (B) has two or more hydrocarbon groups having a double bond at the terminal, the cured product of the adhesive layer containing the polyfunctional compound (B) has low dielectric properties, crosslinkability and adhesion. Excellent in strength.
The hydrocarbon group having a double bond at the terminal has preferably 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms.
The hydrocarbon group having a double bond at the terminal includes a vinyl group, an allyl group, a 3-butenyl group, a 4-pentenyl group, a 5-hexenyl group, an isopropenyl group, a 1-methyl-2-propenyl group, and a vinylbenzyl group. , Vinyl naphthyl group and the like. Among these, an allyl group is preferable.

The number of hydrocarbon groups having a double bond at the terminal contained in the polyfunctional compound (B) is 2 or more. When the number of hydrocarbon groups having a double bond at the terminal is 2 or more, a crosslinked structure is formed in the cured product, and a cured product having better adhesive strength and heat resistance can be formed.
In addition, the number of hydrocarbon groups having double bonds at the ends is increased from the viewpoint of suppressing the occurrence of cracks in the adhesive layer after curing because the crosslinked structure formed in the cured product is appropriately sparse. , Preferably 2-4, more preferably 2. When the number of hydrocarbon groups having a double bond at the terminal is 2, the amount of the polyfunctional compound (B) blended is large while exhibiting the curability of the polyfunctional compound (B). Also, the curing shrinkage of the adhesive layer can be suppressed, and when the curable adhesive sheet for a device is used for adhering a plate-shaped member such as a circuit board, the warp of the plate-shaped member can be reduced. When the double bond of a hydrocarbon group having a double bond at the terminal is polymerized, the distance between the monomers before the polymerization (that is, the distance between the double bonds indicated by the Van der Waals distance) is increased between the repeating units by the polymerization. As the number of hydrocarbon groups having a double bond at the end increases, the curing shrinkage of the curable adhesive layer tends to increase. By selecting a compound having a double bond at the terminal and having 2 hydrocarbon groups as the polyfunctional compound (B), it is possible to efficiently suppress curing shrinkage.

The polyfunctional compound (B) preferably has a heterocyclic skeleton. Since the polyfunctional compound (B) has a heterocyclic skeleton, it becomes easy to obtain a cured product having excellent adhesive strength and low dielectric properties.
Examples of the heterocyclic skeleton include an isocyanurate skeleton and a glycoluril skeleton.

Examples of the polyfunctional compound (B) having an isocyanurate skeleton include a compound represented by the following formula (7) or (8).

In the formula (7), R ²¹ and R ²² each independently represent a hydrocarbon group having a double bond at the terminal, and R ²³ is a saturated hydrocarbon group having 1 to 15 carbon atoms and 1 to 15 carbon atoms. Represents an alkoxy group-substituted alkyl group.
In formula (8), R ^{24 to} R ²⁶ each independently represent a hydrocarbon group having a double bond at the end.

The hydrocarbon groups having double bonds at the ends represented by ^{R 21} , R ²² , R ²⁴ , R ²⁵ , and R ^{26 are as described above.}

The ^{saturated hydrocarbon group represented by R 23} has 1 to 15 carbon atoms, preferably 5 to 15 carbon atoms, and more preferably 8 to 15 carbon atoms. Examples of the saturated hydrocarbon group represented by R ²³ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a t-butyl group, an s-butyl group, an isobutyl group and an n-pentyl group. n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, etc. Can be mentioned.

The ^{alkoxy group-substituted alkyl group represented by R 23} has 2 to 15 carbon atoms, preferably 2 to 12 and more preferably 3 to 10. Examples of the alkoxy group-substituted alkyl group represented by R ²³ include a methoxymethyl group, an ethoxymethyl group, a 2-methoxyethoxymethyl group, a benzyloxymethyl group and the like.

Examples of the polyfunctional compound (B) having a glycoluril skeleton include a compound represented by the following formula (9).

In formula (9), R ^{27 to} R ³⁰ each independently represent a hydrocarbon group having 1 to 15 carbon atoms, and at least two of these are hydrocarbon groups having a double bond at the terminal. R ³¹ and R ³² represent hydrogen atoms or saturated hydrocarbon groups having 1 to 15 carbon atoms.

Among these, a compound having an isocyanurate skeleton is preferable as the polyfunctional compound (B), and a compound represented by the formula (7) is more preferable, because a cured product having an appropriate crosslink density can be easily obtained. From the viewpoint of further improving the low dielectric property of the cured product of the adhesive layer and adjusting the molecular weight of the compound in an appropriate range, the compound represented by the following formula is more preferable.

In the formula, R represents a saturated hydrocarbon group having 5 to 15 carbon atoms, and a saturated hydrocarbon group having 8 to 15 carbon atoms is preferable.

