WO2023054677A1

WO2023054677A1 - Curable adhesive sheet, and method for producing cured product

Info

Publication number: WO2023054677A1
Application number: PCT/JP2022/036717
Authority: WO
Inventors: 健太西嶋; 幹広樫尾; 直史泉
Original assignee: リンテック株式会社
Priority date: 2021-09-30
Filing date: 2022-09-30
Publication date: 2023-04-06
Also published as: TW202332750A; JPWO2023054677A1; CN118019819A; KR20240070534A

Abstract

Provided is a curable adhesive sheet having a curable adhesive layer capable of forming a cured product having a loss tangent of 0.01 or less at 23°C and 1 GHz, and a first release film and a second release film enclosing the two surfaces of the curable adhesive layer, wherein the first release film has a colored resin film (i) and a release agent layer that is laminated on one surface of the colored resin film (i) and is in contact with the surface of the curable adhesive layer, the second release film has a resin film (ii) that is visually distinguishable from the colored resin film (i) and a release agent layer that is laminated on one surface of the resin film (ii) and is in contact with the surface of the curable adhesive layer, and the curable adhesive sheet satisfies requirement (Ia). Requirement (Ia): the thickness ratio [(T2)/(T1)] of the thickness (T2) of the second release film and the thickness (T1) of the first release film is 1.05 or greater.

Description

Curable adhesive sheet and method for producing cured product

The present invention relates to a curable adhesive sheet and a method for producing a cured product using the curable adhesive sheet.

In recent years, flexible printed wiring boards (FPC) have been used as wiring members as electronic devices have become smaller and lighter. An FPC can be manufactured by, for example, etching the copper foil of a copper-clad laminate in which a copper foil is bonded to an insulating resin film such as polyimide to form an electric circuit.
Moreover, for such FPCs, a coverlay sheet 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. ing.

As an example of such a coverlay sheet, Patent Document 1 discloses an adhesive composition containing predetermined amounts of a styrene-based elastomer, a modified polyphenylene ether resin having a polymerizable group at the end, an epoxy resin, and an epoxy resin curing agent. An invention relating to a thermosetting adhesive sheet having a thermosetting adhesive layer formed on a substrate is disclosed.

JP 2019-135280 A

By the way, the surface of the thermosetting adhesive layer of the thermosetting adhesive sheet as described in Patent Document 1 is provided with a release sheet subjected to release treatment for the purpose of protecting the surface.
As a release sheet, a release sheet having a release layer on a paper substrate is widely used. In some cases, this foreign matter may be mixed between the adherend and the thermosetting adhesive layer. In particular, in FPCs, contamination by foreign matter can cause malfunction of electronic equipment.
In addition, when a release sheet that is not a paper substrate is used, there is also the problem of ease of handling in that the release sheet is difficult to separate from the thermosetting adhesive layer.
Therefore, there is a demand for a curable adhesive sheet that suppresses the contamination of foreign matter when applied to an adherend and that is easy to handle.

The present invention provides a curable adhesive layer capable of forming a cured product having a dielectric loss tangent of a predetermined value or less, and a curable adhesive having a first release film and a second release film sandwiching both sides of the curable adhesive layer. A sheet, wherein the first release film has a colored resin film, the second release film has a resin film visually distinguishable from the colored resin film, the thickness of the second release film and the first release film To provide a curable adhesive sheet in which the ratio of the thickness to the thickness is set to a predetermined value or more.

Specifically, one aspect provided by the present invention is as follows.
[1] A curable adhesive layer capable of forming a cured product having a dielectric loss tangent of 0.01 or less at 23° C. and 1 GHz, and a first release film and a second release film sandwiching both sides of the curable adhesive layer A curable adhesive sheet having
The first release film has a colored resin film (i) and a release agent layer laminated on one surface of the colored resin film (i) and in contact with the surface of the curable adhesive layer,
A second release film is laminated on one surface of the resin film (ii) visually distinguishable from the colored resin film (i) and on one surface of the resin film (ii), and is in contact with the surface of the curable adhesive layer. and a release agent layer,
A curable adhesive sheet that satisfies the following requirement (Ia).
Requirement (Ia): The thickness ratio [(T2)/(T1)] between the thickness (T2) of the second release film and the thickness (T1) of the first release film is 1.05 or more.
[2] The curable adhesive sheet according to [1] above, which further satisfies the following requirement (Ib).
Requirement (Ib): The thickness ratio [(T2)/(T1)] of the thickness (T2) of the second release film and the thickness (T1) of the first release film is 10.0 or less.
[3] The curable adhesive sheet according to [1] or [2] above, which further satisfies the following requirement (IIa).
Requirement (IIa): The thickness difference [(T2) - (T1)] between the thickness (T2) of the second release film and the thickness (T1) of the first release film is 5.0 µm or more.
[4] The curable adhesive sheet according to any one of [1] to [3] above, which further satisfies the following requirement (IIb).
Requirement (IIb): The thickness difference [(T2) - (T1)] between the thickness (T2) of the second release film and the thickness (T1) of the first release film is 165.0 µm or less.
[5] The curable adhesive sheet according to any one of [1] to [4] above, which further satisfies the following requirement (III).
Requirement (III): The peel force (R1) when peeling the first release film from the curable adhesive layer at a peel angle of 180 ° and a peel speed of 300 mm / min, and the second release film at a peel angle of 180 °, The ratio [(R1)/(R2)] to the peel force (R2) when peeled from the curable adhesive layer at a peel speed of 300 mm/min is 0.97 or less.
[6] The curable adhesive sheet according to any one of [1] to [5] above, which further satisfies the following requirement (IV).
Requirement (IV): The peel force (R2) when peeling the second release film from the curable adhesive layer at a peel angle of 180 ° and a peel speed of 300 mm / min is It is greater than the peel force (R1) when peeling from the curable adhesive layer at a peel speed of 300 mm/min, and is 600 mN/50 mm or less.
[7] The curable adhesive sheet according to any one of [1] to [6] above, wherein the resin film (ii) is a transparent resin film.
[8] The curable adhesive sheet according to any one of [1] to [7] above, wherein the curable adhesive layer is a layer formed from a curable adhesive composition containing a polyphenylene ether resin. .
[9] When the curable adhesive layer exposed by peeling the first release film is attached to the adherend, the curable adhesive layer and the The curable adhesive sheet according to any one of [1] to [8] above, wherein the presence or absence of foreign matter at the interface with the adherend can be confirmed.
[10] A method for producing a cured product using the curable adhesive sheet according to any one of [1] to [9] above, comprising the following steps (1) to (3): Production method.
Step (1): A step of peeling off the first release film and attaching the exposed curable adhesive layer to an adherend.
Step (2): A step of confirming that no foreign matter exists at the interface between the curable adhesive layer and the adherend by optical inspection means from the second release film side.
Step (3): After step (2), the step of curing the curable adhesive layer to obtain a cured product.

The curable adhesive sheet of one preferred embodiment of the present invention can suppress the contamination of foreign matter when attached to an adherend, and is easy to remove the release film and has excellent handleability.

1 is a schematic cross-sectional view in the thickness direction of the adhesive sheet, showing an example of the configuration of the curable adhesive sheet of the present invention; FIG.

The upper and lower limits of the numerical ranges described herein can be arbitrarily combined. For example, when the numerical range is described as "preferably 20 to 120, more preferably 40 to 90", the range of "20 to 90" and the range of "40 to 120" are also described in this specification. included in the specified numerical range. Further, for example, when the numerical range is described as "preferably 20 or more, more preferably 40 or more, and preferably 120 or less, more preferably 90 or less", "20 to 90" Ranges and ranges from "40 to 120" are also included in the numerical ranges described herein.
In addition, as a numerical range described in this specification, for example, "60 to 100" means a range of "60 or more and 100 or less".
Furthermore, in the definition of the upper limit value and the lower limit value described in this specification, it is possible to define the numerical range from the lower limit value to the upper limit value by appropriately selecting from each option and combining them arbitrarily.
In addition, various requirements described as preferred embodiments described herein can be combined.

In this specification, for example, "(meth)acrylate" is used as a term indicating both "acrylate" and "methacrylate", and the same applies to other similar terms.
As used herein, the term "active ingredient" of the curable adhesive composition means a component excluding water and a diluent such as an organic solvent among the components contained in the curable adhesive composition.

As used herein, the number average molecular weight (Mn) is a value converted to standard polystyrene measured by a gel permeation chromatography (GPC) method, specifically a value measured based on the method described in Examples. is.

In this specification, the thickness of each layer constituting the curable adhesive sheet is a value measured in accordance with JIS K7130 (1999). name "PG-02J").

[Structure of Curable Adhesive Sheet]
FIG. 1 is a schematic cross-sectional view in the thickness direction of the adhesive sheet, showing an example of the configuration of the curable adhesive sheet of the present invention.
As shown in FIG. 1, the curable adhesive sheet 1 of the present invention comprises a curable adhesive layer 10, and a first release film 21 and a second release film 22 sandwiching both sides of the curable adhesive layer 10. have.
The curable adhesive layer 10 can be cured to form a cured product having a dielectric loss tangent of 0.01 or less at 23° C. and 1 GHz.

The first release film 21 comprises a colored resin film (i) 212 and a release layer 211 laminated on one surface of the colored resin film (i) 212 and in contact with the surface 10a of the curable adhesive layer 10. have. Note that the colored resin film includes a white resin film.
The second release film 22 includes a resin film (ii) 222 and a release layer 221 laminated on one surface of the resin film (ii) 222 and in contact with the surface 10b of the curable adhesive layer 10. have.
In the curable adhesive sheet of one aspect of the present invention, the resin film (ii) of the second release film is visually distinguishable from the colored resin film (i) of the first release film.

In the curable adhesive sheet of one aspect of the present invention, when used, the first release film 21 is peeled off, and after the exposed surface 10a of the curable adhesive layer 10 is attached to an adherend, the second release film 22 is applied. It is assumed to be used for peeling off.
As described above, the first release film has a colored resin film (i), and the second release film has a resin film (ii) that is visually distinguishable from the colored resin film (i). The distinction between the film and the second release film becomes clear. Therefore, in the curable adhesive sheet of one aspect of the present invention, it is easy to identify the first release film to be peeled first when used, and it is possible to prevent misidentification such as erroneously peeling off the second release film. Further, as described later, when the second release film is a colorless transparent resin film, the entire curable adhesive sheet becomes nearly colorless and transparent by first peeling off the colored resin film (i) that is the first release film. Since it looks good, there is also an advantage that it is easy to visually recognize that the colored resin film (i) has been peeled off.

In addition, since both the first release film and the second release film use a resin film as a base material, dust and foreign substances caused by the release film are less likely to occur. Therefore, when the curable adhesive sheet of one embodiment of the present invention is attached to an adherend, contamination by foreign matter can be effectively suppressed. It is possible to suppress the occurrence of malfunction of the electronic device.

In addition, in the curable adhesive sheet of one embodiment of the present invention, when the curable adhesive layer exposed by peeling the first release film is attached to an adherend, optical It is preferable that the presence or absence of foreign matter at the interface between the curable adhesive layer and the adherend can be confirmed by inspection means.
With such a configuration, when the curable adhesive layer is attached to the adherend, foreign matter is not mixed between the adherend and the curable adhesive layer from the second release film side. It is possible to confirm whether or not Therefore, the curable adhesive sheet can be reapplied, and the yield of the product can be improved.
In addition, if the resin film which the 2nd peeling film has is a transparent resin film, for example, it can be set as the said structure.

