Expand sheet and expanding method

Abstract

To provide an expand sheet that enables increase of spacing between adjacent semiconductor chips mounted on the expand sheet.SOLUTION: An expand sheet 100 comprising a base material 10 and an adhesive layer 20 provided on one surface of the base material 10, the expand sheet having a tensile modulus of 170 MPa or less at 23°C and a 300% test force of 20 N or more at 23°C.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an expanding sheet and an expanding method. [Background technology]

[0002] For example, a semiconductor wafer is cut into a predetermined shape and size, and is divided into a plurality of semiconductor chips. The individual chips are then spaced apart from one another and then mounted on an object.

[0003] To increase the spacing between the individual chips, for example, an expandable sheet is used. Examples of expandable sheets include an adhesive sheet having a substrate and an adhesive layer provided on the substrate. The individual chips are attached to the adhesive layer of the expandable sheet, and the expandable sheet is then expanded to increase the spacing between the individual chips.

[0004] Patent Document 1 discloses a workpiece processing sheet comprising a substrate and an adhesive layer laminated on one side of the substrate. The workpiece processing sheet disclosed in Patent Document 1 has a static friction force of 10 N or less on the surface of the substrate opposite to the adhesive layer, a tensile modulus of E1 when the substrate is stretched by 1% in a tensile test at 23°C, and a tensile modulus of E2 when the substrate is stretched by 20% in a tensile test at 23°C. 20 When E 20 The tensile elastic modulus ratio calculated by / E1 is 0.25 or more when the static friction force is 1 to 10 N, and is 0.03 or more when the static friction force is less than 1 N. The work processing sheet disclosed in Patent Document 1 can be used as an expand sheet, etc. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-151238 Summary of the Invention [Problem to be solved by the invention]

[0006] By expanding the expandable sheet, the distance between adjacent semiconductor chips attached to the expandable sheet (the so-called kerf width) is expanded. In an expandable sheet to which semiconductor chips are attached, the expandable sheet may be expanded, for example, by pushing up a push-up jig from the side of the expandable sheet to which no semiconductor chips are attached. After the expandable sheet is expanded in this way, the kerf width between adjacent semiconductor chips may be narrow after expansion. A narrow kerf width after expansion is likely to affect the processability of the semiconductor chips. For this reason, when the expandable sheet is expanded by, for example, pushing up a push-up jig, it is desired to maximize the increase in the kerf width after the expandable sheet is expanded.

[0007] The object of the present invention is to provide an expanding sheet that can expand the distance between adjacent semiconductor chips attached to the expanding sheet when the expanding sheet is stretched, compared to conventional expanding sheets, and an expanding method using the expanding sheet. [Means for solving the problem]

[0008] [1] A substrate and a pressure-sensitive adhesive layer provided on one surface of the substrate, The tensile modulus at 23°C is 170 MPa or less, and the 300% test force at 23°C is 20 N or more. Expanded sheet.

[0009] [2] In the expandable sheet according to [1], The substrate contains at least one resin selected from the group consisting of thermoplastic polyurethane and ethylene-(meth)acrylic acid copolymer. Expanded sheet.

[0010] [3] In the expandable sheet according to [2], The substrate comprises the thermoplastic polyurethane. Expanded sheet.

[0011] [4] In the expandable sheet according to any one of [1] to [3], The pressure-sensitive adhesive layer has energy ray curability. Expanded sheet.

[0012] [5] An expanding method for expanding an expanding sheet to expand the distance between adjacent workpieces attached to the expanding sheet, The expandable sheet is an expandable sheet according to any one of [1] to [4]. Expanding method. [Effects of the Invention]

[0013] According to one aspect of the present invention, an expandable sheet can be provided that, when expanded, can expand the distance between adjacent semiconductor chips attached to the expandable sheet compared to conventional expandable sheets, and an expansion method using the expandable sheet can be provided. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic cross-sectional view illustrating an example of an expanding sheet according to the present embodiment. [Figure 2] (A) is an explanatory diagram that schematically shows an example of the state before the expandable sheet according to this embodiment is expanded, and (B) is an explanatory diagram that schematically shows an example of the state after the expandable sheet according to this embodiment is expanded. DETAILED DESCRIPTION OF THE INVENTION

[0015] A preferred embodiment of the present invention will be described below by way of example, but the present invention is not limited to the content of the embodiment.

[0016] [Expanded Sheet] The expandable sheet according to this embodiment includes a substrate and a pressure-sensitive adhesive layer, and has a tensile modulus of elasticity of 170 MPa or less at 23°C and a 300% test force of 20 N or more at 23°C.

[0017] The expandable sheet according to the present embodiment will be described below with reference to the drawings. Fig. 1 shows a schematic cross-sectional view of an example of the expandable sheet according to the present embodiment. Fig. 2(A) and Fig. 2(B) show an example of the state of the expandable sheet according to the present embodiment before and after expansion. Note that some parts of the drawings are enlarged or reduced in size to facilitate explanation.

[0018] As shown in FIG. 1 , the expandable sheet 100 includes a substrate 10 and a pressure-sensitive adhesive layer 20. The expandable sheet 100 satisfies both of the following conditions (1) and (2): (1) The tensile modulus at 23°C is 170 MPa or less. (2) The 300% test force at 23°C is 20 N or more. In the expandable sheet 100, the substrate 10 includes a first main surface 10A of the substrate 10 and a second main surface 10B opposite to the first main surface 10A. In the expandable sheet 100, the first main surface 10A of the substrate 10 is the surface that faces the pressure-sensitive adhesive layer 20, and the second main surface 10B is the outer surface of the substrate 10. The pressure-sensitive adhesive layer 20 is provided in direct contact with the substrate 10, and the first main surface 10A of the substrate 10 faces the second main surface 20B of the pressure-sensitive adhesive layer 20. The first main surface 20A of the pressure-sensitive adhesive layer 20 is an adhesive surface. Here, the main surface refers to the largest surface of each of the substrate 10 and the pressure-sensitive adhesive layer 20, and refers to the surface facing the thickness direction (i.e., the stacking direction of the layers).

[0019] FIG. 2A shows an example of the state after each semiconductor chip CP separated from the dicing tape has been transferred to the expanding sheet 100, prior to expanding the expanding sheet 100. As shown in FIG. 2A, each semiconductor chip CP is attached to the adhesive layer 20 of the expanding sheet 100. Each semiconductor chip CP has a first surface CP1 and a second surface CP2, with the second surface CP2 attached to the first main surface 20A of the adhesive layer 20. The semiconductor chip CP may have a circuit on either the first surface CP1 or the second surface CP2. The surface without the circuit is the back surface of the semiconductor chip CP. A ring frame RF is attached to the first main surface 20A of the adhesive layer 20 at the periphery. The expanding sheet 100 with the semiconductor chips CP and ring frames RF attached thereto is expanded by an expanding device (not shown). The expanding device includes a stage ST as a push-up jig. The expanding sheet 100 with the semiconductor chips CP and ring frame RF attached thereto is placed on the stage ST with the second main surface 10B of the base material 10 facing the stage ST. Thereafter, the ring frame RF is fixed to an expanding device.

