Substrate film and workpiece processing sheet

Abstract

This invention provides a substrate film composed of a polyester resin-containing material. The results of a tensile test performed on the substrate film at a tensile speed of 406 mm / min at 23°C are plotted on a coordinate plane with tensile elongation (%) as the horizontal axis and tensile stress (MPa) as the vertical axis. For the plotted curve, there are no points that are maximum values, or there are at least one maximum value and one minimum value. Furthermore, the absolute value of the difference between the tensile stress at the point with the minimum tensile elongation (among the points with maximum values) and the tensile stress at the point with the minimum tensile elongation (among the points with minimum values) is less than 2.0 MPa. This substrate film possesses excellent flexibility, enabling good expansion. Based on this substrate film, workpiece processing sheets that can be well expanded can be obtained.

Description

Technical Field

[0001] This invention relates to a substrate film and a workpiece processing sheet, wherein the substrate film is suitable for use as a substrate film for workpiece processing sheets used for processing workpieces such as semiconductor wafers. Background Technology

[0002] Semiconductor wafers such as silicon and gallium arsenide, or various packages, are manufactured in large diameters. After being cut into chips and peeled off, they are transferred to the mounting process, which is the next step. At this time, semiconductor wafers and other workpieces are attached to an adhesive sheet (hereinafter sometimes referred to as a "workpiece processing sheet") with a substrate and an adhesive layer, and then undergo back-side grinding, cutting, cleaning, drying, expansion, picking, and mounting.

[0003] In the aforementioned pick-up process, to facilitate the picking up of semiconductor chips, sometimes the semiconductor chips are picked up one by one from the side of the workpiece wafer opposite to the side where the semiconductor chips are stacked. In particular, to suppress collisions between semiconductor chips during picking and to facilitate picking, the workpiece wafer is usually stretched (expanded) to separate the semiconductor chips from each other. Therefore, the workpiece wafer is required to have excellent flexibility that enables good expansion.

[0004] Patent documents 1 and 2 disclose an invention concerning a workpiece processing sheet developed for the purpose of achieving good expansion. In particular, cited document 1 discloses a cutting film having a substrate layer and an adhesive layer, the substrate layer comprising a specified atactic polypropylene and a specified olefin elastomer under specified conditions. Furthermore, cited document 2 discloses an adhesive tape formed by sequentially layering an adhesive layer, an adhesive coating layer, a thermoplastic elastomer layer, and a resin layer, wherein the thermoplastic elastomer layer is composed of a specified resin composition.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent No. 5494132

[0008] Patent Document 2: Japanese Patent Application Publication No. 11-199840 Summary of the Invention

[0009] The technical problem to be solved by the present invention

[0010] The inventors of this invention investigated a substrate film made primarily of a specified polyester resin, used as a substrate film for workpiece processing. The inventors confirmed that this workpiece processing sheet possesses various excellent effects, primarily suppressing the generation of cutting fragments during cutting. Furthermore, the inventors discovered that the usefulness of the substrate film can be further improved by enhancing its expandability.

[0011] The present invention was made in view of the above-mentioned actual situation, and its object is to provide a substrate film with excellent flexibility that enables good expansion, and a workpiece processing sheet that can be well expanded.

[0012] Technical means to solve technical problems

[0013] To achieve the above objectives, firstly, the present invention provides a substrate film, characterized in that it is composed of a material containing polyester resin, and the results of a tensile test performed on the substrate film at a tensile speed of 406 mm / min at 23°C are plotted on a coordinate plane with tensile elongation (unit: %) as the horizontal axis and tensile stress (unit: MPa) as the vertical axis. For the plotted curve, there are no points that become maximum values, or there are at least one point that becomes a maximum value and one point that becomes a minimum value, and the absolute value of the difference between the tensile stress at the point with the minimum tensile elongation among the points that become maximum values ​​and the tensile stress at the point with the minimum tensile elongation among the points that become minimum values ​​is 2.0 MPa or less (Invention 1).

[0014] The substrate film of the above-mentioned invention (Invention 1) has excellent flexibility because it is made of a material containing polyester resin and the curve obtained based on the above-mentioned tensile test meets the above conditions. The workpiece processing sheet using the substrate film can be well expanded.

[0015] In the above invention (Invention 1), it is preferable that the tensile modulus measured when the substrate film is subjected to a tensile test at a tensile speed of 406 mm / min in an environment of 23°C is 50 MPa or more and 800 MPa or less (Invention 2).

[0016] In the above inventions (Inventions 1 and 2), it is preferred that the tensile modulus measured when the substrate film is subjected to a tensile test at a tensile speed of 200 mm / min in an environment of 23°C is 50 MPa or more and 800 MPa or less (Invention 3).

[0017] In the above inventions (Inventions 1 to 3), it is preferable that the elongation at break measured when the substrate film is subjected to a tensile test at a tensile speed of 406 mm / min in an environment of 23°C is 150% or more and 800% or less (Invention 4).

[0018] In the above inventions (Inventions 1 to 4), it is preferable that the elongation at break measured when the substrate film is subjected to a tensile test at a tensile speed of 200 mm / min in an environment of 23°C is 150% or more and 800% or less (Invention 5).

[0019] In the above inventions (Inventions 1 to 5), it is preferred that the content of the polyester resin in the material is 55% by mass or more and 96% by mass or less (Invention 6).

[0020] In the above inventions (Inventions 1 to 6), it is preferred that the polyester resin has an alicyclic structure (Invention 7).

[0021] In the above invention (Invention 7), it is preferable that the polyester resin contains a dicarboxylic acid having the alicyclic structure as a monomer unit constituting the polyester resin (Invention 8).

[0022] In the above inventions (Inventions 7 and 8), it is preferable that the polyester resin contains a diol having the alicyclic structure as a monomer unit constituting the polyester resin (Invention 9).

[0023] In the above inventions (Inventions 7 to 9), it is preferred that the number of carbon atoms in the constituent ring of the alicyclic structure is 6 or more and 14 or less (Invention 10).

[0024] In the above inventions (Inventions 1 to 10), it is preferable that the polyester resin contains a dimer acid obtained by dimerizing an unsaturated fatty acid as a monomer unit constituting the polyester resin, wherein the unsaturated fatty acid has 10 or more and 30 or less carbon atoms (Invention 11).

[0025] In the above inventions (Inventions 1 to 11), it is preferred that the thickness of the substrate film is 20 μm or more and 600 μm or less (Invention 12).

[0026] In the above-described inventions (Inventions 1-12), it is preferable that the substrate film is used as a substrate film constituting a workpiece processing sheet (Invention 13).

[0027] Second, the present invention provides a workpiece processing sheet, characterized in that it comprises the substrate film (Invention 1-13) and an adhesive layer (Invention 14) laminated on one side of the substrate film.

[0028] Invention Effects

[0029] The substrate film of the present invention has excellent flexibility that enables good expansion. Furthermore, the workpiece processing sheet of the present invention can be well expanded. Attached Figure Description

[0030] Figure 1Curves illustrating the physical properties of the substrate film in this embodiment. Detailed Implementation

[0031] The following describes the embodiments of the present invention.

[0032] [Substrate Film]

[0033] The substrate film of this embodiment is composed of a material containing polyester resin. Furthermore, for the substrate film of this embodiment, the results of a tensile test conducted at a tensile speed of 406 mm / min at 23°C are plotted on a coordinate plane with tensile elongation (in %) as the horizontal axis and tensile stress (in MPa) as the vertical axis. For the obtained curve, either of the following two conditions must be met.