By the way, in an adhesive sheet having a configuration in which an adhesive layer is sandwiched between two release films, when a release film using a resin film is used as a substrate, compared to a release film using a general paper substrate, A handling problem is likely to arise in that one release film is difficult to separate from the adhesive layer.
In particular, a curable adhesive layer having a low dielectric loss tangent, such as the curable adhesive sheet of the present invention, is often composed of a component having no polar group or a component having a low polarity. Low polarity on the surface of the layer. Therefore, when a curable adhesive layer with a low surface polarity is sandwiched between release films having two resin films, one release film is removed from the surface with a low polarity of the curable adhesive layer during use. It becomes more and more difficult to peel off, resulting in handling problems.

In order to deal with the handling problem that it is difficult to peel off the release film from the low polarity surface of the curable adhesive layer, the curable adhesive sheet of the present invention is adjusted so as to satisfy the following requirement (Ia). .
Requirement (Ia): The thickness ratio [(T2)/(T1)] between the thickness (T2) of the second release film and the thickness (T1) of the first release film is 1.05 or more.
By adjusting the thickness ratio of the first release film and the second release film so as to satisfy the above requirement (I), the curable adhesive layer is sandwiched between the first release film and the second release film. From this state, the first release film can be easily peeled off, and a curable adhesive sheet with excellent handleability can be obtained. Such an effect is thought to be due to the fact that the second release film serves as a support and fixes the shape of the curable adhesive layer, making it easier to separate the first release film from the curable adhesive layer.

In the curable adhesive sheet of one aspect of the present invention, the first release film is easily peeled off from the curable adhesive layer in a state in which the curable adhesive layer is sandwiched between the first release film and the second release film. From the viewpoint, the thickness ratio [(T2)/(T1)] defined in the above requirement (I) is 1.05 or more, preferably 1.25 or more, more preferably 1.50 or more, and still more preferably is greater than or equal to 1.70.

In the curable adhesive sheet of one aspect of the present invention, the configuration in which the curable adhesive layer is sandwiched between the first release film and the second release film makes it easier to separate the first release film from the curable adhesive layer. Furthermore, from the viewpoint of facilitating the winding of a long curable adhesive sheet even with a winding core having a small diameter, it is preferable to satisfy the following requirement (Ib).
Requirement (Ib): The thickness ratio [(T2)/(T1)] of the thickness (T2) of the second release film and the thickness (T1) of the first release film is 10.0 or less.
From the above viewpoint, the thickness ratio [(T2)/(T1)] defined by the requirement (Ib) is 10.0 or less, preferably 7.0 or less, more preferably 4.0 or less, and further Preferably it is 3.0 or less.

In the curable adhesive sheet of one aspect of the present invention, the configuration in which the curable adhesive layer is sandwiched between the first release film and the second release film makes it easier to separate the first release film from the curable adhesive layer. Therefore, it is preferable to further satisfy the following requirement (IIa).
Requirement (IIa): The thickness difference [(T2) - (T1)] between the thickness (T2) of the second release film and the thickness (T1) of the first release film is 5.0 µm or more.
From the above viewpoint, the thickness difference [(T2) - (T1)] defined by the requirement (IIa) is 5.0 μm or more, preferably 10.0 μm or more, more preferably 20.0 μm or more, and still more preferably is 30.0 μm or more.

In the curable adhesive sheet of one aspect of the present invention, the configuration in which the curable adhesive layer is sandwiched between the first release film and the second release film makes it easier to separate the first release film from the curable adhesive layer. Therefore, it is preferable to further satisfy the following requirement (IIb).
Requirement (IIb): The thickness difference [(T2) - (T1)] between the thickness (T2) of the second release film and the thickness (T1) of the first release film is 165.0 µm or less.
From the above viewpoint, the thickness difference [(T2) - (T1)] defined by the above requirement (IIb) is 165.0 µm or less, preferably 100.0 µm or less, more preferably 70.0 µm or less, and even more preferably is 50.0 μm or less.

In the curable adhesive sheet of one aspect of the present invention, the configuration in which the curable adhesive layer is sandwiched between the first release film and the second release film makes it easier to separate the first release film from the curable adhesive layer. Therefore, it is preferable to further satisfy the following requirement (III).
Requirement (III): The peel force (R1) when peeling the first release film from the curable adhesive layer at a peel angle of 180 ° and a peel speed of 300 mm / min, and the second release film at a peel angle of 180 °, The ratio [(R1)/(R2)] to the peel force (R2) when peeled from the curable adhesive layer at a peel speed of 300 mm/min is 0.97 or less.
From the above viewpoint, the ratio [(R1) / (R2)] defined by the above requirement (III) is 0.97 or less, preferably 0.95 or less, more preferably 0.88 or less, and still more preferably 0.80 or less. The ratio [(R1)/(R2)] between the peel strength (R1) and the peel strength (R2) defined in the above requirement (IIa) has no particular lower limit, but is preferably 0.2 or more, more preferably is greater than or equal to 0.35.

In the curable adhesive sheet of one aspect of the present invention, the configuration in which the curable adhesive layer is sandwiched between the first release film and the second release film makes it easier to separate the first release film from the curable adhesive layer. Therefore, it is preferable to further satisfy the following requirement (IV).
Requirement (IV): The peel force (R2) when peeling the second release film from the curable adhesive layer at a peel angle of 180 ° and a peel speed of 300 mm / min is It is greater than the peel force (R1) when peeling from the curable adhesive layer at a peel speed of 300 mm/min, and is 600 mN/50 mm or less.
From the above viewpoint, the peel force (R2) is 600 mN/50 mm or less, preferably 450 mN/50 mm or less, more preferably 250 mN/50 mm or less, and even more preferably 150 mN/50 mm or less.

In the curable adhesive sheet of one aspect of the present invention, the configuration in which the curable adhesive layer is sandwiched between the first release film and the second release film makes it easier to separate the first release film from the curable adhesive layer. Therefore, the peel force (R1) is preferably smaller than the peel force (R2) and is 5 mN/50 mm or more.
The peel strength (R2) is more preferably 10 mN/50 mm or more, still more preferably 20 mN/50 mm or more.

As described above, in the curable adhesive sheet of one embodiment of the present invention, the curable adhesive layer is sandwiched between the first release film and the second release film. From the viewpoint of facilitating the process, it is preferable to satisfy the following requirement (Va), and it is more preferable to satisfy the following requirement (Vb).
・ Requirement (Va): 5 mN / 50 mm ≤ peel force (R1) < peel force (R2) ≤ 600 mN / 50 mm
・ Requirement (Vb) 5 mN / 50 mm ≤ peel strength (R1) < peel strength (R2) ≤ 250 mN / 50 mm

The release force (R1) and the release force (R2) are determined by the type of release agent that forms the resin film and the release agent layer that constitute the first release film and the second release film, and the type of release agent that forms the curable adhesive layer. It can be adjusted by appropriately setting the type and content of each component contained in the curable adhesive composition. A specific adjustment method will be described in detail in the description of each configuration.
Moreover, in the present specification, the peel strengths (R1) and (R2) mean values measured based on the method described in Examples below.

Each layer constituting the curable adhesive sheet of one embodiment of the present invention and the material forming the layer will be described below.

[First release film, second release film]
The first release film used in one aspect of the present invention may have a structure including a colored resin film (i) and a release layer formed from a release agent.
Examples of resin components contained in the colored resin film (i) include polyester resins such as polyethylene terephthalate resin, polybutylene terephthalate resin and polyethylene naphthalate resin; polyolefin resins such as polypropylene resin and polyethylene resin; and mixed resins in which two or more of the above are used in combination.
In addition to the resin component, the colored resin film (i) contains additives such as ultraviolet absorbers, antistatic agents, light stabilizers, antioxidants, resin stabilizers, fillers, colorants (pigments, dyes, etc.). may contain.
The colored resin film (i) may be a colored resin film colored by containing a coloring agent such as a pigment or a dye together with the resin component. It may be a treated foamed resin film. The foamed resin film is usually a white opaque colored resin film. Moreover, a resin film formed from a resin composition containing a filler together with a resin component also becomes a colored resin film due to a decrease in transparency due to light scattering. A coloring agent may be further added to the foamed resin film or the colored resin film containing the filler.
In addition, it may be a colored resin film obtained by providing a printed layer on the surface of a colorless resin film by means of printing or the like.
The front and back surfaces of the colored resin film (i) used in one aspect of the present invention may have different colors.

The second release film used in one aspect of the present invention may have a structure having a resin film (ii) visually distinguishable from the colored resin film (i), and a release agent layer.
Examples of embodiments of the resin film (ii) visually distinguishable from the colored resin film (i) include the following embodiments (a) to (h).
(a) In the case where the colored resin film (i) is opaque, it is used as a colorless and transparent resin film.
(b) When the colored resin film (i) is opaque, a colored resin film having a color different from that of the colored resin film (i) is used as a transparent resin film.
(c) When the colored resin film (i) is transparent, an opaque colored resin film having a color different from that of the colored resin film (i).
(d) A mode in which a visible mark is attached to the surface of the resin film (ii).
(e) When the colored resin film (i) is opaque, the resin film (ii) is a colored resin film of the same color as the colored resin film (i) and is a transparent resin film.
(f) When the colored resin film (i) is transparent, the resin film (ii) is an opaque colored resin film having the same color as the colored resin film (i).
(g) When the colored resin film (i) is transparent, the resin film (ii) is a colored resin film having a color different from that of the colored resin film (i) and is a transparent resin film.
(h) A mode in which the resin film (ii) is a colorless transparent resin film when the colored resin film (i) is transparent.
Among these embodiments, the resin film (ii) preferably has any one of the above-described embodiments (a) to (d) from the viewpoint of being more visually distinguishable from the colored resin film (i).

The resin film (ii) is preferably a transparent resin film that can be visually distinguished from the colored resin film (i), and more preferably a colorless transparent resin film.
A curable adhesive sheet using a second release film having a transparent resin film peels off the first release film, attaches the curable adhesive layer to the adherend, and then attaches the transparent resin film side of the second release film. Therefore, it is possible to check the state of the interface between the adherend and the curable adhesive layer, such as whether or not foreign matter is mixed between the adherend and the curable adhesive layer. If, for example, the inclusion of foreign matter is confirmed, the yield of the product can be improved by reattaching the curable adhesive sheet.
When the resin film (ii) is a transparent resin film, the colored resin film (i) is opaque so that the resin film (ii) can be visually distinguished from the colored resin film (i). is preferred.

The haze of the transparent resin film (i) used in one aspect of the present invention is determined by checking foreign matter that may be mixed between the adherend and the curable adhesive layer after the curable adhesive layer is attached to the adherend. It may be as transparent as possible, preferably 10.0% or less, more preferably 3.0% or less, even more preferably 1.0% or less, and even more preferably 0.6% or less.
When the colored resin film (i) is opaque and the resin film (ii) is transparent, the haze of the colored resin film (i) is preferably It is 30.0% or more, more preferably 45.0% or more, still more preferably 60.0% or more, and even more preferably 80% or more.
The haze of the resin film can be measured using a commercially available haze meter.

The resin component contained in the resin film (ii) includes the same resins as those exemplified as the resin component contained in the colored resin film (i).
In addition, the additives other than the resin component contained in the resin film (ii) are the same as the additives contained in the above-mentioned colored resin film (i).

Also, the release layers of the first release film and the second release film can be formed from various release agents.
Such release agents may be, for example, silicone release agents, rubber elastomer release agents such as olefin release agents, isoprene release agents, butadiene release agents, long-chain alkyl release agents, Non-silicone release agents such as alkyd release agents and fluorine release agents may also be used.
Among these, the release agent, which is the material for forming the release layer, is a non-silicone release agent from the viewpoint of suppressing the occurrence of malfunction of electronic devices due to silicon contamination due to the migration of the silicon component to the adherend. is preferred.
In addition, from the viewpoint of adjusting the release forces (R1) and (R2), it is preferable that at least one of the release layer of the first release film and the second release film is a layer formed from an alkyd-based release agent. More preferably, both the release layers of the first release film and the second release film are layers formed from an alkyd release agent.

