KR102509242B1 - adhesive sheet - Google Patents

Abstract

A pressure-sensitive adhesive sheet comprising a resin, thermally expandable particles having an expansion onset temperature (t) of 120 to 250°C, a non-adhesive thermally expandable substrate, and an adhesive layer containing an adhesive resin, wherein the thermally expandable substrate meets the following requirements ( A pressure-sensitive adhesive sheet satisfying 1) to (2) is provided. The pressure-sensitive adhesive sheet can be easily peeled off with a weak force when peeling, while suppressing sedimentation of the target when heating, when the target is temporarily fixed. Requirement (1): The storage modulus (E′) (100) of the thermally expandable substrate at 100° C. is 2.0×10 ⁵ Pa or more. Requirement (2): The storage elastic modulus (E′) (t) of the thermally expandable substrate at the expansion start temperature (t) of the thermally expandable particles is 1.0×10 ⁷ Pa or less.

Description

adhesive sheet

The present invention relates to an adhesive sheet.

Adhesive sheets are sometimes used not only for semi-permanently fixing members, but also for temporary fixing for temporarily fixing building materials, interior materials, electronic parts, and the like when processing them.

Coexistence of adhesiveness at the time of use and releasability after use are required for such an adhesive sheet for temporary fixing.

For example, Patent Document 1 discloses a heat-peelable pressure-sensitive adhesive sheet for temporary fixing at the time of cutting electronic parts, in which a heat-expandable adhesive layer containing heat-expandable microspheres is provided on at least one surface of a base material. has been initiated.

In this heat-peelable pressure-sensitive adhesive sheet, the maximum particle diameter of the heat-expandable microsphere is adjusted with respect to the thickness of the heat-expandable pressure-sensitive adhesive layer, and the average roughness of the center line of the surface of the heat-expandable pressure-sensitive adhesive layer before heating is adjusted to 0.4 µm or less.

In Patent Literature 1, the heat-peelable pressure-sensitive adhesive sheet can ensure a contact area with an adherend when cutting an electronic component, and exhibits adhesiveness capable of preventing adhesive defects such as chip scattering. , After use, there is a description to the effect that the heat-expandable microsphere can be easily peeled off by heating to expand the contact area with the adherend.

Patent Document 1: Japanese Patent No. 3594853

BACKGROUND OF THE INVENTION In recent years, miniaturization, thinning, and high density of electronic devices have progressed, and semiconductor devices mounted in electronic devices are also being demanded for miniaturization, thinning, and high density. FOWLP (Fan-out-Wafer-Le-Vel-Package) is attracting attention as a semiconductor package technology that can respond to these demands.

As shown in FIG. 3 , in the FOWLP 50, a redistribution layer 53 is provided on the surface of the semiconductor chip 51 sealed by the encapsulation resin layer 52, and solder balls pass through the redistribution layer 53. It is a semiconductor package in which 54 and the semiconductor chip 51 are electrically connected.

As shown in FIG. 3 , since the FOWLP 50 can fan out terminals, which are solder balls 54, to the outside of the semiconductor chip 51, the number of terminals is reduced compared to the area of the semiconductor chip 51. It can be applied to many uses.

By the way, in the manufacturing process of FOWLP, a semiconductor chip is placed on an adhesive sheet, and an encapsulating resin in a flowable state heated to around 100° C. is (1) adhered to the semiconductor chip and the periphery of the semiconductor chip Encapsulation step (1) or (2) of filling the surface of the sheet and heating to form a layer composed of encapsulating resin, or (2) laminating a resin film for encapsulation on a semiconductor chip and heating and laminating the laminate. this is done After the encapsulation step, the adhesive sheet is removed, and a redistribution layer and a solder ball are formed on the exposed surface of the semiconductor chip, thereby manufacturing the FOWLP.

In the pressure-sensitive adhesive sheet used in the above sealing step, from the time the semiconductor chip is placed to the time when the sealing resin is sealed, the positional displacement of the semiconductor chip does not occur, and the sealing resin does not penetrate at the adhesive interface between the semiconductor chip and the pressure-sensitive adhesive sheet. A certain degree of adhesion is required. On the other hand, after encapsulation, releasability with which the adhesive sheet can be easily removed is required.

In the sealing step of the FOWLP manufacturing method described above, consider using a heat-peelable pressure-sensitive adhesive sheet provided with a heat-expandable pressure-sensitive adhesive layer containing heat-expandable microspheres on a base material, for example, as described in Patent Document 1. do.

However, according to the study of the present inventors, when the adhesive sheet described in Patent Literature 1 is used in the sealing step, the elastic modulus of the heat-expandable adhesive layer decreases due to heating in the sealing step, and the mounted semiconductor chip moves toward the adhesive sheet side. subsidence was found.

If the sealing resin is cured while the semiconductor chip is settled on the adhesive sheet side, the surface of the semiconductor chip side containing the sealing resin after removing the adhesive sheet has a step difference between the surface of the semiconductor chip and the surface of the sealing resin, resulting in poor flatness. . In addition, displacement of semiconductor chips may occur, and adverse effects such as inter-chip distances not being constant may occur.

In addition, when removing the PSA sheet described in Patent Literature 1, even if the heat-expandable adhesive layer is expanded by heating, it is also considered that the semiconductor chip settles toward the PSA sheet side, making peeling difficult without external force of a certain magnitude.

In addition, these problems are not limited to the encapsulation process of the FOWLP manufacturing method, but can also occur in the manufacturing process of PSP (Panel Scale Package), for example, and heat treatment is performed while fixing the object to the adhesive sheet. This is a concern that may arise in the process.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an adhesive sheet that can be easily peeled off with a weak force during peeling while suppressing sedimentation of the object when the object is temporarily fixed or heated. do.

The inventors of the present invention have a configuration of a pressure-sensitive adhesive sheet having a non-adhesive heat-expandable base material containing a resin and heat-expandable particles and an adhesive layer containing an adhesive resin, and storing the heat-expandable base material at a predetermined temperature. It discovered that the said subject was solvable by adjusting elastic modulus E' to a specific range.

That is, the present invention relates to the following [1] to [12].

[1] An adhesive sheet having a non-adhesive thermally expandable substrate containing a resin and thermally expandable particles having an expansion onset temperature (t) of 120 to 250°C, and an adhesive layer comprising an adhesive resin, wherein the thermally expandable substrate is An adhesive sheet that satisfies the following requirements (1) to (2).

Requirement (1): The storage modulus (E') (100) of the thermally expandable substrate at 100°C is 2.0×10 ⁵ Pa or more.

Requirement (2): The storage elastic modulus (E') (t) of the thermally expandable substrate at the expansion start temperature (t) of the thermally expandable particles is 1.0×10 ⁷ Pa or less.

[2] The adhesive sheet according to [1] above, wherein the thermally expandable substrate satisfies the following requirement (3).

Requirement (3): The storage modulus (E') (23) of the thermally expandable substrate at 23°C is 1.0×10 ⁶ Pa or more.

[3] The pressure-sensitive adhesive sheet according to [1] or [2] above, wherein the ratio of the thickness of the thermally expandable substrate to the thickness of the pressure-sensitive adhesive layer (heat-expandable substrate/pressure-sensitive adhesive layer) at 23°C is 0.2 or more.

[4] The pressure-sensitive adhesive sheet according to any one of [1] to [3] above, wherein the thickness of the heat-expandable substrate at 23°C is 10 to 1000 μm, and the thickness of the pressure-sensitive adhesive layer is 1 to 60 μm.

[5] The pressure-sensitive adhesive sheet according to any one of [1] to [4] above, wherein the probe tack value on the surface of the thermally expandable substrate is less than 50 mN/5 mmφ.

[6] The pressure-sensitive adhesive sheet according to any one of [1] to [5] above, wherein the storage shear modulus (G') (23) of the pressure-sensitive adhesive layer at 23°C is 1.0 × 10 ⁴ to 1.0 × 10 ⁸ Pa.

[7] The pressure-sensitive adhesive sheet according to any one of [1] to [6] above, each having two pressure-sensitive adhesive layers on both surfaces of the heat-expandable substrate.

[8] The pressure-sensitive adhesive sheet according to any one of [1] to [7] above, wherein the average particle diameter of the heat-expandable particles before expansion at 23°C is from 3 to 100 µm.

[9] The pressure-sensitive adhesive sheet according to any one of [1] to [8] above, which is used in a sealing step involving heating using an encapsulating resin.

[10] A thermally expandable substrate comprising a resin and thermally expandable particles having an expansion onset temperature (t) of 120 to 250°C, is non-adhesive, and satisfies the following requirements (1) to (2).

Requirement (1): The storage modulus (E') (100) of the thermally expandable substrate at 100°C is 2.0×10 ⁵ Pa or more.

Requirement (2): The storage elastic modulus (E') (t) of the thermally expandable substrate at the expansion start temperature (t) of the thermally expandable particles is 1.0×10 ⁷ Pa or less.

[11] After attaching the PSA sheet according to any one of [1] to [9] above to an adherend, peeling the PSA sheet from the adherend by heating at a temperature equal to or higher than the expansion start temperature (t). , How to use the adhesive sheet.

[12] The method of using the pressure-sensitive adhesive sheet according to the above [11], which is used in a sealing step involving heating using an encapsulating resin.

The pressure-sensitive adhesive sheet of the present invention can be easily peeled off with a weak force when peeling, while suppressing settling of the target when heating, when the object is temporarily fixed.

1 is a schematic cross-sectional view of an adhesive sheet showing an example of the configuration of the adhesive sheet of the present invention.
Fig. 2 is a cross-sectional schematic diagram of a double-sided pressure-sensitive adhesive sheet showing an example of the configuration of the pressure-sensitive adhesive sheet of the present invention.
3 is a cross-sectional schematic diagram showing an example of FOWLP.

In the present invention, "active ingredient" refers to a component excluding the dilution solvent among the components included in the target composition.

Incidentally, the mass average molecular weight (Mw) is a value measured in terms of standard polystyrene measured by gel permeation chromatography (GPC) method, and is a value specifically measured based on the method described in Examples.

In the present invention, for example, "(meth)acrylic acid" represents both "acrylic acid" and "methacrylic acid", and other similar terms are also the same.

In addition, the lower limit value and upper limit value described step by step for a preferable numerical range (for example, ranges such as content) can be independently combined. For example, from the description of "preferably 10 to 90, more preferably 30 to 60", "10 to 60" is obtained by combining "preferably lower limit value (10)" and "more desirable upper limit value (60)". may be

[Configuration of the pressure-sensitive adhesive sheet of the present invention]

The pressure-sensitive adhesive sheet of the present invention is not particularly limited as long as it has a non-adhesive heat-expandable base material containing resin and heat-expandable particles, and a pressure-sensitive adhesive layer containing pressure-sensitive adhesive resin.

1 and 2 are cross-sectional schematic views of the PSA sheet showing the configuration of the PSA sheet of the present invention.

As the PSA sheet of one embodiment of the present invention, PSA sheet 1a having an PSA layer 12 on a thermally expandable substrate 11 shown in Fig. 1(a) is exemplified.

Further, the PSA sheet of one embodiment of the present invention may have a configuration further including a release material 13 on the PSA surface of PSA layer 12, as in PSA sheet 1b shown in FIG. 1(B).

As the pressure-sensitive adhesive sheet of another embodiment of the present invention, it is good also as a structure which each has the said two adhesive layers on both surfaces of the said heat-expandable base material.

As an adhesive sheet having such a configuration, for example, a double-sided adhesive sheet having a configuration in which a thermally expandable substrate 11 as shown in FIG. 2 (a) is sandwiched between a first adhesive layer 121 and a second adhesive layer 122 The adhesive sheet 2a is mentioned.

In addition, like the double-sided adhesive sheet 2b shown in FIG. 2(b), it further has a release material 131 on the adhesive surface of the first adhesive layer 121, and on the adhesive surface of the second adhesive layer 122. It is good also as a structure which has the release material 132 further.