[0020] The state shown in Figure 2(B) is an example of the state after the expandable sheet 100 has been expanded by an expandable device (not shown). As shown in Figure 2(B), with the ring frame RF fixed to the expandable device (not shown), the stage ST of the expandable device is raised in the direction of arrow Z to push up the expandable sheet 100 from the second main surface 10B side of the substrate 10, thereby expanding the expandable sheet 100 in the radial direction of arrow R. Here, arrow R shown in Figure 2(B) represents the radial direction, and the expandable sheet 100 does not expand only in the direction of arrow R, but rather expands throughout the entire radial direction, including the front and back sides of the paper in Figure 2(B).

[0021] By satisfying the above conditions (1) and (2), the expandable sheet 100 according to this embodiment can achieve a greater distance between adjacent semiconductor chips CP attached to the expandable sheet 100 than conventional expandable sheets when the expandable sheet 100 is expanded. As shown in FIG. 2(B), when the expandable sheet 100 is expanded by the stage ST, the stage ST comes into contact with the second main surface 10B of the substrate 10 in the expandable sheet 100. If the tensile modulus of the expandable sheet 100 is too high, pushing up the stage ST will cause only the end of the expandable sheet 100 in contact with the stage ST to expand, or only the end of the expandable sheet 100 will be prone to yielding. Furthermore, if the 300% test force is too low, frictional resistance between the stage ST and the expandable sheet 100 in contact with the stage ST will make it difficult to increase the distance between adjacent semiconductor chips CP attached to the adhesive layer 20 of the expandable sheet 100. In particular, the distance between adjacent semiconductor chips CP on the expanding sheet 100 located near the center of the stage ST is difficult to expand and does not reach a predetermined distance. For this reason, the expanding sheet 100 is configured to have a 300% test force that is not too high in tensile elasticity and is not too low so as to be unaffected by the frictional resistance between the stage ST and the expanding sheet 100. As a result, it is believed that the expanding sheet 100 can increase the kerf width between semiconductor chips CP attached to the expanding sheet 100 after expansion, compared to conventional expanding sheets.

[0022] While an example of an expandable sheet according to the present embodiment has been described above with reference to FIG. 1, the expandable sheet according to the present embodiment is not limited thereto. The expandable sheet according to the present embodiment may take various forms as long as it has the above-described configuration. For example, in the expandable sheet 100, a release film (not shown) may be provided on the first main surface 20A of the pressure-sensitive adhesive layer 20. When a release film is provided, the release film is laminated on the first main surface 20A, which is the adhesive surface of the pressure-sensitive adhesive layer 20, for example, until the expandable sheet 100 is used.

[0023] Furthermore, while an example of the state of the expandable sheet according to this embodiment before and after it is stretched has been described with reference to Figures 2(A) and 2(B), the state of the expandable sheet according to this embodiment before and after it is stretched is not limited to the states shown in Figures 2(A) and 2(B). Figures 2(A) and 2(B) have been described with an example of stretching the expandable sheet 100 by raising a push-up jig, but in addition to this method, the expandable sheet 100 may also be stretched by lowering the expandable sheet 100 and pressing it against a member similar to a push-up jig.

[0024] Specific examples of the layers constituting the expandable sheet according to this embodiment will be described below. In the following description, reference numerals will be omitted.

[0025] <Base material> The substrate is not particularly limited as long as it has properties suitable for expanding the expandable sheet. The substrate is preferably made of a resin, and more preferably a resin film.

[0026] Examples of resins constituting the substrate include polyester resins (polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.), polyolefin resins (polyethylene, polypropylene, polybutene, polybutadiene, polymethylpentene, ethylene-norbornene copolymer, norbornene resin, and ethylene copolymer (ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer, etc.)), polyvinyl chloride resins (polyvinyl chloride and vinyl chloride copolymer, etc.), (meth)acrylic acid ester copolymer, thermoplastic polyurethane, polyamide, polyimide, polystyrene, polycarbonate, fluororesin, and ionomer. The substrate may be a single-layer film of the above resin, or a laminate film in which two or more layers are laminated. When the substrate is a laminate film, the resins in each layer may be the same or different.

[0027] From the viewpoint of environmental friendliness, the resin constituting the substrate is preferably a resin other than polyvinyl chloride resin. In other words, the substrate preferably does not contain polyvinyl chloride resin. In order to facilitate the expansion of the distance between adjacent semiconductor chips attached to the expandable sheet 100, the resin constituting the substrate preferably contains one or two of thermoplastic polyurethane and ethylene-(meth)acrylic acid copolymer. From the same viewpoint, it is also preferable to use only one or two of thermoplastic polyurethane and ethylene-(meth)acrylic acid copolymer. In other words, the substrate preferably contains at least one resin selected from the group consisting of thermoplastic polyurethane and ethylene-(meth)acrylic acid copolymer, and more preferably contains thermoplastic polyurethane.

[0028] In this specification, "(meth)acrylic" means both acrylic and methacrylic, and the same applies to other similar terms.

[0029] The substrate may contain various additives, as necessary, such as a colorant, a flame retardant, a plasticizer, an antistatic agent, a lubricant, a filler, etc. In addition, when the pressure-sensitive adhesive layer is energy ray-curable, the substrate preferably has transparency to energy rays.

[0030] The arithmetic mean roughness Ra of the substrate is preferably 0.3 μm or more, more preferably 0.5 μm or more, and even more preferably 0.8 μm or more. For example, if the substrate contains at least one resin selected from the group consisting of thermoplastic polyurethane and ethylene-(meth)acrylic acid copolymer and the arithmetic mean roughness Ra of the substrate is 0.3 μm or more, the distance between adjacent semiconductor chips attached to the expandable sheet can be more easily increased.

[0031] The Shore A hardness of the substrate measured in accordance with JIS K 7311:1995 is preferably at least 80, more preferably at least 85. For example, if the substrate contains at least one resin selected from the group consisting of thermoplastic polyurethane and ethylene-(meth)acrylic acid copolymer, and the Shore A hardness of the substrate is at least 80, the distance between adjacent semiconductor chips attached to the expandable sheet can be more easily increased.