The thickness (T1) of the first release film of the curable adhesive sheet of one embodiment of the present invention is preferably 10 μm or more, more preferably 20 μm or more, and still more preferably 30 μm, from the viewpoint of adjusting the peel strength (R1). The thickness is preferably 200 μm or less, more preferably 100 μm or less, even more preferably 70 μm or less, and even more preferably 45 μm or less.

The thickness (T2) of the second release film included in the curable adhesive sheet of one embodiment of the present invention is preferably 33 μm or more, more preferably 47 μm or more, and even more preferably 55 μm, from the viewpoint of adjusting the peel force (R2). More preferably, it is 65 µm or more, and preferably 270 µm or less, more preferably 210 µm or less, and still more preferably 140 µm or less.

[Curable adhesive layer]
The curable adhesive layer of the curable adhesive sheet of one embodiment of the present invention can form a cured product having a dielectric loss tangent of 0.01 or less at 23° C. and 1 GHz.
The dielectric loss tangent at 23 ° C. and 1 GHz of the cured product that can be formed is 0.01 or less,
It is preferably 0.005 or less, more preferably 0.002 or less.
The dielectric loss tangent of the cured product at 23° C. and 1 GHz is not particularly limited to a lower limit, but is preferably 0.00005 or more, more preferably 0.0001 or more.
In this specification, the dielectric loss tangent of the cured product means a value measured based on the method described in Examples below.

The method for curing the curable adhesive layer may be a thermosetting method or a photo-curing method, and can be appropriately selected according to the application. For example, when the curable adhesive sheet of one embodiment of the present invention is used as a coverlay sheet to form a cured product for protecting a circuit board, a thermosetting method is preferable.

In the curable adhesive sheet of one aspect of the present invention, the thickness of the curable adhesive layer is preferably 3.0 μm or more, more It is preferably 5.0 μm or more, more preferably 10 μm or more, still more preferably 15 μm or more, and preferably 60 μm or less, more preferably 45 μm or less.

The curable adhesive layer of the curable adhesive sheet of one aspect of the present invention can be formed from a curable adhesive composition containing a binder resin (A) (hereinafter also referred to as "component (A)"). .
The curable adhesive composition used in one aspect of the present invention is a composition capable of forming a cured product with improved adhesive strength and low dielectric properties, as well as from the viewpoint of adjusting the peel strength (R1) or (R2). From the viewpoint of, it is preferable to further contain a polyphenylene ether resin (B) (hereinafter also referred to as "component (B)"). It is more preferable to further contain a polyfunctional compound (C) having two or more hydrocarbon groups (hereinafter also referred to as "component (C)").
In addition, the curable adhesive composition used in one aspect of the present invention includes a cationic polymerization initiator (D) (hereinafter also referred to as "component (D)"), which reacts with the reactive functional group of component (A). It further contains one or more selected from the obtained cross-linking agent (E) (hereinafter also referred to as "component (E)") and the silane coupling agent (F) (hereinafter also referred to as "component (F)") is preferred.
In addition, the curable adhesive composition used in one aspect of the present invention may contain additives other than these components (A) to (F) within a range that does not impair the effects of the present invention.

In the curable adhesive composition used in one aspect of the present invention, the viewpoint of adjusting the peel strength (R1) or (R2), and the curable adhesive layer or cured product thereof with improved adhesive strength and low dielectric properties From the viewpoint of a composition capable of forming % by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, still more preferably 75% by mass or more, and usually 100% by mass or less, preferably 99.90% by mass or less, more preferably is 99.00% by mass or less, more preferably 95.00% by mass or less.

From the above viewpoint, in the curable adhesive composition used in one aspect of the present invention, the total content of component (A), component (B), component (C), and component (D) is It is preferably 60% by mass or more, more preferably 75% by mass or more, still more preferably 90% by mass or more, and usually 100% by mass or less, relative to the total amount (100% by mass) of the active ingredients of the composition. , 99.70% by mass or less, or 90% by mass or less.

From the above viewpoint, in the curable adhesive composition used in one aspect of the present invention, component (A), component (B), component (C), component (D), component (E), and component (F) The total content is preferably 60% by mass or more, more preferably 75% by mass or more, and still more preferably 90% by mass or more with respect to the total amount (100% by mass) of the active ingredients of the curable adhesive composition. Also, it is usually 100% by mass or less, and may be 99.70% by mass or less, or 90% by mass or less.
Details of each component contained in the curable adhesive composition used in one embodiment of the present invention are described below.

<Component (A): Binder resin>
The curable adhesive composition used in one aspect of the present invention preferably contains a binder resin (A). By containing the binder resin (A), it becomes a composition capable of forming a curable adhesive layer having excellent adhesive strength when cured and good shape stability.
The binder resin (A) may be used alone or in combination of two or more.

In the curable adhesive composition used in one aspect of the present invention, the content of component (A) is preferably 35% by mass with respect to the total amount (100% by mass) of the active ingredients in the curable adhesive composition. Above, more preferably 45% by mass or more, still more preferably 55% by mass or more, and preferably 90% by mass or less, more preferably 80% by mass or less, still more preferably 75% by mass or less.

The number average molecular weight (Mn) of the binder resin (A) used in one embodiment of the present invention is from the viewpoint of improving film-forming properties and forming a curable adhesive layer with good shape stability. , preferably 10,000 or more, more preferably 25,000 or more, and still more preferably 35,000 or more, and when the composition is in the form of a solution, the solubility of the component (A) with a dilution solvent is preferably 150,000 or less, more preferably 100,000 or less, and still more preferably 70,000 or less, from the viewpoint of making the composition excellent in coating properties.

Examples of the binder resin (A) include polyolefin-based resins, phenoxy-based resins, polyimide-based resins, polyamide-imide-based resins, polyvinyl butyral-based resins, polycarbonate-based resins, and styrene-based resins.
Among these, the binder resin (A) used in one embodiment of the present invention contains a polyolefin resin from the viewpoint of being a composition capable of forming a cured product having excellent dielectric properties in a high frequency region (e.g., 1 GHz or higher). is preferred.

The polyolefin-based resin may be a polymer having structural units derived from an olefin-based monomer, and may be a polymer consisting only of structural units derived from an olefin-based monomer. It may be a copolymer having a structural unit derived from and a structural unit derived from a monomer copolymerizable with an olefinic monomer.

The olefinic monomers constituting the polyolefinic resin include α-olefins having 2 or more carbon atoms, preferably α-olefins having 2 to 8 carbon atoms, ethylene, propylene, 1-butene, isobutylene, and 1- At least one selected from hexene is more preferred, and at least one selected from ethylene and propylene is even more preferred.
These olefinic monomers may be used alone or in combination of two or more.

Examples of monomers copolymerizable with olefinic monomers that constitute the polyolefinic resin include vinyl acetate, (meth)acrylic acid esters, and styrene. These monomers may be used alone or in combination of two or more.
Specifically, the polyolefin-based resin used in one aspect of the present invention includes very low density polyethylene (VLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), linear low Density polyethylene, polypropylene (PP), ethylene-propylene copolymer, olefinic elastomer (TPO), ethylene-vinyl acetate copolymer (EVA), ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic Examples include acid ester copolymers.

The binder resin (A) used in one aspect of the present invention is a composition capable of improving film-forming properties and forming a curable adhesive layer with good shape stability, and further improving low dielectric properties. A binder resin having a reactive functional group from the viewpoint of making a composition capable of forming a cured product and reducing the peeling force when peeling the first release film or the second release film from the curable adhesive layer. It preferably contains a polyolefin resin having a reactive functional group, and more preferably one or more selected from styrene resins having a reactive functional group, and a polyolefin resin having a reactive functional group ( More preferably, it contains at least A1).

In the curable adhesive composition used in one aspect of the present invention, the content of the polyolefin-based resin (A1) is, from the viewpoint of making the composition capable of forming a cured product having excellent low dielectric properties, the curable adhesive composition It is preferably 50 to 100% by mass, more preferably 70 to 100% by mass, still more preferably 85 to 100% by mass, based on the total amount (100% by mass) of component (A) contained in the product.

The reactive functional groups of the binder resin (A) include, for example, a carboxy group, a group having a carboxylic anhydride structure, a group having a carboxylic acid ester structure, a hydroxyl group, an epoxy group, an amide group, an ammonium group, a nitrile group, Amino group, imide group, isocyanate group, acetyl group, thiol group, sulfone group, phosphon group, nitro group, halogen atom, alkoxysilyl group and the like.
The reactive functional groups possessed by the binder resin (A) may be composed of one type alone, or may be composed of a combination of two or more types.
Among these, the reactive functional groups possessed by the binder resin (A) include a carboxy group, a group having a carboxylic anhydride structure, an epoxy group, an amide group, an ammonium group, a nitrile group, an amino group, an imide group, an isocyanate group, A composition that is preferably a group selected from an acetyl group, a thiol group, an ether group, a thioether group, a sulfone group, a phosphonic group, a nitro group, a urethane group, a halogen atom, and an alkoxysilyl group, and which can form a cured product with excellent adhesive strength. From the viewpoint of reducing the peel force when peeling the first peeling film or the second peeling film from the curable adhesive layer, the group selected from a group having a carboxyl group and a carboxylic anhydride structure is more A group having a carboxylic acid anhydride structure is more preferable, from the viewpoint of obtaining a composition capable of forming a cured product having excellent adhesive strength and low dielectric properties.

The binder resin (A) used in one aspect of the present invention may be a modified resin obtained by modifying a main chain resin using a modifying agent to introduce the reactive functional groups described above.
Specific modified resins include, for example, acid-modified resins into which acid groups have been introduced and resins into which hydroxyl groups have been introduced. Alternatively, from the viewpoint of reducing the peeling force when peeling the second release film from the curable adhesive layer, an acid-modified resin in which an acid group is introduced is preferable, and a cured product that is more excellent in adhesive strength and low dielectric properties. Acid anhydride-modified resin into which an acid anhydride structure is introduced is more preferable from the viewpoint of making a composition capable of forming

Acid-modified resins or acid anhydride-modified resins (hereinafter also referred to as “unsaturated carboxylic acids, etc.”) are produced, for example, by reacting a main chain resin with an unsaturated carboxylic acid or the like to form a carboxy group or a carboxylic acid anhydride. It is obtained by introducing a structure and graft-denaturing it.
The method of introducing the unsaturated carboxylic acid or the like into the resin is not particularly limited. Examples include a method of heating and melting the reaction as described above, or a method of dissolving the resin and the unsaturated carboxylic acid in an organic solvent, followed by heating and stirring in the presence of a radical generator.

Examples of unsaturated carboxylic acids include maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, tetrahydrophthalic acid, and aconitic acid.
Examples of unsaturated carboxylic anhydrides include maleic anhydride, itaconic anhydride, glutaconic anhydride, citraconic anhydride, aconitic anhydride, norbornene dicarboxylic anhydride, and tetrahydrophthalic anhydride.
These may be used alone or in combination of two or more.
Among these, maleic anhydride is preferable from the viewpoint of forming a composition capable of forming a cured product having excellent adhesive strength and low dielectric properties.

The amount of unsaturated carboxylic acid or the like to be reacted with the resin is preferably 0.1 to 5 parts per 100 parts by mass of the resin, from the viewpoint of making the composition capable of forming a cured product having excellent adhesive strength and low dielectric properties. parts by mass, more preferably 0.2 to 3 parts by mass, and even more preferably 0.2 to 1 part by mass.

