Adhesive tape for workpiece processing

Abstract

This invention provides an adhesive tape for workpiece processing that can be used as a back-side grinding tape for grinding and thinning semiconductor wafers, and also as a cutting tape for cutting brittle workpieces such as glass substrates. More specifically, the adhesive tape for workpiece processing of this invention comprises, in sequence, a substrate film formed of a polyester resin composition, an intermediate layer, and an active energy radiation-curable adhesive layer. The intermediate layer is formed of a resin composition containing a ternary or higher (meth)acrylate copolymer (A1) comprising methyl acrylate and methacrylic acid as copolymer monomer components. When the total amount of copolymer monomer components constituting the acrylic copolymer (A1) is set as 100 parts by mass, methyl acrylate is contained in the range of 37 to 57 parts by mass, and methacrylic acid is contained in the range of 2 to 7 parts by mass. The active energy radiation-curable adhesive layer is formed of an adhesive composition containing: a (meth)acrylate copolymer (A2) in which 2-ethylhexyl acrylate with carbon-carbon double bonds is introduced as the main copolymer monomer, and a crosslinking agent.

Description

Technical Field

[0001] This invention relates to adhesive tape for workpiece processing that is suitable for use in processing workpieces such as semiconductor wafers and glass substrates. Background Technology

[0002] Conventionally, as a process for manufacturing semiconductor chips for semiconductor devices, known processes include back-grinding (hereinafter sometimes simply referred to as "grinding"), which involves grinding a semiconductor wafer with circuitry formed on its surface from its back side using a grinding wheel to a predetermined thickness to achieve thin-film processing of the semiconductor wafer; and dicing (hereinafter sometimes simply referred to as "cutting" or "splitting"), which involves monolithically converting the semiconductor wafer into a semiconductor chip. Furthermore, as a process for manufacturing camera modules for smartphones, medical sensors, etc., dicing processes are known for monolithically converting glass substrates into glass chips. Examples of adhesive tapes used in grinding or cutting such semiconductor wafers, glass plates, and other workpieces include back-grinding tapes and dicing tapes, which have an active energy radiation-curable adhesive layer on a substrate film.

[0003] The aforementioned back-side polishing tape is used to stably hold and fix semiconductor wafers and protect the circuit surfaces during the back-side polishing process. The specific method of use is as follows: First, the back-side polishing tape is adhered to the side of the semiconductor wafer where the circuit is formed to fix the semiconductor wafer. From the back side of the semiconductor wafer, a polishing wheel is used to polish while simultaneously spraying water until a predetermined thickness is achieved. After the polishing process is completed, the adhesive layer of the back-side polishing tape is irradiated with active energy rays such as ultraviolet (UV) to reduce the adhesion, allowing the back-side polishing tape to be peeled off from the semiconductor wafer.

[0004] Furthermore, the aforementioned dicing tape is used to fix the thin-film semiconductor wafer, which has been thinned by the aforementioned back-side grinding process, into individual semiconductor chips by cutting it into predetermined sizes using a rotating dicing blade, thereby preventing the thin-film semiconductor wafer from shifting position and preventing the individual semiconductor chips from scattering. The specific method of use is as follows: First, after attaching the dicing tape to the ring frame, the thin-film semiconductor wafer is attached and placed on the adhesive layer. Next, cutting is performed while supplying water towards the dicing blade and semiconductor wafer to remove unavoidably generated cutting chips, etc., and while individual chips are being individually cut to predetermined sizes. After the cutting process is completed, the adhesive layer of the dicing tape is irradiated with active energy rays such as ultraviolet (UV) to reduce the adhesion, and the individual semiconductor chips are picked up from the adhesive layer by a pick-up device. Before picking up, the dicing tape is expanded as needed. If picking is complete, the dicing tape is manually peeled off from the ring frame. The ring frame with the dicing tape peeled off is washed and reused.

[0005] In recent years, with the thin-film development of semiconductor devices, there is a need to further thin the semiconductor wafer in the aforementioned back-side polishing process. To polish the semiconductor wafer to a thickness thinner than before, a back-side polishing tape with higher thickness accuracy than previously required is needed. That is, if the thickness of the back-side polishing tape is uneven, this unevenness will affect the semiconductor wafer; sometimes the polished semiconductor wafer will have an uneven thickness, or worse, the semiconductor wafer may break. To improve the thickness accuracy of the back-side polishing tape, polyester films such as polyethylene terephthalate films with high thickness accuracy are preferably used as the substrate film (Patent Document 1).

[0006] Furthermore, unlike semiconductor wafers, the cutting process described above requires a smaller cutting strip than usual to cut brittle and easily cracked workpieces such as glass substrates, or hard workpieces such as sapphire glass and crystal substrates. If the cutting strip deforms significantly during cutting, the glass substrate cannot withstand the deformation and cracks, resulting in chipping (damage to the end or cut surface of the glass chip) or chip spatter, sometimes leading to quality issues with the cut glass substrate fragments. Moreover, when cutting hard sapphire glass substrates, the following issues arise: chip misalignment, chip collisions causing chip damage, chip picking errors, and decreased chip dimensional accuracy. To suppress deformation of the cutting strip, polyester films such as polyethylene terephthalate films (Patent Document 2) with high tensile modulus and relatively high hardness are preferably used as the substrate film.

[0007] However, from the perspective of users of the aforementioned adhesive tapes for workpiece processing, there is a need to minimize the variety of adhesive tapes used in workpiece processing, for example, to avoid misuse of adhesive tapes in each process or to improve production efficiency. That is, sometimes there is a requirement for adhesive tapes that can be used both as back-side grinding tapes for grinding semiconductor wafers and for extremely thinning, and as cutting tapes for cutting brittle workpieces such as glass substrates. Furthermore, from the perspective of manufacturers of adhesive tapes for workpiece processing, adhesive tapes with such functions are desired to improve production efficiency. However, for the reasons described later, simultaneously satisfying the characteristics required in each process is difficult and challenging to achieve.

[0008] To achieve a workpiece processing adhesive tape usable in either the back-side grinding process for ultra-thin semiconductor wafers or the cutting process for brittle and easily cracked glass substrates, as described above, polyester films such as polyethylene terephthalate films are preferably used as the substrate film. However, when back-side grinding tapes and cutting tapes are made by directly laminating an active energy radiation-curable adhesive layer onto a polyester film, the adhesion between the substrate film and the active energy radiation-curable adhesive layer sometimes becomes insufficient compared to conventional back-side grinding tapes and cutting tapes using a relatively soft and stretchable substrate film such as a polyolefin film. That is, the active energy radiation-curable adhesive layer has the advantage of being three-dimensionally polymerized and cured by irradiation with active energy radiation, resulting in volume shrinkage from its normal state before curing, and an increase in elastic modulus. Moreover, this phenomenon allows for easy peeling of workpieces such as semiconductor wafers and glass chips from the adhesive layer. However, the relatively soft and stretchable polyolefin film can follow the volume shrinkage of the adhesive layer to a certain extent, thus maintaining the adhesion between the active energy radiation-cured adhesive and the polyolefin film. However, the high surface smoothness of the polyolefin film, coupled with the rigidity of the polyester film, makes it difficult to follow the volume shrinkage of the adhesive layer. Therefore, the adhesion between the active energy radiation-cured adhesive layer and the polyester film sometimes decreases. As a result, for example, during peeling from a semiconductor wafer, the active energy radiation-cured adhesive may sometimes peel off from the polyester film interface, and the adhesive may transfer to the surface of the semiconductor wafer.

[0009] Patent Document 1 discloses an adhesive sheet formed by sequentially stacking a polyester substrate film, a tackifying coating containing a compound having energy-curable adhesive groups, and an energy-curable adhesive layer, with the aim of providing an adhesive sheet in which the energy-curable adhesive layer is not transferred to a wafer or the like. This tackifying coating consists of a polyester substrate film, a tackifying coating containing a compound having energy-curable adhesive groups, and an energy-curable adhesive layer. It is presumed that during the curing of the energy-curable adhesive, at least a portion of the energy-curable adhesive groups contained in the tackifying coating also polymerizes simultaneously, forming covalent bonds between a portion of the adhesive layer and the tackifying coating, thereby maintaining a tight bond between the adhesive layer and the substrate through the tackifying coating.

[0010] The adhesive sheet described in Patent Document 1 is specifically an adhesive sheet used for protecting the circuit surface of a semiconductor wafer during the grinding of the back side of the semiconductor wafer. This adhesive sheet can also be used to temporarily fix the wafer during the semiconductor wafer dicing process. However, when this adhesive sheet is used as a dicing strip for glass substrates, sapphire glass substrates, etc., there are concerns about the following problems. Typically, the dicing strip is supplied to the dicing process in a state of being adhered to a ring frame. During the dicing process, in order to cool the frictional heat generated between the high-speed rotating dicing blade and the glass substrate or sapphire glass substrate, and also to remove cutting chips, washing water is sprayed. However, it is necessary to firmly adhere the dicing strip to the ring frame in a way that can withstand the load and water pressure. Furthermore, the dicing strip may sometimes be extended as needed, so in this case, it is also necessary to firmly adhere it in a way that prevents the dicing strip from peeling off from the ring frame. In the case of a dicing strip having an active energy ray curable adhesive layer, since the adhesion strength decreases in the portion irradiated by active energy rays, the adhesive layer in the portion adhered to the ring frame (the adhesive paste portion) is usually not irradiated by active energy rays, maintaining a high adhesion strength. In this case, if the adhesive sheet described in Patent Document 1 is adhered to the ring frame, and the adhesive paste portion is not irradiated with active energy rays during the cutting process, there is a possibility that the adhesion between the tackifying coating and the energy-ray-cured adhesive layer may become insufficient. This raises concerns that the adhesive sheet may peel off from the ring frame during the cutting process, and that the adhesive layer may transfer (paste residue) to the ring frame when removing unwanted cutting strips from the ring frame after the required process. Consequently, there are concerns that the number of washes required to remove the adhesive from the ring frame increases, and the lifespan of the ring frame may also decrease. Furthermore, no such issues are described.

[0011] Patent Document 2 discloses an adhesive sheet for cutting glass substrates, which aims to provide cut fragments with excellent shape retention and minimizes the risk of fragment damage and chip scattering. The adhesive sheet has an adhesive layer with a thickness of 9 μm or less on a substrate film with a thickness of 130 μm or more and a tensile modulus of elasticity of 1 GPa or more. In an embodiment, a UV-curable adhesive sheet is illustrated, in which a polyester film (tensile modulus of elasticity 1.5 GPa) with one side corona treated is used as the substrate film, and a UV-curable adhesive layer is formed thereon.

[0012] Patent Document 2 describes an adhesive sheet for glass substrate cutting, but it does not address the issue of paste residue on the ring frame. As mentioned above, it is unclear whether the adhesive layer transfers (paste residue) to the ring frame when the unwanted cutting strip is peeled off from the ring frame after the cutting process, raising concerns about paste residue. Furthermore, when using the adhesive sheet of Patent Document 2 as a back-side polishing strip for semiconductor wafers, there are concerns about the following problems: When peeling off the back-side polishing strip after the required process, the surface has unevenness caused by circuit formation, and peeling it off from the entire surface of a large semiconductor wafer places a heavy load on the interface between the substrate film and the UV-curable adhesive layer. As the UV-curable adhesive layer peels off from the substrate film at the interface, there is a concern that the UV-curable adhesive may transfer to the semiconductor wafer surface. Moreover, the adhesive layer in Patent Document 2 is relatively thin, making it difficult to follow the circuits formed on the surface of the semiconductor wafer and insufficiently protecting them. Therefore, there is a concern that polishing water may penetrate the interface between the semiconductor wafer and the adhesive layer during polishing. Furthermore, after polishing, when irradiated with active energy rays, it is susceptible to oxygen hindrance, and the UV-curable adhesive layer cannot be fully cured. There is a concern that when the unwanted back polishing tape is peeled off from the entire semiconductor wafer, there is a concern that paste residue may remain on the periphery of the circuit surface.

[0013] As mentioned above, in order to realize a workpiece processing adhesive tape that can be used as a back-side grinding tape for grinding and thinning semiconductor wafers, and also as a cutting tape for cutting brittle workpieces such as glass substrates and hard workpieces such as sapphire glass substrates, the polyester film, which serves as the substrate film, needs to have sufficient adhesion to the active energy ray-cured adhesive layer, at least before and after irradiation. However, such a workpiece processing adhesive tape has not yet been discovered.

[0014] Existing technical documents

[0015] Patent documents

[0016] Patent Document 1: Japanese Patent Application Publication No. 2013-23665

[0017] Patent Document 2: Japanese Patent Application Publication No. 2004-10829 Summary of the Invention

[0018] The problems that the invention needs to solve

[0019] This invention was made in view of the above-mentioned problems and conditions, and its object is to provide an adhesive tape for workpiece processing. When a polyester film is used as the substrate film and an active energy radiation-curable adhesive layer is used as the adhesive layer, the adhesion between the substrate film and the active energy radiation-curable adhesive is sufficiently high both before and after active energy radiation irradiation. Even when used as a back-side polishing tape for ultra-thinning semiconductor wafers, the active energy radiation-curable adhesive layer can be peeled off without being transferred to the semiconductor wafer during peeling. Furthermore, even when used as a cutting tape for cutting brittle workpieces such as glass substrates and hard workpieces such as sapphire glass substrates, it will not peel off from the ring frame during the process, and peeling off from the ring frame can be performed without any adhesive residue. In other words, the object of this invention is to provide an adhesive tape for workpiece processing that can be used both as a back-side polishing tape for grinding and ultra-thinning semiconductor wafers and as a cutting tape for cutting brittle workpieces such as glass substrates and hard workpieces such as sapphire glass substrates.

[0020] Methods for solving problems

[0021] That is, the adhesive tape for workpiece processing of the present invention is characterized in that it sequentially comprises a substrate film formed of a polyester resin composition, an intermediate layer, and an active energy radiation-curable adhesive layer.

[0022] The aforementioned intermediate layer is formed from a resin composition containing a ternary or higher (meth)acrylate copolymer (A1) comprising methyl acrylate (MA) and methacrylic acid (MAA) as copolymer monomer components.

[0023] When the total amount of copolymer monomer components constituting the above-mentioned ternary or higher (meth)acrylate copolymer (A1) is set as 100 parts by mass, the above-mentioned methyl acrylate (MA) is included in the range of 37 parts by mass to 57 parts by mass, and the above-mentioned methacrylic acid (MAA) is included in the range of 2 parts by mass to 7 parts by mass.

[0024] The aforementioned active energy ray-curable adhesive layer is formed from an adhesive composition comprising: a (meth)acrylate copolymer (A2) with photosensitive carbon-carbon double bonds introduced into the side chains of a binary or higher (meth)acrylate copolymer base polymer (BP), and a crosslinking agent.

[0025] The aforementioned binary or higher (meth)acrylate copolymer base polymer (BP) contains 2-ethylhexyl acrylate (2-EHA) as a copolymer monomer component in a proportion of more than 50 parts by mass and less than 90 parts by mass, based on 100 parts by mass of the total amount of copolymer monomer components constituting the (meth)acrylate copolymer base polymer (BP).

[0026] In one embodiment, the aforementioned ternary or higher (meth)acrylate copolymer (A1) is a ternary or higher (meth)acrylate copolymer containing 2-ethylhexyl acrylate (2-EHA) as a copolymer monomer component other than methyl acrylate (MA) and methacrylic acid (MAA).

[0027] In one embodiment, the aforementioned ternary or higher (meth)acrylate copolymer (A1) is a ternary (meth)acrylate copolymer in which 2-ethylhexyl acrylate (2-EHA), methyl acrylate (MA), and methacrylic acid (MAA) are copolymer monomer components. When the total amount of copolymer monomer components constituting the ternary (meth)acrylate copolymer is set as 100 parts by mass, the amount of 2-ethylhexyl acrylate (2-EHA) is adjusted to be in the range of 36 to 61 parts by mass, the amount of methyl acrylate (MA) is in the range of 37 to 57 parts by mass, and the amount of methacrylic acid (MAA) is in the range of 2 to 7 parts by mass, so that the total amount of copolymer monomer components is 100 parts by mass.

