JP7541021B2 - Expanded Sheet - Google Patents

Description

The present invention relates to an adhesive sheet.

In recent years, electronic devices have become smaller, lighter, and more functional. Semiconductor devices mounted on electronic devices are also required to be smaller, thinner, and more dense. Semiconductor chips are sometimes mounted in packages that are close to the size of the chip. Such packages are sometimes called chip scale packages (CSPs). One type of CSP is wafer level packages (WLPs). In WLPs, external electrodes and the like are formed on a wafer before it is diced into individual pieces, and the wafer is finally diced into individual pieces. WLPs include fan-in and fan-out types. In fan-out type WLP (hereinafter sometimes abbreviated as "FO-WLP"), a semiconductor chip is covered with a sealing material so that the area is larger than the chip size to form a semiconductor chip sealing body, and redistribution layers and external electrodes are formed not only on the circuit surface of the semiconductor chip but also on the surface area of the sealing material.

For example, Patent Document 1 describes a method for manufacturing a semiconductor package in which a plurality of semiconductor chips separated from a semiconductor wafer are surrounded by a molding member to form an expanded wafer while leaving the circuit formation surface, and a rewiring pattern is extended to an area outside the semiconductor chip. In the manufacturing method described in Patent Document 1, before surrounding the plurality of separated semiconductor chips with a molding member, an expand sheet is attached, and the expand sheet is expanded to expand the distance between the plurality of semiconductor chips. Patent Document 2 describes a semiconductor processing sheet used to expand the spacing between multiple semiconductor chips.

International Publication No. 2010/058646 International Publication No. 2018/003312

In the above-mentioned FO-WLP manufacturing method, in order to form the above-mentioned rewiring patterns and the like in the area outside the semiconductor chips, the expand sheet is expanded to sufficiently separate the semiconductor chips from each other.
The sheet used in the expanding step usually has an adhesive layer for fixing the semiconductor chip on the sheet and a base material for supporting the adhesive layer. When the sheet for expanding is stretched as described in Patent Document 1 and Patent Document 2, not only the base material of the sheet but also the adhesive layer is stretched. After the expanding step, when the semiconductor chip is peeled off from the adhesive layer, a problem may occur in which the adhesive layer remains on the surface of the semiconductor chip that was in contact with the adhesive layer. In this specification, such a problem may be referred to as adhesive residue.

The present invention aims to provide an adhesive sheet that can suppress adhesive residue.

According to one aspect of the present invention, there is provided an adhesive sheet having a substrate and an adhesive layer, the adhesive layer containing an energy ray-curable resin, and the adhesive layer alone has a breaking energy of 0.055 J or more after irradiation with energy rays.

In one embodiment of the adhesive sheet of the present invention, it is preferable that the breaking energy of the adhesive layer alone after irradiation with energy rays is 0.065 J or more.

In one embodiment of the adhesive sheet of the present invention, it is preferable that the breaking elongation of the adhesive layer alone after irradiation with energy rays is 6% or more.

In the adhesive sheet according to one embodiment of the present invention, it is preferable that the energy ray curable resin has one or more ethylene glycol units represented by the following general formula (11):

(In the general formula (11), m is 1 or more.)

In the adhesive sheet according to one embodiment of the present invention, it is preferable that the energy ray curable resin further has three or more energy ray curable functional groups.

In the adhesive sheet according to one embodiment of the present invention, it is preferable that the energy ray curable resin further has one or more glycerin skeletons.

According to one aspect of the present invention, an adhesive sheet that can suppress adhesive residue can be provided.

FIG. 1 is a cross-sectional view illustrating a first embodiment of a method of using a pressure-sensitive adhesive sheet according to one embodiment of the present invention. FIG. 1 is a cross-sectional view illustrating a first embodiment of a method of using a pressure-sensitive adhesive sheet according to one embodiment of the present invention. FIG. 1 is a cross-sectional view illustrating a first embodiment of a method of using a pressure-sensitive adhesive sheet according to one embodiment of the present invention. FIG. 1 is a cross-sectional view illustrating a first embodiment of a method of using a pressure-sensitive adhesive sheet according to one embodiment of the present invention. FIG. 1 is a cross-sectional view illustrating a first embodiment of a method of using a pressure-sensitive adhesive sheet according to one embodiment of the present invention. FIG. 1 is a cross-sectional view illustrating a first embodiment of a method of using a pressure-sensitive adhesive sheet according to one embodiment of the present invention. FIG. 2 is a plan view illustrating a biaxial stretching and expanding device used in the examples. FIG. 4 is a cross-sectional view of a pressure-sensitive adhesive sheet according to another embodiment of the present invention.

Hereinafter, one embodiment of the present invention will be described.
[Adhesive sheet]
The pressure-sensitive adhesive sheet according to the present embodiment includes a substrate and a pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet may have any shape, such as a tape shape (long shape) or a label shape (sheet shape).

(Adhesive Layer)
In the pressure-sensitive adhesive sheet according to the present embodiment, the pressure-sensitive adhesive layer contains an energy ray-curable resin, and the pressure-sensitive adhesive layer alone has a breaking energy of 0.055 J or more after irradiation with energy rays.
A pressure-sensitive adhesive sheet having such a breaking energy characteristic of the pressure-sensitive adhesive layer alone after irradiation with energy rays can suppress adhesive residue. If the breaking energy is 0.055 J or more, the pressure-sensitive adhesive layer is unlikely to break and adhesive residue is unlikely to be left behind when the chip is peeled off from the pressure-sensitive adhesive sheet by irradiating it with energy rays after the expanding step.

In the adhesive sheet of this embodiment, it is preferable that the breaking energy of the adhesive layer alone after irradiation with energy rays is 0.065 J or more.

In the adhesive sheet of this embodiment, it is preferable that the breaking energy of the adhesive layer alone after irradiation with energy rays is 0.300 J or less.

The breaking energy of the adhesive layer alone after irradiation with energy rays can be measured by the method described in the examples below.

In the pressure-sensitive adhesive sheet according to this embodiment, it is preferable that the breaking elongation in the displacement-stress curve of the pressure-sensitive adhesive layer alone before irradiation with energy rays is 1500% or more, and that when the displacement in the displacement-stress curve of the pressure-sensitive adhesive layer alone is 1500%, the stress is 0.22 MPa or less.
A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer that combines such properties of breaking elongation and stress can improve alignment after expansion in the expanding step and suppress chip lifting.
In the expanding step, for example, when the gap between the semiconductor chips before expansion is 35 μm, when the gap is expanded to 2000 μm by expanding, the pressure-sensitive adhesive layer undergoes large deformation while conforming to the substrate. When the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to this embodiment has a breaking elongation of 1500% or more before energy ray irradiation, the pressure-sensitive adhesive layer can conform to the substrate without breaking even during such large deformation due to expansion.
Furthermore, when the stress at 1500% displacement in the displacement-stress curve of the adhesive layer alone is 0.22 MPa or less, the constraint force suppressing the deformation of the adhesive sheet by the semiconductor chip when the base material is greatly deformed by expanding can be reduced. The surface of the semiconductor chip in contact with the adhesive layer fixes the surface of the adhesive layer, and a constraint force is applied to suppress the deformation of the base material by pulling the adhesive layer during expansion, which results in non-uniform deformation of the adhesive sheet and impaired alignment of the semiconductor chips. If this constraint force is zero, the adhesive sheet can be expanded uniformly, and the larger the constraint force, the more the deformation of the adhesive sheet is concentrated near the gaps between the semiconductor chips, and further, when the entire work area is taken into consideration, the constraint force is concentrated on the semiconductor chips at the ends, making the expansion itself difficult.
In the pressure-sensitive adhesive sheet according to the present embodiment, when the stress is 0.22 MPa or less, the binding force can be reduced, and good alignment is achieved. When the stress at a displacement of 1500% in the displacement-stress curve of the pressure-sensitive adhesive layer alone exceeds 0.22 MPa, the binding force of the semiconductor chip affects the alignment, and the alignment is impaired.

In the pressure-sensitive adhesive sheet according to this embodiment, it is preferable that the stress is 0.17 MPa or less when the displacement in the displacement-stress curve of the pressure-sensitive adhesive layer alone is 1500%.
A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer in which the stress at 1500% displacement is 0.17 MPa or less exhibits excellent alignment even when the expansion amount in the expanding step is large.

In the pressure-sensitive adhesive sheet according to the present embodiment, the pressure-sensitive adhesive layer alone preferably has a stress of 0.0001 MPa or more when the displacement in the displacement-stress curve is 1500%. By having a stress of 0.0001 MPa or more when the displacement is 1500%, the pressure-sensitive adhesive layer can be prevented from becoming too soft.
If the stress at 1500% displacement is 0.0001 MPa or more, even if the expansion amount is large in the expansion process, problems such as the adhesive sheet coming off the chuck of the expansion device due to insufficient cohesive force of the adhesive can be prevented.

In the pressure-sensitive adhesive sheet according to this embodiment, the pressure-sensitive adhesive layer alone preferably has a breaking elongation of 6% or more after irradiation with energy rays.
If the adhesive layer alone has a breaking elongation of 6% or more after energy ray irradiation, the adhesive layer can follow the deformation of the adhesive sheet when the semiconductor chip is picked up from the adhesive sheet, thereby suppressing adhesive residue.

The breaking elongation in the displacement-stress curve of the adhesive layer alone, as well as the stress at a displacement of 1500% in the displacement-stress curve, can be measured by the method described in the examples below.

