TWI752222B - Film for sealing, sealing structure, and manufacturing method of sealing structure - Google Patents

Abstract

The present invention is a sealing film (2), which is composed of a resin composition containing a thermosetting resin and an inorganic filler, and the thermosetting resin has a structural unit represented by the following formula (1):

In formula (1), X ¹ represents a reactive functional group, and R ¹ represents a hydrocarbon group having 2 to 25 carbon atoms.

Description

Film for sealing, sealing structure, and manufacturing method of sealing structure

The present invention relates to a film for sealing, a sealing structure, and a method for producing the sealing structure.

In recent years, with the development of electronic apparatuses such as smartphones and the like, which are produced on the premise of being portable, semiconductor devices are being reduced in size and thickness. Similarly, the demand for miniaturization and thinning of electronic component devices used therein is increasing. Therefore, various technologies for encapsulating electronic components having movable parts such as surface acoustic wave (SAW) elements are being studied. A SAW element is an electronic component in which regular comb-shaped electrodes are formed on a piezoelectric film or a piezoelectric substrate, and is an electronic component capable of extracting electrical signals in a specific frequency band using surface acoustic waves.

When encapsulating such an electronic component having a movable portion, it is necessary to provide a space for securing the movability of the movable portion. For example, in a SAW element, if another substance adheres to the surface on which the comb-shaped electrodes are formed, desired frequency characteristics cannot be obtained, and therefore it becomes necessary to form a hollow structure.

Conventionally, in order to form a hollow structure, a sealing method in which a rib or the like is formed on a piezoelectric substrate, and then a lid is closed (for example, Patent Document 1) has been carried out. However, in this method, since the number of steps increases and the height of the sealing portion is high, there is a problem that it is difficult to reduce the thickness of the electronic component device.

Therefore, there has been proposed a method of preparing a hollow structure in which the wafer on which the comb-shaped electrodes are formed is inverted via bumps, and performing wafer sealing in a state in which a hollow region is provided between the substrate and the wafer. A wafer is mounted on a substrate (for example, Patent Documents 2 and 3). [Prior Art Literature] (Patent Literature)

Patent Document 1: Japanese Patent Laid-Open No. 2002-16466 Patent Document 2: Japanese Patent No. 4989402 Patent Document 3: Japanese Patent Laid-Open No. 2016-175976

[Problem to be Solved by the Invention] When the body to be sealed is sealed in a state where a hollow region is provided between the substrate and the body to be sealed, it is difficult to ensure excellent embedding properties for the body to be sealed, and it is difficult to sufficiently suppress the sealing material (The resin composition constituting the sealing film) flows into the hollow region. For example, in the techniques of Patent Documents 2 and 3, when an attempt is made to ensure sufficient embedding properties, the sealing material may enter the hollow region between the base material and the body to be sealed.

Accordingly, an object of the present invention is to provide a film for sealing, which is excellent in embedding property for a body to be sealed, a sealing structure using the film for sealing, and a method for producing the same, and The flow of the sealing material into the hollow region between the substrate and the body to be sealed can be sufficiently suppressed. [Technical means to solve the problem]

The present inventors first considered adjusting the melt viscosity of the resin composition constituting the sealing film to a desired range, and studied adding an elastomer component to the resin composition, adjusting the blending amount of the inorganic filler, and the like. However, it is difficult to solve the above-mentioned problems only by adjusting the melt viscosity to a desired range by these methods. The present inventors focused on thermosetting resins and conducted further studies, and as a result found that by introducing a specific branched group into the main skeleton of the specific thermosetting resin, it becomes easy to control the fluidity of the sealing film, and it is possible to ensure the The present invention is accomplished by achieving excellent embeddability of the body to be sealed and sufficiently suppressing the sealing material (resin composition constituting the film for sealing) from flowing into the hollow region between the substrate and the body to be sealed.

式(1)中，X¹ 表示反應性官能基，R¹ 表示碳數2～25的烴基。That is, one aspect of the present invention relates to a sealing film comprising a resin composition containing a thermosetting resin and an inorganic filler, the thermosetting resin having a structural unit represented by the following formula (1) :

In formula (1), X ¹ represents a reactive functional group, and R ¹ represents a hydrocarbon group having 2 to 25 carbon atoms.

According to the above-described film for sealing, it is possible to sufficiently suppress the flow of the sealing material into the hollow region between the substrate and the body to be sealed while ensuring excellent embedding properties with respect to the body to be sealed. That is, according to the above-mentioned film for sealing, it is possible to have both embedding properties and hollow non-filling properties. Furthermore, according to the said film for sealing, the glass transition temperature (Tg) after hardening becomes sufficient easily, and it becomes easy to improve the reliability (thermal reliability) of a sealing structure.

式(2)中，X² 表示反應性官能基，R² 表示氫原子或苯基。The above thermosetting resin may further have a structural unit represented by the following formula (2). In this case, it is possible to maintain the non-filling properties of the hollow, and further improve the embedding properties with respect to the body to be sealed.

In formula (2), X ² represents a reactive functional group, and R ² represents a hydrogen atom or a phenyl group.

The above-mentioned X ¹ may be a hydroxyl group. In this case, heat resistance and flame retardancy are excellent. Moreover, such a thermosetting resin can be produced inexpensively.

The above-mentioned resin composition may further contain an epoxy resin. In this case, the mechanical strength is excellent, and the shrinkage during hardening is less, so that the dimensional stability is excellent. In addition, it is excellent in heat resistance, water resistance, and chemical resistance, and is excellent in electrical insulation.

Content of the structural unit represented by the said formula (1) in the said thermosetting resin may be 20 mol% or more based on the total amount of the structural unit which comprises the said thermosetting resin. In this case, the embedding property and the hollow non-filling property can be achieved at a higher level.

The weight average molecular weight of the said thermosetting resin may be 500 or more. In this case, the embedding property and the hollow non-filling property can be achieved at a higher level.

The film thickness of the said sealing film may be 20-250 micrometers.

The above-mentioned film for sealing can be suitably used for the purpose of sealing a body to be sealed, which is provided on a substrate with a bump therebetween.

One aspect of the present invention relates to a method for producing a sealing structure, which prepares a hollow structure including a substrate and a to-be-sealed body provided on the substrate with bumps interposed therebetween, wherein the substrate and the above-mentioned A hollow area is provided between the bodies to be sealed; and the body to be sealed is sealed by the film for sealing of the present invention. According to this method, it is possible to obtain a sealing structure in which the body to be sealed is sufficiently embedded and the hollow region is sufficiently secured.

In the above-described manufacturing method, the body to be sealed may be a surface acoustic wave (SAW) element having electrodes on the side of the hollow region. In the above-described manufacturing method, the SAW element can be sufficiently embedded, and the adhesion of the sealing material to the surface having the electrodes of the SAW element can be sufficiently suppressed. Therefore, according to the above-described manufacturing method, the reliability of the SAW element can be improved. Moreover, for the same reason, the above-mentioned manufacturing method can improve the yield when manufacturing the sealing structure (hollow sealing structure) provided with such a to-be-sealed body.

One aspect of the present invention relates to a sealing structure including: a substrate; a body to be sealed provided on the substrate with bumps interposed therebetween; The body to be sealed is sealed; and a hollow region is provided between the substrate and the body to be sealed. In this sealing structure, the to-be-sealed body is sufficiently embedded, and the hollow region is sufficiently secured.

In the above-described sealing structure, the body to be sealed may be a SAW element having electrodes on the side of the hollow region. In this sealing structure, the SAW element is sufficiently embedded, and the adhesion of the sealing material to the surface having the electrodes of the SAW element is sufficiently suppressed. Therefore, the reliability of the SAW element is excellent. [Effect of invention]

ADVANTAGE OF THE INVENTION According to the present invention, it is possible to provide a film for sealing, which is excellent in embedding property for a to-be-sealed body, and a sealing structure using the same, and a method for producing the sealing structure. The sealing material is suppressed from flowing into the hollow region between the substrate and the body to be sealed.

In the numerical range represented using "-" in this specification, the numerical value described before and after "-" is included as a minimum value and a maximum value, respectively. In the numerical range described in steps in this specification, the upper limit or the lower limit of the numerical range in one stage can be replaced with the upper limit or the lower limit of the numerical range in another stage. In the numerical range described in this specification, the upper limit or the lower limit of this numerical range can be replaced with the numerical value shown in an Example. "A or B" means that any one of A and B may be included, or both of them may be included. The materials exemplified in this specification may be used alone or in combination of two or more, unless otherwise specified. In this specification, when there are plural substances in the composition to correspond to each component, unless otherwise specified, the content of each component in the composition means the total amount of the plural substances present in the composition.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

式(1)中，X¹ 表示反應性官能基，R¹ 表示碳數2～25的烴基。<Film for sealing> The film for sealing according to the present embodiment is a film-like resin composition containing a thermosetting component and an inorganic filler. The sealing film of the present embodiment contains, as a thermosetting component, a thermosetting resin having a structural unit represented by the following formula (1).

In formula (1), X ¹ represents a reactive functional group, and R ¹ represents a hydrocarbon group having 2 to 25 carbon atoms.