[0028] In one embodiment, the glass transition temperature (Tg) of the aforementioned ternary or higher (meth)acrylate copolymer (A1) is in the range of -43°C to -18°C.

[0029] In one embodiment, the aforementioned binary or higher (meth)acrylate copolymer base polymer (BP) is a ternary (meth)acrylate copolymer in which 2-ethylhexyl acrylate (2-EHA), 2-hydroxyethyl acrylate (2-HEA), and methacrylic acid (MAA) are copolymer monomer components. When the total amount of copolymer monomer components constituting the (meth)acrylate copolymer base polymer (BP) is set to 100 parts by mass, the following parameters are adjusted to include: 2-ethylhexyl acrylate (2-EHA) in the range of 66 to 90 parts by mass; 2-hydroxyethyl acrylate (2-HEA) in the range of 9.8 to 31 parts by mass; and methacrylic acid (MAA) in the range of 0.2 to 3 parts by mass, so that the total amount of copolymer monomer components is 100 parts by mass.

[0030] In one embodiment, the glass transition temperature (Tg) of the aforementioned binary or higher (meth)acrylate copolymer base polymer (BP) is in the range of -65°C to -50°C.

[0031] In one embodiment, the thickness of the aforementioned intermediate layer is 5 μm or more.

[0032] In one embodiment, the thickness of the aforementioned active energy ray-cured adhesive layer is 5 μm or more.

[0033] In one embodiment, the sum of the thickness of the intermediate layer and the thickness of the active energy ray-cured adhesive layer is 10 μm or more.

[0034] In one embodiment, the substrate film formed from the polyester resin composition is a polyethylene terephthalate film.

[0035] In one embodiment, the adhesion of the adhesive tape used for workpiece processing to the glass plate before ultraviolet irradiation is in the range of 5.0 N / 25 mm to 25.0 N / 25 mm, and the adhesion after ultraviolet irradiation is in the range of 0.01 N / 25 mm to 0.50 N / 25 mm.

[0036] In one embodiment, the adhesion of the adhesive tape used for workpiece processing to the stainless steel sheet (SUS304BA sheet) before ultraviolet irradiation is in the range of 5.0N / 25mm to 25.0N / 25mm, and the adhesion after ultraviolet irradiation is in the range of 0.01N / 25mm to 0.50N / 25mm.

[0037] The effects of the invention

[0038] According to the present invention, an adhesive tape for workpiece processing can be provided, which, when using a film formed of a polyester resin composition as the substrate film and an active energy radiation-curable adhesive layer as the adhesive layer, exhibits sufficiently high adhesion between the substrate film and the active energy radiation-curable adhesive layer both before and after active energy radiation irradiation. Even when used as a back-side grinding tape for ultra-thinning semiconductor wafers, the active energy radiation-curable adhesive layer can be peeled off without being transferred to the semiconductor wafer during peeling. Furthermore, even when used as a cutting tape for cutting brittle workpieces such as glass substrates and hard workpieces such as sapphire glass substrates, it will not peel off from the ring frame during the process, and peeling off from the ring frame can be performed without any adhesive residue. In other words, an adhesive tape for workpiece processing can be provided that can be used as a back-side grinding tape for ultra-thinning semiconductor wafers and as a cutting tape for cutting brittle workpieces such as glass substrates. Attached Figure Description

[0039] Figure 1 This is a cross-sectional view showing an example of the structure of the adhesive tape for workpiece processing according to this embodiment.

[0040] Figure 2 This is a cross-sectional view showing an example of another configuration of the adhesive tape for workpiece processing using this embodiment.

[0041] Figure 3 This is a perspective view showing a state in which a ring frame (wafer ring) is bonded and held at the outer edge of the adhesive tape for workpiece processing in this embodiment, and a glass substrate monolithized by the cutting process is bonded and held at the center of the adhesive tape for workpiece processing.

[0042] Figure 4 This is a schematic cross-sectional view used to illustrate the method of using the adhesive tape for workpiece processing according to this embodiment in the cutting process.

[0043] Figure 5 The following is a perspective view showing the state in which the adhesive tape for workpiece processing using this embodiment is peeled off from the ring frame.

[0044] Figure 6 A schematic cross-sectional view showing the use of the adhesive tape for workpiece processing according to this embodiment in the back-side grinding process: (a) before grinding; (b) after thinning.

[0045] Figure 7 A schematic diagram illustrating the process of peeling the workpiece processing adhesive tape of the application embodiment from the surface of the thin-film semiconductor wafer starting with the peeling tape: (a) a cross-sectional view before peeling; (b) a perspective view showing the state during peeling from above. Detailed Implementation

[0046] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments.

[0047] <Composition of Adhesive Tape for Workpiece Machining>

[0048] Figure 1 This is a cross-sectional view showing an example of the configuration of the adhesive tape for workpiece machining using this embodiment. For example... Figure 1 As shown, the adhesive tape 10 for workpiece processing has a structure in which an intermediate layer 2 and an active energy radiation-curable adhesive layer 3 are sequentially provided on one side of a substrate film 1. Additionally, although not shown, a release liner (peel backing) with release properties may be provided on the surface of the active energy radiation-curable adhesive layer 3 of the adhesive tape 10 (the side opposite to the side opposite to the substrate film 1). The substrate film 1 is composed of a polyester resin composition. The intermediate layer 2 is formed of a resin composition containing a predetermined (meth)acrylate copolymer. The active energy radiation-curable adhesive layer 3 is formed of an adhesive composition containing a (meth)acrylate copolymer in which photosensitive carbon-carbon double bonds are introduced into the side chains of a predetermined (meth)acrylate copolymer base polymer (BP).

[0049] Figure 2This is a cross-sectional view illustrating an example of another configuration of the adhesive tape for workpiece machining using this embodiment. For example... Figure 2 As shown, the adhesive tape 10 for workpiece processing has a structure in which an intermediate layer 2 and an active energy radiation-curable adhesive layer 3 are sequentially provided on one side of the substrate film 1, but... Figure 1 The substrate film 1 is composed of a single layer, in contrast, Figure 2 The substrate film 1 is composed of a resin layer 1a made of a polyester-based resin composition and a resin layer 1b made of, for example, a resin composition other than polyester. Other configurations are similar to those described above. Figure 1 same.

[0050] Such a workpiece processing adhesive tape 10 can be used, for example, in cutting processes where hard workpieces such as brittle and easily cracked glass substrates, crystal substrates, or sapphire glass substrates that have undergone various circuit formations or surface treatments are cut into fragments. Furthermore, it can also be used in the cutting processes of conventional silicon semiconductor wafers, silicon carbide, gallium arsenide, gallium phosphide, gallium nitride, and other compound semiconductor wafers. That is, as a cutting tape, specifically, such as... Figure 3 and Figure 4 It is used as shown. First, after attaching the active energy radiation-curable adhesive layer 3 to the outer edge of the workpiece processing adhesive tape 10, which is punched into a circle, a ring frame 20 made of SUS is attached. Then, for example, a glass substrate 30 is attached to the active energy radiation-curable adhesive layer 3 at the center of the workpiece processing adhesive tape 10, with the side without circuit formation in contact with the active energy radiation-curable adhesive layer 3. Here, the thickness of the workpiece, such as a glass substrate, crystal substrate, or sapphire glass substrate, is, for example, in the range of 50 μm to 5000 μm. Next, the glass substrate 30 is cut into a glass chip 30a of a predetermined size by a high-speed rotating cutting scraper 40 while spraying washing cooling water. Here, the area of ​​the chip's planar surface is, for example, 1 × 10⁻⁶. -6 mm 2 ~9mm 2 Within the range of cutting, after cutting, the portion of the active energy ray-curable adhesive layer 3 to which the workpiece is attached is irradiated with active energy rays such as ultraviolet (UV) from the substrate film 1 side of the workpiece processing adhesive tape 10, thereby reducing the adhesion of the active energy ray-curable adhesive layer 3 and picking up (peeling) the glass chip 30a from the active energy ray-curable adhesive layer 3 of the workpiece processing adhesive tape 10. This allows for the acquisition of a high-quality glass chip 30a with suppressed defects.

[0051] Figure 5The following is a perspective view showing the state after all glass chips 30a have been picked up, with the unwanted workpiece processing adhesive tape 10 peeled off from the ring frame 20. The workpiece processing adhesive tape is peeled off from the ring frame manually, but sometimes a peeling device is used. The ring frame 20 with the workpiece processing adhesive tape 10 peeled off is washed and reused as needed. However, if the adhesive layer of the active energy ray-cured adhesive layer peels off from the substrate film 1 and transfers (paste residue) to the surface of the ring frame 10 during the peeling of the workpiece processing adhesive tape 10, washing takes time, reducing operational efficiency.

[0052] Furthermore, the workpiece processing adhesive tape 10 with such a configuration can also be used in the back grinding process for grinding semiconductor wafers such as silicon wafers that have undergone various circuit formations or other surface processing to extremely thin thicknesses. Specifically, as a back grinding tape, such as... Figure 6 Use it as shown. First, as shown... Figure 6 As shown in (a), on the side of the semiconductor wafer 50 where the circuit 51 is formed, with a thickness of, for example, 775 μm, the side of the active energy radiation-curable adhesive layer 3 of the workpiece processing adhesive tape 10 is attached. Next, from the side opposite to where the circuit is formed, the semiconductor wafer 50 is ground to a predetermined thickness using a grinding machine (grinding wheel) 60 while being supplied with grinding water. At this time, the semiconductor wafer 50 is held on a holding table (not shown) by means of the workpiece processing adhesive tape 10. Figure 6 (b) This indicates that the grinding of the semiconductor wafer 50 has ended, and the semiconductor wafer 50' has been thinned to a predetermined thickness, and is held on the workpiece processing adhesive tape 10. Here, the thickness of the thinned semiconductor wafer 50' is, for example, in the range of 20 μm to 100 μm.

[0053] After grinding, firstly, the portion of the active energy radiation-curable adhesive layer 3 to which the thin-film semiconductor wafer 50' is bonded is irradiated with active energy radiation such as ultraviolet (UV) from the substrate film 1 side of the adhesive tape 10 for workpiece processing, thereby curing the active energy radiation-curable adhesive layer 3 and reducing the adhesion. Next, as... Figure 7As shown in (a), after attaching the SUS-made ring frame 20 to the outer edge of the separately prepared circular cutting strip 11, an active energy radiation-curable adhesive layer 3 is applied to the active energy radiation-curable adhesive layer 3 at the center of the cutting strip 11, such that the polished surface side of the aforementioned thin-film semiconductor wafer 50' is in contact with the active energy radiation-curable adhesive layer 3. Next, a strip-shaped release strip 12 (e.g., 50mm wide × 60mm long) is applied to the back of the substrate film 1 of the workpiece processing adhesive strip 10 by pressing or hot pressing. The workpiece processing adhesive strip 10 and the thin-film semiconductor wafer 50' are approximately the same shape, and there is no starting point for peeling, so the strip-shaped release strip 12 is firmly fixed to serve as the starting point for peeling. Moreover, before the cutting process in the next step, as Figure 7 As shown in (b), the workpiece processing adhesive tape 10 is peeled off from the surface of the thin-film semiconductor wafer 50', which has circuitry 51 on its surface, starting from the peeling tape 12. The peeling is performed manually or using a peeling device. At this time, the thin-film semiconductor wafer 50' is adsorbed and held on a holding table (not shown) by the cutting tape 11. As a result, a thin-film semiconductor wafer 50' with high thickness accuracy and no surface contamination such as paste residue can be obtained.

[0054] <Adhesive tape for workpiece machining>

[0055] (Substrate film)

[0056] The substrate film 1 in the adhesive tape 10 for workpiece processing according to this embodiment will be described below. From the viewpoint of tensile strength and rigidity, a film formed from a polyester resin composition is used as the substrate film 1. The film formed from the polyester resin composition is a film in which polyester is the main component. Preferably, the polyester contains at least 70% by mass relative to the total resin component (components other than resin) in the resin composition constituting the substrate film 1, and more preferably at least 80% by mass with a composition similar to that of the polyester monomer. There is no particular upper limit, but it is 100% by mass or less.

[0057] Examples of polyesters that serve as the main component of the substrate film 1 include, for instance, crystalline linear saturated polyesters obtained by polycondensation of aromatic diacids or their ester derivatives with glycols or their ester derivatives. Specific examples of polyesters include homopolymers such as polyethylene terephthalate, polyethylene isophthalate, polyethylene terephthalate, and polyethylene 2,6-naphthalate, as well as copolyesters in which these resins are the main components. Furthermore, the aforementioned polyesters can also be used by blending the homopolymers together or by blending the homopolymers with the copolyesters. Among these polyesters, polyethylene terephthalate is particularly preferred because it is readily available and readily produces substrate film 1 with good mechanical strength (tensile strength, rigidity, etc.), transparency, heat resistance, and high thickness accuracy.

[0058] Examples of aromatic dicarboxylic acids in the aforementioned homopolymer include terephthalic acid and 2,6-naphthalenedicarboxylic acid, while examples of diols include ethylene glycol, diethylene glycol, and 1,4-cyclohexanediethanol. The total amount of repeating units in the aforementioned homopolymer, i.e., the main repeating units comprising the aromatic dicarboxylic acid and diol components, is preferably 80 mol% or more, more preferably 90 mol% or more, and even more preferably 95 mol% or more.

[0059] Furthermore, the aromatic dicarboxylic acids used as the aforementioned copolyesters include, for example, phthalic acid, isophthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, and p-hydroxybenzoic acid, which can be used alone or in combination.

[0060] Examples of the diols used as the copolyesters mentioned above include ethylene glycol, diethylene glycol, 1,4-butanediol, propylene glycol, neopentyl glycol, etc., which can be used alone or in combination of two or more.

[0061] The mass ratio of the copolymer component in the aforementioned copolyester is preferably less than 20% by mass. When the mass ratio is less than 20% by mass, the mechanical strength, transparency, heat resistance, and thickness accuracy of the substrate film 1 can be maintained.

[0062] The polyester is preferably contained in a proportion of 70% by mass or more relative to the total resin composition constituting the substrate film 1 (the components of the resin composition excluding additives other than resin). However, the resin composition may contain, as needed, other resins such as aromatic ether compounds, ethylene-vinyl acetate copolymers, ethylene-(meth)acrylic acid copolymers, polyolefin elastomers, polyamide elastomers, polycarbonate resins, and ionomer resins. From the viewpoint of maintaining the mechanical strength, transparency, heat resistance, and thickness accuracy of the substrate film 1, the other resins are preferably contained in a proportion of 30% by mass or less relative to the total resin composition constituting the substrate film 1 (the components of the resin composition excluding additives other than resin), and more preferably in a proportion of 20% by mass or less.

[0063] Furthermore, other types of polyester used as the main component of the aforementioned substrate film 1 can be exemplified by so-called polyester-polyether block thermoplastic elastomers, in which aromatic polyesters are used for the hard segments and polyethers are used for the soft segments; and so-called polyester-polyester block thermoplastic elastomers, in which aromatic polyesters are used for the hard segments and aliphatic polyesters are used for the soft segments. Specifically, as a polyester-polyether block thermoplastic elastomer, examples include thermoplastic polyester elastomers in which polybutylene terephthalate is used for the hard segments and polytetramethylene ether glycol is used for the soft segments; and as a polyester-polyester block thermoplastic elastomer, examples include thermoplastic polyester elastomers in which polybutylene terephthalate is used for the hard segments and polylactone is used for the soft segments.

[0064] The polyester resin composition constituting the substrate film 1 is preferably formulated with particles primarily intended to impart slip properties to the substrate film 1. The type of particles used is not particularly limited as long as they impart slip properties. Specific examples include inorganic particles such as silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, alumina, and titanium dioxide; and heat-resistant organic particles such as thermosetting urea resin, thermosetting phenolic resin, thermosetting epoxy resin, and benzoguanamine resin. The shape of the particles used is not particularly limited; spherical, blocky, rod-shaped, or flat particles can be used. Two or more types of these particles can be used in combination as needed.