As the polyfunctional compound (B), a commercially available product can be used.
For example, examples of the compound represented by the formula (7) include L-DAIC (manufactured by Shikoku Chemicals Corporation). Examples of the compound represented by the formula (8) include TAIC (manufactured by Mitsubishi Chemical Corporation). Examples of the compound represented by the formula (9) include TA-G (manufactured by Shikoku Chemicals Corporation).

The molecular weight of the polyfunctional compound (B) is preferably 1,000 or less, more preferably 800 or less, and even more preferably 500 or less.
The polyfunctional compound (B) having a molecular weight of 1,000 or less tends to satisfy the requirement of being a liquid at 25 ° C. As will be described later, when the polyfunctional compound (B) is a compound that is liquid at 25 ° C., the adhesive layer has improved adhesiveness at room temperature.
"Liquid at 25 ° C" means having fluidity at 25 ° C. For example, a compound that is liquid at 25 ° C. is a compound having a viscosity of 2 to 10000 mPa · s measured at 25 ° C. and 1.0 rpm using an E-type viscometer.

The molecular weight of the polyfunctional compound (B) is preferably 100 or more, more preferably 200 or more, and even more preferably 275 or more.
The polyfunctional compound (B) having a high molecular weight has the desired physical properties because the drying step when forming the adhesive layer and the step of curing the adhesive layer are difficult to volatilize even in the thermosetting step. A cured product can be easily obtained.
The boiling point of the polyfunctional compound (B) is preferably 175 to 350 ° C, more preferably 200 to 300 ° C. The 5% weight loss temperature of the polyfunctional compound (B) is preferably 175 to 350 ° C., more preferably 200 to 300 ° C.

The polyfunctional compound (B) can be used alone or in combination of two or more.
The content of the polyfunctional compound (B) is preferably 5% by mass or more, more preferably 6 to 50% by mass, and further preferably 10 to 30% by mass in the adhesive layer. The content of the polyfunctional compound (B) may be 6 to 30% by mass in the adhesive layer when the content of the binder resin described later is large.
When the content of the polyfunctional compound (B) is 5% by mass or more in the adhesive layer, a cured product having excellent adhesive strength and low dielectric properties can be easily obtained.
Further, as will be described later, from the viewpoint of the adhesiveness of the adhesive layer at room temperature, it is preferable that the adhesive layer contains a compound that is liquid at 25 ° C., but the compound that is liquid at 25 ° C. is polyfunctional. It is preferably the sex compound (B). That is, it is considered that a compound having a cyclic ether group and liquid at 25 ° C. is also effective in terms of improving the adhesiveness of the adhesive layer at room temperature and promoting the curing reaction. However, if a compound having a cyclic ether group is used, it may be difficult to obtain a cured product having excellent low dielectric properties. In this respect, the polyfunctional compound (B) has a large content in the adhesive layer because the hydrocarbon group having a double bond is involved in the curing reaction, unlike the case where the compound having a cyclic ether group is used. Also tends to be able to maintain the low dielectric properties of the cured product. Therefore, if the polyfunctional compound (B) is liquid at 25 ° C., the adhesive layer can contain the compound liquid at 25 ° C. in a suitable amount without impairing the low dielectric property of the cured product. Therefore, the content of the polyfunctional compound (B), which is liquid at 25 ° C., is preferably 5% by mass or more, more preferably 6 to 50% by mass, and 10 to 30% by mass in the adhesive layer. It is more preferably mass%. The content of the polyfunctional compound (B), which is liquid at 25 ° C., may be 6 to 30% by mass in the adhesive layer when the content of the binder resin described later is large.

[(C) component: binder resin]
The adhesive layer of the curable adhesive sheet for devices of the present invention may contain a binder resin as the component (C).
As will be described later, the adhesive layer of the curable adhesive sheet for devices of the present invention may contain a liquid compound at 25 ° C. In such a case, the adhesive layer containing the binder resin makes it easier to maintain the shape of the adhesive layer.

The binder resin is not particularly limited as long as it is a polymer component that imparts film-forming property and flexibility to the adhesive layer.
Binder resins include olefin resins, acrylic polymers, polyester resins, polyvinyl alcohol resins, polyvinyl butyral, polyvinyl chloride, phenoxy resins, polyamide resins, cellulose-based materials, polyvinyl ethers, polyimide resins, and styrene-isoprene-styrene blocks. Examples thereof include polymers, styrene-butadiene-styrene block copolymers and the like.

As the binder resin, an olefin resin is preferable because a cured product having excellent low dielectric properties can be easily obtained.
The olefin-based resin refers to a polymer containing a repeating unit derived from an olefin-based monomer. The olefin-based resin may be a polymer consisting of only repeating units derived from the olefin-based monomer, or the repeating units derived from the olefin-based monomer and a monomer copolymerizable with the olefin-based monomer. A polymer composed of repeating units derived from the same may be used, but from the viewpoint that a cured product having excellent low dielectric properties can be easily obtained, a polymer consisting only of repeating units derived from an olefin-based monomer is preferable. ..