In the adhesive sheet according to the present embodiment, the adhesive contained in the adhesive layer is not particularly limited as long as the breaking energy of the adhesive layer alone after irradiation with energy rays satisfies the above-mentioned range. The material (adhesive) constituting the adhesive layer can be appropriately selected and blended, for example, from the materials described below, so as to satisfy the above-mentioned breaking energy range.

Energy ray curable resin (a1)
The energy ray curable resin (a1) is a resin that is polymerized and cured when irradiated with energy rays. Examples of the energy rays include ultraviolet rays and electron beams. The energy ray curable resin (a1) is preferably an ultraviolet ray curable resin.

The energy ray curable resin (a1) has at least one energy ray curable functional group in the molecule. The energy ray curable functional group is preferably a functional group containing a carbon-carbon double bond, and more preferably an acryloyl group or a methacryloyl group.
The pressure-sensitive adhesive layer containing the energy ray-curable resin (a1) is cured by irradiation with energy rays, and the adhesive strength is reduced. When it is desired to separate the adherend and the pressure-sensitive adhesive sheet, the separation can be easily achieved by irradiating the pressure-sensitive adhesive layer with energy rays.

Examples of energy ray-curable resins (a1) include low molecular weight compounds having energy ray-curable groups (monofunctional monomers, polyfunctional monomers, monofunctional oligomers, and polyfunctional oligomers).

It is preferable that the energy ray curable resin (a1) has one or more ethylene glycol units represented by the following general formula (11).

(In the general formula (11), m is 1 or more.)

When the energy ray curable resin (a1) has two or more ethylene glycol units represented by the following general formula (11), the two or more m's are the same or different from each other.

It is preferable that m in the general formula (11) is 2 or more.

Because the energy ray curable resin (a1) has a flexible polyethylene glycol chain, the adhesive layer before curing becomes easily deformed, and the crosslink density of the adhesive layer after curing is appropriately reduced, making the adhesive layer less likely to break.

The number of ethylene glycol units per molecule of the energy ray curable resin (a1) is preferably 3 or more, and more preferably 5 or more.

In one embodiment, the number of ethylene glycol units per molecule of the energy ray curable resin (a1) is preferably 10 or more, more preferably 30 or more, and even more preferably 50 or more.

The number of ethylene glycol units per molecule of the energy ray curable resin (a1) is preferably 100 or less, more preferably 90 or less, and even more preferably 80 or less.

The energy ray curable resin (a1) preferably further has three or more energy ray curable functional groups, more preferably four or more. If the number of energy ray curable functional groups in the energy ray curable resin (a1) is three or more, it becomes easier to suppress adhesive residue.

It is preferable that the energy ray-curable resin (a1) has a group in which an ethylene glycol unit represented by general formula (11) is directly bonded to an energy ray-curable functional group.

It is preferable that the energy ray curable resin (a1) has one or more groups containing an ethylene glycol unit represented by the following general formula (11A).

(In the general formula (11A), m is 1 or more, and R is a hydrogen atom or a methyl group.)

When the energy ray curable resin (a1) has a group represented by the general formula (11A), the number of groups represented by the general formula (11A) in one molecule is preferably 3 or more, and more preferably 4 or more.
When the number of groups represented by the general formula (11A) contained in one molecule of the energy ray curable resin (a1) is 3 or more, adhesive residue can be more easily suppressed.
In the case where the energy ray curable resin (a1) has a group represented by the general formula (11A), the number of groups represented by the general formula (11A) in one molecule is preferably 10 or less, more preferably 9 or less, and even more preferably 8 or less.

It is preferable that the energy ray curable resin (a1) further has one or more glycerin skeletons. It is also preferable that the energy ray curable resin (a1) has a polyglycerin skeleton.

The energy ray curable resin (a1) has a glycerin skeleton that has more ether bonds and can be multifunctionalized than a carbon-carbon bond system such as a saturated hydrocarbon skeleton, making the adhesive layer more easily deformable and at the same time achieving good curing properties.

The energy ray curable resin (a1) is preferably represented by the following general formula (12).

(In the general formula (12),
n is 1 or more,
R ₁ , R ₂ and R ₃ each independently represent an atom or a group in a molecule of the energy ray-curable resin;
At least one of R ₁ , R ₂ and R ₃ has one or more ethylene glycol units represented by the general formula (11).

When n is 1, the general formula (12) is represented by the following general formula (12-1).

(In the general formula (12-1), R ₁ , R ₂ and R ₃ have the same meanings as R ₁ , R ₂ and R ₃ in the general formula (12).)

When n is 4, the general formula (12) is represented by the following general formula (12-4).

(In the general formula (12-4),
R _1A , R _1B , R _1C and R _1D each independently have the same meaning as R ₁ in formula (12);
_R2 and _R3 have the same meanings as _R2 and _R3 in the general formula (12).

It is preferable that R ₁ , R ₂ and R ₃ each independently have one or more ethylene glycol units represented by the general formula (11). In this case, the number of ethylene glycol units in R ₁ , R ₂ and R ₃ is the same or different from each other.

It is preferable that at least one of R ₁ , R ₂ and R ₃ is a group containing an energy ray-curable functional group, and it is more preferable that R ₁ , R ₂ and R ₃ are each independently a group containing an energy ray-curable functional group.

It is preferable that R ₁ , R ₂ and R ₃ each independently represent a group having one or more ethylene glycol units represented by the general formula (11) and containing an energy ray-curable functional group.

It is more preferable that R ₁ , R ₂ and R ₃ are each independently a group represented by the general formula (11A).

For example, in the energy ray-curable resin (a1) represented by the general formula (12-4), when R _1A , R _1B , R _1C , R _1D , R ₂ , and R ₃ each have one energy ray-curable functional group, the energy ray-curable resin (a1) corresponds to having six energy ray-curable functional groups.

The energy ray curable resin (a1) is preferably represented by the following general formula (13).

(In the general formula (13),
n is 1 or more,
R ₁₁ , R ₁₂ and R ₁₃ each independently represent another atom or a group in the molecule of the energy ray-curable resin;
m1, m2 and m3 each independently represent 1 or more.

In the general formula (13), when n is 2 or more, two or more m1's are the same or different from each other, and two or more R _'s are the same or different from each other.

At least one of R ₁₁ , R ₁₂ and R ₁₃ is preferably a group containing an energy ray-curable functional group, and it is more preferable that R ₁₁ , R ₁₂ and R ₁₃ are each independently a group containing an energy ray-curable functional group.

It is also preferable that the energy ray curable resin (a1) is represented by the following general formula (14).

(In the general formula (14),
R ₂₁ , R ₂₂ , R ₂₃ and R ₂₄ each independently represent another atom or a group in the molecule of the energy ray-curable resin;
At least one of R ₂₁ , R ₂₂ , R ₂₃ and R ₂₄ has one or more ethylene glycol units represented by the general formula (11).

It is preferable that R ₂₁ , R ₂₂ , R ₂₃ and R ₂₄ each independently have one or more ethylene glycol units represented by the general formula (11). In this case, the number of ethylene glycol units in R ₂₁ , R ₂₂ , R ₂₃ and R ₂₄ is the same or different from each other.

It is preferable that at least one of R ₂₁ , R ₂₂ , R ₂₃ and R ₂₄ is a group containing an energy ray-curable functional group, and it is more preferable that R ₂₁ , R ₂₂ , R ₂₃ and R ₂₄ are each independently a group containing an energy ray-curable functional group.

It is preferred that R ₂₁ , R ₂₂ , R ₂₃ and R ₂₄ each independently represent a group having one or more ethylene glycol units represented by the general formula (11) and containing an energy ray-curable functional group.

It is more preferable that R ₂₁ , R ₂₂ , R ₂₃ and R ₂₄ each independently represent a group represented by the general formula (11A).

The energy ray curable resin (a1) is preferably represented by the following general formula (15).

(In the general formula (15),
R ₂₅ , R ₂₆ , R ₂₇ and R ₂₈ each independently represent another atom or a group in the molecule of the energy ray-curable resin,
m21, m22, m23 and m24 each independently represent 1 or more.

It is preferable that at least one of R ₂₅ , R ₂₆ , R ₂₇ and R ₂₈ is a group containing an energy ray-curable functional group, and it is more preferable that R ₂₅ , R ₂₆ , R ₂₇ and R ₂₈ are each independently a group containing an energy ray-curable functional group.

The pressure-sensitive adhesive layer preferably contains 15 mass% or more and 55 mass% or less of the energy ray curable resin (a1) relative to the total amount of solids in the pressure-sensitive adhesive layer, more preferably contains 20 mass% or more and 48 mass% or less, and even more preferably contains 24 mass% or more and 48 mass% or less.
When the pressure-sensitive adhesive layer contains 15 mass % or more and 55 mass % or less of the energy ray curable resin (a1), the alignment property can be further improved and adhesive residue can be further suppressed.
When the pressure-sensitive adhesive layer contains 20% by mass or more of the energy ray-curable resin (a1), the alignment property is easily improved.
When the pressure-sensitive adhesive layer contains 48% by mass or less of the energy ray curable resin (a1), the pressure-sensitive adhesive is less likely to seep out from the ends of the roll when the pressure-sensitive adhesive sheet is wound into a roll.

The ratio M _EG /M _UV of the total number M _EG of ethylene glycol units contained in the energy ray curable resin (a1) to the total number M _UV of energy ray curable functional groups contained in the energy ray curable resin (a1) is preferably 1 or more and 15 or less.

When the pressure-sensitive adhesive layer contains 24 mass % or more of the energy ray curable resin (a1) and has M _EG /M _UV of 9 or more, excellent alignment is exhibited even if the expansion amount in the expanding step is large.

The energy ray curable resin (a1) is preferably a (meth)acrylic resin.