<Component (B): Polyphenylene ether resin>
The curable adhesive composition used in one aspect of the present invention is a composition capable of forming a cured product with improved adhesive strength and low dielectric properties, as well as from the viewpoint of adjusting the peel strength (R1) or (R2). It is preferable to contain the polyphenylene ether resin (B) from the viewpoint of
In addition, polyphenylene ether resin (B) may be used independently and may use 2 or more types together.

In the curable adhesive composition used in one aspect of the present invention, the content of component (B) is preferably 5 parts by mass or more, more preferably 12 parts by mass, with respect to 100 parts by mass of the total amount of component (A). Above, more preferably 17 parts by mass or more, preferably 80 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 40 parts by mass or less.

From the viewpoint of adjusting the peel strength (R1) or (R2), and from the viewpoint of forming a composition capable of forming a cured product with improved adhesive strength and low dielectric properties, the polyphenylene ether resin used in one embodiment of the present invention ( The number average molecular weight (Mn) of B) is preferably 1500 or more, more preferably 1700 or more, and still more preferably 1900 or more. It is preferably 7,000 or less, more preferably 5,500 or less, and still more preferably 4,000 or less from the viewpoint of obtaining a composition having good solubility with and excellent coating properties.

The polyphenylene ether resin (B) used in one aspect of the present invention may be a resin having a structural unit represented by at least one of the following general formulas (bi) and (b-ii) in the main chain.

In general formula (b-i) or formula (b-ii) above, R ^a1 and R ^a2 each independently represent a halogen atom (fluorine atom, chlorine atom, bromine atom, or iodine atom) having 1 to 6 alkyl group or phenyl group, preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, still more preferably an alkyl group having 1 to 3 carbon atoms, methyl groups or ethyl groups are even more preferred, and methyl groups are particularly preferred.
Examples of alkyl groups having 1 to 6 carbon atoms that can be selected as R ^a1 and R ^a2 include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, t-butyl group, s -butyl group, isobutyl group, n-pentyl group, n-hexyl group and the like.
m1 and m2 are each independently an integer of 0 to 4, preferably an integer of 0 to 3, more preferably an integer of 0 to 2, and still more preferably 2.

From the viewpoint of adjusting the peel strength (R1) or (R2), and from the viewpoint of making the composition capable of forming a cured product with improved adhesion strength while improving low dielectric properties, it is one aspect of the present invention. The polyphenylene ether resin (B) used is preferably a resin having a skeleton represented by the following formula (b-1) as a main chain.

In general formula (b-1) above, R ^a1 and R ^a2 , and m1 and m2 are the same as defined in general formula (bi) or formula (b-ii) above; The same applies to types and numerical ranges.
X is a divalent organic group, and at least one hydrogen atom of the organic group may be substituted with a substituent.
p1 and p2 are each independently an integer of 0 or greater, and p1+p2 is an integer of 1 or greater.
* indicates the bonding position with the terminal group.

Examples of divalent hydrocarbon groups that can be selected as X include an alkylene group having 1 to 20 carbon atoms, an oxyalkylene group having 1 to 20 carbon atoms, an alkenylene group having 1 to 20 carbon atoms, and a ring-forming carbon atom number of 3. to 10 cycloalkylene groups, cycloalkenylene groups having 3 to 10 ring-forming carbon atoms, phenylene groups, biphenylene groups, terphenylene groups, naphthylene groups, groups formed by combining two or more of these groups, and the like.
The alkylene group, oxyalkylene group, and alkenylene group described above may be linear or branched.
The alkylene group, oxyalkylene group, and alkenylene group have a substituent selected from a halogen atom, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, and a cycloalkyl group having 3 to 10 carbon atoms. may
In addition, the cycloalkylene group, cycloalkenylene group, phenylene group, biphenylene group, terphenylene group, and naphthylene group are halogen atoms, alkyl groups having 1 to 6 carbon atoms, oxyalkyl groups having 1 to 6 carbon atoms, and may have a substituent selected from alkenyl groups having 1 to 6 carbon atoms.

Among these, from the viewpoint of adjusting the peel strength (R1) or (R2), and from the viewpoint of making the composition capable of forming a cured product with improved adhesive strength, X is the following formula (b-2) is preferably a group represented by

In general formula (b-2) above, R ^b1 and R ^b2 each independently represent a halogen atom (fluorine atom, chlorine atom, bromine atom, or iodine atom), an alkyl group having 1 to 6 carbon atoms, and an oxyalkyl group having 1 to 6 carbon atoms or an alkenyl group having 1 to 6 carbon atoms, preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and 1 to 6 carbon atoms; An alkyl group of 3 is more preferred, a methyl group or an ethyl group is even more preferred, and a methyl group is particularly preferred.
Examples of alkyl groups having 1 to 6 carbon atoms that can be selected as R ^b1 and R ^b2 include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, t-butyl group, s -butyl group, isobutyl group, n-pentyl group, n-hexyl group and the like.
n1 and n2 are each independently an integer of 0 to 4, preferably an integer of 0 to 3, more preferably an integer of 1 to 3, and still more preferably 3.

In general formula (b-2) above, A is a single bond or a divalent hydrocarbon group.
The divalent hydrocarbon group that can be selected as A includes, for example, an alkylene group having 1 to 20 carbon atoms, an oxyalkylene group having 1 to 20 carbon atoms, an alkenylene group having 1 to 20 carbon atoms, and a ring-forming carbon atom number of 3. to 10 cycloalkylene groups and 3 to 10 ring-forming carbon atoms cycloalkenylene groups.
The alkylene group, oxyalkylene group, and alkenylene group may be linear or branched.
Further, the hydrocarbon group that can be selected as A includes a substituent selected from a halogen atom, an alkyl group having 1 to 6 carbon atoms, an oxyalkyl group having 1 to 6 carbon atoms, and an alkenyl group having 1 to 6 carbon atoms. may have.
Among these, from the viewpoint of adjusting the peel strength (R1) or (R2), and from the viewpoint of making the composition capable of forming a cured product with improved adhesive strength, A is a single bond or has 1 to 1 carbon atoms. 20 alkylene groups are preferred, and single bonds are more preferred.

From the viewpoint of adjusting the peel strength (R1) or (R2), and from the viewpoint of forming a composition capable of forming a cured product with improved adhesive strength, the polyphenylene ether resin (B) used in one embodiment of the present invention is , as the main chain, the resin is more preferably a resin having a skeleton represented by the following formula (b-3).

In general formula (b-3) above, R ^a1 and R ^a2 are the same as defined in general formula (bi) or formula (b-ii) above. are the same.
Further, R ^b1 and R ^b2 are the same as defined in the general formula (b-2) above, and the types and numerical ranges of suitable groups are also the same.
p1 and p2 are each independently an integer of 0 or greater, and p1+p2 is an integer of 1 or greater.
* indicates the bonding position with the terminal group.
R ^a1 , R ^a2 , R ^b1 , and R ^b2 in the general formula (b-3) are each independently preferably an alkyl group having 1 to 6 carbon atoms, and preferably 1 to 4 carbon atoms. is more preferred, an alkyl group having 1 to 3 carbon atoms is more preferred, a methyl group or an ethyl group is even more preferred, and a methyl group is particularly preferred.

The polyphenylene ether resin (B) used in one aspect of the present invention forms a cured product with improved peel strength (R1) or (R2), low dielectric properties, crosslinkability, and heat resistance. Polyphenylene ether resin having a vinyl group is preferable from the viewpoint of making a composition that can be used.
The vinyl group that the polyphenylene ether resin (B) has may be one that constitutes a part of the hydrocarbon substituent, such as vinylbenzyl group and vinylnaphthyl group. That is, the polyphenylene ether resin (B) is formed by bonding a vinyl group or a vinyl group-containing hydrocarbon group to a polyphenylene ether skeleton.

Polyphenylene used in one aspect of the present invention from the viewpoint of adjusting the peel strength (R1) or (R2), and from the viewpoint of forming a composition capable of forming a cured product having excellent low dielectric properties, crosslinkability, and heat resistance The ether resin (B) is preferably a resin having a vinyl group or a vinyl group-containing hydrocarbon group at both ends of the main chain.
A polyphenylene ether resin (B) having a vinyl group or a vinyl group-containing hydrocarbon group at both ends of the main chain forms a polyphenylene ether skeleton to be the main chain, and then has a vinyl group or a vinyl group-containing hydrocarbon group at both ends. can be obtained by introducing
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 convert the terminal phenolic hydroxyl groups to vinyl. By benzyl etherifying, a polyphenylene ether resin (B) having vinylbenzyl groups at both ends of the polyphenylene ether skeleton can be obtained.

The polyphenylene ether resin (B) used in one aspect of the present invention is preferably a compound represented by the following general formula (b-4).

p1 and p2 are each independently an integer of 0 or greater, and p1+p2 is an integer of 1 or greater.

A commercially available product can also be used as the polyphenylene ether resin (B) used in one aspect of the present invention. Examples of commercially available products include OPE-2St (compound represented by the above general formula (b-4)) manufactured by Mitsubishi Gas Chemical Company, Inc., and the like.

<Component (C): Polyfunctional compound>
The curable adhesive composition used in one aspect of the present invention preferably contains a polyfunctional compound (C) having two or more unsaturated hydrocarbon groups with double bonds at their terminals. The polyfunctional compound (C) in the present invention excludes compounds corresponding to the components (A) and (B).
By forming a composition containing a polyfunctional compound (C) together with the polyphenylene ether resin (B) described above, it is possible to form a cured product with improved low dielectric properties and adhesive strength in a well-balanced manner. In particular, since the polyfunctional compound (C) has two or more unsaturated hydrocarbon groups, a crosslinked structure is formed in the obtained cured product, thereby forming a cured product with further improved adhesive strength. .
In addition, polyfunctional compound (C) may be used independently and may use 2 or more types together.

In the curable adhesive composition used in one aspect of the present invention, the content of the component (C) is a composition capable of forming a cured product excellent in low dielectric properties with respect to 100 parts by mass of the total amount of the component (A). It is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and still more preferably 20 parts by mass or more, from the viewpoint of obtaining a curable adhesive sheet with improved sticking properties while maintaining a product, and component (C) As the content of increases, the peel strength (R1) and peel strength (R2) tend to increase, so a curable adhesive sheet adjusted to reduce the peel strength (R1) or peel strength (R2) from the viewpoint of reducing the content, it is preferably 80 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 40 parts by mass or less.

In the curable adhesive composition used in one aspect of the present invention, from the viewpoint of forming a composition capable of forming a cured product with improved low dielectric properties, adhesive strength, and heat resistance in a well-balanced manner, the component (B) and the component The content ratio [(B)/(C)] with (C) is preferably 15/85 or more, more preferably 30/70 or more, and preferably 85/15 or less, in terms of mass ratio. Preferably it is 70/30 or less.

In the curable adhesive composition used in one aspect of the present invention, the total content of component (B) and component (C) is the peel strength (R1) or ( It is preferable from the viewpoint of making a curable adhesive sheet adjusted to reduce R2) while providing a curable adhesive sheet with excellent sticking properties, and from the viewpoint of making a composition capable of forming a cured product with excellent adhesive strength. is 85 parts by mass or less, more preferably 75 parts by mass or less, still more preferably 65 parts by mass or less, preferably 15 parts by mass or more, more preferably 25 parts by mass or more, and still more preferably 35 parts by mass or more .