In addition, in the double-sided pressure-sensitive adhesive sheet 2b shown in FIG. 2 (b), the peeling force and the peeling material 132 when peeling the release material 131 from the first pressure-sensitive adhesive layer 121 are compared to the second pressure-sensitive adhesive layer 122. When the peeling force at the time of peeling off from the same level is about the same, when trying to peel both release materials outwardly, a phenomenon in which the pressure-sensitive adhesive layer is divided along the two release materials and peels off may occur.

From the viewpoint of suppressing this phenomenon, it is preferable to use two types of release materials designed to have different peel forces from the pressure-sensitive adhesive layer to be adhered to each other as the two release materials 131 and 132 .

As another PSA sheet, in the double-sided PSA sheet 2a shown in FIG. It may be a double-sided pressure-sensitive adhesive sheet having a structure in which a release material is laminated and wound into a roll shape.

Here, in the PSA sheet of one embodiment of the present invention, another layer may be provided between the thermally expandable substrate and the PSA layer.

However, from the viewpoint of an adhesive sheet that can be easily peeled off with a weak force, a thermally expandable substrate (such as the adhesive sheets 1a and 1b shown in FIG. 11) and the pressure-sensitive adhesive layer 12 are preferably directly laminated.

[thermally expandable substrate]

The heat-expandable base material of the pressure-sensitive adhesive sheet of the present invention contains a resin and heat-expandable particles having an expansion onset temperature (t) of 120 to 250°C, and satisfies the following requirements (1) to (2) as a non-adhesive base material. .

Requirement (1): The storage modulus (E') (100) of the thermally expandable substrate at 100°C is 2.0×10 ⁵ Pa or more.

Requirement (2): The storage elastic modulus (E') (t) of the thermally expandable substrate at the expansion start temperature (t) of the thermally expandable particles is 1.0×10 ⁷ Pa or less.

In addition, in this specification, the storage elastic modulus (E') of a thermally expansible substrate at a predetermined temperature means the value measured according to the method described in the Example.

For example, in the encapsulation step of the manufacturing process of FOWLP, encapsulation resin in a fluid state by heating to around 100°C is filled on a semiconductor chip, or a resin sheet for encapsulation is laminated on a semiconductor chip, heated, and laminated. Depending on the method, it is common to encapsulate the semiconductor chip.

That is, the above requirement (1) assumes that the temperature environment in the sealing step of the FOWLP manufacturing process is 100 ° C., and the storage modulus (E ') of the thermally expandable substrate under the temperature environment in the sealing step is defined.

In general, since the heat-expandable pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet described in Patent Literature 1 contains an adhesive resin, the degree of decrease in the storage elastic modulus (E') tends to be very large as the temperature rises.

Here, when the degree of reduction of the storage elastic modulus (E') of the heat-expandable pressure-sensitive adhesive layer is extremely large, the heat-expandable particles and the adhesive resin contained in the heat-expandable pressure-sensitive adhesive layer tend to flow, and accordingly, the adhesion surface of the heat-expandable pressure-sensitive adhesive layer easier to transform

As a result, when encapsulating while pouring encapsulating resin having fluidity onto an object such as a semiconductor chip, for example, by heating the encapsulating resin at around 100° C., the adhesive sheet becomes flexible according to the weight and heating of the encapsulating resin. This makes it easy for the object to settle toward the pressure-sensitive adhesive sheet. The settling of the object also causes the object to be displaced, the distance between the objects to vary, and the flatness to be poor due to irregularities on the surface on which the object is placed after sealing. In addition, this problem may arise similarly also in the sealing method by lamination using the resin film for sealing.

Further, in the pressure-sensitive adhesive sheet in which a new pressure-sensitive adhesive layer is provided on the surface of the heat-expandable pressure-sensitive adhesive layer, as described above, the flow of the heat-expandable particles and the pressure-sensitive adhesive resin in the heat-expandable pressure-sensitive adhesive layer causes deformation of the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer. It is easy to occur, and the above-described problems may occur.

In response to these problems, the pressure-sensitive adhesive sheet of the present invention contains a resin and thermally expandable particles, and has a storage modulus (E') at 100°C (100) of 2.0×10 ⁵ Pa as stipulated in the above requirement (1). By using the above-adjusted thermally expandable substrate, the above-mentioned problem is solved.

By having a thermally expandable substrate that satisfies the requirement (1), the flow of thermally expandable particles can be appropriately suppressed even under the temperature environment in the sealing process such as the manufacturing process of FOWLP, so an adhesive provided on the thermally expandable substrate The adhesive surface of the layer becomes difficult to deform.

As a result, the weight of the encapsulating resin laminated on the object, such as a semiconductor chip, or the pressure accompanying the lamination using the resin sheet for encapsulation causes the object to sink toward the adhesive sheet side, resulting in difficulties in forming a flat surface, and the location of the object. It is possible to suppress the occurrence of deviation.

On the other hand, when a thermally expandable substrate having a storage modulus (E′) (100) of less than 2.0×10 ⁵ Pa is used, the fluidity of the thermally expandable particles contained in the thermally expandable substrate is sufficiently high under a temperature environment of 100° C. assuming a sealing step. It is not suppressed, and deformation of the adhesive surface of the adhesive layer provided on the heat-expandable base material is likely to occur.

As a result, for example, when the pressure-sensitive adhesive sheet having the heat-expandable base material is used in the encapsulation step of manufacturing FOWLP, the weight of the encapsulating resin or the pressure accompanying the lamination using the resin sheet for encapsulation causes the semiconductor chip to move through the adhesive sheet. It settles to the side of the pressure-sensitive adhesive layer, and irregularities are seen on the surface of the semiconductor chip after sealing, which may cause a problem that it is difficult to form a flat surface.

The storage elastic modulus (E′) (100) specified in the requirement (1) of the thermally expandable substrate used in one embodiment of the present invention is 2.0 × 10 ⁵ Pa or more, but from the above viewpoint, preferably 4.0 × 10 ⁵ Pa or more, more preferably 6.0 × 10 ⁵ Pa or more, still more preferably 8.0 × 10 ⁵ Pa or more, and even more preferably 1.0 × 10 ⁶ Pa or more.

In the sealing step, from the viewpoint of effectively suppressing displacement of objects to be sealed, such as semiconductor chips, the storage elastic modulus (E') (100) specified in the requirement (1) of the thermally expandable substrate is preferably 1.0 × 10 ¹² Pa or less, more preferably 1.0 × 10 ¹¹ Pa or less, still more preferably 1.0 × 10 ¹⁰ Pa or less, still more preferably 1.0 × 10 ⁹ Pa or less.

On the other hand, the above requirement (2) stipulates the storage elastic modulus (E') of the thermally expandable substrate at the time of peeling of the pressure-sensitive adhesive sheet.

When peeling the adhesive sheet of the present invention from an adherend, the thermally expandable particles in the thermally expandable substrate expand by heating to a temperature equal to or higher than the expansion start temperature (t) of the thermally expandable particles, and irregularities are formed on the surface of the thermally expandable substrate. , the pressure-sensitive adhesive layer laminated on the irregularities is also pushed up, and irregularities are also formed on the adhesive surface.

Further, by forming irregularities on the adhesion surface of the pressure-sensitive adhesive layer, the contact area between the adherend (semiconductor chip and encapsulating resin after curing) and the adhesion surface is reduced, and a space is created between the adherend and the adhesion surface, resulting in adhesion from the adherend. The sheet can be easily peeled off with a weak force.

However, in order to improve the peelability of the PSA sheet, it is necessary to facilitate the formation of irregularities on the adhesive surface of the PSA layer when heated to a temperature equal to or higher than the expansion start temperature (t). For this purpose, it is necessary that the thermally expandable particles included in the thermally expandable substrate are adjusted to be easily expandable.

In the above requirement (2), the storage elastic modulus (E')(t) of the thermally expandable substrate is specified at the expansion start temperature (t) of the thermally expandable particles. It can also be said as an index indicating the rigidity of the base material.

That is, according to the study of the present inventors, when the storage modulus (E′) (t) of the thermally expandable substrate exceeds 1.0×10 ⁷ Pa at the expansion start temperature (t) of the thermally expandable particles, the expansion start temperature (t) or more It was found that even when the thermally expandable particles try to expand by heating to the temperature, the expansion is suppressed and the thermally expandable particles do not become sufficiently large, and the formation of unevenness on the adhesive surface of the pressure-sensitive adhesive layer laminated on the surface of the thermally expandable base material becomes insufficient. .

The storage modulus (E′) (t) specified in the requirement (2) of the thermally expandable substrate used in one embodiment of the present invention is, from the above viewpoint, preferably 9.0 × 10 ⁶ Pa or less, more preferably 8.0 × 10 ⁶ Pa or less, more preferably 6.0 x 10 ⁶ Pa or less, still more preferably 4.0 x 10 ⁶ Pa or less.

In addition, from the viewpoint of suppressing the flow of the expanded thermally expandable particles, improving the shape retention of irregularities formed on the adhesive surface of the pressure-sensitive adhesive layer, and further improving the peelability, the requirements (2) for the thermally expandable substrate The storage elastic modulus (E′)(t) is preferably 1.0×10 ³ Pa or more, more preferably 1.0×10 ⁴ Pa or more, still more preferably 1.0×10 ⁵ Pa or more.

In addition, it is preferable that the thermally expandable base material included in the pressure-sensitive adhesive sheet of one embodiment of the present invention further satisfies the following requirement (3).

Requirement (3): The storage modulus (E') (23) of the thermally expandable substrate at 23°C is 1.0×10 ⁶ Pa or more.

By using a thermally expandable substrate that satisfies the above requirement (3), positional displacement at the time of affixing an object such as a semiconductor chip can be prevented. Moreover, when an object is affixed, excessive sedimentation to the adhesive layer can also be prevented.

For example, a semiconductor chip is usually mounted so that its circuit surface may be covered with the adhesive surface of the adhesive layer. For mounting of semiconductor chips, a known device such as a flip chip bonder or a die bonder may be used, for example.

Here, when a semiconductor chip is placed on the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet using a flip-chip bonder or a die bonder, a force to push the semiconductor chip in the thickness direction of the pressure-sensitive adhesive sheet is applied, so that the semiconductor chip moves along the thickness direction of the pressure-sensitive adhesive layer. There is a risk of excessive sedimentation to the side.

In addition, when a semiconductor chip is placed on the pressure-sensitive adhesive sheet using a flip chip bonder or die bonder, a force for moving the semiconductor chip in the horizontal direction of the pressure-sensitive adhesive sheet is also applied, so that the semiconductor chip may be displaced in the horizontal direction of the pressure-sensitive adhesive layer. There are also concerns.

However, this problem can be solved by using a thermally expandable substrate that satisfies the above requirement (3).

From the above viewpoint, the storage elastic modulus (E′) 23 of the thermally expandable substrate specified in the above requirement (3) is preferably 5.0 × 10 ⁶ to 5.0 × 10 ¹² Pa, more preferably 1.0 × 10 7 to 1.0 × 10 ⁷ Pa. 1.0×10 ¹² Pa, more preferably 5.0×10 ⁷ to 1.0×10 ¹¹ Pa, still more preferably 1.0×10 ⁸ to 1.0×10 ¹⁰ Pa.

In one aspect of the present invention, the thickness of the thermally expandable substrate at 23°C is preferably 10 to 1000 μm, more preferably 20 to 500 μm, still more preferably 25 to 400 μm, still more preferably 30 to 300 μm.

Also, in the present specification, the thickness of the thermally expandable substrate means a value measured according to the method described in Examples. In addition, the thickness of the thermally expandable substrate is the value before expansion of the thermally expandable particles.

The thermally expandable substrate of the PSA sheet of one embodiment of the present invention is a non-adhesive substrate.

In the present invention, it is judged whether or not the substrate is non-adhesive, if the probe tack value measured in accordance with JIS 　Z0237: 1991 is less than 50 mN/5 mmφ for the surface of the target substrate, the substrate is referred to as a "non-adhesive substrate". judge that

Here, the probe tack value on the surface of the thermally expandable substrate used in one embodiment of the present invention is usually less than 50 mN/5 mmφ, but is preferably less than 30 mN/5 mmφ, more preferably less than 10 mN/5 mmφ, and furthermore Preferably it is less than 5 mN/5 mmφ.