The energy ray-curable resin (a1) is preferably an ultraviolet-curable resin, and more preferably an ultraviolet-curable (meth)acrylic resin.

The energy ray curable resin (a1) is a resin that undergoes polymerization and hardening when irradiated with energy rays. Examples of energy rays include ultraviolet rays and electron beams.

Examples of the energy ray-curable resin (a1) that can be used include acrylates such as trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, pentaerythritol triacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate, 1,4-butylene glycol diacrylate, and 1,6-hexanediol diacrylate, cyclic aliphatic skeleton-containing acrylates such as dicyclopentadiene dimethoxy diacrylate and isobornyl acrylate, and acrylate compounds such as polyethylene glycol diacrylate, oligoester acrylate, urethane acrylate oligomer, epoxy modified acrylate, polyether acrylate, and itaconic acid oligomer.

The energy ray curable resin (a1) may be used alone or in combination of two or more.

The molecular weight of the energy ray curable resin (a1) is preferably 100 or more, and more preferably 300 or more.
The molecular weight of the energy ray curable resin (a1) is preferably 30,000 or less, and more preferably 15,000 or less.
When the molecular weight of the energy ray curable resin (a1) is 100 or more, phase separation in the pressure-sensitive adhesive can be prevented, and the storage stability of the tape can be maintained.
When the molecular weight of the energy ray curable resin (a1) is 30,000 or less, the compatibility with other materials can be maintained.

It is also preferable that the weight average molecular weight of the energy ray curable resin (a1) is not more than 10000. When the weight average molecular weight of the energy ray curable resin (a1) is not more than 10000, it is easy to achieve both extensibility and curability of the adhesive.
The weight average molecular weight can be obtained from a standard polystyrene equivalent value by gel permeation chromatography (GPC).

Photopolymerization initiator (C)
When the pressure-sensitive adhesive layer contains an ultraviolet-curable compound (for example, an ultraviolet-curable resin), the pressure-sensitive adhesive layer preferably contains a photopolymerization initiator (C).
By including the photopolymerization initiator (C) in the pressure-sensitive adhesive layer, the polymerization curing time and the light irradiation dose can be reduced.

Specific examples of photopolymerization initiators (C) include benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin methyl benzoate, benzoin dimethyl ketal, 2,4-diethylthioxanthone, 1-hydroxycyclohexyl phenyl ketone, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzyl, dibenzyl, diacetyl, β-chloroanthraquinone, (2,4,6-trimethylbenzyldiphenyl)phosphine oxide, 2-benzothiazole-N,N-diethyldithiocarbamate, oligo{2-hydroxy-2-methyl-1-[4-(1-propenyl)phenyl]propanone}, and 2,2-dimethoxy-1,2-diphenylethan-1-one. These photopolymerization initiators (C) may be used alone or in combination of two or more.

When the energy ray curable resin (a1) and the (meth)acrylic copolymer (b1) are blended in the pressure-sensitive adhesive layer, the photopolymerization initiator (C) is preferably used in an amount of 0.1 parts by mass or more, and more preferably 0.5 parts by mass or more, per 100 parts by mass of the total amount of the energy ray curable resin (a1) and the (meth)acrylic copolymer (b1).
In addition, when the energy ray curable resin (a1) and the (meth)acrylic copolymer (b1) are blended in the pressure-sensitive adhesive layer, the photopolymerization initiator (C) is preferably used in an amount of 10 parts by mass or less, and more preferably 6 parts by mass or less, per 100 parts by mass of the total amount of the energy ray curable resin (a1) and the (meth)acrylic copolymer (b1).

In addition to the above components, the adhesive layer may contain other components as appropriate. Examples of other components include a crosslinking agent (E), an antistatic agent, an antioxidant, and a colorant.

Crosslinking agent (E)
As the crosslinking agent (E), a polyfunctional compound having reactivity with the functional group of the (meth)acrylic copolymer (b1) etc. can be used. Examples of such polyfunctional compounds include isocyanate compounds, epoxy compounds, amine compounds, melamine compounds, aziridine compounds, hydrazine compounds, aldehyde compounds, oxazoline compounds, metal alkoxide compounds, metal chelate compounds, metal salts, ammonium salts, and reactive phenolic resins.

The amount of the crosslinking agent (E) is preferably 0.01 parts by mass or more, more preferably 0.03 parts by mass or more, and even more preferably 0.04 parts by mass or more, based on 100 parts by mass of the (meth)acrylic copolymer (b1).
The amount of the crosslinking agent (E) is preferably 8 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 3.5 parts by mass or less, and even more preferably 2.1 parts by mass or less, relative to 100 parts by mass of the (meth)acrylic copolymer (b1).

The thickness of the adhesive layer is not particularly limited. For example, the thickness of the adhesive layer is preferably 10 μm or more, and more preferably 20 μm or more. The thickness of the adhesive layer is preferably 150 μm or less, and more preferably 100 μm or less.

(Substrate)
The substrate preferably has a first substrate side and a second substrate side opposite the first substrate side.
In the pressure-sensitive adhesive sheet of this embodiment, it is preferable that the pressure-sensitive adhesive layer of this embodiment is provided on one of the first substrate surface and the second substrate surface, and it is preferable that no pressure-sensitive adhesive layer is provided on the other surface.

From the viewpoint of ease of large stretching, the material of the substrate is preferably a thermoplastic elastomer or a rubber-based material, and more preferably a thermoplastic elastomer.

In addition, from the viewpoint of ease of large stretching, it is preferable to use a resin with a relatively low glass transition temperature (Tg) as the material for the substrate. The glass transition temperature (Tg) of such a resin is preferably 90°C or less, more preferably 80°C or less, and even more preferably 70°C or less.

Examples of thermoplastic elastomers include urethane-based elastomers, olefin-based elastomers, vinyl chloride-based elastomers, polyester-based elastomers, styrene-based elastomers, acrylic-based elastomers, and amide-based elastomers. The thermoplastic elastomers may be used alone or in combination of two or more. As the thermoplastic elastomer, it is preferable to use a urethane-based elastomer because it is easy to stretch the elastomer significantly.

Urethane elastomers are generally obtained by reacting a long-chain polyol, a chain extender, and a diisocyanate. Urethane elastomers consist of soft segments having structural units derived from the long-chain polyol, and hard segments having a polyurethane structure obtained by reacting a chain extender with a diisocyanate.

When urethane-based elastomers are classified according to the type of long-chain polyol, they are divided into polyester-based polyurethane elastomers, polyether-based polyurethane elastomers, polycarbonate-based polyurethane elastomers, etc. The urethane-based elastomers can be used alone or in combination of two or more types. In this embodiment, the urethane-based elastomer is preferably a polyester-based polyurethane elastomer or a polyether-based polyurethane elastomer from the viewpoint of being easily stretched greatly.

Examples of long-chain polyols include polyester polyols such as lactone-based polyester polyols and adipate-based polyester polyols; polyether polyols such as polypropylene (ethylene) polyols and polytetramethylene ether glycol; polycarbonate polyols, etc. In this embodiment, the long-chain polyol is preferably an adipate-based polyester polyol from the viewpoint of being easily stretched.

Examples of diisocyanates include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, and hexamethylene diisocyanate. In this embodiment, the diisocyanate is preferably hexamethylene diisocyanate because it is easy to stretch the diisocyanate.

Chain extenders include low molecular weight polyhydric alcohols (e.g., 1,4-butanediol, 1,6-hexanediol, etc.) and aromatic diamines. Of these, it is preferable to use 1,6-hexanediol because it is easy to extend the chain significantly.

Examples of olefin-based elastomers include elastomers containing at least one resin selected from the group consisting of ethylene-α-olefin copolymers, propylene-α-olefin copolymers, butene-α-olefin copolymers, ethylene-propylene-α-olefin copolymers, ethylene-butene-α-olefin copolymers, propylene-butene-α-olefin copolymers, ethylene-propylene-butene-α-olefin copolymers, styrene-isoprene copolymers, and styrene-ethylene-butylene copolymers. Olefin-based elastomers can be used alone or in combination of two or more.

The density of the olefin-based elastomer is not particularly limited. For example, the density of the olefin-based elastomer is preferably 0.860 g/cm ³ or more and less than 0.905 g/cm ³ , more preferably 0.862 g/cm ³ or more and less than 0.900 g/cm ³ , and particularly preferably 0.864 g/cm ³ or more and less than 0.895 g/cm ^3. When the density of the olefin-based elastomer satisfies the above range, the substrate has excellent irregularity-following properties when a semiconductor wafer as an adherend is attached to the pressure-sensitive adhesive sheet.

It is preferable that the mass ratio of monomers consisting of olefin compounds (also referred to as "olefin content" in this specification) among all monomers used to form the olefin elastomer is 50 mass% or more and 100 mass% or less.
If the olefin content is too low, the properties of an elastomer containing structural units derived from an olefin are less likely to be exhibited, and the substrate is less likely to exhibit flexibility and rubber elasticity.
From the viewpoint of stably obtaining flexibility and rubber elasticity, the olefin content is preferably 50% by mass or more, and more preferably 60% by mass or more.

