JP7541019B2 - Adhesive sheet - Google Patents

Description

The present invention relates to an adhesive sheet and a method for manufacturing 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 close to their size. 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 material 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 the molding material, an expandable wafer mount tape is attached, and the wafer mount tape is expanded to increase the distance between the plurality of semiconductor chips.

International Publication No. 2010/058646

In the expanding step, the tape or sheet to which multiple semiconductor chips are attached is expanded to expand the spaces between the semiconductor chips. When the sheet is stretched and expanded, if the amount of expansion varies within the sheet plane, it is difficult to uniformly expand the spaces between the semiconductor chips.
Furthermore, there may be a problem in that the adhesive contained in the adhesive layer of the adhesive sheet seeps out from the ends in the width direction of the sheet.

An object of the present invention is to provide an adhesive sheet that has excellent extensibility and can reduce the difference in the amount of elongation in the in-plane direction of the adhesive sheet when the adhesive sheet is expanded in an expanding process to expand the distance between semiconductor chips.
Another object of the present invention is to provide an adhesive sheet having excellent extensibility, which can suppress the seepage of adhesive and reduce the difference in the amount of elongation in the in-plane direction of the adhesive sheet when the adhesive sheet is expanded in an expanding process to expand the distance between semiconductor chips, as well as a method for manufacturing said adhesive sheet.

The pressure-sensitive adhesive sheet according to one embodiment of the present invention has a substrate and a pressure-sensitive adhesive layer,
A first test piece having a width of 25 mm was prepared from the pressure-sensitive adhesive sheet, and the substrate and the pressure-sensitive adhesive layer at both ends of the first test piece in the longitudinal direction were gripped with grippers, and the tensile strength F _A1 when pulled 0.5 mm by a tensile tester was measured.
A first semiconductor chip and a second semiconductor chip having a vertical dimension of 45 mm, a horizontal dimension of 35 mm, and a thickness dimension of 0.625 mm are aligned with the sides of the first semiconductor chip and the second semiconductor chip whose vertical dimension is 45 mm along the longitudinal direction of the first test piece, and the distance between the first semiconductor chip and the second semiconductor chip is 35 μm. The first semiconductor chip is attached to the adhesive layer at one end side in the longitudinal direction of the first test piece, and the second semiconductor chip is attached to the adhesive layer at the other end side in the longitudinal direction of the first test piece to prepare a second test piece. The substrate, the adhesive layer, and the semiconductor chip at each end in the longitudinal direction of the second test piece are held with a gripper, and the tensile strength F _B1 when pulled 0.5 mm by a tensile tester satisfies the relationship of the following mathematical formula (Math 1A).
F _B1 /F _A1 ≦30...(Math 1A)

The pressure-sensitive adhesive sheet according to one embodiment of the present invention has a substrate and a pressure-sensitive adhesive layer,
The pressure-sensitive adhesive layer contains an energy ray-curable resin,
the pressure-sensitive adhesive layer has a cured portion at both ends in a width direction of the pressure-sensitive adhesive layer, where the energy ray curable resin is cured, and an uncured portion at which the energy ray curable resin is not cured,
A first test piece having a width of 25 mm was prepared from the pressure-sensitive adhesive sheet in a region corresponding to the uncured portion, and the uncured portions of the substrate and the pressure-sensitive adhesive layer at both ends of the first test piece in the longitudinal direction were gripped with grippers to measure the tensile strength F _A1 when pulled 0.5 mm by a tensile tester;
A first semiconductor chip and a second semiconductor chip having a vertical dimension of 45 mm, a horizontal dimension of 35 mm, and a thickness dimension of 0.625 mm were aligned with the sides of the first semiconductor chip and the second semiconductor chip whose vertical dimension is 45 mm along the longitudinal direction of the first test piece, and the distance between the first semiconductor chip and the second semiconductor chip was set to 35 μm. The first semiconductor chip was attached to the adhesive layer of the uncured portion at one end side of the longitudinal direction of the first test piece, and the second semiconductor chip was attached to the adhesive layer of the uncured portion at the other end side of the longitudinal direction of the first test piece to prepare a second test piece, and the substrate, the adhesive layer of the uncured portion, and the semiconductor chip at each end in the longitudinal direction of the second test piece were held with a gripper, and the tensile strength F _B1 when pulled 0.5 mm by a tensile tester satisfied the relationship of the following mathematical formula (Math 1A).
F _B1 /F _A1 ≦30...(Math 1A)

In an adhesive sheet according to one embodiment of the present invention, a third test piece is prepared by cutting the adhesive sheet along the longitudinal direction to a size of 150 mm in length and 25 mm in width so as to include a cured portion in which the energy ray curable resin has been cured. The third test piece is held by a pair of chucks with a chuck distance of 100 mm and extended at a speed of 5 mm/sec until the chuck distance becomes 200 mm. It is preferable that no lift occurs at the interface between the cured portion and the substrate.

In one aspect of the pressure-sensitive adhesive sheet of the present invention,
It is preferable that when the adhesive sheet 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 an area ratio (S2/S1)×100 of an area S1 of the adhesive sheet before stretching to an area S2 of the adhesive sheet after stretching is 381%, the cured portion of the adhesive layer does not peel off at the interface with the substrate.

In the pressure-sensitive adhesive sheet according to one aspect of the present invention, it is preferable that the tensile strength F _A1 and the tensile strength F _B1 satisfy the relationship of the following mathematical formula (Mathematical formula 1B).
1≦F _B1 /F _A1 ≦30…(Math 1B)

In the pressure-sensitive adhesive sheet according to one aspect of the present invention, it is preferable that the Young's modulus Y _A1 of the first test piece and the Young's modulus Y _B1 of the second test piece satisfy the relationship of the following mathematical formula (Mathematical Formula 2A).
Y _B1 /Y _A1 ≦19...(Math. 2A)

In the adhesive sheet according to one embodiment of the present invention, it is preferable that the adhesive layer contains an acrylic adhesive.

In one embodiment of the adhesive sheet of the present invention, it is preferable that the substrate contains a urethane-based elastomer.

The adhesive sheet of one embodiment of the present invention is preferably used in an expanding process for expanding the spacing between multiple semiconductor chips during the manufacturing process of a semiconductor device.

The pressure-sensitive adhesive sheet according to one embodiment of the present invention is long and wound into a roll.
Adhesive sheet.

A method for producing a pressure-sensitive adhesive sheet according to one embodiment of the present invention includes the steps of:
A step of applying a pressure-sensitive adhesive composition containing an energy ray curable resin onto a substrate to form a pressure-sensitive adhesive layer;
a step of irradiating both ends in the width direction of the pressure-sensitive adhesive layer with energy rays to cure the energy ray curable resin and form a cured portion;
and a step of cutting the portion outside the cured portion while leaving either the entire cured portion outside both widthwise ends of the uncured portion where the energy ray curable resin has not been cured, or while leaving only a portion of the cured portion.

In one aspect of the present invention, there is provided a method for producing a pressure-sensitive adhesive sheet, comprising the steps of:
It is preferable that the widths of the cured portions remaining outside both widthwise ends of the uncured portion are each independently 0.5 mm or more.