[0034] (Condition 1) There are no points in the curve that become local maxima (hereinafter, sometimes referred to as "local points").

[0035] (Condition 2) There is at least one point that becomes a maximum and one point that becomes a minimum (hereinafter, sometimes referred to as the "minimum point") in the curve, and the absolute value of the difference between the tensile stress at the point where the elongation of the tensile is the minimum among the points that become a maximum and the tensile stress at the point where the elongation of the tensile is the minimum among the points that become a minimum is less than 2.0 MPa.

[0036] Regarding conditions 1 and 2 above, use Figure 1 To provide a more specific explanation. Figure 1 The diagram illustrates the existence of curves C1 and C2 in a coordinate plane with tensile elongation (in %) as the horizontal axis and tensile stress (in MPa) as the vertical axis. First, curve C1 is an example of the case satisfying condition 1 above. In curve C1, as the tensile elongation increases from 0%, the tensile stress also increases accordingly (however, as the value gradually approaches the specified tensile stress, it becomes less likely to increase). Therefore, there is no point in curve C1 where the tensile stress changes from increasing to decreasing; that is, there is no maximum point.

[0037] On the other hand, curve C2 is an example of the case satisfying condition 2. In curve C2, when the elongation of tension increases from 0%, the tensile stress first increases to point A. Then, with point A as the boundary, the tensile stress begins to decrease. That is, curve C2 has a maximum point at point A. When the elongation of tension exceeds point A and increases further, then with point B as the boundary, the tensile stress changes from decreasing to increasing, and then continues to increase. That is, curve C2 has a minimum point at point B. Here, due to the absolute value of the difference between the tensile stress values ​​at points A and B ( Figure 1 In the middle, the value represented by "Δ" is below 2.0 MPa, and curve C2 satisfies condition 2.

[0038] In addition, Figure 1 In curve C2, there exists one maximum point and one minimum point. However, even when there are multiple maximum and minimum points, condition 2 is sometimes satisfied. In this case, from the multiple maximum and minimum points, select the maximum point with the smallest tensile elongation and the minimum point with the smallest tensile elongation, and determine whether condition 2 is satisfied based on whether the absolute value of the difference between the two is below 2.0 MPa.

[0039] The substrate film of this embodiment, being composed of a material containing polyester resin and satisfying either condition 1 or condition 2 above, possesses excellent flexibility. Therefore, when the substrate film of this embodiment is used as a substrate film for a semiconductor processing wafer, the semiconductor processing wafer can expand well. Consequently, in subsequent pick-up processes, it is easy to perform top-up from the back of the chip, and good pick-up is also possible.

[0040] However, if neither condition 1 nor condition 2 is satisfied, for example, if a maximum point exists but the difference (Δ) in the absolute value is greater than 2.0 MPa, the flexibility of the substrate film becomes insufficient, and the scalability of the semiconductor wafer made using the substrate film also becomes insufficient. Therefore, from the perspective of obtaining higher flexibility, the difference (Δ) in the absolute value is preferably 1.8 MPa or less, more preferably 1.6 MPa or less, particularly preferably 1.5 MPa or less, further preferably 1.3 MPa or less, and most preferably 1.0 MPa or less. On the other hand, there is no particular limitation on the lower limit of the difference (Δ) in the absolute value; for example, it can be greater than 0.

[0041] Furthermore, generally speaking, when the tensile elongation of the substrate film is increased from 0%, even if the tensile stress initially reaches a maximum, the tensile stress will eventually continue to increase until the substrate film breaks. Therefore, a curve that has a maximum value but no minimum value (i.e., a curve where the tensile stress continuously decreases after the maximum value) is usually not produced. In addition, the details of the determination method for whether conditions 1 and 2 above are met are described in the test examples below.

[0042] Although the substrate film of this embodiment can be used for various purposes, it is particularly suitable as a substrate for workpiece processing wafers used in processing workpieces such as semiconductor wafers, and especially suitable as a substrate for cutting wafers used in cutting workpieces, due to the aforementioned effects.

[0043] Furthermore, since the substrate film of this embodiment is made of a material containing polyester resin, the generation of cutting chips can be effectively suppressed when the workpiece processing sheet made using this substrate film is used for workpiece cutting with a rotating circular blade. This chip suppression effect can be achieved without exposing the substrate film of this embodiment to radiation such as electron beams or gamma rays. Therefore, according to the substrate film of this embodiment, compared with conventional substrate films manufactured by methods involving radiation irradiation, workpiece processing sheets can be manufactured at a lower manufacturing cost with significantly reduced chip generation.

[0044] Furthermore, the substrate film of this embodiment, which uses the aforementioned polyester resin as a material, has good transparency, making it easy to observe or inspect the workpiece through a workpiece processing sheet equipped with the substrate film.

[0045] 1. Material of the substrate film

[0046] As described above, the substrate film of this embodiment is made of a material containing polyester resin.

[0047] (1) Polyester resin

[0048] The specific composition of the aforementioned polyester resin is not particularly limited, but a polyester resin that readily satisfies conditions 1 and 2, thereby making the substrate film more flexible, is preferred. From this perspective, the polyester resin preferably has an alicyclic structure.

[0049] From the perspective of achieving better flexibility in the substrate film, the alicyclic structure of the aforementioned polyester resin preferably has 6 or more carbon atoms in its constituent rings. Furthermore, the number of carbon atoms is preferably 14 or less, particularly preferably 10 or less. A carbon atom count of 6 is especially preferred. Moreover, the alicyclic structure can be a monocyclic type consisting of one ring, a bicyclic type consisting of two rings, or an alicyclic structure consisting of three or more rings.

[0050] Furthermore, from the perspective of achieving better flexibility in the substrate film, the aforementioned polyester resin preferably contains a dicarboxylic acid with an alicyclic structure as a monomer unit constituting the polyester resin. Similarly, from the same perspective, the aforementioned polyester resin preferably contains a diol with an alicyclic structure as a monomer unit constituting the polyester resin. The polyester resin may contain only either this dicarboxylic acid or the diol, but from the perspective of achieving better flexibility, it is preferable that the polyester resin contains both this dicarboxylic acid and the diol.

[0051] The structure of the aforementioned dicarboxylic acids is not particularly limited as long as it has an alicyclic structure and two carboxyl groups. For example, the dicarboxylic acid can be a structure formed by two carboxyl groups bonded to an alicyclic structure, or it can be a structure formed by further inserting an alkyl group or the like between such an alicyclic structure and the carboxyl group. Preferred examples of such dicarboxylic acids include 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, decahydronaphthalene-1,4-dicarboxylic acid, decahydronaphthalene-1,5-dicarboxylic acid, decahydronaphthalene-2,6-dicarboxylic acid, and decahydronaphthalene-2,7-dicarboxylic acid, among which 1,4-cyclohexanedicarboxylic acid is preferred. These dicarboxylic acids can also be derivatives of alkyl esters, etc. Such alkyl ester derivatives can be, for example, alkyl esters with 1 or more and 10 or fewer carbon atoms. More specific examples include dimethyl esters, diethyl esters, etc., with dimethyl esters being particularly preferred.

[0052] In this embodiment, when the polyester resin contains a dicarboxylic acid having an alicyclic structure as a monomer unit, the proportion of the dicarboxylic acid monomer relative to all 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. By placing it within these ranges, the substrate film of this embodiment readily exhibits superior flexibility.