Examples of styrene-based elastomers include styrene-conjugated diene copolymers and styrene-olefin copolymers. Specific examples of styrene-conjugated diene copolymers include unhydrogenated styrene-conjugated diene copolymers such as styrene-butadiene copolymer, styrene-butadiene-styrene copolymer (SBS), styrene-butadiene-butylene-styrene copolymer, styrene-isoprene copolymer, styrene-isoprene-styrene copolymer (SIS), and styrene-ethylene-isoprene-styrene copolymer, as well as hydrogenated styrene-conjugated diene copolymers such as styrene-ethylene/propylene-styrene copolymer (SEPS, a styrene-isoprene-styrene copolymer water additive), and styrene-ethylene-butylene-styrene copolymer (SEBS, a styrene-butadiene copolymer hydrogen additive). In addition, examples of industrially usable styrene-based elastomers include trade names such as Tufprene (manufactured by Asahi Kasei Corporation), Kraton (manufactured by Kraton Polymer Japan Co., Ltd.), Sumitomo TPE-SB (manufactured by Sumitomo Chemical Co., Ltd.), Epofriend (manufactured by Daicel Corporation), Rabalon (manufactured by Mitsubishi Chemical Corporation), Septon (manufactured by Kuraray Co., Ltd.), and Tuftec (manufactured by Asahi Kasei Corporation). The styrene-based elastomer may be hydrogenated or unhydrogenated. The styrene-based elastomers may be used alone or in combination of two or more.

Examples of rubber-based materials include natural rubber, synthetic isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), halogenated butyl rubber, acrylic rubber, urethane rubber, and polysulfide rubber. The rubber-based materials can be used alone or in combination of two or more of these.

The substrate may be a laminated film in which a plurality of films made of the above-mentioned materials (e.g., thermoplastic elastomers or rubber-based materials) are laminated. The substrate may also be a laminated film in which a film made of the above-mentioned materials (e.g., thermoplastic elastomers or rubber-based materials) is laminated with another film.

The substrate may contain additives in a film mainly made of the above-mentioned resin-based material.
Examples of additives include pigments, dyes, flame retardants, plasticizers, antistatic agents, lubricants, and fillers. Examples of pigments include titanium dioxide and carbon black. Examples of fillers include organic materials such as melamine resins, inorganic materials such as fumed silica, and metal materials such as nickel particles. The content of such additives is not particularly limited, but is preferably within a range in which the substrate can exhibit the desired function.

The substrate may be subjected to a surface treatment or primer treatment on one or both sides as desired in order to improve adhesion with the adhesive layer laminated on at least one of the first substrate surface and the second substrate surface. Examples of the surface treatment include an oxidation method and a roughening method. Examples of the primer treatment include a method of forming a primer layer on the substrate surface. Examples of the oxidation method include a corona discharge treatment, a plasma discharge treatment, a chromium oxidation treatment (wet), a flame treatment, a hot air treatment, an ozone treatment, and an ultraviolet irradiation treatment. Examples of the roughening method include a sandblasting method and a thermal spraying method.

When the adhesive layer contains an energy ray-curable adhesive, it is preferable that the substrate is transparent to energy rays. When ultraviolet rays are used as the energy rays, it is preferable that the substrate is transparent to ultraviolet rays. When electron beams are used as the energy rays, it is preferable that the substrate is transparent to electron beams.

The thickness of the substrate is not limited as long as the adhesive sheet can function properly in the desired process. The thickness of the substrate is preferably 20 μm or more, and more preferably 40 μm or more. The thickness of the substrate is preferably 250 μm or less, and more preferably 200 μm or less.

In addition, when the thickness is measured at multiple locations at 2 cm intervals in the in-plane direction of the first substrate surface or the second substrate surface of the substrate, the standard deviation of the thickness of the substrate is preferably 2 μm or less, more preferably 1.5 μm or less, and even more preferably 1 μm or less. With the standard deviation being 2 μm or less, the adhesive sheet has a highly accurate thickness, and it becomes possible to stretch the adhesive sheet uniformly.

It is preferred that the tensile modulus of elasticity in the MD and CD directions of the substrate at 23° C. is 10 MPa or more and 350 MPa or less, respectively, and that the 100% stress in the MD and CD directions of the substrate at 23° C. is 3 MPa or more and 20 MPa or less, respectively.
When the tensile modulus and 100% stress are within the above ranges, the pressure-sensitive adhesive sheet can be stretched significantly.
The 100% stress of the substrate is a value obtained as follows. A test piece having a size of 100 mm (length direction) x 15 mm (width direction) is cut out from the substrate. Both ends of the cut-out test piece in the length direction are gripped by grippers so that the length between the grippers is 50 mm. After gripping the test piece with the grippers, it is pulled in the length direction at a speed of 200 mm/min, and the measured value of the tensile force is read when the length between the grippers becomes 100 mm. The 100% stress of the substrate is a value obtained by dividing the measured value of the tensile force read by the cross-sectional area of the substrate. The cross-sectional area of the substrate is calculated by the width direction length of 15 mm x the thickness of the substrate (test piece). The cutting is performed so that the flow direction (MD direction) or the direction perpendicular to the MD direction (CD direction) during the production of the substrate coincides with the length direction of the test piece. In this tensile test, the thickness of the test piece is not particularly limited and may be the same as the thickness of the substrate to be tested.

It is preferable that the breaking elongation of the substrate in both the MD and CD directions at 23° C. is 100% or more.
When the substrate has a breaking elongation of 100% or more in both the MD and CD directions, the pressure-sensitive adhesive sheet can be largely stretched without breaking.

The tensile modulus (MPa) and breaking elongation (%) of the substrate can be measured as follows. The substrate is cut into 15 mm x 140 mm to obtain a test piece. The breaking elongation and tensile modulus of the test piece are measured at 23°C in accordance with JIS K7161:2014 and JIS K7127:1999. Specifically, the test piece is subjected to a tensile test at a speed of 200 mm/min using a tensile tester (manufactured by Shimadzu Corporation, product name "Autograph AG-IS 500N") with the chuck distance set to 100 mm, and the breaking elongation (%) and tensile modulus (MPa) are measured. The measurements are performed in both the machine direction (MD) during the manufacture of the substrate and the direction perpendicular to the machine direction (CD).

(Physical properties of adhesive sheet)
When the pressure-sensitive adhesive sheet according to the present embodiment is stretched in a first direction, a second direction opposite to the first direction, a third direction perpendicular to the first direction, and a fourth direction opposite to the third direction, and the area ratio (S2/S1)×100 of the area S1 of the pressure-sensitive adhesive sheet before stretching to the area S2 of the pressure-sensitive adhesive sheet after stretching is 300%, it is preferable that the substrate and the pressure-sensitive adhesive layer do not break. The first direction, the second direction, the third direction, and the fourth direction each preferably correspond to, for example, the four directions of +X-axis, -X-axis, +Y-axis, and -Y-axis directions of biaxial stretching described later. An example of an apparatus for stretching in the four directions is an expanding apparatus described later.

(Release sheet)
The pressure-sensitive adhesive sheet according to the present embodiment may have a release sheet laminated on the adhesive surface for the purpose of protecting the adhesive surface until the adhesive surface of the pressure-sensitive adhesive layer is attached to an adherend (e.g., a semiconductor chip, etc.). The configuration of the release sheet is arbitrary. An example of the release sheet is a plastic film that has been subjected to a release treatment using a release agent or the like.
Specific examples of the plastic film include polyester films and polyolefin films. Examples of the polyester film include films of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Examples of the polyolefin film include films of polypropylene and polyethylene.
The release agent may be a silicone-based, fluorine-based, or long-chain alkyl-based agent, etc. Among these release agents, the silicone-based agent is preferred because it is inexpensive and provides stable performance.
The thickness of the release sheet is not particularly limited, but is usually 20 μm or more and 250 μm or less.

(Method of manufacturing pressure-sensitive adhesive sheet)
The pressure-sensitive adhesive sheet according to this embodiment can be produced in the same manner as a conventional pressure-sensitive adhesive sheet.
The method for producing the pressure-sensitive adhesive sheet is not particularly limited as long as it is possible to laminate the above-mentioned pressure-sensitive adhesive layer on one surface of the substrate.
An example of a method for producing a pressure-sensitive adhesive sheet is as follows. First, a coating liquid containing a pressure-sensitive adhesive composition constituting a pressure-sensitive adhesive layer and, if desired, a solvent or a dispersion medium is prepared. Next, the coating liquid is applied to one surface of a substrate by a coating means to form a coating film. Examples of the coating means include a die coater, a curtain coater, a spray coater, a slit coater, and a knife coater. Next, the coating film is dried to form a pressure-sensitive adhesive layer. The properties of the coating liquid are not particularly limited as long as it can be applied. The coating liquid may contain a component for forming the pressure-sensitive adhesive layer as a solute, or may contain a component for forming the pressure-sensitive adhesive layer as a dispersoid.

Another example of a method for manufacturing a pressure-sensitive adhesive sheet is as follows. First, a coating liquid is applied onto the release surface of the release sheet to form a coating film. Next, the coating film is dried to form a laminate consisting of a pressure-sensitive adhesive layer and a release sheet. Next, a substrate may be attached to the surface of the pressure-sensitive adhesive layer of this laminate opposite to the release sheet side to obtain a laminate of the pressure-sensitive adhesive sheet and the release sheet. The release sheet in this laminate may be peeled off as a processing material, or may protect the pressure-sensitive adhesive layer until an adherend (e.g., a semiconductor chip, a semiconductor wafer, etc.) is attached to the pressure-sensitive adhesive layer.

When the coating liquid contains a crosslinking agent, the crosslinking reaction between the (meth)acrylic copolymer (b1) in the coating film and the crosslinking agent can be advanced by changing the drying conditions (e.g., temperature, time, etc.) of the coating film or by separately carrying out a heat treatment, and a crosslinked structure can be formed at the desired density in the adhesive layer. In order to advance this crosslinking reaction sufficiently, after laminating the adhesive layer on the substrate by the above-mentioned method, the obtained adhesive sheet can be cured by, for example, leaving it in an environment of 23°C and a relative humidity of 50% for several days.