In one aspect of the present invention, there is provided a method for producing a pressure-sensitive adhesive sheet, comprising the steps of:
It is preferable to further include a step of winding up the cut pressure-sensitive adhesive sheet into a roll after the step of cutting off the portion outside the cured portion.

According to one aspect of the present invention, when the adhesive sheet is expanded in an expanding process to expand the distance between semiconductor chips, the difference in the amount of elongation in the in-plane direction of the adhesive sheet can be reduced, thereby providing an adhesive sheet with excellent expandability.
According to another aspect of the present invention, it is possible to provide an adhesive sheet having excellent extensibility, which can suppress the seepage of adhesive and reduce the difference in the amount of elongation in the in-plane direction of the adhesive sheet when the adhesive sheet is expanded in an expanding process to expand the distance between semiconductor chips, as well as a method for manufacturing the adhesive sheet.

1 is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to an embodiment. FIG. 2 is a schematic diagram showing a state in which a first test piece is gripped by grippers of a tensile tester. FIG. 13 is a schematic diagram showing a state in which a second test piece is gripped by grippers of a tensile testing machine. FIG. 4 is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to another embodiment. FIG. 4 is a perspective view showing a state in which a pressure-sensitive adhesive sheet according to another embodiment is wound into a roll. 5A to 5C are schematic cross-sectional views illustrating a method for producing a pressure-sensitive adhesive sheet according to another embodiment. 5A to 5C are schematic cross-sectional views illustrating a method for producing a pressure-sensitive adhesive sheet according to another embodiment. 5A to 5C are schematic cross-sectional views illustrating a method for producing a pressure-sensitive adhesive sheet according to another embodiment. FIG. 2 is a plan view illustrating a biaxial stretching and expanding device used in the examples.

The following describes one embodiment of the present invention.

First Embodiment
[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).
1 is a schematic cross-sectional view of an example of a pressure-sensitive adhesive sheet according to the present embodiment. In FIG. 1, a pressure-sensitive adhesive sheet 1 having a substrate 10 and a pressure-sensitive adhesive layer 20 is shown.

The adhesive sheet of this embodiment has a first test piece and a second test piece prepared from the adhesive sheet, and the ratio of the tensile strengths measured using a tensile tester satisfies a specified range.

(First test piece)
The first test piece was made from the pressure-sensitive adhesive sheet according to this embodiment. The width of the first test piece was 25 mm.

Figure 2 is a schematic diagram showing the substrate 10 and adhesive layer 20 at one end of the first test piece being gripped by a first gripper 110 of a tensile testing machine, and the substrate 10 and adhesive layer 20 at the other end of the first test piece being gripped by a second gripper 120 of the tensile testing machine.

(Second test piece)
The second test piece is produced by attaching two semiconductor chips to the first test piece produced from the adhesive sheet according to this embodiment. In this embodiment, the two semiconductor chips are a first semiconductor chip and a second semiconductor chip. Both the first semiconductor chip and the second semiconductor chip have a vertical dimension of 45 mm, a horizontal dimension of 35 mm, and a thickness dimension of 0.625 mm.
The first and second semiconductor chips are attached such that their sides measuring 45 mm in length are aligned along the longitudinal direction of the first test piece.
The first semiconductor chip is attached to one end of the first test piece in the longitudinal direction, and the second semiconductor chip is attached to the other end of the first test piece in the longitudinal direction, with the distance between the first and second semiconductor chips attached to the first test piece being 35 μm.

Figure 3 is a schematic diagram showing the substrate 10, adhesive layer 20 and first semiconductor chip CP1 at one end side of the second test piece being held by a first gripper 110 of a tensile testing machine, and the substrate 10, adhesive layer 20 and second semiconductor chip CP2 at the other end side of the second test piece being held by a second gripper 120 of the tensile testing machine.

(Tensile strength)
In the pressure-sensitive adhesive sheet according to this embodiment, the tensile strengths of the first test piece and the second test piece measured using a tensile tester satisfy the relationship of the following mathematical formula (Mathematical Formula 1A).
F _B1 /F _A1 ≦30...(Math 1A)

In the above formula (Mathematical Formula 1A), the tensile strength F _A1 is the strength when the substrate and the pressure-sensitive adhesive layer at both ends in the longitudinal direction of the first test piece are gripped with grippers and pulled 0.5 mm using a tensile tester.

In the above formula (Mathematical Formula 1A), the tensile strength F _B1 is the strength when the substrate, the adhesive layer and the semiconductor chip at each end in the longitudinal direction of the second test piece are gripped with grippers and pulled 0.5 mm using a tensile tester.

The present inventors have found that the behavior of the adhesive sheet in the way it stretches differs between the area of the adhesive sheet to which the semiconductor chip is not attached and the area to which the semiconductor chip is attached when the adhesive sheet is expanded (spread).The present inventors have also found that in a conventional adhesive sheet, the tensile strength of the area to which the semiconductor chip is not attached is significantly different from the tensile strength of the area to which the semiconductor chip is attached, and that when the adhesive sheet is spread in the expanding step to increase the distance between the semiconductor chips, the difference in the amount of stretch in the in-plane direction of the adhesive sheet is large.
According to the adhesive sheet of this embodiment, F _B1 /F _A1 is 30 or less, and the ratio F B1 /F _A1 of the tensile strength of the portion of the adhesive sheet to which the semiconductor chip is not attached to the tensile strength of the portion to which the semiconductor chip is attached is small. Therefore, according to the adhesive sheet of this embodiment, when the adhesive sheet is spread in the expanding _step to expand the distance between the semiconductor chips, the difference in the amount of elongation in the in-plane direction of the adhesive sheet is small, resulting in excellent expandability and reducing the variation in the distance between the semiconductor chips.
The tensile amount of 0.5 mm used when measuring the tensile strengths F _A1 and F _B1 is a guideline for the tensile amount in the expanding step. Therefore, the pressure-sensitive adhesive sheet according to the present embodiment may be used in an expanding step with a tensile amount smaller than 0.5 mm, or may be used in an expanding step with a tensile amount larger than 0.5 mm.
According to the adhesive sheet of this embodiment, F _B1 /F _A1 when stretched by 0.5 mm is 30 or less, so when the adhesive sheet of this embodiment is used in an expansion process in which the sheet is stretched by more than 0.5 mm, it is possible to prevent the difference in the amount of elongation between the tensile strength of the portion of the adhesive sheet to which the semiconductor chip is not attached and the portion to which the semiconductor chip is attached from becoming excessively large.