Further, in the present specification, a specific method for measuring the probe tack value on the surface of the thermally expandable substrate follows the method described in Examples.

The heat-expandable base material of the pressure-sensitive adhesive sheet of one embodiment of the present invention contains a resin and heat-expandable particles, but may contain an additive for base material as necessary within a range not impairing the effects of the present invention.

Also, the thermally expandable substrate may be formed of a resin composition (y) containing a resin and thermally expandable particles.

Hereinafter, each component contained in the resin composition (y), which is a forming material of the thermally expandable substrate, will be described.

<resin>

The resin contained in the resin composition (y) may be a polymer capable of forming a thermally expandable base material satisfying the above requirements (1) and (2).

Moreover, as resin contained in resin composition (y), a non-adhesive resin may be sufficient as it, and an adhesive resin may be sufficient as it.

That is, even if the resin contained in the resin composition (y) is an adhesive resin, in the process of forming the thermally expandable substrate with the resin composition (y), the resin obtained by polymerization of the adhesive resin with a polymerizable compound is a non-adhesive resin, The thermally expandable base material containing the resin may be non-adhesive.

The mass average molecular weight (Mw) of the resin contained in the resin composition (y) is preferably 10 million to 1 million, more preferably 10 million to 700,000, still more preferably 1000 to 500,000.

In addition, when the resin is a copolymer having two or more types of structural units, the form of the copolymer is not particularly limited, and may be any of block copolymers, random copolymers, and graft copolymers.

The content of the resin is preferably 50 to 99% by mass, more preferably 60 to 95% by mass, still more preferably 65 to 90% by mass, based on the total amount (100% by mass) of the active ingredients of the resin composition (y). mass%, more preferably 70 to 85 mass%.

Further, from the viewpoint of forming a thermally expandable substrate that satisfies the requirements (1) and (2), the resin contained in the resin composition (y) includes at least one selected from acrylic urethane resins and olefin resins. it is desirable

Moreover, as said acrylic urethane type-resin, the following resin (U1) is preferable.

- An acrylic urethane-based resin (U1) obtained by polymerizing a urethane prepolymer (UP) and a vinyl compound containing (meth)acrylic acid ester.

(Acrylic urethane resin (U1))

Examples of the urethane prepolymer (UP) serving as the main chain of the acrylic urethane resin (U1) include a reaction product of a polyol and polyvalent isocyanate.

Further, the urethane prepolymer (UP) is preferably obtained by subjecting the chain extension reaction to using a chain extension agent.

Examples of the polyol used as a raw material of the urethane prepolymer (UP) include alkylene type polyols, ether type polyols, ester type polyols, ester amide type polyols, ester/ether type polyols, and carbonate type polyols.

These polyols may be used alone or in combination of two or more.

As the polyol used in one embodiment of the present invention, diols are preferable, ester type diols, alkylene type diols and carbonate type diols are more preferable, and ester type diols and carbonate type diols are still more preferable.

Examples of the ester type diol include alkanediols such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, and 1,6-hexanediol; Alkylene glycol, such as ethylene glycol, propylene glycol, diethylene glycol, and dipropylene glycol; one or two or more selected from diols such as phthalic acid, isophthalic acid, terephthalic acid, naphthalene dicarboxylic acid, 4,4-diphenyldicarboxylic acid, diphenylmethane-4,4'-dicar Boxylic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, hetic acid, maleic acid, fumaric acid, itaconic acid, cyclohexane-1,3-dicarboxylic acid, cyclohexane-1,4-dicarboxylic acid, hexa and dicarboxylic acids such as hydrophthalic acid, hexahydroisophthalic acid, hexahydroterephthalic acid, and methyl hexahydrophthalic acid, and condensation polymers of one or two or more kinds selected from anhydrides thereof.

Specifically, polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyhexamethylene isophthalate diol, polyneopentyl adipate diol, polyethylene propylene adipate diol, polyethylene butylene adipate diol, Polybutylene hexamethylene adipate diol, polydiethylene adipate diol, poly (polytetramethylene ether) adipate diol, poly (3-methylpentylene adipate) diol, polyethylene azerate diol, polyethylene sebacate diol, poly butylene azerate diol, polybutylene sebacate diol, and polyneopentyl terephthalate diol; and the like.

Examples of the alkylene diol include alkanediol such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, and 1,6-hexanediol; Alkylene glycol, such as ethylene glycol, propylene glycol, diethylene glycol, and dipropylene glycol; polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polybutylene glycol; polyoxyalkylene glycols such as polytetramethylene glycol; etc. can be mentioned.

Examples of the carbonate-type diol include 1,4-tetramethylene carbonate diol, 1,5-pentamethylene carbonate diol, 1,6-hexamethylene carbonate diol, 1,2-propylene carbonate diol, and 1,3-propylene carbonate. diol, 2,2-dimethyl propylene carbonate diol, 1,7-heptamethylene carbonate diol, 1,8-octamethylene carbonate diol, 1,4-cyclohexane carbonate diol, and the like.

Examples of the polyvalent isocyanate used as a raw material of the urethane prepolymer (UP) include aromatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates.

These polyhydric isocyanates may be used independently or may use 2 or more types together.

Further, such polyvalent isocyanate may be a trimethylolpropane adduct-type modified product, a biuret-type modified product reacted with water, or an isocyanurate-type modified product containing an isocyanurate ring.

Among these, as the polyhydric isocyanate used in one embodiment of the present invention, diisocyanate is preferable, and 4,4'-diphenylmethane diisocyanate (MDI) and 2,4-tolylene diisocyanate (2,4-TDI) , 2,6-tolylene diisocyanate (2,6-TDI), hexamethylene diisocyanate (HMDI), and at least one selected from alicyclic diisocyanates are more preferred.

Examples of the alicyclic diisocyanate include 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate, IPDI), 1,3-cyclopentane diisocyanate, and 1,3-cyclohexane diisocyanate. Isocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, and the like, but isophorone diisocyanate (IPDI) is preferred.

In one aspect of the present invention, the urethane prepolymer (UP) serving as the main chain of the acrylic urethane resin (U1) is preferably a linear urethane prepolymer that is a reaction product of a diol and diisocyanate and has ethylenically unsaturated groups at both ends.

As a method of introducing ethylenically unsaturated groups to both ends of the linear urethane prepolymer, a method of reacting a diol and a diisocyanate compound with an NCO group at the terminal of the linear urethane prepolymer formed by reacting a hydroxyalkyl (meth)acrylate is mentioned. can

Examples of the hydroxyalkyl (meth)acrylate include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate. hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate and the like.

As the vinyl compound serving as the side chain of the acrylic urethane resin (U1), at least (meth)acrylic acid ester is included.

As the (meth)acrylic acid ester, at least one selected from alkyl (meth)acrylates and hydroxyalkyl (meth)acrylates is preferable, and alkyl (meth)acrylates and hydroxyalkyl (meth)acrylates are used in combination. it is more preferable

When using an alkyl (meth)acrylate and a hydroxyalkyl (meth)acrylate together, the blending ratio of the hydroxyalkyl (meth)acrylate to 100 parts by mass of the alkyl (meth)acrylate is preferably 0.1 to 100. Part by mass, more preferably 0.5 to 30 parts by mass, even more preferably 1.0 to 20 parts by mass, still more preferably 1.5 to 10 parts by mass.

The number of carbon atoms in the alkyl group of the alkyl (meth)acrylate is preferably 1 to 24, more preferably 1 to 12, still more preferably 1 to 8, still more preferably 1 to 3.

Moreover, as a hydroxyalkyl (meth)acrylate, the same thing as the hydroxyalkyl (meth)acrylate used in order to introduce ethylenically unsaturated groups to both terminals of the above-mentioned linear urethane prepolymer is mentioned.

Examples of vinyl compounds other than (meth)acrylic acid esters include aromatic hydrocarbon-based vinyl compounds such as styrene, α-methylstyrene, and vinyltoluene; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; polar group-containing monomers such as vinyl acetate, vinyl propionate, (meth)acrylonitrile, N-vinylpyrrolidone, (meth)acrylic acid, maleic acid, fumaric acid, itaconic acid, and meta(acrylamide); etc. can be mentioned.

These may be used independently and may use 2 or more types together.

The content of the (meth)acrylic acid ester in the vinyl compound is preferably 40 to 100% by mass, more preferably 65 to 100% by mass, still more preferably 80 to 100% by mass, based on the total amount (100% by mass) of the vinyl compound. 100% by mass, more preferably 90 to 100% by mass.

The total content of alkyl (meth)acrylate and hydroxyalkyl (meth)acrylate in the vinyl compound is preferably 40 to 100% by mass, more preferably 65 - 100% by mass, more preferably 80 - 100% by mass, still more preferably 90 - 100% by mass.

The acrylic urethane-based resin (U1) used in one embodiment of the present invention is obtained by mixing a urethane prepolymer (UP) and a vinyl compound containing (meth)acrylic acid ester and polymerizing both.

In the polymerization, it is preferable to further add a radical initiator.

In the acrylic urethane resin (U1) used in one embodiment of the present invention, the content ratio of the structural unit (u11) derived from the urethane prepolymer (UP) and the structural unit (u12) derived from the vinyl compound [(u11)/( u12)], in mass ratio, is preferably 10/90 to 80/20, more preferably 20/80 to 70/30, even more preferably 30/70 to 60/40, still more preferably 35/65 ~ 55/45.

(olefin resin)

As the olefin-based resin suitable as the resin contained in the resin composition (y), it is a polymer having at least a structural unit derived from an olefin monomer.

As said olefin monomer, C2-C8 alpha-olefin is preferable, and ethylene, propylene, butylene, isobutylene, 1-hexene etc. are mentioned specifically,.

Among these, ethylene and propylene are preferred.

Specific examples of the olefin-based resin include ultra-low density polyethylene (VLDPE, density: 880 kg/m 3 or more and less than 910 kg/m 3), low-density polyethylene (LDPE, density: 910 kg/m 3 or more and less than 915 kg/m 3), medium-density polyethylene polyethylene resins such as (MDPE, density: 915 kg/m 3 or more and less than 942 kg/m 3 ), high-density polyethylene (HDPE, density: 942 kg/m 3 or more), and linear low-density polyethylene; polypropylene resin (PP); polybutene resin (PB); ethylene-propylene copolymer; olefinic elastomers (TPO); poly(4-methyl-1-pentene) (PMP); ethylene-vinyl acetate copolymer (EVA); ethylene-vinyl alcohol copolymer (EVOH); olefin-based terpolymers such as ethylene-propylene-(5-ethylidene-2-norbornene); etc. can be mentioned.

In one aspect of the present invention, the olefin-based resin may be a modified olefin-based resin further subjected to at least one type of modification selected from acid modification, hydroxyl group modification, and acrylic modification.

For example, as an acid-modified olefin-based resin obtained by acid-modifying an olefin-based resin, a modified polymer obtained by graft-polymerizing an unsaturated carboxylic acid or an anhydride thereof with the above-described unmodified olefin-based resin is exemplified. .

Examples of the unsaturated carboxylic acids or anhydrides thereof include maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, tetrahydrophthalic acid, aconitic acid, (meth)acrylic acid, maleic anhydride, and itaconic anhydride. , glutaconic acid anhydride, citraconic acid anhydride, aconitic acid anhydride, norbornenedicarboxylic acid anhydride, tetrahydrophthalic acid anhydride, and the like.

Moreover, an unsaturated carboxylic acid or its anhydride may be used independently, and may use 2 or more types together.

Examples of the acrylic-modified olefin-based resin obtained by performing acrylic modification on the olefin-based resin include a modified polymer formed by graft polymerization of an alkyl (meth)acrylate as a side chain to the above-described unmodified olefin-based resin as a main chain.

As carbon number of the alkyl group which said alkyl (meth)acrylate has, Preferably it is 1-20, More preferably, it is 1-16, More preferably, it is 1-12.

As said alkyl (meth)acrylate, the thing similar to the compound which can be selected as a monomer (a1') mentioned later is mentioned, for example.