The number of carbon atoms in the unsaturated hydrocarbon group per one of the polyfunctional compound (C) used in one aspect of the present invention is preferably 2 to 7, more preferably 2 to 4, still more preferably 2 to 3.
Examples of the unsaturated hydrocarbon group include vinyl group, allyl group, 3-butenyl group, 4-pentenyl group, 5-hexenyl group, isopropenyl group, 1-methyl-2-propenyl group and vinylbenzyl group. , a vinyl naphthyl group, and the like.
Among these, the unsaturated hydrocarbon group possessed by the polyfunctional compound (C) is preferably an allyl group.

The number of the unsaturated hydrocarbon groups possessed by the polyfunctional compound (C) used in one aspect of the present invention is 2 or more, but the crosslinked structure is moderately sparse, and a cured product in which the generation of cracks is suppressed is obtained. A composition that can be formed from the viewpoint of a composition that can be formed, and a composition that can suppress curing shrinkage in the adhesion process of making a cured product from a curable adhesive layer and reduce warping of a plate-like member such as a circuit board that is an adherend. From the viewpoint of, preferably 2 to 4, more preferably 2 to 3, more preferably 2.

From the viewpoint of making a composition capable of forming a cured product with improved low dielectric properties and adhesive strength in a well-balanced manner, the polyfunctional compound (C) used in one embodiment of the present invention has two unsaturated hydrocarbon groups. A polyfunctional compound having the above and further having a saturated hydrocarbon group is preferred.
From the above viewpoint, the polyfunctional compound (C) used in one embodiment of the present invention preferably has 1 to 4 saturated hydrocarbon groups, more preferably 1 to 2, and still more preferably 1.

Examples of the saturated hydrocarbon group include an alkyl group and an alkyl group substituted with an alkoxy group.
Examples of the alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, t-butyl group, s-butyl group, isobutyl group, 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 and the like.
The number of carbon atoms in the alkyl group is preferably 1-20, more preferably 4-18, even more preferably 6-16, still more preferably 8-15.

Examples of the alkyl group substituted with the alkoxy group include methoxymethyl group, ethoxymethyl group, 2-methoxyethoxymethyl group, benzyloxymethyl group and the like.
The number of carbon atoms in the alkyl group substituted with the alkoxy group is preferably 2-15, more preferably 2-12, and still more preferably 3-10.

The polyfunctional compound (C) used in one aspect of the present invention preferably contains the polyfunctional compound (C1) having two unsaturated hydrocarbon groups.
As described above, the composition containing the polyfunctional compound (C1) having two unsaturated hydrocarbon groups suppresses the occurrence of cracks and causes warping of a plate-like member such as a circuit board as an adherend. It can be a composition capable of forming a cured product with reduced dielectric properties and a composition capable of forming a cured product with further improved low dielectric properties and adhesive strength.
From the above viewpoint, the polyfunctional compound (C1) is more preferably a polyfunctional compound having two unsaturated hydrocarbon groups and at least one saturated hydrocarbon group.

From the above viewpoint, in the curable adhesive composition used in one aspect of the present invention, the content of the polyfunctional compound (C1) is the total amount of the component (C) contained in the curable adhesive composition (100 mass %), preferably 50 to 100% by mass, more preferably 70 to 100% by mass, even more preferably 80 to 100% by mass, and even more preferably 90 to 100% by mass.

The polyfunctional compound (C) used in one aspect of the present invention is preferably a polyfunctional compound having a heterocyclic skeleton. By containing a polyfunctional compound having a heterocyclic skeleton, it is possible to obtain a composition capable of forming a cured product with improved low dielectric properties and adhesive strength.
Specific heterocyclic skeletons include isocyanurate skeletons and glycoluril skeletons.

Examples of the polyfunctional compound (C) used in one embodiment of the present invention include compounds having an isocyanurate skeleton represented by the following general formula (c-1), and glycoluril represented by the following general formula (c-2). A compound having a skeleton can be mentioned.

In general formula ⁽ c-1), R ¹¹ to R ¹³ are each independently an unsaturated hydrocarbon group having a double bond at the ^end or a saturated hydrocarbon group, are the unsaturated hydrocarbon groups.
In general formula (c-2), R ²¹ to R ²⁶ are each independently a hydrogen atom, an unsaturated hydrocarbon group having a terminal double bond, or a saturated hydrocarbon group, At least two of R ²¹ to R ²⁶ are the unsaturated hydrocarbon groups.
Specific examples of unsaturated hydrocarbon groups and saturated hydrocarbon groups that can be selected as R ¹¹ to R ¹³ and R ²¹ to R ²⁶ are as described above, and the preferred carbon number ranges are also as described above. .

A composition that can form a cured product in which crack generation is suppressed and warpage of a plate-like member such as a circuit board as an adherend is reduced, and a cured product with low dielectric properties and further improved adhesive strength is provided. From the viewpoint of forming a composition that can be formed, the polyfunctional compound (C) used in one embodiment of the present invention preferably contains a compound having an isocyanurate skeleton represented by the general formula (c-1), It more preferably contains a compound (C11) having an isocyanurate skeleton represented by the following general formula (c-11).

In general formula (c-11) above, R ^a is a saturated hydrocarbon group, and specific examples thereof are as described above.
Among these, R ^a is preferably an alkyl group. The number of carbon atoms in the alkyl group is preferably 1-20, more preferably 4-18, even more preferably 6-16, still more preferably 8-15.

From the above viewpoint, in the curable adhesive composition used in one aspect of the present invention, the content of the compound (C11) is based on the total amount (100% by mass) of the component (C) contained in the curable adhesive composition. , preferably 50 to 100% by mass, more preferably 70 to 100% by mass, even more preferably 80 to 100% by mass, and even more preferably 90 to 100% by mass.

Note that a commercially available product may be used as the polyfunctional compound (C) used in one embodiment of the present invention.
Specific commercial products include, for example, L-DAIC (product name, manufactured by Shikoku Kasei Kogyo Co., Ltd., compound represented by the general formula (c-11)), TAIC (registered trademark) (product name, Mitsubishi Chemical Co., Ltd., a compound in which R ¹¹ to R ¹³ in the general formula (c-1) are allyl groups), TA-G (product name, manufactured by Shikoku Kasei Kogyo Co., Ltd., in the general formula (c-2) compounds represented) and the like.

The molecular weight (formula weight) of the polyfunctional compound (C) used in one aspect of the present invention is the viewpoint of making the composition easy to form a cured product having desired physical properties, and the smaller the molecular weight of the component (C), the , Since the peel strength (R1) and the peel strength (R2) tend to increase, from the viewpoint of a curable adhesive sheet adjusted to reduce the peel strength (R1) or the peel strength (R2), preferably 200 or more, more preferably 230 or more, still more preferably 270 or more, and preferably 1000 or less, more preferably 800 or less from the viewpoint of making the composition easy to form a curable adhesive layer that can be easily applied at room temperature. , more preferably 500 or less.

The boiling point of the polyfunctional compound (C) used in one aspect of the present invention is preferably 175 to 350°C, more preferably 200 to 300°C.
Moreover, the 5% weight loss temperature of the polyfunctional compound (C) used in one aspect of the present invention is preferably 175 to 350°C, more preferably 200 to 300°C.

In addition, from the viewpoint of making a composition capable of forming a cured product excellent in low dielectric properties and making it a composition that easily forms a curable adhesive layer that can be easily applied at room temperature, the polyfunctional adhesive used in one embodiment of the present invention The liquid compound (C) is preferably a compound that is liquid at 25°C.
In this specification, "a compound that is liquid at 25°C" refers to a compound that has fluidity at 25°C. means a compound having a viscosity of 2 to 10,000 mPa·s as measured by

<Component (D): Cationic polymerization initiator>
The curable adhesive composition used in one aspect of the present invention preferably further contains a cationic polymerization initiator (D).
By making the curable adhesive composition containing the cationic polymerization initiator (D), the polymerization reaction of the component (B) and the component (C) is sufficiently advanced, and the curable adhesive layer formed is preserved. Stability can be improved.
In addition, a cationic polymerization initiator (D) may be used independently and may use 2 or more types together.

In the curable adhesive composition used in one aspect of the present invention, the content of component (D) is such that component (B) and component ( From the viewpoint of making the composition capable of sufficiently advancing the polymerization reaction of component C and forming a curable adhesive layer with improved storage stability, the amount is preferably 0.01 parts by mass or more, more preferably 0.05. parts by mass or more, more preferably 0.10 parts by mass or more, still more preferably 0.15 parts by mass or more, still more preferably 0.20 parts by mass or more, even more preferably 0.25 parts by mass or more, and particularly preferably 0.25 parts by mass or more. 30 parts by mass or more, preferably 6.0 parts by mass or less, more preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, even more preferably 2.0 parts by mass or less, still more preferably is 1.5 parts by mass or less, more preferably 1.0 parts by mass or less, and particularly preferably 0.70 parts by mass or less.

The cationic polymerization initiator (D) used in one aspect of the present invention may be a thermal cationic polymerization initiator or a photocationic polymerization initiator, and the polymerization can be carried out in a simple process. From this point of view, a thermal cationic polymerization initiator is preferred.

The thermal cationic polymerization initiator used in one aspect of the present invention is a compound capable of generating a cationic species that initiates polymerization by heating. are mentioned.
These thermal cationic polymerization initiators may be used alone or in combination of two or more.

Sulfonium salts include, for example, triphenylsulfonium tetrafluoroborate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluoroalcinate, tris(4-methoxyphenyl)sulfonium hexafluoroalcinate, diphenyl(4-phenylthiophenyl ) sulfonium hexafluoroalcinate and the like.
In addition, commercially available sulfonium salts can also be used. SI-80L, San-Aid SI-100L, San-Aid SI-B2A, San-Aid SI-B3 (manufactured by Sanshin Chemical Industry Co., Ltd.), CYRACURE UVI-6974, CYRACURE UVI-6990 (manufactured by Union Carbide), UVI -508, UVI-509 (manufactured by General Electric Co.), FC-508, FC-509 (manufactured by Minnesota Mining and Manufacturing Co.), CD-1010, CD-1011 (manufactured by Thurstomer (manufactured by Nippon Soda Co., Ltd.), CI series products (manufactured by Nippon Soda Co., Ltd.), and the like.

Examples of quaternary ammonium salts include tetrabutylammonium tetrafluoroborate, tetrabutylammonium hexafluorophosphate, tetrabutylammonium hydrogensulfate, tetraethylammonium tetrafluoroborate, tetraethylammonium p-toluenesulfonate, N,N-dimethyl- N-benzylanilinium hexafluoroantimonate, N,N-dimethyl-N-benzylanilinium tetrafluoroborate, N,N-dimethyl-N-benzylpyridinium hexafluoroantimonate, N,N-diethyl-N-benzyltrifluoro romethanesulfonate, N,N-dimethyl-N-(4-methoxybenzyl)pyridinium hexafluoroantimonate, N,N-diethyl-N-(4-methoxybenzyl)toluidinium hexafluoroantimonate and the like.

Phosphonium salts include, for example, ethyltriphenylphosphonium hexafluoroantimonate, tetrabutylphosphonium hexafluoroantimonate, and the like.

Examples of diazonium salts include AMERICURE (manufactured by American Can) and ULTRASET (manufactured by ADEKA).

Examples of iodonium salts include diphenyliodonium hexafluoroarcinate, bis(4-chlorophenyl)iodonium hexafluoroarcinate, bis(4-bromophenyl)iodonium hexafluoroarcinate, phenyl(4-methoxyphenyl)iodonium hexafluoroalkinate, and the like.
Commercially available iodonium salts can also be used, such as UV-9310C (manufactured by Toshiba Silicone Co., Ltd.), Photoinitiator 2074 (manufactured by Rhone-Poulenc), UVE series products (manufactured by General Electric), FC series. (manufactured by Minnesota Mining and Manufacturing Co.).