[0053] Furthermore, when the polyester resin in this embodiment includes a dicarboxylic acid with an alicyclic structure as a monomer unit constituting it, the proportion of the dicarboxylic acid with an alicyclic structure relative to the total amount of dicarboxylic acids with a cyclic 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. By setting the above proportion to 60% or more, the substrate film of this embodiment tends to have superior flexibility. In addition, the upper limit of this proportion is not particularly limited; for example, it can be 100% or less. Furthermore, the dicarboxylic acids with cyclic structures mentioned above include, in addition to dicarboxylic acids with alicyclic structures, dicarboxylic acids with aromatic ring structures, etc.

[0054] The structure of the aforementioned diol is not particularly limited as long as it has an alicyclic structure and two hydroxyl groups. For example, the diol can be a structure formed by two hydroxyl groups bonded to an alicyclic structure, or it can be a structure formed by further inserting alkyl groups between such an alicyclic structure and the hydroxyl groups. Preferred examples of such diols include 1,2-cyclohexanediol (especially 1,2-cyclohexanediol), 1,3-cyclohexanediol (especially 1,3-cyclohexanediol), 1,4-cyclohexanediol (especially 1,4-cyclohexanediol), and 2,2-bis-(4-hydroxycyclohexyl)-propane, among which 1,4-cyclohexanediol is preferred.

[0055] In this embodiment, when the polyester resin comprises a diol having an alicyclic structure as a monomer unit, the proportion of this diol monomer relative to all 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. By placing it within these ranges, the substrate film of this embodiment readily exhibits superior flexibility.

[0056] For the polyester resin in this embodiment, from the perspective of easily achieving superior flexibility in the substrate film, the polyester resin preferably includes a dimer acid obtained by dimerizing unsaturated fatty acids as a monomer unit constituting the polyester resin. Here, the number of carbon atoms in the unsaturated fatty acid is preferably 10 or more, particularly preferably 15 or more. Furthermore, the number of carbon atoms is preferably 30 or less, particularly preferably 25 or less. Examples of such dimer acids include dicarboxylic acids with 36 carbon atoms obtained by dimerizing unsaturated fatty acids with 18 carbon atoms, such as oleic acid and linoleic acid; and dicarboxylic acids with 44 carbon atoms obtained by dimerizing unsaturated fatty acids with 22 carbon atoms, such as erucic acid. In addition, when obtaining the above-mentioned dimer acid, a small amount of trimer acid formed by trimerizing the above-mentioned unsaturated fatty acids may also be generated. The polyester resin in this embodiment may contain both the above-mentioned dimer acid and this trimer acid.

[0057] When the polyester resin in this embodiment contains the aforementioned dimer acid as a monomer unit constituting it, the proportion of the dimer acid relative to all 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. By placing it within these ranges, the polyester resin readily possesses the desired softness, and as a result, the substrate film of this embodiment readily possesses superior softness.

[0058] The polyester resin in this embodiment may also contain monomers other than the dicarboxylic acids, diols, and dimer acids mentioned above as monomer units constituting it. Examples of such monomers include aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic 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. Furthermore, it may also contain diols other than those with alicyclic structures. For example, it may contain ethylene glycol, propylene glycol, butanediol, hexanediol, octanediol, decanediol; ethylene oxide adducts of bisphenol A, bisphenol S, etc.; and trimethylolpropane, etc.

[0059] However, in the polyester resin of this embodiment, from the perspective of easily achieving superior flexibility, it is preferable to include more monomers with alicyclic structures (such as dicarboxylic acids with alicyclic structures and diols with aliphatic structures) than monomers with aromatic ring structures. In particular, among the monomer units constituting the polyester resin of this embodiment, the molar ratio of monomer units with aromatic ring structures to monomer units with alicyclic structures 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.

[0060] Furthermore, the heat of fusion of the polyester resin in this embodiment, measured by differential scanning calorimetry at a heating rate of 20°C / min, is preferably 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. By setting the heat of fusion to 2 J / g or more, the crystallinity of the substrate film is moderately increased, resulting in better operability and processability. Furthermore, this 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 most preferably 30 J / g or less. By setting the heat of fusion to 150 J / g or less, the substrate film of this embodiment tends to have superior flexibility. The details of the method for measuring the heat of fusion are described in the Examples section below.

[0061] The method for manufacturing the polyester resin in this embodiment is not particularly limited. The polyester resin can be obtained by using a known catalyst to polymerize the monomer components.

[0062] The polyester resin content in the material constituting the substrate film of 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 above-mentioned 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 keeping the polyester resin content in the material within the above range, the substrate film constituting it tends to have better flexibility.

[0063] (2) Elastomer

[0064] In addition to the aforementioned polyester resin, the material used to manufacture the substrate film of this embodiment preferably contains an elastomer. By including an elastomer in the material, conditions 1 and 2 are easily satisfied, thereby making the substrate film more flexible.

[0065] The elastomer in this embodiment is not particularly limited and can be either a thermosetting elastomer or a thermoplastic elastomer. However, from the perspective that the substrate film of this embodiment is more likely to have better flexibility, a thermoplastic elastomer is preferred.

[0066] The examples of the aforementioned thermoplastic elastomers are not particularly limited. For example, styrene-based elastomers, acrylic elastomers, urethane elastomers, olefin elastomers, polyester elastomers, and silicone elastomers can be used. These elastomers can be used alone or in combination of two or more. Among the aforementioned elastomers, from the perspective of easily achieving superior flexibility, at least one of styrene-based elastomers, acrylic elastomers, urethane elastomers, and olefin elastomers is preferred; particularly preferred is at least one of styrene-based elastomers, acrylic elastomers, and urethane elastomers; and even more preferred is styrene-based elastomers. Furthermore, from the perspective of easily adjusting the physical properties of the substrate film to the desired range, urethane elastomers are preferred.

[0067] In this specification, "styrene-based elastomer" is a copolymer containing structural units derived from styrene or its derivatives (styrene compounds), and is a thermoplastic material that has rubber-like elasticity in a temperature range including room temperature.

[0068] Examples of styrene-based elastomers include styrene-conjugated diene copolymers and styrene-olefin copolymers. Specific examples of styrene-conjugated diene copolymers include non-hydrogenated styrene-conjugated diene copolymers such as styrene-butadiene copolymers, styrene-butadiene-styrene copolymers (SBS), styrene-butadiene-butene-styrene copolymers, styrene-isoprene copolymers, styrene-isoprene-styrene copolymers (SIS), and styrene-ethylene-isoprene-styrene copolymers; and hydrogenated styrene-conjugated diene copolymers such as styrene-ethylene / propylene-styrene copolymers (SEPS) and styrene-ethylene / butene-styrene copolymers (SEBS). These styrene-based elastomers can be used alone or in combination of two or more. Among the aforementioned styrene-based elastomers, styrene-conjugated diene copolymers are preferred from the perspective of easily achieving better flexibility; hydrogenated styrene-conjugated diene copolymers are preferred, and styrene-ethylene / butene-styrene copolymers are even more preferred.

[0069] When using a styrene-ethylene / butene-styrene copolymer, 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. Furthermore, the styrene content is 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 / butene-styrene copolymer with a styrene content within the above range, the substrate film of this embodiment readily exhibits superior flexibility.

[0070] In this specification, "acrylic elastomer" is a copolymer containing structural units derived from acrylic acid or its derivatives (acrylic compounds), and is a thermoplastic material that has rubber-like elasticity in a temperature range including room temperature.

