Workpiece processing sheet

Abstract

A base material film characterized by comprising a material including a polyester resin that has an alicyclic structure and an elastomer other than the polyester resin. The base material film has excellent flexibility making it possible to have good expandability, and makes it possible to provide a workpiece machining sheet that has good expandability.

Description

[Technical Field]

[0001] The present invention relates to a base film that can be suitably used as a base film for a workpiece processing sheet used in processing workpieces such as semiconductor wafers, and to the workpiece processing sheet. [Background technology]

[0002] Semiconductor wafers such as silicon and gallium arsenide and various packages are manufactured in large diameters, cut into chips (diced), peeled off (picked up), and then transferred to the next process, the mounting process. At this time, the workpieces such as semiconductor wafers are attached to an adhesive sheet (hereinafter sometimes referred to as a "workpiece processing sheet") that has a base material and an adhesive layer, and undergo processing such as backgrinding, dicing, cleaning, drying, expanding, picking up, and mounting.

[0003] In the above-mentioned pickup process, in order to facilitate the pickup of semiconductor chips, the semiconductor chips may be individually pushed up from the side of the workpiece processing sheet opposite to the side on which the semiconductor chips are stacked. In particular, to prevent collisions between semiconductor chips during pickup and to facilitate pickup, the workpiece processing sheet is usually stretched (expanded) to separate the semiconductor chips. Therefore, the workpiece processing sheet is required to have excellent flexibility to enable good expansion.

[0004] Patent Documents 1 and 2 disclose inventions relating to workpiece processing sheets developed for the purpose of achieving good expansion. In particular, Patent Document 1 discloses a dicing film having a base layer and an adhesive layer, the base layer containing a predetermined random polypropylene and a predetermined olefin-based elastomer under predetermined conditions. Patent Document 2 also discloses an adhesive tape comprising an adhesive layer, an adhesive-receiving layer, a thermoplastic elastomer layer, and a resin layer laminated in this order, the thermoplastic elastomer layer being made of a predetermined resin composition. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5494132 [Patent Document 2] Japanese Patent Application Publication No. 11-199840 Summary of the Invention [Problem to be solved by the invention]

[0006] The present inventors have been studying the use of a substrate film composed primarily of a specific polyester resin as the substrate film for a workpiece processing sheet. The inventors have confirmed that such a workpiece processing sheet has various excellent effects, including the effect of suppressing the generation of chips during dicing. Furthermore, the inventors have found that the usefulness of the substrate film can be further enhanced by improving the expandability of the substrate film.

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide a base film having excellent flexibility that allows for good expansion, and a workpiece processing sheet that allows for good expansion. [Means for solving the problem]

[0008] To achieve the above object, first, the present invention provides a substrate film characterized by being made of a material containing a polyester resin having an alicyclic structure and an elastomer other than the polyester resin (Invention 1).

[0009] The base film of the above invention (Invention 1) is made of a material containing a polyester resin having an alicyclic structure and an elastomer other than the polyester resin, and therefore has excellent flexibility, and a work processing sheet using the base film can be expanded well.

[0010] In the above invention (Invention 1), the content of the elastomer in the material is preferably 4% by mass or more and 45% by mass or less (Invention 2).

[0011] In the above inventions (Inventions 1 and 2), the elastomer is preferably a thermoplastic elastomer (Invention 3).

[0012] In the above invention (Invention 3), the thermoplastic elastomer is preferably at least one of a styrene-based elastomer, an acrylic-based elastomer, a urethane-based elastomer, and an olefin-based elastomer (Invention 4).

[0013] In the above inventions (Inventions 1 to 4), the polyester resin preferably contains the dicarboxylic acid having an alicyclic structure as a monomer unit constituting the polyester resin (Invention 5).

[0014] In the above inventions (Inventions 1 to 5), the polyester resin preferably contains the diol having an alicyclic structure as a monomer unit constituting the polyester resin (Invention 6).

[0015] In the above inventions (Inventions 1 to 6), the alicyclic structure preferably has 6 or more and 14 or less carbon atoms constituting the ring (Invention 7).

[0016] In the above inventions (Inventions 1 to 7), the polyester resin preferably contains, as a monomer unit constituting the polyester resin, a dimer acid obtained by dimerizing an unsaturated fatty acid, and the number of carbon atoms of the unsaturated fatty acid is preferably 10 or more and 30 or less (Invention 8).

[0017] In the above inventions (Inventions 1 to 8), the tensile modulus of elasticity measured when the substrate film is subjected to a tensile test in an environment of 23°C at a tensile speed of 200 mm / min is preferably 50 MPa or more and 800 MPa or less (Invention 9).

[0018] In the above inventions (Inventions 1 to 9), the base film preferably has a breaking elongation of 150% or more and 800% or less when subjected to a tensile test at a temperature of 23°C and a tensile speed of 200 mm / min (Invention 10).

[0019] In the above inventions (Inventions 1 to 10), the thickness of the substrate film is preferably 20 μm or more and 600 μm or less (Invention 11).

[0020] In the above inventions (Inventions 1 to 11), it is preferable to use it as a base film constituting a workpiece processing sheet (Invention 12).

[0021] Secondly, the present invention provides a workpiece processing sheet (Invention 13), which is characterized by comprising a base film of the above inventions (Inventions 1 to 12) and an adhesive layer laminated on one side of the base film. [Effects of the Invention]

[0022] The base film according to the present invention has excellent flexibility that allows for good expansion, and the workpiece processing sheet according to the present invention also has good expansion properties. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, an embodiment of the present invention will be described. [Base film] The substrate film according to this embodiment is made of a material containing a polyester resin having an alicyclic structure and an elastomer other than the polyester resin. The substrate film according to this embodiment is made of the above material, resulting in extremely excellent flexibility. In particular, by combining an elastomer with a polyester resin that can exhibit flexibility on its own, the substrate film according to this embodiment has extremely excellent stretchability. Therefore, when the substrate film according to this embodiment is used as the substrate film for a semiconductor processing sheet, the semiconductor processing sheet can be expanded well. Accordingly, in the subsequent pickup process, it becomes easier to push up the chip from the backside, enabling good pickup.

[0024] Although the substrate film of this embodiment can be used for various purposes, since it can provide the effects described above, it is particularly suitable for use as the substrate of a workpiece processing sheet used for processing workpieces such as semiconductor wafers, and is particularly suitable for use as the substrate of a dicing sheet used for dicing workpieces.