[0032] From the viewpoint of increasing the distance between adjacent semiconductor chips attached to the expandable sheet, the thickness of the substrate is preferably 60 μm or more, more preferably 70 μm or more, and even more preferably 80 μm or more. The thickness of the substrate is preferably 500 μm or less, more preferably 300 μm or less, and even more preferably 200 μm or less. For example, if the substrate contains at least one resin selected from the group consisting of thermoplastic polyurethane and ethylene-(meth)acrylic acid copolymer and the thickness of the substrate is 60 μm or more, the distance between adjacent semiconductor chips attached to the expandable sheet can be increased more easily. If the thickness of the substrate is 500 μm or less, the expandable sheet can be easily expanded.

[0033] The substrate can be obtained by a known method, for example, by molding a resin composition containing a resin and additives added as needed by a casting method, a calendar method, a T-die extrusion method, an inflation method, or the like.

[0034] <Adhesive layer> The adhesive layer is not particularly limited and is formed from an adhesive composition containing various types of adhesives. Examples of adhesives include acrylic, rubber, silicone, urethane, polyester, and polyvinyl ether adhesives. Among these, an acrylic adhesive is preferred because it easily exerts adhesive strength with the semiconductor chip.

[0035] The pressure-sensitive adhesive may be a non-energy ray-curable pressure-sensitive adhesive that does not have energy ray-curability, or may be an energy ray-curable pressure-sensitive adhesive. Examples of energy rays include ultraviolet rays and electron beams.

[0036] In this specification, "energy ray curable" means a property of being cured by irradiation with energy rays, and "non-energy ray curable" means a property of not being cured even when irradiated with energy rays.

[0037] When the adhesive is energy ray-curable, irradiating the adhesive layer attached to the semiconductor chip with energy rays cures the adhesive, reducing its adhesive strength to the semiconductor chip. This allows the semiconductor chip and the expandable sheet to be easily separated. From this perspective, the adhesive is preferably an energy ray-curable adhesive, and more preferably an ultraviolet-curable adhesive.

[0038] (energy ray curable adhesive) When the adhesive is energy ray-curable, the energy ray-curable adhesive is composed of an energy ray-curable adhesive resin. The energy ray-curable adhesive resin may contain the components exemplified in (I) to (III) below. The adhesive resin preferably contains any one of the components (I), (II), or (III) below. In this specification, the energy ray-curable adhesive resin collectively refers to the components exemplified in (I) to (III) below.

[0039] (I): A component containing a non-energy ray curable polymer and an energy ray curable compound. (II): A component that does not contain an energy ray-curable compound and contains an energy ray-curable polymer in which an unsaturated group has been introduced into the side chain of a non-energy ray-curable polymer. (III): A component containing an energy ray-curable compound and an energy ray-curable polymer in which an unsaturated group has been introduced into the side chain of a non-energy ray-curable polymer.

[0040] In the adhesive resin, the non-energy ray curable polymer is preferably a (meth)acrylic copolymer. The (meth)acrylic copolymer as the non-energy ray curable polymer can be composed of the same components as the (meth)acrylic copolymer before being reacted with the unsaturated group-containing compound, which will be described later in the section on (meth)acrylic copolymers.

[0041] [Energy ray curable compound] The energy ray-curable compound has an energy ray-curable double bond in the molecule, and is a compound that polymerizes and hardens when irradiated with energy rays (for example, ultraviolet rays).

[0042] The energy ray-curable compound is preferably a (meth)acrylic compound. The energy ray-curable compound is preferably an ultraviolet ray-curable compound. The energy ray-curable compound is more preferably an ultraviolet ray-curable (meth)acrylic compound.

[0043] Examples of the energy ray curable compound 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 compound include acrylates such as trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, pentaerythritol triacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate, 1,4-butylene glycol diacrylate, and 1,6-hexanediol diacrylate; acrylates containing a cyclic aliphatic skeleton such as dicyclopentadiene dimethoxy diacrylate and isobornyl acrylate; and acrylate compounds such as polyethylene glycol diacrylate, oligoester acrylate, urethane acrylate oligomer, epoxy-modified acrylate, polyether acrylate, and itaconic acid oligomer. One type of energy ray curable compound may be used alone, or two or more types may be used in combination.

[0044] The molecular weight of the energy ray-curable compound is usually 100 or more and 30,000 or less, and preferably about 300 or more and 10,000 or less. If the molecular weight of the energy ray-curable compound is 100 or more, the effect of suppressing adhesive residue is enhanced. If the molecular weight of the energy ray-curable compound is 300 or more, the effect of suppressing adhesive residue is further enhanced.

[0045] The energy ray-curable compound is preferably a polyfunctional energy ray-curable compound. The number of functional groups in the energy ray-curable compound is preferably 2 or more, more preferably 5 or more, and even more preferably 8 or more. When the number of functional groups is within the above range, the effect of suppressing adhesive transfer is further enhanced.

[0046] [(Meth)acrylic copolymer] It is also preferable that the pressure-sensitive adhesive further contains a (meth)acrylic copolymer, which is different from the energy ray-curable compound described above.

[0047] The (meth)acrylic copolymer preferably has an energy ray-curable carbon-carbon double bond, that is, the pressure-sensitive adhesive preferably contains an energy ray-curable compound and an energy ray-curable (meth)acrylic copolymer.

[0048] The pressure-sensitive adhesive preferably contains 10 parts by mass or more of the energy ray-curable compound per 100 parts by mass of the (meth)acrylic copolymer, more preferably 20 parts by mass or more, and even more preferably 25 parts by mass or more. The pressure-sensitive adhesive preferably contains 200 parts by mass or less of the energy ray-curable compound per 100 parts by mass of the (meth)acrylic copolymer, more preferably 160 parts by mass or less, and even more preferably 120 parts by mass or less.

[0049] The weight average molecular weight (Mw) of the (meth)acrylic copolymer is preferably 50,000 (50,000) or more, more preferably 100,000 (100,000) or more, and even more preferably 300,000 (300,000) or more. The weight average molecular weight (Mw) of the (meth)acrylic copolymer is preferably 1,500,000 (1.5 million) or less, and more preferably 1,000,000 (1 million) or less.

[0050] The weight average molecular weight (Mw) in this specification is a value measured by gel permeation chromatography (GPC) in terms of standard polystyrene. The weight average molecular weight (Mw) in this specification can be measured, for example, under the following measurement conditions.

[0051] <Measurement conditions> Measuring device: Tosoh Corporation, HLC-8320 GPC columns (passed in the following order): Tosoh Corporation TSK gel superH-H TSK gel super HM-H TSK gel superH2000 Measurement solvent: tetrahydrofuran ·Measurement temperature: 40℃

[0052] The (meth)acrylic copolymer is preferably a (meth)acrylic acid ester polymer (hereinafter sometimes referred to as "energy ray curable polymer") having a functional group having energy ray curability (energy ray curable group) introduced into the side chain.