[0071] Examples of acrylic elastomers include (meth)acrylic diblock copolymers and (meth)acrylic triblock copolymers. These copolymers have the following structure: at one or both ends of relatively soft segments (soft segments) composed of polybutyl acrylate (PBA) and poly(2-ethylhexyl acrylate) (2EHA), harder segments (hard segments) composed of polymethyl methacrylate (PMMA) that mimic crosslinking are linked. From the perspective of film strength, (meth)acrylic triblock copolymers are preferred.

[0072] Examples of the above-mentioned (meth)acrylic triblock copolymers include polymethyl methacrylate (PMMA)-polybutyl acrylate (PBA)-polymethyl methacrylate (PMMA) and polymethyl methacrylate (PMMA)-polyethylhexyl acrylate-polymethyl methacrylate (PMMA).

[0073] When using an acrylic elastomer, specifically a (meth)acrylate triblock copolymer with PMMA segments as described above, the ratio of methyl methacrylate monomer to all monomers constituting the copolymer (MMA ratio) is preferably 10% by weight or more, particularly preferably 20% by weight or more, and even more preferably 30% by weight or more. Furthermore, this MMA ratio is preferably 80% or less, particularly preferably 70% by weight or less, and even more preferably 60% by weight or less. By using a (meth)acrylate triblock copolymer with an MMA ratio within the above-mentioned range, the substrate film of this embodiment readily exhibits superior flexibility.

[0074] In this specification, "urethane elastomer" is a copolymer containing structural units derived from urethane compounds or their derivatives (urethane compounds), and is a material that has rubber-like elasticity and thermoplasticity in a temperature range including room temperature.

[0075] In particular, urethane elastomers are typically obtained by reacting long-chain polyols, chain extenders and polyisocyanates, and consist of soft segments having structural units derived from long-chain polyols and hard segments having polyurethane structures obtained by reacting chain extenders and polyisocyanates.

[0076] If urethane elastomers are classified according to the type of long-chain polyols used as their soft segment components, they can be classified into polyester polyurethane elastomers, polyether polyurethane elastomers, polycarbonate polyurethane elastomers, etc.

[0077] Examples of the aforementioned long-chain polyols include polyester polyols such as lactone-based polyester polyols and adipate-based polyester polyols; poly(ethylene) polyols and polytetramethylene ether glycols; and polycarbonate polyols.

[0078] Examples of the aforementioned polyisocyanates include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, and hexamethylene diisocyanate.

[0079] Examples of chain extenders include low molecular weight polyols such as 1,4-butanediol and 1,6-hexanediol, as well as aromatic diamines.

[0080] In this specification, "olefin elastomer" is a copolymer containing structural units derived from olefins or their derivatives (olefin compounds), and is a thermoplastic material that has rubber-like elasticity in a temperature range including room temperature.

[0081] As an olefin elastomer, examples include olefin elastomers comprising at least one resin selected from the group consisting of ethylene-α-olefin copolymers, propylene-α-olefin copolymers, butene-α-olefin copolymers, ethylene-propylene-α-olefin copolymers, ethylene-butene-α-olefin copolymers, propylene-butene-α-olefin copolymers, and ethylene-propylene-butene-α-olefin copolymers.

[0082] The elastomer content in the material constituting the substrate film of 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. By making the elastomer content in the material 4% by mass or more, the substrate film formed using this material is more likely to have better flexibility. Furthermore, the above-mentioned content is preferably 45% by mass or less, particularly preferably 40% by mass or less, and even more preferably 35% by mass or less. By making the elastomer content in the material 45% by mass or less, it is easier to form the substrate film using this material and to easily achieve excellent chip suppression effect.

[0083] (3) Other ingredients

[0084] The material used to manufacture the substrate film of this embodiment may also contain other components besides the polyester resin and elastomer described above. In particular, the material may also contain components commonly used in substrate films for workpiece processing.

[0085] Examples of such components include flame retardants, plasticizers, lubricants, antioxidants, colorants, infrared absorbers, ultraviolet absorbers, ion scavengers, and various other additives. While there are no particular limitations on the content of these additives, it is preferable to set them within the range where the substrate film performs its desired function.

[0086] (4) Composition of the substrate film

[0087] As for the layer composition of the substrate film in this embodiment, it can be a single layer or multiple layers, as long as it includes a layer made of a material containing the polyester resin (hereinafter, sometimes referred to as "resin layer A"). From the perspective of reducing manufacturing costs, the substrate film in this embodiment is preferably a single layer (resin layer A only). On the other hand, when there are multiple layers, multiple layers of resin layer A can be stacked, or resin layer A can be stacked with other layers.

[0088] In addition, for the surface of the laminated adhesive layer in the substrate film, in order to improve the adhesion with the adhesive layer, surface treatments such as primer treatment, corona treatment, and plasma treatment can be applied.

[0089] 2. Physical properties of the substrate film, etc.

[0090] The tensile modulus of the substrate film in this embodiment, when subjected to a tensile test at 200 mm / min at 23°C, is preferably 800 MPa or less, particularly preferably 600 MPa or less, and even more preferably 500 MPa or less. By setting the tensile modulus to 800 MPa or less, conditions 1 and 2 are easily satisfied, thereby making the substrate film of this embodiment more flexible. 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. Moreover, by setting the tensile modulus to 100 MPa or more, the substrate film of this embodiment readily possesses moderate strength, and workpiece processing sheets equipped with this substrate film exhibit good handlingability and facilitate satisfactory workpiece processing.

[0091] The tensile modulus of the substrate film in this embodiment, when subjected to a tensile test at a tensile speed of 406 mm / min at 23°C, is preferably 800 MPa or less, particularly preferably 600 MPa or less, and even more preferably 500 MPa or less. By setting the tensile modulus to 800 MPa or less, conditions 1 and 2 are easily satisfied, thereby making the substrate film of this embodiment more flexible. 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. Moreover, by setting the tensile modulus to 50 MPa or more, the substrate film of this embodiment readily possesses moderate strength, and the workpiece processing sheet equipped with this substrate film exhibits good handlingability and facilitates the desired workpiece processing. Additionally, in this specification, the tensile speed of 406 mm / min represents a value obtained by converting the stress velocity of the workpiece processing sheet under normal stretching conditions into a tensile speed.

[0092] The fracture stress measured when the substrate film of this embodiment is subjected to a tensile test at a tensile speed of 200 mm / min at 23°C is preferably 60 MPa or less, particularly preferably 50 MPa or less, and even more preferably 40 MPa or less. By setting the fracture stress to 60 MPa or less, the substrate film of this embodiment has better processability. Furthermore, the fracture stress 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. By setting the fracture stress to 15 MPa or more, the substrate film of this embodiment easily possesses moderate strength, and the workpiece processing sheet having this substrate film has good handlingability and is easy to process into the desired workpiece. Furthermore, by setting the fracture stress to 15 MPa or more, the substrate film of this embodiment has good scalability.

[0093] The fracture stress measured when the substrate film in this embodiment is subjected to a tensile test at a tensile speed of 406 mm / min at 23°C is preferably 60 MPa or less, particularly preferably 50 MPa or less, and even more preferably 40 MPa or less. By setting the fracture stress to 60 MPa or less, the substrate film of this embodiment has better processability. Furthermore, the fracture stress is preferably 5 MPa or more, particularly preferably 10 MPa or more, even more preferably 15 MPa or more, more preferably 20 MPa or more, and more preferably 25 MPa or more. By setting the fracture stress to 5 MPa or more, the substrate film of this embodiment easily possesses moderate strength, and the workpiece processing sheet containing this substrate film has good handlingability and is easy to process into the desired workpiece. Furthermore, by setting the fracture stress to 5 MPa or more, the substrate film of this embodiment has good scalability.