[0025] Furthermore, since the substrate film according to the present embodiment is made of a material containing a polyester resin having an alicyclic structure, a workpiece processing sheet constructed using the substrate film can effectively suppress the generation of cutting chips when used in dicing workpieces using a rotating circular blade. This effect of suppressing cutting chips is achieved without irradiating the substrate film according to the present embodiment with radiation such as electron beams or gamma rays. Therefore, the substrate film according to the present embodiment allows the production of a workpiece processing sheet at lower production costs than conventional substrate films produced by methods including a radiation irradiation step.

[0026] Furthermore, the base film of this embodiment, which is made from the above-mentioned polyester resin, has good transparency, making it easy to view and inspect the work through the work processing sheet that includes this base film.

[0027] 1.Material of the base film As described above, the substrate film according to this embodiment is made of a material containing a polyester resin having an alicyclic structure and an elastomer other than the polyester resin.

[0028] (1) Polyester resin The specific composition of the polyester resin is not particularly limited as long as it has an alicyclic structure.

[0029] From the viewpoint of making it easier for the base film to have better flexibility, the alicyclic structure of the polyester resin preferably has 6 or more carbon atoms constituting the ring. The number of carbon atoms is preferably 14 or less, and particularly preferably 10 or less. In particular, the number of carbon atoms is preferably 6. The alicyclic structure may be a monocyclic structure consisting of one ring, a bicyclic structure consisting of two rings, or a structure consisting of three or more rings.

[0030] Furthermore, from the viewpoint of making the base film more likely to have good flexibility, the polyester resin preferably contains a dicarboxylic acid having an alicyclic structure as a monomer unit constituting the polyester resin. From the same viewpoint, the polyester resin preferably contains a diol having an alicyclic structure as a monomer unit constituting the polyester resin. Although only one of such dicarboxylic acid and diol may be contained in the polyester resin, from the viewpoint of making the base film more likely to have good flexibility, it is preferable that the polyester resin contains both such dicarboxylic acid and diol.

[0031] The structure of the dicarboxylic acid described above is not particularly limited as long as it has an alicyclic structure and two carboxy groups. For example, the dicarboxylic acid may have a structure in which two carboxy groups are bonded to an alicyclic structure, or a structure in which an alkyl group or the like is further inserted between the alicyclic structure and the carboxy group. Preferred examples of such dicarboxylic acids include 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,4-decahydronaphthalenedicarboxylic acid, 1,5-decahydronaphthalenedicarboxylic acid, 2,6-decahydronaphthalenedicarboxylic acid, and 2,7-decahydronaphthalenedicarboxylic acid. Among these, 1,4-cyclohexanedicarboxylic acid is preferred. These dicarboxylic acids may also be derivatives such as alkyl esters. Examples of such alkyl ester derivatives include alkyl esters having 1 to 10 carbon atoms. More specific examples include dimethyl esters and diethyl esters, with dimethyl esters being particularly preferred.

[0032] When the polyester resin of this embodiment contains a dicarboxylic acid having an alicyclic structure as a constituent monomer unit thereof, the proportion of the dicarboxylic acid monomer to the total monomer units constituting the polyester resin is preferably 20 mol% or more, more preferably 25 mol% or more, particularly preferably 30 mol% or more, and even more preferably 35 mol% or more. Furthermore, this proportion is preferably 60 mol% or less, more preferably 55 mol% or less, particularly preferably 50 mol% or less, and even more preferably 45 mol% or less. Within these ranges, the substrate film of this embodiment is more likely to have excellent flexibility.

[0033] Furthermore, when the polyester resin of the present embodiment contains a dicarboxylic acid having an alicyclic structure as a constituent monomer unit thereof, the ratio of the dicarboxylic acid having an alicyclic structure to the total dicarboxylic acids having a ring structure constituting the polyester resin is preferably 60% or more, more preferably 70% or more, particularly preferably 80% or more, and even more preferably 90% or more. When the ratio is 60% or more, the base film of the present embodiment is likely to have better flexibility. The upper limit of this ratio is not particularly limited and may be, for example, 100% or less. The dicarboxylic acid having a ring structure includes not only dicarboxylic acids having an alicyclic structure but also dicarboxylic acids having an aromatic ring structure.

[0034] The structure of the diol is not particularly limited as long as it has an alicyclic structure and two hydroxy groups. For example, the diol may have a structure in which two hydroxy groups are bonded to an alicyclic structure, or a structure in which an alkyl group or the like is further inserted between the alicyclic structure and the hydroxy group. Preferred examples of such diols include 1,2-cyclohexanediol (particularly 1,2-cyclohexanedimethanol), 1,3-cyclohexanediol (particularly 1,3-cyclohexanedimethanol), 1,4-cyclohexanediol (particularly 1,4-cyclohexanedimethanol), 2,2-bis-(4-hydroxycyclohexyl)-propane, etc., and among these, it is preferred to use 1,4-cyclohexanedimethanol.

[0035] When the polyester resin of this embodiment contains a diol having an alicyclic structure as a constituent monomer unit thereof, the proportion of the diol monomer to the total monomer units constituting the polyester resin is preferably 35 mol% or more, particularly preferably 40 mol% or more, and even more preferably 45 mol% or more. Furthermore, this proportion is preferably 65 mol% or less, particularly preferably 60 mol% or less, and even more preferably 55 mol% or less. Within these ranges, the substrate film of this embodiment is likely to have better flexibility.

[0036] From the viewpoint of improving the flexibility of the base film, the polyester resin of this embodiment preferably contains, as a monomer unit constituting the polyester resin, a dimer acid obtained by dimerizing an unsaturated fatty acid. Here, the carbon number of the unsaturated fatty acid is preferably 10 or more, particularly 15 or more. Furthermore, the carbon number is preferably 30 or less, particularly 25 or less. Examples of such dimer acids include a 36-carbon dicarboxylic acid obtained by dimerizing an 18-carbon unsaturated fatty acid such as oleic acid or linoleic acid, and a 44-carbon dicarboxylic acid obtained by dimerizing a 22-carbon unsaturated fatty acid such as erucic acid. Note that when obtaining the dimer acid, a small amount of trimer acid obtained by trimerizing the unsaturated fatty acid may also be produced. The polyester resin of this embodiment may contain such a trimer acid in addition to the dimer acid.

[0037] When the polyester resin of this embodiment contains the above-mentioned dimer acid as a constituent monomer unit, the proportion of the dimer acid relative to the total dicarboxylic acid units constituting the polyester resin is preferably 2 mol% or more, particularly preferably 5 mol% or more, and even more preferably 10 mol% or more. Furthermore, this proportion is preferably 25 mol% or less, particularly preferably 23 mol% or less, and even more preferably 20 mol% or less. Within these ranges, the polyester resin is more likely to have the desired flexibility, and as a result, the substrate film of this embodiment is more likely to have excellent flexibility.