Examples of the hydroxyl-modified olefin-based resin obtained by subjecting the olefin-based resin to hydroxyl-modification include a modified polymer formed by graft polymerization of a hydroxyl-containing compound onto the above-described unmodified olefin-based resin as a main chain.

Examples of the hydroxyl group-containing compound include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl ( hydroxyalkyl (meth)acrylates such as meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; and unsaturated alcohols such as vinyl alcohol and allyl alcohol.

(Resin other than acrylic urethane resin and olefin resin)

In one aspect of the present invention, the resin composition (y) may contain resins other than acrylic urethane resins and olefin resins within a range not impairing the effects of the present invention.

Examples of such resins include vinyl resins such as polyvinyl chloride, polyvinylidene chloride, and polyvinyl alcohol; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polystyrene; acrylonitrile-butadiene-styrene copolymer; cellulose triacetate; polycarbonate; polyurethane not applicable to acrylic urethane resins; polysulfone; polyether ether ketone; polyethersulfone; polyphenylene sulfide; polyimide-based resins such as polyetherimide and polyimide; polyamide-based resin; acrylic resin; A fluorine-type resin etc. are mentioned.

However, from the viewpoint of forming a thermally expandable substrate that satisfies the above requirements (1) and (2), it is preferable that the content ratio of resins other than the acrylic urethane-based resin and the olefin-based resin in the resin composition (y) is small.

The content ratio of the resin other than the acrylic urethane resin and the olefin resin is preferably less than 30 parts by mass, more preferably less than 20 parts by mass, more preferably less than 20 parts by mass relative to 100 parts by mass of the total amount of the resin contained in the resin composition (y). It is preferably less than 10 parts by mass, more preferably less than 5 parts by mass, still more preferably less than 1 part by mass.

<thermal expansible particles>

The heat-expandable particles used in the present invention may be particles having an expansion start temperature (t) adjusted to 120 to 250°C, and are appropriately selected depending on the intended use.

In addition, in this specification, the expansion start temperature (t) of thermally expansible particle|grains means the value measured based on the following method.

[Measurement method of expansion onset temperature (t) of thermally expansible particles]

In an aluminum cup with a diameter of 6.0 mm (inner diameter: 5.65 mm) and a depth of 4.8 mm, 0.5 mg of thermally expandable particles to be measured were added, and an aluminum lid (diameter: 5.6 mm, thickness: 0.1 mm) was placed on the sample to prepare a sample. do.

Using a dynamic viscoelasticity measuring device, the height of the sample is measured in a state where a force of 0.01 N is applied to the sample from the top of the aluminum lid with a presser. Then, with a force of 0.01 N applied to the presser, heating from 20 ° C to 300 ° C at a heating rate of 10 ° C / min, measuring the amount of displacement in the vertical direction of the presser, and starting the displacement in the positive direction. Let it be the temperature (t).

The thermally expandable particles are preferably microencapsulated foaming agents composed of an outer shell made of a thermoplastic resin and an encapsulated component that is enclosed in the outer shell and vaporizes when heated to a predetermined temperature.

Examples of the thermoplastic resin constituting the outer shell of the microencapsulation foaming agent include vinylidene chloride-acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyacrylonitrile, and polyvinylidene chloride. , polysulfone, and the like.

As the contained component enclosed in the outer shell, for example, propane, butane, pentane, hexane, heptane, octane, nonane, decane, isobutane, isopentane, isohexane, isoheptane, isooctane, isononane, isodecane, cyclopropane , cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, neopentane, dodecane, isododecane, cyclotridecane, hexyl cyclohexane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octa Decane, nonadecane, isotridecane, 4-methyl dodecane, isotetradecane, isopentadecane, isohexadecane, 2, 2, 4, 4, 6, 8, 8-heptamethyl nonane, isoheptadecane, iso Octadecane, isononadecane, 2, 6, 10, 14-tetramethyl pentadecane, cyclotridecane, heptyl cyclohexane, n-octyl cyclohexane, cyclopentadecane, nonyl cyclohexane, decylcyclohexane, pentadecyl cyclo Hexane, hexadecyl cyclohexane, heptadecyl cyclohexane, octadecyl cyclohexane, etc. are mentioned.

These encapsulation components may be used independently or may use 2 or more types together.

The expansion start temperature (t) of the heat-expandable particles can be adjusted by appropriately selecting the type of encapsulated component.

The average particle diameter of the heat-expandable particles used in one embodiment of the present invention before expansion at 23°C is preferably 3 to 100 μm, more preferably 4 to 70 μm, even more preferably 6 to 60 μm, still more preferably 10 to 50 μm.

In addition, the average particle diameter of thermally expansible particles before expansion is the volume median particle diameter (D ₅₀ ), measured using a laser diffraction type particle size distribution analyzer (for example, manufactured by Malvern, product name “MASTERSIZER 3000”) before expansion. In the particle distribution of the thermally expandable particles, it means a particle size corresponding to 50% of the cumulative volume frequency calculated as the particle size of the thermally expandable particles before expansion is smaller.

The 90% particle diameter (D ₉₀ ) of the thermally expandable particles used in one embodiment of the present invention before expansion at 23°C is preferably 10 to 150 μm, more preferably 20 to 100 μm, still more preferably 25 to 90 μm, More preferably, it is 30-80 micrometers.

In addition, the 90% particle diameter (D ₉₀ ) of the thermally expandable particles before expansion is the value of the thermally expandable particles before expansion, measured using a laser diffraction type particle size distribution analyzer (for example, manufactured by Malvern, product name “MASTERSIZER 3000”). In the particle distribution, it means a particle size corresponding to 90% of the cumulative volume frequency calculated as the particle size of the thermally expandable particles before expansion is smaller.

The maximum volume expansion rate of the heat-expandable particles used in one embodiment of the present invention when heated to a temperature equal to or higher than the expansion start temperature (t) is preferably 1.5 to 100 times, more preferably 2 to 80 times, still more preferably is 2.5 to 60 times, more preferably 3 to 40 times.

The content of the heat-expandable particles is preferably 1 to 40% by mass, more preferably 5 to 35% by mass, still more preferably 10 to 35% by mass, based on the total amount (100% by mass) of the active ingredients of the resin composition (y). 30% by mass, more preferably 15 to 25% by mass.

<Additives for Substrate>

The resin composition (y) used in one embodiment of the present invention may contain a base material additive included in a base material of a typical pressure-sensitive adhesive sheet within a range not impairing the effects of the present invention.

Examples of such additives for substrates include ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, slip agents, antiblocking agents, colorants and the like.

In addition, these additives for base materials may be used independently, respectively, or may use 2 or more types together.

When such an additive for substrate is contained, the content of each additive for substrate is preferably 0.0001 to 20 parts by mass, more preferably 0.001 to 10 parts by mass, based on 100 parts by mass of the resin in the resin composition (y). am.

<Non-solvent type resin composition (y1)>

As the resin composition (y) used in one embodiment of the present invention, from the viewpoint of forming a thermally expandable substrate satisfying the above requirements (1) and (2), a mass average molecular weight (Mw) having an ethylenically unsaturated group of 50000 or less and a non-solvent type resin composition (y1) obtained by blending an oligomer, an energy ray polymerizable monomer, and the above-described heat-expandable particles and containing no solvent.

In the non-solvent type resin composition (y1), although no solvent is blended, the energy ray polymerizable monomer contributes to the improvement of the plasticity of the oligomer.

A thermally expandable base material satisfying the above requirements (1) and (2) is easily formed by irradiating energy rays to a coating film formed of the non-solvent type resin composition (y1).

The type, shape, and amount (content) of the heat-expandable particles blended in the non-solvent type resin composition (y1) are as described above.

The mass average molecular weight (Mw) of the oligomer contained in the non-solvent type resin composition (y1) is 50000 or less, but is preferably 1000 to 50000, more preferably 2000 to 40000, still more preferably 3000 to 35000, still more preferably It is 4000 to 30000.

In addition, as said oligomer, among the resins contained in the above-mentioned resin composition (y), what is necessary is just to have an ethylenically unsaturated group whose mass average molecular weight is 50000 or less, but the above-mentioned urethane prepolymer (UP) is preferable.

Moreover, as said oligomer, the modified olefin resin which has an ethylenically unsaturated group can also be used.

The total content of the oligomer and the energy ray polymerizable monomer in the non-solvent type resin composition (y1) is preferably 50 to 99% by mass relative to the total amount (100% by mass) of the non-solvent type resin composition (y1); It is more preferably 60 to 95% by mass, still more preferably 65 to 90% by mass, still more preferably 70 to 85% by mass.

Examples of the energy ray polymerizable monomer include isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxy (meth)acrylate, and cyclopentyloxy (meth)acrylate. alicyclic polymerizable compounds such as hexyl (meth)acrylate, adamantane (meth)acrylate, and tricyclodecane acrylate; aromatic polymerizable compounds such as phenyl hydroxypropyl acrylate, benzyl acrylate, and phenol ethylene oxide-modified acrylate; and heterocyclic polymerizable compounds such as tetrahydrofurfuryl (meth)acrylate, morpholine acrylate, N-vinylpyrrolidone, and N-vinyl caprolactam.

These energy ray polymerizable monomers may be used alone or in combination of two or more.

The content ratio of the oligomer and the energy ray polymerizable monomer in the non-solvent type resin composition (y1) [oligomer/energy ray polymerizable monomer] is a mass ratio, preferably 20/80 to 90/10, more preferably is 30/70 to 85/15, more preferably 35/65 to 80/20.

In one aspect of the present invention, it is preferable that the non-solvent type resin composition (y1) further contains a photopolymerization initiator.

By containing a photopolymerization initiator, the curing reaction can be sufficiently advanced even by irradiation with relatively low-energy energy rays.

As the photopolymerization initiator, for example, 1-hydroxy-cyclohexyl-phenyl-ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzylphenyl sulfide, tetramethylthiuram monosulfide, azo Bisisobutyronitrile, dibenzyl, diacetyl, 8-chloroanthraquinone, etc. are mentioned.

These photopolymerization initiators may be used alone or in combination of two or more.

The compounding amount of the photopolymerization initiator is preferably from 0.01 to 5 parts by mass, more preferably from 0.01 to 4 parts by mass, still more preferably from 0.02 to 3 parts by mass, based on the total amount (100 parts by mass) of the oligomer and energy ray polymerizable monomer. is the mass part.

[Adhesive Layer]

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of one embodiment of the present invention may contain a pressure-sensitive adhesive resin, and may contain additives for pressure-sensitive adhesive such as a crosslinking agent, a tackifier, a polymerizable compound, and a polymerization initiator, if necessary.

Further, from the viewpoint of preventing an object, such as a semiconductor chip, from being deposited on the pressure-sensitive adhesive layer by heating in the sealing step, the pressure-sensitive adhesive layer included in the pressure-sensitive adhesive sheet of one embodiment of the present invention is a non-thermal-expandable pressure-sensitive adhesive layer. It is preferable.

In one embodiment of the present invention, the adhesive force on the adhesive surface of the pressure-sensitive adhesive layer on which an object such as a semiconductor chip is mounted at 23°C before expansion of the thermally expandable particles is preferably 0.1 to 10.0 N/25 mm, more preferably 0.2 - 8.0 N/25 mm, more preferably 0.4 - 6.0 N/25 mm, still more preferably 0.5 - 4.0 N/25 mm.

If the adhesive force is 0.1 N/25 mm or more, adherends such as semiconductor chips can be sufficiently fixed to the extent that displacement can be prevented in subsequent steps such as a sealing step.

On the other hand, if the adhesive force is 10.0 N / 25 mm or less, at the time of peeling, it can be easily peeled with weak force by heating to a temperature equal to or higher than the expansion start temperature (t).

In addition, the above adhesive force means a value measured according to the method described in the Examples.

In the pressure-sensitive adhesive sheet of one embodiment of the present invention, the storage shear modulus (G') 23 of the pressure-sensitive adhesive layer on which objects such as semiconductor chips are mounted at 23°C is preferably 1.0×10 ⁴ to 1.0×10 ⁸ Pa; More preferably, it is 5.0×10 ⁴ to 5.0×10 ⁷ Pa, and still more preferably 1.0×10 ⁵ to 1.0×10 ⁷ Pa.