[0053] Energy beam curable polymers The energy ray-curable polymer is preferably a copolymer obtained by reacting a (meth)acrylic copolymer having a functional group-containing monomer unit with an unsaturated group-containing compound having a functional group that bonds to the functional group of the (meth)acrylic copolymer.

[0054] The (meth)acrylic copolymer preferably 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.

[0055] The functional group-containing monomer as a constituent unit of the (meth)acrylic copolymer is preferably a monomer having a polymerizable double bond and a functional group in the molecule, and 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, etc.

[0056] Examples of hydroxy 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. One type of hydroxy group-containing monomer may be used alone, or two or more types may be used in combination.

[0057] 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.

[0058] Examples of the amino group-containing monomer or substituted amino group-containing monomer include aminoethyl (meth)acrylate, n-butylaminoethyl (meth)acrylate, etc. The amino group-containing monomer or substituted amino group-containing monomer may be used alone or in combination of two or more.

[0059] As the (meth)acrylic acid ester monomer constituting the (meth)acrylic copolymer, in addition to alkyl (meth)acrylates in which the number of carbon atoms in the alkyl group is 1 or more and 20 or less, for example, monomers having an alicyclic structure in the molecule (alicyclic structure-containing monomers) are preferably used.

[0060] The alkyl(meth)acrylate is preferably an alkyl(meth)acrylate in which the number of carbon atoms in the alkyl group is 1 or more and 18 or less. More 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. One type of alkyl(meth)acrylate may be used alone, or two or more types may be used in combination.

[0061] Preferred examples of the alicyclic structure-containing monomer include cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, adamantyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate. The alicyclic structure-containing monomer may be used alone or in combination of two or more.

[0062] Furthermore, the (meth)acrylic copolymer preferably contains structural units derived from the functional group-containing monomer in a proportion of 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more. The (meth)acrylic copolymer 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.

[0063] Furthermore, the (meth)acrylic copolymer preferably contains structural units 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. The (meth)acrylic copolymer preferably contains structural units 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.

[0064] The (meth)acrylic copolymer 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. In addition to the above-mentioned monomers, the (meth)acrylic copolymer may contain at least one structural unit selected from the group consisting of dimethylacrylamide, vinyl formate, vinyl acetate, styrene, and the like.

[0065] An energy ray-curable polymer can be obtained by reacting the (meth)acrylic copolymer having the functional group-containing monomer unit with an unsaturated group-containing compound having a functional group bonded to the functional group.

[0066] The functional group of the unsaturated group-containing compound can be appropriately selected depending on the type of functional group of the functional group-containing monomer unit of the (meth)acrylic copolymer.For example, when the functional group of the (meth)acrylic copolymer is a hydroxy group, an amino group, or a substituted amino group, the functional group of the unsaturated group-containing compound is preferably an isocyanate group or an epoxy group, and when the functional group of the (meth)acrylic copolymer is an epoxy group, the functional group of the unsaturated group-containing compound is preferably an amino group, a carboxy group, or an aziridinyl group.

[0067] The unsaturated group-containing compound contains at least one energy ray-polymerizable carbon-carbon double bond in one molecule, preferably 1 to 6, and more preferably 1 to 4.

[0068] Examples of unsaturated group-containing compounds include 2-methacryloyloxyethyl isocyanate (2-isocyanatoethyl methacrylate), meta-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.

[0069] The unsaturated group-containing compound 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, relative to the number of moles of the functional group-containing monomer in the (meth)acrylic copolymer. The unsaturated group-containing compound is preferably used in a proportion (addition rate) of 95 mol % or less, more preferably 93 mol % or less, and even more preferably 90 mol % or less, relative to the number of moles of the functional group-containing monomer in the (meth)acrylic copolymer.

[0070] In the reaction between the (meth)acrylic copolymer and the unsaturated group-containing compound, the reaction temperature, pressure, solvent, time, presence or absence of a catalyst, and type of catalyst can be appropriately selected depending on the combination of the functional groups of the (meth)acrylic copolymer and the unsaturated group-containing compound. As a result, the functional groups of the (meth)acrylic copolymer and the unsaturated group-containing compound react with each other, and an unsaturated group is introduced into the side chain of the (meth)acrylic copolymer (i.e., a functional group having energy ray curability (energy ray-curable group) is introduced into the side chain), thereby obtaining an energy ray-curable polymer.

[0071] When a catalyst is used in the reaction between the (meth)acrylic copolymer and the unsaturated group-containing compound, the reaction between the (meth)acrylic copolymer and the unsaturated group-containing compound is preferably carried out in the presence of at least one organometallic catalyst selected from the group consisting of organotin compounds, zirconium complexes, zinc complexes, and zirconium-containing metal soaps. The use of an organometallic catalyst facilitates improved adhesion to the substrate, and facilitates suppression of peeling between the substrate and the pressure-sensitive adhesive layer. From the viewpoint of environmental friendliness, the organometallic catalyst is preferably at least one organometallic catalyst selected from the group consisting of zirconium complexes, zinc complexes, and zirconium-containing metal soaps.

[0072] The organometallic catalyst may be an organotin compound. Organotin compounds as organometallic catalysts have a high advantage in terms of reactivity between the (meth)acrylic copolymer and the unsaturated group-containing compound. Specific examples of organotin compounds include dibutyltin dilaurate (DBTDL), dioctyltin dilaurate (DOTDL), dibutyltin diacetate (DBTDA), dioctyltin diacetate (DOTDA), dioctyltin maleate (DOTM), and dibutyltin maleate (DBTM). Among these, the organotin compound as the organometallic catalyst used in the reaction between the (meth)acrylic copolymer and the unsaturated group-containing compound preferably contains dibutyltin dilaurate (DBTDL).

[0073] When an organotin compound is used as the organometallic catalyst, the content of the organotin compound in the adhesive resin is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and even more preferably 0.02 parts by mass or more, relative to 100 parts by mass of the total amount of the monomers constituting the (meth)acrylic copolymer. The content of the organotin compound in the adhesive resin is preferably less than 0.3 parts by mass, more preferably 0.1 parts by mass or less, and even more preferably 0.07 parts by mass or less, relative to 100 parts by mass of the total amount of the monomers constituting the (meth)acrylic copolymer.

[0074] The weight average molecular weight (Mw) of the energy ray curable polymer is preferably 50,000 (50,000) or more, more preferably 100,000 (100,000) or more, and even more preferably 300,000 (300,000) or more. The weight average molecular weight (Mw) of the energy ray curable polymer is preferably 1,500,000 (1.5 million) or less, and more preferably 1,000,000 (1 million) or less.