In the pressure-sensitive adhesive sheet according to this embodiment, it is preferable that the tensile strength F _A1 of the first test piece and the tensile strength F _B1 of the second test piece measured using a tensile tester satisfy the relationship of the following mathematical formula (Mathematical Formula 1B).
1≦F _B1 /F _A1 ≦30…(Math 1B)

In the pressure-sensitive adhesive sheet according to this embodiment, it is also preferable that the tensile strength F _A1 of the first test piece and the tensile strength F _B1 of the second test piece measured using a tensile tester satisfy the relationship of the following mathematical formula (Mathematical Formula 1C).
F _B1 /F _A1 ≦20...(Math. 1C)

Methods for adjusting the value of F _B1 /F _A1 within the range of the above-mentioned formula (1A), formula (1B), or formula (1C) include the following methods. For example, the value of F B1 /F A1 can be adjusted within the range of the above-mentioned formula (1A), formula (1B), or formula (1C) by combining one or more of the following: changing the composition of the pressure-sensitive adhesive composition used in the pressure-sensitive adhesive layer 20, changing the thickness of the pressure _- sensitive _{adhesive layer} , changing the material of the substrate, and changing the thickness of the substrate.

(Young's Modulus)
In the pressure-sensitive adhesive sheet according to this embodiment, it is preferable that the Young's modulus Y _A1 of the first test piece and the Young's modulus Y _B1 of the second test piece satisfy the relationship of the following mathematical formula (Mathematical Formula 2A).
Y _B1 /Y _A1 ≦19...(Math. 2A)
By satisfying the relationship of the above formula (Math. 2A), the ratio _YB1 /YA1 between the Young's modulus of the portion of the adhesive sheet where the semiconductor chip is not attached and the Young's modulus of the portion where the semiconductor chip is _attached is small. Therefore, when the adhesive sheet is expanded in the expanding process to expand the distance between the semiconductor chips, it is easy to reduce the difference in the amount of elongation in the in-plane direction of the adhesive sheet. In addition, by satisfying the relationship of the above formula (Math. 2A), even if the adhesive sheet is used in the expanding process where the tensile amount is greater than 0.5 mm, the value of _YB1 / _YA1 can be prevented from becoming excessively large.
The Young's modulus of the pressure-sensitive adhesive sheet can be measured according to the measurement method described in the Examples section below.

(Substrate)
The substrate preferably has a first substrate surface and a second substrate surface opposite to the first substrate surface. For example, as shown in FIG. 1, a substrate 10 of a pressure-sensitive adhesive sheet 1 has a first substrate surface 11 and a second substrate surface 12 opposite to the first substrate surface 11.
In the pressure-sensitive adhesive sheet of the present embodiment, the pressure-sensitive adhesive layer according to the present embodiment is preferably provided on one of the first substrate surface and the second substrate 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.

Examples of the thermoplastic elastomer 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 from the viewpoint of ease of large stretching. That is, in the pressure-sensitive adhesive sheet according to this embodiment, the substrate preferably contains a urethane-based elastomer.

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 addition, 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).

(Adhesive Layer)
In the pressure-sensitive adhesive sheet according to the present embodiment, the pressure-sensitive adhesive layer is not particularly limited as long as it satisfies the relationship of the above-mentioned mathematical formula (Mathematical formula 1A). The material constituting the pressure-sensitive adhesive layer can be appropriately selected and blended from, for example, the materials described below so as to satisfy the range of the relationship of the above-mentioned mathematical formula (Mathematical formula 1A).
For example, the adhesive used in the adhesive layer may be a rubber-based adhesive, an acrylic-based adhesive, a silicone-based adhesive, a polyester-based adhesive, or a urethane-based adhesive.

In the adhesive sheet of this embodiment, it is preferable that the adhesive layer contains an acrylic adhesive.

Energy ray curable resin (a1)
The pressure-sensitive adhesive layer preferably contains an energy ray-curable resin (a1). The energy ray-curable resin (a1) has an energy ray-curable double bond in the molecule.
The pressure-sensitive adhesive layer containing the energy ray-curable resin is cured by irradiation with energy rays, and the adhesive strength is reduced. When it is desired to separate the adhesive sheet from the adherend, separation can be easily achieved by irradiating the pressure-sensitive adhesive layer with energy rays.

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 curing when irradiated with energy rays, such as ultraviolet rays and electron beams.
Examples of the energy ray curable resin (a1) include low molecular weight compounds having an energy ray polymerizable group (monofunctional monomers, polyfunctional monomers, monofunctional oligomers, and polyfunctional oligomers). Specific examples of the energy ray curable resin (a1) 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, polyethylene glycol diacrylate, oligoester acrylate, urethane acrylate oligomer, epoxy modified acrylate, polyether acrylate, and itaconic acid oligomer.

The molecular weight of the energy ray curable resin (a1) is typically 100 or more and 30,000 or less, and preferably approximately 300 or more and 10,000 or less.

(Meth)acrylic copolymer (b1)
The pressure-sensitive adhesive layer according to this embodiment preferably further contains a (meth)acrylic copolymer (b1). The (meth)acrylic copolymer is different from the energy ray-curable resin (a1) described above.

The (meth)acrylic copolymer (b1) preferably has an energy ray-curable carbon-carbon double bond. That is, in this embodiment, the pressure-sensitive adhesive layer preferably contains an energy ray-curable resin (a1) and an energy ray-curable (meth)acrylic copolymer (b1).

The pressure-sensitive adhesive layer according to this embodiment preferably contains 10 parts by mass or more of the energy ray-curable resin (a1) relative to 100 parts by mass of the (meth)acrylic copolymer (b1), more preferably contains 20 parts by mass or more, and even more preferably contains 25% by mass or more.
The pressure-sensitive adhesive layer according to this embodiment preferably contains the energy ray-curable resin (a1) in an amount of 80 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 60 parts by mass or less, per 100 parts by mass of the (meth)acrylic copolymer (b1).

The weight average molecular weight (Mw) of the (meth)acrylic copolymer (b1) is preferably 10,000 or more, more preferably 150,000 or more, and even more preferably 200,000 or more.
The weight average molecular weight (Mw) of the (meth)acrylic copolymer (b1) is preferably 1.5 million or less, and more preferably 1 million or less.
In this specification, the weight average molecular weight (Mw) is a value measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

It is preferable that the (meth)acrylic copolymer (b1) is a (meth)acrylic acid ester polymer (b2) (hereinafter sometimes referred to as "energy ray-curable polymer (b2)") having a functional group having energy ray curability (energy ray-curable group) introduced into the side chain.

The energy radiation curable polymer (b2) is preferably a copolymer obtained by reacting an acrylic copolymer (b21) having a functional group-containing monomer unit with an unsaturated group-containing compound (b22) having a functional group bonded to the functional group. In this specification, (meth)acrylic acid ester means both acrylic acid ester and methacrylic acid ester. The same applies to other similar terms.

It is preferable that the acrylic copolymer (b21) contains a structural unit derived from a functional group-containing monomer and a structural unit derived from a (meth)acrylic acid ester monomer or a derivative of a (meth)acrylic acid ester monomer.

The functional group-containing monomer as a constituent unit of the acrylic copolymer (b21) is preferably a monomer having a polymerizable double bond and a functional group in the molecule. The functional group is preferably at least one selected from the group consisting of a hydroxy group, a carboxy group, an amino group, a substituted amino group, an epoxy group, and the like.

Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. The hydroxyl group-containing monomers may be used alone or in combination of two or more.

Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. The carboxyl group-containing monomer may be used alone or in combination of two or more.

Examples of amino group-containing monomers or substituted amino group-containing monomers include aminoethyl (meth)acrylate and n-butylaminoethyl (meth)acrylate. The amino group-containing monomers or substituted amino group-containing monomers may be used alone or in combination of two or more.

As the (meth)acrylic acid ester monomer constituting the acrylic copolymer (b21), in addition to alkyl (meth)acrylates in which the alkyl group has 1 to 20 carbon atoms, for example, monomers having an alicyclic structure in the molecule (alicyclic structure-containing monomers) are preferably used.

As the alkyl (meth)acrylate, an alkyl (meth)acrylate in which the number of carbon atoms in the alkyl group is 1 or more and 18 or less is preferred. Examples of the alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. The alkyl (meth)acrylate may be used alone or in combination of two or more kinds.

Preferred examples of alicyclic structure-containing monomers include cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, adamantyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate. The alicyclic structure-containing monomers may be used alone or in combination of two or more.

The acrylic copolymer (b21) preferably contains the structural unit derived from the functional group-containing monomer in a proportion of 1 mass % or more, more preferably 5 mass % or more, and even more preferably 10 mass % or more.
In addition, the acrylic copolymer (b21) preferably contains the structural units derived from the functional group-containing monomer in a proportion of 35% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less.

Furthermore, the acrylic copolymer (b21) preferably contains a structural unit derived from a (meth)acrylic acid ester monomer or a derivative thereof in a proportion of 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more.
In addition, the acrylic copolymer (b21) preferably contains a structural unit derived from a (meth)acrylic acid ester monomer or a derivative thereof in a proportion of 99% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less.

The acrylic copolymer (b21) can be obtained by copolymerizing the above-mentioned functional group-containing monomer with a (meth)acrylic acid ester monomer or a derivative thereof in a conventional manner.
The acrylic copolymer (b21) may contain, in addition to the above-mentioned monomers, at least one structural unit selected from the group consisting of dimethylacrylamide, vinyl formate, vinyl acetate, styrene, and the like.

The energy ray curable polymer (b2) is obtained by reacting the acrylic copolymer (b21) having the above-mentioned functional group-containing monomer unit with an unsaturated group-containing compound (b22) having a functional group bonded to the functional group.

The functional group of the unsaturated group-containing compound (b22) can be appropriately selected depending on the type of functional group of the functional group-containing monomer unit of the acrylic copolymer (b21). For example, when the functional group of the acrylic copolymer (b21) is a hydroxy group, an amino group, or a substituted amino group, the functional group of the unsaturated group-containing compound (b22) is preferably an isocyanate group or an epoxy group, and when the functional group of the acrylic copolymer (b21) is an epoxy group, the functional group of the unsaturated group-containing compound (b22) is preferably an amino group, a carboxy group, or an aziridinyl group.

The unsaturated group-containing compound (b22) contains at least one energy ray-polymerizable carbon-carbon double bond in one molecule, preferably 1 to 6, and more preferably 1 to 4.

Examples of unsaturated group-containing compounds (b22) include 2-methacryloyloxyethyl isocyanate (2-isocyanatoethyl methacrylate), meth-isopropenyl-α,α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, 1,1-(bisacryloyloxymethyl)ethyl isocyanate; acryloyl monoisocyanate compounds obtained by reacting a diisocyanate compound or a polyisocyanate compound with hydroxyethyl (meth)acrylate; acryloyl monoisocyanate compounds obtained by reacting a diisocyanate compound or a polyisocyanate compound with a polyol compound and hydroxyethyl (meth)acrylate; glycidyl (meth)acrylate; (meth)acrylic acid, 2-(1-aziridinyl)ethyl (meth)acrylate, 2-vinyl-2-oxazoline, 2-isopropenyl-2-oxazoline, and the like.

The unsaturated group-containing compound (b22) is preferably used in a proportion (addition rate) of 50 mol % or more, more preferably 60 mol % or more, and even more preferably 70 mol % or more, based on the number of moles of the functional group-containing monomer in the acrylic copolymer (b21).
In addition, the unsaturated group-containing compound (b22) is preferably used in a proportion of 95 mol % or less, more preferably 93 mol % or less, and even more preferably 90 mol % or less, based on the number of moles of the functional group-containing monomer in the acrylic copolymer (b21).

In the reaction between the acrylic copolymer (b21) and the unsaturated group-containing compound (b22), the reaction temperature, pressure, solvent, time, presence or absence of a catalyst, and type of catalyst can be appropriately selected according to the combination of the functional group of the acrylic copolymer (b21) and the functional group of the unsaturated group-containing compound (b22). As a result, the functional group of the acrylic copolymer (b21) reacts with the functional group of the unsaturated group-containing compound (b22), and the unsaturated group is introduced into the side chain of the acrylic copolymer (b21), thereby obtaining an energy radiation curable polymer (b2).

The weight average molecular weight (Mw) of the energy ray curable polymer (b2) is preferably 10,000 or more, more preferably 150,000 or more, and even more preferably 200,000 or more.
The weight average molecular weight (Mw) of the energy ray curable polymer (b2) is preferably 1.5 million or less, and more preferably 1 million or less.

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 the photopolymerization initiator (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 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).

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, and even more preferably 3.5 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.

(Release sheet)
The 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 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.
It is preferably used in an expanding step for expanding the spaces between multiple semiconductor chips during the manufacturing process of a semiconductor device.
The semiconductor chips are preferably attached to the center of the adhesive sheet.
In addition, the plurality of semiconductor chips are preferably semiconductor chips obtained by dicing a semiconductor wafer. For example, a semiconductor wafer attached to a dicing sheet is diced to divide the semiconductor wafer into a plurality of semiconductor chips, and the plurality of semiconductor chips obtained by dividing the semiconductor chips may be directly transferred to the adhesive sheet according to the present embodiment, or may be transferred to another adhesive sheet, and then transferred from the other adhesive sheet to the adhesive sheet according to the present embodiment.

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.

Second Embodiment
[Adhesive sheet]
The pressure-sensitive adhesive sheet according to this embodiment has a substrate and a pressure-sensitive adhesive layer, similar to the pressure-sensitive adhesive sheet according to the first embodiment.
The pressure-sensitive adhesive layer according to this embodiment differs from the pressure-sensitive adhesive sheet according to the first embodiment in that it contains an energy ray-curable resin and has cured portions at both widthwise ends of the pressure-sensitive adhesive layer where the energy ray-curable resin is cured and uncured portions where the energy ray-curable resin is not cured.
In the pressure-sensitive adhesive sheet according to this embodiment, a first test piece and a second test piece are prepared from an uncured portion of the pressure-sensitive adhesive sheet, and the ratio of tensile strengths measured with a tensile tester satisfies a predetermined range.
In the following description, differences from the first embodiment will be mainly described, and overlapping descriptions will be omitted or simplified. The same components as those in the first embodiment will be denoted by the same reference numerals, and descriptions thereof will be omitted or simplified.