The sealing film of the present embodiment is suitable for use with a hollow structure including a substrate, a body to be sealed (for example, an electronic component such as a SAW element) provided on the substrate, and a body provided on the substrate and the body to be sealed the hollow area in between. According to the sealing film of the present embodiment, it is possible to have both the embedding property and the hollow non-filling property with respect to the to-be-sealed body. The reason why such an effect can be obtained is unknown, but the present inventors speculate as follows. That is, in the sealing film of the present embodiment, R ¹ in the structural unit represented by the above formula (1) becomes a steric hindrance, and the flow of the thermosetting resin in the sealing film is suppressed, thereby suppressing the The resin composition flows into the hollow region. On the other hand, R ^{1 has} an appropriate size, and the steric hindrance at the time of sealing is relieved by the shear stress, so the embedding property with respect to the body to be sealed is not hindered. From such a reason, according to the sealing film of this embodiment, the said effect can be acquired.

However, it is also possible to prevent the sealing material (especially thermosetting resin) from flowing into the hollow region by adding an excessive amount of elastomer to the sealing film, but this method not only reduces the embedding property, but also reduces the encapsulation property after curing. When Tg falls, it may become difficult to ensure the reliability (thermal reliability) of the sealing structure. On the other hand, the film for sealing according to the present embodiment does not need to use an excessive amount of the elastomer, and has the structural unit represented by the above formula (1), so that Tg after curing can be sufficiently secured.

(Thermosetting component) As a thermosetting component, a thermosetting resin, a hardening agent, a hardening accelerator, etc. are mentioned. The thermosetting component may contain a thermosetting resin without containing a curing agent and/or a curing accelerator. In addition, the thermosetting component may contain a thermosetting resin having at least a structural unit represented by the above formula (1) (hereinafter, also referred to as "first thermosetting resin"), and may further contain a first thermosetting resin Thermosetting resin other than resin (hereinafter, also referred to as "second thermosetting resin")

[First Thermosetting Resin] The first thermosetting resin has at least a structural unit represented by the above formula (1).

The reactive functional group represented by X ^{1 should} just be a functional group which can react with another reactive functional group by heat. In the present embodiment, the film for sealing is cured by forming a three-dimensionally crosslinked structure, for example, by reacting the reactive functional group of the first thermosetting resin with another reactive functional group by heat. As a reactive functional group, a hydroxyl group, an epoxy group, a carboxyl group, an isocyanato group, etc. are mentioned. Among these functional groups, a hydroxyl group (phenolic hydroxyl group) is preferable from the viewpoint of being able to be produced inexpensively and from the viewpoint of being excellent in heat resistance and flame retardancy. In other words, the first thermosetting resin preferably contains a phenol resin. Furthermore, the other reactive functional group that can react with the reactive functional group may be the reactive functional group possessed by the first thermosetting resin or the reactive functional group possessed by the second thermosetting resin, It may also be a reactive functional group possessed by the hardener.

The hydrocarbon group represented by R ¹ may be linear or branched. In addition, the hydrocarbon group may be either saturated or unsaturated. When the hydrocarbon group is an unsaturated hydrocarbon group, the unsaturated hydrocarbon group may have two or more unsaturated bonds.

The number of carbon atoms in the hydrocarbon group is preferably 4 or more, more preferably 8 or more, still more preferably 10 or more, and particularly preferably 15 or more, from the viewpoint of making the hollow non-filling property more favorable. In particular, when the carbon number of the hydrocarbon group is 15 or more, the elastic modulus can be reduced, and the cracking property and the warp property can be improved. The number of carbon atoms in the hydrocarbon group may be 22 or less, 20 or less, or 18 or less, from the viewpoint of better embedding properties. The above upper limit value and lower limit value can be arbitrarily combined. Therefore, the carbon number of the hydrocarbon group may be, for example, 4-22, 8-20, 10-18, or 15-18. In addition, in the same description below, the upper limit value and the lower limit value described individually can also be combined arbitrarily.

In the present embodiment, the longer the main chain of the hydrocarbon group is, the better the hollow non-filling property is, and the easier the Tg after hardening is sufficient. From such a viewpoint, when the hydrocarbon group is branched, the number of carbon atoms in the main chain of the branched hydrocarbon group may be 2 or more, 4 or more, or 6 or more. The number of carbon atoms in the main chain of the branched hydrocarbon group may be 22 or less, 20 or less, or 18 or less, from the viewpoint of better embedding properties.

Examples of linear hydrocarbon groups include -(CH ₂ ) ₁₄ CH ₃ , -(CH ₂ ) ₇ CH=CH(CH ₂ ) ₅ CH ₃ , -(CH ₂ ) ₇ CH=CHCH ₂ CH=CH (CH ₂ ) ₂ CH ₃ , -(CH ₂ ) ₇ CH=CHCH ₂ CH=CHCH=CHCH ₃ , -(CH ₂ ) ₇ CH=CHCH ₂ CH=CHCH ₂ CH=CH _{2 ,} etc.

A branched hydrocarbon group, for example, _{include: -C (CH 3) 2 CH} 3, -C (CH 3) 2 CH 2 C (CH 3) 2 CH 3 and the like.

^{The position of R 1} in the above formula (1) may be any of the ortho position, the meta position or the para position with respect to -X ^{1 . The position of R 1} is preferably the para position with respect to -X ¹ from the viewpoint that steric hindrance is unlikely to occur and the reactivity is excellent.

式(1a)中，X¹ 與上述式(1)中的X¹ 相同，R¹ 與上述式(1)中的R¹ 相同。The positions of the bonds (-* and -CH ₂ -*) can be any of ortho, meta or para positions relative to -X ^{1 .} From the viewpoint of widening the range of ^{R 1} , the bonding position is preferably an ortho ^{position with respect to -X 1 .} For example, the structural unit represented by the formula (1) may contain the structural unit represented by the following formula (1a).

In formula (1a), X ¹ is the same as ^{X 1 in the} above formula (1), and R ^{1 is the} same as ^{R 1 in the above formula (1).}

The first thermosetting resin may be constituted only by the structural unit represented by the above formula (1). In this case, a plurality of structural units represented by the above formula (1) may be used. When there are plural structural units represented by the above formula (1), each of the plural X ^1s may be the same or different, and each of the plural R ^1s may be the same or different. The first thermosetting resin may be, for example, a random copolymer composed of a plurality of different structural units, or a block copolymer.

式(1A)中，X¹ 與上述式(1)中的X¹ 相同，R^1A 表示碳數6以上的烴基。

式(1B)中，X¹ 與上述式(1)中的X¹ 相同，R^1B 表示碳數5以下的烴基。When there are plural structural units represented by the above formula (1), the first thermosetting resin preferably contains the following structural units: ^{structural unit (1A) wherein R 1} is a hydrocarbon group having 6 or more carbon atoms, and R ¹ is a structural unit (1B) of a hydrocarbon group having 5 or less carbon atoms.

In the formula (1A), X ¹ same as (1) in the above formulas X ^1, R ^1A represents a hydrocarbon group having 6 or more carbon atoms.

In the formula (1B), X ¹ same as (1) in the above formulas X ^1, R ^1B represents a hydrocarbon group having 5 or less carbon atoms.

Among the structural units represented by the above-mentioned formula (1) in the first thermosetting resin, the content of the structural unit (1A) constitutes the structure of the thermosetting resin from the viewpoint that the hollow non-filling property becomes more favorable. The total amount of cells may be 20 mol % or more, 30 mol % or more, or 40 mol % or more based on the basis. From the viewpoint of better embedding properties, the content of the structural unit (1A) may be 100 mol % or less, or 90 mol % based on the total amount of the structural units constituting the thermosetting resin. ear % or less, or 80 mol % or less. From these viewpoints, the content of the structural unit (1A) may be 20 to 100 mol %, or 30 to 90 mol %, based on the total amount of the structural units constituting the thermosetting resin. It may be 40 to 80 mol%.

In the structural unit represented by the above-mentioned formula (1) in the first thermosetting resin, from the viewpoint of better embedding properties, the content of the structural unit (1B) constitutes the structural unit of the thermosetting resin As a benchmark, the total amount can exceed 0 mol%, can be more than 10 mol%, and can be more than 20 mol%. From the viewpoint of making the hollow non-filling property more favorable, the content of the structural unit (1B) may be 80 mol % or less, or 70 mol %, based on the total amount of the structural units constituting the thermosetting resin. mol% or less, and may also be 60 mol% or less. From these viewpoints, the content of the structural unit (1B) may be more than 0 mol % and 80 mol % or less, or may be 10 to 70 mol % based on the total amount of structural units constituting the thermosetting resin. The molar % can also be 20 to 60 mol %.

The molar ratio of the structural unit (1A) to the structural unit (1B) may be 0.5 or more from the viewpoint of being able to have both the embedding property and the hollow non-filling property for the sealed body at a higher level, and , can be below 3.0. Therefore, the molar ratio of the structural unit (1A) to the structural unit (1B) may be, for example, 0.5 to 3.0.

式(2)中，X² 表示反應性官能基，R² 表示氫原子或苯基。當以式(2)表示的結構單元為複數個時，複數個X² 各自可以相同亦可以不同，複數個R² 各自可以相同亦可以不同。The first thermosetting resin may further have other structural units than the structural unit represented by the above formula (1). As another structural unit, the structural unit represented by following formula (2) is mentioned, for example.

In formula (2), X ² represents a reactive functional group, and R ² represents a hydrogen atom or a phenyl group. When there are plural structural units represented by formula (2), each of plural X ² may be the same or different, and each plural R ² may be the same or different.