[0075] [Photopolymerization initiator] When the pressure-sensitive adhesive composition contains a photocurable compound, specifically an ultraviolet-curable compound (e.g., an ultraviolet-curable resin), the pressure-sensitive adhesive composition preferably contains a photopolymerization initiator. When the pressure-sensitive adhesive composition contains a photopolymerization initiator, the polymerization and curing time and the amount of light irradiation can be reduced.

[0076] Specific examples of the photopolymerization initiator include a benzoin compound, an acetophenone compound, an acylphosphine oxide compound, a titanocene compound, a thioxanthone compound, and a peroxide compound. Further examples of the photopolymerization initiator include a photosensitizer such as an amine or a quinone.

[0077] More specific examples of the photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl phenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyrolnitrile, dibenzyl, diacetyl, 8-chloroanthraquinone, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide. The photopolymerization initiator may be used alone or in combination of two or more.

[0078] The photopolymerization initiator is preferably used in an amount of 0.01 parts by mass or more, more preferably 0.03 parts by mass or more, and even more preferably 0.05 parts by mass or more, per 100 parts by mass of the adhesive resin of any one of the above embodiments (I), (II), or (III). The photopolymerization initiator is preferably used in an amount of 10 parts by mass or less, more preferably 5 parts by mass or less, per 100 parts by mass of the adhesive resin of any one of the above (I), (II), or (III).

[0079] When the adhesive resin contains a (meth)acrylic copolymer and an energy ray-curable compound, the photopolymerization initiator 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 energy ray-curable compound. When the adhesive resin contains a (meth)acrylic copolymer and an energy ray-curable compound, the photopolymerization initiator 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 energy ray-curable compound.

[0080] [Crosslinking agent] The pressure-sensitive adhesive composition may contain a crosslinking agent. The crosslinking agent may be a polyfunctional compound reactive with functional groups contained in the (meth)acrylic copolymer or the like. Examples of polyfunctional compounds used in the pressure-sensitive adhesive composition 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.

[0081] When the adhesive resin is the adhesive resin of the above embodiment (I), the amount of the crosslinking agent is preferably 0.01 parts by mass or more, and more preferably 1 part by mass or more, per 100 parts by mass of the (meth)acrylic copolymer. When the adhesive resin is the adhesive resin of the above embodiment (I), the amount of the crosslinking agent is preferably 30 parts by mass or less, and more preferably 20 parts by mass or less, per 100 parts by mass of the (meth)acrylic copolymer.

[0082] When the adhesive resin is an adhesive resin of the above embodiment (II), the amount of crosslinking agent is preferably 0.01 parts by mass or more, and more preferably 0.1 parts by mass or more, per 100 parts by mass of the polymer having an unsaturated group introduced into the side chain of the non-energy ray-curable polymer. When the adhesive resin is an adhesive resin of the above embodiment (II), the amount of crosslinking agent is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, per 100 parts by mass of the polymer having an unsaturated group introduced into the side chain of the non-energy ray-curable polymer.

[0083] When the adhesive resin is an adhesive resin of the above-mentioned embodiment (III), the amount of the crosslinking agent is preferably 0.01 parts by mass or more, and more preferably 0.1 parts by mass or more, per 100 parts by mass of the polymer having an unsaturated group introduced into the side chain of the non-energy ray-curable polymer. When the adhesive resin is an adhesive resin of the above embodiment (III), the amount of crosslinking agent is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, per 100 parts by mass of the polymer having an unsaturated group introduced into the side chain of the non-energy ray-curable polymer.

[0084] In addition to the above components, the pressure-sensitive adhesive composition may contain other components such as an antistatic agent, an antioxidant, a softener (plasticizer), a filler, an anti-rust agent, a pigment, and a dye.

[0085] From the viewpoint of being able to further increase the distance between adjacent semiconductor chips attached to the expandable sheet, it is preferable that the adhesive resin be the adhesive resin of the above embodiment (II). That is, it is preferable that the adhesive layer does not contain an energy ray-curable compound, but contains an energy ray-curable polymer in which an unsaturated group has been introduced into the side chain of a non-energy ray-curable polymer. From a similar viewpoint, it is preferable that the adhesive layer does not contain an energy ray-curable compound, but contains an energy ray-curable (meth)acrylic copolymer in which an unsaturated group has been introduced into the side chain of a non-energy ray-curable (meth)acrylic copolymer. From a similar viewpoint, it is also preferable that the adhesive layer further contains a crosslinking agent. From a similar viewpoint, it is also preferable that the adhesive layer further contains a photopolymerization initiator.

[0086] The thickness of the pressure-sensitive adhesive layer is, for example, preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more. The thickness of the pressure-sensitive adhesive layer is, for example, preferably 70 μm or less, more preferably 50 μm or less, even more preferably 30 μm or less, and even more preferably 10 μm or less.

[0087] <Release film> In the expandable sheet according to this embodiment, a release film may be laminated on the first main surface (adhesive surface) of the adhesive layer to protect the adhesive surface until it is attached to a semiconductor chip. The release film is a component that is provided as needed. For example, the release film may be a resin film used as a base material, and at least one surface of the resin film serving as the base material is subjected to a release treatment. Examples of resin films include films of polyester (polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.) and polyolefin (polypropylene, polyethylene, etc.). The release treatment may be performed using a release agent, and examples of the release agent include silicone-based, fluorine-based, and long-chain alkyl-based release agents. The thickness of the release film is not particularly limited, and may be, for example, in the range of 20 μm or more and 250 μm or less.

[0088] [Expanded sheet characteristics] The characteristics of the expandable sheet according to this embodiment will be described.

[0089] <Tensile modulus> The expandable sheet according to this embodiment has a tensile modulus of elasticity at 23°C of 170 MPa or less. From the viewpoint of increasing the distance between adjacent semiconductor chips attached to the expandable sheet, the tensile modulus of elasticity at 23°C is preferably 165 MPa or less, more preferably 120 MPa or less, and even more preferably 80 MPa or less. The lower limit of the tensile modulus of elasticity at 23°C is not particularly limited, and may be, for example, 10 MPa or more or 20 MPa or more. The tensile modulus of elasticity at 23°C can be measured by conducting a tensile test in accordance with JIS K 7161:2014 and JIS K 7127:1999. Specifically, the tensile modulus of elasticity at 23°C can be measured by the method described in the Examples section below.

[0090] <300% test force> In the expandable sheet according to this embodiment, the 300% test force at 23°C is 20 N or more. From the viewpoint of increasing the distance between adjacent semiconductor chips attached to the expandable sheet, the 300% test force at 23°C is preferably 22 N or more, more preferably 30 N or more, and even more preferably 40 N or more. The upper limit of the 300% test force at 23°C is not particularly limited, and may be, for example, 150 N or less or 100 N or less. The 300% test force at 23°C can be measured by conducting a tensile test in accordance with JIS K 7161:2014. Specifically, the 300% test force at 23°C can be measured by the method described in the Examples section below.