[0094] The elongation at break of the substrate film in this embodiment, when subjected to a tensile test at a tensile speed of 200 mm / min at 23°C, is preferably 150% or more, more preferably 200% or more, particularly preferably 250% or more, further preferably 300% or more, and most preferably 350% or more. By achieving an elongation at break of 200% or more, the substrate film in this embodiment readily possesses the desired elongation, and workpiece processing sheets equipped with this substrate film easily achieve excellent expandability and pick-up properties. Furthermore, the elongation at break is preferably 800% or less, more preferably 700% or less, particularly preferably 600% or less, and further preferably 500% or less. By achieving an elongation at break of 800% or less, the processability of the substrate film is more excellent, making it easier to manufacture the desired workpiece processing sheets.

[0095] The elongation at break of the substrate film in this embodiment, when subjected to a tensile test at a tensile speed of 406 mm / min at 23°C, is preferably 150% or more, particularly preferably 200% or more, further preferably 250% or more, more preferably 300% or more, and more preferably 350% or more. By achieving an elongation at break of 150% or more, the substrate film in this embodiment readily possesses the desired elongation, and workpiece processing sheets equipped with this substrate film easily achieve excellent expandability and pick-up properties. Furthermore, the elongation at break is preferably 800% or less, particularly preferably 700% or less, further preferably 600% or less, and more preferably 500% or less. By achieving an elongation at break of 800% or less, the processability of the substrate film is even better, making it easier to manufacture the desired workpiece processing sheets.

[0096] In addition, the detailed methods for determining the tensile modulus, fracture point stress, and elongation at break are described in the test examples below.

[0097] The thickness of the substrate film in 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 substrate film is preferably 600 μm or less, particularly preferably 300 μm or less, and even more preferably 200 μm or less. By making the thickness of the substrate film 20 μm or more, the workpiece processing sheet having the substrate film easily possesses appropriate strength, and it is easy to effectively support and fix the workpiece on the workpiece processing sheet. As a result, chipping during cutting can be effectively suppressed. Furthermore, by making the thickness of the substrate film 600 μm or less, the aforementioned elongation at break is easily achieved. Moreover, by making the thickness of the substrate film 600 μm or less, the substrate film has better processability.

[0098] 3. Manufacturing method of substrate film

[0099] The manufacturing method of the substrate film in this embodiment is not particularly limited as long as the material containing the polyester resin is used. For example, melt extrusion methods such as T-die method and circular die method; calendering method; solution method such as dry method and wet method can be used. Among these, melt extrusion method or calendering method is preferred from the perspective of manufacturing substrate efficiently.

[0100] When manufacturing a substrate film consisting of a single layer by melt extrusion, the substrate film material (containing the aforementioned polyester resin and elastomer) is kneaded and the resulting mixture is directly extruded using a known extruder to form a film, or the substrate film material is kneaded and the resulting mixture is first made into granules and then extruded using a known extruder to form a film.

[0101] In addition, when manufacturing a substrate film consisting of multiple layers by melt extrusion, the components constituting each layer are kneaded separately and multiple layers are extruded simultaneously from the obtained kneaded mixture using a known extruder to form a film, or the components constituting each layer are kneaded separately and the obtained kneaded mixture is first made into granules and then multiple layers are extruded simultaneously using a known extruder to form a film.

[0102] [Workpiece machining sheet]

[0103] The workpiece processing sheet of this embodiment includes the substrate film and an adhesive layer laminated on one side of the substrate film.

[0104] 1. Composition of workpiece machining discs

[0105] The following describes the components of the workpiece processing sheet constituting this embodiment, excluding the substrate film.

[0106] (1)Adhesive layer

[0107] As for the adhesive constituting the adhesive layer, there are no particular limitations as long as it can exert sufficient adhesion to the adhered objects (especially sufficient adhesion to the workpiece for machining). Examples of adhesives constituting the adhesive layer include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, and polyvinyl ether adhesives. Among these, acrylic adhesives are preferred from the perspective of easily exerting the required adhesion.

[0108] The adhesive constituting the adhesive layer of this embodiment can also be an adhesive that does not have the curability of active energy rays, but it is preferably an adhesive that has the curability of active energy rays (hereinafter, sometimes referred to as "active energy ray curable adhesive"). By making the adhesive layer composed of an active energy ray curable adhesive, the adhesive layer can be cured by irradiation with active energy rays, which makes it easier to reduce the adhesion of the workpiece processing sheet to the adhered object. In particular, the processed workpiece can be easily separated from the adhesive sheet by irradiation with active energy rays.

[0109] The active energy ray curable adhesive constituting the adhesive layer can be a polymer with active energy ray curability as the main component, or a mixture of a non-active energy ray curable polymer (polymer without active energy ray curability) and monomers and / or oligomers having at least one active energy ray curable group as the main component.

[0110] The polymer with active energy radiation curable properties is preferably a (meth)acrylate polymer (hereinafter sometimes referred to as "active energy radiation curable polymer") with an active energy radiation curable functional group (active energy radiation curable group) introduced into its side chain. Preferably, this active energy radiation curable polymer is an active energy radiation curable polymer obtained by reacting an acrylic copolymer having a functional group-containing monomer unit with a compound having an unsaturated group having a functional group bonded to said functional group. Furthermore, in this specification, (meth)acrylic acid refers to acrylic acid and methacrylic acid. The same applies to other similar terms. Furthermore, "polymer" also includes the concept of "copolymer".

[0111] The weight-average molecular weight of the aforementioned 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. Furthermore, this weight-average molecular weight is preferably 2.5 million or less, particularly preferably 2 million or less, and even more preferably 1.5 million or less. Additionally, the weight-average molecular weight (Mw) in this specification is a value converted from standard polystyrene determined by gel permeation chromatography (GPC).

[0112] On the other hand, when the active energy-curable adhesive uses a mixture of an inactive energy-curable polymer and a monomer and / or oligomer having at least one active energy-curable group as its main component, the inactive energy-curable polymer component can, for example, be the aforementioned acrylic copolymer before reacting with a compound containing an unsaturated group. Furthermore, the active energy-curable monomer and / or oligomer can, for example, be an ester of a polyol and (meth)acrylic acid.

[0113] The weight-average molecular weight of the acrylic polymer used as the component of the aforementioned inactive energy-curable polymer is preferably 10,000 or more, particularly preferably 150,000 or more, and even more preferably 200,000 or more. Furthermore, the weight-average molecular weight is preferably 2.5 million or less, particularly preferably 2 million or more, and even more preferably 1.5 million or less.

[0114] Furthermore, when using ultraviolet light as the active energy ray for curing the active energy ray-curable adhesive, it is preferable to add a photopolymerization initiator to the adhesive. Alternatively, inactive energy ray-curable polymer components or oligomer components, crosslinking agents, etc., may be added to the adhesive.