The thickness of the adhesive sheet according to this embodiment is preferably 30 μm or more, and more preferably 50 μm or more. The thickness of the adhesive sheet is preferably 400 μm or less, and more preferably 300 μm or less.

[How to use the adhesive sheet]
Since the pressure-sensitive adhesive sheet according to the present embodiment can be attached to various adherends, the adherend to which the pressure-sensitive adhesive sheet according to the present embodiment can be applied is not particularly limited. For example, the adherend is preferably a semiconductor chip or a semiconductor wafer.

The pressure-sensitive adhesive sheet according to this embodiment can be used, for example, for semiconductor processing.
Furthermore, the adhesive sheet according to this embodiment can be used to increase the spacing between multiple semiconductor chips attached to one surface.

The expansion interval between multiple semiconductor chips is not particularly limited, since it depends on the size of the semiconductor chip. The adhesive sheet of this embodiment is preferably used to expand the mutual interval between adjacent semiconductor chips in multiple semiconductor chips attached to one side of the adhesive sheet by 200 μm or more. The upper limit of the mutual interval between the semiconductor chips is not particularly limited. The upper limit of the mutual interval between the semiconductor chips may be, for example, 6000 μm.

The adhesive sheet according to the present embodiment can also be used to expand the spacing between multiple semiconductor chips stacked on one side of the adhesive sheet by at least biaxial stretching. In this case, the adhesive sheet is stretched by applying tension in four directions, for example, the +X-axis direction, the -X-axis direction, the +Y-axis direction, and the -Y-axis direction of the mutually perpendicular X-axis and Y-axis, and more specifically, the adhesive sheet is stretched in each of the MD direction and CD direction of the substrate.

The biaxial stretching described above can be carried out, for example, by using a spacing device that applies tension in the X-axis direction and the Y-axis direction. Here, the X-axis and the Y-axis are assumed to be perpendicular to each other, with one of the directions parallel to the X-axis being the +X-axis direction, the direction opposite to the +X-axis direction being the -X-axis direction, one of the directions parallel to the Y-axis being the +Y-axis direction, and the direction opposite to the +Y-axis direction being the -Y-axis direction.

The spacing device preferably applies tension to the adhesive sheet in four directions, the +X-axis direction, the -X-axis direction, the +Y-axis direction, and the -Y-axis direction, and is provided with a plurality of holding means and a corresponding plurality of tension applying means for each of the four directions. The number of holding means and tension applying means in each direction depends on the size of the adhesive sheet, but may be, for example, 3 or more and 10 or less.

Here, for example, in a group including a plurality of holding means and a plurality of tension applying means provided for applying tension in the +X-axis direction, each holding means preferably includes a holding member for holding the adhesive sheet, and each tension applying means preferably applies tension to the adhesive sheet by moving the holding member corresponding to the tension applying means in the +X-axis direction. The plurality of tension applying means are preferably each independently provided to move the holding means in the +X-axis direction. Also, it is preferable that the three groups including a plurality of holding means and a plurality of tension applying means provided for applying tension in the -X-axis direction, +Y-axis direction, and -Y-axis direction, respectively, have the same configuration. This allows the spacing device to apply tension of different magnitudes to the adhesive sheet for each region in a direction perpendicular to each direction.

In general, when an adhesive sheet is held in four directions, +X-axis direction, -X-axis direction, +Y-axis direction, and -Y-axis direction, using four holding members, and stretched in these four directions, tension is applied to the adhesive sheet not only in these four directions, but also in their combined direction (for example, the combined direction of +X-axis direction and +Y-axis direction, the combined direction of +Y-axis direction and -X-axis direction, the combined direction of -X-axis direction and -Y-axis direction, and the combined direction of -Y-axis direction and +X-axis direction). As a result, a difference may occur between the spacing between the semiconductor chips in the inner region of the adhesive sheet and the spacing between the semiconductor chips in the outer region.

However, in the spacing device described above, multiple tension applying means can independently apply tension to the adhesive sheet in each of the +X axis direction, -X axis direction, +Y axis direction, and -Y axis direction, so that the adhesive sheet can be stretched so as to eliminate the difference in spacing between the inside and outside of the adhesive sheet as described above.
As a result, the spacing between the semiconductor chips can be adjusted accurately.

It is preferable that the spacing device further comprises a measuring means for measuring the mutual spacing between the semiconductor chips. Here, it is preferable that the tension applying means is provided so that the multiple holding members can be moved individually based on the measurement results of the measuring means. By providing the spacing device with a measuring means, it becomes possible to further adjust the spacing based on the measurement results of the spacing between the semiconductor chips by the measuring means, and as a result, it becomes possible to adjust the spacing between the semiconductor chips more accurately.

In the above-mentioned separation device, examples of the holding means include chuck means and decompression means. Examples of the chuck means include a mechanical chuck and a chuck cylinder. Examples of the decompression means include a decompression pump and a vacuum ejector. In the above-mentioned separation device, the holding means may be configured to support the adhesive sheet with adhesive or magnetic force. In addition, as the holding member in the chuck means, for example, a holding member having a configuration including a lower support member that supports the adhesive sheet from below, a driving device supported by the lower support member, and an upper support member that is supported by the output shaft of the driving device and can press the adhesive sheet from above by driving the driving device can be used. Examples of the driving device include electric devices and actuators. Examples of the electric devices include rotary motors, linear motors, linear motors, single-axis robots, and multi-joint robots. Examples of the actuators include air cylinders, hydraulic cylinders, rodless cylinders, and rotary cylinders.

In the above-mentioned separation device, the tension applying means may include a driving device, and the holding member may be moved by the driving device. The driving device included in the tension applying means may be the same as the driving device included in the holding member described above. For example, the tension applying means may include a linear motor as the driving device, and an output shaft interposed between the linear motor and the holding member, and the driven linear motor may move the holding member via the output shaft.

When the adhesive sheet of this embodiment is used to increase the spacing between semiconductor chips, the spacing may be increased from a state in which the semiconductor chips are in contact with each other or from a state in which the spacing between the semiconductor chips has barely been increased, or the spacing between the semiconductor chips may be increased further from a state in which the spacing between the semiconductor chips has already been increased to a predetermined spacing.

When expanding the spacing between semiconductor chips from a state in which the semiconductor chips are in contact with each other or from a state in which the spacing between the semiconductor chips has barely expanded, for example, a semiconductor wafer is divided on a dicing sheet to obtain multiple semiconductor chips, and then the multiple semiconductor chips are transferred from the dicing sheet to the adhesive sheet according to this embodiment, and the spacing between the semiconductor chips can be expanded. Alternatively, a semiconductor wafer is divided on the adhesive sheet according to this embodiment to obtain multiple semiconductor chips, and then the spacing between the semiconductor chips can be expanded.

In the case where the distance between the semiconductor chips is to be further increased from a state in which the distance between the semiconductor chips has already been increased to a predetermined distance, the distance between the semiconductor chips can be increased to a predetermined distance using another adhesive sheet, preferably the adhesive sheet according to this embodiment (first stretching adhesive sheet), and then the semiconductor chips can be transferred from the sheet (first stretching adhesive sheet) to the adhesive sheet according to this embodiment (second stretching adhesive sheet), and then the adhesive sheet according to this embodiment (second stretching adhesive sheet) is stretched, thereby further increasing the distance between the semiconductor chips. Note that such transfer of the semiconductor chips and stretching of the adhesive sheet may be repeated multiple times until the distance between the semiconductor chips reaches the desired distance.

[Method of manufacturing semiconductor wafer level package (FO-WLP)]
The pressure-sensitive adhesive sheet according to the present embodiment is preferably used in applications requiring a relatively large distance between semiconductor chips, and a preferred example of such an application is a method for manufacturing a fan-out type semiconductor wafer level package (FO-WLP). An example of the method for manufacturing such a FO-WLP is the first embodiment described below.

(First aspect)
A first embodiment of the method for producing a FO-WLP using the pressure-sensitive adhesive sheet according to the present embodiment will be described below. In this first embodiment, the pressure-sensitive adhesive sheet according to the present embodiment is used as a first pressure-sensitive adhesive sheet 10, which will be described later.

Figure 1A shows a first adhesive sheet 10 and a number of semiconductor chips CP attached to the first adhesive sheet 10.

The first adhesive sheet 10 has a first substrate 11 and a first adhesive layer 12. The first substrate 11 corresponds to the substrate of the adhesive sheet according to the present embodiment. The first adhesive layer 12 corresponds to the adhesive layer of the adhesive sheet according to the present embodiment. The first substrate 11 has a first substrate surface 11A and a second substrate surface 11B opposite to the first substrate surface 11A. The first adhesive layer 12 is provided on the first substrate surface 11A. No adhesive layer is provided on the second substrate surface 11B.
In this embodiment, the first pressure-sensitive adhesive sheet 10 is used as an expandable sheet.

The semiconductor chip CP has a circuit surface W1 and a back surface W3 opposite the circuit surface W1. A circuit W2 is formed on the circuit surface W1.