[0091] In the expandable sheet according to this embodiment, it is preferable that the tensile modulus at 23°C measured in both the CD and MD directions is 170 MPa or less, and the 300% test force at 23°C measured in both the CD and MD directions is 20 N or more. If the tensile modulus at 23°C and the 300% test force in both the CD and MD directions satisfy the above conditions, the expandable sheet has better expandability. This makes it easier to increase the distance between adjacent semiconductor chips attached to the expandable sheet. In this specification, the MD (machine direction) direction refers to the flow direction during the manufacture of the expandable sheet, and the CD (cross direction) direction refers to the direction perpendicular to the flow direction during the manufacture of the expandable sheet (i.e., the width direction).

[0092] In the expandable sheet according to this embodiment, for example, by selecting the type of resin constituting the substrate, the thickness of the substrate, and the composition of the adhesive, it is possible to satisfy the conditions that the tensile modulus at 23°C is 170 MPa or less and the 300% test force at 23°C is 20 N or more. For example, by selecting a highly flexible resin as the resin constituting the substrate and increasing the thickness, the range of the tensile modulus at 23°C and the range of the 300% test force can be adjusted to fall within the above ranges.

[0093] [Expanded sheet manufacturing method] A preferred method for producing an expanded sheet according to this embodiment will now be described. The method for producing an expanded sheet is not particularly limited. The method for producing an expanded sheet preferably includes, for example, the steps of preparing a substrate, a pressure-sensitive adhesive composition, and a release film; applying the pressure-sensitive adhesive composition to the release-resistant surface (the release-treated surface) of the release film to form a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition; and laminating the substrate on the surface of the pressure-sensitive adhesive layer opposite the release film (the exposed surface of the pressure-sensitive adhesive layer). The substrate, pressure-sensitive adhesive composition, and release film may be the same as those previously described. An example of a method for applying the pressure-sensitive adhesive composition is to prepare a coating liquid containing the pressure-sensitive adhesive composition and, if necessary, a solvent or dispersion medium, and then apply the coating liquid. The coating method is not particularly limited, and examples include spin coating, spray coating, bar coating, knife coating, roll coating, roll knife coating, blade coating, die coating, and gravure coating.

[0094] Examples of the solvent or dispersion medium include aromatic hydrocarbon solvents (benzene, toluene, etc.), ester solvents (ethyl acetate, butyl acetate, etc.), ketone solvents (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), aliphatic hydrocarbon solvents (n-pentane, n-hexane, n-heptane, etc.), and alicyclic hydrocarbon solvents (cyclopentane, cyclohexane, etc.). These solvents or dispersion mediums may be used alone or in combination of two or more.

[0095] The pressure-sensitive adhesive layer can be formed by applying a coating liquid containing a pressure-sensitive adhesive composition to form a coating film, and then heating and drying the coating film.

[0096] The manufacturing method of the expanded sheet according to this embodiment is not limited to the above, and may also be a manufacturing method including the steps of preparing a substrate, a pressure-sensitive adhesive composition, and a release film, laminating the pressure-sensitive adhesive composition on the substrate to provide a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition, and laminating the releasable surface of the release film on the surface of the pressure-sensitive adhesive layer opposite the substrate side.

[0097] When the pressure-sensitive adhesive composition contains a crosslinking agent, it is preferable to form a crosslinked structure in the pressure-sensitive adhesive layer, for example, by changing the drying conditions (temperature, time, etc.) of the coating film coated with a coating liquid containing the pressure-sensitive adhesive composition, or by performing a heat treatment other than drying. The expanded sheet obtained by the above process may also be seasoned. Seasoning conditions include, for example, leaving the sheet at a temperature of 20°C or higher and 50°C or lower (e.g., 23°C) and a relative humidity of 20% RH or higher and 50% RH or lower (e.g., 50% RH) for a period of 3 days to 14 days (e.g., 7 days).

[0098] [How to use the expandable sheet] The shape of the expandable sheet according to the present embodiment is not particularly limited as long as it comprises a base material and a pressure-sensitive adhesive layer, and the expandable sheet may take any shape, such as a tape or label.

[0099] The expandable sheet according to this embodiment can be used, for example, as an adhesive sheet used to expand the distance between individual semiconductor chips. After attaching each individual semiconductor chip to an adhesive layer of the expandable sheet, the expandable sheet is expanded while the individual semiconductor chips are attached to the adhesive layer of the expandable sheet. For example, the expandable sheet according to this embodiment is preferably used in a process in which the expandable sheet, to which the individual semiconductor chips are attached, is fixed with a fixing member and pushed up by a push-up jig from the substrate side opposite the side to which the individual semiconductor chips are attached, thereby expanding the distance between the individual semiconductor chips. When the expandable sheet according to this embodiment is used in such a process, the expandable sheet according to this embodiment is expanded, and the spacing between the individual semiconductor chips in the adhesive layer is expanded to a predetermined distance. Thereafter, for example, the adhesive layer is irradiated with energy rays to reduce the adhesive strength of the adhesive layer to the semiconductor chips. The semiconductor chips are then picked up by a pickup means such as a vacuum collet. It should be noted that, when an expandable sheet is stretched by being pulled in a direction parallel to the expandable sheet, it may be more difficult to increase the kerf width when the expandable sheet is stretched by being pushed up by a push-up jig. Even in the latter case, if the expandable sheet used in the expandable sheet method is the expandable sheet according to this embodiment, the kerf width is likely to increase when the expandable sheet is stretched.

[0100] In the above description, the expanding sheet according to the present embodiment is described as being used to expand the distance between individual semiconductor chips as workpieces, but is not limited to this. In addition to the above, the expanding sheet according to the present embodiment can also be used as an expanding sheet used to expand the distance between individual glass chips as workpieces, for example.

[0101] [Expansion method] The expanding method according to this embodiment is an expanding method for expanding the distance (i.e., kerf width) between adjacent workpieces attached to the expanding sheet by stretching the expanding sheet, where the expanding sheet is the expanding sheet according to this embodiment. Examples of the workpieces include the aforementioned singulated semiconductor chips and singulated glass chips. The expanding method according to this embodiment preferably includes a step of either raising a push-up jig to push up the expanded sheet to which the workpieces have been attached from the substrate side opposite the side to which the workpieces have been attached, thereby stretching the expanded sheet, or holding the outer periphery of the expanded sheet to which the workpieces have been attached with a jig and lowering only the outer periphery, leaving the portion to which the workpieces have been attached. More preferably, the expanding method according to this embodiment includes a step of pushing up the expanded sheet to which the workpieces have been attached with a push-up jig from the substrate side opposite the side to which the workpieces have been attached. In the pushing-up step, the pushing-up jig may be, for example, a cylindrical or columnar jig. In the pushing-up step, the pushing-up height may be, for example, 25 mm or more and 50 mm or less. The pushing-up speed may be, for example, 4 mm / s or more and 15 mm / s or less.