Examples of the reactive functional group in X ² represented by X ¹ include the same examples of the reactive functional group, and preferred examples of the reactive functional groups are also the same.

^{The position of R 2} in the above formula (2) may be any of the ortho position, the meta position or the para position with respect to -X ^{2 . The position of R 2} is preferably the para position with respect to -X ² from the viewpoint of hardly causing steric hindrance and having excellent reactivity.

式(2b)中，X² 與上述式(2)中的X² 相同，R² 與上述式(2)中的R² 相同。The positions of the bonds (-* and -CH ₂ -*), relative to -X ² , may be any of the ortho, meta or para positions. From the viewpoint of reducing the volume of the thermosetting resin and improving the reactivity, the bonding position is preferably an ortho ^{position with respect to -X 2 .} For example, the structural unit represented by the formula (2) may contain the structural unit represented by the following formula (2b).

In formula (2b), X ² is the same as ^{X 2 in the} above formula (2), and R ^{2 is the} same as ^{R 2 in the above formula (2).}

The content of the structural unit represented by the above-mentioned (1) in the first thermosetting resin is based on the total amount of the structural units constituting the thermosetting resin, from the viewpoint that the hollow non-filling property becomes more favorable, It may be 20 mol% or more, 30 mol% or more, or 40 mol% or more. From the viewpoint of better embedding properties, the content of the structural unit represented by the above (1) in the first thermosetting resin may be based on the total amount of the structural units constituting the thermosetting resin. It may be 100 mol % or less, 90 mol % or less, or 80 mol % or less. From these viewpoints, the content of the structural unit represented by the above (1) in the first thermosetting resin may be 20 to 100 mol % based on the total amount of the structural units constituting the thermosetting resin. , can also be 30 to 90 mol%, or 40 to 80 mol%.

From the viewpoint of better embedding properties, the content of the structural unit represented by the above (2) in the first thermosetting resin may be based on the total amount of the structural units constituting the thermosetting resin. If it exceeds 0 mol%, it may be 10 mol% or more, and may be 20 mol% or more. The content of the structural unit represented by the above-mentioned (2) in the first thermosetting resin is based on the total amount of the structural units constituting the thermosetting resin, from the viewpoint that the hollow non-filling property becomes more favorable, It may be 80 mol % or less, 70 mol % or less, or 60 mol % or less. From these viewpoints, the content of the structural unit represented by the above (2) in the first thermosetting resin may be more than 0 mol % based on the total amount of the structural units constituting the thermosetting resin. 80 mol% or less may be 10-70 mol%, or 20-60 mol%.

The structural unit represented by the above-mentioned (1) in the first thermosetting resin is relative to the above-mentioned (2) from the viewpoint of being able to have both the embedding property and the hollow non-filling property for the sealed body at a higher level. The molar ratio of the structural unit represented by ) may be 0.5 or more, and may be 3.0 or less. Therefore, the molar ratio of the structural unit represented by the above (1) to the structural unit represented by the above (2) may be, for example, 0.5 to 3.0.

The weight average molecular weight of the first thermosetting resin may be 500 to 1,000,000, or 500 to 500,000, from the viewpoint of being able to have both the embedding property and the hollow non-filling property for the sealed body at a higher level. , or 500 to 300,000. In addition, the weight average molecular weight is a polystyrene conversion value obtained by gel permeation chromatography (GPC) and using the calibration curve based on standard polystyrene.

The reactive functional group equivalent of the first thermosetting resin may be 100 g/eq. or more, 110 g/eq. or more, or 120 g/ eq. or more or 130 g/eq. or more, and from the same viewpoint, 250 g/eq. or less, 240 g/eq. or less, 210 g/eq. or less, or 200 g/eq. or less. Therefore, the reactive functional group equivalent of the first thermosetting resin may be, for example, 100 to 250 g/eq., 110 to 240 g/eq., 120 to 210 g/eq., or 130 to 130 g/eq. 200g/eq.. In addition, "reactive functional group equivalent" means the mass (g/eq.) of thermosetting resin per 1 equivalent (1 eq.) of reactive functional groups which thermosetting resin has. For example, when the reactive functional group is an epoxy group, the reactive functional group is measured by: after dissolving the thermosetting resin in chloroform, acetic acid and tetraethylammonium bromide are added to the obtained solution acetic acid solution, and then use perchloric acid acetic acid standard solution for potentiometric titration, and detect the end point after all the epoxy groups react. In addition, when the reactive functional group is a hydroxyl group, it is measured by adding an acetylation reagent to a thermosetting resin, heating it in a glycerin bath, and leaving it to cool, and then adding phenolphthalein as an indicator. , and titrated with potassium hydroxide ethanol solution.

The first thermosetting resin may be in a liquid state at 25° C. from the viewpoint of easily suppressing the occurrence of cracks and cracks on the surface of the film. In addition, "liquid state at 25 degreeC" means that the viscosity at 25 degreeC measured by an E-type viscometer is 400 Pa･s or less.

式(3)中，X¹ 與上述式(1)中的X¹ 相同，R¹ 與上述式(1)中的R¹ 相同。R¹ 的位置，相對於-X¹ ，可以是鄰位、間位或對位中的任一個。

式(4)中，X² 與上述式(2)中的X² 相同，R² 與上述式(2)中的R² 相同。R² 的位置，相對於-X² ，可以是鄰位、間位或對位中的任一個。The resin having the structural unit represented by the above formula (1) can be obtained, for example, by polymerizing the compound represented by the following formula (3) by a conventionally known method. In addition, the resin having the structural unit represented by the above formula (1) and the structural unit represented by the above formula (2) can be obtained, for example, by the following method: by a conventionally known method, the following formula (3) The compound represented is copolymerized with the compound represented by the following formula (4).

In formula (3), X ¹ is the same as ^{X 1 in the} above formula (1), and R ^{1 is the} same as ^{R 1 in the above formula (1).} The position of R ¹ with respect to -X ¹ may be any of ortho, meta or para.

In formula (4), X ² is the same as ^{X 2 in the} above formula (2), and R ^{2 is the} same as ^{R 2 in the above formula (2).} The position of R ² with respect to -X ² may be any of ortho, meta or para.

式(3a)中，R¹ 與上述式(1)中的R¹ 相同。R¹ 的位置，相對於-OH，可以是鄰位、間位或對位中的任一個。

式(4a)中，R² 與上述式(2)中的R² 相同。R² 的位置，相對於-OH，可以是鄰位、間位或對位中的任一個。For example, when X ¹ is a hydroxyl group, the first thermosetting resin can be obtained by combining a substituent-containing phenol represented by the following formula (3a) with formaldehyde, and in some cases with the following formula (4a) ) to react with a substituent-containing phenol represented by . In this embodiment, each structural unit which the 1st thermosetting resin has can be adjusted by adjusting the usage-amount of the substituent-containing phenol represented by formula (3a) and the substituent-containing phenol represented by formula (4a), etc. content.

In the formula (3a), R ¹ the same as (1) R in the above formula ^1. The position of R ¹ can be any of the ortho, meta or para positions relative to -OH.

In the formula (4a), R ² the same (2) R in the above formula ^2. The position of R ² can be any of the ortho, meta or para positions relative to -OH.

Further, for example, when X ¹ is an epoxy group, the first thermosetting resin can be obtained by mixing the substituent-containing phenol represented by the above formula (3a) with epichlorohydrin The reaction was carried out in 30% NaOH solution. In this embodiment, each structural unit which the 1st thermosetting resin has can be adjusted by adjusting the usage-amount of the substituent-containing phenol represented by formula (3a) and the substituent-containing phenol represented by formula (4a), etc. content.

The content of the first thermosetting resin may be 1 mass % or more, 3 mass % or more, based on the total mass of the sealing film, from the viewpoint of making the hollow non-filling property more favorable. It may be 5 mass % or more. From the viewpoint of better embedding properties, the content of the first thermosetting resin may be 50 mass % or less, or 30 mass % or less, based on the total mass of the sealing film. It is 10 mass % or less. Therefore, the content of the first thermosetting resin may be, for example, 1 to 50% by mass, 3 to 30% by mass, or 5 to 10% by mass.

[Second Thermosetting Resin] Examples of the second thermosetting resin include epoxy resin, phenol resin, phenoxy resin, cyanate resin, thermosetting polyimide, melamine resin, urea resin, Saturated polyester, alkyd resin, polyurethane, etc. The reactive functional group which the second thermosetting resin has is preferably a functional group which can react with the reactive functional group which the first thermosetting resin has by heat. For example, when the reactive functional group which the first thermosetting resin has is a hydroxyl group (phenolic hydroxyl group), the reactive functional group which the second thermosetting resin has is preferably an epoxy group. In other words, when the first thermosetting resin is a phenol resin, the second thermosetting resin is preferably an epoxy resin. In this case, the mechanical strength is excellent, and the shrinkage during hardening is less, so that the dimensional stability is excellent. In addition, it is excellent in heat resistance, water resistance, and chemical resistance, and is excellent in electrical insulation. The reactive functional group which the second thermosetting resin has may be the same as the reactive functional group which the first thermosetting resin has. For example, when the reactive functional group which the first thermosetting resin has is a hydroxyl group (phenolic hydroxyl group), the reactive functional group which the second thermosetting resin has may be a hydroxyl group (phenolic hydroxyl group). In this case, a hardening agent can be used as a thermosetting component.