[0115] In this embodiment, the thickness of the adhesive layer is preferably 1 μm or more, particularly preferably 2 μm or more, and even more preferably 3 μm or more. Furthermore, the thickness of the adhesive layer is preferably 50 μm or less, particularly preferably 40 μm or less, and even more preferably 30 μm or less. By making the adhesive layer thickness 1 μm or more, the workpiece processing sheet of this embodiment easily achieves the required adhesion. Furthermore, by making the adhesive layer thickness 50 μm or less, it is easy to separate the adhered objects from the cured adhesive layer.

[0116] (2) Peeling sheet

[0117] In the workpiece processing sheet of this embodiment, before attaching the side of the adhesive layer opposite to the substrate film (hereinafter, sometimes referred to as the "adhesive side") to the object to be bonded, a release sheet may be stacked on the surface for the purpose of protecting the surface.

[0118] The composition of the release sheet is optional. For example, a release sheet obtained by peeling a plastic film using a release agent or the like can be shown. Specific examples of such plastic films include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; and polyolefin films such as polypropylene and polyethylene. As the release agent, silicone, fluorine, long-chain alkyl, etc., can be used, with silicone being preferred due to its low cost and stable properties.

[0119] There are no particular restrictions on the thickness of the aforementioned release sheet; for example, it can be above 20 μm and below 250 μm.

[0120] (3) Other

[0121] In the workpiece processing sheet of this embodiment, an adhesive layer may also be laminated on the side of the adhesive layer opposite to the substrate film. In this case, the workpiece processing sheet of this embodiment can be used to cut a die. By attaching the workpiece to the side of the adhesive layer opposite to the adhesive layer in the sheet, and cutting the adhesive layer together with the workpiece, a chip with a monolithized adhesive layer laminated on it can be obtained. The chip can be easily fixed to the object on which the chip is to be mounted using this monolithized adhesive layer. As the material 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, etc.

[0122] Furthermore, in the workpiece processing sheet of this embodiment, a protective film forming layer can be laminated on the adhesive surface of the adhesive layer. In this case, the workpiece processing sheet of this embodiment can be used as a protective film forming and cutting sheet. By attaching the workpiece to the side of the protective film forming layer opposite to the adhesive layer, and cutting the protective film forming layer together with the workpiece, a chip with a stacked monolithic protective film forming layer can be obtained. Preferably, a workpiece with a circuit formed on one side is used; in this case, the protective film forming layer is typically laminated on the side opposite to the side with the circuit formed. By curing the monolithic protective film forming layer at a predetermined time, a protective film with sufficient durability can be formed on the chip. The protective film forming layer is preferably composed of an uncured curable adhesive.

[0123] 2. Manufacturing method of workpiece machining sheet

[0124] The manufacturing method of the workpiece processing sheet in this embodiment is not particularly limited. For example, it is preferable to form an adhesive layer on the release sheet and then laminate one side of the substrate film onto the side of the adhesive layer opposite to the release sheet, thereby obtaining the workpiece processing sheet.

[0125] The adhesive layer described above can be formed using known methods. For example, a coating liquid containing an adhesive composition for forming the adhesive layer, and further containing a solvent or dispersion medium as needed, is prepared. The coating liquid is then applied to the peelable surface of the release sheet (hereinafter sometimes referred to as the "peel surface"). The resulting coating is then dried, thereby forming the adhesive layer.

[0126] The coating liquid can be applied using known methods, such as bar coating, blade coating, roller coating, squeegee coating, die coating, gravure coating, etc. Furthermore, the properties of the coating liquid are not particularly limited as long as it can be applied; some contain components for forming the adhesive layer as solutes, while others contain components for forming the adhesive layer as dispersion media. Additionally, the release liner can be used as a process material for peeling off the adhesive layer, or it can protect the adhesive layer until it is adhered to the substrate.

[0127] When the adhesive composition used to form the adhesive layer contains the aforementioned crosslinking agent, it is preferable to change the aforementioned drying conditions (temperature, time, etc.) or to perform an additional heat treatment to allow the polymer components in the coating film to undergo a crosslinking reaction with the crosslinking agent, thereby forming a crosslinked structure within the adhesive layer at the desired density. Furthermore, to ensure the crosslinking reaction proceeds sufficiently, the adhesive layer may be cured, for example, by standing for several days at 23°C and 50% relative humidity after being bonded to the substrate.

[0128] 3. How to use the workpiece machining disc

[0129] The workpiece processing sheet of this embodiment can be used for processing workpieces such as semiconductor wafers. In this case, the workpiece can be processed on the workpiece after the adhesive side of the workpiece processing sheet of this embodiment is attached to the workpiece. Based on this processing, the workpiece processing sheet of this embodiment can be used as a back-grinding sheet, a dicing sheet, an extension sheet, a pick-up sheet, etc., for workpiece processing. Examples of workpieces include semiconductor wafers, semiconductor packages, and other semiconductor components, as well as glass components such as glass plates.

[0130] As described above, the workpiece processing sheet of this embodiment can be well expanded due to the good flexibility of the substrate film. Therefore, the workpiece processing sheet of this embodiment is particularly suitable for use as a cutting sheet, an expansion sheet, or a pickup sheet.

[0131] Furthermore, when the workpiece processing sheet of this embodiment has the aforementioned adhesive layer, it can be used as a die-cutting sheet. Moreover, when the workpiece processing sheet of this embodiment has the aforementioned protective film forming layer, it can be used as a protective film forming and cutting sheet.

[0132] Furthermore, when the adhesive layer in the workpiece processing sheet of this embodiment is composed of the aforementioned active energy ray-curable adhesive, it is preferable to subject it to irradiation with the following active energy rays during use. That is, when processing a workpiece on the workpiece processing sheet and separating the processed workpiece from the workpiece processing sheet, it is preferable to irradiate the adhesive layer with active energy rays before performing this separation. As a result, the adhesive layer cures, the adhesion of the workpiece processing sheet to the processed workpiece is significantly reduced, and the processed workpiece can be easily separated.

[0133] The embodiments described above are provided for ease of understanding of the present invention and are not intended to limit the invention. Therefore, the elements disclosed in the above embodiments also include all design changes and equivalents that fall within the technical scope of the present invention.

[0134] Example

[0135] The present invention will be further described in detail below through examples, etc., however, the scope of the present invention is not limited to these examples, etc.

[0136] [Example 1]

[0137] (1) Fabrication of substrate film

[0138] 12.90 kg of dimethyl 1,4-cyclohexanedicarboxylate (98% trans isomer), 11.47 kg of 1,4-cyclohexanediethanol, 0.3 kg of ethylene glycol, and 0.11 kg of an ethylene glycol solution containing 10% manganese acetate tetrahydrate were added to a reactor equipped with a stirrer, distillation tube, and vacuum device. The mixture was heated to 200°C under a nitrogen atmosphere and then raised to 230°C after 1 hour. After maintaining this state for 2 hours to carry out the transesterification reaction, 10.30 kg of erucic acid-derived dimer acid (44 carbon atoms, manufactured by Croda International Plc, product name "PRIPOL 1004") and 0.11 kg of an ethylene glycol solution containing 10% trimethyl phosphate were added to the reaction system, followed by an esterification reaction at 230°C for 1 hour. Next, 300 ppm of germanium dioxide was added as a polycondensation catalyst and stirred. The pressure was then reduced to below 133 Pa for 1 hour. During this time, the internal temperature was increased from 230°C to 270°C, and the mixture was stirred until the desired viscosity was achieved under a high vacuum below 133 Pa to carry out the polycondensation reaction. The resulting polymer was extruded into strands in water and then cut into granules.