[0102] [Modification 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 achieving the object of the present invention. [Example]

[0103] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0104] Measurements and evaluations in the following examples and comparative examples were carried out by the methods shown below.

[0105] Tensile modulus The tensile modulus of the expanded sheets prepared in each Example and Comparative Example was measured using the following test method. A tensile test was performed using a tensile tester, and the tensile modulus of the expanded sheet was calculated from the resulting tensile stress and strain. Specifically, the expanded sheet obtained in each Example was cut to a size of 15 mm wide x 150 mm long to prepare a measurement sample. The prepared measurement sample was placed in a tension-compression tester (manufactured by A&D Co., Ltd., product name "Tensilon") so that the stretchable portion of the measurement sample (the distance between chucks) was 100 mm. Tensile measurements were then performed at a temperature of 23°C and a tensile speed of 200 mm / min, and the tensile modulus was calculated from the slope of the resulting chart. Table 1 shows only the results in the CD direction.

[0106] [300% test force] The 300% test force was measured for the expanded sheets produced in each Example and Comparative Example using the following test method. The 300% test force of the expanded sheet was determined by conducting a tensile test using a tensile tester. The elongation at which the test sample broke was defined as the breaking elongation, and the test force at which the elongation reached 300% before the test sample broke was defined as the 300% test force. Specifically, the expanded sheet obtained in each Example was cut to a dimension of 15 mm wide x 150 mm long to prepare a test sample. The prepared test sample was placed in a tensile / compression tester (manufactured by A&D Co., Ltd., product name "Tensilon") so that the stretchable portion of the test sample (distance between chucks) was 100 mm. Tensile measurements were then performed at a temperature of 23°C and a tensile speed of 200 mm / min, and the test force at 300% elongation was defined as the 300% test force. Since the distance between the chucks was 100 mm, the 300% test force represents the test force when the expanded sheet between the chucks was stretched to 300 mm. Note that Table 1 shows only the results in the CD direction.

[0107] [Kerf width evaluation] After peeling the release film from the workpiece processing sheet (manufactured by Lintec Corporation, product name "D-485H"), the exposed surface of the adhesive layer was attached to the polished surface of a 6-inch silicon wafer that had been polished with a #2000 grit polish. Next, a dicing ring frame was attached to the peripheral edge of the exposed surface of the workpiece processing sheet (at a position that did not overlap with the silicon wafer). The workpiece processing sheet was then cut to fit the outer diameter of the ring frame. Thereafter, the silicon wafer was diced into individual chips having a size of 1.0 mm x 1.0 mm by dicing under the following dicing conditions using a dicing device.

[0108] <Dicing conditions> Wafer thickness: 350 μm (#2000 polished finish) Dicing equipment: DISCO Corporation, product name "DFD-6362" Blade: DISCO Corporation, product name "ZH05-SD2000-N1-90CC" Blade rotation speed: 30,000 rpm Cutting speed: 100mm / sec Blade height: 0.060 mm (20 μm cut into the base material) Cutting water amount: 1.0L / min Cutting water temperature: 20℃

[0109] After dicing is complete, ultraviolet light is irradiated through the workpiece processing sheet (illuminance: 230 mW / cm 2 ,Light amount: 190mJ / cm 2), and the individual chips were transferred onto the exposed surface of the adhesive layer of the expand sheet produced in each Example and Comparative Example. The expand sheet onto which the chips had been transferred was then attached to a 6-inch ring frame of an expanding device (manufactured by JCM Corporation, product name "SE-100"), and the 6-inch stage, which was a push-up jig, was pushed up at a push-up height of 35 mm and a push-up speed of 5 mm / s to expand the expand sheet. The distance between adjacent individual chips after the expand sheet was measured using an electron microscope (manufactured by KEYENCE Corporation, product name "VHX-8000", magnification 300x). The difference in the distance between adjacent chips before and after expansion (kerf width after expansion - kerf width before expansion) was taken as the increase in kerf width. The chips were measured at five points: the center, top, bottom, left, and right of the wafer. The width of one side of the chip periphery was measured at each point, and the average value was calculated. Based on the above kerf width, the kerf width was evaluated according to the following evaluation criteria.

[0110] <Evaluation criteria> A (◯): The increase in kerf width was 63 μm or more. F(×): The increase in kerf width was less than 63 μm.

[0111] [Example 1] (1) Preparation of adhesive composition A (meth)acrylic acid ester polymer was obtained by polymerizing 60 parts by weight of 2-ethylhexyl acrylate (2EHA), 10 parts by weight of acryloylmorpholine, and 30 parts by weight of 2-hydroxyethyl acrylate by solution polymerization. Subsequently, 2-methacryloyloxyethyl isocyanate (MOI) was added in an amount equivalent to 90 mol% of the 2-hydroxyethyl acrylate constituting the (meth)acrylic acid ester polymer, and dibutyltin dilaurate (DBTDL) was added as a tin-containing catalyst in an amount of 0.025 parts by weight per 100 parts by weight of the (meth)acrylic acid ester polymer. The mixture was then allowed to react at 50°C for 24 hours to obtain a (meth)acrylic acid ester polymer (weight average molecular weight: 800,000) with energy beam-curable groups introduced into the side chains.

[0112] 100 parts by mass (solids content equivalent, same below) of the (meth)acrylic acid ester polymer obtained above with energy ray-curable groups introduced into the side chains, 0.185 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Tosoh Corporation, product name "Coronate L") as a crosslinking agent, and 3 parts by mass of 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one (manufactured by IGM Resins BV, "Irgacure 127") as a photopolymerization initiator were diluted with toluene to obtain a coating solution of an adhesive composition with a solids content of 30% by mass.

[0113] (2) Formation of adhesive layer A coating solution of the above adhesive composition was applied to the release surface of a release film (manufactured by Lintec Corporation, product name "SP-PET381031"), which consisted of a 38 μm-thick polyethylene terephthalate (PET) film with a silicone-based release agent layer formed on one side thereof, and the film was dried by heating to form a 10 μm-thick adhesive layer on the release film.

[0114] (3) Preparation of substrate An ester-based thermoplastic polyurethane (PU) was prepared. Using a single-layer inflation film-making device, the prepared thermoplastic polyurethane was fed into an extruder with a diameter of 150 mm and melt-kneaded. The mixture was then extruded through a single-layer die at a temperature of 205°C, forming a 100 μm-thick thermoplastic polyurethane film, which was used to obtain a substrate.