As an epoxy resin, if it is resin which has two or more epoxy groups in one molecule, it can be used without a restriction|limiting in particular. Examples of epoxy resins include bisphenol A type epoxy resin, bisphenol AP type epoxy resin, bisphenol AF type epoxy resin, bisphenol B type epoxy resin, bisphenol BP type epoxy resin, bisphenol BP type epoxy resin, Phenol C type epoxy resin, bisphenol E type epoxy resin, bisphenol F type epoxy resin, bisphenol G type epoxy resin, bisphenol M type epoxy resin, bisphenol S type epoxy resin (hexanediol Bisphenol S diglycidyl ether, etc.), bisphenol P type epoxy resin, bisphenol PH type epoxy resin, bisphenol TMC type epoxy resin, bisphenol Z type epoxy resin, phenol novolac type epoxy resin Resin, biphenyl type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, bixylenol type epoxy resin (bixylenol diglycidyl ether, etc.), hydrogenated bisphenol A type epoxy resins (hydrogenated bisphenol A glycidyl ether, etc.); and, dibasic acid-modified diglycidyl ether type epoxy resins of these resins; aliphatic epoxy resins, etc. As for the epoxy resin, one type may be used alone, or two or more types may be used in combination.

The epoxy resin may be a liquid epoxy resin (liquid epoxy resin) at 25° C. from the viewpoint of easily suppressing the occurrence of cracks and cracks on the surface of the film. Examples of liquid epoxy resins include bisphenol A type glycidyl ether, bisphenol AD type glycidyl ether, bisphenol S type glycidyl ether, bisphenol F type glycidyl ether, Hydrogenated bisphenol A glycidyl ether, ethylene oxide adduct bisphenol A glycidyl ether, propylene oxide adduct bisphenol A glycidyl ether, glycidyl ether of naphthalene resin, 3-functional or 4-functional glycidylamine, etc.

Examples of commercially available epoxy resins include trade name "jER825" (bisphenol A epoxy resin, epoxy group equivalent: 175 g/eq.) manufactured by Mitsubishi Chemical Corporation, manufactured by Mitsubishi Chemical Corporation, for example. trade name "jER806" (bisphenol F type epoxy resin, epoxy equivalent: 160 g/eq.), trade name "HP-4032D" manufactured by DIC Co., Ltd. (naphthalene type epoxy resin, epoxy equivalent : 141g/eq.), trade name "EXA-4850" manufactured by DIC Co., Ltd., and other soft and tough epoxy resins; trade name "HP-4700" manufactured by DIC Co., Ltd. (tetrafunctional naphthalene type epoxy resin) , trade name "HP-4750" (3-functional naphthalene type epoxy resin), trade name "HP-4710" (tetra-functional naphthalene type epoxy resin), trade name "EPICLON N-770" (phenol novolak type epoxy resin) resin), trade name "EPICLON N-660" (cresol novolak type epoxy resin) and trade name "EPICLONHP-7200H" (dicyclopentadiene type epoxy resin); trade name manufactured by Nippon Kayaku Co., Ltd. "EPPN-502H" (triphenylmethane type epoxy resin) and trade name "NC-3000" (biphenyl alkyl type epoxy resin); trade name "ESN- 355” (naphthalene type epoxy resin); trade name “YX-8800” (anthracene type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd., trade name “ESCN-190-2” manufactured by Sumitomo Chemical Co., Ltd. cresol novolac epoxy resin), etc. These epoxy resins may be used alone or in combination of two or more.

As the phenol resin, a known phenol resin can be used without particular limitation as long as it has two or more phenolic hydroxyl groups in one molecule. Examples of phenol resins include resins obtained by condensing or co-condensing phenols and/or naphthols and aldehydes under an acidic catalyst, biphenyl skeleton type phenol resins, p-xylene modified phenol resins, m-xylene/para-xylene modified phenol resin, melamine modified phenol resin, terpene modified phenol resin, dicyclopentadiene modified phenol resin, cyclopentadiene modified phenol resin, polycyclic aromatic ring modified phenol resin, xylene modified naphthol resin, etc. As phenols, phenol, cresol, xylenol, resorcinol, catechol, bisphenol A, bisphenol F, etc. are mentioned. As naphthols, α-naphthol, β-naphthol, dihydroxynaphthalene, etc. are mentioned. As aldehydes, formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, salicylaldehyde, etc. are mentioned.

Commercially available phenol resins include trade name "PAPS-PN2" (novolak-type phenol resin) manufactured by Asahi Organic Materials Co., Ltd.; trade name "SK Resin HE200C-7" manufactured by Air Water Co., Ltd. (biphenyl alkyl type phenol resin), trade name "HE910-10" (triphenylmethane type phenol resin); trade names "MEH-7000", "DL-92", "Meiwa Chemical Co., Ltd. H-4" and "HF-1M"; trade names "LVR-8210DL", "ELP" series and "NC" series manufactured by Qunrong Chemical Industry Co., Ltd., trade names manufactured by Nippon Steel & Sumitomo Metal Chemical Co., Ltd. "SN-100, SN-300, SN-395, SN-400" (naphthalene-type phenol resin); and the trade name "HP-850N" (novolak-type phenol resin) manufactured by Hitachi Chemical Co., Ltd.

The reactive functional group equivalent of the second thermosetting resin may be 100 g/eq. or more and 120 g from the viewpoint of reducing the curing shrinkage by reducing the cross-linking points between the resins and improving the warpage and cracking properties. /eq. or more or 140g/eq. or more. From the same viewpoint, it may be 500 g/eq. or less, 400 g/eq. or less, or 300 g/eq. or less. Therefore, the reactive functional group equivalent of the second thermosetting resin may be, for example, 100 to 500 g/eq., 120 to 400 g/eq., or 140 to 300 g/eq.

When the second thermosetting resin contains an epoxy resin, from the viewpoint of better embedding properties, the content of the epoxy resin may be 1 mass % or more based on the total mass of the sealing film, 3 mass % or more may be sufficient, and 5 mass % or more may be sufficient. The content of epoxy resin may be 50 mass % or less, 30 mass % or less, or 10 mass % based on the total mass of the sealing film, from the viewpoint of making the hollow non-filling property more favorable. mass % or less. Therefore, the content of the epoxy resin may be, for example, 1 to 50 mass %, 3 to 30 mass % or less, or 5 to 10 mass % based on the total mass of the sealing film.

When the second thermosetting resin contains a liquid epoxy resin, the content of the liquid epoxy resin is preferably based on the total mass of the sealing film from the viewpoint of easily suppressing cracks and cracks on the surface of the film. It is 0.5 mass % or more, more preferably 1 mass % or more, still more preferably 3 mass % or more, particularly preferably 5 mass % or more, very preferably 7 mass % or more, and very preferably 9 mass % or more. The content of the liquid epoxy resin is preferably 20 mass based on the total mass of the sealing film from the viewpoint of easily suppressing an excessive increase in the viscosity of the film and easily suppressing edge fusion. % or less, more preferably 15 mass % or less, still more preferably 13 mass % or less. From these viewpoints, the content of the liquid epoxy resin is preferably 0.5 to 20 mass %, more preferably 1 to 20 mass %, and still more preferably 3 to 20 mass % based on the total mass of the sealing film. The mass % is particularly preferably 5 to 20 mass %, extremely preferably 7 to 15 mass %, and very preferably 9 to 13 mass %.

The content of the liquid epoxy resin is preferably 20% by mass or more, more preferably 30% by mass, based on the total mass of the second thermosetting resin, from the viewpoint of easily suppressing the occurrence of cracks and cracks on the surface of the film. The above, more preferably 50 mass % or more. The content of the liquid epoxy resin is preferably 95% by mass based on the total mass of the second thermosetting resin from the viewpoint of easily suppressing an excessive increase in the viscosity of the film and from the viewpoint of easily suppressing edge fusion. Below, it is more preferable that it is 90 mass % or less, and it is still more preferable that it is 80 mass % or less. From these viewpoints, the content of the liquid epoxy resin is preferably 20 to 95% by mass, more preferably 30 to 90% by mass, and even more preferably 20 to 95% by mass based on the total mass of the second thermosetting resin. 50 to 80 mass %. The content of the liquid epoxy resin may be 100% by mass based on the total mass of the second thermosetting resin.

When the second thermosetting resin contains a phenol resin, from the viewpoint of better embedding properties, the content of the phenol resin may be 1 mass % or more based on the total mass of the sealing film, or may be It is 3 mass % or more, and may be 5 mass % or more. From the viewpoint of making the hollow non-filling property more favorable, the content of the phenol resin may be 50 mass % or less, 30 mass % or less, or 10 mass % based on the total mass of the sealing film. %the following. Therefore, the content of the phenol resin may be, for example, 1 to 50 mass %, 3 to 30 mass %, or 5 to 10 mass % based on the total mass of the sealing film.

In this embodiment, it is preferable that the thermosetting component contains an epoxy resin and a phenol resin, and the second 1 thermosetting resin contains phenol resin and 2nd thermosetting resin contains epoxy resin. At this time, the content of all epoxy resins and the content of phenol resin contained in the resin composition can be based on the ratio of the molar number M2 of epoxy groups to the molar number M1 of phenolic hydroxyl groups in the resin composition to set.