As the olefin-based monomer, α-olefin having 2 to 8 carbon atoms is preferable, ethylene, propylene, 1-butene, isobutylene, or 1-hexene is more preferable, and ethylene or propylene is further preferable. These olefin-based monomers may be used alone or in combination of two or more.
Examples of the monomer copolymerizable with the olefin-based monomer include vinyl acetate, (meth) acrylic acid ester, and styrene. Here, "(meth) acrylic acid" means acrylic acid or methacrylic acid (the same shall apply hereinafter).
As the monomer copolymerizable with these olefin-based monomers, one type can be used alone, or two or more types can be used in combination.

Examples of olefin resins include ultra-low density polyethylene (VLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), linear low density polyethylene, polypropylene (PP), and ethylene-propylene. Examples thereof include copolymers, olefin-based elastomers (TPO), ethylene-vinyl acetate copolymers (EVA), ethylene- (meth) acrylic acid copolymers, and ethylene- (meth) acrylic acid ester copolymers.

As the binder resin, a resin having a reactive functional group is preferable. By using a resin having a reactive functional group as the binder resin, a crosslinked structure in which the binder resin is involved can be constructed in the cured product of the adhesive layer, and a cured product having excellent heat resistance can be formed. Further, by using a resin having a reactive functional group as a binder resin, a cured product having sufficient adhesive strength can be formed even on a poorly adhesive base material or the like.

Reactive functional groups include carboxyl groups, carboxylic acid anhydride groups, carboxylic acid ester groups, hydroxyl groups, epoxy groups, amide groups, ammonium groups, nitrile groups, amino groups, imide groups, isocyanate groups, acetyl groups and thiol groups. Examples thereof include an ether group, a thioether group, a sulfone group, a phosphone group, a nitro group, a urethane group, an alkoxysilyl group, a silanol group and a halogen atom.

Examples of the resin having a reactive functional group include a modified polyolefin resin described later, a phenoxy resin and a cellulosic material among the above-mentioned binder resins, and a resin other than the olefin-based resin among the above-mentioned binder resins. Modified products and the like can be mentioned.

A modified polyolefin resin is preferable as the binder resin because it is easy to obtain a cured product having excellent low dielectric properties and because it is easy to obtain a cured product having excellent heat resistance.
The modified polyolefin resin is an olefin resin having a reactive functional group introduced therein, which is obtained by subjecting an olefin resin as a precursor to a modification treatment using a modifier (a compound having a functional group in the molecule). be.

As the modified polyolefin resin, an acid-modified polyolefin resin is preferable because a cured product having a higher adhesive strength is formed.
The acid-modified polyolefin resin refers to an olefin-based resin graft-modified with an acid or an acid anhydride. For example, an unsaturated carboxylic acid or an unsaturated carboxylic acid anhydride (hereinafter, may be referred to as “unsaturated carboxylic acid or the like”) is reacted with an olefin resin to introduce a carboxyl group or a carboxylic acid anhydride group ( Those that have been graft-modified) can be mentioned.

Examples of the unsaturated carboxylic acid that reacts with the olefin resin include unsaturated carboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, tetrahydrophthalic acid, and aconitic acid; maleic anhydride, itaconic anhydride, and the like. Unsaturated carboxylic acid anhydrides such as glutaconic anhydride, citraconic anhydride, aconitic anhydride, norbornene dicarboxylic acid anhydride, and tetrahydrophthalic acid anhydride;
These can be used alone or in combination of two or more. Among these, maleic anhydride is preferable because a cured product having better adhesive strength can be easily obtained.

The amount of unsaturated carboxylic acid or the like to be reacted with the olefin resin is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass, and further preferably 0 with respect to 100 parts by mass of the olefin resin. .2-1 parts by mass. By curing the adhesive composition containing the acid-modified polyolefin resin thus obtained, a cured product having better adhesive strength can be formed.

The method for introducing the unsaturated carboxylic acid unit or the unsaturated carboxylic acid anhydride unit into the olefin resin is not particularly limited. For example, a method in which an olefin resin and an unsaturated carboxylic acid are heated and melted above the melting point of the olefin resin to react in the presence of a radical generator such as an organic peroxide or an azonitrile, or an olefin. After dissolving the system resin and unsaturated carboxylic acid or the like in an organic solvent, the unsaturated carboxylic acid or the like is graft-copolymerized with the olefin resin by a method of heating, stirring and reacting in the presence of a radical generator. The method can be mentioned.