The adhesive sheet according to this embodiment also has a substrate and an adhesive layer. The adhesive sheet may have any shape, such as a tape shape (long shape) or a label shape (sheet shape).

FIG. 4 shows a schematic cross-sectional view of a pressure-sensitive adhesive sheet 1A according to this embodiment.
The adhesive sheet 1A has a substrate 10 and an adhesive layer 20. The adhesive layer 20 contains an energy ray curable resin. The adhesive layer 20 has a cured portion 22 where the energy ray curable resin is cured, and an uncured portion 21 where the energy ray curable resin is not cured. As shown in Fig. 4, the cured portion 22 is formed at both widthwise end portions of the adhesive layer 20 of the adhesive sheet 1A. The uncured portion 21 is located between the cured portion 22 at one end side in the width direction and the cured portion 22 at the other end side.

Two opposing sides of the adhesive sheet 1A in the width direction are cured by energy rays, and cured portions 22 are formed at both ends of the adhesive sheet 1A in the width direction. The cured portions 22 prevent the adhesive in the uncured portions 21 from seeping out from the ends of the adhesive sheet 1A in the width direction to the outside of the sheet.

The cross-sectional shape of the cured portion 22 is rectangular in Figure 4, but is not limited to a rectangle and is not particularly limited as long as the shape can suppress the adhesive from seeping out.

It is preferable that the cured portions 22 are formed continuously along both widthwise ends of the adhesive sheet 1A. By forming the cured portions 22 continuously along the longitudinal direction of the adhesive sheet 1A, it is easier to further prevent the adhesive from seeping out of the uncured portions 21 from the widthwise ends of the sheet to the outside of the sheet. If the cured portions 22 are formed discontinuously, there is a risk that the adhesive will seep out from places where the cured portions 22 are not formed.

When the adhesive sheet 1A is a long sheet, it is preferable that the cured portion 22 is formed continuously along the longitudinal direction of the adhesive sheet 1A. By forming the cured portion 22 continuously along the longitudinal direction of the adhesive sheet 1A, it is easier to further prevent the adhesive from seeping out of the uncured portion 21 from the sheet width direction end to the outside of the sheet.

Fig. 5 is a schematic perspective view showing a long adhesive sheet 1A wound into a roll, with a portion of the adhesive sheet 1A being unwound from the roll.
As shown in Fig. 5, cured portions 22 are formed at both widthwise ends of the adhesive sheet 1A, and an uncured portion 21 is present between the cured portion 22 at one end in the widthwise direction and the cured portion 22 at the other end in the widthwise direction. The cured portions 22 are each formed continuously along the longitudinal direction of the adhesive sheet 1A. Note that a roll of a long adhesive sheet 1A as shown in Fig. 5 is often stored such that the width direction of the roll is perpendicular to the placement surface. Therefore, by forming the cured portions 22 continuously at both widthwise ends of the adhesive sheet 1A, it is easy to suppress the adhesive from seeping out from the uncured portions 21 during roll storage.

The width of each of the cured portions 22 is preferably 0.5 mm or more, independently. If the width of the cured portions 22 is 0.5 mm or more, it is easier to prevent the adhesive from the uncured portions 21 from seeping out from the width direction end of the sheet to the outside of the sheet. When the cured portions 22 are continuously formed along the width direction end, the width of the cured portions 22 does not have to be constant along the longitudinal direction, and is preferably formed to a width of 0.5 mm or more along the longitudinal direction.
The width of each of the hardened portions 22 is preferably 10 mm or less. When the hardened portions 22 are formed continuously along the width direction edge portions, the width of the hardened portions 22 is preferably 10 mm or less along the longitudinal direction.
In addition, while a larger width of the cured portion 22 makes it easier to prevent the adhesive from seeping out, the area of the uncured portion 21 becomes smaller. Therefore, from the standpoint of preventing the adhesive from seeping out and ensuring the area of the uncured portion 21 that has the adhesive strength as an adhesive sheet, it is preferable to set an upper limit on the width of the cured portion 22.

(First test piece)
The first test piece was prepared from the region of the uncured portion 21 of the pressure-sensitive adhesive sheet 1A according to this embodiment. The width of the first test piece was 25 mm.
The state in which the first test piece in this embodiment is held is the same as that shown in Fig. 2 in the first embodiment. The substrate 10 and the uncured portion 21 of the pressure-sensitive adhesive layer 20 at one end of the first test piece are held by a first grip 110 of a tensile tester, and the substrate 10 and the uncured portion 21 of the pressure-sensitive adhesive layer 20 at the other end of the first test piece are held by a second grip 120 of the tensile tester.

(Second test piece)
The second test piece is produced by attaching two semiconductor chips to the first test piece produced from the adhesive sheet 1A according to this embodiment. In this embodiment, the two semiconductor chips are a first semiconductor chip and a second semiconductor chip. The first semiconductor chip and the second semiconductor chip each have a vertical dimension of 45 mm, a horizontal dimension of 35 mm, and a thickness dimension of 0.625 mm.
The first and second semiconductor chips are attached such that their sides measuring 45 mm in length are aligned along the longitudinal direction of the first test piece.
The first semiconductor chip is attached to one end of the first test piece in the longitudinal direction, and the second semiconductor chip is attached to the other end of the first test piece in the longitudinal direction, with the distance between the first and second semiconductor chips attached to the first test piece being 35 μm.

The state in which the second test piece in this embodiment is held is the same as that shown in Fig. 3 in the first embodiment. The substrate 10, the uncured portion 21 of the adhesive layer 20, and the first semiconductor chip CP1 at one end of the second test piece are held by a first gripper 110 of the tensile tester, and the substrate 10, the uncured portion 21 of the adhesive layer 20, and the second semiconductor chip CP2 at the other end of the second test piece are held by a second gripper 120 of the tensile tester.

(Tensile strength)
The pressure-sensitive adhesive sheet 1A according to this embodiment also has a tensile strength of the first test piece and the second test piece measured using a tensile tester, which satisfies the relationship of the following mathematical formula (Mathematical formula 1A).
F _B1 /F _A1 ≦30...(Math 1A)

In the above formula (Mathematical Formula 1A), the tensile strength F _A1 is the strength when the substrate and the pressure-sensitive adhesive layer at both ends in the longitudinal direction of the first test piece are gripped with grippers and pulled 0.5 mm using a tensile tester.

In the above formula (Mathematical Formula 1A), the tensile strength F _B1 is the strength when the substrate, the adhesive layer and the semiconductor chip at each end in the longitudinal direction of the second test piece are gripped with grippers and pulled 0.5 mm using a tensile tester.