The ratio (M2/M1) of the molar number M2 of the epoxy group in the resin composition to the molar number M1 of the phenolic hydroxyl group may be 0.7 or more, 0.8 or more, or 0.9 or more, and may be 2.0 or less and 1.8 below or below 1.7. Therefore, the ratio (M2/M1) may be, for example, 0.7 to 2.0, 0.8 to 1.8, or 0.9 to 1.7.

[Curing agent] Although it does not specifically limit as a curing agent (except a component which corresponds to a thermosetting resin), A phenol type curing agent, an acid anhydride type curing agent, an active ester type curing agent, a cyanate ester type curing agent, etc. are mentioned. A hardener may be used individually by 1 type, and may use 2 or more types together.

From the viewpoint of excellent curability of the thermosetting resin, the content of the curing agent may be 1 to 20% by mass, 2 to 15% by mass, or 2 to 15% by mass based on the total mass of the sealing film. 3 to 10 mass %.

[Hardening Accelerator] As the curing accelerator, it can be used without particular limitation, and is preferably at least one selected from the group consisting of an amine-based curing accelerator and a phosphorus-based curing accelerator. In particular, the hardening accelerator is preferably an amine-based hardening accelerator, more preferably from the viewpoint of easily obtaining a cured product having excellent thermal conductivity, from the viewpoint of abundant derivatives, and from the viewpoint of being easy to obtain a desired activation temperature. is at least one selected from the group consisting of imidazole compounds, aliphatic amines and alicyclic amines, and more preferably imidazole compounds. As an imidazole compound, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, etc. are mentioned. A hardening accelerator may be used individually by 1 type, and may use 2 or more types together. As a commercial item of a hardening accelerator, "2P4MZ" and "1B2MZ" by Shikoku Chemical Industry Co., Ltd., etc. are mentioned.

The content of the curing accelerator is preferably in the following range based on the total amount of the thermosetting resin. From the viewpoint of easily obtaining a sufficient hardening acceleration effect, the content of the hardening accelerator is preferably 0.01 mass % or more, more preferably 0.1 mass % or more, and further more preferably 0.3 mass % or more. From the viewpoints that curing does not progress easily in the steps of manufacturing the sealing film (such as coating and drying) or during storage of the sealing film, and it is easy to prevent cracking of the sealing film and forming defects due to an increase in melt viscosity, The content of the hardening accelerator is preferably 5% by mass or less, more preferably 3% by mass or less, and still more preferably 1.5% by mass or less. From these viewpoints, the content of the hardening accelerator is preferably 0.01 to 5 mass %, more preferably 0.1 to 3 mass %, and still more preferably 0.3 to 1.5 mass %.

(Inorganic Filler) As the inorganic filler, conventionally known inorganic fillers can be used, and are not particularly limited. Examples of the constituent material of the inorganic filler include silicas (amorphous silica, crystalline silica, fused silica, spherical silica, synthetic silica, hollow silica, etc.) , barium sulfate, barium titanate, talc, clay, mica powder, magnesium carbonate, calcium carbonate, aluminum oxide (alumina), aluminum hydroxide, magnesium oxide, magnesium hydroxide, silicon nitride, aluminum nitride, aluminum borate, nitrogen Boronide, barium titanate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, barium zirconate, calcium zirconate, etc. From the viewpoints that the effect of improving the dispersibility in the resin composition and the effect of suppressing the precipitation in the varnish are easily obtained by surface modification (for example, surface treatment with a silane compound), etc., and the desired cured film is easily obtained Characteristics From the viewpoint of having a small thermal expansion coefficient, it is preferable to include an inorganic filler such as silica. From the viewpoint of obtaining high thermal conductivity, an inorganic filler containing alumina is preferred. The inorganic filler may be used alone or in combination of two or more.

Surface modification of inorganic filler materials is possible. The method of surface modification is not specifically limited. Surface modification using a silane coupling agent is preferable from the viewpoints of easy handling, abundant functional groups, and easy imparting of desired properties.

Examples of the silane coupling agent include alkyl silane, alkoxy silane, vinyl silane, epoxy silane, amino silane, acryl silane, methacryloyl silane, mercapto silane, thioether silane, isopropyl silane Cyanate silane, sulfur silane, styryl silane, alkyl chlorosilane, etc.

Specific examples of the silane coupling agent include methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, methyltriethoxysilane, and methyltriphenoxysilane , ethyltrimethoxysilane, n-propyltrimethoxysilane, diisopropyldimethoxysilane, isobutyltrimethoxysilane, diisobutyldimethoxysilane, isobutyltriethoxy Silane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, cyclohexylmethyldimethoxysilane, n-octyltriethoxysilane, n-decylmethoxysilane, phenyltrimethoxysilane Silane, diphenyldimethoxysilane, triphenylsilanol, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, n-octyldimethylchlorosilane, tetraethoxysilane , 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-(2-aminopropyltrimethoxysilane Ethyl)aminopropylmethyldimethoxysilane, 3-phenylaminopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyl Dimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, bis(3-(triethyl)disulfide oxysilyl)propyl), bis(3-(triethoxysilyl)propyl) tetrasulfide, vinyltriacetoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane , vinyltriisopropoxysilane, allyltrimethoxysilane, diallyldimethylsilane, 3-methylpropoxypropyltrimethoxysilane, 3-methylpropoxysilane Propylmethyldimethoxysilane, 3-Methylpropionyloxypropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3 -Mercaptopropyltriethoxysilane, N-(1,3-dimethylbutylene)-3-aminopropyltriethoxysilane, aminosilane (phenylaminosilane, etc.), etc. A silane coupling agent may be used individually by 1 type, and may use 2 or more types together.

The average particle size of the inorganic filler is preferably 0.01 μm or more, more preferably 0.1 μm or more, still more preferably 0.3 μm or more, from the viewpoint of easily suppressing aggregation of the inorganic filler and easily dispersing the inorganic filler. Preferably, it is 0.5 μm or more. The average particle size of the inorganic filler is preferably 25 μm or less, more preferably 10 μm or less, and even more preferably 25 μm or less, from the viewpoint of easily suppressing precipitation of the inorganic filler in the varnish, thereby facilitating the production of a homogeneous sealing film. 5μm or less. From these viewpoints, the average particle diameter of the inorganic filler is preferably 0.01 to 25 μm, more preferably 0.01 to 10 μm, still more preferably 0.1 to 10 μm, particularly preferably 0.3 to 5 μm, and most preferably 0.5 to 5 μm. The average particle diameter of the inorganic filler may be 10 to 18 μm.

From the viewpoint of excellent fluidity of the resin composition, it is preferable to use a combination of a plurality of inorganic fillers having mutually different average particle diameters. Among the combinations of inorganic fillers, those in which the average particle diameter of the inorganic filler having the largest average particle diameter is 15 to 25 μm are preferred. Preferably, an inorganic filler having an average particle diameter of 15 to 25 μm, an inorganic filler having an average particle diameter of 0.5 to 2.5 μm, and an inorganic filler having an average particle diameter of 0.1 to 1.0 μm are used in combination.

"Average particle size" refers to the particle size at a point corresponding to 50% of the volume when the cumulative frequency distribution curve based on the particle size is obtained by taking the total volume of the particles as 100%, and the particle size can be used The particle size distribution measurement apparatus used the laser diffraction scattering method. The average particle diameter of each inorganic filler after the combination can be confirmed from the average particle diameter of each inorganic filler at the time of mixing, and can be confirmed by measuring the particle size distribution.

As a commercial item of an inorganic filler, "DAW20" by Denka Co., Ltd.; "SC550O-SXE" and "SC2050-KC" by Admatechs Co., Ltd. are mentioned.

From the viewpoint of improving thermal conductivity and from the viewpoint of easily suppressing the increase in warpage of the sealing structure (for example, electronic component devices such as semiconductor devices) due to the difference in thermal expansion coefficient with the body to be sealed, inorganic fillers The content may be 70 mass % or more, 75 mass % or more, 80 mass % or more, or 84 mass % or more based on the total mass of the sealing film. From the viewpoint of easily suppressing the cracking of the sealing film in the drying step when the sealing film is produced, and from the viewpoint of suppressing the decrease in fluidity due to the increase in the melt viscosity of the sealing film, and the ease of fully sealing the to-be-sealed body (electronic parts, etc.) In other words, the content of the inorganic filler may be 93% by mass or less, 91% by mass or less, or 88% by mass or less, based on the total mass of the sealing film. From these viewpoints, the content of the inorganic filler may be 70 to 93% by mass, 75 to 91% by mass, 80 to 91% by mass, or 80 to 91% by mass based on the total mass of the sealing film. 84-91 mass % may be sufficient, and 84-88 mass % may be sufficient. In addition, the said content is content of the inorganic filler excluding the quantity of a surface treatment agent.

(Elastomer) The sealing film of the present embodiment may contain an elastomer (flexibilizer) as needed. From the viewpoint of being excellent in dispersibility and solubility, the elastomer is preferably selected from the group consisting of polybutadiene particles, styrene butadiene particles, acrylic elastomers, polysiloxane powder, silicone oil, and silicone At least one of the group consisting of oligomers. Elastomers may be used alone or in combination of two or more.

When the elastomer is in the form of particles, the average particle diameter of the elastomer is not particularly limited. In Embedded Wafer-Level Ball Grid Array (eWLB) applications, since it is necessary to embed semiconductor elements, when the sealing film is used for eWLB applications, the average particle size of the elastomer , preferably 50 μm or less. From the viewpoint of excellent dispersibility of the elastomer, the average particle diameter of the elastomer is preferably 0.1 μm or more.