[0038] The polyester resin of this embodiment may contain, as its constituent monomer units, a monomer other than the dicarboxylic acid, diol, and dimer acid described above. Examples of such monomers include aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid; and aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, and 4,4'-diphenyldicarboxylic acid. The polyester resin may also contain a diol component other than a diol having an alicyclic structure. For example, the polyester resin may contain ethylene glycol, propylene glycol, butanediol, hexanediol, octanediol, decanediol; ethylene oxide adducts of bisphenol A, bisphenol S, and the like; trimethylolpropane, and the like.

[0039] However, from the viewpoint of easily realizing superior flexibility, the polyester resin of this embodiment preferably contains more monomers having an alicyclic structure (the above-mentioned dicarboxylic acids having an alicyclic structure or diols having an aliphatic structure) than monomers having an aromatic ring structure. In particular, among the monomer units constituting the polyester resin of this embodiment, the molar ratio of monomer units having an aromatic ring structure to monomer units having an alicyclic structure is preferably less than 1, more preferably 0.5 or less, more preferably 0.2 or less, more preferably 0.1 or less, more preferably 0.05 or less, more preferably 0.03 or less, more preferably 0.01 or less, particularly preferably 0.005 or less, further preferably 0.001 or less, and most preferably 0.

[0040] Furthermore, the polyester resin in this embodiment preferably has a heat of fusion of 2 J / g or more, more preferably 5 J / g or more, particularly preferably 10 J / g or more, and even more preferably 15 J / g or more, as measured by differential scanning calorimetry at a heating rate of 20°C / min. Having a heat of fusion of 2 J / g or more appropriately improves the crystallinity of the substrate film, resulting in better handleability and processability of the substrate film. Furthermore, the heat of fusion is preferably 150 J / g or less, more preferably 100 J / g or less, particularly preferably 70 J / g or less, even more preferably 50 J / g or less, and especially preferably 30 J / g or less. Having a heat of fusion of 150 J / g or less tends to provide the substrate film according to this embodiment with better flexibility. Details of the method for measuring the heat of fusion are as described in the Examples section below.

[0041] The method for producing the polyester resin in this embodiment is not particularly limited, and the polyester resin can be obtained by polymerizing the above-mentioned monomer components using a known catalyst.

[0042] The content of polyester resin in the material constituting the base film according to this embodiment is preferably 55% by mass or more, particularly preferably 60% by mass or more, and even more preferably 65% ​​by mass or more. Furthermore, the content is preferably 96% by mass or less, particularly preferably 94% by mass or less, and even more preferably 92% by mass or less. By ensuring that the content of polyester resin in the material is within the above range, the base film formed using the material is more likely to have good flexibility.

[0043] (2) Elastomer The elastomer in this embodiment is not particularly limited and may be a thermosetting elastomer or a thermoplastic elastomer, but is preferably a thermoplastic elastomer from the viewpoint that the base film in this embodiment is likely to have superior flexibility.

[0044] Examples of the thermoplastic elastomer are not particularly limited, and examples thereof include styrene-based elastomers, acrylic elastomers, urethane-based elastomers, olefin-based elastomers, polyester-based elastomers, and silicone-based elastomers. These may be used alone or in combination of two or more. Among the elastomers described above, from the viewpoint of easily achieving superior flexibility, it is preferable to use at least one of styrene-based elastomers, acrylic elastomers, urethane-based elastomers, and olefin-based elastomers. It is particularly preferable to use at least one of styrene-based elastomers, acrylic elastomers, and urethane-based elastomers, and it is even more preferable to use styrene-based elastomers. Furthermore, from the viewpoint of easily adjusting the physical properties of the substrate film to the desired range, it is preferable to use urethane-based elastomers.

[0045] In this specification, the term "styrene-based elastomer" refers to a copolymer containing structural units derived from styrene or its derivatives (styrene-based compounds), and refers to a material that has rubber-like elasticity and thermoplasticity in a temperature range including room temperature.

[0046] Styrenic elastomers include styrene-conjugated diene copolymers and styrene-olefin copolymers. Specific examples of styrene-conjugated diene copolymers include unhydrogenated styrene-conjugated diene copolymers such as styrene-butadiene copolymer, styrene-butadiene-styrene copolymer (SBS), styrene-butadiene-butylene-styrene copolymer, styrene-isoprene copolymer, styrene-isoprene-styrene copolymer (SIS), and styrene-ethylene-isoprene-styrene copolymer; and hydrogenated styrene-conjugated diene copolymers such as styrene-ethylene / propylene-styrene copolymer (SEPS) and styrene-ethylene / butylene-styrene copolymer (SEBS). These may be used alone or in combination. Among the above-mentioned styrene-based elastomers, styrene-conjugated diene copolymers are preferred due to their ease of achieving better flexibility, with hydrogenated styrene-conjugated diene copolymers being particularly preferred, and styrene-ethylene / butylene-styrene copolymers being even more preferred.

[0047] When a styrene-ethylene / butylene-styrene copolymer is used, the styrene content in the copolymer is preferably 3% by mass or more, particularly preferably 5% by mass or more, and even more preferably 10% by mass. The styrene content is also preferably 60% by mass or less, particularly preferably 50% by mass or less, and even more preferably 40% by mass or less. By using a styrene-ethylene / butylene-styrene copolymer with a styrene content within the above range, the substrate film according to this embodiment is more likely to have excellent flexibility.

[0048] In this specification, the term "acrylic elastomer" refers to a copolymer containing structural units derived from acrylic acid or its derivatives (acrylic compounds), and refers to a material that has rubber-like elasticity and thermoplasticity in a temperature range including room temperature.

[0049] Examples of acrylic elastomers include (meth)acrylic acid-based diblock copolymers and (meth)acrylic acid-based triblock copolymers. These copolymers have a structure in which a relatively hard, pseudo-crosslinkable segment (hard segment) made of polymethyl methacrylate (PMMA) is linked to one or both ends of a relatively soft segment (soft segment) made of polybutyl acrylate (PBA) or poly2-ethylhexyl acrylate (2EHA). Among these, (meth)acrylic acid-based triblock copolymers are preferred from the viewpoint of film strength.