A third test piece is prepared by cutting a size of 150 mm in length and 25 mm in width along the longitudinal direction of the adhesive sheet 1A so as to include a cured portion 22 formed by curing the energy ray curable resin, and the third test piece is held with a pair of chucks with a chuck distance of 100 mm and extended at a speed of 5 mm/sec until the chuck distance becomes 200 mm. It is preferable that no lift occurs at the interface between the cured portion 22 and the substrate 10.
When the cured portion of the adhesive sheet is stretched (for example, when the adhesive sheet is expanded), if lifting occurs at the interface between the cured portion and the substrate, the lifted cured portion breaks off from the adhesive layer, and the broken cured portion scatters and adheres to the adherend and the expanding device attached to the adhesive sheet, which may cause contamination. However, in the adhesive sheet 1A according to the present embodiment, in the tensile test using the third test piece, lifting does not occur at the interface between the cured portion 22 and the substrate 10, so it is easy to suppress contamination of the adherend and the expanding device due to the broken cured portion as described above. In order to prevent lifting from occurring at the interface between the cured portion 22 and the substrate 10, for example, a method of controlling the curing degree of the energy ray curable resin can be mentioned.

When the adhesive sheet 1A of this 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, it is preferable that when the area ratio (S2/S1)×100 of the area S1 of the adhesive sheet 1A before stretching to the area S2 of the adhesive sheet 1A after stretching is 381%, the cured portion 22 of the adhesive layer 20 does not peel off at the interface with the substrate 10.
The first, second, third and fourth directions preferably correspond to, for example, the four directions of +X-axis direction, -X-axis direction, +Y-axis direction and -Y-axis direction of biaxial stretching described later. An example of a device for stretching in the four directions is an expanding device described later.
The adhesive sheet 1A of this embodiment is stretched in four directions, and when the area ratio before and after stretching (S2/S1) x 100 is 381%, the cured portion 22 of the adhesive layer 20 does not peel off at the interface with the substrate 10. Therefore, even when the adhesive sheet 1A is used in an expansion process with a high elongation rate, contamination of the adherend and the expansion device due to broken cured portions is easily suppressed.

[Method of manufacturing pressure-sensitive adhesive sheet]
The method for producing the pressure-sensitive adhesive sheet 1A according to this embodiment includes the following steps (P1) to (P3).
(P1) A step of applying a pressure-sensitive adhesive composition containing an energy ray-curable resin onto a substrate 10 to form a pressure-sensitive adhesive layer 20.
(P2) A step of irradiating both widthwise ends of the pressure-sensitive adhesive layer 20 with energy rays UV to cure the energy ray curable resin and form cured portions 22.
(P3) A process of cutting out the area outside the cured portion 22, leaving either the entire cured portion 22 outside both widthwise ends of the uncured portion 21 where the energy ray curable resin has not been cured, or leaving only a portion of the cured portion 22.

The pressure-sensitive adhesive sheet 1A according to this embodiment can be produced, for example, as follows.
First, in step (P1), a pressure-sensitive adhesive layer 20 is formed on a substrate 10. In this embodiment, the pressure-sensitive adhesive layer 20 can be formed, for example, in the same manner as in the first embodiment.

FIG. 6A is a schematic cross-sectional view illustrating the step (P2) of forming cured portions 22 at both widthwise end portions of adhesive sheet 1A.
Since the pressure-sensitive adhesive layer 20 contains an energy ray curable resin, both ends in the width direction are irradiated with energy rays UV to form the cured portions 22. When the energy ray curable resin is an ultraviolet ray curable resin, ultraviolet rays are irradiated as the energy rays.
It is preferable that cured portion 22 be formed with a width larger than the width of cured portion 22 required when used as pressure-sensitive adhesive sheet 1A.

FIG. 6B is a schematic cross-sectional view illustrating a step (P3) of cutting both widthwise ends of adhesive sheet 1A so that cured portion 22 remains after cured portion 22 is formed by irradiation with energy rays.
In Fig. 6B, cuts are made at positions C1 and C2 of the cured portion 22, which is formed with a width larger than the width required for use as the adhesive sheet 1A. By making cuts in the cured portion 22, it is possible to prevent the adhesive from adhering to the cutting blade. The cuts are made along the sheet longitudinal direction of the cured portion 22.
It is preferable that the width of the hardened portion 22 remaining outside both widthwise ends of the unhardened portion 21 (the distance from the boundary between the unhardened portion 21 and the hardened portion 22 to position C1 or position C2 in cross-sectional view) is independently 0.5 mm or more.

Figure 6C shows the adhesive sheet 1A, which has hardened portions 22 formed at both widthwise ends after cutting in step (P3), and scrap material 1a.

After the step (P3) of cutting the portion outside the cured portion 22, it is preferable to further include a step of winding up the cut adhesive sheet 1A into a roll.

[How to use the adhesive sheet]
The pressure-sensitive adhesive sheet 1A according to this embodiment can be used in the same manner as the pressure-sensitive adhesive sheet according to the first embodiment.

The pressure-sensitive adhesive sheet 1A according to the present embodiment can be used, for example, for semiconductor processing. The pressure-sensitive adhesive sheet 1A is preferably used in an expanding step for expanding the gap between multiple semiconductor chips during the manufacturing process of a semiconductor device.
The semiconductor chips are preferably attached to the center portion (uncured portion 21) of the adhesive sheet 1A.
In the expanding step, it is preferable that the cured portion 22 of the pressure-sensitive adhesive sheet 1A is held by a holding means of the separating device.

The adhesive sheet 1A of this embodiment has excellent extensibility because it suppresses the seepage of adhesive and reduces the difference in the amount of elongation in the in-plane direction of the adhesive sheet when the adhesive sheet is expanded in the expansion process to expand the distance between semiconductor chips.

[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.

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 62 parts by mass of butyl acrylate (BA), 10 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, solid content 35.0% by mass) 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 80 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 90,000, 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, UV resin A (10-functional urethane acrylate, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., product name "UV-5806", Mw = 1740, containing a photopolymerization initiator) and a tolylene diisocyanate-based crosslinking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "Coronate L") were added as a crosslinking agent. 50 parts by mass of UV resin A and 0.2 parts by mass of the crosslinking agent were added relative to 100 parts by mass of the solid content in the adhesive base. After the addition, the mixture was stirred for 30 minutes to prepare adhesive composition A1.
Next, the prepared solution of pressure-sensitive adhesive composition A1 was applied to a polyethylene terephthalate (PET)-based release film (manufactured by Lintec Corporation, product name "SP-PET381031", thickness 38 μm) and dried to form a pressure-sensitive adhesive layer with a thickness of 40 μm on the release film.
A polyester-based polyurethane elastomer sheet (manufactured by Seedam Co., Ltd., product name "Higress DUS202", thickness 100 μm) was bonded to the adhesive layer as a substrate, and unnecessary portions of the ends in the width direction were then cut and removed to produce an adhesive sheet.