As a commercial item of an elastomer, "SG-280 EK23", "SG-70L", "WS-023 EK30" etc. which are acrylic elastomers by Nagase ChemteX Co., Ltd. are mentioned. In addition, among commercially available elastomer components, there are elastomer components dispersed in liquid resins (eg, liquid epoxy resins) in advance, but not the elastomers alone, and can be used without problems. As such a commercial item, "MX-136" and "MX-965" by KANEKA Co., Ltd., etc. are mentioned.

From the viewpoint of making the hollow non-filling property more favorable, the content of the elastomer may be 1 mass % or more, 5 mass % or more, based on the total amount of the thermosetting component and the elastomer. It may be 10 mass % or more. From the viewpoint of better embedding properties, and from the viewpoint of easily obtaining a sufficient Tg after hardening and improving the reliability (thermal reliability) of the sealing structure, the content of the elastomer is based on the thermosetting component and elasticity. The total amount of bodies may be 30 mass % or less, 25 mass % or less, or 20 mass % or less as a reference. From the above viewpoints, the content of the elastomer may be 1 to 30% by mass, 5 to 25% by mass, or 10 to 20% by mass based on the total amount of the thermosetting component and the elastomer. %the following.

(Other components) The sealing film of the present embodiment may further contain other additives. Specific examples of such additives include pigments, dyes, mold release agents, antioxidants, surface tension modifiers, and the like.

Moreover, the film for sealing of this embodiment may contain a solvent (for example, the solvent used when manufacturing the film for sealing). As the solvent, a conventionally known organic solvent may be used. The organic solvent may be a solvent capable of dissolving components other than the inorganic filler, and examples thereof include aliphatic hydrocarbons, aromatic hydrocarbons, terpenes, halogens, esters, ketones, alcohols, Aldehydes, etc. A solvent may be used individually by 1 type, and may use 2 or more types together.

The solvent may be at least one selected from the group consisting of esters, ketones, and alcohols, from the viewpoint of a small environmental load and the ease of dissolving the thermosetting component. Among them, when the solvent is a ketone, it is particularly easy to dissolve the thermosetting component. The solvent may be selected from the group consisting of acetone, methyl ethyl ketone, and methyl isobutyl ketone from the viewpoint of less volatilization at room temperature (25° C.) and easy removal during drying. at least one.

The content of the solvent (organic solvent, etc.) contained in the film for sealing is preferably within the following range based on the total mass of the film for sealing. The content of the solvent may be 0.2 mass % or more from the viewpoint of easily suppressing the occurrence of defects such as cracking of the sealing film due to brittleness, and the case where the minimum melt viscosity is increased and the embedding property is lowered. It may be 0.3 mass % or more, 0.5 mass % or more, 0.6 mass % or more, or 0.7 mass % or more. From the viewpoint of easily suppressing the problems that the adhesiveness of the sealing film becomes too strong and the workability is lowered, and the problems such as foaming caused by the volatilization of the solvent (organic solvent, etc.) during the thermal curing of the sealing film, the content of the solvent , may be 1.5 mass % or less, or 1 mass % or less. From these viewpoints, the content of the solvent may be 0.2 to 1.5 mass %, 0.3 to 1 mass %, 0.5 to 1 mass %, 0.6 to 1 mass %, or 0.7 to 0.7 mass %. 1 mass %.

The thickness of the sealing film may be 20 μm or more, 30 μm or more, 50 μm or more, or 100 μm or more, from the viewpoint of easily suppressing in-plane thickness variation during coating. The thickness of the film for sealing may be 250 μm or less, 200 μm or less, or 150 μm or less, from the viewpoint of easily obtaining constant drying properties in the depth direction during coating. From these viewpoints, the thickness of the film for sealing may be 20 to 250 μm, 30 to 250 μm, 50 to 200 μm, or 100 to 150 μm. Moreover, the thickness of the film for sealing of a plurality of sheets can also be laminated|stacked, and the film for sealing with a thickness exceeding 250 micrometers can also be manufactured.

From the viewpoint of reliability (thermal reliability) of the obtained sealing structure, the glass transition temperature Tg after curing of the film for sealing may be 80 to 180° C., 80 to 165° C., or 80° C. ~150°C. The glass transition temperature Tg after curing of the film for sealing can be adjusted by the type and content of the thermosetting component, the type and content of the elastomer component, and the like. The glass transition temperature Tg can be measured by the method described in the examples.

From the viewpoint of better embedding properties, the minimum value (minimum melt viscosity) of the melt viscosity of the film for sealing at 35 to 200°C may be 100 to 10000 Pa･s or 250 to 8500 Pa･s , or 500 to 7000Pa･s. From the viewpoint of better non-filling properties in the hollow, the maximum value (maximum melt viscosity) of the melt viscosity of the sealing film at 70 to 90°C may be 500 to 25000Pa･s or 4000 to 20000Pa･s s, may be 6000 to 15000Pa･s. The said minimum melt viscosity and the maximum melt viscosity can be calculated|required by carrying out the method described, and measuring the melt viscosity of the film for sealing.

As described above, the sealing film of the present embodiment can be suitably used for sealing the body to be sealed in the hollow structure, but the structure to be sealed does not need to have a hollow structure. The sealing film of the present embodiment can also be used for, for example, sealing of semiconductor devices, embedding of electronic components arranged on printed wiring boards, and the like.

The sealing film of the present embodiment can also be used as, for example, a support-attached sealing film. The supporting body-attached sealing film 10 shown in FIG. 1 includes a supporting body 1 and a sealing film 2 provided on the supporting body 1 .

As the support 1, a polymer film, a metal foil, or the like can be used. Examples of polymer films include: polyolefin films such as polyethylene films and polypropylene films; vinyl films such as polyvinyl chloride films; polyester films such as polyethylene terephthalate films; polycarbonate films; acetate fibers plain film; tetrafluoroethylene film, etc. As metal foil, copper foil, aluminum foil, etc. are mentioned.

The thickness of the support body 1 is not particularly limited, but from the viewpoint of excellent workability and drying properties, it may be 2 to 200 μm. When the thickness of the support body 1 is 2 μm or more, the failure of the support body to be broken during coating, the failure of the support body to bend due to the weight of the varnish, and the like are easily suppressed. When the thickness of the support body 1 is 200 μm or less, in the drying step, when hot air is blown from both the coated surface and the back surface, it is easy to suppress the inconvenience that the drying of the solvent in the varnish is hindered.

In this embodiment, the support body 1 may not be used. Moreover, the protective layer may be arrange|positioned at the opposite side to the support body 1 of the film 2 for sealing, and the purpose of this protective layer is to protect the film for sealing. By forming a protective layer on the film 2 for sealing, workability|operativity can be improved, and when winding, it can avoid the inconvenience that the film for sealing sticks to the back surface of a support body.

As the protective layer, a polymer film, a metal foil, or the like can be used. Examples of polymer films include: polyolefin films such as polyethylene films and polypropylene films; vinyl films such as polyvinyl chloride films; polyester films such as polyethylene terephthalate films; polycarbonate films; acetate fibers plain film; tetrafluoroethylene film, etc. As a metal foil, a copper foil, an aluminum foil, etc. can be illustrated.

<The manufacturing method of the film for sealing> The film for sealing of this embodiment can be specifically manufactured as follows.

First, a varnish (varnish-like resin composition) is prepared by mixing the constituent components (thermosetting resin, curing agent, curing accelerator, inorganic filler, solvent, etc.) of the resin composition of the present embodiment. The mixing method is not particularly limited, and a mill, a mixer, and a stirring blade can be used. The solvent (organic solvent) can be used to prepare a varnish by dissolving and dispersing the material of the sealing film, that is, the constituent components of the resin composition, or can be used to assist in the preparation of a varnish. Most of the solvent can be removed by the drying step after coating.

A film for sealing can be produced by applying the varnish produced in this way on a support (a film-like support or the like), and then heating and drying by blowing hot air or the like. The coating method is not particularly limited, and for example, a notch coater, a bar coater, a kiss coater, a roll coater, and a gravure coater can be used. , die coater and other coating devices.

<The sealing structure and its manufacturing method> The sealing structure of this embodiment is provided with the to-be-sealed body and the sealing part for sealing the to-be-sealed body. The sealing portion is the cured product of the sealing film of the present embodiment, and includes the cured product of the resin composition of the present embodiment. The sealing structure may be a hollow sealing structure having a hollow structure. The hollow sealing structure includes, for example, a substrate, a to-be-sealed body provided on the substrate, a hollow region provided between the substrate and the to-be-sealed body, and a sealing portion for sealing the to-be-sealed body. The sealing structure of the present embodiment may include a plurality of bodies to be sealed. A plurality of to-be-sealed bodies may be of the same type or different from each other.