As the acid-modified polyolefin resin, a commercially available product can also be used. Examples of commercially available products include Admer (registered trademark) (manufactured by Mitsui Chemicals), Unistor (registered trademark) (manufactured by Mitsui Chemicals), BondyRam (manufactured by Polyram), orevac (registered trademark) (manufactured by ARKEMA), and the like. Modic (registered trademark) (manufactured by Mitsubishi Chemical Corporation) and the like can be mentioned.

The number average molecular weight (Mn) of the binder resin is preferably 10,000 to 150,000, more preferably 30,000 to 100,000.
The number average molecular weight (Mn) of the binder resin can be determined as a standard polystyrene-equivalent value by performing gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.

As the binder resin, one type can be used alone, or two or more types can be used in combination.
When the adhesive layer contains a binder resin, the content of the binder resin is preferably 40 to 80% by mass, more preferably 45 to 80% by mass in the adhesive layer.
When the content of the binder resin is 40 to 80% by mass in the adhesive layer, it becomes easy to obtain an adhesive layer having both shape retention and tackiness.

[Component (D): Cationic polymerization initiator]
The adhesive layer of the curable adhesive sheet for devices of the present invention may contain a cationic polymerization initiator as the component (D).
The cationic polymerization initiator is preferable because it can efficiently proceed with the polymerization reaction of the components (A) and (B) and can improve the storage stability of the adhesive layer as compared with other curing agents.
Examples of the cationic polymerization initiator include a thermal cationic polymerization initiator and a photocationic polymerization initiator, and a thermal cationic polymerization initiator that can be polymerized by a simple step is preferable.

The thermal cationic polymerization initiator is a compound capable of generating a cationic species that initiates polymerization by heating.
Examples of the thermal cationic polymerization initiator include sulnifoam salt, quaternary ammonium salt, phosphonium salt, diazonium salt, iodonium salt and the like.

Examples of the sulfonium salt include triphenylsulfonium tetrafluoroborate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluoroalcinate, tris (4-methoxyphenyl) sulfonium hexafluoroalcinate, and diphenyl (4-phenylthiophenyl) sulfonium. Hexafluoroalcinate and the like can be mentioned.

A commercially available product can also be used as the sulfonium salt. Commercially available products include Adeka Opton SP-150, Adeka Opton SP-170, Adeka Opton CP-66, Adeka Opton CP-77 (above, manufactured by Adeka), Sun Aid SI-60L, Sun Aid SI-80L, Sun Aid SI-100L, Sun Aid SI- B2A, Sun Aid SI-B3 (above, manufactured by Sanshin Chemical Co., Ltd.), CYRACURE UVI-6974, CYRACURE UVI-6990 (above, manufactured by Union Carbide), UVI-508, UVI-509 (above, manufactured by General Electric Co., Ltd.) ), FC-508, FC-509 (above, manufactured by Minnesota Mining and Manufacturing), CD-1010, CD-1011 (above, manufactured by Surftmer), CI series products (manufactured by Nippon Soda), etc. Can be mentioned.

Examples of the quaternary ammonium salt include tetrabutylammonium tetrafluoroborate, tetrabutylammonium hexafluorophosphate, tetrabutylammonium hydrogen sulfate, tetraethylammonium tetrafluoroborate, tetraethylammonium p-toluenesulfonate, N, N-dimethyl-N-. Benzylanilinium hexafluoroammonate, N, N-dimethyl-N-benzylanilinium tetrafluoroborate, N, N-dimethyl-N-benzylpyridinium hexafluoroantimonate, N, N-diethyl-N-benzyltrifluoromethanesulfonate , N, N-dimethyl-N- (4-methoxybenzyl) pyridinium hexafluoroammonate, N, N-diethyl-N- (4-methoxybenzyl) toluidinium hexafluoroammonate and the like.

Examples of the phosphonium salt include ethyltriphenylphosphonium hexafluoroantimonate and tetrabutylphosphonium hexafluoroantimonate.

Examples of the diazonium salt include AMERICURE (manufactured by American Can) and ULTRASET (manufactured by ADEKA CORPORATION).

Examples of the iodonium salt include diphenyl iodonium hexafluoroalcinate, bis (4-chlorophenyl) iodonium hexafluoroalcinate, bis (4-bromophenyl) iodonium hexafluoroalcinate, and phenyl (4-methoxyphenyl) iodonium hexafluoroalcinate. Can be mentioned. In addition, as commercial products, UV-9310C (manufactured by Toshiba Silicone), Photoinitiator 2074 (manufactured by Rhone-Poulenc), UVE series products (manufactured by General Electric), FC series products (Minnesota Mining and Manufacturing) (Manufactured by the company) can also be used.