[0065] Furthermore, the average particle size of the aforementioned particles is typically 0.01 μm to 3 μm, preferably in the range of 0.01 μm to 1 μm. When the average particle size is within this range, the substrate film 1 can be imparted with appropriate slipperiness and smoothness. Furthermore, the content of the aforementioned particles relative to the total resin composition constituting the substrate film 1 is typically 0.001% by mass to 5% by mass, preferably in the range of 0.005% by mass to 3% by mass. When the particle content is within this range, appropriate slipperiness and smoothness can be imparted.

[0066] In addition, to the extent that the effects of the present invention are not impaired, the above-mentioned polyester resin composition may, as needed, add conventionally known catalysts, antioxidants, antistatic agents, heat stabilizers, lubricants, dyes, pigments, etc., in addition to the particles mentioned above.

[0067] As the substrate film 1 formed from the above-mentioned polyester resin composition, any one of unstretched polyester film, uniaxially stretched polyester film, and biaxially stretched polyester film can be used, with biaxially stretched polyester film being preferred. Specifically, biaxially stretched polyethylene terephthalate film is preferred.

[0068] The aforementioned substrate film 1 can be a single layer or a stack of two or more layers. From the viewpoint of process simplification and thickness accuracy, the substrate film 1 is preferably... Figure 1 The single-layer structure is shown. In the case where the substrate film 1 is composed of two layers, for example... Figure 2 As shown, the substrate film 1 is constructed by a laminate comprising a resin layer 1a made of a polyester-based resin composition and a resin layer 1b made of, for example, a resin composition other than polyester. Here, the resin layer 1a is the layer directly in contact with the intermediate layer 2. When the substrate film 1 is constructed by a laminate, at least the resin layer 1a directly in contact with the intermediate layer 2 is made of the aforementioned polyester-based resin composition. The resin layer 1b can be a layer made of a resin composition other than polyester, or it can be a layer made of a polyester-based resin composition. Furthermore, as the resin component of the resin composition other than polyester, the same resin as those exemplified above as other resins besides polyester can be used.

[0069] The total thickness of the substrate film 1 is not particularly limited as long as it falls within the range suitable for film fabrication. It is typically 12 μm to 250 μm, preferably 25 μm to 188 μm, and more preferably 38 μm to 125 μm. If the total thickness of the substrate film 1 is less than 12 μm, the operability of the adhesive tape 10 during manufacturing and use in the process deteriorates, resulting in concerns about poor quality of the processed workpieces (glass chip 30a, thin-film semiconductor wafer 50', etc.). On the other hand, if the total thickness exceeds 250 μm, the rigidity becomes too high, also resulting in concerns about poor quality of the processed workpieces.

[0070] When the substrate film 1 is composed of two or more layers, the total thickness of the layers made of the polyester resin composition depends on the overall thickness of the substrate film 1, and therefore cannot be generalized. For example, it is preferable to set the thickness to be 50% or more of the overall thickness of the substrate film 1. When the ratio is 50%, the quality of the processed workpiece becomes good.

[0071] (Middle layer)

[0072] The intermediate layer 2 of the adhesive tape 10 for workpiece processing in this embodiment will be described below. The intermediate layer 2 is formed of a resin composition containing a ternary or higher (meth)acrylate copolymer (A1) (hereinafter sometimes simply referred to as "(meth)acrylate copolymer (A1)") comprising methyl acrylate (MA) and methacrylic acid (MAA) as copolymer monomer components. When the total amount of copolymer monomer components constituting the ternary or higher (meth)acrylate copolymer (A1) is set as 100 parts by mass, the methyl acrylate (MA) is contained in a range of at least 37 parts by mass and up to 57 parts by mass, and the methacrylic acid (MAA) is contained in a range of 2 parts by mass and up to 7 parts by mass. The content ratio of the ternary or higher (meth)acrylate copolymer (A) relative to the total amount of the resin composition is preferably 90% by mass or more, more preferably 95% by mass or more.

[0073] [(Meth)acrylate copolymer (A1)]

[0074] In the aforementioned ternary or higher (meth)acrylate copolymer (A1), by including methyl acrylate (MA) and methacrylic acid (MAA) as copolymer monomer components in amounts within the aforementioned range, the adhesion between the substrate film 1 and the intermediate layer 2, as well as the adhesion between the intermediate layer 2 and the reactive energy radiation-cured adhesive layer 3 (described later), becomes excellent. Even after irradiating the adhesive tape 10 for workpiece processing with reactive energy radiation, their adhesion can be sufficiently maintained at a level that does not become an obstacle during workpiece processing. As a result, the quality of the processed workpiece becomes excellent.

[0075] Furthermore, in the aforementioned ternary or higher (meth)acrylate copolymers (A1), when the total amount of copolymer monomer components constituting the aforementioned (meth)acrylate copolymers (A1) is set as 100 parts by mass, copolymer monomer components other than the aforementioned methyl acrylate (MA) and methacrylic acid (MAA) are included in the range of 36 parts by mass to 61 parts by mass.

[0076] As copolymer monomer components other than methyl acrylate (MA) and methacrylic acid (MAA) mentioned above, there are no particular limitations as long as the monomer is capable of copolymerizing with methyl acrylate (MA) and methacrylic acid (MAA). Examples include (meth)acrylate monomers having straight-chain or branched alkyl groups with 2 to 20 carbon atoms, (meth)acrylate cycloalkyl ester monomers, monomers containing functional groups, vinyl acetate, styrene, acrylonitrile, N-methylvinylpyrrolidone, etc. These monomers can be used alone or in combination.

[0077] Examples of (meth)acrylate monomers having alkyl groups having 2 to 20 carbon atoms in a straight or branched manner include ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecanyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, hexadecyl (meth)acrylate, octadecyl (meth)acrylate, octadecyl (meth)acrylate, and eicosyl (meth)acrylate. Among these, from the viewpoints of versatility, adhesion between the intermediate layer 2 and the active energy ray-cured adhesive layer 3, and adhesion between the intermediate layer 2 and the substrate film 1, it is preferable to use (meth)acrylate monomers having straight-chain or branched alkyl groups with 2 to 8 carbon atoms. Specifically, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc. are preferred.

[0078] Examples of the aforementioned cycloalkyl methacrylate monomers include cyclopentyl methacrylate, cyclohexyl methacrylate, and dicyclopentyl methacrylate.

[0079] Specifically, examples of monomers containing functional groups include acrylic acid, carboxyethyl methacrylate, carboxypentyl methacrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; anhydride monomers such as maleic anhydride and itaconic anhydride; and hydroxyl monomers such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 6-hydroxyhexyl methacrylate, 8-hydroxyoctyl methacrylate, 10-hydroxydecyl methacrylate, 12-hydroxylaurate methacrylate, and (4-hydroxymethylcyclohexyl)methacrylate. The monomers include: styrene sulfonic acid, allyl sulfonic acid, 2-(meth)acrylamide-2-methylpropane sulfonic acid, (meth)acrylamide propane sulfonic acid, (meth)acrylate sulfonylpropyl ester, (meth)acryloyloxynaphthalene sulfonic acid, and other monomers containing sulfonic acid groups; 2-hydroxyethylacryloyl phosphate ester, and other monomers containing phosphate groups; (meth)acrylate glycidyl ester, and other monomers containing glycidyl groups; (meth)acrylamide, (meth)acrylate N-hydroxymethylamide, and other monomers containing amide groups; (meth)acrylate dimethylaminoethyl ester, (meth)acrylate tert-butylaminoethyl ester, and (meth)acrylate alkylaminoalkyl ester, and other monomers containing amino groups. Among these, considering versatility, adhesion between the intermediate layer 2 and the active energy ray-cured adhesive layer 3, adhesion between the intermediate layer 2 and the substrate film 1, and improved cohesion of the intermediate layer 2, acrylic acid, (meth)acrylate 2-hydroxyethyl ester, (meth)acrylate 4-hydroxybutyl ester, (meth)acrylamide, etc., are preferred.

[0080] As the ternary or higher (meth)acrylate copolymer (A1) described above in this invention, it is preferable to use a ternary or higher (meth)acrylate copolymer that, in addition to the copolymer monomer components of the predetermined methyl acrylate (MA) and methacrylic acid (MAA) described above, also contains 2-ethylhexyl acrylate (2-EHA) and / or n-butyl acrylate (n-BA) as copolymer monomer components. Specific examples of such ternary or higher (meth)acrylate copolymers include:

[0081] (1) A terpolymer of 2-ethylhexyl acrylate (2-EHA), methyl acrylate (MA) and methacrylic acid (MAA);

[0082] (2) A terpolymer of n-butyl acrylate (n-BA), methyl acrylate (MA) and methacrylic acid (MAA);

[0083] (3) A quaternary copolymer of 2-ethylhexyl acrylate (2-EHA), n-butyl acrylate (n-BA), methyl acrylate (MA) and methacrylic acid (MAA);

[0084] (4) A quaternary copolymer of 2-ethylhexyl acrylate (2-EHA), methyl acrylate (MA), 2-hydroxyethyl acrylate (2-HEA) and methacrylic acid (MAA);

[0085] (5) A quaternary copolymer of 2-ethylhexyl acrylate (2-EHA), methyl acrylate (MA), ethyl acrylate (EA) and methacrylic acid (MAA);

[0086] (6) Tetrapolymers of 2-ethylhexyl acrylate (2-EHA), methyl acrylate (MA), acrylic acid (AA) and methacrylic acid (MAA), etc.

[0087] From a generality perspective, ternary (meth)acrylate copolymers with 2-ethylhexyl acrylate (2-EHA), methyl acrylate (MA), and methacrylic acid (MAA) as copolymer monomers are suitable, as are ternary copolymers with n-butyl acrylate (n-BA), methyl acrylate (MA), and methacrylic acid (MAA). However, ternary (meth)acrylate copolymers with 2-ethylhexyl acrylate (2-EHA), methyl acrylate (MA), and methacrylic acid (MAA) as copolymer monomers are more suitable.

[0088] As the aforementioned ternary or higher (meth)acrylate copolymer (A1), when using the aforementioned ternary (meth)acrylate copolymer of 2-ethylhexyl acrylate (2-EHA), methyl acrylate (MA), and methacrylic acid (MAA), each monomer component is preferably included in a range of 36 to 61 parts by mass, methyl acrylate (MA) in a range of 37 to 57 parts by mass, and methacrylic acid (MAA) in a range of 2 to 7 parts by mass, so that the total amount of copolymer monomer components is 100 parts by mass.

[0089] The aforementioned ternary or higher (meth)acrylate copolymer (A1) is obtained as follows: methyl acrylate (MA) monomer, methacrylic acid (MAA) monomer, and one or more monomers selected from the aforementioned monomers other than these two monomers are combined as copolymer monomer components in a predetermined amount, and the resulting mixture is polymerized. Polymerization can be carried out by any of the following methods: solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, etc. From the viewpoint of improving the cohesiveness of the intermediate layer 2, the weight-average molecular weight (Mw) of the aforementioned ternary or higher (meth)acrylate copolymer (A1) is preferably 100,000 or more, and from the viewpoint of suitable coating of the resin composition solution of the intermediate layer 2, it is preferably 1,500,000 or less. That is, the aforementioned weight-average molecular weight (Mw) is preferably in the range of 100,000 to 1,500,000, more preferably in the range of 300,000 to 1,000,000. Here, the weight-average molecular weight (Mw) is the weight-average molecular weight converted from standard polystyrene obtained using gel permeation chromatography (GPC).

[0090] Furthermore, the glass transition temperature (Tg) of the aforementioned ternary or higher (meth)acrylate copolymer (A1) is not particularly limited as long as it does not impair the effects of the present invention. From the viewpoints of the adhesion between the aforementioned substrate film 1 and the aforementioned intermediate layer 2, the adhesion between the aforementioned intermediate layer 2 and the reactive energy radiation-cured adhesive layer 3 described later, and the processing quality of the workpiece, it is preferably in the range of -43°C to -18°C, and more preferably in the range of -43°C to -24°C. Here, the glass transition temperature (Tg) is a theoretical value calculated by the Fox formula shown in the following general formula (1) based on the composition of the monomer components constituting the aforementioned ternary or higher (meth)acrylate copolymer (A1).

[0091] [Number 1]

[0092] 1 / Tg = W1 / Tg1 + W2 / Tg2 + ... + W n / Tg n (1)

[0093] In the above general formula (1), Tg is the glass transition temperature (unit: K) of ternary or higher (meth)acrylate copolymers (Al). i (i = 1, 2, ..., n) represents the glass transition temperature (in K) of monomer i when it forms a homopolymer, W i (i = 1, 2, ..., n) represents the mass fraction of monomer i in all monomer components.

[0094] The glass transition temperature (Tg) of homopolymers can be found in publications such as the "Polymer Handbook" (edited by J. Brandrup and E. Himmergut, Interscience Publishers).

[0095] If the glass transition temperature (Tg) is within the aforementioned range, for example, when cutting a brittle and easily cracked workpiece such as a glass substrate 30 using a rotating cutting scraper 40, the workpiece on the adhesive layer 3 is well held and fixed, further suppressing shaking, thus suppressing defects, chip size deviation, and positional deviation. Furthermore, it can suppress paste residue on the ring frame 20 and the transfer of the adhesive layer when peeling the workpiece processing adhesive tape 10 from the ring frame 20 after cutting. Moreover, for example, when grinding the semiconductor wafer 50, it can appropriately follow the height differences of the circuits 51, electrodes, etc., on the surface of the semiconductor wafer 50, thus suppressing paste residue at the periphery of the circuit surface when peeling the workpiece processing adhesive tape 10 from the thin-film semiconductor wafer 50'; it can ensure the uniformity of the thickness of the thin-film semiconductor wafer 50'. Furthermore, it can also suppress the transfer of the adhesive layer 3 to the thin-film semiconductor wafer 50'.

[0096] Furthermore, the acid value of the aforementioned ternary or higher (meth)acrylate copolymer (Al) is not particularly limited as long as it is within a range that does not impair the effects of the present invention. From the viewpoint of improving the adhesion between the substrate film 1 and the intermediate layer 2, the adhesion between the intermediate layer 2 and the active energy ray-cured adhesive layer 3 (described later), and the cohesiveness of the intermediate layer 2, it is preferably 13.0 mg KOH / g or higher. From the viewpoint of inhibiting gelation during the polymerization of the copolymer (Al) and the rigidity of the intermediate layer 2 (the reduction in adhesion and the reduction in the followability of height differences before irradiation of the adhesive tape 10 for workpiece processing due to increased rigidity), it is preferably 50.7 mg KOH / g or lower. That is, the aforementioned acid value is preferably in the range of 13.0 mg KOH / g or higher and 50.7 mg KOH / g or lower.

[0097] Furthermore, the hydroxyl value of the ternary or higher (meth)acrylate copolymer (A1) is not particularly limited as long as it is within a range that does not impair the effect of the present invention. From the viewpoint of the adhesion between the substrate film 1 and the intermediate layer 2, the adhesion between the intermediate layer 2 and the active energy ray-cured adhesive layer 3 described later, and the rigidity of the intermediate layer 2 (the reduction in adhesion before irradiation by the active energy ray of the adhesive tape 10 for workpiece processing due to increased rigidity, and the reduction in the followability of height difference), it is preferably in the range of 0 mg KOH / g to 96.6 mg KOH / g.

[0098] [Cross-linking agent]

[0099] To improve the cohesiveness of the intermediate layer 2, the resin composition constituting the intermediate layer 2 preferably contains a crosslinking agent capable of reacting with the functional groups present in the ternary or higher (meth)acrylate copolymer (A1). There are no particular limitations on such a crosslinking agent; known crosslinking agents having functional groups capable of reacting with the functional groups present in the ternary or higher (meth)acrylate copolymer (A1), i.e., carboxyl groups, or hydroxyl groups, glycidyl groups, etc., introduced as needed, can be used. Specifically, examples include polyisocyanate-based crosslinking agents, epoxy-based crosslinking agents, metal chelate-based crosslinking agents, aziridine-based crosslinking agents, melamine resin-based crosslinking agents, urea resin-based crosslinking agents, anhydride compound-based crosslinking agents, polyamine-based crosslinking agents, and polymer-based crosslinking agents containing carboxyl groups. Among these, from the viewpoint of reactivity and versatility, polyisocyanate-based crosslinking agents or epoxy-based crosslinking agents are preferred. These crosslinking agents can be used alone or in combination. The amount of crosslinking agent is preferably 0.01 to 10.0 parts by mass relative to 100 parts by mass of the solid content of the above-mentioned ternary or higher (meth)acrylate copolymer (A1), and more preferably 0.1 to 5.0 parts by mass.