The multiple semiconductor chips CP are preferably formed by, for example, dicing a semiconductor wafer into individual pieces.
Dicing is preferably performed on a semiconductor wafer attached to a dicing sheet etc. Cutting means such as a dicing saw is used for dicing.
Instead of using the above-mentioned cutting means, the dicing may be performed by irradiating the semiconductor wafer with a laser beam. For example, the semiconductor wafer may be completely divided by irradiation with a laser beam to be divided into a plurality of semiconductor chips.
Alternatively, after forming a modified layer inside the semiconductor wafer by irradiating the laser light, the semiconductor wafer may be broken at the position of the modified layer by stretching the adhesive sheet in the expanding process described later, and divided into semiconductor chips CP. The method of dividing into semiconductor chips in this manner may be called stealth dicing. In the case of stealth dicing, the laser light is irradiated so that, for example, infrared laser light is focused on a focal point set inside the semiconductor wafer. In these methods, the laser light may be irradiated from either side of the semiconductor wafer.
After dicing, the multiple semiconductor chips CP are preferably transferred collectively to an expandable sheet.

In this embodiment, the multiple individual semiconductor chips CP are transferred from the dicing sheet to the first adhesive sheet 10. The multiple semiconductor chips CP are attached with their circuit surfaces W1 facing the first adhesive layer 12.

Figure 1B shows a diagram illustrating the process of stretching the first adhesive sheet 10 holding multiple semiconductor chips CP (hereinafter sometimes referred to as the "expanding process").

The first adhesive sheet 10 is stretched to increase the spacing between the multiple semiconductor chips CP. When stealth dicing is performed, the first adhesive sheet 10 is stretched to break the semiconductor wafer at the modified layer, dividing it into multiple semiconductor chips CP, and increasing the spacing between the multiple semiconductor chips CP.

The method of stretching the first adhesive sheet 10 in the expanding step is not particularly limited. Examples of methods of stretching the first adhesive sheet 10 include a method of pressing an annular or circular expander against the first adhesive sheet 10 to stretch it, and a method of gripping and stretching the outer periphery of the first adhesive sheet 10 using a gripping member or the like. An example of the latter method is a biaxial stretching method using the aforementioned spacing device or the like. Among these methods, the biaxial stretching method is preferred from the viewpoint of making it possible to expand the gap between the semiconductor chips CP more widely.

As shown in FIG. 1B, the distance between the semiconductor chips CP after expansion is D1. The distance D1 is not particularly limited because it depends on the size of the semiconductor chips CP. It is preferable that the distance D1 is, for example, independently 200 μm or more and 6000 μm or less.

After the expanding step, a step is carried out in which the first adhesive sheet 10 is irradiated with energy rays to harden the first adhesive layer 12 (hereinafter sometimes referred to as the "energy ray irradiation step"). If the first adhesive layer 12 is ultraviolet-curable, the first adhesive sheet 10 is irradiated with ultraviolet rays in the energy ray irradiation step. By hardening the first adhesive layer 12 after the expanding step, the shape retention of the first adhesive sheet 10 after stretching is improved. As a result, the alignment of the multiple semiconductor chips CP attached to the first adhesive layer 12 is easily maintained.

2A shows a diagram for explaining the process of transferring a plurality of semiconductor chips CP to a second adhesive sheet 20 after the expanding process (hereinafter, sometimes referred to as the "transfer process"). Since the first adhesive layer 12 is cured after the first expanding process, the adhesive strength of the first adhesive layer 12 is reduced, making it easier to peel the first adhesive sheet 10 from the semiconductor chips CP. Furthermore, since the first adhesive sheet 10 is the adhesive sheet according to this embodiment, adhesive residue on the semiconductor chips CP can be suppressed.
After the first adhesive sheet 10 is stretched to expand the interval between the multiple semiconductor chips CP to a distance D1, the second adhesive sheet 20 is attached to the back surface W3 of the semiconductor chip CP. Here, the second adhesive sheet 20 is not particularly limited as long as it can hold the multiple semiconductor chips CP. If it is desired to further expand the distance D1 between the multiple semiconductor chips CP, it is preferable to use an expandable sheet as the second adhesive sheet 20, and it is more preferable to use the adhesive sheet of this embodiment.

The second pressure-sensitive adhesive sheet 20 has a second substrate 21 and a third pressure-sensitive adhesive layer 22 .
When the adhesive sheet of this embodiment is used as the second adhesive sheet 20, the second substrate 21 corresponds to the substrate of the adhesive sheet of this embodiment, and the third adhesive layer 22 corresponds to the adhesive layer of the adhesive sheet of this embodiment.

The second adhesive sheet 20 may be attached to a second ring frame together with multiple semiconductor chips CP. In this case, the second ring frame is placed on the third adhesive layer 22 of the second adhesive sheet 20 and lightly pressed to fix it. Then, the third adhesive layer 22 exposed on the inside of the ring shape of the second ring frame is pressed against the back surface W3 of the semiconductor chip CP to fix the multiple semiconductor chips CP to the second adhesive sheet 20.

FIG. 2B is a diagram illustrating the step of peeling off first adhesive sheet 10 after second adhesive sheet 20 has been attached.
After the second adhesive sheet 20 is attached, the circuit surfaces W1 of the semiconductor chips CP are exposed by peeling off the first adhesive sheet 10. It is preferable that the distance D1 between the semiconductor chips CP expanded in the expanding step is maintained even after the first adhesive sheet 10 is peeled off.

When the second adhesive sheet 20 is an expandable sheet, a step of stretching the second adhesive sheet 20 (hereinafter sometimes referred to as a "second expanding step") may be carried out after peeling off the first adhesive sheet 10. In this case, the expanding step of stretching the first adhesive sheet 10 may be referred to as a first expanding step.
In the second expanding step, the spaces between the multiple semiconductor chips CP are further expanded.
When the second adhesive sheet 20 is the adhesive sheet according to this embodiment, the alignment of the multiple semiconductor chips CP after expansion is improved.

The method for stretching the second adhesive sheet 20 in the second expansion process is not particularly limited. For example, the second expansion process can be carried out in the same manner as the first expansion process.

The distance between the semiconductor chips CP after the second expanding process is designated as D2. The distance D2 is not particularly limited because it depends on the size of the semiconductor chip CP, but the distance D2 is greater than the distance D1. It is preferable that the distances D2 are, for example, independently 200 μm or more and 6000 μm or less.

2C is a diagram illustrating a process (hereinafter sometimes referred to as a "transfer process") of transferring a plurality of semiconductor chips CP attached to the second adhesive sheet 20 to a third adhesive sheet 30. When the second adhesive sheet 20 is the adhesive sheet according to this embodiment, adhesive residue of the semiconductor chips CP can be suppressed.
2C shows a state where the semiconductor chips CP are transferred from the second adhesive sheet 20 to the third adhesive sheet 30 without carrying out the second expanding step. The third adhesive sheet 30 is not particularly limited as long as it is capable of holding a plurality of semiconductor chips CP.

It is preferable that the distance D1 between the semiconductor chips CP is maintained for the multiple semiconductor chips CP transferred from the second adhesive sheet 20 to the third adhesive sheet 30. When the second expansion process is performed, it is preferable that the distance D2 between the semiconductor chips CP is maintained.

After the first expanding process, the transfer process and expanding process can be repeated any number of times to set the distance between the semiconductor chips CP to the desired distance and to set the orientation of the circuit surface when sealing the semiconductor chip CP to the desired orientation.

When it is desired to seal multiple semiconductor chips CP on the third adhesive sheet 30, it is preferable to use an adhesive sheet for the sealing process as the third adhesive sheet 30, and it is more preferable to use an adhesive sheet having heat resistance.

The third pressure-sensitive adhesive sheet 30 has a third substrate 31 and a fourth pressure-sensitive adhesive layer 32 .
In addition, when a heat-resistant adhesive sheet is used as the third adhesive sheet 30, the third substrate 31 and the fourth adhesive layer 32 are preferably formed of a material having heat resistance capable of withstanding the temperature applied in the sealing process. Another embodiment of the third adhesive sheet 30 is an adhesive sheet having a third substrate, a third adhesive layer, and a fourth adhesive layer. This adhesive sheet includes a third substrate between the third adhesive layer and the fourth adhesive layer, and has adhesive layers on both sides of the third substrate.

The multiple semiconductor chips CP transferred from the second adhesive sheet 20 to the third adhesive sheet 30 are attached with their circuit surfaces W1 facing the fourth adhesive layer 32.

Figure 2D shows a diagram illustrating the process of sealing multiple semiconductor chips CP using a sealing member 60 (hereinafter sometimes referred to as the "sealing process").

In this embodiment, the sealing process is performed after the multiple semiconductor chips CP are transferred to the third adhesive sheet 30.
In the sealing process, the semiconductor chips CP are covered with the sealing member 60 while the circuit surface W1 is protected by the third adhesive sheet 30, thereby forming the sealing body 3. The sealing member 60 is also filled between the semiconductor chips CP. Since the circuit surface W1 and the circuit W2 are covered by the third adhesive sheet 30, the circuit surface W1 can be prevented from being covered by the sealing member 60.

The sealing process produces a sealing body 3 in which multiple semiconductor chips CP spaced apart at a predetermined distance are embedded in the sealing member 60. In the sealing process, it is preferable that the multiple semiconductor chips CP are covered by the sealing member 60 while maintaining the distance therebetween after the expansion process is performed.

After the sealing process, the third adhesive sheet 30 is peeled off. The circuit surface W1 of the semiconductor chip CP and the surface 3A of the sealing body 3 that was in contact with the third adhesive sheet 30 are exposed.

After the adhesive sheet is peeled off from the sealing body 3, a rewiring layer forming process for forming a rewiring layer electrically connected to the semiconductor chip CP and a connection process for electrically connecting the rewiring layer and the external terminal electrodes are sequentially performed on the sealing body 3. The rewiring layer forming process and the connection process with the external terminal electrodes electrically connect the circuit of the semiconductor chip CP to the external terminal electrodes.
The sealing body 3 to which the external terminal electrodes are connected is diced into individual semiconductor chips CP. The method for dicing the sealing body 3 is not particularly limited. By dicing the sealing body 3, a semiconductor package is manufactured for each semiconductor chip CP. The semiconductor package to which the external electrodes fanned out to the outside of the region of the semiconductor chip CP are connected is manufactured as a fan-out type wafer level package (FO-WLP).