When the storage shear modulus (G′) 23 of the pressure-sensitive adhesive layer is 1.0 × 10 ⁴ Pa or more, positional displacement when attaching an object such as a semiconductor chip can be prevented, and furthermore, to the pressure-sensitive adhesive layer at this time Excessive sedimentation can be prevented.

On the other hand, when the storage shear modulus (G′) 23 of the pressure-sensitive adhesive layer is 1.0 × 10 ⁸ Pa or less, it is easily deformed by heating to a temperature equal to or higher than the expansion start temperature (t) during peeling, and thermal expansion in the thermally expandable substrate Irregularities are easily formed on the surface of the pressure-sensitive adhesive layer due to the expansion of the sticky particles, and as a result, it can be easily peeled off with a weak force.

Also, in the present specification, the storage shear modulus (G′) 23 of the pressure-sensitive adhesive layer means a value measured according to the method described in Examples.

In the case of a pressure-sensitive adhesive sheet having a plurality of pressure-sensitive adhesive layers, such as the double-sided pressure-sensitive adhesive sheets 2a and 2b shown in FIG. 2, the storage shear modulus (G') of the pressure-sensitive adhesive layer on which an object such as a semiconductor chip is mounted ) (23) is preferably within the above range.

On the other hand, in order to fix the PSA sheet, the storage shear modulus (G′) 23 of the PSA layer on the side to be attached to the support or the like at 23° C. is preferably 1.0 × 10 from the viewpoint of improving adhesion to the support or the like. ⁴ to 1.0 × 10 ⁸ Pa, more preferably 3.0 × 10 ⁴ to 5.0 × 10 ⁷ Pa, still more preferably 5.0 × 10 ⁴ to 1.0 × 10 ⁷ Pa.

The thickness of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of one embodiment of the present invention is determined from the viewpoint of expressing excellent adhesive strength and from the viewpoint of forming irregularities on the surface of the pressure-sensitive adhesive layer formed by expansion of the thermally expandable particles in the thermally expandable substrate by heat treatment. From the viewpoint of ease, it is preferably 1 to 60 μm, more preferably 2 to 50 μm, even more preferably 3 to 40 μm, still more preferably 5 to 30 μm.

In the PSA sheet of one embodiment of the present invention, the ratio of the thickness of the thermally expandable substrate to the thickness of the adhesive layer at 23°C [thermal expandable substrate/adhesive layer] is the ratio of the thickness of the thermally expandable substrate/adhesive layer to the object side after sealing in the sealing process such as the manufacturing process of FOWLP. It is preferably 0.2 or more, more preferably 0.5 or more, even more preferably 1.0 or more, still more preferably 5.0 or more, from the viewpoint of flattening the surface and preventing the object from being displaced. It is preferably 1000 or less, more preferably 200 or less, still more preferably 60 or less, still more preferably 30 or less, from the viewpoint of obtaining a pressure-sensitive adhesive sheet that can be easily peeled off with weak force at times.

In addition, in the present specification, in the case of a PSA sheet having a plurality of PSA layers, such as the double-sided PSA sheets 2a and 2b shown in FIG. 2, the above "thickness of PSA layer" means the thickness of each PSA layer. do. That is, for each pressure-sensitive adhesive layer, it is preferable that the thickness and the ratio [heat-expandable substrate/pressure-sensitive adhesive layer] fall within the above range.

In addition, the thickness of the pressure-sensitive adhesive layer means a value measured according to the method described in Examples.

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of one embodiment of the present invention may be formed of a pressure-sensitive adhesive composition containing a pressure-sensitive adhesive resin.

In addition, in a PSA sheet having a plurality of PSA layers, such as the double-sided PSA sheets 2a and 2b shown in FIG. 2, each PSA layer may be formed from the same PSA composition or may be formed from different PSA compositions.

Hereinafter, each component contained in the pressure-sensitive adhesive composition, which is a forming material of the pressure-sensitive adhesive layer, will be described.

<adhesive resin>

As the adhesive resin used in one embodiment of the present invention, the resin alone may have adhesiveness and a polymer having a mass average molecular weight (Mw) of 10,000 or more.

The mass average molecular weight (Mw) of the adhesive resin used in one embodiment of the present invention is preferably 10,000 to 2,000,000, more preferably 20,000 to 1,500,000, still more preferably 3, from the viewpoint of improving adhesive strength. ten thousand to one million

Specific examples of the adhesive resin include rubber-based resins such as acrylic resins, urethane-based resins, and polyisobutylene-based resins, polyester-based resins, olefin-based resins, silicone-based resins, and polyvinyl ether-based resins.

These adhesive resins may be used independently or may use 2 or more types together.

In addition, when such an adhesive resin is a copolymer having two or more types of structural units, the form of the copolymer is not particularly limited, and may be any of block copolymers, random copolymers, and graft copolymers.

The adhesive resin used in one embodiment of the present invention may be an energy ray curable adhesive resin obtained by introducing a polymerizable functional group into the side chain of the above adhesive resin.

As said polymerizable functional group, a (meth)acryloyl group, a vinyl group, etc. are mentioned.

Moreover, although an ultraviolet-ray or an electron beam can be mentioned as an energy-beam, an ultraviolet-ray is preferable.

The content of the adhesive resin is preferably 30 to 99.99% by mass, more preferably 40 to 99.95% by mass, still more preferably 50 to 99.90% by mass, based on the total amount (100% by mass) of the active ingredients of the pressure-sensitive adhesive composition. More preferably, it is 55 to 99.80% by mass, and still more preferably 60 to 99.50% by mass.

In addition, in the following description of this specification, "the content of each component with respect to the total amount of the active ingredient of the adhesive composition" is synonymous with "the content of each component in the adhesive layer formed from the said adhesive composition."

In one embodiment of the present invention, from the viewpoint of exhibiting excellent adhesive strength and from the viewpoint of facilitating the formation of irregularities on the surface of the pressure-sensitive adhesive layer formed by the expansion of thermally expandable particles in the thermally expandable substrate by heat treatment, the adhesive resin is an acrylic resin. It is preferable to include resin.

The content ratio of the acrylic resin in the adhesive resin is preferably 30 to 100% by mass, more preferably 50 to 100% by mass, and even more preferably 50 to 100% by mass relative to the total amount (100% by mass) of the adhesive resin contained in the adhesive composition. 70 to 100% by mass, more preferably 85 to 100% by mass.

(Acrylic resin)

In one embodiment of the present invention, as the acrylic resin that can be used as the adhesive resin, for example, a polymer containing a structural unit derived from an alkyl (meth)acrylate having a linear or branched chain alkyl group, or a cyclic structure The polymer etc. which contain the structural unit derived from branched (meth)acrylate are mentioned.

The mass average molecular weight (Mw) of the acrylic resin is preferably 100,000 to 1.5 million, more preferably 200,000 to 1.3 million, still more preferably 350,000 to 1.2 million, still more preferably 500,000 to 1.1 million. .

As the acrylic resin used in one embodiment of the present invention, a structural unit (a1) derived from an alkyl (meth)acrylate (a1') (hereinafter also referred to as "monomer (a1')") and a functional group-containing monomer (a2') ) (hereinafter also referred to as "monomer (a2')"), an acrylic copolymer (A1) having a structural unit (a2) derived from is more preferable.

The number of carbon atoms in the alkyl group of the monomer (a1') is preferably 1 to 24, more preferably 1 to 12, still more preferably 2 to 10, still more preferably 4 to 8, from the viewpoint of improving the adhesive properties. am.

In addition, the alkyl group of the monomer (a1') may be a straight-chain alkyl group or a branched-chain alkyl group.

Examples of the monomer (a1') include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and Uryl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, etc. are mentioned.

These monomers (a1') may be used alone or in combination of two or more.

As the monomer (a1'), butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate are preferable.

The content of the structural unit (a1) is preferably 50 to 99.9% by mass, more preferably 60 to 99.0% by mass, and still more preferably 60 to 99.0% by mass, relative to the precursor unit (100% by mass) of the acrylic copolymer (A1). 70 to 97.0% by mass, more preferably 80 to 95.0% by mass.

As a functional group which a monomer (a2') has, a hydroxyl group, a carboxyl group, an amino group, an epoxy group etc. are mentioned, for example.

That is, as a monomer (a2'), a hydroxyl-containing monomer, a carboxyl-containing monomer, an amino-group-containing monomer, an epoxy-group-containing monomer etc. are mentioned, for example.

These monomers (a2') may be used alone or in combination of two or more.

Among these, as a monomer (a2'), a hydroxyl group-containing monomer and a carboxyl group-containing monomer are preferable.

As a hydroxyl group-containing monomer, the same thing as the above-mentioned hydroxyl group-containing compound is mentioned, for example.

Examples of the carboxyl group-containing monomer include ethylenically unsaturated monocarboxylic acids such as (meth)acrylic acid and crotonic acid; ethylenically unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, maleic acid and citraconic acid and their anhydrides, 2-(acryloyloxy)ethyl succinate, 2-carboxyethyl (meth)acrylate, and the like. .

The content of the structural unit (a2) is preferably 0.1 to 40% by mass, more preferably 0.5 to 35% by mass, and still more preferably 0.5 to 35% by mass, relative to the precursor unit (100% by mass) of the acrylic copolymer (A1). 1.0 to 30% by mass, more preferably 3.0 to 25% by mass.

The acrylic copolymer (A1) may further have a structural unit (a3) derived from a monomer (a3') other than the monomers (a1') and (a2').

In addition, in the acrylic copolymer (A1), the content of the structural units (a1) and (a2) is preferably 70 to 100% by mass relative to the precursor unit (100% by mass) of the acrylic copolymer (A1). It is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, and still more preferably 95 to 100% by mass.

Examples of the monomer (a3') include olefins such as ethylene, propylene, and isobutylene; halogenated olefins such as vinyl chloride and vinylidene chloride; diene monomers such as butadiene, isoprene, and chloroprene; Cyclohexyl (meth)acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth) ) (meth)acrylates having a cyclic structure such as acrylate and imide (meth)acrylate; Styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, (meth)acrylamide, (meth)acrylonitrile, (meth)acryloylmorpholine, N-vinylpyrrolidone, etc. can

In addition, the acrylic copolymer (A1) may be an energy ray curable acrylic copolymer having a polymerizable functional group introduced into the side chain.

The polymerizable functional group and the energy ray are as described above.

In addition, the polymerizable functional group is a compound having a polymerizable functional group and a substituent capable of bonding with the functional group of the acrylic copolymer having the above-described structural units (a1) and (a2) and the structural unit (a2) of the acrylic copolymer. It can be introduced by reacting.

As said compound, (meth)acryloyloxyethyl isocyanate, (meth)acryloyl isocyanate, glycidyl (meth)acrylate etc. are mentioned, for example.

<Crosslinking agent>

In one aspect of the present invention, when the pressure-sensitive adhesive composition contains an adhesive resin containing a functional group such as the above-mentioned acrylic copolymer (A1), it is preferable to further contain a crosslinking agent.

The crosslinking agent reacts with an adhesive resin having a functional group, and uses the functional group as a crosslinking origin to crosslink the adhesive resins.

As a crosslinking agent, an isocyanate type crosslinking agent, an epoxy type crosslinking agent, an aziridine type crosslinking agent, a metal chelate type crosslinking agent, etc. are mentioned, for example.

These crosslinking agents may be used independently or may use 2 or more types together.

Among these crosslinking agents, isocyanate-based crosslinking agents are preferable from the viewpoint of increasing cohesive force and improving adhesive force, and from viewpoints such as ease of availability.

The content of the crosslinking agent is appropriately adjusted according to the number of functional groups the adhesive resin has, but is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and still more preferably 0.03 to 7 parts by mass, based on 100 parts by mass of the adhesive resin having a functional group. Preferably, it is 0.05 to 5 parts by mass.

<Tackifier>

In one aspect of the present invention, the pressure-sensitive adhesive composition may further contain a tackifier from the viewpoint of further improving the adhesive force.

In this specification, "tackifier" refers to an oligomer having a mass average molecular weight (Mw) of less than 10,000 as a component that supplementally improves the adhesive strength of the above-mentioned adhesive resin, and is distinguished from the above-mentioned adhesive resin.