[0100] Examples of polyisocyanate-based crosslinking agents include, for instance, polyisocyanate compounds having an isocyanurate ring, adduct polyisocyanate compounds formed by reacting trimethylolpropane with hexamethylene diisocyanate, adduct polyisocyanate compounds formed by reacting trimethylolpropane with toluene diisocyanate, adduct polyisocyanate compounds formed by reacting trimethylolpropane with phenylenediamine diisocyanate, and adduct polyisocyanate compounds formed by reacting trimethylolpropane with isophorone diisocyanate. One or more of these agents can be used in combination.

[0101] Examples of epoxy-based crosslinking agents include, for instance, bisphenol A-epiglohydrin type epoxy resins, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl erythritol, diglycerol polyglycidyl ether, 1,3'-bis(N,N-diglycidylaminomethyl)cyclohexane, and N,N,N',N'-tetraglycidyl-m-phenylenediamine. One or more of these agents can be used in combination.

[0102] [thickness]

[0103] The thickness of the intermediate layer 2 is not particularly limited as long as it does not impair the effects of the present invention. It can be appropriately adjusted according to the processing of the workpiece. From the viewpoint of the adhesion between the substrate film 1 and the intermediate layer 2, and the adhesion between the intermediate layer 2 and the active energy ray curable adhesive layer 3 described later, it is preferably 5 μm or more. From the viewpoint of proper coating and drying of the resin composition solution of the intermediate layer 2, it is preferably 150 μm or less. That is, the thickness of the intermediate layer 2 is preferably in the range of 5 μm or more and 150 μm or less, and more preferably in the range of 5 μm or more and 100 μm or less.

[0104] (Active energy radiation cured adhesive layer)

[0105] The following describes the active energy ray-curable adhesive layer 3 (hereinafter, sometimes simply referred to as "adhesive layer 3") in the adhesive tape 10 for workpiece processing according to this embodiment. The active energy ray-curable adhesive layer 3 is formed from an adhesive composition comprising a (meth)acrylate copolymer (A2) (hereinafter, sometimes simply referred to as "(meth)acrylate copolymer (A2)") containing photosensitive carbon-carbon double bonds introduced into the side chains of a (meth)acrylate copolymer base polymer (BP) of two or more elements, and a crosslinking agent. The content of the (meth)acrylate copolymer (A2) relative to the total amount of the adhesive composition is preferably 90% by mass or more, more preferably 95% by mass or more.

[0106] There are no particular limitations on the method for manufacturing the (meth)acrylate copolymer (A2) with photosensitive carbon-carbon double bonds introduced into the side chain. A common method is to copolymerize a copolymer monomer component containing a (meth)acrylate monomer and a monomer containing a functional group to obtain a binary or higher (meth)acrylate copolymer base polymer, and then perform an addition reaction on a compound having a functional group and a carbon-carbon double bond that can undergo an addition reaction with the functional group of the base polymer (an active energy ray reactive compound).

[0107] [(Meth)acrylate copolymer base polymer (BP)]

[0108] In the binary or higher (meth)acrylate copolymer base polymer (BP) of this embodiment (hereinafter, sometimes simply referred to as base polymer (BP), when the total amount of copolymer monomer components constituting the (meth)acrylate copolymer base polymer (BP) is set to 100 parts by mass, 2-ethylhexyl acrylate (2-EHA) is included as a copolymer monomer component in a proportion of more than 50 parts by mass and less than 90 parts by mass.

[0109] In the aforementioned binary or higher (meth)acrylate copolymer base polymer (BP), as described above, by including 2-ethylhexyl acrylate (2-EHA) as a copolymer monomer component in a proportion exceeding 50 parts by mass and less than 90 parts by mass of 100 parts by mass, based on the total amount of copolymer monomer components constituting the base polymer (BP), the adhesion between the intermediate layer 2 and the adhesive layer 3 can be improved, and this adhesion can be sufficiently maintained at a level that does not become an obstacle during workpiece processing, both before and after irradiation with the active energy rays of the adhesive tape 10 for workpiece processing. On the other hand, it is possible to impart the high adhesion required to maintain the workpiece during workpiece processing before irradiation with the active energy rays of the adhesive tape 10 for workpiece processing, and the cohesive force of the adhesive layer 3 required to suppress paste residue on the workpiece when the adhesive tape 10 for workpiece processing is peeled off from the processed workpiece. As a result, the quality of the processed workpiece can be improved.

[0110] Furthermore, in the aforementioned binary or higher (meth)acrylate copolymer base polymer (BP), when the total amount of copolymer monomer components constituting the base polymer (BP) is set to 100 parts by mass, it is preferable that, as copolymer monomer components other than the aforementioned 2-ethylhexyl acrylate (2-EHA), monomers containing functional groups are included in a proportion of 10 to 34 parts by mass, and other copolymer monomers (excluding 2-EHA and monomers containing functional groups) are included in a proportion of 0 to 40 parts by mass, so that the total amount of copolymer monomer components is adjusted to 100 parts by mass.

[0111] Examples of monomers containing functional groups include those containing carboxyl groups, anhydride monomers, hydroxyl monomers, sulfonic acid monomers, glycidyl monomers, amide monomers, and amino monomers, which are the same as the monomer components of the ternary or higher (meth)acrylate copolymer (A1) used as the intermediate layer 2 described above. One or more of these monomers can be used in combination. Among these, monomers containing hydroxyl groups are preferred from the viewpoint of ease of addition reaction with the reactive compounds described later. Specifically, examples of hydroxyl monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylaurate (meth)acrylate, and methyl (4-hydroxymethylcyclohexyl)methacrylate. Of these, from a general viewpoint, 2-hydroxyethyl methacrylate and 4-hydroxybutyl methacrylate are preferred.

[0112] The purpose of copolymerizing the aforementioned monomers containing functional groups is as follows: First, for the aforementioned binary or higher (meth)acrylate copolymer base polymer (BP), the functional group serves as an addition reaction site for introducing the reactive carbon-carbon double bond of the active energy ray (AE) reaction via an addition reaction; second, as a crosslinking reaction site for reacting with the crosslinking agent described later to increase the molecular weight of the aforementioned (meth)acrylate copolymer (A2); third, as an active point (polar point) for improving the initial adhesion between the crosslinked AE-cured adhesive layer 3 and the workpiece; fourth, as an active point (polar point) for improving the adhesion between the aforementioned intermediate layer 2 and the aforementioned AE-cured adhesive layer 3. As a result, the content ratio of the aforementioned monomers containing functional groups, as described above, is preferably adjusted to a range of 10% by mass to 34% by mass relative to the total amount of copolymer monomer components constituting the aforementioned binary or higher (meth)acrylate copolymer base polymer (BP).

[0113] Furthermore, in the aforementioned binary or higher (meth)acrylate copolymer base polymers (BP), from the viewpoints of improving cohesiveness, adjusting glass transition temperature (Tg), and improving heat resistance, other copolymer monomers (excluding 2-EHA and monomers containing functional groups) can be included as copolymer monomer components in a proportion of less than 40% by mass relative to the total amount of copolymer monomer components constituting the aforementioned (meth)acrylate copolymer base polymer (BP), as needed. As for the aforementioned other copolymer monomer components, there are no particular limitations as long as they are monomers capable of copolymerizing with the aforementioned 2-ethylhexyl acrylate (2-EHA) and the aforementioned monomers containing functional groups. Examples include, for instance, (meth)acrylate monomers having linear or branched alkyl groups with 1 to 20 carbon atoms, (meth)acrylate cycloalkyl ester monomers, vinyl acetate, styrene, acrylonitrile, N-methylvinylpyrrolidone, etc. These monomers can be used alone or in combination of two or more.

[0114] As for the (meth)acrylate monomers having a linear or branched alkyl group having 1 to 20 carbon atoms, specifically, in addition to methyl methacrylate having a linear alkyl group having 1 carbon atom, examples can be given of monomer components that are the same as the monomer components exemplified in the copolymer monomer components of the ternary or higher (meth)acrylate copolymer (A1) described above as the intermediate layer 2, namely, (meth)acrylate monomers having a linear or branched alkyl group having 2 to 20 carbon atoms. Among these, from a general viewpoint, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, dodecyl methacrylate, tridecyl methacrylate, stearyl methacrylate, etc., are preferred.

[0115] Examples of the aforementioned cycloalkyl methacrylate monomers include cyclopentyl methacrylate, cyclohexyl methacrylate, and dicyclopentyl methacrylate.

[0116] As the base polymer (BP) of the binary or higher (meth)acrylate copolymer in this embodiment, a binary or higher (meth)acrylate copolymer comprising 2-ethylhexyl acrylate (2-EHA) and 2-hydroxyethyl acrylate (2-HEA) as copolymer monomer components is preferably used. Specific examples of such binary or higher (meth)acrylate copolymers include:

[0117] (1) A binary copolymer of 2-ethylhexyl acrylate (2-EHA) and 2-hydroxyethyl acrylate (2-HEA);

[0118] (2) A terpolymer of 2-ethylhexyl acrylate (2-EHA), 2-hydroxyethyl acrylate (2-HEA), and methacrylic acid (MAA);

[0119] (3) A quaternary copolymer of 2-ethylhexyl acrylate (2-EHA), n-butyl acrylate (n-BA), 2-hydroxyethyl acrylate (2-HEA) and methacrylic acid (MAA);

[0120] (4) Quaternary copolymers of 2-ethylhexyl acrylate (2-EHA), 2-hydroxyethyl acrylate (2-HEA), methyl methacrylate (MMA) and methacrylic acid (MAA), etc.

[0121] From a generality perspective, binary (meth)acrylate copolymers with 2-ethylhexyl acrylate (2-EHA) and 2-hydroxyethyl acrylate (2-HEA) as copolymer monomers are suitable, as are ternary (meth)acrylate copolymers with 2-ethylhexyl acrylate (2-EHA), 2-hydroxyethyl acrylate (2-HEA), and methacrylic acid (MAA) as copolymer monomers. Ternary (meth)acrylate copolymers with 2-ethylhexyl acrylate (2-EHA), 2-hydroxyethyl acrylate (2-HEA), and methacrylic acid (MAA) as copolymer monomers are even more suitable.

[0122] When using a binary (meth)acrylate copolymer of 2-ethylhexyl acrylate (2-EHA) and 2-hydroxyethyl acrylate (2-HEA) as the base polymer (BP) for the aforementioned binary or higher (meth)acrylate copolymers, for each monomer component, it is preferable to include 2-ethylhexyl acrylate (2-EHA) in the range of 66 to 90 parts by mass and 2-hydroxyethyl acrylate (2-HEA) in the range of 10 to 34 parts by mass, with the total amount of copolymer monomer components constituting the binary (meth)acrylate copolymer set as 100 parts by mass, so that the total amount of copolymer monomer components is adjusted to include 100 parts by mass.

[0123] Furthermore, when using a ternary (meth)acrylate copolymer of 2-ethylhexyl acrylate (2-EHA), 2-hydroxyethyl acrylate (2-HEA), and methacrylic acid (MAA) as the base polymer (BP) for the aforementioned binary or higher (meth)acrylate copolymers, for each monomer component, it is preferable to include 2-ethylhexyl acrylate (2-EHA) in the range of 66 to 90 parts by mass, 2-hydroxyethyl acrylate (2-HEA) in the range of 9.8 to 31 parts by mass, and methacrylic acid (MAA) in the range of 0.2 to 3 parts by mass, in order to make the total amount of copolymer monomer components 100 parts by mass.

[0124] Furthermore, the glass transition temperature (Tg) of the aforementioned binary or higher (meth)acrylate copolymer base polymer (BP) is not particularly limited as long as it falls within a range that does not impair the effects of the present invention. From the viewpoints of the adhesion between the intermediate layer 2 and the active energy ray-cured adhesive layer 3, the control of adhesion force before and after irradiation with active energy rays for workpiece processing, and the processing quality of the workpiece, a range of -65°C to -50°C is preferred. Here, the glass transition temperature (Tg) is a theoretical value calculated using the Fox formula based on the composition of the monomer components constituting the aforementioned binary or higher (meth)acrylate copolymer base polymer (BP).

[0125] If the glass transition temperature (Tg) is within the aforementioned range, for example, when cutting a brittle and easily cracked workpiece such as a glass substrate 30 with a rotating cutting scraper 40, the workpiece on the adhesive layer 3 can be firmly fixed, thus suppressing chip positional shift and chip scattering. Furthermore, since the adhesion between the intermediate layer 2 and the adhesive layer 3 is improved, it is possible to suppress paste residue on the ring frame 20 and the transfer of the adhesive layer 3 when peeling the workpiece processing adhesive tape 10 from the ring frame 20 after cutting. Moreover, for example, when grinding the semiconductor wafer 50, it is possible to appropriately follow the height differences of the circuits 51, electrodes, etc., on the surface of the semiconductor wafer 50, thus suppressing paste residue on the periphery of the circuit surface and the transfer of the adhesive layer 3 to the thin-film semiconductor wafer 50' when peeling the workpiece processing adhesive tape 10 from the thin-film semiconductor wafer 50'.

[0126] [A (meth)acrylate copolymer (A2) with photosensitive carbon-carbon double bonds introduced into its side chain]

[0127] As described above, the (meth)acrylate copolymer (A2) with photosensitive carbon-carbon double bonds introduced into its side chain can be obtained by reacting the functional groups introduced into the side chain of the (meth)acrylate copolymer base polymer (BP) through copolymerization of the aforementioned functional group-containing monomers with a compound having a functional group capable of undergoing an addition reaction with that functional group and a carbon-carbon double bond (an active energy-reactive compound). Examples of such active energy-reactive compounds include, for instance, compounds having isocyanate groups and carbon-carbon double bonds, compounds having carboxyl groups and carbon-carbon double bonds, compounds having glycidyl groups and carbon-carbon double bonds, and compounds having amino groups and carbon-carbon double bonds. These radiation-reactive compounds can be used alone or in multiples.

[0128] Specific examples of the above addition reaction include the following methods: (1) using a monomer containing a hydroxyl group as the monomeric component containing a functional group of the above-mentioned binary or higher (meth)acrylate copolymer base polymer (BP), and causing the hydroxyl group to undergo an addition reaction with the isocyanate group of a compound having an isocyanate group and a carbon-carbon double bond (an active energy ray reactive compound); (2) using a monomer containing a carboxyl group as the monomeric component containing a functional group of the above-mentioned base polymer (BP), and causing the carboxyl group to undergo an addition reaction with a compound having a glycidyl group and a carbon-carbon double bond (an active energy ray reactive compound). (2) A method for adding glycidyl groups to the basic polymer (BP) of the above-mentioned polymer; (3) A method for adding glycidyl groups to the carboxyl groups of a compound having carboxyl groups and carbon-carbon double bonds (active energy ray reactive compounds) by using a monomer containing glycidyl groups as a monomer containing functional groups of the basic polymer (BP); (4) A method for adding amino groups to the isocyanate groups of a compound having isocyanate groups and carbon-carbon double bonds (active energy ray reactive compounds), etc.

[0129] In the above-mentioned addition reaction, from the viewpoint of ease of tracking the reaction (stability of control) and ease of technology, the most suitable method is to use a monomer containing a hydroxyl group as the monomer component containing a functional group of the above-mentioned binary or higher (meth)acrylate copolymer base polymer (BP), and to carry out an addition reaction between the hydroxyl group and the isocyanate group of a compound having an isocyanate group and a carbon-carbon double bond (an active energy ray reactive compound). Examples of such compounds having an isocyanate group and a carbon-carbon double bond (active energy ray reactive compounds) include, for example, isocyanate compounds having a (meth)acryloyloxy group. Specifically, examples include 2-methacryloyloxyethyl isocyanate, 4-methacryloyloxy n-butyl isocyanate, 2-acryloyloxyethyl isocyanate, and m-isopropenyl-α,α-dimethylbenzyl isocyanate. Among these, from the viewpoint of versatility, 2-methacryloyloxyethyl isocyanate is preferred.