The adhesive sheet according to this embodiment can suppress adhesive residue. Therefore, it can be suitably used in applications where it is necessary to greatly expand the spacing between multiple semiconductor chips and transfer the expanded multiple semiconductor chips to another component, as described above.

[Modifications of the embodiment]
The present invention is not limited to the above-described embodiment, and includes modifications of the above-described embodiment within the scope of the invention.

For example, circuits in a semiconductor wafer or semiconductor chip are not limited to the arrangement or shape shown in the figure. The connection structure with external terminal electrodes in a semiconductor package is also not limited to the aspects described in the above-mentioned embodiment. In the above-mentioned embodiment, an aspect of manufacturing a FO-WLP type semiconductor package was described as an example, but the present invention can also be applied to aspects of manufacturing other semiconductor packages, such as a fan-in type WLP.

In the manufacturing method for the FO-WLP according to the first aspect described above, some steps may be modified or some steps may be omitted.

In the above embodiment, an adhesive sheet in which the adhesive layer according to the above embodiment is provided on one of the first substrate surface and the second substrate surface, and no adhesive layer is provided on the other surface, has been described as an example, but the present invention is not limited to such an embodiment.
For example, a pressure-sensitive adhesive sheet having pressure-sensitive adhesive layers provided on both sides of a substrate can be mentioned, and at least one of the pressure-sensitive adhesive layers is the pressure-sensitive adhesive layer according to the above embodiment.
For example, pressure-sensitive adhesive sheet 10A is shown in Fig. 4. Pressure-sensitive adhesive sheet 10A has a substrate 110, a first pressure-sensitive adhesive layer 12, and a second pressure-sensitive adhesive layer 13. Pressure-sensitive adhesive sheet 10A includes substrate 110 between first pressure-sensitive adhesive layer 12 and second pressure-sensitive adhesive layer 13.
A first pressure-sensitive adhesive layer 12 is provided on a first substrate surface 11A of the substrate 110, and a second pressure-sensitive adhesive layer 13 is provided on a second substrate surface 11B.
The substrate 110 is the same as the first substrate 11 in the above embodiment.
The first pressure-sensitive adhesive layer 12 corresponds to the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to the embodiment. The second pressure-sensitive adhesive layer 13 is not particularly limited.
The compositions of the first pressure-sensitive adhesive layer 12 and the second pressure-sensitive adhesive layer 13 may be the same or different.
The thicknesses of the first pressure-sensitive adhesive layer 12 and the second pressure-sensitive adhesive layer 13 may be the same or different.

The present invention will be described in more detail below with reference to examples. The present invention is not limited to these examples.

[Preparation of adhesive sheet]
Example 1
An acrylic copolymer was obtained by copolymerizing 52 parts by mass of butyl acrylate (BA), 20 parts by mass of methyl methacrylate (MMA), and 28 parts by mass of 2-hydroxyethyl acrylate (2HEA). A solution of a resin (acrylic A) (adhesive base) was prepared by adding 2-isocyanatoethyl methacrylate (manufactured by Showa Denko K.K., product name "Karens MOI" (registered trademark)) to this acrylic copolymer. The addition ratio was 90 mol % of 2-isocyanatoethyl methacrylate to 100 mol % of 2HEA in the acrylic copolymer.
The weight average molecular weight (Mw) of the obtained resin (acrylic A) was 600,000, and Mw/Mn was 4.5. The weight average molecular weight Mw and number average molecular weight Mn in terms of standard polystyrene were measured by gel permeation chromatography (GPC), and the molecular weight distribution (Mw/Mn) was calculated from the respective measured values.
To this adhesive base, an energy ray curable resin A (manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., product name "SA-TE60"), a photopolymerization initiator (manufactured by IGM Resins B.V., product name "Omnirad 127D") and a crosslinking agent (manufactured by Toyochem Co., Ltd., TMP-TDI (trimethylolpropane adduct of tolylene diisocyanate)) were added in the ratios shown below, and ethyl acetate was further added, followed by stirring for 30 minutes to prepare an adhesive composition A1 with a solid content of 35.0 mass %.
Adhesive base: 100 parts by weight of solid content Energy ray curable resin A: 51.4 parts by weight of solid content Photopolymerization initiator: 3.7 parts by weight of solid content Crosslinking agent: 0.2 parts by weight of solid content

Next, the prepared solution of adhesive composition A1 was applied to a polyethylene terephthalate (PET)-based release film (manufactured by Lintec Corporation, product name "PET752150"), and the coating was dried at 90°C for 90 seconds and further dried at 100°C for 90 seconds to form a 30 µm-thick adhesive layer on the release film.
A urethane substrate (manufactured by Kurabo Industries, Ltd., product name "U-1490", thickness 100 μm, hardness 90 degrees (A type)) was bonded to the adhesive layer, and unnecessary portions of the ends in the width direction were cut and removed to produce adhesive sheet SA1.
The properties of the energy ray curable resin are shown in Table 1.

Example 2
An adhesive sheet SA2 according to Example 2 was produced in the same manner as in Example 1, except that in producing the adhesive sheet SA1 according to Example 1, energy ray curable resin B (manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., product name "SA-TE6") was used instead of energy ray curable resin A ("SA-TE60").

Example 3
In producing the adhesive sheet SA1 of Example 1, the adhesive sheet SA3 of Example 3 was produced in the same manner as in Example 1, except that the energy ray curable resin C (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "ATM-35E") was used instead of the energy ray curable resin A ("SA-TE60") in the production of the adhesive sheet SA1 of Example 1.

Example 4
In producing the adhesive sheet SA1 of Example 1, the adhesive sheet SA4 of Example 4 was produced in the same manner as in Example 1, except that the energy ray curable resin D (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "A-GLY-9E") was used instead of the energy ray curable resin A ("SA-TE60") in the production of the adhesive sheet SA1 of Example 1.

(Comparative Example 1)
In producing the adhesive sheet SA1 of Example 1, an adhesive sheet R-SA1 of Comparative Example 1 was produced in the same manner as in Example 1, except that energy ray curable resin E (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "A-DOD-N") was used instead of energy ray curable resin A ("SA-TE60") in the production of the adhesive sheet SA1 of Example 1.

(Comparative Example 2)
An adhesive sheet R-SA2 according to Comparative Example 2 was produced in the same manner as in Example 1, except that in producing the adhesive sheet SA1 according to Example 1, energy ray curable resin F (manufactured by Mitsubishi Chemical Corporation, product name "UV-5806") was used instead of energy ray curable resin A ("SA-TE60").

[Evaluation of Adhesive Sheet]
The produced pressure-sensitive adhesive sheets were subjected to the following evaluations. The evaluation results are shown in Table 1.

(Method of Evaluating Alignment)
The pressure-sensitive adhesive sheets produced in Examples 1 to 4 and Comparative Examples 1 and 2 were cut to 210 mm x 210 mm to obtain test pressure-sensitive adhesive sheets, in such a way that each side of the cut sheet was parallel or perpendicular to the MD direction of the substrate in the pressure-sensitive adhesive sheet.
The silicon wafer was diced to cut out a total of 49 chips, each measuring 3 mm×3 mm, in seven rows in the X-axis direction and seven rows in the Y-axis direction.
The release film of the test adhesive sheet was peeled off, and a total of 49 chips cut out as described above were attached to the center of the exposed adhesive layer. At this time, the chips were arranged in 7 rows in the X-axis direction and 7 rows in the Y-axis direction, and the distance between the chips was 35 μm in both the X-axis direction and the Y-axis direction.

Next, the test adhesive sheet with the chips attached was placed in a biaxially stretchable expanding device (spacing device). FIG. 3 shows a plan view of the expanding device 100. In FIG. 3, the X-axis and the Y-axis are perpendicular to each other, with the positive direction of the X-axis being the +X-axis direction, the negative direction of the X-axis being the -X-axis direction, the positive direction of the Y-axis being the +Y-axis direction, and the negative direction of the Y-axis being the -Y-axis direction. The test adhesive sheet 200 was placed in the expanding device 100 so that each side was parallel to the X-axis or Y-axis. As a result, the MD direction of the substrate in the test adhesive sheet 200 was parallel to the X-axis or Y-axis. Note that the chips are omitted in FIG. 3.

3, the expanding device 100 has five holding means 101 in each of the +X-axis direction, -X-axis direction, +Y-axis direction, and -Y-axis direction (a total of 20 holding means 101). Of the five holding means 101 in each direction, holding means 101A are located at both ends, holding means 101C is located in the center, and holding means 101B is located between holding means 101A and holding means 101C. Each side of the test adhesive sheet 200 was gripped by these holding means 101.

As shown in Figure 3, one side of the test adhesive sheet 200 is 210 mm. The distance between the holding means 101 on each side is 40 mm. The distance between the end of one side of the test adhesive sheet 200 (the apex of the sheet) and the holding means 101A on that side that is closest to that end is 25 mm.

First expansion test Next, a plurality of tension applying means (not shown) corresponding to each of the holding means 101 were driven to move the holding means 101 independently. The four sides of the test pressure-sensitive adhesive sheet were fixed with a gripping jig, and the test pressure-sensitive adhesive sheet was expanded by an expansion amount of 200 mm at a speed of 5 mm/s in each of the X-axis direction and the Y-axis direction. As a result of the first expansion test, the area of the test pressure-sensitive adhesive sheet was expanded to 381% of that before expansion. In this embodiment, this expansion test with an expansion amount of 200 mm may be referred to as the first expansion test. After the first expansion test, the substrate and the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheets according to Examples 1 to 4 were not broken.