[0139] The resulting polyester resin granules were dried at 85°C for at least 4 hours. Then, using a twin-screw kneader, 70 parts by weight of the dried granules were kneaded with 30 parts by weight of a styrene-ethylene / butene-styrene copolymer (SEBS) as a styrene-based elastomer (styrene:ethylene / butene ratio = 20:80, melt flow rate (MFR) = 13.0 g / 10 min (measured according to ISO 1133, at 230°C and a load of 2.16 kg)). The resulting granules were fed into the feed hopper of a single-screw extruder equipped with a T-die. Then, under conditions of a cylinder temperature of 220°C and a die temperature of 220°C, the granules were extruded from the T-die in a molten kneaded state and cooled by cooling rollers, thereby obtaining a sheet-like substrate film with a thickness of 80 μm.

[0140] Furthermore, the aforementioned polyester resin contains approximately 50 mol% of 1,4-cyclohexanediethanol, approximately 40.5 mol% of dimethyl 1,4-cyclohexanedicarboxylate, and 9.5 mol% of erucic acid-derived dimer acid as monomers constituting the resin. Moreover, the proportion of the dimer acid to all dicarboxylic acid units constituting the aforementioned polyester resin is 19.1 mol%. Further, the heat of fusion of the aforementioned polyester resin was determined by the method described later, and the result was 20 J / g.

[0141] (2) Preparation of adhesive composition

[0142] 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)acrylate polymer. The weight-average molecular weight (Mw) of this acrylic polymer was determined by the method described later, and the result was 500,000.

[0143] 100 parts by weight of the (meth)acrylate polymer obtained as described above (solid component conversion, the same applies below), 120 parts by weight of the urethane acrylate oligomer (Mw: 8,000), 5 parts by weight of the isocyanate crosslinking agent (manufactured by TOSOH CORPORATION, product name "CORONATE L") and 4 parts by weight of the photopolymerization initiator (manufactured by IGMresins BV, product name "Omnirad 184") are mixed to obtain an energy-curable adhesive composition.

[0144] (3) Formation of adhesive layer

[0145] The adhesive composition obtained in step (2) above is coated onto the release surface of a release sheet (manufactured by LINTEC Corporation, product name "SP-PET381031"), which is 38 μm thick and obtained by peeling one side of a polyethylene terephthalate film using an organosilicon release agent. The resulting coating is then dried at 100°C for 1 minute. This results in a laminate with an adhesive layer of 10 μm thickness formed on the release surface of the release sheet.

[0146] (4) Fabrication of workpiece machining discs

[0147] By bonding one side of the substrate film obtained in step (1) to the adhesive layer side of the laminate obtained in step (3), a workpiece processing sheet is obtained.

[0148] Here, the heat of fusion of the polyester resin is determined according to JIS K 7121:2012 using a differential scanning calorimeter (DSC, manufactured by TA Instruments, product name "DSC Q2000").

[0149] Specifically, first, the temperature was increased from room temperature to 250°C at a rate of 20°C / min and maintained at 250°C for 10 minutes, then decreased to -60°C at a rate of 20°C / min and maintained at -60°C for 10 minutes. Then, the temperature was increased again to 250°C at a rate of 20°C / min to obtain the DSC curve, and the melting point was determined.

[0150] Furthermore, the above weight-average molecular weight (Mw) is the weight-average molecular weight converted from standard polystyrene determined using gel permeation chromatography (GPC) under the following conditions (GPC determination).

[0151] <Measurement Conditions>

[0152] • Measuring apparatus: Manufactured by TOSOH CORPORATION, HLC-8320

[0153] • GPC column (passes in the following order): manufactured by TOSOH CORPORATION

[0154] TSK gel super HH

[0155] TSK gel super HM-H

[0156] TSK gel super H2000

[0157] • Solvent for determination: Tetrahydrofuran

[0158] • Measurement temperature: 40℃

[0159] [Example 2]

[0160] Except for changing the mass ratio of dried polyester resin particles to SEBS to 80:20 in the process of making the substrate film, the substrate film was made in the same manner as in Example 1, and the workpiece processing sheet was obtained by using the substrate film in the same manner as in Example 1.

[0161] [Example 3]

[0162] Except for changing the mass ratio of dried polyester resin particles to SEBS to 90:10 in the process of making the substrate film, the substrate film was made in the same manner as in Example 1, and the workpiece processing sheet was obtained by using the substrate film in the same manner as in Example 1.

[0163] [Example 4]

[0164] Particles of dried polyester resin were obtained in the same manner as in step (1) of Example 1. 80 parts by weight of these particles and 20 parts by weight of a polymethyl methacrylate (PMMA)-polybutyl acrylate (PBA)-polymethyl methacrylate (PMMA) triblock copolymer (granular, MMA ratio = 50 wt%, melt flow rate (MFR) = 31.0 g / 10 min (measured according to ISO 1133, at 230°C and 2.16 kg load)) were kneaded using a twin-screw kneader. The resulting particles were then fed into the feed hopper of a single-screw extruder equipped with a T-die. The particles were then extruded from the T-die in a molten kneaded state at a cylinder temperature of 220°C and a die temperature of 220°C, and cooled by cooling rollers to obtain a sheet-like substrate film with a thickness of 80 μm. A workpiece processing sheet was obtained, except using this substrate film, in the same manner as in Example 1.

[0165] [Example 5]

[0166] Particles of dried polyester resin were obtained in the same manner as in step (1) of Example 1. 80 parts by weight of these particles and 20 parts by weight of a thermoplastic polyurethane elastomer (manufactured by BASF JAPAN, product name "Elastollan ET164D"), which is a urethane elastomer, were kneaded together using a twin-screw kneader. The resulting particles were fed into the feed hopper of a single-screw extruder equipped with a T-die. The particles were then extruded from the T-die in a molten kneaded state at a cylinder temperature of 220°C and a die temperature of 220°C, and cooled by cooling rollers to obtain a sheet-like substrate film with a thickness of 80 μm. A workpiece processing sheet was obtained, except using this substrate film, in the same manner as in Example 1.

[0167] [Comparative Example 1]

[0168] Except for the step of making the substrate film, in which the substrate film is made without using SEBS (by feeding dried polyester resin granules into the feed hopper of a single screw extruder equipped with a T-die), the substrate film is made in the same manner as in Example 1, and the substrate film is used to obtain a workpiece processing sheet in the same manner as in Example 1.

[0169] [Comparative Example 2]

[0170] Except that a resin sheet with a thickness of 80 μm, manufactured using an alcohol-modified polyester resin having a structure represented by the following general formula (1), was used as the substrate, a workpiece processing sheet was obtained in the same manner as in Example 1. Furthermore, the heat of fusion of the alcohol-modified polyester resin was measured by the aforementioned method, and the result was 0 J / g.

[0171] [Chemical Formula 1]

[0172]

[0173] [Comparative Example 3]

[0174] Except that a resin sheet with a thickness of 80 μm, manufactured using an amorphous polyester resin having a structure represented by the following general formula (2), was used as the substrate, a workpiece processing sheet was obtained in the same manner as in Example 1. Furthermore, the heat of fusion of the aforementioned amorphous polyester resin was measured using the method described above, and the result was 0 J / g.