[0115] The physical properties of the substrate produced in Example 1 were as follows. The arithmetic mean roughness Ra of the substrate was 0.70 μm. The arithmetic mean roughness Ra was measured using a roughness measuring instrument (manufactured by Mitutoyo Corporation, "SVP-3000S4"). The hardness (JIS-A) of the substrate was 90. The hardness of the substrate was measured using a Shore hardness tester. The density of the substrate was 1.12 g / cm 3 The density of the substrate was calculated by dividing the weight of the substrate by the volume of the substrate.

[0116] (4) Production of expanded sheets The exposed surface of the pressure-sensitive adhesive layer formed in the above step (2) was attached to the substrate prepared in the above step (3). The release film was peeled off from the pressure-sensitive adhesive layer to obtain the expanded sheet of Example 1.

[0117] [Example 2] The expanded sheet of Example 2 was obtained in the same manner as Example 1, except that in preparing the (3) substrate of Example 1, an ester-based thermoplastic polyurethane different from the ester-based thermoplastic polyurethane used in Example 1 was used as the thermoplastic polyurethane (PU).

[0118] The physical properties of the substrate produced in Example 2 were as follows. The measurement methods were the same as in Example 1. The arithmetic mean roughness Ra was 0.68 μm. The hardness (JIS-A) of the substrate was 86. The density of the substrate was 1.10 g / cm 3 It was.

[0119] [Example 3] An expanded sheet of Example 3 was obtained in the same manner as in Example 1, except that the substrate was prepared as follows.

[0120] Ethylene-methacrylic acid copolymer (EMAA) (manufactured by Mitsui Dow Polychemicals Co., Ltd., product name "Nucrel N0903HC") was prepared. The prepared EMAA was extruded using a small T-die extruder (manufactured by Toyo Seiki Seisakusho Co., Ltd., product name "Labo Plastomill") to form a 140 μm-thick EMAA film, which was used to obtain a substrate.

[0121] [Example 4] An expanded sheet of Example 4 was obtained in the same manner as in Example 3, except that the thickness of the substrate was changed to 150 μm.

[0122] [Comparative Example 1] An expanded sheet of Comparative Example 1 was obtained in the same manner as in Example 3, except that the thickness of the substrate was changed to 80 μm.

[0123] Comparative Example 2 An expanded sheet of Comparative Example 2 was obtained in the same manner as in Example 3, except that the thickness of the substrate was changed to 70 μm.

[0124] Comparative Example 3 An expanded sheet of Comparative Example 3 was obtained in the same manner as in Example 1, except that the substrate was prepared as follows.

[0125] Styrene-(ethylene / butylene)-styrene copolymer (SEBS) and polyethylene (PE) were prepared. The layer on the side where the adhesive layer was to be formed was the surface layer of the substrate, and the layer on the back side of the layer on the side where the adhesive layer was to be formed was the back layer of the substrate. The prepared SEBS was placed in the hopper on the surface layer side of a Toshiba Machine single-screw extruder (50φmm, L / D=32), and the prepared PE was placed in the hopper on the back layer side. The extruder temperatures were then set as follows: C1: 210°C, C2: 230°C, C3: 230°C, C4: 230°C, and C5: 230°C, and the mixture was co-extruded from a 550mm wide T-die (temperature setting: 230°C, lip opening: 0.3mm). The co-extruded molten resin was cooled and solidified using a winding machine equipped with a cooling roll (cooling roll 700 mm wide x φ350 mm, roll temperature 30°C), and then a lubricant was applied to the back layer to obtain a two-layer laminated substrate with a thickness of 80 μm.

[0126] Comparative Example 4 An expanded sheet of Comparative Example 4 was obtained in the same manner as in Example 1, except that the substrate was prepared as follows.

[0127] Polypropylene (PP) (Prime Polymer Co., Ltd., product name "Prime Polypro E100-GPL"), olefin-based thermoplastic elastomer (TPO) (Mitsui Chemicals, Inc., product name "Tafmer PN2070", PP:PE:Bu = 70:15:15), and antistatic agent (AS agent) (Sanyo Chemical Industries, Ltd., product name "Pelestat") were prepared. The prepared PP, TPO, and AS agent were dry-blended at a mass ratio of PP:TPO:AS agent = 80:15:5. Then, it was put into the hopper of a Toshiba Machine single-screw extruder (50φmm, L / D=32), and the extruder temperature was set as follows: C1: 210 ° C, C2: 230 ° C, C3: 230 ° C, C4: 230 ° C, C5: 230 ° C, and it was extruded from a 550 mm wide T-die (temperature setting: 230 ° C, lip opening 0.3 mm). The extruded molten resin was cooled and solidified on a winding machine equipped with a cooling roll (cooling roll 700 mm wide × φ350 mm, roll temperature 30 ° C), and then a lubricant was applied to the back side on the side where the adhesive layer was not provided, to obtain a single-layer substrate with a thickness of 140 μm.

[0128] [Table 1]

[0129] It can be seen that the expanding sheets of each example had better kerf width evaluation results than the expanding sheets of the comparative examples. From the above results, it was confirmed that the expanding sheet of this embodiment can achieve a greater distance between adjacent semiconductor chips attached to the expanding sheet when expanded, compared to conventional expanding sheets. Furthermore, from the above results, it was confirmed that the expanding method using the expanding sheet of this embodiment can increase the distance between adjacent semiconductor chips attached to the expanding sheet, compared to when conventional expanding sheets are used. [Explanation of symbols]

[0130] 10...substrate, 10A...first main surface of substrate, 10B...second main surface of substrate, 20...adhesive layer, 20A...first main surface of adhesive layer, 20B...second main surface of adhesive layer, 100...expanded sheet, CP...semiconductor chip, CP1...first surface of semiconductor chip, CP2...second surface of semiconductor chip, RF...ring frame, ST...stage.

Claims

1. A substrate and a pressure-sensitive adhesive layer provided on one surface of the substrate, The tensile modulus at 23°C is 170 MPa or less, and the 300% test force at 23°C is 20 N or more. Expanded sheet.

2. The expandable sheet according to claim 1, the substrate contains at least one resin selected from the group consisting of thermoplastic polyurethane and ethylene-(meth)acrylic acid copolymer; Expanded sheet.

3. The expandable sheet according to claim 2, The substrate comprises the thermoplastic polyurethane. Expanded sheet.

4. The expandable sheet according to any one of claims 1 to 3, The pressure-sensitive adhesive layer has energy ray curability. Expanded sheet.

5. An expanding method for expanding an expanding sheet to expand the distance between adjacent workpieces attached to the expanding sheet, The expandable sheet is the expandable sheet according to any one of claims 1 to 3. Expanding method.

Images