[0130] In the above addition reaction, a polymerization inhibitor is preferably used to maintain the reactive energy of the carbon-carbon double bond. As such a polymerization inhibitor, a quinone-based inhibitor such as hydroquinone-monomethyl ether is preferred. The amount of the polymerization inhibitor is not particularly limited, but is generally preferred to be between 0.01 and 0.1 parts by mass relative to 100 parts by mass of the binary or higher (meth)acrylate copolymer base polymer (BP).

[0131] During the above addition reaction, (1) in order to further increase the molecular weight by crosslinking with the functional groups of the above (meth)acrylate copolymer (A2) as reaction sites through the subsequently added crosslinking agent, and (2) in order to improve the initial adhesion between the active energy ray-cured adhesive layer 3 after the crosslinking reaction and the workpiece, that is, the adhesion of the workpiece processing adhesive tape 10 to the workpiece before active energy ray irradiation, it is preferable that functional groups remain in the adhesive composition after the crosslinking reaction. In addition, on the other hand, in order to ensure that the adhesive layer 3 cures and shrinks after workpiece processing and the adhesion is sufficiently reduced when the workpiece processing adhesive tape 10 is irradiated with active energy rays, making it easy to peel off from the workpiece, it is also necessary to introduce photosensitive carbon-carbon double bonds into the above-mentioned binary or higher (meth)acrylate copolymer base polymer (BP) in a manner that is within an appropriate concentration range. Both aspects need to be considered. As a result, for example, when an isocyanate compound having a (meth)acryloyloxy group is added to a (meth)acrylate copolymer base polymer (BP) having hydroxyl groups in its side chain, as a standard, the amount of the isocyanate compound having the (meth)acryloyloxy group relative to the total amount of hydroxyl-containing monomer components that are monomer components of the copolymer (BP) is preferably used in an amount ranging from 22 mol% to 99 mol%. More preferably, it is in the range of 40 mol% to 90 mol%, and even more preferably, it is in the range of 50 mol% to 85 mol%.

[0132] The (meth)acrylate copolymer (A2) of this embodiment, incorporating photosensitive carbon-carbon double bonds into the side chains of a binary or higher (meth)acrylate copolymer base polymer (BP), is obtained as follows: The above-mentioned 2-ethylhexyl acrylate (2-EHA) monomer, the above-mentioned monomer containing a functional group, and one or more monomers selected from the above-mentioned monomers other than these two monomers as copolymer monomer components are combined in a predetermined amount. The resulting mixture is polymerized to synthesize the base polymer (BP). Then, an active energy ray reactive compound is subjected to an addition reaction in the presence of an organometallic catalyst to obtain the copolymer. Polymerization can also be carried out using any of the following methods: solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, etc. From the viewpoint of improving the cohesiveness of the active energy ray cured adhesive layer 3, the weight-average molecular weight (Mw) of the above-mentioned (meth)acrylate copolymer (A2) is preferably 100,000 or more; from the viewpoint of suitable coating of the adhesive composition solution of the active energy ray cured adhesive layer 3, it is preferably 1,500,000 or less. That is, the aforementioned weight-average molecular weight (Mw) is preferably in the range of 100,000 to 1,500,000, more preferably in the range of 300,000 to 1,000,000. Here, the weight-average molecular weight (Mw) is the weight-average molecular weight converted from standard polystyrene obtained by gel permeation chromatography (GPC).

[0133] Furthermore, the acid value of the aforementioned (meth)acrylate copolymer (A2) is not particularly limited as long as it is within a range that does not impair the effects of the present invention; it can be 0 mg KOH / g. However, from the viewpoint of improving the adhesion between the intermediate layer 2 and the active energy ray-cured adhesive layer 3, and increasing the adhesion of the adhesive tape 10 to the workpiece before active energy ray irradiation, it is preferably 1.2 mg KOH / g or higher. From the viewpoint of decreasing the adhesion of the adhesive tape 10 to the workpiece after active energy ray irradiation, it is preferably 17.8 mg KOH / g or lower. That is, the aforementioned acid value is preferably in the range of 1.2 mg KOH / g or higher and 17.8 mg KOH / g or lower.

[0134] Furthermore, the hydroxyl value of the above-mentioned (meth)acrylate copolymer (A2) is not particularly limited as long as it is within the range that does not impair the effect of the present invention. From the viewpoint of improving the adhesion between the intermediate layer 2 and the active energy ray-cured adhesive layer 3, enhancing the cohesiveness of the adhesive layer 3, and controlling the adhesion of the adhesive tape 10 for workpiece processing to the workpiece before and after active energy ray irradiation, it is preferably in the range of 3.5 mg KOH / g or more and 91.7 mg KOH / g or less.

[0135] Furthermore, the carbon-carbon double bond concentration of the aforementioned (meth)acrylate copolymer (A2) (the carbon-carbon double bond equivalent per 1g of the solid component of (meth)acrylate copolymer (A2)) is only required to achieve a sufficient reduction in adhesion in the adhesive layer 3 after irradiation with active energy rays. It varies depending on the amount of active energy irradiation and other usage conditions, and is not a one-size-fits-all situation. However, the carbon-carbon double bond concentration is preferably in the range of 0.59 meq / g to 1.60 meq / g. From the viewpoint of balancing effectiveness and economy, the range of 0.59 meq / g to 1.49 meq / g is more preferred, and the range of 0.59 meq / g to 1.29 meq / g is particularly preferred. When the carbon-carbon double bond concentration is less than 0.59 meq / g, the adhesive strength reduction effect in the adhesive layer 3 after irradiation by active energy rays is reduced. Therefore, there is a concern that peeling the workpiece from the adhesive tape 10 becomes difficult, increasing the risk of workpiece breakage and other defects. On the other hand, when the carbon-carbon double bond concentration exceeds 1.60 meq / g, its effect gradually saturates, making it less desirable from an economic point of view. Furthermore, based on the copolymer composition of the (meth)acrylate copolymer (A2), it is prone to gelation during the addition reaction, making synthesis difficult; the adhesion between the intermediate layer 2 and the active energy ray-cured adhesive layer 3 becomes insufficient. Additionally, the carbon-carbon double bond concentration of the (meth)acrylate copolymer (A2) can be determined, for example, by measuring the iodine value of the (meth)acrylate copolymer (A2).

[0136] [Cross-linking agent]

[0137] To increase the molecular weight of the aforementioned (meth)acrylate copolymer (A2) and improve the cohesiveness of the adhesive layer 3, the adhesive composition constituting the active energy ray-curable adhesive layer 3 of this embodiment contains a crosslinking agent capable of reacting with the functional groups present in the (meth)acrylate copolymer (A2). There are no particular limitations on such a crosslinking agent; known crosslinking agents having functional groups capable of reacting with the aforementioned (meth)acrylate copolymer (A2), typically hydroxyl groups, or carboxyl groups introduced as needed, can be used. Specifically, examples include, for instance, polyisocyanate-based crosslinking agents, epoxy-based crosslinking agents, metal chelate-based crosslinking agents, aziridine-based crosslinking agents, melamine resin-based crosslinking agents, urea resin-based crosslinking agents, anhydride compound-based crosslinking agents, polyamine-based crosslinking agents, and polymer-based crosslinking agents containing carboxyl groups. Among these, from the viewpoint of reactivity and versatility, polyisocyanate-based crosslinking agents, epoxy-based crosslinking agents, or metal chelate-based crosslinking agents are preferred, with polyisocyanate-based crosslinking agents being more preferred. These crosslinking agents can be used alone or in combination. The amount of crosslinking agent incorporated relative to 100 parts by weight of the solid content of the above-mentioned (meth)acrylate copolymer (A2) is preferably in the range of 0.01 parts by weight to 10.0 parts by weight, more preferably in the range of 0.1 parts by weight to 5.0 parts by weight, and particularly preferably in the range of 0.2 parts by weight to 1.0 parts by weight.

[0138] As the aforementioned polyisocyanate-based crosslinking agent and epoxy-based crosslinking agent, examples can be made of the same crosslinking agents exemplified above as the crosslinking agent for intermediate layer 2. Furthermore, as a metal chelate-based crosslinking agent, a crosslinking agent capable of crosslinking hydroxyl groups is preferred; specifically, examples include titanium chelates with Ti as the central metal and zirconium chelates with Zr as the central metal.

[0139] Among the aforementioned crosslinking agents, polyisocyanate-based crosslinking agents such as polyisocyanate compounds having isocyanurate rings, adduct polyisocyanate compounds formed by reacting trimethylolpropane with hexamethylene diisocyanate, and adduct polyisocyanate compounds formed by reacting trimethylolpropane with toluene diisocyanate are suitable.

[0140] In this embodiment, for example, when using a binary or higher (meth)acrylate copolymer containing 2-ethylhexyl acrylate (2-EHA) and 2-hydroxyethyl acrylate (2-HEA) as copolymer monomers as the base polymer of the (meth)acrylate copolymer (A2), and using the above-mentioned polyisocyanate-based crosslinking agent as the crosslinking agent, the equivalent ratio (NCO / OH) of the isocyanate group (NCO) of the polyisocyanate-based crosslinking agent and the hydroxyl group (OH) of the (meth)acrylate copolymer (A2) with photosensitive carbon-carbon double bonds introduced into the side chain in the adhesive composition excluding the photopolymerization initiator described later is not particularly limited as long as it is within a range that does not impair the effect of the present invention. From the viewpoints of the cohesiveness of the adhesive layer 3, the adhesion between the intermediate layer 2 and the active energy ray-cured adhesive layer 3, and the control of adhesion, it is preferably in the range of 0.005 to 0.338. Furthermore, from the same point of view, the residual hydroxyl concentration in the adhesive composition as a whole (excluding the photopolymerization initiator) after the crosslinking reaction using the polyisocyanate-based crosslinking agent is preferably in the range of 0.04 mmol / g to 1.62 mmol / g, and the carbon-carbon double bond concentration is preferably in the range of 0.58 meq / g to 1.48 meq / g.

[0141] [Photopolymerization initiator]

[0142] The adhesive composition constituting the active energy ray-curable adhesive layer 3 of this embodiment includes a photopolymerization initiator that generates free radicals upon irradiation by active energy rays. The photopolymerization initiator senses the irradiation of the active energy ray by the adhesive composition constituting the active energy ray-curable adhesive layer 3 and generates free radicals, initiating a crosslinking reaction that introduces photosensitive carbon-carbon double bonds into the side chains of the (meth)acrylate copolymer (A2).

[0143] There are no particular limitations on the photopolymerization initiator used, and conventionally known initiators can be used. Examples include alkyl phenyl ketone-based free radical polymerization initiators, acylphosphine oxide-based free radical polymerization initiators, and oxime ester-based free radical polymerization initiators. Examples of alkyl phenyl ketone-based free radical polymerization initiators include benzyl methyl ketal-based free radical polymerization initiators, α-hydroxyalkyl phenyl ketone-based free radical polymerization initiators, and aminoalkyl phenyl ketone-based free radical polymerization initiators. Specifically, examples of benzyl methyl ketal-based free radical polymerization initiators include 2,2'-dimethoxy-1,2-diphenylethane-1-one (e.g., trade name Omnirad 651, manufactured by IGM Resins BV). As free radical polymerization initiators for α-hydroxyalkyl phenyl ketones, examples include, for instance, 2-hydroxy-2-methyl-1-phenylpropane-1-one (trade name: Omnirad 1173, manufactured by IGM Resins BV), 1-hydroxycyclohexylphenyl ketone (trade name: Omnirad 184, manufactured by IGM Resins BV), 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propane-1-one (trade name: Omnirad 2959, manufactured by IGM Resins BV), and 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropanoyl)benzyl]phenyl}-2-methylpropane-1-one (trade name: Omnirad 127, manufactured by IGM Resins BV), etc. As free radical polymerization initiators for aminoalkyl phenyl ketones, examples include, for instance, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropane-1-one (trade name Omnirad 907, manufactured by IGM Resins BV) or 2-benzylmethyl 2-dimethylamino-1-(4-morpholinophenyl)-1-butanone (trade name Omnirad 369, manufactured by IGM Resins BV). Examples of acylphosphine oxide-based free radical polymerization initiators include, specifically, 2,4,6-trimethylbenzoyl diphenylphosphine oxide (trade name Omnirad TPO, manufactured by IGM Resins BV) and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (trade name Omnirad 819, manufactured by IGM Resins BV). Examples of oxime ester-based free radical polymerization initiators include (2E)-2-(benzoyloxyimino)-1-[4-(phenylthio)phenyl]octane-1-one (trade name Omnirad OXE-01, manufactured by IGM Resins B.V.). These photopolymerization initiators can be used alone or in combination of two or more.

[0144] The amount of photopolymerization initiator added is preferably between 0.1 and 10.0 parts by mass relative to 100 parts by mass of the solid content of the (meth)acrylate copolymer (A2) with photosensitive carbon-carbon double bonds introduced into its side chains. When the amount of photopolymerization initiator added is less than 0.1 parts by mass, the photoreactivity with active energy rays is insufficient. Therefore, even when irradiated with active energy rays, the photoradical crosslinking reaction of the (meth)acrylate copolymer (A2) does not proceed sufficiently. As a result, the adhesive strength reduction effect in the adhesive layer 3 after irradiation with active energy rays is reduced, making peeling from the workpiece difficult and increasing the risk of workpiece breakage and other defects. On the other hand, when the amount of photopolymerization initiator added exceeds 10.0 parts by mass, its effect saturates, which is also undesirable from an economic point of view. Furthermore, depending on the type of photopolymerization initiator, the adhesive layer 3 may sometimes yellow and become aesthetically unappealing.

[0145] In addition, compounds such as dimethylaminoethyl methacrylate and isoamyl 4-dimethylaminobenzoate can be added to the above adhesive composition as sensitizers for such photopolymerization initiators.

[0146] [other]

[0147] The adhesive composition constituting the active energy ray curable adhesive layer 3 of this embodiment may, without impairing the effects of the present invention, also contain additives such as multifunctional acrylic monomers, multifunctional acrylic oligomers, tackifiers, fillers, anti-aging agents, colorants, flame retardants, antistatic agents, surfactants, silane coupling agents, and leveling agents as needed.

[0148] [thickness]

[0149] The thickness of the aforementioned active energy ray-cured adhesive layer 3 is not particularly limited as long as it does not impair the effects of the present invention. It can be appropriately adjusted according to the processing of the workpiece. From the viewpoint of improving the adhesion between the intermediate layer 2 and the adhesive layer 3, increasing the adhesion of the adhesive tape 10 to the workpiece before active energy ray irradiation, and decreasing the adhesion after active energy ray irradiation, it is preferable to have a thickness of 5 μm or more. From the viewpoint of proper application and drying of the adhesive composition solution of the adhesive layer 3, and economic efficiency, it is preferable to have a thickness of 150 μm or less. That is, the thickness of the aforementioned adhesive layer 3 is preferably in the range of 5 μm or more and 150 μm or less, and more preferably in the range of 8 μm or more and 50 μm or less.

[0150] (Adhesive tape for workpiece machining)

[0151] The adhesive tape 10 for workpiece processing in this embodiment has a structure comprising a substrate film 1 formed of a polyester resin composition, an intermediate layer 2, and an active energy radiation-curable adhesive layer 3. Typically, a release liner is provided on the side of the adhesive layer 3 opposite to the side in contact with the intermediate layer 2. The release liner is not particularly limited and can be, for example, synthetic resins such as polyethylene, polypropylene, and polyethylene terephthalate; or paper. Furthermore, to improve the peelability of the adhesive layer 3, a release treatment using a silicone-based release agent, a long-chain alkyl-based release agent, or a fluorinated release agent can be applied to the surface of the release liner. The thickness of the release liner is not particularly limited, and release liners in the range of 10 μm to 200 μm are suitable.