The cationic polymerization initiator may be used alone or in combination of two or more.
When the adhesive layer contains a cationic polymerization initiator, the content of the cationic polymerization initiator is preferably 0 with respect to 100 parts by mass of the total amount of the polyphenylene ether resin (A) and the polyfunctional compound (B). .1 to 6 parts by mass, more preferably 0.3 to 5 parts by mass, still more preferably 0.5 to 4 parts by mass.

The adhesive layer may contain a reactive curing agent other than the cationic polymerization initiator. Examples of the reactive curing agent other than the cationic polymerization initiator include amine compounds such as benzylmethylamine and 2,4,6-trisdimethylaminomethylphenol; 2-methylimidazole, 2-ethyl-4-methylimidazole, and 2-hepta. Imidazole compounds such as decylimidazole; Lewis acids such as boron trifluoride / monoethylamine complex, boron trifluoride / piperazine complex; peroxides such as di (t-butylperoxy) diisopropylbenzene; Agents can be mentioned.

[Component (E): Silane coupling agent]
The adhesive layer of the curable adhesive sheet for devices of the present invention may contain a silane coupling agent as the component (E).
When the adhesive layer contains a silane coupling agent, it becomes easy to obtain a cured product having better adhesive strength.

As the silane coupling agent, a known silane coupling agent can be used. Of these, an organosilicon compound having at least one alkoxysilyl group in the molecule is preferable.
Examples of the silane coupling agent include 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-acryloxypropyltri. Silane coupling agent having a (meth) acryloyl group such as methoxysilane;
A silane coupling agent having a vinyl group such as vinyltrimethoxysilane, vinyltriethoxysilane, dimethoxymethylvinylsilane, diethoxymethylvinylsilane, trichlorovinylsilane, and vinyltris (2-methoxyethoxy) silane;
2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 8-glycid Silane coupling agent having an epoxy group such as xioctyltrimethoxysilane;
Silane coupling agent having a styryl group such as p-styryltrimethoxysilane and p-styryltriethoxysilane;

N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane , 3-Aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethylbutylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N -(Vinylbenzyl) -2-aminoethyl-3-aminopropyl Asilane coupling agent having an amino group such as a hydrochloride of trimethoxysilane;
A silane coupling agent having a ureido group such as 3-ureidopropyltrimethoxysilane and 3-ureidopropyltriethoxysilane;
Silane coupling agent having halogen atoms such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane;
A silane coupling agent having a mercapto group such as 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane;
Silane coupling agent having a sulfide group such as bis (trimethoxysilylpropyl) tetrasulfide and bis (triethoxysilylpropyl) tetrasulfide;
Silane coupling agent having an isocyanate group such as 3-isocyanatepropyltrimethoxysilane and 3-isocyanatepropyltriethoxysilane;
A silane coupling agent having an allyl group such as allyltrichlorosilane, allyltriethoxysilane, and allyltrimethoxysilane;
Examples thereof include silane coupling agents having a hydroxyl group such as 3-hydroxypropyltrimethoxysilane and 3-hydroxypropyltriethoxysilane; and the like.

The silane coupling agent may be used alone or in combination of two or more.
When the adhesive layer contains a silane coupling agent, the content of the silane coupling agent is preferably 0.01 to 5% by mass, more preferably 0.05 to 1% by mass in the adhesive layer.

[Cyclic ether compound]
The adhesive layer of the curable adhesive sheet for devices of the present invention may or may not contain a compound having a cyclic ether group.

Examples of the cyclic ether group include an oxylan group (epoxy group), an oxetane group (oxetanyl group), a tetrahydrofuryl group, a tetrahydropyranyl group and the like.
In the present specification, the oxylan group includes a group having an oxylan structure such as a glycidyl group, a glycidyl ether group, and an epoxycyclohexyl group.

A cured product of the adhesive layer containing a compound having a cyclic ether group tends to have excellent adhesive strength.
However, since a hydroxyl group is generated by ring-opening of the cyclic ether group, when the adhesive layer contains a compound having a cyclic ether group, it may be difficult to obtain a cured product having excellent low dielectric properties.

Further, since the adhesive layer of the curable adhesive sheet for devices of the present invention contains the above component (B), the cured product can be sufficiently adhered without utilizing the action and effect of the compound having a cyclic ether group. Has strength.
Therefore, it is preferable that the adhesive layer of the curable adhesive sheet for devices of the present invention contains almost no compound having a cyclic ether group.
The content of the compound having a cyclic ether group is preferably less than 5% by mass, more preferably 3% by mass or less in the adhesive layer.