[0175] [Chemical Formula 2]

[0176]

[0177] [Experimental Example 1] (Determination of tensile properties of substrate film)

[0178] The substrate films prepared in the examples and comparative examples were cut into test pieces of 15mm × 150mm. The 150mm edge was cut parallel to the MD direction (the longitudinal direction during substrate film manufacturing), and the 15mm edge was cut parallel to the TD direction (the direction perpendicular to the MD direction). Then, for this test piece, the tensile modulus, elongation at break, and stress at the point of fracture were measured according to JIS K7127:1999.

[0179] Specifically, using a tensile testing machine (manufactured by Shimadzu Corporation, product name "Autograph AG-X plus 100N"), with the clamp spacing set to 100 mm, the test specimens were subjected to tensile testing in the MD direction of the substrate film at 200 mm / min and at an environment of 23°C. The tensile modulus (MPa), elongation at break (%), and stress at the point of fracture (MPa) were measured. These results related to the tensile speed of 200 mm / min are shown in Table 1.

[0180] In addition, except that the stretching speed was changed to 406 mm / min, tensile tests were performed in the same manner as described above, and the tensile modulus (MPa), elongation at break (%), and stress at the point of fracture (MPa) were measured. These results related to the stretching speed of 406 mm / min are shown in Table 1. Furthermore, in Comparative Examples 2 and 3, the absolute value of the difference between the maximum and minimum tensile stresses was significantly higher than 2.0. Therefore, for Comparative Examples 2 and 3, it was determined that it was not very meaningful to investigate the tensile modulus, elongation at break, and stress at the stretching speed of 406 mm / min in detail, and therefore, these measurements were not performed on Comparative Examples 2 and 3.

[0181] Furthermore, except for interchangeing the TD and MD directions, test pieces were obtained from the substrate film in the same manner as described above (i.e., test pieces with a 15mm long side parallel to the MD direction and a 150mm long side parallel to the TD direction). For this test piece, a tensile test was performed in the TD direction of the substrate film at a tensile speed of 406mm / min, measuring the change in tensile stress (MPa) as the elongation (%) increased from 0% to 640% (or, if the substrate film was judged before reaching 640%, from 0% to fracture). The measurement results were then plotted on a coordinate plane with elongation (%) on the horizontal axis and tensile stress (MPa) on the vertical axis to create a curve. The presence of a maximum point where the tensile stress becomes a maximum value was confirmed on the curve, and the results are shown in Table 1. Furthermore, when such a maximum point exists, based on the further confirmation that a minimum point exists where the tensile stress becomes a minimum, the absolute value (MPa) of the difference between the tensile stress of the maximum point (which, if multiple exist, is the maximum point with the smallest tensile elongation) and the minimum point (which, if multiple exist, is the minimum point with the smallest tensile elongation) is determined. This result is also shown in Table 1.

[0182] [Experimental Example 2] (Evaluation of Extensibility)

[0183] The release tab is peeled off from the workpiece processing wafer manufactured in the examples and comparative examples. After the exposed surface of the adhesive layer is attached to one side of a silicon wafer with a thickness of 40 μm, a dicing ring frame is attached to the periphery of the exposed surface of the workpiece processing wafer (the position that does not overlap with the silicon wafer). Then, the silicon wafer is diced using a dicing machine (manufactured by DISCO Corporation, product name "DFD6362") under the following conditions.

[0184] • Workpiece (attached object): Silicon wafer

[0185] • Workpiece dimensions: 6 inches in diameter, 40 μm in thickness

[0186] • Cutting blade: Manufactured by DISCO Corporation, product name "27HECC", diamond blade

[0187] • Blade speed: 50,000 rpm

[0188] • Cutting speed: 100mm / second

[0189] • Cutting depth: Cutting from the surface of the substrate film to a depth of 20μm

[0190] • Cutting size: 8mm × 8mm

[0191] Then, the workpiece processing piece with the chip and ring frame obtained by cutting attached is placed on the expansion device (manufactured by JCM Corporation, product name "ME-300B"), and the ring frame is pulled down at a speed of 2 mm / s until the pull-down amount is 40 mm.

[0192] Next, the pull-down amount (mm) at which fracture occurred was recorded. The result is shown in Table 1 as the limit pull-down amount. In addition, for workpieces that do not fracture even when the pull-down amount reaches 40mm, it is shown as "40 or more".

[0193]

[0194] As shown in Table 1, the workpiece processing sheet manufactured in the examples exhibits excellent scalability.

[0195] Industrial applicability

[0196] The substrate film of the present invention is suitable for use as a substrate film for fabricating workpieces such as semiconductor wafers.

Claims

1. A substrate film, characterized in that, It is made of a material containing polyester resin and elastomer. The elastomer is at least one selected from styrene-based elastomers, acrylic elastomers, urethane elastomers, polyester elastomers, and silicone elastomers. The results of a tensile test on the substrate film at a tensile speed of 406 mm / min at 23°C were plotted on a coordinate plane with tensile elongation in % on the horizontal axis and tensile stress in MPa on the vertical axis. For the obtained curve, There are no points in the curve that become a maximum value, or The curve contains at least one point that becomes a maximum and one point that becomes a minimum, and the absolute value of the difference between the tensile stress at the point where the tensile elongation is minimum (the point where the tensile elongation is minimum) and the tensile stress at the point where the tensile elongation is minimum (the point where the tensile elongation is minimum) is less than 2.0 MPa.

2. The substrate film according to claim 1, characterized in that, When the substrate film is subjected to a tensile test at a tensile speed of 406 mm / min at an environment of 23°C, the tensile modulus is measured to be above 50 MPa and below 800 MPa.

3. The substrate film according to claim 1, characterized in that, When the substrate film is subjected to a tensile test at a tensile speed of 200 mm / min at an environment of 23°C, the tensile modulus is measured to be above 50 MPa and below 800 MPa.

4. The substrate film according to claim 1, characterized in that, When the substrate film is subjected to a tensile test at a tensile speed of 406 mm / min at an environment of 23°C, the elongation at break is measured to be more than 150% and less than 800%.

5. The substrate film according to claim 1, characterized in that, When the substrate film is subjected to a tensile test at a tensile speed of 200 mm / min at an environment of 23°C, the elongation at break is measured to be more than 150% and less than 800%.

6. The substrate film according to claim 1, characterized in that, The polyester resin content in the material is 55% by mass or more and 96% by mass or less.

7. The substrate film according to claim 1, characterized in that, The polyester resin has an alicyclic structure.

8. The substrate film according to claim 7, characterized in that, The polyester resin contains dicarboxylic acid having the alicyclic structure as a monomer unit constituting the polyester resin.

9. The substrate film according to claim 7, characterized in that, The polyester resin contains diols having the alicyclic structure as monomer units constituting the polyester resin.

10. The substrate film according to claim 7, characterized in that, The number of carbon atoms in the constituent rings of the alicyclic structure is 6 or more and 14 or less.

11. The substrate film according to claim 1, characterized in that, The polyester resin contains dimer acids obtained by dimerizing unsaturated fatty acids as monomer units constituting the polyester resin. The unsaturated fatty acid has 10 or more but less than 30 carbon atoms.

12. The substrate film according to claim 1, characterized in that, The content of the elastomer in the material is 4% by mass or more and 45% by mass or less.

13. The substrate film according to claim 1, characterized in that, The thickness of the substrate film is greater than 20 μm and less than 600 μm.

14. The substrate film according to claim 1, characterized in that, It is used as a substrate film for forming workpiece processing sheets.

15. A workpiece processing sheet, characterized in that, It comprises a substrate film as described in any one of claims 1 to 14, and an adhesive layer laminated on one side of the substrate film.

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