The mass average molecular weight (Mw) of the tackifier is preferably 400 to 10000, more preferably 500 to 8000, still more preferably 800 to 5000.

Examples of the tackifier include rosin-based resins, terpene-based resins, styrene-based resins, and C5 fractions such as pentene, isoprene, piperine, and 1,3-pentadiene produced by thermal decomposition of petroleum naphtha. C5-based petroleum resins obtained by copolymerization, C9-based petroleum resins obtained by copolymerizing C9 fractions such as indene and vinyltoluene produced by thermal decomposition of petroleum naphtha, and hydrogenated resins obtained by hydrogenating these.

The softening point of the tackifier is preferably 60 to 170°C, more preferably 65 to 160°C, still more preferably 70 to 150°C.

In addition, in this specification, the "softening point" of a tackifier means the value measured based on JIS　K　2531.

Tackifiers may be used alone or in combination of two or more with different softening points or structures.

And, when using a plurality of tackifiers of two or more types, it is preferable that the weighted average of the softening points of the plurality of tackifiers falls within the above range.

The content of the tackifier is preferably 0.01 to 65% by mass, more preferably 0.05 to 55% by mass, still more preferably 0.1 to 50% by mass, based on the total amount (100% by mass) of the active ingredients of the pressure-sensitive adhesive composition. , more preferably from 0.5 to 45% by mass, still more preferably from 1.0 to 40% by mass.

<Photoinitiator>

In one aspect of the present invention, when the pressure-sensitive adhesive composition contains an energy ray curable pressure-sensitive adhesive resin as the pressure-sensitive adhesive resin, it is preferable to further contain a photopolymerization initiator.

By using the pressure-sensitive adhesive composition containing an energy ray-curable pressure-sensitive adhesive resin and a photopolymerization initiator, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition can sufficiently advance the curing reaction even when irradiated with relatively low-energy energy rays, and can adjust the adhesive force to a desired range. there will be

Examples of the photopolymerization initiator used in one embodiment of the present invention include those that are incorporated into the above-described non-solvent type resin composition (y1).

The content of the photopolymerization initiator is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 5 parts by mass, still more preferably 0.05 to 2 parts by mass with respect to 100 parts by mass of the energy ray curable adhesive resin.

<Additive for adhesive>

In one aspect of the present invention, the pressure-sensitive adhesive composition, which is a material for forming the pressure-sensitive adhesive layer, may contain, in addition to the above-mentioned additives, additives for pressure-sensitive adhesives used in general pressure-sensitive adhesives within a range that does not impair the effects of the present invention.

Examples of such additives for pressure-sensitive adhesives include antioxidants, softeners (plasticizers), rust inhibitors, pigments, dyes, retarders, reaction accelerators (catalysts), and ultraviolet absorbers.

In addition, these additives for adhesives may be used independently, respectively, and may use 2 or more types together.

When such additives for adhesives are contained, the content of each additive for adhesives is preferably 0.0001 to 20 parts by mass, more preferably 0.001 to 10 parts by mass with respect to 100 parts by mass of the adhesive resin.

The pressure-sensitive adhesive composition, which is a material for forming the pressure-sensitive adhesive layer, may contain thermally expandable particles within a range that does not impair the effects of the present invention.

However, as described above, it is preferable that the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of one embodiment of the present invention is a non-heat-expandable pressure-sensitive adhesive layer. For this reason, the adhesive composition which is a forming material of the said adhesive layer is so preferable that content of thermally expandable particle|grains is very small.

The content of the heat-expandable particles is preferably less than 5% by mass, more preferably less than 1% by mass, still more preferably less than 0.1% by mass, still more preferably less than 0.1% by mass, based on the total amount (100% by mass) of the active ingredients of the pressure-sensitive adhesive composition. It is preferably less than 0.01% by mass, particularly preferably less than 0.001% by mass.

[release material]

Like the PSA sheet 1b in FIG. 1(b) and the PSA sheet 2b in FIG. 2(b), the PSA sheet of one embodiment of the present invention may further have a release material on the sticking surface of the PSA layer.

In addition, in the case of the PSA sheet having two PSA layers, such as PSA sheet 2b in FIG. 2(B), the two release materials provided on the sticking surface of each PSA layer are adjusted so that the difference in peeling force is different. it is desirable that

As the release material, a release sheet subjected to a double-sided release process, a release sheet subjected to a single-side release process, or the like is used, and a release agent coated on a base material for the release material is exemplified.

Examples of the base material for the release material include paper such as high-quality paper, glassine paper, and kraft paper; plastic films, such as polyester resin films, such as polyethylene terephthalate resin, polybutylene terephthalate resin, and polyethylene naphthalate resin, and olefin resin films, such as polypropylene resin and polyethylene resin; etc. can be mentioned.

Examples of the release agent include rubber-based elastomers such as silicone-based resins, olefin-based resins, isoprene-based resins, and butadiene-based resins, long-chain alkyl-based resins, alkyd-based resins, and fluorine-based resins.

The thickness of the release material is not particularly limited, but is preferably 10 to 200 μm, more preferably 25 to 170 μm, still more preferably 35 to 80 μm.

[Method for Producing Adhesive Sheet]

The manufacturing method of the adhesive sheet of this invention is not specifically limited, The manufacturing method (a) which has the following steps (1a) and (2a) is mentioned.

Step (1a): A step of forming a coating film by applying a resin composition (y), which is a material for forming a thermally expandable substrate, onto the release-treated surface of a release material, and drying or UV irradiating the coating film to form a thermally expandable substrate.

Step (2a): A step of applying an adhesive composition, which is a material for forming an adhesive layer, onto the surface of the formed heat-expandable substrate to form a coating film, and drying the coating film to form an adhesive layer.

Moreover, as another manufacturing method of the adhesive sheet of this invention, the manufacturing method (b) which has the following steps (1b) - (3b) is mentioned.

Step (1b): A step of forming a coating film by applying the resin composition (y), which is a material for forming a thermally expandable substrate, onto the release-treated surface of the release material, and drying the coating film to form the thermally expandable substrate.

- Step (2b): A step of applying an adhesive composition, which is a forming material of an adhesive layer, to the release treated surface of the release material to form a coating film, and drying the coating film to form an adhesive layer.

Step (3b): A step of bonding the surface of the heat-expandable base material formed in step (1b) and the surface of the pressure-sensitive adhesive layer formed in step (2b).

In the above production methods (a) and (b), the resin composition (y) and the pressure-sensitive adhesive composition may be in the form of a solution by further blending a diluting solvent.

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

Further, in the step (1a) of the production method (a) and the step (1b) of the production method (b), in the drying process of forming the thermally expandable substrate from the coating film, from the viewpoint of preventing expansion of the thermally expandable particles, the drying temperature is preferably carried out below the expansion initiation temperature (t) of the thermally expandable particles.

[Use of PSA Sheet of the Present Invention, Method for Using PSA Sheet]

The pressure-sensitive adhesive sheet of the present invention can be easily peeled off with a weak force while suppressing sedimentation of the object during heating when the object is temporarily fixed.

For this reason, the PSA sheet of the present invention is preferably used in a sealing process involving heating using an encapsulating resin, and specifically, it is preferably used in a sealing process when producing FOWLP.

In the encapsulating step for producing FOWLP, after placing a semiconductor chip on the adhesive surface of the adhesive layer of the pressure-sensitive adhesive sheet of the present invention, the upper surface and adhesive surface of the semiconductor chip are covered with an encapsulating resin, and the encapsulating resin is heated. Heat cured and sealed.

At this time, when a general PSA sheet is used, the elastic modulus of each layer constituting the PSA sheet decreases due to heating in the sealing step, and the mounted semiconductor chips sink toward the PSA sheet side.

On the other hand, since the PSA sheet of the present invention satisfies the above requirement (1), it effectively suppresses sedimentation of semiconductor chips toward the PSA sheet side, which may occur in the sealing step, and flattens the surface of the semiconductor chip side after sealing. In addition to being able to do so, it is possible to suppress the occurrence of misalignment of the semiconductor chip.

As the encapsulating resin, any one can be appropriately selected and used from among those used as semiconductor encapsulating materials, and examples thereof include thermosetting resins and those containing energy ray curable resins.

In addition, the form of the encapsulating resin may be solid at room temperature, such as granular or film, or may be a liquid with fluidity like a composition, but from the viewpoint of workability, a film-like material is preferable.

As a method of coating a semiconductor chip and its peripheral portion using an encapsulating resin, it can be appropriately selected and applied according to the type of encapsulant from among methods conventionally applied to the semiconductor encapsulation process, and for example, a roll lamination method, A vacuum press method, a vacuum lamination method, a spin coat method, a die coat method, a transfer molding method, a compression molding method, and the like can be applied.

Further, the sealing step is preferably performed under a temperature condition lower than the expansion start temperature (t) of the thermally expandable particles.

In addition, although the coating treatment of the encapsulating resin and the heat curing treatment may be performed separately, when the encapsulating resin is heated in the coating treatment, even if the encapsulant is cured as it is by the heating and the coating treatment and the thermal curing treatment are performed simultaneously. good night.

On the other hand, after the sealing process is completed, the pressure-sensitive adhesive sheet can be easily peeled off with a weak force by heating to a temperature equal to or higher than the expansion start temperature (t).

The "temperature above the expansion start temperature (t)" at the time of peeling the adhesive sheet is preferably "expansion start temperature (t) + 10°C" or more and "expansion start temperature (t) + 60°C" or less, and "expansion start temperature ( It is more preferable that it is more than "t) + 15 degreeC" and "expansion start temperature (t) + 40 degreeC" or less.

Further, from the above characteristics of the PSA sheet of the present invention, the present invention can also provide a method of using the PSA sheet according to [1] below.

[1] A method of using a pressure-sensitive adhesive sheet in which the above-described pressure-sensitive adhesive sheet of the present invention is applied to an adherend, and then the pressure-sensitive adhesive sheet is peeled from the adherend by heat treatment at a temperature equal to or higher than the expansion start temperature (t).

In addition, it is preferable that the said usage method be used in the sealing process involving the use of sealing resin and heating.

Example

In the present invention, the following examples will be specifically described, but the present invention is not limited to the following examples. In addition, the physical property values in the following production examples and examples are values measured according to the following method.

<Mass average molecular weight (Mw)>

It was measured under the following conditions using a gel permeation chromatography apparatus (manufactured by TOSOH CORPORATION, product name "HLC-8020"), and the value measured in terms of standard polystyrene was used.

(Measuring conditions)

・Column: "TSK" guard "column" HXL-L" "TSK" gel "G2500HXL" "TSK" gel "G2000HXL" "TSK" gel "G1000HXL" (all manufactured by TOSOH CORPORATION) connected sequentially

Column temperature: 40℃

Developing solvent: tetrahydrofuran

・Flow rate: 1.0mL/min

<Measurement of the thickness of each layer>

It was measured using a static pressure thickness meter manufactured by TECLOCK (product number: "PG-02J", standard specifications: based on JIS K6783, Z1702, Z1709).

<Average particle diameter (D ₅₀ ), 90% particle diameter (D ₉₀ ) of thermally expandable particles>

The particle distribution of the thermally expandable particles before expansion was measured at 23°C using a laser diffraction type particle size distribution analyzer (eg, manufactured by Malvern, product name "MASTERSIZER 3000").

Then, the particle diameters corresponding to 50% and 90% of the cumulative volume frequencies calculated in the smaller particle size of the particle distribution are respectively “average particle diameter of thermally expandable particles (D ₅₀ )” and “90% particle diameter of thermally expandable particles (D ₉₀ )”.

<Storage modulus (E') of thermally expansible substrate>

When the measurement target was a non-adhesive thermally expandable substrate, the thermally expandable substrate had a size of 5 mm in length x 30 mm in width x 200 µm in thickness, and a release material was removed to obtain a test sample.

Using a dynamic viscoelasticity measuring device (manufactured by TA Instruments, product name "DMAQ800"), under the conditions of a test start temperature of 0°C, a test end temperature of 300°C, a temperature increase rate of 3°C/min, a frequency of 1 Hz, and an amplitude of 20 μm, the predetermined At temperature, the storage modulus (E') of the test sample was measured.