When the curable adhesive composition of one aspect of the present invention contains the cationic polymerization initiator (D), at least part of the cationic polymerization initiator (D) is subjected to differential scanning calorimetry under the following conditions. It may be a high-temperature reactive thermal cationic polymerization initiator that gives a peak top temperature of an exothermic peak exceeding 120°C.
(Differential scanning calorimetry conditions)
A mixture containing 0.1 part by mass of a cationic polymerization initiator to be measured, 100 parts by mass of bisphenol A diglycidyl ether, and 0.1 part by mass of γ-butyrolactone was used as a measurement sample, and the temperature was changed from 30°C to 300°C. Differential scanning calorimetry is performed at a heating rate of 10°C/min to measure the peak temperature of the exothermic peak.

Examples of commercially available high-temperature reactive thermal cationic polymerization initiators include San-Aid SI-B3, San-Aid SI-B4, San-Aid SI-B5, and San-Aid SI-150 (all manufactured by Sanshin Chemical Industry Co., Ltd.). .

<Reactive curing agent other than cationic polymerization initiator (D)>
The curable adhesive composition used in one aspect of the present invention, in place of the cationic polymerization initiator (D), or together with the cationic polymerization initiator (D), in a range that does not impair the effects of the present invention, cationic polymerization initiation Other reactive curing agents than the agent (D) may be contained.
In the curable adhesive composition used in one aspect of the present invention, the content of the other reactive curing agent is 0 to 90 parts by mass and 0 to 50 parts by mass with respect to 100 parts by mass of the total amount of component (D). , 0 to 40 parts by weight, 0 to 30 parts by weight, 0 to 20 parts by weight, 0 to 10 parts by weight, 0 to 5.0 parts by weight, 0 to 2.0 parts by weight, 0 to 1.0 parts by weight, 0 It may be up to 0.10 parts by mass, 0 to 0.010 parts by mass, or 0 to 0.0010 parts by mass.
On the other hand, when the curable adhesive composition of one aspect of the present invention does not contain the cationic polymerization initiator (D), the content of the other reactive curing agent is the total of component (B) and component (C) 0.01 parts by mass or more, 0.05 parts by mass or more, 0.10 parts by mass or more, 0.15 parts by mass or more, 0.20 parts by mass or more, 0.25 parts by mass or more with respect to the amount of 100 parts by mass, Alternatively, it may be 0.30 parts by mass or more, and 6.0 parts by mass or less, 5.0 parts by mass or less, 3.0 parts by mass or less, 2.0 parts by mass or less, 1.5 parts by mass or less, 1. It may be 0 parts by mass or less, or 0.70 parts by mass or less.

Examples of reactive curing agents (D) other than cationic polymerization initiators include amine compounds such as benzylmethylamine and 2,4,6-trisdimethylaminomethylphenol; 2-methylimidazole, 2-ethyl-4-methyl imidazole compounds such as imidazole and 2-heptadecyl imidazole; Lewis acids such as boron trifluoride/monoethylamine complex and boron trifluoride/piperazine complex; peroxides such as di(t-butylperoxy)diisopropylbenzene; is mentioned.

<Component (E): Crosslinking agent>
When the curable adhesive composition used in one aspect of the present invention contains a binder resin having a reactive functional group as component (A), it further contains a cross-linking agent (E) capable of reacting with the reactive functional group. is preferred.
By using a composition that further contains the cross-linking agent (E) together with the component (A), it is possible to form a curable adhesive layer that is highly effective in suppressing the exudation of the adhesive component. That is, in the process of forming a curable adhesive layer from a coating film formed from a curable adhesive composition, the reactive functional groups of the crosslinking agent (E) and the binder resin (A) react with each other to form a coating film. A crosslinked structure is formed inside, and a curable adhesive layer that is difficult to fluidize even when heated can be formed. As a result, the formed curable adhesive layer is adhered to an adherend such as a circuit board, cured, and adhered to the adherend. become more difficult to occur. Also from the viewpoint of adjusting the peel strength (R1) or (R2), it is preferable to use a composition containing a cross-linking agent (E).
The cross-linking agent (E) may be used alone or in combination of two or more.

In the curable adhesive composition used in one aspect of the present invention, the content of component (E) is preferably 0.01 parts by mass or more, more preferably 0 parts by mass, relative to 100 parts by mass of the total amount of component (A). 0.03 parts by mass or more, more preferably 0.05 parts by mass or more, more preferably 0.07 parts by mass or more, still more preferably 0.10 parts by mass or more, still more preferably 0.15 parts by mass or more, still more preferably 0 .20 parts by mass or more, more preferably 0.25 parts by mass or more, particularly preferably 0.30 parts by mass or more, and preferably 10.0 parts by mass or less, more preferably 8.0 parts by mass or less, more preferably 6.0 parts by mass or less, more preferably 5.0 parts by mass or less, even more preferably 4.0 parts by mass or less, still more preferably 3.0 parts by mass or less, and even more preferably 2.5 parts by mass or less; More preferably 2.0 parts by mass or less, particularly preferably 1.5 parts by mass or less.

The molecular weight of the cross-linking agent (E) used in one aspect of the present invention increases the probability of reaction with the component (A), facilitates the formation of a cross-linked structure, and has a higher effect of suppressing the exudation of the adhesive component. It is preferably 1000 or less, more preferably 800 or less, still more preferably 700 or less, still more preferably 600 or less, and particularly preferably 500 or less, from the viewpoint of a composition capable of forming an agent layer. A composition that adjusts so that the cross-linking agent (E) can remain in the curable adhesive layer by heating in the drying step of forming the agent layer, and can express the effect of adding the cross-linking agent (E). from the viewpoint of achieving, it is preferably 100 or more, more preferably 150 or more, still more preferably 200 or more, even more preferably 250 or more, and particularly preferably 300 or more.

The cross-linking agent (E) used in one aspect of the present invention is appropriately selected according to the type of reactive functional group possessed by the component (A). , aziridine-based cross-linking agents, and the like.
Among these, from the viewpoint of storage stability, the cross-linking agent (E) used in one embodiment of the present invention is preferably at least one selected from isocyanate-based cross-linking agents, epoxy-based cross-linking agents, and metal chelate-based cross-linking agents.
From the viewpoint of making a composition capable of forming a cured product with further improved low dielectric properties, the cross-linking agent (E) used in one embodiment of the present invention is preferably a cross-linking agent having an isocyanurate skeleton.

The isocyanate-based cross-linking agent is preferably a compound having two or more isocyanate groups in the molecule. 5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, diphenylmethane-4,4-diisocyanate, isophorone diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, tetramethylxylylene diisocyanate, 1,5-naphthalene diisocyanate, Examples include triphenylmethane triisocyanate, adducts of these polyisocyanate compounds and polyol compounds such as trimethylolpropane, burettes and isocyanurates of these polyisocyanate compounds, and the like.

The epoxy-based cross-linking agent is preferably a compound having two or more epoxy groups in the molecule. -m-xylylenediamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidylaniline, diglycidylamine and the like.

Metal chelate-based cross-linking agents include chelate compounds having metal ions functioning as cross-linking points. Examples of such metal ions include aluminum ions, zirconium ions, titanium ions, zinc ions, iron ions, and tin ions.
Among these, the metal chelate-based cross-linking agent is preferably an aluminum chelate compound. and aluminum bisoleyl acetoacetate.

Among these, from the viewpoint of making a composition capable of forming a curable adhesive layer having a higher effect of suppressing the exudation of the adhesive component and a composition capable of forming a cured product with further improved low dielectric properties. The cross-linking agent (E) used in one aspect of the present invention is preferably an isocyanate-based cross-linking agent, more preferably an isocyanurate of a polyisocyanate compound, and an isocyanurate of 1,5-pentamethylene diisocyanate [1,3,5 -tris(5-isocyanatopentyl)-1,3,5-triazine-2,4,6-trione] and the isocyanurate of 1,6-hexamethylene diisocyanate [1,3,5-tris(6-isocyanate hexyl)-1,3,5-triazine-2,4,6-trione] is more preferable.

<Component (F): Silane coupling agent>
The curable adhesive composition used in one aspect of the present invention preferably further contains a silane coupling agent (F).
By using a composition containing a silane coupling agent, a cured product with improved adhesive strength can be formed.
In addition, the silane coupling agent (F) may be used alone or in combination of two or more.

In the curable adhesive composition used in one aspect of the present invention, the content of component (F) is preferably 0.001 parts by mass or more, more preferably 0 parts by mass, relative to 100 parts by mass of the total amount of component (A). 0.005 parts by mass or more, more preferably 0.01 parts by mass or more, more preferably 0.03 parts by mass or more, still more preferably 0.05 parts by mass or more, still more preferably 0.07 parts by mass or more, still more preferably 0 .10 parts by mass or more, more preferably 0.12 parts by mass or more, particularly preferably 0.15 parts by mass or more, and preferably 6.0 parts by mass or less, more preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, more preferably 3.0 parts by mass or less, even more preferably 2.0 parts by mass or less, even more preferably 1.5 parts by mass or less, and even more preferably 1.0 parts by mass or less; More preferably 0.80 parts by mass or less, particularly preferably 0.60 parts by mass or less.

The silane coupling agent (E) used in one aspect of the present invention is preferably an organosilicon compound having at least one alkoxysilyl group in the molecule.
Specific silane coupling agents include, for example, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3 - Silane coupling agents having a (meth)acryloyl group such as acryloxypropyltrimethoxysilane; vinyltrimethoxysilane, vinyltriethoxysilane, dimethoxymethylvinylsilane, diethoxymethylvinylsilane, trichlorovinylsilane, vinyltris(2-methoxyethoxy) Silane coupling agents having a vinyl group such as silane; 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3- Silane coupling agents having an epoxy group such as glycidoxypropyltriethoxysilane and 8-glycidoxyoctyltrimethoxysilane; silane coupling agents having a styryl group such as p-styryltrimethoxysilane and p-styryltriethoxysilane Agent; N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltri Ethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane , N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, silane coupling agents having an amino group; 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, etc. Silane coupling agents having a ureido group of; Silane coupling agents having halogen atoms such as 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane; 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxy silane coupling agents having a mercapto group such as silane; bis (trimethoxysilylpropyl) tetrasulfide, silane coupling agents having a sulfide group such as bis (triethoxysilylpropyl) tetrasulfide; 3-isocyanatopropyltrimethoxysilane, Silane coupling agents having an isocyanate group such as 3-isocyanatopropyltriethoxysilane; Silane coupling agents having an allyl group such as allyltrichlorosilane, allyltriethoxysilane, allyltrimethoxysilane; 3-hydroxypropyltrimethoxysilane , a silane coupling agent having a hydroxyl group such as 3-hydroxypropyltriethoxysilane;

<Cyclic ether compound>
The curable adhesive composition used in one aspect of the present invention may also be a composition containing a cyclic ether compound.
Any compound having a cyclic ether group can be used as the cyclic ether compound.
The cyclic ether group includes, for example, an oxirane group (epoxy group), an oxetane group (oxetanyl group), a tetrahydrofuryl group, a tetrahydropyranyl group and the like.
In this specification, the oxirane group includes groups having an oxirane structure such as glycidyl group, glycidyl ether group and epoxycyclohexyl group.
In addition, a cyclic ether compound may be used independently and may use 2 or more types together.

A composition containing a cyclic ether compound has the property of being able to form a cured product having excellent adhesive strength, but the cured product has a large relative dielectric constant and dielectric loss tangent value, and the above-mentioned component (B) and ( The low dielectric properties tend to be inferior to compositions containing component C) and not containing a cyclic ether compound.