[Example 2]
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 (adhesive base) of a resin (acrylic A2) 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 A2) 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. Relative to 100 parts by mass of the solid content in the adhesive base, 18 parts by mass of the energy ray curable resin A, 1.3 parts by mass of the photopolymerization initiator, 0.2 parts by mass of the crosslinking agent, and ethyl acetate were added, and the mixture was stirred for 30 minutes to prepare an adhesive composition A1 with a solid content of 35.0% by mass.
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 attached to the adhesive layer to prepare an adhesive tape.
When this adhesive tape was cut to a width of 300 mm, two LED-UV units were installed at each cut so as to straddle the cut portion. The distance between the lens tip of the LED-UV unit and the tape was 10 mm. Regarding the output of the LED-UV unit, both lamps were irradiated with UV at 50% output to form a cured portion in the adhesive layer. The adhesive tape was cut along the formed cured portion to prepare an adhesive sheet (width 300 mm) having a cured portion at both ends in the width direction. As shown in Table 2, the width of the cured portion at both ends in the sheet width direction was 1.00 mm. The slit speed during cutting was 10 m/min. Table 2 also shows the relationship between the output of the LED-UV unit and the light amount and illuminance per LED-UV unit.

The LED-UV unit used in Example 2 is described below.
・LED-UV unit: HOYA CANDEO OPTRONICS Control unit: H-1 VC II
Light emitting part = H-1 VH4
Lens = HO-03L

[Example 3]
The adhesive sheet of Example 3 was produced in the same manner as in Example 2, except that the output of the LED-UV unit in the production of the adhesive sheet of Example 2 was changed to 40% and the width of the cured portion at both ends in the sheet width direction was set to 0.50 mm, as shown in Table 2.

[Example 4]
The adhesive sheet of Example 4 was produced in the same manner as in Example 2, except that the output of the LED-UV unit in the production of the adhesive sheet of Example 2 was changed to 90% and the width of the cured portion at both ends in the sheet width direction was set to 1.25 mm, as shown in Table 2.

[Example 5]
The pressure-sensitive adhesive sheet of Example 5 was produced in the same manner as in Example 2, except that the substrate in the pressure-sensitive adhesive sheet of Example 2 was changed to fine paper (basis weight: 60 g/m ² ).

[Example 6]
The pressure-sensitive adhesive sheet of Example 6 was produced in the same manner as in Example 2, except that the substrate in the production of the pressure-sensitive adhesive sheet of Example 2 was changed to a polyethylene terephthalate film (thickness: 50 μm).

[Comparative Example 1]
An adhesive sheet was prepared in the same manner as in Example 1, except that the adhesive base was changed as follows.
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 B) (adhesive base, solid content 35.0% by mass) 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 B) was 600,000, and Mw/Mn was 4.5. The weight average molecular weight Mw and molecular weight distribution (Mw/Mn) of the resin (acrylic B) according to Comparative Example 1 were determined in the same manner as in Example 1.

[Comparative Example 2]
The pressure-sensitive adhesive sheet of Comparative Example 2 was produced in the same manner as in Example 2, except that the UV irradiation was not performed in the production of the pressure-sensitive adhesive sheet according to Example 2.

[Evaluation of Adhesive Sheet]
The produced pressure-sensitive adhesive sheets were subjected to the following evaluations. The evaluation results are shown in Tables 1 and 2.

<Measurement method>
(Method of measuring tensile strength)
The tensile strength was measured using an Autograph AG-IS manufactured by Shimadzu Corporation.
A first test piece having a width of 25 mm was prepared from the pressure-sensitive adhesive sheet. For a pressure-sensitive adhesive sheet having a cured portion and an uncured portion, the first test piece was prepared from a region of the pressure-sensitive adhesive sheet corresponding to the uncured portion.
A first semiconductor chip and a second semiconductor chip were attached to the first test piece to prepare a second test piece. As the first semiconductor chip and the second semiconductor chip, both of the semiconductor chips used had a vertical dimension of 45 mm, a horizontal dimension of 35 mm, and a thickness dimension of 0.625 mm.
The first and second semiconductor chips were attached with their sides measuring 45 mm in the longitudinal direction of the first test piece.
The first semiconductor chip was attached to one end of the first test piece in the longitudinal direction, and the second semiconductor chip was attached to the other end of the first test piece in the longitudinal direction. The distance between the first and second semiconductor chips attached to the first test piece was 35 μm.

The substrate and the adhesive layer at both ends of the first test piece in the longitudinal direction were gripped with grippers, and the tensile strength was measured with a tensile tester. The tensile strength F _A1 of the first test piece when pulled 0.5 mm (pulling distance 0.5 mm) is shown in Table 1.
The substrate, the adhesive layer, and the semiconductor chip at both ends of the second test piece in the longitudinal direction were gripped with grippers, and the tensile strength was measured with a tensile tester. The tensile strength F _B1 of the second test piece when pulled 0.5 mm (pulling distance 0.5 mm) is shown in Table 1.
The unit of tensile strength is N.
Other conditions during the tensile test are as follows:
Distance between grippers: 50 mm
Tensile speed: 50 mm/min

(Method of measuring Young's modulus)
A tensile test was performed using a universal testing machine (Shimadzu Corporation's "Autograph AG-IS500N") in accordance with JIS K7161 and JIS K7127. In the tensile test, the first test piece and the second test piece were fixed, and the tensile test was performed at a tensile speed of 50 mm/min. A stress-strain curve was created at this time, and the Young's modulus was calculated from the slope of the stress-strain curve at the beginning of the test.
The measurement results of the Young's modulus of the pressure-sensitive adhesive sheets according to Example 1, Example 2 and Comparative Example 1 are shown in Table 1.

As shown in Table 1, the adhesive sheets according to Examples 1 and 2 had F _B1 /F _A1 of 30 or less, and the ratio F _B1 /F _A1 of the tensile strength of the portion of the adhesive sheet to which the semiconductor chip is not attached to the tensile strength of the portion to which the semiconductor chip is attached was smaller than that of Comparative Example 1. Therefore, according to the adhesive sheets according to Examples 1 and 2, when the adhesive sheet is spread in the expanding step to expand the distance between the semiconductor chips, the difference in the amount of elongation in the in-plane direction of the adhesive sheet is small, resulting in excellent expandability and enabling small variation in the distance between the semiconductor chips.

(Method for evaluating suppression of adhesive bleeding)
A 300 mm wide pressure-sensitive adhesive sheet with hardened portions formed at both widthwise ends was wound up to prepare a roll. The roll was stored at 40° C. for 3 days, after which it was visually or microscopically confirmed whether the pressure-sensitive adhesive had seeped out from the roll ends. The evaluation criteria for the suppression of seepage were set as follows. In this example, evaluation A was judged to be acceptable.
Evaluation criteria for exudation suppression Evaluation A: No change in appearance at the roll end Evaluation B: Change in appearance at the roll end

(Method of evaluating variability)
The pressure-sensitive adhesive sheets prepared in the Examples and Comparative Examples were cut to a size of 210 mm x 210 mm to obtain test pressure-sensitive adhesive sheets, with each side of the cut sheet being 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. 7 shows a plan view of the expanding device 100. In FIG. 7, 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. 7.

7, 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 7, 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 adhesive sheet were fixed with a gripping jig, and the test adhesive sheet was expanded by an expansion amount of 200 mm at a speed of 5 mm/s in the X-axis direction and the Y-axis direction. As a result of the first expansion test, the area of the test 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. The adhesive sheets of Examples 5 and 6 could not be expanded.