[0152] The manufacturing method of the adhesive tape 10 for the above-mentioned workpiece processing is not particularly limited, and for example, it can be manufactured using the following method. First, a substrate film 1 formed of a polyester resin composition is prepared. Next, a solution of the resin composition for the intermediate layer 2, which is the forming material of the intermediate layer 2, is prepared. The solution of the resin composition can be prepared, for example, by uniformly mixing and stirring (meth)acrylate copolymer (A1), a crosslinking agent, and a diluent, which are components of the intermediate layer 2. As the solvent, a common organic solvent such as toluene or ethyl acetate can be used.

[0153] Next, using a solution of the resin composition for the intermediate layer 2, the solution is coated onto the substrate film 1 and dried to form an intermediate layer 2 of a predetermined thickness. The coating method is not particularly limited; for example, a die coater, a corner roller coater (registered trademark), a gravure coater, a roller coater, or a reverse coater can be used. Furthermore, the drying conditions are not particularly limited; for example, a drying temperature between 80°C and 150°C and a drying time between 0.5 minutes and 5 minutes are preferred. Next, the release liner side is adhered to the exposed surface of the intermediate layer 2 formed on the substrate film 1.

[0154] Next, prepare to peel off the liner and prepare a solution of the adhesive composition for the adhesive layer 3, which serves as the forming material of the adhesive layer 3. The solution of the adhesive composition can be prepared, for example, by uniformly mixing and stirring the (meth)acrylate copolymer (A2), a crosslinking agent, a photopolymerization initiator, and a diluent, which are components of the adhesive layer 3. Common organic solvents such as toluene and ethyl acetate can be used as solvents.

[0155] Next, using a solution of the adhesive composition for adhesive layer 3, the solution is applied to the release treatment side of the release liner and dried to form an adhesive layer 3 of a predetermined thickness. The application method is not particularly limited, and the same method as for intermediate layer 2 can be used. Furthermore, the drying conditions are not particularly limited, and the same conditions as for intermediate layer 2 can be used. Finally, the exposed surface of the adhesive layer 3 formed on the release treatment side of the release liner is bonded to the surface where the release liner of intermediate layer 2, formed on the previously prepared substrate film 1, to form a laminate.

[0156] Finally, the above-mentioned laminate is aged, for example, at 40°C for 72 hours, to allow the (meth)acrylate copolymer of the intermediate layer 2 and the adhesive layer 3 to react with the crosslinking agent, thereby crosslinking and curing them. Through the above process, it is possible to manufacture a workpiece processing adhesive tape 10 on a substrate film 1 formed of a polyester resin composition, which sequentially comprises an intermediate layer 2, an active energy radiation-curable adhesive layer 3, and a release liner from the substrate film side. In addition, the intermediate layer 2 and the adhesive layer 3 can be aged separately and then bonded together to form a laminate. Furthermore, in this invention, the laminate with a release liner on the adhesive layer 3 is also processed as the workpiece processing adhesive tape 10.

[0157] Other methods for manufacturing the adhesive tape 10 for workpiece processing described above include the following: First, a substrate film 1 formed from a polyester resin composition is prepared. Next, solutions of resin compositions for intermediate layer 2 (as forming material of intermediate layer 2) and adhesive compositions for adhesive layer 3 (as forming material of adhesive layer 3) are prepared. Then, using a die coater with two outlets, the solutions are simultaneously extruded onto the substrate film 1 in a wet-on-wet coating manner, starting from the substrate film side and following the order of intermediate layer 2 and adhesive layer 3, to form intermediate layer 2 and adhesive layer 3 of a predetermined thickness. Furthermore, a laminate is formed by attaching the exposed surface of the adhesive layer 3 to the release treatment surface of the release liner.

[0158] Finally, by aging the above-mentioned laminate at, for example, 40°C for 72 hours, the (meth)acrylate copolymer of the intermediate layer 2 and the adhesive layer 3 is reacted with a crosslinking agent, thereby crosslinking and curing them. Through the above process, it is possible to manufacture a workpiece processing adhesive tape 10, which consists of an intermediate layer 2, an active energy radiation-curable adhesive layer 3, and a release liner, sequentially from the substrate film side on a substrate film 1 formed of a polyester resin composition.

[0159] In the aforementioned adhesive tape 10 for workpiece processing, the total thickness of the intermediate layer 2 and the active energy ray-curable adhesive layer 3 is not particularly limited as long as it does not impair the effect of the present invention. It can be appropriately adjusted according to the workpiece processing requirements. For example, a thickness of 10 μm to 300 μm is preferred, and a thickness of 13 μm to 150 μm is more preferred. More specifically, for example, when cutting brittle workpieces such as glass substrates 30 or hard workpieces such as sapphire glass substrates, the total thickness is preferably in the range of 13 μm to 40 μm. Furthermore, for example, when grinding semiconductor wafers with circuits formed on their surfaces, the total thickness is preferably in the range of 20 μm to 135 μm.

[0160] The aforementioned adhesive tape 10 for workpiece processing needs to have a high initial adhesion that allows it to firmly hold and fix the workpiece on the active energy ray-curable adhesive layer 3 in a way that prevents the workpiece from moving during workpiece processing. On the other hand, after the predetermined processing is completed, the active energy ray-curable adhesive layer 3 needs to be cured and shrunk by irradiation with active energy rays in a way that allows the processed workpiece to be easily peeled off from the adhesive tape 10, thereby significantly reducing its adhesion.

[0161] Examples of active energy rays include ultraviolet light, visible light, infrared light, electron beams, beta rays, and gamma rays. Among these active energy rays, ultraviolet (UV) and electron beams (EB) are preferred, with ultraviolet (UV) being particularly preferred. The light source for irradiating the aforementioned ultraviolet (UV) is not particularly limited, and can include, for example, black light lamps, ultraviolet fluorescent lamps, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, carbon arc lamps, metal halide lamps, xenon lamps, etc. Furthermore, ArF stimulated excimer lasers, KrF stimulated excimer lasers, stimulated excimer lamps, or synchrotron radiation can also be used. The irradiation intensity of the aforementioned ultraviolet (UV) is not particularly limited; for example, 100 mJ / cm² is preferred. 2 Above 2,000 mJ / cm 2 The following range is more preferably 300 mJ / cm 2 Above 1,000 mJ / cm 2 The following range.

[0162] The adhesion (initial adhesion) of the adhesive tape 10 for workpiece processing to the glass plate before ultraviolet irradiation is preferably in the range of 5.0 N / 25 mm to 25.0 N / 25 mm, more preferably in the range of 10.0 N / 25 mm to 20.0 N / 25 mm. When the adhesion to the glass plate before ultraviolet irradiation is less than 5.0 N / 25 mm, for example, when cutting the glass substrate 30, it becomes difficult to hold and fix the glass substrate 30 well to the adhesive layer 3 of the adhesive tape 10 for workpiece processing. Therefore, there is concern that the scattering and positional displacement of the glass chip 30a cannot be sufficiently suppressed, and that damage to the glass chip 30a caused by positional displacement may occur. On the other hand, when the adhesion to the glass plate before ultraviolet irradiation exceeds 25.0 N / 25 mm, the glass chip 30a is held excessively firmly to the adhesive layer 3. Therefore, there is concern that the adhesion of the adhesive tape 10 for workpiece processing after ultraviolet irradiation is not sufficiently reduced, and the glass chip 30a cannot be picked up well.

[0163] Furthermore, the adhesion of the adhesive tape 10 for workpiece processing to the glass plate after ultraviolet irradiation is preferably in the range of 0.01 N / 25 mm to 0.5 N / 25 mm, more preferably in the range of 0.02 N / 25 mm to 0.25 N / 25 mm. When the adhesion of the adhesive tape 10 for workpiece processing to the glass plate after ultraviolet irradiation is less than 0.01 N / 25 mm, for example, during the stage from cutting the glass substrate 30 until picking up the glass chip 30a from the adhesive tape 10, the glass chip 30a may unintentionally peel off from the adhesive tape 10 or shift, thus raising concerns about poor pick-up. On the other hand, when the adhesion of the adhesive tape 10 to the glass plate after ultraviolet irradiation exceeds 0.5 N / 25 mm, for example, when picking up the glass chip 30a individually, the reduction in adhesion is insufficient, thus raising concerns about breakage of the glass chip 30a and poor pick-up. Furthermore, even if pick-up is possible, there is a concern about residue buildup.

[0164] Furthermore, the adhesion in this invention is defined as the adhesion (N / 25mm) obtained by the 180° peel method according to JIS Z0237:2009, and the details of the measurement method are described in the test method section below. In addition, the adhesion after ultraviolet irradiation is measured from the substrate film 1 side of the adhesive tape 10 for workpiece processing, using a high-pressure mercury lamp as the light source, with an irradiation intensity of 75mW / cm. 2 The cumulative light intensity reached 300 mJ / cm². 2 The adhesive force was measured by irradiating the object with ultraviolet (UV) light with a center wavelength of 365 nm.

[0165] Furthermore, the adhesion (initial adhesion) of the aforementioned workpiece processing adhesive tape 10 to the stainless steel sheet (SUS304BA sheet) before ultraviolet irradiation is preferably in the range of 5.0 N / 25 mm to 25.0 N / 25 mm, more preferably in the range of 10.0 N / 25 mm to 20.0 N / 25 mm. When the adhesion to the aforementioned stainless steel sheet (SUS304BA sheet) before ultraviolet irradiation is less than 5.0 N / 25 mm, for example, when cutting the glass substrate 30, there is a concern that the adhesive tape 10 may peel off or shift from the SUS-made ring frame 20 due to its inability to withstand the load and water pressure of the cutting scraper 40 and washing water. Additionally, for example, when grinding the semiconductor wafer 50, there is a concern that grinding water may penetrate to the interface between the semiconductor wafer 50 and the adhesive layer 3. On the other hand, if the adhesion of the aforementioned stainless steel sheet (SUS304BA sheet) before UV irradiation exceeds 25.0 N / 25 mm, for example, during the workpiece cutting process, the SUS-made ring frame 20 is excessively held and fixed to the adhesive layer 3. Therefore, when the unwanted workpiece processing adhesive tape 10 is peeled off from the ring frame after the required process, there is a concern that the adhesive layer 3 may transfer to the SUS-made ring frame. Furthermore, during the semiconductor wafer 50 grinding process, the semiconductor wafer 50 is excessively held and fixed to the adhesive layer 3. Therefore, there is a concern that the adhesion of the workpiece processing adhesive tape 10 is not sufficiently reduced after UV irradiation. When the workpiece processing adhesive tape 10 is peeled off from the thin-film semiconductor wafer 50' after grinding, the adhesive layer 3 may transfer or paste may remain on the surface of the thin-film semiconductor wafer 50'.

[0166] Furthermore, the adhesion of the workpiece processing adhesive tape 10 to the stainless steel sheet (SUS304BA sheet) after ultraviolet irradiation is preferably in the range of 0.01N / 25mm or more and 0.5N / 25mm or less, more preferably in the range of 0.02N / 25mm or more and 0.25N / 25mm or less. When the adhesion of the workpiece processing adhesive tape 10 to the stainless steel sheet (SUS304BA sheet) after ultraviolet irradiation is within the above range, for example, after the semiconductor wafer 50 is polished, when the workpiece processing adhesive tape 10 is peeled off from the thin-film semiconductor wafer 50', the adhesive layer 3 can be removed without leaving any residue on the surface of the thin-film semiconductor wafer 50', and the thin-film wafer 50' can be peeled off easily without breaking it.

[0167] As described above, in the workpiece processing adhesive tape 10 according to the present invention, the substrate film 1 formed of a polyester resin composition and the active energy radiation-cured adhesive layer 3 are well bonded by the intermediate layer 2 in either the state before or after active energy radiation irradiation. Therefore, even when used as a back-side grinding tape for extremely thinning semiconductor wafers, the active energy radiation-cured adhesive layer can be peeled off without being transferred to the semiconductor wafer during peeling. Furthermore, even when used as a cutting tape for cutting brittle workpieces such as glass substrates or hard workpieces such as sapphire glass substrates, it will not peel off from the ring frame during the process. When peeling off from the ring frame, peeling can be performed without any adhesive residue, providing not only excellent operability but also excellent workpiece processing quality. The workpiece processing adhesive tape 10 of this embodiment is suitable not only for the aforementioned semiconductor wafers and optical components but also for the processing and transportation of workpieces such as ceramics and other electronic device components.

[0168] Example

[0169] Next, the present invention will be further described in detail using examples and comparative examples. However, the present invention is not limited to the following examples.

[0170] 1. Preparation of the solution of the resin composition for the intermediate layer

[0171] As a solution of resin composition for intermediate layer 2 of adhesive tape 10 for workpiece processing, solutions of resin compositions (A1-a) to (A1-s) respectively containing the following (meth)acrylate copolymers (A1-a') to (A1-s') are prepared.

[0172] First, the copolymer monomer components used to synthesize these (meth)acrylate copolymers (A1) are prepared as follows:

[0173] • Methyl acrylate (MA, molecular weight: 86.04, homopolymer Tg: 10℃);

[0174] • Methacrylic acid (MAA, molecular weight: 86.06; homopolymer Tg: 228℃);

[0175] • Acrylic acid (AA, molecular weight: 72.06; homopolymer Tg: 106℃);

[0176] • 2-Ethylhexyl acrylate (2-EHA, molecular weight: 184.3, homopolymer Tg: -70℃);

[0177] • n-Butyl acrylate (n-BA, molecular weight: 128.17, homopolymer Tg: -54℃);

[0178] Ethyl acrylate (EA, molecular weight: 100.12, homopolymer Tg: -22℃);

[0179] · 2-Hydroxyethyl acrylate (2-HEA, molecular weight: 116.12, homopolymer Tg: -15℃).

[0180] In addition, as a crosslinking agent, a TDI-based polyisocyanate crosslinking agent manufactured by Tosoh Corporation (trade name: CORONATE L-45E, solid content concentration: 45% by mass, isocyanate group content in solution: 8.05% by mass, isocyanate group content in solid content: 17.89% by mass, calculated number of isocyanate groups: average 2.8 per molecule, molecular weight: 656.64) was prepared.

[0181] (Solution of resin composition (A1-a) for the intermediate layer)

[0182] 2-Ethylhexyl acrylate (2-EHA), methyl acrylate (MA), and methacrylic acid (MAA) were prepared as copolymer monomers. These copolymer monomers were mixed in a copolymerization ratio of 2-EHA / MA / MAA = 60 parts by mass / 37 parts by mass / 3 parts by mass (=325.56 mmol / 430.03 mmol / 34.86 mmol). Ethyl acetate was used as the solvent, and azobisisobutyronitrile (AIBN) was used as the initiator. Solution free radical polymerization was used to synthesize a solution of (meth)acrylate copolymer (A1-a') (solids concentration: 35% by mass, weight-average molecular weight Mw: 400,000, solids acid value: 19.6 mg KOH / g). The Tg of the resulting (meth)acrylate copolymer (A1-a') was -42℃ according to the Fox equation.

[0183] Next, relative to 286 parts by mass (100 parts by mass equivalent of solid content) of the (meth)acrylate copolymer (A1-a') solution, a TDI-based polyisocyanate crosslinking agent (trade name: CORONATE L-45E, solid content concentration: 45% by mass) manufactured by Tosoh Corporation was added as a crosslinking agent, diluted with ethyl acetate, and stirred to prepare a solution of resin composition (A1-a) for intermediate layer 2 with a solid content concentration of 30% by mass.

[0184] (A solution of resin composition (A1-b) to (A1-s) for the intermediate layer)

[0185] Relative to the (meth)acrylate copolymer (A1-a'), solutions of (meth)acrylate copolymers (A1-b') to (A1-s') were synthesized by appropriately varying the copolymerization ratio and copolymer monomer composition as shown in Tables 1-4 and 9, respectively, while following the same procedure. The glass transition temperature (Tg), weight-average molecular weight (Mw), solids component acid value, and solids component hydroxyl value of the synthesized (meth)acrylate copolymers (A1-b') to (A1-s') are shown in Tables 1-4 and 9, respectively. Next, using these (meth)acrylate copolymer solutions, relative to 286 parts by mass (100 parts by mass equivalent of solid content) of each of the (meth)acrylate copolymer (A1-b') to (A1-s') solutions, a TDI-based polyisocyanate crosslinking agent (trade name: CORONATE L-45E, solid content concentration: 45% by mass) manufactured by Tosoh Corporation was added as a crosslinking agent, diluted with ethyl acetate, and stirred to prepare a solution of resin composition (A1-b) to (A1-s) for intermediate layer 2 with a solid content concentration of 30% by mass.