In the curable adhesive composition used in one aspect of the present invention, the content of the cyclic ether compound is less than 5.0% by mass with respect to the total amount (100% by mass) of the active ingredients of the curable adhesive composition. , less than 3.0% by weight, less than 1.0% by weight, less than 0.50% by weight, less than 0.10% by weight, less than 0.010% by weight, less than 0.0010% by weight, less than 0.00010% by weight, Alternatively, it may be less than 0.000010% by mass.
Further, in the curable adhesive composition used in one aspect of the present invention, the content of the cyclic ether compound is 100 parts by mass in total of the components (A) to (C) contained in the curable adhesive composition. On the other hand, less than 5.0 parts by mass, less than 3.0 parts by mass, less than 1.0 parts by mass, less than 0.50 parts by mass, less than 0.10 parts by mass, less than 0.010 parts by mass, 0.0010 parts by mass less than, less than 0.00010 parts by mass, or less than 0.000010 parts by mass.

<Inorganic filler>
The curable adhesive composition used in one aspect of the present invention may be a composition containing an inorganic filler, or may be a composition containing no inorganic filler.
Examples of inorganic fillers include silica, alumina, talc, aluminum hydroxide, magnesium hydroxide, titanium oxide, mica, aluminum borate, barium sulfate, boron nitride, forsterite, zinc oxide, magnesium oxide, calcium carbonate, and the like. are mentioned.
These inorganic fillers may be used alone or in combination of two or more.

However, the content of the inorganic filler in the curable adhesive composition used in one aspect of the present invention is preferably as low as possible.
In the curable adhesive composition used in one aspect of the present invention, the content of the inorganic filler is 0 to 30% by mass with respect to the total amount (100% by mass) of the active ingredients of the curable adhesive composition, 0-20% by mass, 0-10% by mass, 0-5.0% by mass, 0-2.0% by mass, 0-1.0% by mass, 0-0.1% by mass, 0-0.01% by mass %, or 0 to 0.001% by mass.
In addition, in the curable adhesive composition used in one aspect of the present invention, the content of the inorganic filler is 100 parts by mass of the total amount of components (A) to (C) contained in the curable adhesive composition. On the other hand, less than 50 parts by mass, less than 30 parts by mass, less than 10 parts by mass, less than 5.0 parts by mass, less than 1.0 parts by mass, less than 0.1 parts by mass, less than 0.01 parts by mass, 0.001 parts by mass or less than 0.0001 part by mass.

<Other additives>
The curable adhesive composition used in one aspect of the present invention may contain additives other than the above-described components within a range that does not impair the effects of the present invention.
Other additives include, for example, ultraviolet absorbers, antistatic agents, light stabilizers, antioxidants, resin stabilizers, pigments, extenders, softeners, and the like.
These additives may be used alone or in combination of two or more.
The content of these additives can be appropriately set according to the type of additive.
For example, the content of each additive is 0.001 to 30 parts by mass, 0.005 to 20 parts by mass, 0.005 to 20 parts by mass, and 0 0.01 to 10 parts by mass, or 0.03 to 5 parts by mass.

<Liquid active ingredient>
The curable adhesive composition used in one aspect of the present invention preferably contains an active ingredient that is liquid at 25°C. By using a composition containing a liquid active ingredient, it is possible to improve the sticking property of the formed curable adhesive layer.

In the curable adhesive composition used in one aspect of the present invention, the content of the active ingredient that is liquid at 25° C. is based on the total amount (100% by mass) of the active ingredient in the curable adhesive composition. From the viewpoint of making a composition capable of forming a curable adhesive layer excellent in As the content of the active ingredient in the liquid increases, the release force (R1) and release force (R2) tend to increase. From the viewpoint of making a flexible adhesive sheet, the content is preferably 50% by mass or less, more preferably 35% by mass or less, and even more preferably 25% by mass or less.

In addition, from the viewpoint of making a composition capable of forming a curable adhesive layer with excellent sticking properties and further making it a composition capable of forming a cured product with improved low dielectric properties and adhesive strength, one aspect of the present invention is At least one active ingredient that is liquid at 25° C. contained in the curable adhesive composition used in the embodiment is preferably a polyfunctional compound (C).
In the curable adhesive composition used in one aspect of the present invention, the content of the polyfunctional compound (C) with respect to the total amount (100% by mass) of the active ingredients that are liquid at 25°C is preferably 70% by mass or more, It is more preferably 80% by mass or more, still more preferably 85% by mass or more, and may be usually 100% by mass or less, preferably 99.0% by mass or less, more preferably 98.0% by mass or less.

<Dilution solvent>
The curable adhesive composition used in one aspect of the present invention may be in the form of a solution by further adding a diluent solvent.
Examples of diluent solvents used in one aspect of the present invention include 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; aliphatic hydrocarbon solvents such as n-pentane, n-hexane, and n-heptane; alicyclic hydrocarbon solvents such as cyclopentane, cyclohexane, and methylcyclohexane; and the like.
These diluent solvents may be used alone or in combination of two or more.
These diluent solvents may be the solvents used during the synthesis of the components (A) and (B) as they are, or the solvents other than the solvents used during the synthesis of the components (A) and (B). More than one kind of solvent may be added.

When the curable adhesive composition used in one aspect of the present invention is in the form of a solution, the concentration of the active ingredient in the curable adhesive composition is appropriately set so as to have a desired viscosity in consideration of applicability and the like. However, with respect to the total amount (100% by mass) of the curable adhesive composition, it may be preferably 3.0% by mass or more, more preferably 10% by mass or more, and preferably 70% by mass or less. , and more preferably 50% by mass or less.

[Method for producing curable adhesive sheet]
As a method for producing the curable adhesive sheet of one embodiment of the present invention, the curable adhesive composition described above is coated on the release layer of the first release film or the second release film by a known coating method. be able to.
From the viewpoint of improving the applicability to the release film, it is preferable to dilute the curable adhesive composition with a diluting solvent to form a solution.

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

After applying the curable adhesive composition to form a coating film, it is preferable to carry out a drying treatment.
Examples of the drying treatment method include hot air drying, hot roll drying, and infrared irradiation.
The drying conditions for the formed coating film are preferably 80° C. to 150° C. and heating for 30 seconds to 5 minutes (preferably 40 seconds to 3 minutes, more preferably 45 seconds to 2 minutes) to dry. Through this drying step, a curable adhesive layer can be formed on the release layer of the first release film or the second release film. Furthermore, by laminating the other release film on the exposed surface of the formed curable adhesive layer, the curable adhesive sheet of one embodiment of the present invention can be obtained. From the viewpoint of making it easier to obtain a curable adhesive sheet that satisfies the above requirement (III) or requirement (IV), a curable adhesive layer formed by applying a curable adhesive composition to the second release film It is preferable to laminate a first release film on the exposed surface of the.

When the curable adhesive composition used for forming the curable adhesive layer contains a cross-linking agent (E), a certain period of time (for example, 1 to 14 days) is required to complete the cross-linking reaction. It is preferable to go through a seasoning process to retain the degree of flavor).

[Method for producing cured product]
The present invention also provides a method for producing a cured product using the curable adhesive sheet of one embodiment of the present invention described above. The method for producing a cured product of the present invention preferably comprises the following steps (1) to (3).
Step (1): A step of peeling off the first release film and attaching the exposed curable adhesive layer to an adherend.
Step (2): A step of confirming that no foreign matter exists at the interface between the curable adhesive layer and the adherend by optical inspection means from the second release film side.
Step (3): After step (2), the step of curing the curable adhesive layer to obtain a cured product.

Step (1) is a step of peeling off the first release film and attaching the exposed curable adhesive layer to an adherend. In the curable adhesive sheet of one aspect of the present invention, even when the curable adhesive layer is sandwiched between the first release film and the second release film, the first release film can be easily peeled off from the curable adhesive layer. Therefore, it is easy to handle. In addition, handling is excellent in that the first release film and the second release film are visually distinguishable.

Step (2) is a step of confirming that no foreign matter exists at the interface between the curable adhesive layer and the adherend by optical inspection means from the second release film side. Since it is possible to check whether foreign matter is mixed in, it contributes to the improvement of product yield.

Step (3) is a step of curing the curable adhesive layer to obtain a cured product after step (2).
The method for curing the adhesive adhesive layer may be a heat curing method or a photo-curing method. Although it is selected depending on the type, the thermosetting method is preferable from the viewpoint of productivity.
The heating temperature for heat curing is preferably 80 to 200° C., more preferably 90 to 190° C., still more preferably 100 to 180° C., and the heating time is preferably 10 minutes to 12 hours, more preferably 30 minutes to 6 hours, more preferably 40 minutes to 3 hours.
Moreover, when performing thermosetting, it is preferable to perform a hot press. The pressure for hot pressing is preferably 0.1 to 10 MPa, more preferably 0.5 to 8.0 MPa, still more preferably 1.0 to 5.0 MPa.
When the curable adhesive layer is cured by a photo-curing method, a cured product can be obtained by irradiating the curable adhesive layer with energy rays such as ultraviolet rays.
Note that the method for producing a cured product using the curable adhesive sheet of one embodiment of the present invention is not limited to having step (2), and step (2) is provided between step (1) and step (3). May not be implemented.

[Method for using curable adhesive sheet, method for producing circuit board with cured product]
A cured product obtained by curing the curable adhesive layer of the curable adhesive sheet of one embodiment of the present invention is excellent in low dielectric properties in a high frequency region.
Therefore, the curable adhesive sheet of one aspect of the present invention is suitably used when forming a member in a device that requires low dielectric properties, and is particularly used as a cover lay sheet for protecting a circuit board. is preferred.
Examples of circuit boards include flexible printed circuit boards (FPC).

Since the curable adhesive layer of the curable adhesive sheet of one aspect of the present invention has the above properties, the present invention can also provide the following [1] and [2].
[1] The curable adhesive layer of the curable adhesive sheet of one aspect of the present invention is laminated to a circuit board, the curable adhesive layer is cured to obtain a cured product, and the cured product is obtained as described above. A method for using a curable adhesive sheet, which has a bonding step for bonding with a circuit board.
[2] The curable adhesive layer of the curable adhesive sheet of one aspect of the present invention is laminated to a circuit board, the curable adhesive layer is cured to obtain a cured product, and the cured product is obtained as described above. A method for producing a circuit board with a cured product, comprising a step of bonding the circuit board to the circuit board.

In the above [1] and [2], after the curable adhesive layer is laminated to the circuit board, the curable adhesive layer is inspected from the second release film side by optical inspection means. It is preferable to confirm that no foreign matter exists at the interface between the agent layer and the circuit board.
In the above [1] and [2], the method of curing the curable adhesive layer to obtain a cured product can be adjusted depending on the type of the reactive curing agent such as the component (D), etc., and the thermosetting method can be used. It may be a photo-curing method, and specifically, the same method as the step (3) of the above-described method for producing a cured product of one embodiment of the present invention can be mentioned.

EXAMPLES The present invention will be described in more detail below with reference to examples. However, the present invention is by no means limited to the following examples.
Further, each physical property value is a value measured by the method shown below.

[Number average molecular weight (Mn)]
Using a gel permeation chromatograph (manufactured by Tosoh Corporation, product name "HLC-8320 GPC"), measurement was performed under the following conditions, and the values measured in terms of standard polystyrene were used.
(Measurement condition)
Column: "TSK gel guard column super HH", "TSK gel super HM-H", "TSK gel super HM-H" and "TSK gel super H2000" are sequentially connected (both manufactured by Tosoh Corporation )
・Column temperature: 40°C
・Developing solvent: tetrahydrofuran ・Flow rate: 1.0 mL/min

[Thickness of each layer]
Using a constant pressure thickness measuring instrument (manufactured by Teclock Co., Ltd., product name "PG-02J"), the thickness was measured according to JIS K6783, Z1702, and Z1709.