After the test pressure-sensitive adhesive sheet was expanded by the first expansion test, the expanded state of the test pressure-sensitive adhesive sheet 200 was maintained by a ring frame.
The standard deviation was calculated based on the positional relationship between the chips while maintaining the expanded state, and the variation was evaluated. The position of the chip on the test adhesive sheet was measured using a CNC image measuring device (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 the variation were set as follows. In this embodiment, evaluation A or evaluation B was judged to be acceptable.
Evaluation Criteria for Variation Evaluation A: The standard deviation was 100 μm or less.
Evaluation B: The standard deviation was 200 μm or less.
Evaluation C: The standard deviation was 201 μm or more.

(Method for evaluating adhesive lifting at 100% elongation)
A third test piece was prepared by cutting out the adhesive sheet in a length direction of 150 mm and a width of 25 mm so as to include a cured portion where the energy ray curable resin was cured. The third test piece was held by a pair of chucks of a tensile tester. The tensile tester used was an Autograph AG-IS manufactured by Shimadzu Corporation. The distance between the chucks holding the third test piece was set to 100 mm. When the sheet was stretched at a speed of 5 mm/sec until the distance between the chucks reached 200 mm, it was visually confirmed whether the cured portion of the adhesive layer peeled off at the interface with the substrate and whether lifting occurred. The evaluation criteria for adhesive lifting at an elongation of 100% were set as follows. In this example, evaluation A was judged to be acceptable.
Evaluation criteria for adhesive lifting at 100% elongation: Evaluation A: No lifting occurred in the cured portion of the adhesive layer at 100% elongation. Evaluation B: Lifting occurred in one or more places in the cured portion of the adhesive layer at 100% elongation.

(Evaluation method for area expandability)
During the first expand test described above, it was visually confirmed whether the cured portion of the adhesive layer peeled off at the interface with the substrate, causing lifting. The evaluation criteria for area expandability were set as follows. In this example, evaluation A was judged to be acceptable. The adhesive sheets of Examples 5 and 6 could not be evaluated because they could not be expanded.
Evaluation criteria for area expandability Evaluation A: No lifting of the cured portion of the pressure-sensitive adhesive layer occurred during the first expand test.
Evaluation B: During the first expanding test, lifting occurred in one or more locations in the cured portion of the pressure-sensitive adhesive layer.

The adhesive sheets of Examples 2 to 6 had hardened areas at both ends in the width direction, which prevented the adhesive from seeping out. Furthermore, in the adhesive sheets of Examples 2 and 3, no lifting of the adhesive occurred at 100% elongation or during the first expand test. This is thought to be because the hardened areas of the adhesive sheets of Examples 2 and 3 were formed by UV irradiation with an output of approximately 40% to 50%, and the degree of hardening of the hardened areas was appropriately controlled.

1...adhesive sheet, 10...substrate, 20...adhesive layer, CP1...first semiconductor chip, CP2...second semiconductor chip.

Claims (9)

An adhesive sheet,
The adhesive layer includes a substrate and a pressure-sensitive adhesive layer.
The substrate contains a thermoplastic elastomer or a rubber-based material,
The pressure-sensitive adhesive layer contains an energy ray-curable resin,
the pressure -sensitive adhesive layer has a cured portion at both ends in a width direction of the pressure-sensitive adhesive layer where the energy ray curable resin is cured by energy rays, and an uncured portion at which the energy ray curable resin is not cured by the energy rays,
A first test piece having a width of 25 mm was prepared from the pressure-sensitive adhesive sheet in a region corresponding to the uncured portion, and the uncured portions of the substrate and the pressure-sensitive adhesive layer at both ends of the first test piece in the longitudinal direction were gripped with grippers to measure the tensile strength F _A1 when pulled 0.5 mm by a tensile tester;
A first semiconductor chip and a second semiconductor chip having a vertical dimension of 45 mm, a horizontal dimension of 35 mm, and a thickness dimension of 0.625 mm are aligned with the side of the first semiconductor chip and the second semiconductor chip having a vertical dimension of 45 mm along the longitudinal direction of the first test piece, and a distance between the first semiconductor chip and the second semiconductor chip is set to 35 μm. The first semiconductor chip is attached to the adhesive layer of the uncured portion at one end side of the longitudinal direction of the first test piece, and the second semiconductor chip is attached to the adhesive layer of the uncured portion at the other end side of the longitudinal direction of the first test piece to prepare a second test piece. The substrate, the adhesive layer of the uncured portion, and the semiconductor chip at each end in the longitudinal direction of the second test piece are held with a gripper, and the tensile strength F _B1 when pulled 0.5 mm by a tensile tester satisfies the relationship of the following mathematical formula (Math 1A),
During the manufacturing process of a semiconductor device, the device is used in an expanding process for expanding the space between multiple semiconductor chips.
Adhesive sheet.
F _B1 /F _A1 ≦30...(Math 1A) a third test piece is prepared by cutting the adhesive sheet along the longitudinal direction to a size of 150 mm in length and 25 mm in width so as to include a cured portion in which the energy ray curable resin is cured; the third test piece is held by a pair of chucks with a chuck distance of 100 mm and extended at a speed of 5 mm/sec until the chuck distance becomes 200 mm; and no lift occurs at the interface between the cured portion and the substrate.
The pressure-sensitive adhesive sheet according to claim 1 . The pressure-sensitive adhesive sheet according to claim 1 or 2,
the pressure-sensitive adhesive sheet 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 when an area ratio (S2/S1)×100 of an area S1 of the pressure-sensitive adhesive sheet before stretching to an area S2 of the pressure-sensitive adhesive sheet after stretching is 381%, the cured portion of the pressure-sensitive adhesive layer does not peel off at the interface with the substrate.
Adhesive sheet. The pressure-sensitive adhesive sheet according to any one of claims 1 to 3,
The tensile strength F _A1 and the tensile strength F _B1 satisfy the relationship of the following formula (Mathematical formula 1B):
Adhesive sheet.
1≦F _B1 /F _A1 ≦30…(Math 1B) The pressure-sensitive adhesive sheet according to any one of claims 1 to 4,
The Young's modulus Y _A1 of the first test piece and the Young's modulus Y _B1 of the second test piece satisfy the relationship of the following mathematical formula (Mathematical Formula 2A):
Adhesive sheet.
Y _B1 /Y _A1 ≦19...(Math. 2A) The pressure-sensitive adhesive sheet according to any one of claims 1 to 5,
The pressure-sensitive adhesive layer contains an acrylic pressure-sensitive adhesive.
Adhesive sheet. The pressure-sensitive adhesive sheet according to any one of claims 1 to 6,
The substrate contains a urethane-based elastomer.
Adhesive sheet. The pressure-sensitive adhesive sheet according to any one of claims 1 to 7,
The pressure-sensitive adhesive layer contains the energy ray-curable resin and an energy ray-curable (meth)acrylic copolymer different from the energy ray-curable resin.
Adhesive sheet. The pressure-sensitive adhesive sheet according to any one of claims 1 to 8,
The pressure-sensitive adhesive sheet is long and wound into a roll.
Adhesive sheet.

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