[0186] 2. Preparation of solutions for adhesive compositions

[0187] As an adhesive composition for an active energy ray-curable adhesive layer 3 of an adhesive tape 10 for workpiece processing, adhesive compositions (A2-a) to (A2-j) are synthesized, each containing a (meth)acrylate copolymer (A2-a') to (A2-j') with photosensitive carbon-carbon double bonds introduced into the side chain of a (meth)acrylate copolymer base polymer (BP) in which 2-ethylhexyl acrylate (2-EHA) is the main copolymer monomer.

[0188] First, the copolymer monomer components used to synthesize these (meth)acrylate copolymer base polymers (BPs) with 2-ethylhexyl acrylate (2-EHA) as the main copolymer monomer are prepared as follows:

[0189] Methyl methacrylate (MMA, molecular weight: 100.12, homopolymer Tg: 105℃);

[0190] • n-Butyl acrylate (n-BA, molecular weight: 128.17, homopolymer Tg: -54℃);

[0191] • 2-Ethylhexyl acrylate (2-EHA, molecular weight: 184.3, Tg: -70℃);

[0192] • 2-Hydroxyethyl acrylate (2-HEA, molecular weight: 116.12, Tg: -15℃);

[0193] • Methacrylic acid (MAA, molecular weight: 86.06, Tg: 228℃).

[0194] In addition, as a crosslinking agent, a TDI-based polyisocyanate crosslinking agent manufactured by Tosoh Corporation (trade name: CORONATE L-45E, solid content concentration: 45% by mass, isocyanate group content in solution: 8.05% by mass, isocyanate group content in solid content: 17.89% by mass, calculated number of isocyanate groups: average 2.8 per molecule, molecular weight: 656.64) was prepared.

[0195] (A solution of adhesive composition (A2-a) for use in active energy ray-cured adhesive layers)

[0196] As copolymer monomer components, 2-ethylhexyl acrylate (2-EHA), 2-hydroxyethyl acrylate (2-HEA), and methacrylic acid (MAA) were prepared. These comonomer components were mixed in a copolymerization ratio of 2-EHA / 2-HEA / MAA = 79.0 parts by mass / 20.0 parts by mass / 1.0 parts by mass (= 428.65 mmol / 172.24 mmol / 11.62 mmol). Ethyl acetate was used as the solvent, and azobisisobutyronitrile (AIBN) was used as the initiator. Solution free radical polymerization was used to synthesize a solution of a (meth)acrylate copolymer base polymer (BP-a) with 2-ethylhexyl acrylate (2-EHA) as the main copolymer monomer component. The Tg of the resulting (meth)acrylate copolymer base polymer (BP-a) calculated using the Fox equation was -60 °C.

[0197] Next, relative to 100 parts by mass of the solid component of the (meth)acrylate copolymer base polymer (BP-a), as an active energy ray reactive compound manufactured by Showa Denko Corporation, ethyl 2-isocyanate of methacrylate (trade name: Karenz) manufactured by Showa Denko Corporation, having an isocyanate group and an active energy ray reactive carbon-carbon double bond, was used in combination. 16.0 parts by weight (103.13 mmol: 59.9 mol% relative to the total moles of 2-HEA) of an isocyanate group (MOI, molecular weight: 155.15, isocyanate group: 1 / molecule, double bond group: 1 / molecule) were reacted with a portion of the hydroxyl groups of 2-HEA to synthesize a solution of a (meth)acrylate copolymer (A2-a') with photosensitive carbon-carbon double bonds introduced into the side chain (solids concentration: 33% by weight, weight-average molecular weight Mw: 800,000, hydroxyl value of solids: 33.4 mgKOH / g, acid value of solids: 5.6 mgKOH / g, carbon-carbon double bond content: 0.89 mmol / g). Additionally, 0.05 parts by weight of hydroquinone monomethyl ether was used as a polymerization inhibitor to maintain the reactivity of the carbon-carbon double bonds in the above reaction.

[0198] Next, relative to 303 parts by mass (100 parts by mass equivalent of solid content) of the solution of the (meth)acrylate copolymer (A2-a') with photosensitive carbon-carbon double bonds in the side chain synthesized above, an acylphosphine oxide photopolymerization initiator (trade name: Omnirad 819) manufactured by IGM Resins BV was mixed at a ratio of 1.52 parts by mass, and a TDI-based polyisocyanate crosslinking agent (trade name: CORONATE L-45E, solid content concentration: 45% by mass) manufactured by Tosoh Corporation was mixed at a ratio of 0.45 parts by mass (0.20 parts by mass equivalent of solid content, 0.30 mmol) as a crosslinking agent. The mixture was diluted with ethyl acetate and stirred to prepare a solution of adhesive composition (A2-a) for adhesive layer 3 with a solid content concentration of 30% by mass. In the adhesive composition (A2-a) excluding the photopolymerization initiator, the equivalent ratio (NCO / OH) of the isocyanate group (NCO) of the polyisocyanate crosslinking agent and the hydroxyl group (OH) of the (meth)acrylate copolymer (A2-a') with photosensitive carbon-carbon double bonds introduced into the side chain is 0.014, the residual hydroxyl concentration is 0.59 mmol / g, and the carbon-carbon double bond content is 0.89 mmol / g.

[0199] (A solution of adhesive compositions (A2-b) to (A2-j) for active energy ray-cured adhesive layers)

[0200] First, solutions of (meth)acrylate copolymer base polymers (BP-b) to (BP-j) were synthesized by appropriately varying the copolymerization ratio and copolymer monomer composition of the copolymer monomers as shown in Tables 4 to 6, respectively, with other procedures performed in the same manner. Next, solutions of (meth)acrylate copolymer base polymers (BP-b) to (BP-j) were synthesized by adjusting the amount of ethyl 2-isocyanate methacrylate (trade name: Karenz MOI), a reactive compound for active energy radiation, as shown in Tables 4 to 6, with addition reactions performed, with other procedures performed in the same manner, resulting in solutions of (meth)acrylate copolymers (A2-b') to (A2-j') with photosensitive carbon-carbon double bonds introduced into the side chains. The glass transition temperature (Tg) of the synthesized (meth)acrylate copolymer base polymers (BP-b) to (BP-j), and the weight-average molecular weight (Mw), solids component hydroxyl value, solids component acid value, and carbon-carbon double bond concentration of the (meth)acrylate copolymers (A2-b') to (A2-j') are shown in Tables 4 to 6. Next, relative to these (meth)acrylate copolymers (A2-b') to (A2-h') with photosensitive carbon-carbon double bonds introduced into the side chains, solutions of adhesive compositions (A2-b) to (A2-j) for adhesive layer 3 with a solids component concentration of 30% by mass were prepared by diluting with ethyl acetate, using an acylphosphine oxide-based photopolymerization initiator (trade name: Omnirad 819) and a polyisocyanate-based crosslinking agent (trade name: CORONATE L-45E) as shown in Tables 4 to 6.

[0201] In addition, the equivalent ratio (NCO / OH) of the isocyanate group (NCO) in the adhesive composition (A2-b) to (A2-j) excluding the photopolymerization initiator and the hydroxyl group (OH) in the (meth)acrylate copolymer (A2-b) to (A2-j) with photosensitive carbon-carbon double bonds introduced into the side chain, the residual hydroxyl concentration and the carbon-carbon double bond concentration are as follows.

[0202] ·(A2-b)

[0203] (NCO / OH): 0.014, residual hydroxyl concentration: 0.59 mmol / g, carbon-carbon double bond concentration: 0.89 meq / g

[0204] ·(A2-c)

[0205] (NCO / OH): 0.024, residual hydroxyl concentration: 0.35 mmol / g, carbon-carbon double bond concentration: 1.07 meq / g

[0206] ·(A2-d)

[0207] (NCO / OH): 0.020, residual hydroxyl concentration: 0.42 mmol / g, carbon-carbon double bond concentration: 1.29 meq / g

[0208] ·(A2-e)

[0209] (NCO / OH): 0.016, residual hydroxyl concentration: 0.52 mmol / g, carbon-carbon double bond concentration: 1.48 meq / g

[0210] ·(A2-f)

[0211] (NCO / OH): 0.047, residual hydroxyl concentration: 0.17 mmol / g, carbon-carbon double bond concentration: 0.58 meq / g

[0212] ·(A2-g)

[0213] (NCO / OH): 0.005, residual hydroxyl concentration: 1.62 mmol / g, carbon-carbon double bond concentration: 0.89 meq / g

[0214] ·(A2-h)

[0215] (NCO / OH): 0.338, residual hydroxyl concentration: 0.04 mmol / g, carbon-carbon double bond concentration: 0.69 meq / g

[0216] ·(A2-i)

[0217] (NCO / OH): 0.015, residual hydroxyl concentration: 1.38 mmol / g, carbon-carbon double bond concentration: 0.88 meq / g

[0218] ·(A2-j)

[0219] (NCO / OH): 0.216, residual hydroxyl concentration: 0.15 mmol / g, carbon-carbon double bond concentration: 0.58 meq / g

[0220] 3. Fabrication of adhesive tape 10 for workpiece machining

[0221] Regarding the adhesive tapes 10(a) to 10(kk) for workpiece processing made from Examples 1 to 31 and Comparative Examples 1 to 6 above, the composition of the substrate film 1, the intermediate layer 2, and the active energy ray curable adhesive layer 3 are shown in Tables 1 to 10.

[0222] (Example 1)

[0223] As the substrate film 1, a solution of the resin composition (A1-a) for the intermediate layer is coated on a polyethylene terephthalate (PET) film (trade name: Emblet#100, thickness: 100μm) manufactured by Unitika Co., Ltd., so that the thickness of the dried intermediate layer 2 is 10μm. The film is heated at 100°C for 3 minutes to dry the solvent and form the intermediate layer 2 on the substrate film 1.

[0224] Next, a solution of the adhesive composition (A2-a) was applied to the release treatment side of a release liner (trade name: NS-38+A, material: polyethylene terephthalate, thickness: 38 μm) manufactured by Nakamoto Packs Co., Ltd., such that the thickness of the dried active energy radiation-curable adhesive layer 3 was 10 μm. After heating at 100°C for 3 minutes to dry the solvent, the solution was adhered to the side of the intermediate layer 2 formed on the substrate film 1 on the active energy radiation-curable adhesive layer 3. Then, the solution was stored at 40°C for 72 hours to crosslink and cure the active energy radiation-curable adhesive layer 3, thus producing an adhesive tape 10(a) for workpiece processing.

[0225] (Examples 2-15)

[0226] The solution of resin composition (A1-a) for intermediate layer 2 was changed to the solution of resin composition (A1-b) to (A1-o) for intermediate layer 2 as shown in Tables 1 to 4. Otherwise, the same procedure was followed as in Example 1 to produce adhesive tapes 10(b) to 10(o) for workpiece processing.

[0227] (Examples 16-24)

[0228] The solutions of adhesive compositions (A2-a) for active energy ray curable adhesive layer 3 were changed to solutions of adhesive compositions (A2-b) to (A2-j) for adhesive composition 3, as shown in Tables 4 to 6. The amount of crosslinking agent in the adhesive composition was changed only for Examples 22 to 24. Otherwise, the operation was the same as in Example 2 to produce adhesive tapes 10(p) to 10(x) for workpiece processing.

[0229] (Examples 25-31)

[0230] The thickness of the intermediate layer 2 and the thickness of the active energy ray-cured adhesive layer 3 are respectively shown in Tables 7 and 8. Otherwise, the same procedure is followed as in Example 2 to produce adhesive tapes 10(y) to 10(ee) for workpiece processing.

[0231] (Comparative Examples 1-4)

[0232] The solution of resin composition (A1-a) for intermediate layer 2 was changed to the solution of resin composition (A1-p) to (A1-s) for intermediate layer 2 as shown in Table 9. Otherwise, the same procedure was followed as in Example 1 to produce adhesive tapes 10(ff) to 10(ii) for workpiece processing.

[0233] (Comparative Example 5)

[0234] Without setting an intermediate layer 2, as shown in Table 10, the same operation as in Example 1 was performed to produce the adhesive tape 10 (jj) for workpiece processing.

[0235] (Comparative Example 6)

[0236] The solution of the resin composition (A1-a) used for intermediate layer 2 was changed to a solution of the following resin composition: 333.3 parts by weight (converted to 100 parts by weight) of an amorphous polyester resin (trade name: Vylon 600, number average molecular weight Mn: 16,000, Tg: 47℃, hydroxyl value: 7 mg KOH / g, acid value: <2 mg KOH / g) manufactured by Toyobo Co., Ltd. was dissolved in methyl ethyl ketone to prepare a solution with a solid content concentration of 30% by weight. Then, at a ratio of 13.3 parts by weight (converted to 10 parts by weight, 15.66 mmol) of HDI-based polyisocyanate crosslinking agent (trade name: CORONATE) manufactured by Tosoh Co., Ltd. was added as a crosslinking agent. HL, solid component concentration: 75% by mass, isocyanate group content in solution: 12.8% by mass, isocyanate group content in solid component: 17.07% by mass, calculated number of isocyanate groups: average 2.6 per molecule, molecular weight: 638.75), the thickness of the intermediate layer 2 was changed to 2 μm, otherwise, as shown in Table 10, the same operation as in Example 1 was performed to produce the adhesive tape 10 (kk) for workpiece processing.

[0237] 4. Evaluation method for adhesive tape 10 used in workpiece machining

[0238] Regarding the adhesive tapes 10(a) to 10(kk) for workpiece processing prepared from Examples 1 to 31 and Comparative Examples 1 to 6 above, the following operations were performed to evaluate the adhesion before and after ultraviolet irradiation, the paste residue on the adhered object, and the adhesion of the active energy ray-cured adhesive layer.

[0239] 4.1 Determination of adhesive force before and after ultraviolet irradiation

[0240] The adhesive tapes 10(a) to 10(kk) for workpiece processing, prepared according to the examples and comparative examples, were cut into strips with a length of 150 mm and a width of 25 mm to prepare test specimens. Furthermore, the MD direction (the coating direction of the intermediate layer 2 and the adhesive layer 3) of the adhesive tape 10 for workpiece processing was set as the length direction of the test specimen, and the direction perpendicular to this direction was set as the width direction of the test specimen. Glass plates and stainless steel plates (SUS304BA plates) were prepared as the substrates. Under an environment of 23°C and 50% humidity, the release liner was peeled from the adhesive tape 10 for workpiece processing, and the exposed adhesive layer 3 was overlapped onto one side of the substrate. A 2 kg roller was used to apply a load for bonding, and the bonding was allowed to proceed for 20 minutes. The length of the bonded portion was set to 80 mm. Then, using a tensile testing machine, the adhesive tape 10 for workpiece processing was peeled off from the adherend at a peeling speed of 300 mm / min and a peeling angle of 180° according to the 180° peel method of JIS Z0237:2009, and the adhesion force (unit: N / 25 mm) was measured. The number of samples used for the test was set to 3, and the average value of the 3 measurements was taken as the adhesion force before ultraviolet (UV) irradiation.

[0241] Furthermore, similarly to the above, the adhesive tape 10 for workpiece processing prepared in the embodiments and comparative examples was bonded to the object to be bonded. After being left for 20 minutes, the adhesive layer 3 was cured by irradiating the substrate film 1 side of the adhesive tape 10 with ultraviolet light (UV) with a center wavelength of 365nm using a high-pressure mercury lamp. The UV irradiation conditions were set to an irradiation intensity of 75mW / cm². 2 Cumulative light intensity: 300 mJ / cm 2 Then, the adhesion (unit: N / 25mm) was measured in the same manner as above, and the average of the three measurements was taken as the adhesion after ultraviolet (UV) irradiation.