[Peeling force (R1)]
A test sample was prepared by cutting the curable adhesive sheet to be measured into a size of 150 mm long×50 mm wide.
Then, one adhesive surface of the double-sided tape is attached to the surface of the test sample opposite to the surface in contact with the curable adhesive layer of the second release film, and the other adhesive surface of the double-sided tape is superimposed on the surface of the metal plate. , was crimped.
Then, in an environment of a temperature of 23 ° C. and a relative humidity of 50%, a precision universal testing machine (manufactured by Shimadzu Corporation, product name "Autograph AG-IS") was used to measure the peel force. A value measured when the release film was peeled off from a test sample fixed to a metal plate at a peel angle of 180° and a peel speed of 300 mm/min was defined as "peeling force (R1)".

[Peeling force (R2)]
The first release film is removed from the curable adhesive sheet to be measured, and the exposed adhesive surface is placed on the surface of a 25 μm thick polyimide film (manufactured by Toray DuPont Co., Ltd., Kapton 100H) and alkali-free glass. It was pressure-bonded at 100° C. using a laminator. Next, the curable adhesive sheet was cut together with the polyimide film into a size of 150 mm long×50 mm wide to prepare a test sample. One adhesive surface of the double-sided tape is attached to the surface of the polyimide film of the test sample opposite to the surface on which the curable adhesive layer is laminated, and the other adhesive surface of the double-sided tape is attached to the surface of the metal plate. stacked and pressed. This test sample was subjected to a peel test in the same manner as the peel force (R1) measurement described above. That is, in an environment with a temperature of 23 ° C. and a relative humidity of 50%, the second release film to be measured for peel force is peeled from the test sample fixed to the metal plate using the precision universal tester. The value measured when peeled under conditions of an angle of 180° and a peeling speed of 300 mm/min was defined as "peeling force (R2)".

Production Examples 1-2
(1) Preparation of curable adhesive composition The components shown in Table 1 are blended in the amounts shown in Table 1 (ratio of active ingredients), dissolved in toluene, and cured to a predetermined concentration of active ingredients. adhesive compositions (1) to (2) were prepared.
The details of each component used in the preparation of the curable adhesive compositions (1) and (2) are as follows.
<Component (A): Binder resin>
"Modified polyolefin": A solution containing a maleic anhydride-modified α-olefin polymer (solid at 25°C) with Mn = 47,000 (manufactured by Mitsui Chemicals, Inc., product name "Unistol H-200").
<Component (B): Polyphenylene ether resin>
- "Polyphenylene ether resin (b1)": a solution (Mitsubishi Gas Chemical Co., Ltd., product name “OPE-2St 2200”).
- "Polyphenylene ether resin (b2)": a solution (Mitsubishi Gas Chemical Co., Ltd., product name “OPE-2St 1200”).
<Component (C): Polyfunctional compound>
- "Polyfunctional compound": a compound having an isocyanurate skeleton, wherein R ^a in the general formula (c-11) is an alkyl group having 8 to 15 carbon atoms. Manufactured by Shikoku Kasei Co., Ltd., product name "L-DAIC", molecular weight = 377.27, liquid at 25°C.
<Component (D): Cationic polymerization initiator>
- "Thermal cationic polymerization initiator": A thermal cationic polymerization initiator (manufactured by Sanshin Chemical Industry Co., Ltd., product name "San-Aid SI-B3"), solid at 25°C.
<Component (E): Crosslinking agent>
・ “Isocyanate-based cross-linking agent”: 1,3,5-tris(5-isocyanatopentyl)-1,3,5-triazine-2,4,6-trione (manufactured by Mitsui Chemicals, Inc., product name “Stabio D- 370N"), molecular weight = 462, liquid at 25°C.
<Component (F): Silane coupling agent>
- "Silane coupling agent": 8-glycidoxyoctyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd., product name "KBM4803"), liquid at 25°C.

Examples 1 to 4, Comparative Example 1
The curable adhesive compositions used in the following Examples and Comparative Examples, which are materials for forming the release film and the curable adhesive layer, are as follows.
<First release film>
- Non-silicone release film (1): Product name "PC38 AL-5", manufactured by Lintec Corporation, a non-silicone having a release layer formed from an alkyd release agent on a polyethylene terephthalate (PET) film made white by foaming Silicone-based release film, thickness: 38 μm.
<Second release film>
・ Non-silicone release film (2): product name “SP-PET50 AL-5”, manufactured by Lintec Corporation, a non-silicone release film having a release layer formed from an alkyd release agent on a colorless PET film, thick Thickness: 50 μm.
・ Non-silicone release film (3): product name “SP-PET75 AL-5”, manufactured by Lintec Corporation, a non-silicone release film having a release layer formed from an alkyd release agent on a colorless PET film, thick Thickness: 75 μm.
・ Non-silicone release film (4): product name “SP-PET38 AL-5”, manufactured by Lintec Corporation, a non-silicone release film having a release layer formed from an alkyd release agent on a colorless PET film, thick Thickness: 38 μm.
<Material for Forming Curable Adhesive Layer>
• Curable adhesive composition (1): Curable adhesive composition (1) prepared according to the composition shown in Table 1 in Production Example 1.
• Curable adhesive composition (2): Curable adhesive composition (2) prepared according to the composition shown in Table 1 in Production Example 2.

The curable adhesive composition shown in Table 1 is applied onto the release layer of the second release film shown in Table 2 to form a coating film, the coating film is dried, and the curable adhesive composition having a thickness of 25 μm is applied. An agent layer was formed.
Further, the exposed surface of the formed curable adhesive layer and the release layer of the first release film shown in Table 2 were laminated to prepare a curable adhesive sheet.

Using the produced curable adhesive sheet, the peel strength (R1) and (R2) were measured by the method described above. The results are shown in Table 2.
Also, the dielectric loss tangent of the cured product obtained by curing the curable adhesive layer and the releasability of the first release film were evaluated based on the following evaluation methods. These results are also shown in Table 2.

[Dielectric loss tangent of cured product]
A plurality of prepared curable adhesive sheets are prepared, a plurality of curable adhesive layers are superimposed to form a curable adhesive layer having a thickness of about 1 mm, and a second release film/a curable adhesive having a thickness of about 1 mm A laminate was obtained by laminating the agent layer/first release film in this order.
Then, this laminate is heated at 160° C. for 1 hour to cure the curable adhesive layer to obtain a cured product, and the cured product obtained by removing the first release film and the second release film is measured. was used as a sample.
The dielectric loss tangent of the cured product was measured at 23° C. and 1 GHz using an RF impedance material analyzer (manufactured by Keysight Technologies, product name “E4991A”) for the obtained measurement sample. In addition, in this specification, 1 GHz is adopted as an example of a high frequency region.

[Evaluation of releasability of the first release film]
In a state in which the curable adhesive layer of the prepared curable adhesive sheet is sandwiched between the first release film and the second release film, regarding the ease of peeling when trying to peel off only the first release film, Based on the case of the curable adhesive sheet of Comparative Example 1, evaluation was made on a scale of 5 (maximum value) to 1 (minimum value). The criteria for ease of peeling for each standard are as follows.
· "5": Compared with Comparative Example 1, the ease of peeling was felt very much, which was a dramatic difference.
· "4": compared with Comparative Example 1, the ease of peeling was felt sufficiently, and the difference was clear.
· “3”: Compared with Comparative Example 1, it is felt that peeling is easy.
· “2”: Compared with Comparative Example 1, it is felt that peeling is a little easier.
· “1”: The ease of peeling was about the same as in Comparative Example 1 or worse than in Comparative Example 1.

As can be seen from Table 2, the curable adhesive sheets produced in Examples 1 to 4 are easier to peel off of the first release film than Comparative Example 1, and are superior in handleability. In addition, since the curable adhesive sheets prepared in Examples 1 to 4 use a non-silicone release agent, the silicone component does not migrate to the adherend. can be suppressed.

1 curable adhesive sheet 10

curable adhesive layer

10a, 10b surface 21 first release film 211 release layer 212 resin film 22 second release film 221 release layer 222 resin film

Claims

Curing having a curable adhesive layer capable of forming a cured product having a dielectric loss tangent of 0.01 or less at 23° C. and 1 GHz, and a first release film and a second release film sandwiching both sides of the curable adhesive layer an adhesive sheet,
The first release film has a colored resin film (i) and a release agent layer laminated on one surface of the colored resin film (i) and in contact with the surface of the curable adhesive layer,
A second release film is laminated on one surface of the resin film (ii) visually distinguishable from the colored resin film (i) and on one surface of the resin film (ii), and is in contact with the surface of the curable adhesive layer. and a release agent layer,
A curable adhesive sheet that satisfies the following requirement (Ia).
Requirement (Ia): The thickness ratio [(T2)/(T1)] between the thickness (T2) of the second release film and the thickness (T1) of the first release film is 1.05 or more.
The curable adhesive sheet according to claim 1, further satisfying the following requirement (Ib).
Requirement (Ib): The thickness ratio [(T2)/(T1)] of the thickness (T2) of the second release film and the thickness (T1) of the first release film is 10.0 or less.
3. The curable adhesive sheet according to claim 1 or 2, further satisfying the following requirement (IIa).
Requirement (IIa): The thickness difference [(T2) - (T1)] between the thickness (T2) of the second release film and the thickness (T1) of the first release film is 5.0 µm or more.
4. The curable adhesive sheet according to any one of claims 1 to 3, further satisfying the following requirement (IIb).
Requirement (IIb): The thickness difference [(T2) - (T1)] between the thickness (T2) of the second release film and the thickness (T1) of the first release film is 165.0 µm or less.
The curable adhesive sheet according to any one of claims 1 to 4, further satisfying the following requirement (III).
Requirement (III): The peel force (R1) when peeling the first release film from the curable adhesive layer at a peel angle of 180 ° and a peel speed of 300 mm / min, and the second release film at a peel angle of 180 °, The ratio [(R1)/(R2)] to the peel force (R2) when peeled from the curable adhesive layer at a peel speed of 300 mm/min is 0.97 or less.
The curable adhesive sheet according to any one of claims 1 to 5, further satisfying the following requirement (IV).
Requirement (IV): The peel force (R2) when peeling the second release film from the curable adhesive layer at a peel angle of 180 ° and a peel speed of 300 mm / min is It is greater than the peel force (R1) when peeling from the curable adhesive layer at a peel speed of 300 mm/min, and is 600 mN/50 mm or less.
The curable adhesive sheet according to any one of claims 1 to 6, wherein the resin film (ii) is a transparent resin film.
The curable adhesive sheet according to any one of claims 1 to 7, wherein the curable adhesive layer is a layer formed from a curable adhesive composition containing a polyphenylene ether resin.
When the curable adhesive layer exposed by peeling the first release film is attached to the adherend, the curable adhesive layer and the adherend are detected from the second release film side by optical inspection means. 9. The curable adhesive sheet according to any one of claims 1 to 8, wherein the presence or absence of foreign matter at the interface with the body can be confirmed.
A method for producing a cured product using the curable adhesive sheet according to any one of claims 1 to 9, comprising the following steps (1) to (3).
Step (1): A step of peeling off the first release film and attaching the exposed curable adhesive layer to an adherend.
Step (2): A step of confirming that no foreign matter exists at the interface between the curable adhesive layer and the adherend by optical inspection means from the second release film side.
Step (3): After step (2), the step of curing the curable adhesive layer to obtain a cured product.