<Storage shear modulus (G') of the pressure-sensitive adhesive layer, storage modulus (E') of the thermally expandable pressure-sensitive adhesive layer>

When the measuring object is a thermally expandable adhesive layer and adhesive layer having adhesiveness, the thermally expandable adhesive layer and the adhesive layer were set to a diameter of 8 mm × a thickness of 3 mm, and a release material was removed to obtain a test sample.

Using a viscoelasticity measuring device (manufactured by Anton Paar, device name "MCR300"), under the conditions of a test start temperature of 0 ° C, a test end temperature of 300 ° C, a temperature increase rate of 3 ° C / min, and a frequency of 1 Hz, according to the torsion shear method, At a predetermined temperature, the storage shear modulus (G') of the test sample was measured.

And the value of the storage elastic modulus (E') was computed from the approximate expression "E'=3G'" based on the value of the measured storage shear elastic modulus (G').

<probe tack value>

After cutting the heat-expandable substrate or heat-expandable pressure-sensitive adhesive layer to be measured into a square with a side of 10 mm, it was allowed to stand for 24 hours in an environment of 23 ° C. and 50% RH (relative humidity), and the peelable film was removed to obtain a test sample. did.

Under the environment of 23 ° C., 50% RH (relative humidity), using a tacking tester (manufactured by NIPPON TOKUSHU SOKKI CO., LTD., product name “NTS-4800”), the peelable film was removed and expressed, of the test sample The probe tack value on the surface was measured based on JIS 　Z0237:1991.

Specifically, a stainless steel probe having a diameter of 5 mm was brought into contact with the surface of the test sample at a contact load of 0.98 N/cm for 1 second, and then the probe was separated from the surface of the test sample at a speed of 10 mm/sec. The force required to release was measured. Then, the measured value was used as the probe tack value of the test sample.

Details of the adhesive resin, additives, heat-expandable particles, and release material used in the formation of each layer in the following production examples are as follows.

<adhesive resin>

・Acrylic copolymer (i): Mw 60, having structural units derived from raw material monomers consisting of 2-ethylhexyl acrylate (2 EHA)/2-hydroxyethyl acrylate (HEA) = 80.0/20.0 (mass ratio) A solution containing only an acrylic copolymer. Dilution solvent: ethyl acetate, solid content concentration: 40% by mass.

Acrylic copolymer (ii): n-butyl acrylate (BA) / methyl methacrylate (MMA) / 2-hydroxyethyl acrylate (HEA) / acrylic acid = 86.0 / 8.0 / 5.0 / 1.0 (mass ratio) A solution containing an acrylic copolymer having a Mw of 600,000 and having constituent units derived from raw material monomers. Dilution solvent: ethyl acetate, solid content concentration: 40% by mass.

＜Additives＞

- Isocyanate crosslinking agent (i): TOSOH CORPORATION product, product name "Coronate L", solid content concentration: 75 mass %.

· Photopolymerization initiator (i): BASF company make, product name "IRGACURE 184", 1-hydroxy-cyclohexyl-phenyl-ketone.

<thermal expansible particles>

- Thermally expandable particles (i): KUREHA CORPORATION, product name "S2640", expansion start temperature (t) = 208 ° C. Average particle diameter (D ₅₀ ) = 24 μm, 90% particle diameter (D ₉₀ ) = 49 μm.

<release material>

- Heavy release film: Product name "SP-PET382150" manufactured by Lintec Corporation, polyethylene terephthalate (PET) film provided with a release agent layer formed of a silicone-based release agent on one side, thickness: 38 µm.

- Light release film: manufactured by LINTEC Corporation, product name "SP-PET381031", PET film provided with a release agent layer formed of a silicone-based release agent on one side, thickness: 38 µm.

Production Example 1 (Formation of the first pressure-sensitive adhesive layer (X-1))

5.0 parts by mass (solid content ratio) of the isocyanate-based crosslinking agent (i) was blended with 100 parts by mass of the solid content of the acrylic copolymer (i) as an adhesive resin, diluted with toluene, and stirred uniformly to obtain a solid content concentration (active ingredient concentration) ) 25% by mass of composition (x-1) was prepared.

And, on the surface of the release agent layer of the heavy release film, the prepared composition (x-1) is applied to form a coating film, and the coating film is dried at 100 ° C. for 60 seconds to obtain a first pressure-sensitive adhesive layer (X-1) having a thickness of 10 μm 1) was formed.

Also, the storage shear modulus (G') 23 of the first pressure-sensitive adhesive layer (X-1) at 23°C was 2.5×10 ⁵ Pa.

Production Example 2 (formation of second pressure-sensitive adhesive layer (X-2))

To 100 parts by mass of the solid content of the acrylic copolymer (ii), which is an adhesive resin, 0.8 parts by mass (solid content ratio) of the isocyanate-based crosslinking agent (i) was blended, diluted with toluene, and stirred uniformly to obtain a solid content concentration (active ingredient) Concentration) A composition (x-2) of 25% by mass was prepared.

And, on the surface of the release agent layer of the easy release film, the prepared composition (x-2) was applied to form a coating film, and the coating film was dried at 100 ° C. for 60 seconds to form a second pressure-sensitive adhesive layer (X-2) having a thickness of 10 μm. 2) was formed.

Also, the storage shear modulus (G') 23 of the second pressure-sensitive adhesive layer (X-2) at 23°C was 9.0×10 ⁴ Pa.

Production Example 3 (Formation of Thermally Expandable Substrate (Y-1))

(1) Preparation of composition (y-1)

A terminal isocyanate urethane prepolymer obtained by reacting an ester type diol with isophorone diisocyanate (IPDI) was reacted with 2-hydroxyethyl acrylate to obtain a bifunctional acrylic urethane oligomer having a mass average molecular weight (Mw) of 5000.

Then, to 40 mass% (solid content ratio) of the acrylic urethane oligomer synthesized above, 40 mass% (solid content ratio) of isobornyl acrylate (IBXA) as an energy ray polymerizable monomer, and 20 phenyl hydroxypropyl acrylate (HPPA) 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF, product name "IRGACURE 184") 2.0 An energy ray curable composition was prepared by further blending parts by mass (solid content ratio) and 0.2 parts by mass (solid content ratio) of a phthalocyanine-based pigment as an additive.

Then, the heat-expandable particle (i) was blended with the energy ray-curable composition to prepare a solvent-free composition (y-1) containing no solvent.

In addition, the content of the thermally expandable particles (i) relative to the total amount (100 mass%) of the composition (y-1) was 20 mass%.

(2) Formation of thermally expandable substrate (Y-1)

The prepared composition (y-1) was applied on the surface of the release agent layer of the easy release film to form a coating film.

Then, using an ultraviolet irradiator (manufactured by EYE GRAPHICS., Ltd., product name "ECS-401 GX") and a high-pressure mercury lamp (manufactured by EYE GRAPHICS., Ltd., product name "H04-L41"), an illuminance of 160 mW/ The coated film was cured by irradiation with ultraviolet rays under conditions of cm 2 and light amount of 500 mJ/cm 2 to form a thermally expandable substrate (Y-1) having a thickness of 50 μm. In addition, said illuminance and light quantity at the time of ultraviolet-ray irradiation are the values measured using the illuminance and photometer (made by EIT, product name "UV"Power"Puck"II").

Production Example 4 (Formation of Thermally Expandable Substrate (Y-2))

(1) Synthesis of Urethane Prepolymer

In a reaction vessel under a nitrogen atmosphere, isophorone diisocyanate (IPDI) is mixed with respect to 100 parts by mass (solid content ratio) of a carbonate-type diol having a mass average molecular weight of 1,000. was blended so as to be 1/1, further adding 160 parts by mass of toluene, and reacting under a nitrogen atmosphere for 6 hours or more at 80°C while stirring until the isocyanate group concentration reached the theoretical amount.

Then, a solution obtained by diluting 1.44 parts by mass (solid content ratio) of 2-hydroxyethyl methacrylate (2-HEMA) with 30 parts by mass of toluene was added, and the mixture was heated at 80°C for 6 minutes until the isocyanate groups at both ends disappeared. It was made to react for more time, and the urethane prepolymer of mass average molecular weight 2.9 million was obtained.

(2) Synthesis of acrylic urethane resin

In a reaction vessel under a nitrogen atmosphere, 100 parts by mass (solid content ratio) of the urethane prepolymer obtained in (1) above, 117 parts by mass (solid content ratio) of methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (2- HEMA) 5.1 mass parts (solid content ratio), 1-thioglycerol 1.1 mass parts (solid content ratio), and 50 mass parts of toluene were added, and it heated up to 105 degreeC, stirring.

Then, in the reaction container, a solution obtained by diluting 2.2 parts by mass (solid content ratio) of a radical initiator (manufactured by Japan Finechem Inc., product name “ABN-E”) with 210 parts by mass of toluene was further added over 4 hours while maintaining at 105°C. Dropped.

It was made to react at 105 degreeC after completion|finish of dripping for 6 hours, and the solution of the acrylic urethane-type resin with a mass average molecular weight of 10.5 million was obtained.

(3) Formation of thermally expandable substrate (Y-2)

Based on 100 parts by mass of the solid content of the solution of the acrylic urethane resin obtained in the above (2), 6.3 parts by mass (solid content ratio) of the isocyanate-based crosslinking agent (i), 1.4 mass parts of dioctyl tin bis(2-ethylhexanoate) as a catalyst Part (solid content ratio) and the heat-expandable particles (i) were blended, diluted with toluene, and stirred uniformly to prepare a composition (y-2) having a solid content concentration (active ingredient concentration) of 30% by mass.

In addition, the content of the heat-expandable particle (i) with respect to the total amount (100 mass%) of the active ingredient in the obtained composition (y-2) was 20 mass%.

Then, the prepared composition (y-2) is applied on the surface of the release agent of the easy release film to form a coating film, and the coating film is dried at 100 ° C. for 120 seconds to obtain a thermally expandable substrate (Y-2) having a thickness of 50 μm has formed

Production Example 5 (formation of thermally expandable pressure-sensitive adhesive layer (Y-3))

6.3 parts by mass (solid content ratio) of the isocyanate-based crosslinking agent (i) and the thermally expandable particles (i) were mixed with 100 parts by mass of the solid content of the acrylic copolymer (ii), which is an adhesive resin, and diluted with toluene; It was stirred uniformly to prepare a composition (y-3) having a solid content concentration (active ingredient concentration) of 30% by mass.

In addition, the content of the thermally expandable particles (i) relative to the total amount (100 mass%) of the active ingredient in the obtained composition (y-3) was 20 mass%.

Then, on the surface of the release agent layer of the easy release film, the prepared composition (y-3) was applied to form a coating film, and the coating film was dried at 100 ° C. for 120 seconds to obtain a thermally expandable pressure-sensitive adhesive layer (Y-3) having a thickness of 50 μm. 3) was formed.

Production Example 6 (Formation of Thermally Expandable Substrate (Y-4))

(1) Synthesis of acrylic copolymer (iii)

52 parts by mass of n-butyl acrylate (BA), 20 parts by mass of methyl methacrylate (MMA), and 28 parts by mass of 2-hydroxyethyl acrylate (HEA) were solution-polymerized in an ethyl acetate solvent to obtain a non-energy ray curable An acrylic copolymer was obtained.

Methacryloyloxyethyl isocyanate (MOI) in an amount such that the number of isocyanate groups is 0.9 equivalent with respect to the total number of hydroxyl groups in the obtained acrylic copolymer is added to a solution containing the acrylic copolymer to react, and the side chain is An energy ray-curable acrylic copolymer (iii) having a Mw of 1,000,000 and having a methacryloyl group was obtained.

(2) Formation of thermally expandable substrate (Y-4)

Then, with respect to 100 parts by mass of the solid content of the energy ray curable acrylic copolymer (iii) obtained in the above (1), the isocyanate-based crosslinking agent (i) is 0.5 parts by mass (solid content ratio), and the photopolymerization initiator (i) is 3.0 parts by mass. Part by mass (solid content ratio), the thermally expandable particles (i) were blended, diluted with toluene, and stirred uniformly to prepare a composition (y-4) having a solid content concentration (active ingredient concentration) of 30 mass%.