[0242] 4.2 Evaluation of Paste Residue

[0243] The surface of the adhered object after the aforementioned adhesion test was visually observed to evaluate the presence or absence of adhesive residue. Regarding the glass plate, the surface after the adhesion test was performed under ultraviolet light was observed. This is an evaluation of adhesive residue on the surface of the glass chip 30a when, hypothetically, the glass chip 30a is picked up from the UV-irradiated workpiece adhesive tape 10 after the glass substrate 30 has been cut.

[0244] Furthermore, regarding the stainless steel sheet (SUS304BA sheet), the surface was observed after the adhesion was measured before and after ultraviolet (UV) irradiation. The former (before UV irradiation) is an evaluation of the paste residue on the surface of the ring frame 20 when the outer edge of the workpiece processing adhesive tape 10 that has not been irradiated by UV is peeled off from the ring frame 20 after the cutting process. The latter (after UV irradiation) is an evaluation of the paste residue on the surface of the semiconductor wafer 50' when the workpiece processing adhesive tape 10 that has been irradiated by UV is peeled off from the thin-film semiconductor wafer 50' after the semiconductor wafer 50 has been polished.

[0245] The above-mentioned paste residue was evaluated according to the following criteria. A score of 0 was considered to indicate that there were no practical problems.

[0246] Evaluation Criteria

[0247] • 〇: No paste residue

[0248] ×: Contains paste residue

[0249] 4.3 Evaluation of the adhesion (cross-cut test) of active energy radiation-cured adhesive layers

[0250] First, the adhesive layer 3 was cured by irradiating the substrate film 1 side of the workpiece processing adhesive tape 10 prepared in the examples and comparative examples with ultraviolet light (UV) with a center wavelength of 365 nm using a high-pressure mercury lamp. The UV irradiation conditions were set to an irradiation intensity of 75 mW / cm². 2 Cumulative light intensity: 300 mJ / cm 2Next, the release liner is peeled off from the adhesive tape 10 used for workpiece processing. Based on the cross-cut method of JIS K 5600-5-6:1999, a grid-like cut is made on the surface of the adhesive layer 3. Ten cuts are made in each direction of the grid pattern, with a cut interval of 1 mm, forming a 100-grid grid. After attaching the film substrate adhesive tape (trade name, NO.626050, manufactured by Maxell Co., Ltd.; 180° peel adhesion for SUS304BA board: 10.8 N / 25 mm) to the formed grid, the number of grids peeled off by the adhesive layer 3 when manually peeled is counted to evaluate the adhesion between the intermediate layer 2 and the active energy radiation-cured adhesive layer 3. Additionally, without the intermediate layer 2, the adhesion between the substrate film 1 and the active energy radiation-cured adhesive layer 3 is evaluated. This evaluation assesses the residue on the surface of the semiconductor wafer 50' when, hypothetically, after the semiconductor wafer 50 has been polished, the adhesive tape 10 for workpiece processing that will be exposed to ultraviolet light is peeled off from the thin-film semiconductor wafer 50' at high speed. That is, if the adhesion is good, there will be no residue on the surface of the thin-film semiconductor wafer 50' even when the adhesive tape 10 for workpiece processing that will be exposed to ultraviolet light is peeled off at high speed.

[0251] Furthermore, in the absence of UV irradiation on the adhesive tape 10 for workpiece processing as described above, i.e., in the state before UV irradiation, the adhesion between the intermediate layer 2 and the active energy ray-curable adhesive layer 3 is evaluated based on the aforementioned cross-cutting method. This evaluation is based on the assumption that after the cutting process, the un-UV-irradiated outer edge of the adhesive tape 10 for workpiece processing is peeled off from the ring frame 20 at high speed. For example, the adhesive tape is forcefully pressed and peeled off from the center of the tape by hand, and the residue on the surface of the ring frame 20 is evaluated. That is, if the adhesion is good, even if the un-UV-irradiated outer edge of the adhesive tape 10 for workpiece processing is peeled off from the ring frame 20 at high speed, there is no residue on the surface of the thin-film semiconductor wafer 50'.

[0252] The above-mentioned fit is evaluated according to the following criteria. A score of 0 indicates that there are no practical problems.

[0253] • 〇: The range where the number of grids peeled off from the adhesive layer is 0 (0 / 100) relative to 100 grids.

[0254] ×: The number of grids from which the adhesive layer has been peeled off relative to 100 grids is in the range of 1 to 100 (1 / 100 to 100 / 100).

[0255] 5. Evaluation Results

[0256] Regarding the adhesive tapes 10(a) to 10(kk) for workpiece processing made from Examples 1 to 31 and Comparative Examples 1 to 6 above, the results of the physical property evaluation are shown in Tables 11 to 20.

[0257] [Table 1]

[0258] Table 1. Composition of Adhesive Tape

[0259]

[0260] [Table 2]

[0261] Table 2 Composition of Adhesive Tape

[0262]

[0263] [Table 3]

[0264] Table 3. Composition of Adhesive Tape

[0265]

[0266] [Table 4]

[0267] Table 4. Composition of Adhesive Tape

[0268]

[0269] [Table 5]

[0270] Table 5 Composition of Adhesive Tape

[0271]

[0272] [Table 6]

[0273] Table 6. Composition of Adhesive Tape

[0274]

[0275] [Table 7]

[0276] Table 7 Composition of Adhesive Tape

[0277]

[0278] [Table 8]

[0279] Table 8. Composition of Adhesive Tape

[0280]

[0281] [Table 9]

[0282] Table 9 Composition of Adhesive Tape

[0283]

[0284] [Table 10]

[0285] Table 10 Composition of Adhesive Tape

[0286]

[0287] [Table 11]

[0288] Table 11 Physical properties of adhesive tape

[0289]

[0290] [Table 12]

[0291] Table 12 Properties of Adhesive Tape

[0292]

[0293] [Table 13]

[0294] Table 13 Properties of Adhesive Tape

[0295]

[0296] [Table 14]

[0297] Table 14 Physical properties of adhesive tape

[0298]

[0299] [Table 15]

[0300] Table 15 Physical properties of adhesive tape

[0301]

[0302] [Table 16]

[0303] Table 16 Physical properties of adhesive tape

[0304]

[0305] [Table 17]

[0306] Table 17 Physical properties of adhesive tape

[0307]

[0308] [Table 18]

[0309] Table 18 Physical properties of adhesive tape

[0310]

[0311] [Table 19]

[0312] Table 19 Properties of Adhesive Tape

[0313]

[0314] [Table 20]

[0315] Table 20 Properties of Adhesive Tape

[0316]

[0317] First, as shown in Tables 11-18, the adhesive tapes 10(a)-10(ee) for workpiece processing in Examples 1-31, which meet the requirements of the present invention, were confirmed to improve the processing quality of workpieces. Even when a film formed of a polyester resin composition was used as the substrate film, ideal results were obtained in the evaluation of any of the following: adhesion before and after ultraviolet irradiation, paste residue on the adhered object, and adhesion of the active energy ray-cured adhesive layer. That is, when the adhesive tape for workpiece processing of the present invention is used as a back-side polishing tape for ultra-thinning semiconductor wafers, it is determined that uniform ultra-thinning can be achieved by polishing the semiconductor wafer. After polishing, when the back-side polishing tape is peeled off, the active energy ray-cured adhesive layer can be peeled off without transferring to the ultra-thinned semiconductor wafer. Furthermore, when used as a cutting strip for high-quality cutting of brittle workpieces such as glass substrates and hard workpieces such as sapphire glass substrates, it is determined that during the cutting process, the cutting strip holding the workpiece does not peel off from the ring frame. In addition, the pick-up performance of the cut chip is also good, and when the cutting strip is peeled off from the ring frame after picking up, it can be peeled off without any paste residue on the ring frame.

[0318] In contrast, as shown in Tables 19 and 20, the adhesive tapes 10(ff) to 10(kk) for workpiece processing of Comparative Examples 1 to 6, which do not meet the requirements of the present invention, are at a level where there are no problems with the adhesion before and after ultraviolet irradiation. However, in any evaluation of the paste residue on the adhered object and the adhesion of the active energy ray-cured adhesive layer, the results are worse than those of the adhesive tapes 10(a) to 10(ee) for workpiece processing of Examples 1 to 31.

[0319] Specifically, in the adhesive tape 10(ff) for workpiece processing of Comparative Example 1 and the adhesive tape 10(gg) for workpiece processing of Comparative Example 2, the content of methyl acrylate (MA), which is the copolymer monomer component of the ternary (meth)acrylate copolymer (A1) as the intermediate layer 2, exceeds the upper limit value of the claims. Therefore, in the evaluation of the adhesion by cross-cut test after ultraviolet irradiation, compared with the adhesive tapes 10(a) to 10(c) for workpiece processing of Examples 1 to 3, a large amount of adhesive layer peeling was confirmed.

[0320] Furthermore, in the workpiece processing adhesive tape 10(hh) of Comparative Example 3 and the workpiece processing adhesive tape 10(ii) of Comparative Example 4, the content of methacrylic acid (MAA), the copolymer monomer component of the ternary (meth)acrylate copolymer (A1) as the intermediate layer 2, was lower than the lower limit of the claims. Therefore, in the evaluation of adhesion by cross-cut test before ultraviolet irradiation, a considerable amount of adhesive layer peeling was confirmed compared with the workpiece processing adhesive tapes 10(c), 10(d), 10(f), and 10(g) of Examples 3, 4, 6, and 7. In addition, in the evaluation of paste residue before ultraviolet irradiation, paste residue was also observed on the surface of the stainless steel plate (SUS304BA plate).

[0321] Furthermore, the adhesive tape 10(jj) for workpiece processing in Comparative Example 5 does not have an intermediate layer 2. Therefore, in the evaluation of the adhesion by cross-cut test before ultraviolet irradiation, the adhesive layer was observed to peel off completely (100 / 100).

[0322] Furthermore, in the adhesive tape 10(kk) for workpiece processing in Comparative Example 6, the intermediate layer 2 used an amorphous polyester resin composition different from that of the present invention. However, in the evaluation of the adhesion by cross-cut test before ultraviolet irradiation, an extremely large amount of adhesive layer peeling was observed.

[0323] Explanation of symbols

[0324] 1…Substrate film

[0325] 2…Intermediate layer

[0326] 3…Active Energy Ray Curing Adhesive Layer

[0327] 10… Adhesive tape for workpiece machining

[0328] 11…cutting strip

[0329] 12… Peeling tape

[0330] 20… ring frame

[0331] 30…glass substrate

[0332] 30a… Glass chip (a monolithically mounted glass substrate)

[0333] 40…cutting scraper

[0334] 50… Semiconductor wafers

[0335] 50'...a thin-film semiconductor wafer

[0336] 51…circuit

[0337] 60… Grinding machine (grinding wheel).

Claims

1. An adhesive tape for workpiece processing, characterized in that, This is an adhesive tape for workpiece processing, comprising a substrate film formed from a polyester resin composition, an intermediate layer, and an active energy radiation-curable adhesive layer. The intermediate layer is formed of a resin composition containing a ternary or higher (meth)acrylate copolymer (A1) comprising methyl acrylate and methacrylic acid as copolymer monomer components, wherein the ternary or higher (meth)acrylate copolymer (A1) comprises 90% by mass or more in the resin composition. When the total amount of copolymer monomer components constituting the ternary or higher (meth)acrylate copolymer (A1) is set as 100 parts by mass, the copolymer monomer components other than the methyl acrylate and the methacrylic acid include methyl acrylate in the range of 37 to 57 parts by mass, the methacrylic acid includes methacrylic acid in the range of 2 to 7 parts by mass, and at least one selected from (meth)acrylate monomers, (meth)acrylate cycloalkyl ester monomers, monomers containing functional groups, vinyl acetate, styrene, acrylonitrile, and N-methylvinylpyrrolidone as copolymer monomer components other than the methyl acrylate and the methacrylic acid in the range of 36 to 61 parts by mass. The active energy ray-curable adhesive layer is formed from an adhesive composition comprising: a (meth)acrylate copolymer (A2) with photosensitive carbon-carbon double bonds introduced into the side chains of a binary or higher (meth)acrylate copolymer base polymer, and a crosslinking agent. The binary or higher (meth)acrylate copolymer base polymer contains 2-ethylhexyl acrylate as a copolymer monomer component in a proportion of more than 50 parts by mass and less than 90 parts by mass, based on 100 parts by mass of the total amount of copolymer monomer components constituting the (meth)acrylate copolymer base polymer.

2. The adhesive tape for workpiece processing according to claim 1, wherein the ternary or higher (meth)acrylate copolymer (A1) is a ternary or higher (meth)acrylate copolymer containing 2-ethylhexyl acrylate as a copolymer monomer component other than methyl acrylate and methacrylic acid.

3. The adhesive tape for workpiece processing according to claim 2, wherein the ternary or higher (meth)acrylate copolymer (A1) is a ternary (meth)acrylate copolymer in which 2-ethylhexyl acrylate, methyl acrylate and methacrylic acid are copolymer monomer components. When the total amount of copolymer monomer components constituting the ternary (meth)acrylate copolymer (A1) is set as 100 parts by mass, the 2-ethylhexyl acrylate is in the range of 36 to 61 parts by mass, the methyl acrylate is in the range of 37 to 57 parts by mass, and the methacrylic acid is in the range of 2 to 7 parts by mass, in order to adjust the total amount of copolymer monomer components to 100 parts by mass.

4. The adhesive tape for workpiece processing according to any one of claims 1 to 3, wherein the glass transition temperature of the ternary or higher (meth)acrylate copolymer (Al) is in the range of -43°C to -18°C.

5. The adhesive tape for workpiece processing according to any one of claims 1 to 3, wherein the binary or higher (meth)acrylate copolymer base polymer is a ternary (meth)acrylate copolymer in which 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, and methacrylic acid are copolymer monomer components, and the total amount of copolymer monomer components constituting the (meth)acrylate copolymer base polymer is set as 100 parts by mass, wherein the 2-ethylhexyl acrylate is in the range of 66 parts by mass to 90 parts by mass, the 2-hydroxyethyl acrylate is in the range of 9.8 parts by mass to 31 parts by mass, and the methacrylic acid is in the range of 0.2 parts by mass to 3 parts by mass, in order to adjust the total amount of copolymer monomer components to 100 parts by mass.

6. The adhesive tape for workpiece processing according to any one of claims 1 to 3, wherein the glass transition temperature of the binary or higher (meth)acrylate copolymer base polymer is in the range of -65°C to -50°C.

7. The adhesive tape for workpiece processing according to any one of claims 1 to 3, wherein the thickness of the intermediate layer is 5 μm or more.

8. The adhesive tape for workpiece processing according to any one of claims 1 to 3, wherein the thickness of the active energy ray curable adhesive layer is 5 μm or more.

9. The adhesive tape for workpiece processing according to any one of claims 1 to 3, wherein the sum of the thickness of the intermediate layer and the thickness of the active energy ray curable adhesive layer is 10 μm or more.

10. The adhesive tape for workpiece processing according to any one of claims 1 to 3, wherein the substrate film formed from the polyester resin composition is a polyethylene terephthalate film.

11. The adhesive tape for workpiece processing according to any one of claims 1 to 3, wherein the adhesive force of the adhesive tape for workpiece processing on the glass plate before ultraviolet irradiation, i.e., the initial adhesive force is in the range of 5.0 N / 25 mm or more and 25.0 N / 25 mm or less, and the adhesive force after ultraviolet irradiation is in the range of 0.01 N / 25 mm or more and 0.50 N / 25 mm or less.

12. The adhesive tape for workpiece processing according to any one of claims 1 to 3, wherein the adhesive force of the adhesive tape for workpiece processing on stainless steel plate, i.e., SUS304BA plate before ultraviolet irradiation, i.e., the initial adhesive force is in the range of 5.0 N / 25 mm or more and 25.0 N / 25 mm or less, and the adhesive force after ultraviolet irradiation is in the range of 0.01 N / 25 mm or more and 0.50 N / 25 mm or less.

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