[Other ingredients]
The adhesive layer of the curable adhesive sheet for devices of the present invention may contain other components as long as the effects of the present invention are not impaired.
Examples of other components include additives such as ultraviolet absorbers, antistatic agents, light stabilizers, antioxidants, resin stabilizers, fillers, pigments, bulking agents, and softeners.
These can be used alone or in combination of two or more.
When the adhesive layer contains these additives, the content thereof can be appropriately determined according to the purpose.
[Adhesive layer]

The adhesive layer of the curable adhesive sheet for devices of the present invention preferably contains a liquid compound at 25 ° C.
As described above, the adhesive layer of the curable adhesive sheet for devices of the present invention contains the polyphenylene ether resin (A). Since the polyphenylene ether resin (A) has a relatively rigid molecular structure, the adhesive layer containing the polyphenylene ether resin (A) may be inferior in stickability at room temperature (for example, 25 ° C., the same applies hereinafter).
In this respect, by impregnating the adhesive layer with a compound that is liquid at 25 ° C., the adhesiveness of the adhesive layer at room temperature is improved.

When the adhesive layer contains a compound that is liquid at 25 ° C., the content thereof is preferably 5% by mass or more, more preferably 6 to 50% by mass, in the adhesive layer from the above viewpoint. Yes, more preferably 10 to 30% by mass. The content of the compound liquid at 25 ° C. may be 6 to 30% by mass in the adhesive layer when the content of the binder resin described later is large.

At least one of the compounds liquid at 25 ° C. is preferably a compound having two or more hydrocarbon groups having a double bond at the terminal (that is, a compound satisfying the requirements of the component (B)).
By using a compound that satisfies the requirements of the component (B) as a liquid compound at 25 ° C., it is possible to achieve both the adhesiveness of the adhesive layer at room temperature and the low dielectric property of the cured product at a high level. ..
From this viewpoint, the content of the liquid compound at 25 ° C., which has two or more hydrocarbon groups having a double bond at the terminal, is 90% by mass or more based on the total amount of the liquid compound at 25 ° C. It is preferably 95% by mass or more, more preferably 95% by mass or more.

The method for forming the adhesive layer of the curable adhesive sheet for devices of the present invention is not particularly limited. For example, the cast method can be used to form the adhesive layer.
When the adhesive layer is formed by a casting method, a known method is used to apply the adhesive composition as a raw material to the peeled layer surface of the base material or the peeling film, and the obtained coating film is applied. By drying, an adhesive layer can be formed.

The adhesive composition contains the above-mentioned components (A) and (B) and other optional components.
The adhesive composition may further contain a solvent.
As the solvent, aromatic hydrocarbon solvents such as benzene and toluene; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone; n-pentane, n-hexane and n- An aliphatic hydrocarbon solvent such as heptane; an alicyclic hydrocarbon solvent such as cyclopentane, cyclohexane, and methylcyclohexane; and the like can be mentioned.
These solvents may be used alone or in combination of two or more.
When the adhesive composition contains a solvent, the content of the solvent can be appropriately determined in consideration of coatability and the like.
The adhesive composition can be prepared by appropriately mixing and stirring each component according to a conventional method.

Examples of the method for applying the adhesive composition include a spin coating method, a spray coating method, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, and a gravure coating method.

Examples of the method for drying the coating film include conventionally known drying methods such as hot air drying, hot roll drying, and infrared irradiation.
The conditions for drying the coating film are, for example, 80 to 150 ° C. for 30 seconds to 5 minutes.

The thickness of the adhesive layer is not particularly limited, but is usually 1 to 50 μm, preferably 1 to 25 μm, and more preferably 5 to 25 μm. The adhesive layer having a thickness within the above range is suitably used as a material for forming a circuit board.
The thickness of the adhesive layer can be measured according to JIS K 7130 (1999) using a known thickness gauge.

The adhesive layer of the curable adhesive sheet for devices of the present invention has curability. Curability is thermosetting from the viewpoint that polymerization is possible by a simple process and that the thermosetting method is often used in circuit board applications, which is suitable for the use of the curable adhesive sheet for devices of the present invention. It is preferably sex. In this case, heating the adhesive layer cures the adhesive layer.

When the curable adhesive sheet for a device of the present invention is thermosetting, the conditions for thermosetting the adhesive layer are not particularly limited.
The heating temperature is 80 to 200 ° C., preferably 90 to 190 ° C. from the viewpoint of efficiently proceeding the reaction of the polyphenylene ether resin having a vinyl group.
The heating time is usually 30 minutes to 12 hours, preferably 1 to 6 hours.
Further, when the curable adhesive sheet for a device of the present invention is photocurable, the adhesive layer can be irradiated with, for example, ultraviolet rays as light rays for photocuring the adhesive layer.

The cured product of the adhesive layer is excellent in low dielectric properties in the high frequency region.
The relative permittivity of the cured product of the adhesive layer at 23 ° C. and a frequency of 1 GHz (hereinafter, this relative permittivity may be referred to as “relative permittivity (α)”) is preferably 2.50 or less. More preferably, it is 2.40 or less.
There is no particular lower limit for the relative permittivity (α), but it is usually 2.00 or more.