The sealing structure is, for example, an electronic component device. An electronic component device includes electronic components as a to-be-sealed body. Examples of electronic components include semiconductor elements, semiconductor wafers, integrated circuits, semiconductor devices, filters such as SAW filters, passive components such as sensors, and the like. A semiconductor element obtained by singulating a semiconductor wafer can be used. The electronic component device may be a semiconductor device including a semiconductor element or a semiconductor wafer as an electronic component, a printed wiring board, or the like. When the electronic component device has a hollow structure, that is, when the electronic component device is a hollow sealed structure, the body to be sealed has a movable portion on the surface of the hollow region side (substrate side), for example, through the bumps. arranged on the substrate. As such a to-be-sealed body, electronic components, such as a SAW element (SAW device), such as a SAW filter, are mentioned, for example. When the body to be sealed is a SAW filter, among the surfaces of the piezoelectric substrate, the surface on the side where the electrodes (for example, a pair of comb-shaped electrodes, that is, an interdigital transducer (IDT)) are mounted becomes the movable portion .

Next, the manufacturing method of the hollow sealing structure performed using the film for sealing of this embodiment is demonstrated. Here, the case where the hollow sealing structure is an electronic component device and the body to be sealed is a SAW element will be described.

FIG. 2 is a schematic cross-sectional view for explaining an embodiment of a method of manufacturing a hollow sealing structure, that is, an embodiment of a method of manufacturing an electronic component device, that is, a semiconductor device. In the manufacturing method of the present embodiment, first, as a body to be sealed (object to be embedded), a hollow structure is prepared, and the hollow structure includes a substrate 30 and a plurality of the substrates 30 arranged in parallel on the substrate 30 with the bumps 40 interposed therebetween. In the surface acoustic wave (SAW) element 20, the SAW element 20 side surface of the substrate 30 faces the sealing film 2 side surface of the support-attached sealing film 10 (FIG. 2(a)). Here, the hollow structure 60 has the hollow region 50, and the SAW element 20 has a movable portion on the surface 20a on the side of the hollow region 50 (the side of the substrate 30).

Next, after the SAW element 20 is embedded in the sealing film 2 by pressing (laminating) the sealing film 2 against the SAW element 20 under heating, the sealing film 2 in which the SAW element 20 is embedded is cured. , to obtain a cured product of the sealing film (the sealing portion of the cured product including the resin composition) 2a (Fig. 2(b)). Thereby, the electronic component device 100 can be obtained.

It does not specifically limit as a laminator used for lamination, For example, the laminator of a roll type, a balloon type, etc. is mentioned. From the viewpoint of excellent embeddability, the laminator may be a bladder-type laminator capable of vacuum pressurization.

Lamination is usually carried out below the softening point of the support. The lamination temperature (sealing temperature) is preferably in the vicinity of the minimum melt viscosity of the film for sealing. The lamination temperature is, for example, 60 to 140°C. The pressure at the time of lamination differs depending on the size, density, etc. of the to-be-sealed body to be embedded (eg, electronic components such as semiconductor elements). The pressure at the time of lamination may be, for example, in the range of 0.2 to 1.5 MPa, or in the range of 0.3 to 1.0 MPa. The lamination time is not particularly limited, and may be 20 to 600 seconds, 30 to 300 seconds, or 40 to 120 seconds.

Hardening of the film for sealing can be carried out, for example, in the atmosphere or under an inert gas. The hardening temperature (heating temperature) is not particularly limited, and may be 80 to 280°C, 100 to 240°C, or 120 to 200°C. When the curing temperature is 80° C. or higher, the curing of the sealing film can be sufficiently advanced, and the occurrence of defects can be suppressed. When the hardening temperature is 280° C. or lower, thermal damage to other materials tends to be suppressed. The hardening time (heating time) is not particularly limited, and may be 30 to 600 minutes, 45 to 300 minutes, or 60 to 240 minutes. When the hardening time is within these ranges, the hardening of the sealing film can sufficiently progress, and more favorable production efficiency can be obtained. In addition, as for the hardening conditions, a plurality of conditions may be combined.

In the present embodiment, a plurality of electronic component devices 200 can be obtained by further dividing the electronic component devices 100 into pieces by a cutting machine or the like ( FIG. 2( c )).

The above-described method for producing a hollow sealing structure of the present embodiment can ensure excellent embedding properties for the body to be sealed (eg, the SAW element 20 ), and can sufficiently suppress the sealing material from flowing into the hollow region between the substrate 30 and the body to be sealed 50.

In the present embodiment, after the SAW element 20 is sealed with the sealing film 20 according to the lamination method, the sealing film 2 is thermally cured to obtain a hollow sealing structure (electronic component device), The hollow sealing structure includes the SAW element 20 embedded in the cured product 2a, and the sealing structure can also be obtained by compression molding using a compression molding device, or by using a hydraulic press. Press-forming is carried out to obtain a sealing structure. The temperature (sealing temperature) when the body to be sealed is sealed by compression molding and hydraulic pressing can be the same as the lamination temperature described above.

As mentioned above, although the preferable embodiment of this invention was described, this invention is not necessarily limited to the said embodiment, It can change suitably in the range which does not deviate from the summary. [Example]

Hereinafter, the present invention will be described in further detail using examples, but the present invention is not limited to these examples at all.

The following materials were used in Examples and Comparative Examples.

(Thermosetting resin) A1: Bisphenol F-type epoxy resin (manufactured by Mitsubishi Chemical Corporation, trade name "jER806", epoxy group equivalent: 160 g/eq.) B1: Hydrocarbyl group-containing phenol resin (phenolic hydroxyl equivalent : 140 g/eq., weight-average molecular weight: 120,000) B2: Hydrocarbyl-containing phenol resin (phenolic hydroxyl equivalent: 185 g/eq., weight-average molecular weight: 120,000) B3: Hydrocarbyl-containing phenol resin (phenolic hydroxyl equivalent: 243 g /eq., weight-average molecular weight: 120,000) B4: Hydrocarbyl-containing phenol resin (phenolic hydroxyl equivalent: 205 g/eq., weight-average molecular weight: 120,000) B5: Novolak-type phenol resin (manufactured by Meiwa Chemical Co., Ltd., Brand name "DL-92", phenolic hydroxyl equivalent: 103 g/eq., weight average molecular weight: 50,000)

(hardening accelerator) C1: Imidazole (manufactured by Shikoku Chemical Industry Co., Ltd., trade name "2P4MZ")

(Elastomer) D1: Acrylate polymer (manufactured by Nagase ChemteX Co., Ltd., trade name "SG-280 EK23", molecular weight 900,000)

(Inorganic filler) E1: Silica (manufactured by Admatechs Co., Ltd., trade name "5μm SX-E2", phenylaminosilane treatment, average particle size: 5.8μm)

B1 to B4 were prepared according to the method described in Japanese Patent Laid-Open No. 2015-89949. Specifically, it was prepared according to the following method.

(Synthesis Example 1) First, cardanol, methanol, and a 50% formaldehyde aqueous solution were mixed to obtain a mixed solution. Next, 35% hydrochloric acid was added to the obtained reaction liquid after dripping 30% sodium hydroxide aqueous solution into the obtained mixed liquid, and it was made to react, and sodium hydroxide was neutralized. Next, after adding phenol to the reaction liquid, oxalic acid was further added. Next, after washing the reaction liquid with water, excess phenol was distilled off. Thereby, resin B1 which consists of 40 mol% of the structural unit represented by following formula (5) and 60 mol% of the structural unit represented by following formula (6) was obtained.

(Synthesis Example 2) First, 4-tertiary butylphenol, methanol, and a 50% formaldehyde aqueous solution were mixed to obtain a mixed solution. Next, 35% hydrochloric acid was added to the obtained reaction liquid after dripping 30% sodium hydroxide aqueous solution into the obtained mixed liquid, and it was made to react, and sodium hydroxide was neutralized. Next, after adding 4-phenylphenol to the reaction liquid, oxalic acid was further added. Next, after washing the reaction liquid with water, excess 4-phenylphenol was distilled off. Thereby, resin B2 which consists of 50 mol% of the structural unit represented by following formula (7) and 50 mol% of the structural unit represented by following formula (8) was obtained.

(Synthesis Example 3) First, 4-(1,1,3,3-tetramethylbutyl)phenol, methanol, and a 50% formaldehyde aqueous solution were mixed to obtain a mixed solution. Next, 30% sodium hydroxide aqueous solution was dripped into the obtained mixed liquid, and it was made to react. Thereby, resin B3 which consists of a structural unit represented by following formula (9) is obtained.

(Synthesis Example 4) First, cardanol, methanol, and a 50% formaldehyde aqueous solution were mixed to obtain a mixed solution. Next, 35% hydrochloric acid was added to the obtained reaction liquid after dripping 30% sodium hydroxide aqueous solution into the obtained mixed liquid, and it was made to react, and sodium hydroxide was neutralized. Next, after adding amylphenol to the reaction liquid, oxalic acid was further added. Next, after washing the reaction liquid with water, excess amylphenol was distilled off. Thereby, resin B4 which consists of 75 mol% of the structural unit represented by the said formula (5) and 25 mol% of the structural unit represented by the following formula (10) was obtained.