[0050] Examples of the (meth)acrylic acid triblock copolymer include polymethyl methacrylate (PMMA)-polybutyl acrylate (PBA)-polymethyl methacrylate (PMMA), polymethyl methacrylate (PMMA)-poly2-ethylhexyl acrylate-polymethyl methacrylate (PMMA), and the like.

[0051] When a (meth)acrylic acid triblock copolymer having a PMMA segment as described above is used as the acrylic elastomer, the ratio of methyl methacrylate monomers (MMA ratio) to all monomers constituting the copolymer is preferably 10% by weight or more, more preferably 20% by weight or more, and even more preferably 30% by weight or more. Furthermore, the MMA ratio is preferably 80% by weight or less, more preferably 70% by weight or less, and even more preferably 60% by weight or less. By using a (meth)acrylic acid triblock copolymer having an MMA ratio within the above range, the substrate film according to this embodiment is more likely to have excellent flexibility.

[0052] In this specification, the term "urethane-based elastomer" refers to a copolymer containing structural units derived from a urethane compound or its derivative (urethane-based compound), and refers to a material that has rubber-like elasticity and thermoplasticity in a temperature range including room temperature.

[0053] In particular, urethane-based elastomers are generally obtained by reacting a long-chain polyol, a chain extender, and a polyisocyanate, and are composed of soft segments having structural units derived from the long-chain polyol and hard segments having a polyurethane structure obtained by reacting the chain extender with the polyisocyanate.

[0054] Urethane elastomers can be classified according to the type of long-chain polyol used as the soft segment component into polyester polyurethane elastomers, polyether polyurethane elastomers, polycarbonate polyurethane elastomers, and the like.

[0055] Examples of the long-chain polyol include polyester polyols such as lactone-based polyester polyols and adipate-based polyester polyols; polyether polyols such as polypropylene (ethylene) polyols and polytetramethylene ether glycol; and polycarbonate polyols.

[0056] Examples of the polyisocyanate include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, and hexamethylene diisocyanate.

[0057] Examples of the chain extender include low molecular weight polyhydric alcohols such as 1,4-butanediol and 1,6-hexanediol, and aromatic diamines.

[0058] In this specification, the term "olefin-based elastomer" refers to a copolymer containing structural units derived from olefins or their derivatives (olefin-based compounds), and refers to a material that has rubber-like elasticity and thermoplasticity in a temperature range including room temperature.

[0059] Examples of olefin-based elastomers include those containing at least one resin selected from the group consisting of ethylene-α-olefin copolymer, propylene-α-olefin copolymer, butene-α-olefin copolymer, ethylene-propylene-α-olefin copolymer, ethylene-butene-α-olefin copolymer, propylene-butene-α-olefin copolymer, and ethylene-propylene-butene-α-olefin copolymer.

[0060] The elastomer content in the material constituting the substrate film according to this embodiment is preferably 4% by mass or more, particularly preferably 6% by mass or more, and even more preferably 8% by mass or more. When the elastomer content in the material is 4% by mass or more, the substrate film formed using this material is more likely to have good flexibility. Furthermore, the content is preferably 45% by mass or less, particularly preferably 40% by mass or less, and even more preferably 35% by mass or less. When the elastomer content in the material is 45% by mass or less, it becomes easier to form a substrate film using this material and to achieve a better chip suppression effect.

[0061] (3) Other ingredients The material for producing the base film according to the present embodiment may contain components other than the polyester resin and elastomer described above. In particular, the material may contain components used in base films for general workpiece processing sheets.

[0062] Examples of such components include various additives such as flame retardants, plasticizers, lubricants, antioxidants, colorants, infrared absorbers, ultraviolet absorbers, ion scavengers, etc. The content of these additives is not particularly limited, but is preferably set within a range in which the substrate film exhibits the desired functions.

[0063] (4) Structure of the base film The layer structure of the substrate film according to this embodiment may be a single layer or multiple layers, as long as it includes a layer made of a material containing the polyester resin and elastomer described above (hereinafter, sometimes referred to as "resin layer A"). From the viewpoint of reducing production costs, the substrate film according to this embodiment is preferably a single layer (only resin layer A). On the other hand, when the substrate film is multiple layers, multiple resin layers A may be laminated, or resin layer A may be laminated with other layers.

[0064] The surface of the base film on which the pressure-sensitive adhesive layer is to be laminated may be subjected to a surface treatment such as a primer treatment, a corona treatment, or a plasma treatment in order to enhance adhesion to the pressure-sensitive adhesive layer.

[0065] 2. Physical properties of the base film The tensile modulus of the base film in this embodiment, measured when subjected to a tensile test in an environment of 23 ° C. and a tensile speed of 200 mm / min, is preferably 800 MPa or less, particularly preferably 600 MPa or less, and even more preferably 500 MPa or less. When the tensile modulus is 800 MPa or less, the base film according to this embodiment is more likely to have good flexibility. Furthermore, the tensile modulus is preferably 50 MPa or more, more preferably 100 MPa or more, particularly preferably 150 MPa or more, even more preferably 200 MPa or more, even more preferably 250 MPa or more, and most preferably 300 MPa or more. Furthermore, when the tensile modulus is 100 MPa or more, the base film according to this embodiment is more likely to have appropriate strength, and the workpiece processing sheet including this base film has good handleability and is easy to perform the desired workpiece processing.

[0066] The tensile modulus of the base film of this embodiment, measured when subjected to a tensile test at 23°C and a tensile speed of 406 mm / min, is preferably 800 MPa or less, more preferably 600 MPa or less, and even more preferably 500 MPa or less. Having a tensile modulus of 800 MPa or less facilitates the base film of this embodiment to have better flexibility. Furthermore, the tensile modulus is preferably 50 MPa or more, more preferably 100 MPa or more, particularly preferably 150 MPa or more, even more preferably 200 MPa or more, even more preferably 250 MPa or more, and most preferably 300 MPa or more. Having a tensile modulus of 50 MPa or more facilitates the base film of this embodiment to have adequate strength, and the workpiece processing sheet including this base film has good handleability and facilitates the desired workpiece processing. In this specification, a tensile speed of 406 mm / min represents the strain rate of the workpiece processing sheet under normal expanding conditions converted into a tensile speed.