The dielectric loss tangent of the cured product of the adhesive layer at 23 ° C. and a frequency of 1 GHz (hereinafter, this dielectric loss tangent may be referred to as “dielectric loss tangent (β)”) is preferably 0.0030 or less, and more. It is preferably 0.0020 or less.
There is no particular lower limit for the dielectric loss tangent (β), but it is usually 0.0001 or more.

The measurement sample of the relative permittivity (α) and the dielectric loss tangent (β) is not particularly limited as long as the adhesive layer is sufficiently cured.
For example, if the adhesive layer to be measured has recommended curing conditions, the cured adhesive layer cured under the recommended conditions is used as a measurement sample for the relative permittivity (α) and the dielectric loss tangent (β). If the adhesive layer is thermosetting and there is no recommended curing condition or it is unknown, for example, the cured product obtained at 160 ° C. for 1 hour is subjected to relative permittivity (α) and dielectric loss tangent (β). ) May be used as a measurement sample.
The relative permittivity (α) and the dielectric loss tangent (β) can be measured according to the method described in Examples.

[Curable adhesive sheet for devices]
The curable adhesive sheet for a device of the present invention may have a base material in addition to the adhesive layer.
As the base material, a resin film can usually be used.
Resin components of the resin film include polyimide, polyamide, polyamideimide, polyphenylene ether, polyetherketone, polyetheretherketone, polyolefin, polyester, polycarbonate, polysulfone, polyethersulfone, polyphenylene sulfide, polyarylate, acrylic resin, cyclo. Examples thereof include olefin-based polymers, aromatic polymers, polyurethane-based polymers, and liquid crystal polymer films.
The thickness of the base material is not particularly limited, but is preferably 10 to 500 μm, more preferably 10 to 300 μm, and even more preferably 15 to 200 μm.

The curable adhesive sheet for a device of the present invention may have a release film in addition to the adhesive layer.
The release film functions as a protective film for the adhesive layer until the curable adhesive sheet for the device is used. Further, when the curable adhesive sheet for a device does not have a base material, the release film functions as a support in the manufacturing process of the curable adhesive sheet for a device.
When the curable adhesive sheet for a device of the present invention is used, the release film is usually peeled off.

As the release film, a conventionally known one can be used. For example, a base material for a release film having a release layer peeled with a release agent can be mentioned.
As the base material for the release film, paper base materials such as glassin paper, coated paper, and high-quality paper; laminated paper obtained by laminating a thermoplastic resin such as polyethylene on these paper base materials; polyethylene terephthalate resin, polybutylene terephthalate resin, etc. Plastic films such as polyethylene naphthalate resin, polypropylene resin, and polyethylene resin; and the like.

Examples of the release agent include rubber-based elastomers such as silicone-based resins, olefin-based resins, isoprene-based resins, and butadiene-based resins, long-chain alkyl-based resins, alkyd-based resins, and fluorine-based resins.
The thickness of the release film is not particularly limited, but is usually about 20 to 250 μm.

When the curable adhesive sheet for a device of the present invention has a release film, it may have one release film on each side of the adhesive layer, for a total of two release films, or on one side of the adhesive layer. Only may have a release film. When the curable adhesive sheet for a device has two release films on the front and back sides of the adhesive layer, the release force of each release film may be different.

As described above, the cured product of the adhesive layer of the curable adhesive sheet for devices of the present invention is excellent in low dielectric properties in the high frequency region.
Therefore, the curable adhesive sheet for devices of the present invention is suitably used when forming a member in a device that requires low dielectric properties.
For example, by using the curable adhesive sheet for devices of the present invention, the adhesive cured product layer constituting the circuit board can be efficiently formed. That is, the curable adhesive sheet for devices of the present invention can be used as a curable adhesive sheet for circuit boards. Examples of the circuit board include a flexible printed wiring board and the like.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

[Compounds used in Examples or Comparative Examples]
-Polyphenylene ether resin (A1): Vinyl benzyl-modified polyphenylene ether [manufactured by Mitsubishi Gas Chemical Company, trade name: OPE-2St 1200, number average molecular weight: 1200]
-Polyphenylene ether resin (A2): Vinyl benzyl-modified polyphenylene ether [manufactured by Mitsubishi Gas Chemical Company, trade name: OPE-2St 2200, number average molecular weight: 2200]
-Polyfunctional compound (B1): Dialyl compound having an isocyanurate skeleton (manufactured by Shikoku Chemicals Corporation, trade name: L-DAIC)
-Cyclic ether group-containing compound (BX1): Hydrogenated bisphenol A type epoxy resin [manufactured by Mitsubishi Chemical Co., Ltd., trade name: YX8000, epoxy equivalent: 205 g / eq, liquid at 25 ° C]
Binder resin (C1): Acid-modified α-olefin polymer [manufactured by Mitsui Chemicals, trade name: Unistor H-200, number average molecular weight: 47,000]
-Cationic polymerization initiator (D1): Sulfonium salt-based thermal cationic polymerization initiator [manufactured by Sanshin Chemical Co., Ltd., trade name: Sun Aid SI-B3]
-Silane coupling agent (E1): 8-glycidoxyoctyltrimethoxysilane [manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBM4803]