Further, the content of the thermally expandable particles (1) with respect to the total amount (100 mass%) of the active ingredient in the obtained composition (y-4) was 20 mass%.

Then, on the surface of the release agent layer of the easy release film, the prepared composition (y-4) was applied to form a coating film, and after drying the coating film at 100 ° C. for 120 seconds, illuminance 160 mW / cm 2, light amount 500 mJ / cm 2 was irradiated with ultraviolet rays to form a thermally expandable substrate (Y-4) having a thickness of 50 μm. In addition, said illuminance and light quantity at the time of ultraviolet-ray irradiation are the values measured using the illuminance and photometer (made by EIT, product name "UV"Power"Puck"II").

Regarding the heat-expandable base material (Y-1) to (Y-2), (Y-4) formed in Production Examples 3 to 4 and 6 and the heat-expandable pressure-sensitive adhesive layer (Y-3) formed in Production Example 5, the above-described method Based on this, the storage modulus (E′) was measured at 23° C., 100° C., and 208° C., which is the starting temperature of the thermally expandable particles used, and the probe tack value at the surface was also measured. These results are shown in Table 1.

Example 1

After attaching the exposed surfaces of the first pressure-sensitive adhesive layer (X-1) formed in Production Example 1 and the thermally expandable substrate (Y-1) formed in Production Example 3 to each other, easy peeling of the thermally expandable substrate (Y-1) side The film was removed, and the second pressure-sensitive adhesive layer (X-2) formed in Production Example 2 was attached to the exposed surface of the thermally expandable substrate (Y-1).

As a result, the light release film/second adhesive layer (X-2)/heat-expandable base material (Y-1)/first adhesive layer (X-1)/heavy release film are laminated in this order (1) has produced

Example 2

Easy-to-peel film/second pressure-sensitive adhesive layer (X-2)/ A pressure-sensitive adhesive sheet (2) was produced by laminating the thermally expandable base material (Y-2)/first pressure-sensitive adhesive layer (X-1)/heavy release film in this order.

Comparative Example 1

The exposed surfaces of the second pressure-sensitive adhesive layer (X-2) formed in Production Example 2 and the thermally expandable pressure-sensitive adhesive layer (Y-3) formed in Production Example 5 were attached to each other.

Then, the easy release film on the side of the thermally expandable adhesive layer (Y-3) is removed, and the first adhesive layer (X-1) formed in Production Example 1 is formed on the surface of the exposed thermally expandable adhesive layer (Y-3). attached to each other

As a result, the light release film/second adhesive layer (X-2)/heat-expandable adhesive layer (Y-3)/first adhesive layer (X-1)/heavy release film are laminated in this order (3) ) was produced.

Comparative Example 2

Easy-to-peel film/Second pressure-sensitive adhesive layer (X-2)/ A pressure-sensitive adhesive sheet 4 was produced by laminating the thermally expandable base material (Y-4)/first pressure-sensitive adhesive layer (X-1)/heavy release film in this order.

Comparative Example 3

The exposed surfaces of the second pressure-sensitive adhesive layer (X-2) formed in Production Example 2 and the thermally expandable pressure-sensitive adhesive layer (Y-3) formed in Production Example 5 are attached to each other, and the easy-to-peel film/second pressure-sensitive adhesive layer (X-2 ) / heat-expandable pressure-sensitive adhesive layer (Y-3) / easy-peelable film were laminated in this order to produce an adhesive sheet (5).

In addition, the following measurements were performed on the produced PSA sheets (1) to (5). These results are shown in Table 2.

<Evaluation of displacement of semiconductor chips during encapsulation process>

The easy release film on the side of the second pressure-sensitive adhesive layer (X-2) of the produced pressure-sensitive adhesive sheets (1) to (5) was removed, and the exposed pressure-sensitive adhesive surface of the second pressure-sensitive adhesive layer (X-2) was attached to a support. .

Then, the heavy release films of the adhesive sheets 1 to 4 and the light release film of the other side of the adhesive sheet 5 are removed, and the exposed first adhesive layer (X-1) or the thermally expandable adhesive layer (Y On the adhesive surface of -3), 9 semiconductor chips (each chip size is 6.4 mm × 6.4 mm, chip thickness is 200 μm (#2000)) are placed so that the circuit surface of each semiconductor chip is in contact with the adhesive surface, It was tactful with the necessary spacing.

Thereafter, a resin film for sealing was laminated on the adhesive surface and the semiconductor chip, and the semiconductor chip was sealed using a vacuum heating and pressing laminator ("7024 HP5" manufactured by ROHM and HAAS) to produce a sealed body.

In addition, sealing conditions are as follows.

Preheating temperature: 100℃ for both table and diagram

·Vacuum: 60 seconds

・Dynamic Press Mode: 30 seconds

·Static press mode: 10 seconds

Encapsulation temperature: 180 ° C (temperature lower than 208 ° C, which is the starting temperature of expansion of thermally expandable particles)

・Encapsulation time: 60 minutes

After sealing, the pressure-sensitive adhesive sheets (1) to (5) are heated for 3 minutes to an expansion start temperature of the thermally expandable particles (208° C. or higher, 240° C. , The semiconductor chip on the surface of the separated encapsulation body (the surface where the adhesive sheet was attached) was observed visually and under a microscope, the presence or absence of positional displacement of the semiconductor chip was confirmed, and the following criteria were evaluated.

A: A semiconductor chip with a displacement of 25 µm or more from before sealing was not confirmed.

F: A semiconductor chip with a displacement of 25 μm or more from before sealing was confirmed.

<Evaluation of the flatness of the surface of the semiconductor chip after the sealing step>

The surface of the semiconductor chip side of the encapsulation body from which the adhesive sheets (1) to (5) were separated obtained in the above-mentioned "evaluation of positional misalignment of the semiconductor chip during the encapsulation step" was measured using a contact type surface roughness meter ("SV3000" manufactured by Mitutoyo Corporation). The level difference was measured using and evaluated according to the following criteria.

· A: The location where a level difference of 2 micrometers or more had arisen was not confirmed.

· F: A location where a level difference of 2 µm or more was generated was confirmed.

<Measurement of the adhesive strength of the adhesive sheet before and after heating>

The easy release film on the side of the second pressure-sensitive adhesive layer (X-2) of the manufactured pressure-sensitive adhesive sheets (1) to (5) is removed, and on the surface of the exposed second pressure-sensitive adhesive layer (X-2), a thickness of 50 μm is applied. A polyethylene terephthalate (PET) film (manufactured by TOYOBO CO., LTD., product name "Cosmo Shine A4100") was laminated to form an adhesive sheet with a base material.

Then, the heavy release films of the adhesive sheets 1 to 4 and the light release film of the other side of the adhesive sheet 5 are also removed, and the exposed first adhesive layer (X-1) or the thermally expandable adhesive layer (Y The adhesive surface of -3) was adhered to a stainless steel plate (SUS304 polished No. 360) as an adherend, and left still for 24 hours in an environment of 23°C and 50% RH (relative humidity) was used as a test sample.

Then, using the above test sample, in an environment of 23°C and 50%RH (relative humidity), based on JIS 　Z0237: 2000, according to the 180° peeling method, at a tensile speed of 300 mm/min at 23°C. of the adhesive force was measured.

Further, the above test sample was heated for 3 minutes on a hot plate at 240°C, which is equal to or higher than the expansion initiation temperature of the thermally expandable particles (208°C), and then heated to 60 °C in a standard environment (23°C, 50% RH (relative humidity)). After leaving still for a minute, the adhesive strength after heating to the expansion start temperature or higher was also measured at a tensile speed of 300 mm/min according to the 180° peeling method based on JIS Z0237:2000.

In addition, when it was difficult to measure the adhesive force to the extent that it could not be adhered to the stainless steel plate as an adherend, it was regarded as "not measurable" and the adhesive force was set to 0 (N/25 mm).

From Table 2, it can be seen that the PSA sheets (1) and (2) of Examples 1 and 2 have a high effect of suppressing sedimentation of semiconductor chips during heating in the sealing step, so that positional displacement of the semiconductor chips is not observed, and sealing The surface on the side of the semiconductor chip after the process was also flat.

In addition, the adhesive sheets (1) and (2) have good adhesive strength before heating, but after heating to the expansion start temperature or higher, the adhesive strength decreases to such an extent that measurement becomes impossible. It became the result which proved that it can peel easily.

On the other hand, since the PSA sheet 3 of Comparative Example 1 and the PSA sheet 5 of Comparative Example 3 have a thermally expandable adhesive layer instead of a thermally expandable substrate, sedimentation of the semiconductor chip is prevented during heating in the sealing step. Occurrence occurred, positional displacement of the semiconductor chip was observed, and a level difference was observed on the surface of the semiconductor chip side after the sealing step. For this reason, it is considered unsuitable for use in the encapsulation process at the time of manufacturing FOWLP, for example.

In addition, the adhesive strength of the adhesive sheet 4 of Comparative Example 2 before and after heating to the expansion start temperature or higher did not change much, and it was impossible to say that it could be peeled off by heating.

1a, 1b: adhesive sheet
2a, 2b: double-sided adhesive sheet
11: thermally expandable substrate
12: adhesive layer
121: first adhesive layer
122: second adhesive layer
13, 131, 132: release material
50: FOWLP
51: semiconductor chip
52: encapsulating resin layer
53: redistribution layer
54: solder ball

Claims (12)

A non-adhesive thermally expandable substrate comprising a resin and thermally expandable particles having an expansion onset temperature (t) of 120 to 250°C, and
An adhesive layer containing an adhesive resin;
As an adhesive sheet having
The thermally expandable substrate satisfies the following requirements (1) to (2),
The pressure-sensitive adhesive sheet, wherein the ratio of the thickness of the thermally expandable substrate to the thickness of the pressure-sensitive adhesive layer (heat-expandable substrate/pressure-sensitive adhesive layer) is 0.2 or more at 23°C.
Requirement (1): The storage modulus (E') (100) of the thermally expandable substrate at 100°C is 2.0×10 ⁵ Pa or more.
Requirement (2): The storage elastic modulus (E') (t) of the thermally expandable substrate at the expansion start temperature (t) of the thermally expandable particles is 1.0×10 ⁷ Pa or less. According to claim 1,
The heat-expandable substrate satisfies the following requirement (3), the pressure-sensitive adhesive sheet.
Requirement (3): The storage modulus (E') (23) of the thermally expandable substrate at 23°C is 1.0×10 ⁶ Pa or more. delete According to claim 1 or 2,
At 23 ° C., the thickness of the thermally expandable substrate is 10 to 1000 μm, and the thickness of the pressure-sensitive adhesive layer is 1 to 60 μm. According to claim 1 or 2,
The pressure-sensitive adhesive sheet having a probe tack value on the surface of the thermally expandable substrate of less than 50 mN/5 mmφ. According to claim 1 or 2,
A pressure-sensitive adhesive sheet having a storage shear modulus (G′) 23 of the pressure-sensitive adhesive layer at 23° C. of 1.0×10 ⁴ to 1.0×10 ⁸ Pa. According to claim 1 or 2,
The pressure-sensitive adhesive sheet having two pressure-sensitive adhesive layers on both surfaces of the heat-expandable substrate, respectively. According to claim 1 or 2,
The pressure-sensitive adhesive sheet, wherein the average particle diameter of the heat-expandable particles before expansion at 23°C is 3 to 100 µm. According to claim 1 or 2,
A pressure-sensitive adhesive sheet used in an encapsulating process in which an encapsulating resin is used and heating is involved. delete A method of using a pressure-sensitive adhesive sheet comprising: attaching the pressure-sensitive adhesive sheet according to claim 1 or 2 to an adherend and then peeling the pressure-sensitive adhesive sheet from the adherend by heat treatment at a temperature equal to or higher than the expansion start temperature (t). According to claim 11,
A method of using an adhesive sheet that is used in a sealing process in which an encapsulating resin is used and heating is involved.

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