[0067] The stress at break of the base film of this embodiment, measured when subjected to a tensile test at 23°C and a tensile speed of 200 mm / min, is preferably 60 MPa or less, particularly preferably 50 MPa or less, and even more preferably 40 MPa or less. Having a stress at break of 60 MPa or less allows the base film of this embodiment to have better processability. Furthermore, the stress at break is preferably 5 MPa or more, more preferably 10 MPa or more, particularly preferably 15 MPa or more, even more preferably 20 MPa or more, and most preferably 25 MPa or more. Having a stress at break of 15 MPa or more allows the base film of this embodiment to have appropriate strength, and a workpiece processing sheet including this base film has good handleability and facilitates the desired workpiece processing. Furthermore, having a stress at break of 15 MPa or more allows the base film of this embodiment to have good expandability.

[0068] The stress at break of the base film of this embodiment, measured when subjected to a tensile test at 23°C and a tensile speed of 406 mm / min, is preferably 60 MPa or less, particularly preferably 50 MPa or less, and even more preferably 40 MPa or less. Having a stress at break of 60 MPa or less allows the base film of this embodiment to have better processability. Furthermore, the stress at break is preferably 5 MPa or more, particularly preferably 10 MPa or more, more preferably 15 MPa or more, preferably 20 MPa or more, and even more preferably 25 MPa or more. Having a stress at break of 5 MPa or more allows the base film of this embodiment to have appropriate strength, and a workpiece processing sheet including this base film has good handleability and facilitates good workpiece processing. Furthermore, having a stress at break of 5 MPa or more allows the base film of this embodiment to have good expandability.

[0069] The breaking elongation of the base film in this embodiment, measured when subjected to a tensile test in an environment of 23 ° C. and a tensile speed of 200 mm / min, is preferably 150% or more, more preferably 200% or more, particularly preferably 250% or more, even more preferably 300% or more, and most preferably 350% or more. When the breaking elongation is 200% or more, the base film in this embodiment is likely to have the desired extensibility, and a workpiece processing sheet including the base film is likely to achieve excellent expandability and pick-up properties. Furthermore, the breaking elongation is preferably 800% or less, more preferably 700% or less, particularly preferably 600% or less, and even more preferably 500% or less. When the breaking elongation is 800% or less, the processability of the base film is improved, making it easier to produce the desired workpiece processing sheet.

[0070] The breaking elongation of the base film in this embodiment, measured when subjected to a tensile test in an environment of 23°C and a tensile speed of 406 mm / min, is preferably 150% or more, particularly preferably 200% or more, even more preferably 250% or more, preferably 300% or more, and preferably 350% or more. When the breaking elongation is 150% or more, the base film in this embodiment is likely to have the desired extensibility, and a workpiece processing sheet including this base film is likely to achieve excellent expandability and pick-up properties. Furthermore, the breaking elongation is preferably 800% or less, particularly preferably 700% or less, and even more preferably 600% or less, and preferably 500% or less. When the breaking elongation is 800% or less, the processability of the base film is improved, making it easier to produce the desired workpiece processing sheet.

[0071] The details of the methods for measuring the tensile modulus, stress at break, and elongation at break are as described in the test examples below.

[0072] The thickness of the base film according to this embodiment is preferably 20 μm or more, particularly preferably 40 μm or more, and even more preferably 60 μm or more. Furthermore, the thickness of the base film is preferably 600 μm or less, particularly preferably 300 μm or less, and even more preferably 200 μm or less. When the thickness of the base film is 20 μm or more, the workpiece processing sheet provided with the base film tends to have appropriate strength, and the workpiece fixed on the workpiece processing sheet tends to be well supported. As a result, it becomes possible to effectively suppress the occurrence of chipping during dicing. Furthermore, when the thickness of the base film is 600 μm or less, the above-mentioned breaking elongation is easily achieved. Furthermore, when the thickness of the base film is 600 μm or less, the base film has better processability.

[0073] 3. Manufacturing method of base film The method for producing the substrate film according to this embodiment is not particularly limited as long as a material containing the polyester resin and elastomer described above is used, and examples thereof include melt extrusion methods such as the T-die method and the round die method; calendaring methods; and solution methods such as the dry method and the wet method. Among these, it is preferable to employ the melt extrusion method or the calendaring method from the viewpoint of efficiently producing the substrate.

[0074] When a single-layer substrate film is produced by melt extrusion, the material for the substrate film (the material containing the polyester resin and elastomer described above) is kneaded, and the resulting kneaded mixture is directly or firstly formed into pellets, which are then extruded into a film using a known extruder.

[0075] Furthermore, when a substrate film consisting of multiple layers is produced by melt extrusion, the components constituting each layer are kneaded separately, and the multiple layers are simultaneously extruded from the resulting kneaded mixture, either directly or after pellets have been produced, using a known extruder to form a film.

[0076] [Work processing sheet] The workpiece processing sheet according to this embodiment includes the above-described base film and an adhesive layer laminated on one side of the base film.

[0077] 1. Composition of workpiece processing sheet Hereinafter, the components constituting the workpiece processing sheet according to this embodiment, other than the base film, will be described.

[0078] (1) Adhesive layer The adhesive constituting the adhesive layer is not particularly limited as long as it can exert sufficient adhesive strength to the adherend (particularly, adhesive strength to the workpiece sufficient for processing the workpiece). Examples of adhesives constituting the adhesive layer include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, polyvinyl ether adhesives, etc. Among these, it is preferable to use acrylic adhesives because they can easily exert the desired adhesive strength.

[0079] The adhesive constituting the adhesive layer in this embodiment may be an adhesive that does not have active energy ray curability, but is preferably an adhesive that has active energy ray curability (hereinafter, sometimes referred to as an "active energy ray curable adhesive"). When the adhesive layer is composed of an active energy ray curable adhesive, the adhesive layer can be cured by irradiation with active energy rays, making it possible to easily reduce the adhesive strength of the workpiece processing sheet to the adherend. In particular, irradiation with active energy rays makes it possible to easily separate the processed workpiece from the adhesive sheet.

[0080] The active energy ray-curable adhesive constituting the adhesive layer may be one whose main component is a polymer having active energy ray curability, or one whose main component is a mixture of a non-active energy ray-curable polymer (a polymer not having active energy ray curability) and a monomer and / or oligomer having at least one active energy ray-curable group.

[0081] The active energy ray-curable polymer is preferably a (meth)acrylic acid ester polymer (hereinafter sometimes referred to as "active energy ray-curable polymer") having an active energy ray-curable functional group (active energy ray-curable group) introduced into its side chain. This active energy ray-curable polymer is preferably one obtained by reacting an acrylic copolymer having a functional group-containing monomer unit with an unsaturated group-containing compound having a functional group bonded to the functional group. In this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. Furthermore, the term "polymer" also includes the concept of "copolymer."