[Example 1]
50 parts by mass of polyphenylene ether resin (A1), 10 parts by mass of polyfunctional compound (B1), 100 parts by mass of binder resin (C1), 0.5 parts by mass of cationic polymerization initiator (D1), silane coupling agent (E1) 0.2 parts by mass was dissolved in toluene to prepare an adhesive composition.
This adhesive composition is applied onto the peeling surface of the release film (first release film, manufactured by Lintec Corporation, trade name: SP-PET752150), and the obtained coating film is dried at 100 ° C. for 2 minutes to make it thicker. An adhesive layer having a size of 15 μm was formed. A release-treated surface of another release film (second release film, manufactured by Lintec Corporation, trade name: SP-PET381130) is bonded onto this adhesive layer to form a curable adhesive sheet (thermosetting adhesive sheet). Obtained.

[Examples 2 to 6, Comparative Examples 1 to 4]
An adhesive composition and a thermosetting adhesive sheet were obtained in the same manner as in Example 1 except that the types and amounts of the components constituting the adhesive composition were changed to those shown in Table 1.

The following tests were performed on the thermosetting adhesive sheets obtained in Examples 2 to 6 and Comparative Examples 1 to 4. The results are shown in Table 1.

[Relative permittivity, dielectric loss tangent]
A structure of a release film / an adhesive layer / a release film having a thickness of about 1 mm by laminating a plurality of adhesive layers of the thermosetting adhesive sheets obtained in Examples or Comparative Examples so as to have a thickness of about 1 mm. Was obtained. This laminate was heated at 160 ° C. for 1 hour to cure an adhesive layer having a thickness of about 1 mm, and then the release films on both sides were peeled off to obtain a sample for measurement.
The obtained measurement sample was measured for relative permittivity and dielectric loss tangent at 23 ° C. and 1 GHz using an RF impedance material analyzer (manufactured by Keysight Co., Ltd., E4991A). In the examples or comparative examples, 1 GHz was adopted as an example of the high frequency region.

The following can be seen from Table 1.
The cured product of the adhesive layer of the curable adhesive sheet obtained in Examples 1 to 6 has a low dielectric property in a high frequency region.
On the other hand, since the adhesive layer of the curable adhesive sheet obtained in Comparative Examples 1 to 4 contains a compound having a cyclic ether group instead of the component (B) of the present invention, a cured product of these adhesive layers. Is inferior in low dielectric properties in the high frequency region.

Claims (9)

A curable adhesive sheet for a device having an adhesive layer containing the following components (A) and (B).
Component (A): Polyphenylene ether resin having a vinyl group (B) Component: Compound represented by the following formula

(In the formula, R represents a saturated hydrocarbon group having 5 to 15 carbon atoms.) The curable adhesive sheet for a device according to claim 1 , wherein the molecular weight of the component (B) is 1,000 or less. The curable adhesive sheet for a device according to claim 1 or 2 , wherein the adhesive layer contains an olefin resin as a binder resin. The curable adhesive sheet for a device according to any one of claims 1 to 3 , wherein the adhesive layer contains a resin having a reactive functional group as a binder resin. The curable adhesive sheet for a device according to any one of claims 1 to 4 , wherein the adhesive layer further contains the following component (D).
Component (D): Cationic polymerization initiator The adhesive layer is a layer containing a compound having a cyclic ether group or a layer not containing a compound having a cyclic ether group, and the content of the compound having a cyclic ether group is 5% by mass in the adhesive layer. The curable adhesive sheet for a device according to any one of claims 1 to 5 , which is less than. Any of claims 1 to 6 , wherein the adhesive layer is a layer containing a liquid compound at 25 ° C., and the content of the liquid compound at 25 ° C. is 5% by mass or more in the adhesive layer. Curable adhesive sheet for devices as described in. The curable adhesive sheet for a device according to claim 7 , wherein at least one of the compounds liquid at 25 ° C. is a compound having two or more hydrocarbon groups having a double bond at the end. The eighth aspect of the present invention, which has two or more hydrocarbon groups having a double bond at the terminal, and the content of the liquid compound at 25 ° C. is 90% by mass or more based on the total amount of the liquid compound at 25 ° C. Curable adhesive sheet for devices.