<Preparation of sealing film (film-like epoxy resin composition)> (Example 1) A1, B1, D1, and E1 in amounts (parts by mass) shown in Table 1 were put into a 0.5 L (liter) polyethylene container , and stir with a stirring blade to disperse the inorganic filler E1. Then, the amount (parts by mass) of C1 shown in Table 1 was added, and the mixture was further stirred for 30 minutes. The obtained mixed solution was filtered through a nylon-made #150 mesh (106 μm opening), and the filtrate was extracted. Thereby, a varnish-like epoxy resin composition was obtained. Using a coater, the varnish-like epoxy resin composition was coated on a PET film under the following conditions. In this way, a film for sealing with a thickness of 110 μm was produced on the support.・Coating head method: Cutaway wheel ・Coating and drying speed: 1 m/min ・Drying conditions (temperature/furnace length): 80°C/1.5m (meter), 100°C/1.5m ・Support: PET film with a thickness of 38 μm

A protective layer (polyethylene terephthalate film with a thickness of 50 μm) was arranged on the side opposite to the support in the film for sealing, thereby protecting the surface of the film for sealing. In addition, in each following evaluation, the evaluation was performed after peeling a support body and a protective layer. The same applies to the following Examples and Comparative Examples.

(Examples 2 to 4 and Comparative Examples 1 to 2) The types and blending amounts of the materials (A1, B1, C1, D1, and E1) used were changed as shown in Table 1. Otherwise, the same as in Example 1. In the same manner, the varnish-like epoxy resin compositions of Examples 2 to 4 and Comparative Examples 1 to 2 were obtained. Next, the same procedure as in Example 1 was carried out, except that the varnish-like epoxy resin compositions of Examples 2 to 4 and Comparative Examples 1 to 2 were used, respectively, in place of the varnish-like epoxy resin composition of Example 1. The sealing films (thickness: 110 μm) of Examples 2 to 4 and Comparative Examples 1 to 2 were obtained.

<Evaluation method> The following methods were used to evaluate the melt viscosity, embedding properties, and hollow non-filling properties of the sealing film, as well as the elastic modulus and glass transition temperature after curing of the sealing film.

(1) Evaluation A: Melt viscosity of sealing film (film-like epoxy resin composition) 0.6 g of the sealing film was weighed and formed into a flat plate shape with a diameter of 2 cm using a compression molding machine. The obtained molded product was prepared as a sample for evaluation, and the melt viscosity of the sealing film was measured under the following conditions. The measurement was performed by raising the temperature from 40°C to 200°C. Measuring device: Rheometer, product name: ARES-G2 manufactured by Japan TA Instruments Co., Ltd. Measurement mode: Dynamic Temperature Ramp Frequency: 1.0 Hz Temperature range: 40°C to 200°C Heating rate: 5°C/min

(2) Evaluation B: Embedding properties and hollow non-filling properties at a sealing temperature of 70°C The following methods were used to evaluate the embedding properties and hollow non-filling properties at a sealing temperature of 70°C. First, a substrate (5 cm×5 cm) provided with a through hole (1 mm in diameter) in the center of the main surface was prepared. Next, a double-sided tape was pasted at a distance of 2 cm from the edge of the through hole on one of the main surfaces of the substrate, and the glass plate was pasted on the substrate through the double-sided tape. The obtained laminate was placed with the glass plate side facing down, and a 1 cm square sealing film was placed on the surface of the substrate opposite to the glass plate so as to close the through holes. Next, after placing a weight of 100 g on the film for sealing, heating was performed in an oven (trade name "SAFETY OVEN SPH-201" by ESPEC Co., Ltd.) at 70° C. for 1 hour.

After heating, the presence or absence of resin flowing into the glass plate side from the through hole due to the melting of the sealing film and the inflow amount (inflow area) of the resin were visually observed, and the embedding properties and hollow non-filling properties were evaluated according to the following criteria. [Embedding properties] A: Resin reaches the substrate B: Resin does not reach the substrate [Hollow non-filling properties] A: Inflow area ≦ 2.5mm ² B: Inflow area ≦ 5mm ² but > 2.5mm ² C: Inflow area > 5mm ²

(3) Evaluation C: Embedding properties and hollow non-filling properties at a melt viscosity of 7000 Pa･s Based on the measurement results of the melt viscosity of Evaluation A, sealing was performed at a temperature at which the melt viscosity of the sealing film became 7000 Pa･s, except that Otherwise, the embedding and hollow non-filling properties were evaluated in the same way as Evaluation B.

(4) Evaluation D: Elastic modulus and glass transition temperature Tg after curing of sealing film The sealing films of Examples and Comparative Examples were laminated on copper foil under the following conditions to obtain a sealing film with copper foil film.・Laminator device: Vacuum pressure laminator MVLP-500 manufactured by Meiki Seisakusho ・Lamination temperature: 110°C ・Lamination pressure: 0.5MPa ・Evacuation time: 30 seconds ・Lamination time: 40 seconds

The sealing film with copper foil is pasted on a stainless steel (SUS) plate, and the sealing film is hardened according to the following conditions to obtain a cured product of the sealing film with copper foil (epoxy with copper foil) Resin hardened body) ・Oven: SAFETY OVEN SPH-201 manufactured by ESPEC Co., Ltd. ・Oven temperature: 140°C ・Time: 120 minutes

After peeling the copper foil from the cured product of the copper foil-attached sealing film, the cured product of the sealing film was cut into 4 mm×30 mm to prepare a test piece. The elastic modulus and glass transition temperature of the produced test piece were measured under the following conditions.・Measuring device: DVE (DVE-V4 manufactured by RHEOLOGY Co., Ltd.) ・Measuring temperature: 25 to 300°C ・Heating rate: 5°C/min

When the elastic modulus is high, the sealing structure becomes liable to warp and crack, so the elastic modulus is evaluated according to the following judgment criteria. A: Modulus of elasticity (30℃) ≦15GPa B: Modulus of elasticity (30℃) ＞15GPa

When the glass transition temperature Tg is low, the thermal reliability of the sealing structure deteriorates, so the glass transition temperature is evaluated according to the following judgment criteria. A: Glass transition temperature (°C) ≧100 B: Glass transition temperature (°C) <100

<Evaluation Results> Table 1 shows the results. In addition, the compounding quantity of each component in Table 1 is a solid content quantity (quantity except the quantity of a solvent).

[Table 1]

As shown in Table 1, in the examples, both the embedding property and the hollow non-filling property can be achieved at a sealing temperature of 70°C. In addition, even when sealing is performed at a temperature where the melt viscosity is 7000 Pa·s, it is possible to have both embedding properties and hollow non-filling properties. On the other hand, in Comparative Example 1, the desired embedding property was not obtained at a sealing temperature of 70° C., and the desired hollow non-filling property was not obtained even when the melt viscosity was at a temperature of 7000 Pa·s. In addition, in Comparative Example 2, the desired hollow non-fillability was not obtained in both evaluation A (sealing temperature: 70° C.) and evaluation B (melt viscosity: 7000 Pa·s).

1‧‧‧Support 2‧‧‧Film for sealing 2a‧‧‧Cutting of film for sealing (sealing part) 10‧‧‧Film for sealing with support 20‧‧‧Surface acoustic wave element (body to be sealed )20a‧‧‧Surface acoustic wave element on the hollow region side (substrate side) 30‧‧‧Substrate 40‧‧‧Bumps 50‧‧‧Hollow region 60‧‧‧Hollow structure 100, 200‧‧‧Hollow sealing Structure (sealed structure)

Fig. 1 is a schematic cross-sectional view showing a support-attached sealing film having a sealing film according to an embodiment. FIG. 2 is a schematic cross-sectional view for explaining an embodiment of a method for producing a hollow sealing structure.

Domestic storage information (please note in the order of storage institution, date and number) None

Foreign deposit information (please note in the order of deposit country, institution, date and number) None

1: Support body

2: Film for sealing

10: Sealing film with support

Claims (11)

A sealing film comprising a resin composition containing a thermosetting resin and an inorganic filler, the thermosetting resin having a structural unit represented by the following formula (1):

In formula (1), X ¹ represents a reactive functional group, and R ¹ represents a hydrocarbon group having 2 to 25 carbon atoms; the sealing film is used to seal the body to be sealed, and the body to be sealed is provided on the substrate through the bumps superior. The sealing film according to claim 1, wherein the thermosetting resin further has a structural unit represented by the following formula (2):

In formula (2), X ² represents a reactive functional group, and R ² represents a hydrogen atom or a phenyl group. The film for sealing according to claim 1 or 2, wherein X ¹ is a hydroxyl group. The film for sealing according to claim 1 or 2, wherein the resin composition further contains an epoxy resin. The sealing film according to claim 1 or 2, wherein the content of the structural unit represented by the formula (1) in the thermosetting resin is based on the total amount of the structural units constituting the thermosetting resin. In total, it is more than 20 mol%. The sealing film according to claim 1 or 2, wherein the thermosetting resin has a weight average molecular weight of 500 or more. The film for sealing according to claim 1 or 2, wherein the film thickness is 20 to 250 μm. A method of manufacturing a sealing structure, which prepares a hollow structure including a substrate and a body to be sealed provided on the substrate with bumps interposed therebetween, and a hollow body is provided between the substrate and the body to be sealed The said to-be-sealed body is sealed by the film for sealing described in any one of Claims 1-7. The method for producing a sealing structure according to claim 8, wherein the body to be sealed is a surface acoustic wave element having electrodes on the side of the hollow region. A sealing structure comprising: a substrate; a body to be sealed provided on the substrate with bumps interposed therebetween; and a cured product of the sealing film according to any one of claims 1 to 7, which is used for The body to be sealed is sealed; and a hollow area is provided between the substrate and the body to be sealed area. The sealing structure according to claim 10, wherein the body to be sealed is a surface acoustic wave element having electrodes on the side of the hollow region.

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