[0082] The weight-average molecular weight of the active energy radiation-curable polymer is preferably 10,000 or more, particularly preferably 150,000 or more, and even more preferably 200,000 or more. The weight-average molecular weight is preferably 2,500,000 or less, particularly preferably 2,000,000 or less, and even more preferably 1,500,000 or less. The weight-average molecular weight (Mw) in this specification is a value measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

[0083] On the other hand, when the active energy ray-curable adhesive is mainly composed of a mixture of an active energy ray non-curable polymer component and a monomer and / or oligomer having at least one active energy ray-curable group, the active energy ray non-curable polymer component can be, for example, the above-mentioned acrylic copolymer before being reacted with an unsaturated group-containing compound.Furthermore, the active energy ray-curable monomer and / or oligomer can be, for example, an ester of a polyhydric alcohol and (meth)acrylic acid.

[0084] The weight-average molecular weight of the acrylic polymer as the non-active energy ray-curable polymer component is preferably 10,000 or more, particularly preferably 150,000 or more, and even more preferably 200,000 or more, and is preferably 2,500,000 or less, particularly preferably 2,000,000 or more, and even more preferably 1,500,000 or less.

[0085] When ultraviolet rays are used as the active energy rays for curing the active energy ray-curable adhesive, it is preferable to add a photopolymerization initiator to the adhesive. In addition, the adhesive may also contain an active energy ray-non-curable polymer component or oligomer component, a crosslinking agent, etc.

[0086] The thickness of the adhesive layer in this embodiment is preferably 1 μm or more, particularly preferably 2 μm or more, and even more preferably 3 μm or more. The thickness of the adhesive layer is also preferably 50 μm or less, particularly preferably 40 μm or less, and even more preferably 30 μm or less. Having an adhesive layer thickness of 1 μm or more makes it easier for the workpiece processing sheet according to this embodiment to exhibit the desired adhesiveness. Having an adhesive layer thickness of 50 μm or less also makes it easier for the adherend to be separated from the adhesive layer after curing.

[0087] (2) Release sheet In the workpiece processing sheet according to this embodiment, a release sheet may be laminated on the side of the adhesive layer opposite the base film (hereinafter sometimes referred to as the "adhesive side") in order to protect that side until it is attached to the adherend.

[0088] The release sheet may have any configuration, and may be, for example, 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 such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; and polyolefin films such as polypropylene and polyethylene. Silicone-based, fluorine-based, and long-chain alkyl-based release agents can be used, and among these, silicone-based release agents are preferred because they are inexpensive and provide stable performance.

[0089] There are no particular limitations on the thickness of the release sheet, and it may be, for example, 20 μm or more and 250 μm or less.

[0090] (3) Other In the workpiece processing sheet according to this embodiment, an adhesive layer may be laminated on the surface of the adhesive layer opposite the base film. In this case, the workpiece processing sheet according to this embodiment can be used as a dicing / die bonding sheet. In this sheet, a workpiece is attached to the surface of the adhesive layer opposite the adhesive layer, and the adhesive layer is diced together with the workpiece to obtain a chip on which the individualized adhesive layer is laminated. The individualized adhesive layer allows the chip to be easily fixed to the object on which it is to be mounted. As a material for constituting the adhesive layer, it is preferable to use a material containing a thermoplastic resin and a low-molecular-weight thermosetting adhesive component, or a material containing a B-stage (semi-cured) thermosetting adhesive component.

[0091] Furthermore, in the workpiece processing sheet according to this embodiment, a protective film forming layer may be laminated on the adhesive surface of the adhesive layer. In this case, the workpiece processing sheet according to this embodiment can be used as a sheet for both protective film formation and dicing. With such a sheet, a workpiece is attached to the surface of the protective film forming layer opposite the adhesive layer, and the protective film forming layer is diced together with the workpiece to obtain a chip on which a singulated protective film forming layer is laminated. It is preferable that the workpiece has a circuit formed on one side. In this case, the protective film forming layer is typically laminated on the surface opposite the surface on which the circuit is formed. By curing the singulated protective film forming layer at a predetermined timing, a protective film with sufficient durability can be formed on the chip. The protective film forming layer is preferably made of an uncured curable adhesive.

[0092] 2. Manufacturing method of workpiece processing sheet The method for producing the workpiece processing sheet according to the present embodiment is not particularly limited. For example, it is preferable to obtain the workpiece processing sheet by forming an adhesive layer on a release sheet, and then laminating one side of a base film on the surface of the adhesive layer opposite the release sheet.

[0093] The pressure-sensitive adhesive layer can be formed by a known method. For example, a coating liquid containing a pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer and, if desired, a solvent or dispersion medium is prepared. The coating liquid is then applied to the release surface of a release sheet (hereinafter sometimes referred to as the "release surface"). The resulting coating film is then dried to form the pressure-sensitive adhesive layer.

[0094] The coating of the coating liquid described above can be carried out by a known method, such as bar coating, knife coating, roll coating, blade coating, die coating, gravure coating, etc. The properties of the coating liquid are not particularly limited as long as it can be applied, and the coating liquid may contain components for forming the pressure-sensitive adhesive layer as a solute or as a dispersoid. The release sheet may be peeled off as a processing material, or may protect the pressure-sensitive adhesive layer until it is attached to the adherend.

[0095] When the adhesive composition for forming the adhesive layer contains the above-mentioned crosslinking agent, it is preferable to change the above-mentioned drying conditions (temperature, time, etc.) or to separately perform a heat treatment to promote the crosslinking reaction between the polymer component in the coating film and the crosslinking agent, thereby forming a crosslinked structure with a desired density in the adhesive layer. Furthermore, in order to promote the above-mentioned crosslinking reaction sufficiently, after laminating the adhesive layer and the substrate, curing may be performed, for example, by leaving them to stand in an environment of 23°C and a relative humidity of 50% for several days.

[0096] 3. How to use the workpiece processing sheet The workpiece processing sheet according to this embodiment can be used for processing workpieces such as semiconductor wafers. In this case, the adhesive surface of the workpiece processing sheet according to this embodiment can be attached to the workpiece, and then the workpiece can be processed on the workpiece processing sheet. Depending on the processing, the workpiece processing sheet according to this embodiment can be used as a workpiece processing sheet such as a backgrinding sheet, dicing sheet, expanding sheet, or pickup sheet. Examples of workpieces include semiconductor components such as semiconductor wafers and semiconductor packages, and glass components such as glass plates.

[0097] As described above, the workpiece processing sheet according to this embodiment has a base film with good flexibility, which allows for good expansion, and therefore the workpiece processing sheet according to this embodiment is particularly suitable for use as a dicing sheet, an expanding sheet, or a pick-up sheet.