Second Expand Test The test pressure-sensitive adhesive sheet was expanded in the same manner as in the first expand test, except that the expansion amount in the X-axis direction and the Y-axis direction in the first expand test was changed to 350 mm. As a result of the second expand test, the area of the test pressure-sensitive adhesive sheet was expanded to 711% of that before expansion. In this embodiment, this expand test with an expansion amount of 350 mm may be referred to as the second expand test. The second expand test was performed on pressure-sensitive adhesive sheets whose alignment evaluation was evaluation A, which will be described later, as a result of the first expand test. After the second expand test, the substrate and the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheets according to Examples 1 to 3 did not break.

After the test pressure-sensitive adhesive sheet was expanded by the first expansion test or the second expansion test, the expanded state of the test pressure-sensitive adhesive sheet 200 was maintained by a ring frame.
The alignment was evaluated by calculating the standard deviation of the chip-to-chip distance based on the positional relationship between the chips while maintaining the expanded state. Specifically, the center of each chip was determined from the corner of the chip, and the center-to-center distance between adjacent chips was measured. The chip-to-chip distance was determined by subtracting 3 mm, which is the length of the chip side, from the center-to-center distance. The position of the chip on the test adhesive sheet was measured using a CNC image measuring machine (manufactured by Mitutoyo Corporation, product name "Vision ACCEL"). The standard deviation was calculated using data analysis software JMP13 manufactured by JMP. The evaluation criteria for alignment were set as follows. In this embodiment, evaluation A or evaluation B was judged to be pass.
Evaluation criteria for alignment: Evaluation A: Standard deviation is 100 μm or less; Evaluation B: Standard deviation is 200 μm or less; Evaluation C: Standard deviation is 201 μm or more

(Evaluation method for tip lift)
After expanding the test adhesive sheet by the first expand test in the description of the alignment evaluation method described above, the expanded state of the test adhesive sheet 200 was maintained by a ring frame. With the expanded state maintained, the bonding state between the adhesive layer side surface of the chip and the adhesive layer was observed through the test adhesive sheet 200 using a digital microscope (manufactured by Keyence Corporation, product name "VHX-1000"). The evaluation criteria for chip lifting were set as follows. In this example, evaluation A was judged to be acceptable.
Evaluation Criteria for Chip Lifting Evaluation A: None of the chips are lifted from the adhesive sheet (the ends of the chips are not separated from the adhesive layer).
Rating B: At least one chip is floating from the adhesive sheet (an end of the chip is separated from the adhesive layer).

(Method for evaluating adhesive bleeding)
A roll sample of a long adhesive sheet was prepared using the adhesive composition, long release film, and urethane substrate prepared in the above-mentioned Examples or Comparative Examples. Next, the adhesive sheet unwound from the roll sample was cut to a width of 35 mm, and the cut adhesive sheet was wound up on a 3-inch ABS core for 25 m to obtain a test roll sample. This test roll sample was left in a thermostatic chamber at 40° C. for 48 hours, and the state of the cut surface was examined by touch. The evaluation criteria for the bleeding of the adhesive were set as follows. In this example, evaluation A was judged to be acceptable.
- Evaluation criteria for bleeding Evaluation A: No tackiness on cut surface Evaluation B: Tackiness on cut surface

(SS properties: breaking elongation and stress before UV curing)
Only the adhesive layer of the adhesive sheets of Examples 1 to 4 and Comparative Examples 1 and 2 was laminated to prepare samples for evaluating SS characteristics having a thickness of 200 μm, a width of 15 mm, and a length of 50 mm. The samples for evaluating SS characteristics were then fixed with a chuck to a tensile tester with the chuck distance adjusted to 30 mm. The samples for evaluating SS characteristics fixed with the chuck were pulled at a speed of 50 mm/min, and the displacement and stress at that time were recorded. A displacement-stress curve was created based on the recorded displacement and stress. The tensile tester used was an "Autograph AG-IS 500N" manufactured by Shimadzu Corporation.
The displacement at which the sample for evaluating SS characteristics broke was taken as the breaking elongation (unit: %). In Table 1, the entry ">2000" indicates that the sample for evaluating SS characteristics did not break even when the displacement was 2000%.
Table 1 shows the stress (unit: MPa) at 1500% displacement in the displacement-stress curve.
The evaluation criteria for the SS characteristics were set as follows: In this example, evaluation A was determined as passing.
Evaluation criteria for SS characteristics: Evaluation A: The breaking elongation was 1500% or more, and the stress at 1500% displacement was 0.22 MPa or less.
Evaluation B: Corresponded to at least one of the cases where the breaking elongation was less than 1500% and the stress at 1500% displacement exceeded 0.22 MPa.

(SS properties: breaking energy after UV curing)
The breaking energy E (unit: J) after UV curing was obtained by a tensile test at 23° C. based on JIS K7161:1994 and JIS K 7127:1999.
First, a sheet-like adhesive layer before UV curing having a thickness of 40 μm, a width of 15 mm, and a length of 150 mm was prepared by laminating only the adhesive layers of the adhesive sheets of Examples 1 to 4 and Comparative Examples 1 and 2. This sheet-like adhesive layer before UV curing was irradiated with ultraviolet (UV) rays to prepare a sample for evaluating the SS characteristics after UV curing.
・Ultraviolet irradiation conditions: 220mW/cm ² , 160mJ/cm ²
Thereafter, the sample for evaluation of UV-cured SS characteristics was fixed with a chuck in a tensile testing machine with the chuck distance adjusted to 100 mm. The sample for evaluation of UV-cured SS characteristics fixed with the chuck was pulled at a speed of 50 mm/min, and the displacement and stress at that time were recorded. A displacement-stress curve was created based on the recorded displacement and stress. The tensile testing machine used was an "Autograph AG-IS 500N" manufactured by Shimadzu Corporation.
The displacement at the time when the sample for evaluating SS characteristics after UV curing broke was defined as the breaking elongation (unit: %).
The breaking energy E (unit: J) after UV curing was calculated using a spreadsheet software according to the following formula (A).

In the above formula (A), the constant a is the breaking point displacement (unit: mm), and f(x) is the stress (unit: N) at the displacement x (unit: mm). The sampling rate for measuring the breaking energy E was 1 time/0.05 sec (20 Hz).

(Method for evaluating adhesive residue)
After expanding the test pressure-sensitive adhesive sheet in the first expand test in the above-mentioned evaluation of alignment, it was irradiated with ultraviolet light under the following irradiation conditions.
・Ultraviolet irradiation conditions: 220mW/cm ² , 160mJ/cm ²
After the ultraviolet irradiation, the chip was peeled off from the test adhesive sheet using UV-curable tape D-218 manufactured by Lintec Corporation.
The chip surface that had been in contact with the adhesive layer was observed at 100x optical magnification using a digital microscope (manufactured by Keyence Corporation, product name "VHX-1000").
The criterion for determining whether or not there was adhesive residue was that if there was one or more adhesive residues in one chip, it was counted as a chip with adhesive residue. The evaluation criteria for adhesive residue were set as follows. In this example, evaluation A or evaluation B was determined to be acceptable.
Evaluation criteria for glue residue Evaluation A: No glue residue on any chips Evaluation B: The rate of glue residue chips is 40% or less Evaluation C: The rate of glue residue chips is 41% or more

The symbols in Table 1 are explained as follows.
EG: ethylene glycol Number of EG units M _EG : total number of ethylene glycol units contained in one molecule of the energy ray curable resin Number of UV curable functional groups M _UV : total number of energy ray (ultraviolet ray in this embodiment) curable functional groups contained in one molecule of the energy ray curable resin M _EG /M _UV : number of ethylene glycol (EG) units per energy ray (UV) curable functional group

As shown in Table 1, in the adhesive sheets of Examples 1 to 4, the breaking energy of the adhesive layer alone after irradiation with energy rays was 0.055 J or more, so the adhesive sheets of Examples 1 to 4 were adhesive sheets with little adhesive residue.

10...first adhesive sheet, 11...first substrate, 12...first adhesive layer, 13...second adhesive layer, 110...substrate.

Claims (5)

The adhesive layer includes a substrate and a pressure-sensitive adhesive layer.
The pressure-sensitive adhesive layer contains an energy ray-curable resin,
The energy ray-curable resin has a group in which an ethylene glycol unit represented by the following general formula (11) is directly bonded to an energy ray-curable functional group,
the number of ethylene glycol units contained in one molecule of the energy ray curable resin is 3 or more and 100 or less,
the energy ray curable resin has three or more energy ray curable functional groups,
The breaking energy of the pressure-sensitive adhesive layer alone after irradiation with energy rays is 0.055 J or more;
Expanded sheet.

(In the general formula (11), m is 3 or more.) The expandable sheet according to claim 1,
The breaking energy of the pressure-sensitive adhesive layer alone after irradiation with energy rays is 0.065 J or more;
Expanded sheet. The expandable sheet according to claim 1 or 2,
The pressure-sensitive adhesive layer alone has a breaking elongation of 6% or more after irradiation with energy rays;
Expanded sheet. The expandable sheet according to any one of claims 1 to 3 ,
The energy ray curable resin further has one or more glycerin skeletons.
Expanded sheet. The expandable sheet according to any one of claims 1 to 4,
The pressure-sensitive adhesive layer contains the energy ray curable resin and a (meth)acrylic copolymer.
Expanded sheet.

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