[0098] When the workpiece processing sheet according to this embodiment has the adhesive layer described above, the workpiece processing sheet can be used as a dicing / die bonding sheet. Furthermore, when the workpiece processing sheet according to this embodiment has the protective film forming layer described above, the workpiece processing sheet can be used as a protective film forming / dicing sheet.

[0099] Furthermore, when the adhesive layer of the workpiece processing sheet according to this embodiment is composed of the aforementioned active energy ray-curable adhesive, it is also preferable to irradiate the adhesive layer with active energy rays as follows during use. That is, when processing of a workpiece on the workpiece processing sheet is completed and the processed workpiece is to be separated from the workpiece processing sheet, it is preferable to irradiate the adhesive layer with active energy rays before the separation. This hardens the adhesive layer, effectively reducing the adhesive strength of the workpiece processing sheet to the processed workpiece, making it easier to separate the processed workpiece.

[0100] The above-described embodiments have been described to facilitate understanding of the present invention, and are not intended to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention. [Example]

[0101] The present invention will be explained in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0102] Example 1 (1) Preparation of the base film A reactor equipped with a stirrer, distillation tube, and pressure regulator was charged with 12.90 kg of dimethyl 1,4-cyclohexanedicarboxylate (trans isomer ratio 98%), 11.47 kg of 1,4-cyclohexanedimethanol, 0.3 kg of ethylene glycol, and 0.11 kg of an ethylene glycol solution containing 10% manganese acetate tetrahydrate. The mixture was heated to 200°C under a nitrogen flow and then increased to 230°C over 1 hour. After maintaining the temperature for 2 hours to allow for transesterification, 10.30 kg of erucic acid-derived dimer acid (44 carbon atoms, Croda, product name "PRIPOL 1004") and 0.11 kg of an ethylene glycol solution containing 10% trimethyl phosphate were added to the system, and the esterification reaction was continued at 230°C for 1 hour. Next, 300 ppm of germanium dioxide was added as a polycondensation catalyst and stirred, after which the pressure was reduced to 133 Pa or less over 1 hour, during which time the internal temperature was raised from 230°C to 270°C, and the polycondensation reaction was carried out by stirring until a predetermined viscosity was reached under a high vacuum of 133 Pa or less. The resulting polymer was extruded into water in the form of a strand, cut, and pelletized.

[0103] The polyester resin pellets thus obtained were dried at 85°C for at least 4 hours. Subsequently, 70 parts by mass of the dried pellets were mixed with 30 parts by mass of a styrene-ethylene / butylene-styrene copolymer (SEBS) (styrene:ethylene / butylene ratio = 20:80, melt flow rate (MFR) = 13.0 g / 10 min (measured in accordance with ISO 1133 at 230°C under a load of 2.16 kg)) as a styrene-based elastomer in a twin-screw mixer. The resulting pellets were placed in the hopper of a single-screw extruder equipped with a T-die. The melt-mixed pellets were then extruded through the T-die at a cylinder temperature of 220°C and a die temperature of 220°C and cooled on a cooling roll to obtain an 80 μm-thick sheet-like substrate film.

[0104] The polyester resin contained approximately 50 mol% of 1,4-cyclohexanedimethanol, approximately 40.5 mol% of dimethyl 1,4-cyclohexanedicarboxylate, and 9.5 mol% of a dimer acid derived from erucic acid as its constituent monomers. The proportion of the dimer acid to the total dicarboxylic acid units constituting the polyester resin was 19.1 mol%. The heat of fusion of the polyester resin was measured by the method described below and was found to be 20 J / g.

[0105] (2) Preparation of adhesive composition 95 parts by mass of n-butyl acrylate and 5 parts by mass of acrylic acid were polymerized by solution polymerization to obtain a (meth)acrylic acid ester polymer. The weight average molecular weight (Mw) of this acrylic polymer was measured by the method described below and was found to be 500,000.

[0106] 100 parts by mass (solid content equivalent, same below) of the (meth)acrylic acid ester polymer obtained as described above, 120 parts by mass of a urethane acrylate oligomer (Mw: 8,000), 5 parts by mass of an isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, product name "Coronate L"), and 4 parts by mass of a photopolymerization initiator (manufactured by IGM Resins BV, product name "Omnirad184") were mixed to obtain an energy ray-curable adhesive composition.

[0107] (3) Formation of adhesive layer The adhesive composition obtained in step (2) above was applied to the release-treated surface of a release sheet (manufactured by Lintec Corporation, product name "SP-PET381031"), one side of which was a 38 μm-thick polyethylene terephthalate film release-treated with a silicone-based release agent, and the resulting coating was dried for 1 minute at 100° C. This resulted in a laminate in which a 10 μm-thick adhesive layer was formed on the release surface of the release sheet.

[0108] (4) Preparation of workpiece processing sheet One side of the base film obtained in the above step (1) was bonded to the adhesive layer side of the laminate obtained in the above step (3) to obtain a workpiece processing sheet.

[0109] Here, the heat of fusion of the polyester resin described above was measured using a differential scanning calorimeter (DSC, manufactured by TA Instruments, product name "DSC Q2000") in accordance with JIS K 7121:2012.

[0110] Specifically, the sample was first heated from room temperature to 250°C at a heating rate of 20°C / min, held at 250°C for 10 minutes, cooled to -60°C at a heating rate of 20°C / min, and held at -60°C for 10 minutes. After that, the sample was again heated to 250°C at a heating rate of 20°C / min to obtain a DSC curve, and the melting point was measured.

[0111] The weight average molecular weight (Mw) is a weight average molecular weight measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement) and converted into standard polystyrene. <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℃

[0112] Example 2 In the process of producing the base film, the ratio of the mass parts of the dried polyester resin pellets to the SEBS was changed to 80:20, except that the base film was produced in the same manner as in Example 1, and a work processing sheet was obtained using the base film in the same manner as in Example 1.

[0113] Example 3 In the process of producing the base film, the ratio of the mass parts of the dried polyester resin pellets to the SEBS was changed to 90:10. The base film was produced in the same manner as in Example 1, and a work processing sheet was obtained using the base film in the same manner as in Example 1.

[0114] Example 4 Dried polyester resin pellets were obtained in the same manner as in step (1) of Example 1. 80 parts by mass of the pellets and 20 parts by mass of a polymethacrylic acid (PMMA)-polybutyl acrylate (PBA)-polymethacrylic acid (PMMA) triblock copolymer (pellet-like, MMA ratio = 50 wt %, melt flow rate (MFR) = 31.0 g / 10 min (measured at 230 °C and a load of 2.16 kg according to ISO 1133)) as an acrylic elastomer were kneaded in a twin-screw kneader. The pellets thus obtained were placed in the hopper of a single-screw extruder equipped with a T-die. The pellets were then extruded from the T-die in a melt-kneaded state under conditions of a cylinder temperature of 220 °C and a die temperature of 220 °C, and cooled on a cooling roll to obtain a sheet-like substrate film with a thickness of 80 μm. A workpiece processing sheet was obtained in the same manner as in Example 1, except for using the substrate film.

[0115] Example 5 Dried polyester resin pellets were obtained in the same manner as in step (1) of Example 1. 80 parts by mass of the pellets and 20 parts by mass of a thermoplastic polyurethane elastomer (manufactured by BASF Japan Ltd., product name "Elastollan ET164D") as a urethane-based elastomer were kneaded in a twin-screw kneader. The pellets thus obtained were fed into the hopper of a single-screw extruder equipped with a T-die. The pellets were then extruded from the T-die in a melt-kneaded state under conditions of a cylinder temperature of 220°C and a die temperature of 220°C, and cooled with a cooling roll to obtain a sheet-like substrate film with a thickness of 80 μm. A workpiece processing sheet was obtained in the same manner as in Example 1, except that the substrate film was used.

[0116] Comparative Example 1 In the process of producing the base film, the base film was produced without using SEBS (the dried polyester resin pellets alone were fed into the hopper of a single-screw extruder equipped with a T-die to produce the base film), except that the base film was produced in the same manner as in Example 1, and a work processing sheet was obtained using the base film in the same manner as in Example 1.

[0117] [Test Example 1] (Measurement of tensile properties of base film) The substrate films prepared in the examples and comparative examples were cut into 15 mm × 150 mm test pieces. The 150 mm side was parallel to the MD direction (the flow direction during the production of the substrate film) of the substrate film, and the 15 mm side was parallel to the TD direction (the direction perpendicular to the MD direction) of the substrate film. The tensile modulus, elongation at break, and stress at break of the test pieces were measured in accordance with JIS K7127:1999.

[0118] Specifically, the test piece was placed in a tensile testing machine (Shimadzu Corporation, product name "Autograph AG-Xplus 100N") with a chuck distance of 100 mm, and then subjected to a tensile test in which the test piece was pulled in the MD direction of the substrate film at a speed of 200 mm / min in an environment of 23°C, and the tensile modulus (MPa), elongation at break (%), and stress at break (MPa) were measured. These results for a pulling speed of 200 mm / min are shown in Table 1.

[0119] The tensile test was carried out in the same manner as above, except that the tensile speed was changed to 406 mm / min, and the tensile modulus (MPa), elongation at break (%), and stress at break (MPa) were measured. The results for the tensile speed of 406 mm / min are shown in Table 1.

[0120] [Test Example 2] (Evaluation of expandability) The release sheet was peeled off from the workpiece processing sheet produced in the examples and comparative examples, and the exposed surface of the adhesive layer was attached to one side of a 40 μm thick silicon wafer. A dicing ring frame was then 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). Next, the silicon wafer was diced using a dicing saw (manufactured by Disco Corporation, product name "DFD6362") under the following conditions. Workpiece (substrate): Silicon wafer Work size: 6 inch diameter, 40μm thickness Dicing blade: DISCO Corporation, product name "27HECC", diamond blade Blade rotation speed: 50,000 rpm Dicing speed: 100mm / sec Cutting depth: Cut to a depth of 20 μm from the surface of the base film Dicing size: 8mm x 8mm

[0121] The workpiece processing sheet with the diced chips and ring frame attached was then placed in an expanding device (manufactured by JCM, product name "ME-300B"), and the ring frame was pulled down at a speed of 2 mm / sec until the pulling-down distance reached 40 mm.

[0122] The amount of pull-down (mm) at which breakage occurred was recorded. The results are shown in Table 1 as the limiting amount of pull-down. Note that if no breakage occurred even when the amount of pull-down reached 40 mm, it is indicated as "40 or more."

[0123] [Table 1]

[0124] As is clear from Table 1, the workpiece processing sheets produced in the examples exhibited excellent expandability. [Industrial Applicability]

[0125] The base film of the present invention can be suitably used as a base film constituting a workpiece processing sheet used in processing workpieces such as semiconductor wafers.

Claims

1. A substrate film, a pressure-sensitive adhesive layer laminated on one side of the base film; A workpiece processing sheet comprising: The base film is The material contains a polyester resin having an alicyclic structure and an elastomer other than the polyester resin, the elastomer is a styrene-ethylene / butylene-styrene copolymer (SEBS); The workpiece processing sheet is a back grinding sheet, a dicing sheet, an expanding sheet, or a pick-up sheet. A workpiece processing sheet characterized by:

2. 2. The workpiece processing sheet according to claim 1, wherein the content of the elastomer in the material is 4% by mass or more and 45% by mass or less.

3. 3. The workpiece processing sheet according to claim 1, wherein the polyester resin contains the dicarboxylic acid having the alicyclic structure as a monomer unit constituting the polyester resin.

4. The workpiece processing sheet according to any one of claims 1 to 3, characterized in that the polyester resin contains a diol having an alicyclic structure as a monomer unit constituting the polyester resin.

5. The workpiece processing sheet according to any one of claims 1 to 4, characterized in that the alicyclic structure has 6 or more and 14 or less carbon atoms constituting the ring.

6. the polyester resin contains, as a monomer unit constituting the polyester resin, a dimer acid obtained by dimerizing an unsaturated fatty acid; The number of carbon atoms of the unsaturated fatty acid is 10 or more and 30 or less. The workpiece processing sheet according to any one of claims 1 to 5.

7. The workpiece processing sheet according to any one of claims 1 to 6, characterized in that the tensile modulus measured when a tensile test is performed on the base film in an environment of 23 ° C. and at a tensile speed of 200 mm / min is 50 MPa or more and 800 MPa or less.

8. The workpiece processing sheet according to any one of claims 1 to 7, characterized in that the base film has a breaking elongation measured when subjected to a tensile test in an environment of 23 ° C. and at a tensile speed of 200 mm / min, of 150% or more and 800% or less.

9. The workpiece processing sheet according to any one of claims 1 to 8, characterized in that the thickness of the base film is 20 µm or more and 600 µm or less.

Images